1
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Radulovic T, Rajaram E, Ebbers L, Pagella S, Winklhofer M, Kopp-Scheinpflug C, Nothwang HG, Milenkovic I, Hartmann AM. Serine 937 phosphorylation enhances KCC2 activity and strengthens synaptic inhibition. Sci Rep 2023; 13:21660. [PMID: 38066086 PMCID: PMC10709408 DOI: 10.1038/s41598-023-48884-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 11/30/2023] [Indexed: 12/18/2023] Open
Abstract
The potassium chloride cotransporter KCC2 is crucial for Cl- extrusion from mature neurons and thus key to hyperpolarizing inhibition. Auditory brainstem circuits contain well-understood inhibitory projections and provide a potent model to study the regulation of synaptic inhibition. Two peculiarities of the auditory brainstem are (i) posttranslational activation of KCC2 during development and (ii) extremely negative reversal potentials in specific circuits. To investigate the role of the potent phospho-site serine 937 therein, we generated a KCC2 Thr934Ala/Ser937Asp double mutation, in which Ser937 is replaced by aspartate mimicking the phosphorylated state, and the neighbouring Thr934 arrested in the dephosphorylated state. This double mutant showed a twofold increased transport activity in HEK293 cells, raising the hypothesis that auditory brainstem neurons show lower [Cl-]i. and increased glycinergic inhibition. This was tested in a mouse model carrying the same KCC2 Thr934Ala/Ser937Asp mutation by the use of the CRISPR/Cas9 technology. Homozygous KCC2 Thr934Ala/Ser937Asp mice showed an earlier developmental onset of hyperpolarisation in the auditory brainstem. Mature neurons displayed stronger glycinergic inhibition due to hyperpolarized ECl-. These data demonstrate that phospho-regulation of KCC2 Ser937 is a potent way to interfere with the excitation-inhibition balance in neural circuits.
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Affiliation(s)
- Tamara Radulovic
- Division of Physiology School of Medicine and Health Sciences, Carl Von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
- Research Center Neurosensory Science, Carl Von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
| | - Ezhilarasan Rajaram
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximilians-University Munich, 82152, Planegg-Martinsried, Germany
| | - Lena Ebbers
- Division of Neurogenetics, School of Medicine and Health Sciences, Carl Von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
| | - Sara Pagella
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximilians-University Munich, 82152, Planegg-Martinsried, Germany
| | - Michael Winklhofer
- Research Center Neurosensory Science, Carl Von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
- Institute for Biology and Environmental Sciences IBU, Carl Von Ossietzky University of Oldenburg, 26111, Oldenburg, Germany
| | - Conny Kopp-Scheinpflug
- Division of Neurobiology, Faculty of Biology, Ludwig-Maximilians-University Munich, 82152, Planegg-Martinsried, Germany
| | - Hans Gerd Nothwang
- Division of Neurogenetics, School of Medicine and Health Sciences, Carl Von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
- Research Center Neurosensory Science, Carl Von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
- Center of Excellence Hearing4all, Carl Von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
| | - Ivan Milenkovic
- Division of Physiology School of Medicine and Health Sciences, Carl Von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
- Research Center Neurosensory Science, Carl Von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
| | - Anna-Maria Hartmann
- Division of Neurogenetics, School of Medicine and Health Sciences, Carl Von Ossietzky University Oldenburg, 26111, Oldenburg, Germany.
- Research Center Neurosensory Science, Carl Von Ossietzky University Oldenburg, 26111, Oldenburg, Germany.
