miR-130a-3p inhibition protects against renal fibrosis in vitro via the TGF-β1/Smad pathway by targeting SnoN

Background: Renal fibrosis, a common pathological outcome of chronic kidney disease (CKD), is characterized by extracellular matrix (ECM) accumulation, damage to the tubular epithelium, and the proliferation and activation of fibroblasts. SnoN, a TGF-beta 1/Smad transcriptional co-suppressor, is downregulated in obstructive nephropathy. However, the relationship between miR-130a-3p and SnoN expression in the regulation of renal fibrosis is still unknown. Methods: We used human renal proximal tubular epithelial cells (HRPTEpiCs, HK-2 and primary HRPTEpiCs) treated with TGF-beta 1 to establish an in vitro renal fibrosis model. The expression of miR-130a-3p, SnoN and other proteins related to epithelial mesenchymal transition (EMT) and TGF-beta 1/Smad signalling was investigated by western blotting or qRT-PCR. A luciferase reporter assay was conducted to confirm the interaction of SnoN mRNA and miR-130a-3p. The translocation of p-Smad 2/3 and Smad 7 was determined using immunofluorescence staining. Results: After TGF-beta 1 treatment, miR-130a-3p was highly expressed in renal tubular epithelial cells, while SnoN was poorly expressed. The cell morphology changed to fibroblast-like, indicating evidence of EMT. The levels of EMT and fibrosis-related proteins were decreased through miR-130a-3p inhibition. Additionally, miR-130a-3p acted upon the 3'-UTR of SnoN directly to suppress SnoN expression. Furthermore, miR-130a-3p/SnoN promoted the activation of TGF-beta 1/Smad signalling, as revealed by p-Smad 2/3 and Smad 7 expression levels and distribution patterns. Conclusion: Our study verified that miR-130a-3p facilitates the TGF-beta 1/Smad pathway in renal tubular epithelial cells and may participate in renal fibrosis by targeting SnoN, which could be a possible strategy for renal fibrosis treatment.