Modulation of endothelial nitric oxide synthase by fibronectin.
Nitric oxide (NO) produced by the action of endothelial nitric oxide synthase (eNOS) plays an important role in the regulation of vascular tone, cell survival, and angiogenesis. Interaction of endothelial cells (ECs) with a fibronectin (FN) rich matrix is important in the regulation of EC function and survival during angiogenesis. The present study was carried out to examine if FN can regulate eNOS and thereby NO levels in ECs. The activity and the levels of mRNA and protein of eNOS were significantly low in HUVECs maintained in culture on FN. Inhibition of p38 MAPK and blocking the interaction of FN with alpha(5)beta(1) integrin using antibody caused the reversal of the FN effect. Immunoblot analysis of Ser/Thr phosphorylation of purified eNOS suggested that FN downregulates post-translational phosphorylation of eNOS at Ser residues. These results suggest that FN negatively modulates eNOS in an alpha(5)beta(1) integrin-p38 MAPK-dependent pathway.
Viji
R I
RI
Department of Biochemistry, University of Kerala, Thiruvananthapuram, Kerala, 695 581, India.
Kumar
V B Sameer
VB
Kiran
M S
MS
Sudhakaran
P R
PR
D017209:Apoptosis / Q000502:physiology; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism*; D006801:Humans; D039081:Integrin alpha5beta1 / Q000378:metabolism; D019331:NG-Nitroarginine Methyl Ester / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D011107:Polylysine / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D015398:Signal Transduction / Q000502:physiology; D014157:Transcription Factors / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D004791:Enzyme Inhibitors; D005353:Fibronectins; D039081:Integrin alpha5beta1; D009573:Nitrites; D014157:Transcription Factors; D011107:Polylysine; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; D052250:Nitric Oxide Synthase Type III; D048051:p38 Mitogen-Activated Protein Kinases; D019331:NG-Nitroarginine Methyl Ester