The Notch signalling pathway plays fundamental roles in diverse developmental processes in metazoans, where it is important in driving cell fate and directing differentiation of various cell types. However, we still have limited knowledge about the role of Notch in early preimplantation stages of mammalian development, or how it interacts with other signalling pathways active at these stages such as Hippo. By using genetic and pharmacological tools in vivo, together with image analysis of single embryos and pluripotent cell culture, we have found that Notch is active from the 4-cell stage. Transcriptomic analysis in single morula identified novel Notch targets, such as early naïve pluripotency markers or transcriptional repressors such as TLE4. Our results reveal a previously undescribed role for Notch in driving transitions during the gradual loss of potency that takes place in the early mouse embryo prior to the first lineage decisions. Overall design: Transcriptomic analysis comparing single Rbpj mutant and control mouse morulae. RNA was isolated from individual E2.5 embryos from two litters. 3 mutant and 3 control embryos were used for analysis.
Transitions in cell potency during early mouse development are driven by Notch.
Specimen part, Subject
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The Scc2-Scc4 complex acts in sister chromatid cohesion and transcriptional regulation by maintaining nucleosome-free regions.
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Budding yeast Wapl controls sister chromatid cohesion maintenance and chromosome condensation.
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View SamplesThe Scc2/Scc4 complex binds to broad nucleosome-free regions in the promoters of highly expressed genes. The cohesin loader is recruited to these sites by the RSC chromatin remodeling complex
The Scc2-Scc4 complex acts in sister chromatid cohesion and transcriptional regulation by maintaining nucleosome-free regions.
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View SamplesCohesin acetylation by Eco1 during DNA replication establishes sister chromatid cohesion. We show that acetylation makes cohesin resistant to Wapl activity from S-phase until mitosis. Wapl turns out to be a key regulator of cohesin dynamics on chromosomes by controling cohesin maintenance following its establishment in S-phase and its role in chromosome condensation.
Budding yeast Wapl controls sister chromatid cohesion maintenance and chromosome condensation.
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View SamplesHistone acetylation and other modifications of the chromatin are important regulators of gene expression and, consequently, may contribute to drug-induced behaviors and neuroplasticity. Previous studies have shown that a reduction on histone deacetylase (HDAC) activity results on the enhancement of some psychostimulant-induced behaviors. In the present study, we extend those seminal findings by showing that the administration of the HDAC inhibitor sodium butyrate enhances morphine-induced locomotor sensitization and conditioned place preference. In contrast, this compound has no effects on the development of morphine tolerance and dependence. Similar effects were observed for cocaine and ethanol-induced behaviors. These behavioral changes were accompanied by a selective boosting of a component of the transcriptional program activated by chronic morphine administration that included circadian clock genes and other genes relevant in addictive behavior. Our results support an specific role for histone acetylation and the epigenetic modulation of transcription at a reduced number of biologically relevant loci on non-homeostatic, long lasting, drug-induced behavioral plasticity. To further investigate the molecular bases of sodium butyrate action on long-lasting behavioral responses to morphine, we screened for potential substrates of their interaction by performing a genome-wide comparison of the striatal transcriptome after chronic administration of morphine in the absence or presence of sodium butyrate.
Selective boosting of transcriptional and behavioral responses to drugs of abuse by histone deacetylase inhibition.
Sex, Age, Specimen part
View SamplesMethods of reprogramming somatic cells to an induced pluripotent state (iPSC) have enabled the direct modeling of human disease and ultimately promise to revolutionize regenerative medicine. iPSCs offer an invaluable source of patient-specific pluripotent stem cells for disease modeling, drug screening, toxicology tests and importantly for regenerative medicine, and already have been employed to unmask novel insights into human diseases. While iPSCs can be consistently generated through overexpression of the four Yamanaka Factors OCT4, SOX2, KLF4 and c-MYC (OSKM), reprogrammed cells present worrisome differences with embryonic stem cells in transcriptional and epigenetic profiles, as well as developmental potential and difficulties in cell culturing. A thorough mechanistic understanding of the reprogramming process is critical to overcoming these barriers to the clinical use of iPSC. We have recently published a novel factor combination based on molecules specifically enriched in the metaphase II human oocyte. We have shown that just the overexpression of histone-remodeling chaperone ASF1A and OCT4 in hADFs previously exposed to the oocyte-specific paracrine growth factor GDF9 can reprogram hADFs into pluripotent cells (AO9-iPSCs). Our study contributes to the understanding of the molecular pathways governing somatic cell reprogramming. Here we want to go deeper in the reprogramming mechanisms by understanding the importance of somatic cell origin, and analyzing (and establishing comparison with) the transcriptional and epigenetic characteristics of AO9-iPSCs. As the intrinsic histone chaperone activity of ASF1A and our data indicate, these cells could be closer to the embryonic pluripotent state, with less epigenetic memory, better culture properties and differentiation potential.
Analysis of Menstrual Blood Stromal Cells Reveals SOX15 Triggers Oocyte-Based Human Cell Reprogramming.
Sex, Specimen part, Subject
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Genomic landscape of transcriptional and epigenetic dysregulation in early onset polyglutamine disease.
Sex, Age, Specimen part
View SamplesTranscriptional dysregulation is an important early feature of polyglutamine diseases. One of its proposed causes is defective neuronal histone acetylation, but important aspects of this hypothesis, such as the precise genomic topography of acetylation deficits
Genomic landscape of transcriptional and epigenetic dysregulation in early onset polyglutamine disease.
Sex, Age, Specimen part
View SamplesBrain metastasis represents a substantial source of morbidity and mortality in various cancers, and is characterized by high resistance to chemotherapy. Here we define the role of the most abundant cell type in the brain, the astrocyte, in brain metastasis. Cancer cells assemble of carcinoma-astrocyte gap junctions composed of connexin 43 (Cx43). Cx43 in cancer cells support brain metastatic colonization. We employ translating ribosome affinity purification (TRAP) to isolate translating mRNA from cancer cells in mixed asrtocyte co-cultures to determine the mechanism behind this Cx43-mediated brain metastatic growth. Once engaged with the astrocyte gap-junctional network, brain metastatic cancer cells employ these channels to transfer the cytosolic dsDNA response messenger cGAMP to astrocytes, activating the cGAS-STING pathway and production of inflammatory cytokines IFNa and TNFa. As paracrine signals, these factors activate the STAT1 and NF-?B pathways in brain metastatic cells, which support tumour growth and chemoresistance. Overall design: TRAP mRNAs were isolated from MDA231-BrM2 (control or Cx43-depleted) after co-cultured with astrocytes. Gene expression profiles were generated by deep sequencing, in duplicate, using Illumina Illumina HiSeq 2000. Two independent replicates were done per condition (i.e. rep1 and rep2).
Carcinoma-astrocyte gap junctions promote brain metastasis by cGAMP transfer.
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