Oxidative stress-induced DNA damage, the senescence-associated secretory phenotype (SASP), and impaired autophagy all are general features of senescent cells. However, the crosstalk among these events and processes is not fully understood. Here, using NIH3T3 cells exposed to hydrogen peroxide stress, we show that stress-induced DNA damage provokes the SASP largely via cytosolic chromatin fragment (CCF) formation, which activates a cascade comprising cGMP-AMP synthase (cGAS), stimulator of interferon genes protein (STING), NF-κB, and SASP, and that autolysosomal function inhibits this cascade. We found that CCFs accumulate in senescent cells with activated cGAS-STING-NF-κB signaling, promoting SASP and cellular senescence. We also present evidence that the persistent accumulation of CCFs in prematurely senescent cells is partially associated with a defect in DNA- degrading activity in autolysosomes and reduced abundance of activated DNase 2a. Intriguingly, we found that metformin- or rapamycin-induced activation of autophagy significantly lessened the size and levels of CCFs and repressed the activation of the cGAS-STING-NF-κB-SASP cascade and cellular senescence. These effects of autophagy activators indicated that autolysosomal function contributes to CCFs clearance and SASP suppression, further supported by the fact that the lysosome inhibitor bafilomycin A1 blocked the role of autophagy-mediated CCFs clearance and senescence repression. Taken together, these findings confirm the significant role of CCFs formation in the SASP and oxidative stress-induced senescence and reveal that CCF-mediated SASP inversely correlated with autolysosomal function. We conclude that the restoration of autolysosomal function may prevent DNA damage-provoked SASP production and cellular senescence.

中文翻译：

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溶酶体降解胞质染色质片段拮抗氧化应激诱导的衰老。

氧化应激诱导的DNA损伤，衰老相关的分泌表型（SASP）和自噬受损都是衰老细胞的普遍特征。但是，这些事件和过程之间的串扰尚不完全清楚。在这里，使用暴露于过氧化氢胁迫的NIH3T3细胞，我们显示了应激诱导的DNA损伤主要通过胞质染色质片段（CCF）的形成激发了SASP，CCF形成了一个级联，其中包括干扰素基因蛋白的刺激物cGMP-AMP合酶（cGAS）。 （STING），NF-κB和SASP，而这种溶酶体功能会抑制这种级联反应。我们发现，CCFs在活化的cGAS-STING-NF-κB信号传导的衰老细胞中蓄积，从而促进SASP和细胞衰老。我们还提供证据表明，CCFs在早衰细胞中的持续积累与自溶酶体中DNA降解活性的缺陷和活化的DNase 2a的丰度降低部分相关。有趣的是，我们发现二甲双胍或雷帕霉素诱导的自噬激活显着降低了CCF的大小和水平，并抑制了cGAS-STING-NF-κB-SASP级联和细胞衰老的激活。自噬激活剂的这些作用表明，自溶酶体功能有助于CCFs清除和SASP抑制，溶酶体抑制剂bafilomycin A1阻断了自噬介导的CCFs清除和衰老抑制的作用进一步证明了这一点。在一起 这些发现证实了CCFs在SASP和氧化应激诱导的衰老中的重要作用，并揭示了CCF介导的SASP与自身溶酶体功能成反比。我们得出的结论是，常溶酶体功能的恢复可能会阻止DNA损伤引起的SASP产生和细胞衰老。