Fast-spiking (FS) interneurons are important elements of neocortical circuitry that constitute the primary source of synaptic inhibition in adult cortex and impart temporal organization on ongoing cortical activity. The highly specialized intrinsic membrane and firing properties that allow cortical FS interneurons to perform these functions are attributable to equally specialized gene expression, which is ultimately coordinated by cell-type-specific transcriptional regulation. Although embryonic transcriptional events govern the initial steps of cell-type specification in most cortical interneurons, including FS cells, the electrophysiological properties that distinguish adult cortical cell types emerge relatively late in postnatal development, and the transcriptional events that drive this maturational process are not known. To address this, we used mouse whole-genome microarrays and whole-cell patch clamp to characterize the transcriptional and electrophysiological maturation of cortical FS interneurons between postnatal day 7 (P7) and P40. We found that the intrinsic and synaptic physiology of FS cells undergoes profound regulation over the first 4 postnatal weeks and that these changes are correlated with primarily monotonic but bidirectional transcriptional regulation of thousands of genes belonging to multiple functional classes. Using our microarray screen as a guide, we discovered that upregulation of two-pore K leak channels between P10 and P25 contributes to one of the major differences between the intrinsic membrane properties of immature and adult FS cells and found a number of other candidate genes that likely confer cell-type specificity on mature FS cells.
Transcriptional and electrophysiological maturation of neocortical fast-spiking GABAergic interneurons.
Specimen part
View SamplesThe mammalian forebrain is a tissue of stunning complexity comprised of numerous regions each containing many distinct cell types that differ in their intrinsic and synaptic physiology, morphology and connectivity. These differences are likely conferred by differential gene expression, but the extent and nature of cell type specific gene expression is largely unknown. Here, we carried out microarray analysis of twelve major classes of fluorescently labelled neurons within the forebrain and provide the first comprehensive view of gene expression differences. The results demonstrate a profound molecular heterogeneity among neuronal subtypes, represented disproportionately by gene paralogs, and begin to reveal the genetic programs underlying the fundamental divisions between neuronal classes including that between glutamatergic and GABAergic neurons.
Molecular taxonomy of major neuronal classes in the adult mouse forebrain.
Sex, Specimen part
View SamplesMutations in methyl-CpG-binding protein 2 (MeCP2) cause Rett syndrome and related autism spectrum disorders. MeCP2 is believed to be required for proper regulation of brain gene expression, but prior microarray studies in Mecp2 knockout mice using brain tissue homogenates have revealed only subtle changes in gene expression. Here, by profiling discrete subtypes of neurons we uncovered more dramatic effects of MeCP2 on gene expression, overcoming the "dilution problem" associated with assaying homogenates of complex tissues. The results reveal misregulation of genes involved in neuronal connectivity and communication. Importantly, genes up-regulated following loss of MeCP2 are biased toward longer genes but this is not true for down-regulated genes, suggesting MeCP2 may selectively repress long genes. Since genes involved in neuronal connectivity and communication, such as cell adhesion and cell-cell signaling genes, are enriched among longer genes, their misregulation following loss of MeCP2 suggests a possible etiology for altered circuit function in Rett syndrome.
Cell-type-specific repression by methyl-CpG-binding protein 2 is biased toward long genes.
Sex, Age, Specimen part
View SamplesThere is a continuing need for driver strains to enable cell type-specific manipulation in the nervous system. Each cell type expresses a unique set of genes, and recapitulating expression of marker genes by BAC transgenesis or knock-in has generated useful transgenic mouse lines. However since genes are often expressed in many cell types, many of these lines have relatively broad expression patterns. We report an alternative transgenic approach capturing distal enhancers for more focused expression. We identified an enhancer trap probe often producing restricted reporter expression and developed efficient enhancer trap screening with the PiggyBac transposon. We established more than 200 lines and found many lines that label small subsets of neurons in brain substructures, including known and novel cell types. Images and other information about each line are available online (http://enhnacertrap.bio.brandeis.edu). Overall design: Examination of 6 cortical mouse neuronal cell types. 5 of which are in layer 6 in 3 different cortical regions.
A Mammalian enhancer trap resource for discovering and manipulating neuronal cell types.
Sex, Cell line, Subject
View SamplesThis SuperSeries is composed of the SubSeries listed below.
A specific LSD1/KDM1A isoform regulates neuronal differentiation through H3K9 demethylation.
Cell line
View SamplesObesity has been shown to increase risk for cardiovascular disease and type-2 diabetes. In addition, it has been implicated in aggravation of neurological conditions such as Alzheimer's. In the model organism Drosophila melanogaster, a physiological state mimicking diet-induced obesity can be induced by subjecting fruit flies to a solid medium disproportionately higher in sugar than protein (HSD) or that has been supplemented with a rich source of saturated fat (HFD). These flies can exhibit increased circulating glucose levels, increased triglyceride content, insulin-like peptide resistance, and behavior indicative of neurological decline, such as decreased climbing ability. We subjected Oregon-R-C flies to variants of the HSD, HFD, or normal (control) diet (ND), followed by a total RNA extraction from fly heads of each diet group for the purpose of Poly-A selected RNA-Sequencing. We targeted at least 50 million paired-end, stranded reads of 75 basepairs in size, and analyzed 4 biological replicates per dietary condition. Our objective was to identify the effects of obesogenic diets on transcriptome patterns, how they differed between obesogenic diets, and identify genes that may relate to pathogenesis accompanying an obesity-like state. Functional annotation and enrichment analysis among genes whose expression was significantly affected by the obesogenic diets indicated an overrepresentation of genes associated with immunity, metabolism, and hemocyanin in the HFD group, and CHK, cell cycle activity, and DNA binding and transcription in the HSD group. Heat map representation of genes affected by both diets illustrated a large fraction of differentially expressed genes between the two diet groups. Diets high in sugar and diets high in fat both have notableeffects on the Drosophila transcriptome in head tissue. The impacted genes, and how they may relate to pathogenesis in the Drosophila obesity-like state, warrant further experimental investigation. Our results also indicate differences in the effects of the HFD and HSD on expression profiles in head tissue of Oregon-R-C flies, despite the reportedly similar phenotypic impacts of the diets. Overall design: Flies were reared on one of three diets (high fat, high sugar, or normal). 6 replicates, with twenty flies each, from each diet treatment were collected for a total of 18 samples. The heads of the flies were then obtained, and RNA extracted from each of those samples. 4 of the RNA samples from each diet group (12 samples total) were sequenced.
