METTL3-mediated m6A modification of SIRT1 mRNA affects the progression of diabetic cataracts through cellular autophagy and senescence.

BACKGROUND

The increasing incidence of diabetes mellitus has established diabetic cataracts (DC) as a significant worldwide public health issue. The mechanisms underlying DC remain unknown, and effective prevention and treatment strategies are lacking. Accordingly, we aimed to explore the role and mechanism behind N6-methyladenosine (m6A) in DC progression.

METHODS

Methyltransferase-like 3 (METTL3), p21, Beclin1, LC3, and p62 expression levels were measured in human tissues. This study assessed total m6A levels and common m6A-regulated biomarkers in both in vitro and in vivo DC models. Autophagy flux was detected in vitro through Ad-mCherry-GFP-LC3B and Monodansylcadaverine (MDC) staining. Cellular senescence was assessed utilizing the senescence-associated β-galactosidase (SA-β-Gal) assay. Furthermore, the effect of METTL3 on SIRT1 mRNA modification was demonstrated, and its mechanism was elucidated using RT-qPCR, western blot, RNA stability assays, and RIP analysis.

RESULTS

METTL3, p21, and p62 expression levels were elevated in lens epithelial cells (LECs) from DC patients, while Beclin1 and LC3 levels were reduced. Silencing METTL3-mediated m6A modifications restored high-glucose-induced autophagy inhibition and prevented premature senescence in LECs. Notably, SIRT1720 and Metformin significantly enhanced autophagosome generation and delayed cellular senescence. The m6A-reading protein YTHDF2 bound to m6A modifications, and YTHDF2 silencing significantly reduced METTL3-mediated SIRT1 inactivation.

CONCLUSIONS

METTL3 induces senescence in DC by destabilizing SIRT1 mRNA in an m6A-YTHDF2-dependent manner. The METTL3-YTHDF2-SIRT1 axis is a key target and potential pathogenic mechanism in DC.