Structural Basis of Katp Channel Gating

Katp 通道选通的结构基础

基本信息

批准号：
8004316
负责人：
Show-Ling Shyng
金额：
$ 8.11万
依托单位：
OREGON HEALTH & SCIENCE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-01-15 至 2011-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8004316
关键词：
ATP sensitive potassium channel complex Address Adenoviruses Affect Binding Biogenesis Biological Assay Blood Vessels COS Cells Cell Line Cell membrane Cell physiology Cells Complex Coupling Cytoplasmic Tail Data Defect Diabetes Mellitus Disease Family Functional disorder GIRK1 subunit, G protein-coupled inwardly-rectifying potassium channel Genes Genetic Glucose Goals Hand Health Homology Modeling Hormones Human Hypoglycemia In Vitro Internet Ions Ischemia Knowledge Lead Ligand Binding Mediating Membrane Membrane Potentials Metabolism MgADP MgATP Molecular Monitor Mutagenesis Mutate Mutation Myocardium Neurons Pancreas Patients Persistent Hyperinsulinemia Hypoglycemia of Infancy Pharmacological Treatment Phosphatidylinositols Physiological Physiological Processes Plasma Play Population Potassium Proteins Protocols documentation Rattus Recombinants Regulation Research Research Personnel Rest Role Signal Transduction Simulate Site Structure Structure-Activity Relationship System Testing Therapeutic Work base cell type design disease-causing mutation drug development gain of function mutation glucose sensor insight insulin secretion inward rectifier potassium channel loss of function loss of function mutation member mutant neonatal diabetes mellitus novel programs protein expression protein protein interaction response sulfonylurea receptor

项目摘要

ATP-sensitive potassium (KAip) channels play a key role in coupling cell metabolism to cell excitability and govern diverse physiological processes including hormone secretion, control of vascular tone, and modulation of the activity of cardiac muscle and neurons during ischemia. The long-term goal of this project is to understand the structural basis of KATP channel gating. Towards this goal, our research has focused on the pancreatic subtype of KATP channels, which are heteromultimeric complexes each composed of four inwardly rectifying potassium channel Kir6.2 subunits and four regulatory sulfonylurea receptor 1 subunits. In pancreatic p-cells, KATP channels serve as glucose sensors to regulate insulin secretion. Mutations in either Kir6.2 or SUR1 that lead to loss of channel function are the major cause of congenital hyperinsulinism, a disease characterized by persistent insulin secretion despite low plasma glucose level. On the other hand, mutations in Kir6.2 that lead to gain of channel activity have recently been shown to cause neonatal diabetes. Several physiological molecules, including intracellular ATP, MgADP, and membrane phosphoinositides, especially PI-4,5-P2 (PIP2), regulate the activity of KATP channels. However, structural features of the channel proteins that are critical for control of channel activity by these molecules are not clearly understood. The goal of this application is to gain insight to the structure-function relationship of KATP channels using a forward genetics approach by studying how mutations identified in disease affect channel function. In the first aim, we will determine channel defects caused by nine novel Kir6.2 mutations identified in congenital hyperinsulinism using COS cells, addressing both defects in channel biogenesis/expression and gating. We will then evaluate how these mutations impact on p-cell physiology and how they respond to potential molecular or pharmacological treatments, by expressing mutant Kir6.2 in a rat pancreatic p-cell line INS-1. In the second aim, we will perform similar studies on Kir6.2 mutations recently identified in neonatal diabetes. In the third aim, we will identify intersubunit interactions in the cytoplasmic domain of Kir6.2 that are important for gating and for physical association between Kir6.2 subunits, based on our previous finding that disruption of an intersubunit ion pair in Kir6.2 impairs normal channel gating. We will focus on potential interactions that are mediated by residues that have been found mutated in congenital hyperinsulinism or neonatal diabetes. The proposed study will better our understanding of not only the structure-function relationships of KATP channels but also the molecular basis of insulin secretion diseases caused by channel mutations. Such knowledge may help identify novel structural sites for drug development and is essential for designing effective therapeutic strategies for these diseases.

ATP敏感钾（KAIP）通道在将细胞代谢与细胞兴奋性偶联和管理各种生理过程，包括激素分泌，血管张力的控制和缺血期间心肌和神经元活性的调节。该项目的长期目标是了解KATP通道门控的结构基础。为了实现这一目标，我们的研究重点是 KATP通道的胰腺亚型，它们是异类复合物，每个复合物由四个组成向内整理钾通道Kir6.2亚基和四个调节磺酰脲受体1个亚基。在胰腺P细胞，KATP通道是调节胰岛素分泌的葡萄糖传感器。两者中的突变导致通道功能丧失的Kir6.2或SUR1是先天性超胰岛素主义的主要原因，一个尽管血浆葡萄糖水平较低，但其特征是持续的胰岛素分泌。另一方面，最近已证明Kir6.2的突变导致通道活性获得的突变引起新生儿糖尿病。几种生理分子，包括细胞内ATP，MGADP和膜磷酸肌醇，尤其是PI-4,5-P2（PIP2），调节KATP通道的活性。但是，结构通道蛋白的特征对于控制这些分子控制通道活性至关重要的特征不是清楚地理解。该应用的目的是洞悉KATP的结构功能关系通过研究疾病中鉴定出的突变如何影响通道，使用正向遗传学方法的通道功能。在第一个目标中，我们将确定由九种新颖的Kir6.2突变引起的通道缺陷在使用COS细胞的先天性高胰岛素中，解决了通道生物发生/表达中的两个缺陷和门控。然后，我们将评估这些突变对P细胞生理学的影响以及它们如何反应潜在的分子或药理学治疗，通过在大鼠胰腺P细胞系中表达突变kir6.2 ins-1。在第二个目标中，我们将对最近在新生儿发现的Kir6.2突变进行类似的研究糖尿病。在第三个目的中，我们将确定在Kir6.2的细胞质结构域中的亚基间相互作用根据我们以前的发现，对于Kir6.2亚基之间的门控和物理关联很重要 Kir6.2中亚基离子对的破坏会损害正常通道门控。我们将专注于潜力被发现在先天性高胰岛素中突变的残基介导的相互作用或新生儿糖尿病。拟议的研究不仅将使我们对结构功能的理解更好 KATP通道的关系，也是通道引起的胰岛素分泌疾病的分子基础突变。这种知识可能有助于确定药物开发的新型结构部位，对于为这些疾病设计有效的治疗策略。