title: Cholesterol depletion in adipocytes causes caveolae collapse concomitant with proteosomal degradation of cavin-2 in a switch-like fashion.
abstract: Caveolae, little caves of cell surfaces, are enriched in cholesterol, a certain level of which is required for their structural integrity. Here we show in adipocytes that cavin-2, a peripheral membrane protein and one of 3 cavin isoforms present in caveolae from non-muscle tissue, is degraded upon cholesterol depletion in a rapid fashion resulting in collapse of caveolae. We exposed 3T3-L1 adipocytes to the cholesterol depleting agent methyl-β-cyclodextrin, which results in a sudden and extensive degradation of cavin-2 by the proteasome and a concomitant movement of cavin-1 from the plasma membrane to the cytosol along with loss of caveolae. The recovery of cavin-2 at the plasma membrane is cholesterol-dependent and is required for the return of cavin-1 from the cytosol to the cell surface and caveolae restoration. Expression of shRNA directed against cavin-2 also results in a cytosolic distribution of cavin-1 and loss of caveolae. Taken together, these data demonstrate that cavin-2 functions as a cholesterol responsive component of caveolae that is required for cavin-1 localization to the plasma membrane, and caveolae structural integrity.
authors.affiliation: Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Breen
authors.forename: Marta
authors.initials: M
authors.lastname: Camps
authors.forename: Francisco
authors.initials: F
authors.lastname: Carvalho-Simoes
authors.forename: Antonio
authors.initials: A
authors.lastname: Zorzano
authors.forename: Paul F
authors.initials: PF
authors.lastname: Pilch
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D021941:Caveolae / Q000187:drug effects / Q000378:metabolism*; D002784:Cholesterol / Q000172:deficiency*; D005347:Fibroblasts; D005822:Genetic Vectors; D057809:HEK293 Cells; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D016086:Lentivirus; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D061251:Primary Cell Culture; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D059748:Proteolysis / Q000187:drug effects; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins; D015398:Signal Transduction / Q000187:drug effects; D047392:beta-Cyclodextrins / Q000494:pharmacology
chemical_list: C112745:Cavin1 protein, mouse; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D008565:Membrane Proteins; D020033:Protein Isoforms; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; D002784:Cholesterol; D046988:Proteasome Endopeptidase Complex