Methyl-H3K9-binding protein MPP8 mediates E-cadherin gene silencing and promotes tumour cell motility and invasion

ArticleinThe EMBO Journal 29(21):3673-87 · November 2010with23 Reads
DOI: 10.1038/emboj.2010.239 · Source: PubMed
Abstract
H3K9 methylation has been linked to a variety of biological processes including position-effect variegation, heterochromatin formation and transcriptional regulation. To further understand the function of H3K9 methylation, we have identified and characterized MPP8 as a methyl-H3K9-binding protein. MPP8 displays an elevated expression pattern in various human carcinoma cells, whereas knocking-down MPP8 results in the loss of cellular mesenchymal marker as well as the reduction of tumour cell migration and invasiveness, suggesting that MPP8 contributes to tumour progression. Following characterization demonstrates that MPP8 targets the E-cadherin gene promoter and modulates the expression of this key regulator of cell behaviour and tumour progression through its methyl-H3K9 binding. Furthermore, MPP8 interacts with H3K9 methyltransferases GLP and ESET, as well as DNA methyltransferase 3A. MPP8 knockdown decreases DNA methylation on E-cadherin CpG island attended by the loss of DNMT3A localization, indicating MPP8 also directs DNA methylation. Together, our results suggest a model by which MPP8 recognizes methyl-H3K9 marks and directs DNA methylation to repress tumour suppressor gene expression and, in turn, has an important function in epithelial-to-mesenchymal transition and metastasis.
    • "The M phase phosphoprotein 8 (MPP8) was identified as a protein that is highly phosphorylated during M phase [1]. MPP8 possesses a chromodomain in the amino terminal region which has an affinity for trimethylated histone H3 lysine 9 (H3K9me3) residues [5,6]. This chromodomain also binds to dimethylated Dnmt3a (K44me2), a mammalian de novo DNA methyltransferase, and auto-methylated GLP or G9a, both of which are linked with H3K9 dimethylation [2]. "
    [Show abstract] [Hide abstract] ABSTRACT: Epigenetic modifications such as DNA methylation and histone H3 lysine 27 methylation (H3K27me) are repressive marks that silence gene expression. The M phase phosphoprotein (MPP8) associates with proteins involved in both DNA methylation and histone modifications, and therefore, is a potential candidate to mediate crosstalk between repressive epigenetic pathways. Here, by performing immunohistochemical analyses we demonstrate that MPP8 is expressed in the rodent testis, especially in spermatocytes, suggesting a role in spermatogenesis. Interestingly, we found that MPP8 physically interacts with PRC1 (Polycomb Repressive Complex 1) components which are known to possess essential function in testis development by modulating monoubiquitination of Histone H2A (uH2A) and trimethylation of Histone H3 Lysine 27 (H3K27me3) residues. Knockdown analysis of MPP8 in HeLa cells resulted in derepression of a set of genes that are normally expressed in spermatogonia, spermatids and mature sperm, thereby indicating a role for this molecule in silencing testis-related genes in somatic cells. In addition, depletion of MPP8 in murine ES cells specifically induced expression of genes involved in mesoderm differentiation, such as Cdx2 and Brachyury even in the presence of LIF, which implicated that MPP8 might be required to repress differentiation associated genes during early development. Taken together, our results indicate that MPP8 could have a role for silencing genes that are associated with differentiation of the testis and the mesoderm by interacting with epigenetic repressors modules such as the PRC1 complex. Copyright © 2015. Published by Elsevier Inc.
    Full-text · Article · Feb 2015
    • "Notably, a number of paired histone binding domains characterized to engage the chromatin template in a multivalent manner harbor single domain reader functions that are broadly shared among chromatin-associated factors. For instance , the PHD finger of BPTF shares the ability to read H3K4me3 with a growing list of chromatin-associated factors [33,115116117, and the TTD of UHRF1 is one of a host of identified H3K9me3 readers [57, 102,118119120121 . Importantly, in vitro affinity measurements for these interactions are often similar, suggesting the possibility that competition for histone PTMs exists at defined regions of chromatin. "
    [Show abstract] [Hide abstract] ABSTRACT: A major mechanism regulating the accessibility and function of eukaryotic genomes are the covalent modifications to DNA and histone proteins that dependably package our genetic information inside the nucleus of every cell. Formally postulated over a decade ago, it is becoming increasingly clear that post-translational modifications (PTMs) on histones act singly and in combination to form a language or ‘code’ that is read by specialized proteins to facilitate downstream functions in chromatin. Underappreciated at the time was the level of complexity harbored both within histone PTMs and their combinations, as well as within the proteins that read and interpret the language. In addition to histone PTMs, newly-identified DNA modifications that can recruit specific effector proteins has raised further awareness that histone PTMs operate within a broader language of epigenetic modifications to orchestrate the dynamic functions associated with chromatin. Here, we highlight key recent advances in our understanding of the epigenetic language encompassing histone and DNA modifications and foreshadow challenges that lie ahead as we continue our quest to decipher the fundamental mechanisms of chromatin regulation. This article is part of a Special Issue entitled: Molecular mechanisms of histone modification function.
    Full-text · Article · Aug 2014
    • "PcDNA- FLAG-HA-TIF1b and pRL-TK were described previously [9]. pCS2-Myc-Trim28 [25] and pGL3-E-cadherin [26] were the generous gifts from Ryan Potts (UT Southwestern) and Jia Fang (Moffitt Cancer Center), respectively. TGF-b was purchased from R&D Systems (240-B-002). "
    [Show abstract] [Hide abstract] ABSTRACT: In previous work, we demonstrated that transcription factor Trim28 (Tripartite motif containing 28) plays a tumor-suppressor role in early-staged adenocarcinoma of the lung due to its ability to restrain transcription of cell cycle-regulating genes. Herein we examine Trim28's role in the epithelial-to-mesenchymal transition (EMT) which is strongly implicated in cancer metastasis. We found that Trim28 plays a role in TGF-β-induced EMT in non-small cell lung cancer cells. Silencing Trim28 with inhibitory RNAs alters the expression of numerous EMT markers, such as E-cadherin and N-cadherin, whereas overexpression of Trim28 has an opposite effect. Trim28 expression is induced following TGF-β treatment at both protein and mRNA levels. Trim28 deficiency impairs TGF-β-induced EMT and decreases cell migration and invasion. Finally, we demonstrate that the expression of Trim28 affects the acetylation and methylation of histones on E-cadherin and N-cadherin promoters. These results suggest that Trim28 contributes to EMT and might be important for tumor metastasis in lung cancer. Taken together with our previous work these results suggest a model in which Trim28 is a tumor suppressor early in the transformation process in lung cancer, but in later stages it functions as an oncogene.
    Full-text · Article · Jul 2014
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