Malignant gliomas constitute one of the most significant areas of unmet medical need, due to the invariable failure of surgical eradication and their marked molecular heterogeneity. Accumulating evidence has revealed a critical contribution by the Polycomb axis of epigenetic repression. However, a coherent understanding of the regulatory networks affected by Polycomb during gliomagenesis is still lacking. Here we integrate transcriptomic and epigenomic analyses to define Polycomb-dependent networks that promote gliomagenesis, validating them both in two independent mouse models and in a large cohort of human samples. We found that Polycomb dysregulation in gliomagenesis affects transcriptional networks associated to invasiveness and de-differentiation. The dissection of these networks uncovers Zfp423 as a crtitical Polycomb-dependent transcription factor whose silencing negatively impacts survival. The anti-gliomagenic activity of Zfp423 requires interaction with the SMAD proteins within the BMP signaling pathway, pointing to a novel synergic circuit through which Polycomb inhibits BMP signaling. Overall design: Transcriptomic analysis of two different stages of gliomagenesis
Polycomb dysregulation in gliomagenesis targets a Zfp423-dependent differentiation network.
Specimen part, Cell line, Subject
View SamplesTransdifferentiation of fibroblasts into induced Neuronal cells (iNs) by neuronal-specific transcription factors Brn2, Myt1l and Ascl1 is a paradigmatic example of inter-lineage conversion across epigenetically distant cells. Despite tremendous progress on the transcriptional hierarchy underlying transdifferentiation, the enablers of the concomitant epigenome resetting remain to be elucidated. Here we investigated the role of KMT2A and KMT2B, two histone H3 lysine 4 methylases with cardinal roles in development, through individual and combined inactivation. We found that Kmt2b, whose human homologue's mutations cause dystonia, is selectively required for iN conversion through the suppression of the alternative myocyte program and the induction of neuronal maturation genes. Overall design: In order to study the role of KMT2A and KMT2B during transdifferentiation, we employed conditional mouse strains carrying: i) the exon 2 of Kmt2a and/or Kmt2b flanked by LoxP sites; ii) the knock-in of the YFP-coding gene into one Rosa26 allele, downstream of a LoxP-flanked transcription termination cassette (STOP cassette); and iii) the gene coding for the tamoxifen-inducible version of Cre recombinase knocked into the second Rosa26 allele (Glaser et al., 2006; Kranz et al., 2010; Testa et al., 2004). MEFs were derived from Kmt2a (and/or Kmt2b)fl/fl Cre+ YFP+ embryos and from Kmt2a+/+Kmt2b+/+ Cre+ YFP+ or Kmt2afl/+ Cre+ YFP+ for Kmt2a conditional KO (cKO) as controls (Figure 1A), and were subjected to transdifferentiation. After 13 days of BAM treatment, cells were FACS sorted for PSA-NCAM expression, and the transcriptome of positive and negative cells were independently profiled.
KMT2B Is Selectively Required for Neuronal Transdifferentiation, and Its Loss Exposes Dystonia Candidate Genes.
Specimen part, Subject
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7q11.23 dosage-dependent dysregulation in human pluripotent stem cells affects transcriptional programs in disease-relevant lineages.
Sex, Specimen part, Subject
View SamplesWe apply the cellular reprogramming experimental paradigm to two disorders caused by symmetrical copy number variations (CNV) of 7q11.23 and displaying a striking combination of shared as well as symmetrically opposite phenotypes: Williams Beuren syndrome (WBS) and 7q microduplication syndrome (7dup). Through a uniquely large and informative cohort of transgene-free patient-derived induced pluripotent stem cells (iPSC), along with their differentiated derivatives, we find that 7q11.23 CNV disrupt transcriptional circuits in disease-relevant pathways already at the pluripotent state. These alterations are then selectively amplified upon differentiation into disease-relevant lineages, thereby establishing the value of large iPSC cohorts in the elucidation of disease-relevant developmental pathways. In addition, we functionally define the quota of transcriptional dysregulation specifically caused by dosage imbalances in GTF2I (also known as TFII-I), a transcription factor in 7q11.23 thought to play a critical role in the two conditions, which we found associated to key repressive chromatin modifiers. Finally, we created an open-access web-based platform (accessible at http://bio.ieo.eu/wbs/ ) to make accessible our multi-layered datasets and integrate contributions by the entire community working on the molecular dissection of the 7q11.23 syndromes.
7q11.23 dosage-dependent dysregulation in human pluripotent stem cells affects transcriptional programs in disease-relevant lineages.
Sex, Specimen part, Subject
View SamplesFunctional characterization of AtWRKY72 using Arabidopsis T-DNA insertion lines showed that this gene is important for basal defense to root-knot nematode (RKN) and Hyaloperonospora parasitica arabidopsis (Hpa), but not several tested R gene-mediated defenses.To profile transcriptional reprogramming associated with AtWRKY72-dependent basal defense we used Affymetrix ATH1 GeneChips representing ~24,000 Arabidopsis genes. Three independent biological replicates were performed with Col-0, wrky72-1 and wrky72-2 plants at 96 hpt with HpaNoco2 or mock treatment. Using a false discovery rate of less than 0.05 we identified for each of these three lines genes that showed significant transcriptional changes in response to HpaNoco2 compared to the mock-treated controls. Identification of downstream targets of WRKY72 in Arabidopsis by this microarray suggests that WRKY72 uses a unique signaling pathway that involves AP2/ERF TFs independent of the ethylene signaling pathway.
WRKY72-type transcription factors contribute to basal immunity in tomato and Arabidopsis as well as gene-for-gene resistance mediated by the tomato R gene Mi-1.
No sample metadata fields
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GeneChip analysis of human embryonic stem cell differentiation into hemangioblasts: an in silico dissection of mixed phenotypes.
No sample metadata fields
View SamplesTo understand the differentiation process of embryonic stem cells into hemangioblasts, gene expression profiles of ES, EB and Blast cells (BL) were analyzed.
GeneChip analysis of human embryonic stem cell differentiation into hemangioblasts: an in silico dissection of mixed phenotypes.
No sample metadata fields
View SamplesTo understand the differentiation process of embryonic stem cells into hemangioblasts, gene expression profiles of ES, EB and Blast cells (BL) were analyzed.
GeneChip analysis of human embryonic stem cell differentiation into hemangioblasts: an in silico dissection of mixed phenotypes.
No sample metadata fields
View SamplesTo understand the differentiation process of embryonic stem cells into hemangioblasts, gene expression profiles of ES, EB and Blast cells (BL) were analyzed.
GeneChip analysis of human embryonic stem cell differentiation into hemangioblasts: an in silico dissection of mixed phenotypes.
No sample metadata fields
View SamplesTo understand the differentiation process of embryonic stem cells into hemangioblasts, gene expression profiles of ES, EB and Blast cells (BL) were analyzed.
GeneChip analysis of human embryonic stem cell differentiation into hemangioblasts: an in silico dissection of mixed phenotypes.
No sample metadata fields
View Samples