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Heller DT, Kolson DR, Brandebura AN, Amick EM, Wan J, Ramadan J, Holcomb PS, Liu S, Deerinck TJ, Ellisman MH, Qian J, Mathers PH, Spirou GA. Astrocyte ensheathment of calyx-forming axons of the auditory brainstem precedes accelerated expression of myelin genes and myelination by oligodendrocytes. J Comp Neurol 2024; 532:e25552. [PMID: 37916792 PMCID: PMC10922096 DOI: 10.1002/cne.25552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 09/22/2023] [Accepted: 10/17/2023] [Indexed: 11/03/2023]
Abstract
Early postnatal brain development involves complex interactions among maturing neurons and glial cells that drive tissue organization. We previously analyzed gene expression in tissue from the mouse medial nucleus of the trapezoid body (MNTB) during the first postnatal week to study changes that surround rapid growth of the large calyx of Held (CH) nerve terminal. Here, we present genes that show significant changes in gene expression level during the second postnatal week, a developmental timeframe that brackets the onset of airborne sound stimulation and the early stages of myelination. Gene Ontology analysis revealed that many of these genes are related to the myelination process. Further investigation of these genes using a previously published cell type-specific bulk RNA-Seq data set in cortex and our own single-cell RNA-Seq data set in the MNTB revealed enrichment of these genes in the oligodendrocyte lineage (OL) cells. Combining the postnatal day (P)6-P14 microarray gene expression data with the previously published P0-P6 data provided fine temporal resolution to investigate the initiation and subsequent waves of gene expression related to OL cell maturation and the process of myelination. Many genes showed increasing expression levels between P2 and P6 in patterns that reflect OL cell maturation. Correspondingly, the first myelin proteins were detected by P4. Using a complementary, developmental series of electron microscopy 3D image volumes, we analyzed the temporal progression of axon wrapping and myelination in the MNTB. By employing a combination of established ultrastructural criteria to classify reconstructed early postnatal glial cells in the 3D volumes, we demonstrated for the first time that astrocytes within the mouse MNTB extensively wrap the axons of the growing CH terminal prior to OL cell wrapping and compaction of myelin. Our data revealed significant expression of several myelin genes and enrichment of multiple genes associated with lipid metabolism in astrocytes, which may subserve axon wrapping in addition to myelin formation. The transition from axon wrapping by astrocytes to OL cells occurs rapidly between P4 and P9 and identifies a potential new role of astrocytes in priming calyceal axons for subsequent myelination.
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Affiliation(s)
| | - Douglas R. Kolson
- WVU Rockefeller Neuroscience Institute, West Virginia University School of Medicine, Morgantown, WV
- Otolaryngology HNS, West Virginia University School of Medicine, Morgantown, WV
| | - Ashley N. Brandebura
- WVU Rockefeller Neuroscience Institute, West Virginia University School of Medicine, Morgantown, WV
- Biochemistry, West Virginia University School of Medicine, Morgantown, WV
| | - Emily M. Amick
- Medical Engineering, University of South Florida, Tampa, FL
| | - Jun Wan
- Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN
| | - Jad Ramadan
- Otolaryngology HNS, West Virginia University School of Medicine, Morgantown, WV
| | - Paul S. Holcomb
- WVU Rockefeller Neuroscience Institute, West Virginia University School of Medicine, Morgantown, WV
| | - Sheng Liu
- Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN
| | - Thomas J. Deerinck
- National Center for Microscopy and Imaging Research, University of California, San Diego, CA
- Department of Neuroscience, University of California, San Diego, CA
| | - Mark H. Ellisman
- National Center for Microscopy and Imaging Research, University of California, San Diego, CA
- Department of Neuroscience, University of California, San Diego, CA
| | - Jiang Qian
- Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, MD
| | - Peter H. Mathers
- WVU Rockefeller Neuroscience Institute, West Virginia University School of Medicine, Morgantown, WV
- Otolaryngology HNS, West Virginia University School of Medicine, Morgantown, WV
- Biochemistry, West Virginia University School of Medicine, Morgantown, WV
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2
