What is the role of the histidine rich calcium binding protein (HRC) in cardiomyopathy?
['The histidine-rich Ca-binding protein (HRC) is a Ca-storage protein in cardiac sarcoplasmic reticulum. Recent transgenic studies revealed that this protein inhibits the maximal rates of sarcoplasmic reticulum Ca-transport, leading to cardiac dysfunction. In view of the role of sarcoplasmic reticulum Ca-cycling in myocardial ischemia/reperfusion injury, we designed this study to gain further insight into the role of HRC during ischemia/reperfusion.', 'Our findings suggest that increased cardiac HRC expression protects against ischemia/reperfusion injury in the heart, resulting in improved recovery of function and reduced infarction.', 'The histidine-rich calcium binding protein (HRC) Ser96Ala polymorphism was shown to correlate with ventricular arrhythmias and sudden death only in dilated cardiomyopathy patients', 'The HRC(S96A) mutant exacerbated the inhibitory effects of HRC(WT) on the amplitude of Ca(2+) transients, prolongation of Ca(2+) decay time, and caffeine-induced sarcoplasmic reticulum Ca(2+) release. Consistent with these findings, HRC(S96A) reduced maximal sarcoplasmic reticulum calcium uptake rate to a higher extent than HRC(WT). Furthermore, the frequency of spontaneous Ca(2+) sparks, which was reduced by HRC(WT), was increased by mutant HRC(S96A) under resting conditions although there were no spontaneous Ca(2+) waves under stress conditions. However, expression of the HRC(S96A) genetic variant in cardiomyocytes from a rat model of postmyocardial infarction heart failure induced dramatic disturbances of rhythmic Ca(2+) transients. These findings indicate that the HRC Ser96Ala variant increases the propensity of arrhythmogenic Ca(2+) waves in the stressed failing heart, suggesting a link between this genetic variant and life-threatening ventricular arrhythmias in human carriers.']
['The histidine-rich Ca-binding protein (HRC), a 165 kDa sarcoplasmic reticulum (SR) protein, regulates SR Ca cycling during excitation–contraction coupling.  HRC mutations or polymorphisms lead to cardiac dysfunction.  The Ser96Ala genetic variant of HRC is associated with life-threatening ventricular arrhythmias and sudden death in idiopathic dilated cardiomyopathy (DCM).']
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