miR-504-3p-HNF1B signaling axis aggravates podocyte injury in diabetic kidney disease

Recently, microRNAs (miRNAs) have been found to mediate the development of diabetic kidney disease (DKD) by regulating podocyte injury. The aim of this study was to investigate the influence of miR-504-3p on high glucose (HG)-treated mouse renal podocytes (MPC5) and its potential regulatory mechanisms. First, a DKD cell model was established. Next, RT-qPCR was performed to measure miR-504-3p and HNF1 Homeobox B (HNF1B) expression levels. Additionally, the proliferation and apoptosis of MPC5 cells were assessed using CCK-8 assay and Flow cytometry, respectively. The protein expression levels of cell fibrotic markers, podocyte injury marker, epithelial-mesenchymal transition (EMT) markers and HNF1B were measured by Western Blotting. ROS, MDA, SOD and GSH kits were used to assess oxidative stress levels. Furthermore, the interplay between miR-504-3p and HNF1B was confirmed by luciferase reporter experiments. The miR-504-3p expression was significantly upregulated in GEO database (GSE161884) and in HG-induced MPC5 cells. The results revealed that HG treatment decreased MPC5 cell proliferation, promoted cell apoptosis and fibrosis, and ultimately led to podocyte injury. However, miR-504-3p knockdown could reverse these phenotypes and reduce podocyte injury. Moreover, online database screening combined with dual luciferase reporter assay confirmed HNF1B as a specific target of miR-504-3p. Finally, overexpression of HNF1B mitigated the proliferation inhibition and apoptosis promotion induced by oxidative stress and inhibited EMT-mediated cell fibrosis, thereby counteracting the effects of miR-504-3p on podocyte injury under HG treatment. In summary, our data indicate that miR-504-3p regulates HG-induced podocyte injury by sponging HNF1B, providing a new direction for the treatment of DKD.