Generation of oligodendroglial cells by direct lineage conversion
ABSTRACT: We report the generation of induced oligodendrocyte precursor cells (iOPCs) by direct lineage conversion. Forced expression of the three transcription factors Sox10, Olig2 and Zfp536 was sufficient to convert mouse and rat fibroblasts into iOPCs with morphologies and gene expression signatures that resemble OPCs. We compared the global gene expression pattern of iOPCs, fibroblasts, primary OPCs from the neonatal rat brain, and their differentiated progeny. We purified iOPCs by O4 immunopanning three weeks after infection and extracted total RNA. Acutely isolated rat cortical OPCs were either used directly for RNA extraction or expanded in mitogen-containing media for 24h before switching into differentiation medium, lacking PDGF/NT-3 and containing T3. Cells were harvested for microarray analysis 3 and 6 days after induction of differentiation.
Project description:Primary mixed glial cultures were prepared from dissociated cerebral cortices of Sprague-Dawley rats at postnatal day 1 to 3 and glial populations were isolated by sequential rotary shaking procedures using well-established protocols. Cultured cells were exposed to 1 micromol dexamethasone for 24hours prior to RNA isolation. Control samples were exposed to equal volume of carrier. For each cell type, RNA samples from four cultures were dispatched to Source Bioscience UK Ltd. (Nottingham) for processing and hybridisation. RNA integrity was determined using the Bioanalyzer (Agilent) and the three RNA samples with the highest quality per condition were selected for microarray analysis. 750ng of processed cRNA was hybridised to Illumina RatRef-12 bead chips.
Project description:To identify factors involved in glioma-initiating cells (GICs), we compared gene expressions between GIC-like cells and non-GICs. p53-deficient Neural stem cells (NSCs), oligodendrocyte precursor cells (OPCs), and astrocytes (ASTs) were transfected with pCMS-EGFP-HRasL61 and pBabe-neo by electroporation and cultured in 0.5 mg/ml neomycin. The GFP-positive stable NSCs (NSCL61s), OPCs (OPCL61s) and ASTs (ASTL61s) were purified by flow cytometry. Total RNA was prepared using a RNeasy Mini Kit (QIAGEN) and used for the expression analysis.
Project description:Stem cell biology has garnered much attention due to its potential to impact human health through disease modeling and cell replacement therapy. This is especially pertinent to myelin-related disorders such as multiple sclerosis and leukodystrophies where restoration of normal oligodendrocyte function could provide an effective treatment. Progress in myelin repair has been constrained by the difficulty in generating pure populations of oligodendrocyte progenitor cells (OPCs) in sufficient quantities. Pluripotent stem cells theoretically provide an unlimited source of OPCs but significant advances are currently hindered by heterogeneous differentiation strategies that lack reproducibility. Here we provide a platform for the directed differentiation of pluripotent mouse epiblast stem cells (EpiSCs) through a defined series of developmental transitions into a pure population of highly expandable OPCs in ten days. These OPCs robustly differentiate into myelinating oligodendrocytes both in vitro and in vivo. Our results demonstrate that pluripotent stem cells can provide a pure population of clinically-relevant, myelinogenic oligodendrocytes and offer a tractable platform for defining the molecular regulation of oligodendrocyte development, drug screening, and potential cell-based remyelinating therapies. 6 total samples were analyzed. Pluripotent epiblast stem cells (EpiSCs) were differentiated to patterned neural rosettes, oligodendrocyte progenitor cells (OPCs), and oligodendrocytes. OPCs and oligodedrocytes were analyzed at two separate passages (3 and 11).
Project description:We performed genome-wide profiling of Tcf7l2 occupancy during oligodendrocyte differentiation and identified the key enzymes involved in cholesterol metabolism and essential for CNS myelination. Examination of Tcf7l2 chIP-seq in oligodendrocyte progenitor cell and 2 differentiation oligodendrocytes.
