Trpm2 enhances physiological bioenergetics and protects against pathological oxidative cardiac injury: Role of Pyk2 phosphorylation. Issue 9 (13th January 2019)

• Record Type: Journal Article
• Authors: Miller, Barbara A.; Wang, JuFang; Song, Jianliang; Zhang, Xue‐Qian; Hirschler‐Laszkiewicz, Iwona; Shanmughapriya, Santhanam; Tomar, Dhanendra; Rajan, Sudasan; Feldman, Arthur M.; Madesh, Muniswamy; Sheu, Shey‐Shing; Cheung, Joseph Y.
• Is Part Of: Journal of cellular physiology. Volume 234:Issue 9(2019:Sep.)
• Page Start: 15048
• Page End: 15060
• Publication Date: 2019-01-13
• Subjects: hypoxia‐reoxygenation -- ischemic cardiomyopathy -- mitochondrial oxidants -- oxidative injury -- voltage‐independent Ca2+ channels; Physiology -- Periodicals; Cell physiology -- Periodicals; 571.6
• DOI: 10.1002/jcp.28146
• Languages: English
• ISSNs: 0021-9541

Abstract

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 H2 O2 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 Ca 2+ 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 Ca 2+ influx through activated Trpm2 channels phosphorylated Pyk2. Part of phosphorylated Pyk2 translocated from cytosol to mitochondria which has been previously shown to augment mitochondrial Ca 2+ uptake and enhance adenosine triphosphate generation. Although Trpm2‐mediated Ca 2+ influx phosphorylated Ca 2+ ‐calmodulin kinase II (CaMKII), the CaMKII inhibitor KN93 did not significantly affect Pyk2 phosphorylation in H2 O2 ‐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 Ca 2+ 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. Abstract : Trpm2‐mediated calcium influx phosphorylates proline‐rich tyrosine kinase 2 (Pyk2) in the heart. Part of the phosphorylated Pyk2 translocate to the mitochondria resulting in enhanced mitochondrial calcium uptake.Trpm2‐mediated Pyk2 activation protects the heart from oxidative injury not only by assuring efficient electron flow during oxidative phosphorylation and thereby maintaining cellular bioenergetics and minimizing toxic levels of mitochondrial superoxide, but also by activating downstream prosurvival signaling pathways such as protein kinase B (Akt) and extracellular signal‐regulated protein kinases 1 and 2 (ERK1/2).