1
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Kim EJ, Doh H, Yang J, Eyun SI. The occurrence of positive selection on BicA transporter of Microcystis aeruginosa. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 283:116795. [PMID: 39083868 DOI: 10.1016/j.ecoenv.2024.116795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 07/10/2024] [Accepted: 07/24/2024] [Indexed: 08/02/2024]
Abstract
The rapid growth of cyanobacteria, particularly Microcystis aeruginosa, poses a significant threat to global water security. The proliferation of toxic Microcystis aeruginosa raises concerns due to its potential harm to human health and socioeconomic impacts. Dense blooms contribute to spatiotemporal inorganic carbon depletion, promoting interest in the roles of carbon-concentrating mechanisms (CCMs) for competitive carbon uptake. Despite the importance of HCO3- transporters, genetic evaluations and functional predictions in M. aeruginosa remain insufficient. In this study, we explored the diversity of HCO3- transporters in the genomes of 46 strains of M. aeruginosa, assessing positive selection for each. Intriguingly, although the Microcystis BicA transporter became a partial gene in 23 out of 46 genomic strains, we observed significant positive sites. Structural analyses, including predicted 2D and 3D models, confirmed the structural conservation of the Microcystis BicA transporter. Our findings suggest that the Microcystis BicA transport likely plays a crucial role in competitive carbon uptake, emphasizing its ecological significance. The ecological function of the Microcystis BicA transport in competitive growth during cyanobacterial blooms raises important questions. Future studies require experimental confirmation to better understand the role of the Microcysits BicA transporter in cyanobacterial blooms dynamics.
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Affiliation(s)
- Eun-Jeong Kim
- Department of Life Science, Chung-Ang University, Seoul 06974, Korea
| | - Huijeong Doh
- Department of Life Science, Chung-Ang University, Seoul 06974, Korea
| | - Jihye Yang
- Department of Life Science, Chung-Ang University, Seoul 06974, Korea
| | - Seong-Il Eyun
- Department of Life Science, Chung-Ang University, Seoul 06974, Korea.
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2
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Takahashi S, Homma K. The molecular principles underlying diverse functions of the SLC26 family of proteins. J Biol Chem 2024; 300:107261. [PMID: 38582450 PMCID: PMC11078650 DOI: 10.1016/j.jbc.2024.107261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Revised: 03/07/2024] [Accepted: 03/30/2024] [Indexed: 04/08/2024] Open
Abstract
Mammalian SLC26 proteins are membrane-based anion transporters that belong to the large SLC26/SulP family, and many of their variants are associated with hereditary diseases. Recent structural studies revealed a strikingly similar homodimeric molecular architecture for several SLC26 members, implying a shared molecular principle. Now a new question emerges as to how these structurally similar proteins execute diverse physiological functions. In this study, we sought to identify the common versus distinct molecular mechanism among the SLC26 proteins using both naturally occurring and artificial missense changes introduced to SLC26A4, SLC26A5, and SLC26A9. We found: (i) the basic residue at the anion binding site is essential for both anion antiport of SLC26A4 and motor functions of SLC26A5, and its conversion to a nonpolar residue is crucial but not sufficient for the fast uncoupled anion transport in SLC26A9; (ii) the conserved polar residues in the N- and C-terminal cytosolic domains are likely involved in dynamic hydrogen-bonding networks and are essential for anion antiport of SLC26A4 but not for motor (SLC26A5) and uncoupled anion transport (SLC26A9) functions; (iii) the hydrophobic interaction between each protomer's last transmembrane helices, TM14, is not of functional significance in SLC26A9 but crucial for the functions of SLC26A4 and SLC26A5, likely contributing to optimally orient the axis of the relative movements of the core domain with respect to the gate domains within the cell membrane. These findings advance our understanding of the molecular mechanisms underlying the diverse physiological roles of the SLC26 family of proteins.
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Affiliation(s)
- Satoe Takahashi
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA; Center for Mechanical Excitability, The University of Chicago, Chicago, Illinois, USA
| | - Kazuaki Homma
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA; Center for Mechanical Excitability, The University of Chicago, Chicago, Illinois, USA; The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University, Evanston, Illinois, USA.
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3
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Geertsma ER, Oliver D. SLC26 Anion Transporters. Handb Exp Pharmacol 2024; 283:319-360. [PMID: 37947907 DOI: 10.1007/164_2023_698] [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] [Indexed: 11/12/2023]
Abstract
Solute carrier family 26 (SLC26) is a family of functionally diverse anion transporters found in all kingdoms of life. Anions transported by SLC26 proteins include chloride, bicarbonate, and sulfate, but also small organic dicarboxylates such as fumarate and oxalate. The human genome encodes ten functional homologs, several of which are causally associated with severe human diseases, highlighting their physiological importance. Here, we review novel insights into the structure and function of SLC26 proteins and summarize the physiological relevance of human members.
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Affiliation(s)
- Eric R Geertsma
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.
| | - Dominik Oliver
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, Marburg, Germany.
- Center for Mind, Brain and Behavior (CMBB), Universities of Marburg and Giessen, Marburg, Giessen, Germany.
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4
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Takahashi S, Homma K. The molecular principles underlying diverse functions of the SLC26 family of proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.10.570988. [PMID: 38106153 PMCID: PMC10723444 DOI: 10.1101/2023.12.10.570988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Mammalian SLC26 proteins are membrane-based anion transporters that belong to the large SLC26/SulP family, and many of their variants are associated with hereditary diseases. Recent structural studies revealed a strikingly similar homodimeric molecular architecture for several SLC26 members, implying a shared molecular principle. Now a new question emerges as to how these structurally similar proteins execute diverse physiological functions. In this study we sought to identify the common vs. distinct molecular mechanism among the SLC26 proteins using both naturally occurring and artificial missense changes introduced to SLC26A4, SLC26A5, and SLC26A9. We found: (i) the basic residue at the anion binding site is essential for both anion antiport of SLC26A4 and motor functions of SLC26A5, and its conversion to a nonpolar residue is crucial but not sufficient for the fast uncoupled anion transport in SLC26A9; (ii) the conserved polar residues in the N- and C-terminal cytosolic domains are likely involved in dynamic hydrogen-bonding networks and are essential for anion antiport of SLC26A4 but not for motor (SLC26A5) and uncoupled anion transport (SLC26A9) functions; (iii) the hydrophobic interaction between each protomer's last transmembrane helices, TM14, is not of functional significance in SLC26A9 but crucial for the functions of SLC26A4 and SLC26A5, likely contributing to optimally orient the axis of the relative movements of the core domain with respect to the gate domains within the cell membrane. These findings advance our understanding of the molecular mechanisms underlying the diverse physiological roles of the SLC26 family of proteins.
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5
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Lin X, Haller PR, Bavi N, Faruk N, Perozo E, Sosnick TR. Folding of prestin's anion-binding site and the mechanism of outer hair cell electromotility. eLife 2023; 12:RP89635. [PMID: 38054956 PMCID: PMC10699807 DOI: 10.7554/elife.89635] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2023] Open
Abstract
Prestin responds to transmembrane voltage fluctuations by changing its cross-sectional area, a process underlying the electromotility of outer hair cells and cochlear amplification. Prestin belongs to the SLC26 family of anion transporters yet is the only member capable of displaying electromotility. Prestin's voltage-dependent conformational changes are driven by the putative displacement of residue R399 and a set of sparse charged residues within the transmembrane domain, following the binding of a Cl- anion at a conserved binding site formed by the amino termini of the TM3 and TM10 helices. However, a major conundrum arises as to how an anion that binds in proximity to a positive charge (R399), can promote the voltage sensitivity of prestin. Using hydrogen-deuterium exchange mass spectrometry, we find that prestin displays an unstable anion-binding site, where folding of the amino termini of TM3 and TM10 is coupled to Cl- binding. This event shortens the TM3-TM10 electrostatic gap, thereby connecting the two helices, resulting in reduced cross-sectional area. These folding events upon anion binding are absent in SLC26A9, a non-electromotile transporter closely related to prestin. Dynamics of prestin embedded in a lipid bilayer closely match that in detergent micelle, except for a destabilized lipid-facing helix TM6 that is critical to prestin's mechanical expansion. We observe helix fraying at prestin's anion-binding site but cooperative unfolding of multiple lipid-facing helices, features that may promote prestin's fast electromechanical rearrangements. These results highlight a novel role of the folding equilibrium of the anion-binding site, and help define prestin's unique voltage-sensing mechanism and electromotility.
