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Liang Y, Ormazabal-Toledo R, Yao S, Shi YS, Herrera-Molina R, Montag D, Lin X. Deafness causing neuroplastin missense variants fail to promote plasma membrane Ca 2+-ATPase levels and Ca 2+ transient regulation in brain neurons. J Biol Chem 2024; 300:107474. [PMID: 38879011 DOI: 10.1016/j.jbc.2024.107474] [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: 02/12/2024] [Revised: 06/06/2024] [Accepted: 06/09/2024] [Indexed: 07/08/2024] Open
Abstract
Hearing, the ability to sense sounds, and the processing of auditory information are important for perception of the world. Mice lacking expression of neuroplastin (Np), a type-1 transmembrane glycoprotein, display deafness, multiple cognitive deficiencies, and reduced expression of plasma membrane calcium (Ca2+) ATPases (PMCAs) in cochlear hair cells and brain neurons. In this study, we transferred the deafness causing missense mutations pitch (C315S) and audio-1 (I122N) into human Np (hNp) constructs and investigated their effects at the molecular and cellular levels. Computational molecular dynamics show that loss of the disulfide bridge in hNppitch causes structural destabilization of immunoglobulin-like domain (Ig) III and that the novel asparagine in hNpaudio-1 results in steric constraints and an additional N-glycosylation site in IgII. Additional N-glycosylation of hNpaudio-1 was confirmed by PNGaseF treatment. In comparison to hNpWT, transfection of hNppitch and hNpaudio-1 into HEK293T cells resulted in normal mRNA levels but reduced the Np protein levels and their cell surface expression due to proteasomal/lysosomal degradation. Furthermore, hNppitch and hNpaudio-1 failed to promote exogenous PMCA levels in HEK293T cells. In hippocampal neurons, expression of additional hNppitch or hNpaudio-1 was less efficient than hNpWT to elevate endogenous PMCA levels and to accelerate the restoration of basal Ca2+ levels after electrically evoked Ca2+ transients. We propose that mutations leading to pathological Np variants, as exemplified here by the deafness causing Np mutants, can affect Np-dependent Ca2+ regulatory mechanisms and may potentially cause intellectual and cognitive deficits in humans.
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Affiliation(s)
- Yi Liang
- Neurogenetics Laboratory, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Rodrigo Ormazabal-Toledo
- Departamento de Química Orgánica y Fisicoquímica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Songhui Yao
- Guangdong Institute of Intelligence Science and Technology, Zhuhai, Guangdong, China
| | - Yun Stone Shi
- Guangdong Institute of Intelligence Science and Technology, Zhuhai, Guangdong, China
| | - Rodrigo Herrera-Molina
- Neurogenetics Laboratory, Leibniz Institute for Neurobiology, Magdeburg, Germany; Centro Integrativo de Biología y Química Aplicada, Universidad Bernardo O'Higgins, Santiago, Chile
| | - Dirk Montag
- Neurogenetics Laboratory, Leibniz Institute for Neurobiology, Magdeburg, Germany.
| | - Xiao Lin
- Neurogenetics Laboratory, Leibniz Institute for Neurobiology, Magdeburg, Germany; Guangdong Institute of Intelligence Science and Technology, Zhuhai, Guangdong, China.
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2
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Calcium signaling and genetic rare diseases: An auditory perspective. Cell Calcium 2023; 110:102702. [PMID: 36791536 DOI: 10.1016/j.ceca.2023.102702] [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: 12/14/2022] [Revised: 02/01/2023] [Accepted: 02/02/2023] [Indexed: 02/07/2023]
Abstract
Deafness is a highly heterogeneous disorder which stems, for 50%, from genetic origins. Sensory transduction relies mainly on sensory hair cells of the cochlea, in the inner ear. Calcium is key for the function of these cells and acts as a fundamental signal transduction. Its homeostasis depends on three factors: the calcium influx, through the mechanotransduction channel at the apical pole of the hair cell as well as the voltage-gated calcium channel at the base of the cells; the calcium buffering via Ca2+-binding proteins in the cytoplasm, but also in organelles such as mitochondria and the reticulum endoplasmic mitochondria-associated membranes with specialized proteins; and the calcium extrusion through the Ca-ATPase pump, located all over the plasma membrane. In addition, the synaptic transmission to the central nervous system is also controlled by calcium. Genetic studies of inherited deafness have tremendously helped understand the underlying molecular pathways of calcium signaling. In this review, we discuss these different factors in light of the associated genetic diseases (syndromic and non-syndromic deafness) and the causative genes.
