Acute kidney injury (AKI) is associated with high morbidity and mortality rates. The molecular mechanisms underlying AKI are currently being extensively investigated. WWP2 is an E3 ligase that regulates cell proliferation and differentiation. Whether WWP2 plays a regulatory role in AKI remains to be elucidated. We aimed to investigate the implication of WWP2 in AKI and its underlying mechanism in the present study. We utilized renal tissues from patients with AKI and established AKI models in global or tubule-specific knockout (cKO) mice strains to study WWP2′s implication in AKI. We also systemically analyzed ubiquitylation omics and proteomics to decipher the underlying mechanism. In the present study, we found that WWP2 expression significantly increased in the tubules of kidneys with AKI. Global or tubule-specific knockout of WWP2 significantly aggravated renal dysfunction and tubular injury in AKI kidneys, whereas WWP2 overexpression significantly protected tubular epithelial cells against cisplatin. WWP2 deficiency profoundly affected autophagy in AKI kidneys. Further analysis with ubiquitylation omics, quantitative proteomics and experimental validation suggested that WWP2 mediated poly-ubiquitylation of CDC20, a negative regulator of autophagy. CDC20 was significantly decreased in AKI kidneys, and selective inhibiting CDC20 with apcin profoundly alleviated renal dysfunction and tubular injury in the cisplatin model with or without WWP2 cKO, indicating that CDC20 may serve as a downstream target of WWP2 in AKI. Inhibiting autophagy with 3-methyladenine blocked apcin’s protection against cisplatin-induced renal tubular cell injury. Activating autophagy by rapamycin significantly protected against cisplatin-induced AKI in WWP2 cKO mice, whereas inhibiting autophagy by 3-methyladenine further aggravated apoptosis in cisplatin-exposed WWP2 KO cells. Taken together, our data indicated that the WWP2/CDC20/autophagy may be an essential intrinsic protective mechanism against AKI. Further activating WWP2 or inhibiting CDC20 may be novel therapeutic strategies for AKI.

中文翻译：

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WWP2缺失通过靶向CDC20/自噬轴加重急性肾损伤


急性肾损伤（AKI）与高发病率和死亡率相关。目前正在广泛研究 AKI 的分子机制。 WWP2 是一种调节细胞增殖和分化的 E3 连接酶。 WWP2 是否在 AKI 中发挥调节作用仍有待阐明。本研究旨在探讨WWP2在AKI中的意义及其潜在机制。我们利用 AKI 患者的肾组织，在整体或肾小管特异性敲除 (cKO) 小鼠品系中建立 AKI 模型，以研究 WWP2 在 AKI 中的意义。我们还系统地分析了泛素化组学和蛋白质组学，以破译其潜在机制。在本研究中，我们发现 AKI 肾小管中 WWP2 表达显着增加。 WWP2 的整体或肾小管特异性敲除显着加重 AKI 肾脏的肾功能障碍和肾小管损伤，而 WWP2 过表达可显着保护肾小管上皮细胞免受顺铂的影响。 WWP2 缺乏严重影响 AKI 肾脏的自噬。泛素化组学、定量蛋白质组学和实验验证的进一步分析表明，WWP2 介导 CDC20（自噬的负调节因子）的多泛素化。 AKI 肾脏中 CDC20 显着降低，在有或没有 WWP2 cKO 的顺铂模型中，用 apcin 选择性抑制 CDC20 可显着缓解肾功能障碍和肾小管损伤，表明 CDC20 可能作为 AKI 中 WWP2 的下游靶标。用 3-甲基腺嘌呤抑制自噬会阻断 apcin 对顺铂诱导的肾小管细胞损伤的保护作用。 雷帕霉素激活自噬可显着保护WWP2 cKO小鼠免受顺铂诱导的AKI，而3-甲基腺嘌呤抑制自噬则进一步加剧顺铂暴露的WWP2 KO细胞的细胞凋亡。综上所述，我们的数据表明 WWP2/CDC20/自噬可能是针对 AKI 的重要内在保护机制。进一步激活WWP2或抑制CDC20可能是AKI的新治疗策略。