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）：高血压影响美国的6000万成年人，是中风，心肌梗塞和充血性心力衰竭的主要独立危险因素，也是终末期肾脏疾病的主要原因。超过一半的高血压患者具有盐敏感成分，在大约30％的情况下，高血压主要是由于肾脏钠处理中的异常。激酶SPAK和OSR1在调节肾脏钠运输的调节中起着重要作用。在体外，两种激酶都激活了钠转运蛋白NKCC2和NCC，但对通过这些途径在整个动物中激活它们的途径知之甚少。在小鼠中的研究表明，OSR1对于激活NKCC2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，其中一些抑制了钠的运输，这与普遍的观点相反，即SPAK和OSR1仅激活它。降低血压（例如饮食盐限制）或增加血压的激素（例如醛固酮，加压素和血管紧张素II）的刺激降低了抑制性SPAK和OSR1的水平，但增加了激活形式的水平。因此，SPAK和OSR1对肾脏钠转运和血压的调节比以前认为的要复杂。该提案的目的是确定SPAK和OSR1调节肾脏钠转运的机制。 R01赠款的应用将为主要研究者提供必要的资源，以测试SPAK和OSR1同工型通过差异调节肾脏钠转运的假设，并差异介导对改变血压的生理刺激的反应。为了检验这一假设，提出了三个具体目标。目的1是检查SPAK和OSR1同工型通过差异调节肾脏钠转运的机制。 SPAK和OSR1同工型抑制NKCC2活性的机制将使用爪蟾卵母细胞和哺乳动物细胞确定。目的2是确定调节同工型表达的生理因素。使用野生型，SPAK基因敲除和肾OSR1敲除小鼠，钠限制，醛固酮输注和诱导 - 高素质对SPAK和OSR1同工型的水平和肾脏定位的影响以及这些作用的机制和时机。 AIM 3是检查SPAK和OSR1如何调节整个动物的肾脏钠运输和血压。急性和慢性醛固酮，加压素或血管紧张素II对NCC和NKCC2磷酸化和活性的影响将在野生型，SPAK敲除和肾脏OSR1敲除小鼠中确定。肾脏中缺乏SPAK和OSR1的小鼠也将被描述。这些研究将使我们能够为SPAK或OSR1同工型分配特定的生理功能，这是朝着了解两个密切相关的激酶在体外激活相同靶标的密切相关的激酶在体内的作用截然不同的。此外，我们将深入了解独立于SPAK/OSR1激活阳离子共转运蛋白的途径。