title: Tyrosine nitration of PA700 activates the 26S proteasome to induce endothelial dysfunction in mice with angiotensin II-induced hypertension.
abstract: The ubiquitin-proteasome system has been implicated in oxidative stress-induced endothelial dysfunction in cardiovascular diseases. However, the mechanism by which oxidative stress alters the ubiquitin-proteasome system is poorly defined. The present study was conducted to determine whether oxidative modifications of PA700, a 26S proteasome regulatory subunit, contributes to angiotensin II (Ang II)-induced endothelial dysfunction. Exposure of human umbilical vein endothelial cells to low concentrations of Ang II, but not vehicle, for 6 hours significantly decreased the levels of tetrahydro-l-biopterin (BH4), an essential cofactor of endothelial NO synthase, which was accompanied by a decrease in GTP cyclohydrolase I, the rate-limiting enzyme for de novo BH4 synthesis. In addition, Ang II increased both tyrosine nitration of PA700 and the 26S proteasome activity, which were paralleled by increased coimmunoprecipitation of PA700 and the 20S proteasome. Genetic inhibition of NAD(P)H oxidase or administration of uric acid (a peroxynitrite scavenger) or N(G)-nitro-l-arginine methyl ester (nonselective NO synthase inhibitor) significantly attenuated Ang II-induced PA700 nitration, 26S proteasome activation, and reduction of GTP cyclohydrolase I and BH4. Finally, Ang II infusion in mice decreased the levels of both BH4 and GTP cyclohydrolase I and impaired endothelial-dependent relaxation in isolated aortas, and all of these effects were prevented by the administration of MG132, a potent inhibitor for 26S proteasome. We conclude that Ang II increases tyrosine nitration of PA700 resulting in accelerated GTP cyclohydrolase I degradation, BH4 deficiency, and consequent endothelial dysfunction in hypertension.
authors: Division of Endocrinology and Diabetes, Department of Medicine, University of Oklahoma Health Sciences Center, 941 Stanton L. Young Blvd, Oklahoma City, OK 73104, USA. ming-hui-zou@ouhsc.edu
authors: Jian
authors: J
authors: Xu
authors: Shuangxi
authors: S
authors: Wang
authors: Yong
authors: Y
authors: Wu
authors: Ping
authors: P
authors: Song
authors: Ming-Hui
authors: MH
authors: Zou
mesh_terms: D000804:Angiotensin II / Q000633:toxicity; D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D001708:Biopterins / Q000031:analogs & derivatives / Q000378:metabolism; D001794:Blood Pressure / Q000187:drug effects; D002478:Cells, Cultured; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism / Q000503:physiopathology*; D006136:GTP Cyclohydrolase / Q000378:metabolism; D006801:Humans; D006973:Hypertension / Q000139:chemically induced / Q000378:metabolism / Q000503:physiopathology*; D066298:In Vitro Techniques; D007976:Leupeptins / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D009566:Nitrates / Q000378:metabolism; D030421:Peroxynitrous Acid / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism*; D061988:Proteasome Inhibitors; D034741:RNA, Small Interfering / Q000235:genetics; D014162:Transfection; D014443:Tyrosine / Q000378:metabolism*; D014664:Vasodilation / Q000187:drug effects
chemical_list: D015853:Cysteine Proteinase Inhibitors; D007976:Leupeptins; D009566:Nitrates; C085834:PA700 proteasome activator; D061988:Proteasome Inhibitors; D034741:RNA, Small Interfering; D000804:Angiotensin II; D030421:Peroxynitrous Acid; D001708:Biopterins; D014443:Tyrosine; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D006136:GTP Cyclohydrolase; C003402:sapropterin; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde