Epigenetic Control of Nephron Progenitor Cell Lifespan

肾再生领域取得进展的一个重要障碍是对阻止肾生成的机制认识不足。最近的遗传学和表观遗传学证据表明，肾单位祖细胞的寿命并不是固定的。我们已发表的和初步的数据表明，小鼠围产期的特点是单细胞染色质景观的显着变化，打破了鼻咽癌自我更新和分化的平衡。这项为期一年的Bridge R56赠款提案的主要目的是生成审查小组要求的初步数据，支持我们的假设，即通过组蛋白H3K27甲基化/去甲基化平衡建立的染色质/组蛋白二价体通过抑制染色质对促分化转录因子的可及性来维持NPC的寿命。在目标1A中，我们将产生鼻咽癌特异性Kdm6b缺失小鼠，以检验抑制发育促进剂H3K27去甲基化将推迟肾脏形成停止的时间和增强肾单位捐赠的假设。目的1B将产生鼻咽癌特异性激活转录因子(ATF4)转基因小鼠，以验证ATF4足以阻止肾脏发生的假说。通过单细胞分析，我们发现了围产期鼻咽癌ATF4基序活性的差异浓缩。有趣的是，ATF4基序富含二价启动子，支持染色质二价控制NPC寿命的总体假设。总而言之，这些研究的结果将为竞争性更新应用奠定坚实的基础，这将深入研究基于染色质的停止肾生成的机制。 该项目的成功完成将对确定肾单位祖细胞维持的表观遗传控制规则产生广泛影响。这些知识可能被转化为优化肾单位再生和理解肾脏疾病的表观遗传学程序。

A significant barrier to progress in the renal regeneration field is insufficient knowledge surrounding the mechanisms driving cessation of nephrogenesis. Recent genetic and epigenetic evidence demonstrated that the lifespan of nephron progenitor cells (NPCs) is not fixed. Our published and preliminary data indicate that the perinatal period in mice is characterized by remarkable changes in the single-cell chromatin landscape that tip the balance of NPC self-renewal and differentiation. The principal aim of this one-year Bridge R56 grant proposal is to generate the preliminary data requested by the Review Panel supporting our hypothesis that chromatin/histone bivalency, established through the balance of histone H3K27 methylation/demethylation, maintains the NPC lifespan by restraining chromatin accessibility to pro-differentiation transcription factors. In Aim 1A, we will generate NPC-specific Kdm6bnull mice to test the hypothesis that inhibiting H3K27 demethylation of developmental enhancers will delay the timing of cessation of nephrogenesis and enhance nephron endowment. Aim 1B will generate NPC-specific activating transcription factor (ATF4)-transgenic mice to test the hypothesis that ATF4 is sufficient to drive the cessation of nephrogenesis. We discovered differential enrichment of ATF4 motif activity in perinatal NPCs by single-cell analysis. Interestingly, ATF4 motifs are enriched in bivalent promoters, supporting the overall premise that chromatin bivalency controls NPC lifespan. Collectively, the results of these studies will form a strong basis for the competitive renewal application, which will delve into the chromatin-based mechanisms of cessation of nephrogenesis. Successful completion of this project will have broad impacts on defining the rules of epigenetic control of nephron progenitor maintenance. This knowledge may be translated to optimizing nephron regeneration and understanding epigenetic programming of renal disease.