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

对逐渐走向衰竭的心脏提供变力支持代表着一种未得到满足的需求。直接尝试改进 激活-肾上腺素能受体(-AR)信号的收缩功能增加心力衰竭的相关风险 和死亡。钙调蛋白(影响钙离子处理的介质)绕过-AR信号转导不一定 心律不齐。我们的工作全球假说基于我们最近和正在进行的研究RAD调节的工作 L型钙通道的特点是绕过-AR信号通路，增加钙诱导的钙释放。 提供安全、稳定的功能增长，以对抗心力衰竭的进展。在本应用程序中，我们重点介绍 Rad-LTCC相互作用机制作为心脏肌力支持的一种新方法。LTCC是 整合了包括蛋白激酶A(PKA)和钙离子在内的多种信号通路的大分子枢纽- 钙调蛋白激酶II(CaMKII)。RAD是单体G蛋白RGK家族的一员。RAD绑定到 辅助Cav_2和CaV_(1.2)，它们是低温致孔混凝土的成孔亚基。RAD原因的缺失或磷酸化 LTCC电流(ICa，L)的调制和易化。对ICa的调制，L在-AR信令后常观察到 激活PKA；促进由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结合了药理学和遗传学方法。具体而言 目的2我们将使用转基因小鼠的敲入模型来探索RAD-CaV1.2的结构功能 允许我们探索保持LTCC异构体蛋白天然化学计量比的RAD-LTCC效应 很复杂。具体目标3探索RAD-LTCC相互作用作为减缓心力衰竭进展的一种方法。 为了实现这些目标，我们将利用体内、体外和细胞/分子整合AIMS的研究结果 动物模型中的方法。将对体外人类心脏切片进行测试，以评估其翻译潜力 RAD-LTCC在心脏健康和疾病中的调节。

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.