Circular RNA COL1A2 promotes angiogenesis via regulating miR-29b/VEGF axis in diabetic retinopathy

Aims: The dysregulation of circular RNAs (circRNAs) has been implicated in the progression of diabetic retinopathy (DR). This study aims to explore the role and underlying mechanism of hsa_circ_0081108 (circCOL1A2) in DR. Materials and methods: circCOL1A2, vascular endothelial growth factor (VEGF) and miR-29b expression levels in human retinal microvascular endothelial cells (hRMECs) were detected by quantitative reverse transcription polymerase chain reaction (RT-qPCR) and Western blotting. The biological functions of hRMECs were evaluated by MTT, transwell, tube formation, and vascular permeability assays, respectively. The interaction between miR-29b and circCOL1A2/VEGF was determined by dual luciferase assay. The release of VEGF was examined by ELISA. The in vivo role of circCOL1A2 was further verified in streptozotocin (STZ)-induced DR in mice. The pathological changes and VEGF expression in retinal tissues were detected by hematoxylin and eosin (HE) and immunohistochemical staining. Key findings: High glucose (HG) challenge led to increased circCOL1A2, VEGF, MMP-2, MMP-9 levels, but decreased miR-29b level in hRMECs. In addition, circCOL1A2 sponged miR-29b to promote VEGF expression. Silencing of circCOL1A2 inhibited HG-induced proliferation, migration, angiogenesis and vascular permeability of hRMECs via enhancing miR-29b expression. Moreover, circCOL1A2/miR-29b axis participated in HG-induced increase in angiogenesis-related protein expression. Finally, circCOL1A2 knockdown suppressed angiogenesis via regulating miR-29b/VEGF axis in DR mice. Significance: circCOL1A2 facilities angiogenesis during the pathological progression of DR via regulating miR29b/VEGF axis, suggesting that targeting circCOL1A2 may be a potential treatment for DR.