Project description:Establishment and maintenance of CNS glial cell identity ensures proper brain development and function, yet the epigenetic mechanisms underlying glial fate control remain poorly understood. Here we show that the histone deacetylase Hdac3 controls oligodendrocyte-specification gene Olig2 expression, and functions as a molecular switch for oligodendrocyte and astrocyte lineage determination. Our data suggest that Hdac3 cooperates with p300 to prime and maintain oligodendrogenic programs while inhibiting Stat3-mediated astrogliogenesis, and thereby regulate phenotypic commitment at the point of oligodendrocyte-astrocytic fate decision. Examination of Hdac3 and p300 genomewide occupancy in differentiating oligodendrocytes
Project description:A Transcriptome Database for Astrocytes, Neurons, and Oligodendrocytes: A New Resource for Understanding Brain Development and Function Understanding the cell-cell interactions that control CNS development and function has long been limited by the lack of methods to cleanly separate astrocytes, neurons, and oligodendrocytes. Here we describe the first method for the isolation and purification of developing and mature astrocytes from mouse forebrain. This method takes advantage of the expression of S100β by astrocytes. We used fluorescent activated cell sorting (FACS) to isolate EGFP positive cells from transgenic mice that express EGFP under the control of an S100β promoter. By depletion of astrocytes and oligodendrocytes we obtained purified populations of neurons, while by panning with oligodendrocyte-specific antibodies we obtained purified populations of oligodendrocytes. Using GeneChip Arrays we then created a transcriptome database of the expression levels of over 20,000 genes by gene profiling these three main CNS neural cell types at postnatal ages day 1 to 30. This database provides the first global characterization of the genes expressed by mammalian astrocytes in vivo and is the first direct comparison between the astrocyte, neuron, and oligodendrocyte transcriptomes. We demonstrate that Aldh1L1, a highly expressed astrocyte gene, is a highly specific antigenic marker for astrocytes with a substantially broader, and therefore potentially more useful, pattern of astrocyte expression than the traditional astrocyte marker GFAP. This transcriptome database of acutely isolated and highly pure populations of astrocytes, neurons and oligodendrocytes provides a resource to the neuroscience community by providing improved cell type specific markers and for better understanding of neural development, function, and disease. We acutely purified mouse astrocytes from early postnatal ages (P1) to later postnatal ages (P30), when astrocyte differentiation is morphologically complete (Bushong et al., 2004), and acutely purified mouse OL-lineage cells from stages ranging from OPCs to newly differentiated OLs to myelinating OLs. We extracted RNA from each of these highly purified, acutely isolated cell types and used GeneChip Arrays to determine the expression levels of over 20,000 genes and construct a comprehensive database of cell type specific gene expression in the mouse forebrain. Analysis of this database confirms cell type specific expression of many well characterized and functionally important genes. In addition, we have identified thousands of new cell type enriched genes, thereby providing important new information about astrocyte, OL, and neuron interactions, metabolism, development, and function. This database provides a comparison of the genome-wide transcriptional profiles of the main CNS cell types and is a resource to the neuroscience community for better understanding the development, physiology, and pathology of the CNS. Keywords: Developmental CNS Cell type comparision FACS purification of astrocytes: Dissociated forebrains from S100β-EGFP mice were resuspended in panning buffer (DBPS containing 0.02% BSA and 12.5 U/ml DNase) and sequentially incubated on the following panning plates: secondary antibody only plate to deplete microglia, O4 plate to deplete OLs, PDGFRα plate to deplete OPCs, and a second O4 plate to deplete any remaining OLs. This procedure was sufficient to deplete all OL-lineage cells from animals P8 and younger, however, in older animals that had begun to myelinate, additional depletion of OLs and myelin debris was accomplished as follows. The nonadherent cells from the last O4 dish were harvested by centrifugation, and the cells were resuspended in panning buffer containing GalC, MOG, and O1 supernatant and incubated for 15 minutes at room temperature. The cell suspension was washed and then resuspended in panning buffer containing 20 μg donkey anti-mouse APC for 15 minutes. The cells were washed and resuspended in panning buffer containing propidium iodide (PI). EGFP+ astrocytes were then purified by fluorescence activated cell sorting (FACS). Dead cells were gated out using high PI staining and forward light scatter. Astrocytes were identified based on high EGFP fluorescence and negative APC fluorescence from indirect immunostaining for OL markers GalC, MOG, and O1. Cells were sorted twice and routinely yielded >99.5% purity based on reanalysis of double sorted cells.; FACS purification of neurons: EGFP- cells were the remaining forebrain cells after microglia, OLs, and astrocytes had been removed, and were primarily composed of neurons, and to a lesser extent, endothelial cells (we estimate < 4% endothelial cells at P7 and < 20% endothelial cells at P17). EGFP- cells from S100β-EGFP dissociated forebrain were FACS purified in parallel with astrocyte purification and were sorted based on their negative EGFP fluorescence immunofluorescence. Cells were sorted twice and routinely yielded >99.9% purity. In independent preparations, the EGFP- cell population was additionally depleted of endothelial cells and pericytes by sequentially labeling with biotin-BSL1 lectin and streptavidin-APC while also labeling for OL markers as described above. Cells were sorted twice and routinely yielded >99.9% purity.; Panning purification of oligodendrocyte lineage cells: Dissociated mouse forebrains were resuspended in panning buffer. In order to deplete microglia, the