Capzb2 Interacts with b-Tubulin to Regulate Growth Cone Morphology and Neurite Outgrowth

Neuronal growth, migration, and survival depend on the regulated formation of cellular outgrowths called neurites. Extension of normal neurites requires coordinated interactions between cytoskeletal networks made up of microfilaments (composed of F-actin) and microtubules (formed by tubulin) in structures called growth cones that form at the tips of growing neurites. Capping protein (CP) has been known as a heterodimer that regulates F-actin assembly in a variety of cell types. Surprisingly, a new study by BUSM researchers found the neuronal CP b subunit, Capzb2, not only regulates F-actin assembly, but also inhibits microtubule polymerization by direct interaction with tubulin. “We further showed that this function of Capzb2 is required for establishment of the normal shape of growth cones and the appropriate length of neuritis,” said lead author Ivana Delalle, MD, PhD, an assistant professor of pathology and laboratory medicine. “Our data thus revealed an unexpected, dual role for CP in the regulation of both microfilaments and microtubules in neurons,” she added.