Post-translational modifications, such as poly(ADP-ribosyl)ation (PARylation), regulate chromatin-modifying enzymes, ultimately affecting gene expression. This study explores the role of poly(ADP-ribose) polymerase (PARP) on global gene expression in a lymphoblastoid B cell line. We found that inhibition of PARP catalytic activity with olaparib resulted in global gene deregulation, affecting approximately 11% of genes expressed. Gene ontology analysis revealed that PARP could exert these effects through transcription factors and chromatin-remodeling enzymes, including the Polycomb Repressive Complex 2 (PRC2) member EZH2. EZH2 mediates the trimethylation of histone H3 at lysine 27 (H3K27me3), a modification associated with chromatin compaction and gene silencing. Both pharmacological inhibition of PARP and knockdown of PARP1 induced the expression of EZH2 that resulted in increased global H3K27me3. Chromatin immunoprecipitation confirmed that PARP1 inhibition led to H3K27me3 deposition at EZH2-target genes, which resulted in gene silencing. Moreover, increased EZH2 expression is attributed to occupancy loss of the transcription repressor E2F4 at the EZH2 promoter following PARP inhibition. Together, these data show that PARP plays an important role in global gene regulation and identifies for the first time a direct role of PARP1 in regulating the expression and function of EZH2. Overall design: Examination of the effect of PARP inhibition on global gene expression in LCLs cell lines. mRNA profiles of LCLs cells lines treated at different time points with olaparib were generated by deep sequencing, in triplicate, using Illumina GAIIx.
Global Transcriptome Analysis Reveals That Poly(ADP-Ribose) Polymerase 1 Regulates Gene Expression through EZH2.
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View SamplesThe aim of the study was to illucidate how BAFF mediates B cell survival and growth through the identification of BAFF-regulated genes.
BAFF controls B cell metabolic fitness through a PKC beta- and Akt-dependent mechanism.
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View SamplesPancreatic ductal adenocarcinoma (PDA) carries a dismal prognosis and current treatments are only modestly effective. We present evidence that this variation is caused in part by recurrent, pervasive molecular differences between tumors. mRNA expression profiles measured using microdissected PDA clinical samples reveal three dominant subtypes of disease; epithelial, mesenchymal and acinar-like. The classical and quasi-mesenchymal subtypes are observed in human and mouse PDA cell lines. Importantly, responses to cytotoxics and KRAS depletion in human PDA cell lines differ substantially between subtypes, and in opposing directions. Integrated genomics implicate and functional studies support overexpression of the trancription factor GATA6 as a driver of the epithelial subtype. These results provide a molecular framework for evaluating the prospects of personalized treatment in PDA.
Subtypes of pancreatic ductal adenocarcinoma and their differing responses to therapy.
Specimen part, Cell line
View SamplesCTCF (CCCTC-binding factor) is a highly conserved 11-zinc finger DNA binding protein with tens of thousands of binding sites genome-wide. CTCF acts as a multifunctional regulator of transcription, having been previously associated with activator, repressor, and insulator activity. These diverse regulatory functions are crucial for preimplantation development and are implicated in the regulation of numerous lineage-specific genes. Despite playing a critical role in developmental gene regulation, the mechanisms that underlie developmental changes in CTCF recruitment and function are poorly understood. Our previous work suggested that differences in CTCF’s binding site sequence may affect the regulation of CTCF recruitment, as well as CTCF’s regulatory function. To investigate these two possibilities directly during a developmental process, changes in genome-wide CTCF binding and gene expression were characterized during in vitro differentiation of mouse embryonic stem cells. CTCF binding sites were initially separated into three classes (named LowOc, MedOc, and HighOc) based on similarity to the consensus motif. The LowOc class, with lower-similarity to the consensus motif, is more likely to show changes in binding during differentiation. These more dynamically bound sites are enriched for motifs that confer a lower in vitro affinity for CTCF, suggesting a mechanism where sites with low-binding affinity are more amenable to developmental control. Additionally, by comparing changes in CTCF binding with changes in gene expression during differentiation, we show that LowOc and HighOc sites are associated with distinct regulatory functions. In sum, these results suggest that the regulatory control of CTCF’s binding and function is dependent in part upon specific motifs within its DNA binding site. Overall design: Mouse E14 ES cells were differentiated in vitro for 4.5 days using retinoic acid. RNA-Seq was performed from cells collected before and after differentiation.
CTCF binding site sequence differences are associated with unique regulatory and functional trends during embryonic stem cell differentiation.
Specimen part, Cell line, Subject
View SamplesThe roles of histone demethylase RBP2 in gene expression were assessed using gene expression profiling experiments with wild type and RBP2-/- primary MEFs. Several cytokine genes including SDF1 and Kit ligand were upregulated upon inactivation of RBP2.
The retinoblastoma binding protein RBP2 is an H3K4 demethylase.
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View SamplesThis SuperSeries is composed of the SubSeries listed below.
