Role of micro RNAs in renin cell differentiation

描述（申请人提供）：肾素是肾素-血管紧张素系统的关键激素，调节血压和体液电解质稳态。在早期胚胎发育中，肾素前体细胞存在于未分化的后肾间质中。在胎儿后期，肾素细胞广泛分布在肾内动脉和肾小球内。随着成熟，肾素细胞减少并局限于典型的成人肾小球旁（JG）定位。如果血压或体液电解质稳态受到威胁，肾素细胞的数量会沿着肾小球前动脉、肾小球和间质增加，类似于胚胎模式。肾素细胞数量的增加（招募）是由于先前存在的成年细胞的去分化，而不涉及细胞迁移或复制。事实上，使用crex -lox系统，我们发现肾素细胞是产生小动脉平滑肌（SM）、系膜细胞和间质细胞的前体，当体内平衡受到威胁时，正是这些细胞重新表达肾素。此外，使用双标记细胞模型，我们发现小动脉SM细胞在cAMP刺激下重新获得肾素表型，这是一种由染色质重塑和CREB结合肾素启动子中cAMP响应元件介导的效应。除了这种表观遗传/转录控制外，肾素细胞身份的获得和维持可能受到内源性microrna的调节，这是一组非编码小rna，在转录后水平调节基因表达，已知可调节细胞命运。肾素细胞中Dicer的条件缺失导致肾脏中JG细胞的消失，这表明microrna可能调节肾素细胞的特异性和肾血管的发育。通过严格的排除标准和涉及多种方法和功能分析的筛选策略，我们确定了两个令人兴奋和独特的肾素细胞特异性microrna (miR-330和miR- 125b-5p)，它们调节维持肌上皮样肾素细胞表型的关键基因。我们假设miR-330和miR-125b-5p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身份。通过体内和体外方法，我们将验证以下假设：1)microrna决定肾素细胞在发育过程中分化的时空格局；2)miR-330和miR-125b-5p具有调节肾素细胞分化状态的特征分布模式和表达水平；3)miR-330和miR-125b-5p调节肾素细胞的身份和命运以及肾素形态发生。

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. PUBLIC HEALTH RELEVANCE: Understanding the mechanisms that govern the identity and plasticity of the renin cell is of fundamental biological and medical importance. Information gained from the proposed studies may help children and adults affected by kidney diseases and hypertension.