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3
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Beckmann D, Langnaese K, Gottfried A, Hradsky J, Tedford K, Tiwari N, Thomas U, Fischer KD, Korthals M. Ca 2+ Homeostasis by Plasma Membrane Ca 2+ ATPase (PMCA) 1 Is Essential for the Development of DP Thymocytes. Int J Mol Sci 2023; 24:ijms24021442. [PMID: 36674959 PMCID: PMC9865543 DOI: 10.3390/ijms24021442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/22/2022] [Accepted: 12/30/2022] [Indexed: 01/13/2023] Open
Abstract
The strength of Ca2+ signaling is a hallmark of T cell activation, yet the role of Ca2+ homeostasis in developing T cells before expressing a mature T cell receptor is poorly understood. We aimed to unveil specific functions of the two plasma membrane Ca2+ ATPases expressed in T cells, PMCA1 and PMCA4. On a transcriptional and protein level we found that PMCA4 was expressed at low levels in CD4-CD8- double negative (DN) thymocytes and was even downregulated in subsequent stages while PMCA1 was present throughout development and upregulated in CD4+CD8+ double positive (DP) thymocytes. Mice with a targeted deletion of Pmca1 in DN3 thymocytes had an almost complete block of DP thymocyte development with an accumulation of DN4 thymocytes but severely reduced numbers of CD8+ immature single positive (ISP) thymocytes. The DN4 thymocytes of these mice showed strongly elevated basal cytosolic Ca2+ levels and a pre-mature CD5 expression, but in contrast to the DP thymocytes they were only mildly prone to apoptosis. Surprisingly, mice with a germline deletion of Pmca4 did not show any signs of altered progression through the developmental thymocyte stages, nor altered Ca2+ homeostasis throughout this process. PMCA1 is, therefore, non-redundant in keeping cellular Ca2+ levels low in the early thymocyte development required for the DN to DP transition.
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Affiliation(s)
- David Beckmann
- Institute for Biochemistry and Cell Biology, Medical Faculty, Otto-von-Guericke-University Magdeburg, 39120 Magdeburg, Germany
| | - Kristina Langnaese
- Institute for Biochemistry and Cell Biology, Medical Faculty, Otto-von-Guericke-University Magdeburg, 39120 Magdeburg, Germany
| | - Anna Gottfried
- Institute for Biochemistry and Cell Biology, Medical Faculty, Otto-von-Guericke-University Magdeburg, 39120 Magdeburg, Germany
| | - Johannes Hradsky
- Institute for Biochemistry and Cell Biology, Medical Faculty, Otto-von-Guericke-University Magdeburg, 39120 Magdeburg, Germany
| | - Kerry Tedford
- Institute for Biochemistry and Cell Biology, Medical Faculty, Otto-von-Guericke-University Magdeburg, 39120 Magdeburg, Germany
| | - Nikhil Tiwari
- Department of Cellular Neuroscience, Leibniz Institute for Neurobiology, 39120 Magdeburg, Germany
| | - Ulrich Thomas
- Department of Cellular Neuroscience, Leibniz Institute for Neurobiology, 39120 Magdeburg, Germany
| | - Klaus-Dieter Fischer
- Institute for Biochemistry and Cell Biology, Medical Faculty, Otto-von-Guericke-University Magdeburg, 39120 Magdeburg, Germany
- Correspondence:
| | - Mark Korthals
- Institute for Biochemistry and Cell Biology, Medical Faculty, Otto-von-Guericke-University Magdeburg, 39120 Magdeburg, Germany
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4
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Huang S, Qian S. Advances in otolith-related protein research. Front Neurosci 2022; 16:956200. [PMID: 35958995 PMCID: PMC9361852 DOI: 10.3389/fnins.2022.956200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 06/27/2022] [Indexed: 11/16/2022] Open
Abstract
Otoliths are biological crystals formed by a layer of calcium carbonate crystal that adhere to the ciliary surface of the utricular and saccular receptors in the vestibule of all vertebrates inner ear, enabling the utricle and saccule to better perceive the changes in linear and gravitational acceleration. However, the molecular etiology of otolith related diseases is still unclear. In this review, we have summarized the recent findings and provided an overview of the proteins that play important roles in otolith formation and maintenance (Otoconin-90, Otolin-1, Otolith Matrix Protein-1, Cochlin, Otogelin, α-Tectorin, β-Tectorin, Otopetrin-1, and Otopetrin-2, PMCA2, etc.), providing new insight for the prevention and management of benign paroxysmal positional vertigo (BPPV) with basis for otolith-related proteins as potential biomarkers of vestibular disease.
