title: Asymmetric Dimethylarginine Stimulates Akt1 Phosphorylation via Heat Shock Protein 70-Facilitated Carboxyl-Terminal Modulator Protein Degradation in Pulmonary Arterial Endothelial Cells.
abstract: Asymmetric dimethylarginine (ADMA) induces the mitochondrial translocation of endothelial nitric oxide synthase (eNOS) through the nitration-mediated activation of Akt1. However, it is recognized that the activation of Akt1 requires phosphorylation events at threonine (T) 308 and serine (S) 473. Thus, the current study was performed to elucidate the potential effect of ADMA on Akt1 phosphorylation and the mechanisms that are involved. Exposure of pulmonary arterial endothelial cells to ADMA enhanced Akt1 phosphorylation at both threonine 308 and Ser473 without altering Akt1 protein levels, phosphatase and tensin homolog activity, or membrane Akt1 levels. Heat shock protein (Hsp) 90 plays a pivotal role in maintaining Akt1 activity, and our results demonstrate that ADMA decreased Hsp90-Akt1 interactions, but, surprisingly, overexpression of a dominant-negative Hsp90 mutant increased Akt1 phosphorylation. ADMA exposure or overexpression of dominant-negative Hsp90 increased Hsp70 levels, and depletion of Hsp70 abolished ADMA-induced Akt1 phosphorylation. ADMA decreased the interaction of Akt1 with its endogenous inhibitor, carboxyl-terminal modulator protein (CTMP). This was mediated by the proteasomal-dependent degradation of CTMP. The overexpression of CTMP attenuated ADMA-induced Akt1 phosphorylation at Ser473, eNOS phosphorylation at Ser617, and eNOS mitochondrial translocation. Finally, we found that the mitochondrial translocation of eNOS in our lamb model of pulmonary hypertension is associated with increased Akt1 and eNOS phosphorylation and reduced Akt1-CTMP protein interactions. In conclusion, our data suggest that CTMP is directly involved in ADMA-induced Akt1 phosphorylation in vitro and in vivo, and that increasing CTMP levels may be an avenue to treat pulmonary hypertension.
authors.affiliation: 1 Department of Medicine, Division of Translational and Regenerative Medicine, The University of Arizona, Tucson, Arizona.
authors.forename: Xutong
authors.initials: X
authors.lastname: Sun
authors.affiliation: 1 Department of Medicine, Division of Translational and Regenerative Medicine, The University of Arizona, Tucson, Arizona.
authors.forename: Manuela
authors.initials: M
authors.lastname: Kellner
authors.affiliation: 1 Department of Medicine, Division of Translational and Regenerative Medicine, The University of Arizona, Tucson, Arizona.
authors.forename: Ankit A
authors.initials: AA
authors.lastname: Desai
authors.affiliation: 1 Department of Medicine, Division of Translational and Regenerative Medicine, The University of Arizona, Tucson, Arizona.
authors.forename: Ting
authors.initials: T
authors.lastname: Wang
authors.affiliation: 2 Department of Neuroscience and Regenerative Medicine, Georgia Regents University, Augusta, Georgia.
authors.forename: Qing
authors.initials: Q
authors.lastname: Lu
authors.affiliation: 1 Department of Medicine, Division of Translational and Regenerative Medicine, The University of Arizona, Tucson, Arizona.
authors.forename: Archana
authors.initials: A
authors.lastname: Kangath
authors.affiliation: 1 Department of Medicine, Division of Translational and Regenerative Medicine, The University of Arizona, Tucson, Arizona.
authors.forename: Ning
authors.initials: N
authors.lastname: Qu
authors.affiliation: 1 Department of Medicine, Division of Translational and Regenerative Medicine, The University of Arizona, Tucson, Arizona.
authors.forename: Christina
authors.initials: C
authors.lastname: Klinger
authors.affiliation: 3 Pediatric Cardiology and Congenital Heart Disease, German Heart Center at the Technical University of Munich, Munich, Germany.
authors.forename: Sohrab
authors.initials: S
authors.lastname: Fratz
authors.affiliation: 1 Department of Medicine, Division of Translational and Regenerative Medicine, The University of Arizona, Tucson, Arizona.
authors.forename: Jason X-J
authors.initials: JX
authors.lastname: Yuan
authors.affiliation: 4 Department of Medicine, University of Illinois Chicago, Chicago, Illinois; and.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Jacobson
authors.affiliation: 1 Department of Medicine, Division of Translational and Regenerative Medicine, The University of Arizona, Tucson, Arizona.
authors.forename: Joe G N
authors.initials: JG
authors.lastname: Garcia
authors.affiliation: 1 Department of Medicine, Division of Translational and Regenerative Medicine, The University of Arizona, Tucson, Arizona.
authors.forename: Ruslan
authors.initials: R
authors.lastname: Rafikov
authors.affiliation: 5 Department of Pediatrics and.|6 Cardiovascular Research Institute, University of California San Francisco, San Francisco, California.
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Fineman
authors.affiliation: 1 Department of Medicine, Division of Translational and Regenerative Medicine, The University of Arizona, Tucson, Arizona.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Black
mesh_terms: D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D002352:Carrier Proteins / Q000378:metabolism*; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D005799:Genes, Dominant; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D018841:HSP90 Heat-Shock Proteins; D008168:Lung / Q000098:blood supply; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D059748:Proteolysis / Q000187:drug effects*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D011651:Pulmonary Artery / Q000473:pathology*; D012039:Regional Blood Flow / Q000187:drug effects; D012756:Sheep; D054875:Ubiquitination / Q000187:drug effects
chemical_list: D002352:Carrier Proteins; D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; C018524:N,N-dimethylarginine; D001120:Arginine; D052250:Nitric Oxide Synthase Type III; D051057:Proto-Oncogene Proteins c-akt; D046988:Proteasome Endopeptidase Complex
keywords: Akt1; asymmetric dimethylarginine; mitochondrion; proteasome