Faculty Research Interests
Carmela R. Abraham, Ph.D.
Our laboratory studies the mechanisms of normal brain aging and the etiology of Alzheimer’s disease (AD). The 40-42 amino acid amyloid beta peptide (Aß) is the major component of plaques that accumulate in the brains of AD patients. There is ample evidence that Aß causes irreversible neurodegeneration. Therefore, the formation and clearance of Aß are major therapeutic targets for the treatment of AD. Aß is a proteolytic fragment of the amyloid precursor protein (APP), a ubiquitously expressed and conserved protein with unknown function. We are studying the physiologic function of APP and its role in the brain and particularly, in AD. Aß accumulates in the AD brain likely as a result of aberrant clearance. In another project, we study a novel protease involved in the degradation of Aß. Studying the proteases that degrade this peptide is crucial for understanding the etiology of the disease and for the design of therapeutic compounds aimed at decreasing the Aß load in the brain. We also investigate normal human brain aging and use the rhesus monkey as a model. Rhesus monkeys develop cognitive impairment as they age. To our surprise, we could not detect cortical neuronal loss, but extensive changes were observed in the white matter volume and myelin, the insulating layer that surrounds nerve fibers and facilitates communication. We attribute these age-related changes to neuroinflammation. Specifically, we are interested in the expression of gene products that could contribute to the destruction of myelin. The myelin abnormalities may contribute to the cognitive deficits that are seen with normal aging. A gene we are currently focusing on is Klotho, an anti-aging gene that when deleted in mice leads to a premature aging phenotype and when overexpressed results in a 30% lifespan extension and resistance to oxidative stress. We are studying the role of Klotho in myelin formation and repair. To prove our hypotheses we use biochemical and molecular techniques, including microarray analyses, light, fluorescent and confocal microscopy, cell culture and animal models.
Catherine Costello, Ph.D.
The objective of our research is to establish the detailed structures of biopolymers in order to understand their structure-activity relationships as they influence or reflect biological processes related to health, growth and development, and disease. Our particular focus for new method development is on the needs of glycobiology, since carbohydrates and their conjugates (glycoproteins, glycolipids, etc.) are involved in targeting and immune system recognition, nervous system growth and development, infection, parasite response, carcinogenesis, and other critical processes. The techniques for full structural characterization of these complex molecules are much less developed than are methods for linear biopolymers (proteins and oligonucleotides). Our protein studies include determinations of post-translational modifications related to oxidative stress in cardiovascular disease and investigations of protein misfolding disorders. Recent introduction of new mass spectral ionization methods and rapid progress in means for mass separation and detection now make it possible to perform structural studies on low picomole amounts of samples even when they are complex mixtures. In our research program we are refining and extending the tools of mass spectrometry and are applying them to collaborative studies undertaken with colleagues at BUSM and other institutions around and outside the US. Our laboratory includes a Resource Center sponsored by the NIH National Center for Research Resources and the NIH National Heart, Lung and Blood Institute-supported Cardiovascular Proteomics Center.
Matthew D. Layne, Ph.D.
Paul F. Pilch, Ph.D.
Biochemistry and Medicine
Cell biology of adipocyte and skeletal muscle metabolism and function: The modern Western diet coupled with a sedentary lifestyle has led to an epidemic of obesity, a consequence of which is a dramatic rise in the incidence of type II diabetes mellitus, a malfunction in insulin-regulated metabolism. At the cellular level, type II diabetes is characterized by failure of insulin to act in liver, muscle and fat and we study insulin action in the latter two tissues. Insulin resistance in muscle (and fat) derives from the failure of insulin to activate the tissue-specific glucose transporter GLUT4. The activation mechanism for this process involves vesicle trafficking and protein targeting with regard to GLUT4 and the insulin receptor. We are characterizing the formation and protein content of GLUT4-containing vesicles in order to identify the organelles through which they pass on their way to and from the cell surface and we are probing the signaling from the insulin receptor to the GLUT4-containing vesicles as well as the regulation of Glut4 expression. We are also studying the regulation of adipokine formation and secretion, as these molecules are adipocyte-specific cytokines that affect insulin sensitivity in other peripheral tissues.
A characteristic morphological feature of fat and muscle cells is the presence of numerous cell surface (plasma membrane) micro-domains called caveolae. Caveolae are involved in lipid trafficking in adipocytes and other cells, and we have recently shown that they have a complex coat composition and their structure/stability requires their interaction with the cortical cytoskeleton. This interaction is likely to play a role in cell motility related to tumor metastasis. Moreover, lack of caveolae in mice and humans due to functional loss of caveolae protein components causes muscular- and lipo-dystrophies amongst other pathologies. Thus, the broad goal is to study adipocyte and muscle cell biology in order to understand the interplay between their characteristic patterns of gene expression as it related to glucose and fat metabolism, insulin sensitivity and broader cellular functions such as motility and cell surface membrane repair. Understanding these pathways will help us to figure out how they are compromised in pathophysiological states such as diabetes.
Katya Ravid, D.Sc., Ph.D.
Medicine and Biochemistry
The cells of all blood lineages arise from pluripotent hematopoietic stem cells that reside in the marrow. The bone marrow also contains stem cells of other lineages, including fat, vascular etc. Our research is focused on two interrelated projects that bear on mechanisms associated with the development of blood and vascular pathologies: (1) Studies in the lab center on molecular mechanisms involved in cell cycle control during the development of bone marrow megakaryocytes into platelets, a process that includes cellular polyploidization prior to platelet fragmentation. We also identified mechanisms of polyploidy in vascular smooth muscle cells and found that the degree of polyploidy serves as an excellent biomarker for aging; (2) Ongoing studies explore the role of vascular and bone marrow cell (mesenchymal stem cells) adenosine receptors in tissue regeneration. Transgenic and knockout mouse models are used to assist in exploring mechanisms in vivo. For more information visit: http://www.bumc.bu.edu/ravidlab/ Dr. Ravid, along with other faculty, also offer NHLBI-funded training in cardiovascular biology via a training program, which she directs. Details are outlined at:http://www.bumc.bu.edu/cardiograd/
Mohammad H. Zaman, PhD.
Research in our lab is focused at the interface of cell biology, mechanics, systems biology and medicine. We are interested in understanding and decoupling the integrated chemical, biological and mechanical basis of tumor invasion that precedes metastasis. We utilize computational and experimental tools rooted in cell biology, chemistry, mechanics and imaging to ask how cells process external information and use it to develop specific responses in native like 3D environments. Our work is also aimed at developing multi-scale models, integrating both first principle and data driven approaches to quantify cell signaling, adhesion and motion in 3D environments.
The second main thrust of our research is focused on developing computational and experimental tools to improve the quality of life, education and the practice of medicine in the developing world. In this regard, we are working closely with the Center for Global Health and various medical schools and engineering institutions around the globe to develop cheap, robust and easy to use solutions to develop improved diagnostics and tools for data analysis.
Richard A. Cohen, M.D.
The research interests of the Vascular Biology Unit center around the biology and pathophysiology of nitric oxide (NO) in the setting of vascular disease. Areas of study are currently focused on novel signaling mechanisms that rely on ion channels and transporters. These include the regulation of intracellular calcium via NO-dependent inhibition of store-operated calcium influx by its ability to stimulate calcium uptake by sarcoplasmic/endoplasmic reticulum calcium ATPase. Levels of NO and its actions in diseased blood vessels are regulated by oxidants that both destroy NO and introduce post translational modifications of its protein targets. Thus, the calcium ATPase target of NO is inactivated by oxidants in diseased arteries. Levels of oxidants are increased in diseased arteries by endogenous enzymes. In hypertension, superoxide anion production by vascular NADPH oxidase is upregulated, and in diabetes, endothelial nitric oxide synthase becomes partially uncoupled, producing superoxide anion in addition to NO. NO and superoxide react to form peroxynitrite, a potent oxidant. Presence of this oxidant in vascular tissue is evidenced by tyrosine nitration of proteins, including the calcium ATPase and prostacyclin synthase. Inactivation of the latter enzyme leads to vasoconstrictor prostanoids responsible for adhesion molecule expression and apoptosis of endothelial cells. Inhibiting NADPH oxidase, over expression of superoxide dismutase, and antioxidants to prevent oxidative changes in vascular proteins all represent therapeutic interventions being investigated.
Wilson Colucci, M.D.
Dr. Colucci’s laboratory is studying the mechanisms that mediate myocardial remodeling and failure. A major focus is to understand the roles of reactive oxygen species in mediating myocyte phenotype via their effects on cell growth, gene expression and apoptosis. Recently, they have demonstrated that oxidative stress, mechanical deformation and catecholamines can induce both hypertrophic growth and apoptosis in cardiac myocytes. Parallel studies are being performed in vitro and in vivo using cultured cardiac myocytes and genetically-modified mice, respectively in order to determine the relationship between the molecular/cellular events involved in cardiac remodeling and alterations in physiological function that can be assessed at the single myocyte and whole heart level in transgenic and knock-out mice.
Victoria Herrera, M.D.
Our research work focuses on the molecular genetic basis of hypertension and its target organ complications such as increased susceptibility to coronary artery disease and stroke with particular attention to gender-specific issues and fetal basis of these susceptibilities. Work also focuses on the investigation of the role of the dual endothelin-1/angiotensin II receptor (Dear) on cardiac and vascular network development. The investigation of molecular mechanisms underlying hypertension-coronary artery disease interaction involves a) the dissection of pathways involved in vulnerable plaque development and destabilization using an integrated approach spanning histopathology, transcription profiling, biomarker identification and in vivo pathway testing using transgenic rat models, and b) identification of genetic modifiers of hyperlipidemia relevant to gender and genetic background differences through total genome search for putative quantitative trait loci in F2 intercross hybrids. The investigation of the molecular mechanisms underlying hypertension-stroke interaction and dissection of gender-specific issues and fetal basis of adult-onset hemorrhagic stroke involves a) modeling in transgenic rats addressing both gender-specific issues and fetal basis mechanisms, b) investigation of disease course changes in cellular and molecular events in the neurovascular unit, and c) investigation of mechanism-based biomarkers predictive of risk or onset of hemorrhagic stroke. The investigation of the role of a unique dual-ligand receptor, Dear, in cardiac and vascular development involves tissue-specific gene-targeting experiments in mouse models as well as development of in vitro experimental systems, based on initial observations identifying Dear as a key player in cardiac and vascular network formation.
Flora Sam, M.D.
Flora Sam’s NIH funded laboratory is involved in both clinical and basic studies of heart failure.
Research focuses on studying mechanisms of cardiac remodeling in hypertrophy, hypertension and heart failure (systolic and diastolic heart failure). We are currently studying:
- pro-inflammatory and pro-fibrotic mechanisms that mediate cardiac remodeling in heart failure and hypertension.
- the role of aldosterone in mediating the cardiac myocyte phenotype in cardiac remodeling.
- the mechanisms by which adipokines modulate cardiac myocyte remodeling
- crosstalk between cardiac myocytes and adipocytes
We are studying these mechanisms by using cultured cardiac myocytes and fibroblasts (in vitro) and genetically-modified mice (in vivo), to determine the relationship between molecular/cellular events involved in cardiac remodeling and the changes in physiological function that can be assessed at the single cell and whole heart level in genetically-modified mice. We are also investigating factors, which are important in inter-tissue communication in human heart failure and studying the role of matrix markers in human subjects with cardiac amyloid and heart failure.
Kenneth Walsh, Ph.D.
