Abstract
Apaf1 is a key regulator of the mitochondrial intrinsic pathway of apoptosis, as it activates executioner caspases by forming the apoptotic machinery apoptosome. Its genetic regulation and its post-translational modification are crucial under the various conditions where apoptosis occurs. Here we describe Ku70/86, a mediator of non-homologous end-joining pathway of DNA repair, as a novel regulator of Apaf1 transcription. Through analysing different Apaf1 promoter mutants, we identified an element repressing the Apaf1 promoter. We demonstrated that Ku70/86 is a nuclear factor able to bind this repressing element and downregulating Apaf1 transcription. We also found that Ku70/86 interaction with Apaf1 promoter is dynamically modulated upon DNA damage. The effect of this binding is a downregulation of Apaf1 expression immediately following the damage to DNA; conversely, we observed Apaf1 upregulation and apoptosis activation when Ku70/86 unleashes the Apaf1-repressing element. Therefore, besides regulating DNA repair, our results suggest that Ku70/86 binds to the Apaf1 promoter and represses its activity. This may help to inhibit the apoptosome pathway of cell death and contribute to regulate cell survival.
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Abbreviations
- Apaf1:
-
apoptotic protease activating factor
- Bac:
-
bacterial artificial chromosome
- ChIP:
-
chromatin immunoprecipitation
- CMV:
-
Cytomegalovirus
- DNA-PKcs:
-
DNA-dependent protein kinase catalytic subunit
- DSB:
-
double-strand break
- EMSA:
-
electrophoretic mobility shift assay
- ERBB2:
-
erythrocyte blastosis virus B2
- ETNA:
-
Embryonic Telencephalic Naïve Apaf1 cells
- G6pdx:
-
glucose-6-phosphate dehydrogenase X-linked
- HDAC:
-
histone deacetylase
- NHEJ:
-
non-homologous end-joining
- 8-OHdG:
-
8-hydroxydeoxyguanosine
- Pol II:
-
RNA polymerase II
- STS:
-
staurosporine
- TSP:
-
transcription start point
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Acknowledgements
F Cecconi is supported by grants from the Telethon Foundation, AIRC, the Italian Ministry of Health and the Italian Ministry of University and Research. D De Zio is supported by a fellowship from the Telethon Foundation. The authors thank M Acuna Villa and MW Bennett for editorial and secretarial work, F Florenzano and G Filomeni for research assistance, and A Nobili for technical support.
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De Zio, D., Bordi, M., Tino, E. et al. The DNA repair complex Ku70/86 modulates Apaf1 expression upon DNA damage. Cell Death Differ 18, 516–527 (2011). https://doi.org/10.1038/cdd.2010.125
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DOI: https://doi.org/10.1038/cdd.2010.125
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