RNA-Sequencing of <i>Drosophila melanogaster</i> Head Tissue on High-Sugar and High-Fat Diets.
Specimen part, Subject
View SamplesMouse embryonic fibroblasts (MEFs) were generated from 13.5-day-old embryos obtained from heterozygous PKBa mice intercrosses (Yang et al., 2003). Briefly, after dissection of head and visceral organs for genotyping, embryos were minced and trypsinized for 30 min at 37C. Embryonic fibroblasts were then plated and maintained in Dulbeccos Modified Eagle Medium (DMEM) with 10% foetal calf serum (FCS) (Life Technologies), 100 units/ml of penicillin and 100 mg/ml of streptomycin at 37C in an atmosphere of 5% CO2. All experiments were performed with wild-type and PKBa-/- MEFs between 15-20 passages. To induce adipocyte differentiation, 2-day-postconfluent cells (day 0) were treated with DMEM supplemented with 10% FCS, 8 mg/ml biotin, 4 mg/ml pantothenate, 0.5 mM 3-isobutyl-1-methylxanthine, 1 mM dexamethasone and 10 mg/ml insulin (all from Sigma). Total RNA was extracted from cells using TRIzol (Invitrogen) according to the manufacturers instructions.
PKBalpha is required for adipose differentiation of mouse embryonic fibroblasts.
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View SamplesThe thymus constitutes the primary lymphoid organ for the majority of T cells. The phosphatidyl-inositol 3 kinase (PI3K) signaling pathway is involved in lymphoid development. Defects in single components of this pathway prevent thymocytes from progressing beyond early T cell developmental stages. Protein kinase B (PKB) is the main effector of the PI3K pathway. To determine whether PKB mediates PI3K signaling in early T cell development, we characterized PKB knockout thymi. Our results reveal a significant thymic hypocellularity in PKBalpha-/- neonates and an accumulation of early thymocyte subsets in PKBalpha-/- adult mice. The latter finding is specifically attributed to the lack of PKBalpha within the lymphoid component of the thymus. Microarray analyses show that the absence of PKBalpha in early thymocyte subsets modifies the expression of genes known to be involved in pre-TCR signaling, in T cell activation, and in the transduction of interferon-mediated signals. This report highlights the specific requirements of PKBalpha for thymic development.
Deletion of PKBalpha/Akt1 affects thymic development.
Sex, Age, Specimen part
View SamplesGlioblastoma multiforme (GBM) is the most malignant and most common tumor of the central nervous system characterized by rapid growth and extensive tissue infiltration. GBM results in more years of life lost than any other cancer type. Notch signaling has been implicated in GBM pathogenesis through several modes of action. Inhibition of Notch leads to a reduction of cancer-initiating cells in gliomas and reduces proliferation and migration. Deltex1 (DTX1) is part of an alternative Notch signaling pathway distinct from the canonical MAML1/RBPJ-mediated cascade. In this study, we show that DTX1 activates both the RTK/PI3K/PKB as well as the MAPK/ERK pathway. Moreover, we found the anti-apoptotic factor Mcl-1 to be induced by DTX1. In accordance with this, the clonogenic potential and proliferation rates of glioma cell lines correlated with DTX1 levels. DTX1 knock down mitigated the tumorigenic potential in vivo, and overexpression of DTX1 increased cell migration and invasion of tumor cells accompanied by an elevation of the pro-migratory factors PKB and Snail1. Microarray gene expression analysis identified a DTX1-specific transcriptional program - including microRNA-21 - which is distinct from the canonical Notch signaling. We propose the alternative Notch pathway via DTX1 as oncogenic factor in malignant glioma and found low DTX1 expression levels to correlate with prolonged survival of GBM and early breast cancer patients in open source databases.
Deltex-1 activates mitotic signaling and proliferation and increases the clonogenic and invasive potential of U373 and LN18 glioblastoma cells and correlates with patient survival.
Specimen part, Cell line
View SamplesTo identify signaling pathways that are differentially regulated in human gliomas, a microarray analysis on 30 brain tumor samples (12 primary glioblastomas (GBM), 3 secondary glioblastomas (GBM-2), 8 astrocytomas (Astro) and 7 oligodendrogliomas (Oligo)) and on 5 glioblastoma cell lines (LN018, LN215, LN229, LN319 and BS149) was performed. Normal brain tissue (NB) and normal human astrocytes (NHA) were used as a control. Kinase expression in each tumor was compared to expression in normal brain and expression values from normal human astrocytes were used as an additional control.
MAP kinase-interacting kinase 1 regulates SMAD2-dependent TGF-β signaling pathway in human glioblastoma.
Sex, Age, Specimen part, Disease stage, Cell line
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