title: Anaphase-promoting complex/cyclosome controls HEC1 stability.
abstract: OBJECTIVE
  Chromosome segregation during mitosis requires a physically large proteinaceous structure called the kinetochore to generate attachments between chromosomal DNA and spindle microtubules. It is essential for kinetochore components to be carefully regulated to guarantee successful cell division. Depletion, mutation or dysregulation of kinetochore proteins results in mitotic arrest and/or cell death. HEC1 (high expression in cancer) has been reported to be a kinetochore protein, depletion of which, by RNA interference, results in catastrophic mitotic exit.
  
  
  RESULTS
  To investigate how HEC1 protein is controlled post-translation, we analysed the role of anaphase-promoting complex/cyclosome (APC/C)-Cdh1 in degradation of HEC1 protein. In this study, we show that HEC1 is an unstable protein and can be targeted by endogenous ubiquitin-proteasome system in HEK293T cells. Results of RNA interference and in vivo ubiquitination assay indicated that HEC1 could be ubiquitinated and degraded by APC/C-hCdh1 E3 ligase. The evolutionally conserved D-box at the C-terminus functioned as the degron of HEC1, destruction of which resulted in resistance to degradation mediated by APC/C-Cdh1. Overexpression of non-degradable HEC1 (D-box destroyed) induced accumulation of cyclin B protein in vivo and triggered mitotic arrest.
  
  
  CONCLUSIONS
  APC/C-Cdh1 controls stability of HEC1, ensuring normal cell cycle progression.
authors.affiliation: Laboratory of Cell Senescence, Shantou University Medical College, Shantou, Guangdong, China.
authors.forename: L
authors.initials: L
authors.lastname: Li
authors.forename: Y
authors.initials: Y
authors.lastname: Zhou
authors.forename: G-F
authors.initials: GF
authors.lastname: Wang
authors.forename: S-C
authors.initials: SC
authors.lastname: Liao
authors.forename: Y-B
authors.initials: YB
authors.lastname: Ke
authors.forename: W
authors.initials: W
authors.lastname: Wu
authors.forename: X-H
authors.initials: XH
authors.lastname: Li
authors.forename: R-L
authors.initials: RL
authors.lastname: Zhang
authors.forename: Y-C
authors.initials: YC
authors.lastname: Fu
mesh_terms: D064173:Anaphase-Promoting Complex-Cyclosome; D015703:Antigens, CD; D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism*; D003598:Cytoskeletal Proteins; D006801:Humans; D018386:Kinetochores / Q000378:metabolism; D008938:Mitosis; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000235:genetics; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D013379:Substrate Specificity; D014162:Transfection; D025801:Ubiquitin / Q000235:genetics / Q000378:metabolism; D043743:Ubiquitin-Protein Ligase Complexes / Q000235:genetics / Q000502:physiology*
chemical_list: D015703:Antigens, CD; C513384:CDH1 protein, human; D015820:Cadherins; D003598:Cytoskeletal Proteins; C120529:NDC80 protein, human; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D025801:Ubiquitin; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D046988:Proteasome Endopeptidase Complex