TRPM2 channels protect against cardiac ischemia-reperfusion injury: role of mitochondria.
Cardiac TRPM2 channels were activated by intracellular adenosine diphosphate-ribose and blocked by flufenamic acid. In adult cardiac myocytes the ratio of GCa to GNa of TRPM2 channels was 0.56 ± 0.02. To explore the cellular mechanisms by which TRPM2 channels protect against cardiac ischemia/reperfusion (I/R) injury, we analyzed proteomes from WT and TRPM2 KO hearts subjected to I/R. The canonical pathways that exhibited the largest difference between WT-I/R and KO-I/R hearts were mitochondrial dysfunction and the tricarboxylic acid cycle. Complexes I, III, and IV were down-regulated, whereas complexes II and V were up-regulated in KO-I/R compared with WT-I/R hearts. Western blots confirmed reduced expression of the Complex I subunit and other mitochondria-associated proteins in KO-I/R hearts. Bioenergetic analyses revealed that KO myocytes had a lower mitochondrial membrane potential, mitochondrial Ca(2+) uptake, ATP levels, and O2 consumption but higher mitochondrial superoxide levels. Additionally, mitochondrial Ca(2+) uniporter (MCU) currents were lower in KO myocytes, indicating reduced mitochondrial Ca(2+) uptake was likely due to both lower ψm and MCU activity. Similar to isolated myocytes, O2 consumption and ATP levels were also reduced in KO hearts. Under a simulated I/R model, aberrant mitochondrial bioenergetics was exacerbated in KO myocytes. Reactive oxygen species levels were also significantly higher in KO-I/R compared with WT-I/R heart slices, consistent with mitochondrial dysfunction in KO-I/R hearts. We conclude that TRPM2 channels protect the heart from I/R injury by ameliorating mitochondrial dysfunction and reducing reactive oxygen species levels.
From the Center of Translational Medicine.
Barbara A
BA
Miller
Nicholas E
NE
Hoffman
Salim
S
Merali
Xue-Qian
XQ
Zhang
JuFang
J
Wang
Sudarsan
S
Rajan
Santhanam
S
Shanmughapriya
Erhe
E
Gao
Carlos A
CA
Barrero
Karthik
K
Mallilankaraman
Jianliang
J
Song
Tongda
T
Gu
Iwona
I
Hirschler-Laszkiewicz
Walter J
WJ
Koch
Arthur M
AM
Feldman
Muniswamy
M
Madesh
Joseph Y
JY
Cheung
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004579:Electron Transport; D004594:Electrophysiology; D057809:HEK293 Cells; D006321:Heart / Q000503:physiopathology; D006352:Heart Ventricles / Q000378:metabolism; D006801:Humans; D008297:Male; D008564:Membrane Potentials; D051379:Mice; D018345:Mice, Knockout; D008928:Mitochondria / Q000378:metabolism*; D032342:Muscle Cells / Q000166:cytology; D017202:Myocardial Ischemia / Q000473:pathology; D010100:Oxygen / Q000737:chemistry; D010101:Oxygen Consumption; D040901:Proteomics; D017382:Reactive Oxygen Species / Q000378:metabolism; D015427:Reperfusion Injury / Q000473:pathology*; D050053:TRPM Cation Channels / Q000378:metabolism*
D017382:Reactive Oxygen Species; D050053:TRPM Cation Channels; C544443:TRPM2 protein, mouse; D000255:Adenosine Triphosphate; D010100:Oxygen; D002118:Calcium
Calcium Channels; Cardiac Ischemia; Cardiovascular Disease; Electrophysiology; Global Proteomics Analysis; Mitochondria; Mitochondrial Bioenergetics; TRP Channels