WTX interacts with the transcriptional regulator TRIM28 to mediate cellular differentiation
Ontology highlight
ABSTRACT: WTX encodes a tumor suppressor implicated in Wilms tumor and in mesenchymal differentiation, with distinct functions in the cytoplasm, at the plasma membrane and in the nucleus. Here we report that the transcriptional corepressor TRIM28 is the major binding partner for nuclear WTX. The WTX-TRIM28 interaction supports chromatin binding by TRIM28, enhancing transcriptional silencing of some TRIM28 target sequences. In mouse ES cells, where TRIM28-mediated silencing of repetitive sequences is best characterized, Wtx knockdown similarly derepresses endogenous retroviruses and LINE elements. We performed digital gene expression (DGE) profiling using Helicos RNA sequencing. Helicos sequencing does not involve an amplification step, hence it has less bias, especially in sequencing of repetitive elements. We sequenced RNA extracted from mouse ESCs harboring GFP, Wtx or Trim28 hairpins. The resulting sequence reads were aligned with the RefSeq database as well as Repbase, which is a database for the repetitive sequences.
Project description:Aberrant transcription of the HSATII pericentromeric satellite repeat is present in a wide variety of epithelial cancers. We observed that HSATII expression is induced in colon cancer cells cultured as xenografts or under non-adherent conditions in vitro, but it is rapidly lost in standard 2D cultures. Unexpectedly, physiological induction of endogenous HSATII RNA, as well as introduction of synthetic HSATII transcripts, generate complementary DNA intermediates in the form of DNA:RNA hybrids. Single molecule sequencing of tumor xenografts shows that HSATII RNA-derived DNA (rdDNA) molecules are stably reincorporated within pericentromeric loci, leading to progressive expansion of these regions We analyzed the dynamics of HSATII RNA and DNA level changes using single molecule sequencing (Helicos/SeqLL) in SW620 colon cancer cells transitioned from 2D in vitro culture conditions to growth as mouse xenografts and vice versa.
Project description:This SuperSeries is composed of the following subset Series: GSE40171: RNA sequencing of circulating tumour cells implicates WNT signaling in pancreatic cancer metastasis (mouse data) GSE40174: RNA sequencing of circulating tumour cells implicates WNT signaling in pancreatic cancer metastasis (human data) Refer to individual Series
Project description:Melanoma is an invasive malignancy with a high frequency of blood-borne metastases, but circulating tumor cells (CTCs) have not been readily isolated. We adapted microfluidic CTC capture to a tamoxifen-driven B-RAF/PTEN mouse melanoma model. CTCs were detected in all tumor-bearing mice, rapidly declining after B-RAF inhibitor treatment. CTCs were shed early from localized tumors and a short course of B-RAF inhibition following surgical resection was sufficient to dramatically suppress distant metastases. The large number of CTCs in melanoma-bearing mice enabled comparison of RNA sequencing profiles with the matched primary tumor. A mouse melanoma CTC-derived signature correlated with invasiveness and cellular motility in human melanoma. In patients with metastatic melanoma, CTCs were detected in smaller numbers in patients with metastatic melanoma and declined with successful B-RAF targeted therapy. Together, the capture of CTCs and their molecular characterization provide insight into the hematogenous spread of melanoma. We adapted a microfluidic platform, the HbCTC-Chip (Stott et al., 2010, Pubmed ID: 20930119), to capture melanoma CTCs derived from mouse tumors, using panels of antibodies against melanoma-specific cell surface markers, followed by staining for melanoma antigens and optimized on-chip fluorescent imaging. We used a tamoxifen inducible BRAF(CA/+)/PTEN(flox/flox) melanoma mouse model (Dankort et al., 2009, Pubmed ID: 19282848) derived from a C57BL/6 background. Such mice received focal subcutaneous injection of tamoxifen (Sigma) (50ul at 5mg/ml in 50% EtOH suspension) at the left flank at 6-7 weeks after birth. Blood samples were collected from five mice with high tumor burden following tamoxifen injection. Blood from each mouse was split and processed through the CTC-chips functionalized with anti-CSPG4/MCAM antibody and control IgGs, respectively. Matched primary (from the tamoxifen injection site) and metastatic (from upper or lower back) tumors were harvested from the same mouse and immediately flash-frozen in liquid nitrogen. RNA extraction, single molecular sequencing and determination of Digital Gene Expression was as in Yu et al., 2012 (Pubmed ID: 22763454). One of the five mice yielded no CTC or IgG data. In addition, skin was taken from a sixth mouse, which was a complete wild type C57BL/6 mouse (without the BRAF/PTEN transgenes).The skin was taken after euthanasia of the animal and was processed as the tissue from the matched primary and metastatic tumors.
