Linking DNA replication checkpoint to MBF cell-cycle transcription reveals a distinct class of G1/S genes

Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, USA.
The EMBO Journal (Impact Factor: 10.75). 02/2012; 31(7):1798-810. DOI: 10.1038/emboj.2012.27
Source: PubMed

ABSTRACT Reprogramming gene expression is crucial for DNA replication stress response. We used quantitative proteomics to establish how the transcriptional response results in changes in protein levels. We found that expression of G1/S cell-cycle targets are strongly up-regulated upon replication stress, and show that MBF, but not SBF genes, are up-regulated via Rad53-dependent inactivation of the MBF co-repressor Nrm1. A subset of G1/S genes was found to undergo an SBF-to-MBF switch at the G1/S transition, enabling replication stress-induced transcription of genes targeted by SBF during G1. This subset of G1/S genes is characterized by an overlapping Swi4/Mbp1-binding site and is enriched for genes that cause a cell cycle and/or growth defect when overexpressed. Analysis of the prototypical switch gene TOS4 (Target Of SBF 4) reveals its role as a checkpoint effector supporting the importance of this distinct class of G1/S genes for the DNA replication checkpoint response. Our results reveal that replication stress induces expression of G1/S genes via the Rad53-MBF pathway and that an SBF-to-MBF switch characterizes a new class of genes that can be induced by replication stress.

Download full-text


Available from: Robertus A M de Bruin, Aug 22, 2015
  • Source
    • "Because ribonucleotide reductase (Cdc22) is the target of HU and its expression is directly regulated by MBF (Lowndes et al., 1992), hyperactivation of the complex might help to overcome the block to DNA replication inflicted by the drug. Similar processes have been described in the distantly related budding yeast (de Bruin et al., 2008; Bastos de Oliveira et al., 2012; Travesa FIGURE 5: Cdc10 Ser-720 and Ser-732 are phosphorylated by Chk1, inactivating MBFdependent transcription. (A) Chk1 signals MBF through the C-terminal region of Cdc10. "
    [Show abstract] [Hide abstract]
    ABSTRACT: In fission yeast cells, Cds1 is the effector kinase of the DNA replication checkpoint. We have previously shown that when the DNA replication checkpoint is activated, the repressor Yox1 is phosphorylated and inactivated by Cds1 resulting in the activation of the MBF-dependent transcription. This is essential to reinitiate DNA synthesis and for a correct G1-to-S transition. Here we show that Cdc10, which is an essential part of the MBF core, is the target of the DNA damage checkpoint. When fission yeast cells are treated with DNA damaging agents, Chk1 is activated and phosphorylates Cdc10 at its carboxy-terminal domain. This modification is responsible for the repression of MBF-dependent transcription through induced release of MBF from chromatin. This inactivation of MBF is important for survival of cells challenged with DNA damaging agents. Thus, Yox1 and Cdc10 couple normal cell cycle regulation in unperturbed conditions and the DNA replication and DNA damage checkpoints on a single transcriptional complex.
    Molecular biology of the cell 09/2013; 24(21). DOI:10.1091/mbc.E13-05-0257 · 5.98 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To explore cell cycle regulation in the dimorphic fungus Candida albicans, we identified and characterized CaNrm1, a C. albicans homolog of the S. cerevisiae Whi5 and Nrm1 transcription inhibitors that, analogous to mammalian Rb, regulate the cell cycle transcription program during the G1 phase. CaNRM1 is able to complement the phenotypes of both whi5 and nrm1 mutants in S. cerevisiae. In C. albicans, global transcription analysis of the CaNRM1 deletion mutant reveals a preferential induction of G1 and G1/S-specific genes. CaNrm1 interacts genetically with the C. albicans MBF functional homolog, and physically with its subunit CaSwi4. Similar to S. cerevisiae Whi5, CaNrm1 subcellular localization oscillates with the cell cycle between the nucleus and the cytoplasm. Deletion of CaNRM1 further results in increased resistance to hydroxyurea, an inhibitor of DNA replication; analysis of the expression of ribonucleotide reductase, the target of hydroxyurea, suggests that its transcriptional induction in res
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: MBF and SBF transcription factors regulate a large family of coordinately expressed G1/S genes required for early cell-cycle functions including DNA replication and repair. SBF is inactivated upon S-phase entry by Clb/CDK whereas MBF targets are repressed by the co-repressor, Nrm1. Using genome-wide expression analysis of cells treated with methyl methane sulfonate (MMS), hydroxyurea (HU) or camptothecin (CPT), we show that genotoxic stress during S phase specifically induces MBF-regulated genes. This occurs via direct phosphorylation of Nrm1 by Rad53, the effector checkpoint kinase, which prevents its binding to MBF target promoters. We conclude that MBF-regulated genes are distinguished from SBF-regulated genes by their sensitivity to activation by the S-phase checkpoint, thereby, providing an effective mechanism for enhancing DNA replication and repair and promoting genome stability.
    The EMBO Journal 02/2012; 31(7):1811-22. DOI:10.1038/emboj.2012.28 · 10.75 Impact Factor
Show more