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Affiliation(s)
- Shouju Huang
- The Fourth School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, China
- Department of Neurology, The Second Affiliated Hospital of Jiaxing University, Jiaxing, China
| | - Shuxia Qian
- Department of Neurology, The Second Affiliated Hospital of Jiaxing University, Jiaxing, China
- *Correspondence: Shuxia Qian,
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5
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Shankhwar S, Schwarz K, Katiyar R, Jung M, Maxeiner S, Südhof TC, Schmitz F. RIBEYE B-Domain Is Essential for RIBEYE A-Domain Stability and Assembly of Synaptic Ribbons. Front Mol Neurosci 2022; 15:838311. [PMID: 35153673 PMCID: PMC8831697 DOI: 10.3389/fnmol.2022.838311] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 01/03/2022] [Indexed: 01/17/2023] Open
Abstract
Synaptic ribbons are presynaptic specializations that define eponymous ribbon synapses. Synaptic ribbons are largely composed of RIBEYE, a protein containing an N-terminal A-domain and a carboxyterminal B-domain that is identical with CtBP2, a NAD(H)-binding transcriptional co-repressor. Previously we showed that synaptic ribbons are completely absent in RIBEYE knockout mice in which the RIBEYE A-domain-encoding exon had been deleted, but CtBP2 is still made, demonstrating that the A-domain is required for synaptic ribbon assembly. In the present study, we asked whether the RIBEYE B-domain also has an essential role in the assembly of synaptic ribbons. For this purpose, we made use of RIBEYE knockin mice in which the RIBEYE B-domain was replaced by a fluorescent protein domain, whereas the RIBEYE A-domain was retained unchanged. We found that replacing the RIBEYE B-domain with a fluorescent protein module destabilizes the resulting hybrid protein and causes a complete loss of synaptic ribbons. Our results thus demonstrate an essential role of the RIBEYE B-domain in enabling RIBEYE assembly into synaptic ribbons, reinforcing the notion that RIBEYE is the central organizer of synaptic ribbons.
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Affiliation(s)
- Soni Shankhwar
- Institute of Anatomy and Cell Biology, Saarland University, Medical School, Homburg, Germany
- *Correspondence: Soni Shankhwar Frank Schmitz
| | - Karin Schwarz
- Institute of Anatomy and Cell Biology, Saarland University, Medical School, Homburg, Germany
| | - Rashmi Katiyar
- Institute of Anatomy and Cell Biology, Saarland University, Medical School, Homburg, Germany
| | - Martin Jung
- Institute of Medical Biochemistry and Molecular Biology, Saarland University, Medical School, Homburg, Germany
| | - Stephan Maxeiner
- Institute of Anatomy and Cell Biology, Saarland University, Medical School, Homburg, Germany
| | - Thomas C. Südhof
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA, United States
| | - Frank Schmitz
- Institute of Anatomy and Cell Biology, Saarland University, Medical School, Homburg, Germany
- *Correspondence: Soni Shankhwar Frank Schmitz
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6
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Structure, Function and Regulation of the Plasma Membrane Calcium Pump in Health and Disease. Int J Mol Sci 2022; 23:ijms23031027. [PMID: 35162948 PMCID: PMC8835232 DOI: 10.3390/ijms23031027] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 12/30/2021] [Accepted: 01/06/2022] [Indexed: 12/28/2022] Open
Abstract
In this review, I summarize the present knowledge of the structural and functional properties of the mammalian plasma membrane calcium pump (PMCA). It is outlined how the cellular expression of the different spliced isoforms of the four genes are regulated under normal and pathological conditions.
