The non-hypertrophic role of calcineurin in regulating cardiac structure-function

描述（由申请人提供）：每年有超过500万美国人被诊断患有心力衰竭。心力衰竭通常伴有心脏的病理性生长。钙调神经磷酸酶信号传导是肥大反应的重要调节因子。钙调神经磷酸酶的一种新的非肥大作用正在出现，其中钙调神经磷酸酶可能直接维持生存能力和心脏性能，因为心脏特异性钙调神经磷酸酶缺失的小鼠具有正常的心脏形态，但左心室功能差和过早死亡。迄今为止，钙调磷酸酶缺失对心脏功能的直接与代偿作用仍未得到解决，并且报告显示钙调磷酸酶缺失心肌的积极和消极功能结果。在钙调神经磷酸酶缺乏的心脏的屏幕中确定了Ca 2+处理基因表达的实质性改变。这表明，钙调神经磷酸酶可以调节Ca 2+循环蛋白，这是关键的功能成分，在胞质Ca 2+的波动启动收缩和舒张。因此，本提案旨在检验钙调神经磷酸酶通过翻译后和NFAT依赖性调节Ca 2+处理直接调节肥厚非依赖性心脏活力和心室性能的假设。该基金的特点是对钙调神经磷酸酶靶向siRNA向心肌细胞的急性基因转移和有条件Lox-P靶向钙调神经磷酸酶小鼠模型进行比较分析，以阐明钙调神经磷酸酶缺失对体外心肌细胞功能的直接与间接影响（aiml），并确定Ca 2+处理蛋白的磷酸化状态（aim 2）。将使用高保真细胞缩短和Ca 2+测量在来自两种遗传模型的分离的心肌细胞中检查肌细胞收缩性，而候选蛋白和蛋白质组学分析将确定Ca 2+处理蛋白的磷酸化状态。还将使用遗传拯救策略来研究NFAT依赖性转录是否是钙调磷酸酶缺陷小鼠中生存能力差的基础（目的3）。这一建议应作出实质性贡献，阐明钙调磷酸酶的额外的调节作用，在心脏，从而奠定了基础工作，开发新的治疗策略，心力衰竭。外行语言：钙调神经磷酸酶依赖性心脏病理性生长与终末期心力衰竭有关。钙调神经磷酸酶在心脏功能中的一种新的生长非依赖性调节作用正在出现，这表明钙调神经磷酸酶缺失可以直接改变心肌功能。该建议旨在阐明钙调神经磷酸酶在细胞和生物体水平上对心脏功能的直接与间接影响，而不依赖于心脏生长。这项工作的成果将为设计具有转化潜力的分子心力衰竭治疗方法取得重大进展。

DESCRIPTION (provided by applicant): Over 5 million Americans are diagnosed with heart failure yearly. Heart failure is generally accompanied by pathologic growth of the heart. Calcineurin signaling is an essential regulator of the hypertrophic response. A new non-hypertrophic role for calcineurin is emerging, in which calcineurin might directly maintain viability and cardiac performance, as mice with cardiac-specific calcineurin deletion have normal cardiac morphology but poor left ventricular function and premature death. To date the direct versus compensatory effects of calcineurin deletion on cardiac function remain unresolved, and reports show both positive and negative functional outcomes in calcineurin-deleted cardiac muscle. Substantial alterations in Ca2+ handling gene expression were identified in a screen of calcineurin deficient hearts. This suggests that calcineurin may regulate Ca2+ cycling proteins, which are critical functional components, as fluctuations in cytosolic Ca2+ initiate contraction and relaxation. Thus, this proposal seeks to test the hypothesis that calcineurin is directly regulating hypertrophy-independent cardiac viability and ventricular performance through post-translational and NFAT-dependent regulation of Ca2+ handling. This grant features a comparative analysis of acute gene transfer of calcineurin-targeted siRNA to cardiac myocytes and a conditional Lox-P targeted calcineurin mouse model to elucidate the direct versus indirect effects of calcineurin loss on cardiac myocyte function in vitro (aiml), and to determine the phosphorylation status of Ca2+ handling proteins (aim 2). Myocyte contractility will be examined in isolated cardiac myocytes from both genetic models using high fidelity cell shortening and Ca2+ measurements, while candidate protein and proteomic analysis will determine the phosphorylation status of Ca2+ handling proteins. A genetic rescue strategy will also be used to investigate if NFAT-dependent transcription underlies the poor survivability in calcineurin deficient mice (aim 3). This proposal should make substantial contributions to elucidating calcineurin's additional regulatory roles in the heart thereby laying the ground work for developing new therapeutic strategies for heart failure. Lay Language: Calcineurin-dependent pathologic growth of the heart is associated with end-stage heart failure. A new growth-independent regulatory role for calcineurin in cardiac function is now emerging that suggests calcineurin deletion can directly alter cardiac muscle function. This proposal is designed to elucidate the direct versus indirect effects of calcineurin on cardiac function independent of cardiac growth at the cellular and organismal level. The outcome of this work should make significant inroads into designing molecular heart failure therapies with translational potential.