Human CENP-I specifies localization of CENP-F, MAD1 and MAD2 to kinetochores and is essential for mitosis

Nat Cell Biol. 2003 Apr;5(4):341-5. doi: 10.1038/ncb953.


The kinetochore, a macromolecular complex located at the centromere of chromosomes, provides essential functions for accurate chromosome segregation. Kinetochores contain checkpoint proteins that monitor attachments between the kinetochore and microtubules to ensure that cells do not exit mitosis in the presence of unaligned chromosomes. Here we report that human CENP-I, a constitutive protein of the kinetochore that shares limited similarity with Mis6 of Schizosaccharomyces pombe, is required for the localization of CENP-F and the checkpoint proteins MAD1 and MAD2 to kinetochores. Depletion of CENP-I from kinetochores causes the cell cycle to delay in G2. Although monopolar chromosomes in CENP-I-depleted cells fail to establish bipolar connections, the cells are unable to arrest in mitosis. These cells are transiently delayed in mitosis in a MAD2-dependent manner, even though their kinetochores are depleted of MAD2. The delay is extended considerably when the number of unattached kinetochores is increased. This suggests that no single unattached kinetochore in CENP-I-depleted cells can arrest mitosis. The collective output from many unattached kinetochores is required to reach a threshold signal of 'wait for anaphase' to sustain a prolonged mitotic arrest.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antineoplastic Agents / pharmacology
  • Calcium-Binding Proteins / genetics
  • Calcium-Binding Proteins / metabolism
  • Carrier Proteins*
  • Cell Cycle Proteins
  • Cell Nucleus / genetics*
  • Cell Nucleus / metabolism
  • Chromosomal Proteins, Non-Histone / genetics
  • Chromosomal Proteins, Non-Histone / metabolism
  • DNA-Binding Proteins / deficiency
  • DNA-Binding Proteins / genetics*
  • Eukaryotic Cells / cytology
  • Eukaryotic Cells / metabolism*
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • Genes, cdc / physiology*
  • HeLa Cells
  • Humans
  • Kinetochores / metabolism*
  • Mad2 Proteins
  • Microfilament Proteins
  • Microtubules / genetics
  • Microtubules / metabolism
  • Mitosis / genetics*
  • Nocodazole / pharmacology
  • Nuclear Proteins
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism
  • Protein Transport / genetics
  • RNA, Small Interfering / genetics
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism
  • Schizosaccharomyces pombe Proteins


  • Antineoplastic Agents
  • CENPI protein, human
  • Calcium-Binding Proteins
  • Carrier Proteins
  • Cell Cycle Proteins
  • Chromosomal Proteins, Non-Histone
  • DNA-Binding Proteins
  • Fungal Proteins
  • MAD1L1 protein, human
  • Mad2 Proteins
  • Microfilament Proteins
  • Nuclear Proteins
  • Phosphoproteins
  • RNA, Small Interfering
  • Repressor Proteins
  • Schizosaccharomyces pombe Proteins
  • centromere protein F
  • mad1 protein, S pombe
  • mad2 protein, S pombe
  • Nocodazole