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7
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Lin X, Liang Y, Herrera-Molina R, Montag D. Neuroplastin in Neuropsychiatric Diseases. Genes (Basel) 2021; 12:1507. [PMID: 34680901 PMCID: PMC8535836 DOI: 10.3390/genes12101507] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/20/2021] [Accepted: 09/21/2021] [Indexed: 02/07/2023] Open
Abstract
Molecular mechanisms underlying neuropsychiatric and neurodegenerative diseases are insufficiently elucidated. A detailed understanding of these mechanisms may help to further improve medical intervention. Recently, intellectual abilities, creativity, and amnesia have been associated with neuroplastin, a cell recognition glycoprotein of the immunoglobulin superfamily that participates in synapse formation and function and calcium signaling. Data from animal models suggest a role for neuroplastin in pathways affected in neuropsychiatric and neurodegenerative diseases. Neuroplastin loss or disruption of molecular pathways related to neuronal processes has been linked to various neurological diseases, including dementia, schizophrenia, and Alzheimer's disease. Here, we review the molecular features of the cell recognition molecule neuroplastin, and its binding partners, which are related to neurological processes and involved in learning and memory. The emerging functions of neuroplastin may have implications for the treatment of diseases, particularly those of the nervous system.
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Affiliation(s)
- Xiao Lin
- Neurogenetics Laboratory, Leibniz Institute for Neurobiology, Brenneckestr. 6, D-39118 Magdeburg, Germany; (X.L.); (Y.L.)
| | - Yi Liang
- Neurogenetics Laboratory, Leibniz Institute for Neurobiology, Brenneckestr. 6, D-39118 Magdeburg, Germany; (X.L.); (Y.L.)
| | - Rodrigo Herrera-Molina
- Combinatorial NeuroImaging (CNI), Leibniz Institute for Neurobiology, Brenneckestr. 6, D-39118 Magdeburg, Germany;
- Centro Integrativo de Biología y Química Aplicada, Universidad Bernardo O’Higgins, Santiago 8307993, Chile
- Center for Behavioral Brain Sciences (CBBS), D-39106 Magdeburg, Germany
| | - Dirk Montag
- Neurogenetics Laboratory, Leibniz Institute for Neurobiology, Brenneckestr. 6, D-39118 Magdeburg, Germany; (X.L.); (Y.L.)
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8
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Crosstalk among Calcium ATPases: PMCA, SERCA and SPCA in Mental Diseases. Int J Mol Sci 2021; 22:ijms22062785. [PMID: 33801794 PMCID: PMC8000800 DOI: 10.3390/ijms22062785] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 03/07/2021] [Accepted: 03/08/2021] [Indexed: 12/20/2022] Open
Abstract
Calcium in mammalian neurons is essential for developmental processes, neurotransmitter release, apoptosis, and signal transduction. Incorrectly processed Ca2+ signal is well-known to trigger a cascade of events leading to altered response to variety of stimuli and persistent accumulation of pathological changes at the molecular level. To counterbalance potentially detrimental consequences of Ca2+, neurons are equipped with sophisticated mechanisms that function to keep its concentration in a tightly regulated range. Calcium pumps belonging to the P-type family of ATPases: plasma membrane Ca2+-ATPase (PMCA), sarco/endoplasmic Ca2+-ATPase (SERCA) and secretory pathway Ca2+-ATPase (SPCA) are considered efficient line of defense against abnormal Ca2+ rises. However, their role is not limited only to Ca2+ transport, as they present tissue-specific functionality and unique sensitive to the regulation by the main calcium signal decoding protein—calmodulin (CaM). Based on the available literature, in this review we analyze the contribution of these three types of Ca2+-ATPases to neuropathology, with a special emphasis on mental diseases.