Research in the Walsh laboratory is focused in three areas. The major project investigates the signaling- and transcriptional-regulatory mechanisms that control both normal and pathological tissue growth in the cardiovascular system. Many of these studies involve analyses of the PI3-kinase/Akt/GSK/Forkhead signaling axis. This pathway is of critical importance in the regulation of organ growth and body size. Signaling through this pathway controls cellular enlargement (hypertrophy), cell death (apoptosis), and blood vessel recruitment and growth (angiogenesis). We have shown that the PI3-kinase/Akt/GSK/Forkhead signaling axis regulates multiple steps critical in angiogenesis including endothelial cell apoptosis, differentiation, nitric oxide production and migration. We have also shown that some of these signaling steps are important for cardiac hypertrophy during normal postnatal development, and that they regulate myocyte survival in models of heart disease. The second project investigates the role of the immune system in vascular disease. These studies focus on the Fas/Fas ligand system. Fas is a death receptor that mainly functions to downregulate inflammatory reaction. Aberrations in Fas-mediated apoptosis can contribute to a variety of vascular disorders including atherosclerosis. Current research employs transgenic mouse models to assess the interrelationships between vascular and autoimmune diseases. The third project explores the molecular mechanisms by which amyloid proteins are toxic to cells. The insoluble aggregates of the amyloid proteins A40 and A42 are the predominant components of the inclusion bodies and plaques characteristic of the vessels and neuronal tissues of the Alzheimer’s diseased brain. Cerebral amyloid angiopathy, a disease that affects the brain in half of elderly individuals, is also characterized by amyloid deposition in blood vessels. Our experiments are attempting to elucidate how amyloid proteins induce apoptosis and design strategies to ameliorate the toxicity of amyloid aggregates once they are formed in vascular smooth muscle cells.
Mengwei Zang, M.D., Ph.D.
Vascular Biology Unit
The main goal of Dr. Zang’s laboratory is to investigate the physiological regulation of novel signaling molecules important in energy homeostasis and their impact in diabetes and cardiovascular complications. Better understanding of these molecular mechanisms will provide a great opportunity for the development of novel therapeutic strategies for metabolic syndrome and cardiovascular disease. A major focus is to determine how protein kinases or signal transduction pathways modulate glucose and lipid metabolism in hepatocytes by their effects on phosphorylation, protein-protein interactions and gene expression, and their implication in pathological dysregulation in insulin resistance and diabetes. Recent studies focus on the role of key energy sensors, such as AMP protein kinase (AMPK) and the NAD-dependent deacetylase (SIRT1), in the regulation of cell metabolism and diabetes. These studies have demonstrated that AMPK is required for metformin, one of the most widely prescribed type 2 diabetes drugs in the world, to prevent hepatocyte lipid accumulation caused by high glucose. Importantly, she has identified AMPK activation as a molecular mechanism for the beneficial effects of nature products, such as polyphenols including resveratrol, present in red wine, on hepatic lipid accumulation, hyperlipidemia and atherogenesis in type 1 and type 2 diabetic LDL receptor deficient mice. She and her colleagues have also defined SIRT1 as an upstream effector responsible for activating the LKB1/AMPK signaling pathway that explains the ability of polyphenols to inhibit high glucose-induced hepatocyte lipid accumulation. Our findings point to SIRT1 and AMPK as sharing a common pathway and functional consequence, providing major therapeutic targets for the treatment of diabetes. Parallel studies are being performed using in vitro cultured cell models and in vivo genetically modified mice, to dissect the relationship between the cell signaling and alteration in cell metabolism that can be assessed from molecular and cellular levels that are integrated in diabetic mouse models. Current research is attempting to elucidate how these critical signaling pathways influence disease states, including fatty liver, dyslipidemia, and atherosclerosis in obesity, insulin resistance and type 2 diabetes. The ultimate goal is to provide new insight into the mechanism of insulin resistance and diabetes and to identify potential therapeutic interventions.
ENDOCRINOLOGY, DIABETES, & NUTRITION
Susan K. Fried, Ph.D.
Endocrinology, Diabetes and Nutrition
Obesity, particularly abdominal obesity, confers increased risk for cardiovascular disease, type 2 diabetes, osteoarthritis, stroke and cancer. The long-term goal of research in my laboratory is to understand how fat deposition in different anatomical depots is regulated, and why abdominal obesity is associated with metabolic abnormalities. We are currently engaged in several projects that should shed light on these questions:
Regulation of leptin production: Adipocytes are now recognized as endocrine cells that produce a variety of hormones, including leptin, interleukin-6, and adiponectin. However, very little is known about the mechanisms that regulate the synthesis and secretion of adipose hormones (adipokines). We have focused our attention on leptin, an adipocyte hormone that regulates metabolism and appetite and is centrally involved in the regulation of body weight. Leptin production is increased in proportion to the amount of fat stored in the adipocyte. In addition, serum leptin levels change independent of adiposity, in response to changes in nutritional status. Our recent studies using human adipose tissue placed in organ culture and a rat model indicate that the nutritional regulation of leptin production is regulated, at least in part, by insulin, glucocorticoids, catecholamines and cytokines (Figure 1). Using metabolic labeling and immunopreciptation methods to monitor rates of leptin synthesis, turnover and secretion, we have demonstrated that pre- and post-transcriptional mechanisms are involved. Reporter assays show that elements within the 5’ UTR of leptin stimulates, while the 3’UTR inhibits translation. The insulin stimulation of leptin mRNA translation requires both UTRs. Current studies are investigating the cis elements and transacting factors that mediate the nutritional regulation of leptin mRNA translation.
Depot differences in adipose tissue metabolism: We find significant differences in cytokine production in visceral (omental) adipose tissue. Interestingly, we find these cytokines are expressed mainly in stromal cells, not adipocytes. We are currently studying the hormonal regulation of cytokine production (TNFa, IL6 and 8) in human omental vs subcutaneous adipose tissue, as well as the metabolic effects of these cytokines on adipocyte metabolism and leptin production. https://www.bumc.bu.edu/busm/profile/susan-fried/
Michael F. Holick, M.D., Ph.D.
Endocrinology, Diabetes and Nutrition
Our research focuses on how sunlight provides humans with their vitamin D requirement and explores the multitude of roles that vitamin D has for health. Dr. Holick’s lab has several mouse models that evaluate the importance of vitamin D nutrition as a chemopreventive agent for human prostate and colorectal cancers. His lab is evaluating several novel vitamin D analogues that have the potential for treating colorectal and prostate cancer. Investigations into the mechanism of action as to how vitamin D regulates genes responsible for cellular and proliferation have provided insights into the importance of vitamin D for cancer prevention. A study is underway to evaluate the effect of giving a pharmacologic dose of vitamin D to men with prostate cancer to determine what its impact is on their prostatic specific antigen (PSA) levels as well as quality of life. In addition, a group of men with prostate cancer will be receiving ultraviolet irradiation to determine whether the skin’s production of vitamin D and its photoproducts have any additional benefit for controlling the rise in PSA level and improving quality of life. Studies are underway to better understand how exposure to sunlight affects both human cultured keratinocytes and melanoma cells in culture. The goal is to determine which genes are being regulated by ultraviolet irradiation and how this affects the proliferation and differentiation of the skin cells. Dr. Holick’s laboratory has been investigating the role of parathyroid hormone related peptide (PTHrP) in skin and hair proliferation and differentiation. Studies have shown that PTHrP receptor agonists inhibit skin cell proliferation and induce terminal differentiation and have been effective in treating psoriasis. PTHrP receptor antagonists enhance epidermal and hair follicle keratinocyte proliferation resulting in stimulating in both skin and hair growth. A study is underway to evaluate the potential clinical application for the use of a PTHrP receptor antagonist for mitigating alopecia in women undergoing chemotherapy for breast cancer.
Zhijun Luo, M.D., Ph.D.
Endocrinology, Diabetes and Nutrition
Protein phosphorylation is an important regulatory process that controls almost all cellular programs including cell proliferation, differentiation, survival, apoptosis and metabolism. It is a process in which kinases catalyze the transfer of phosphate from ATP to target proteins at tyrosine, serine or threonine residues, thereby regulating their functions. Mutations of responsible kinases and their activators have been frequently found to associate with unrestrained growth of cancer cells. Thus, our overall research interest is to understand how protein phosphorylation regulates cell metabolism and growth and how its alteration causes functional abnormalities such as malignancy and the metabolic syndrome. Specifically, our current research projects include the following: (1) regulation and function of Raf kinase, an important effector of Ras and an upstream kinase of Erk and (2) regulation of cell metabolism in cancer cells by AMPK.
Sayon Roy, Ph.D.
Endocrinology, Diabetes and Nutrition; Ophthalmology
We are working on projects related to the pathogenesis of diabetic microangiopathy, in particular, vascular complications in diabetic retinopathy and diabetic nephropathy. One of the projects involves applying a novel gene therapeutic strategy to normalize altered gene expression in the retinal capillary cells with the goal of preventing characteristic lesions of diabetic retinopathy. A second project aims at understanding the role of gap junction intercellular communication in the development of retinal vascular lesions associated with cell death in early diabetic retinopathy. In this project we are investigating whether high glucose alters the expression of endothelial specific connexins (Cx37, Cx40, Cx43), and connexin phosphorylation. A third project attempts to unravel the mechanism(s) underlying blood retinal barrier breakdown in diabetic retinopathy. Because tight junction serves as the permeability barrier, we are currently investigating whether the synthesis of occludin and ZO-1, and other endothelial tight junction proteins are altered by high glucose condition in vitro and in retinal capillaries of diabetic rats. A fourth project attempts to identify a biochemical link between the pathogenesis of diabetic retinopathy and diabetic nephropathy in terms of altered ultrastructure and function of the retinal and glomerular capillaries from the perspective of high glucose-induced overexpression of extracellular matrix proteins. A fifth project aims at understanding the role of mitochondrial dysfunction in diabetes. In this project, we are investigating the link between high glucose-induced mitochondrial fragmentation, increased production of reactive oxygen species and apoptosis in the context of diabetic retinopathy.
Neil B. Ruderman, M.D., Ph.D.
Endocrinology, Diabetes and Nutrition
Dr. Ruderman’s research deals with the effects of insulin, exercise, and fuels on cellular metabolism, signal transduction, and most recently, gene expression. Its focus in the past 10 years has been on a malonyl CoA fuel sensing and signaling mechanism described by his laboratory and its regulation by AMPK. His group has proposed that dysregulation of this mechanism, leading to increases in fatty acid esterification and/or the generation of reactive O2 species, plays a causal role in the pathogenesis of many forms of insulin resistance in skeletal muscle and the early endothelial cell damage that antedates atherosclerosis in diabetes. Their research also examines the notion that activation of AMPK prevents this dysregulation and, perhaps independently, later events that it causes (e.g., NFB-mediated gene expression). Some of the investigators in his unit and their fellows work primarily with skeletal muscle (Saha), some with cultured vascular cells (Ido), and still others with adipocytes (Luo). Thus, from a conceptual perspective, mechanisms worked out in one system are often tested in others. The techniques employed by the Ruderman laboratory include reporter gene assays, adenoviral gene transfer (cultured vascular cells), immunofluorescence microscopy, protein separation, enzyme analysis, and metabolite determination by spectrophotometric and chromatographic methods. The models used include incubated tissues, cultured cells, intact rodents and, in some collaborative efforts, humans. Many program faculty are co-investigators and/or advisors in this work, as are individuals from other institutions. The latter include Drs. Marc Prentki, University of Montreal (malonyl CoA regulation); E.W. Kraegen, Garvan Institute, Australia (insulin resistance in rodents in vivo); Guenther Boden, Temple University (insulin resistance in humans); and David Carling, Hammersmith Hospital, U.K. (molecular biological approaches to study AMPK action in vascular cells).
