Homocysteine impaired endothelial function through compromised vascular endothelial growth factor/Akt/endothelial nitric oxide synthase signalling.
1. Hyperhomocysteinaemia (HHcy) is associated with endothelial dysfunction and has been recognized as a risk factor of cardiovascular disease. The present study aimed to investigate the effect of homocysteine (Hcy) on endothelial function in vivo and in vitro, and the underlying signalling pathways. 2. The HHcy animal model was established by intragastric administration with l-methionine in rats. Plasma Hcy and nitric oxide (NO) concentration were measured by fluorescence immunoassay or nitrate reductase method, respectively. Vasorelaxation in response to acetylcholine and sodium nitroprusside were carried out on aortic rings. Human umbilical vein endothelial cells (HUVEC) were treated with indicated concentrations of Hcy in the in vitro experiments. Intracellular NO level and NO concentration in culture medium were assayed. The alterations of possible signalling proteins were detected by western blot analysis. 3. l-methionine administration induced a significant increase in plasma Hcy and decrease in plasma NO. Endothelium-dependent relaxation of aortic rings in response to acetylcholine was impaired in l-methionine-administrated rats. The in vitro study showed that Hcy reduced both intracellular and culture medium NO levels. Furthermore, Hcy decreased phosphorylation of endothelial nitric oxide synthase (eNOS) at serine-1177 and phosphorylation of Akt at serine-473. Hcy-induced dephosphorylation of eNOS at Ser-1177 was partially reversed by insulin (Akt activator) and GF109203X (PKC inhibitor). Furthermore, Hcy reduced vascular endothelial growth factor (VEGF) expression in a dose-dependent manner. 4. In conclusion, Hcy impaired endothelial function through compromised VEGF/Akt/endothelial nitric oxide synthase signalling. These findings will be beneficial for further understanding the role of Hcy in cardiovascular disease.
Yan
Ting-Ting
TT
Department of Pathophysiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.
Li
Qian
Q
Zhang
Xuan-Hong
XH
Wu
Wei-Kang
WK
Sun
Juan
J
Li
Lin
L
Zhang
Quan
Q
Tan
Hong-Mei
HM
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000378:metabolism; D015153:Blotting, Western; D018929:Cell Culture Techniques; D002460:Cell Line; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000201:enzymology / Q000378:metabolism / Q000502:physiology*; D006710:Homocysteine / Q000097:blood / Q000494:pharmacology*; D006801:Humans; D020138:Hyperhomocysteinemia / Q000097:blood / Q000201:enzymology / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D008715:Methionine; D009569:Nitric Oxide / Q000096:biosynthesis / Q000097:blood; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
D042461:Vascular Endothelial Growth Factor A; C467498:vascular endothelial growth factor A, rat; D006710:Homocysteine; D009569:Nitric Oxide; D008715:Methionine; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat; D051057:Proto-Oncogene Proteins c-akt