The human autoantigen MCP1 is required during early stages of DNA replication

Metaphase chromosome protein 1 (MCP1) is a nuclear autoantigen that is associated with condensed chromosomes throughout mitosis. During interphase, this antigen shows a speckle distribution in the nucleus, excluding the nucleolus. Additionally, MCP1 binds tightly to the scaffold/matrix component of...

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Bibliographic Details
Published in:Chromosome research 2000-01, Vol.8 (8), p.699-711
Main Authors: Bronze-da-Rocha, E, Nóvoa, A, Cunha, C, do Carmo-Fonseca, M, Staines, N A, Sunkel, C E
Format: Article
Language:English
Subjects:
Animals
Antibodies, Monoclonal - administration & dosage
Autoantigens - genetics
Autoantigens - metabolism
Cell cycle
Cell Cycle - drug effects
Cell Line
Cell Nucleus - metabolism
Chromosomes
Cytoplasm - drug effects
Cytoplasm - metabolism
Deoxyribonucleic acid
DNA
DNA Replication - drug effects
DNA Replication - genetics
Gene Expression
Green Fluorescent Proteins
Humans
Interphase - drug effects
Interphase - genetics
Luminescent Proteins - genetics
Macropodidae
Microinjections
Mitosis - drug effects
Mitosis - genetics
Proteins
Recombinant Fusion Proteins - genetics
Recombinant Fusion Proteins - metabolism
S Phase - drug effects
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Summary:Metaphase chromosome protein 1 (MCP1) is a nuclear autoantigen that is associated with condensed chromosomes throughout mitosis. During interphase, this antigen shows a speckle distribution in the nucleus, excluding the nucleolus. Additionally, MCP1 binds tightly to the scaffold/matrix component of nuclei and isolated chromosomes. In order to determine the in-vivo localization of the antigen, we have expressed MCP1 fused to EGFP in tissue culture cells. The results demonstrate that MCP1 is located in the nucleus during interphase and during mitosis associates tightly to condensed chromosomes. Furthermore, microinjection of specific antibody confirms these results. We have used a specific monoclonal antibody (mAb 402) against MCP1 to assess the function of this antigen during cell cycle progression. HeLa and Ptk-2 cells that were microinjected into the nucleus and/or cytoplasm at G1/S and very early S phase were not able to progress and complete DNA replication. However, injection of mAb 402 at mid or late S phase does not prevent completion of DNA replication and subsequent progression into mitosis. Microinjection of mAb 402 in Ptk-2 cells synchronized in mitosis did not interfere with progression of mitosis and cells divided. Our results suggest that MCP1 is required at the G1/S transition and during early S phase.
ISSN:0967-3849
1573-6849
DOI:10.1023/A:1012097704355