DNA double-strand break-induced phosphorylation of Drosophila histone variant H2Av helps prevent radiation-induced apoptosis.
The response of eukaryotic cells to the formation of a double-strand break (DSB) in chromosomal DNA is highly conserved. One of the earliest responses to DSB formation is phosphorylation of the C-terminal tail of H2A histones located in nucleosomes near the break. Histone variant H2AX and core histone H2A are phosphorylated in mammals and budding yeast, respectively. We demonstrate the DSB-induced phosphorylation of histone variant H2Av in Drosophila melanogaster. H2Av is a member of the H2AZ family of histone variants. Ser137 within an SQ motif located near the C- terminus of H2Av was phosphorylated in response to gamma-irradiation in both tissue culture cells and larvae. Phosphorylation was detected within 1 min of irradiation and detectable after only 0.3 Gy of radiation exposure. Photochemically induced DSBs, but not general oxidative damage or UV-induced nicking of DNA, caused H2Av phosphorylation, suggesting that phosphorylation is DSB specific. Imaginal disc cells from Drosophila expressing a mutant allele of H2Av with its C-terminal tail deleted, and therefore unable to be phosphorylated, were more sensitive to radiation-induced apoptosis than were wildtype controls, suggesting that phosphorylation of H2Av is important for repair of radiation-induced DSBs. These observations suggest that in addition to providing the function of an H2AZ histone, H2Av is also the functional homolog in Drosophila of H2AX.
Madigan
James P
JP
Wadsworth Center, New York State Department of Health, State University of New York, Albany, NY 12201-2002, USA.
Chotkowski
Heather L
HL
Glaser
Robert L
RL
D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000528:radiation effects*; D015153:Blotting, Western; D002460:Cell Line; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D004330:Drosophila / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D005838:Genotype; D006657:Histones / Q000235:genetics / Q000378:metabolism*; D007814:Larva / Q000166:cytology / Q000235:genetics / Q000528:radiation effects; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D017386:Sequence Homology, Amino Acid
D006657:Histones; D004247:DNA