Regulation of sodium transport and blood pressure by SPAK/OSR1 kinases

SPAK/OSR1 激酶对钠转运和血压的调节

• 批准号: 8827332
• 负责人: JAMES A MCCORMICK
• 金额: $ 32.56万
• 依托单位: OREGON HEALTH & SCIENCE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-01 至 2019-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8827332
• 关键词: Acute; Adult; Affect; Aldosterone; American; Angiotensin II; Animals; Antihypertensive Agents; Applications Grants; Blood Pressure; Cations; Chronic; Complex; Congestive Heart Failure; Data; Distal convoluted renal tubule structure; Dominant-Negative Mutation; Drug Targeting; End stage renal failure; Endocrine; Essential Hypertension; Extracellular Fluid; Goals; Heterozygote; Hormones; Hypertension; Hypotension; In Vitro; Infusion procedures; Investigation; Kidney; Knock-out; Knockout Mice; Learning; Length; Limb structure; Mammalian Cell; Mediating; Modeling; Mus; Myocardial Infarction; Nephrons; Pathway interactions; Patients; Phosphorylation; Phosphotransferases; Physiological; Play; Population; Principal Investigator; Process; Protein Isoforms; Regulation; Resources; Risk Factors; Role; Sodium; Stimulus; Stroke; Testing; Thick; Time; Tissues; United States; Vasopressins; Xenopus oocyte; blood pressure reduction; blood pressure regulation; design; dietary salt; in vivo; insight; mouse model; novel; public health relevance; response; restoration; salt sensitive; sodium-potassium chloride cotransporter 2 protein

DESCRIPTION (provided by applicant): Hypertension affects 60 million adults in the United States, and is a major independent risk factor for stroke, myocardial infarction, and congestive heart failure, and a major cause of end-stage renal disease. More than half of hypertensive patients have a salt-sensitive component, and in approximately 30%, hypertension is predominantly due to abnormalities in sodium handling by the kidney. The kinases SPAK and OSR1 play important roles in the regulation of renal sodium transport. In vitro, both kinases activate the sodium transporters NKCC2 and NCC, but little is known about the pathways via which SPAK and OSR1 activate them in whole animals. Studies in mice indicate that OSR1 is more important for activation of NKCC2, while SPAK is the main activator of NCC. Recent evidence shows that multiple forms of SPAK and OSR1 exist in the kidney, some of which inhibit sodium transport, contrary to the prevailing view that SPAK and OSR1 only activate it. Stimuli that lower blood pressure (e.g. dietary salt restriction), or administration of hormones that increase blood pressure (e.g. aldosterone, vasopressin and angiotensin II), reduce the levels of inhibitory SPAK and OSR1, but increase levels of activating forms. Regulation of renal sodium transport and blood pressure by SPAK and OSR1 is thus more complex than previously believed. The objective of this proposal is to determine the mechanisms by which SPAK and OSR1 regulate renal sodium transport. The R01 Grant application will provide the necessary resources for the principal investigator to test the hypothesis that SPAK and OSR1 isoforms differentially regulate renal sodium transport, and differentially mediate responses to physiological stimuli that alter blood pressure. To test this hypothesis, three specific aims are proposed. Aim 1 is to examine the mechanisms by which SPAK and OSR1 isoforms differentially regulate renal sodium transport. The mechanisms by which SPAK and OSR1 isoforms inhibit activity of NKCC2 will be determined using Xenopus oocytes and mammalian cells. Aim 2 is to identify the physiological factors that modulate isoform expression. Using wild-type, SPAK knockout and renal OSR1 knockout mice, the effects of sodium restriction, aldosterone infusion and induced-hypertension on the levels and renal localization of SPAK and OSR1 isoforms, as well as the mechanism and timing of these effects, will be determined. Aim 3 is to examine how SPAK and OSR1 regulate renal sodium transport and blood pressure in whole animals. The effects of acute and chronic aldosterone, vasopressin or angiotensin II administration on NCC and NKCC2 phosphorylation and activity will be determined in wild-type, SPAK knockout and renal OSR1 knockout mice. Mice lacking both SPAK and OSR1 in the kidney will also be characterized. These studies will enable us to assign specific physiological functions to either SPAK or OSR1 isoforms, a significant advance towards understanding how two closely related kinases that activate the same targets in vitro have very different roles in vivo. In addition, we will gain insight into the pathways that activate cation cotransporters independently of SPAK/OSR1.

描述（由申请人提供）：高血压影响美国 6000 万成年人，是中风、心肌梗死和充血性心力衰竭的主要独立危险因素，也是终末期肾病的主要原因。超过一半的高血压患者有盐敏感成分，大约 30% 的高血压患者主要是由于肾脏处理钠的异常造成的。激酶 SPAK 和 OSR1 在肾钠转运的调节中发挥重要作用。在体外，这两种激酶都会激活钠转运蛋白 NKCC2 和 NCC，但人们对 SPAK 和 OSR1 在整个动物中激活它们的途径知之甚少。小鼠研究表明，OSR1对于NKCC2的激活更为重要，而SPAK是NCC的主要激活剂。最近的证据表明，肾脏中存在多种形式的SPAK和OSR1，其中一些抑制钠转运，这与SPAK和OSR1仅激活钠转运的普遍观点相反。降低血压的刺激（例如饮食盐限制）或施用升压激素（例如醛固酮、加压素和血管紧张素 II），会降低抑制性 SPAK 和 OSR1 的水平，但会增加激活形式的水平。因此，SPAK 和 OSR1 对肾钠转运和血压的调节比之前认为的更为复杂。该提案的目的是确定 SPAK 和 OSR1 调节肾钠转运的机制。 R01 资助申请将为主要研究者提供必要的资源，以测试 SPAK 和 OSR1 同种型差异调节肾钠转运，并差异介导对改变血压的生理刺激的反应这一假设。为了检验这一假设，提出了三个具体目标。目标 1 是检查 SPAK 和 OSR1 亚型差异调节肾钠转运的机制。 SPAK 和 OSR1 同种型抑制 NKCC2 活性的机制将使用非洲爪蟾卵母细胞和哺乳动物细胞来确定。目标 2 是确定调节同种型表达的生理因素。使用野生型、SPAK 敲除和肾 OSR1 敲除小鼠，限制钠摄入、醛固酮输注和诱导高血压对 SPAK 和 OSR1 亚型的水平和肾脏定位的影响，以及这些影响的机制和时间，将被研究。决定。目标 3 是检查 SPAK 和 OSR1 如何调节整个动物的肾钠转运和血压。将在野生型、SPAK 敲除和肾 OSR1 敲除小鼠中确定急性和慢性醛固酮、加压素或血管紧张素 II 给药对 NCC 和 NKCC2 磷酸化和活性的影响。肾脏中同时缺乏 SPAK 和 OSR1 的小鼠也将被表征。这些研究将使我们能够将特定的生理功能分配给SPAK或OSR1亚型，这对于理解在体外激活相同靶标的两种密切相关的激酶如何在体内发挥截然不同的作用来说是一个重大进展。此外，我们将深入了解独立于 SPAK/OSR1 激活阳离子协同转运蛋白的途径。