Joshua D. Safer, M.D.
Endocrinology, Diabetes and Nutrition
Diseases of cutaneous proliferation and differentiation are poorly treated. Among the elderly, chronic wounds cost $8-12 billion dollars annually in medical costs and more in lost productivity. Current wound healing agents are expensive and have been associated with increased scarring. In addition, hyperproliferative skin diseases like psoriasis afflict 1% of the human population and result in further financial toll.
Although skin is the largest organ in the body, the role of thyroid hormone metabolism in epidermal proliferation has not been investigated with rigor. In the thyroid research unit, we endeavor to establish mechanistic pathways integral to thyroid hormone action on adult skin. The research attempts to provide possible therapeutic targets for enhancing or suppressing the proliferative response of skin in such diverse conditions as psoriasis, burn injury, and wound healing. The laboratory has been developing a research program to demonstrate that local manipulation of thyroid hormone economy would prove a novel and cost-effective strategy for the treatment of cutaneous pathology.
The active thyroid hormone, T3, is necessary for both growth and differentiation of skin cells. Previously we have found that epidermal proliferation is diminished in hypothyroid mice, that topical T3 can stimulate epidermal proliferation and that topical T3 can accelerate wound healing. The major circulating pro-hormone, T4 is converted to T3 by intracellular thyroid hormone deiodinases. Part of the research done in the lab relates to establishing thyroid hormone deiodinase expression and activity in order to highlight the potential to target the deiodinases in order to treat skin disease.
Current projects in the lab include the following: 1. Immunohistochemistry to demonstrate the tissue locations of thyroid hormone relevant proteins in a murine model. 2. Western protein analysis and rtPCR analysis of cultured cells for protein and gene expression.
In addition, projects in the lab include making use of a murine wound healing model where thyroid hormone, thyroid hormone analogs, and thyroid hormone antagonists can be topically applied to murine epidermis. Biopsies of the epidermis are taken and subject to investigation. The investigation includes immunohistochemistry, rtPCR, and BrdU incorporation into RNA. We further supplement the in vivo experiments with an assay of cell migration.
Jennifer J. Schlezinger, Ph.D.
Humans receive significant ambient daily exposures to multiple environmental contaminants, including aromatic hydrocarbons (by-products of combustion), phthalate esters (plasticizers used in manufacturing PVC) and organotins (antifouling agents). These types of contaminants induce apoptosis in developing B lymphocytes within the bone marrow. We want to know how synthetic chemicals override the naturally occurring cellular processes to induce death. We investigate multiple processes in the cell that may be altered by these chemicals, particularly how chemicals interact with receptors such as the aryl hydrocarbon receptor (AhR) and the peroxisome proliferator activated receptors (PPAR). Our newest research is focused on how activation of PPAR in the bone marrow may alter the bone marrow microenvironment, potentially adversely effecting lymphopoiesis. Further, as real-world exposures, such as those at Superfund sites, typically involve complex chemical mixtures, we want to investigate how chemicals within the mixtures may interact to enhance deleterious effects. Understanding these pathways is important because loss of B lymphocytes could potentially impair the ability to mount an immune response to infections. On the other side of the coin, our understanding of death pathways and mixture interactions potentially may be put to use in the development of new chemotherapeutics.
Barbara E. Corkey, Ph.D.
The main goal of work in the Corkey laboratory is to determine how fuels generate the signals to communicate among different organs in the body to modulate hormone and adipokine exocytosis, electrical activity, metabolism and gene expression. It involves assessment of the influence of metabolites and mitochondrial energy state on intracellular signal transduction in adipocytes, pancreatic ß-cells, liver and human fibroblasts. Recent emphasis has been on ion handling, respiration, the signaling consequences of cellular energy state, the influence of fatty acids on protein kinases and the role of fatty acids and long acyl CoA on signal transduction. Unique resources of the laboratory include imaging, fluorescence and amperometric techniques to measure responsiveness of living cells to various treatments and stimuli. Work is done in collaboration with scientists at Boston University School of Medicine, the BioCurrents Laboratory of the Marine Biological Institute, the Karolinska Institute, the Universities of Chicago, Montreal and Pennsylvania, and the Hamner Institutes for Health Sciences.
Gustavo Mostoslavsky, M.D., Ph.D.
Our goal is to advance our understanding of stem cell biology with a focus on their genetic manipulation via gene transfer and their potential use for stem cell-based therapy. We believe that by discovering the mechanisms involved in stem cell self-renewal and differentiation we will be able to manipulate stem cell fate and use it as the basis for the correction of several diseases. Project areas in the lab focuses on the use of different stem cell populations, including embryonic stem cells, induced Pluripotent Stem (iPS) cells, hematopoietic stem cells and intestinal stem cells and their genetic manipulation by lentiviral vectors.
Specific Areas of Research
Embryonic Stem Cell Modeling of Intestinal Differentiation Embryonic Stem Cells (ESC) are pluripotent undifferentiated cells capable of giving rise to cells from all three germ layers. This unique ability makes them ideal candidates to model early development allowing us to study the basic signaling mechanisms involved in stem cell fate determination. At the same time, manipulating ESC differentiation toward a specific developmental pathway holds a great promise for their use in regenerative medicine. One focus of our lab is differentiating mouse ESC into intestinal epithelial cells in order to understand the complex signaling pathways involved in intestinal commitment from endodermal progenitors and undifferentiated stem cells.
Our lab has a major interest in the study of induced Pluripotent Stem cells or iPS cells and the development of tools for their generation and characterization. Recent pioneering work by the laboratory of Dr. Yamanaka showed that fibroblasts transduced with retroviral vectors expressing four transcription factors, Oct4, Klf4, Sox2 and cMyc can be reprogrammed to become pluripotent stem cells that appear almost indistinguishable from ESC. In contrast to ESC, iPS cells are genetically identical to the individual from whom they are derived, raising the prospect of utilizing iPS cells for autologous cell-based therapies without risk of rejection. We have recently developed a single lentiviral vector, named pHAGE-STEMCCA, capable of generating iPS cells from post-natal fibroblasts with the highest efficiency reported to date. We aimed at using iPS cells in parallel to ESC for the study of intestinal lineage specification and their potential for regenerative medicine.
Characterization and Isolation of Intestinal Stem Cells The identification of Intestinal Stem Cells (ISCs) has long-eluded investigators. The recent discovery of LGR5 as a putative marker of ISCs has opened a window for their study and characterization. We use several methods, including gene marking and gene transfer technologies to study ISC biology and their potential use in cell and gene therapy.
Hematopoietic Stem Cell Manipulation for the Study of Stem Cell Self- Renewal and Differentiation Hematopoietic Stem Cells (HSCs) are the most thoroughly characterized stem cell population in the body and their study has resulted in well-established methods for their isolation, purification and reliable assays of HSC function. During the last few years we have substantially improved our ability to genetically manipulate HSCs using viral vectors for gene transfer. Despite these efforts, few genes are known to play a role in the processes of stem cell self- renewal and differentiation. Understanding the molecular mechanisms that govern those unique functions are crucial for developing the promise that stem cells hold for developmental biology and regenerative medicine. In our lab, we use lentiviral viral gene transfer to study the role of several molecules in long-term HSC self- renewal and differentiation.
Hematopoietic Stem Cell Manipulation for the Correction of Immunodeficiencies Our longstanding interest in the immune system combined with our experience in manipulating HSCs have culminated in several studies whose goal is genetic correction of Severe Combined Immunodeficiency (SCID). It has recently become clear that many SCID patients suffer from a spectrum of previously unrecognized hypomorphic mutations leading to partially impaired V(D)J rearrangement activity. The best example of this type of immunodeficiency is Omenn Syndrome (OS), which is caused in most cases by Rag hypomorphic mutations. While it is well established that the genetic defect in either of the RAG genes is the first determinant of the clinical presentation, the mechanism by which specific Rag mutations induce such diverse immunological phenotypic outcomes is still poorly understood. We have recently started a collaboration with a group at Harvard Medical School to use a variety of lentiviral vectors expressing Rag1 to study its role in immune dysregulation and to develop a new therapeutic approach for Rag1 related immunodeficiency based on lentiviral mediated gene therapy.
Gwynneth Offner, Ph.D.
Dr. Offner’s laboratory has had a long-standing interest in the structure, function and regulation of epithelial mucins. During the past decade, cloning studies on epithelial mucins have identified at least twenty distinct mucin genes, which can be divided into two groups: membrane-associated and secreted gel-forming mucins. Recent studies in her laboratory have focused on the former, specifically on MUC1. MUC1 is overexpressed in many cancers, including breast, colon, pancreatic and lung. Using RNA interference, her laboratory has shown that suppression of MUC1 gene expression leads to changes in cell phenotype and a decrease in the metastatic potential of cells. MUC1 is also expressed in normal cells, where it functions in epithelial cell protection. Dr. Offner’s hypothesis is that membrane bound mucins interact with secreted mucins to enhance the epithelial protective barrier. She has identified specific domains in the secreted mucin MUC5B which interact with a domain at the amino-terminal end of MUC1. Currently, she and her colleagues are investigating the binding of other proteins to the mucin scaffold, which could modulate mucin function in different cell and tissue types. The integrity of the mucin scaffold may have particular relevance to the pathogenesis of inflammatory bowel disease and this is a current focus in the laboratory.
Satish K. Singh, M.D.
H. Christian Weber, M.D.
The major thrust of Dr. Weber’s laboratory focuses on cell and molecular biological studies of mammalian bombesin receptors in human cancer and obesity. This family of G protein-coupled receptors comprises the gastrin-releasing peptide receptor (GRP-R), the neuromedin B receptor (NMB-R), and the orphan bombesin receptor subtype-3 (BRS-3). The human GRP-R is found ectopically expressed in human cancers of the colon, stomach, and prostate thereby mediating potent mitogenic properties through ligand specific receptor activation. Our research is directed towards the understanding of molecular mechanisms of aberrant GRP-R expression in epithelial cells and intracellular signaling pathways relevant in GRP-R dependent cell proliferation. Furthermore, it has now been clearly established that GRP-R and BRS-3 play a significant role in the regulation of feeding behavior, obesity, and glucose homeostasis. Consequently, laboratory investigations are aimed at the elucidation of ligand-activated intracellular signaling events and molecular mechanisms by which bombesin receptors regulate energy homeostasis.
Kenneth H. Albrecht, Ph.D.
Mammalian gonadal sex determination is a powerful system for studying organogenesis, cell fate determination, and the evolution of sex chromosomes and developmental regulatory mechanisms. Besides basic scientific interest, mammalian sex determination also is of biomedical interest. Approximately one in 1000 infants has a gonadal or genital anomaly. Furthermore, many of the known genes involved in sex determination also are implicated in pathological processes such as tumorigenesis and primary adrenal failure, and have essential roles in the normal development of organs other than the gonads. We use the mouse as a model system for studying mammalian sex determination and gonadal and adrenal organogenesis and employ genetic, molecular genetic, genomic, cell biological and embryological techniques. Currently, there are two main projects underway in the lab. In the first, we are investigating the molecular mechanisms of three mouse models of human sex reversal and adrenal dysmorphogenesis. In the second, we are identifying and characterizing new genes important for gonad development using genetic and genomic approaches such as microarray analysis of gene expression during organogenesis. Our long-term goal is to understand the molecular mechanisms of gonadal and adrenal organogenesis and their role in human disease.
Shoumita Dasgupta, Ph.D
Dr. Dasgupta is the Assistant Dean of Admissions and the
Director of Graduate Studies, Genetics and Genomics
Lindsay A. Farrer, Ph.D.
