title: Activation of the AMP-activated protein kinase (AMPK) by nitrated lipids in endothelial cells.
abstract: The AMP-activated protein kinase (AMPK) is an important regulator of endothelial metabolic and functional homeostasis. Here, we examined the regulation of AMPK by nitrated oleic acid (OA-NO(2)) and investigated the implications in endothelial function. Treatment of bovine aortic endothelial cells (BAECs) with OA-NO(2) induced a significant increase in both AMPK-Thr172 phosphorylation and AMPK activity as well as upregulation of heme oxygenase (HO)-1 and hypoxia-inducible factor (HIF)-1α. Pharmacologic inhibition or genetic ablation of HO-1 or HIF-1α abolished OA-NO(2)-induced AMPK phosphorylation. OA-NO(2) induced a dramatic increase in extracellular signal-regulated kinase (ERK)1/2 phosphorylation that was abrogated by the HO-1 inhibitor, zinc deuteroporphyrin IX 2,4-bis-ethylene glycol (ZnBG). Inhibition of ERK1/2 using UO126 or PD98059 reduced but did not abolish OA-NO(2)-induced HIF-1α upregulation, suggesting that OA-NO(2)/HO-1-initiated HIF-1α induction is partially dependent on ERK1/2 activity. In addition, OA-NO(2) enhanced endothelial intracellular Ca(2+), an effect that was inhibited by the HIF-1α inhibitor, YC-1, and by HIF-1α siRNA. These results implicate the involvement of HIF-1α. Experiments using the Ca(2+)/calmodulin-dependent protein kinase kinase (CaMKK) inhibitor STO-609, the selective CaMKII inhibitor KN-93, and an isoform-specific siRNA demonstrated that OA-NO(2)-induced AMPK phosphorylation was dependent on CaMKKβ. Together, these results demonstrate that OA-NO(2) activates AMPK in endothelial cells via an HO-1-dependent mechanism that increases HIF-1α protein expression and Ca(2+)/CaMKKβ activation.
authors.affiliation: Section of Molecular Medicine, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wu
authors.forename: Yunzhou
authors.initials: Y
authors.lastname: Dong
authors.forename: Ping
authors.initials: P
authors.lastname: Song
authors.forename: Ming-Hui
authors.initials: MH
authors.lastname: Zou
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000818:Animals; D001011:Aorta / Q000166:cytology; D002118:Calcium / Q000378:metabolism; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase / Q000378:metabolism; D002417:Cattle; D042783:Endothelial Cells / Q000187:drug effects* / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D051547:Heme Oxygenase-1 / Q000378:metabolism; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D015538:Nitrosation / Q000187:drug effects; D019301:Oleic Acid / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism
chemical_list: D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D019301:Oleic Acid; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D051547:Heme Oxygenase-1; D017346:Protein Serine-Threonine Kinases; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase; D048049:Extracellular Signal-Regulated MAP Kinases; D055372:AMP-Activated Protein Kinases; D002118:Calcium