title: Ca²⁺ entry via Trpm2 is essential for cardiac myocyte bioenergetics maintenance.
abstract: Ubiquitously expressed Trpm2 channel limits oxidative stress and preserves mitochondrial function. We first demonstrated that intracellular Ca(2+) concentration increase after Trpm2 activation was due to direct Ca(2+) influx and not indirectly via reverse Na(+)/Ca(2+) exchange. To elucidate whether Ca(2+) entry via Trpm2 is required to maintain cellular bioenergetics, we injected adenovirus expressing green fluorescent protein (GFP), wild-type (WT) Trpm2, and loss-of-function (E960D) Trpm2 mutant into left ventricles of global Trpm2 knockout (gKO) or WT hearts. Five days post-injection, gKO-GFP heart slices had higher reactive oxygen species (ROS) levels but lower oxygen consumption rate (OCR) than WT-GFP heart slices. Trpm2 but not E960D decreased ROS and restored OCR in gKO hearts back to normal levels. In gKO myocytes expressing Trpm2 or its mutants, Trpm2 but not E960D reduced the elevated mitochondrial superoxide (O2(.-)) levels in gKO myocytes. After hypoxia-reoxygenation (H/R), Trpm2 but not E906D or P1018L (inactivates Trpm2 current) lowered O2(.-) levels in gKO myocytes and only in the presence of extracellular Ca(2+), indicating sustained Ca(2+) entry is necessary for Trpm2-mediated preservation of mitochondrial function. After ischemic-reperfusion (I/R), cardiac-specific Trpm2 KO hearts exhibited lower maximal first time derivative of LV pressure rise (+dP/dt) than WT hearts in vivo. After doxorubicin treatment, Trpm2 KO mice had worse survival and lower +dP/dt. We conclude 1) cardiac Trpm2-mediated Ca(2+) influx is necessary to maintain mitochondrial function and protect against H/R injury; 2) Ca(2+) influx via cardiac Trpm2 confers protection against H/R and I/R injury by reducing mitochondrial oxidants; and 3) Trpm2 confers protection in doxorubicin cardiomyopathy.
authors.affiliation: Center of Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania; Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pennsylvania; and.
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Hoffman
authors.affiliation: Department of Pediatrics, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania.
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Miller
authors.affiliation: Center of Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania;
authors.forename: JuFang
authors.initials: J
authors.lastname: Wang
authors.affiliation: Center of Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania;
authors.forename: John W
authors.initials: JW
authors.lastname: Elrod
authors.affiliation: Center of Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania; Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pennsylvania; and.
authors.forename: Sudasan
authors.initials: S
authors.lastname: Rajan
authors.affiliation: Center of Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania;
authors.forename: Erhe
authors.initials: E
authors.lastname: Gao
authors.affiliation: Center of Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania;
authors.forename: Jianliang
authors.initials: J
authors.lastname: Song
authors.affiliation: Center of Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania;
authors.forename: Xue-Qian
authors.initials: XQ
authors.lastname: Zhang
authors.affiliation: Department of Pediatrics, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania.
authors.forename: Iwona
authors.initials: I
authors.lastname: Hirschler-Laszkiewicz
authors.affiliation: Center of Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania; Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pennsylvania; and.
authors.forename: Santhanam
authors.initials: S
authors.lastname: Shanmughapriya
authors.affiliation: Center of Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania;
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Koch
authors.affiliation: Center of Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania;
authors.forename: Arthur M
authors.initials: AM
authors.lastname: Feldman
authors.affiliation: Center of Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania; Department of Biochemistry, Temple University School of Medicine, Philadelphia, Pennsylvania; and.
authors.forename: Muniswamy
authors.initials: M
authors.lastname: Madesh
authors.affiliation: Center of Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania; Division of Nephrology, Temple University School of Medicine, Philadelphia, Pennsylvania; Joseph.cheung@tuhs.temple.edu.
authors.forename: Joseph Y
authors.initials: JY
authors.lastname: Cheung
mesh_terms: D000200:Action Potentials; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D009202:Cardiomyopathies / Q000139:chemically induced / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D004195:Disease Models, Animal; D004317:Doxorubicin; D004734:Energy Metabolism; D057809:HEK293 Cells; D006801:Humans; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008929:Mitochondria, Heart / Q000378:metabolism; D009154:Mutation; D009200:Myocardial Contraction; D015428:Myocardial Reperfusion Injury / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D032383:Myocytes, Cardiac / Q000378:metabolism*; D018384:Oxidative Stress; D010101:Oxygen Consumption; D017382:Reactive Oxygen Species / Q000378:metabolism; D050053:TRPM Cation Channels / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection; D016277:Ventricular Function, Left; D017725:Ventricular Pressure
chemical_list: D017382:Reactive Oxygen Species; D050053:TRPM Cation Channels; C544443:TRPM2 protein, mouse; D004317:Doxorubicin; D002118:Calcium
keywords: cardiac Trpm2 currents; doxorubicin cardiomyopathy; hypoxia-reoxygenation; ischemic cardiomyopathy; mitochondrial superoxide; voltage-independent Ca2+ channels