Structural basis of KATP Channel Gating

KATP通道门控的结构基础

基本信息

批准号：
8254382
负责人：
Show-Ling Shyng
金额：
$ 28.18万
依托单位：
OREGON HEALTH & SCIENCE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2006
资助国家：
美国
起止时间：
2006-03-06 至 2015-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8254382
关键词：
ATP-Binding Cassette Transporters Address Affect Affinity Basic Science Binding Cardiac Cells Chemicals Childhood Complex Coupling Data Development Diabetes Mellitus Diagnosis Diazoxide Disease Exhibits Family Fostering Functional disorder Genetic Glucose Goals Health Sciences Homeostasis Human Hyperinsulinism Infant Ion Channel Kir6.2 channel Knowledge Lead Link Mediating Membrane Metabolic Metabolism MgADP Molecular Molecular Conformation Mutagenesis Mutate Mutation Myopathy N-terminal Neurologic Neurons Non-Insulin-Dependent Diabetes Mellitus Nucleotides Pancreas Pathway interactions Persistent Hyperinsulinemia Hypoglycemia of Infancy Phosphatidylinositol 4,5-Diphosphate Phosphatidylinositols Physiological Play Potassium Probability Proteins Publishing Regulation Research Role Scanning Screening procedure Signal Transduction Signal Transduction Pathway Structural Models Structure-Activity Relationship Sulfonylurea Compounds Testing Therapeutic Agents Work base cell type crosslink human disease innovation insulin secretion member neonatal diabetes mellitus novel novel therapeutics public health relevance response sulfonylurea receptor

项目摘要

DESCRIPTION (provided by applicant): ATP-sensitive potassium (KATP) channels couple cell metabolism to membrane excitability. They play a vital role in energy homeostasis by eliciting physiological response appropriate to metabolic signals. A member of the inwardly rectifying potassium (Kir) channel family, KATP channels are unique in requiring co-assembly of Kir6.2 with a sulfonylurea receptor (SUR), an ABC transporter, for functional expression. In pancreatic ¿- cells, KATP channels formed by Kir6.2 and SUR1 mediate glucose-stimulated insulin secretion. Mutations in Kir6.2 or SUR1 that reduce channel function cause congenital hyperinsulinism whereas those that increase channel function cause neonatal diabetes. Both Kir6.2 and SUR1 play an integral role in the channel's complex gating regulation. The long-term goal of this project is to understand the structure-function relationship of channel proteins with respect to gating. Work in the previous cycle has identified and elucidated the role of several structural features of the pore-forming subunit Kir6.2 in channel gating. In this renewal application, we will address the mechanisms of functional coupling between SUR1 and Kir6.2. SUR1 increases the open probability (Po) of Kir6.2, hypersensitizes Kir6.2 to the inhibitory effect of ATP and stimulatory effect of membrane phosphoinositides, and confers the effects of MgADP as well as the pharmacological agent sulfonylureas and diazoxide on Kir6.2. Functional coupling between SUR1 and Kir6.2 is thus essential to channel gating; yet significant knowledge gaps remain regarding the mechanisms by which SUR1 exerts its multiple effects on Kir6.2. The goal of this renewal application is to elucidate the mechanisms and structural basis that are responsible for functional coupling between SUR1 and Kir6.2. Based on our preliminary data, we propose a unifying hypothesis to explain how SUR1 imposes its multiple effects on Kir6.2 gating. Specifically, we hypothesize that SUR1 confers the intrinsic Po of KATP channels by stabilizing Kir6.2 in the PIP2-bound open state via molecular interactions between residues in the short cytoplasmic loops of TMD0 in SUR1 and those in the N-terminal domain of Kir6.2; and ATP, MgADP and pharmacological agents modulate channel activity in turn by changing the SUR1-Kir6.2 interface to strengthen or weaken channel-PIP2 interactions. We will interweave forward genetics approach employing disease mutations, guided mutagenesis screening, chemical cross-linking and structural modeling approaches to test the hypothesis. The research is innovative because it presents a novel concept to the field. The research is significant from both the human health and basic science standpoints. It will identify new disease mechanisms to directly facilitate diagnosis and treatment of several rare but devastating infant/childhood diseases and will lead to a better understanding of the structure-function relationship of the channel to foster new ideas on how to modulate channel activity to treat diseases caused by channel dysfunction, including type II diabetes. It will also lead to a better understanding of how a silent ABC transporter regulates an ion channel to advance both the ABC transporter and the ion channel fields. PUBLIC HEALTH RELEVANCE: The ATP-sensitive potassium (KATP) channels play a key role in linking metabolic signals to physiological responses in many cell types. Dysfunction of KATP channels causes human disease including diabetes, hyperinsulinism, cardiac myopathy and neurological deficits. The goal of this project is to understand the molecular basis underlying the ability of the channel to open or close according to metabolic signals to facilitate development of novel therapeutic agents for disease caused by channel dysfunction.