Project description:Circulating tumour cells (CTCs) shed into blood from primary cancers include putative precursors that initiate distal metastases. While these cells are extraordinarily rare, they may identify cellular pathways contributing to the blood-borne dissemination of cancer. Here, we adapted a microfluidic device for efficient capture of CTCs from an endogenous mouse pancreatic cancer model and subjected CTCs to single-molecule RNA sequencing, identifying Wnt2 as enriched in CTCs. Expression of Wnt2 in pancreatic cancer cells suppresses anoikis, enhances anchorage-independent sphere formation, and increases metastatic propensity in vivo. The effect of Wnt2 is correlated with fibronectin upregulation, and it is mediated in part through non-canonical Wnt signaling and suppressed by inhibition of the Map3k7 (Tak1) kinase, an integrator of Wnt, BMP and TGF-beta signaling. In humans, formation of non-adherent tumour spheres by pancreatic cancer cells is associated with upregulation of multiple Wnt genes, and pancreatic CTCs revealed significant enrichment for non-canonical Wnt signaling in 5 of 11 cases. Thus, molecular analysis of CTCs may identify novel therapeutic targets to prevent the distal spread of cancer. Expression profiling of primary tumor, circulating tumor cells and ascites in a mouse model of pancreatic cancer suggested WNT signaling plays a role in pancreatic cancer metastasis. Induction of Wnt2 signaling in mouse pancreatic NB508 cells supported the hypothesis.
Project description:Circulating tumour cells (CTCs) shed into blood from primary cancers include putative precursors that initiate distal metastases. While these cells are extraordinarily rare, they may identify cellular pathways contributing to the blood-borne dissemination of cancer. Here, we adapted a microfluidic device for efficient capture of CTCs from an endogenous mouse pancreatic cancer model and subjected CTCs to single-molecule RNA sequencing, identifying Wnt2 as enriched in CTCs. Expression of Wnt2 in pancreatic cancer cells suppresses anoikis, enhances anchorage-independent sphere formation, and increases metastatic propensity in vivo. The effect of Wnt2 is correlated with fibronectin upregulation, and it is mediated in part through non-canonical Wnt signaling and suppressed by inhibition of the Map3k7 (Tak1) kinase, an integrator of Wnt, BMP and TGF-beta signaling. In humans, formation of non-adherent tumour spheres by pancreatic cancer cells is associated with upregulation of multiple Wnt genes, and pancreatic CTCs revealed significant enrichment for non-canonical Wnt signaling in 5 of 11 cases. Thus, molecular analysis of CTCs may identify novel therapeutic targets to prevent the distal spread of cancer. Expression profiling of circulating tumor cells in human pancreatic cancer patients support a hypothesis that WNT signaling plays a role in pancreatic cancer metastasis.
