Ring-finger protein 5 attenuates oxygen-glucose deprivation and reperfusion-induced mitochondrial dysfunction and inflammation in cardiomyocytes by inhibiting the S100A8/MYD88/NF-κB axis.

Mitochondrial dysfunction is closely intertwined with the progression of heart failure (HF). Ring-finger protein 5 (RNF5) is an E3 ubiquitin ligase, whose deletion induces the enhanced S100A8 expression. S100A8 regulates the mitochondrial dysfunction and S100A8/myeloid differentiation factor 88 (MYD88)/nuclear factor-kappa B (NF-κB) pathway promotes an inflammatory response; however, whether RNF5 modulated mitochondrial dysregulation and inflammation through the S100A8/MYD88/NF-κB axis remains unknown. Here, H9c2 cells were stimulated with oxygen-glucose deprivation/reperfusion (OGD/R) to build a HF model in vitro. RNF5 level was assessed in gene expression omnibus database and in OGD/R-induced H9c2 cells with reverse transcriptase quantitative polymerase chain reaction and western blot. The RNF5 level was overexpressed via transfecting RNF5 overexpression plasmids into H9c2 cells. The role and mechanism of RNF5 in OGD/R-elicited H9c2 cells were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide, spectrophotometry, flow cytometry, mitochondrial membrane potential (MMP) measurement, enzyme-linked immunosorbent assay and western blot assays. The RNF5 expression was downregulated both in silico and in OGD/R-stimulated H9c2 cells. OGD/R treatment caused a decrease in the cell viability, the MMP level, and the translational expression of mito-cyt-c and NF-κB-cyto, and an elevation in the concentrations of lactate dehydrogenase and creatine kinase myocardial band, the apoptosis rate, the inflammatory factor release, and the relative protein expression of cyto-cyt-c, S100A8, MYD88 and NF-κB-nuc in H9c2 cells. Upregulation of RNF5 reversed these indicators in OGD/R-stimulated H9c2 cells. Altogether, based on these outcomes, we concluded that RNF5 impeded mitochondrial dysfunction and inflammation through attenuating the S100A8/MYD88/NF-κB axis in OGD/R-stimulated H9c2 cells.