Extracellular signal-regulated protein kinase/Jun kinase cross-talk underlies vascular endothelial cell growth factor-induced endothelial cell proliferation.
Ligand binding to vascular endothelial cell growth factor (VEGF) receptors activates the mitogen-activated protein kinases extracellular signal-regulated kinase (ERK) and c-Jun N-terminal protein kinase (JNK). Possible cross-communication of ERK and JNK effecting endothelial cell (EC) actions of VEGF is poorly understood. Incubation of EC with PD 98059, a specific mitogen-activated protein kinase kinase inhibitor, or transfection with Y185F, a dominant negative ERK2, strongly inhibited VEGF-activated JNK. JNK was also activated by ERK2 expression in the absence of VEGF, inhibited 82% by co-transfection with dominant negative SEK-1, indicating upstream activation of JNK by ERK. VEGF-stimulated JNK activity was also reversed by dominant negative SEK-1. Other EC growth factors exhibited similar cross-activation of JNK through ERK. VEGF stimulated the nuclear incorporation of thymidine, reversed 89% by PD 98059 and 72% by Y185F. Dominant negative SEK-1 or JNK-1 also significantly reduced VEGF-stimulated thymidine incorporation. Expression of wild type Jip-1, which prevents JNK nuclear translocation, inhibited VEGF-induced EC proliferation by 75%. VEGF stimulated both cyclin D1 synthesis and Cdk4 kinase activity, inhibited by PD 98059 and dominant negative JNK-1. Important events for VEGF-induced G1/S progression and cell proliferation are enhanced through a novel ERK to JNK cross-activation and subsequent JNK action.
Pedram
A
A
Division of Endocrinology, Veterans Affairs Medical Center, Long Beach, Long Beach, California 90822, USA.
Razandi
M
M
Levin
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ER
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002417:Cattle; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D016228:Endothelial Growth Factors / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology; D004789:Enzyme Activation; D048031:JNK Mitogen-Activated Protein Kinases; D008222:Lymphokines / Q000494:pharmacology*; D020928:Mitogen-Activated Protein Kinases; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D008222:Lymphokines; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases