Prolonged disturbance of proteostasis induces cellular senescence via temporal mitochondrial dysfunction and subsequent mitochondrial accumulation in human fibroblasts. (2nd November 2021)

• Record Type: Journal Article
• Authors: Takenaka, Yasuhiro; Inoue, Ikuo; Nakano, Takanari; Ikeda, Masaaki; Kakinuma, Yoshihiko
• Is Part Of: FEBS journal. Volume 289:Number 6(2022)
• Page Start: 1650
• Page End: 1667
• Publication Date: 2021-11-02
• Subjects: aggregate -- DNA damage response -- lysosome -- oxidative stress -- proteasome; Biochemistry -- Periodicals; Molecular biology -- Periodicals; Pathology, Molecular -- Periodicals; 572
• DOI: 10.1111/febs.16249
• Languages: English
• ISSNs: 1742-464X

Abstract

Abstract : 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. Abstract : Prolonged disturbance of proteostasis by MG132 or bafilomycin A (BAFA1) causes excess production of mitochondrial superoxide and intracellular reactive oxygen species (ROS), and induced temporal mitochondrial dysfunction, mitochondrial accumulation, and eventually cellular senescence. Co‐treatment with vitamin E or rapamycin partially attenuated cellular senescence in which the levels of ROS, mitochondrial accumulation, and protein aggregates were suppressed, implying the critical involvement of oxidative stress and mitochondrial function in cellular senescence induced by disturbed proteostasis.