Dr. Farrer is Chief of the Genetics Program and a Professor of Medicine, Neurology, Genetics & Genomics, Epidemiology, and Biostatistics at Boston University Schools of Medicine and Public Health. He has served as served as the dissertation advisor or primary mentor for many pre-doctoral and postdoctoral trainees who have embarked on successful research careers. His laboratory is focused on identifying the genetic basis of several complex diseases and developing genetic mapping methods for locating modifiers for disorders whose primary defects are already known, but account for only a small portion of the phenotypic variation. Such modifier genes will probably be more amenable than the primary structural genes to strategies for delaying or modulating expression. Working together with other BU researchers, his lab is leading efforts to identify genes for hypertension and severe asthma, and genes influencing severity and expression of sickle cell anemia. In collaboration with researchers at other academic institutions, they are conducting genome scans to uncover genes conveying susceptibility to substance dependence and macular degeneration. In 2005, they identified a functional genetic variant in the complement factor H gene which accounts for approximately 50% of the attributable risk for macular degeneration, the leading cause of progressive vision loss and blindness in the elderly. Dr. Farrer’s major research focus is Alzheimer disease (AD). He directs the MIRAGE Project, a multi-center study of AD funded since 1991 by the National Institute on Aging, which has a long-term goal of identifying genetic and environmental risk factors for AD. This study was the first to demonstrate that genetic factors have a major role in the development of AD. His team has also shown that the ε4 variant of apolipoprotein E (APOE), the strongest AD risk factor identified thus far, is more weakly associated with disease in men and persons older than 75 years. The aim of the currently funded project is to compare variations in genes related to vascular functioning with disease risk and pre-clinical changes evident on MRI scan of the brain in 1000 White and African American AD families. In 2007, Dr. Farrer co-directed an international study which demonstrated in that neuronal sortilin-related receptor SORL1 is genetically and functionally associated with AD. Currently, his lab is conducting genome wide association studies for AD in Caucasian and African American families in the MIRAGE Study and in an inbred Israeli Arab community with an extraordinarily high prevalence of the disorder.
Richard Sherva, Ph.D.
My primary interest is in exploring the genetic epidemiology of complex disease using linkage and association methods. I’ve worked on cardiovascular phenotypes including hypertension, metabolic syndrome, and stroke, as well as psychiatric diseases including addiction and ADHD, with a focus on gene x (gene, environment, drug treatment) interactions. I currently work on projects related to the genetics of Alzheimer’s disease, cocaine addiction, and thalassemia.
Sam Thiagalingam, Ph.D.
Research focuses on the use cancer genomics and molecular biology, employing primarily breast and colon cancers as model systems. We hope to contribute to the elucidation of the multi-modular molecular network (MMMN) cancer progression models as the road map to dissect the complexity inherent to cancer through these studies. Our approach to achieve this overall goal is to undertake research under the following topics: (i) The Smad signaling connection to colon cancer metastasis; (ii) The Smad signaling connection to breast cancer metastasis/bone metastasis; (iii) Development of therapeutic approaches to breast cancer by targeting TGF-beta signaling events; and (iv) hBub1 is a suppressor of p53 mediated cell death. Recently, we have also become interested in the role of epigenetics in the pathogenesis of major psychiatric disorders such as schizophrenia (SCZ) and bipolar disorder (BD). Because of the overwhelming evidence for the role of environmental factors in the presentation of the major psychiatric disorders, we hope to decipher a direct correlation between the altered epigenome and SCZ and BD. Our pioneering studies analyzing the LOH frequencies of colon cancer showed that SMAD4 is the major target tumor suppressor gene localized to the minimally lost region on chromosome18q. As a follow up of these studies, we are working to unravel the molecular basis of SMAD4 inactivation in advanced metastatic colon cancer. Furthermore, overactivation of the signaling cascade mediated by increased levels of TGF-beta has been implicated in high incidence of breast cancer metastases. We have devised an inter-disciplinary research strategy to test the inhibitors of TGF-beta signaling as potential therapeutic agents for advanced breast cancer. We have also continued to maintain an interest in understanding the connection between genomic instability and cancer at the molecular level. Our genetic and epigenetic studies of lung cancer and the examination of the literature have enabled us to propose an academically simplified scheme to explain the complexity in cancer progression as a process that consists of various alterations in a multi-modular molecular network (MMMN) defined by a cascade of modular events encompassing multiple targets within each module. We are in the process of developing strategies to validate the MMMN model for breast cancer with the hope of paving the way for developing similar models for other cancers as well as the other complex diseases. Furthermore, in a series of preliminary studies on post-mortem brain samples, by investigating DNA methylation and polymorphisms of COMT and RELN in bipolar disorder and schizophrenia, we demonstrated that differential epigenetic modification of these genes play a significant role in the pathogenesis. We plan to extend these preliminary observations to establish a logical relationship between epigenetic changes and schizophrenia and bipolar disorder by analyzing candidate genes and a wide spectrum of genes.
HEMATOLOGY & ONCOLOGY
David Chui, M.D.
Hematology and Oncology
Gerald V. Denis, Ph.D.
Hematology and Medical Oncology
All of the work in our lab is focused on the study of a novel transcriptional co-activator, the double bromodomain protein Brd2. This protein is related to the basal transcription factor TAF250; Brd2 binds to acetylated histones through its bromodomains, then recruits transcription factors and co-activators/co-repressors to chromatin. Through its association with the SWI/SNF complex, Brd2 helps remodel chromatin to regulate the transcription activity of many genes. This highly conserved and ubiquitous protein is essential for life; knockout of the gene is lethal in all organisms tested so far (mice, Drosophila, yeast). We have found that, in mammals, two key targets of Brd2 are the cyclin A locus, which controls cell cycle progression through S phase, and gene targets of the PPAR transcription factor, which controls adipogenic transcription. Brd2 is a positive regulator of cyclin A but a negative regulator of adipogenesis. In transgenic mice that constitutively express Brd2 in B cells, cyclin A is upregulated and the cell cycle is destabilized, leading to an aggressive non-Hodgkin’s lymphoma, which in humans is one of the major contributors to cancer death. We are developing new molecular profiling and therapeutic approaches to treat this malignancy. On the other hand, whole-animal knockdown of Brd2 in mice causes extreme, morbid obesity; dramatically illustrating a role for Brd2 in energy homeostasis. The unexpected role of Brd2 in energy metabolism has profound significance for human health: demographic projections warn of an enormous, worldwide increase in morbidity and mortality associated with obesity. The incidence of individuals with diabetes is expected to reach 366,000,000 by 2030; and these cases will be accompanied by numerous health complications. Much of the incidence Type 2 diabetes will be directly related to obesity. We are investigating human populations to understand Brd2’s involvement in obesity as well as hematologic cancers, and we are actively exploring Brd2 mechanisms of transcriptional control in collaboration with BUSM experts in diabetes and cancer.
Maria Isabel Dominguez, Ph.D.
Hematology and Medical Oncology
The canonical Wnt pathway is essential for proliferation and cell fate determination in adult tissues and during embryonic development. Our long-term goal is to characterize the mechanism of Wnt signaling and understand the role of the Wnt pathway in development and cancer. We are focusing our studies on the function, regulation and mechanism of action of two components of the Wnt pathway: the serine-threonine kinases CK2 and GSK3beta. To understand the role of these kinases in embryonic development, we utilize two model organisms: the frog Xenopus laevis and the mouse. In Xenopus laevis, we have implicated CK2 and GSK3beta in regulating maternal dorsal fate determination. Currently, we aim to determine how these two kinases are regulated endogenously during early frog Xenopus laevis development. In the mouse, through the study of CK2alpha ablated embryos, we have implicated CK2 in regulating cellular differentiation and morphogenesis of the heart. We are pursuing biochemical, molecular and genetic approaches to determine the downstream targets of CK2 during heart development. Concomitantly, we are using Xenopus and cell culture to understand the molecular mechanism of action of CK2 and GSK3beta in Wnt signaling. Understanding how the Wnt pathway is normally activated is a prerequisite to understand its dysregulation displayed in cancers. Utilizing Xenopus embryos, we have shown that CK2 is sufficient and necessary for canonical Wnt signaling. Ongoing studies focus in determining the mechanism of regulation of Wnt signaling by CK2, and in the development and testing of novel CK2 inhibitors in vivo in Xenopus and in vitro in breast and colon tumor cell lines.
Jianlin Gong, M.D.
Hematology and Medical Oncology
Dr. Gong’s research work is focused on the development of dendritic cell (DC)-based tumor vaccine. One of the DC-based tumor vaccines pioneered by her group is through the use of fusion between DC and tumor cells. The fusion of DC with tumor cells represents in many ways an ideal approach to deliver, process, and subsequently present tumor antigens to the immune system. DC-tumor fusion vaccine is effective in the elimination of established pulmonary metastases in the animals. Coculture of cancer-patient-derived T cells with the fusion vaccine induces CTL against autologous tumor cells. These studies have culminated in a phase I clinical trial of DC-AML fusion vaccine for patients with acute myelogenous leukemia (AML) in BMC organized by her and Dr. Adam Lerner in the division of Hematology/Oncology. In studying the molecular basis of DC-tumor fusion vaccine, her laboratory has identified that the tumor-antigen peptides chaperoned by heat shock protein may be the therapeutic component of DC-tumor fusion cells. This finding could potentially be the basis for a vaccine for clinical use. Her laboratory has several transgenic murine models, including a mouse (MMT) with expression of polyomavirus middle T oncogene and development of spontaneous mammary carcinomas. This murine model mimics breast cancer development in humans and thus is highly relevant to the study of human breast cancer. MMT mice are being crossed with mice deficient in telomerase, the biologic clock that controls cell division, to determine the role of telomerase in the tumorigenesis of breast cancer.
Kevan L. Hartshorn, M.D.
Hematology and Oncology
Adam Lerner, M.D.
Hematology and Medical Oncology
My laboratory studies two topics: cyclic nucleotide-mediated apoptosis in lymphoid malignancies and the role of a novel family of focal-adhesion-associated proteins in breast cancer anti-estrogen resistance. With regards to the first topic, we have shown that PDE4 cyclic nucleotide phosphodiesterase inhibitors selectively induce apoptosis in chronic lymphocytic leukemia (CLL) cells. Such PDE4 inhibitors are already in clinical trials as anti-inflammatory medications for asthma and COPD. We are interested in determining the mechanism by which such drugs kill CLL cells and the best way to take advantage of this activity in clinical trials in CLL. We are also studying EPAC, a cAMP-activated Rap1 GDP exchange factor that is activated in CLL cells following treatment with PDE4 inhibitors. Remarkably, CLL cells are the only circulating hematopoietic cells that appear to express functional levels of EPAC. As EPAC activation is anti-apoptotic when it occurs in the absence of concomitant PKA activation, we are interested in whether EPAC may be a novel therapeutic target in CLL. A second area of interest is AND-34, a novel p130Cas-associated protein that activates Rac and Cdc42 in breast cancer cell lines and in B lymphocytes. Over-expression of AND-34 or p130Cas induces anti-estrogen resistance in human breast cancer cell lines and, at least for AND-34, this appears to occur in a Rac-dependent fashion. We are examining the mechanism by which AND-34 activates Rac and what “upstream” signaling pathways initiate such AND-34-mediated Rac activation in breast cancer cells.
Martin H. Steinberg, M.D.
