Caveolins, caveolae, and lipid rafts in cellular transport, signaling, and disease

Abstract

Caveolae were initially described some 50 years ago. For many decades, they remained predominantly of interest to structural biologists. The identification of a molecular marker for these domains, caveolin, combined with the possibility to isolate such cholesterol- and sphingolipid-rich regions as detergent-insoluble membrane complexes paved the way to more rigorous characterization of composition, regulation, and function. Experiments with knock-out mice for the caveolin genes clearly demonstrate the importance of caveolin-1 and -3 in formation of caveolae. Nonetheless, detergent-insoluble domains are also found in cells lacking caveolin expression and are referred to here as lipid rafts. Caveolae and lipid rafts were shown to represent membrane compartments enriched in a large number of signaling molecules whose structural integrity is essential for many signaling processes. Caveolin-1 is an essential structural component of cell surface caveolae, important for regulating trafficking and mobility of these vesicles. In addition, caveolin-1 is found at many other intracellular locations. Variations in subcellular localization are paralleled by a plethora of ascribed functions for this protein. Here, more recent data addressing the role of caveolin-1 in cellular signaling and the development of diseases like cancer will be preferentially discussed.

Effects of caveolin-1 and P-ERK1/2 on Ang II-induced glomerular mesangial cell proliferation

“…Studies using gene knockout technology indicate that caveolin-1 plays a key role in the formation and mobility of the caveolae. 19,20 In our study, Ang II reduced caveolin-1 expression on plasma membrane, and promoted its partial translocation to the cytoplasm. Therefore, We postulated that Ang II promoted the translocation of caveolin-1 to the cytoplasm, where it was partially degraded, resulting in decreased protein levels of caveolin-1.…”

The Tetraspan Protein EMP2 Regulates Expression of Caveolin-1

“…Caveolae are found in most cell types but are particularly abundant in terminally differentiated cells such as adipocytes, endothelial cells, type 1 pneumocytes, fibroblasts, and muscle cells (1,2). The primary structural component of caveolae is caveolin-1, a 21-24-kDa integral membrane protein believed to act as a scaffolding protein within caveolae membranes (3).…”

Expression of caveolin‐1 in the rat temporomandibular joint

“…Caveolae are flask-shaped invaginations of the plasma membrane that play important roles in cholesterol transport (Smart et al, 1996), transcytosis (for review, see Stan, 2002), signal transduction (for review, see Quest et al, 2004), and tumor suppression (Lee et al, 1998). Caveolin is a major component protein of the caveolae (Rothberg et al, 1992), which has three main isoforms: caveolin-1, -2, and -3 (for review, see Cohen et al, 2004).…”