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9
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Cochlear homeostasis: a molecular physiological perspective on maintenance of sound transduction and auditory neurotransmission with noise and ageing. CURRENT OPINION IN PHYSIOLOGY 2020. [DOI: 10.1016/j.cophys.2020.09.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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10
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Hegedűs L, Zámbó B, Pászty K, Padányi R, Varga K, Penniston JT, Enyedi Á. Molecular Diversity of Plasma Membrane Ca2+ Transporting ATPases: Their Function Under Normal and Pathological Conditions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:93-129. [DOI: 10.1007/978-3-030-12457-1_5] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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11
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Lu X, Wang Q, Gu H, Zhang X, Qi Y, Liu Y. Whole exome sequencing identified a second pathogenic variant in HOMER2 for autosomal dominant non-syndromic deafness. Clin Genet 2019; 94:419-428. [PMID: 30047143 DOI: 10.1111/cge.13422] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Revised: 06/26/2018] [Accepted: 07/19/2018] [Indexed: 12/11/2022]
Abstract
Hearing loss is one of the most common sensory disorders worldwide, and about half of all occurrences are attributable to genetic factors. Here, we have identified a novel pathogenic variant in HOMER2 in a Chinese family with autosomal dominant, non-syndromic hearing loss. This is the second family reported globally with hearing loss caused by a variant in HOMER2. The pathogenic variant c.840_841insC in HOMER2 (NM_199330), segregating with the hearing-loss phenotype in the family, leads to a premature stop codon producing a truncated protein. The coiled-coil domain in the C-terminal of HOMER2 protein is essential for protein multimerization and HOMER2-CDC42 interaction. We compared the phenotypes in the two families and found that hearing impairment in this Chinese family was more severe. Furthermore, we found that the ability of this insertion mutant type HOMER2 (HOMER2MU ) to multimerize decreased more significantly than wild-type HOMER2 (HOMER2WT ) and the reported c.554G>C (NM_004839) mutant HOMER2. HOMER2MU protein tended to be distributed in a diffuse manner, whereas HOMER2WT and the reported mutant HOMER2 tended to cluster together. Our research provides a validating second family for variants in HOMER2 causing non-syndromic sensorineural hearing loss. HOMER2 homo-/hetero-multimerization might be the first step in exerting its normal function.
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Affiliation(s)
- X Lu
- Department of Otolaryngology, Head and Neck Surgery, Peking University First Hospital, Beijing, China
| | - Q Wang
- Department of Otolaryngology, Head and Neck Surgery, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - H Gu
- Department of Otolaryngology, Head and Neck Surgery, Peking University First Hospital, Beijing, China
| | - X Zhang
- Department of Otolaryngology, Head and Neck Surgery, Peking University First Hospital, Beijing, China
| | - Y Qi
- Department of Central Laboratory, Peking University First Hospital, Beijing, China
| | - Y Liu
- Department of Otolaryngology, Head and Neck Surgery, Peking University First Hospital, Beijing, China
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12
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Lang I, Jung M, Niemeyer BA, Ruth P, Engel J. Expression of the LRRC52 γ subunit (γ2) may provide Ca 2+-independent activation of BK currents in mouse inner hair cells. FASEB J 2019; 33:11721-11734. [PMID: 31348683 DOI: 10.1096/fj.201900701rr] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Mammalian inner hair cells (IHCs) transduce sound into depolarization and transmitter release. Big conductance and voltage- and Ca2+-activated K+ (BK) channels are responsible for fast membrane repolarization and small time constants of mature IHCs. For unknown reasons, they activate at around -75 mV with a voltage of half-maximum activation (Vhalf) of -50 mV although being largely insensitive to Ca2+ influx. Ca2+-independent activation of BK channels was observed by others in heterologous expression systems if γ subunits leucine-rich repeat-containing protein (LRRC)26 (γ1) and LRRC52 (γ2) were coexpressed with the pore-forming BKα subunit, which shifted Vhalf by -140 and -100 mV, respectively. Using nested PCR, we consistently detected transcripts for LRRC52 but not for LRRC26 in IHCs of 3-wk-old mice. Confocal immunohistochemistry showed synchronous up-regulation of LRRC52 protein with BKα at the onset of hearing. Colocalization of LRRC52 protein and BKα at the IHC neck within ≤40 nm was specified using an in situ proximity ligation assay. Mice deficient for the voltage-gated Cav1.3 Ca2+ channel encoded by Cacna1d do not express BKα protein. LRRC52 protein was neither expressed in IHCs of BKα nor in IHCs of Cav1.3 knockout mice. Together, LRRC52 is a γ2 subunit of BK channel complexes and is a strong candidate for causing the Ca2+-independent activation of BK currents at negative membrane potentials in mouse IHCs.-Lang, I., Jung, M., Niemeyer, B. A., Ruth, P., Engel, J. Expression of the LRRC52 γ subunit (γ2) may provide Ca2+-independent activation of BK currents in mouse inner hair cells.