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Affiliation(s)
- Xiaoxuan Lin
- Center for Mechanical Excitability, The University of ChicagoChicagoUnited States
- Department of Biochemistry and Molecular Biology, The University of ChicagoChicagoUnited States
| | - Patrick R Haller
- Center for Mechanical Excitability, The University of ChicagoChicagoUnited States
- Department of Biochemistry and Molecular Biology, The University of ChicagoChicagoUnited States
| | - Navid Bavi
- Center for Mechanical Excitability, The University of ChicagoChicagoUnited States
- Department of Biochemistry and Molecular Biology, The University of ChicagoChicagoUnited States
| | - Nabil Faruk
- Department of Biochemistry and Molecular Biology, The University of ChicagoChicagoUnited States
| | - Eduardo Perozo
- Center for Mechanical Excitability, The University of ChicagoChicagoUnited States
- Department of Biochemistry and Molecular Biology, The University of ChicagoChicagoUnited States
- Institute for Neuroscience, The University of ChicagoChicagoUnited States
- Institute for Biophysical Dynamics, The University of ChicagoChicagoUnited States
| | - Tobin R Sosnick
- Center for Mechanical Excitability, The University of ChicagoChicagoUnited States
- Department of Biochemistry and Molecular Biology, The University of ChicagoChicagoUnited States
- Institute for Biophysical Dynamics, The University of ChicagoChicagoUnited States
- Prizker School for Molecular Engineering, The University of ChicagoChicagoUnited States
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6
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Kuwabara MF, Haddad BG, Lenz-Schwab D, Hartmann J, Longo P, Huckschlag BM, Fuß A, Questino A, Berger TK, Machtens JP, Oliver D. Elevator-like movements of prestin mediate outer hair cell electromotility. Nat Commun 2023; 14:7145. [PMID: 37932294 PMCID: PMC10628124 DOI: 10.1038/s41467-023-42489-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Accepted: 10/12/2023] [Indexed: 11/08/2023] Open
Abstract
The outstanding acuity of the mammalian ear relies on cochlear amplification, an active mechanism based on the electromotility (eM) of outer hair cells. eM is a piezoelectric mechanism generated by little-understood, voltage-induced conformational changes of the anion transporter homolog prestin (SLC26A5). We used a combination of molecular dynamics (MD) simulations and biophysical approaches to identify the structural dynamics of prestin that mediate eM. MD simulations showed that prestin samples a vast conformational landscape with expanded (ES) and compact (CS) states beyond previously reported prestin structures. Transition from CS to ES is dominated by the translational-rotational movement of prestin's transport domain, akin to elevator-type substrate translocation by related solute carriers. Reversible transition between CS and ES states was supported experimentally by cysteine accessibility scanning, cysteine cross-linking between transport and scaffold domains, and voltage-clamp fluorometry (VCF). Our data demonstrate that prestin's piezoelectric dynamics recapitulate essential steps of a structurally conserved ion transport cycle.
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Affiliation(s)
- Makoto F Kuwabara
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, 35037, Marburg, Germany
| | - Bassam G Haddad
- Institute of Biological Information Processing (IBI-1), Molekular- und Zellphysiologie, and JARA-HPC, Forschungszentrum Jülich, Jülich, Germany
| | - Dominik Lenz-Schwab
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, 35037, Marburg, Germany
| | - Julia Hartmann
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, 35037, Marburg, Germany
| | - Piersilvio Longo
- Institute of Biological Information Processing (IBI-1), Molekular- und Zellphysiologie, and JARA-HPC, Forschungszentrum Jülich, Jülich, Germany
| | - Britt-Marie Huckschlag
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, 35037, Marburg, Germany
| | - Anneke Fuß
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, 35037, Marburg, Germany
| | - Annalisa Questino
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, 35037, Marburg, Germany
| | - Thomas K Berger
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, 35037, Marburg, Germany
| | - Jan-Philipp Machtens
- Institute of Biological Information Processing (IBI-1), Molekular- und Zellphysiologie, and JARA-HPC, Forschungszentrum Jülich, Jülich, Germany.
- Institute of Clinical Pharmacology, RWTH Aachen University, Aachen, Germany.
| | - Dominik Oliver
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University Marburg, 35037, Marburg, Germany.
- DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodeling, GRK 2213, Philipps University, Marburg, Germany.
- Center for Mind, Brain and Behavior (CMBB), Universities of Marburg and Giessen, Marburg, Germany.
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7
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Lin X, Haller P, Bavi N, Faruk N, Perozo E, Sosnick TR. Folding of Prestin's Anion-Binding Site and the Mechanism of Outer Hair Cell Electromotility. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.27.530320. [PMID: 36909622 PMCID: PMC10002659 DOI: 10.1101/2023.02.27.530320] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
Abstract
Prestin responds to transmembrane voltage fluctuations by changing its cross-sectional area, a process underlying the electromotility of outer hair cells and cochlear amplification. Prestin belongs to the SLC26 family of anion transporters yet is the only member capable of displaying electromotility. Prestin's voltage-dependent conformational changes are driven by the putative displacement of residue R399 and a set of sparse charged residues within the transmembrane domain, following the binding of a Cl - anion at a conserved binding site formed by amino termini of the TM3 and TM10 helices. However, a major conundrum arises as to how an anion that binds in proximity to a positive charge (R399), can promote the voltage sensitivity of prestin. Using hydrogen-deuterium exchange mass spectrometry, we find that prestin displays an unstable anion-binding site, where folding of the amino termini of TM3 and TM10 is coupled to Cl - binding. This event shortens the TM3-TM10 electrostatic gap, thereby connecting the two helices, resulting in reduced cross-sectional area. These folding events upon anion-binding are absent in SLC26A9, a non-electromotile transporter closely related to prestin. Dynamics of prestin embedded in a lipid bilayer closely match that in detergent micelle, except for a destabilized lipid-facing helix TM6 that is critical to prestin's mechanical expansion. We observe helix fraying at prestin's anion-binding site but cooperative unfolding of multiple lipid-facing helices, features that may promote prestin's fast electromechanical rearrangements. These results highlight a novel role of the folding equilibrium of the anion-binding site, and helps define prestin's unique voltage-sensing mechanism and electromotility.
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8
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Dehghani-Ghahnaviyeh S, Zhao Z, Tajkhorshid E. Lipid-mediated prestin organization in outer hair cell membranes and its implications in sound amplification. Nat Commun 2022; 13:6877. [PMID: 36371434 PMCID: PMC9653410 DOI: 10.1038/s41467-022-34596-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 10/28/2022] [Indexed: 11/13/2022] Open
Abstract
Prestin is a high-density motor protein in the outer hair cells (OHCs), whose conformational response to acoustic signals alters the shape of the cell, thereby playing a major role in sound amplification by the cochlea. Despite recent structures, prestin's intimate interactions with the membrane, which are central to its function remained unresolved. Here, employing a large set (collectively, more than 0.5 ms) of coarse-grained molecular dynamics simulations, we demonstrate the impact of prestin's lipid-protein interactions on its organization at densities relevant to the OHCs and its effectiveness in reshaping OHCs. Prestin causes anisotropic membrane deformation, which mediates a preferential membrane organization of prestin where deformation patterns by neighboring copies are aligned constructively. The resulting reduced membrane rigidity is hypothesized to maximize the impact of prestin on OHC reshaping. These results demonstrate a clear case of protein-protein cooperative communication in membrane, purely mediated by interactions with lipids.
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Affiliation(s)
- Sepehr Dehghani-Ghahnaviyeh
- grid.35403.310000 0004 1936 9991Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL USA
| | - Zhiyu Zhao
- grid.35403.310000 0004 1936 9991Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL USA
| | - Emad Tajkhorshid
- grid.35403.310000 0004 1936 9991Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL USA
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9
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Futamata H, Fukuda M, Umeda R, Yamashita K, Tomita A, Takahashi S, Shikakura T, Hayashi S, Kusakizako T, Nishizawa T, Homma K, Nureki O. Cryo-EM structures of thermostabilized prestin provide mechanistic insights underlying outer hair cell electromotility. Nat Commun 2022; 13:6208. [PMID: 36266333 PMCID: PMC9584906 DOI: 10.1038/s41467-022-34017-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 10/11/2022] [Indexed: 01/11/2023] Open
Abstract
Outer hair cell elecromotility, driven by prestin, is essential for mammalian cochlear amplification. Here, we report the cryo-EM structures of thermostabilized prestin (PresTS), complexed with chloride, sulfate, or salicylate at 3.52-3.63 Å resolutions. The central positively-charged cavity allows flexible binding of various anion species, which likely accounts for the known distinct modulations of nonlinear capacitance (NLC) by different anions. Comparisons of these PresTS structures with recent prestin structures suggest rigid-body movement between the core and gate domains, and provide mechanistic insights into prestin inhibition by salicylate. Mutations at the dimeric interface severely diminished NLC, suggesting that stabilization of the gate domain facilitates core domain movement, thereby contributing to the expression of NLC. These findings advance our understanding of the molecular mechanism underlying mammalian cochlear amplification.
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Affiliation(s)
- Haon Futamata
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Masahiro Fukuda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo; Meguro-ku, Tokyo, 153-8503, Japan
| | - Rie Umeda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Keitaro Yamashita
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Atsuhiro Tomita
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Satoe Takahashi
- Department of Otolaryngology-Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Takafumi Shikakura
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa, Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Shigehiko Hayashi
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa, Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Tsukasa Kusakizako
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Tomohiro Nishizawa
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan.
- Graduate School of Medical Life Science, Yokohama City University, Yokohama, Japan.
| | - Kazuaki Homma
- Department of Otolaryngology-Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA.
- The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University, Evanston, IL, 60608, USA.
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan.
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10
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Butan C, Song Q, Bai JP, Tan WJT, Navaratnam D, Santos-Sacchi J. Single particle cryo-EM structure of the outer hair cell motor protein prestin. Nat Commun 2022; 13:290. [PMID: 35022426 PMCID: PMC8755724 DOI: 10.1038/s41467-021-27915-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 12/16/2021] [Indexed: 12/18/2022] Open
Abstract
The mammalian outer hair cell (OHC) protein prestin (Slc26a5) differs from other Slc26 family members due to its unique piezoelectric-like property that drives OHC electromotility, the putative mechanism for cochlear amplification. Here, we use cryo-electron microscopy to determine prestin’s structure at 3.6 Å resolution. Prestin is structurally similar to the anion transporter Slc26a9. It is captured in an inward-open state which may reflect prestin’s contracted state. Two well-separated transmembrane (TM) domains and two cytoplasmic sulfate transporter and anti-sigma factor antagonist (STAS) domains form a swapped dimer. The transmembrane domains consist of 14 transmembrane segments organized in two 7+7 inverted repeats, an architecture first observed in the bacterial symporter UraA. Mutation of prestin’s chloride binding site removes salicylate competition with anions while retaining the prestin characteristic displacement currents (Nonlinear Capacitance), undermining the extrinsic voltage sensor hypothesis for prestin function. Prestin, expressed in outer hair cell (OHC), belongs to the Slc26 transporter family and functions as a voltage-driven motor that drives OHC electromotility. Here, the authors report cryo-EM structure and characterization of gerbil prestin, with insights into its mechanism of action.
