Mmu-miR-664-5p contributes to high glucose-induced MPC5 podocyte injury via its target RUNX3

As a predominant contributor to end-stage renal disease, diabetic nephropathy (DN) progression is critically influenced by podocyte impairment, which serves as a pivotal determinant in the initiation of proteinuria and subsequent renal functional decline. MicroRNAs (miRNAs) act as key post-transcriptional regulators that modulate target gene expression through mRNA degradation and/or translational repression. Previous studies have demonstrated that the upregulation of human runt-associated transcription factor 3 (RUNX3) suppresses the epithelial-to-mesenchymal transition (EMT) in renal tubular epithelial cells in DN. But, the role of RUNX3 in podocyte-specific EMT and its regulation by miRNAs has not been comprehensively explored. This study aimed to investigate whether the microRNA mmu-miR-664-5p contributes to high glucose (HG)-induced podocyte injury by targeting RUNX3 and to determine if Shenxiao decoction (SXD) exerts its protective effect through this pathway. We found that HG significantly upregulates mmu-miR-664-5p, which directly binds to the 3' UTR of RUNX3 mRNA. Inhibition of mmu-miR-664-5p in HG-induced mouse podocyte clone-5 (MCP5) enhanced cell viability, reduced apoptosis, migration, and invasion, and reversed EMT marker expression. We further discovered that SXD-containing serum (SCS), counteracts HG-induced podocyte EMT by downregulating mmu-miR-664-5p and restoring RUNX3. Conversely, adding exogenous miR-664-5p mimetic to SCS-treated HG media reversed these protective effects. In conclusion, mmu-miR-664-5p promoted the EMT effect of MPC5 podocytes in HG medium by targeting RUNX3, and SXD mitigates this process through its inhibition of miR-664-5p, collectively highlighting the mmu-miR-664-5p/RUNX3 axis as a prospective target for therapeutic intervention in DN.