Lysine acetyltransferase 5 contributes to diabetic retinopathy by modulating autophagy through epigenetically regulating autophagy-related gene 7.

Abstract

Objective: Diabetic retinopathy (DR) is a prevalent and serious complication among individuals with diabetes, significantly compromising their visual acuity and overall quality of life. Lysine acetyltransferase 5 (KAT5), an essential catalytic subunit of the nucleosome acetyltransferase of the H4 complex, is implicated in the development of various diseases, including neurological disorders, breast cancer, and lung cancer. However, the function of KAT5 in DR remains poorly understood. This study aims to investigate the influence of KAT5 on autophagy (Atg) during DR.

Material and methods: Experiments were conducted using streptozotocin (STZ)-treated rats to induce diabetes and observe changes in KAT5 expression and its effect on Atg. Retinal tissues and RF/6A cells were utilized to analyze the expression levels of various proteins and their involvement in Atg and apoptosis. KAT5 depletion and Atg7 knockdown were performed to further understand their roles in the process.

Results: The eyeballs of STZ-treated rats showed increased expression of KAT5. Depletion of KAT5 attenuated STZ-induced DR injury in rats. The retinal tissues of STZ-treated rats exhibited reduced expression of B-cell lymphoma-2 (Bcl-2) and increased levels of BCL-2-associated X protein and cleaved caspase 3, which could be reversed by KAT5 depletion. STZ treatment induced expression of Beclin-1 and microtubule-associated protein 1 light chain 3B in retinal tissues, and KAT5 knockdown blocked this effect. In monkey retinal choroidal endothelial ( RF/6A) cells, high glucose (HG) treatment decreased 5-ethynyl-2'-deoxyuridine-positivecells and increased terminal deoxynucleotidyl transferase dUTP nick-end labeling-positive cells, which were reversed by KAT5 depletion. KAT5 depletion also attenuated HG-induced apoptosis and Atg in RF/6A cells. Mechanistically, KAT5 depletion reduced histone H3 lysine 27 acetylation and ribonucleic acid ( RNA) polymerase II enrichment on the Atg7 promoter, leading to a decrease in the messenger RNA ( mRNA) and protein expression of Atg7. Atg7 knockdown suppressed Atg in RF/6A cells under HG conditions and reversed the effect of KAT5 depletion on cell apoptosis and Atg.

Conclusion: The findings suggest that KAT5 contributes to DR by modulating Atg through epigenetic regulation of Atg7. KAT5 emerges as a valuable target for DR treatment, providing a fresh perspective on the disease's pathogenesis and laying the foundation for the development of potential therapeutic strategies.