C-Terminus of Heat Shock Protein 70–Interacting Protein–Dependent GTP Cyclohydrolase I Degradation in Lambs with Increased Pulmonary Blood Flow
Year: 2010
Type: article
Abstract: We showed that nitric oxide (NO) signaling is decreased in the pulmonary vasculature before the development of endothelial dysfunction in a lamb model of congenital heart disease and increased pulmonary blood flow (Shunt). The elucidation of the molecular mechanism by which this occurs was the purpose of this study. Here, we demonstrate that concentrations of the endogenous NO synthase (NOS) inhibitor, asymmetric dimethylarginine (ADMA), are elevated, whereas the NOS cofactor tetrahydrobiopterin (BH(4)) is decreased in Shunt lambs. Our previous studies demonstrated that ADMA decreases heat shock protein-90 (Hsp90) chaperone activity, whereas other studies suggest that guanosine-5'-triphosphate cyclohydrolase 1 (GCH1), the rate-limiting enzyme in the generation of BH(4), may be a client protein for Hsp90. Thus, we determined whether increases in ADMA could alter GCH1 protein and activity. Our data demonstrate that ADMA decreased GCH1 protein, but not mRNA concentrations, in pulmonary arterial endothelial cells (PAECs) because of the ubiquitination and proteasome-dependent degradation of GCH1. We also found that Hsp90-GCH1 interactions were reduced, whereas the association of GCH1 with Hsp70 and the C-terminus of Hsp70-interacting protein (CHIP) increased in ADMA-exposed PAECs. The overexpression of CHIP potentiated, whereas a CHIP U-box domain mutant attenuated, ADMA-induced GCH1 degradation and reductions in cellular BH(4) concentrations. We also found in vivo that Hsp90/GCH1 interactions are decreased, whereas GCH1-Hsp70 and GCH1-CHIP interactions and GCH1 ubiquitination are increased. Finally, we found that supplementation with l-arginine restored Hsp90-GCH1 interactions and increased both BH(4) and NO(x) concentrations in Shunt lambs. In conclusion, increased concentrations of ADMA can indirectly alter NO signaling through decreased cellular BH(4) concentrations, secondary to the disruption of Hsp90-GCH1 interactions and the CHIP-dependent proteasomal degradation of GCH1.
Authors: Xutong Sun, Sohrab Fratz, Shruti Sharma, Yali Hou, Ruslan Rafikov, Sanjiv Kumar, Imran Rehmani, Jing Tian, Anita Smith, Christian Schreiber, Judith Reiser, Susanne Naumann, Sebastian Haag, John Hess, John D. Catravas, Cam Patterson, Jeffery R. Fineman, Stephen M. Black
Language: English
Subfield: Physiology (medical)
Field: Medicine
Domain: Health Sciences
Open Access status: green
Funders: American Heart Association, Fondation Leducq, National Institutes of Health, National Heart, Lung, and Blood Institute, National Institute of General Medical Sciences, National Institute of Environmental Health Sciences, Eunice Kennedy Shriver National Institute of Child Health and Human Development
Awards: G1587067858, G2148221198, G2279855079, G2784643556, Perinatal Pulmonary Hypertension: Developmental Mediators, ROS in Pulmonary Hypertension: Role of ADMA, NO-mediated signaling in endothelial cells, Role of altered carnitine metabolism in perinatal endothelial dysfunction, CHIP: A link between the chaperone and proteasome system, VASCULAR ANTI-INFLAMMATORY ACTIONS OF HSP90 INHIBITORS, G741329215, ENOS Dimer Disruption and Endothelial Dysfunction, Metabolic reprogramming of smooth muscle cells in pulmonary hypertension, Research Training in Pediatric Critical Care Medicine, UNC Center for Environmental Health and Susceptibility
OpenAlex ID: W2040754116