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Andrew J Bannister

Publications and source records attributed to Andrew J Bannister.

17 recordsLinked to original sources
PubMed2006

Blimp1 associates with Prmt5 and directs histone arginine methylation in mouse germ cells.

Blimp1, a transcriptional repressor, has a crucial role in the specification of primordial germ cells (PGCs) in mice at embryonic day 7.5 (E7.5). This SET-PR domain protein can form complexes with various chromatin modifiers in a context-dependent manner. Here, we show that Blimp1 has a novel interaction with Prmt5, an arginine-specific histone methyltransferase, which mediates symmetrical dimethylation of arginine 3 on histone H2A and/or H4 tails (H2A/H4R3me2s). Prmt5 has been shown to associate with Tudor, a component of germ plasm in Drosophila melanogaster. Blimp1-Prmt5 colocalization results in high levels of H2A/H4 R3 methylation in PGCs at E8.5. However, at E11.5, Blimp1-Prmt5 translocates from the nucleus to the cytoplasm, resulting in the loss of H2A/H4 R3 methylation at the time of extensive epigenetic reprogramming of germ cells. Subsequently, Dhx38, a putative target of the Blimp1-Prmt5 complex, is upregulated. Interestingly, expression of Dhx38 is also seen in pluripotent embryonic germ cells that are derived from PGCs when Blimp1 expression is lost. Our study demonstrates that Blimp1 is involved in a novel transcriptional regulatory complex in the mouse germ-cell lineage.

Active Transport, Cell Nucleus↗
PubMed2006

Dynamic distribution of the replacement histone variant H3.3 in the mouse oocyte and preimplantation embryos.

Upon fertilization, the gametes undergo a drastic reprogramming that includes changes in DNA methylation and histone modifications. Currently, it is not known whether replacement of the major histones by histone variants is also involved in these processes. Here we have examined the expression and localization of the histone variant H3.3 in early mouse embryogenesis. We show that H3.3 is present in the oocyte as a maternal factor. It is then incorporated preferentially into the male pronucleus before genome activation, pointing towards an asymmetry in histone composition between the two pronuclei. This is in line with the male pronucleus bearing transcriptional activation first. The same distribution was observed when we followed the localisation of a tagged version of H3.3. We detected H3.3 in the nuclei of mouse embryos in all of the stages analysed, from the zygote to the blastocyst stage, suggesting that the epigenetic mechanisms in the early embryo not only involve changes in histone modifications but may also include histone replacement.

Animals↗
PubMed2005

Reversing histone methylation.

Histones package DNA, and post-translational modifications of histones can regulate access to DNA. Until recently, histone methylation-unlike all other histone modifications-was considered a permanent mark. The discovery of enzymes that reverse the methylation of lysines and arginines challenges our current thinking on the unique nature of histone methylation, and substantially increases the complexity of histone modification pathways.

Animals↗
PubMed2005

Spatial distribution of di- and tri-methyl lysine 36 of histone H3 at active genes.

Methylation of lysine 4 of histone H3 (K4/H3) is linked to transcriptional activity, whereas methylation of K9/H3 is tightly associated with gene inactivity. These are well characterized sites of methylation within histones, but there are numerous other, less characterized, sites of modification. In Saccharomyces cerevisiae, methylation of K36/H3 has been linked to active genes, but little is known about this methylation in higher eukaryotes. Here we analyzed for the first time the levels and spatial distribution of di- and tri-methyl (di- and tri-Me) K36/H3 in metazoan genes. We analyzed chicken genes that are developmentally regulated, constitutively active, or inactive. We found that active genes contain high levels of these modifications compared with inactive genes. Furthermore, in actively transcribed regions the levels of di- and tri-Me K36/H3 peak toward the 3' end of the gene. This is in striking contrast to the distributions of di- and tri-Me K4/H3, which peak early in actively transcribed regions. Thus, di/tri-Me K4/H3 and di/tri-Me K36/H3 are both useful markers of active genes, but their genic distribution indicates differing roles. Our data suggest that the unique spatial distribution of di- and tri-Me K36/H3 plays a role in transcriptional termination and/or early RNA processing.

