Angiotensin Receptor Regulation By Upstream Short Open Reading Frames

描述（由申请人提供）：血管紧张素II（Ang II）在体液稳态和血压（BP）中起关键作用。我们最近发现，在血管紧张素1a型受体（AT 1aR）mRNA的5'前导序列的外显子2的短开放阅读框内编码的7个氨基酸的肽（PEP 7）抑制细胞外信号调节蛋白激酶1和2（Erk 1/2）的Ang II活化，并调节AT 1aR在细胞中的运输。PEP 7还显著降低了Ang II介导的钠摄入量，而对Ang II介导的水摄入量没有任何影响，并且它拮抗了Ang II诱导的BP升高。目的1将确定PEP 7抑制Erk 1/2激活的信号转导机制。我们将检验PEP 7抑制Erk 1/2激活是Ang II依赖性的，并通过AT 1aR-G蛋白非依赖性的β-arrestin信号通路介导的假设。我们还将研究PEP 7调节AT 1aR囊泡运输抑制AT 1aR偶联到β-arrestin途径使用药理学和分子方法，共聚焦显微镜。目的2将阐明PEP 7调节体液和电解质稳态的机制。我们将在体内研究PEP 7在钠摄入量升高的病理生理模型中的作用，包括低钠性低血容量和等渗性低血容量，以及调节中枢催产素和加压素通路的条件，以及选择性抑制G蛋白介导的蛋白激酶C和G蛋白非依赖性Erk 1/2信号级联的条件。目的3将通过研究PEP 7在Ang II和儿茶酚胺依赖性高血压模型中对动脉压的影响来确定PEP 7的抗高血压作用是否是Ang II依赖性的。我们还将确定PEP 7在两种盐敏感性模型中是否有效降低血压，以及减少钠摄入在这些效应中起什么作用。通过实现这些目标，我们将深入了解PEP 7生物学，可以利用它来开发新的干预措施，用于因膳食钠而恶化的疾病，如盐敏感性高血压。

DESCRIPTION (provided by applicant): Angiotensin II (Ang II) plays a key role in fluid homeostasis and blood pressure (BP). We have recently found that a seven amino acid peptide (PEP7) encoded within a short open reading frame in exon 2 of the 5' leader sequence of the angiotensin type 1a receptor (AT1aR) mRNA inhibits Ang II activation of extracellular signal-regulated protein kinases 1 and 2 (Erk1/2) and regulates AT1aR trafficking in cells. PEP7 also markedly reduced Ang II-mediated sodium intake without having any effect on Ang II-mediated water intake and it antagonized Ang II- induced increases in BP. Aim 1 will determine the signaling mechanism by which PEP7 inhibits Erk1/2 activation. We will test the hypothesis that PEP7 inhibition of Erk1/2 activation is Ang II dependent and mediated via the AT1aR-G protein-independent ß-arrestin signaling pathway. We will also investigate PEP7 regulation of AT1aR vesicular trafficking by inhibiting AT1aR coupling to the ß-arrestin pathway using both pharmacological and molecular approaches, and confocal microscopy. Aim 2 will elucidate the mechanism by which PEP7 regulates fluid and electrolyte homeostasis. We will investigate PEP7 effects in vivo in pathophysiological models of elevated sodium intake including hyponatremic hypovolemia and isotonic hypovolemia as well as conditions that modulate central oxytocin and vasopressin pathways and those that selectively inhibit G protein-mediated protein kinase C and G protein-independent Erk1/2 signaling cascades. Aim 3 will determine if the antihypertensive effects of PEP7 are Ang II-dependent by investigating PEP7 effects on arterial pressure in models of Ang II- and catecholamine- dependent hypertension. We will also determine if PEP7 is effective at lowering BP in two models of salt-sensitivity and what role reduced sodium intake plays in these effects. By achieving these aims, we will gain insight into PEP7 biology that could be leveraged toward developing novel interventions for diseases that are worsened by dietary sodium, like salt- sensitive hypertension.