The primary goal in our laboratory is to establish a better understanding of the mechanisms involved in the control of collagen gene expression associated with inflammation, atherosclerosis, tumors, and fibrotic diseases including systemic sclerosis. Collagen, a family of extracellular proteins, plays a critical role in remodeling after injury. Progressive deposition of excess extracellular matrix (ECM), occurs in a large group of diseases with no effective therapy including cardiovascular disease, pulmonary fibrosis, diabetic nephropathy, systemic sclerosis, and liver cirrhosis. Fibrosis (excessive scarring) is a progressive deposition of excess collagen-rich extracellular matrix produced by activated myofibroblasts leading to impairment and finally failure of affected organs. In normal healing following injury, fibroblasts differentiate into myofibroblasts. If progression to fibrosis occurs, these myofibroblasts do not undergo apoptosis but instead continue to proliferate and produce excess amounts of ECM. Isolated primary fibroblasts from fibrotic lesions maintain their activated myofibroblast phenotype containing abundant stress fibers with smooth muscle actin (SMA). Myocardin related transcription factors (MRTF-A, MRTF-B), members of the myocardin family, link actin dynamics with gene transcription. Our data indicate that MRTF-A dramatically (100 fold) activates collagen transcription. Fibroblasts with knockdown of MRTFA have different morphology and produce less collagen and SMA. We hypothesize that MRTFA plays a central role in activation and perpetuation of myofibroblast during the development of fibrotic disease.
Our laboratory has been examining both activation and repression of collagen transcription using molecular biology approaches. We have demonstrated that collagen type I genes are methylated in the first exon in cancer cells and colon cancer. Collagen gene is silenced in certain tumors. A methylation sensitive DNA binding protein (RFX1) represses transcription by binding to the collagen gene transcription start site. This protein belongs to a family of proteins that can function as transcription activators or repressors. RFX1 interacts with a co-repressor complex containing histone deacetylase which could be involved with spreading of DNA methylation and silencing. A RFX5 complex containing three other proteins (RFXANK/B, RFXAP, CIITA) are essential activators of major histocompatibility complex class II (MHC II) proteins that respond to interferon-gamma during inflammation and activate cells to become antigen producing cells. Interferon activates RFX5/CIITA synthesis and nuclear localization in human fibroblasts and smooth muscle cells. RFX5 proteins form a complex at the RFX site at the collagen gene transcription start site and recruits CIITA to repress collagen transcription through a phosphorylation sensitive interaction with co-repressor complex. Thus, this family of proteins may be very important modulators of collagen expression during inflammation.
- Graduate Faculty (Primary Mentor of Grad Students), Boston University School of Medicine, Graduate Medical Sciences
- Boston University, PhD
- Boston University, MS
- Simmons College, BS
- Published on 1/1/2016
Tam A, Xu S, Lopez H, Ahmed B, Khan K, Rosario H, Arumalla N, Gibson M, Denton C, Abraham D, Smith BD, Stratton RJ. O42 Investigating Mechanical Stress-Responsive Macrophages in Scleroderma. Rheumatology. 2016; 55(suppl 1):i54-i55.
- Published on 1/1/2016
Tam A, Shiwen X, Lopez H, Khan K, Ahmed-Abdi B, Rosario H, Arumalla N, Gibson M, Denton C, Abraham D, Smith BD, Stratton RJ. SAT0193 Macrophages Responding To Mechanical Stress in Scleroderma. Annals of the Rheumatic Diseases. 2016; 75(suppl 2):738.
- Published on 5/8/2015
Shiwen X, Stratton R, Nikitorowicz-Buniak J, Ahmed-Abdi B, Ponticos M, Denton C, Abraham D, Takahashi A, Suki B, Layne MD, Lafyatis R, Smith BD. A Role of Myocardin Related Transcription Factor-A (MRTF-A) in Scleroderma Related Fibrosis. PLoS One. 2015; 10(5):e0126015. PMID: 25955164.
- Published on 1/8/2015
McDonald ME, Li C, Bian H, Smith BD, Layne MD, Farmer SR. Myocardin-related transcription factor A regulates conversion of progenitors to beige adipocytes. Cell. 2015 Jan 15; 160(1-2):105-18. PMID: 25579684.
- Published on 1/1/2014
Ponticos, M., and B.D. Smith. Journal of biomedical research. Extracellular matrix synthesis in vascular disease: hypertension, and atherosclerosis. 2014; 28(1):25-39..
- Published on 1/1/2014
Stratton RJ, Xu S, Nikitorowicz J, Abdi-Ahmed B, Ponticos M, Denton CP, Abraham D, Smith BD. 309. Investigating the Role of MRTF-A in Systemic Sclerosis. Rheumatology. 2014; 53(suppl 1):i175.
- Published on 12/16/2013
Tumelty KE, Smith BD, Nugent MA, Layne MD. Aortic carboxypeptidase-like protein (ACLP) enhances lung myofibroblast differentiation through transforming growth factor ß receptor-dependent and -independent pathways. J Biol Chem. 2014 Jan 31; 289(5):2526-36. PMID: 24344132.
- Published on 9/20/2013
Ponticos M, Smith BD. Extracellular matrix synthesis in vascular disease: hypertension, and atherosclerosis. J Biomed Res. 2014 Jan; 28(1):25-39. PMID: 24474961.
- Published on 11/2/2011
Luchsinger LL, Patenaude CA, Smith BD, Layne MD. Myocardin-related transcription factor-A complexes activate type I collagen expression in lung fibroblasts. J Biol Chem. 2011 Dec 23; 286(51):44116-25. PMID: 22049076.
- Published on 8/12/2010
Xu Y, Luchsinger L, Lucey EC, Smith BD. The effect of class II transactivator mutations on bleomycin-induced lung inflammation and fibrosis. Am J Respir Cell Mol Biol. 2011 Jun; 44(6):898-905. PMID: 20705943.
View 61 more publications: View full profile at BUMC