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Affiliation(s)
- Isabelle Lang
- Hearing Research, Department of Biophysics and Center for Integrative Physiology and Molecular Medicine (CIPMM), Saarland University, Homburg, Germany
| | - Martin Jung
- Department of Biochemistry and Molecular Biology, Saarland University, Homburg, Germany
| | - Barbara A Niemeyer
- Molecular Biophysics, Department of Biophysics and Center for Integrative Physiology and Molecular Medicine (CIPMM), Saarland University, Homburg, Germany
| | - Peter Ruth
- Institute of Pharmacy, Department of Pharmacology, Toxicology and Clinical Pharmacy, University of Tübingen, Tübingen, Germany
| | - Jutta Engel
- Hearing Research, Department of Biophysics and Center for Integrative Physiology and Molecular Medicine (CIPMM), Saarland University, Homburg, Germany
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13
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Smits JJ, Oostrik J, Beynon AJ, Kant SG, de Koning Gans PAM, Rotteveel LJC, Klein Wassink-Ruiter JS, Free RH, Maas SM, van de Kamp J, Merkus P, Koole W, Feenstra I, Admiraal RJC, Lanting CP, Schraders M, Yntema HG, Pennings RJE, Kremer H. De novo and inherited loss-of-function variants of ATP2B2 are associated with rapidly progressive hearing impairment. Hum Genet 2018; 138:61-72. [PMID: 30535804 PMCID: PMC6514080 DOI: 10.1007/s00439-018-1965-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 11/30/2018] [Indexed: 01/21/2023]
Abstract
ATP2B2 encodes the PMCA2 Ca2+ pump that plays an important role in maintaining ion homeostasis in hair cells among others by extrusion of Ca2+ from the stereocilia to the endolymph. Several mouse models have been described for this gene; mice heterozygous for loss-of-function defects display a rapidly progressive high-frequency hearing impairment. Up to now ATP2B2 has only been reported as a modifier, or in a digenic mechanism with CDH23 for hearing impairment in humans. Whole exome sequencing in hearing impaired index cases of Dutch and Polish origins revealed five novel heterozygous (predicted to be) loss-of-function variants of ATP2B2. Two variants, c.1963G>T (p.Glu655*) and c.955delG (p.Ala319fs), occurred de novo. Three variants c.397+1G>A (p.?), c.1998C>A (p.Cys666*), and c.2329C>T (p.Arg777*), were identified in families with an autosomal dominant inheritance pattern of hearing impairment. After normal newborn hearing screening, a rapidly progressive high-frequency hearing impairment was diagnosed at the age of about 3–6 years. Subjects had no balance complaints and vestibular testing did not yield abnormalities. There was no evidence for retrocochlear pathology or structural inner ear abnormalities. Although a digenic inheritance pattern of hearing impairment has been reported for heterozygous missense variants of ATP2B2 and CDH23, our findings indicate a monogenic cause of hearing impairment in cases with loss-of-function variants of ATP2B2.
