Pinning GRK2 in place to protect the heart
In addition to its role in terminating signaling mediated by activated G protein–coupled receptors, the kinase GRK2 also localizes to mitochondria to regulate cell survival and metabolism in a manner dependent on phosphorylation of Ser670 by ERK. Sato et al. found that mice that expressed a mutant form of GRK2 that could not undergo this phosphorylation event showed decreased mitochondrial accumulation of the mutant GRK2, reduced cardiac necrosis, and improved cardiac function after ischemia-reperfusion injury. Compared to those from wild-type mice, cardiomyocytes from mice expressing the nonphosphorylatable form of GRK2 were better able to maintain a normal metabolism when subjected to ischemia-reperfusion injury in vitro. These results show that preventing GRK2 from translocating to mitochondria after myocardial infarction is cardioprotective.
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