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Affiliation(s)
- Carmen Butan
- Department of Surgery (Otolaryngology), Yale University School of Medicine, New Haven, CT, USA
| | - Qiang Song
- Department of Surgery (Otolaryngology), Yale University School of Medicine, New Haven, CT, USA
| | - Jun-Ping Bai
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
| | - Winston J T Tan
- Department of Surgery (Otolaryngology), Yale University School of Medicine, New Haven, CT, USA
| | - Dhasakumar Navaratnam
- Department of Surgery (Otolaryngology), Yale University School of Medicine, New Haven, CT, USA. .,Department of Neurology, Yale University School of Medicine, New Haven, CT, USA. .,Neuroscience, Yale University School of Medicine, New Haven, CT, USA.
| | - Joseph Santos-Sacchi
- Department of Surgery (Otolaryngology), Yale University School of Medicine, New Haven, CT, USA. .,Neuroscience, Yale University School of Medicine, New Haven, CT, USA. .,Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT, USA.
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11
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Progress in understanding the structural mechanism underlying prestin's electromotile activity. Hear Res 2021; 423:108423. [PMID: 34987017 DOI: 10.1016/j.heares.2021.108423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 11/17/2021] [Accepted: 12/22/2021] [Indexed: 11/21/2022]
Abstract
Prestin (SLC26A5), a member of the SLC26 transporter family, is the molecular actuator that drives OHC electromotility (eM). A wealth of biophysical data indicates that eM is mediated by an area motor mechanism, in which prestin molecules act as elementary actuators by changing their area in the membrane in response to changes in membrane potential. The area changes of a large and densely packed population of prestin molecules sum up, resulting in macroscopic cellular movement. At the single protein level, this model implies major voltage-driven conformational rearrangements. However, the nature of these structural dynamics remained unknown. A main obstacle in elucidating the eM mechanism has been the lack of structural information about SLC26 transporters. The recent emergence of several high-resolution cryo-EM structures of prestin as well as other SLC26 transporter family members now provides a reliable picture of prestin's molecular architecture. Thus, SLC26 transporters including prestin generally are dimers, and each protomer is folded according to a 7+7 transmembrane domain inverted repeat (7TMIR) architecture. Here, we review these structural findings and discuss insights into a potential molecular mechanism. Most important, distinct conformations were observed when purifying and imaging prestin bound to either its physiological ligand, chloride, or to competitively inhibitory anions, sulfate or salicylate. Despite differences in detail, these structural snapshots indicate that the conformational landscape of prestin includes rearrangements between the two major domains of prestin's transmembrane region (TMD), core and scaffold ('gate') domains. Notably, distinct conformations differ in the area the TMD occupies in the membrane and in their impact on the immediate lipid environment. Both effects can contribute to generate membrane deformation and thus may underly electromotility. Further functional studies will be necessary to determine whether these or similar structural rearrangements are driven by membrane potential to mediate piezoelectric activity. This article is part of the Special Issue Outer hair cell Edited by Joseph Santos-Sacchi and Kumar Navaratnam.
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12
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SLC26A9 is selected for endoplasmic reticulum associated degradation (ERAD) via Hsp70-dependent targeting of the soluble STAS domain. Biochem J 2021; 478:4203-4220. [PMID: 34821356 PMCID: PMC8826537 DOI: 10.1042/bcj20210644] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 11/23/2021] [Accepted: 11/24/2021] [Indexed: 12/24/2022]
Abstract
SLC26A9, a member of the solute carrier protein family, transports chloride ions across various epithelia. SLC26A9 also associates with other ion channels and transporters linked to human health, and in some cases these heterotypic interactions are essential to support the biogenesis of both proteins. Therefore, understanding how this complex membrane protein is initially folded might provide new therapeutic strategies to overcome deficits in the function of SLC26A9 partners, one of which is associated with Cystic Fibrosis. To this end, we developed a novel yeast expression system for SLC26A9. This facile system has been used extensively with other ion channels and transporters to screen for factors that oversee protein folding checkpoints. As commonly observed for other channels and transporters, we first noted that a substantial fraction of SLC26A9 is targeted for endoplasmic reticulum associated degradation (ERAD), which destroys folding-compromised proteins in the early secretory pathway. We next discovered that ERAD selection requires the Hsp70 chaperone, which can play a vital role in ERAD substrate selection. We then created SLC26A9 mutants and found that the transmembrane-rich domain of SLC26A9 was quite stable, whereas the soluble cytosolic STAS domain was responsible for Hsp70-dependent ERAD. To support data obtained in the yeast model, we were able to recapitulate Hsp70-facilitated ERAD of the STAS domain in human tissue culture cells. These results indicate that a critical barrier to nascent membrane protein folding can reside within a specific soluble domain, one that is monitored by components associated with the ERAD machinery.
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13
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Bavi N, Clark MD, Contreras GF, Shen R, Reddy BG, Milewski W, Perozo E. The conformational cycle of prestin underlies outer-hair cell electromotility. Nature 2021; 600:553-558. [PMID: 34695838 DOI: 10.1038/s41586-021-04152-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 10/15/2021] [Indexed: 11/09/2022]
Abstract
The voltage-dependent motor protein prestin (also known as SLC26A5) is responsible for the electromotive behaviour of outer-hair cells and underlies the cochlear amplifier1. Knockout or impairment of prestin causes severe hearing loss2-5. Despite the key role of prestin in hearing, the mechanism by which mammalian prestin senses voltage and transduces it into cellular-scale movements (electromotility) is poorly understood. Here we determined the structure of dolphin prestin in six distinct states using single-particle cryo-electron microscopy. Our structural and functional data suggest that prestin adopts a unique and complex set of states, tunable by the identity of bound anions (Cl- or SO42-). Salicylate, a drug that can cause reversible hearing loss, competes for the anion-binding site of prestin, and inhibits its function by immobilizing prestin in a new conformation. Our data suggest that the bound anion together with its coordinating charged residues and helical dipole act as a dynamic voltage sensor. An analysis of all of the anion-dependent conformations reveals how structural rearrangements in the voltage sensor are coupled to conformational transitions at the protein-membrane interface, suggesting a previously undescribed mechanism of area expansion. Visualization of the electromotility cycle of prestin distinguishes the protein from the closely related SLC26 anion transporters, highlighting the basis for evolutionary specialization of the mammalian cochlear amplifier at a high resolution.
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Affiliation(s)
- Navid Bavi
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Michael David Clark
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Gustavo F Contreras
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Rong Shen
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Bharat G Reddy
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Rectify Pharmaceuticals, Cambridge, MA, USA
| | - Wieslawa Milewski
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Eduardo Perozo
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA.
- Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL, USA.
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14
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Ge J, Elferich J, Dehghani-Ghahnaviyeh S, Zhao Z, Meadows M, von Gersdorff H, Tajkhorshid E, Gouaux E. Molecular mechanism of prestin electromotive signal amplification. Cell 2021; 184:4669-4679.e13. [PMID: 34390643 PMCID: PMC8674105 DOI: 10.1016/j.cell.2021.07.034] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/26/2021] [Accepted: 07/23/2021] [Indexed: 11/21/2022]
Abstract
Hearing involves two fundamental processes: mechano-electrical transduction and signal amplification. Despite decades of studies, the molecular bases for both remain elusive. Here, we show how prestin, the electromotive molecule of outer hair cells (OHCs) that senses both voltage and membrane tension, mediates signal amplification by coupling conformational changes to alterations in membrane surface area. Cryoelectron microscopy (cryo-EM) structures of human prestin bound with chloride or salicylate at a common "anion site" adopt contracted or expanded states, respectively. Prestin is ensconced within a perimeter of well-ordered lipids, through which it induces dramatic deformation in the membrane and couples protein conformational changes to the bulk membrane. Together with computational studies, we illustrate how the anion site is allosterically coupled to changes in the transmembrane domain cross-sectional area and the surrounding membrane. These studies provide insight into OHC electromotility by providing a structure-based mechanism of the membrane motor prestin.
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Affiliation(s)
- Jingpeng Ge
- Vollum Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Johannes Elferich
- Vollum Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Sepehr Dehghani-Ghahnaviyeh
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Zhiyu Zhao
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Marc Meadows
- Vollum Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Henrique von Gersdorff
- Vollum Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
| | - Emad Tajkhorshid
- Theoretical and Computational Biophysics Group, NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, Department of Biochemistry, and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Eric Gouaux
- Vollum Institute, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA; Howard Hughes Medical Institute, Portland, OR 97239, USA.
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15
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Farrell B, Skidmore BL, Rajasekharan V, Brownell WE. A novel theoretical framework reveals more than one voltage-sensing pathway in the lateral membrane of outer hair cells. J Gen Physiol 2021; 152:151746. [PMID: 32384538 PMCID: PMC7335013 DOI: 10.1085/jgp.201912447] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Accepted: 03/18/2020] [Indexed: 11/20/2022] Open
Abstract
Outer hair cell (OHC) electromotility amplifies acoustic vibrations throughout the frequency range of hearing. Electromotility requires that the lateral membrane protein prestin undergo a conformational change upon changes in the membrane potential to produce an associated displacement charge. The magnitude of the charge displaced and the mid-reaction potential (when one half of the charge is displaced) reflects whether the cells will produce sufficient gain at the resting membrane potential to boost sound in vivo. Voltage clamp measurements performed under near-identical conditions ex vivo show the charge density and mid-reaction potential are not always the same, confounding interpretation of the results. We compare the displacement charge measurements in OHCs from rodents with a theory shown to exhibit good agreement with in silico simulations of voltage-sensing reactions in membranes. This model equates the charge density to the potential difference between two pseudo-equilibrium states of the sensors when they are in a stable conformation and not contributing to the displacement current. The model predicts this potential difference to be one half of its value midway into the reaction, when one equilibrium conformation transforms to the other pseudo-state. In agreement with the model, we find the measured mid-reaction potential to increase as the charge density decreases to exhibit a negative slope of ∼1/2. This relationship suggests that the prestin sensors exhibit more than one stable hyperpolarized state and that voltage sensing occurs by more than one pathway. We determine the electric parameters for prestin sensors and use the analytical expressions of the theory to estimate the energy barriers for the two voltage-dependent pathways. This analysis explains the experimental results, supports the theoretical approach, and suggests that voltage sensing occurs by more than one pathway to enable amplification throughout the frequency range of hearing.
