Epigenomic Stress Response

• Published in: The Journal of biological chemistry Vol. 278; no. 17; pp. 14985 - 14995
• Main Authors: Milutinovic, Snezana, Zhuang, Qianli, Niveleau, Alain, Szyf, Moshe
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 25.04.2003; American Society for Biochemistry and Molecular Biology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M213219200

The DNA methylation pattern is an important component of the epigenome that regulates and maintains gene expression programs. In this paper, we test the hypothesis that vertebrate cells possess mechanisms protecting them from epigenomic stress similar to DNA damage checkpoints. We show that knockdown of DNMT1 (DNA methyltransferase1) by an antisense oligonucleotide triggers an intra-S-phase arrest of DNA replication that is not observed with control oligonucleotide. The cells are arrested at different positions throughout the S-phase of the cell cycle, suggesting that this response is not specific to distinct classes of origins of replication. The intra-S-phase arrest of DNA replication is proposed to protect the genome from extensive DNA demethylation that could come about by replication in the absence of DNMT1. This protective mechanism is not induced by 5-aza-2′-deoxycytidine, a nucleoside analog that inhibits DNA methylation by trapping DNMT1 in the progressing replication fork, but does not reduce de novosynthesis of DNMT1. Our data therefore suggest that the intra-S-phase arrest is triggered by a reduction in DNMT1 and not by demethylation of DNA. DNMT1 knockdown also leads to an induction of a set of genes that are implicated in genotoxic stress response such asNF-κB, JunB, ATF-3, and GADD45β (growth arrestDNA damage 45β gene). Based on these data, we suggest that this stress response mechanism evolved to guard against buildup of DNA methylation errors and to coordinate inheritance of genomic and epigenomic information.