SIRT3 regulates mitophagy in liver fibrosis through deacetylation of PINK1/NIPSNAP1

Abstract

Damaged mitochondria, a key factor in liver fibrosis, can be removed by the mitophagy pathway to maintain homeostasis of the intracellular environment to alleviate the development of fibrosis. PINK1 (PTEN‐induced kinase 1) and NIPSNAP1 (nonneuronal SNAP25‐like protein 1), which cooperatively regulate mitophagy, have been predicted to include the sites of lysine acetylation related to SIRT3 (mitochondrial deacetylase sirtuin 3). Our study aimed to discuss whether SIRT3 deacetylates PINK1 and NIPSNAP1 to regulate mitophagy in liver fibrosis. Carbon tetrachloride (CCl4)‐induced liver fibrosis as an in vivo model and LX‐2 cells as activated cells were used to simulate liver fibrosis. SIRT3 expression was significantly decreased in mice in response to CCl4, and SIRT3 knockout in vivo significantly deepened the severity of liver fibrosis, as indicated by increased α‐SMA and Col1a1 levels both in vivo and in vitro. SIRT3 overexpression decreased α‐SMA and Col1a1 levels. Furthermore, SIRT3 significantly regulated mitophagy in liver fibrosis, as demonstrated by LC3‐Ⅱ/Ⅰ and p62 expression and colocalization between TOM20 and LAMP1. Importantly, PINK1 and NIPSNAP1 expression was also decreased in liver fibrosis, and PINK1 and NIPSNAP1 overexpression significantly improved mitophagy and attenuated ECM production. Furthermore, after simultaneously interfering with PINK1 or NIPSNAP1 and overexpressing SIRT3, the effect of SIRT3 on improving mitophagy and alleviating liver fibrosis was disrupted. Mechanistically, we show that SIRT3, as a mitochondrial deacetylase, specifically regulates the acetylation of PINK1 and NIPSNAP1 to mediate the mitophagy pathway in liver fibrosis. SIRT3‐mediated PINK1 and NIPSNAP1 deacetylation is a novel molecular mechanism in liver fibrosis.

Kynurenine in IDO1high cancer cell-derived extracellular vesicles promotes angiogenesis by inducing endothelial mitophagy in ovarian cancer

“…Ultimately, we uncovered that sirt3 expression of the endothelial cells could be upregulated by EVs released from IDO1 high ovarian cancer cells, which is known to play essential roles in regulating mitophagy [ 60 , 73 , 74 ]. Prior studies have shown that acetylation favors protein stabilization [ 75 ].…”

Sirtuin 4 (Sirt4) downregulation contributes to chondrocyte senescence and osteoarthritis via mediating mitochondrial dysfunction

“…Consequently, SIRT4 may also function as a deacetylase in our model. Additionally, Li et al indicated that SIRT3 regulates mitophagy in liver fibrosis through deacetylation of PINK1/NIPSNAP1 74 . In our research, Sirt4 may regulate Pink1 by deacetylating it, thus contributing to the regulation of mitophagy and mitochondrial dysfunction.…”

Liver Cell Mitophagy in Metabolic Dysfunction-Associated Steatotic Liver Disease and Liver Fibrosis

“…Liver inflammation leads to the activation of HSCs, the major source of the fibrous scars in liver fibrosis [ 78 , 101 ]. Damaged mitophagy was demonstrated to be involved in carbon tetrachloride (CCl 4 )- or common bile duct ligation (CBDL)-induced liver fibrosis in rodents [ 102 , 103 , 104 , 105 ]. FK506 binding protein 51 (FKBP51) is a glucocorticoid receptor binding protein that is crucial for modulating metabolic function ( Figure 3 ).…”

“…In PM2.5-induced liver fibrosis, PM2.5 activated ROS-mediated mitophagy and miR-411/Drp1-mediated mitophagy in HSCs [ 111 , 112 ]. In CCl 4 -induced murine liver fibrosis, decreased deacetylase SIRT3 levels are observed, while Sirt3 knockout further exacerbates liver fibrosis [ 105 ]. Mitochondrial SIRT3 specifically deacetylates PINK1 and nonneuronal SNAP25-like protein 1 (NIPSNAP1) to improve impaired mitophagy and attenuate HSC activation and ECM production [ 105 ].…”