Atg5-mediated autophagy deficiency in proximal tubules promotes cell cycle G2/M arrest and renal fibrosis
Atg5-mediated autophagy deficiency in proximal tubules promotes cell cycle G2/M arrest and renal fibrosis
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DOI：
10.1080/15548627.2016.1190071
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发表时间：
2016-01-01
期刊：
影响因子：
13.3
通讯作者：
Mao, Haiping
中科院分区：
文献类型：
--
作者：
Li, Huiyan;Peng, Xuan;Mao, Haiping
Macroautophagy/自噬保护免受细胞应激。肾亚致死性损伤触发的肾小管上皮细胞周期阻滞在G（2）/M与间质纤维化相关然而，自噬在肾纤维化中的作用是难以捉摸的。在此，我们假设肾小管上皮细胞中的自噬活性是抑制细胞周期G（2）/M阻滞和随后的纤维化反应的关键。在血管紧张素II（AGT II）刺激的肾上皮细胞和单侧输尿管梗阻（UUO）后的小鼠肾脏中，我们观察到自噬的发生先于COL 1（胶原，I型）的产生增加。雷帕霉素对自噬的药理学增强抑制了COL 1的积累和肾纤维化。相反，通过近端肾小管上皮细胞特异性缺失Atg 5基因消除自噬，降低LC 3-II蛋白水平和SQSTM 1/p62降解，显示与野生型小鼠相比，UUO模型中细胞周期明显停滞在G（2）/M期，COL 1沉积强烈，间质纤维化严重。在体外，AGT II暴露优先在G（1）/S期触发自噬，并在G（2）/M期增加COL 1的表达在肾上皮细胞。用AGT II刺激Atg 5缺陷的原代近端肾小管细胞也导致G（2）/M阻滞和COL 1产生增加。药理学或遗传学抑制自噬增加AGT II介导的G（2）/M阻滞。增强的ATG 5表达，而不是自噬缺陷的ATG 5突变体K130 R，挽救了G（2）/M阻滞，表明ATG 5对细胞周期进程的调节是自噬依赖的。总之，Atg 5介导的近端上皮细胞自噬是一种重要的宿主防御机制，通过阻断G（2）/M阻滞来预防肾纤维化。
Macroautophagy/autophagy protects against cellular stress. Renal sublethal injury-triggered tubular epithelial cell cycle arrest at G(2)/M is associated with interstitial fibrosis. However, the role of autophagy in renal fibrosis is elusive. Here, we hypothesized that autophagy activity in tubular epithelial cells is pivotal for inhibition of cell cycle G(2)/M arrest and subsequent fibrogenic response. In both renal epithelial cells stimulated by angiotensin II (AGT II) and the murine kidney after unilateral ureteral obstruction (UUO), we observed that occurrence of autophagy preceded increased production of COL1 (collagen, type I). Pharmacological enhancement of autophagy by rapamycin suppressed COL1 accumulation and renal fibrosis. In contrast, genetic ablation of autophagy by proximal tubular epithelial cell-specific deletion of Atg5, with reduction of the LC3-II protein level and degradation of SQSTM1/p62, showed marked cell cycle arrest at the G(2)/M phase, robust COL1 deposition, and severe interstitial fibrosis in a UUO model, as compared with wild-type mice. In vitro, AGT II exposure triggered autophagy preferentially in the G(1)/S phase, and increased COL1 expression in the G(2)/M phase in renal epithelial cells. Stimulation of Atg5-deficient primary proximal tubular cells with AGT II also resulted in elevated G(2)/M arrest and COL1 production. Pharmacological or genetic inhibition of autophagy increased AGT II-mediated G(2)/M arrest. Enhanced expression of ATG5, but not the autophagy-deficient ATG5 mutant K130R, rescued the G(2)/M arrest, suggesting the regulation of cell cycle progression by ATG5 is autophagy dependent. In conclusion, Atg5-mediated autophagy in proximal epithelial cells is a critical host-defense mechanism that prevents renal fibrosis by blocking G(2)/M arrest.