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Affiliation(s)
- Brenda Farrell
- Bobby R. Alford Department of Otolaryngology and Head & Neck Surgery, Baylor College of Medicine, Houston, TX
| | - Benjamin L Skidmore
- Bobby R. Alford Department of Otolaryngology and Head & Neck Surgery, Baylor College of Medicine, Houston, TX
| | - Vivek Rajasekharan
- Bobby R. Alford Department of Otolaryngology and Head & Neck Surgery, Baylor College of Medicine, Houston, TX
| | - William E Brownell
- Bobby R. Alford Department of Otolaryngology and Head & Neck Surgery, Baylor College of Medicine, Houston, TX
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16
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Comparative Molecular Dynamics Investigation of the Electromotile Hearing Protein Prestin. Int J Mol Sci 2021; 22:ijms22158318. [PMID: 34361083 PMCID: PMC8347359 DOI: 10.3390/ijms22158318] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 07/23/2021] [Accepted: 07/26/2021] [Indexed: 01/05/2023] Open
Abstract
The mammalian protein prestin is expressed in the lateral membrane wall of the cochlear hair outer cells and is responsible for the electromotile response of the basolateral membrane, following hyperpolarisation or depolarisation of the cells. Its impairment marks the onset of severe diseases, like non-syndromic deafness. Several studies have pointed out possible key roles of residues located in the Transmembrane Domain (TMD) that differentiate mammalian prestins as incomplete transporters from the other proteins belonging to the same solute-carrier (SLC) superfamily, which are classified as complete transporters. Here, we exploit the homology of a prototypical incomplete transporter (rat prestin, rPres) and a complete transporter (zebrafish prestin, zPres) with target structures in the outward open and inward open conformations. The resulting models are then embedded in a model membrane and investigated via a rigorous molecular dynamics simulation protocol. The resulting trajectories are analyzed to obtain quantitative descriptors of the equilibration phase and to assess a structural comparison between proteins in different states, and between different proteins in the same state. Our study clearly identifies a network of key residues at the interface between the gate and the core domains of prestin that might be responsible for the conformational change observed in complete transporters and hindered in incomplete transporters. In addition, we study the pathway of Cl− ions in the presence of an applied electric field towards their putative binding site in the gate domain. Based on our simulations, we propose a tilt and shift mechanism of the helices surrounding the ion binding cavity as the working principle of the reported conformational changes in complete transporters.
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17
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Zhang XD, Thai PN, Ren L, Perez Flores MC, Ledford HA, Park S, Lee JH, Sihn CR, Chang CW, Chen WC, Timofeyev V, Zuo J, Chan JW, Yamoah EN, Chiamvimonvat N. Prestin amplifies cardiac motor functions. Cell Rep 2021; 35:109097. [PMID: 33951436 PMCID: PMC8720583 DOI: 10.1016/j.celrep.2021.109097] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 12/27/2020] [Accepted: 04/16/2021] [Indexed: 02/06/2023] Open
Abstract
Cardiac cells generate and amplify force in the context of cardiac load, yet the membranous sheath enclosing the muscle fibers-the sarcolemma-does not experience displacement. That the sarcolemma sustains beat-to-beat pressure changes without experiencing significant distortion is a muscle-contraction paradox. Here, we report that an elastic element-the motor protein prestin (Slc26a5)-serves to amplify actin-myosin force generation in mouse and human cardiac myocytes, accounting partly for the nonlinear capacitance of cardiomyocytes. The functional significance of prestin is underpinned by significant alterations of cardiac contractility in Prestin-knockout mice. Prestin was previously considered exclusive to the inner ear's outer hair cells; however, our results show that prestin serves a broader cellular motor function.
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Affiliation(s)
- Xiao-Dong Zhang
- Division of Cardiovascular Medicine, University of California, Davis, Davis, CA 95616, USA; Department of Veterans Affairs, VA Northern California Health Care System, Mather, CA 95655, USA.
| | - Phung N Thai
- Division of Cardiovascular Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Lu Ren
- Division of Cardiovascular Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Maria Cristina Perez Flores
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV 89557, USA
| | - Hannah A Ledford
- Division of Cardiovascular Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Seojin Park
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV 89557, USA
| | - Jeong Han Lee
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV 89557, USA
| | - Choong-Ryoul Sihn
- Division of Cardiovascular Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Che-Wei Chang
- Department of Pathology and Laboratory Medicine, University of California, Davis, Davis, CA 95817, USA
| | - Wei Chun Chen
- Division of Cardiovascular Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Valeriy Timofeyev
- Division of Cardiovascular Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Jian Zuo
- Department of Biomedical Sciences, Creighton University, Omaha, NE 68178, USA
| | - James W Chan
- Department of Pathology and Laboratory Medicine, University of California, Davis, Davis, CA 95817, USA
| | - Ebenezer N Yamoah
- Department of Physiology and Cell Biology, University of Nevada, Reno School of Medicine, Reno, NV 89557, USA.
| | - Nipavan Chiamvimonvat
- Division of Cardiovascular Medicine, University of California, Davis, Davis, CA 95616, USA; Department of Veterans Affairs, VA Northern California Health Care System, Mather, CA 95655, USA.
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18
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Effertz T, Moser T, Oliver D. Recent advances in cochlear hair cell nanophysiology: subcellular compartmentalization of electrical signaling in compact sensory cells. Fac Rev 2021; 9:24. [PMID: 33659956 PMCID: PMC7886071 DOI: 10.12703/r/9-24] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In recent years, genetics, physiology, and structural biology have advanced into the molecular details of the sensory physiology of auditory hair cells. Inner hair cells (IHCs) and outer hair cells (OHCs) mediate two key functions: active amplification and non-linear compression of cochlear vibrations by OHCs and sound encoding by IHCs at their afferent synapses with the spiral ganglion neurons. OHCs and IHCs share some molecular physiology, e.g. mechanotransduction at the apical hair bundles, ribbon-type presynaptic active zones, and ionic conductances in the basolateral membrane. Unique features enabling their specific function include prestin-based electromotility of OHCs and indefatigable transmitter release at the highest known rates by ribbon-type IHC active zones. Despite their compact morphology, the molecular machineries that either generate electrical signals or are driven by these signals are essentially all segregated into local subcellular structures. This review provides a brief account on recent insights into the molecular physiology of cochlear hair cells with a specific focus on organization into membrane domains.
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Affiliation(s)
- Thomas Effertz
- InnerEarLab, Department of Otorhinolaryngology, University Medical Center Göttingen, 37099 Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37099 Göttingen, Germany
- Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, 37075 Göttingen, Germany
- Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, 37075 Göttingen, Germany
| | - Dominik Oliver
- Institute for Physiology and Pathophysiology, Philipps University, Deutschhausstraße 2, 35037 Marburg, Germany
- Center for Mind, Brain and Behavior (CMBB), Universities of Marburg and Giessen, Germany
- DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodelling, GRK 2213, Philipps University, Marburg, Germany
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19
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Costanzi E, Coletti A, Zambelli B, Macchiarulo A, Bellanda M, Battistutta R. Calmodulin binds to the STAS domain of SLC26A5 prestin with a calcium-dependent, one-lobe, binding mode. J Struct Biol 2021; 213:107714. [PMID: 33667636 DOI: 10.1016/j.jsb.2021.107714] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 01/14/2021] [Accepted: 02/25/2021] [Indexed: 10/22/2022]
Abstract
SLC26A5 transporter prestin is fundamental for the higher hearing sensitivity and frequency selectivity of mammals. Prestin is a voltage-dependent transporter found in the cochlear outer hair cells responsible for their electromotility. Intracellular chloride binding is considered essential for voltage sensitivity and electromotility. Prestin is composed by a transmembrane domain and by a cytosolic domain called STAS. There is evidence of a calcium/calmodulin regulation of prestin mediated by the STAS domain. Using different biophysical techniques, namely SEC, CD, ITC, MST, NMR and SAXS, here we demonstrate and characterize the direct interaction between calmodulin and prestin STAS. We show that the interaction is calcium-dependent and that involves residues at the N-terminal end of the "variable loop". This is an intrinsically disordered insertion typical of the STAS domains of the SLC26 family of transporters whose function is still unclear. We derive a low-resolution model of the STAS/CaM complex, where only one lobe of calmodulin is engaged in the interaction, and build a model for the entire dimeric prestin in complex with CaM, which can use the unoccupied lobe to interact with other regions of prestin or with other regulatory proteins. We show that also a non-mammalian STAS can interact with calmodulin via the variable loop. These data start to shed light on the regulatory role of the STAS variable loop of prestin.
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Affiliation(s)
- Elisa Costanzi
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy
| | - Alice Coletti
- Department of Pharmaceutical Sciences, University of Perugia, via del Liceo 1, 06123 Perugia, Italy; Department of Pharmacy, University of Chieti-Pescara, via dei Vestini 31, 66100 Chieti, Italy
| | - Barbara Zambelli
- Department of Pharmacy and Biotechnology, University of Bologna, viale Fanin 40, 40127 Bologna, Italy
| | - Antonio Macchiarulo
- Department of Pharmaceutical Sciences, University of Perugia, via del Liceo 1, 06123 Perugia, Italy
| | - Massimo Bellanda
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy.
| | - Roberto Battistutta
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy.