Hematology and Medical Oncology
A single beta-globin gene mutation causes sickle cell anemia. Nevertheless, the exceptional phenotypic variability of this disease suggests that other genes could modulate its phenotype. We have discovered that polymorphisms in some genes were associated with discrete subphenotypes of sickle cell anemia, stroke for example, and with disease severity estimated by a more comprehensive analysis of laboratory data and clinical subphenotypes. In some of our studies we have learned that networks of interacting gene polymorphisms or SNPs and laboratory variables can predict the likelihood of stroke in sickle cell anemia with great accuracy, and also foretell the likelihood of near-term death. In genome-wide association studies of about 2,000 sickle cell anemia patients and 1500 centenarians, we hypothesize that independent studies of these groups will provide extensive information about disease predisposition. Using novel analytical methods, we hope to facilitate a model of age-associated disease predisposition that transcends population origin effects and thus, represents the key genetic factors affecting disease predisposition that are inherent to all humans. With contemporary association analysis and novel bioinformatics, we will compare associations with clinical features of sickle cell anemia including blood pressure, survival, stroke, osteonecrosis, priapism, leg ulcers and an integrated measure of disease severity that reflects pathophysiological elements of this disease. In centenarian subjects, using centenarian offspring vs. controls, we are studying genetic associations with clinical features including physical function, disease prevalence and age at onset of age-related conditions including hypertension, stroke, cardiovascular disease and dementia. We will use novel advanced network modeling techniques to suggest genes and pathways that play crucial roles in aging-related disease, such as stroke and hypertension.
We are studying gene expression in mononuclear cells and blood outgrowth endothelial cells from patients with sickle cell pulmonary hypertension and controls in studies founded on our observations that inflammation and genes of the TGF-beta/BMP pathway seem to be associated with several disease subphenotypes. Finally, we are examining whether the serum proteome and oxidatively modified proteins in plasma are associated with sickle pulmonary hypertension.
Progressing from genome-based studies, through gene expression, to the serum proteome, these integrated genomic studies will further illuminate our understanding of the pathophysiology and genetic modulation of sickle cell disease and bring us closer to our ultimate goal of discovering new therapeutic targets.
Frank C. Gibson III, Ph.D.
Dr. Gibson’s primary research interests focus into the mechanisms underlying microbial pathogenesis and gaining better insight into both host-specific and pathogen-specific activities/structures affecting diseases of the oral cavity. The principal organism studied in the Gibson lab is the anaerobic pathogen Porphyromonas gingivalis. Ongoing research interests in the Gibson lab include defining the properties of the capsular polysaccharide of P. gingivalis that influence disease caused by this organism. Dr. Gibson is interested in the defining the impact of chronic infections such as periodontal disease on the progression of systemic diseases including atherosclerotic cardiovascular disease. In addition, the Gibson lab has initiated studies to identify the influence of aging on the host inflammatory response directed at P. gingivalis. Genetic techniques, molecular approaches, as well as cell and animal modeling are routinely employed in the Gibson lab to better characterize novel host-pathogen interactions.
Andrew J. Henderson, Ph.D.
Effective strategies for eradicating HIV infection will depend on purging virus from cellular reservoirs that harbor transcriptionally latent HIV provirus. How HIV latency is established and maintained is poorly understood since studies on HIV transcription repression have been hindered by the rarity and inaccessibility of latently infected cells. The primary focus of the Henderson lab is developing approaches to investigate how cellular signals regulate HIV transcription and replication. Current projects include examining signal transduction pathways that impact HIV replication, including repression of provirus transcription. We have characterized both positive and negative signaling pathways that impact multiple steps of the HIV replication cycle. In addition, we have gained insights into how latent provirus is induced providing potential new therapeutic targets for HIV. These studies have provided a better understanding of the factors that limit HIV expression in different cell populations.
Robin Ingalls, M.D.
Over the last decade, a new appreciation for the innate immune system has emerged in the immunology field. The innate immune system is the first line of defense against invading pathogens and is required to optimize the more specialized adaptive immune response. Our laboratory is interested in understanding the innate immune recognition of pathogenic bacteria at mucosal surfaces. The mucosal surface, once described by the late Charles Janeway as the frontier of the immune system, is a complex biosystem providing physical, chemical and cellular defenses against pathogens while tolerating a host of commensal bacteria. One of the main projects of the lab is to understand the role of innate immune receptors, adaptor proteins and soluble mediators in driving responses to the sexually transmitted bacterial pathogens, Neisseria gonorrhoeae and Chlamydia trachomatis. In particular we are interested in understanding mucosal immune response in the upper and lower female reproductive tract, as these infections disproportionately impact on women, leading to the complications of tubal infertility, ectopic pregnancy, and chronic pelvic pain. We have established in vitro and in vivo (mouse) models to study both the protective immune response as well as the complications associated with infection. In addition to our long-standing studies on sexually transmitted infections, we have recently started a project to compare the mucosal immune response in the respiratory tract with that of the genital tract, using the mouse pathogen C. muridarum and the human pathogen C. pneumoniae. Finally, related to the C. pneumoniae respiratory studies, we have also started to investigate the role of innate immunity in mediating the chronic inflammatory plaque formation associated with C. pneumoniae infection.
Paul Skolnik, M.D.
Dr. Skolnik is Professor of Medicine at the Boston University School of Medicine. Dr. Skolnik has a substantial record of serving as mentor for successful basic and clinical research trainees on NIH-funded T32 training grants and K08 awards. His current basic research interests include HIV-related innate immune responses in the lung, modeling of cytokine and chemokine networks in the lung, and micro-RNA effects on these innate immune responses. Patient-derived samples are used in these studies whenever possible to most closely mirror the in vivo situation. He also has expertise in clinical HIV/AIDS research design and methodology and is site PI for the AIDS Clinical Trials Group (ACTG) at Boston University Medical Center. Dr. Skolnik has carried out many clinical trials of investigational new immunotherapeutic and antiretroviral drug therapies for HIV infection, and especially studies the immunologic effects of these anti-HIV therapies.
Lee M. Wetzler, M.D.
Dr. Wetzler’s laboratory investigates innate and adaptive immunity and microbial pathogenesis, especially in regard to vaccine development. One major aspect of this work centers on the pathogenic Neisseria, Neisseria gonorrhoeae and Neisseria meningitidis. He has found that the major outer membrane protein of these organisms, the Neisserial porin PorB, can work as an immune adjuvant due to it recognition by the pattern recognition receptor TOLL-like receptor (TLR) 2. He has found that antigen presenting cells, including B cells, dendritic cells and macrophages, are activated by PorB in a TLR2, TLR1 and MyD88 dependent manner, inducting upregulation of class II MHC, costimulatory molecule CD86 and other markers of activation. Moreover, MAPK signaling events are required for the upregulation of the expression of these markers, as well as production of pro-inflammatory cytokines. Using an in vivo peritoneal mouse model of inflammation, we have shown that both PorB and intact N. meningitidis induce a significant cellular influx and pro-inflammatory cytokine production, which is also TLR2 dependent. However, we also found that mast cells are activated during this process, which may be in a TLR2 independent manner, along with a significant influx of eosinophils, indicative of induction of a TH2 type cellular response. Studies are continuing to investigate the mechanisms of these phenomena.
We are also investigating the use of this TLR2 ligand, PorB, as a vaccine adjuvant using classic antigens like OVA and more relevant antigens like bacterial capsular polysaccharide. This work has also been extended to investigate the adjuvant activity and mechanism of immune stimulation of the B subunit of cholera toxin. We have found that CTB induces antigen presenting cell stimulation via the lipid raft ganglioside GM1 via induction of a cell-signaling program ending in NF-kB and CREB activation and gene transcription. This work is still on going.
Finally, a new major thrust of the Wetzler lab is investigating the immune response and natural history of Francisella tularensis pulmonary infection in mice and using this data to aid in developing vaccines towards this potential bio-terrorist agent. We have found that using PorB as an adjuvant and Francisella LPS as an antigen, we can enhance protection in these mice, which is likely due to induction of antibodies and improved immunity (potentially both innate and adaptive immunity. It appears that induction of IL-1beta may be more associated with survival both during natural infection and after vaccination, while IL-6 and IL-17 may have the opposite effect, being more associated with death after pulmonary infection. Finally, we have recently found that induction of bronchial associated lymphoid tissue (BALT) after vaccination also appears to be associated with protection. These iBALT structures are long lasting and may be due to persistent antigen stimulation, which we are currently investigating.
Barbara S. Nikolajczyk, Ph.D.
My lab is interested in understanding inflammation in type 2 diabetes and inflammatory bowel disease patients. Inflammation is strongly implicated in the direst complications of type 2 diabetes, including cardiovascular disease and stroke. We are focusing on two cell types that promote inflammation in these patients: monocytes and B cells. Monocytes are well known to produce significant amounts of pro-inflammatory cytokines. We are specifically interested in how IL-1 beta, a cytokine at the apex of multiple pro-inflammatory cascades, is hyper-expressed by monocytes from type 2 diabetics. We have defined a “poised promoter architecture” for the IL-1 beta locus in normal monocytes. This structure is characterized by a constitutively accessible promoter and constitutive transcription factor association. Current work is aimed at understanding how this structure is changed in patients to result in IL-1 beta hyper-production. A second focus of the lab is to understand how B cells contribute to type 2 diabetes and inflammatory bowel disease through production of pro-inflammatory cytokines. We have found B cells in type 2 diabetes patients are fundamentally altered such that they unexpectedly respond to inflammatory stimuli. Ongoing analyses are characterizing these responses as well as the underlying molecular mechanisms driving them. These studies are aimed at identifying targets for alleviating the over-production of pro-inflammatory cytokines generally associated with the devastating complications of systemic inflammatory diseases.
Gregory Viglianti, Ph.D.
Worldwide, heterosexual transmission accounts for most HIV-1 infections. Clearly, controlling heterosexual transmission of HIV-1 would be a significant step toward eliminating this global epidemic. To achieve this goal, it will be important to delineate the cellular and molecular events that affect virus transmission. Although both inflammatory and ulcerative sexually transmitted infections (STIs) enhance sexual transmission of HIV-1, the underlying mechanisms leading to this enhancement have not been fully elucidated. Enhanced susceptibility to infection may be due to a number of factors, including the disruption of the integrity of the cervicovaginal epithelial barrier, recruitment of HIV-1 target cells such as Langerhans/dendritic cells (LC/DC), macrophages (MØ)‚ and T lymphocytes to sites of inflammation, and direct activation of target cells by STIs. A common feature of STI pathogens is that they encode ligands for members of the Toll-like receptor (TLR) family of pattern recognition receptors and these ligand-activated TLRs can both activate HIV-1 target cells and induce local inflammatory responses. Ligand-activated nuclear receptors (NR), including peroxisome proliferator activated receptor (PPAR), liver X receptor (LXR), glucocorticoid receptor (GR), and estrogen receptors (ER) are potent inhibitors of TLR-induced inflammatory gene expression in MØ, LC/DC, and epithelial cells. In addition, retinoic acid receptor (RAR) and PPAR ligands have been shown to repress HIV-1 gene expression while estrogen has been shown to block vaginal transmission of SIVmac. A goal of our laboratory is to determine the role of TLR-signaling in augmenting HIV-1 infection of target cells that are found in the cervicovaginal mucosae. Our major, and long-term goal is to examine the potential role of ligand-activated NR as inhibitors of HIV-1 transmission. We hypothesize that ligand-activated NR act by: 1) directly repressing HIV-1 transcription, and 2) by limiting the TLR-induced inflammatory microenvironment that favors HIV-1 replication. We are currently focusing our efforts to 1) evaluate the impact of NR/TLR crosstalk on HIV-1 replication and inflammatory gene expression in primary LC, DC, and MØ, 2) examine the effects of NR/TLR crosstalk on HIV-1 infection of target cells and inflammation in vaginal and cervical tissue explants and in an organotypic model of the human vagina, and 3) determine the molecular mechanism(s) of TLR-modulated HIV-1 transcription and how it is regulated by NR signaling.
