RGK GTPases/Ca2+ Channel Cross Talk

描述(由申请人提供)：这个项目关注最近发现的两个蛋白质家族之间的串扰：高压激活的钙通道(Cav)和Ras样GTP酶的Rem/Rad/Gem/Kir(RGK)家族。钙离子通过钙离子通道(ICA)内流调节许多重要的过程，包括肌肉收缩、突触交流和基因表达。ICA的失调与多种神经和心血管疾病有关，包括自闭症和心律失常。相反，阻断ICA是治疗心绞痛、中风和高血压等严重疾病的重要疗法。最近发现RGK GTP酶通过与辅助的CaVβ亚基相互作用而有效地抑制Cav通道。由于RGK蛋白广泛存在，并且它们在疾病中的表达存在差异，它们与Cav通道的串扰很好地调节了许多钙依赖的生物和病理生理事件。此外，RGK GTP酶代表了一种新的ICA抑制剂的原型，有可能被开发成具有治疗和实际应用的新型遗传编码的Cav通道阻滞剂。我们试图解决与RGK GTP酶在CAV通道上的作用相关的关键未知因素，这些未知因素限制了人们对这种串扰的(病理性)生理影响的了解，以及它潜在的有益开发。我们的长期目标是深入了解RGK GTPase/Cav通道串扰的潜在机制，并将这些知识应用于：(1)了解这种相互作用如何对(病理)生理学做出贡献，以及(2)创造新一代有用的遗传编码的Cav通道抑制剂。我们提出了三个目标：(1)阐明RGK蛋白对CAV通道门控和运输的影响，并阐明其潜在的机制。(2)研究Ca~(2+)-CaM对RGK GTPase/Cav通道串扰的影响。(3)测定RGK GTP酶在心脏中的表达谱，并确定其与L型CAV通道的串扰对功能的影响。

DESCRIPTION (provided by applicant): This project focuses on a recently discovered crosstalk between two protein families: high-voltage-activated Ca2+ (CaV) channels and the Rem/Rad/Gem/Kir (RGK) family of Ras-like GTPases. Ca2+ influx through CaV channels (ICa) regulates many essential processes including muscle contraction, synaptic communication, and gene expression. Dysregulation of ICa is linked to diverse neurological and cardiovascular disorders including autism and cardiac arrhythmias. Conversely, blockade of ICa is an important therapy for serious diseases such as angina, stroke, and hypertension. RGK GTPases were recently revealed to potently inhibit CaV channels by interacting with auxiliary CaVbeta subunits. Because RGK proteins are widely prevalent, and their expression differentially regulated in disease, their crosstalk with CaV channels is well-placed to regulate many Ca2+-dependent biological and pathophysiological events. Moreover, RGK GTPases represent a new archetype of ICa inhibitors that could be potentially exploited to generate novel genetically-encoded CaV-channel blockers with therapeutic and practical applications. We seek to address critical unknowns related to the action of RGK GTPases on CaV channels that limit insights into the (patho)physiological impact of this crosstalk, and its latent beneficial exploitation. Our long-term objective is to gain an in-depth understanding of mechanisms underlying the RGK GTPase/CaV-channel crosstalk and apply this knowledge to: (1) an appreciation of how this interaction contributes to (patho)physiology, and (2) create a new generation of useful genetically-encoded CaV- channel inhibitors. We propose 3 Aims: (1) Clarify the impact of RGK proteins on the gating and trafficking of CaV channels and elucidate the underlying mechanisms. (2) Characterize the functional impact of Ca2+- CaM on the RGK GTPase/CaV channel crosstalk. (3) Determine the expression profile of RGK GTPases in heart and define the functional impact of their crosstalk with L-type CaV channels.