title: RhoA activation mediates phosphatidylinositol 3-kinase-dependent proliferation of human vascular endothelial cells: an alloimmune mechanism of chronic allograft nephropathy.
abstract: HLA class I ligation on graft endothelial cells (EC) has been shown to promote graft arteriosclerosis and chronic allograft nephropathy. This study investigated transcriptional and functional changes mediated by anti-HLA antibodies (Ab), developed by transplant recipient, on vascular renal EC. For mimicking interactions that occur between alloantibodies and graft endothelium, HLA-typed primary cultures of human EC were incubated in vitro in the presence of monomorphic or polymorphic anti-HLA class I Ab. Gene expression analysis identified the upregulation of several molecules involved in cell signaling and proliferation, including the GTP-binding protein RhoA. It was demonstrated further that HLA class I ligation on EC induced a rapid translocation of RhoA to the cell membrane associated with F-actin stress fiber formation and cytoskeleton reorganization. Western blot analysis showed that anti-HLA class I Ab induced, in addition to RhoA, the activation of phosphatidylinositol 3-kinase, reflected by the phosphorylation of Akt (Ser473) and GSK3beta (Ser9), in EC. C3 exoenzyme, an inhibitor of RhoA, inhibited RhoA translocation in response to HLA class I ligation and reduced phosphatidylinositol 3-kinase activation. EC proliferation and cell cycle progression, examined by 5,6-carboxyfluorescein diacetate succinimidyl ester staining, demonstrated that anti-HLA-induced EC proliferation was efficiently prevented by the 3-hydroxy-3-methylglutaryl CoA reductase inhibitor simvastatin (0.1 micromol/L) through inhibition of RhoA geranylgeranylation. Taken together, these findings support the conclusion that RhoA is a key mediator of signaling pathways that lead to cytoskeletal reorganization and EC proliferation in response to alloantibodies that bind to HLA class I and demonstrate the specific and potent inhibitory effect of simvastatin on allostimulated EC growth.
authors.affiliation: INSERM U643, 30 bd J. Monnet, 44093 Nantes Cedex 01, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Coupel
authors.forename: Fabrice
authors.initials: F
authors.lastname: Leboeuf
authors.forename: Gwénola
authors.initials: G
authors.lastname: Boulday
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Soulillou
authors.forename: Béatrice
authors.initials: B
authors.lastname: Charreau
mesh_terms: D002455:Cell Division / Q000187:drug effects; D002908:Chronic Disease; D003599:Cytoskeleton / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D015870:Gene Expression / Q000276:immunology; D005805:Genes, MHC Class I / Q000276:immunology; D006801:Humans; D007674:Kidney Diseases / Q000209:etiology / Q000276:immunology*; D016030:Kidney Transplantation / Q000009:adverse effects* / Q000276:immunology*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D017368:Protein Prenylation / Q000187:drug effects; D019821:Simvastatin / Q000494:pharmacology; D014181:Transplantation Immunology / Q000276:immunology*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism / Q000502:physiology*
chemical_list: C066737:RHOA protein, human; D019821:Simvastatin; D019869:Phosphatidylinositol 3-Kinases; D020742:rhoA GTP-Binding Protein