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

在之前建立和使用三重转基因小鼠系的研究中，我们已经展示了一种新的再生机制，在严重的系膜细胞损伤后，肾素阳性的成体祖细胞从肾小球旁的装置被招募到肾小球。因此，这些被招募的细胞一旦进入肾小球，就失去了肾素阳性并分化为系膜细胞(从头获得系膜细胞标记物)。在这项赠款提案中，将探索这种前体细胞招募机制在严重创伤后系膜细胞再生中的作用/重要性。为了分析肾素表达对前体细胞功能的作用，我们通过将我们的三重转基因小鼠(MREN-rtTam2/LC-1/tdTomato)与携带花肾素基因的小鼠(MREN-rtTam2/LC-1/tdTomato/Ren Flox)杂交，创建了肾素基因阳性的成年祖细胞中具有特定肾素基因敲除的小鼠。为了确定肾素阳性的成体祖细胞在肾小球修复中的整体重要性，我们将通过白喉毒素A(MREN-rtTAm2/LC-1/tdTomato/dTA)或白喉毒素受体(MREN-rtTam2/LC-1/tdTomato/R-DTR)的细胞类型特异性诱导表达和随后的刺激来去除这些细胞。此外，我们将以MREN-rtTAm2/LC-1/bletti小鼠为研究对象，以确定肾素来源的前体细胞在系膜再分化过程中的克隆性模式(即随机、局灶节段性、向心性)。与正常系膜细胞相比，肾素阳性前体细胞的分离、表型特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，并使我们能够在治疗上使用/操纵它们，以改进未来的再生机制。

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.