Caveolin-1 cooperates with the recently described cavin protein family to form membrane caveolae structures, which are particularly abundant in adipocytes.
Caveolin-1 is also present in adipocytes as a lipid droplet associated pool, whose function remains uncertain. Caveolin-1 deficiency leads to lipoatrophy in mice models and human subjects, suggesting a critical role in the storage of lipids. We report here on retroviral overexpression caveolin-1-RFP, cavin-1-GFP or cavin-3-GFP in 3T3-L1 adipocytes. All three cell lines differentiated normally, contained a higher number of caveolae, and displayed ameliorated maximal insulin response, which is known to occur in caveolae. Only caveolin-1 overexpressing adipocytes, but not cavin-1 or -3, accumulated significantly larger lipid droplets than control lines containing empty retroviral vectors. Also, when injected into nude mice, all cell lines induced the formation of newly generated fat pads, but those produced from caveolin-1-RFP preadipocytes contained larger adipocytes, indicating a specific impact of caveolin-1 but not other cavins on lipid storage in vivo. Together our data demonstrate a specific role of lipid droplet caveolin pool, independent of caveolae, to modulate lipid droplet expansibility.