Vassilis Zannis, Ph.D.
Dr. Zannis’ research focuses in two directions. The first direction is the structure and function of apolipoproteins A-I and apolipoprotein E and their role in the pathogenesis in cardiovascular disease. In addition, we are investigating the role of apoE in Alzheimer’s disease. For these studies we have developed methodologies for high level of expression of variant apolipoprotein forms and their purification from the culture medium. The variant apoA-I forms are analyzed for their ability to bind to lipids and lipoproteins to bind to the scavenger receptor BI (SR-BI) and to activate LCAT. The variant apoE forms are analyzed for their ability to bind to amyloid peptide (A) and to apoE receptors present in the brain (VLDL receptor E receptor II). The second direction is the role of the apoCIII enhancer on the transcriptional regulation of the human apoA-I CIII gene cluster. In particular we are focusing on the role of hormone nuclear receptors which bind to proximal and distal sites as well as the role of the SP1 which binds to the apoCIII enhancer on these genes using transgenic animals and antisense methodologies.
Steven C. Borkan, M.D.
Dr. Borkan is an Associate Professor of Medicine at Boston University and an attending physician in the Renal Section at Boston Medical Center. His research interests include the cellular mechanisms of ischemic acute kidney injury (AKI), a common cause of organ failure. Specifically, his laboratory manipulates the cell stress response, including individual heat stress proteins (HSP), to promote renal epithelial cell survival and protect organ function after ischemia. The lab focuses on the role of Hsp70 in antagonizing mitochondrial membrane injury caused by members of the BCL2 family. At present, it appears that Hsp70 simultaneously interrupts several checkpoints in the apoptotic cell death pathway, preserves renal structure and organ function. Hsp70 also prevents mitochondrial fragmentation resulting from dysregulation of organelle fission and fusion during renal cell stress. Our future goals include manipulating Hsp70 using both pharmacologic and molecular approaches to prevent the consequences of acute ischemic AKI. Murine models with site-specific expression (proximal tubule, distal vascular endothelial cell) or knockout of Hsp70 will be used to identify the sites most vulnerable sites for ischemic injury in order to target future therapy. Dr. Borkan is the senior author of numerous publications in the area of the cellular stress response and has been a Principal Investigator for the NIH for nearly 15 years.
Herbert T. Cohen, M.D. >
Dr. Cohen’s laboratory is addressing the molecular basis of renal cancer, renal cystic disease and renal development and offers special expertise in gene expression mechanisms, signal transduction, protein-protein interactions, transcription factors, and renal epithelial cell biology. The laboratory has identified the first member of new protein family, the Jade family of proteins, on the basis of its interaction with the von Hippel-Lindau tumor suppressor pVHL. pVHL protein is a key component of the cellular oxygen-sensing system. VHL is also the major renal cancer gene in adults. Jade-1 is a novel, growth suppressive plant homeodomain transcription factor that is the first protein found to be stabilized by pVHL. Jade-1 is also a ubiquitin ligase and key component of histone acetylation complexes. Interestingly, Jade-1 is stabilized by VHL protein in a manner that correlates with risk of renal manifestations in von Hippel-Lindau disease, which includes a cystic renal disease phenotype. A wider role for Jade-1 in renal cyst formation was therefore sought. Jade-1 is regulated by the product of the major gene for autosomal dominant polycystic kidney disease (ADPKD), polycystin-1, in a manner that is also disease relevant and physiologic. Importantly, Jade-1 serves as a critical ubiquitin ligase for the oncoprotein beta-catenin, which also plays critical roles in renal cancer, renal cyst formation and renal development. In part by controlling transcription and beta-catenin ubiquitination, Jade-1 and related family members are likely to be particularly important in many contexts.
Weining Lu, M.D.
The primary research interests in my laboratory focus in the kidney development and the molecular basis of congenital anomalies of the kidney and urinary tract (CAKUT). CAKUT is family of diseases with a diverse anatomical spectrum, including kidney anomalies (e.g. renal dysplasia, duplex kidneys, renal cystic diseases, hydronephrosis), and ureteric anomalies (e.g. vesicoureteral reflux, megaureter, ureterovesical or ureteropelvic junction obstruction). As many as 2% of human fetuses have renal and urological anomalies which is the primary cause of kidney failure in young children. These patients may present later in life with reflux or obstructive nephropathy, a condition that manifests with low nephron numbers, secondary focal and segmental glomerulosclerosis (FSGS), proteinuria, and hypertension.
My research program has adopted combined human and mouse molecular genetics approaches to identify a number of different developmental genes (e.g. ROBO2, NFIA) to the study of kidney development and CAKUT. The first human molecular genetics approach is to study individuals with CAKUT and apparent chromosomal defects, with the aim of using chromosomal translocations as signposts to identify these critical genes (reverse genetics). Thereafter, molecular identification and analysis of candidate genes as well as mutation studies in affected individuals with a familial pattern of CAKUT will be carried out (forward genetics). The second approach is to study temporal and spatial expression patterns of candidate genes in human and mouse. Meanwhile, we will generate and study knockout and transgenic mouse models of candidate genes to elucidate more fully their role in kidney and urinary tract development. Once these candidate genes (e.g. ROBO2, NFIA) have been identified, we will take a multidisciplinary approach to gain further mechanistic insights in vivo and in vitro on the role of these genes in normal and abnormal developmental processes of the kidney and urinary tract, and on the pathogenesis of CAKUT. This multidisciplinary approach includes the application of human and mouse molecular genetics, developmental biology, renal physiology, molecular biology, and biochemistry. The ultimate goal is to provide new knowledge of disease mechanisms underlying developmental antecedents of CAKUT and to identify potential therapeutic interventions.
Ian R. Rifkin, MBBCh, Ph.D.
The overall goal of my research is to better understand basic mechanisms involved in the pathogenesis of systemic autoimmune disease in general and systemic lupus erythematosus (SLE) in particular. There are two main projects in the laboratory, both involving the use of murine models of lupus. The first project focuses on the identification and cloning of autoreactive T cells, testing the pathogenicity of the cloned T cells in-vivo, and studying their in vivo regulation and activation. The second project focuses on i) the role of autoantigen itself (DNA/protein or RNA/protein complexes) in activating the innate and adaptive immune responses characteristic of SLE through engagement of Toll-like receptors in dendritic cells and autoreactive B cells and ii) the development of strategies to inhibit this activation in vivo with a view to identifying novel therapeutic targets in autoimmunity. In addition to the murine studies, collaborations have been established to test whether similar pathogenic pathways are important in human SLE.
David J. Salant, M.D.
The focus of Dr. Salant’s laboratory is on the immune basis of glomerular diseases with particular regard to the humoral mechanisms of glomerular cell injury in order to elucidate the mechanisms by which antibodies alter the function and morphology of glomerular visceral epithelial cells (podocytes). Experimental models of immunological glomerular diseases resembling those seen in man are used to obtain a fundamental understanding of the immunopathogenetic mechanisms of injury. Specific interests include: The structural biology of the podocyte and alterations that lead to the development of proteinuria. The effects of antibody- and complement-mediated podocyte injury on the podocyte cytoskeleton and slit-diaphragm protein complex. The role of complement regulatory proteins in limiting complement-mediated podocyte injury. The role of the notch family of signaling receptors in glomerular development and response to injury. Identification of the target antigen/s in human membranous nephropathy.
John H Schwartz, M.D.
Renal epithelial cells are highly polarized. This polarization is required to perform biochemical work (transport) and to maintain the integrity of the epithelial tubular membrane. I have interest in two different aspects of the polarity phenomena. The first deals with the molecular basis for the targeting and fusion of vesicles that are involved in the shuttling of aquaporin-2 and H+-ATPase to and from the apical membrane of renal collecting duct cells. We have demonstrated that the same subset of proteins involved in polarized exocytosis in neurons, SNARE proteins, are involved in the targeting in renal epithelial cells. We are currently identifying the signal cascade that regulates the activation of these SNARES. The second area of interest deals with the effect of ischemia on the maintenance of junctional complexes in renal epithelial cells. Ischemia disrupts these complexes and induces a loss in the functional polarity of tubular epithelial cells. We have begun to identify the sequence of regulatory changes that induces the loss of ZA and the intermediate effect of the liberation of catenins from the ZA.Expertise: Renal Physiology; acid-base homeostasis; ion transport; epithelial cell biology; ischemic renal disease.
Diddahally R. Govindaraju, Ph.D.
Robert C. Green, MD, MPH
Dr. Green is the Associate Director of Boston University’s Alzheimer’s Disease Clinical and Research Program and the Clinical Director of the NIA-funded Alzheimer’s Disease Center. He is Professor of Neurology, Genetics and Epidemiology. Dr. Green’s research interests are in early and preclinical detection, treatment and prevention of Alzheimer’s disease and in translational genomics and personalized medicine. He is Principal Investigator and Director of the REVEAL Study (Risk Evaluation and Education for Alzheimer’s Disease), a multi-center project funded by the National Human Genome Research Institute and the National Institute on Aging to develop genetic risk assessment strategies for individuals at risk for Alzheimer’s disease. Dr Green is also PI of an NIH mentoring award and an NIH-funded project titled, Impact of Direct-to-Consumer Genetic Testing. He serves as a consultant on the NIH-funded Cache County Memory and Aging Study and site-PI/steering committee chair of the Alzheimer’s Disease Neuroimaging Initiative Data and Publications Core. He was the Boston site director of the NIH-funded ADAPT Study (Alzheimer’s Disease Anti-Inflammatory Prevention Trial), one of the first large-scale intervention trials to prevent the development of Alzheimer’s disease in at-risk family members. Dr. Green is the author of over 150 publications, serves on a number of advisory, editorial and grant review boards and is immediate past President of the Society for Behavioral and Cognitive Neurology. He was voted one of America’s “Best Doctors” by his peers.
Richard H. Myers, Ph.D.
Research interest is focused upon the application of genetic research methods for the investigation of adult onset diseases with complex etiology (Parkinson’s disease, coronary heart disease, Alzheimer’s disease, osteoarthritis, osteoporosis etc.). He has a long-standing interest in Huntington’s disease and has participated in a wide range of research investigations for this disease. He was a member of the New England Huntington’s Disease “Center Without Walls” since its inception in 1980. His HD studies may best be characterized as ‘Neurobiological Studies’ in that they include studies into the mechanisms disease expression, including complex genetic modifier studies and a series of neuropathological studies of effects of disease expression in the brain. He has been involved in a number of studies in positional cloning. From 1980 to 1993, he participated in the cloning of the gene for Huntington’s disease. He then initiated the genome scan project in the Framingham Study, and initiated an NIH funded project for a genome scan in Parkinson’s disease. Since 1993 he has participated in genetic linkage studies for hypertension (the HyperGEN study, one of the NHLBI Family Blood Pressure Program Project studies), and the genome scan in the NHLBI Family Heart Study.
Deborah Anderson, Ph.D.
Sexually transmitted infections (STIs) are epidemic in the United States and worldwide, and have far reaching health, social and economic consequences. Each year more than twenty million men and women in the United States acquire an STI; the World Health Organization estimates the global annual incidence of curable STIs (excluding HIV-1 and other viral STIs) to be 333 million. Some STIs, such as those transmitted by the Human Immunodeficiency Virus Type 1 and high-risk human papilloma virus strains, can cause severe morbidity often leading to death. Others adversely affect fertility and neonatal health. Our current research is focused on the development of vaccines and topical microbicides for the control of sexually transmitted pathogens including HIV-1. To this end, we are studying mechanisms of cell-associated HIV transmission and fundamental features of local immune defense functions at genital mucosal surfaces that affect HIV-1 pathogenesis and transmission.