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20
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Ashmore J. Tonotopy of cochlear hair cell biophysics (excl. mechanotransduction). CURRENT OPINION IN PHYSIOLOGY 2020. [DOI: 10.1016/j.cophys.2020.06.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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21
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Kim D, Han SA, Kim JH, Lee JH, Kim SW, Lee SW. Biomolecular Piezoelectric Materials: From Amino Acids to Living Tissues. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1906989. [PMID: 32103565 DOI: 10.1002/adma.201906989] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 12/16/2019] [Indexed: 06/10/2023]
Abstract
Biomolecular piezoelectric materials are considered a strong candidate material for biomedical applications due to their robust piezoelectricity, biocompatibility, and low dielectric property. The electric field has been found to affect tissue development and regeneration, and the piezoelectric properties of biological materials in the human body are known to provide electric fields by pressure. Therefore, great attention has been paid to the understanding of piezoelectricity in biological tissues and its building blocks. The aim herein is to describe the principle of piezoelectricity in biological materials from the very basic building blocks (i.e., amino acids, peptides, proteins, etc.) to highly organized tissues (i.e., bones, skin, etc.). Research progress on the piezoelectricity within various biological materials is summarized, including amino acids, peptides, proteins, and tissues. The mechanisms and origin of piezoelectricity within various biological materials are also covered.
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Affiliation(s)
- Daeyeong Kim
- Department of Energy Science and Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 42988, Republic of Korea
| | - Sang A Han
- School of Advanced Materials Science and Engineering, Sungkyunkwan University (SKKU), Suwon, 440-746, Republic of Korea
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Squires Way, North Wollongong, NSW, 2500, Australia
| | - Jung Ho Kim
- Institute for Superconducting and Electronic Materials, Australian Institute for Innovative Materials, University of Wollongong, Squires Way, North Wollongong, NSW, 2500, Australia
| | - Ju-Hyuck Lee
- Department of Energy Science and Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu, 42988, Republic of Korea
| | - Sang-Woo Kim
- School of Advanced Materials Science and Engineering, Sungkyunkwan University (SKKU), Suwon, 440-746, Republic of Korea
| | - Seung-Wuk Lee
- Department of Bioengineering, University of California, Berkeley, CA, 94720, USA
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
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22
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Diverse Mechanisms of Sound Frequency Discrimination in the Vertebrate Cochlea. Trends Neurosci 2020; 43:88-102. [PMID: 31954526 DOI: 10.1016/j.tins.2019.12.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 12/05/2019] [Accepted: 12/10/2019] [Indexed: 01/17/2023]
Abstract
Discrimination of different sound frequencies is pivotal to recognizing and localizing friend and foe. Here, I review the various hair cell-tuning mechanisms used among vertebrates. Electrical resonance, filtering of the receptor potential by voltage-dependent ion channels, is ubiquitous in all non-mammals, but has an upper limit of ~1 kHz. The frequency range is extended by mechanical resonance of the hair bundles in frogs and lizards, but may need active hair-bundle motion to achieve sharp tuning up to 5 kHz. Tuning in mammals uses somatic motility of outer hair cells, underpinned by the membrane protein prestin, to expand the frequency range. The bird cochlea may also use prestin at high frequencies, but hair cells <1 kHz show electrical resonance.
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23
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Wasano K, Takahashi S, Rosenberg SK, Kojima T, Mutai H, Matsunaga T, Ogawa K, Homma K. Systematic quantification of the anion transport function of pendrin (SLC26A4) and its disease-associated variants. Hum Mutat 2020; 41:316-331. [PMID: 31599023 PMCID: PMC6930342 DOI: 10.1002/humu.23930] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 10/01/2019] [Accepted: 10/03/2019] [Indexed: 01/14/2023]
Abstract
Thanks to the advent of rapid DNA sequencing technology and its prevalence, many disease-associated genetic variants are rapidly identified in many genes from patient samples. However, the subsequent effort to experimentally validate and define their pathological roles is extremely slow. Consequently, the pathogenicity of most disease-associated genetic variants is solely speculated in silico, which is no longer deemed compelling. We developed an experimental approach to efficiently quantify the pathogenic effects of disease-associated genetic variants with a focus on SLC26A4, which is essential for normal inner ear function. Alterations of this gene are associated with both syndromic and nonsyndromic hereditary hearing loss with various degrees of severity. We established HEK293T-based stable cell lines that express pendrin missense variants in a doxycycline-dependent manner, and systematically determined their anion transport activities with high accuracy in a 96-well plate format using a high throughput plate reader. Our doxycycline dosage-dependent transport assay objectively distinguishes missense variants that indeed impair the function of pendrin from those that do not (functional variants). We also found that some of these putative missense variants disrupt normal messenger RNA splicing. Our comprehensive experimental approach helps determine the pathogenicity of each pendrin variant, which should guide future efforts to benefit patients.
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Affiliation(s)
- Koichiro Wasano
- Department of Otolaryngology – Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Laboratory of Auditory Disorders, Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo 152-8902, Japan
| | - Satoe Takahashi
- Department of Otolaryngology – Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Samuel K. Rosenberg
- Department of Otolaryngology – Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Takashi Kojima
- Department of Otolaryngology – Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Hideki Mutai
- Laboratory of Auditory Disorders, Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo 152-8902, Japan
| | - Tatsuo Matsunaga
- Laboratory of Auditory Disorders, Division of Hearing and Balance Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, 2-5-1 Higashigaoka, Meguro, Tokyo 152-8902, Japan
| | - Kaoru Ogawa
- Department of Otolaryngology, Head and Neck Surgery, Keio University School of Medicine, Tokyo 160-8582, Japan
| | - Kazuaki Homma
- Department of Otolaryngology – Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University, Evanston, IL 60608, USA
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24
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Wang C, Sun B, Zhang X, Huang X, Zhang M, Guo H, Chen X, Huang F, Chen T, Mi H, Yu F, Liu LN, Zhang P. Structural mechanism of the active bicarbonate transporter from cyanobacteria. NATURE PLANTS 2019; 5:1184-1193. [PMID: 31712753 DOI: 10.1038/s41477-019-0538-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Accepted: 09/27/2019] [Indexed: 05/11/2023]
Abstract
Bicarbonate transporters play essential roles in pH homeostasis in mammals and photosynthesis in aquatic photoautotrophs. A number of bicarbonate transporters have been characterized, among which is BicA-a low-affinity, high-flux SLC26-family bicarbonate transporter involved in cyanobacterial CO2-concentrating mechanisms (CCMs) that accumulate CO2 and improve photosynthetic carbon fixation. Here, we report the three-dimensional structure of BicA from Synechocystis sp. PCC6803. Crystal structures of the transmembrane domain (BicATM) and the cytoplasmic STAS domain (BicASTAS) of BicA were solved. BicATM was captured in an inward-facing HCO3--bound conformation and adopts a '7+7' fold monomer. HCO3- binds to a cytoplasm-facing hydrophilic pocket within the membrane. BicASTAS is assembled as a compact homodimer structure and is required for the dimerization of BicA. The dimeric structure of BicA was further analysed using cryo-electron microscopy and physiological analysis of the full-length BicA, and may represent the physiological unit of SLC26-family transporters. Comparing the BicATM structure with the outward-facing transmembrane domain structures of other bicarbonate transporters suggests an elevator transport mechanism that is applicable to the SLC26/4 family of sodium-dependent bicarbonate transporters. This study advances our knowledge of the structures and functions of cyanobacterial bicarbonate transporters, and will inform strategies for bioengineering functional BicA in heterologous organisms to increase assimilation of CO2.
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Affiliation(s)
- Chengcheng Wang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Bo Sun
- Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai, China
| | - Xue Zhang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xiaowei Huang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Minhua Zhang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Hui Guo
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Xin Chen
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Fang Huang
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Taiyu Chen
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Hualing Mi
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Fang Yu
- Shanghai Key Laboratory of Plant Molecualr Sciences, College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Lu-Ning Liu
- Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Peng Zhang
- National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
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25
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Pan B, Akyuz N, Liu XP, Asai Y, Nist-Lund C, Kurima K, Derfler BH, György B, Limapichat W, Walujkar S, Wimalasena LN, Sotomayor M, Corey DP, Holt JR. TMC1 Forms the Pore of Mechanosensory Transduction Channels in Vertebrate Inner Ear Hair Cells. Neuron 2019; 99:736-753.e6. [PMID: 30138589 DOI: 10.1016/j.neuron.2018.07.033] [Citation(s) in RCA: 209] [Impact Index Per Article: 41.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 06/10/2018] [Accepted: 07/19/2018] [Indexed: 11/28/2022]
Abstract
The proteins that form the permeation pathway of mechanosensory transduction channels in inner-ear hair cells have not been definitively identified. Genetic, anatomical, and physiological evidence support a role for transmembrane channel-like protein (TMC) 1 in hair cell sensory transduction, yet the molecular function of TMC proteins remains unclear. Here, we provide biochemical evidence suggesting TMC1 assembles as a dimer, along with structural and sequence analyses suggesting similarity to dimeric TMEM16 channels. To identify the pore region of TMC1, we used cysteine mutagenesis and expressed mutant TMC1 in hair cells of Tmc1/2-null mice. Cysteine-modification reagents rapidly and irreversibly altered permeation properties of mechanosensory transduction. We propose that TMC1 is structurally similar to TMEM16 channels and includes ten transmembrane domains with four domains, S4-S7, that line the channel pore. The data provide compelling evidence that TMC1 is a pore-forming component of sensory transduction channels in auditory and vestibular hair cells.
