Dynamic modulation of ionic and lipid signaling by neuronal Kv2 channels

神经元 Kv2 通道对离子和脂质信号传导的动态调节

• 批准号: 9765044
• 负责人: Nicholas C. Vierra
• 金额: $ 6.12万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-09 至 2020-11-08
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9765044
• 关键词: Acute; Address; Anxiety Disorders; Architecture; Biology; Brain; Cell membrane; Cell physiology; Characteristics; Classification; Clinical; Comprehension; Defect; Dendrites; Dense Core Vesicle; Disease; Endoplasmic Reticulum; Enzymes; Epilepsy; Exocytosis; Fellowship; Generations; Goals; Homeostasis; Interneurons; Ion Channel; Knockout Mice; Link; Lipids; Mass Spectrum Analysis; Mediating; Mediator of activation protein; Membrane Lipids; Mentors; Molecular; Mutation; Neuroendocrine Cell; Neurons; Neuropeptides; Organelles; Pathogenesis; Pathogenicity; Physiological; Proteins; Rattus; Regulation; Research; Research Design; Research Personnel; Resources; Role; Ryanodine Receptor Calcium Release Channel; Signal Transduction; Site; Synaptic Vesicles; Techniques; Testing; Tissues; Training; VAPA gene; Voltage-Gated Potassium Channel; autism spectrum disorder; base; hippocampal pyramidal neuron; improved; insight; lipid transport; live cell imaging; nervous system disorder; neuronal cell body; neurophysiology; neurotransmission; novel; novel therapeutic intervention; recruit; spatiotemporal; treatment strategy; uptake; vesicular release; voltage

The training plan outlined in this proposal focuses on defining the fundamental neurophysiological functions controlled by the voltage-gated K+ channel Kv2.1. Kv2.1 channels form prominent plasma membrane (PM) clusters on the neuronal soma that are in close proximity to the endoplasmic reticulum (ER). These Kv2.1- associated ER-PM junctions, or EPJs, often contain Ca2+ handling machinery, including L-type Ca2+ channels (LTCCs) and ryanodine receptor (RyR) ER Ca2+ release channels. In addition to being significant sites of Ca2+ uptake and release, EPJs also serve important roles in modulating cellular lipid handling. Lipid transfer between the ER and PM can be acutely regulated by Ca2+, and lipid-modulating enzymes at EPJs exert a reciprocal effect on cellular Ca2+ dynamics. As Kv2.1 clusters enhance the formation EPJs and may modulate Ca2+ signaling at these sites, Kv2.1 is perfectly poised to integrate and control neuronal Ca2+- and lipid signals. Importantly, clinical findings suggest that Kv2.1-associated EPJs are critical for normal brain function: three distinct mutations in Kv2.1 that disrupt the channel domain required for its clustered organization with EPJs cause severe neurodevelopmental delay. However, the molecular architecture, regulation, and functional roles of Kv2.1- associated EPJs remain poorly understood. This presents a major obstacle to determining how Kv2.1 channels contribute to normal neuronal function and limits our understanding of its contributions to the pathogenesis of debilitating neuronal disorders. Although its role in neurons is not yet clear, Kv2.1 clustering in neuroendocrine cells was found to facilitate the exocytosis of dense-core vesicles (DCV), secretory organelles that in neurons contain diverse neuroactive cargo. As defects in neuronal DCV release are associated with autism, anxiety disorders, and epilepsy, it is important to define the molecular points of intersection between Kv2.1 channels and DCV release. I hypothesize that Kv2.1-associated EPJs control neuronal Ca2+ and lipid signals to regulate DCV release. I will test the central hypothesis by determining the mechanisms by which Kv2.1 channels modulate local Ca2+ and lipid homeostasis and signaling in neurons (Aim 1). These findings will be extended to detailed studies of how Kv2.1 channels contribute to the regulation of somatodendritic DCV release (Aim 2). Successful completion of the proposed research will advance our understanding of the fundamental mechanisms regulating neuron function. Moreover, elucidating the influence of Kv2.1 channels on neuronal DCV release will greatly expand comprehension of the mechanisms underlying DCV exocytosis and may also improve understanding of the mechanisms underlying Kv2.1’s contributions to neurological disorders. Through this fellowship, I will develop 1) a novel understanding of the physiological functions of Kv2.1 channels, and 2) my potential as an independent investigator focused on ion channel biology. These training goals will be facilitated by the detailed research plan, the exceptionally qualified mentors with expertise in the proposed study design, and the outstanding facilities and training resources available at UC Davis.

该提案中概述的培训计划着重于定义由电压门控的K+通道Kv2.1控制的基本神经生理功能。 Kv2.1通道在神经元体内形成突出的质膜（PM）簇，与内质网（ER）非常接近。这些Kv2.1-相关的ER-PM连接或EPJ通常包含CA2+处理机械，包括L型Ca2+通道（LTCCS）和Ryanodine受体（RYR）ER CA2+释放通道。除了是Ca2+摄取和释放的重要部位外，EPJ还在调节细胞脂质处理方面起着重要作用。 ER和PM之间的脂质转移可以通过Ca2+急剧调节，而在EPJS处的脂质调节酶对细胞CA2+动力学产生相互影响。随着KV2.1簇增强了EPJ的形成，并可能在这些位点调节Ca2+信号传导，KV2.1完全中毒为整合和控制神经元Ca2+和脂质信号。重要的是，临床发现表明，KV2.1相关的EPJ对于正常的大脑功能至关重要：KV2.1中的三个不同突变破坏了其簇状组织所需的EPJS所需的通道域导致严重的神经发育延迟。但是，Kv2.1相关的EPJ的分子结构，调控和功能作用仍然很少了解。这是确定KV2.1通道如何促进正常神经元功能的主要障碍，并限制了我们对其对神经元疾病发病机理的贡献的理解。尽管尚不清楚其在神经元中的作用，但发现神经内分泌细胞中的KV2.1聚类促进了浓密蔬菜（DCV）的胞吐作用，而神经元中的秘密细胞器包含潜水神经活性货物。由于神经元DCV释放中的缺陷与自闭症，焦虑症和癫痫有关，因此定义Kv2.1通道和DCV释放之间的交点分子点很重要。我假设Kv2.1相关的EPJ控制神经元CA2+和脂质信号以调节DCV释放。我将通过确定KV2.1通道调节局部Ca2+和脂质稳态以及神经元中的脂质稳态的机制来检验中心假设（AIM 1）。这些发现将扩展到有关KV2.1通道如何促进体内源性DCV释放的调节的详细研究（AIM 2）。成功完成拟议的研究将提高我们对基本机制调节神经元功能的理解。此外，阐明KV2.1通道对神经元DCV释放的影响将极大地扩展对DCV胞吞作用的机制的理解，并可能提高人们对KV2.1对神经系统疾病贡献的机制的理解。通过这一奖学金，我将发展1）对KV2.1通道的物理功能的新知识，以及2）我作为专注于离子通道生物学的独立研究者的潜力。这些培训目标将由详细的研究计划，具有拟议研究设计专业知识的非凡资格的导师以及UC Davis提供的出色设施和培训资源制定。