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

Department of Molecular Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL 33612, USA.
The EMBO Journal (Impact Factor: 10.43). 11/2010; 29(21):3673-87. DOI: 10.1038/emboj.2010.239
Source: PubMed


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.

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    • "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]. "
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    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.
    Biochemical and Biophysical Research Communications 02/2015; 458(3). DOI:10.1016/j.bbrc.2015.01.122 · 2.30 Impact Factor
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    • "PcDNA-FLAG-HA-TIF1β 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-β was purchased from R&D Systems (240-B-002). "
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    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.
    PLoS ONE 07/2014; 9(7):e101040. DOI:10.1371/journal.pone.0101040 · 3.23 Impact Factor
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    • "Another member, MPP8 (M-phase phosphoprotein 8) recognizes H3K9 methylation on chromatin and interacts with HMTases GLP and ESET as well as the DNA methyltransferase DNMT3A. MPP8 in turn functions to repress CDH1 expression thereby promoting EMT [82]. "
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    ABSTRACT: Tumor metastasis is the major cause of mortality and morbidity in most solid cancers. A growing body of evidence suggests that the epithelial-to-mesenchymal transition (EMT) plays a central role during tumor metastasis and frequently imparts a stem cell-like phenotype and therapeutic resistance to tumor cells. The induction of EMT is accompanied by a dynamic reprogramming of the epigenome involving changes in DNA methylation and several post-translational histone modifications. These changes in turn promote the expression of mesenchymal genes or repress those associated with an epithelial phenotype. Importantly, in order for metastatic colonization and the formation of macrometastases to occur, tumor cells frequently undergo a reversal of EMT referred to as the mesenchymal-to-epithelial transition (MET). Thus, a high degree of epigenetic plasticity is required in order to induce and reverse EMT during tumor progression. In this review, we describe various epigenetic regulatory mechanisms employed by tumor cells during EMT and elaborate on the importance of the histone code in controlling both the expression and activity of EMT-associated transcription factors. We propose that a more thorough understanding of the epigenetic mechanisms controlling EMT may provide new opportunities which may be harnessed for improved and individualized cancer therapy based on defined molecular mechanisms.
    Oncotarget 04/2014; 5(8):2016-29. DOI:10.18632/oncotarget.1875 · 6.36 Impact Factor
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