MicroRNA-199a-3p suppresses high glucose-induced apoptosis and inflammation by regulating the IKKβ/NF-κB signaling pathway in renal tubular epithelial cells

Renal tubular epithelial cells (RTEC) injury induced by hyperglycemia is considered a major contributor to the pathogenesis of diabetic nephropathy (DN). However, few studies have focused on the role of microRNAs (miRNAs/miRs) in RTEC injury. Therefore, the present study aimed to investigate the role and mechanisms of miRNAs in RTEC injury. In the study, miRNAs expression profiles were determined via microarray assay in the peripheral blood samples of patients with DN. High glucose (HG)-induced injury in HK-2 cells was used as a cell model to examine the potential role of miR-199a-3p in DN. The expression of miR-199a-3p was validated using reverse transcription-quantitative PCR. The expressions of TNF-α, IL-1β and IL-6, were detected via ELISA. The protein levels of apoptosis-related proteins were determined using western blotting. Cell apoptosis and caspase 3 activity were evaluated via flow cytometry analysis and caspase 3 activity assay, respectively. Luciferase reporter assay was used to confirm the interaction between miR-199a-3p and IKKβ. miR-199a-3p was found to be significantly downregulated in the peripheral blood samples, and there was a negative correlation between miR-199a-3p expression and proteinuria in patients with DN. It was identified that miR-199a-3p expression was time-dependently decreased in the HG-induced cell damage model. Moreover, miR-199a-3p overexpression significantly improved HG-induced cell injury, as evidenced by the decrease in cell apoptosis and inflammation. Subsequent analyses demonstrated that miR-199a-3p directly targeted IKKβ, whose expression was increased, and negatively correlated with miR-199a-3p expression in patients with DN. The protective effects of miR-199a-3p overexpression on HG-treated HK-2 cells were partially reversed by IKKβ overexpression. In addition, activation of the NF-κB pathway by HG was blocked by miR-199a-3p mimics transfection in HK-2 cells. Collectively, the present findings indicated that miR-199a-3p protected HK-2 cells against HG-induced injury via inactivation of the IKKβ/NF-κB pathway, suggesting enhanced expression of miR-199a-3p as a potential therapeutic strategy for patients with DN.