Identification of key regions and genes important in the pathogenesis of sezary syndrome by combining genomic and expression microarrays.
Specimen part, Disease
View SamplesThis study used tumour and paired normal samples from 28 Szary Syndrome (SS) patients to define recurrent regions of chromosomal aberrations. Our data identified recurrent losses of 17p13.2-p11.2 and 10p12.1-q26.3 occurring in 71 and 68% of cases respectively; common gains were detected for 17p11.2-q25.3 (64%) and chromosome 8/8q (50%). Moreover, we identified novel genomic lesions recurring in more than 30% of tumours: loss of 9q13-q21.33 and gain of 10p15.3-10p12.2. In the Szary Syndrome cases analysed, we could find several small and few large Uniparental Disomies involving interstitial or telomeric regions of LOH occurring mainly for chromosome 10 and to a lesser extent for chromosome 9 and 17. In the attempt to correlate Copy Number data and clinical parameters we find a relationship between complex pattern of chromosomal aberrations, involving at least three recurrent Copy Number alterations, and shorter survival. Integrating mapping and transcriptional data we were able to identify a total of 113 deregulated transcripts in aberrant chromosomal regions that included cancer related genes such as members of the NF-kB pathway (BAG4, BTRC, NKIRAS2, PSMD3, TRAF2) that might explain its constitutive activation in CTCL. Matching this list of genes with those discriminating patients with different survival times we identify several common candidates that might exert critical roles in Szary Syndrome, like BUB3 and PIP5K1B.
Identification of key regions and genes important in the pathogenesis of sezary syndrome by combining genomic and expression microarrays.
Specimen part, Disease
View SamplesCurrent models imply that the FERM domain protein Merlin, encoded by the tumor suppressor NF2, inhibits mitogenic signaling at or near the plasma membrane. Here, we show that the closed, growth inhibitory form of Merlin accumulates in the nucleus, binds to the E3 ubiquitin ligase CRL4DCAF1, and suppresses its activity. Depletion of DCAF1 blocks the promitogenic effect of inactivation of Merlin. Conversely, enforced expression of a Merlin-insensitive mutant of DCAF1 counteracts the antimitogenic effect of Merlin. Re-expression of Merlin and silencing of DCAF1 induce a similar, tumor-suppressive program of gene expression. Tumor-derived mutations invariably disrupt Merlins ability to interact with or inhibit CRL4DCAF1. Finally, depletion of DCAF1 inhibits the hyperproliferation of Schwannoma cells from NF2 patients and suppresses the oncogenic potential of Merlin-deficient tumor cell lines. We propose that Merlin suppresses tumorigenesis by translocating to the nucleus to inhibit CRL4DCAF1.
Merlin/NF2 suppresses tumorigenesis by inhibiting the E3 ubiquitin ligase CRL4(DCAF1) in the nucleus.
Specimen part
View SamplesDefining the role of epigenetic regulators in normal hematopoiesis has become critically important, as recurrent mutations or aberrant expression of these genes has been identified in both myeloid and lymphoid hematological malignancies. We have found that PRMT4, a type I arginine methyltransferase, whose function in normal and malignant hematopoiesis is unknown, is overexpressed in AML patient samples. In support of an oncogenic role for PRMT4, we find that its overexpression blocks the myeloid differentiation of human stem/progenitor cells (HSPCs) while its knockdown (KD) is sufficient to induce myeloid differentiation of HSPCs and multiple AML cell lines. Although classically thought of as a co-activator, we found that PRMT4 functions to repress the expression of miR-223 in HSPCs via the methylation of RUNX1, which triggers the assembly of a multi-protein repressor complex that includes DPF2. As part of a feedback loop, PRMT4 expression is repressed post-transcriptionally by miR-223 during the normal differentiation process. These data reveal an unidentified role of PRMT4 in myeloid differentiation and its unexpected repressive role in transcriptional regulation. Furthermore, depletion of PRMT4 results in the differentiation of myeloid leukemia cells in vitro and their decrease proliferation in vivo. Thus, targeting PRMT4 holds potential as a novel therapy for acute myelogenous leukemia. Overall design: Purified human primary CD34+ cells were transduced with lentiviruses carrying PRMT4KD or scramble control shRNAs. Total RNA was extrated. RNAseq was performed to identify target genes that are regulated by PRMT4. Experiments were performed in triplicate.
PRMT4 blocks myeloid differentiation by assembling a methyl-RUNX1-dependent repressor complex.
Specimen part, Subject
View SamplesWe report the application of RNA-seq analysis for high-throughput profiling of murine lungs infected with Aspergillus fumigatus. We compared the lung transcription of wildtype murine lungs and lungs from mice deficient in metabolic cytokine adiponectin. Overall design: Examination of 2 different mice strain and comparison of lung transcripts in response to Aspergillus fumigatus infection.
The Metabolic Cytokine Adiponectin Inhibits Inflammatory Lung Pathology in Invasive Aspergillosis.
Specimen part, Cell line, Subject
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