Unknown,Transcriptomics,Genomics,Proteomics

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A unique chromatin complex occupies young alpha-satellite arrays of human centromeres

ABSTRACT: Using high-resolution chromatin immunoprecipitation (ChIP) of centromere components and clustering of sequence data we find that specific dimeric alpha-satellite units shared by multiple individuals dominate functional human centromeres. We have analyzed the chromatin landscape of the human genome using paired-end MNase-seq

ORGANISM(S): Homo sapiens

SUBMITTER: Jorja Henikoff

PROVIDER: E-GEOD-60951 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Fibro-adipogenic progenitors (FAPs) are emerging cellular components of the skeletal muscle regenerative environment. The alternative functional phenotype of FAPs - either supportive of muscle regeneration or promoting fibro-adipogenic degeneration M-bM-^@M-^S is a key determinant in the pathogenesis of muscular diseases, including Duchenne Muscular Dystrophy (DMD). However, the molecular regulation of FAPs is still unknown. We show here that an M-bM-^@M-^\HDAC-myomiR-BAF60 variant networkM-bM-^@M-^] regulates the functional phenotype of FAPs in dystrophic muscles of mdx mice. Combinatorial analysis of gene expression microarray and genome-wide chromatin remodeling by Nuclease accessibility (NA)-seq revealed that HDAC inhibitors de-repress a M-bM-^@M-^\latentM-bM-^@M-^] myogenic program in FAPs from dystrophic muscles at early stages of disease progression. In these cells HDAC inhibition promoted the expression of two core components of the myogenic transcriptional machinery, MyoD and BAF60C, and upregulated the myomiRs (miRs) 1.2, 133 and 206, which target two alternative BAF60 variants (BAF60A and B) ultimately leading to the activation of a pro-myogenic program at the expense of the fibro-adipogenic phenotype. By contrast, FAPs from dystrophic muscles at late stages of disease progression displayed resistance to HDACi-induced chromatin remodeling at myogenic loci and fail to activate the pro-myogenic phenotype. These results reveal a previously unappreciated disease stage-specific bipotency of mesenchimal cells within the regenerative environment of dystrophic muscles. Resolution of such bi-potency by epigenetic interventions, such as HDACi, provides the molecular rationale for the in situ reprogramming of target cells to promote therapeutic regeneration of dystrophic muscles. Genome-wide chromatin accessibility patterns in FAPs cells derived from mdx mice at different ages treated either with HDAC inhibitor Trichostatin A (TSA) or with vehicle (saline solution) were assessed using NA-seq (PMID: 19289091)

Project description:Our group is interested in epithelial-to-mesenchymal transition (EMT), in particular, TGF-beta induced EMT. TGF-beta signalling has been shown to be an important factor in the induction of EMT and it has been demonstrated that adding TGF-beta to epithelial cells in culture is a convenient way to study the process of EMT. In response to TGF-beta, Smad2 and 3 are activated, and form complexes with Smad4, which then regulate transcription of target genes through interactions with other DNA binding transcription factors. In the induction of EMT, the activated Smads mediate transcriptional regulation through three families of transcription factors, resulting in repression of epithelial marker gene expression and activation of mesenchymal gene expression (Xu J, et al. 2009) Also investigated in this study is the role of H2A.Z in EMT. H2A.Z is an evolutionary conserved and a metazoan essential histone variant of the H2A class. Mice deficient in H2A.Z die during early development but the reason for this is unknown (Faast et al. 2001). Previously, our laboratory showed that the loss of H2A.Z in Xenpous laevis impaired cell movement required for the formation of the mesoderm and neural crest (Ridgway et al. 2004). Given that mesoderm formation is critically dependent upon EMT, we therefore wondered whether H2A.Z might be a chromatin regulator of EMT. We transfected MDCK cells with a lentiviral vector to express a construct encoding an shRNA targeting canine H2A.Z as we wanted to test the hypothesis that H2A.Z is involved in the maintenance of cellular identity and that its loss might trigger de-differentiation. In order to investigate changes in histone variant H2A.Z occupancy associated with TGF-beta induced epithelial-to-mesenchymal transition (EMT) we performed H2A.Z ChIP-Seq in untreated and TGFb-treated MDCK cells. The MDCK cell line has been extensively used as a model system for EMT because they convert fully from the epithelial to the mesenchymal state in response to TGF-beta. Please note that RNA-seq data generated in conjunction to this ChIP-seq data set were also deposited at ArrayExpress under accession number E-MTAB-5628 ( https://www.ebi.ac.uk/arrayexpress/experiments/E-MTAB-5628 ).

Project description:The proper balance of excitatory and inhibitory neurons is crucial to normal processing of somatosensory information in the dorsal spinal cord. Two neural basic helix-loop-helix transcription factors, Ascl1 and Ptf1a, are essential for generating the correct number and sub-type of neurons in multiple regions of the nervous system. M-BM- In the dorsal spinal cord, Ascl1 and Ptf1a have contrasting functions in specifying inhibitory versus excitatory neurons. To understand how Ascl1 and Ptf1a function in these processes, we identified their direct transcriptional targets genome-wide in the embryonic mouse neural tube using ChIP-Seq and RNA-Seq. We show that Ascl1 and Ptf1a regulate the specification of excitatory and inhibitory neurons in the dorsal spinal cord through direct regulation of distinct homeodomain transcription factors known for their function in neuronal sub-type specification. Besides their roles in regulating these homeodomain factors, Ascl1 and Ptf1a each function differently during neuronal development with Ascl1 directly regulating genes with roles in several steps of the neurogenic program including, Notch signaling, neuronal differentiation, axon guidance, and synapse formation. In contrast, Ptf1a directly regulates genes encoding components of the neurotransmitter machinery in inhibitory neurons, and other later aspects of neural development distinct from those regulated by Ascl1. Moreover, Ptf1a represses the excitatory neuronal fate by directly repressing several targets of Ascl1. Examination of the Ascl1 and Ptf1a bound sequences shows they are enriched for a common E-Box with a GC core and with additional motifs used by Sox, Rfx, Pou, and Homeodomain factors. Ptf1a bound sequences are uniquely enriched in an E-Box with a GA/TC core and in the binding motif for its co-factor Rbpj, providing two keys to specificity of Ptf1a binding. The direct transcriptional targets identified for Ascl1 and Ptf1a provide a molecular understanding for how they function in neuronal development, particularly as key regulators of homeodomain transcription factors required for neuronal sub-type specification. Examination of Ascl1 and Ptf1a genome-wide binding in developing neural tube.

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A unique chromatin complex occupies young alpha-satellite arrays of human centromeres

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