COX17 Attenuates Diabetes-Associated Retinal Injury by Improving Mitochondrial Function

Diabetic retinopathy (DR), a common complication of diabetes, is a leading cause of blindness globally. Cytochrome C oxidase copper chaperone (COX17) is important for Cytochrome C oxidase assembly, and COX17 overexpression is reported to improve mitochondrial function in renal tissue. This study aimed to explore whether COX17 alleviated DR by regulating mitochondrial function.

Diabetes was induced in rats by a single intraperitoneal injection of 65 mg/kg streptozotocin (STZ). Overexpression of COX17 was performed by infection of adeno-associated virus into the vitreous body of rats 2 weeks after STZ injection. Human retinal microvascular endothelial cells (HRMECs) were cultured with high-glucose (HG) medium (20 mM d-glucose). Immunofluorescence assay, enzymatic histochemistry assay, CCK-8 assay, DCFH-DA staining, flow cytometry, western blot, and real-time PCR were performed.

COX17 expression was decreased in the retinal tissues of diabetic rats and HG-stimulated HRMECs. COX17 overexpression alleviated retinal neovascularisation and increased retinal thickness in diabetic rats. COX17 overexpression decreased ROS and apoptosis and increased Cytochrome C oxidase activity, mtDNA copy number, ATP content, and mitochondrial membrane potential (MMP) in both the retinal tissues of diabetic rats and HG-induced HRMECs. Overexpression of COX17 effectively reduced cell apoptosis and increased cell viability. Overexpression of COX17 increased mtDNA in HG-induced HRMECs.

Overall, our study suggested that COX17 overexpression exerted protective effects in the retinas of diabetic rats and in HRMECs by stabilising mitochondrial function.