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

L型钙通道（L-type Ca 2 + channels，LTCCs）是脑神经元中钙离子信号的重要介质 事件神经元胞体上的LTCCs在调节Ca 2+依赖性基因表达中起着独特而关键的作用。 LTCC的一个显著特征是它们的活性通过集群的合作门控来调节。 渠道它们的聚集也使它们定位于专门的Ca 2+信号微域， 在功能上与Ca 2+依赖性蛋白偶联，这些蛋白抑制LTCC介导的Ca 2+进入特异性 Ca 2+信号通路。通过它们作为K+传导电压门控通道的典型功能， Kv2.1通道在动作电位的调节中起关键作用，随后影响LTCC活性。 普遍的共识是，在神经元中LTCC和Kv2.1通道的功能在很大程度上是 彼此独立。我们最近的工作挑战了这一观点。我们发现了一本小说， Kv2.1在物理调节神经元LTCC的组织，增强其活性方面的非传导作用 并影响它们在特定微区中的定位。这些令人兴奋的新结果导致了一种新的模型， 在脑神经元中，Kv2.1起着双重作用，一个是作为典型的K+通道塑造内在膜， 另一个是非传导性的物理作用，聚集LTCC以增强其活性 并定位于Ca 2+信号微区。互补的背景和技能的结合 Timmer和桑塔纳实验室的集合使我们能够实施多尺度系统方法， 使用细胞、分子、生物物理、成像、基因编辑和全动物方法， 研究Kv2.1影响LTCC组织的分子机制，以及 LTCC功能和神经元信号传导。该项目有三个具体目标，即确定如何 选择性消除1）Kv2.1表达，2）Kv2.1聚集，和3）Kv2.1增强LTCC的能力 成簇影响体细胞LTCC定位和功能、Ca 2+诱导的Ca 2+释放或火花以及LTCC依赖性转录因子活化。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中的Ca 2+信号， 在疾病中改变。

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.