Anchorage of VEGF to the extracellular matrix conveys differential signaling responses to endothelial cells.
VEGF can be secreted in multiple isoforms with variable affinity for extracellular proteins and different abilities to induce vascular morphogenesis, but the molecular mechanisms behind these effects remain unclear. Here, we show molecular distinctions between signaling initiated from soluble versus matrix-bound VEGF, which mediates a sustained level of VEGFR2 internalization and clustering. Exposure of endothelial cells to matrix-bound VEGF elicits prolonged activation of VEGFR2 with differential phosphorylation of Y1214, and extended activation kinetics of p38. These events require association of VEGFR2 with beta1 integrins. Matrix-bound VEGF also promotes reciprocal responses on beta1 integrin by inducing its association with focal adhesions; a response that is absent upon exposure to soluble VEGF. Inactivation of beta1 integrin blocks the prolonged phosphorylation of Y1214 and consequent activation of p38. Combined, these results indicate that when in the context of extracellular matrix, activation of VEGFR2 is distinct from that of soluble VEGF in terms of recruitment of receptor partners, phosphorylation kinetics, and activation of downstream effectors.
Chen
Tom T
TT
Department of Molecular, Cellular, and Developmental Biology, University of California, Los Angeles, Los Angeles, CA 90095, USA.
Luque
Alfonso
A
Lee
Sunyoung
S
Anderson
Sean M
SM
Segura
Tatiana
T
Iruela-Arispe
M Luisa
ML
D000818:Animals; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D005109:Extracellular Matrix / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D022001:Focal Adhesions / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D011485:Protein Binding / Q000187:drug effects; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D034421:Sus scrofa; D014443:Tyrosine / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D019012:Integrin beta1; D020033:Protein Isoforms; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D014443:Tyrosine; D003094:Collagen; D040301:Vascular Endothelial Growth Factor Receptor-2; D048051:p38 Mitogen-Activated Protein Kinases