title: Inhibition of the AMP-activated protein kinase-α2 accentuates agonist-induced vascular smooth muscle contraction and high blood pressure in mice.
abstract: The aim of the present study was to determine the effects and molecular mechanisms by which AMP-activated protein kinase (AMPK) regulates smooth muscle contraction and blood pressure in mice. In cultured human vascular smooth muscle cells, we observed that activation of AMPK by 5-aminoimidazole-4-carboxamide 1-β-d-ribofuranoside inhibited agonist-induced phosphorylation of myosin light chain (MLC) and myosin phosphatase targeting subunit 1 (MYPT1). Conversely, AMPK inhibition with pharmacological or genetic means potentiated agonist-induced the phosphorylation of MLC and MYPT1, whereas it inhibited both Ras homolog gene family member A and Rho-associated kinase activity. In addition, AMPK activation or Rho-associated kinase inhibition with Y27632 abolished agonist-induced phosphorylation of MLC and MYPT1. Gene silencing of p190-guanosine triphosphatase-activating protein abolished the effects of AMPK activation on MLC, MYPT1, and Ras homolog gene family member A in human smooth muscle cells. Ex vivo analyses revealed that agonist-induced contractions of the mesenteric artery and aortas were stronger in both AMPKα1(-/-) and AMPKα2(-/-) knockout mice than in wild-type mice. Inhibition of Rho-associated kinase with Y27632 normalized agonist-induced contractions of AMPKα1(-/-) and AMPKα2(-/-) vessels. AMPKα2(-/-) mice had higher blood pressure along with decreased serine phosphorylation of p190-guanosine triphosphatase-activating protein. Finally, inhibition of the Ras homolog gene family member A/Rho-associated kinase pathway with Y27632, which suppressed MYPT1 and MLC phosphorylation, lowered blood pressure in AMPKα2(-/-) mice. In conclusion, AMPK decreases vascular smooth muscle cell contractility by inhibiting p190-GTP-activating protein-dependent Ras homolog gene family member A activation, indicating that AMPK may be a new therapeutic target in lowering high blood pressure.
authors.affiliation: Division of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, BSEB 325, 941 Stanton L. Young Blvd, Oklahoma City, OK 73104, USA.
authors.forename: Shuangxi
authors.initials: S
authors.lastname: Wang
authors.forename: Bin
authors.initials: B
authors.lastname: Liang
authors.forename: Benoit
authors.initials: B
authors.lastname: Viollet
authors.forename: Ming-Hui
authors.initials: MH
authors.lastname: Zou
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000620:Aminoimidazole Carboxamide / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D015153:Blotting, Western; D002478:Cells, Cultured; D006801:Humans; D051379:Mice; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D018994:Myosin Light Chains / Q000378:metabolism; D043263:Myosin-Light-Chain Phosphatase / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D012265:Ribonucleotides / Q000494:pharmacology
chemical_list: D018994:Myosin Light Chains; D012265:Ribonucleotides; D000620:Aminoimidazole Carboxamide; D055372:AMP-Activated Protein Kinases; D043263:Myosin-Light-Chain Phosphatase; C031143:AICA ribonucleotide