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2
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Bordeynik-Cohen M, Sperber M, Ebbers L, Messika-Gold N, Krohs C, Koffler-Brill T, Noy Y, Elkon R, Nothwang HG, Avraham KB. Shared and organ-specific gene-expression programs during the development of the cochlea and the superior olivary complex. RNA Biol 2023; 20:629-640. [PMID: 37602850 PMCID: PMC10443965 DOI: 10.1080/15476286.2023.2247628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 08/07/2023] [Accepted: 08/09/2023] [Indexed: 08/22/2023] Open
Abstract
The peripheral and central auditory subsystems together form a complex sensory network that allows an organism to hear. The genetic programs of the two subsystems must therefore be tightly coordinated during development. Yet, their interactions and common expression pathways have never been systematically explored. MicroRNAs (miRNAs) are short non-coding RNAs that regulate gene expression and are essential for normal development of the auditory system. We performed mRNA and small-RNA sequencing of organs from both auditory subsystems at three critical developmental timepoints (E16, P0, P16) to obtain a comprehensive and unbiased insight of their expression profiles. Our analysis reveals common and organ-specific expression patterns for differentially regulated mRNAs and miRNAs, which could be clustered with a particular selection of functions such as inner ear development, Wnt signalling, K+ transport, and axon guidance, based on gene ontology. Bioinformatics detected enrichment of predicted targets of specific miRNAs in the clusters and predicted regulatory interactions by monitoring opposite trends of expression of miRNAs and their targets. This approach identified six miRNAs as strong regulatory candidates for both subsystems. Among them was miR-96, an established critical factor for proper development in both subsystems, demonstrating the strength of our approach. We suggest that other miRNAs identified by this analysis are also common effectors of proper hearing acquirement. This first combined comprehensive analysis of the developmental program of the peripheral and central auditory systems provides important data and bioinformatics insights into the shared genetic program of the two sensory subsystems and their regulation by miRNAs.
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Affiliation(s)
- Mor Bordeynik-Cohen
- Laboratory of Neural and Sensory Genomics, Department of Human Molecular Genetics & Biochemistry, Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Michal Sperber
- Department of Human Molecular Genetics & Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Lena Ebbers
- Neurogenetics group and Cluster of Excellence Hearing4All, School of Medicine and Health Sciences and Research Center for Neurosensory Science, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Naama Messika-Gold
- Department of Human Molecular Genetics & Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Constanze Krohs
- Neurogenetics group and Cluster of Excellence Hearing4All, School of Medicine and Health Sciences and Research Center for Neurosensory Science, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Tal Koffler-Brill
- Laboratory of Neural and Sensory Genomics, Department of Human Molecular Genetics & Biochemistry, Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Yael Noy
- Laboratory of Neural and Sensory Genomics, Department of Human Molecular Genetics & Biochemistry, Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - Ran Elkon
- Department of Human Molecular Genetics & Biochemistry, Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Hans Gerd Nothwang
- Neurogenetics group and Cluster of Excellence Hearing4All, School of Medicine and Health Sciences and Research Center for Neurosensory Science, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Karen B. Avraham
- Laboratory of Neural and Sensory Genomics, Department of Human Molecular Genetics & Biochemistry, Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
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3
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Ihbe N, Le Prieult F, Wang Q, Distler U, Sielaff M, Tenzer S, Thal SC, Mittmann T. Adaptive Mechanisms of Somatostatin-Positive Interneurons after Traumatic Brain Injury through a Switch of α Subunits in L-Type Voltage-Gated Calcium Channels. Cereb Cortex 2021; 32:1093-1109. [PMID: 34411234 DOI: 10.1093/cercor/bhab268] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Revised: 07/07/2021] [Accepted: 07/08/2021] [Indexed: 12/28/2022] Open
Abstract
Unilateral traumatic brain injury (TBI) causes cortical dysfunctions spreading to the primarily undamaged hemisphere. This phenomenon, called transhemispheric diaschisis, is mediated by an imbalance of glutamatergic versus GABAergic neurotransmission. This study investigated the role of GABAergic, somatostatin-positive (SST) interneurons in the contralateral hemisphere 72 h after unilateral TBI. The brain injury was induced to the primary motor/somatosensory cortex of glutamate decarboxylase 67-green fluorescent protein (GAD67-GFP) knock-in mice at postnatal days 19-21 under anesthesia in vivo. Single GFP+ interneurons of the undamaged, contralateral cortex were isolated by fluorescence-activated cell sorting and analyzed by mass spectrometry. TBI caused a switch of 2 α subunits of pore-forming L-type voltage-gated calcium channels (VGCC) in GABAergic interneurons, an increased expression of CaV1.3, and simultaneous ablation of CaV1.2. This switch was associated with 1) increased excitability of single SST interneurons in patch-clamp recordings and (2) a recovery from early network hyperactivity in the contralateral hemisphere in microelectrode array recordings of acute slices. The electrophysiological changes were sensitive to pharmacological blockade of CaV1.3 (isradipine, 100 nM). These data identify a switch of 2 α subunits of VGCCs in SST interneurons early after TBI as a mechanism to counterbalance post-traumatic hyperexcitability.
