title: 5-Methylcytosine DNA glycosylase participates in the genome-wide loss of DNA methylation occurring during mouse myoblast differentiation.
abstract: Changes in gene expression during mouse myoblast differentiation were monitored by DNA microarray hybridisation. Four days after the onset of differentiation 2.37% of the genes increased in activity from a value of zero, whereas during the same time 1.68% of total genes had decreased expression. During the first 24 h of differentiation an average of 700 000 CpG sites per haploid genome were demethylated. Maximal loss of DNA methylation is attained after 2 days of differentiation, followed by a gradual remethylation. The highest demethylation is observed in highly repeated DNA sequences, followed by single copy sequences. When DNA replication is inhibited by aphidicolin or L-mimosine this genome-wide demethylation is still observed. During the first 3 h of differentiation there is an increase in the number of hemimethylated CpG sites, which disappear rapidly during the course of genome-wide hypomethylation. Transfection of cells with an antisense morpholino oligonucleotide to 5-methylcytosine DNA glycosylase (G/T mismatch DNA glycosylase) decreases both the activity of the enzyme and genome-wide demethylation. It is concluded that the genome-wide loss of DNA methylation in differentiating mouse myoblasts occurs in part by formation of hemimethylated CpG sites, which can serve as the substrate for 5-methylcytosine-DNA glycosylase.
authors.affiliation: Friedrich Miescher Institut, Maulbeerstrasse 66, CH-4058 Basel, Switzerland. jost@fmi.ch
authors.forename: J P
authors.initials: JP
authors.lastname: Jost
authors.forename: E J
authors.initials: EJ
authors.lastname: Oakeley
authors.forename: B
authors.initials: B
authors.lastname: Zhu
authors.forename: D
authors.initials: D
authors.lastname: Benjamin
authors.forename: S
authors.initials: S
authors.lastname: Thiry
authors.forename: M
authors.initials: M
authors.lastname: Siegmann
authors.forename: Y C
authors.initials: YC
authors.lastname: Jost
mesh_terms: D000818:Animals; D016590:Aphidicolin / Q000494:pharmacology; D002454:Cell Differentiation; D002478:Cells, Cultured; D018899:CpG Islands / Q000235:genetics; D004247:DNA / Q000096:biosynthesis; D045647:DNA Glycosylases; D019175:DNA Methylation / Q000187:drug effects; D004261:DNA Replication / Q000187:drug effects; D020869:Gene Expression Profiling; D016678:Genome; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D051379:Mice; D008898:Mimosine / Q000494:pharmacology; D009132:Muscles / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D009699:N-Glycosyl Hydrolases / Q000235:genetics / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D016376:Oligonucleotides, Antisense / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014162:Transfection
chemical_list: D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger; D016590:Aphidicolin; D008898:Mimosine; D004247:DNA; C093335:5-methylcytosine-DNA glycosylase; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases