title: Combinatory action of VEGFR2 and MAP kinase pathways maintains endothelial-cell integrity.
abstract: Blood vessels normally maintain stereotyped lumen diameters and their stable structures are crucial for vascular function. However, very little is known about the molecular mechanisms controlling the maintenance of vessel diameters and the integrity of endothelial cells. We investigated this issue in zebrafish embryos by a chemical genetics approach. Small molecule libraries were screened using live Tg(kdrl:GRCFP)(zn1) transgenic embryos in which endothelial cells are specifically labeled with GFP. By analyzing the effects of compounds on the morphology and function of embryonic blood vessels after lumen formation, PP1, a putative Src kinase inhibitor, was identified as capable of specifically reducing vascular lumen size by interrupting endothelial-cell integrity. The inhibitory effect is not due to Src or general VEGF signaling inhibition because another Src inhibitor and Src morpholino as well as several VEGFR inhibitors failed to produce a similar phenotype. After profiling a panel of 22 representative mammalian kinases and surveying published data, we selected a few possible new candidates. Combinational analysis of these candidate kinase inhibitors established that PP1 induced endothelial collapse by inhibiting both the VEGFR2 and MAP kinase pathways. More importantly, combinatory use of two clinically approved drugs Dasatinib and Sunitinib produced the same phenotype. This is the first study to elucidate the pathways controlling maintenance of endothelial integrity using a chemical genetics approach, indicating that endothelial integrity is controlled by the combined action of the VEGFR2 and MAP kinase pathways. Our results also suggest the possible side effect of the combination of two anticancer drugs on the circulatory system.
authors.affiliation: Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University, Shenzhen Graduate School, Shenzhen University Town, Shenzhen 518055, China.
authors.forename: Hanbing
authors.initials: H
authors.lastname: Zhong
authors.forename: Danyang
authors.initials: D
authors.lastname: Wang
authors.forename: Nan
authors.initials: N
authors.lastname: Wang
authors.forename: Yesenia
authors.initials: Y
authors.lastname: Rios
authors.forename: Haigen
authors.initials: H
authors.lastname: Huang
authors.forename: Song
authors.initials: S
authors.lastname: Li
authors.forename: Xinrong
authors.initials: X
authors.lastname: Wu
authors.forename: Shuo
authors.initials: S
authors.lastname: Lin
mesh_terms: D000818:Animals; D004625:Embryo, Nonmammalian / Q000098:blood supply* / Q000187:drug effects; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D020935:MAP Kinase Signaling System / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018919:Neovascularization, Physiologic / Q000187:drug effects*; D011720:Pyrazoles / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015027:Zebrafish / Q000196:embryology; D019061:src-Family Kinases / Q000037:antagonists & inhibitors
chemical_list: C108123:4-amino-5-(4-methylphenyl)-7-(tert-butyl)pyrazolo(3,4-d)pyrimidine; D004791:Enzyme Inhibitors; D011720:Pyrazoles; D011743:Pyrimidines; D040301:Vascular Endothelial Growth Factor Receptor-2; D019061:src-Family Kinases; D020928:Mitogen-Activated Protein Kinases