RBM15 promotes m6A methylation and stability of KLF6 mRNA to accelerate pyroptosis of retinal ganglion cells in early-stage diabetic retinopathy.

Neurodegeneration in early-stage diabetes retinopathy (DR) is mainly caused by the loss of retinal ganglion cells (RGCs), and high glucose-treated cell pyroptosis contributes to an important cause. However, the detailed molecular regulatory mechanism has not yet been thoroughly examined. In this study, primary mouse RGCs were stimulated with different concentrations of glucose, and mouse was intraperitoneally injected with streptozotocin (STZ) to construct DR model in vitro and in vivo. We found that compared to normal controls, RNA binding motif protein 15 (RBM15) was significantly upregulated in high glucose-treated RGCs and STZ-induced mice. RBM15 silence restored cell viability and inhibited cell apoptosis and cell death in high glucose-triggered RGCs. In parallel, RBM15 knockdown distinctly improved pathological damage such as thinning of retinal tissue thickness and loss of RGCs in STZ-modeling mice. Interestingly, the production of inflammatory cytokines and the expression of Cleaved caspase-1, NLRP3 and GSDMD-N were significantly reduced by RBM15 silence in vivo and in vitro. Mechanistically, RBM15 bound to kruppel like factor 6 (KLF6) mRNA to promote m6A modification and stabilize KLF6 mRNA, upregulating KLF6 expression in model cells and model mice retinal tissues. KLF6 overexpression increased the production of inflammatory cytokines and the expression of proteins related to pyroptosis, reversing the protective effects of RBM15 silence in high glucose-treated RGCs and diabetic retina. In conclusion, RBM15 is upregulated by high glucose, and stabilizes KLF6 mRNA to activate NLRP3-mediated pyroptosis pathway, exacerbating inflammation and apoptosis of RGCs and accelerating the progression of DR.