ALKBH5 SUMOylation-mediated FBXW7 m6A modification regulates epithelial cells senescence during 1-nitropyrene-induced pulmonary fibrosis [Ribo-seq]
Abstract:Our previous study found that 1-nitropyrene (1-NP) exposure evoked pulmonary fibrosis in mice. However, the exact mechanism remained elusive. We found that 1-NP induced telomere damage and cellular senescence in mice lungs and MLE-12 cells. Further research showed that 1-NP downregulated telomere repeat binding factor 2 (TRF2), and upregulated FBXW7. Mechanistically, 1-NP-caused TRF2 ubiquitination and proteasomal degradation depended on E3 ubiquitin ligase activity of FBXW7. Moreover, 1-NP upregulated FBXW7 m6A modification via an ALKBH5-YTHDF1-dependent manner. Further analysis found 1-NP promoted ALKBH5 SUMOylation and subsequent proteasomal degradation. Additionally, 1-NP evoked mitochondrial reactive oxygen species (mtROS) overproduction. Mito-TEMPO, a mitochondrial-targeted antioxidant, mitigated 1-NP-caused mtROS overproduction, ALKBH5 SUMOylation, FBXW7 m6A modification, TRF2 degradation and cellular senescence. Taken together, mtROS-initiated ALKBH5 SUMOylation and subsequent FBXW7 m6A modification is indispensable in TRF2 degradation and cellular senescence in pulmonary epithelial cells during 1-NP-induced pulmonary fibrosis. Our study provides target intervention measures towards 1-NP-evoked pulmonary fibrosis. Overall design: The immortalized mouse lung epithelial (MLE)-12 cells, also known as AEC2 cells were from American Type Culture Collection (USA). MLE-12 cells were incubated using 4 mL of medium comprising 10% fetal bovine serum obtained from Thermo Scientific (MA, USA) in an incubator with 5% CO2. To investigate the influence of 1-nitropyrene (5 µM) on FBXW7 mRNA translation, the MLE-12 cells were cultured with or without 1-nitropyrene for 12h.