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Sun Y, Jia Y, Guo Y, Chen F, Yan Z. Taurine Transporter dEAAT2 is Required for Auditory Transduction in Drosophila. Neurosci Bull 2018; 34:939-950. [PMID: 30043098 PMCID: PMC6246829 DOI: 10.1007/s12264-018-0255-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 04/20/2018] [Indexed: 12/22/2022] Open
Abstract
Drosophila dEAAT2, a member of the excitatory amino-acid transporter (EAAT) family, has been described as mediating the high-affinity transport of taurine, which is a free amino-acid abundant in both insects and mammals. However, the role of taurine and its transporter in hearing is not clear. Here, we report that dEAAT2 is required for the larval startle response to sound stimuli. dEAAT2 was found to be enriched in the distal region of chordotonal neurons where sound transduction occurs. The Ca2+ imaging and electrophysiological results showed that disrupted dEAAT2 expression significantly reduced the response of chordotonal neurons to sound. More importantly, expressing dEAAT2 in the chordotonal neurons rescued these mutant phenotypes. Taken together, these findings indicate a critical role for Drosophila dEAAT2 in sound transduction by chordotonal neurons.
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Affiliation(s)
- Ying Sun
- State Key Laboratory of Medical Neurobiology, Human Phenome Institute, Ministry of Education Key Laboratory of Contemporary Anthropology, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Yanyan Jia
- State Key Laboratory of Medical Neurobiology, Human Phenome Institute, Ministry of Education Key Laboratory of Contemporary Anthropology, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Yifeng Guo
- State Key Laboratory of Medical Neurobiology, Human Phenome Institute, Ministry of Education Key Laboratory of Contemporary Anthropology, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai, 200438, China
| | - Fangyi Chen
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, 518055, China.
| | - Zhiqiang Yan
- State Key Laboratory of Medical Neurobiology, Human Phenome Institute, Ministry of Education Key Laboratory of Contemporary Anthropology, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, Shanghai, 200438, China.
- Department of Human Anatomy, School of Basic Medicine Sciences, Southwest Medical University, Luzhou, 646000, China.
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Eckhard A, Gleiser C, Rask-Andersen H, Arnold H, Liu W, Mack A, Müller M, Löwenheim H, Hirt B. Co-localisation of Kir4.1 and AQP4 in rat and human cochleae reveals a gap in water channel expression at the transduction sites of endocochlear K+ recycling routes. Cell Tissue Res 2012; 350:27-43. [DOI: 10.1007/s00441-012-1456-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Accepted: 05/22/2012] [Indexed: 11/30/2022]
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Takumi Y, Nagelhus EA, Eidet J, Matsubara A, Usami S, Shinkawa H, Nielsen S, Ottersen OP. Select types of supporting cell in the inner ear express aquaporin-4 water channel protein. Eur J Neurosci 1998; 10:3584-95. [PMID: 9875338 DOI: 10.1046/j.1460-9568.1998.00360.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Aquaporins (AQPs) confer a high water permeability on cell membranes and play important parts in secretory and absorptive epithelia in kidney and other organs. Here we investigate whether AQPs are expressed in the sensory epithelia of the inner ear, where a precise volume regulation is crucial. By use of specific antibodies it was found that the inner ear contains AQP1 and 4 while being devoid of detectable levels of AQP2, 3 or 5. Immunofluorescence and postembedding immunogold labelling revealed a strictly non-epithelial distribution of AQP1, confirming previous data. In contrast, AQP4 protein and mRNA (visualized by in situ hybridization) were concentrated in select types of supporting cell, including Hensen's cells and inner sulcus cells. Immunogold particles signalling AQP4 were confined to the basolateral plasma membrane of Hensen's cells and to the basal plasma membrane of Claudius cells and inner sulcus cells. AQP4 was also found in supporting cells of the vestibular end organs, but was absent from transitional epithelial cells and dark cells. Strong labelling for AQP4 and AQP4-mRNA was associated with the central part of the cochlear and vestibular nerves. Hair cells were consistently unlabelled. Our findings indicate that AQP4 may facilitate osmotically driven water fluxes in the sensory epithelia of the inner ear and thus contribute to the volume and ion homeostasis at these sites.
