miR-122 promotes diabetic retinopathy through targeting TIMP3

Diabetic retinopathy (DR) is a primary complication of diabetes mellitus. DR can cause severe vision loss for patients. miR-122 is elevated in DR patients, while its role in DR is unclear. Hence, the purpose of this study was to analyze the effect of miR-122 on the function of high glucose-induced REC cells and the underlying molecular mechanisms. In this study, our results revealed that miR-122 was up-regulated in high glucose-induced human retinal pigment epithelial cells (ARPE-19). High glucose decreased the cell viability of ARPE-19 cells, which was then restored by miR-122 knockdown. In addition, miR-122 knockdown suppressed apoptosis of high glucose-induced ARPE-19 cells. High glucose also inhibited B-cell lymphoma-2 (Bcl-2) level and increased cleaved caspase-3 level in ARPE-19 cells, which were reversed by miR-122 knockdown. Tissue inhibitor of metalloproteinases-3 (TIMP3) was a direct target of miR-122. TIMP3 was decreased in high glucose-induced ARPE-19 cells, and the decrease was abrogated by miR-122 knockdown. In addition, the effects of miR-122 overexpression in cell viability and apoptosis of high glucose-induced ARPE-19 were abolished by overexpression of TIMP3. In conclusion, the effect and mechanism of miR-122 on high glucose-induced ARPE-19 cells were demonstrated for the first time. miR-122 promoted diabetic retinopathy through targeting TIMP3, making miR-122 a promising target for diabetic retinopathy therapy.