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Nadei OV, Agalakova NI. Optimal Reference Genes for RT-qPCR Experiments in Hippocampus and Cortex of Rats Chronically Exposed to Excessive Fluoride. Biol Trace Elem Res 2024; 202:199-209. [PMID: 37010724 DOI: 10.1007/s12011-023-03646-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Accepted: 03/20/2023] [Indexed: 04/04/2023]
Abstract
Normalization of the quantitative real-time PCR (RT-qPCR) data to the stably expressed reference genes is critically important for obtaining reliable results. However, all previous studies focused on F- toxicity for brain tissues used a single, non-validated reference gene, what might be a cause of contradictory or false results. The present study was designed to analyze the expression of a series of reference genes to select optimal ones for RT-qPCR analysis in cortex and hippocampus of rats chronically exposed to excessive fluoride (F-) amounts. Six-week-old male Wistar rats randomly assigned to four groups consumed regular tap water with 0.4 (control), 5, 20, and 50 ppm F- (NaF) for 12 months. The expression of six genes (Gapdh, Pgk1, Eef1a1, Ppia, Tbp, Helz) was compared by RT-qPCR in brain tissues from control and F--exposed animals. The stability of candidate reference genes was evaluated by coefficient of variation (CV) analysis and RefFinder online program summarizing the results of four well-acknowledged statistical methods (Delta-Ct, BestKeeper, NormFinder, and GeNorm). In spite of some discrepancies in gene ranking between these algorisms, Pgk1, Eef1a1, and Ppia were found to be most valid in cortex, while Ppia, Eef1a1, and Helz showed the greatest expression stability in hippocampus. Tbp and Helz were identified as the least stable genes in cortex, whereas Gapdh and Tbp are unsuitable for hippocampus. These data indicate that reliable mRNA quantification in the cortex and hippocampus of F--poisoned rats is possible using normalization to geometric mean of Pgk1+Eef1a1 or Ppia+Eef1a1 expression, respectively.
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Affiliation(s)
- Olga V Nadei
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, 194223, Saint-Petersburg, Russia
| | - Natalia I Agalakova
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, 194223, Saint-Petersburg, Russia.
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3
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Brandebura AN, Kolson DR, Amick EM, Ramadan J, Kersting MC, Nichol RH, Holcomb PS, Mathers PH, Stoilov P, Spirou GA. Transcriptional profiling reveals roles of intercellular Fgf9 signaling in astrocyte maturation and synaptic refinement during brainstem development. J Biol Chem 2022; 298:102176. [PMID: 35753346 PMCID: PMC9304775 DOI: 10.1016/j.jbc.2022.102176] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 06/15/2022] [Accepted: 06/16/2022] [Indexed: 11/26/2022] Open
Abstract
Neural tissue maturation is a coordinated process under tight transcriptional control. We previously analyzed the kinetics of gene expression in the medial nucleus of the trapezoid body (MNTB) in the brainstem during the critical postnatal phase of its development. While this work revealed timed execution of transcriptional programs, it was blind to the specific cells where gene expression changes occurred. Here, we utilized single-cell RNA-Seq to determine transcriptional profiles of each major MNTB cell type. We discerned directional signaling patterns between neuronal, glial, and vascular-associated cells for VEGF, TGFβ, and Delta-Notch pathways during a robust period of vascular remodeling in the MNTB. Furthermore, we describe functional outcomes of the disruption of neuron-astrocyte fibroblast growth factor 9 (Fgf9) signaling. We used a conditional KO (cKO) approach to genetically delete Fgf9 from principal neurons in the MNTB, which led to an early onset of glial fibrillary acidic protein (Gfap) expression in astrocytes. In turn, Fgf9 cKO mice show increased levels of astrocyte-enriched brevican (Bcan), a component of the perineuronal net matrix that ensheaths principal neurons in the MNTB and the large calyx of Held terminal, while levels of the neuron-enriched hyaluronan and proteoglycan link protein 1 (Hapln1) were unchanged. Finally, volumetric analysis of vesicular glutamate transporters 1 and 2 (Vglut1/2), which serves as a proxy for terminal size, revealed an increase in calyx of Held volume in the Fgf9 cKO. Overall, we demonstrate a coordinated neuron-astrocyte Fgf9 signaling network that functions to regulate astrocyte maturation, perineuronal net structure, and synaptic refinement.
