Low expression of microRNA-15b promotes the proliferation of retinal capillary endothelial cells and pericytes by up-regulating VEGFA in diabetic rats.

Abstract

To investigate the role of microRNA-15b in diabetic retinopathy and its underlying mechanism. Diabetes rat model was established by streptozotocin injection. The mRNA expression of microRNA-15b in retinal capillary endothelial cells and pericytes of diabetic rats was detected by quantitative Real Time-Polymerase Chain Reaction (qRT-PCR). The mRNA and protein expressions of vascular endothelial growth factor A (VEGFA) were detected by qRT-PCR and Western blot, respectively. MicroRNA-15b mimics or inhibitor were transfected into retinal capillary endothelial cells and pericytes of diabetic rats, respectively. The mRNA expressions of microRNA-15b and VEGFA were detected by qRT-PCR. Cell counting kit-8 (CCK-8) assay was used to detect the proliferation of capillary endothelial cells and pericytes. Dual-Luciferase reporter gene assay was conducted to verify the binding condition of microRNA-15b and VEGFA. RNA immunoprecipitation (RIP) assay was performed to determine whether microRNA-15b could bind to AGO2. Rescue experiments were finally carried out by detecting the proliferation of retinal capillary endothelial cells and pericytes after downregulation or overexpression of microRNA-15b and VEGFA. The expression of microRNA-15b decreased, whereas VEGFA expression increased in retinal capillary endothelial cells and pericytes of diabetic rats. High expression of microRNA-15b in retinal capillary endothelial cells and pericytes resulted in VEGFA down-regulation and decreased proliferation. RIP assay results indicated that microRNA-15b could interact with AGO2. Additionally, Dual-Luciferase reporter gene assay showed that VEGFA is a direct target gene of microRNA-15b. VEGFA overexpression could reverse the inhibited proliferation of retinal capillary endothelial cells and pericytes induced by microRNA-15b overexpression. Similarly, VEGFA knockdown could reverse the effect of the low expression of microRNA-15b on the proliferation of retinal capillary endothelial cells and pericytes. Low expression of microRNA-15b in retinal capillary endothelial cells and pericytes of diabetic rats promotes the development of diabetic retinopathy by up-regulating VEGFA.