RETRACTED: Characterization of a cytosolic heat-shock protein caveolin chaperone complex - Involvement in cholesterol trafficking (Retracted Article)

Caveolin is a 22-kDa protein that appears to play a critical role in regulating the cholesterol concentration of caveolae, Even though caveolin is thought to be a membrane protein, several reports suggest that this peculiar protein can traffic independently of membrane vesicles, We now present evidence that a cytosolic pool of caveolin is part of a heat-shock protein-immunophilin chaperone complex consisting of caveolin, heat-shock protein 56, cyclophilin 40, cyclophilin A, and cholesterol. Treatment of MH 3T3 cells with 1 mu m cyclosporin A or 100 nM rapamycin disrupted the putative transport complex and prevented rapid (10-20 min) transport of cholesterol to caveolae, The lymphoid cell line, L1210-JF, does not express caveolin, does not form an immunophilin-caveolin complex, and does not transport newly synthesized cholesterol to caveolae, Transfection of caveolin cDNA into L1210-JF cells allowed the assembly of a transport complex identical to that found in NIH 3T3 cells, In addition, newly synthesized cholesterol in transfected cells was rapidly (10-20 min) and specifically transported to caveolae, These data strongly suggest that a caveolin-chaperone complex is a mechanism by which newly synthesized cholesterol is transported from the endoplasmic reticulum through the cytoplasm to caveolae.