Project description:By applying RNA-ISH and RNAseq to circulating tumor cells (CTCs), the study provides definitive evidence of epithelial to mesenchymal transition (EMT) across all histological types of breast cancer, identifying mediators such as FOXC1 and TGF-β signaling, and demonstrating dynamic treatment-associated changes in EMT within clusters of CTCs. Epithelial to mesenchymal transition (EMT) has been postulated to contribute to the migration and dissemination of cancer cells, but supporting histopathological evidence is limited. We used a microfluidic device to isolate circulating tumor cells (CTCs), combined with multiplex fluorescent RNA-in-situ hybridization (ISH) and RNA sequencing, to quantify and characterize EMT in breast cancer cells within the bloodstream. Whereas only rare (0.1-10%) cells in the primary tumor expressed both mesenchymal and epithelial markers, such biphenotypic as well as purely mesenchymal cells were enriched among CTCs, across all histological subtypes of breast cancer. In an index patient followed longitudinally, fluctuation in epithelial and mesenchymal states was observed as a function of initial response and subsequent resistance to therapy. Mesenchymal markers were predominant in clusters of tumor cells, many of which had adherent platelets. Finally, RNA sequencing of CTC clusters identified TGF-β and other EMT-related signatures, which were absent from more epithelial CTCs. FOXC1, a known regulator of EMT, was abundantly expressed in mesenchymal CTCs and was detectable within localized regions of the primary breast tumor. Together, these data support a role for EMT in the blood-borne dissemination of breast cancer and point to the dynamic nature of this cell fate change.
Project description:Nucleosomes are the principal packaging units of chromatin and critical for gene regulation and genome stability. In mammals, a subset of nucleosomes fail to be replaced by protamines during spermatogenesis and are retained in mature spermatozoa providing opportunities for paternal epigenetic transmission. In humans, the remaining 10% localize at regulatory elements of genes. To assess evolutionary conservation and to dissect the molecular logic underlying nucleosome retention, we determined the genome wide nucleosome occupancy in mouse spermatozoa that only contain 1% residual histones. In striking contrast to mammalian somatic cells and haploid round spermatids, we observe high enrichment of nucleosomes at CpG-rich sequences throughout the genome, at conserved regulatory sequences as well as at intra- and intergenic regions and repetitive DNA. This preferred occupancy occurs mutually exclusive with DNA methylation both in mouse and human sperm. At unmethylated CpG-rich sequences, residing nucleosomes are largely composed of the H3.3 histone variant, and trimethylated at lysine 4 (H3K4me3). Both canonical H3.1/H3.2 and H3.3 variant histones are present at promoters marked by Polycomb-mediated H3K27me3, which is strongly predictive for gene repression in pre-implantation embryos. Our data indicate important roles of DNA sequence composition, DNA methylation, variant H3.3 and canonical H3.1/H3.2 histones and associated modifications in nucleosome retention versus eviction during the histone-to-protamine remodeling process in elongating spermatids and potentially in epigenetic inheritance by nucleosomes between generations. Identification of histone, histone variant and histone modification states in round spermatids and sperm
Project description:WTX encodes a tumor suppressor implicated in Wilms tumor and in mesenchymal differentiation, with distinct functions in the cytoplasm, at the plasma membrane and in the nucleus. Here we report that the transcriptional corepressor TRIM28 is the major binding partner for nuclear WTX. The WTX-TRIM28 interaction supports chromatin binding by TRIM28, enhancing transcriptional silencing of some TRIM28 target sequences. In mouse ES cells, where TRIM28-mediated silencing of repetitive sequences is best characterized, Wtx knockdown similarly derepresses endogenous retroviruses and LINE elements.
Project description:In this study, a GFP-tagged version of the protein HCF-1 was immuno-precipitated from C. elegans lysates of the strain IU171 and co-purifying proteins were identified by LC-MS/MS. As a negative control, the same immuno-precipitation was conducted from wild-type (strain N2) worms that did not carry a HCF-1::GFP transgene.
Project description:Multiprotein chromatin remodelling complexes show remarkable conservation of function amongst metazoans, even though each component present in invertebrates are often present as multiple paralogous proteins in vertebrate complexes. In some cases these paralogues have been shown to specify distinct biochemical and/or functional activities in vertebrate cells. Here we set out to define the biochemical and functional diversity encoded by one such group of proteins within the mammalian Nucleosome Remodelling and Deaceylation (NuRD) complex: Mta1, Mta2 and Mta3. We find that, in contrast to what has been described in somatic cells, MTA proteins are not mutually exclusive within ES cell NuRD and, despite subtle differences in chromatin binding and biochemical interactions, serve largely redundant functions. Nevertheless, ES cells lacking all three MTA proteins represent a complete NuRD null and are viable, allowing us to identify a previously undetected function for NuRD in maintaining differentiation trajectory during early stages of lineage commitment.