title: Vascular proinflammatory responses by aldosterone are mediated via c-Src trafficking to cholesterol-rich microdomains: role of PDGFR.
abstract: OBJECTIVE
  We demonstrated c-Src activation as a novel non-genomic signalling pathway for aldosterone in vascular smooth muscle cells (VSMCs). Here, we investigated molecular mechanisms and biological responses of this phenomenon, focusing on the role of lipid rafts/caveolae and platelet-derived growth factor receptor (PDGFR) in c-Src-regulated proinflammatory responses by aldosterone.
  
  
  RESULTS
  Studies were performed in cultured VSMCs from Wistar-Kyoto (WKY) rats and caveolin-1 knockout (Cav 1(-/-)) and wild-type mice. Aldosterone stimulation increased c-Src phosphorylation and trafficking to lipid rafts/caveolae. Cholesterol depletion with methyl-β-cyclodextrin abrogated aldosterone-induced phosphorylation of c-Src and its target, Pyk2. Aldosterone effects were recovered by cholesterol reload. Aldosterone-induced c-Src and cortactin phosphorylation was reduced in caveolin-1-silenced and Cav 1(-/-) VSMCs. PDGFR is phosphorylated by aldosterone within cholesterol-rich fractions of VSMCs. AG1296, a PDGFR inhibitor, prevented c-Src phosphorylation and translocation to cholesterol-rich fractions. Aldosterone induced an increase in adhesion molecule protein content and promoted monocyte adhesion to VSMCs, responses that were inhibited an by cholesterol depletion, caveolin-1 deficiency, AG1296 and PP2, a c-Src inhibitor. Mineralocorticoid receptor (MR) content in flotillin-2-rich fractions and co-immunoprecipitation with c-Src and PDGFR increased upon aldosterone stimulation, indicating MR-lipid raft/signalling association.
  
  
  CONCLUSIONS
  We demonstrate that aldosterone-mediated c-Src trafficking/activation and proinflammatory signalling involve lipid rafts/caveolae via PDGFR.
authors.affiliation: Ottawa Hospital Research Institute, University of Ottawa, Ottawa, ON, Canada. gcallera@uottawa.ca
authors.forename: Glaucia E
authors.initials: GE
authors.lastname: Callera
authors.forename: Alvaro
authors.initials: A
authors.lastname: Yogi
authors.forename: Ana M
authors.initials: AM
authors.lastname: Briones
authors.forename: Augusto C I
authors.initials: AC
authors.lastname: Montezano
authors.forename: Ying
authors.initials: Y
authors.lastname: He
authors.forename: Rita C A
authors.initials: RC
authors.lastname: Tostes
authors.forename: Ernesto L
authors.initials: EL
authors.lastname: Schiffrin
authors.forename: Rhian M
authors.initials: RM
authors.lastname: Touyz
mesh_terms: D000450:Aldosterone / Q000494:pharmacology*; D000818:Animals; D000081247:CSK Tyrosine-Protein Kinase; D021941:Caveolae / Q000502:physiology; D002784:Cholesterol / Q000502:physiology*; D007249:Inflammation / Q000139:chemically induced*; D021962:Membrane Microdomains / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010766:Phosphorylation; D021381:Protein Transport; D011505:Protein-Tyrosine Kinases / Q000502:physiology*; D051381:Rats; D011921:Rats, Inbred WKY; D018161:Receptors, Mineralocorticoid / Q000502:physiology; D017479:Receptors, Platelet-Derived Growth Factor / Q000502:physiology*; D019061:src-Family Kinases
chemical_list: D018161:Receptors, Mineralocorticoid; D000450:Aldosterone; D002784:Cholesterol; D011505:Protein-Tyrosine Kinases; D017479:Receptors, Platelet-Derived Growth Factor; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases