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Published online 5 March 2001. doi:10.1083/jcb.152.5.1057
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© The Rockefeller University Press, 0021-9525/2001//1057 $5.00
The Journal of Cell Biology, Volume 152, Number 5, , 2001 1057-1070

Original Article

A Caveolin Dominant Negative Mutant Associates with Lipid Bodies and Induces Intracellular Cholesterol Imbalance



Albert Pola, Robert Luetterforsta, Margaret Lindsaya, Sanna Heinob, Elina Ikonenb, and Robert G. Partona

a Institute for Molecular Bioscience, Centre for Microscopy and Microanalysis and Department of Physiology and Pharmacology, University of Queensland, Queensland 4072, Australia
b Department of Biochemistry, National Public Health Institute, 00300 Helsinki, Finland
University Of Queensland, Queensland 4072, Brisbane, Australia.(61) 7 3365 4422(61) 7 3365 6468

r.parton{at}mailbox.uq.edu.au

Recent studies have indicated a role for caveolin in regulating cholesterol-dependent signaling events. In the present study we have analyzed the role of caveolins in intracellular cholesterol cycling using a dominant negative caveolin mutant. The mutant caveolin protein, cav-3DGV, specifically associates with the membrane surrounding large lipid droplets. These structures contain neutral lipids, and are accessed by caveolin 1–3 upon overexpression. Fluorescence, electron, and video microscopy observations are consistent with formation of the membrane-enclosed lipid rich structures by maturation of subdomains of the ER. The caveolin mutant causes the intracellular accumulation of free cholesterol (FC) in late endosomes, a decrease in surface cholesterol and a decrease in cholesterol efflux and synthesis. The amphiphile U18666A acts synergistically with cavDGV to increase intracellular accumulation of FC. Incubation of cells with oleic acid induces a significant accumulation of full-length caveolins in the enlarged lipid droplets. We conclude that caveolin can associate with the membrane surrounding lipid droplets and is a key component involved in intracellular cholesterol balance and lipid transport in fibroblasts.

Key Words: caveolin • caveolae • cholesterol • lipid droplets • endoplasmic reticulum

© 2001 The Rockefeller University Press

The online version of this article contains supplemental material.

Abbreviations used in this paper: BFA, brefeldin A; CDV, cavDGV enriched vesicles; FC, free cholesterol; GFP, green fluorescent protein; NPC, Niemann-Pick disease C; PDI, phosphodisulphide isomerase; PM, plasma membrane; SCAP, SREBP-cleavage activating protein; SREBP, sterol-regulatory element-binding protein; YFP, yellow fluorescent protein.


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