Animals↗
PubMed2004

Histone deimination antagonizes arginine methylation.

Methylation of arginine residues within histone H3 has been linked to active transcription. This modification appears on the estrogen-regulated pS2 promoter when the CARM1 methyltransferase is recruited during transcriptional activation. Here we describe a process, deimination, that converts histone arginine to citrulline and antagonizes arginine methylation. We show that peptidyl arginine deiminase 4 (PADI4) specifically deiminates, arginine residues R2, R8, R17, and R26 in the H3 tail. Deimination by PADI4 prevents arginine methylation by CARM1. Dimethylation of arginines prevents deimination by PADI4 although monomethylation still allows deimination to take place. In vivo targeting experiments on an endogenous promoter demonstrate that PADI4 can repress hormone receptor-mediated gene induction. Consistent with a repressive role for PADI4, this enzyme is recruited to the pS2 promoter following hormone induction when the gene is transcriptionally downregulated. The recruitment of PADI4 coincides with deimination of the histone H3 N-terminal tail. These results define deimination as a novel mechanism for antagonizing the transcriptional induction mediated by arginine methylation.

Arginine↗
PubMed2004

Methylation of H3 lysine 4 at euchromatin promotes Sir3p association with heterochromatin.

Set1p methylates lysine 4 of histone H3 and can activate transcription by recruiting the chromatin-remodeling factor Isw1p. In addition, Lys-4-methylated H3 is required for maintenance of silencing at the telomeres, rDNA, and HML locus in Saccharomyces cerevisiae. The molecular mechanism underlying the role of Set1p in silencing is not known. Here we report that euchromatic methylation of H3 Lys-4 is necessary to maintain silencing at specific heterochromatic sites. Inactivation of Set1p catalytic activity or mutation of H3 Lys-4 leads to decreased binding of the silent information regulator Sir3p at heterochromatic sites. Concomitantly, there is an increase in the amount of Sir3p bound to genes located in subtelomeric regions. Consistent with this result is the finding that in vitro, Sir3p preferentially binds histone H3 tails when methylation is absent at H3 Lys-4, a situation found in heterochromatin. The inability of Sir3p to bind methylated H3 Lys-4 tails suggests a model whereby H3 Lys-4 methylation prevents Sir3p association at euchromatic sites and therefore concentrates Sir3p at unmodified, heterochromatic regions of the genome.

DNA Methylation↗
PubMed2004

Direct binding of INHAT to H3 tails disrupted by modifications.

The N-terminal tails of histones are central to the regulation of chromatin structure. They form a binding platform for multiple protein complexes, which in turn regulate DNA processes such as transcription. Using peptide mass fingerprinting we identified INHAT (inhibitor of acetyltransferases) as a specific histone H3 N-terminal tail-binding complex. INHAT comprises two essential subunits, SET and pp32. We demonstrate that both SET and pp32 bind directly to the N terminus of H3. The binding is differentially affected by various modifications within the H3 N terminus. In particular, single phosphorylations within the H3 tail abrogates binding of INHAT, as does the simultaneous acetylation of multiple lysine residues. The histone modifications that affect INHAT binding are therefore compatible with its known role in transcriptional repression. We suggest that the charge of the histone tail is a major determinant in allowing INHAT to bind chromatin and coordinate the activity of multiple histone acetyltransferases.

Acetyltransferases↗
PubMed2003

Histone H3 lysine 4 methylation patterns in higher eukaryotic genes.

Lysine residues within histones can be mono-, di - or tri-methylated. In Saccharomyces cerevisiae tri-methylation of Lys 4 of histone H3 (K4/H3) correlates with transcriptional activity, but little is known about this methylation state in higher eukaryotes. Here, we examine the K4/H3 methylation pattern at the promoter and transcribed region of metazoan genes. We analysed chicken genes that are developmentally regulated, constitutively active or inactive. We found that the pattern of K4/H3 methylation shows similarities to S. cerevisiae. Tri-methyl K4/H3 peaks in the 5' transcribed region and active genes can be discriminated by high levels of tri-methyl K4/H3 compared with inactive genes. However, our results also identify clear differences compared to yeast, as significant levels of K4/H3 methylation are present on inactive genes within the beta-globin locus, implicating this modification in maintaining a 'poised' chromatin state. In addition, K4/H3 di-methylation is not genome-wide and di-methylation is not uniformly distributed throughout the transcribed region. These results indicate that in metazoa, di- and tri-methylation of K4/H3 is linked to active transcription and that significant differences exist in the genome-wide methylation pattern as compared with S. cerevisiae.

