title: Caveolins/caveolae protect adipocytes from fatty acid-mediated lipotoxicity.
abstract: Mice and humans lacking functional caveolae are dyslipidemic and have reduced fat stores and smaller fat cells. To test the role of caveolins/caveolae in maintaining lipid stores and adipocyte integrity, we compared lipolysis in caveolin-1 (Cav1)-null fat cells to that in cells reconstituted for caveolae by caveolin-1 re-expression. We find that the Cav1-null cells have a modestly enhanced rate of lipolysis and reduced cellular integrity compared with reconstituted cells as determined by the release of lipid metabolites and lactic dehydrogenase, respectively, into the media. There are no apparent differences in the levels of lipolytic enzymes or hormonally stimulated phosphorylation events in the two cell lines. In addition, acute fasting, which dramatically raises circulating fatty acid levels in vivo, causes a significant upregulation of caveolar protein constituents. These results are consistent with the hypothesis that caveolae protect fat cells from the lipotoxic effects of elevated levels fatty acids, which are weak detergents at physiological pH, by virtue of the property of caveolae to form detergent-resistant membrane domains.
authors.affiliation: Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA.
authors.forename: Tova
authors.initials: T
authors.lastname: Meshulam
authors.forename: Michael R
authors.initials: MR
authors.lastname: Breen
authors.forename: Libin
authors.initials: L
authors.lastname: Liu
authors.forename: Robert G
authors.initials: RG
authors.lastname: Parton
authors.forename: Paul F
authors.initials: PF
authors.lastname: Pilch
mesh_terms: D017667:Adipocytes / Q000166:cytology / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D021941:Caveolae / Q000187:drug effects / Q000378:metabolism*; D051242:Caveolin 1 / Q000235:genetics / Q000378:metabolism; D018929:Cell Culture Techniques; D002454:Cell Differentiation; D003902:Detergents / Q000009:adverse effects / Q000494:pharmacology; D050171:Dyslipidemias / Q000378:metabolism / Q000473:pathology; D004591:Electrophoresis, Polyacrylamide Gel; D004622:Embryo, Mammalian / Q000166:cytology; D005215:Fasting / Q000378:metabolism; D005227:Fatty Acids / Q000009:adverse effects* / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D017353:Gene Deletion; D015870:Gene Expression; D007770:L-Lactate Dehydrogenase / Q000032:analysis / Q000378:metabolism; D008066:Lipolysis / Q000187:drug effects*; D051379:Mice; D018345:Mice, Knockout; D018613:Microscopy, Confocal; D051381:Rats; D017207:Rats, Sprague-Dawley; D015854:Up-Regulation
chemical_list: D051242:Caveolin 1; D003902:Detergents; D005227:Fatty Acids; D007770:L-Lactate Dehydrogenase