Project description:Previously, we suggested a cytosolic role for the histone-methyltransferase Ezh2 in regulating lymphocyte activation, but molecular mechanisms underpinning this extra-nuclear function remained unclear. Here we show that Ezh2 regulates integrin-signaling and adhesion dynamics of neutrophils and dendritic cells. Ezh2 deficiency impaired integrin-dependent transendothelial migration of innate leukocytes and restricted disease progression in an animal model of multiple sclerosis. Direct methylation of talin, a key regulatory molecule in cell migration, by Ezh2 disrupted talin binding to F-actin and thereby promoted adhesion structure turnover. This regulatory effect was abolished by targeted disruption of Ezh2 interactions with Vav1. Our studies reveal a novel extra-nuclear function for Ezh2 in regulating adhesion dynamics with implications for leukocyte migration, immune responses and potentially pathogenic processes. Control and Ezh2-deficient bone marrow derived immature and mature dendritic cells were analyzed in triplicates
Project description:Previously, we suggested a cytosolic role for the histone-methyltransferase Ezh2 in regulating lymphocyte activation, but molecular mechanisms underpinning this extra-nuclear function remained unclear. Here we show that Ezh2 regulates integrin-signaling and adhesion dynamics of neutrophils and dendritic cells. Ezh2 deficiency impaired integrin-dependent transendothelial migration of innate leukocytes and restricted disease progression in an animal model of multiple sclerosis. Direct methylation of talin, a key regulatory molecule in cell migration, by Ezh2 disrupted talin binding to F-actin and thereby promoted adhesion structure turnover. This regulatory effect was abolished by targeted disruption of Ezh2 interactions with Vav1. Our studies reveal a novel extra-nuclear function for Ezh2 in regulating adhesion dynamics with implications for leukocyte migration, immune responses and potentially pathogenic processes.
Project description:SLK controls the cytoskeleton, cell adhesion and migration. Analysis of a protein kinase phosphorylation site dataset showed that podocyte adhesion proteins – paxillin, vinculin and talin-1 may be potential SLK substrates. The project examines if these adhesion proteins are substrates of SLK.
Project description:This logical network model integrate signalling, transcriptional and epigenetic regulatory mechanisms underlying the the Acute Promyelocytic Leukaemia cell responses to RA treatment depending on their genetic background. The explicit inclusion of the histone methyltransferase EZH2 allowed us to assess its role in the maintenance of the resistant phenotype, distinguishing between its canonical and non-canonical activities. Ultimately, this model offers a solid basis to assess the roles of novel regulatory mechanisms, as well as to explore novel therapeutical approaches in silico.
Project description:A cytosolic role for EZH2 in regulating cell signaling via interaction with the VAV family of proteins has been reported by us previously. However, it is unclear whether EZH2 interactions with VAV are critical for tumorigenesis. Here, we show that cytosolic EZH2 exhibits greater transforming/metastatic capacity than wild-type EZH2 and that targeted disruption of the EZH2-VAV interaction abolishes EZH2-promoted tumorigenesis. We also found that interaction of cytosolic EZH2 with VAV is critical for EZH2-mediated talin methylation and subsequent STAT3 activation. Both cytosolic EZH2 and a methyl-mimicking talin mutant substantially promoted STAT3 activation and tumor growth. We therefore propose that the VAV-dependent cytosolic function of EZH2 may be a critical step in the initiation of cellular transformation, preceding the well-established function of EZH2 in epigenetic silencing of tumor suppressors. Thus, disrupting EZH2-VAV interaction could be an alternative intervention strategy for treatment of cancers associated with EZH2 overexpression.
Project description:The enhancer of zeste homolog 2 (EZH2) oncoprotein is a histone methyltransferase that functions canonically as a catalytic subunit of the polycomb repressive complex 2 (PRC2) to tri-methylate histone H3 at Lys 27 (H3K27me3). Although targeting EZH2 methyltransferase is a promising therapeutic strategy against cancer, methyltransferase-independent oncogenic functions of EZH2 are described. Moreover, pharmacological EZH2 methyltransferase inhibition was only variably effective in pre-clinical and clinical studies, suggesting that targeting EZH2 methyltransferase alone may be insufficient. Here, we demonstrate a non-canonical mechanism of EZH2’s oncogenic activity characterized by interactions with inosine monophosphate dehydrogenase 2 (IMPDH2) and downstream promotion of guanosine-5'-triphosphate (GTP) production. EZH2-IMPDH2 interactions identified by Liquid Chromatography-Mass Spectrometry (LC-MS) of EZH2 immunoprecipitates from melanoma cells were verified to occur between the N-terminal EED-binding domain of cytosolic EZH2 and the CBS domain of IMPDH2 in a methyltransfersase-independent manner. EZH2 silencing reduced cellular GTP, ribosome biogenesis, RhoA-mediated actomyosin contractility and melanoma cell proliferation and invasion by impeding the activity of IMPDH2. Guanosine, which replenishes GTP, reversed these effects and thereby promoted invasive and clonogenic cell states even in EZH2 silenced cells. IMPDH2 silencing antagonized the proliferative and invasive effects of EZH2, also in a guanosine-reversible manner. In human melanomas, high cytosolic EZH2 and IMPDH2 expression were associated with nucleolar enlargement, a marker of ribosome biogenesis. EZH2-IMPDH2 complexes were also observed in a range of cancers in which Sappanone A (SA), which inhibits EZH2-IMPDH2 interactions, was anti-tumorigenic, although notably non-toxic in normal cells. These findings illuminate a previously unrecognized, non-canonical, methyltransferase-independent, and GTP-dependent mechanism by which EZH2 regulates tumorigenicity in melanoma and other cancers, opening new avenues for development of anti-EZH2 therapeutics.
Project description:Abnormalities of chromosome 7q are common in myeloid malignancies. Agilent CGH arrays targeted to 7q and Affymetrix SNP 6.0 arrays were used to characterise 7q aUPD and deletions. Sample #017 in this data series showed a microdeletion encompassing EZH2. Screening of a total of 614 cases with myeloid disorders revealed 49 monoallelic or biallelic EZH2 mutations in 42 individuals, most commonly myelodysplastic/myeloproliferative neoplasms (27/219; 12%) and myelofibrosis (4/30; 13%). EZH2 encodes the catalytic subunit of the Polycomb repressive complex 2 (PRC2), the highly conserved histone H3 lysine 27 methyltransferase that influences stem cell renewal by epigenetic repression of genes involved in cell fate decisions. EZH2 has oncogenic activity and its overexpression has been causally linked to differentiation blocks in epithelial tumors. Unexpectedly, the mutations we identified resulted in premature chain termination or direct abrogation of histone methyltransferase activity, suggesting that EZH2 acts as a tumor suppressor for myeloid malignancies. High density CGH array analysis of 7q and the TET2 region in 8 atypical myeloproliferative neoplasms
Project description:This SuperSeries is composed of the following subset Series: GSE41651: Characterization of the EZH2-MMSET histone methyltransferase regulatory axis in cancer [expression] GSE41652: Characterization of the EZH2-MMSET histone methyltransferase regulatory axis in cancer [ChIP-seq] Refer to individual Series
Project description:Inhibition of H3K27 methyltransferase EZH2 enhances osteogenic commitment of human mesenchymal progenitors and Ezh2 inactivation in mouse calvarial cells induces a post-proliferative state concomitant with increased production of a bone-related mineralizing extra-cellular matrix.