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: 9981844
• 负责人: Nicholas C. Vierra
• 金额: $ 4.84万
• 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 2021-05-08
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9981844
• 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; Estrogen receptor positive; 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; de novo mutation; 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.

本提案中概述的培训计划侧重于定义由电压门控K+通道Kv2.1控制的基本神经生理功能。Kv2.1通道在紧邻内质网（ER）的神经元索马上形成突出的质膜（PM）簇。这些Kv2.1相关的ER-PM连接或EPJ通常含有Ca 2+处理机制，包括L型Ca 2+通道（LTCC）和兰尼碱受体（RyR）ER Ca 2+释放通道。除了是Ca 2+吸收和释放的重要位点外，EPJ在调节细胞脂质处理方面也发挥着重要作用。ER和PM之间的脂质转移可以通过Ca 2+进行急性调节，并且EPJ处的脂质调节酶对细胞Ca 2+动力学产生相互作用。由于Kv2.1簇增强了EPJ的形成，并可能在这些位点调节Ca 2+信号，因此Kv2.1完全准备好整合和控制神经元Ca 2+和脂质信号。重要的是，临床研究结果表明，Kv2.1相关的EPJ对正常的脑功能至关重要：Kv2.1中的三种不同突变破坏了EPJ聚集组织所需的通道结构域，导致严重的神经发育延迟。然而，Kv2.1相关的EPJ的分子结构，调节和功能作用仍然知之甚少。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衰弱性神经元疾病发病机制的理解。虽然其在神经元中的作用尚不清楚，但发现Kv2.1在神经内分泌细胞中的聚集促进致密核心囊泡（DCV）的胞吐，致密核心囊泡是神经元中含有不同神经活性货物的分泌细胞器。由于神经元DCV释放的缺陷与自闭症、焦虑症和癫痫相关，因此定义Kv2.1通道和DCV释放之间的分子交叉点是重要的。我推测，Kv2.1相关的EPJs控制神经元钙和脂质信号，以调节DCV的释放。我将通过确定Kv2.1通道调节神经元中局部Ca 2+和脂质稳态和信号传导的机制来检验中心假设（目的1）。这些发现将被扩展到详细的研究如何Kv2.1通道有助于调节体树突DCV释放（目的2）。这项研究的成功完成将促进我们对调节神经元功能的基本机制的理解。此外，阐明Kv2.1通道对神经元DCV释放的影响将大大扩展对DCV胞吐作用机制的理解，也可能提高对Kv2.1对神经系统疾病的作用机制的理解。通过这项奖学金，我将开发1）Kv2.1通道的生理功能的新的理解，和2）我的潜力，作为一个独立的研究人员专注于离子通道生物学。这些培训目标将通过详细的研究计划，在拟议的研究设计中具有专业知识的特别合格的导师，以及UC Davis提供的优秀设施和培训资源来实现。