Role of micro RNAs in renin cell differentiation

描述（由申请人提供）：肾素是肾素-血管紧张素系统的关键激素，调节血压和液体-电解质稳态。在胚胎发育早期，未分化的后肾间充质中存在肾素前体细胞。在胎儿后期，肾素细胞广泛分布于沿着肾内动脉和肾小球内。随着成熟，肾素细胞越来越少，并局限于经典的成人肾小球（JG）定位。如果血压或液体-电解质平衡受到威胁，则沿着肾小球前动脉、肾小球和肾小球的肾素细胞数量增加，类似于胚胎模式。肾素细胞数量的增加（募集）是由于预先存在的成体细胞的去分化，不涉及细胞迁移或复制。事实上，使用cre-lox系统，我们发现肾素细胞是产生小动脉平滑肌（SM）、系膜和间质细胞的前体，并且当稳态受到威胁时，这些细胞重新表达肾素。此外，使用双重标记的细胞模型，我们发现，小动脉SM细胞reacquire的肾素表型cAMP刺激后，染色质重塑和结合CREB在cAMP反应元件在肾素启动子介导的效果。除了这种表观遗传/转录控制之外，肾素细胞身份的获得和维持可以由内源性microRNA调节，内源性microRNA是一组在转录后水平调节基因表达并且已知调节细胞命运的非编码小RNA。条件性删除Dicer导致肾脏中JG细胞的消失，表明microRNA可能调节肾素细胞的特化和肾脏血管发育。使用严格的排除标准和筛选策略，涉及多种方法和功能测定，我们确定了两个令人兴奋的和独特的肾素细胞特异性microRNA（miR-330和miR-125 b-5 p），调节维持肌上皮样肾素细胞表型的关键基因。我们推测miR-330和miR-125 b-5 p通过控制肾素和血管平滑肌基因的表达来调节肾素细胞的特性。使用体内和体外方法，我们将测试以下假设：2）miR-330和miR-125 b-5 p具有调节肾素细胞分化状态的特征性分布模式和表达水平，3）miR-330和miR-125 b-5 p调节肾素细胞的身份和命运以及肾单位的形态发生。

DESCRIPTION (provided by applicant): Renin, the key hormone of the renin-angiotensin system, regulates blood pressure and fluid-electrolyte homeostasis. In early embryonic development, renin precursor cells are present in the undifferentiated metanephric mesenchyme. Later in fetal life, renin cells are broadly distributed along intrarenal arteries and inside the glomeruli. With maturation, renin cells are fewer and restricted to the classical adult juxtaglomerular (JG) localization. If blood pressure or fluid-electrolyte homeostasis is threatened, the number of renin cells increases along preglomerular arteries, glomeruli and interstitium resembling the embryonic pattern. The increase in renin cell number (recruitment) is due to de-differentiation of preexisting adult cells and does not involve cell migration or replication. In fact, using a cre-lox system we found that renin cells are precursors that give rise to arteriolar smooth muscle (SM), mesangial, and interstitial cells and it is these cells that re-express renin when homeostasis is threatened. Further, using a dually labeled cell model we found that arteriolar SM cells reacquire the renin phenotype upon cAMP stimulation, an effect mediated by chromatin remodeling and binding of CREB at the cAMP responsive element in the renin promoter. In addition to this epigenetic/ transcriptional control, the acquisition and maintenance of renin cell identity may be regulated by endogenous microRNAs, a group of non-coding small RNAs that regulate gene expression at the post-transcriptional level and are known to regulate cell fate. Conditional deletion of Dicer in renin cells resulted in the disappearance of JG cells in the kidney suggesting that microRNAs may regulate renin cell specification and kidney vascular development. Using stringent exclusion criteria and a screening strategy involving multiple methodologies and functional assays, we identified two exciting and unique renin cell specific microRNAs (miR-330 and miR- 125b-5p) that regulate crucial genes for the maintenance of the myoepithelioid renin cell phenotype. We hypothesize that miR-330 and miR-125b-5p regulate the identity of the renin cell by controlling the expression of renin and vascular smooth muscle genes. Using in vivo and in vitro approaches, we will test the following hypotheses: 1) microRNAs determine the temporal and spatial pattern of renin cell differentiation during development, 2) miR-330 and miR-125b-5p have a characteristic distribution pattern and expression levels that regulate the state of differentiation of the renin cell, and 3) miR-330 and miR-125b-5p regulate the identity and fate of renin cells and nephron morphogenesis.