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Affiliation(s)
- Natascha Ihbe
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University, 55128 Mainz, Germany
| | - Florie Le Prieult
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University, 55128 Mainz, Germany
| | - Qi Wang
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University, 55128 Mainz, Germany
| | - Ute Distler
- Institute for Immunology, University Medical Center of the Johannes Gutenberg University, 55131 Mainz, Germany
| | - Malte Sielaff
- Institute for Immunology, University Medical Center of the Johannes Gutenberg University, 55131 Mainz, Germany
| | - Stefan Tenzer
- Institute for Immunology, University Medical Center of the Johannes Gutenberg University, 55131 Mainz, Germany
| | - Serge C Thal
- Clinic for Anesthesiology, University Medical Center of the Johannes Gutenberg University, 55131 Mainz, Germany
| | - Thomas Mittmann
- Institute of Physiology, University Medical Center of the Johannes Gutenberg University, 55128 Mainz, Germany
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4
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Saleh AJ, Nothwang HG. Differential expression of microRNAs in the developing avian auditory hindbrain. J Comp Neurol 2021; 529:3477-3496. [PMID: 34180540 DOI: 10.1002/cne.25205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 06/24/2021] [Accepted: 06/25/2021] [Indexed: 11/08/2022]
Abstract
The avian auditory hindbrain is a longstanding model for studying neural circuit development. Information on gene regulatory network (GRN) components underlying this process, however, is scarce. Recently, the spatiotemporal expression of 12 microRNAs (miRNAs) was investigated in the mammalian auditory hindbrain. As a comparative study, we here investigated the spatiotemporal expression of the orthologous miRNAs during development of the chicken auditory hindbrain. All miRNAs were expressed both at E13, an immature stage, and P14, a mature stage of the auditory system. In most auditory nuclei, a homogeneous expression pattern was observed at both stages, like the mammalian system. An exception was the nucleus magnocellularis (NM). There, at E13, nine miRNAs showed a differential expression pattern along the cochleotopic axis with high expression at the rostromedial pole. One of them showed a gradient expression whereas eight showed a spatially selective expression at the rostral pole that reflected the different rhombomeric origins of this composite nucleus. The miRNA differential expression persisted in the NM to the mature stage, with the selective expression changed to linear gradients. Bioinformatics analysis predicted mRNA targets that are associated with neuronal developmental processes such as neurite and synapse organization, calcium and ephrin-Eph signaling, and neurotransmission. Overall, this first analysis of miRNAs in the chicken central auditory system reveals shared and strikingly distinct features between chicken and murine orthologues. The embryonic gradient expression of these GRN elements in the NM adds miRNA patterns to the list of cochleotopic and developmental gradients in the central auditory system.
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Affiliation(s)
- Ali Jason Saleh
- Division of Neurogenetics and Cluster of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Hans Gerd Nothwang
- Division of Neurogenetics and Cluster of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany.,Research Center for Neurosensory Science, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
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5
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Schinzel F, Seyfer H, Ebbers L, Nothwang HG. The Lbx1 lineage differentially contributes to inhibitory cell types of the dorsal cochlear nucleus, a cerebellum-like structure, and the cerebellum. J Comp Neurol 2021; 529:3032-3045. [PMID: 33786818 DOI: 10.1002/cne.25147] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 03/25/2021] [Accepted: 03/26/2021] [Indexed: 12/21/2022]
Abstract
The dorsal cochlear nucleus (DCN) is a mammalian-specific nucleus of the auditory system. Anatomically, it is classified as a cerebellum-like structure. These structures are proposed to share genetic programs with the cerebellum. Previous analyses demonstrated that inhibitory serial sister cell types (SCTs) of the DCN and cerebellum are derived from the pancreatic transcription factor 1a (Ptf1a) lineage. Postmitotic neurons of the Ptf1a lineage often express the transcription factor Ladybird homeobox protein homolog 1 (Lbx1) which is involved in neuronal cell fate determination. Lbx1 is therefore an attractive candidate for a further component of the genetic program shared between the DCN and cerebellum. Here, we used cell-type specific marker analysis in combination with an Lbx1 reporter mouse line to analyze in both tissues which cell types of the Ptf1a lineage express Lbx1. In the DCN, stellate cells and Purkinje-like cartwheel cells were part of the Lbx1 lineage and Golgi cells were not, as determined by cell counts. In contrast, in the cerebellum, stellate cells and Golgi cells were part of the Lbx1 lineage and Purkinje cells were not. Hence, two out of three phenotypically similar cell types differed with respect to their Lbx1 expression. Our study demonstrates that Lbx1 is differentially recruited to the developmental genetic program of inhibitory neurons both within a given tissue and between the DCN and cerebellum. The differential expression of Lbx1 within the DCN and the cerebellum might contribute to the genetic individuation of the inhibitory SCTs to adapt to circuit specific tasks.
