Regulation of Sarcoplasmic Reticulum Calcium Release in Heart Failure

 然而，关于RyR2在HF中磷酸化改变的机制仍存在重大争议。我们的初步数据显示，SpeG磷酸化了RyR2，S2811上的一个新的磷酸化位点。此外，我们的数据表明，充血性心力衰竭患者和小鼠的SpeG水平下调。具体目的(1)将决定SpeG如何与RyR2结合，以及SpeG如何改变细胞内钙的处理。特殊目的(2)将评估RyR2的SpeG调节在心力衰竭中的作用。特殊目的(3)将确定SpeG介导的RyR2上S2811的磷酸化在正常和衰竭心脏中的作用。更好地了解RyR2在心力衰竭中功能异常的分子机制可能导致新的药理学策略。

 DESCRIPTION (provided by applicant): It is well established that altered sarcoplasmic reticulum (SR) Ca handling plays a key role in HF pathogenesis. Whereas altered post-translational modifications (PTM) of the SR Ca release channel/ ryanodine receptor type- 2 (RyR2) have been linked to HF development, it remains highly controversial which kinases and phosphatases underlie these disease-associated changes. RyR2 hyper-phosphorylation can be caused by increased activity of protein kinase A (PKA) and Ca/calmodulin-dependent protein kinase II (CaMKII). However, there remains significant controversy about the mechanisms underlying altered phosphorylation of RyR2 in HF. We have identified a novel kinase within the RyR2 macromolecular complex, known as `striated muscle preferentially expressed gene' (SPEG). Our preliminary data show that SPEG phosphorylates a novel phosphorylation site on RyR2, S2811. In addition, our data suggest that SPEG levels are downregulated in patients and mice with congestive heart failure. Our long-term goal is to define the molecular and cellular mechanisms by which SEPG regulates RyR2 and intracellular Ca handling in normal and failing hearts. The overall hypothesis is that SPEG phosphorylates a novel S2811 residue on RyR2, which modulates RyR2 activity and intracellular Ca handling in cardiac myocytes. Specific aim (1) will determine how SPEG binds to RyR2 and how SPEG modifies intracellular Ca handling. Specific aim (2) will assess the role of SPEG modulation of RyR2 in heart failure. Specific aim (3) will determine the role of SPEG-mediated phosphorylation of S2811 on RyR2 in normal and failing hearts. Significance: Heart failure (HF) is a deadly and costly disease affecting 5.7 millin people in the US alone, and a leading cause of hospitalization for those >65 years of age. A better understanding of the molecular mechanisms underlying abnormal RyR2 function in HF could lead to new pharmacological strategies.