title: Transient DNA demethylation in differentiating mouse myoblasts correlates with higher activity of 5-methyldeoxycytidine excision repair.
abstract: It has been recently shown that in developing chicken embryonic nuclear extracts there is a 5-methyldeoxycytidine excision repair activity (Jost, J. P. (1993) Proc. Natl. Acad. Sci. U. S. A. 90, 4684-4688). We show that in differentiating mouse myoblasts, a similar enzymatic reaction may be responsible for the genome-wide DNA demethylation (up to 50% of all CmCGG) occurring between the 3rd and 5th days of differentiation. Furthermore, in differentiating myoblasts, there is first a 50% transient decrease in DNA methyltransferase activity and a 90% drop in the rate of DNA synthesis, followed by an increase in 5-methyl-CpG endonuclease and 5-methyldeoxycytidine excision repair activities. As tested in vitro, the maximal activity of the 5-methyldeoxycytidine excision repair coincides with the maximal in vivo genome-wide DNA demethylation. We also find that 3-aminobenzamide, a potent inhibitor of ADP-ribosyltransferase, blocks the differentiation of myoblasts, the 5-methyldeoxycytidine excision repair activity, and the genome-wide demethylation.
authors.affiliation: Friedrich Miescher Institute, Basel, Switzerland.
authors.forename: J P
authors.initials: JP
authors.lastname: Jost
authors.forename: Y C
authors.initials: YC
authors.lastname: Jost
mesh_terms: D000818:Animals; D001483:Base Sequence; D001549:Benzamides / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002642:Chick Embryo; D004247:DNA / Q000096:biosynthesis / Q000378:metabolism*; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism*; D004260:DNA Repair; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000378:metabolism; D007700:Kinetics; D051379:Mice; D008969:Molecular Sequence Data; D009132:Muscles / Q000166:cytology / Q000378:metabolism*; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis / Q000378:metabolism; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D013379:Substrate Specificity; D013997:Time Factors
chemical_list: D001549:Benzamides; D009838:Oligodeoxyribonucleotides; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D003841:Deoxycytidine; C025160:3-aminobenzamide; D004247:DNA; C016569:5-methyldeoxycytidine; D004248:DNA (Cytosine-5-)-Methyltransferases