Histone H3K27 methyltransferase Ezh2 represses Wnt genes to facilitate adipogenesis

Nuclear Receptor Biology Section, Clinical Endocrinology Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.67). 04/2010; 107(16):7317-22. DOI: 10.1073/pnas.1000031107
Source: PubMed


Wnt/beta-catenin signaling inhibits adipogenesis. Genome-wide profiling studies have revealed the enrichment of histone H3K27 methyltransferase Ezh2 on Wnt genes. However, the functional significance of such a direct link between the two types of developmental regulators in mammalian cells, and the role of Ezh2 in adipogenesis, remain unclear. Here we show Ezh2 and its H3K27 methyltransferase activity are required for adipogenesis. Ezh2 directly represses Wnt1, -6, -10a, and -10b genes in preadipocytes and during adipogenesis. Deletion of Ezh2 eliminates H3K27me3 on Wnt promoters and derepresses Wnt expression, which leads to activation of Wnt/beta-catenin signaling and inhibition of adipogenesis. Ectopic expression of the wild-type (WT) Ezh2, but not the enzymatically inactive F667I mutant, prevents the loss of H3K27me3 and the defects in adipogenesis in Ezh2(-/-) preadipocytes. The adipogenesis defects in Ezh2(-/-) cells can be rescued by expression of adipogenic transcription factors PPARgamma, C/EBPalpha, or inhibitors of Wnt/beta-catenin signaling. Interestingly, Ezh2(-/-) cells show marked increase of H3K27 acetylation globally as well as on Wnt promoters. These results indicate that H3K27 methyltransferase Ezh2 directly represses Wnt genes to facilitate adipogenesis and suggest that acetylation and trimethylation on H3K27 play opposing roles in regulating Wnt expression.

