2024, Vol. 28 ›› Issue (26): 4221-4225

Role of METTL3 in homocysteine-induced autophagy in mouse islet beta cells

Ma Lingju1, 2, Wang Lexin2, Chi Hongyang2, 3, Zhang Jingwen2, Peng Hongjian2, 4, Gao Chunlan2, 5, Jiang Yideng2, Huang Hui1, Yang Li1, Ma Shengchao2, 3   

Abstract: BACKGROUND: Hyperhomocysteinemia is closely related to the function of islet β cells, but its specific molecular mechanism is not fully understood.
OBJECTIVE: To investigate the role of N6 methyltransferase-like 3 (METTL3) in homocysteine (Hcy)-induced autophagy of mouse islet β cells.
METHODS: The 3rd and 4th generation mouse islet β cells were taken for the experiment. (1) Cell modeling and grouping: cells in control group were not treated with Hcy, while those in homocysteine group were treated with 100 µmol/L Hcy for 48 hours. (2) The mouse islet β-cells were transfected with the plasmids overexpressing Ad-METTL3 and si-METTL3 according to the instructions of LipofectamineTM 2000. Three different interfering fragments were designed, and the one with the best interfering efficiency was verified and screened by PCR. (3) After transfection, the cells were divided into control group, Hcy group, Ad-NC (negative control)+Hcy group, Ad-METTL3+Hcy group, si-NC (negative control)+Hcy group and si-METTL3+Hcy group. (4) qRT-PCR and western blot were used to detect the expression levels of METTL3 and autophagy-related proteins LC3II/I and p62 in cells. Insulin level was determined by ELISA to evaluate insulin secretion capacity of islet cells. Autophagy-related proteins and insulin level were detected after overexpression and interference with METTL3.
RESULTS AND CONCLUSION: Compared with the control group, the expression level of LC3II/I was increased (P < 0.05), the expression of p62 was significantly reduced (P < 0.05), and the insulin secretion capacity was significantly decreased (P < 0.05) in the Hcy group. Compared with the control group, the protein and mRNA levels of METTL3 were reduced in the Hcy group (P < 0.05). After METTL3 silencing in islet β cells, Hcy further upregulated the expression of LC3II/I (P < 0.05), significantly dowregulated the expression of p62 (P < 0.05), and increased the insulin level (P < 0.05). After overexpression of METTL3, Hcy significantly decreased the LC3II/I expression and increased the p62 expression in islet β cells (P < 0.05).   To conclude, METTL3 is involved in the Hcy-induced autophagy regulation of islet β cells and plays a role in the regulation of insulin secretion.

Key words: methyltransferase-like 3, islet β cell, homocysteine, autophagy, LC3II/I