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Heterochromatin is refractory to γ-H2AX modification in yeast and mammals

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 (γ-H2AX). In budding yeast, a single endonuclease-induced DSB triggers γ-H2AX modification of 50...

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Detalles Bibliográficos
Autores principales: Kim, Jung-Ae, Kruhlak, Michael, Dotiwala, Farokh, Nussenzweig, André, Haber, James E.
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 2007
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2064441/
https://www.ncbi.nlm.nih.gov/pubmed/17635934
http://dx.doi.org/10.1083/jcb.200612031
Descripción
Sumario: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 (γ-H2AX). In budding yeast, a single endonuclease-induced DSB triggers γ-H2AX modification of 50 kb on either side of the DSB. The extent of γ-H2AX spreading does not depend on the chromosomal sequences. DNA resection after DSB formation causes the slow, progressive loss of γ-H2AX from single-stranded DNA and, after several hours, the Mec1 (ATR)-dependent spreading of γ-H2AX to more distant regions. Heterochromatic sequences are only weakly modified upon insertion of a 3-kb silent HMR locus into a γ-H2AX–covered region. The presence of heterochromatin does not stop the phosphorylation of chromatin more distant from the DSB. In mouse embryo fibroblasts, γ-H2AX distribution shows that γ-H2AX foci increase in size as chromatin becomes more accessible. In yeast, we see a high level of constitutive γ-H2AX in telomere regions in the absence of any exogenous DNA damage, suggesting that yeast chromosome ends are transiently detected as DSBs.