Mechanisms of L-type Calcium Channel Regulation in Heart Health and Disease

对心脏逐渐衰竭的正性肌力支持是一种未满足的需求。直接尝试改善 通过激活β-肾上腺素能受体（β-AR）信号传导的收缩功能增加心力衰竭的相关风险 与死绕过β-AR信号传导的钙索（影响Ca2+处理的试剂）不一定是 预防性的我们的工作全球假设基于我们最近和正在进行的研究RAD调节的工作 L-型钙通道（LTCC）的主要作用是通过旁路β-AR信号增加钙诱导的钙释放（CICR）。 提供安全、稳定的功能恢复，以对抗心力衰竭进展。在本应用程序中，我们重点关注 Rad-LTCC相互作用的机制作为向心脏灌输正性肌力支持的新手段。LTCC是 一个大分子枢纽，整合了多种信号通路，包括蛋白激酶A（PKA）和Ca2 +- 钙调蛋白激酶II（CaMK II）。RAD是单体G蛋白RGK家族的成员。RAD绑定到 辅助CaV1.2和CaV1.2是LTCC的成孔亚基。RAD的缺失或磷酸化导致 LTCC电流（ICa，L）调节和促进。ICa，L的调节通常在β-AR信号传导后观察到， 激活PKA;易化由CaMKII激活引起。在具体目标1中，我们将剖析RAD如何集成 这些信号通路中的每一个都使用药理学和遗传学方法的组合。在特定 目的2：我们将使用基因修饰小鼠的敲入模型来探索RAD-CaV 1. 2的结构-功能， 允许我们探索RAD-LTCC效应，保留LTCC异多聚体蛋白的天然化学计量 复杂.具体目标3探讨了RAD-LTCC相互作用作为减缓心力衰竭进展的方法。 为了实现这些目标，我们将使用体内，离体和细胞/分子生物学方法整合目的之间的发现， 动物模型的方法。将测试离体人心脏切片以评估以下的翻译潜力： RAD-LTCC调节心脏健康和疾病。

Inotropic support for hearts progressing towards failure represents an unmet need. Direct attempts to improve systolic function by activating -adrenergic receptor (-AR) signaling increases associated risk of heart failure and death. Calcitropes (agents influencing Ca2+ handling) that bypass -AR signaling are not necessarily proarrhythmic. Our working global hypothesis based on our recent and ongoing work studying RAD regulation of the L-type Ca2+ channel (LTCC) is that bypassing -AR signaling to increase Ca2+-induced Ca2+ release (CICR) provides safe, stable gain of function to counter heart failure progression. In this application we focus on the mechanisms of Rad – LTCC interactions as a novel means to instill inotropic support to the heart. The LTCC is a macromolecular hub that integrates multiple signaling pathways including protein kinase A (PKA) and Ca2+- calmodulin kinase II (CaMKII). RAD is a member of the RGK family of monomeric G-proteins. RAD binds to auxiliary CaV2 and CaV1.2, the pore-forming subunit of the LTCC. Deletion, or phosphorylation of RAD causes LTCC current (ICa,L) modulation and facilitation. Modulation of ICa,L is commonly observed after -AR signaling to activate PKA; facilitation is caused by CaMKII activation. In Specific Aim 1 we will dissect how RAD integrates each of these signaling pathways using a combination of pharmacological and genetic approaches. In Specific Aim 2 we will explore RAD – CaV1.2 structure-function using knock-in models of genetically modified mice that allow us to explore RAD – LTCC effects retaining native stoichiometry of the LTCC heteromultimeric protein complex. Specific Aim 3 explores RAD – LTCC interplay as an approach to attenuate progression of heart failure. To achieve these goals, we will integrate findings among Aims using in vivo, ex vivo and cellular/molecular approaches in animal models. Ex vivo human heart slices will be tested to evaluate the translational potential of RAD – LTCC regulation in heart health and disease.