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Affiliation(s)
- Ashley N Brandebura
- Graduate Program in Biochemistry and Molecular Biology, West Virginia University, Morgantown, West Virginia, USA; Department of Biochemistry, West Virginia University, Morgantown, West Virginia, USA; Rockefeller Neuroscience Institute, West Virginia University, Morgantown, West Virginia, USA
| | - Douglas R Kolson
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, West Virginia, USA; Department of Otolaryngology HNS, West Virginia University, Morgantown, West Virginia, USA; Department of Ophthalmology, West Virginia University, Morgantown, West Virginia, USA
| | - Emily M Amick
- Department of Medical Engineering, University of South Florida, Tampa, Florida, USA
| | - Jad Ramadan
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, West Virginia, USA; Department of Otolaryngology HNS, West Virginia University, Morgantown, West Virginia, USA
| | - Matthew C Kersting
- Department of Medical Engineering, University of South Florida, Tampa, Florida, USA
| | - Robert H Nichol
- Department of Medical Engineering, University of South Florida, Tampa, Florida, USA
| | - Paul S Holcomb
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, West Virginia, USA; Department of Otolaryngology HNS, West Virginia University, Morgantown, West Virginia, USA
| | - Peter H Mathers
- Department of Biochemistry, West Virginia University, Morgantown, West Virginia, USA; Rockefeller Neuroscience Institute, West Virginia University, Morgantown, West Virginia, USA; Department of Otolaryngology HNS, West Virginia University, Morgantown, West Virginia, USA; Department of Ophthalmology, West Virginia University, Morgantown, West Virginia, USA.
| | - Peter Stoilov
- Department of Biochemistry, West Virginia University, Morgantown, West Virginia, USA.
| | - George A Spirou
- Department of Medical Engineering, University of South Florida, Tampa, Florida, USA.
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Chokr SM, Milinkeviciute G, Cramer KS. Synapse Maturation and Developmental Impairment in the Medial Nucleus of the Trapezoid Body. Front Integr Neurosci 2022; 16:804221. [PMID: 35221938 PMCID: PMC8863736 DOI: 10.3389/fnint.2022.804221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 01/17/2022] [Indexed: 11/29/2022] Open
Abstract
Sound localization requires rapid interpretation of signal speed, intensity, and frequency. Precise neurotransmission of auditory signals relies on specialized auditory brainstem synapses including the calyx of Held, the large encapsulating input to principal neurons in the medial nucleus of the trapezoid body (MNTB). During development, synapses in the MNTB are established, eliminated, and strengthened, thereby forming an excitatory/inhibitory (E/I) synapse profile. However, in neurodevelopmental disorders such as autism spectrum disorder (ASD), E/I neurotransmission is altered, and auditory phenotypes emerge anatomically, molecularly, and functionally. Here we review factors required for normal synapse development in this auditory brainstem pathway and discuss how it is affected by mutations in ASD-linked genes.
