Neuronal Kv2.1 Potassium Channels as Organizers of Somatic L-Type Calcium Channel Microdomains

L类钙通道(LTCC)作为多种钙信号的中介体，在大脑神经元中发挥着基础性作用 事件。神经元胞体上的LTCCs在调节钙依赖基因表达方面发挥着独特而关键的作用。 LTCC的一个显著特征是它们的活动由集群通过集群的协作门控来调节 频道。它们的集群还将它们定位于专门的钙信号微域，在这些微域中，它们 与钙依赖蛋白功能偶联，将LTCC介导的钙离子内流的影响转导到特异性 钙离子信号转导通路。通过它们作为K+传导电压门控通道的典型功能，躯体 Kv2.1通道在动作电位的调节中起关键作用，进而影响LTCC的活性。 普遍的共识是，LTCC和Kv2.1通道在神经元中的功能在很大程度上 彼此独立的。我们最近的工作挑战了这一观点。我们发现了一部出乎意料的小说 Kv2.1在物理调节神经元LTCC组织、增强其活性中的非传导作用 并影响它们在特定微域中的定位。这些令人兴奋的新结果导致了一种新的模型 在大脑神经元中，Kv2.1扮演着双重角色，一是作为规范的K+通道塑造固有膜 一种是神经元的特性，另一种是聚集LTCC以增强其活性的非传导物理作用 并将它们定位在钙信号微域中。互补的背景和技能的结合 Timmer和Santana实验室的集合使我们能够实施多尺度系统方法，其中包括 使用细胞、分子、生物物理、成像、基因编辑和全动物方法严格地 研究Kv2.1影响LTCC组织的分子机制及其后果 LTCC功能与神经元信号转导。该项目有三个具体目标，即确定如何 选择性地消除1)Kv2.1表达，2)Kv2.1聚集，以及3)Kv2.1增强LTCC的能力 聚集影响体细胞LTCC的定位和功能，钙离子诱导的钙释放或火花，以及LTCC依赖的转录因子激活。拟议的研究有可能改变我们的 了解神经元离子通道是如何调节的，以及这如何影响健康和健康中的钙信号转导 当疾病改变时。

L-type Ca2+ channels (LTCCs) play a fundamental role in brain neurons as mediators of diverse Ca2+ signaling events. LTCCs on neuronal somata play a unique and crucial role in regulating Ca2+-dependent gene expression. A salient feature of LTCCs is that their activity is regulated by clustering through cooperative gating of clustered channels. Their clustering also localizes them to specialized Ca2+ signaling microdomains within which they functionally couple to Ca2+-dependent proteins that transduce the impact of LTCC-mediated Ca2+ entry to specific Ca2+ signaling pathways. Through their canonical function as K+ conducting voltage-gated channels, somatic Kv2.1 channels play critical roles in the regulation of action potentials, with a subsequent impact on LTCC activity. The general consensus is that the functions of LTCCs and Kv2.1 channels in neurons are otherwise largely independent from one another. Our recent work challenges this view. We discovered a novel and unexpected nonconducting role for Kv2.1 in physically regulating the organization of neuronal LTCCs, enhancing their activity and impacting their localization in specific microdomains. These exciting new results lead to a novel model that in brain neurons, Kv2.1 plays dual roles, one as a canonical K+ channel shaping the intrinsic membrane properties of neurons, and the other a nonconducting physical role to cluster LTCCs to enhance their activity and localize them in Ca2+ signaling microdomains. The combination of the complementary backgrounds and skill sets of the Timmer and Santana labs allows us to implement a multi-scale systems approach that involves the use of cellular, molecular, biophysical, imaging, gene editing and whole-animal approaches to rigorously investigate the molecular mechanisms whereby Kv2.1 impacts LTCC organization, and the consequences to LTCC function and neuronal signaling. The project has three specific aims, which are to determine how selectively eliminating 1) Kv2.1 expression, 2) Kv2.1 clustering, and 3) the ability of Kv2.1 to enhance LTCC clustering impacts somatic LTCC localization and function, Ca2+-induced Ca2+ release or sparks, and LTCC-dependent transcript factor activation. The proposed studies have the potential of transforming our understanding of how neuronal ion channels are regulated and how this impacts Ca2+ signaling in health and when altered in disease.