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Interaction of FANCD2 and NBS1 in the DNA damage response
Koji Nakanishi1, Toshiyasu Taniguchi, Velvizhi Ranganathan
1Department of Pediatric Oncology, Dana-Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, USA.
Abstract:
Fanconi anaemia (FA) and Nijmegen breakage syndrome (NBS) are autosomal recessive chromosome instability syndromes with distinct clinical phenotypes. Cells from individuals affected with FA are hypersensitive to mitomycin C (MMC), and cells from those with NBS are hypersensitive to ionizing radiation. Here we report that both NBS cell lines and individuals with NBS are hypersensitive to MMC, indicating that there may be functional linkage between FA and NBS. In wild-type cells, MMC activates the colocalization of the FA subtype D2 protein (FANCD2) and NBS1 protein in subnuclear foci. Ionizing radiation activates the ataxia telangiectasia kinase (ATM)-dependent and NBS1-dependent phosphorylation of FANCD2, resulting in an S-phase checkpoint. NBS1 and FANCD2 therefore cooperate in two distinct cellular functions, one involved in the DNA crosslink response and one involved in the S-phase checkpoint response.
Insights
Fanconi anaemia (FA) and Nijmegen breakage syndrome (NBS) are linked. NBS cells are hypersensitive to mitomycin C (MMC), revealing a shared DNA crosslink response pathway involving NBS1 and FANCD2 proteins.
Area of Science:
- Genetics
- Molecular Biology
- Cell Biology
Background:
- Fanconi anaemia (FA) and Nijmegen breakage syndrome (NBS) are distinct autosomal recessive chromosome instability syndromes.
- FA cells exhibit hypersensitivity to mitomycin C (MMC), while NBS cells are sensitive to ionizing radiation.
Purpose of the Study:
- To investigate the potential functional linkage between FA and NBS.
- To elucidate the molecular mechanisms underlying the cellular responses to DNA damage in these syndromes.
Main Methods:
- Testing NBS cell lines and individuals for hypersensitivity to MMC.
- Analyzing the colocalization of FANCD2 and NBS1 proteins in response to MMC.
- Investigating the ATM-dependent phosphorylation of FANCD2 induced by ionizing radiation.
Main Results:
- NBS cell lines and individuals with NBS demonstrated hypersensitivity to MMC.
- MMC treatment induced colocalization of FANCD2 and NBS1 proteins in wild-type cells.
- Ionizing radiation triggered ATM-dependent phosphorylation of FANCD2, mediated by NBS1, activating an S-phase checkpoint.
Conclusions:
- NBS shares a functional linkage with FA, particularly in DNA crosslink repair.
- NBS1 and FANCD2 cooperate in distinct cellular functions: DNA crosslink response and S-phase checkpoint activation.