KCNQ CHANNELS: GATING AND SUBUNITS MODULATION

KCNQ 通道：门控和子单元调制

• 批准号: 9638596
• 负责人: JONATHAN R SILVA
• 金额: $ 33.36万
• 依托单位: WASHINGTON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-03-01 至 2021-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9638596
• 关键词: Action Potentials; Adrenergic Agents; Affect; Arrhythmia; Behavior; Brain; Chemosensitization; Coupled; Coupling; Data; Dependence; Disease; Drug Design; Epilepsy; Epithelial; Epithelium; Exercise; Exhibits; Family; Heart; Ion Channel Gating; Ion Transport; Ions; Labyrinth; Light; Long QT Syndrome; Membrane; Membrane Potentials; Modeling; Molecular; Molecular Conformation; Movement; Mutation; Neurons; Pathway interactions; Patients; Pharmaceutical Preparations; Pharmacology; Physiological; Physiology; Potassium Channel; Property; Rest; Role; Signaling Molecule; Structure; Sudden Death; Symptoms; Syncope; Testing; Thyroid Gland; Work; airway epithelium; base; deafness; experience; gastrointestinal epithelium; heart function; inhibitor/antagonist; insight; malignant stomach neoplasm; novel; public health relevance; response; sensor; therapy design; tool; voltage

 DESCRIPTION (provided by applicant): This project is to reveal the major molecular bases for the function of KCNQ K+ channels (KCNQ1-5) that are important in the heart, brain, inner ear and epithelia. The aberrant functions of these channels are associated with cardiac arrhythmia, epilepsy, deafness, and gastric cancer. The importance of these channels is based on two prominent properties. First, all these channels, when expressed without auxiliary ß subunits, are activated by voltages at negative ranges (start activating around -60 mV). Being activated just above the resting membrane potential, the M-current through KCNQ2 and 3 in neurons reduces membrane excitability and acts as a "brake" to membrane discharge. Second, the association of the KCNE family K+ channel ß subunits, which radically alter gating, permeation and pharmacological properties of KCNQ1, determines the physiological role of KCNQ1. KCNQ1 associates with KCNE1 to form the IKs channel in the heart that regulates action potential duration, and with KCNE2 or KCNE3 to form the constitutively open background K+ channels in epithelia important for ion transport. What are the mechanisms underlying these properties? This is a long-standing question whose answer will provide the basis for the understanding and treatment of KCNQ associated diseases. We propose that the answer to this question lies in a novel mechanism for KCNQ1 activation. During voltage dependent activation in KCNQ1, the voltage sensor domain (VSD) moves in two steps, from the resting to intermediate and then to activated state; the channel pore opens at both intermediate and activated states of VSD, but the VSD-pore interaction differs at different states of VSD to alter channel gating, ion permeation and pharmacology. KCNE1 modulates channel function by suppressing the intermediate openings of the channel. In this project we wish to test various aspects of this hypothesis in three specific aims. 1) We wish to identify the structural motifs that are important for the VSD-pore interaction at intermediate and activated states, respectively. Mutations in KCNQ1 and KCNE1 are associated with long QT syndrome (LQT) that predispose patients to fatal cardiac arrhythmia, this study will reveal if some of the LQT mutations alter VSD-pore interaction. 2) We will examine if suppression of the intermediate and potentiation of the activated openings is the main mechanism for major functional changes upon KCNE1 association including the response to ß- adrenergic stimulation and inactivation gating. LQT patients with KCNQ1 mutations often experience symptoms of cardiac arrhythmia such as syncope and sudden death during exercise when ß-adrenergic pathway is stimulated. This study is therefore particularly significant for the understanding of molecular bases of LQT. 3) We wish to reveal if KCNE2 and 3 make the channel constitutively open by altering VSD activation, pore opening or VSD-pore interaction. We will identify if these channels are at intermediate or activated open states and their responses to drugs and cellular signaling molecules.

 描述(申请人提供)：该项目旨在揭示KCNQ K+通道(KCNQ1-5)功能的主要分子基础，KCNQ1-5在心脏、脑、内耳和上皮细胞中起重要作用。这些通道的功能异常与心律失常、癫痫、耳聋和胃癌有关。这些渠道的重要性基于两个突出的属性。首先，所有这些通道，当表达时没有辅助亚基时，都被负电压范围内的电压激活(开始激活大约-60 mV)。神经元中通过KCNQ2和KCNQ3的M-电流仅在静息膜电位上方被激活，从而降低了膜的兴奋性，并对膜放电起到了“刹车”的作用。其次，KCNE家族K+通道亚基之间的关联从根本上改变了KCNQ1的门控、渗透和药理特性，决定了KCNQ1的生理作用。KCNQ1与KCNE1结合，在心脏形成调节动作电位时程的IKS通道，与KCNE2或KCNE3结合，在上皮细胞形成对离子转运重要的结构性开放的背景K+通道。这些特性背后的机制是什么？这是一个长期存在的问题，其答案将为了解和治疗KCNQ相关疾病提供基础。我们认为，这个问题的答案在于一种新的KCNQ1激活机制。在KCNQ1的电压依赖激活过程中，电压敏感域(VSD)分两步运动，从静止到中间再到激活状态，通道孔在VSD的中间状态和激活状态都打开，但VSD-孔的相互作用在VSD的不同状态下是不同的，从而改变通道门控、离子渗透和药理学。KCNE1通过抑制通道的中间开口来调节通道功能。在这个项目中，我们希望通过三个具体的目标来检验这一假设的各个方面。1)我们希望确定在中间态和活化态分别对VSD-孔相互作用重要的结构基序。KCNQ1和KCNE1的突变与长QT综合征(LQT)有关，LQT使患者容易发生致命的心律失常，这项研究将揭示一些LQT突变是否会改变VSD-孔道相互作用。2)我们将研究抑制中间产物和增强激活的开口是否是KCNE1关联的主要功能变化的主要机制，包括对？肾上腺素能刺激和失活门控的反应。携带KCNQ1基因突变的LQT患者在运动时经常出现心律失常的症状，如晕厥和猝死。因此，这项研究对于了解LQT的分子基础具有特别重要的意义。3)我们希望揭示KCNE_2和KCNE_3是否通过改变VSD激活、孔道开放或VSD-孔道相互作用而使通道结构性开放。我们将确定这些通道是处于中间开放状态还是激活开放状态，以及它们对药物和细胞信号分子的反应。

项目成果

Arrhythmia-associated calmodulin variants interact with KCNQ1 to confer aberrant membrane trafficking and function.

• DOI: 10.1093/pnasnexus/pgad335
• 发表时间: 2023-11
• 期刊: PNAS NEXUS
• 作者: Kang, Po wei;Woodbury, Lucy;Angsutararux, Paweorn;Sambare, Namit;Shi, Jingyi;Marras, Martina;Abella, Carlota;Bedi, Anish;Zinn, DeShawn;Cui, Jianmin;Silva, Jonathan R.
• 通讯作者: Silva, Jonathan R.