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Affiliation(s)
- Friedrich Schinzel
- Division of Neurogenetics and Cluster of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Hannah Seyfer
- Division of Neurogenetics and Cluster of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Lena Ebbers
- Division of Neurogenetics and Cluster of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
| | - Hans Gerd Nothwang
- Division of Neurogenetics and Cluster of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany.,Research Center for Neurosensory Science, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
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6
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Krohs C, Bordeynik-Cohen M, Messika-Gold N, Elkon R, Avraham KB, Nothwang HG. Expression pattern of cochlear microRNAs in the mammalian auditory hindbrain. Cell Tissue Res 2021; 383:655-666. [PMID: 33156384 PMCID: PMC7904729 DOI: 10.1007/s00441-020-03290-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2020] [Accepted: 08/24/2020] [Indexed: 12/28/2022]
Abstract
The auditory system comprises the auditory periphery, engaged in sound transduction and the central auditory system, implicated in auditory information processing and perception. Recently, evidence mounted that the mammalian peripheral and central auditory systems share a number of genes critical for proper development and function. This bears implication for auditory rehabilitation and evolution of the auditory system. To analyze to which extent microRNAs (miRNAs) belong to genes shared between both systems, we characterize the expression pattern of 12 cochlea-abundant miRNAs in the central auditory system. Quantitative real-time PCR (qRT-PCR) demonstrated expression of all 12 genes in the cochlea, the auditory hindbrain and the non-auditory prefrontal cortex (PFC) at embryonic stage (E)16 and postnatal stages (P)0 and P30. Eleven of them showed differences in expression between tissues and nine between the developmental time points. Hierarchical cluster analysis revealed that the temporal expression pattern in the auditory hindbrain was more similar to the PFC than to the cochlea. Spatiotemporal expression analysis by RNA in situ hybridization demonstrated widespread expression throughout the cochlear nucleus complex (CNC) and the superior olivary complex (SOC) during postnatal development. Altogether, our data indicate that miRNAs represent a relevant class of genetic factors functioning across the auditory system. Given the importance of gene regulatory network (GRN) components for development, physiology and evolution, the 12 miRNAs provide promising entry points to gain insights into their molecular underpinnings in the auditory system.
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Affiliation(s)
- Constanze Krohs
- Neurogenetics Group and Cluster of Excellence Hearing4All, School of Medicine and Health Sciences, Carl Von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
| | - Mor Bordeynik-Cohen
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Naama Messika-Gold
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Ran Elkon
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Karen B Avraham
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, 6997801, Tel Aviv, Israel
| | - Hans Gerd Nothwang
- Neurogenetics Group and Cluster of Excellence Hearing4All, School of Medicine and Health Sciences, Carl Von Ossietzky University Oldenburg, 26111, Oldenburg, Germany.
- Research Center for Neurosensory Science, Carl Von Ossietzky University Oldenburg, 26111, Oldenburg, Germany.
- Department of Neuroscience, Center of Excellence Hearing4All, Carl Von Ossietzky University Oldenburg, 26111, Oldenburg, Germany.
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7
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Takahashi M, Sanchez JT. Effects of Neurotrophin-3 on Intrinsic Neuronal Properties at a Central Auditory Structure. Neurosci Insights 2020; 15:2633105520980442. [PMID: 33354669 PMCID: PMC7734498 DOI: 10.1177/2633105520980442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 11/23/2020] [Indexed: 11/15/2022] Open
Abstract
Neurotrophins, a class of growth factor proteins that control neuronal proliferation, morphology, and apoptosis, are found ubiquitously throughout the nervous system. One particular neurotrophin (NT-3) and its cognate tyrosine receptor kinase (TrkC) have recently received attention as a possible therapeutic target for synaptopathic sensorineural hearing loss. Additionally, research shows that NT-3-TrkC signaling plays a role in establishing the sensory organization of frequency topology (ie, tonotopic order) in the cochlea of the peripheral inner ear. However, the neurotrophic effects of NT-3 on central auditory properties are unclear. In this study we examined whether NT-3-TrkC signaling affects the intrinsic electrophysiological properties at a first-order central auditory structure in chicken, known as nucleus magnocellularis (NM). Here, the expression pattern of specific neurotrophins is well known and tightly regulated. By using whole-cell patch-clamp electrophysiology, we show that NT-3 application to brainstem slices does not affect intrinsic properties of high-frequency neuronal regions but had robust effects for low-frequency neurons, altering voltage-dependent potassium functions, action potential repolarization kinetics, and passive membrane properties. We suggest that NT-3 may contribute to the precise establishment and organization of tonotopy in the central auditory pathway by playing a specialized role in regulating the development of intrinsic neuronal properties of low-frequency NM neurons.
