Published online July 16, 2007
doi:10.1083/jcb.200612031
The Journal of Cell Biology, Vol. 178, No. 2, 209-218
The Rockefeller University Press, 0021-9525 $30.00
© 2007 Kim et al.
Heterochromatin is refractory to
-H2AX modification in yeast and mammals
Jung-Ae Kim1,2,
Michael Kruhlak3,
Farokh Dotiwala1,2,
André Nussenzweig3, and
James E. Haber1,2
1 Rosenstiel Center and 2 Department of Biology, Brandeis University, Waltham, MA 02454
3 Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
Correspondence to James E. Haber: haber{at}brandeis.edu
Double-strand break (DSB) damage in yeast and mammalian cells induces the rapid ATM (ataxia telangiectasia mutated)/ATR (ataxia telangiectasia and Rad3 related)-dependent phosphorylation of histone H2AX (
-H2AX). In budding yeast, a single endonuclease-induced DSB triggers
-H2AX modification of 50 kb on either side of the DSB. The extent of
-H2AX spreading does not depend on the chromosomal sequences. DNA resection after DSB formation causes the slow, progressive loss of
-H2AX from single-stranded DNA and, after several hours, the Mec1 (ATR)-dependent spreading of
-H2AX to more distant regions. Heterochromatic sequences are only weakly modified upon insertion of a 3-kb silent HMR locus into a
-H2AXcovered region. The presence of heterochromatin does not stop the phosphorylation of chromatin more distant from the DSB. In mouse embryo fibroblasts,
-H2AX distribution shows that
-H2AX foci increase in size as chromatin becomes more accessible. In yeast, we see a high level of constitutive
-H2AX in telomere regions in the absence of any exogenous DNA damage, suggesting that yeast chromosome ends are transiently detected as DSBs.
Abbreviations used in this paper: ChIP, chromatin immunoprecipitation; CPY, carboxy peptidase Y; DSB, double-strand break; MMS, methylmethanesulfonate; NCS, neocarzinostatin; TPE, telomere position effect; TSA, trichostatin A.

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