Animals↗
PubMed2003

A novel human Ada2 homologue functions with Gcn5 or Brg1 to coactivate transcription.

In yeast, the transcriptional adaptor yeast Ada2 (yAda2) is a part of the multicomponent SAGA complex, which possesses histone acetyltransferase activity through action of the yGcn5 catalytic enzyme. yAda2, among several SAGA proteins, serves to recruit SAGA to genes via interactions with promoter-bound transcription factors. Here we report identification of a new human Ada2 homologue, hAda2beta. Ada2beta differs both biochemically and functionally from the previously characterized hAda2alpha, which is a stable component of the human PCAF (human Gcn5 homologue) acetylase complex. Ada2beta, relative to Ada2alpha, interacted selectively, although not stably, with the Gcn5-containing histone acetylation complex TFTC/STAGA. In addition, Ada2beta interacted with Baf57 (a component of the human Swi/Snf complex) in a yeast two-hybrid screen and associated with human Swi/Snf in vitro. In functional assays, hAda2beta (but not Ada2alpha), working in concert with Gcn5 (but not PCAF) or Brg1 (the catalytic component of hSwi/Snf complex), increased transcription via the B-cell-specific transcription factor Pax5/BSAP. These findings support the view that Gcn5 and PCAF have distinct roles in vivo and suggest a new mechanism of coactivator function, in which a single adaptor protein (Ada2beta) can coordinate targeting of both histone acetylation and chromatin remodeling activities.

Acetyltransferases↗
PubMed2003

Consequences of the depletion of zygotic and embryonic enhancer of zeste 2 during preimplantation mouse development.

Enhancer of zeste 2 (Ezh2), a SET domain-containing protein, is crucial for development in many model organisms, including early mouse development. In mice, Ezh2 is detected as a maternally inherited protein in the oocyte but its function at the onset of development is unknown. We have used a conditional allele of Ezh2 to deplete the oocyte of this maternal inheritance. We show that the loss of maternal Ezh2 has a long-term effect causing severe growth retardation of neonates despite 'rescue' through embryonic transcription from the paternal allele. This phenotypic effect on growth could be attributed to the asymmetric localisation of the Ezh2/Eed complex and the associated histone methylation pattern to the maternal genome, which is disrupted in Ezh2 mutant zygotes. During subsequent development, we detect distinct histone methylation patterns in the trophectoderm and the pluripotent epiblast. In the latter where Oct4 expression continues from the zygote onwards, the Ezh2/Eed complex apparently establishes a unique epigenetic state and plasticity, which probably explains why loss of Ezh2 is early embryonic lethal and obligatory for the derivation of pluripotent embryonic stem cells. By contrast, in the differentiating trophectoderm cells where Oct4 expression is progressively downregulated Ezh2/Eed complex is recruited transiently to one X chromosome in female embryos at the onset of X-inactivation. This accumulation and the associated histone methylation are also lost in Ezh2 mutants, suggesting a role in X inactivation. Thus, Ezh2 has significant and diverse roles during early development, as well as during the establishment of the first differentiated cells, the trophectoderm, and of the pluripotent epiblast cells.

Animals↗
PubMed2002

cis-acting DNA from fission yeast centromeres mediates histone H3 methylation and recruitment of silencing factors and cohesin to an ectopic site.