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Affiliation(s)
- Momoko Takahashi
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL, USA
| | - Jason Tait Sanchez
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL, USA
- Department of Neurobiology, Northwestern University, Evanston, IL, USA
- The Hugh Knowles Hearing Research Center, Northwestern University, Evanston, IL, USA
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8
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Loss of inner hair cell ribbon synapses and auditory nerve fiber regression in Cldn14 knockout mice. Hear Res 2020; 391:107950. [PMID: 32251970 DOI: 10.1016/j.heares.2020.107950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 02/06/2020] [Accepted: 03/10/2020] [Indexed: 11/21/2022]
Abstract
Proper functioning of the auditory nerve is of critical importance for auditory rehabilitation by cochlear implants. Here we used the Cldn14-/- mouse to study in detail the effects of Claudin 14 loss on auditory synapses and the auditory nerve. Mutations in the tight junction protein Claudin 14 cause autosomal recessive non-syndromic hearing loss (DFNB29) in humans and mice, due to extensive degeneration of outer and inner hair cells. Here we show that massive inner hair cell loss in Cldn14-/- mice starts after the third postnatal week. Immunohistochemical analysis, using presynaptic Ribeye and postsynaptic GluR2 or PSD 95 as markers, revealed the degeneration of full ribbon synapses in inner hair cells from apical cochlear regions already at postnatal day 12 (P12). At P20, significant reduction in number of ribbon synapses has been observed for all cochlear regions and the loss of synaptic ribbons becomes even more prominent in residual inner hair cells from middle and apical cochlear regions at P45, which by then lost more than 40% of all ribbon synapses. In contrast to excessive noise exposure, loss of Claudin 14 does not cause an increase in "orphan" ribbons with no postsynaptic counterpart due to a reduction of postsynaptic structures. Hair cell loss in Cldn14-/- mice is associated with regression of peripheral auditory nerve processes, especially of outer radial fibers, which normally innervate the outer hair cells. The number of spiral ganglion neurons per area, however, was unchanged between the genotypes. Different effects were observed in the cochlear nucleus complex (CNC), the central projection area of the auditory nerve. While the dorsal cochlear nucleus (DCN) showed a significant 19.7% volume reduction, VGLUT-1 input was reduced by 34.4% in the ventral cochlear nucleus (VCN) but not in the DCN of Cldn14-/- mice. Taken together, massive inner hair cell loss starts after the third postnatal week in Cldn14-/- mice, but is preceded by the loss of ribbon synapses, which may be a first sign of an ongoing degeneration process in otherwise morphologically inconspicuously inner hair cells. In addition to the regression of peripheral nerve processes, reduced levels of VGLUT-1 in the VCN of Cldn14-/- mice suggests that Claudin 14 loss does not only cause hair cell loss but also affects peripheral and central connectivity of the auditory nerve.
