Sex-specific promoters regulate Dnmt3L expression in mouse germ cells

Abstract

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.

The zinc-finger protein basonuclin 2 is required for proper mitotic arrest, prevention of premature meiotic initiation and meiotic progression in mouse male germ cells

“…DNMT3L is a zinc-finger protein that resembles cytosine-5-methyltransferase 3, but lacks its catalytic domains. Dnmt3l is expressed from E14.5 until the perinatal period in prospermatogonia, but not in oocytes; it is required for retrotransposon inactivation (Aapola et al, 2000;Bourc'his and Bestor, 2004;Bourc'his et al, 2001;Shovlin et al, 2007). The albumin gene is specifically expressed in prospermatogonia of newborn testis and is not expressed in the ovary (Gelly et al, 1994;McLeod and Cooke, 1989).…”

Foetal germ cells: striking the balance between pluripotency and differentiation

“…epigenetic marks, such as genomic imprints, are re-established through the activity of DNMT3L and the de novo methyltransferase DNMT3A (Bourc'his et al, 2001;Hata et al, 2002;Bourc'his and Bestor, 2004;Kaneda et al, 2004;La Salle et al, 2004;Sakai et al, 2004;Webster et al, 2005;Kato et al, 2007;Lucifero et al, 2007;Shovlin et al, 2007). Establishment of appropriate epigenetic patterns subsequent to reprogramming is essential for normal development and in some cases (for example genomic imprints) these epigenetic patterns will be maintained in all somatic cells throughout the life of an individual.…”

“…These changes include aspects of epigenetic programming, regulation of pluripotency, cell signalling and nuclear import/export, sex specific development and regulation of gene and protein expression. DNA methylation at imprinted loci is regulated in quiescent germ cells through the activity of DNMT3A and DNMT3L which are both up regulated early during male germ cell differentiation and are required for establishing imprints during this developmental phase (Bourc'his et al, 2001;Hata et al, 2002;Bourc'his and Bestor, 2004;Kaneda et al, 2004;Sakai et al, 2004;Webster et al, 2005;Kato et al, 2007;Lucifero et al, 2007;Shovlin et al, 2007). Proteins such as, NANOS2, a member In mice male sex determination is initiated by SRY, which commits the somatic supporting cells to Sertoli cell development.…”

Plasticity in Dnmt3L-dependent and -independent modes of de novo methylation in the developing mouse embryo

“…In vivo, Dnmt3l is highly expressed during gametogenesis under the control of sex-specific promoters (Bourc'his et al, 2001;Shovlin et al, 2007). The canonical transcript is produced in prospermatogonia, whereas in oocytes a longer transcript originates from an upstream promoter embedded in an intron of the neighboring Aire gene.…”