Lipid rafts, dopamine 1 receptor, and hypertension

项目摘要 多巴胺D1受体（D1 R）在血压（BP）的调节中起重要作用。DRD1 小鼠生殖细胞缺失导致高血压。G蛋白偶联受体激酶4 GRK 4在D1 R的正常细胞再循环和功能中是重要的。但部分 回收的D1 R必须靶向脂筏才能发挥功能。因此，突变体D1 Rs 347 C>A和 351 C>A仍然靶向质膜，但不能定位于脂筏;这些突变 阻止D1 R介导的刺激肾近端小管cAMP产生的增加 细胞（RPTC）和损害（例如，347 C>A）小鼠中的正常BP调节。D1 R中的C347和C351 是棕榈酰化位点; SNX 19作为D1 R棕榈酰化的支架蛋白， 高尔基体，通过高尔基体特异性锌指蛋白。脂筏也需要适当的 腺苷酸环化酶5和6的膜分布和维持以及D1 R的调节。 棕榈酰化的抑制或分子生物学破坏阻止D1 R靶向脂筏， 损害D1 R功能并导致高血压。沉默SNX 19损害D1 R介导的 在RPTC中cAMP增加，Na+转运减少，而在远曲小管细胞中不增加。 肾脏SNX 19在血压调节中很重要;肾脏限制性SNX 19沉默增加 正常但非低盐饮食的C57 Bl/6小鼠的BP。小鼠中SNX 19的种系缺失也 增加血压正常盐饮食。SNX 19是D1 R的上游。SNX 19 rs 2298566与 在人体中，Na+排泄能力降低，血压升高，并损害D1 R功能 （h）RPTC。SNX 19蛋白在来自高血压人的hRPTC中减少。我们将测试 总体假设SNX 19在RPT中D1 R向脂筏的运输中很重要 正常的D1 R功能。肾脏D1 R功能受损，导致 通过其受损的运输到RPT质膜中的脂筏，导致盐敏感 高血压具体目标1将检验SNX 19靶向D1 R进入脂质的假设 RPTC质膜的筏对于正常的D1 R功能至关重要。SNX 19和GRK 4相互作用 在脂筏中调节D1 R功能，包括D1 R介导的Na+转运抑制， RPTC。具体目标2将检验以下假设： D1 R基因阻止SNX 19将D1 R靶向RPTC血浆中脂筏的能力 膜的在C57 Bl/6小鼠中SNX 19的种系缺失或肾限制性缺失导致盐- 敏感性高血压突变DRD 1以阻止D1 R靶向RPTC血浆的脂筏 膜也会导致盐敏感性高血压。这些基因和它们的蛋白质 治疗人类原发性高血压的靶点。

Project Summary The D1 dopamine receptor (D1R) is important in the regulation of blood pressure (BP). Drd1 germline deletion in mice causes hypertension. G protein-coupled receptor kinase type 4 (GRK4) is important in the normal cellular recycling and function of D1R. However, some of the recycled D1R has to be targeted to lipid rafts to be functional. Thus, mutant D1Rs 347C>A and 351C>A still target to the plasma membrane but fail to localize in lipid rafts; these mutations prevent the increase in D1R-mediated stimulation of cAMP production in renal proximal tubule cells (RPTCs) and impair (e.g., 347C>A) normal BP regulation in mice. C347 and C351 in D1R are palmitoylation sites; SNX19 functions as a scaffold protein for the palmitoylation of D1R at the Golgi, via Golgi-specific zinc finger protein. Lipid rafts are also needed for the proper membrane distribution and maintenance of adenylyl cyclases 5 and 6 and regulation by D1R. Inhibition or molecular biological disruption of palmitoylation prevents D1R targeting to lipid rafts, impairs D1R function, and causes hypertension. Silencing SNX19 impairs D1R-mediated increase in cAMP and decrease in Na+ transport in RPTCs but not distal convoluted tubule cells. Renal SNX19 is important in the regulation of BP; renal-restricted silencing of Snx19 increases BP in C57Bl/6 mice on normal but not low salt diet. Germline deletion of SNX19 in mice also increases BP on normal salt diet. SNX19 is upstream of D1R. SNX19 rs2298566 is associated with decreased ability to excrete Na+ and high BP in humans and impairs D1R function in human (h)RPTCs. SNX19 protein is decreased in hRPTCs from hypertensive humans. We will test the overall hypothesis that SNX19 is important in the trafficking of D1R to lipid rafts in the RPT plasma membrane for normal D1R function. Impaired functioning of D1R in the kidney, caused by its impaired trafficking to lipid rafts in RPT plasma membranes, causes salt-sensitive hypertension. Specific Aim 1 will test the hypothesis that SNX19 targeting of D1R into the lipid rafts of RPTC plasma membrane is crucial for normal D1R function. SNX19 and GRK4 interact in lipid rafts to regulate D1R function, including D1R-mediated inhibition of Na+ transport in RPTCs. Specific aim 2 will test the hypothesis that mutations of the palmitoylation sites in the D1R gene prevent the ability of SNX19 to target the D1R to lipid rafts in the RPTC plasma membrane. Germline deletion or renal-restricted deletion of SNX19 in C57Bl/6 mice causes salt- sensitive hypertension. Mutating DRD1 to prevent D1R targeting to lipid rafts of RPTC plasma membrane also causes salt-sensitive hypertension. These genes and their proteins could be targets in the treatment of human essential hypertension.