title: Perlecan Domain V induces VEGf secretion in brain endothelial cells through integrin α5β1 and ERK-dependent signaling pathways.
abstract: Perlecan Domain V (DV) promotes brain angiogenesis by inducing VEGF release from brain endothelial cells (BECs) following stroke. In this study, we define the specific mechanism of DV interaction with the α(5)β(1) integrin, identify the downstream signal transduction pathway, and further investigate the functional significance of resultant VEGF release. Interestingly, we found that the LG3 portion of DV, which has been suggested to possess most of DV's angio-modulatory activity outside of the brain, binds poorly to α(5)β(1) and induces less BEC proliferation compared to full length DV. Additionally, we implicate DV's DGR sequence as an important element for the interaction of DV with α(5)β(1). Furthermore, we investigated the importance of AKT and ERK signaling in DV-induced VEGF expression and secretion. We show that DV increases the phosphorylation of ERK, which leads to subsequent activation and stabilization of eIF4E and HIF-1α. Inhibition of ERK activity by U0126 suppressed DV-induced expression and secretion of VEGR in BECs. While DV was capable of phosphorylating AKT we show that AKT phosphorylation does not play a role in DV's induction of VEGF expression or secretion using two separate inhibitors, LY294002 and Akt IV. Lastly, we demonstrate that VEGF activity is critical for DV increases in BEC proliferation, as well as angiogenesis in a BEC-neuronal co-culture system. Collectively, our findings expand our understanding of DV's mechanism of action on BECs, and further support its potential as a novel stroke therapy.
authors.affiliation: Department of Molecular & Cellular Medicine, Texas A&M Health Science Center, College Station, Texas, USA.
authors.forename: Douglas N
authors.initials: DN
authors.lastname: Clarke
authors.forename: Abraham
authors.initials: A
authors.lastname: Al Ahmad
authors.forename: Boyeon
authors.initials: B
authors.lastname: Lee
authors.forename: Christi
authors.initials: C
authors.lastname: Parham
authors.forename: Lisa
authors.initials: L
authors.lastname: Auckland
authors.forename: Andrezj
authors.initials: A
authors.lastname: Fertala
authors.forename: Michael
authors.initials: M
authors.lastname: Kahle
authors.forename: Courtney S
authors.initials: CS
authors.lastname: Shaw
authors.forename: Jill
authors.initials: J
authors.lastname: Roberts
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Bix
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D002070:Butadienes / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D039561:Eukaryotic Initiation Factor-4E / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D019812:Heparan Sulfate Proteoglycans / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D039081:Integrin alpha5beta1 / Q000235:genetics / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects* / Q000235:genetics; D051379:Mice; D009025:Morpholines / Q000494:pharmacology; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D017434:Protein Structure, Tertiary; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D040262:Receptors, Vascular Endothelial Growth Factor / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism*
chemical_list: D002070:Butadienes; D002867:Chromones; D004791:Enzyme Inhibitors; D039561:Eukaryotic Initiation Factor-4E; D019812:Heparan Sulfate Proteoglycans; C497443:Hif1a protein, mouse; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D039081:Integrin alpha5beta1; D009025:Morpholines; D009570:Nitriles; D011994:Recombinant Proteins; C113580:U 0126; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; C071927:perlecan; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D040262:Receptors, Vascular Endothelial Growth Factor; D051057:Proto-Oncogene Proteins c-akt