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Available from: I-hsin Su, Mar 11, 2015
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    • "Deletion of Ezh2 eliminates H3K27me3 on Wnt promoters and derepresses Wnt expression, which leads to activation of Wnt/b-catenin signaling and inhibition of adipogenesis. Ectopic expression of the WT Ezh2, but not the enzymatically inactive F667I mutant, prevents the loss of H3K27me3 and the defective adipogenesis in Ezh2 2/2 preadipocytes (Wang et al., 2010). Moreover, the involvement of the polycomb family protein in adipogenic differentiation seems also supported by data reporting histone H3 modifications associated with differentiation and long-term culture of mesenchymal adipose stem cells. "
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    ABSTRACT: We have recently generated knockout mice for the Cbx7 gene, coding for a polycomb group protein that is downregulated in human malignant neoplasias. These mice develop liver and lung adenomas and carcinomas, which confirms a tumour suppressor role for CBX7. The CBX7 ability to downregulate CCNE1 expression likely accounts for the phenotype of the Cbx7-null mice. Unexpectedly, Cbx7-knockout mice had a higher fat tissue mass than wild-type, suggesting a role of CBX7 in adipogenesis. Consistently, we demonstrate that Cbx7-null mouse embryonic fibroblasts go towards adipocyte differentiation more efficiently than their wild-type counterparts, and this effect is Cbx7 dose-dependent. Similar results were obtained when Cbx7-null embryonic stem cells were induced to differentiate into adipocytes. Conversely, mouse embryonic fibroblasts and human adipose-derived stem cells overexpressing CBX7 show an opposite behaviour. These findings support a negative role of CBX7 in the control of adipocyte cell growth and differentiation.
    Biology Open 09/2014; 3(9). DOI:10.1242/bio.20147872 · 2.42 Impact Factor
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    • "In the presence of EA, the inhibited CARM1 activity by EA results in the suppression of H3R17 methylation, which in turn abolishes H3K9 acetylation and HDAC9 dissociation, and ultimately represses adipogenesis. Extensive research from several groups has identified that histone-modifying enzymes play pivotal roles in adipocyte development: (a) deletion of histone methyl-transferase enhancer of zeste homolog (Ezh2) abolished trimethylation on H3K27 of Wnt promoter region, resulting in constitutive activation of Wnt signaling and transcriptional inhibition of adipogenesis [24]; (b) silencing of PRMT5 repressed adipogenic gene expression, which was reversed by PRMT5 overexpression [26]; (c) histone methyltransferase G9a seemed to play dual roles for turning on or off adipogenic signaling based on its methylation sites by serving as a coactivator or co-repressor [49]; (d) Class II HDACs have been reported to control PPARγ signaling [50]. Among the Class II HDACs, HDAC9 has been identified as a unique transcriptional co-repressor on C/EBPα promoter [28]; and (e) mice born with the deletion of CARM1 lacked in fat pad development [51] [52] identifying the adipose-specific role of CARM1 as a coactivator for PPARγ [25]. "
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    ABSTRACT: Chromatin remodeling is a key mechanism in adipocyte differentiation. However, it is unknown whether dietary polyphenols are epigenetic effectors for adiposity control. Ellagic acid (EA) is a naturally occurring polyphenol in numerous fruits and vegetables. Recently, EA-containing foods have been reported to reduce adiposity. In the present study, we sought to determine whether EA inhibits adipogenesis by modifying chromatin remodeling in human adipogenic stem cells (hASCs). qPCR microarray of chromatin modification enzymes revealed that 10 μmol/L of EA significantly inhibits histone deacetylase (HDAC) 9 down-regulation. In addition, EA was associated with up-regulation of HDAC activity and a marked reduction of histone acetylation levels. However, chemical inhibition of HDAC activity or depletion of HDAC9 by siRNA were not sufficient to reverse the anti-adipogenic effects of EA. Intriguingly, EA treatment was also associated with reduced histone 3 arginine 17 methylation levels (H3R17me2), implying the inhibitory role of EA in coactivator-associated arginine methyltransferase 1 (CARM) 1 activity during adipogenesis. Boosting CARM1 activity by delivering cell-penetrating peptides of CARM1 (CPP-CARM1) not only recovered H3R17me2, but also restored adipogenesis evidenced by H3 acetylation at lysine 9 (H3K9Ac), HDAC9 down-regulation, PPARγ expression, and triglyceride accumulation. Taken together, our data suggest that reduced CARM1 activity by EA results in a decrease of H3R17me2 levels, which may interrupt consecutive histone remodeling steps for adipocyte differentiation including histone acetylation and HDAC9 dissociation from chromatin. Our work provides the mechanistic insights into how EA, a polyphenol ubiquitously found in fruits and vegetables, attenuates human adipocyte differentiation by altering chromatin remodeling.
    The Journal of nutritional biochemistry 09/2014; 25(9). DOI:10.1016/j.jnutbio.2014.04.008 · 3.79 Impact Factor
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    • "In particular, EZH2, the catalytic subunit of Polycomb Repressive Complex 2 (PRC2), induces histone methyltransferase activity primarily by trimethylating histone H3 at lysine 27 (H3K27me3), hence mediating gene silencing. PcGs are crucial in the chromatin control of stem cell self-renewal and differentiation [1]–[7]. They also play a crucial role in malignant progression and are implicated in cancer metastasis [8]. "
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    ABSTRACT: Objective Growing evidences indicate that the histone methyltransferase EZH2 (enhancer of zeste homolog 2) may be an appropriate therapeutic target in some tumors. Indeed, a high expression of EZH2 is correlated with poor prognosis and metastasis in many cancers. In addition, 3-Deazaneplanocin A (DZNep), an S-adenosyl-L homocysteine hydrolase inhibitor which induces EZH2 protein depletion, leads to cell death in several cancers and tumors. The aim of this study was to determine whether an epigenetic therapy targeting EZH2 with DZNep may be also efficient to treat chondrosarcomas. Methods EZH2 expression was determined by immunohistochemistry and western-blot. Chondrosarcoma cell line CH2879 was cultured in the presence of DZNep, and its growth and survival were evaluated by counting adherent cells periodically. Apoptosis was assayed by cell cycle analysis, Apo2.7 expression using flow cytometry, and by PARP cleavage using western-blot. Cell migration was assessed by wound healing assay. Results Chondrosarcomas (at least with high grade) highly express EZH2, at contrary to enchondromas or chondrocytes. In vitro, DZNep inhibits EZH2 protein expression, and subsequently reduces the trimethylation of lysine 27 on histone H3 (H3K27me3). Interestingly, DZNep induces cell death of chondrosarcoma cell lines by apoptosis, while it slightly reduces growth of normal chondrocytes. In addition, DZNep reduces cell migration. Conclusion These results indicate that an epigenetic therapy that pharmacologically targets EZH2 via DZNep may constitute a novel approach to treat chondrosarcomas.
    PLoS ONE 07/2014; 9(5):e98176. DOI:10.1371/journal.pone.0098176 · 3.23 Impact Factor
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