Circ_001209 aggravates diabetic retinal vascular dysfunction through regulating miR-15b-5p/COL12A1

Diabetic retinopathy, a common complication of diabetes mellitus and a major cause of blindness. circRNAs spongs target miRNA and thus influencing mRNA expression in DR. We investigated the mechanism of circ_001209 in regulating diabetic retinal vascular dysfunction. QRT-PCR analysis was performed to detect the expression of miR-15b-5p, COL12A1 and circ_001209 in human retinal vascular endothelial cells (HRVECs) under high glucose conditions. Western blot assay, wound healing assay, transwell assay and tube formation were used to explore the roles of circ_001209/miR-15b-5p/COL12A1 in retinal vascular dysfunction. Bioinformatics analysis and luciferase reporter, RNA-FISH, and overexpression assays were performed to reveal the mechanisms of the circ_001209/miR-15b-5p/COL12A1 interaction. TUNEL staining and H&E staining were used to evaluate the pathological changes in streptozotocin (STZ)-induced DR in rats. Downregulation of miR-15b-5p under HG conditions promoted proliferation, migration, and tube formation of HRVECs. QRT-PCR and western blot results revealed that miR-15b-5p affected the HRVECs function through targeting COL12A1. Under HG conditions, circ_001209, which acts as a sponge of miR-15b-5p, is upregulated. Besides, overexpression of circ_001209 can affect HRVEC function and aggravate retinal injury in diabetic rats. Upregulation of circ_001209 contributes to vascular dysfunction in diabetic retinas through regulating miR-15b-5p and COL12A1, providing a potential treatment strategy for diabetic retinopathy.