描述（由申请人提供）：ATP 敏感钾 (KATP) 通道将细胞代谢与膜兴奋性结合起来，它们通过引发适合代谢信号的生理反应，在能量稳态中发挥重要作用。在家族中，KATP 通道的独特之处在于需要 Kir6.2 与磺酰脲受体 (SUR)（一种 ABC 转运蛋白）共同组装才能在胰腺中进行功能表达。 ¿ - 细胞中，Kir6.2 和 SUR1 形成的 KATP 通道介导葡萄糖刺激的胰岛素分泌。Kir6.2 或 SUR1 的突变会降低通道功能，导致先天性高胰岛素血症，而增加通道功能的突变会导致新生儿糖尿病。该项目的长期目标是了解通道蛋白与门控的结构-功能关系。识别并阐明了成孔亚基 Kir6.2 的几个结构特征在通道门控中的作用。在这个更新应用中，我们将解决 SUR1 和 Kir6.2 之间的功能耦合增加开放概率 (Po) 的机制。 Kir6.2的Kir6.2使Kir6.2对ATP的抑制作用和膜磷酸肌醇的刺激作用过敏，并赋予MgADP以及药物制剂的作用因此，SUR1 和 Kir6.2 之间的功能耦合对于通道门控至关重要；但关于 SUR1 对 Kir6.2 发挥多重作用的机制仍存在重大知识空白。为了阐明 SUR1 和 Kir6.2 之间功能耦合的机制和结构基础，根据我们的初步数据，我们提出了一个统一的假设来解释 SUR1 如何对 SUR1 施加其多重影响。具体来说，我们通过 SUR1 中 TMD0 的短胞质环中的残基与 N 中的残基之间的分子相互作用，将 Kir6.2 稳定在 PIP2 结合的开放状态，从而探究 SUR1 赋予 KATP 通道的内在 Po。 - Kir6.2的末端结构域；以及ATP、MgADP和药物制剂通过改变SUR1-Kir6.2界面来依次调节通道活性以增强或减弱我们将利用疾病突变、引导诱变筛选、化学交联和结构建模方法交织正向遗传学方法来检验该假设，因为它向该领域提出了一个新颖的概念。它将从人类健康和基础科学的角度确定新的疾病机制，以直接促进几种罕见但具有破坏性的婴儿/儿童疾病的诊断和治疗，并将导致更好地理解该通道的结构与功能关系，以培育新的疾病机制。关于如何调制通道的想法治疗由通道功能障碍引起的疾病（包括 II 型糖尿病）的活性还将有助于更好地了解沉默 ABC 转运蛋白如何调节离子通道以促进 ABC 转运蛋白和离子通道场的发展。公共健康相关性：ATP 敏感钾 (KATP) 通道在将代谢信号与多种细胞类型的生理反应联系起来方面发挥着关键作用。KATP 通道的功能障碍会导致人类疾病，包括糖尿病、高胰岛素血症、心肌病和神经缺陷。该项目旨在了解通道根据代谢信号打开或关闭的能力的分子基础，以促进开发针对通道功能障碍引起的疾病的新型治疗剂。