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SV40 T antigen interacts with Nbs1 to disrupt DNA replication control
Xiaohua Wu1, Dror Avni, Takuya Chiba
1Dana Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts 02115, USA. xiaohwu@scripps.edu
Genes & Development
|June 4, 2004
Summary
Nijmegen breakage syndrome protein 1 (Nbs1) prevents DNA replication errors. Simian virus 40 large T antigen disrupts Nbs1, causing DNA damage and promoting viral replication.
Area of Science:
- Molecular Biology
- Genetics
- Virology
Background:
- Nijmegen breakage syndrome (NBS) is a genetic disorder linked to radiation hypersensitivity, chromosomal instability, and cancer predisposition.
- The NBS protein 1 (Nbs1) forms a complex with Mre11 and Rad50, crucial for DNA double-strand break repair.
- Simian virus 40 (SV40) large T antigen (T) interacts with Nbs1, influencing cellular DNA replication.
Purpose of the Study:
- To investigate the role of Nbs1 in suppressing DNA rereplication.
- To determine how SV40 T antigen affects Nbs1 function and DNA replication.
- To elucidate the mechanism by which Nbs1 regulates viral DNA replication.
Main Methods:
- Cell culture of NBS-deficient and proficient fibroblasts.
- Analysis of DNA replication initiation and progression.
- Western blotting and immunoprecipitation to study protein interactions.
- SV40 DNA replication assays.
Main Results:
- NBS-deficient cells exhibit aberrant DNA rereplication, which is corrected by wild-type Nbs1.
- Expression of an N-terminal Nbs1 fragment induces DNA rereplication and tetraploidy in NBS-deficient cells.
- SV40 T antigen targets Nbs1, leading to enhanced hyperreplication of viral DNA in NBS-deficient cells.
Conclusions:
- Nbs1 acts as a critical suppressor of cellular and viral DNA rereplication.
- SV40 T antigen interferes with Nbs1 function to promote viral DNA replication.
- Understanding the Nbs1-T interaction provides insights into DNA repair, genome stability, and viral propagation.