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9
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Pitman KA, Ricci R, Gasperini R, Beasley S, Pavez M, Charlesworth J, Foa L, Young KM. The voltage-gated calcium channel CaV1.2 promotes adult oligodendrocyte progenitor cell survival in the mouse corpus callosum but not motor cortex. Glia 2019; 68:376-392. [PMID: 31605513 PMCID: PMC6916379 DOI: 10.1002/glia.23723] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 09/02/2019] [Accepted: 09/10/2019] [Indexed: 12/21/2022]
Abstract
Throughout life, oligodendrocyte progenitor cells (OPCs) proliferate and differentiate into myelinating oligodendrocytes. OPCs express cell surface receptors and channels that allow them to detect and respond to neuronal activity, including voltage‐gated calcium channel (VGCC)s. The major L‐type VGCC expressed by developmental OPCs, CaV1.2, regulates their differentiation. However, it is unclear whether CaV1.2 similarly influences OPC behavior in the healthy adult central nervous system (CNS). To examine the role of CaV1.2 in adulthood, we conditionally deleted this channel from OPCs by administering tamoxifen to P60 Cacna1cfl/fl (control) and Pdgfrα‐CreER:: Cacna1cfl/fl (CaV1.2‐deleted) mice. Whole cell patch clamp analysis revealed that CaV1.2 deletion reduced L‐type voltage‐gated calcium entry into adult OPCs by ~60%, confirming that it remains the major L‐type VGCC expressed by OPCs in adulthood. The conditional deletion of CaV1.2 from adult OPCs significantly increased their proliferation but did not affect the number of new oligodendrocytes produced or influence the length or number of internodes they elaborated. Unexpectedly, CaV1.2 deletion resulted in the dramatic loss of OPCs from the corpus callosum, such that 7 days after tamoxifen administration CaV1.2‐deleted mice had an OPC density ~42% that of control mice. OPC density recovered within 2 weeks of CaV1.2 deletion, as the lost OPCs were replaced by surviving CaV1.2‐deleted OPCs. As OPC density was not affected in the motor cortex or spinal cord, we conclude that calcium entry through CaV1.2 is a critical survival signal for a subpopulation of callosal OPCs but not for all OPCs in the mature CNS.
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Affiliation(s)
- Kimberley A Pitman
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
| | - Raphael Ricci
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
| | - Robert Gasperini
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia.,School of Medicine, University of Tasmania, Hobart, Australia
| | - Shannon Beasley
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
| | - Macarena Pavez
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
| | - Jac Charlesworth
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
| | - Lisa Foa
- School of Medicine, University of Tasmania, Hobart, Australia
| | - Kaylene M Young
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Australia
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10
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Schlüter T, Berger C, Rosengauer E, Fieth P, Krohs C, Ushakov K, Steel KP, Avraham KB, Hartmann AK, Felmy F, Nothwang HG. miR-96 is required for normal development of the auditory hindbrain. Hum Mol Genet 2018; 27:860-874. [DOI: 10.1093/hmg/ddy007] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 12/30/2017] [Indexed: 12/17/2022] Open
Affiliation(s)
- Tina Schlüter
- Neurogenetics Group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, Germany
| | - Christina Berger
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians University Munich, 82152 Martinsried, Germany
| | - Elena Rosengauer
- Neurogenetics Group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, Germany
| | - Pascal Fieth
- Computational Theoretical Physics Group, Institute of Physics, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, Germany
| | - Constanze Krohs
- Neurogenetics Group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, Germany
| | - Kathy Ushakov
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Karen P Steel
- Wolfson Centre for Age-Related Diseases, King's College London, Guy's Campus, London SE1 1UL, UK
| | - Karen B Avraham
- Department of Human Molecular Genetics and Biochemistry, Sackler Faculty of Medicine and Sagol School of Neuroscience, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Alexander K Hartmann
- Computational Theoretical Physics Group, Institute of Physics, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, Germany
| | - Felix Felmy
- Division of Neurobiology, Department Biology II, Ludwig-Maximilians University Munich, 82152 Martinsried, Germany
- Institute of Zoology, University of Veterinary Medicine Hannover, Foundation, 30559 Hannover, Germany
| | - Hans Gerd Nothwang
- Neurogenetics Group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, Germany
- Research Center for Neurosensory Science, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, Germany
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Ebbers L, Weber M, Nothwang HG. Activity-dependent formation of a vesicular inhibitory amino acid transporter gradient in the superior olivary complex of NMRI mice. BMC Neurosci 2017; 18:75. [PMID: 29073893 PMCID: PMC5659004 DOI: 10.1186/s12868-017-0393-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 10/13/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In the mammalian superior olivary complex (SOC), synaptic inhibition contributes to the processing of binaural sound cues important for sound localization. Previous analyses demonstrated a tonotopic gradient for postsynaptic proteins mediating inhibitory neurotransmission in the lateral superior olive (LSO), a major nucleus of the SOC. To probe, whether a presynaptic molecular gradient exists as well, we investigated immunoreactivity against the vesicular inhibitory amino acid transporter (VIAAT) in the mouse auditory brainstem. RESULTS Immunoreactivity against VIAAT revealed a gradient in the LSO and the superior paraolivary nucleus (SPN) of NMRI mice, with high expression in the lateral, low frequency processing limb and low expression in the medial, high frequency processing limb of both nuclei. This orientation is opposite to the previously reported gradient of glycine receptors in the LSO. Other nuclei of the SOC showed a uniform distribution of VIAAT-immunoreactivity. No gradient was observed for the glycine transporter GlyT2 and the neuronal protein NeuN. Formation of the VIAAT gradient was developmentally regulated and occurred around hearing-onset between postnatal days 8 and 16. Congenital deaf Claudin14 -/- mice bred on an NMRI background showed a uniform VIAAT-immunoreactivity in the LSO, whereas cochlear ablation in NMRI mice after hearing-onset did not affect the gradient. Additional analysis of C57Bl6/J, 129/SvJ and CBA/J mice revealed a strain-specific formation of the gradient. CONCLUSIONS Our results identify an activity-regulated gradient of VIAAT in the SOC of NRMI mice. Its absence in other mouse strains adds a novel layer of strain-specific features in the auditory system, i.e. tonotopic organization of molecular gradients. This calls for caution when comparing data from different mouse strains frequently used in studies involving transgenic animals. The presence of strain-specific differences offers the possibility of genetic mapping to identify molecular factors involved in activity-dependent developmental processes in the auditory system. This would provide an important step forward concerning improved auditory rehabilitation in cases of congenital deafness.
