Heterotrimeric G alpha q/G alpha 11 proteins function upstream of vascular endothelial growth factor (VEGF) receptor-2 (KDR) phosphorylation in vascular permeability factor/VEGF signaling.
Vascular permeability factor/vascular endothelial growth factor (VPF/VEGF) functions by activating two receptor-tyrosine kinases, Flt-1 (VEGF receptor (VEGFR)-1) and KDR (VEGFR-2), both of which are selectively expressed on primary vascular endothelium. KDR is responsible for VPF/VEGF-stimulated endothelial cell proliferation and migration, whereas Flt-1 down-modulates KDR-mediated endothelial cell proliferation. Our most recent works show that pertussis toxin-sensitive G proteins and Gbetagamma subunits are required for Flt-1-mediated down-regulation of human umbilical vein endothelial cell (HUVEC) proliferation and that Gq/11 proteins are required for KDR-mediated RhoA activation and HUVEC migration. In this study, we demonstrate that Gq/11 proteins are also required for VPF/VEGF-stimulated HUVEC proliferation. Our results further indicate that Gq/11 proteins specifically mediate KDR signaling such as intracellular Ca2+ mobilization rather than Flt-1-induced CDC42 activation and that a Gq/11 antisense oligonucleotide completely inhibits MAPK phosphorylation induced by KDR but has no effect on Flt-1-induced MAPK activation. More importantly, we demonstrate that Gq/11 proteins interact with KDR in vivo, and the interaction of Gq/11 proteins with KDR does not require KDR tyrosine phosphorylation. Surprisingly, the Gq/11 antisense oligonucleotide completely inhibits VPF/VEGF-stimulated KDR phosphorylation. Expression of a constitutively active mutant of G11 but not Gq can cause phosphorylation of KDR and MAPK. In addition, a Gbetagamma minigene, hbetaARK1(495), inhibits VPF/VEGF-stimulated HUVEC proliferation, MAPK phosphorylation, and intracellular Ca2+ mobilization but has no effect on KDR phosphorylation. Taken together, this study demonstrates that Gq/11 proteins mediate KDR tyrosine phosphorylation and KDR-mediated HUVEC proliferation through interaction with KDR.
Zeng
Huiyan
H
Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA.
Zhao
Dezheng
D
Yang
Suping
S
Datta
Kaustubh
K
Mukhopadhyay
Debabrata
D
D002118:Calcium / Q000378:metabolism; D002455:Cell Division / Q000502:physiology; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D016228:Endothelial Growth Factors / Q000378:metabolism / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D020962:Heterotrimeric GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism / Q000494:pharmacology; D008222:Lymphokines / Q000378:metabolism / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014443:Tyrosine / Q000378:metabolism; D014471:Umbilical Veins / Q000166:cytology; D042461:Vascular Endothelial Growth Factor A; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism*; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D016326:Extracellular Matrix Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D014443:Tyrosine; D004247:DNA; C501162:FLT1 protein, human; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2; D020928:Mitogen-Activated Protein Kinases; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D020962:Heterotrimeric GTP-Binding Proteins; D002118:Calcium