USP13 modulates the stability of the APC/C adaptor CDH1.

BACKGROUND: The cell division cycle is a process that is exquisitely controlled by a complex interplay between E3 ubiquitin ligases and deubiquitinating enzymes (DUBs). We have previously reported that the DUB USP13 regulates Aurora B levels along the cell cycle. That observation prompted us to explore any possible connection between USP13 and the APC/CCDH1, the major E3 controlling Aurora B levels in cells. METHODS: We performed immunoprecipitation assays followed by western-blotting to assess the interaction between USP13 and CDH1. The cellular effects of USP13 gain or loss of function were analyzed by transfection of FLAG-tagged USP13 plasmid or small interfering RNAs and short hairpin RNAs directed against USP13. The levels of CDH1 and other proteins were quantified in cell extracts by western-blotting. RESULTS: We found that USP13 binds to the APC/C adaptor CDH1. In addition, we report for the first time that USP13 controls CDH1 protein levels in cells: overexpression of USP13 increased CDH1 levels, whereas depletion of USP13 decreased CDH1 levels. CONCLUSIONS: We unveil the existing interplay between USP13 and CDH1: USP13 is capable of stabilizing CDH1 levels. We previously reported that USP13 stabilizes Aurora B in cells, a known substrate of the APC/CCDH1 E3 ubiquitin ligase, before their entry into mitosis. Altogether, our data identify and establish the USP13-CDH1-Aurora B axis as a new regulatory module required for flawless cell cycle progression in mammalian cells, whose misfunction may be involved in the rewiring of cell cycle pathways linked to cancer development.