Caveolins Muscle Their Way Into the Regulation of Cell Differentiation, Development and Function. Focus On “Muscle-Specific Interaction of Caveolin Isoforms (Cav-1, Cav-2 and Cav-3): Differential Complex Formation Between Caveolins in Fibroblastic Versus Muscle Cells

Since their initial characterization in the early 1990s, the functions ascribed to caveolin proteins have steadily increased in complexity and sophistication. Caveolins were initially identified as the main component of the “coat” of caveolae, vesicles that were originally described in the 1950s (22). Caveolae were initially considered to be vesicular structures that mediated transcytosis of macromolecules; caveolins were thus viewed as structural proteins that aided formation of the vesicle. By the mid-1990s, caveolae and their “siblings,” lipid rafts, rapidly became appreciated as “hot spots” for plasmalemmal signaling, with a newly recognized function as organizational or scaffolding proteins that attract and retain certain signaling moieties in efficient complexes. However, in recent years, evidence has steadily mounted to support the notion that caveolins are much more than simply structural components of vesicles or docking sites for signaling molecules. In fact, caveolins are now acknowledged to be critical regulators of several signaling pathways that control cell development, differentiation, and proliferation