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Affiliation(s)
- Lena Ebbers
- Neurogenetics Group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, Germany
| | - Maren Weber
- Neurogenetics Group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, Germany
| | - Hans Gerd Nothwang
- Neurogenetics Group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, Germany
- Research Center for Neurosensory Science, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, Germany
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Ullah I, Subhan F, Lu Z, Chan SW, Rudd JA. Action of Bacopa monnieri to antagonize cisplatin-induced emesis in Suncus murinus (house musk shrew). J Pharmacol Sci 2017; 133:232-239. [PMID: 28363413 DOI: 10.1016/j.jphs.2017.03.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 01/27/2017] [Accepted: 03/01/2017] [Indexed: 10/20/2022] Open
Abstract
Bacopa monnieri (BM, family Scrophulariaceae) is used in several traditional systems of medicine for the management of epilepsy, depression, neuropathic pain, sleep disorders and memory deficits. The present study investigated the potential of BM methanol (BM-MetFr) and BM n-butanol fractions (BM-ButFr) to reduce chemotherapy-induced emesis in Suncus murinus (house musk shrew). Cisplatin (30 mg/kg, i.p.) reliably induced retching and/or vomiting over a 2 day period. BM-MetFr (10-40 mg/kg, s.c.) and BM-ButFr (5-20 mg/kg, s.c.) antagonized the retching and/or vomiting response by ∼59.4% (p < 0.05) and 78.9% (p < 0.05), respectively, while the 5-HT3 receptor antagonist, palonosetron (0.5 mg/kg, s.c.), reduced the response by ∼71% (p < 0.05). The free radical scavenger/antioxidant, N-(2-mercaptopropionyl)-glycine (30-300 mg/kg, s.c.) reduced the retching and/or vomiting response occurring on day one non-significantly by 44% (p > 0.05). In conclusion, the n-butanol fractions of BM have anti-emetic activity comparable with palonosetron and MPG. BM may be useful alone or in combination with other anti-emetic drugs for the treatment of chemotherapy-induced emesis in man.
