title: Modulation of long-term endothelial-barrier integrity is conditional to the cross-talk between Akt and Src signaling.
abstract: Although numerous studies have implicated Akt and Src kinases in vascular endothelial growth factor (VEGF) and Angiopoietin-1 (Ang-1)-induced endothelial-barrier regulation, a link between these two pathways has never been demonstrated. We determined the long-term effects of Akt inhibition on Src activity and vice versa, and in turn, on the human microvascular endothelial cell (HMEC) barrier integrity at the basal level, and in response to growth factors. Our data showed that Akt1 gene knockdown increases gap formation in HMEC monolayer at the basal level. Pharmacological inhibition of Akt, but not Src resulted in exacerbated VEGF-induced vascular leakage and impaired Ang-1-induced HMEC-barrier protection in vitro at 24 hr. Whereas inhibition of Akt had no effect on VEGF-induced HMEC gap formation in the short term, inhibition of Src blunted this process. In contrast, inhibition of Akt disrupted the VEGF and Ang-1 stabilized barrier integrity in the long-term while inhibition of Src did not. Interestingly, both long-term Akt inhibition and Akt1 gene knockdown in HMECs resulted in increased Tyr416 phosphorylation of Src. Treatment of HMECs with transforming growth factor-β1 (TGFβ1) that inhibited Akt Ser473 phosphorylation in the long-term, activated Src through increased Tyr416 phosphorylation and decreased HMEC-barrier resistance. The effect of TGFβ1 on endothelial-barrier breakdown was blunted in Akt1 deficient HMEC monolayers, where endothelial-barrier resistance was already impaired compared to the control. To our knowledge, this is the first report demonstrating a direct cross-talk between Akt and Src in endothelial-barrier regulation.
authors.affiliation: Clinical and Experimental Therapeutics, University of Georgia and Charlie Norwood VA Medical Center, Augusta, Georgia.|Department of Urology, The First Affiliated Hospital of Chongqing University, Chongqing, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Gao
authors.affiliation: Clinical and Experimental Therapeutics, University of Georgia and Charlie Norwood VA Medical Center, Augusta, Georgia.
authors.forename: Harika
authors.initials: H
authors.lastname: Sabbineni
authors.affiliation: Clinical and Experimental Therapeutics, University of Georgia and Charlie Norwood VA Medical Center, Augusta, Georgia.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Artham
authors.affiliation: Clinical and Experimental Therapeutics, University of Georgia and Charlie Norwood VA Medical Center, Augusta, Georgia.|Department of Medicine and Vascular Biology Center, Augusta University, Augusta, Georgia.
authors.forename: Payaningal R
authors.initials: PR
authors.lastname: Somanath
mesh_terms: D042683:Angiopoietin-1 / Q000494:pharmacology; D002199:Capillary Permeability / Q000187:drug effects; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology*; D006801:Humans; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D012694:Serine; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014162:Transfection; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology; D014443:Tyrosine; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D042683:Angiopoietin-1; D047428:Protein Kinase Inhibitors; D053773:Transforming Growth Factor beta1; D042461:Vascular Endothelial Growth Factor A; D014443:Tyrosine; D012694:Serine; D019061:src-Family Kinases; C494918:AKT1 protein, human; D051057:Proto-Oncogene Proteins c-akt
keywords: Akt; Src; VE-cadherin; endothelial-barrier; vascular permeability