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Xu SJ, Lombroso SI, Fischer DK, Carpenter MD, Marchione DM, Hamilton PJ, Lim CJ, Neve RL, Garcia BA, Wimmer ME, Pierce RC, Heller EA. Chromatin-mediated alternative splicing regulates cocaine-reward behavior. Neuron 2021; 109:2943-2966.e8. [PMID: 34480866 PMCID: PMC8454057 DOI: 10.1016/j.neuron.2021.08.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 06/14/2021] [Accepted: 08/10/2021] [Indexed: 10/20/2022]
Abstract
Neuronal alternative splicing is a key gene regulatory mechanism in the brain. However, the spliceosome machinery is insufficient to fully specify splicing complexity. In considering the role of the epigenome in activity-dependent alternative splicing, we and others find the histone modification H3K36me3 to be a putative splicing regulator. In this study, we found that mouse cocaine self-administration caused widespread differential alternative splicing, concomitant with the enrichment of H3K36me3 at differentially spliced junctions. Importantly, only targeted epigenetic editing can distinguish between a direct role of H3K36me3 in splicing and an indirect role via regulation of splice factor expression elsewhere on the genome. We targeted Srsf11, which was both alternatively spliced and H3K36me3 enriched in the brain following cocaine self-administration. Epigenetic editing of H3K36me3 at Srsf11 was sufficient to drive its alternative splicing and enhanced cocaine self-administration, establishing the direct causal relevance of H3K36me3 to alternative splicing of Srsf11 and to reward behavior.
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Affiliation(s)
- Song-Jun Xu
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Sonia I Lombroso
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Delaney K Fischer
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Marco D Carpenter
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Dylan M Marchione
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Peter J Hamilton
- Department of Brain and Cognitive Sciences, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Carissa J Lim
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Rachel L Neve
- Gene Delivery Technology Core, Massachusetts General Hospital, Cambridge, MA 02139, USA
| | - Benjamin A Garcia
- Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA; Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Mathieu E Wimmer
- Department of Psychology, Temple University, Philadelphia, PA 19121, USA
| | - R Christopher Pierce
- Department of Psychiatry, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| | - Elizabeth A Heller
- Department of Systems Pharmacology and Translational Therapeutics, University of Pennsylvania, Philadelphia, PA 19104, USA; Institute for Translational Medicine and Therapeutics, University of Pennsylvania, Philadelphia, PA,19104, USA; Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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6
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Kohrman DC, Borges BC, Cassinotti LR, Ji L, Corfas G. Axon-glia interactions in the ascending auditory system. Dev Neurobiol 2021; 81:546-567. [PMID: 33561889 DOI: 10.1002/dneu.22813] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 11/25/2020] [Accepted: 02/05/2021] [Indexed: 11/09/2022]
Abstract
The auditory system detects and encodes sound information with high precision to provide a high-fidelity representation of the environment and communication. In mammals, detection occurs in the peripheral sensory organ (the cochlea) containing specialized mechanosensory cells (hair cells) that initiate the conversion of sound-generated vibrations into action potentials in the auditory nerve. Neural activity in the auditory nerve encodes information regarding the intensity and frequency of sound stimuli, which is transmitted to the auditory cortex through the ascending neural pathways. Glial cells are critical for precise control of neural conduction and synaptic transmission throughout the pathway, allowing for the precise detection of the timing, frequency, and intensity of sound signals, including the sub-millisecond temporal fidelity is necessary for tasks such as sound localization, and in humans, for processing complex sounds including speech and music. In this review, we focus on glia and glia-like cells that interact with hair cells and neurons in the ascending auditory pathway and contribute to the development, maintenance, and modulation of neural circuits and transmission in the auditory system. We also discuss the molecular mechanisms of these interactions, their impact on hearing and on auditory dysfunction associated with pathologies of each cell type.
