Autophagy is associated with apoptosis in cisplatin injury to renal tubular epithelial cells
Autophagy is associated with apoptosis in cisplatin injury to renal tubular epithelial cells
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DOI：
10.1152/ajprenal.00590.2007
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发表时间：
2008-04-01
影响因子：
4.2
通讯作者：
Kaushal, Gur P.
中科院分区：
文献类型：
--
作者：
Yang, Cheng;Kaushal, Varsha;Kaushal, Gur P.
自噬已成为控制生命和死亡的另一种主要“程序化”机制，就像真核生物细胞凋亡的“程序化细胞死亡”一样。我们检测了顺铂对肾小管上皮细胞（RTEC）损伤过程中自噬蛋白的表达和自噬体的形成。早在顺铂暴露后 2-4 小时就检测到自噬，表现为 LC3-I 的诱导、LC3-I 向 LC3-II 蛋白的转化以及自噬的重要标志物 Beclin 1 和 Atg5 的上调。在 RTEC 中转染 GFP-LC3 后，顺铂诱导的自噬体相关 LC3-II 点状染色的出现为自噬提供了进一步的证据。自噬抑制剂 3-甲基腺嘌呤可阻断自噬体的点状染色。正常细胞用吖啶橙染色，正常细胞的细胞质和核成分显示绿色荧光，但顺铂处理的细胞显示相当多的红色荧光，表明形成了许多酸性自噬溶酶体空泡。自噬抑制剂 LY294002 或 3-甲基腺嘌呤或渥曼青霉素抑制自噬体的形成，但在顺铂处理 2-4 小时后诱导细胞凋亡，如 caspase-3/7 和 -6 激活、核碎裂和细胞死亡所示。自噬抑制剂从自噬到凋亡的转变进一步表明顺铂治疗后的凋亡前滞后期是由自噬介导的。在顺铂损伤的后期，细胞凋亡也被发现与自噬有关，因为自噬抑制剂和自噬蛋白 Beclin 1 和 Atg5 的失活增强了 caspase 的激活和细胞凋亡。我们的结果表明，自噬的诱导会产生适应性反应，抑制顺铂诱导的细胞凋亡，并延长 RTEC 的存活时间。
Autophagy has emerged as another major "programmed" mechanism to control life and death much like "programmed cell death" is for apoptosis in eukaryotes. We examined the expression of autophagic proteins and formation of autophagosomes during progression of cisplatin injury to renal tubular epithelial cells (RTEC). Autophagy was detected as early as 2-4 h after cisplatin exposure as indicated by induction of LC3-I, conversion of LC3-I to LC3-II protein, and upregulation of Beclin 1 and Atg5, essential markers of autophagy. The appearance of cisplatin-induced punctated staining of autophagosome-associated LC3-II upon GFP-LC3 transfection in RTEC provided further evidence for autophagy. The autophagy inhibitor 3-methyladenine blocked punctated staining of autophagosomes. The staining of normal cells with acridine orange displayed green fluorescence with cytoplasmic and nuclear components in normal cells but displayed considerable red fluorescence in cisplatin-treated cells, suggesting formation of numerous acidic autophagolysosomal vacuoles. Autophagy inhibitors LY294002 or 3-methyladenine or wortmannin inhibited the formation of autophagosomes but induced apoptosis after 2-4 h of cisplatin treatment as indicated by caspase-3/7 and -6 activation, nuclear fragmentation, and cell death. This switch from autophagy to apoptosis by autophagic inhibitors further suggests that the preapoptotic lag phase after treatment with cisplatin is mediated by autophagy. At later stages of cisplatin injury, apoptosis was also found to be associated with autophagy, as autophagic inhibitors and inactivation of autophagy proteins Beclin 1 and Atg5 enhanced activation of caspases and apoptosis. Our results demonstrate that induction of autophagy mounts an adaptive response, suppresses cisplatin-induced apoptosis, and prolongs survival of RTEC.