MicroRNA (miR)-489-3p contributes to lipopolysaccharide-induced HK-2 cell injury by targeting RIPK4 and inactivating the β-catenin signaling

Acute kidney injury (AKI) involves a sudden loss of renal function and is associated with high mortality. MicroRNA (miR)-489-3p may serve as a critical molecule in AKI according to previous studies. The study aimed to explore the functional roles of miR-489-3p in AKI and underlying mechanisms. An in vitro model of sepsis-induced cell injury was established by treating human proximal tubular epithelial cells (HK-2) with lipopolysaccharide (LPS). Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was performed to examine expression levels of kidney injury molecule-1 (KIM-1), miR-489-3p, and downstream mRNAs. After silencing miR-489-3p, receptor-interacting protein kinase 4 (RIPK4), or β-catenin signaling, HK-2 cell viability was measured using cell counting kit-8 assays. Apoptosis was assessed by TdT-mediated dUTP nick-end labeling (TUNEL) assay and flow cytometry analysis. Western blot analysis was performed to examine protein levels of apoptotic markers, RIPK4, and β-catenin. Luciferase reporter assays were conducted to explore the interaction between miR-489-3p and RIPK4. Immunofluorescence staining was performed to evaluate the distribution of β-catenin in LPS-stimulated HK-2 cells. MiR-489-3p was significantly upregulated in LPS-treated HK-2 cells. Its inhibition attenuated the pro-apoptotic effects induced by LPS, increased cell viability, and reduced KIM-1 level. MiR-489-3p directly targeted 3′ untranslated region of RIPK4 and suppressed its expression. Knockdown of RIPK4 rescued the suppressive effect of miR-489-3p inhibition on cell apoptosis. Moreover, miR-489-3p was found to inactivate the β-catenin signaling by reducing RIPK4 expression. IWR-1 treatment similarly rescued the suppressive effect of miR-489-3p inhibition on cell apoptosis. In conclusion, miR-489-3p promotes LPS-induced HK-2 cell damage by targeting RIPK4 and inactivating β-catenin signaling.