Trpm2 enhances physiological bioenergetics and protects against pathological oxidative cardiac injury: Role of Pyk2 phosphorylation

Abstract

The mechanisms by which Trpm2 channels enhance mitochondrial bioenergetics and protect against oxidative stress‐induced cardiac injury remain unclear. Here, the role of proline‐rich tyrosine kinase 2 (Pyk2) in Trpm2 signaling is explored. Activation of Trpm2 in adult myocytes with H2O2 resulted in 10‐ to 21‐fold increases in Pyk2 phosphorylation in wild‐type (WT) myocytes which was significantly lower (~40%) in Trpm2 knockout (KO) myocytes. Pyk2 phosphorylation was inhibited (~54%) by the Trpm2 blocker clotrimazole. Buffering Trpm2‐mediated Ca2+ increase with 1,2‐bis(2‐aminophenoxy)ethane‐N,N,N′,N′‐tetraacetic acid (BAPTA) resulted in significantly reduced pPyk2 in WT but not in KO myocytes, indicating Ca2+ influx through activated Trpm2 channels phosphorylated Pyk2. Part of phosphorylated Pyk2 translocated from cytosol to mitochondria which has been previously shown to augment mitochondrial Ca2+ uptake and enhance adenosine triphosphate generation. Although Trpm2‐mediated Ca2+ influx phosphorylated Ca2+‐calmodulin kinase II (CaMKII), the CaMKII inhibitor KN93 did not significantly affect Pyk2 phosphorylation in H2O2‐treated WT myocytes. After ischemia/reperfusion (I/R), Pyk2 phosphorylation and its downstream prosurvival signaling molecules (pERK1/2 and pAkt) were significantly lower in KO‐I/R when compared with WT‐I/R hearts. After hypoxia/reoxygenation, mitochondrial membrane potential was lower and superoxide level was higher in KO myocytes, and were restored to WT values by the mitochondria‐targeted superoxide scavenger MitoTempo. Our results suggested that Ca2+ influx via tonically activated Trpm2 phosphorylated Pyk2, part of which translocated to mitochondria, resulting in better mitochondrial bioenergetics to maintain cardiac health. After I/R, Pyk2 activated prosurvival signaling molecules and prevented excessive increases in reactive oxygen species, thereby affording protection from I/R injury.

TRPM2 channel-mediated cell death: An important mechanism linking oxidative stress-inducing pathological factors to associated pathological conditions

“…This study provided further evidence by expressing the mutant TRPM2 channel with impaired Ca 2+ permeability in cardiomyocytes to show that TRPM2-mediated Ca 2+ influx into cardiomyocytes is critical in the maintenance of mitochondrial function and protection against myocardial I/R injury. Moreover, as shown in a more recent study [ 170 ], exposure to H 2 O 2 (200 μM for 15 min) increased the phosphorylation levels of the Ca 2+ -sensitive proline‐rich tyrosine kinase PYK2, and downstream pro-survival signalling molecules ERK1/2 and Akt in WT adult mouse cardiomyocytes, which was attenuated by TRPM2-KO and also by treatment with the intracellular Ca 2+ chelator BAPTA-AM. In addition, exposure to H 2 O 2 promoted the translocation of PYK2 from the cytosol to mitochondria in WT adult mouse cardiomyocytes.…”

“…Miller and colleagues provide evidence, however, that favours an opposing role of the TRPM2 channel in cardiomyocytes, namely, that the TRPM2 channel protects against ROS-induced cardiomyocyte death and myocardial I/R injury and thereby preserves cardiac function [ 96 , [167] , [168] , [169] , [170] ]. As shown in an earlier study using ventricular myocytes isolated from adult mice [ 169 ], exposure to H 2 O 2 (200 μM) increased intracellular Ca 2+ concentration that was dependent on extracellular Ca 2+ and reduced by treatment with CTZ.…”

TRPM2‐mediated extracellular Ca2+ entry promotes acinar cell necrosis in biliary acute pancreatitis

“…Although the expression of TRPM2 has been demonstrated previously in different cell types, including inflammatory cells (Yamamoto et al 2008), myocytes (Miller et al 2019) and epithelial cells (Liu et al 2013), to our knowledge, this is the first report demonstrating the expression of TRPM2 in the exocrine pancreas. Using conventional PCR and immunolabelling techniques, the expression of TRPM2 in the basolateral membrane of acinar cells and on the luminal membrane of ductal cells was confirmed.…”

“…), myocytes (Miller et al . ) and epithelial cells (Liu et al . ), to our knowledge, this is the first report demonstrating the expression of TRPM2 in the exocrine pancreas.…”

TRPM2 Oxidation Activates Two Distinct Potassium Channels in Melanoma Cells through Intracellular Calcium Increase

“…Related to the aberrant proliferation and the often hypoxic environment, most cancers are characterized by enhanced oxidative stress [39,40], which can be directly sensed by various TRP channels, including TRPV1 [41], TRPV2 [17], and TRPM2 [42]. Interestingly, TRPM2 is implicated in several physiological and pathological pathways involving oxidative stress, and its activation has been generally associated with a large increase in intracellular Ca 2+ [43][44][45][46][47][48].…”