Long noncoding RNA MIAT inhibits the progression of diabetic nephropathy and the activation of NF-kappa B pathway in high glucose-treated renal tubular epithelial cells by the miR-182-5p/GPRC5A axis

Background - Diabetic nephropathy (DN) is a common diabetic complication. Long noncoding RNAs (lncRNAs) have been identified as essential regulators in DN progression. This study is devoted to the research of lncRNA-myocardial infarction-associated transcript (MIAT) in DN. Methods - DN cell model was established by high glucose (HG) treatment for human renal tubular epithelial cells (HK-2). Cell viability and colonizing capacity were analyzed by Cell Counting Kit-8 (CCK-8) and colony formation assay. Apoptosis was assessed via caspase-3 detection and flow cytometry. Enzyme-linked immunosorbent assay (ELISA) was used for evaluating inflammation. The protein determination was completed using western blot. MIAT, microRNA-182-5p (miR-182-5p), and G protein-coupled receptor class C group 5 member A (GPRC5A) levels were all examined via reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Intergenic binding was verified using dual-luciferase reporter, RNA immunoprecipitation (RIP), and RNA pull-down assays. Results - HG induced the inhibition of cell growth, but accelerated apoptosis and inflammation as well as the activation of nuclear factor kappa B (NF-kappa B) pathway. MIAT reestablishment prevented the HG-induced cell damages and NF-kappa B signal activation. Mechanistically, MIAT was proved as a miR-182-5p sponge and regulated the expression of GPRC5A that was a miR-182-5p target. The rescued experiments demonstrated that MIAT downregulation or miR-182-5p upregulation aggravated the HG-induced cell damages and activated the NF-kappa B pathway via the respective regulation of miR-182-5p or GPRC5A. Conclusion - Taken together, MIAT functioned as an inhibitory factor in the pathogenesis to impede the development of DN and inactivate the NF-kappa B pathway via regulating the miR-182-5p/GPRC5A axis.