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Affiliation(s)
- Y Takumi
- Department of Anatomy, University of Oslo, Norway
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Dhillon SK, Davies WE, Hopkins PC, Rose SJ. Effects of dietary taurine on auditory function in full-term infants. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1998; 442:507-14. [PMID: 9635068 DOI: 10.1007/978-1-4899-0117-0_61] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Three groups of neonates fed taurine supplemented infant formula, non-supplemented infant formula or breast milk, respectively, were studied from birth to 12 weeks of age. In addition to the measurement of whole blood taurine content, auditory function was monitored using auditory brainstem responses (ABRs) and transient evoked otoacoustic emissions (TEOAEs). The results showed a significant reduction in whole blood taurine concentration in the non-supplemented formula group. In addition, there was a significant drop in whole blood taurine levels in all 3 groups over the first four weeks of life. ABR wave latencies were significantly shorter in the non-supplemented group, with wave V showing the greatest reductions. Falling taurine levels after full-term birth may aid synaptic maturation/efficiency within the auditory system. TEOAE responses were significantly larger over the low to mid frequencies in the breast fed group suggesting improved middle ear function.
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Affiliation(s)
- S K Dhillon
- Hearing Services Centre City Hospital, Birmingham, England
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5
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Abstract
Taurine is the second most abundant free amino acid in the brain where its osmoregulatory function is well established. Taurine-deprived kittens show retinal pathology leading to blindness. In the inner ear, taurine has been reported to be the most abundant free amino acid although its role in inner ear function is not known. Immunohistochemistry was employed here to investigate the localisation of taurine in normal cochleae of the guinea pig compared with two different conditions: experimentally induced endolymphatic hydrops and after oral administration of glycerol. In normal cochleae, by light microscopy, taurine-like immunoreaction was never observed in the sensory outer hair cells and appeared absent from the inner hair cells. In contrast taurine-like immunolabeling was found to be present in all supporting tissue with the striking exception of the tectorial membrane and the outer pillar cell which had no or little taurine immunoreactivity respectively. In early experimental endolymphatic hydrops, the distribution of taurine-like immunoreactivity appeared similar to that observed for normal cochleae. In long-term hydrops, degenerated outer hair cells were replaced by the swelling of the phalangeal process of the Deiters' cells which became highly immunoreactive to taurine. After glycerol administration, the tectorial membrane became more tightly bound to the apical surface of the sensory hair cells and distinctly immunoreactive to taurine. The localisation of taurine in the organ of Corti shown here is consistent with taurine being involved in the maintenance of osmotic equilibrium in the normal and perhaps also in the restructuration of the pathological organ of Corti.
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MESH Headings
- Administration, Oral
- Animals
- Cochlea/chemistry
- Cochlea/cytology
- Edema/chemically induced
- Edema/metabolism
- Edema/physiopathology
- Endolymph/chemistry
- Female
- Glycerol/administration & dosage
- Glycerol/toxicity
- Guinea Pigs
- Hair Cells, Auditory, Inner/chemistry
- Hair Cells, Auditory, Inner/cytology
- Hair Cells, Auditory, Outer/chemistry
- Hair Cells, Auditory, Outer/cytology
- Immune Sera/immunology
- Immunohistochemistry
- Solvents/administration & dosage
- Solvents/toxicity
- Taurine/analysis
- Taurine/immunology
- Tectorial Membrane/chemistry
- Vestibular Nucleus, Lateral/chemistry
- Vestibular Nucleus, Lateral/cytology
- Water-Electrolyte Balance
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Affiliation(s)
- K C Horner
- INSERM, Laboratoire d'Audiologie Expérimentale, Université Bordeaux II, France
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Davies WE, Hopkins PC, Rose SJ, Dhillon SK. The influence of different taurine diets on hearing development in normal babies. A preliminary report. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1996; 403:631-7. [PMID: 8915404 DOI: 10.1007/978-1-4899-0182-8_70] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- W E Davies
- Department of Pharmacology, Medical School, University of Birmingham, USA
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7
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Usami S, Ottersen OP. Immunocytochemical localization of taurine in the inner ear. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1996; 403:361-8. [PMID: 8915372 DOI: 10.1007/978-1-4899-0182-8_38] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- S Usami
- Department of Otorhinolaryngology, Hirosaki University School of Medicine, Japan
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