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Affiliation(s)
- Bifeng Pan
- Departments of Otolaryngology and Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Nurunisa Akyuz
- Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Xiao-Ping Liu
- Departments of Otolaryngology and Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Yukako Asai
- Departments of Otolaryngology and Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Carl Nist-Lund
- Departments of Otolaryngology and Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Kiyoto Kurima
- Molecular Biology and Genetics Section, National Institute on Deafness and Other Communication Disorders, NIH, Bethesda, MD 20892, USA
| | - Bruce H Derfler
- Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Bence György
- Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Walrati Limapichat
- Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Sanket Walujkar
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - Lahiru N Wimalasena
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - Marcos Sotomayor
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - David P Corey
- Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA.
| | - Jeffrey R Holt
- Departments of Otolaryngology and Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA.
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26
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Abstract
Outer hair cells (OHCs) of the mammalian cochlea behave like actuators: they feed energy into the cochlear partition and determine the overall mechanics of hearing. They do this by generating voltage-dependent axial forces. The resulting change in the cell length, observed by microscopy, has been termed "electromotility." The mechanism of force generation OHCs can be traced to a specific protein, prestin, a member of a superfamily SLC26 of transporters. This short review will identify some of the more recent findings on prestin. Although the tertiary structure of prestin has yet to be determined, results from the presence of its homologs in nonmammalian species suggest a possible conformation in mammalian OHCs, how it can act like a transport protein, and how it may have evolved.
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Affiliation(s)
- Jonathan Ashmore
- University College London Ear Institute, London WC1X8EE, United Kingdom
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27
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Pourahmadiyan A, Alipour P, Fattahi N, Kasiri M, Rezaeian F, Taghipour-Sheshdeh A, Mohammadi-Asl J, Tabatabaiefar MA, Hashemzadeh Chaleshtori M. A pathogenic variant in SLC26A4 is associated with Pendred syndrome in a consanguineous Iranian family. Int J Audiol 2019; 58:628-634. [PMID: 31187663 DOI: 10.1080/14992027.2019.1619945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Objective: Hearing loss (HL) is a common sensory deficit with high phenotypic and genotypic heterogeneity. A large Iranian family with HL was genetically assessed in this study. Design: A proband from a consanguineous multiplex HL family from Iran was examined via Targeted Next-Generation Sequencing (TNGS). Sanger sequencing allowed the segregation analysis of the variant of interest and the investigation of its presence in a cohort of 50 ethnicity-matched healthy control individuals. The gene was previously associated with HL. Therefore, to determine whether the variant was specifically associated with Pendred Syndrome (PDS) or DFNB4, biochemical analyses, PTA, thyroid scans by Tc99m, perchlorate discharge test and high-resolution CT scan of the temporal bone were carried out on the affected family members. Study sample: Ten members of a large multiplex Iranian family with HL were recruited in this study. In addition, 50 unrelated healthy controls of the same ethnic group were randomly selected to genotype the variant. Results: A homozygous missense variant (NM_000441.1: c.1211C > T/p.Thr404Ile) in exon 10 was found segregating in the family. Based on the ACMG's guidelines, the variant was classified as pathogenic. Conclusion: This study expands the spectrum of SLC26A4 pathogenic variants in hearing loss.
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Affiliation(s)
- Azam Pourahmadiyan
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences , Shahrekord , Iran
| | - Paria Alipour
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences , Shahrekord , Iran
| | - Najmeh Fattahi
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences , Shahrekord , Iran
| | - Mahbubeh Kasiri
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences , Shahrekord , Iran
| | - Fateme Rezaeian
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences , Shahrekord , Iran
| | - Afsaneh Taghipour-Sheshdeh
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences , Shahrekord , Iran
| | - Javad Mohammadi-Asl
- Department of Medical Genetics, School of Medicine, Ahvaz Jundishapur University of Medical Sciences , Ahvaz , Iran
| | - Mohammad Amin Tabatabaiefar
- Department of Genetics and Molecular Biology, School of Medicine, Isfahan University of Medical Sciences , Isfahan , Iran.,Pediatric Inherited Diseases Research Center, Research Institute for Primordial Prevention of Non-communicable Disease, Isfahan University of Medical Sciences , Isfahan , Iran
| | - Morteza Hashemzadeh Chaleshtori
- Cellular and Molecular Research Center, Basic Health Sciences Institute, Shahrekord University of Medical Sciences , Shahrekord , Iran
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28
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Chang YN, Jaumann EA, Reichel K, Hartmann J, Oliver D, Hummer G, Joseph B, Geertsma ER. Structural basis for functional interactions in dimers of SLC26 transporters. Nat Commun 2019; 10:2032. [PMID: 31048734 PMCID: PMC6497670 DOI: 10.1038/s41467-019-10001-w] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 04/13/2019] [Indexed: 12/13/2022] Open
Abstract
The SLC26 family of transporters maintains anion equilibria in all kingdoms of life. The family shares a 7 + 7 transmembrane segments inverted repeat architecture with the SLC4 and SLC23 families, but holds a regulatory STAS domain in addition. While the only experimental SLC26 structure is monomeric, SLC26 proteins form structural and functional dimers in the lipid membrane. Here we resolve the structure of an SLC26 dimer embedded in a lipid membrane and characterize its functional relevance by combining PELDOR/DEER distance measurements and biochemical studies with MD simulations and spin-label ensemble refinement. Our structural model reveals a unique interface different from the SLC4 and SLC23 families. The functionally relevant STAS domain is no prerequisite for dimerization. Characterization of heterodimers indicates that protomers in the dimer functionally interact. The combined structural and functional data define the framework for a mechanistic understanding of functional cooperativity in SLC26 dimers.
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Affiliation(s)
- Yung-Ning Chang
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany
| | - Eva A Jaumann
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue Str. 7, 60438, Frankfurt am Main, Germany
| | - Katrin Reichel
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue Str. 3, 60438, Frankfurt am Main, Germany
| | - Julia Hartmann
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University, 35037, Marburg, Germany
| | - Dominik Oliver
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University, 35037, Marburg, Germany.,DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodeling, Philipps University, GRK 2213, Philipps, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max-von-Laue Str. 3, 60438, Frankfurt am Main, Germany. .,Institute of Biophysics, Goethe University Frankfurt, Max-von-Laue Str. 1, 60438, Frankfurt am Main, Germany.
| | - Benesh Joseph
- Institute of Physical and Theoretical Chemistry, Goethe University Frankfurt, Max-von-Laue Str. 7, 60438, Frankfurt am Main, Germany. .,Institute of Biophysics, Goethe University Frankfurt, Max-von-Laue Str. 1, 60438, Frankfurt am Main, Germany.
| | - Eric R Geertsma
- Institute of Biochemistry, Biocenter, Goethe University Frankfurt, Max-von-Laue Str. 9, 60438, Frankfurt am Main, Germany.
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29
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Seidler U, Nikolovska K. Slc26 Family of Anion Transporters in the Gastrointestinal Tract: Expression, Function, Regulation, and Role in Disease. Compr Physiol 2019; 9:839-872. [DOI: 10.1002/cphy.c180027] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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30
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Interleukin-Mediated Pendrin Transcriptional Regulation in Airway and Esophageal Epithelia. Int J Mol Sci 2019; 20:ijms20030731. [PMID: 30744098 PMCID: PMC6386862 DOI: 10.3390/ijms20030731] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 01/29/2019] [Accepted: 01/29/2019] [Indexed: 12/28/2022] Open
Abstract
Pendrin (SLC26A4), a Cl−/anion exchanger, is expressed at high levels in kidney, thyroid, and inner ear epithelia, where it has an essential role in bicarbonate secretion/chloride reabsorption, iodide accumulation, and endolymph ion balance, respectively. Pendrin is expressed at lower levels in other tissues, such as airways and esophageal epithelia, where it is transcriptionally regulated by the inflammatory cytokines interleukin (IL)-4 and IL-13 through a signal transducer and activator of transcription 6 (STAT6)-mediated pathway. In the airway epithelium, increased pendrin expression during inflammatory diseases leads to imbalances in airway surface liquid thickness and mucin release, while, in the esophageal epithelium, dysregulated pendrin expression is supposed to impact the intracellular pH regulation system. In this review, we discuss some of the recent findings on interleukin-mediated transcriptional regulation of pendrin and how this dysregulation impacts airway and esophagus epithelial homeostasis during inflammatory diseases.
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31
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Kuwabara MF, Wasano K, Takahashi S, Bodner J, Komori T, Uemura S, Zheng J, Shima T, Homma K. The extracellular loop of pendrin and prestin modulates their voltage-sensing property. J Biol Chem 2018; 293:9970-9980. [PMID: 29777056 DOI: 10.1074/jbc.ra118.001831] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 04/24/2018] [Indexed: 12/21/2022] Open
Abstract
Pendrin and prestin belong to the solute carrier 26 (SLC26) family of anion transporters. Prestin is unique among the SLC26 family members in that it displays voltage-driven motor activity (electromotility) and concurrent gating currents that manifest as nonlinear cell membrane electrical capacitance (nonlinear capacitance (NLC)). Although the anion transport mechanism of the SLC26 proteins has begun to be elucidated, the molecular mechanism of electromotility, which is thought to have evolved from an ancestral ion transport mechanism, still remains largely elusive. Here, we demonstrate that pendrin also exhibits large NLC and that charged residues present in one of the extracellular loops of pendrin and prestin play significant roles in setting the voltage-operating points of NLC. Our results suggest that the molecular mechanism responsible for sensing voltage is not unique to prestin among the members of the SLC26 family and that this voltage-sensing mechanism works independently of the anion transport mechanism.