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Affiliation(s)
- Jeroen J Smits
- Hearing and Genes, Department of Otorhinolaryngology, Head and Neck Surgery, Radboud University Medical Center, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jaap Oostrik
- Hearing and Genes, Department of Otorhinolaryngology, Head and Neck Surgery, Radboud University Medical Center, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Andy J Beynon
- Hearing and Genes, Department of Otorhinolaryngology, Head and Neck Surgery, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Sarina G Kant
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Pia A M de Koning Gans
- Department of Clinical Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | | | | | - Rolien H Free
- Department of Otorhinolaryngology, Head and Neck Surgery, University Medical Center Groningen, Groningen, The Netherlands
| | - Saskia M Maas
- Department of Clinical Genetics, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Jiddeke van de Kamp
- Department of Clinical Genetics, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Paul Merkus
- Department of Otolaryngology, Head and Neck Surgery, Ear and Hearing, Amsterdam Public Health Research Institute, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Wouter Koole
- Hearing and Genes, Department of Human Genetics, Radboud University Medical Center, Internal postal code 855, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Ilse Feenstra
- Hearing and Genes, Department of Human Genetics, Radboud University Medical Center, Internal postal code 855, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Ronald J C Admiraal
- Hearing and Genes, Department of Otorhinolaryngology, Head and Neck Surgery, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Cornelis P Lanting
- Hearing and Genes, Department of Otorhinolaryngology, Head and Neck Surgery, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Margit Schraders
- Hearing and Genes, Department of Otorhinolaryngology, Head and Neck Surgery, Radboud University Medical Center, Nijmegen, The Netherlands
- Hearing and Genes, Department of Human Genetics, Radboud University Medical Center, Internal postal code 855, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Helger G Yntema
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
- Hearing and Genes, Department of Human Genetics, Radboud University Medical Center, Internal postal code 855, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Ronald J E Pennings
- Hearing and Genes, Department of Otorhinolaryngology, Head and Neck Surgery, Radboud University Medical Center, Nijmegen, The Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Hannie Kremer
- Hearing and Genes, Department of Otorhinolaryngology, Head and Neck Surgery, Radboud University Medical Center, Nijmegen, The Netherlands.
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands.
- Hearing and Genes, Department of Human Genetics, Radboud University Medical Center, Internal postal code 855, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands.
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Fettiplace R, Nam JH. Tonotopy in calcium homeostasis and vulnerability of cochlear hair cells. Hear Res 2018; 376:11-21. [PMID: 30473131 DOI: 10.1016/j.heares.2018.11.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 11/05/2018] [Accepted: 11/08/2018] [Indexed: 12/18/2022]
Abstract
Ototoxicity, noise overstimulation, or aging, can all produce hearing loss with similar properties, in which outer hair cells (OHCs), principally those at the high-frequency base of the cochlea, are preferentially affected. We suggest that the differential vulnerability may partly arise from differences in Ca2+ balance among cochlear locations. Homeostasis is determined by three factors: Ca2+ influx mainly via mechanotransducer (MET) channels; buffering by calcium-binding proteins and organelles like mitochondria; and extrusion by the plasma membrane CaATPase pump. We review quantification of these parameters and use our experimentally-determined values to model changes in cytoplasmic and mitochondrial Ca2+ during Ca2+ influx through the MET channels. We suggest that, in OHCs, there are two distinct micro-compartments for Ca2+ handling, one in the hair bundle and the other in the cell soma. One conclusion of the modeling is that there is a tonotopic gradient in the ability of OHCs to handle the Ca2+ load, which correlates with their vulnerability to environmental challenges. High-frequency basal OHCs are the most susceptible because they have much larger MET currents and have smaller dimensions than low-frequency apical OHCs.
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Affiliation(s)
- Robert Fettiplace
- Department of Neuroscience, University of Wisconsin, Madison, WI, 53706, USA.
| | - Jong-Hoon Nam
- Departments of Mechanical Engineering and Biomedical Engineering, University of Rochester, Rochester, NY, 14627, USA
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