Elucidating the effects of Olfactory Receptor 78 on blood pressure and renin release

项目摘要 我们实验室最近的研究表明，嗅觉受体78(Olfr78)是一种短链脂肪 酸(SCFA)受体，在血压调节中起关键作用。Olfr78调节肾素 对肠道微生物区系产生的丙酸等单链脂肪酸的反应而释放。到目前为止，我们有 研究表明，Olfr78在肾小球旁小球装置(JGA)中表达，Olfr78KO小鼠 在对单链脂肪酸的反应中释放肾素的能力有缺陷。然而，此外，Olfr78也在 外周血管系统中的血管平滑肌细胞；在那里它也可能对血压起作用 控制力。全身Olfr78空白小鼠在基线时表现出较低的血压，我们假设这 低血压主要由JGA中的Olfr78信号调节。确定Olfr78基因的表达 主要负责低血压表型的细胞类型，我们将使用最近创建的小鼠 其中Olfr78在JGA中使用CRE-LOX系统(Olfr78 JGA KO)选择性地被击倒的模型。 这些组织特异性基因敲除小鼠的特征将决定JGA定位的Olfr78的贡献 在全身淘汰赛中观察到的低血压表型，以及扩展到奥弗里78岁的S在 肾脏。此外，虽然已知Olfr78是一种G蛋白偶联受体，但精确的信号转导 SCFA结合和肾素释放之间的联系途径尚未显示。先前的研究表明，夏令营 产生导致JGA中肾素的释放，这种释放被胞浆升高所抑制 钙含量。为了建立Olfr78和cAMP介导的肾素释放之间的联系，计划利用稳定的 表达Olfr78永生化JGA细胞系。该细胞系将是探索这一机制的有价值的工具 潜在的Olfr780在体外介导肾素的分泌。然后，可以将后续调查结果应用回IN 活体模型以更好地理解单个OR如何影响复杂的血压过程 监管。我推测JGA中的Olfr78在血液调节中起着重要作用 压力通过肾素释放，这种释放是通过Gsα依赖的cAMP途径介导的。至 针对这一假设，我提出了以下目标。目的1：鉴定表达Olfr78的细胞类型 负责基线低血压的奥弗里78全身可见的击倒。我将描述一只老鼠模型的特征 在JGA中使用cre-lox技术选择性地击倒Olfr78的地方，特别关注 肾素水平和血压在基线和高血压应激下。目标2：确定Olfr78如何 激活导致体内肾素释放，我们将通过体外肾素释放来阐明肾素释放的机制 模特。利用永生化的小鼠肾细胞系，我们将使用各种药物抑制剂来探索 Olfr78介导的肾素释放所需的信号级联的必要组成部分。一起， 这些研究将为血压调节的新途径提供新的见解。

Project Summary Recent studies in our laboratory have demonstrated that olfactory receptor 78 (Olfr78) is a short chain fatty acid (SCFA) receptor that plays a critical role in the modulation of blood pressure. Olfr78 modulates renin release in response to SCFA’s such as propionate, which are produced by the gut microbiota. To date we have shown that Olfr78 is expressed in the renal juxtaglomerular apparatus (JGA), and that Olfr78KO mice are defective in their ability to release renin in response to SCFAs. In addition however, Olfr78 is also expressed in vascular smooth muscle cells of the peripheral vasculature; where it could also contribute to blood pressure control. Full body Olfr78 null mice exhibit lowered blood pressure at baseline, and we hypothesize that this hypotension is primarily mediated by Olfr78 signaling in the JGA. To definitively identify the Olfr78-expressing cell type which is primarily responsible for the hypotensive phenotype, we will use a recently created mouse model where Olfr78 is selectively knocked out in the JGA using a Cre-lox system (Olfr78 JGA KO). Characterization of these tissue specific knockout mice will determine the contribution of JGA-localized Olfr78 to the hypotensive phenotype observed in the full body knockout, as well as expand upon Olfr78’s role in the kidney. Furthermore, while it is known that Olfr78 is a G-protein coupled receptor, the precise signaling pathway linking SCFA binding and renin release has not yet been shown. Prior studies show that cAMP production leads to renin release in the JGA, and that this release is inhibited by the elevation of cytosolic calcium levels. To establish the link between Olfr78 and cAMP mediated renin release, plan to utilize a stably expressing Olfr78 immortalized JGA cell line. This cell line will be a valuable tool in probing the mechanism underlying Olfr780mediated renin secretion in vitro. The subsequent findings can then be applied back to the in vivo model to better understand how a single OR can impact the complex process of blood pressure regulation. I hypothesize that Olfr78 in the JGA plays a significant role in the regulation of blood pressure via renin release, and that this release is mediated via a Gsα dependent cAMP pathway. To address this hypothesis, I propose the following aims. Aim 1: To identify which Olfr78 expressing cell type is responsible for baseline hypotension seen in the full body Olfr78 knockout. I will characterize a mouse model where Olfr78 has been selectively knocked out in the JGA using cre-lox technology, looking specifically at renin levels and blood pressure at baseline and under hypertensive stress. Aim 2: To determine how Olfr78 activation leads to renin release in vivo, we will elucidate the mechanism of renin release using an in vitro model. Using an immortalized mouse kidney cell line, we will use various pharmacological inhibitors to probe the necessary components of the signaling cascade required for Olfr78 mediated renin release. Together, these studies will reveal new insights into a novel pathway of blood pressure regulation.