title: Chronic shear induces caveolae formation and alters ERK and Akt responses in endothelial cells.
abstract: Caveolae are plasmalemmal domains enriched with cholesterol, caveolins, and signaling molecules. Endothelial cells in vivo are continuously exposed to shear conditions, and their caveolae density and location may be different from that of static cultured cells. Here, we show that chronic shear exposure regulates formation and localization of caveolae and caveolin-1 in bovine aortic endothelial cells (BAEC). Chronic exposure (1 or 3 days) of BAEC to laminar shear increased the total number of caveolae by 45-48% above static control. This increase was due to a rise in the luminal caveolae density without changing abluminal caveolae numbers or increasing caveolin-1 mRNA and protein levels. Whereas some caveolin-1 was found in the plasma membrane in static-cultured cells, it was predominantly localized in the Golgi. In contrast, chronic shear-exposed cells showed intense caveolin-1 staining in the luminal plasma membrane with minimum Golgi association. The preferential luminal localization of caveolae may play an important role in endothelial mechanosensing. Indeed, we found that chronic shear exposure (preconditioning) altered activation patterns of two well-known shear-sensitive signaling molecules (ERK and Akt) in response to a step increase in shear stress. ERK activation was blunted in shear preconditioned cells, whereas the Akt response was accelerated. These results suggest that chronic shear stimulates caveolae formation by translocating caveolin-1 from the Golgi to the luminal plasma membrane and alters cell signaling responses.
authors.affiliation: Wallace H. Coulter Dept. of Biomedical Engineering at Georgia Tech and Emory University, Atlanta, GA 30322, USA.
authors.forename: Nolan L
authors.initials: NL
authors.lastname: Boyd
authors.forename: Heonyong
authors.initials: H
authors.lastname: Park
authors.forename: Hong
authors.initials: H
authors.lastname: Yi
authors.forename: Yong Chool
authors.initials: YC
authors.lastname: Boo
authors.forename: George P
authors.initials: GP
authors.lastname: Sorescu
authors.forename: Michelle
authors.initials: M
authors.lastname: Sykes
authors.forename: Hanjoong
authors.initials: H
authors.lastname: Jo
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000166:cytology; D001161:Arteriosclerosis / Q000378:metabolism / Q000503:physiopathology; D002417:Cattle; D021941:Caveolae / Q000201:enzymology* / Q000648:ultrastructure; D051242:Caveolin 1; D022461:Caveolins / Q000235:genetics / Q000378:metabolism; D002452:Cell Count; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D048429:Cell Size / Q000502:physiology; D002478:Cells, Cultured; D002908:Chronic Disease; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D015870:Gene Expression / Q000502:physiology; D006056:Golgi Apparatus / Q000378:metabolism / Q000648:ultrastructure; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D008854:Microscopy, Electron; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger / Q000032:analysis; D013314:Stress, Mechanical
chemical_list: D051242:Caveolin 1; D022461:Caveolins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases