Increased ionizing radiation sensitivity and genomic instability in the absence of histone H2AX.

Howard Hughes Medical Institute, Department of Genetics, Children's Hospital, Boston, MA 02115, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.81). 07/2002; 99(12):8173-8. DOI: 10.1073/pnas.122228699
Source: PubMed

ABSTRACT In mammalian cells, DNA double-strand breaks (DSBs) cause rapid phosphorylation of the H2AX core histone variant (to form gamma-H2AX) in megabase chromatin domains flanking sites of DNA damage. To investigate the role of H2AX in mammalian cells, we generated H2AX-deficient (H2AX(Delta)/Delta) mouse embryonic stem (ES) cells. H2AX(Delta)/Delta ES cells are viable. However, they are highly sensitive to ionizing radiation (IR) and exhibit elevated levels of spontaneous and IR-induced genomic instability. Notably, H2AX is not required for NHEJ per se because H2AX(Delta)/Delta ES cells support normal levels and fidelity of V(D)J recombination in transient assays and also support lymphocyte development in vivo. However, H2AX(Delta)/Delta ES cells exhibit altered IR-induced BRCA1 focus formation. Our findings indicate that H2AX function is essential for mammalian DNA repair and genomic stability.

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