Methyltransferase METTL3‐mediated maturation of miR‐4654 facilitates high glucose‐induced apoptosis and oxidative stress in lens epithelial cells via decreasing SOD2

Abstract

N6‐methyladenosine (m6A) modification has been reported to have roles in modulating the development of diabetic cataract (DC). Methyltransferase‐like 3 (METTL3) is a critical m6A methyltransferase involving in m6A modification activation. Here, we aimed to explore the action and mechanism of METTL3‐mediated maturation of miR‐4654 in DC progression. Human lens epithelial cells (HLECs) were exposed to high glucose (HG) to imitate DC condition in vitro. Levels of genes and proteins were tested via qRT‐PCR and western blotting assays. The proliferation and apoptosis of HLECs were evaluated by cell counting kit‐8, 5‐ethynyl‐2′‐deoxyuridine (EdU), and flow cytometry assays, respectively. Oxidative stress was analyzed by detecting the contents of reactive oxygen species (ROS), superoxide dismutase (SOD) and malondialdehyde (MDA). The binding of miR‐4654 and SOD2 was confirmed by dual‐luciferase reporter assay. The m6A‐RNA immunoprecipitation (MeRIP) assay detected the m6A modification profile. Thereafter, we found that miR‐4654 expression was elevated in DC samples and HG‐induced HLECs. MiR‐4654 knockdown reversed HG‐mediated apoptosis and oxidative stress in HLECs. Mechanistically, miR‐4654 directly targeted SOD2, silencing of SOD2 abolished the protective effects of miR‐4654 knockdown on HLECs under HG condition. In addition, METTL3 induced miR‐4654 maturation through promoting pri‐miR‐4654 m6A modification, thereby increasing miR‐4654 content in HLECs. METTL3 was highly expressed in DC samples and HG‐induced HLECs, METTL3 deficiency protected HLECs against HG‐mediated apoptotic and oxidative injury via down‐regulating miR‐4654. In all, METTL3 induced miR‐4654 maturation in a m6A‐dependent manner, which was then reduced SOD2 expression, thus promoting apoptosis and oxidative stress in HLECs, suggesting a novel path for DC therapy.

The m6A-ncRNAs axis in diabetes complications: novel mechanism and therapeutic potential

“…This process enhances cell viability and reduces oxidative stress responses, crucial for preventing DR exacerbation ( 8 ). Another aspect of METTL3 roles in DR is demonstrated through the induction of mature miR-4654, which facilitates HG-mediated apoptosis and oxidative stress in lens epithelial cells via decreasing the expression of antioxidant superoxide dismutase 2 (SOD2) ( 71 ). In addition, METTL3 mediates m 6 A modifications enhancing the stability of lncRNA SNHG7, which inhibits the endothelial-mesenchymal transition via downregulating the RNA-binding protein KHSRP and the transcriptional coactivator MKL1, thus mitigating DR progression ( 72 ).…”