The roles of microfilament-associated proteins, drebrins, in brain morphogenesis: a review.

The cytoskeleton has been suggested to be one of the important endogenous factors that control neuronal morphogenesis. Analysis of the developmental changes in the protein composition of the brain led to the discovery of novel developmentally regulated actin-binding proteins, drebrins. Drebrins exhibit a number of characteristics that one might expect for an intracellular regulator of neuronal morphogenesis. Drebrin has three isoforms and the mRNA of each isoform is transcribed from a single gene through alternative RNA splicing mechanisms. The expression pattern of each isoform is regulated spatially and temporally in the developing brain. Drebrin and tropomyosin competitively bind to actin filaments, and the exclusion of tropomyosin from actin filaments by overexpression of drebrin in fibroblasts results in the appearance of thick, curving bundles of actin filaments, and the formation of cell processes. Taken together, these data indicate that drebrin is one of the intracellular regulators of the neuronal morphogenesis.