A Conserved E2F6-Binding Element in Murine Meiosis-Specific Gene Promoters1

Abstract

During gametogenesis, germ cells must undergo meiosis in order to become viable haploid gametes. Successful completion of this process is dependent upon the expression of genes whose protein products function specifically in meiosis. Failure to express these genes in meiotic cells often results in infertility, whereas aberrant expression in somatic cells may lead to mitotic catastrophe. The mechanisms responsible for regulating the timely expression of meiosis-specific genes have not been fully elucidated. Here we demonstrate that E2F6, a member of the E2F family of transcription factors, is essential for the repression of the newly identified meiosis-specific gene, Slc25a31 (also known as Ant4, Aac4), in somatic cells. This discovery, along with previous studies, prompted us to investigate the role of E2F6 in the regulation of meiosis-specific genes in general. Interestingly, the core E2F6-binding element (TCCCGC) was highly conserved in the proximal promoter regions of 19 out of 24 (79.2%) meiosis-specific genes. This was significantly higher than the frequency found in the promoters of all mouse genes (15.4%). In the absence of E2F6, only a portion of these meiosis-specific genes was derepressed in somatic cells. However, endogenous E2F6 bound to the promoters of these meiosis-specific genes regardless of whether they required E2F6 for their repression in somatic cells. Further, E2F6 overexpression was capable of reducing their transcription. These findings indicate that E2F6 possesses a broad ability to bind to and regulate the meiosis-specific gene population.

Dnmt3b recruitment through E2F6 transcriptional repressor mediates germ-line gene silencing in murine somatic tissues

“…Coherent with this factor's involvement in transcriptional repression, we report that repression of Dnmt3b-target germ-line genes in WT cells requires E2F6 binding to their regulatory sequences. This adds unique target genes to the previously reported germ-line genes that are derepressed in somatic tissues as a consequence of invalidation of E2F6 in mice (38,44,45). Importantly, binding of E2F6 is required for Dnmt3b binding to the promoter region of these germline genes, as well as essential to maintain their silent state, in four of five Dnmt3b target germ-line genes, providing evidence that these genes are silenced in somatic cells through a Dnmt3b-dependant DNA methylation, through recruitment by the E2F6 transcriptional repressor.…”

“…S7B). In addition, among the genes we have identified as potential Dnmt3b target genes, Slc25a31 and Hoxa11 were already known to be targeted and repressed by E2F6 (38,39). We therefore focused on this particular factor and investigated the interplay between the transcriptional repressor E2F6 and Dnmt3b in the silencing of germ-line genes in somatic tissues.…”

Adenine nucleotide translocase: a component of the phylogenetically conserved cell death machinery

“…Intriguingly, ANT4 (which is conserved in mammals yet absent in non-mammalian species) has been indicated as a mitosis-specific protein that is repressed in somatic cells by the E2F6 transcription factor. 48 The mitochondrial phosphate carrier (SLC25A3), another member of the MCP family, has been found to interact with the viral Bcl-2 analog vMIA (encoded by the genome of Cytomegalovirus) 49 and to induce apoptosis on overexpression. 50 Accordingly, knockdown of this protein, which can interact with ANT1 and with the voltage-dependent anion channel (VDAC), limited staurosporine (STS)-induced cytochrome c release and apoptosis.…”

Mitochondrial ATP transporter Ant2 depletion impairs erythropoiesis and B lymphopoiesis

“…12,13 In contrast, Ant4 is exclusively expressed in meiotic germ cells and repressed in somatic tissues. [15][16][17] Non-rodent mammals including humans have an additional paralog Ant3 (Slc25a6), which is as ubiquitously expressed like Ant2. In humans, ANT2 is induced by cell proliferation, while ANT3 is rather constitutively expressed.…”