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Affiliation(s)
- David C Kohrman
- Department of Otolaryngology - Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
| | - Beatriz C Borges
- Department of Otolaryngology - Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
| | - Luis R Cassinotti
- Department of Otolaryngology - Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
| | - Lingchao Ji
- Department of Otolaryngology - Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
| | - Gabriel Corfas
- Department of Otolaryngology - Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, MI, USA
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Sierksma MC, Slotman JA, Houtsmuller AB, Borst JGG. Structure-function relation of the developing calyx of Held synapse in vivo. J Physiol 2020; 598:4603-4619. [PMID: 33439501 PMCID: PMC7689866 DOI: 10.1113/jp279976] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 07/07/2020] [Indexed: 12/18/2022] Open
Abstract
KEY POINTS During development the giant, auditory calyx of Held forms a one-to-one connection with a principal neuron of the medial nucleus of the trapezoid body. While anatomical studies described that most of the target cells are temporarily contacted by multiple calyces, multi-calyceal innervation was only sporadically observed in in vivo recordings, suggesting a structure-function discrepancy. We correlated synaptic strength of inputs, identified in in vivo recordings, with post hoc labelling of the recorded neuron and synaptic terminals containing vesicular glutamate transporters (VGluT). During development only one input increased to the level of the calyx of Held synapse, and its strength correlated with the large VGluT cluster contacting the postsynaptic soma. As neither competing strong inputs nor multiple large VGluT clusters on a single cell were observed, our findings did not indicate a structure-function discrepancy. ABSTRACT In adult rodents, a principal neuron in the medial nucleus of the trapezoid (MNTB) is generally contacted by a single, giant axosomatic terminal called the calyx of Held. How this one-on-one relation is established is still unknown, but anatomical evidence suggests that during development principal neurons are innervated by multiple calyces, which may indicate calyceal competition. However, in vivo electrophysiological recordings from principal neurons indicated that only a single strong synaptic connection forms per cell. To test whether a mismatch exists between synaptic strength and terminal size, we compared the strength of synaptic inputs with the morphology of the synaptic terminals. In vivo whole-cell recordings of the MNTB neurons from newborn Wistar rats of either sex were made while stimulating their afferent axons, allowing us to identify multiple inputs. The strength of the strongest input increased to calyceal levels in a few days across cells, while the strength of the second strongest input was stable. The recorded cells were subsequently immunolabelled for vesicular glutamate transporters (VGluT) to reveal axosomatic terminals with structured-illumination microscopy. Synaptic strength of the strongest input was correlated with the contact area of the largest VGluT cluster at the soma (r = 0.8), and no indication of a mismatch between structure and strength was observed. Together, our data agree with a developmental scheme in which one input strengthens and becomes the calyx of Held, but not with multi-calyceal competition.
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Affiliation(s)
- Martijn C Sierksma
- Department of Neuroscience, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, 3000 CA, The Netherlands.,Sorbonne Université, Inserm, CNRS, Institut de la Vision, 17 Rue Moreau, Paris, F-75012, France
| | - Johan A Slotman
- Department of Pathology-Optical Imaging Centre, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, 3000 CA, The Netherlands
| | - Adriaan B Houtsmuller
- Department of Pathology-Optical Imaging Centre, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, 3000 CA, The Netherlands
| | - J Gerard G Borst
- Department of Neuroscience, Erasmus MC, University Medical Centre Rotterdam, Rotterdam, 3000 CA, The Netherlands
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8
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Brandebura AN, Morehead M, Heller DT, Holcomb P, Kolson DR, Jones G, Mathers PH, Spirou GA. Glial Cell Expansion Coincides with Neural Circuit Formation in the Developing Auditory Brainstem. Dev Neurobiol 2018; 78:1097-1116. [PMID: 30136399 DOI: 10.1002/dneu.22633] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 04/24/2018] [Accepted: 07/24/2018] [Indexed: 02/01/2023]
Abstract
Neural circuit formation involves maturation of neuronal, glial and vascular cells, as well as cell proliferation and cell death. A fundamental understanding of cellular mechanisms is enhanced by quantification of cell types during key events in synapse formation and pruning and possessing qualified genetic tools for cell type-specific manipulation. Acquiring this information in turn requires validated cell markers and genetic tools. We quantified changing proportions of neurons, astrocytes, oligodendrocytes, and microglia in the medial nucleus of the trapezoid body (MNTB) during neural circuit development. Cell type-specific markers, light microscopy and 3D virtual reality software, the latter developed in our laboratory, were used to count cells within distinct cell populations at postnatal days (P)3 and P6, bracketing the period of nerve terminal growth and pruning in this system. These data revealed a change from roughly equal numbers of neurons and glia at P3 to a 1.5:1 ratio of glia to neurons at P6. PCNA and PH3 labeling revealed that proliferation of oligodendrocytes contributed to the increase in glial cell number during this timeframe. We next evaluated Cre driver lines for selectivity in labeling cell populations. En1-Cre was specific for MNTB neurons. PDGFRα-Cre and Aldh1L1-Cre, thought to be mostly specific for oligodendrocyte lineage cells and astrocytes, respectively, both labeled significant numbers of neurons, oligodendrocytes, and astrocytes and are non-specific genetic tools in this neural system.