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Affiliation(s)
- Makoto F Kuwabara
- From the Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Koichiro Wasano
- the Department of Otolaryngology-Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Satoe Takahashi
- the Department of Otolaryngology-Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | | | - Tomotaka Komori
- From the Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Sotaro Uemura
- From the Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Jing Zheng
- the Department of Otolaryngology-Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611.,The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University, Evanston, Illinois 60608
| | - Tomohiro Shima
- From the Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan,
| | - Kazuaki Homma
- the Department of Otolaryngology-Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, .,The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University, Evanston, Illinois 60608
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32
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Affiliation(s)
- Timothy D Usher
- Department of Physics California State University San Bernardino San Bernardino CA USA
| | - Kimberley R Cousins
- Department of Chemistry and Biochemistry California State University San Bernardino San Bernardino CA USA
| | - Renwu Zhang
- Department of Chemistry and Biochemistry California State University San Bernardino San Bernardino CA USA
| | - Stephen Ducharme
- Department of Physics and Astronomy Nebraska Center for Materials and Nanoscience, University of Nebraska Lincoln Lincoln NE USA
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33
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Rapp C, Bai X, Reithmeier RAF. Molecular analysis of human solute carrier SLC26 anion transporter disease-causing mutations using 3-dimensional homology modeling. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:2420-2434. [PMID: 28941661 DOI: 10.1016/j.bbamem.2017.09.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 06/08/2017] [Accepted: 09/14/2017] [Indexed: 12/22/2022]
Abstract
The availability of the first crystal structure of a bacterial member (SLC26Dg) of the solute carrier SLC26 family of anion transporters has allowed us to create 3-dimensional models of all 10 human members (SLC26A1-A11, A10 being a pseudogene) of these membrane proteins using the Phyre2 bioinformatic tool. The homology modeling predicted that the SLC26 human proteins, like the SLC26Dg template, all consist of 14 transmembrane segments (TM) arranged in a 7+7 inverted topology with the amino-termini of two half-helices (TM3 and 10) facing each other in the centre of the protein to create the anion-binding site, linked to a C-terminal cytosolic sulfate transporter anti-sigma factor antagonist (STAS) domain. A plethora of human diseases are associated with mutations in the genes encoding human SLC26 transporters, including chondrodysplasias with varying severity in SLC26A2 (~50 mutations, 27 point mutations), congenital chloride-losing diarrhea in SLC26A3 (~70 mutations, 31 point mutations) and Pendred Syndrome or deafness autosomal recessive type 4 in SLC26A4 (~500 mutations, 203 point mutations). We have localized all of these point mutations in the 3-dimensional structures of the respective SLC26A2, A3 and A4 proteins and systematically analyzed their effect on protein structure. While most disease-causing mutations may cause folding defects resulting in impaired trafficking of these membrane glycoproteins from the endoplasmic reticulum to the cell surface - as demonstrated in a number of functional expression studies - the modeling also revealed that a number of pathogenic mutations are localized to the anion-binding site, which may directly affect transport function.
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Affiliation(s)
- Chloe Rapp
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Xiaoyun Bai
- Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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34
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Fettiplace R. Hair Cell Transduction, Tuning, and Synaptic Transmission in the Mammalian Cochlea. Compr Physiol 2017; 7:1197-1227. [PMID: 28915323 DOI: 10.1002/cphy.c160049] [Citation(s) in RCA: 197] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Sound pressure fluctuations striking the ear are conveyed to the cochlea, where they vibrate the basilar membrane on which sit hair cells, the mechanoreceptors of the inner ear. Recordings of hair cell electrical responses have shown that they transduce sound via submicrometer deflections of their hair bundles, which are arrays of interconnected stereocilia containing the mechanoelectrical transducer (MET) channels. MET channels are activated by tension in extracellular tip links bridging adjacent stereocilia, and they can respond within microseconds to nanometer displacements of the bundle, facilitated by multiple processes of Ca2+-dependent adaptation. Studies of mouse mutants have produced much detail about the molecular organization of the stereocilia, the tip links and their attachment sites, and the MET channels localized to the lower end of each tip link. The mammalian cochlea contains two categories of hair cells. Inner hair cells relay acoustic information via multiple ribbon synapses that transmit rapidly without rundown. Outer hair cells are important for amplifying sound-evoked vibrations. The amplification mechanism primarily involves contractions of the outer hair cells, which are driven by changes in membrane potential and mediated by prestin, a motor protein in the outer hair cell lateral membrane. Different sound frequencies are separated along the cochlea, with each hair cell being tuned to a narrow frequency range; amplification sharpens the frequency resolution and augments sensitivity 100-fold around the cell's characteristic frequency. Genetic mutations and environmental factors such as acoustic overstimulation cause hearing loss through irreversible damage to the hair cells or degeneration of inner hair cell synapses. © 2017 American Physiological Society. Compr Physiol 7:1197-1227, 2017.
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Affiliation(s)
- Robert Fettiplace
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
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35
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In vivo genetic manipulation of inner ear connexin expression by bovine adeno-associated viral vectors. Sci Rep 2017; 7:6567. [PMID: 28779115 PMCID: PMC5544751 DOI: 10.1038/s41598-017-06759-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 06/19/2017] [Indexed: 01/03/2023] Open
Abstract
We have previously shown that in vitro transduction with bovine adeno–associated viral (BAAV) vectors restores connexin expression and rescues gap junction coupling in cochlear organotypic cultures from connexin–deficient mice that are models DFNB1 nonsyndromic hearing loss and deafness. The aims of this study were to manipulate inner ear connexin expression in vivo using BAAV vectors, and to identify the optimal route of vector delivery. Injection of a BAAV vector encoding a bacterial Cre recombinase via canalostomy in adult mice with floxed connexin 26 (Cx26) alleles promoted Cre/LoxP recombination, resulting in decreased Cx26 expression, decreased endocochlear potential, increased hearing thresholds, and extensive loss of outer hair cells. Injection of a BAAV vector encoding GFP-tagged Cx30 via canalostomy in P4 mice lacking connexin 30 (Cx30) promoted formation of Cx30 gap junctions at points of contacts between adjacent non-sensory cells of the cochlear sensory epithelium. Levels of exogenous Cx30 decayed over time, but were still detectable four weeks after canalostomy. Our results suggest that persistence of BAAV-mediated gene replacement in the cochlea is limited by the extensive remodeling of the organ of Corti throughout postnatal development and associated loss of non-sensory cells.
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36
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Santos-Sacchi J, Song L. Chloride Anions Regulate Kinetics but Not Voltage-Sensor Qmax of the Solute Carrier SLC26a5. Biophys J 2017; 110:2551-2561. [PMID: 27276272 DOI: 10.1016/j.bpj.2016.05.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 05/02/2016] [Accepted: 05/04/2016] [Indexed: 12/23/2022] Open
Abstract
In general, SLC26 solute carriers serve to transport a variety of anions across biological membranes. However, prestin (SLC26a5) has evolved, now serving as a motor protein in outer hair cells (OHCs) of the mammalian inner ear and is required for cochlear amplification, a mechanical feedback mechanism to boost auditory performance. The mechanical activity of the OHC imparted by prestin is driven by voltage and controlled by anions, chiefly intracellular chloride. Current opinion is that chloride anions control the Boltzmann characteristics of the voltage sensor responsible for prestin activity, including Qmax, the total sensor charge moved within the membrane, and Vh, a measure of prestin's operating voltage range. Here, we show that standard narrow-band, high-frequency admittance measures of nonlinear capacitance (NLC), an alternate representation of the sensor's charge-voltage (Q-V) relationship, is inadequate for assessment of Qmax, an estimate of the sum of unitary charges contributed by all voltage sensors within the membrane. Prestin's slow transition rates and chloride-binding kinetics adversely influence these estimates, contributing to the prevalent concept that intracellular chloride level controls the quantity of sensor charge moved. By monitoring charge movement across frequency, using measures of multifrequency admittance, expanded displacement current integration, and OHC electromotility, we find that chloride influences prestin kinetics, thereby controlling charge magnitude at any particular frequency of interrogation. Importantly, however, this chloride dependence vanishes as frequency decreases, with Qmax asymptoting at a level irrespective of the chloride level. These data indicate that prestin activity is significantly low-pass in the frequency domain, with important implications for cochlear amplification. We also note that the occurrence of voltage-dependent charge movements in other SLC26 family members may be hidden by inadequate interrogation timescales, and that revelation of such activity could highlight an evolutionary means for kinetic modifications within the family to address hearing requirements in mammals.
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Affiliation(s)
- Joseph Santos-Sacchi
- Department of Surgery (Otolaryngology), Yale University School of Medicine, New Haven, Connecticut; Department of Neuroscience, Yale University School of Medicine, New Haven, Connecticut; Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut.
| | - Lei Song
- Department of Surgery (Otolaryngology), Yale University School of Medicine, New Haven, Connecticut
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37
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Mammano F, Bortolozzi M. Ca 2+ signaling, apoptosis and autophagy in the developing cochlea: Milestones to hearing acquisition. Cell Calcium 2017; 70:117-126. [PMID: 28578918 DOI: 10.1016/j.ceca.2017.05.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 05/09/2017] [Accepted: 05/09/2017] [Indexed: 12/16/2022]
Abstract
In mammals, the sense of hearing arises through a complex sequence of morphogenetic events that drive the sculpting of the auditory sensory epithelium into its terminally functional three-dimensional shape. While the majority of the underlying mechanisms remain unknown, it has become increasingly clear that Ca2+ signaling is at center stage and plays numerous fundamental roles both in the sensory hair cells and in the matrix of non-sensory, epithelial and supporting cells, which embed them and are tightly interconnected by a dense network of gap junctions formed by connexin 26 (Cx26) and connexin 30 (Cx30) protein subunits. In this review, we discuss the intricate interplay between Ca2+ signaling, connexin expression and function, apoptosis and autophagy in the crucial steps that lead to hearing acquisition.
