title: M-LDH physically associated with sarcolemmal K ATP channels mediates cytoprotection in heart embryonic H9C2 cells.
abstract: Muscle form of lactate dehydrogenase (M-LDH) physically associate with K(ATP) channel subunits, Kir6.2 and SUR2A, and is an integral part of the ATP-sensitive K(+) (K(ATP)) channel protein complex in the heart. Here, we have shown that concomitant introduction of viral constructs containing truncated and mutated forms of M-LDH (Delta M-LDH) and 193gly-M-LDH respectively, generate a phenotype of rat heart embryonic H9C2 cells that do not contain functional M-LDH as a part of the K(ATP) channel protein complex. The K(+) current was increased in wild type cells, but not in cells expressing Delta M-LDH/193gly-M-LDH, when they were exposed to chemical hypoxia induced by 2,4 dinitrophenol (DNP; 10mM). At the same time, the outcome of chemical hypoxia was much worse in Delta M-LDH/193gly-M-LDH phenotype than in the control one, and that was associated with increased loss of intracellular ATP in cells infected with Delta M-LDH/193gly-M-LDH. On the other hand, cells expressing Kir6.2AFA, a Kir6.2 mutant that abolishes K(ATP) channel conductance without affecting intracellular ATP levels, survived chemical hypoxia much better than cells expressing Delta M-LDH/193gly-M-LDH. Based on the obtained results, we conclude that M-LDH physically associated with Kir6.2/SUR2A regulates the activity of sarcolemmal K(ATP) channels as well as an intracellular ATP production during metabolic stress, both of which are important for cell survival.
authors.affiliation: Division of Medical Sciences, Centre for Cardiovascular and Lung Biology, Ninewells Hospital & Medical School, University of Dundee, Dundee DD1 9SY, Scotland, UK.
authors.forename: Sofija
authors.initials: S
authors.lastname: Jovanović
authors.forename: Qingyou
authors.initials: Q
authors.lastname: Du
authors.forename: Andriy
authors.initials: A
authors.lastname: Sukhodub
authors.forename: Aleksandar
authors.initials: A
authors.lastname: Jovanović
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D015687:Cell Hypoxia; D002460:Cell Line; D002470:Cell Survival; D019610:Cytoprotection; D005799:Genes, Dominant; D006321:Heart / Q000196:embryology*; D042541:Intracellular Space / Q000378:metabolism; D015640:Ion Channel Gating; D054086:KATP Channels; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D009132:Muscles / Q000201:enzymology*; D032383:Myocytes, Cardiac / Q000166:cytology* / Q000201:enzymology*; D024661:Potassium Channels, Inwardly Rectifying / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D012508:Sarcolemma / Q000378:metabolism*; D000099161:Kcnj11 Channel
chemical_list: D000255:Adenosine Triphosphate; D054086:KATP Channels; D007770:L-Lactate Dehydrogenase; D024661:Potassium Channels, Inwardly Rectifying; D000099161:Kcnj11 Channel