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Affiliation(s)
- Ashley N Brandebura
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, West Virginia.,Sensory Neuroscience Research Center, West Virginia University, Morgantown, West Virginia.,Graduate program in Biochemistry and Molecular Biology, West Virginia University, Morgantown, West Virginia.,Department of Biochemistry, West Virginia University, Morgantown, West Virginia
| | - Michael Morehead
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, West Virginia.,Sensory Neuroscience Research Center, West Virginia University, Morgantown, West Virginia.,Lane Department of Computer Science and Electrical Engineering, West Virginia University, Morgantown, West Virginia
| | - Daniel T Heller
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, West Virginia.,Sensory Neuroscience Research Center, West Virginia University, Morgantown, West Virginia
| | - Paul Holcomb
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, West Virginia.,Sensory Neuroscience Research Center, West Virginia University, Morgantown, West Virginia
| | - Douglas R Kolson
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, West Virginia.,Sensory Neuroscience Research Center, West Virginia University, Morgantown, West Virginia
| | - Garrett Jones
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, West Virginia.,Sensory Neuroscience Research Center, West Virginia University, Morgantown, West Virginia
| | - Peter H Mathers
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, West Virginia.,Sensory Neuroscience Research Center, West Virginia University, Morgantown, West Virginia.,Department of Biochemistry, West Virginia University, Morgantown, West Virginia.,Department of Otolaryngology HNS, West Virginia University, Morgantown, West Virginia.,Department of Ophthalmology, West Virginia University, Morgantown, West Virginia
| | - George A Spirou
- Rockefeller Neuroscience Institute, West Virginia University, Morgantown, West Virginia.,Sensory Neuroscience Research Center, West Virginia University, Morgantown, West Virginia.,Department of Otolaryngology HNS, West Virginia University, Morgantown, West Virginia
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9
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Weinrich L, Sonntag M, Arendt T, Morawski M. Neuroanatomical characterization of perineuronal net components in the human cochlear nucleus and superior olivary complex. Hear Res 2018; 367:32-47. [PMID: 30025262 DOI: 10.1016/j.heares.2018.07.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 06/21/2018] [Accepted: 07/06/2018] [Indexed: 10/28/2022]
Abstract
The human auditory brainstem, especially the cochlear nucleus (CN) and the superior olivary complex (SOC) are characterized by a high density of neurons associated with perineuronal nets (PNs). PNs build a specific form of extracellular matrix surrounding the neuronal somata, proximal dendrites and axon initial segments. They restrict synaptic plasticity and control high-frequency synaptic activity, a prominent characteristic of neurons of the auditory brainstem. The distribution of PNs within the auditory brainstem has been investigated in a number of mammalian species. However, much less is known regarding PNs in the human auditory brainstem. The present study aimed at the immunohistochemical identification of PNs in the cochlear nucleus (CN) and superior olivary complex (SOC) in the human brainstem. We focused on the complex nature and molecular variability of PNs in the CN and SOC by using specific antibodies against the main PN components (aggrecan, brevican, neurocan and hyaluronan and proteoglycan link protein 1). Virtually all subnuclei within the ventral CN and SOC were found to be associated with PNs. Direct comparison between gerbil and human yielded similar fine structure of PNs and confirmed the typical tight interdigitation of PNs with synaptic terminals in both species. Noticeably, an elaborate combination of immunohistochemical labelings clearly supports the still debated existence of the medial nucleus of trapezoid body (MNTB) in the human brain. In conclusion, the present study demonstrates that PNs form a prominent extracellular structure on CN and SOC neurons in the human brain, potentially stabilizing synaptic contacts, which is in agreement with many other mammalian species.
