Puto LA, Reed JC.. Daxx represses RelB target promoters via DNA methyltransferase recruitment and DNA hypermethylation. Genes Dev 22: 998-1010

Program in Apoptosis and Cell Death Research, Burnham Institute for Medical Research, La Jolla, California 92037, USA.
Genes & Development (Impact Factor: 10.8). 05/2008; 22(8):998-1010. DOI: 10.1101/gad.1632208
Source: PubMed


The apoptosis-modulating protein Daxx functions as a transcriptional repressor that binds to and suppresses the activity of nuclear factor-kappaB member RelB, among other transcription factors. The mechanism by which Daxx represses RelB target genes remains elusive. In this report, we demonstrate that Daxx controls epigenetic silencing of RelB target genes by DNA methylation. Daxx potently represses the RelB target genes dapk1, dapk3, c-flip, and birc3 (ciap2) at both the mRNA and protein levels. Recruitment of Daxx to target gene promoters, and its ability to repress them, is RelB-dependent, as shown by experiments using relB(-/-) cells. Importantly, methylation of target promoters is decreased in daxx(-/-) cells compared with daxx(+/+) cells, and stable transfection of daxx(-/-) cells with Daxx restores DNA methylation. Furthermore, Daxx recruits DNA methyl transferase 1 (Dnmt1) to target promoters, resulting in synergistic repression. The observation that Daxx functions to target DNA methyltransferases onto RelB target sites in the genome provides a rare example of a gene-specific mechanism for epigenetic silencing. Given the documented role of several of the RelB-regulated genes in diseases, particularly cancer, the findings have implications for developing therapeutic strategies based on epigenetic-modifying drugs.

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    • "Cold Spring Harbor Laboratory Press on October 16, 2015 -Published by Downloaded from recruitment (Puto and Reed 2008 "
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    ABSTRACT: Gene expression regulation is gated by promoter methylation states modulating transcription factor binding. The known DNA methylation/unmethylation mechanisms are sequence unspecific, but different cells with the same genome have different methylomes. Thus, additional processes bringing specificity to the methylation/unmethylation mechanisms are required. Searching for such processes, we demonstrated that CpG methylation states are influenced by the sequence context surrounding the CpGs. We used such a property to develop a CpG methylation motif discovery algorithm. The newly discovered motifs reveal "methylation/unmethylation factors" that could recruit the "methylation/unmethylation machinery" to the loci specified by the motifs. Our methylation motif discovery algorithm provides a synergistic approach to the differently methylated region algorithms. Since our algorithm searches for commonly methylated regions inside the same sample, it requires only a single sample to operate. The motifs that were found discriminate between hypomethylated and hypermethylated regions. The hypomethylation-associated motifs have a high CG content, their targets appear in conserved regions near transcription start sites, they tend to co-occur within transcription factor binding sites, they are involved in breaking the H3K4me3/H3K27me3 bivalent balance, and they transit the enhancers from repressive H3K27me3 to active H3K27ac during ES cell differentiation. The new methylation motifs characterize the pluripotent state shared between ES and iPS cells. Additionally, we found a collection of motifs associated with the somatic memory inherited by the iPS from the initial fibroblast cells, thus revealing the existence of epigenetic somatic memory on a fine methylation scale.
    Genome Research 10/2013; 23(12). DOI:10.1101/gr.155960.113 · 14.63 Impact Factor
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    • "Together, these studies suggest that DAXX-mediated loading of H3.3 at regulatory regions may affect transcription. One could argue that DAXX ability to regulate transcription could be H3.3-independent, for instance via its interaction with HDAC- II (Hollenbach et al., 2002), CBP (Kuo et al., 2005), or Dnmt1 (Puto and Reed, 2008; Zhang et al., 2013). However, DAXX loss fails to promote any significant changes in histone acetylation or DNA methylation at the BDNF Exon IV promoter (Michod et al., 2012). "
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    ABSTRACT: The promyelocytic leukemia (PML) protein has been implicated in regulation of multiple key cellular functions, from transcription to calcium homeostasis. PML pleiotropic role is in part related to its ability to localize to both the nucleus and cytoplasm. In the nucleus, PML is known to regulate gene transcription, a role linked to its ability to associate with transcription factors as well as chromatin-remodelers. A new twist came from the discovery that the PML-interacting protein death-associated protein 6 (DAXX) acts as chaperone for the histone H3.3 variant. H3.3 is found enriched at active genes, centromeric heterochromatin, and telomeres, and has been proposed to act as important carrier of epigenetic information. Our recent work has implicated DAXX in regulation of H3.3 loading and transcription in the central nervous system (CNS). Remarkably, driver mutations in H3.3 and/or its loading machinery have been identified in brain cancer, thus suggesting a role for altered H3.3 function/deposition in CNS tumorigenesis. Aberrant H3.3 deposition may also play a role in leukemia pathogenesis, given DAXX role in PML-RARα-driven transformation and the identification of a DAXX missense mutation in acute myeloid leukemia. This review aims to critically discuss the existing literature and propose new avenues for investigation.
    Frontiers in Oncology 06/2013; 3:152. DOI:10.3389/fonc.2013.00152
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    • "The effect on transcriptional regulation could be independent of DAXX chaperone function. In this respect, DAXX has been reported to regulate histone acetylation as well as DNA methylation (Kuo et al., 2005; Puto and Reed, 2008). However, no changes in H3 and H4 acetylation or CpG island methylation were observed in DAXX-deficient neurons. "
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    ABSTRACT: Activity-dependent modifications of chromatin are believed to contribute to dramatic changes in neuronal circuitry. The mechanisms underlying these modifications are not fully understood. The histone variant H3.3 is incorporated in a replication-independent manner into different regions of the genome, including gene regulatory elements. It is presently unknown whether H3.3 deposition is involved in neuronal activity-dependent events. Here, we analyze the role of the histone chaperone DAXX in the regulation of H3.3 incorporation at activity-dependent gene loci. DAXX is found to be associated with regulatory regions of selected activity-regulated genes, where it promotes H3.3 loading upon membrane depolarization. DAXX loss not only affects H3.3 deposition but also impairs transcriptional induction of these genes. Calcineurin-mediated dephosphorylation of DAXX is a key molecular switch controlling its function upon neuronal activation. Overall, these findings implicate the H3.3 chaperone DAXX in the regulation of activity-dependent events, thus revealing a new mechanism underlying epigenetic modifications in neurons.
    Neuron 04/2012; 74(1):122-35. DOI:10.1016/j.neuron.2012.02.021 · 15.05 Impact Factor
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