single-cell suspension was sequentially panned on four BSL1 panning plates. The cell suspension was then sequentially incubated on two PDGFRα plates (to purify and deplete OPCs), one A2B5 plate (to deplete any remaining OPCs), two MOG plates (to purify and deplete myelinating OLs), and one GalC plate (to purify the remaining PDGFRα-, MOG-, OLs). The adherent cells on the first PDGFRα, MOG, and GalC plates were washed to remove all antigen-negative nonadherent cells. The cells were then lysed while still attached to the panning plate with Qiagen RLT lysis buffer, and total RNA was purified. Purified OPCs were >95% NG2 positive and 0% MOG positive. Purified Myelin OLs were 100% MOG positive, >95% MBP positive, and 0% NG2 positive. Purified GalC OLs depleted of OPCs and Myelin OLs were <10% MOG positive and ~50% weakly NG2 positive, a reflection of their recent development as early OLs.; Data normalization and analysis: Raw image files were processed using Affymetrix GCOS and the MAS 5.0 algorithm. Intensity data was normalized per chip to a target intensity TGT value of 500, and expression data and absent/present calls for individual probe sets were determined. Gene expression values were normalized and modeled across arrays using the dChip software package with invariant-set normalization and a PM model. (www.dchip.org, Li and Wong, 2001). The 29 samples were grouped into 9 sample types: Astros P7-P8, Astros P17, Astros P17-gray matter (P17g), Neurons P7, Neurons P17, Neurons-endothelial cell depleted (P7n, P17n), OPCs, GalC-OLs, and MOG-OLs. Gene filtering was performed to select probe sets that were consistently expressed in at least one cell type, where consistently expressed was defined as being called present and having a MAS 5.0 intensity level greater than 200 in at least two-thirds of the samples in the cell type. We identified 20,932 of the 45,037 probe sets that were consistently expressed in at least one of the nine cell types. The Significance Analysis of Microarrays (SAM) method (Tusher et al., 2001) was used to determine genes that were significantly differentially expressed between different cell types (see Supplemental Table S2 for SAM cell type groupings). Clustering was performed using the hclust method with complete linkage in R. Expression values were transformed for clustering by computing a mean expression value for the gene using those samples in the corresponding SAM statistical analysis, and then subtracting the mean from expression intensities. In order to preserve the log2 scale of the data, unless otherwise indicated, no normalization by variance was performed. Plots were created using the gplots package in R. The Bioconductor software package (Gentleman et al., 2004) was used throughout the expression analyses. Functional analyses were performed through the use of Ingenuity Pathways Analysis (Ingenuity® Systems, www.ingenuity.com).
Project description:Many studies have already shown the reprogramming of somatic cells into other cell types such as neural stem cells, blood progenitor cells, and hepatocytes by inducing combinations of transcription factors. One of the recent development in cellular reprogramming is the direct reprogramming, that can change cell fate towards different lineages. This strategy provides an alternative to the use of pluripotent stem cells ruling out the concerns of tumorigenicity caused by undifferentiated cell populations. Here, we generated induced oligodendrocyte progenitor cells (iOPCs) from mouse fibroblasts by direct reprogramming. The generated iOPCs are homogenous, self-renewing, and multipotent. Once differentiated, the somatic stem cells exhibit morphological and molecular characteristics of oligodendrocyte progenitor cells (OPCs). Thus, we demonstrated that terminally differentiated somatic cells can be converted into functional iOPCs by induction of transcription factors offering a new strategies to cure myelin disorders. To identify the global gene expression profiles of iOPCs, we analyzed total 6 samples.
Project description:Purpose: Chronic infection with hepatitis B virus is the leading global risk factor for the development of liver cancer. A large body of research has shown the many effects an HBV infection has on cellular physiology, particularly on pathways that may be involved in the development of HBV-associated diseases. Unfortunately, a significant portion of this research has been done in systems that may not mimic what is seen in a primary hepatocyte, and is not done on a transcriptome-wide scale. Because of this, we performed an RNA-seq analysis of primary rat hepatocytes expressing HBV to determine the global changes HBV has on primary hepatocyte physiology. Methods: To do this RNA-seq analysis, triplicate samples of total RNA were collected from cultured primary rat hepatocytes infected with adenovirus expressing GFP alone (AdGFP) or GFP along with a greater than unit length copy of the HBV genome (AdHBV). Samples were collected either 24h or 48h after infection. cDNA libraries were sequenced two times using the Illumina HiSeq or Illumina NextSeq platform to generate either 1x50bp or 1x75bp reads. Reads from each sequencing run were mapped using the STAR aligner, and output BAMs were merged into a single BAM for each sample. The merged BAM was further analyzed in R using the GenomicAlignments package to quantify number of reads per transcript and DESeq2 to determine differential expression. Reads per kilobase transcript per million total reads (RPKM) was calculated by dividing reads per transcript by the transcript length and then normalizing to the total number of reads in the sample. Results: Following this pipeline, we were able to identify a number of HBV-mediated differentially expressed transcripts at 24h and 48h post-infection. Further pathway analysis of these differentially expressed transcripts identified many important cellular pathways, including those involved with cell cycle regulation and metabolism, as being differentially regulated by HBV in primary hepatocytes. mRNA profiles of HBV-expressing and non-expressing primary rat hepatocytes were generated, in triplicate, 24h and 48h post-infection using Illumina HiSeq 2500 and NextSeq 500 instruments.