Phosphatidylinositide 3-kinase is important in late-stage fibroblast growth factor-1-mediated angiogenesis in vivo.
We previously reported that overexpression of a secreted version of fibroblast growth factor-1 (sp-FGF-1) has the ability to induce angiogenesis in the chicken chorioallantoic membrane (CAM). In our current study, we examine the effects of sp-FGF-1 through a time course analysis of angiogenesis in the chicken CAM on days 3, 4, and 5 after gene transfection. Significant angiogenesis was observed on days 4 and 5 after gene transfection in the CAM assay. To evaluate the role of phosphatidylinositide 3-kinase (PI3K) signaling in sp-FGF-1-induced angiogenesis, we analyzed mRNA expression levels of PI3K and protein activity through its immediate downstream target, AKT-1. We found upregulation of both PI3K and AKT mRNA expression levels in day 5 sp-FGF-1 versus day 5 vector control-transfected CAMs. Furthermore, by blocking PI3K phosphorylation using the specific inhibitor, LY294002, we found that downstream phosphorylation of AKT-1 was inhibited. More importantly, the blockade of the PI3K pathway via LY294002 in sp-FGF-1-transfected CAMs significantly inhibited angiogenesis. These results further elucidate the molecular mechanisms of the sp-FGF-1 signaling pathway and it underscores the importance of PI3K signaling in FGF-1-stimulated angiogenesis in vivo. It also provides a basis for the role of sp-FGF-1 in the development of therapeutic treatments to combat vascular insufficiencies and angiogenesis-dependent cancers.
Weylie
Brian
B
Department of Medical Physiology and Cardiovascular Research Institute, Texas A&M University System Health Science Center, College of Medicine, Temple, TX, USA.
Zhu
James
J
Singh
Ugra
U
Ambrus
Sandy
S
Forough
Reza
R
D000818:Animals; D002642:Chick Embryo; D002645:Chickens; D049033:Chorioallantoic Membrane / Q000098:blood supply* / Q000502:physiology; D002867:Chromones / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016220:Fibroblast Growth Factor 1 / Q000235:genetics / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology; D018919:Neovascularization, Physiologic / Q000187:drug effects / Q000502:physiology*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D021122:Protein Subunits / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014162:Transfection; D015854:Up-Regulation
D002867:Chromones; D004791:Enzyme Inhibitors; D016220:Fibroblast Growth Factor 1; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D021122:Protein Subunits; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one