title: Phosphoinositide 3-kinase gamma gene knockout impairs postischemic neovascularization and endothelial progenitor cell functions.
abstract: OBJECTIVE
  We evaluated whether phosphatidylinositol 3-kinase gamma (PI3Kgamma) plays a role in reparative neovascularization and endothelial progenitor cell (EPC) function.
  
  
  RESULTS
  Unilateral limb ischemia was induced in mice lacking the PI3Kgamma gene (PI3Kgamma-/-) or expressing a catalytically inactive mutant (PI3Kgamma(KD/KD)) and wild-type controls (WT). Capillarization and arteriogenesis were reduced in PI3Kgamma-/- ischemic muscles resulting in delayed reperfusion compared with WT, whereas reparative neovascularization was preserved in PI3Kgamma(KD/KD). In PI3Kgamma-/- muscles, endothelial cell proliferation was reduced, apoptosis was increased, and interstitial space was infiltrated with leukocytes but lacked cKit+ progenitor cells that in WT muscles typically surrounded arterioles. PI3Kgamma is constitutively expressed by WT EPCs, with expression levels being upregulated by hypoxia. PI3Kgamma-/- EPCs showed a defect in proliferation, survival, integration into endothelial networks, and migration toward SDF-1. The dysfunctional phenotype was associated with nuclear constraining of FOXO1, reduced Akt and eNOS phosphorylation, and decreased nitric oxide (NO) production. Pretreatment with an NO donor corrected the migratory defect of PI3Kgamma-/- EPCs. PI3Kgamma(KD/KD) EPCs showed reduced Akt phosphorylation, but constitutive activation of eNOS and preserved proliferation, survival, and migration.
  
  
  CONCLUSIONS
  We newly demonstrated that PI3Kgamma modulates angiogenesis, arteriogenesis, and vasculogenesis by mechanisms independent from its kinase activity.
authors.affiliation: Bristol Heart Institute, University of Bristol, Upper Maudlin Street, Bristol, BS2 8HW, UK. madeddu@yahoo.com
authors.forename: Paolo
authors.initials: P
authors.lastname: Madeddu
authors.forename: Nicolle
authors.initials: N
authors.lastname: Kraenkel
authors.forename: Luciola S
authors.initials: LS
authors.lastname: Barcelos
authors.forename: Mauro
authors.initials: M
authors.lastname: Siragusa
authors.forename: Paola
authors.initials: P
authors.lastname: Campagnolo
authors.forename: Atsuhiko
authors.initials: A
authors.lastname: Oikawa
authors.forename: Andrea
authors.initials: A
authors.lastname: Caporali
authors.forename: Andrew
authors.initials: A
authors.lastname: Herman
authors.forename: Ornella
authors.initials: O
authors.lastname: Azzolino
authors.forename: Laura
authors.initials: L
authors.lastname: Barberis
authors.forename: Alessia
authors.initials: A
authors.lastname: Perino
authors.forename: Federico
authors.initials: F
authors.lastname: Damilano
authors.forename: Costanza
authors.initials: C
authors.lastname: Emanueli
authors.forename: Emilio
authors.initials: E
authors.lastname: Hirsch
mesh_terms: D000818:Animals; D058544:Class Ib Phosphatidylinositol 3-Kinase; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000502:physiology*; D005121:Extremities / Q000098:blood supply; D007511:Ischemia / Q000503:physiopathology*; D007527:Isoenzymes / Q000235:genetics / Q000502:physiology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009130:Muscle, Smooth / Q000502:physiology; D018919:Neovascularization, Physiologic / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000502:physiology*; D013234:Stem Cells / Q000502:physiology*; D019737:Transplants
chemical_list: D007527:Isoenzymes; D019869:Phosphatidylinositol 3-Kinases; D058544:Class Ib Phosphatidylinositol 3-Kinase; C546764:Pik3cg protein, mouse