po 178 wdr5 promotes metastasis dissemination in breast cancer

Introduction The core subunit of the COMPASS-like complex, WD Repeat Domain 5 (WDR5) has a prominent role in cell self-renewal, reprogramming and Epithelial-to-Mesenchymal transition (EMT) in different tumour types. We have identified WDR5 as an epigenetic target in in vivo and in vitro shRNA screenings performed in MCF10DCIS.com (from now MCF10DCIS) breast cancer (BC) cells. Here, we show that WDR5 can regulate metastasis dissemination in BC by stimulating TGFB-induced EMT. Material and methods MCF10DCIS and MDAMB231 cells and six metastatic PDXs were used for in vivo and in vitro studies. Cells were transduced to silence WDR5 (shWDR5) or a neutral control (shLuc). Transcriptomic profiles were evaluated by RNA-seq in shLuc and shWDR5 PDXs and MCF10DCIS cells. Differentially expressed genes (DEGs) were identified using Log2FC>|0.6| and FDR t test for in vivo and in vitro experiments. Results and discussions WDR5 interference significantly inhibited tumour growth and in vitro migration of PDXs and MCF10DCIS cells and reduced metastatic burden of MDAMB231 cells in vivo . These data suggested that WDR5 may be involved in cell motility, promoting invasiveness and metastasis. Gene Ontology performed on DEGs highlighted an enrichment of functions related to EMT and TGFB signalling. Indeed, protein and mRNA levels of a series of gene implicated in EMT (e.g. SNAI1, TWIST1, CDH2, SNAI2, ZEB1) were strongly reduced in shWDR5 PDXs and MCF10DCIS cells, thus suggesting a regulatory role of WDR5 in EMT. H3K4me3 levels were globally affected and concordantly reduced at TSS level of SNAI1 and TWIST1 genes in shWDR5 MCF10DCIS cells, confirming that WDR5 can transcriptionally regulate EMT in BC. Moreover, the induction of EMT by TGFB treatment can be abrogated in WDR5-deficient cells, suggesting that the EMT induced by TGFB is WDR5-dependent. Conclusion Our evidences support a model in which WDR5 is responsible for mediating the epithelial-to-mesenchymal transition and metastasis dissemination in BC. WDR5 is essential for TGFB response and its inhibition may be a successful approach to prevent progression of metastatic BC

EMF1 and PRC2 Cooperate to Repress Key Regulators of Arabidopsis Development

EMBRYONIC FLOWER1 (EMF1) is a plant-specific gene crucial to Arabidopsis vegetative development. Loss of function mutants in the EMF1 gene mimic the phenotype caused by mutations in Polycomb Group protein (PcG) genes, which encode epigenetic repressors that regulate many aspects of eukaryotic development. In Arabidopsis, Polycomb Repressor Complex 2 (PRC2), made of PcG proteins, catalyzes trimethylation of lysine 27 on histone H3 (H3K27me3) and PRC1-like proteins catalyze H2AK119 ubiquitination. Despite functional similarity to PcG proteins, EMF1 lacks sequence homology with known PcG proteins; thus, its role in the PcG mechanism is unclear. To study the EMF1 functions and its mechanism of action, we performed genome-wide mapping of EMF1 binding and H3K27me3 modification sites in Arabidopsis seedlings. The EMF1 binding pattern is similar to that of H3K27me3 modification on the chromosomal and genic level. ChIPOTLe peak finding and clustering analyses both show that the highly trimethylated genes also have high enrichment levels of EMF1 binding, termed EMF1_K27 genes. EMF1 interacts with regulatory genes, which are silenced to allow vegetative growth, and with genes specifying cell fates during growth and differentiation. H3K27me3 marks not only these genes but also some genes that are involved in endosperm development and maternal effects. Transcriptome analysis, coupled with the H3K27me3 pattern, of EMF1_K27 genes in emf1 and PRC2 mutants showed that EMF1 represses gene activities via diverse mechanisms and plays a novel role in the PcG mechanism

Epigenetic Analysis of KSHV Latent and Lytic Genomes

Epigenetic modifications of the herpesviral genome play a key role in the transcriptional control of latent and lytic genes during a productive viral lifecycle. In this study, we describe for the first time a comprehensive genome-wide ChIP-on-Chip analysis of the chromatin associated with the Kaposi's sarcoma-associated herpesvirus (KSHV) genome during latency and lytic reactivation. Depending on the gene expression class, different combinations of activating [acetylated H3 (AcH3) and H3K4me3] and repressive [H3K9me3 and H3K27me3] histone modifications are associated with the viral latent genome, which changes upon reactivation in a manner that is correlated with their expression. Specifically, both the activating marks co-localize on the KSHV latent genome, as do the repressive marks. However, the activating and repressive histone modifications are mutually exclusive of each other on the bulk of the latent KSHV genome. The genomic region encoding the IE genes ORF50 and ORF48 possesses the features of a bivalent chromatin structure characterized by the concomitant presence of the activating H3K4me3 and the repressive H3K27me3 marks during latency, which rapidly changes upon reactivation with increasing AcH3 and H3K4me3 marks and decreasing H3K27me3. Furthermore, EZH2, the H3K27me3 histone methyltransferase of the Polycomb group proteins (PcG), colocalizes with the H3K27me3 mark on the entire KSHV genome during latency, whereas RTA-mediated reactivation induces EZH2 dissociation from the genomic regions encoding IE and E genes concurrent with decreasing H3K27me3 level and increasing IE/E lytic gene expression. Moreover, either the inhibition of EZH2 expression by a small molecule inhibitor DZNep and RNAi knockdown, or the expression of H3K27me3-specific histone demethylases apparently induced the KSHV lytic gene expression cascade. These data indicate that histone modifications associated with the KSHV latent genome are involved in the regulation of latency and ultimately in the control of the temporal and sequential expression of the lytic gene cascade. In addition, the PcG proteins play a critical role in the control of KSHV latency by maintaining a reversible heterochromatin on the KSHV lytic genes. Thus, the regulation of the spatial and temporal association of the PcG proteins with the KSHV genome may be crucial for propagating the KSHV lifecycle