Progression of glomerulosclerosis is associated with loss of podocytes with subsequent glomerular tuft instability. It is thought that a diminished number of podocytes may be able to preserve tuft stability through cell hypertrophy associated with cell cycle reentry. At the same time, reentry into the cell cycle risks podocyte detachment if podocytes cross the G1/S checkpoint and undergo abortive cytokinesis. In order to study cell cycle dynamics during chronic kidney disease (CKD) development, we used a FUCCI model (fluorescence ubiquitination-based cell cycle indicator) of mice with X-linked Alport Syndrome. This model exhibits progressive CKD and expresses fluorescent reporters of cell cycle stage exclusively in podocytes. With the development of CKD, an increasing fraction of podocytes in vivo were found to be in G1 or later cell cycle stages. Podocytes in G1 and G2 were hypertrophic. Heterozygous female mice, with milder manifestations of CKD, showed G1 fraction numbers intermediate between wild-type and male Alport mice. Proteomic analysis of podocytes in different cell cycle phases showed differences in cytoskeleton reorganization and metabolic processes between G0 and G1 in disease. Additionally, in vitro experiments confirmed that damaged podocytes reentered the cell cycle comparable to podocytes in vivo. Importantly, we confirmed the upregulation of PDlim2, a highly expressed protein in podocytes in G1, in a patient with Alport Syndrome, confirming our proteomics data in the human setting. Thus, our data showed that in the Alport model of progressive CKD, podocyte cell cycle distribution is altered, suggesting that cell cycle manipulation approaches may have a role in the treatment of various progressive glomerular diseases characterized by podocytopenia.

肾小球硬化的进展与足细胞丢失以及随后的肾小球簇不稳定有关。据认为，减少数量的足细胞可能能够通过与细胞周期折返相关的细胞肥大来保持簇稳定性。同时，如果足细胞穿过 G1/S 检查点并经历流产的胞质分裂，则重新进入细胞周期可能会导致足细胞脱离。为了研究慢性肾病 (CKD) 发展过程中的细胞周期动力学，我们使用了 X 连锁 Alport 综合征小鼠的 FUCCI 模型（基于荧光泛素化的细胞周期指标）。该模型表现出进行性 CKD，并仅在足细胞中表达细胞周期阶段的荧光报告基因。随着 CKD 的发展，体内足细胞的比例增加发现处于 G1 或更晚的细胞周期阶段。G1和G2的足细胞肥大。具有轻度 CKD 表现的杂合雌性小鼠显示出介于野生型和雄性 Alport 小鼠之间的 G1 分数数。对不同细胞周期阶段足细胞的蛋白质组学分析显示，疾病中 G0 和 G1 之间的细胞骨架重组和代谢过程存在差异。此外，体外实验证实，受损的足细胞重新进入细胞周期，与体内足细胞相当. 重要的是，我们证实了 PDlim2 的上调，PDlim2 是 G1 期足细胞中高表达的蛋白质，在 Alport 综合征患者中，证实了我们在人类环境中的蛋白质组学数据。因此，我们的数据显示，在进行性 CKD 的 Alport 模型中，足细胞细胞周期分布发生了改变，这表明细胞周期操作方法可能在治疗以足细胞减少症为特征的各种进行性肾小球疾病中发挥作用。