Thomas A. Einhorn, M.D.
General Orthopaedic Surgery
Research focus on the molecular mechanisms of skeletal repair. Specific areas of investigation include an understanding of the molecular genetics of fracture healing, cartilage repair, and bone regeneration. Studies are performed in vitro and in vivo. Both normal and genetically manipulated animal models are utilized including knockout, conditional knockout, novel binary systems, and siRNA knockdown protocols. The roles of peptide signaling molecules, pro-inflammatory cytokines, pharmaceuticals and angiogenic agents on bone and cartilage repair and regeneration are investigated.
Louis C. Gerstenfeld, Ph.D. , Chair of Qualifying Exams
General Orthopaedic Surgery
All of our studies focus on bone repair after trauma or surgical treatment. All of our ongoing research is translational and has adapted human surgical techniques to small animal models to address our research goals. We use a combination of state of the art assessment tools to examine fracture and bone repair in vivo including micro-computer assisted tomography (CT) biomechanical testing for strength and material property and novel tools of three dimensional tissue reconstruction of sequential histological specimens. We use cell-based models of primary cultures isolated from the bone marrow and fracture callus and several skeletal cells lines to complement our animal studies. We use all forms of state of the art molecular analysis both in vivo and in vitro including transgenic animal models, retroviral knock down strategies, and various approaches of mRNA expression analysis from RT-PCR to large scale transcriptional profiling.
- We have numerous ongoing projects covering a diverse set of pre-clinical trials of biological compounds, small molecule pharmaceuticals and cell-based therapies that are directed at enhancing fracture healing. Our pre-clinical trials of compounds and drugs involve studies of Bone Morphogenetic Protein (BMPs), VEGF and PTH as therapeutics for improvements in bone healing. We also use cell-based stem cell therapies to promote healing.Our basic research studies in fracture healing focus on three project areas.
- One set of projects examines the role of the innate immune system as a primary initiator in bone regeneration after injury and have primarily focused on the role of tumor necrosis factor (TNF) and Fas mediated cell apoptosis. A second project area is focused on the VEGF signaling during fracture healing. Our final set of projects focuses on the role of inherited genetics in bone and variations in stem cell populations that give rise to repair tissues during fracture healing. This project makes use of inbred strains of mice that have definable variations in bone quality as defined by variation in geometric characteristics and material property intrinsic to mineral and matrix properties. This projects specifically examines how genetic variations effect fracture healing.
Benjamin L. Wolozin, M.D.
Pharmacology and Experimental Therapeutics
Our laboratory investigates the pathophysiology of neurodegenerative diseases. The research on Parkinson Disease pathophysiology of genetic factors implicated in Parkinson’s disease, including LRRK2, alpha-synuclein, parkin, DJ-1 and, LRRK2. We hypothesize that genetic mutations linked to Parkinson’s disease converge onto two main cellular pathways, mitochondrial function or management of misfolded proteins. We perform the studies using genetically modified cells (e.g., primary neuronal cultures or cell lines) or genetically modified animals (principally C. elegans, but also mouse or human tissue from carriers), and apply the tools of molecular biology, immunochemistry and biochemistry. We have recently demonstrated that LRRK2 binds to MKK6, a kinase that lies upstream of p38 and regulates the stress response. Our studies in mammalian cells demonstrate that LRRK2 regulates membrane localization of MKK6, as well as of small GTPases, such as rac1. Using C. elegans lines expressing human LRRK2 (WT or mutant) we demonstrated that LRRK2 modulates the stress response. Knockdown of the C. elegans homologues of MKK6 or p38 blocks the effects of LRRK2 in C. elegans, demonstrating the requirement of MKK6 for the actions of LRRK2. We have recently begun to examine the pathophysiology of Amyotrophic Lateral Sclerosis. This work focuses on a protein, TDP-43, that was recently shown to be the predominant protein that accumulates during the course of the disease. Our work in cell culture demonstrates that TDP-43 aggregates in response to stress and suggests that TDP-43 functions in the stress granule pathway. Finally, our work on Alzheimer disease focuses on the interaction between the proteins that produce beta-amyloid (amyloid precursor protein, presenilins and BACE) and the genes that regulate cholesterol metabolism. Our current work focuses on the mechanism by cholesterol regulates production of beta-amyloid and processing of its precursor protein, APP, with a particular focus is on oxysterol binding proteins, which are regulated by oxysterols, the major cholesterol catabolite in the brain. A second line of research in my lab uses epidemiological approaches to identify promising drug candidates for therapy of Alzheimer’s disease. We are using large databases to analyze the effect of every FDA approved medication on the incidence of Alzheimer disease, and then studying the relevant medications in the laboratory to determine the putative mechanism through which the medications might exhibit their protection.
PHYSIOLOGY & BIOPHYSICS
Victoria Bolotina, Ph.D.
Ion Channel and Calcium Signaling Unit
Dr. Bolotina is a Professor of Medicine, Physiology and Biophysics, and a leading expert in calcium signaling, ion channels and vascular physiology (with over 2000 citations of her work), who is well funded by NIH. The focus of her research is on the molecular mechanisms of calcium entry and its role in physiological and pathological function. Calcium signaling is an essential component of cell life and death and is directly involved in virtually all cellular functions. Using an integrative multidisciplinary approach and multiple state-of-the-art techniques, investigators in Dr. Bolotina’s lab track each process from individual molecules and protein complexes, to Ca2+ signaling cascades within the cell and the function of the whole organs/systems, and translate it to the origins of different disease and potential cures. We combine molecular, biochemical and electrophysiological approaches with advanced imaging of live cells (confocal, FRET, TIRF, live imaging and other), and with studies of the main physiological functions of primary cells and cell lines (proliferation, migration, secretion, constriction and other). To study how targeted impairment of specific molecules translates into organ dysfunction and disease we develop and study new transgenic and KO mouse models. To see the range of interests, depth of the studies and techniques readily available in our lab, please see the papers and review articles published by Dr. Bolotina, and/or come visit the lab.
Currently, there are several major projects underway in Dr. Bolotina’s lab: 1) molecular mechanism of the notorious store-operated Ca2+ entry pathway, and its role in cardiovascular system; 2) mechanism and new determinants of cell migration, angiogenesis and tumor growth; 3) new mechanism of Ca2+oscillations and insulin secretion in beta cells, and new determinants of diabetes; 3) identification of the mysterious calcium influx factor (CIF); 4) characterization of cardiovascular and other phenotypes of a newly developed constitutive and inducible iPLA2b-deficient mouse models.
James A. Hamilton, Ph.D.
Physiology and Biophysics
Dr. Hamilton’s laboratory is developing and applying novel physical approaches to study of obesity, metabolic syndrome, and cardiovascular disease. 13C NMR methods pioneered in his laboratory have been used to describe the interactions of fatty acids and drugs with binding sites on albumin, and new studies are currently correlating important details predicted by NMR with recent x-ray crystal structure. His laboratory has determined the complete solution structure of several intracellular fatty acid binding proteins (FABP) by multi-dimensional NMR and is studying the molecular details of ligand binding to FABP. New fluorescence approaches have been developed to characterize the diffusion of fatty acids into adipocytes and evaluate the effects of drugs and inhibitors on fatty acid uptake.
A newer focus of research is the application of magnetic resonance imaging (MRI) to examine fat tissue and atherosclerosis. These studies extend from animal model systems (mouse and rabbit) to humans. The work emphasizes interactions of different disciplines on translation of basic biophysics to human disease aspects. Our study of subjects with metabolic syndrome and obesity explores the hypothesis that a unifying feature of metabolic syndrome is enhanced deposition of lipids throughout the body outside of the normal adipose stores. These inappropriate stores include hepatocellular triglyceride, perivascular and pericardial triglyceride. MR imaging will identify and quantify site-specific abnormalities in obese patients such as cardiac functions.
In our animal studies of atherosclerosis, imaging of live mice allows us to follow diseases and therapies in a single animal over a long period of time. A rabbit model of the acute event of atherosclerosis, plaque rupture and thrombosis is being studied to develop MRI for prediction of unstable and high risk plaques. In humans with advanced carotid atherosclerosis who are undergoing endarterectomy, we will use MRI to determine evidence of inflammation and plaque vulnerability and perform in vivo and ex vivo to enhance the application of MRI to carotid plaque characterization
PREVENTIVE MEDICINE & EPIDEMIOLOGY
Vasan Ramachandran, MBBS, M.D.
Preventive Medicine & Epidemiology
Dr. Ramachandran’s epidemiological research based at the Framingham Heart Study has focused on 4 inter-related areas:
- the epidemiology of congestive heart failure
- population-based vascular testing and echocardiography; vascular remodeling, ventricular remodeling and ventricular-vascular coupling
- epidemiology of obesity, cardiovascular risk factors and risk prediction; and,
- exercise physiology, and exercise test responses in asymptomatic individuals and related prognostic information
Dr. Ramachandran has been a recipient of a mid-career clinical investigator award (K24) from the National Heart Lung and Blood Institute, USA, and is currently mentoring several fellows in the four areas of research outlined. He has several active RO1s from the NIH that focus on the classic and genetic epidemiology of ventricular-vascular coupling, biomarkers of ventricular and vascular remodeling, and role of biomarkers of distinct biological pathways in mediating CVD risk.
Alan Fine, M.D., Chair of the Admissions Committee
Knowledge about the identity, localization, and biology of lung stem/progenitor cells has lagged behind what is known for other organ systems. This state-of-affairs is a direct result of a variety of technical issues such as a deficiency of informative markers that can be used to precisely characterize putative stem cell populations in the lung. Advancements in the field have also been limited by impediments imposed by the unique biology of the lung, including its marked cellular complexity and slow cell turnover. One additional fundamental limitation in our knowledge base is an uncertainty over the extent and mechanisms involved in adult lung regeneration.
The Fine laboratory is addressing these broad themes in a variety of experimental contexts, including mouse lung development and adult lung injury repair. Using these model systems, they seek to identify reparative and progenitor cell lung populations, and the genetic programs that control their fate. One particular interest involves understanding how differentiated mesenchymal elements, such as bronchial and pulmonary artery vascular smooth muscle evolve and differentiate during embryogenesis and during the early post-natal period. Clarification of these issues has broad implications for understanding the basic biology of the lung and also for the design of therapies for a variety of lung diseases, including asthma, pulmonary hypertension, and interstitial pulmonary fibrosis.
An extension of these studies involves defining the interactions between the developing lung and the developing hematopoietic system. These interactions are necessary for establishing a local and functional innate immune system prior to birth. This work is focused on elucidating how the embryonic lung locally controls differentiation of myeloid progenitors that the Fine lab found localized to the primitive fetal lung mesenchyme. They are also pursuing studies that will determine how certain distinct classes of hematopoietic cells regulate development of the lung’s arterial system in utero.
Matthew R. Jones, Ph.D.
During pneumonia, various pro-inflammatory cytokines and chemokines are released to guide immune cells to the site of infection. Too much inflammation can compromise normal lung function whereas, too little of a host response can lead to uncontrolled bacterial growth and sepsis. Cytokine expression thus needs to be carefully directed by molecular mechanisms regulating transcription, mRNA stability, and translation. Our work is centered on several aspects of cytokine mRNA instability. In general, cytokine transcripts are very labile which is a property imparted by various sequence elements residing in their 3´ untranslated regions (UTRs). These 3´ UTRs contain AU-rich elements (AREs) that are bound by ARE-binding proteins and direct mRNA translational efficiency and decay. One project in the lab is centered on how specific ARE-binding proteins regulate select cytokine expression during inflammation. In addition to AREs, many cytokine transcript 3´ UTRs are targeted by microRNAs, which can lead to their abrogated translation, deadenylation, and ultimately, decay. Another research focus of ours is exploring how cytokine transcript targeting microRNAs themselves are processed and regulated. We have found that the Zcchc11 protein is a uridyltransferase that is responsible for the uridylation of specific microRNAs. End modifications of microRNAs, such as untemplated uridylation, can reduce their ability to repress the targeted transcript. Future studies are designed to elucidate which microRNAs are modified by Zcchc11 during inflammation and whether these edits have functional consequences. Understanding how these mechanisms function to orchestrate inflammation during pneumonia will provide an important basis for future disease management.
