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（由适用提供）：ATP敏感钾（KATP）通道夫妇将细胞代谢与膜兴奋性。他们通过引起适合代谢信号的身体反应在能量稳态中发挥着至关重要的作用。 KATP通道是内部整流钾（KIR）通道家族的成员，在需要与ABC转运蛋白的磺基脲受体（SUR）合作组装以进行功能表达。在胰腺细胞中，由KIR6.2和SUR1中位葡萄糖刺激的胰岛素分泌形成的KATP通道。降低信道功能的Kir6.2或SUR1中的突变会导致先天性超胰岛素化，而那些增加信道功能的突变会导致新生儿糖尿病。 Kir6.2和Sur1在通道复杂的门控调节中都起着不可或缺的作用。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。上一个周期中的工作已经确定并阐明了孔隙门控在通道门控中的孔形成亚基6.2的几种结构特征的作用。在此续订应用中，我们将解决SUR1和KIR6.2之间功能耦合的机制。 SUR1增加了KiR6.2的开放概率（PO），使KiR6.2对ATP的抑制作用和膜磷酸肌醇的刺激作用增强，并赋予MGADP以及药物学剂硫氟烷和非氮杂对Kir6.2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。然而，关于SUR1对KIR6.2执行多重影响的机制仍然存在很大的知识差距。这种更新应用的目的是阐明负责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，以解释SUR1如何暗示其对Kir6.2门控的多重影响。具体而言，我们假设SUR1通过在SUR1中TMD0的短细胞质环与Kir6.2的N端域中的短细胞质环中的残留物之间的分子相互作用来稳定Kir6.2在PIP2结合的开放状态中的Kir6.2通过分子相互作用来赋予KATP通道的固有PO；和ATP，MGADP和药理剂反过来调节通道活性，从而改变SUR1-KIR6.2界面以增强或弱通道PIP2相互作用。我们将采用疾病突变，引导诱变筛查，化学交联和结构建模方法来检验假设，将其交织在一起。这项研究具有创新性，因为它为该领域提出了一个新颖的概念。从人类健康和基础科学的角度来看，这项研究至关重要。它将确定新的疾病机制，以直接促进和治疗几种罕见但毁灭性的婴儿/儿童疾病，并会更好地理解该通道的结构功能关系，从而促进有关如何调节通道活动以治疗由通道功能障碍引起的疾病的新想法，包括II型糖尿病，包括II型糖尿病。这也将使人们更好地理解沉默的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。公共卫生相关性：ATP敏感钾（KATP）通道在将代谢信号与许多细胞类型的身体反应联系起来方面起着关键作用。 KATP通道的功能障碍会导致人类疾病，包括糖尿病，超胰岛素，心脏肌病和神经系统缺陷。该项目的目的是了解该通道开放或关闭的分子基础，根据代谢信号促进通道功能障碍引起的疾病的新型热剂的开发。