Expression data from mouse proprioceptive sensory neuron subclasses.
ABSTRACT: Proprioception relies on two main classes of proprioceptive sensory neurons (pSNs). These neurons innervate two distinct peripheral receptors in muscle, muscle spindles (MSs) or Golgi tendon organs (GTOs), and synapse onto different sets of spinal targets, but the molecular basis of their distinct pSN subtype identity remains unknown. We used microarray analysis to compare gene expression profiles between MS- and GTO- innervating proprioceptors. We generated transgenic mice in which MS and GTO pSNs are labelled with different fluorescent proteins (see de Nooij et al., 2015 for details). We used Fluorescent Activated Cell Sorting (FACS) to isolate the MS and GTO pSN subsets from dissociated DRG from p7-10 transgenic mice. Neurons from multiple FACS experiments were pooled into three samples each for the MS and GTO pSN subset.
Project description:The goal of this study was to analyze global gene expression in specific populations of somatosensory neurons in the periphery, including major, non-overlapping populations that include nociceptors, pruriceptors, and prorioceptors. The mammalian somatosensory nervous system encodes the perception of specific environmental stimuli. The dorsal root ganglion (DRG) contains distinct somatosensory neuron subtypes that innervate diverse peripheral tissues, mediating the detection of thermal, mechanical, proprioceptive, pruriceptive, and nociceptive stimuli. We purified discrete subtypes of mouse DRG somatosensory neurons by flow cytometry using fluorescently labeled mouse lines (SNS-Cre/TdTomato, Parv-Cre/TdTomato) in combination with Isolectin B4-FITC surface staining (IB4). This allowed identification of transcriptional differences between these major populations, revealing enrichment of voltage-gated ion channels, TRP channels, G-protein coupled receptors, transcription factors, and other functionally important classes of genes within specific somatosensory neuron subsets. SNS-Cre mice were bred with Rosa26-TdTomato mice to generate SNS-Cre/TdTomato reporter mice. Parv-Cre mice were bred with Rosa26-TdTomato mice to generate Parv-Cre/TdTomato mice. Isolectin B4-FITC was used to stain the surface of SNS-Cre/TdTomato reporter mice. We used these strategies of fluorescent labeling to purify distinct murine sensory neuron subsets from the dorsal root ganglia (DRG) by fluorescence activated cell sorting (FACS). Neurons were sorted directly in Qiazol for total RNA extraction and microarray analysis. Whole DRG tissue was also included for transcriptome analysis to compare with purified neuronal populations.
Project description:Here we identified two populations of myelinated sensory neurons that display markedly different phenotypes in terms of their action potential characteristics and responses to mechanical stimuli based on their expression of Calcitonin Gene-Related Peptide (CGRP). Myelinated neurons that did not express CGRP responded to mechanical stimuli with significantly larger currents during whole-cell voltage clamp recordings than their CGRP-positive counterparts, regardless of whether these neurons projected to the dorsal hindpaw skin or the gastrocnemius muscle. Importantly, this discrepancy could not be explained by a differential expression of mechanosensitive or mechanically-gated proteins like Stoml3 or Piezo2. Following inflammation of the skin or muscle, myelinated neurons demonstrated a sensitization to mechanical stimuli characterized by increased current amplitudes. Interestingly, myelinated neurons expressing CGRP are sensitized to mechanical stimuli following cutaneous inflammation of the paw, while myelinated neurons that do not express CGRP are sensitized to mechanical stimuli following inflammation of the gastrocnemius muscle. Microarray data was obtained from these populations by first using Fluorescence-Activated Cell Sorting (FACS) to separate the populations of interest. 15 different samples were analyzed, 3 biological replicates for each group (5 groups: saline paw-injected, CFA paw-injected, saline muscle-injected, acid muscle-injected, and CFA muscle-injected). The saline injected groups (paw and muscle) are considered controls.