Darrell Kotton, M.D.
Pulmonary, Allergy and Critical Care
The remarkable capacity of stem cell populations (such as adult hematopoietic stem cells and embryonic stem cells) to indefinitely self-renew or differentiate into multiple lineages has generated considerable excitement in the scientific and lay communities alike. Although stem cells hold enormous promise for the field of regenerative medicine, our approach is based on the long-term goal of understanding how stem cells recapitulate normal developmental milestones as they self-renew and differentiate. Because appropriate recovery of the lung epithelium after injury involves reactivation of early developmental pathways, understanding how embryonic stem cells differentiate and develop into lung epithelial lineages is likely to reveal how the lung recovers from injury and disease.
For our studies we employ a murine embryonic stem cell line engineered to express three knock-in reporter molecules (Brachyury-GFP, Foxa2-hCD4, and Titf1-hCD8). Sequential expression of these reporters indicates the sequential differentiation of ES cells through a primitive streak-like stage into multipotent endodermal precursors followed by early lung epithelial progenitors. Thus, this novel tool should allow us to precisely quantify and purify cells progressing through early stages of endoderm and lung development. Currently we are able to efficiently derive multipotent definitive endoderm in 66% of cultured ES cells after activin A stimulation. These endodermal precursors may be purified by flow cytometry and possess the capacity to undergo further lineage specification into early liver, pancreas, and lung epithelial precursor phenotypes. In contrast to undifferentiated ES cells, which form teratomas in mice if transplanted, our purified endodermal precursors derived from ES cells may be transplanted under mouse kidney capsules where they do not result in teratomas but rather form organized luminal structures with a highly organized epithelium. We are currently focused on the derivation of Titf1+ lung epithelial progenitors from ES cells using a combination of growth factors (e.g. Activin A and FGFs) designed to mimic early in vivo development. Our plan is to test the in vitro and in vivo developmental potential of our ES cell-derived putative lung epithelial progenitors in a variety of ex vivo assays as well as in mouse models of lung injury.
We believe the ES cell system provides an ideal platform to model the early developmental steps involved in lineage specification and differentiation of the lung epithelium from multipotent endoderm. Little is known about the mechanisms that control these early developmental cell fate decisions. We propose approaches designed to evaluate candidate mechanisms controlling lineage specification of lung epithelium from multipotent endodermal precursors. These approaches are designed to test mechanisms for which there is support in the literature as well as in our preliminary data. For example, focused gene expression data obtained by analyzing ES cell-derived endoderm as well as microarrays prepared from the primordial lung field of developing embryos suggest that the transcription factor GATA6, the canonical wnt signaling pathway, and chromatin remodeling proteins (Brm, Brg1, and Suz12) all play important roles in specifying lung lineage in the developing endoderm.
Joseph P. Mizgerd, Sc.D.
Pulmonary, Allergy and Critical Care
Acute lower respiratory tract infections cause a terrible public health burden. The development, progression, and outcome of these infections is determined by innate immune responses such as neutrophil recruitment and activation, necessary for host defense but also contributing to lung injury. Innate immune responses in the lungs require the coordinated expression of mediators including adhesion molecules, chemokines, colony stimulating factors, and cytokines that are absent or present only at low levels in uninfected lungs, but are expressed at high levels during infection. Similar mediators are induced during most lung infections, although individual mediators can have different roles during different infections. The coordinated expression suggests programs of gene regulation. NF-kappaB transcription factors are critical to the gene expression program directing innate immunity in the lungs, with RelA inducing innate immunity genes mediating host defense and p50 counteracting this gene induction to prevent lung injury. Other transcription factors are also important, such as STAT3 which both facilitates host defense and limits lung injury. These transcription factors have cell-specific roles during infection. Finally, expression of innate immunity mediators is regulated post-transcriptionally as well. An improved knowledge of the molecular mechanisms directing innate immunity in the lungs will provide new directions for preventing and curing acute lower respiratory tract infections.
Laertis Oikonomou, Ph.D.
Current research approaches in regenerative medicine aim at harnessing and enhancing the regenerative potential of endogenous stem cells or at manipulating stem cells ex vivo for the development of cell replacement therapies. Several stem cell populations have been isolated and studied, but pluripotent embryonic stem cells (ESCs) hold particular promise for widespread clinical application due to their unparalleled differentiation repertoire. The current research paradigm in ESC research dictates that embryo development serve as “roadmap” for the directed differentiation of ESCs to therapeutically relevant lineages (e.g. motor neurons, islet β-cells, cardiomyocytes).
An indispensable step in the in vitro differentiation of ESCs to lung epithelial cells is the derivation of primordial lung progenitors. Since Nkx2-1, a homeodomain-containing transcription factor, is the first known marker of the lung domain in development at E9.0, we have created an Nkx2-1GFP knock-in mouse as a collaborative effort with Dr. Darrell Kotton to study the epithelial lung progenitors ex vivo. We have isolated Nkx2-1GFP+ lung progenitors by FACS and we will perform deep sequencing to define their global genetic signature. The latter will be compared to the one of other Nkx2-1 expressing lineages (thyroid, forebrain) and of E8.25 pre-specified anterior foregut. These studies will offer high-resolution information on the pathways and mechanisms that control lung specification and will lead to the discovery of new surface markers peculiar to the lung primordium.
We are also set to investigate the mechanisms by which substratum elasticity and biaxial or uniaxial stress, affect the differentiation and maturation of ESC-derived epithelial lung progenitors. Although elasticity is an established concept of continuum mechanics, only recently has it emerged as an important determinant of stem cell fate, self-renewal, and engraftment. We will perform these studies in collaboration with Dr. Bela Suki and Dr. Joyce Wang from the BU Biomedical Engineering Department.
Lee J. Quinton, Ph.D.
Pulmonary, Allergy and Critical Care
Lung infections account for a tremendous burden of disease, representing the most frequent cause of infection-related deaths and a common cause of acute lung injury. The innate immune response is critical for the prevention of lower respiratory tract infections. Yet, this response must be tightly regulated, such that adequate host defenses do not result in inflammatory lung injury. Our long-term goal is to elucidate intra- and extra-pulmonary signaling events required for an immune response that is both effective and balanced. The local response to lung infections includes neutrophil recruitment, expression of soluble mediators such as cytokines, and the extravasation of plasma constituents from the vascular space into the alveolar space. The result is an inflammatory milieu and cellular composition that promotes local immune responsiveness. This physiologic transition within the lung, however, occurs in tandem with a systemic acute phase response (APR), typified by altered circulating levels of acute phase proteins (APPs). While the APR has long been recognized as a useful biomarker of disease progression during pneumonia, the collective impact of APPs on inflammation and host defense are unknown. We have recently shown that the cytokines TNF-alpha, IL-1, and IL-6, which are critical for maximal host defense during pneumonia, are also essential for the activation of downstream transcription factors and the expression of APPs in the liver. Therefore, the hepatic APR may be a systemic conduit through which select cytokines promote the immune response to lung infection. Understanding how APPs and other extra-pulmonary factors integrate with local responses in the lung to promote immunity and tissue protection during pneumonia will help to identify novel prognostic indicators and therapeutics for this important disease.
Maria I. Ramirez, Ph.D.
Pulmonary, Allergy and Critical Care
The main focus of my research is the differentiation of lung epithelial cells during mammalian development. We study two developmental events at the molecular level: the initial determination and specification of the endoderm to become lung epithelium and the differentiation of alveolar type I cells to form the air-blood barrier perinatally. Molecular mechanisms that initiate lung formation from the embryonic foregut: Using extremely sensitive methods for dissection of small tissues and analysis of gene expression, we have identified new and known genes expressed during differentiation of endoderm cells into lung epithelial cells. Chromatin remodeling and DNA methylation genes significantly change their expression level coincident with the formation of the lung primordium. Based on these findings and the importance of chromatin modifications in the regulation of cell fate decisions in other developing systems, we are evaluating whether chromatin modifications and DNA methylation participate in initiation of lung development by establishing patterns of gene expression in the embryonic foregut, inducing lung cell fates. Lung alveolar type I cell morphogenesis: The extensive distal lung gas-exchange surface that supports respiration at birth forms in the last 2-3 days of gestation in mice. This process requires differentiation of epithelial type I and type II cells, vascular remodeling and thinning of the mesenchyme. During lung development, progenitor cuboidal epithelial cells remodel their apical and basolateral plasma membranes and cytoskeleton resulting in cell flattening, thinning and spreading. These processes, to which we refer collectively as cell flattening, are a hallmark of type I cell differentiation and are required for alveolar sac enlargement perinatally, and for repairing the lung epithelium after injury in the adult. We are studying epithelial type I cell flattening during development using models of normal and altered lung epithelial morphogenesis, focusing in the membrane enlargement and cytoskeleton reorganization that take place to increase the surface area covered by epithelial type I cells 25-100 fold during type I cell morphogenesis.
Maria Trojanowska, Ph.D.
David M. Center, M.D.
Dr. Center is Boston University’s Associate Provost for Translational Research and the Director of the Clinical and Translational Research Institute funded by the NIH. As a result, he directs Boston University’s efforts to facilitate translational research in all venues and leads a major effort in identifying new areas of development.
His own laboratory is interested in two major themes which revolve around roles for Interleukin-16, co-discovered with Bill Cruikshank in 1982. The first theme relates to the functions of IL-16 as an immunomodulatory cytokine. Over the past several years, in collaboration with Bill Cruikshank, he has studied the role of IL-16 in recruitment and development of Regulatory T cells and demonstrated that it plays a key role in tolerance to airborne allergens. Utilizing transgenic knockout and overexpressing mice his laboratory is involved in demonstrating the patterns of CD4+ T cell trafficking through lymph nodes and lung parenchymal in normal and immunologically challenged lungs and identifying potential therapeutic implications of altering recruitment patterns of Regulatory T cells.
The second major emphasis of his laboratory relates to the functional properties of the precursor protein for IL-16, Pro-IL-16 as a tumor suppressor gene. In these studies, along with Yujun Zhang he has shown that Interleukin-16 is synthesized as a precursor which is present in cytoplasm and nucleus of resting T cells. It contains a phosphorylation regulated nuclear localization motif and binds a nuclear chaperone hsc70 which is essential for transport to the nucleus where its presence induces arrest of the cell cycle at G0/G1. It inhibits the cell cycle by acting as a scaffolding protein that assembles a histone deacetylase complex targeted via binding to GA-BP to the Skp2 promoter using intermolecular PDZ binding motifs. Skp2 is an essential member of the ubiquitin ligase protein degradation pathway responsive for degrading the cell cycle cyclin dependent kinase inhibitor p27. In the presence of pro-IL-16, the complex inhibits Skp2 transcription, which in turn decreases p27 degradation resulting in rises in p27 levels and arrest of the cell cycle in G1. Current studies are directed at identifying mutations in Pro-IL-16 that predispose to T cell malignancies and determining its role is permissive exit from G1 in normal T cell activation and proliferation following antigen stimulation.