Project description:In this study, we have utilized a single-cell RNA-Sequencing platform coupled with transgenic lineage tracing in order to follow the progression of different embryonic neural stem cell populations as they progress into adult dormant neural stem cells. We show that adult dormant V-SVZ neural stem cells of different embryonic origins share a common molecular signature and reacquire an embryonic precursor-like state when activated to make new neurons in the adult brain.
Project description:A key question in developmental biology is how cellular differentiation is controlled during development. Particular interest has focused upon changes in chromatin state, with transitions between Trithorax-group (TrxG) and Polycomb-group (PcG) chromatin states shown to be vital for the differentiation of ES cells to multipotent stem cells in culture. However, little is known as to the role of chromatin states during the development of complex organs such as the brain. Recent research has also suggested a number of other chromatin states exist in cell culture, including an active state lacking TrxG proteins and a repressive “Black”, “Basal” or “Null” chromatin state devoid of common chromatin marks. The role that these new chromatin states play during development is unknown. Here we show that large scale chromatin remodeling occurs during in vivo Drosophila melanogaster neural development. We demonstrate that the majority of genes that are activated during neuronal differentiation are repressed by the Null chromatin state and a novel TrxG-repressive state in neural stem cells (NSCs). Furthermore, almost all key NSC genes are switched off via a direct transition to HP1-mediated repression. In contrast to previous studies of ES cell to neural progenitor cell development, PcG-mediated repression does not play a significant role in regulating either of these transitions; instead, PcG chromatin specifically regulates lineage-specific transcription factors that control the spatial and temporal patterning of the brain. Combined, our data suggest that forms of chromatin other than canonical PcG/TrxG transitions take over key roles during neural development.
Project description:Neural stem cells were sorted according to their activated or quiescent state by flow cytometry using a set of 3 markers (LeX, CD24 and EGFR) We used microarrays to detail the global programme of gene expression underlying the proliferation/quiescence balance.
Project description:Arginine methylation of histones plays a critical role in regulating gene expression. The writers (methyltransferases) and readers of methylarginine marks are well-known, but the erasers－arginine demethylases－remain mysterious. Here we identify Myc-induced nuclear antigen 53 (Mina53), a jumonji C domain containing protein, as an arginine demethylase for removing asymmetric di-methylation at arginine 3 of histone H4 (H4R3me2a). Using photoaffinity capture method, we first identified Mina53 as an interactor of H4R3me2a. Biochemical assays in vitro and in cells characterized the arginine demethylation activity of Mina53. Molecular dynamics simulations provide further atomic-level evidence that Mina53 acts on H4R3me2a. In a transgenic mouse model, specific Mina53 deletion in neural stem/progenitor cells prevented H4R3me2a demethylation at distinct genes clusters, dysregulating genes important for neural stem/progenitor cell proliferation and differentiation, and consequently impairing the cognitive function of mice. Collectively, we identify Mina53 as a bona fide H4R3me2a eraser, expanding the understanding of epigenetic gene regulation.
Project description:Neural stem cells reside in a hypoxic microenvironment within the brain. However, the crucial transcription factors that regulate neural stem cell biology under physiologic hypoxia are poorly understood. Here, we have performed microarray analysis of hypoxic versus normoxic neural stem cells with the aim of identifying pathways and transcription factors that are activated under oxygen concentrations mimicking normal brain tissue microenvironment.
Project description:Genome-wide maps of chromatin state (H3K4me3, H3K9me3, H3K27me3, H3K36me3, H4K20me3) in pluripotent and lineage-committed cells We report the application of single-molecule-based sequencing technology for high-throughput profiling of histone modifications in mammalian cells. By obtaining over four billion bases of sequence from chromatin immunoprecipitated DNA, we generated genome-wide chromatin-state maps of mouse embryonic stem cells, neural progenitor cells and embryonic fibroblasts. We find that lysine 4 and lysine 27 trimethylation effectively discriminates genes that are expressed, poised for expression, or stably repressed, and therefore reflect cell state and lineage potential. Lysine 36 trimethylation marks primary coding and non-coding transcripts, facilitating gene annotation. Trimethylation of lysine 9 and lysine 20 is detected at satellite, telomeric and active long-terminal repeats, and can spread into proximal unique sequences. Lysine 4 and lysine 9 trimethylation marks imprinting control regions. Finally, we show that chromatin state can be read in an allele-specific manner by using single nucleotide polymorphisms. This study provides a framework for the application of comprehensive chromatin profiling towards characterization of diverse mammalian cell populations. Histone H3 or H4 tri-methylation ChIP-Seq in singlicate from murine embryonic stem (ES) cells, ES-derived neural precursor cells, and embryonic fibroblasts.
Project description:Setdb1 is an epigenetic factors catalyzing modification of H3K9me3. Expression of its gene is localized to embryonic neural cells during vertebrate embryogenesis, suggesting its role in regulating neural stemness. The project is to identify the interaction partners of Setdb1, by which Setdb1 regulates neural stemness in neural stem cells.
Project description:Ectopic expression of the reprogramming factors OCT4, SOX2, or NANOG into human astrocytes in specific cytokine/culture conditions activated the neural stem gene program and induced generation of cells expressing neural stem/precursor markers. Here we compare the whole gene expression profile of primary human astrocytes (Astro) with neural stem cells (HNSC) derived from astrocytes reprogramming