Project description:Transcriptional analysis of identified DRG subpopulations. Cell-type specific intrinsic programs instruct neuronal subpopulations before target-derived factors influence later neuronal maturation. Retrograde neurotrophin signaling controls neuronal survival and maturation of dorsal root ganglion (DRG) sensory neurons, but how these potent signaling pathways intersect with transcriptional programs established at earlier developmental stages remains poorly understood. Here we determine the consequences of genetic alternation of NT3 signaling on genome-wide transcription programs in proprioceptors, an important sensory neuron subpopulation involved in motor reflex behavior. We find that the expression of many proprioceptor-enriched genes is dramatically altered by genetic NT3 elimination, independent of survival-related activities. Combinatorial analysis of gene expression profiles with proprioceptors isolated from mice expressing surplus muscular NT3 identifies an anticorrelated gene set with transcriptional levels scaled in opposite directions. Voluntary running experiments in adult mice further demonstrate the maintenance of transcriptional adjustability of genes expressed by DRG neurons, pointing to life-long gene expression plasticity in sensory neurons. We combined a mouse line expressing GFP under the control of the TrkC promoter (BAC transgene approach) with various NT3 signaling mutants in order to identify the transcriptional changes in identified subpopulations of dorsal root ganglia (DRG) neurons. Sorted cells were processed for RNA extraction and hybridization on Affymetrix microarrays. Analysis was performed a postnatal (p) day p0. Subsequent analysis focused on the transcriptional profile of DRG neuron subpopulations at specific lumbar levels. Additional work addressed the transcriptional changes in whole DRG in adult mice with and without physical exercise.
Project description:Metzincin metalloproteases have major roles in intercellular communication by modulating the function of membrane proteins. One of the proteases is the a-disintegrin-and-metalloprotease 10 (ADAM10) which acts as alpha-secretase of the Alzheimer’s disease amyloid precursor protein. ADAM10 is also required for neuronal network functions in murine brain, but neuronal ADAM10 substrates are only partly known. With a proteomic analysis of Adam10-deficient neurons we identified 91, mostly novel ADAM10 substrate candidates, making ADAM10 a major protease for membrane proteins in the nervous system. Several novel substrates, including the neuronal cell adhesion protein NrCAM, are involved in brain development. Indeed, we detected mistargeted axons in the olfactory bulb of conditional ADAM10-/- mice, which correlate with reduced cleavage of NrCAM, NCAM and other ADAM10 substrates. In summary, the novel ADAM10 substrates provide a potential molecular basis for neuronal network dysfunctions in conditional ADAM10-/- mice and demonstrate a fundamental function of ADAM10 as a sheddase in the brain.
Project description:Primary afferent collateral sprouting (PACS) is a process whereby non-injured primary afferent neurons respond to some stimulus by extending new branches from existing axons. In the model used here (spared dermatome), the intact sensory neurons respond to the denervation of adjacent areas of skin by sprouting new axon branches into that adjacent denervated territory. Neurons of both the central and peripheral nervous systems undergo this process, which contributes to both adaptive and maladaptive plasticity. Investigations of gene expression changes associated with PACS can provide a better understanding of the molecular mechanisms controlling this process. Consequently, it can be used to develop treatment for spinal cord injury to promote functional recovery. In this study, we sought to identify gene expression changes in PACS using 20 Affymetrix Rat Genome 230 2.0 microarrays. The experiments were designed to discover global gene expression changes in non-injured DRG neurons undergoing PACS. T11 DRG neurons remained intact and undergo PACS after the cutaneous nerves of the adjacent segments (T9, T10, T12, and T13) were injured and regeneration of those injured nerves prevented by ligation. Thus, the T9, T10, T12, and T13 dermatomes were denervated, but the T11 dermatome remained intact. Axons of the T11dermatome (and thus housed in the T11 dorsal root ganglion (DRG)), extended new branches to innervate the T9, T10, T12, and T13 dermatomes. N.B.: This is NOT a spared root experiment. ALL spinal roots were non-injured. Peripheral nerves were used. A total of 20 Affymetrix Rat Genome 230 2.0 microarrays were analyzed: six naïve controls, seven replicates at day 7 post-surgery (presumed to represent an “initiation phase”), and seven replicates at day 14 post-surgery (presumed to represent a “maintenance phase”). DRGs were NOT pooled onto microarrays. Each animal had its own microarray with T11 DRG sample which underwent 2-round amplification. After quality control analysis, one of the naïve control microarrays was removed from further analysis.
