Meiotic and epigenetic aberrations inDnmt3L-deficient male germ cells

Abstract

The DNA methyltransferase-like protein Dnmt3L is necessary for the establishment of genomic imprints in oogenesis and for normal spermatogenesis (Bourc'his et al., 2001; Hata et al., 2002). Also, a paternally imprinted gene, H19, loses DNA methylation in Dnmt3L-/- spermatogonia (Bourc'his and Bestor, 2004; Kaneda et al., 2004). To determine the reason for the impaired spermatogenesis in the Dnmt3L-/- testes, we have carried out a series of histological and molecular studies. We show here that Dnmt3L-/- germ cells were arrested and died around the early meiotic stage. A microarray-based gene expression-profiling analysis revealed that various gonad-specific and/or sex-chromosome-linked genes were downregulated in the Dnmt3L-/- testes. In contrast, expression of retrovirus-like intracisternal A-particle (IAP) sequences was upregulated; consistent with this observation, a specific IAP copy showed complete loss of DNA methylation. These findings indicate that Dnmt3L regulates germ cell-specific gene expression and IAP suppression, which are critical for male germ cell proliferation and meiosis.

In situ detection of methylated DNA by histo endonuclease-linked detection of methylated DNA sites: a new principle of analysis of DNA methylation

“…Rather, more importantly, the down-regulation of methylation of CCGG sites may be a possible trigger of induction of germ cell apoptosis in premeiotic germ cells. In agreement with our findings, it is already known that treatment with 5-aza-2'-deoxycytidine (Kelly et al 2003) and mutation of Dnmt3L gene (Hata et al 2006), both of which induce a reduction or loss of DNA methylation in mouse testis, resulted in histological anomalies and germ cell loss in mouse testis. Koji T et al,Page 18 The present results also indicated that the level of methylation at CCGG sites in germ cells was generally higher than that in somatic cells like Sertoli cells.…”

“…Kelly et al (2003) reported that the use of Koji T et al,Page 5 5-aza-2'-deoxycytidine, a cytidine analogue known to decrease the level of DNA methylation, results in histological anomalies in testis. Moreover, DNA methyltransferase-like protein (Dnmt3L) homozygous mutant mice, which exhibit low methylation of DNA in testis, are infertile (Bourc'his et al 2001;Hata et al 2002) and are subject to meiotic aberrations with the appearance of apoptosis-like germ cells (Bourc'his and Bestor 2004;Hata et al 2006).…”

Conserved themes in small-RNA-mediated transposon control

“…Of all the Dnmts, the role of Dnmt3L in transposon silencing has been described in the most detail. Dnmt3L lacks catalytic activity but is required for transcriptional repression, as well as for DNA methylation of the LTR-class IAP elements and the non-LTR class LINE-1 elements (long interspersed elements-1) in the male germline [114][115][116]. Again, methylation of H3K9 and DNA seem to be linked in this context.…”

“…Dnmt3L is a known partner of the de novo methyltransferase Dnmt3a [122][123][124] and, as such, might be involved in the establishment of DNA methylation patterns in the male germline. The strong resemblance among dnmt3l, miwi2 and mili phenotypes [45,86,[114][115][116]125] suggests that these genes all act in de novo methylation of transposon sequences.…”

Maintenance of self‐renewal ability of mouse embryonic stem cells in the absence of DNA methyltransferases Dnmt1, Dnmt3a and Dnmt3b

“…2003;Bourc'his & Bestor 2004;Dodge et al . 2005;Hata et al . 2006), indicating that CpG methylation plays a fundamental role in basic cellular functions of mammalian cells.…”