A bromodomain protein, MCAP, associates with mitotic chromosomes and affects G(2)-to-M transition.
We describe a novel nuclear factor called mitotic chromosome-associated protein (MCAP), which belongs to the poorly understood BET subgroup of the bromodomain superfamily. Expression of the 200-kDa MCAP was linked to cell division, as it was induced by growth stimulation and repressed by growth inhibition. The most notable feature of MCAP was its association with chromosomes during mitosis, observed at a time when the majority of nuclear regulatory factors were released into the cytoplasm, coinciding with global cessation of transcription. Indicative of its predominant interaction with euchromatin, MCAP localized on mitotic chromosomes with exquisite specificity: (i) MCAP-chromosome association became evident subsequent to the initiation of histone H3 phosphorylation and early chromosomal condensation; and (ii) MCAP was absent from centromeres, the sites of heterochromatin. Supporting a role for MCAP in G(2)/M transition, microinjection of anti-MCAP antibody into HeLa cell nuclei completely inhibited the entry into mitosis, without abrogating the ongoing DNA replication. These results suggest that MCAP plays a role in a process governing chromosomal dynamics during mitosis.
Dey
A
A
Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-2753, USA.
Ellenberg
J
J
Farina
A
A
Coleman
A E
AE
Maruyama
T
T
Sciortino
S
S
Lippincott-Schwartz
J
J
Ozato
K
K
D000595:Amino Acid Sequence; D000818:Animals; D002453:Cell Cycle / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism*; D002503:Centromere / Q000378:metabolism; D002874:Chromosome Mapping; D002875:Chromosomes / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D016195:G2 Phase / Q000235:genetics; D006367:HeLa Cells; D006570:Heterochromatin / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D017404:In Situ Hybridization, Fluorescence; D008214:Lymphocytes / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008938:Mitosis / Q000235:genetics; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism*; D010766:Phosphorylation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014018:Tissue Distribution; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D018797:Cell Cycle Proteins; D018076:DNA, Complementary; D006570:Heterochromatin; D006657:Histones; D009687:Nuclear Proteins; D014157:Transcription Factors; C413003:mitotic chromosome-associated protein, 200-kDa