Mechanisms of Regulation of NHE-1

NHE-1的调节机制

• 批准号: 7903712
• 负责人: John R Raymond
• 金额: $ 5.59万
• 依托单位: MEDICAL UNIVERSITY OF SOUTH CAROLINA
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-20 至 2010-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7903712
• 关键词: Address; Affinity; Amendment; Apoptosis; Area; Belief; Binding; Biochemical; Biological; Calmodulin; Carbonic Anhydrase II; Cardiomyopathies; Cell Cycle Regulation; Cell Volumes; Cell membrane; Cell physiology; Cells; Clinical; Congestive Heart Failure; Crystallography; Development; Electrostatics; Evolution; Family; Foundations; Future; Goals; Hypertension; Kidney Failure; Knowledge; Lead; Learning; Left Ventricular Hypertrophy; Lipids; Literature; Maintenance; Mammalian Cell; Mediating; Membrane; Membrane Lipids; Methodology; Methods; Modeling; Molecular; Molecular Models; Muscle Contraction; Myocardium; Nature; Nucleic Acid Regulatory Sequences; Pathway interactions; Peptides; Phosphorylation; Play; Proteins; Protons; Public Health; Reagent; Regulation; Renal function; Reperfusion Injury; Role; Slide; Sodium; Stimulation of Cell Proliferation; Stimulus; Structure; Testing; Tyrosine Phosphorylation; Ursidae Family; Work; base; blood pressure regulation; carbonate dehydratase; clinically relevant; extracellular; genetic regulatory protein; improved; insight; molecular modeling; novel; public health relevance; research study; solute

DESCRIPTION (provided by applicant): This is a twice-amended R01 renewal application, the purpose of which is to study the molecular mechanisms of the rapid regulation of the type-1 sodium-proton exchanger, NHE-1 (also known as product of SLC9A1, solute carrier family 9A, type 1). NHE-1 is ubiquitous, being expressed on the plasma membrane of virtually every mammalian cell. It mediates the 1:1 exchange of extracellular Na+ for intracellular H+, thereby maintaining intracellular pH. NHE-1 also plays cell-specific roles in cell volume maintenance, mitogenesis, cell- cycle regulation, apoptosis and a host of other cellular functions. NHE-1 has also been implicated in clinically relevant conditions such as hypertension, left ventricular hypertrophy, and ischemia-reperfusion injury. Despite its ubiquitous expression in mammalian cells and its potential clinical relevance, much remains to be learned regarding the molecular mechanisms through which this important protein is regulated. We seek a better understanding of the mechanisms through which NHE-1 is activated. We propose a model based on the idea that phosphorylation of NHE-1 and binding of CaM to NHE-1, disrupt electrostatic tethers that occlude the proton sensing and transport regions of NHE-1 in its basal state. Disruption of the tethers allows access of ambient protons to the proton sensing and transport regions of NHE-1, thus resulting in its activation. The activation is potentially facilitated by CA-II, which could couple to NHE-1 in a "metabolon", and which could gain access to the proton sensing and transport regions of NHE-1 by sliding into a pocket created when the electrostatic tethers are disrupted. This model will be tested in three specific aims: Aim #1: We will examine the role of Jak2-induced tyrosine phosphorylation of CaM in the activation of NHE-1. Aim #2: We will examine the role of carbonic anhydrase type 2 (CA-II) as a key regulatory protein that increases the activity of NHE-1. Aim #3: We will examine the role of electrostatic interactions involving the carboxyl terminus of NHE-1 in its activation. We believe that the proposal has been significantly improved by focusing on evaluating this potentially unifying mechanism of activation of NHE-1, which is a natural outgrowth of our previous work in this area, and which could serve as the foundation for the development of a molecular model for the activation of NHE-1. This proposal could also lay the foundation for future structural experiments utilizing NMR and/or crystallography methods. PUBLIC HEALTH RELEVANCE This project is relevant to public health in that NHE-1 is involved in the regulation of blood pressure, kidney function and heart muscle contraction. The work could lead to new therapies for hypertension, congestive heart failure, cardiomyopathies and kidney failure.

描述（由申请人提供）：这是一份两次修改的R01续期申请，目的是研究1型钠-质子交换剂NHE-1（也称为SLC9A1产物，溶质载体族9A， 1型）快速调控的分子机制。NHE-1是普遍存在的，在几乎所有哺乳动物细胞的质膜上表达。它介导细胞外Na+与细胞内H+的1:1交换，从而维持细胞内ph。NHE-1还在细胞体积维持、有丝分裂、细胞周期调节、细胞凋亡和许多其他细胞功能中发挥细胞特异性作用。NHE-1也与高血压、左心室肥厚和缺血再灌注损伤等临床相关疾病有关。尽管它在哺乳动物细胞中普遍表达，并具有潜在的临床意义，但关于这种重要蛋白质的调节分子机制，仍有许多有待了解的地方。我们试图更好地了解NHE-1被激活的机制。我们提出了一个基于NHE-1磷酸化和CaM与NHE-1结合的模型，该模型破坏了静电系带，这些静电系带阻断了NHE-1在基态的质子传感和传输区域。束缚的破坏允许周围的质子进入NHE-1的质子感应和传输区域，从而导致其激活。CA-II可能会促进这种激活，CA-II可以在“代谢物”中与NHE-1偶联，并且可以通过滑入静电系链被破坏时产生的口袋来进入NHE-1的质子感应和传输区域。该模型将在三个特定目标中进行测试：目标1：我们将研究jak2诱导的CaM酪氨酸磷酸化在NHE-1激活中的作用。目的2：我们将研究2型碳酸酐酶（CA-II）作为增加NHE-1活性的关键调节蛋白的作用。目标3：我们将研究涉及NHE-1羧基末端的静电相互作用在其激活中的作用。我们认为，通过专注于评估NHE-1激活的潜在统一机制，我们的建议已经得到了显着改进，这是我们之前在该领域工作的自然结果，并且可以作为开发NHE-1激活的分子模型的基础。这一建议也为未来利用核磁共振和/或晶体学方法进行结构实验奠定了基础。