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

项目摘要 本实验室最近的研究表明，嗅觉受体78（Olfr 78）是一种短链脂肪酸， 酸（SCFA）受体，其在血压调节中起关键作用。Olfr 78调节肾素 在一些实施方案中，肠内微生物群响应于SCFA如丙酸盐而释放，其由肠道微生物群产生。迄今为止， 显示Olfr 78在肾肾小球器（JGA）中表达，并且Olfr 78 KO小鼠是 它们响应SCFA释放肾素的能力有缺陷。然而，另外，Olfr 78也在大肠杆菌中表达。 外周血管系统的血管平滑肌细胞;也可能导致血压升高 控制全身Olfr 78敲除小鼠在基线时表现出降低的血压，我们假设这是因为 低血压主要由JGA中的Olfr 78信号传导介导。为了明确鉴定表达Olfr 78的 细胞类型，这是主要负责水肿表型，我们将使用最近创建的小鼠 模型，其中使用Cre-lox系统在JGA中选择性敲除Olfr 78（Olfr 78 JGA KO）。 这些组织特异性敲除小鼠的表征将确定JGA定位的Olfr 78的贡献。 在全身敲除中观察到的过度表型，以及扩大Olfr 78在 肾此外，虽然已知Olfr 78是G蛋白偶联受体，但精确的信号传导机制可能与G蛋白偶联受体有关。 连接SCFA结合和肾素释放的途径尚未显示。先前的研究表明，cAMP 产生导致JGA中的肾素释放，并且这种释放被细胞质中的升高所抑制。 钙水平。为了建立Olfr 78和cAMP介导的肾素释放之间的联系，计划利用稳定的 表达Olfr 78的永生化JGA细胞系。该细胞系将是探索该机制的有价值的工具 Olfr 780在体外介导的肾素分泌。随后的调查结果可以应用到实际情况中 体内模型，以更好地了解单个OR如何影响血压的复杂过程 调控我推测JGA中的Olfr 78在血液调节中起着重要作用。 这种释放是通过Gsα依赖性cAMP途径介导的。到 针对这一假设，我提出以下目标。目的1：鉴定哪种Olfr 78表达细胞类型是 导致在全身Olfr 78敲除中观察到的基线低血压。我将描述一个小鼠模型 其中Olfr 78已在使用cre-lox技术的JGA中被选择性地敲除，特别关注 在基线和高血压应激下的肾素水平和血压。目的2：确定Olfr 78 激活导致体内肾素的释放，我们将阐明肾素释放的机制，使用体外 模型使用永生化的小鼠肾细胞系，我们将使用各种药理学抑制剂来探测 Olfr 78介导的肾素释放所需的信号级联的必要组分。在一起， 这些研究将揭示新的血压调节途径。

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.