Sex-specific promoters regulate Dnmt3L expression in mouse germ cells.
BACKGROUND
Dnmt3L, a member of the DNA methyltransferase 3 family, lacks enzymatic activity but is required for de-novo methylation of imprinted genes in oocytes and for transposon repression in male germ cells.


METHODS
We used northern blots, RT-PCR, 5' rapid amplification of complementary DNA (cDNA) ends (RACE), RNase H mapping, real-time/quantitative RT-PCR and in situ hybridization to identify and characterize Dnmt3L transcripts produced during germ cell development.


RESULTS
Mouse Dnmt3L uses three sex-specific promoters, not the single promoter previously thought. A promoter active in prospermatogonia drives transcription of an mRNA encoding the full-length protein in perinatal testis, where de-novo methylation occurs. Late pachytene spermatocytes activate a second promoter in intron 9 of the Dnmt3L gene. After this stage, the predominant transcripts are three truncated mRNAs, which appear to be non-coding. We could also detect similar adult testis transcripts in humans. In the mouse ovary, an oocyte-specific promoter located in an intron of the neighbouring autoimmune regulator (Aire) gene produces a transcript with the full open reading frame (ORF). This is the only Dnmt3L transcript found in growing oocytes and is absent in the oocytes of Dnmt3L-/- females.


CONCLUSIONS
Sex-specific promoters control Dnmt3L expression in the mouse germ line, mirroring the situation at the Dnmt1 and Dnmt3A loci.
Shovlin
T C
TC
Stem Cells and Epigenetics Research Group, Centre for Molecular Biosciences, School of Biomedical Sciences, University of Ulster, Coleraine, UK.
Bourc'his
D
D
La Salle
S
S
O'Doherty
A
A
Trasler
J M
JM
Bestor
T H
TH
Walsh
C P
CP
D000818:Animals; D015152:Blotting, Northern; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000096:biosynthesis*; D005260:Female; D018392:Genomic Imprinting; D005854:Germ Cells / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D021141:Nucleic Acid Amplification Techniques; D009865:Oocytes / Q000201:enzymology; D010053:Ovary / Q000201:enzymology; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016914:Ribonuclease H / Q000378:metabolism; D012737:Sex Factors; D013087:Spermatids / Q000201:enzymology; D013093:Spermatogonia / Q000201:enzymology
C498796:Dnmt3l protein, mouse; D004248:DNA (Cytosine-5-)-Methyltransferases; D016914:Ribonuclease H