The Role of Renin-lineage Cells from the Juxtaglomerular Apparatus for Mesangial cell Regeneration after glomerular Injury

在之前的研究中，我们创建并使用了一个三重转基因小鼠系，我们已经展示了一种新的再生机制，肾素阳性的肾小球旁成体祖细胞来自肾小球旁器官，在肾小球系膜细胞严重损伤后进入肾小球。因此，在进入肾小球后，这些募集的细胞失去肾素阳性并分化为系膜细胞（重新获得系膜细胞标记物）。本课题将探讨前体细胞募集机制在严重损伤后系膜细胞再生中的作用和重要性。为了分析肾素表达在前细胞功能中的作用，我们通过将我们的三转基因小鼠（mRen-rtTAm2/LC-1/tdTomato）与携带固定肾素基因的小鼠（mRen-rtTAm2/LC-1/tdTomato/Ren flox）杂交，在肾素阳性的成年祖细胞中构建了特异性敲除肾素的小鼠。为了表征肾素阳性成人祖细胞对肾小球修复的总体重要性，我们将通过细胞类型特异性诱导表达白喉毒素A （mRen-rtTAm2/LC-1/tdTomato/DTA）或白喉毒素受体（mRen-rtTAm2/LC-1/tdTomato/R-DTR）并随后刺激这些细胞。此外，我们将研究mRen-rtTAm2/LC-1/Confetti小鼠，以确定肾素来源的前体细胞在系膜再生过程中的克隆模式（即随机、局部-节段性、向心性）。肾素阳性祖细胞与正常系膜细胞的分离、表型表征和转录分析将进一步帮助我们更好地了解这些细胞的潜力和独特特征。从长远来看，本提案的预期结果将展示肾素阳性前体细胞的特殊特征和潜力，并允许我们在治疗上使用/操纵它们以改进这种再生机制。

In previous studies creating and using a triple transgenic mouse line, we have shown a novel regenerative mechanism, where renin-positive juxtaglomerular adult progenitor cells were recruited from the juxtaglomerular apparatus into glomeruli after severe mesangial cell injury. Hereby, upon entering the glomerulus these recruited cells lose their renin-positivity and differentiate into mesangial cells (de novo acquiring mesangial cell markers).In this grant proposal, the role / importance of this mechanism of precursor cell recruitment for mesangial cell regeneration after severe injury will be explored.To analyze the role of renin expression for precursor cell function, we created mice with a specific renin knockout in renin-positive adult progenitor cells via crossing our triple-transgenic mice (mRen-rtTAm2/LC-1/tdTomato) with mice carrying a floxed renin gene (mRen-rtTAm2/LC-1/tdTomato/Ren flox). To characterize the overall importance of renin-positive adult progenitor cells for glomerular repair, we will ablate these cells by cell type specific inducible expression of either diphtheria toxin A (mRen-rtTAm2/LC-1/tdTomato/DTA) or diphtheria toxin receptor (mRen-rtTAm2/LC-1/tdTomato/R-DTR) and subsequent stimulation. Furthermore, we will study mRen-rtTAm2/LC-1/Confetti mice to identify the clonality pattern (i.e. random, focal-segmental, centripetal) of renin-derived precursor cells during mesangial repopulation.The isolation, phenotypic characterization, and transcriptom analysis of renin-positive progenitor cells compared to normal mesangial cells, will further help us to better understand the potential and unique features of these cells. In perspective, the anticipated results from the present proposal will demonstrate the special features and potential of the renin-positive precursor cells and allow us to therapeutically use/manipulate them for an improvement of this regenerative mechanism in the future.