miR-154-5p Affects the TGF β 1/Smad3 Pathway on the Fibrosis of Diabetic Kidney Disease via Binding E3 Ubiquitin Ligase Smurf1

Aim: The study is aimed at verifying miR-154-5p and Smurf1 combination in glomerular mesangial cells regulating TGFβ1/SMAD3 pathway-related protein ubiquitination in the model of diabetic rats renal tissues, primary mesangial cells, and cell lines.

Methods: The diabetic SD rat model and high-glucose-cultured primary mesangial cells and cell lines were established. miR-154-5p mimic and inhibitor, Smurf1 siRNA, and TGF β 1/SMAD3 inhibitor (SB431542) were pretreated to make the TGFβ1/SMAD3 pathway and ubiquitin changes. Fluorescence in situ hybridization was used for the miR-154-5p renal localization; molecular biological detection was adopted for cell proliferation, renal function, urine protein, and pathway proteins. After bioinformatics predicted binding sites, luciferase and Co-IP were used to detect miRNA and protein binding.

Results: miR-154-5p was significantly increased and mainly concentrated in the glomerular of renal cortex in well-established diabetic rat renal tissues. Rno-miR-154-5p combined Rno-Smurf1 3' UTR, while Smurf1 combined SMAD3 directly. Meanwhile, miR-154-5p regulates TGFβ1/Smad3-mediated cell proliferation via Smurf1 ubiquitination.

Conclusion: miR-154-5p regulates the TGFβ1/Smads pathway through Smurf1 ubiquitination and promotes the fibrosis process of diabetic kidney disease.