Regulation of Vascular Endothelial Growth Factor Splicing from pro-angiogenic to anti-angiogenic isoforms - a novel therapeutic strategy for angiogenesis
J Biol Chem 285, 5532-5540 (2010) - PMID: 19906640
Authors: *Nowak, DG, *Amin, E, Rennel, E, Hoareau-Aveilla, C, Gammons, M, Damodaran, G, Hagiwara, M, Harper, S, Woolard ,J, Ladomery, M*, Bates, D* joint senior authors and joint first authors
Vascular endothelial growth factor (VEGF) is produced either as a pro-angiogenic or anti-angiogenic protein depending upon splice site choice in the terminal, eighth exon. Proximal splice site selection (PSS) in exon 8 generates pro-angiogenic isoforms such as VEGF, and distal splice site selection (DSS) results in anti-angiogenic isoforms such as VEGFb. Cellular decisions on splice site selection depend upon the activity of RNA-binding splice factors, such as ASF/SF2, which have previously been shown to regulate VEGF splice site choice. To determine the mechanism by which the pro-angiogenic splice site choice is mediated, we investigated the effect of inhibition of ASF/SF2 phosphorylation by SR protein kinases (SRPK1/2) on splice site choice in epithelial cells and in in vivo angiogenesis models. Epithelial cells treated with insulin-like growth factor-1 (IGF-1) increased PSS and produced more VEGF and less VEGFb. This down-regulation of DSS and increased PSS was blocked by protein kinase C inhibition and SRPK1/2 inhibition. IGF-1 treatment resulted in nuclear localization of ASF/SF2, which was blocked by SPRK1/2 inhibition. Pull-down assay and RNA immunoprecipitation using VEGF mRNA sequences identified an 11-nucleotide sequence required for ASF/SF2 binding. Injection of an SRPK1/2 inhibitor reduced angiogenesis in a mouse model of retinal neovascularization, suggesting that regulation of alternative splicing could be a potential therapeutic strategy in angiogenic pathologies.
Keywords: Alternative splicing,VEGF,SRPK1