Changes in chromatin accessibility and gene expression induced by overexpression of ONECUT transcription factors
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PROVIDER: PRJNA491706 | ENA |
REPOSITORIES: ENA
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Project description:Remodeling of chromatin accessibility is necessary for successful reprogramming of fibroblasts to neurons. However, it is still not fully known which transcription factors can induce a neuronal chromatin accessibility profile when overexpressed in fibroblasts. To identify such transcription factors, we here used ATAC-sequencing to generate differential chromatin accessibility profiles between human fibroblasts and iNeurons, an in vitro neuronal model system obtained by overexpression of Neurog2 in induced pluripotent stem cells (iPSCs). We found that the ONECUT transcription factor sequence motif was strongly associated with differential chromatin accessibility between iNeurons and fibroblasts. All three ONECUT transcription factors associated with this motif (ONECUT1, ONECUT2 and ONECUT3) induced neuronal morphology and expression of neuronal genes within two days of overexpression in fibroblasts. We observed widespread remodeling of chromatin accessibility; in particular, we found that chromatin regions that contain the ONECUT motif were in- or lowly accessible in fibroblasts and became accessible after the overexpression of ONECUT1, ONECUT2 or ONECUT3. There was substantial overlap with iNeurons, still, many regions that gained accessibility following ONECUT overexpression were not accessible in iNeurons. Our study highlights the potential of ONECUT transcription factors for direct neuronal reprogramming.
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Project description:Remodeling of chromatin accessibility is necessary for successful reprogramming of fibroblasts to neurons. However, it is still not fully known which transcription factors can induce a neuronal chromatin accessibility profile when overexpressed in fibroblasts. To identify such transcription factors, we used ATAC-sequencing to generate differential chromatin accessibility profiles between human fibroblasts and iNeurons, an in vitro neuronal model system obtained by overexpression of Neurog2 in induced pluripotent stem cells (iPSCs). We found that the ONECUT transcription factor sequence motif was strongly associated with differential chromatin accessibility between iNeurons and fibroblasts. All three ONECUT transcription factors associated with this motif (ONECUT1, ONECUT2 and ONECUT3) induced a neuron-like morphology and expression of neuronal genes within two days of overexpression in fibroblasts. We observed widespread remodeling of chromatin accessibility; in particular, we found that chromatin regions that contain the ONECUT motif were in- or lowly accessible in fibroblasts and became accessible after the overexpression of ONECUT1, ONECUT2 or ONECUT3. There was substantial overlap with iNeurons, still, many regions that gained accessibility following ONECUT overexpression were not accessible in iNeurons. Our study highlights both the potential and challenges of ONECUT-based direct neuronal reprogramming.
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Project description:Transcription factors and DNA regulatory binding motifs are fundamental components of the gene regulatory network (GRN). Here, by using genome-wide occupancy profiling of master regulators of MyoGenesis (MyoD and MyoGenin), we show their extensive occupancy in the extragenic enhancer regions coinciding with RNA synthesis (i.e. eRNA). In particular, multiple regions coding for eRNAs were observed within regulatory region of MYOD1, including previously characterized Distal Regulatory Regions (DRR) and Core Enhancer (CE). While CERNA enhanced RNA polymerase II (PolII) occupancy and transcription at MYOD1, DRRRNA acted in trans to activate the downstream MyoGenic GRN. The deployment of transcriptional machinery to appropriate loci is contingent on chromatin accessibility, a rate-limiting step preceding PolII assembly. By nuclease sensitivity assay, we show that eRNAs increase genomic access to the transcriptional complex at defined regulatory regions. In conclusion, our data suggest eRNAs establish a cell-type-specific transcriptional circuitry by directing chromatin-remodeling events. Examination of MyoD and MyoG binding events and production of RNA at the enhancer sites during myogenic differentiation. We performed RNAi against enhancer-derived RNA (DRRi) which resulted in reduction of chromatin accessiblity and RNA polymerase II occupancy at defined regulatory elements. In complementary experiments, overexpression of DRR-RNA (pHAN_DRR1.2) resulted in early activation of MyoG. GFPi and GFP overexpression (pHAN_GFP) were used as control in these experiments, respectively.
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