Research Project 2: Molecular analysis of developing post-natal mouse kidney in health and FSGS

总结 出生后，小鼠的肾脏继续发育数周，人类则持续数月至数年。期间 在此期间，出生后的肾脏正在经历生长和成熟，这需要动态变化， 基因表达、代谢和生理功能，并且容易受到损伤， 形态变化和功能适应。出生后肾脏的生长和成熟起着至关重要的作用， 在发育性疾病中的重要作用。例如，婴儿出生时， 肾单位数量可能对代谢应激更敏感，如高脂肪或高盐饮食，肥胖， 缺氧或肾毒素引起的肾损伤。许多研究已经生成了胎儿和成人的单细胞数据集 小鼠肾脏。然而，尽管出生后的侮辱在发展和进展的重要作用， CKD，出生后肾脏的成熟尚未在分子水平上进行全面研究 使用最先进的技术。由于缺乏这一关键发展时期的参考地图集， 研究儿童肾脏疾病模型中细胞状态变化和多样性的能力。 肾小球疾病，包括肾病综合征，是儿童肾病的重要原因。 疾病局灶节段性肾小球硬化症（FSGS）是一种频率增加的诊断， 经常复发和治疗抵抗，并导致终末期肾病。继发性肾小球硬化 和蛋白尿发生在影响儿童的常见非肾小球疾病中，如CAKUT，并预示着 发展为终末期肾衰竭的风险更高。目前，有有限的治疗选择来治疗 这些疾病和迫切需要更好地了解疾病机制。其中一个主要机制是 细胞对压力或损伤的反应是通过利用染色质修饰机制来重编程基因， 监管网络。我们开发了一种新型的由于转移瘤功能丧失而导致FSGS的小鼠模型 相关蛋白2（Mta 2），NuRD染色质重塑复合物的核心组分。这些突变 小鼠是研究肾单位捐赠中临床上无症状的缺陷以及 改变的细胞分化可以在青春期后期/成年早期表现为FSGS。 在这个建议中，我们将产生一个集成的单细胞和空间转录组学小鼠图谱 （pKidCAP）在出生后的时间点，与主要的生理和发育变化相一致，在出生后的时间点， 肾我们将确定细胞多样性的进化、空间定位、单细胞基因表达 健康和FSGS组织中发育中的出生后肾脏中的特征和染色质可及性状态。 我们将应用ChIP-seq和表观基因组编辑来测试Jun/AP-1靶向细胞中的去阻遏的假设。 mta 2突变体促进炎症、细胞衰老和脂毒性。将这些数据集与 人类pKidCAP图谱（项目1）将创建一个独特参考组，以鉴定小鼠中未发现的途径 与儿童肾脏疾病高度相关的模型。

Summary After birth, the kidney continues to develop for weeks in mice, and for months to years in humans. During this period, the post-natal kidney is undergoing growth and maturation, which requires dynamic changes in gene expression, metabolism, and physiological functions, and is susceptible to insults causing permanent morphological changes and functional adaptation. Post-natal growth and maturation of the kidney play an important role in developmentally programmed diseases. For e.g., children born with a moderate reduction in nephron number may be more sensitive to metabolic stresses, such as high fat or high salt diet, obesity, and renal injury from hypoxia or nephrotoxins. Many studies have generated single cell datasets for fetal and adult mouse kidney. However, in spite of the important role of post-natal insults in development and progression of CKD, post-natal maturation of the kidney has not been comprehensively investigated at the molecular level using state-of-the-art technologies. The lack of a reference atlas for this critical developmental period limits our ability to investigate alterations in cell states and diversity in models of pediatric kidney disease. Glomerular diseases, including nephrotic syndrome, represent an important cause of childhood kidney disease. Focal and segmental glomerulosclerosis (FSGS) is a diagnosis that is increasing in frequency, is often recurrent and treatment resistant, and leads to end stage kidney disease. Secondary glomerulosclerosis and albuminuria develop in common non-glomerular diseases affecting children, such as CAKUT, and portend a higher risk of progression to end stage kidney failure. Currently, there are limited therapeutic options to treat these disorders and a pressing need to better understand disease mechanisms. One of the major mechanisms by which cells respond to stress or injury is by utilizing the chromatin modifying machinery to reprogram gene regulatory networks. We developed a novel mouse model of FSGS due to loss of function of metastases associated protein 2 (Mta2), a core component of the NuRD chromatin remodeling complex. These mutant mice represent an excellent model to investigate how clinically silent defects in nephron endowment and altered cell differentiation can manifest as FSGS in late adolescence/early adulthood. In this proposal we will generate an integrated single cell and spatial transcriptomics mouse atlas (pKidCAP) at post-natal timepoints that coincide with major physiological and developmental changes in the kidney. We will determine the evolution of cell diversity, spatial localization, single cell gene expression signatures and chromatin accessibility states in the developing post-natal kidney in healthy and FSGS tissue. We will apply ChIP-seq and epigenomic editing to test the hypothesis that de-repression of Jun/AP-1 targets in Mta2 mutants promotes inflammation, cell senescence and lipotoxicity. Integration of these datasets with the human pKidCAP atlas (Project 1) will create a unique reference panel to identify pathways uncovered in mouse models that are highly relevant to kidney diseases in children.