Collins HE, Zhu-Mauldin X, Marchase RB, Chatham JC. STIM1/Orai1-mediated SOCE: current perspectives and potential roles in cardiac function and pathology. Am J Physiol Heart Circ Physiol 305: H446 -H458, 2013. First published June 21, 2013 doi:10.1152/ajpheart.00104.2013.-Store-operated Ca 2ϩ entry (SOCE) is critical for Ca 2ϩ signaling in nonexcitable cells; however, its role in the regulation of cardiomyocyte Ca 2ϩ homeostasis has only recently been investigated. The increased understanding of the role of stromal interaction molecule 1 (STIM1) in regulating SOCE combined with recent studies demonstrating the presence of STIM1 in cardiomyocytes provides support that this pathway co-exists in the heart with the more widely recognized Ca 2ϩ handling pathways associated with excitation-contraction coupling. There is now substantial evidence that STIM1-mediated SOCE plays a key role in mediating cardiomyocyte hypertrophy, both in vitro and in vivo, and there is growing support for the contribution of SOCE to Ca 2ϩ overload associated with ischemia/reperfusion injury. Here, we provide an overview of our current understanding of the molecular regulation of SOCE and discuss the evidence supporting the role of STIM1/Orai1-mediated SOCE in regulating cardiomyocyte function.store-operated Ca 2ϩ entry; stromal interaction molecule 1; orai1; cardiomyocytes STORE-OPERATED CA 2ϩ ENTRY (SOCE), also known as capacitative calcium entry (CCE), is the major mechanism of Ca 2ϩ entry in nearly all nonexcitable cells (97, 99). In addition, it is increasingly recognized to co-exist with voltage-gated Ca 2ϩ channels in excitable cells, including neurons, skeletal muscle cells, and cardiomyocytes (1,38,45,83,121). In response to inositol 1,4,5-triphosphate (IP 3 )-(43) or ryanodine receptor (RyR)-mediated (3) Ca 2ϩ release from ER/SR stores, SOCE facilitates the influx of Ca 2ϩ from the extracellular space, resulting in a sustained increase in cytosolic Ca 2ϩ levels. Thus, although one of the roles of SOCE is to rapidly refill the depleted ER/SR stores, the subsequent sustained increase in cytosolic Ca 2ϩ also regulates numerous gene transcription pathways (33,50,151). Indeed, aberrant SOCE has been observed in a growing number of diseases including severe combined immunodeficiency, acute pancreatitis, and Alzheimer's disease (86).The integration of SOCE into well-established models of Ca 2ϩ homeostasis was hampered for many years by the lack of specific molecular mediators; even as recently as 2004 there was considerable controversy as to the specific mechanisms regulating SOCE (90, 113). However, in 2005, stromal interaction molecule 1 (STIM1) was found to localize to the ER/SR membrane and shown to function as a primary mediator of SOCE (54, 102). The putative physiological and pathophysiological roles of SOCE and STIM1 that have been identified to date are summarized in Table 1. A number of studies have recently reported the presence of STIM1 in adult cardiomyocytes (37,59,153), and consistent with earlier evidence supporting a rol...

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Background: Levels of cellular protein O-GlcNAc modification increase in response to stress, but mechanism not understood. Results: Glucose deprivation and heat shock-induced increase in O-GlcNAcylation are attenuated by CaMKII inhibition. Conclusion: CaMKII activation plays a key role in regulating the stress-induced increase in O-GlcNAc. Significance: Understanding the regulation of O-GlcNAcylation is critical in determining its role in cellular stress responses.