BRAP-2 promotes DNA damage induced germline apoptosis in C. elegans through the regulation of SKN-1 and AKT-1

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As part of the DNA damage response (DDR) network, the tumour suppressor Breast cancer susceptibility gene 1 (BRCA1) is activated to facilitate DNA repair, transcription and cell cycle control. BRC-1, the Caenorhabditiselegans ortholog of BRCA1, has conserved function in DNA double strand break repair, wherein a loss of brc-1 results in high levels of germline apoptosis. BRAP2/IMP was initially identified as a BRCA1 associated binding protein and previously we have shown that the C. elegans brap-2 deletion mutant experiences BRC-1 dependent larval arrest when exposed to low concentrations of paraquat. Since BRC-1 function in the germline is conserved, we wanted to determine the role of BRAP-2 in DNA damage induced germline apoptosis in C. elegans. We examined levels of germ cell death following DNA damage and found that brap-2(ok1492) mutants display reduced levels of germline apoptosis when compared to the wild type, and the loss of brap-2 significantly reduced germ cell death in brc-1 mutant animals. We also found increased mRNA levels of skn-1 following DNA damage in brap-2 mutants and that skn-1 RNAi knockdown in brap-2;brc-1 double mutants and a loss of pmk-1 mutation in brap-2 mutants increased apoptosis to wild type levels, indicating that brap-2 promotion of cell survival requires PMK-1 and SKN-1. Since mammalian BRAP2 has been shown to bind the AKT phosphatase PHLPP1/2, it suggests that BRAP2 could be involved in the Insulin/Insulin-like growth factor Signaling (IIS) pathway. We found that this interaction is conserved between the C. elegans homologs and that a loss of akt-1 in brap-2 mutants increased germline apoptosis. Thus in response to DNA damage, our findings suggest that BRAP-2 is required to attenuate the pro-cell survival signals of AKT-1 and PMK-1/SKN-1 to promote DNA damage induced germline apoptosis.

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A number of strains were provided by the CGC, which is funded by NIH Office of Research Infrastructure Programs (P40 OD010440) and the National BioResource Project. AKT antibodies were a kind gift from W.B. Derry of Hospital for Sick Children, Toronto. We thank the Derry Lab (E. Chapman, B. Yu, B. Lant, A. Mateo, M. Hall, M. Gunda and M. Haeri) for their assistance with the irradiation. D.R.D. is a recipient of the Ontario Graduate Scholarship. M.P. is a recipient of the Dean’s Award from the Faculty of Science, York University and a Natural Sciences and Engineering Research Council of Canada (NSERC) undergraduate studentship. D.R.D., Q.H., M.P. and T.J.K were supported by a grant from NSERC.

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Author notes

  1. Edited by E Baehrecke


  1. Department of Biology, York University, Toronto, Ontario, Canada

    • Dayana R. D’Amora
    • , Queenie Hu
    • , Monica Pizzardi
    •  & Terrance J. Kubiseski
  2. Sunnybrook Research Institute, Toronto, Ontario, Canada

    • Queenie Hu
  3. Program in Neuroscience, York University, Toronto, Ontario, Canada

    • Terrance J. Kubiseski


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The authors declare that they have no conflict of interest.

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Correspondence to Terrance J. Kubiseski.

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