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Affiliation(s)
- Luise Weinrich
- Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany
| | - Mandy Sonntag
- Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany
| | - Thomas Arendt
- Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany
| | - Markus Morawski
- Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany.
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10
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Zhang B, Seigneur E, Wei P, Gokce O, Morgan J, Südhof TC. Developmental plasticity shapes synaptic phenotypes of autism-associated neuroligin-3 mutations in the calyx of Held. Mol Psychiatry 2017; 22:1483-91. [PMID: 27725662 DOI: 10.1038/mp.2016.157] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Revised: 07/08/2016] [Accepted: 07/27/2016] [Indexed: 01/21/2023]
Abstract
Neuroligins are postsynaptic cell-adhesion molecules that bind to presynaptic neurexins. Mutations in neuroligin-3 predispose to autism, but how such mutations affect synaptic function remains incompletely understood. Here we systematically examined the effect of three autism-associated mutations, the neuroligin-3 knockout, the R451C knockin, and the R704C knockin, on synaptic transmission in the calyx of Held, a central synapse ideally suited for high-resolution analyses of synaptic transmission. Surprisingly, germline knockout of neuroligin-3 did not alter synaptic transmission, whereas the neuroligin-3 R451C and R704C knockins decreased and increased, respectively, synaptic transmission. These puzzling results prompted us to ask whether neuroligin-3 mutant phenotypes may be reshaped by developmental plasticity. Indeed, conditional knockout of neuroligin-3 during late development produced a marked synaptic phenotype, whereas conditional knockout of neuroligin-3 during early development caused no detectable effect, mimicking the germline knockout. In canvassing potentially redundant candidate genes, we identified developmentally early expression of another synaptic neurexin ligand, cerebellin-1. Strikingly, developmentally early conditional knockout of cerebellin-1 only modestly impaired synaptic transmission, whereas in contrast to the individual single knockouts, developmentally early conditional double knockout of both cerebellin-1 and neuroligin-3 severely decreased synaptic transmission. Our data suggest an unanticipated mechanism of developmental compensation whereby cerebellin-1 and neuroligin-3 functionally occlude each other during development of calyx synapses. Thus, although acute manipulations more likely reveal basic gene functions, developmental plasticity can be a major factor in shaping the overall phenotypes of genetic neuropsychiatric disorders.
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Long P, Wan G, Roberts MT, Corfas G. Myelin development, plasticity, and pathology in the auditory system. Dev Neurobiol 2017; 78:80-92. [PMID: 28925106 DOI: 10.1002/dneu.22538] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 08/23/2017] [Accepted: 09/14/2017] [Indexed: 11/11/2022]
Abstract
Myelin allows for the rapid and precise timing of action potential propagation along neuronal circuits and is essential for healthy auditory system function. In this article, we discuss what is currently known about myelin in the auditory system with a focus on the timing of myelination during auditory system development, the role of myelin in supporting peripheral and central auditory circuit function, and how various myelin pathologies compromise auditory information processing. Additionally, in keeping with the increasing recognition that myelin is dynamic and is influenced by experience throughout life, we review the growing evidence that auditory sensory deprivation alters myelin along specific segments of the brain's auditory circuit. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 80-92, 2018.
