title: Thymosin-β4-mediated therapeutic neovascularization: role of the PI3K/AKT pathway.
abstract: OBJECTIVE
  Thymosin β4 (Tβ4) is known to have pro-angogenic abilities in vitro and in vivo, and its cardioprotective effect is PI3/AKT-dependent. Tβ4-induced vessel formation requires transcriptional activation via the MRTF/SRF pathway. However, the relevance of PI3/AKT signaling for Tβ4-induced angiogenesis remains unclear. Here, we analyzed the PI3K/AKT cascade after Tβ4 transduction in models of chronic hindlimb ischemia.
  
  
  METHODS
  Tube formation assays of endothelial cells transfected with Tβ4 ± AKT-dn or PI3Kα/Rho inhibition were performed. In mice, rAAV.Tβ4 was injected (intramuscular [i.m.]) 14 days before femoral artery ligation. In addition, either rAAV.AKT-dn was co-applied or Rho/PI3K/AKT pathways were inhibited. Capillary density and hindlimb perfusion were obtained. In rabbits, chronic ischemia was induced by femoral artery excision and subsequent i.m. injection of rAAV.Tβ4 ± rAAV.AKT-dn. Analyses of capillary density, collateral formation and perfusion were performed.
  
  
  RESULTS
  Tβ4-induced ring formation was blunted by inhibiting the Rho-kinase (ROCK) or the PI3K/AKT pathway. In vivo, Tβ4 transduction induced angiogenesis and perfusion, an effect abrogated by inhibition of Rho-signaling, or PI3Kα/AKT. In the rabbit model, inhibition of AKT in the lower limb not only abolished angiogenesis but also collateral formation.
  
  
  CONCLUSIONS
  Tβ4 requires PI3Kα/AKT pathway signaling for induction of therapeutic neovascularization in ischemic limb disease.
authors: Deutsches Herzzentrum München, Technische Universität , Munich , Germany.
authors: Teresa
authors: T
authors: Trenkwalder
authors: Elisabeth
authors: E
authors: Deindl
authors: Dario
authors: D
authors: Bongiovanni
authors: Seungmin
authors: S
authors: Lee
authors: Heribert
authors: H
authors: Schunkert
authors: Christian
authors: C
authors: Kupatt
authors: Rabea
authors: R
authors: Hinkel
mesh_terms: D000818:Animals; D000229:Dependovirus; D004730:Endothelium, Vascular / Q000502:physiology*; D005260:Female; D015316:Genetic Therapy; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018919:Neovascularization, Physiologic / Q000235:genetics / Q000502:physiology*; D051058:Oncogene Protein v-akt / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology*; D051057:Proto-Oncogene Proteins c-akt / Q000502:physiology*; D011817:Rabbits; D015398:Signal Transduction / Q000235:genetics; D013947:Thymosin / Q000235:genetics / Q000502:physiology*; D014162:Transfection; D000099201:Thymosin beta(4)
chemical_list: D051058:Oncogene Protein v-akt; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D013947:Thymosin; D000099201:Thymosin beta(4)
keywords: AKT; PI3 kinase; chronic ischemia; gene therapy; thymosin β4