title: Oxidative species increase arginase activity in endothelial cells through the RhoA/Rho kinase pathway.
abstract: OBJECTIVE
  NO produced by endothelial NOS is needed for normal vascular function. During diabetes, aging and hypertension, elevated levels of arginase can compete with NOS for available l-arginine, reducing NO and increasing superoxide (O(2) (.-)) production via NOS uncoupling. Elevated O(2) (.-) combines with NO to form peroxynitrite (ONOO(-)), further reducing NO. Oxidative species increase arginase activity, but the mechanism(s) involved are not known. Our study determined the mechanism involved in peroxynitrite and hydrogen peroxide-induced enhancement in endothelial arginase activity. We hypothesized that oxidative species increase arginase activity through PKC-activated RhoA/Rho kinase (ROCK) pathway.
  
  
  METHODS
  Arginase activity/expression was analysed in bovine aortic endothelial cells (BAEC) treated with an ONOO(-) generator (SIN-1) or H(2) O(2). Pretreatment with inhibitors of Rho kinase (Y-27632) or PKC (Gö6976) was used to investigate the mechanism involved in arginase activation.
  
  
  RESULTS
  Exposure to SIN-1 (25 µM, 24 h) or H(2) O(2) (25 µM, 8 h) increased arginase I expression and arginase activity (35% and 50%, respectively), which was prevented by ROCK inhibitor, Y-27632, PKC inhibitor, Gö6976 or siRNA to p115-Rho GEF. There was an early activation of p115-Rho GEF (SIN-1, 2 h; H(2) O(2), 1 h) and Rho A (SIN-1, 4 h; H(2) O(2), 1 h) that was prevented by using the PKC inhibitor. Exposure to SIN-1 and H(2) O(2 ) also reduced NOS activity, which was blocked by pretreatment with p115-RhoGEF siRNA.
  
  
  CONCLUSIONS
  Our data indicate that the oxidative species ONOO(-) and H(2) O(2) increase arginase activity/expression through PKC-mediated activation of RhoA/Rho kinase pathway.
authors: Department of Pharmacology and Toxicology, Medical College of Georgia, Georgia Health Sciences University, Augusta, Georgia, USA.
authors: S
authors: S
authors: Chandra
authors: M J
authors: MJ
authors: Romero
authors: A
authors: A
authors: Shatanawi
authors: A M
authors: AM
authors: Alkilany
authors: R B
authors: RB
authors: Caldwell
authors: R W
authors: RW
authors: Caldwell
mesh_terms: D000818:Animals; D001119:Arginase / Q000378:metabolism*; D002227:Carbazoles / Q000494:pharmacology; D002417:Cattle; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008981:Molsidomine / Q000031:analogs & derivatives* / Q000494:pharmacology; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D064067:Rho Guanine Nucleotide Exchange Factors; D015398:Signal Transduction / Q000187:drug effects; D054460:rho-Associated Kinases / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: D002227:Carbazoles; D004791:Enzyme Inhibitors; D020662:Guanine Nucleotide Exchange Factors; D020030:Nitric Oxide Donors; D016877:Oxidants; D064067:Rho Guanine Nucleotide Exchange Factors; C081021:Go 6976; C002385:linsidomine; D006861:Hydrogen Peroxide; D008981:Molsidomine; D019001:Nitric Oxide Synthase; D054460:rho-Associated Kinases; D011493:Protein Kinase C; D001119:Arginase; D020742:rhoA GTP-Binding Protein