GOFARR Laboratory for Organ Regenerative Research and Cell Therapeutics in Urology, Saban Research Institute, Division of Urology, Children's Hospital Los Angeles, Los Angeles, California, USA; Division of Nephrology, Department of Pediatrics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
GOFARR Laboratory for Organ Regenerative Research and Cell Therapeutics in Urology, Saban Research Institute, Division of Urology, Children's Hospital Los Angeles, Los Angeles, California, USA.
Kidney Int. 2022 Jan;101(1):106-118. doi: 10.1016/j.kint.2021.08.026. Epub 2021 Sep 23.
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 podocytes 的丢失有关，随后肾小球丛不稳定。据认为，减少的 podocytes 数量可能通过与细胞周期再进入相关的细胞肥大来维持丛的稳定性。与此同时，细胞周期重新进入有 podocyte 脱离的风险，如果 podocyte 跨越 G1/S 检查点并经历有丝分裂失败。为了研究慢性肾脏病 (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 (荧光泛素化细胞周期指示剂)。该模型表现出进行性 CKD，并专门在 podocytes 中表达细胞周期阶段的荧光报告基因。随着 CKD 的发展，体内越来越多的 podocyte 被发现处于 G1 或更晚的细胞周期阶段。处于 G1 和 G2 的 podocyte 发生了肥大。CKD 表现较轻的杂合子雌性小鼠的 G1 分数介于野生型和雄性 Alport 小鼠之间。不同细胞周期阶段 podocyte 的蛋白质组学分析显示，疾病状态下 G0 和 G1 之间细胞骨架重排和代谢过程存在差异。此外，体外实验证实受损的 podocyte 可比体内的 podocyte 更频繁地重新进入细胞周期。重要的是，我们在 Alport 综合征患者中证实了 PDlim2 的上调，PDlim2 是 G1 中 podocyte 中高度表达的蛋白，证实了我们在人类环境中的蛋白质组学数据。因此，我们的数据表明，在进行性 CKD 的 Alport 模型中，podocyte 细胞周期分布发生改变，这表明细胞周期操纵方法可能在治疗各种以 podocytopenia 为特征的进行性肾小球疾病中具有作用。