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Affiliation(s)
- Patrick Long
- Kresge Hearing Research Institute and Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, Michigan, 48109
| | - Guoqiang Wan
- MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, Jiangsu Province, China
| | - Michael T Roberts
- Kresge Hearing Research Institute and Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, Michigan, 48109
| | - Gabriel Corfas
- Kresge Hearing Research Institute and Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, Michigan, 48109
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Abstract
Glial cells, previously thought to have generally supporting roles in the central nervous system, are emerging as essential contributors to multiple aspects of neuronal circuit function and development. This review focuses on the contributions of glial cells to the development of auditory pathways in the brainstem. These pathways display specialized synapses and an unusually high degree of precision in circuitry that enables sound source localization. The development of these pathways thus requires highly coordinated molecular and cellular mechanisms. Several classes of glial cells, including astrocytes, oligodendrocytes and microglia, have now been explored in these circuits in both avian and mammalian brainstems. Distinct populations of astrocytes are found over the course of auditory brainstem maturation. Early appearing astrocytes are associated with spatial compartments in the avian auditory brainstem. Factors from late appearing astrocytes promote synaptogenesis and dendritic maturation, and astrocytes remain integral parts of specialized auditory synapses. Oligodendrocytes play a unique role in both birds and mammals in highly regulated myelination essential for proper timing to decipher interaural cues. Microglia arise early in brainstem development and may contribute to maturation of auditory pathways. Together these studies demonstrate the importance of non-neuronal cells in the assembly of specialized auditory brainstem circuits.
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Affiliation(s)
- Karina S Cramer
- Department of Neurobiology and Behavior, University of California, Irvine Irvine, CA, USA
| | - Edwin W Rubel
- Virginia Merrill Bloedel Hearing Research Center, University of Washington Seattle, WA, USA
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Sierksma MC, Tedja MS, Borst JGG. In vivo matching of postsynaptic excitability with spontaneous synaptic inputs during formation of the rat calyx of Held synapse. J Physiol 2016; 595:207-231. [PMID: 27426483 DOI: 10.1113/jp272780] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 07/07/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Neurons in the medial nucleus of the trapezoid body of anaesthetized rats of postnatal day (P)2-6 showed burst firing with a preferred interval of about 100 ms, which was stable, and a second preferred interval of 5-30 ms, which shortened during development. In 3 out of 132 cases, evidence for the presence of two large inputs was found. In vivo whole-cell recordings revealed that the excitability of the principal neuron and the size of its largest synaptic inputs were developmentally matched. At P2-4, action potentials were triggered by barrages of small synaptic events that summated to plateau potentials, while at later stages firing depended on a single, large and often prespike-associated input, which is probably the nascent calyx of Held. Simulations with a Hodgkin-Huxley-like model, which was based on fits of the intrinsic postsynaptic properties, suggested an essential role for the low-threshold potassium conductance in this transition. ABSTRACT In the adult, principal neurons of the medial nucleus of the trapezoid body (MNTB) are typically contacted by a single, giant terminal called the calyx of Held, whereas during early development a principal neuron receives inputs from many axons. How these changes in innervation impact the postsynaptic activity has not yet been studied in vivo. We therefore recorded spontaneous inputs and intrinsic properties of principal neurons in anaesthetized rat pups during the developmental period in which the calyx forms. A characteristic bursting pattern could already be observed at postnatal day (P)2, before formation of the calyx. At this age, action potentials (APs) were triggered by barrages of summating EPSPs causing plateau depolarizations. In contrast, at P5, a single EPSP reliably triggered APs, resulting in a close match between pre- and postsynaptic firing. Postsynaptic excitability and the size of the largest synaptic events were developmentally matched. The developmental changes in intrinsic properties were estimated by fitting in vivo current injections to a Hodgkin-Huxley-type model of the principal neuron. Our simulations indicated that the developmental increases in Ih , low-threshold K+ channels and leak currents contributed to the reduction in postsynaptic excitability, but that low-threshold K+ channels specifically functioned as a dampening influence in the near-threshold range, thus precluding small inputs from triggering APs. Together, these coincident changes help to propagate bursting activity along the auditory brainstem, and are essential steps towards establishing the relay function of the calyx of Held synapse.
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Affiliation(s)
- Martijn C Sierksma
- Department of Neuroscience, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Milly S Tedja
- Department of Neuroscience, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - J Gerard G Borst
- Department of Neuroscience, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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