Role of MSK1 in the signaling pathway leading to VEGF-mediated PAF synthesis in endothelial cells.
Vascular endothelial growth factor (VEGF) inflammatory effects require acute platelet-activating factor (PAF) synthesis by endothelial cells (EC). We previously reported that VEGF-mediated PAF synthesis involves the activation of VEGF receptor-2/Neuropilin-1 complex, which is leading to the activation of p38 and p42/44 mitogen-activated protein kinases (MAPKs) and group V secretory phospholipase A(2) (sPLA(2)-V). As the mechanisms regulating sPLA(2)-V remain unknown, we addressed the role of the mitogen- and stress-activated protein kinase-1 (MSK1), which can be rapidly and transiently activated by p38 or p42/44 MAPKs. In native bovine aortic endothelial cells (BAEC), we observed a constitutive protein interaction of MSK1 with p38, p42/44 MAPKs, and sPLA(2)-V. These protein interactions were maintained in BAEC transfected either with the empty vector pCDNA3.1, wild-type MSK1 (MSK1-WT) or N-terminal dead kinase MSK1 mutant (MSK1-D195A). However, in BAEC expressing C-terminal dead kinase MSK1 mutant (MSK1-D565A), the interaction between MSK1 and sPLA(2)-V was reduced by 82% and 90% under basal and VEGF-treated conditions as compared to native BAEC. Treatment with VEGF for 15 min increased basal PAF synthesis in native BAEC, pCDNA3.1, MSK1-WT, and MSK1-D195A by 166%, 139%, 125%, and 82%, respectively. In contrast, PAF synthesis was prevented in cells expressing MSK1-D565A mutant. These results demonstrate the essential role of the C-terminal domain of MSK1 for its constitutive interaction with sPLA(2)-V, which appears essential to support VEGF-mediated PAF synthesis.
Research Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger Street, Montreal, Quebec, Canada.
Catherine
C
Marchand
Judith
J
Favier
Martin G
MG
Sirois
D000818:Animals; D002417:Cattle; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010766:Phosphorylation / Q000187:drug effects; D010972:Platelet Activating Factor / Q000096:biosynthesis*; D011485:Protein Binding; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*
D010972:Platelet Activating Factor; D047428:Protein Kinase Inhibitors; D042461:Vascular Endothelial Growth Factor A; D038744:Ribosomal Protein S6 Kinases, 90-kDa; C116919:mitogen and stress-activated protein kinase 1; D020928:Mitogen-Activated Protein Kinases