NEDD4-like ubiquitin ligase 2 (NEDL2) is a HECT type ubiquitin ligase. NEDL2 enhances p73 transcriptional activity and degrades ATR kinase in lamin misexpressed cells. Compared with the important functions of other HECT type ubiquitin ligase, there is less study concerning the function and regulation of NEDL2. Using primary antibody immunoprecipitation and mass spectrometry, we identify a list of potential proteins that are putative NEDL2-interacting proteins. The candidate list contains many of mitotic proteins, especially including several subunits of anaphase-promoting complex/cyclosome (APC/C) and Cdh1, an activator of APC/C. Cdh1 can interact with NEDL2 in vivo and in vitro. Cdh1 recognizes one of the NEDL2 destruction boxes (R(740)GSL(743)) and targets it for degradation in an APC/C-dependent manner during mitotic exit. Overexpression of Cdh1 reduces the protein level of NEDL2, whereas knockdown of Cdh1 increases the protein level of NEDL2 but has no effect on the NEDL2 mRNA level. NEDL2 associates with mitotic spindles, and its protein level reaches a maximum in mitosis. The function of NEDL2 during mitosis is essential because NEDL2 depletion prolongs metaphase, and overexpression of NEDL2 induces chromosomal lagging. Elevated expression of NEDL2 protein and mRNA are both found in colon cancer and cervix cancer. We conclude that NEDL2 is a novel substrate of APC/C-Cdh1 as cells exit mitosis and functions as a regulator of the metaphase to anaphase transition. Its overexpression may contribute to tumorigenesis.
Keywords: APC/C; Cell Cycle; Mitosis; Protein Degradation; Tumor; Ubiquitin Ligase.