Deubiquitinase USP10 Stabilizes Smurf1 and Inhibits TGF-?/BMP Signaling

Objective To explore the regulated function and mechanisms of deubiquitinating enzyme USP10 regulation under physiological conditions. Methods GEO2R and Metascape analyze the differential gene expression and pathway enrichment in microarray (GSE198574) of Usp10+/+ and Usp10-/-neonatal kidney tissues. Western blot and immunohistochemistry are used to measure the expression levels of candidate transcription factors. Co-immunoprecipitation (Co-IP) and GST-pull down assays analyze the interaction between USP10 and the candidate molecules, and deubiquitination experiments verify the regulatory mechanisms of USP10 on target molecules. The expression of cell proliferation marker p21 and apoptosis marker Cleaved-caspase 3 are detected by Western blot. Meanwhile, CCK-8 and plate clonality assays analyze the regulatory functions of USP10 on cell proliferation. Results The TGF-beta/BMP signaling pathway is activated in kidney tissues of Usp10-/-neonatal mice. Physiological deficiency of Usp10 in mice leads to downregulation of Smad ubiquitin-related factor-1 (Smurf1) protein and upregulation of Smad1/5 without affecting their transcription levels. Mechanistically, USP10 interacts with Smurf1 and removes poly-ubiquitylation of Smurf1 which rely on its deubiquitination activity. USP10-deficient promotes the expression of cell cycle inhibitors p21, which is one of the transcriptional target gene of Smad1/5 and inhibits cell proliferation. Conclusion USP10 inhibits TGF-beta/BMP signaling pathway by deubiquitinating and stabilizing Smurf1, thus maintains cell proliferation homeostasis.