BACKGROUND: Metazoan centromeres are generally composed of large repetitive DNA structures packaged in heterochromatin. Similarly, fission yeast centromeres contain large inverted repeats and two distinct silenced domains that are both required for centromere function. The central domain is flanked by outer repetitive elements coated in histone H3 methylated on lysine 9 and bound by conserved heterochromatin proteins. This centromeric heterochromatin is required for cohesion between sister centromeres. Defective heterochromatin causes premature sister chromatid separation and chromosome missegregation. The role of cis-acting DNA sequences in the formation of centromeric heterochromatin has not been established. RESULTS: A deletion strategy was used to identify centromeric sequences that allow heterochromatin formation in fission yeast. Fragments from the outer repeats are sufficient to cause silencing of an adjacent gene when inserted at a euchromatic chromosomal locus. This silencing is accompanied by the local de novo methylation of histone H3 on lysine 9, recruitment of known heterochromatin components, Swi6 and Chp1, and the provision of a new strong cohesin binding site. In addition, we demonstrate that the chromodomain of Chp1 binds to MeK9-H3 and that Chp1 itself is required for methylation of histone H3 on lysine 9. CONCLUSIONS: A short sequence, reiterated at fission yeast centromeres, can direct silent chromatin assembly and cohesin recruitment in a dominant manner. The heterochromatin formed at the euchromatic locus is indistinguishable from that found at endogenous centromeres. Recruitment of Rad21-cohesin underscores the link between heterochromatin and chromatid cohesion and indicates that these centromeric elements act independently of kinetochore activity to recruit cohesin.

Binding Sites↗
PubMed2002

Active genes are tri-methylated at K4 of histone H3.

Lysine methylation of histones in vivo occurs in three states: mono-, di- and tri-methyl. Histone H3 has been found to be di-methylated at lysine 4 (K4) in active euchromatic regions but not in silent heterochromatic sites. Here we show that the Saccharomyces cerevisiae Set1 protein can catalyse di- and tri-methylation of K4 and stimulate the activity of many genes. Using antibodies that discriminate between the di- and tri-methylated state of K4 we show that di-methylation occurs at both inactive and active euchromatic genes, whereas tri-methylation is present exclusively at active genes. It is therefore the presence of a tri-methylated K4 that defines an active state of gene expression. These findings establish the concept of methyl status as a determinant for gene activity and thus extend considerably the complexity of histone modifications.

Antibodies↗
PubMed2002

Histone methylation: dynamic or static?

Methylation of histones mediates transcriptional silencing at heterochromatin sites and affects regulated transcription at euchromatic loci. So is the methyl group a permanent mark on histones, or can it be removed by an active process necessary for regulated gene expression?

Amino Acid Sequence↗
PubMed2002

Unsafe SETs: histone lysine methyltransferases and cancer.

Enzymes that covalently modify histones control many cellular processes by affecting gene expression. A new class of these enzymes is the histone lysine methyltransferase family, whose catalytic activity lies within a conserved domain, the SET domain. This article surveys the evidence for a connection between SET-domain-containing proteins and cancer. It proposes that deregulation of SET-domain function has an important role in carcinogenesis.

Amino Acid Sequence↗
PubMed2002

Protein N-methyltransferase assays in the study of gene transcription.

Protein N-methylation has recently emerged as a major mechanism involved in regulating gene transcription and epigenetic inheritance. Transcriptional coactivators and corepressors have both been shown to associate with protein N-methyltransferases. These enzymes methylate arginine or lysine residues within histones as well as other proteins, such as transcription factors. Here, we discuss the recent advances in our understanding of protein methylation and its involvement in gene expression. Protocols are presented for studying transcriptionally relevant protein methylation.

Amino Acid Sequence↗
PubMed2002

Histone methylation defines epigenetic asymmetry in the mouse zygote.

The oocyte cytoplasm regulates and enhances the epigenetic asymmetry between parental genomes and, consequently, functional differences observed between them during development in mammals. Here we demonstrate a preferential interaction of HP1beta with the maternal genome immediately after fertilisation in the mouse zygote, which also shows a high level of lysine 9-methylated histone H3. In contrast, the paternal genome has neither HP1beta binding nor methylated histone H3 at these early stages. Paternal binding of HP1beta is only detected at the pronuclear stage, prior to the appearance of lysine 9-methylated histone H3. The early recruitment of heterochromatic factors specifically to the maternal genome could explain the preferential DNA demethylation of the paternal genome in the zygote.

Animals↗