lncRNA TUG1 regulates hyperuricemia-induced renal fibrosis in a rat model: TUG1/miR-140-3p/CtsD axis in renal fibrosis

Renal fibrosis is most common among chronic kidney diseases. Molecular studies have shown that long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) participate in renal fibrosis, while the roles of lncRNA taurine upregulated gene 1 (TUG1) and miR-140-3p in hyperuricemia-induced renal fibrosis remain less investigated. In this study, a rat hyperuricemia model is constructed by oral administration of adenine. TUG1, miR-140-3p, and cathepsin D (CtsD) expression levels in rat models are measured. After altering TUG1, miR-140-3p, or CtsD expression in modelled rats, biochemical indices, including uric acid (UA), serum creatine (SCr), blood urea nitrogen (BUN), and 24-h urine protein are detected, pathological changes in the renal tissues, and renal fibrosis are examined. In renal tissues from hyperuricemic rats, TUG1 and CtsD are upregulated, while miR-140-3p is downregulated. Inhibiting TUG1 or CtsD or upregulating miR-140-3p relieves renal fibrosis in hyperuricemic rats. Downregulated miR-140-3p reverses the therapeutic effect of TUG1 reduction, while overexpression of CtsD abolishes the role of miR-140-3p upregulation in renal fibrosis. Collectively, this study highlights that TUG1 inhibition upregulates miR-140-3p to ameliorate renal fibrosis in hyperuricemic rats by inhibiting CtsD.