title: Activation of the prolyl-hydroxylase oxygen-sensing signal cascade leads to AMPK activation in cardiomyocytes.
abstract: The proline hydroxylase domain-containing enzymes (PHD) act as cellular oxygen sensors and initiate a hypoxic signal cascade to induce a range of cellular responses to hypoxia especially in the aspect of energy and metabolic homeostasis regulation. AMP-activated protein kinase (AMPK) is recognized as a major energetic sensor and regulator of cardiac metabolism. However, the effect of PHD signal on AMPK has never been studied before. A PHD inhibitor (PHI), dimethyloxalylglycine and PHD2-specific RNA interference (RNAi) have been used to activate PHD signalling in neonatal rat cardiomyocytes. Both PHI and PHD2-RNAi activated AMPK pathway in cardiomyocytes effectively. In addition, the increased glucose uptake during normoxia and enhanced myocyte viability during hypoxia induced by PHI pretreatment were abrogated substantially upon AMPK inhibition with an adenoviral vector expressing a dominant negative mutant of AMPK-α1. Furthermore, chelation of intracellular Ca2+ by BAPTA, inhibition of calmodulin-dependent kinase kinase (CaMKK) with STO-609, or RNAi-mediated down-regulation of CaMKK α inhibited PHI-induced AMPK activation significantly. In contrast, down-regulation of LKB1 with adenoviruses expressing the dominant negative form did not affect PHI-induced AMPK activation. We establish for the first time that activation of PHD signal cascade can activate AMPK pathway mainly through a Ca(2+)/CaMKK-dependent mechanism in cardiomyocytes. Furthermore, activation of AMPK plays an essential role in hypoxic protective responses induced by PHI.
authors: Institute of Burn Research, Southwest Hospital, State Key Laboratory of Trauma, Burns and Combined Injury, The Third Military Medical University, Chongqing, China.
authors: Hong
authors: H
authors: Yan
authors: Dong-Xia
authors: DX
authors: Zhang
authors: Xiaohua
authors: X
authors: Shi
authors: Qiong
authors: Q
authors: Zhang
authors: Yue-Sheng
authors: YS
authors: Huang
mesh_terms: D000091162:AMP-Activated Protein Kinase Kinases; D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000256:Adenoviridae / Q000235:genetics / Q000378:metabolism; D000600:Amino Acids, Dicarboxylic / Q000493:pharmacokinetics; D000818:Animals; D001562:Benzimidazoles / Q000494:pharmacology; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D015687:Cell Hypoxia; D002478:Cells, Cultured; D002614:Chelating Agents; D015536:Down-Regulation; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology*; D053644:Naphthalimides / Q000494:pharmacology; D010100:Oxygen / Q000378:metabolism*; D010766:Phosphorylation; D011393:Procollagen-Proline Dioxygenase / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction
chemical_list: D000600:Amino Acids, Dicarboxylic; D001562:Benzimidazoles; D002614:Chelating Agents; D053644:Naphthalimides; C458525:STO 609; D004533:Egtazic Acid; D011393:Procollagen-Proline Dioxygenase; D017346:Protein Serine-Threonine Kinases; C488755:Stk11 protein, rat; D054737:Calcium-Calmodulin-Dependent Protein Kinase Kinase; D000091162:AMP-Activated Protein Kinase Kinases; D055372:AMP-Activated Protein Kinases; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D010100:Oxygen; C040947:oxalylglycine