Human CENP-I specifies localization of CENP-F, MAD1 and MAD2 to kinetochores and is essential for mitosis.
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.
Liu
Song-Tao
ST
Fox Chase Cancer Center, 7701 Burholme Avenue, Philadelphia, Pennsylvania 19111, USA.
Hittle
James C
JC
Jablonski
Sandra A
SA
Campbell
Michael S
MS
Yoda
Kinya
K
Yen
Tim J
TJ
D000970:Antineoplastic Agents / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D002467:Cell Nucleus / Q000235:genetics* / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics*; D005057:Eukaryotic Cells / Q000166:cytology / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D018816:Genes, cdc / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D018386:Kinetochores / Q000378:metabolism*; D064246:Mad2 Proteins; D008840:Microfilament Proteins; D008870:Microtubules / Q000235:genetics / Q000378:metabolism; D008938:Mitosis / Q000235:genetics*; D015739:Nocodazole / Q000494:pharmacology; D009687:Nuclear Proteins; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins
D000970:Antineoplastic Agents; C484297:CENPI protein, human; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C501384:MAD1L1 protein, human; D064246:Mad2 Proteins; D008840:Microfilament Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D034741:RNA, Small Interfering; D012097:Repressor Proteins; D029702:Schizosaccharomyces pombe Proteins; C094772:centromere protein F; C501383:mad1 protein, S pombe; C577696:mad2 protein, S pombe; D015739:Nocodazole