Prolonged disturbance of proteostasis induces cellular senescence via temporal mitochondrial dysfunction and subsequent mitochondrial accumulation in human fibroblasts
Prolonged disturbance of proteostasis induces cellular senescence via temporal mitochondrial dysfunction and subsequent mitochondrial accumulation in human fibroblasts
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DOI：
10.1111/febs.16249
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发表时间：
2021-11-02
期刊：
影响因子：
5.4
通讯作者：
Kakinuma, Yoshihiko
中科院分区：
文献类型：
--
作者：
Takenaka, Yasuhiro;Inoue, Ikuo;Kakinuma, Yoshihiko
蛋白质水解活性随着年龄的增长而下降，导致老年生物体中聚集蛋白的积累。为了研究蛋白质平衡紊乱是如何导致细胞衰老的，我们建立了应激性早衰（SIPS）模型，将正常的人成纤维细胞MRC-5细胞用蛋白酶体抑制剂MG132或液泡型atp酶抑制剂巴菲霉素A1 （BAFA1）处理5天。时间过程研究显示，在药物治疗期间和之后，细胞内活性氧（ROS）和线粒体超氧化物显著增加。线粒体膜电位起初下降，提示药物治疗期间颞叶线粒体功能紊乱，但药物治疗后随着线粒体积累恢复。amp活化的蛋白激酶α在治疗期间明显活化；此后，细胞内ATP水平显著升高。通过与维生素E或雷帕霉素共同处理，MG132或BAFA1对SIPS的诱导作用部分减弱，其中ROS水平、线粒体积累和蛋白质聚集被抑制，这表明氧化应激和线粒体功能在SIPS的进展中起关键作用。雷帕霉素联合治疗还能增强HSP70的表达和AKT的激活，从而恢复蛋白质停滞状态，促进细胞存活。我们的研究提出了一种可能的途径，从蛋白质稳态紊乱到细胞衰老，通过过量的ROS产生以及线粒体的功能和数量变化。
Proteolytic activity declines with age, resulting in the accumulation of aggregated proteins in aged organisms. To investigate how disturbance in proteostasis causes cellular senescence, we developed a stress-induced premature senescence (SIPS) model, in which normal human fibroblast MRC-5 cells were treated with the proteasome inhibitor MG132 or the vacuolar-type ATPase inhibitor bafilomycin A1 (BAFA1) for 5 days. Time-course studies revealed a significant increase in intracellular reactive oxygen species (ROS) and mitochondrial superoxide during and after drug treatment. Mitochondrial membrane potential initially decreased, suggesting temporal mitochondrial dysfunction during drug treatment, but was restored along with mitochondrial accumulation after drug treatment. AMP-activated protein kinase alpha was notably activated during treatment; thereafter, intracellular ATP levels significantly increased. SIPS induction by MG132 or BAFA1 was partially attenuated by co-treatment with vitamin E or rapamycin, in which the levels of ROS, mitochondrial accumulation, and protein aggregates were suppressed, implying the critical involvement of oxidative stress and mitochondrial function in SIPS progression. Rapamycin co-treatment also augmented the expression of HSP70 and activation of AKT, which could recover proteostasis and promote cell survival, respectively. Our study proposes a possible pathway from the disturbed proteostasis to cellular senescence via excess ROS production as well as functional and quantitative changes in mitochondria.