title: n-3 PUFA alter caveolae lipid composition and resident protein localization in mouse colon.
abstract: Caveolae, by virtue of their unique lipid environment, serve as signaling platforms that regulate cellular events. Perturbations in caveolae lipid composition have been shown in vitro to displace proteins from lipid microdomains, thereby altering their functionality and subsequent downstream signaling. Because membrane remodeling may not be accurately represented by using pharmacological treatments and in vitro models, we investigated the in vivo ability of dietary n-3 polyunsaturated fatty acids (PUFA) to alter caveolae lipid environment and the compartmentalization of resident proteins in mouse colonic mucosa. n-3 PUFA were examined for their chemoprotective, membrane lipid-modifying properties. Colonic caveolae in mice fed n-6 or n-3 PUFA enriched diets were characteristically enriched in cholesterol, sphingomyelin, and caveolin-1. n-3 PUFA feeding, compared with n-6 PUFA, significantly altered colonic caveolae microenvironment by increasing phospholipid n-3 fatty acyl content and reducing both cholesterol (by 46%) and caveolin-1 (by 53%), without altering total cellular levels. Concomitantly, localization of caveolae-resident signaling proteins H-Ras and eNOS in colonic caveolae was decreased by n-3 PUFA, by 45 and 56%, respectively. The distribution of non-caveolae proteins K-Ras and clathrin was unaffected. Moreover, EGF-stimulated H-Ras, but not K-Ras activation was significantly suppressed following n-3 PUFA feeding, in parallel with the selective alterations in their microlocalization. These findings reveal a novel modality by which n-3 PUFA remodel membrane microdomains in vivo and thereby alter caveolae protein localization and functionality.
authors.affiliation: Faculty of Nutrition,Texas A&M University, College Station, Texas 77843-2471, USA.
authors.forename: David W L
authors.initials: DW
authors.lastname: Ma
authors.forename: Jeongmin
authors.initials: J
authors.lastname: Seo
authors.forename: Laurie A
authors.initials: LA
authors.lastname: Davidson
authors.forename: Evelyn S
authors.initials: ES
authors.lastname: Callaway
authors.forename: Yang-Yi
authors.initials: YY
authors.lastname: Fan
authors.forename: Joanne R
authors.initials: JR
authors.lastname: Lupton
authors.forename: Robert S
authors.initials: RS
authors.lastname: Chapkin
mesh_terms: D000818:Animals; D021941:Caveolae / Q000737:chemistry* / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D051242:Caveolin 1; D022461:Caveolins / Q000032:analysis; D002460:Cell Line; D002784:Cholesterol / Q000032:analysis; D002966:Clathrin / Q000032:analysis / Q000378:metabolism; D003106:Colon / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D004032:Diet; D004789:Enzyme Activation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005227:Fatty Acids / Q000032:analysis; D015525:Fatty Acids, Omega-3 / Q000032:analysis / Q000494:pharmacology*; D043371:Fatty Acids, Omega-6 / Q000032:analysis / Q000494:pharmacology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D010743:Phospholipids / Q000032:analysis*; D021381:Protein Transport / Q000187:drug effects; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018631:ras Proteins / Q000032:analysis / Q000378:metabolism
chemical_list: C495541:Cav1 protein, mouse; C495537:Cav1 protein, rat; D051242:Caveolin 1; D022461:Caveolins; D002966:Clathrin; D005227:Fatty Acids; D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6; D010743:Phospholipids; D004815:Epidermal Growth Factor; D002784:Cholesterol; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; C496315:Nos3 protein, mouse; C496316:Nos3 protein, rat; D019908:Proto-Oncogene Proteins c-raf; D018631:ras Proteins