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The Caenorhabditis elegans homolog of Gen1/Yen1 resolvases links DNA damage signaling to DNA double-strand break repair.

Bailly AP, Freeman A, Hall J, Déclais AC, Alpi A, Lilley DM, Ahmed S, Gartner A - PLoS Genet. (2010)

Bottom Line: DNA double-strand breaks (DSBs) can be repaired by homologous recombination (HR), which can involve Holliday junction (HJ) intermediates that are ultimately resolved by nucleolytic enzymes.An N-terminal fragment of human GEN1 has recently been shown to act as a Holliday junction resolvase, but little is known about the role of GEN-1 in vivo.Furthermore, GEN-1 acts redundantly with the 9-1-1 complex to ensure genome stability.

View Article: PubMed Central - PubMed

Affiliation: Wellcome Trust Centre for Gene Regulation and Expression, University of Dundee, Dundee, United Kingdom.

ABSTRACT
DNA double-strand breaks (DSBs) can be repaired by homologous recombination (HR), which can involve Holliday junction (HJ) intermediates that are ultimately resolved by nucleolytic enzymes. An N-terminal fragment of human GEN1 has recently been shown to act as a Holliday junction resolvase, but little is known about the role of GEN-1 in vivo. Holliday junction resolution signifies the completion of DNA repair, a step that may be coupled to signaling proteins that regulate cell cycle progression in response to DNA damage. Using forward genetic approaches, we identified a Caenorhabditis elegans dual function DNA double-strand break repair and DNA damage signaling protein orthologous to the human GEN1 Holliday junction resolving enzyme. GEN-1 has biochemical activities related to the human enzyme and facilitates repair of DNA double-strand breaks, but is not essential for DNA double-strand break repair during meiotic recombination. Mutational analysis reveals that the DNA damage-signaling function of GEN-1 is separable from its role in DNA repair. GEN-1 promotes germ cell cycle arrest and apoptosis via a pathway that acts in parallel to the canonical DNA damage response pathway mediated by RPA loading, CHK1 activation, and CEP-1/p53-mediated apoptosis induction. Furthermore, GEN-1 acts redundantly with the 9-1-1 complex to ensure genome stability. Our study suggests that GEN-1 might act as a dual function Holliday junction resolvase that may coordinate DNA damage signaling with a late step in DNA double-strand break repair.

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Related in: MedlinePlus

Sensitivity of gen-1 (tm2940) and gen-1 (yp30) in response to DNA damaging agents.(A) L1 stage worms sensitivity assay to IR, (B) L4 stage worms sensitivity assay to IR. (C) MMS, (D) UV irradiation, (E) nitrogen mustard, and (F) HU exposure of L1 stage worms sensitivity assay. Assays were performed as described in Materials and Methods. Error bars represent s.e.m.
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pgen-1001025-g003: Sensitivity of gen-1 (tm2940) and gen-1 (yp30) in response to DNA damaging agents.(A) L1 stage worms sensitivity assay to IR, (B) L4 stage worms sensitivity assay to IR. (C) MMS, (D) UV irradiation, (E) nitrogen mustard, and (F) HU exposure of L1 stage worms sensitivity assay. Assays were performed as described in Materials and Methods. Error bars represent s.e.m.

Mentions: A Holliday junction-resolving activity is likely to be required for meiotic recombination, and a defect in this activity is predicted to result in embryonic lethality due to random autosome segregation in meiosis [55]. We can exclude such a defect as gen-1(tm2940) worms propagate as wild type, and fail to exhibit embryonic lethality in the absence of genotoxic stress (Figure 3A (0 Gy)). Furthermore, we did not observe an enhanced incidence of XO males, a phenotype that would indicate defects in meiotic chromosome pairing or recombination of the X chromosome (Table 1) [56].


The Caenorhabditis elegans homolog of Gen1/Yen1 resolvases links DNA damage signaling to DNA double-strand break repair.

Bailly AP, Freeman A, Hall J, Déclais AC, Alpi A, Lilley DM, Ahmed S, Gartner A - PLoS Genet. (2010)

Sensitivity of gen-1 (tm2940) and gen-1 (yp30) in response to DNA damaging agents.(A) L1 stage worms sensitivity assay to IR, (B) L4 stage worms sensitivity assay to IR. (C) MMS, (D) UV irradiation, (E) nitrogen mustard, and (F) HU exposure of L1 stage worms sensitivity assay. Assays were performed as described in Materials and Methods. Error bars represent s.e.m.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2908289&req=5

pgen-1001025-g003: Sensitivity of gen-1 (tm2940) and gen-1 (yp30) in response to DNA damaging agents.(A) L1 stage worms sensitivity assay to IR, (B) L4 stage worms sensitivity assay to IR. (C) MMS, (D) UV irradiation, (E) nitrogen mustard, and (F) HU exposure of L1 stage worms sensitivity assay. Assays were performed as described in Materials and Methods. Error bars represent s.e.m.
Mentions: A Holliday junction-resolving activity is likely to be required for meiotic recombination, and a defect in this activity is predicted to result in embryonic lethality due to random autosome segregation in meiosis [55]. We can exclude such a defect as gen-1(tm2940) worms propagate as wild type, and fail to exhibit embryonic lethality in the absence of genotoxic stress (Figure 3A (0 Gy)). Furthermore, we did not observe an enhanced incidence of XO males, a phenotype that would indicate defects in meiotic chromosome pairing or recombination of the X chromosome (Table 1) [56].

Bottom Line: DNA double-strand breaks (DSBs) can be repaired by homologous recombination (HR), which can involve Holliday junction (HJ) intermediates that are ultimately resolved by nucleolytic enzymes.An N-terminal fragment of human GEN1 has recently been shown to act as a Holliday junction resolvase, but little is known about the role of GEN-1 in vivo.Furthermore, GEN-1 acts redundantly with the 9-1-1 complex to ensure genome stability.

View Article: PubMed Central - PubMed

Affiliation: Wellcome Trust Centre for Gene Regulation and Expression, University of Dundee, Dundee, United Kingdom.

ABSTRACT
DNA double-strand breaks (DSBs) can be repaired by homologous recombination (HR), which can involve Holliday junction (HJ) intermediates that are ultimately resolved by nucleolytic enzymes. An N-terminal fragment of human GEN1 has recently been shown to act as a Holliday junction resolvase, but little is known about the role of GEN-1 in vivo. Holliday junction resolution signifies the completion of DNA repair, a step that may be coupled to signaling proteins that regulate cell cycle progression in response to DNA damage. Using forward genetic approaches, we identified a Caenorhabditis elegans dual function DNA double-strand break repair and DNA damage signaling protein orthologous to the human GEN1 Holliday junction resolving enzyme. GEN-1 has biochemical activities related to the human enzyme and facilitates repair of DNA double-strand breaks, but is not essential for DNA double-strand break repair during meiotic recombination. Mutational analysis reveals that the DNA damage-signaling function of GEN-1 is separable from its role in DNA repair. GEN-1 promotes germ cell cycle arrest and apoptosis via a pathway that acts in parallel to the canonical DNA damage response pathway mediated by RPA loading, CHK1 activation, and CEP-1/p53-mediated apoptosis induction. Furthermore, GEN-1 acts redundantly with the 9-1-1 complex to ensure genome stability. Our study suggests that GEN-1 might act as a dual function Holliday junction resolvase that may coordinate DNA damage signaling with a late step in DNA double-strand break repair.

Show MeSH
Related in: MedlinePlus