Regulation of Calcium Homeostasis by MyomiRs in Heart Failure

描述（由申请人提供）：尽管在对潜在机制的理解方面取得了进展，但心力衰竭（HF）仍然是死亡的主要原因，这表明迫切需要开发新的非常规治疗策略。细胞内钙（Ca 2+）处理异常与心力衰竭（HF）特征性恶性心律失常的发病机制有关。心脏兴奋-收缩（EC）偶联通过Ca 2+诱导的Ca 2+释放（CICR）介导，CICR由肌浆网（SR）Ca 2+敏感性Ca 2+通道（也称为心脏ryanodine受体（RyR 2））控制。微小RNA（microRNAs，miRs）是一种长度约为22个核苷酸的非蛋白质编码RNA，通过碱基配对相互作用识别靶mRNA，随后通过靶向这些mRNA进行翻译抑制或降解来抑制基因表达。快速积累的证据表明miR在心脏发病机制中的失调，包括心律失常和HF，使其成为新的有吸引力的治疗靶点。然而，为了更好地理解miR的功能，还必须做很多工作。我们的初步研究结果表明，一个家族的miR特异性肌肉组织称为myomiRs在调节心肌细胞中的Ca 2+处理。该提议的中心假设是，包括miR-208 a、miR-208 b和miR-499的myomiR通过调节参与Ca 2+处理的大分子复合物的结构和功能在调节Ca 2+稳态中起关键作用。为了验证这一假设，我们已经开发了技术，以修改在体外和在完整的心脏在体内的表达的miRNA，以检查其对Ca 2+循环在单个心室肌细胞的电生理学和单光子激光扫描共聚焦显微镜的影响。具体而言，我们的目的是研究myomiR介导的调节SR钙释放的分子决定因素，通过RyR 2s在心室肌细胞，并测试这些miR的异常表达模式是否有助于钙依赖性心律失常的心脏疾病的特征，使用大鼠模型的心力衰竭。

DESCRIPTION (provided by applicant): Despite advances in the understanding of underlying mechanisms, heart failure (HF) remains the major cause of mortality, indicating the urgent need in the development of novel unconventional therapeutic strategies. Abnormal intracellular calcium (Ca2+) handling has been implicated in the pathogenesis of malignant arrhythmias characteristic of Heart Failure (HF). Cardiac excitation-contraction (EC) coupling is mediated through Ca2+-induced Ca2+ release (CICR), which is controlled by sarcoplasmic reticulum (SR) Ca2+-sensitive Ca2+ channels, also known as cardiac ryanodine receptors (RyR2). MicroRNAs (miRs) are ~22-nucleotide-long nonprotein-coding RNAs that recognize their target mRNAs by base pairing interactions and subsequently inhibit gene expression by targeting these mRNAs for translational repression or degradation. Rapidly accumulating evidence implicates dysregulated miRs in cardiac pathogenesis including arrhythmias and HF rendering them new attractive targets for therapy. However, much work must be done for better understanding of miR functions. Our preliminary results implicate a family of miRs specific to muscle tissue called myomiRs in regulation of Ca2+ handling in cardiomyocytes. The central hypothesis of this proposal is that myomiRs which include miR-208a, miR-208b and miR-499 play a critical role in regulating Ca2+ homeostasis by modulating the structure and function of macromolecular complexes involved in Ca2+ handling. In order to test this hypothesis we have developed techniques to modify the expression of miRNAs in vitro and in intact hearts in vivo in order to examine their effects on Ca2+ cycling in single ventricular myocytes using electrophysiology and single photon laser scanning confocal microscopy. Specifically we aim to investigate the molecular determinants of myomiR-mediated regulation of SR Ca2+ release through RyR2s in ventricular myocytes, and test whether aberrant expression patterns of these miRs contribute to Ca2+-dependent arrhythmias characteristic of cardiac disease using rat model of heart failure.