Gene delivery of Kir6.2/SUR2A in conjunction with pinacidil handles intracellular Ca2+ homeostasis under metabolic stress.
Metabolic injury is a complex process affecting various tissues, with intracellular Ca2+ loading recognized as a common precipitating event leading to cell death. We have recently observed that cells overexpressing recombinant ATP-sensitive K+ (KATP) channel subunits may acquire resistance against metabolic stress. To examine whether, under metabolic challenge, intracellular Ca2+ homeostasis can be maintained by an activator of channel proteins, we delivered Kir6.2 and SUR2A genes, which encode KATP channel subunits, into a somatic cell line lacking native KATP channels. Hypoxia-reoxygenation was simulated by application and removal of the mitochondrial poison 2,4 dinitrophenol. Under such metabolic stress, Ca2+ loading was induced by Ca2+ influx during hypoxia and release of Ca2+ from intracellular stores during reoxygenation. Delivery of Kir6.2/SUR2A genes, in conjunction with the KATP channel activator pinacidil, prevented intracellular Ca2+ loading irrespective of whether the channel opener was applied throughout the duration of hypoxia-reoxygenation or transiently during the hypoxic or reoxygenation stage. In all stages of injury, the effect of pinacidil was inhibited by the selective antagonist of KATP channel, 5-hydroxydecanoate. The present study provides evidence that combined use of gene delivery and pharmacological targeting of recombinant proteins can handle intracellular Ca2+ homeostasis under hypoxia-reoxygenation irrespective of the stage of the metabolic insult.
Jovanović
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Division of Cardiovascular Diseases, Department of Internal Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA.
Jovanović
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Jovanović
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Terzic
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D000818:Animals; D019556:COS Cells; D002118:Calcium / Q000378:metabolism*; D015687:Cell Hypoxia; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism; D017136:Ion Transport / Q000187:drug effects; D018384:Oxidative Stress; D020110:Pinacidil / Q000494:pharmacology*; D015221:Potassium Channels / Q000235:genetics* / Q000378:metabolism*; D024661:Potassium Channels, Inwardly Rectifying; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D011994:Recombinant Proteins; D020110:Pinacidil; D002118:Calcium