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Affiliation(s)
- Ihsan Ullah
- Department of Pharmacy, University of Swabi, Swabi, Pakistan; Department of Pharmacy, University of Peshawar, Peshawar, Pakistan
| | - Fazal Subhan
- Department of Pharmacy, University of Peshawar, Peshawar, Pakistan
| | - Zengbing Lu
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong
| | - Sze Wa Chan
- School of Health Sciences, Caritas Institute of Higher Education, Tseung Kwan O, N.T., Hong Kong
| | - John A Rudd
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong; Brain and Mind Institute, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
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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] [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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Hartwich H, Rosengauer E, Rüttiger L, Wilms V, Waterholter SK, Nothwang HG. Functional Role of γ-Crystallin N in the Auditory Hindbrain. PLoS One 2016; 11:e0161140. [PMID: 27517863 PMCID: PMC4982622 DOI: 10.1371/journal.pone.0161140] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 07/30/2016] [Indexed: 12/20/2022] Open
Abstract
γ-crystallins are major components of the vertebrate lens but show expression in other tissues as well. Their extralenticular functions remain so far unclear. Here, we explored such roles in the rodent superior olivary complex in which previous analysis demonstrated developmentally regulated expression of Crygd, Cryge and Crygn. Immunohistochemistry with novel antibodies against Crygd/e and Crygn indicate that expression of Crygd/e was moderate and varied between the perinatal superior olivary complex of mice, rats, and gerbils. Crygn-immunoreactivity was more robust and consistently highest in the medial nucleus of the trapezoid body, but also present in other nuclei of the superior olivary complex. To analyze the function of Crygn in the auditory hindbrain, we used a Crygn allele with a floxed exon 2. Upon pairing with Egr2::Cre mice, exon 2, encoding the first two greek key motifs of Crygn, was deleted in the developing auditory hindbrain. Anatomical analysis of these mice revealed a 20% volume reduction in the medial nucleus of the trapezoid body and a 7% reduction in the lateral superior olive at postnatal day 25. This was due to cell loss between postnatal days 4 and 25, whereas cell size was unaffected. Auditory brainstem responses showed normal threshold but a significant increase in the amplitude of wave IV. Crygn is hence required for postmigratory survival and proper function of auditory hindbrain neurons. These results ascertain for the first time an essential extralenticular role for γ-crystallins in vivo.
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Affiliation(s)
- Heiner Hartwich
- Neurogenetics group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
| | - Elena Rosengauer
- Neurogenetics group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
| | - Lukas Rüttiger
- University of Tübingen, Department of Otolaryngology, Hearing Research Centre Tübingen (THRC), Molecular Physiology of Hearing, Elfriede Aulhorn Str. 5, 72076, Tübingen, Germany
| | - Viviane Wilms
- Neurogenetics group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
| | - Sarah-Kristin Waterholter
- Neurogenetics group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
| | - Hans Gerd Nothwang
- Neurogenetics group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
- Research Center for Neurosensory Science, Carl von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
- * E-mail:
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Ebbers L, Runge K, Nothwang HG. Differential patterns of histone methylase EHMT2 and its catalyzed histone modifications H3K9me1 and H3K9me2 during maturation of central auditory system. Cell Tissue Res 2016; 365:247-64. [PMID: 27083448 DOI: 10.1007/s00441-016-2401-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 03/24/2016] [Indexed: 12/31/2022]
Abstract
Histone methylation is an important epigenetic mark leading to changes in DNA accessibility and transcription. Here, we investigate immunoreactivity against the euchromatic histone-lysine N-methyltransferase EHMT2 and its catalyzed mono- and dimethylation marks at histone 3 lysine 9 (H3K9me1 and H3K9me2) during postnatal differentiation of the mouse central auditory system. In the brainstem, expression of EHMT2 was high in the first postnatal week and down-regulated thereafter. In contrast, immunoreactivity in the auditory cortex (AC) remained high during the first year of life. This difference might be related to distinct demands for adult plasticity. Analyses of two deaf mouse models, namely Cldn14 (-/-) and Cacna1d (-/-), demonstrated that sound-driven or spontaneous activity had no influence on EHMT2 immunoreactivity. The methylation marks H3K9me1 and H3K9me2 were high throughout the auditory system up to 1 year. Young auditory neurons showed immunoreactivity against both methylations at similar intensities, whereas many mature neurons showed stronger labeling for either H3K9me1 or H3K9me2. These differences were only poorly correlated with cell types. To identify methyltransferases contributing to the persistent H3K9me1 and H3K9me2 marks in the adult brainstem, EHMT1 and the retinoblastoma-interacting zinc-finger protein RIZ1 were analyzed. Both were down-regulated during brainstem development, similar to EHMT2. Contrary to EHMT2, EHMT1 was also down-regulated in adult cortical areas. Together, our data reveal a marked difference in EHMT2 levels between mature brainstem and cortical areas and a decoupling between EHMT2 abundance and histone 3 lysine 9 methylations during brainstem differentiation. Furthermore, EHMT1 and EHMT2 are differentially expressed in cortical areas.
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Affiliation(s)
- Lena Ebbers
- Neurogenetics Group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
| | - Karen Runge
- Neurogenetics Group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111, Oldenburg, Germany
| | - Hans Gerd Nothwang
- Neurogenetics Group, Center of Excellence Hearing4All, School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, 26111, Oldenburg, Germany. .,Research Center for Neurosensory Science, Carl von Ossietzky University Oldenburg, 26111, Oldenburg, Germany.
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