Project description:Newborn neurons enter an extended maturation stage, during which they acquire excitability characteristics crucial for development of presynaptic and postsynaptic connectivity. In contrast to earlier specification programs, little is known aboutthe regulatory mechanisms that control neuronal maturation. The Pet-1 ETS (E26 transformation-specific) factor is continuously expressed in serotonin (5-HT) neurons and initially acts in postmitotic precursors to control acquisition of 5-HT transmitter identity. Using a combination of RNA sequencing, electrophysiology, and conditional targeting approaches, we determined gene expression patterns in maturing flow-sorted 5-HT neurons and the temporal requirements for Pet-1 in shaping these patterns for functional maturation of mouse 5-HT neurons. We report a profound disruption of postmitotic expression trajectories in Pet-1 / neurons, which prevented postnatal maturation of 5-HT neuron passive and active intrinsic membrane properties, G-protein signaling, and synaptic responses to glutamatergic, lysophosphatidic, and adrenergic agonists. Unexpectedly, conditional targeting revealed a postnatal stage-specific switch in Pet-1 targets from 5-HT synthesis genes to transmitter receptor genes required for afferent modulation of 5-HT neuron excitability. 5-HT1a autoreceptor expression depended transiently on Pet-1, thus revealing an early postnatal sensitive period for control of 5-HT excitability genes. Chromatin immunoprecipitation followed by sequencing revealed that Pet-1 regulates 5-HT neuron maturation through direct gene activation and repression. Moreover, Pet-1 directly regulates the 5-HT neuron maturation factor Engrailed 1, which suggests Pet-1 orchestrates maturationthrough secondary postmitotic regulatoryfactors. The early postnatal switch in Pet-1targets uncovers a distinct neonatal stage-specific function for Pet-1, during which it promotes maturation of 5-HT neuron excitability. 5-HT neuron mRNA profiles of E11.5, E15.5, and postnatal (P1-P3) wild type (WT) and Pet-1-/- mice were generated by deep sequencing, in triplicate, using Illumina HiSeq 2500. Myc-tagged Pet-1 ChIP-seq was performed on E12.5 to E14.5 hindbrains and sequencing using NextSeq 500.
Project description:We evalueted gene expression in dorsal root ganglion (DRG) over-expressing NRG1 typeIII ICD (Intra Cellular Domain). DRG were infected with a lentivirus expressing ICD and compared to not infected DRG or DRG infected with a lentivirus expressing EGFP.
Project description:To study the changes in the gene expression during neuronal maturation we prepared dissociated cultures of the newborn mouse sympathetic superior cervical ganglia that were grown in vitro for 5 days (young neurons) or 21 days (mature neurons) and compared the pattern of gene expression in the young and mature neurons using Affymetrix Exon array technique. As the cultures contained non-neuronal cells, the young and mature non-neuronal cells without neurons were also included. The assay revealed 1310 significantly up-regulated and 1151 significantly down-regulated genes in the mature neurons compared to young ones.
Project description:Topoisomerases are necessary for the expression of neurodevelopmental genes, and are mutated in some patients with autism spectrum disorder (ASD). We have studied the effects of inhibitors of Topoisomerase 1 (Top1) and Topoisomerase 2 (Top2) enzymes on mouse cortical neurons. We find that topoisomerases selectively inhibit long genes (>100kb), with little effect on all other gene expression. Using ChIPseq against RNA Polymerase II (Pol2) we show that the Top1 inhibitor topotecan blocks transcriptional elongation of long genes specifically. Many of the genes inhibited by topotecan are candidate ASD genes, leading us to propose that topoisomerase inhibition might contribute to ASD pathology. 9 experiments, gene expression measured by Affymetrix microarray. 1) cultured mouse cortical neurons treated with 300nM topotecan vs vehicle-treated controls 2) cultured mouse neurons treated with 1uM topotecan vs vehicle-treated controls 3) cultured mouse cortical neurons treated with 3uM ICRF-193 vs vehicle-treated controls. 4) cultured mouse cortical neurons treated with 10 uM irinotecan vs vehicle-treated controls. 5) cultured mouse cortical neurons treated with 3-1000 nM topotecan vs vehicle treated controls 6) cultured mouse cortical neurons treated with lentivirus expressing shRNA against Top1 and Top2b vs scrambled shRNA controls 7) cultured mouse cortical neurons treated with DRB vs vehicle-treated controls 8) cultured mouse cortical neurons treated with hydrogen peroxide or paraquat vs vehicle-treated controls 9) cultured mouse cortical neurons treated with topotecan with or without subsequent drug washout, vs vehicle-treated controls.