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Affiliation(s)
- Fabio Mammano
- Department of Physics and Astronomy "G. Galilei", University of Padua, 35131 Padua, Italy; Venetian Institute of Molecular Medicine (VIMM), Foundation for Advanced Biomedical Research, 35129 Padua, Italy; Department of Biomedical Sciences, Institute of Cell Biology and Neurobiology, Italian National Research Council, 00015 Monterotondo, (RM), Italy.
| | - Mario Bortolozzi
- Department of Physics and Astronomy "G. Galilei", University of Padua, 35131 Padua, Italy; Venetian Institute of Molecular Medicine (VIMM), Foundation for Advanced Biomedical Research, 35129 Padua, Italy; Department of Biomedical Sciences, Institute of Protein Biochemistry, Italian National Research Council, 80131 Naples (NA), Italy
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38
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Bai JP, Moeini-Naghani I, Zhong S, Li FY, Bian S, Sigworth FJ, Santos-Sacchi J, Navaratnam D. Current carried by the Slc26 family member prestin does not flow through the transporter pathway. Sci Rep 2017; 7:46619. [PMID: 28422190 PMCID: PMC5395958 DOI: 10.1038/srep46619] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 03/21/2017] [Indexed: 01/01/2023] Open
Abstract
Prestin in the lateral membrane of outer hair cells, is responsible for electromotility (EM) and a corresponding nonlinear capacitance (NLC). Prestin’s voltage sensitivity is influenced by intracellular chloride. A regulator of intracellular chloride is a stretch-sensitive, non-selective conductance within the lateral membrane, GmetL. We determine that prestin itself possesses a stretch-sensitive, non-selective conductance that is largest in the presence of thiocyanate ions. This conductance is independent of the anion transporter mechanism. Prestin has been modeled, based on structural data from related anion transporters (SLC26Dg and UraA), to have a 7 + 7 inverted repeat structure with anion transport initiated by chloride binding at the intracellular cleft. Mutation of residues that bind intracellular chloride, and salicylate treatment which prevents chloride binding, have no effect on thiocyanate conductance. In contrast, other mutations reduce the conductance while preserving NLC. When superimposed on prestin’s structure, the location of these mutations indicates that the ion permeation pathway lies between the core and gate ring of helices, distinct from the transporter pathway. The uncoupled current is reminiscent of an omega current in voltage-gated ion channels. We suggest that prestin itself is the main regulator of intracellular chloride concentration via a route distinct from its transporter pathway.
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Affiliation(s)
- Jun-Ping Bai
- Dept. of Neurology, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510 USA
| | - Iman Moeini-Naghani
- Dept. of Neurology, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510 USA
| | - Sheng Zhong
- Dept. of Surgery, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510 USA
| | - Fang-Yong Li
- Yale Center for Analytical Sciences, Yale School of Public Health, 300 George St., Ste Suite 555, New Haven, CT 06511, USA
| | - Shumin Bian
- Dept. of Neurology, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510 USA
| | - Fred J Sigworth
- Dept. of Cellular and Molecular Physiology, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510, USA
| | - Joseph Santos-Sacchi
- Dept. of Surgery, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510 USA.,Dept. of Cellular and Molecular Physiology, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510, USA.,Dept. of, Neuroscience, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510, USA
| | - Dhasakumar Navaratnam
- Dept. of Neurology, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510 USA.,Dept. of Surgery, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510 USA.,Dept. of, Neuroscience, Yale School of Medicine, 333 Cedar Street, New Haven, CT, 06510, USA
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Mapping pathogenic mutations suggests an innovative structural model for the pendrin (SLC26A4) transmembrane domain. Biochimie 2016; 132:109-120. [PMID: 27771369 DOI: 10.1016/j.biochi.2016.10.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 10/03/2016] [Indexed: 12/16/2022]
Abstract
Human pendrin (SLC26A4) is an anion transporter mostly expressed in the inner ear, thyroid and kidney. SLC26A4 gene mutations are associated with a broad phenotypic spectrum, including Pendred Syndrome and non-syndromic hearing loss with enlarged vestibular aqueduct (ns-EVA). No experimental structure of pendrin is currently available, making phenotype-genotype correlations difficult as predictions of transmembrane (TM) segments vary in number. Here, we propose a novel three-dimensional (3D) pendrin transmembrane domain model based on the SLC26Dg transporter. The resulting 14 TM topology was found to include two non-canonical transmembrane segments crucial for pendrin activity. Mutation mapping of 147 clinically validated pathological mutations shows that most affect two previously undescribed TM regions.
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40
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Cao H, Zhang A, Sun H, Zhou X, Guan Y, Liu Q, Kong L, Wang X. Metabolomics-proteomics profiles delineate metabolic changes in kidney fibrosis disease. Proteomics 2016; 15:3699-710. [PMID: 26256572 DOI: 10.1002/pmic.201500062] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 07/16/2015] [Accepted: 08/06/2015] [Indexed: 12/24/2022]
Abstract
Kidney fibrosis (KF) is a common process that leads to the progression of various types of kidney disease including kidney-yang deficiency syndrome, however, little is known regarding the underlying biology of this disorder. Fortunately, integrated omics approaches provide the molecule fingerprints related to the disease. In an attempt to address this issue, we integrated metabolomics-proteomics profiles analyzed pathogenic mechanisms of KF based on rat model. A total 37 serum differential metabolites were contributed to KF progress, involved several important metabolic pathways. Using iTRAQ-based quantitative proteomics analysis, 126 differential serum proteins were identified and provide valuable insight into the underlying mechanisms of KF. These proteins appear to be involved in complement and coagulation cascades, regulation of actin cytoskeleton, MAPK signaling pathway, RNA transport, etc. Interestingly, pathway/network analysis of integrated proteomics and metabolomics data firstly reveals that these signaling pathways were closely related with KF. It further indicated that most of these proteins play a pivotal role in the regulation of metabolism pathways.
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Affiliation(s)
- Hongxin Cao
- National TCM Key Laboratory of Serum Pharmacochemistry, Key Laboratory of Metabolomics and Chinmedomics, Department of Pharmaceutical Analysis, Heilongjiang University of Chinese Medicine, Harbin, P. R. China.,China Academy of Chinese Medical Science, Beijing, P. R. China
| | - Aihua Zhang
- National TCM Key Laboratory of Serum Pharmacochemistry, Key Laboratory of Metabolomics and Chinmedomics, Department of Pharmaceutical Analysis, Heilongjiang University of Chinese Medicine, Harbin, P. R. China
| | - Hui Sun
- National TCM Key Laboratory of Serum Pharmacochemistry, Key Laboratory of Metabolomics and Chinmedomics, Department of Pharmaceutical Analysis, Heilongjiang University of Chinese Medicine, Harbin, P. R. China
| | - Xiaohang Zhou
- National TCM Key Laboratory of Serum Pharmacochemistry, Key Laboratory of Metabolomics and Chinmedomics, Department of Pharmaceutical Analysis, Heilongjiang University of Chinese Medicine, Harbin, P. R. China
| | - Yu Guan
- National TCM Key Laboratory of Serum Pharmacochemistry, Key Laboratory of Metabolomics and Chinmedomics, Department of Pharmaceutical Analysis, Heilongjiang University of Chinese Medicine, Harbin, P. R. China
| | - Qi Liu
- National TCM Key Laboratory of Serum Pharmacochemistry, Key Laboratory of Metabolomics and Chinmedomics, Department of Pharmaceutical Analysis, Heilongjiang University of Chinese Medicine, Harbin, P. R. China
| | - Ling Kong
- National TCM Key Laboratory of Serum Pharmacochemistry, Key Laboratory of Metabolomics and Chinmedomics, Department of Pharmaceutical Analysis, Heilongjiang University of Chinese Medicine, Harbin, P. R. China
| | - Xijun Wang
- National TCM Key Laboratory of Serum Pharmacochemistry, Key Laboratory of Metabolomics and Chinmedomics, Department of Pharmaceutical Analysis, Heilongjiang University of Chinese Medicine, Harbin, P. R. China
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41
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Extracellular Cl(-) regulates human SO4 (2-)/anion exchanger SLC26A1 by altering pH sensitivity of anion transport. Pflugers Arch 2016; 468:1311-32. [PMID: 27125215 DOI: 10.1007/s00424-016-1823-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 04/03/2016] [Accepted: 04/07/2016] [Indexed: 12/16/2022]
Abstract
Genetic deficiency of the SLC26A1 anion exchanger in mice is known to be associated with hyposulfatemia and hyperoxaluria with nephrolithiasis, but many aspects of human SLC26A1 function remain to be explored. We report here the functional characterization of human SLC26A1, a 4,4'-diisothiocyanato-2,2'-stilbenedisulfonic acid (DIDS)-sensitive, electroneutral sodium-independent anion exchanger transporting sulfate, oxalate, bicarbonate, thiosulfate, and (with divergent properties) chloride. Human SLC26A1-mediated anion exchange differs from that of its rodent orthologs in its stimulation by alkaline pHo and inhibition by acidic pHo but not pHi and in its failure to transport glyoxylate. SLC26A1-mediated transport of sulfate and oxalate is highly dependent on allosteric activation by extracellular chloride or non-substrate anions. Extracellular chloride stimulates apparent V max of human SLC26A1-mediated sulfate uptake by conferring a 2-log decrease in sensitivity to inhibition by extracellular protons, without changing transporter affinity for extracellular sulfate. In contrast to SLC26A1-mediated sulfate transport, SLC26A1-associated chloride transport is activated by acid pHo, shows reduced sensitivity to DIDS, and exhibits cation dependence of its DIDS-insensitive component. Human SLC26A1 resembles SLC26 paralogs in its inhibition by phorbol ester activation of protein kinase C (PKC), which differs in its undiminished polypeptide abundance at or near the oocyte surface. Mutation of SLC26A1 residues corresponding to candidate anion binding site-associated residues in avian SLC26A5/prestin altered anion transport in patterns resembling those of prestin. However, rare SLC26A1 polymorphic variants from a patient with renal Fanconi Syndrome and from a patient with nephrolithiasis/calcinosis exhibited no loss-of-function phenotypes consistent with disease pathogenesis.
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42
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Hasegawa K, Kato A, Watanabe T, Takagi W, Romero MF, Bell JD, Toop T, Donald JA, Hyodo S. Sulfate transporters involved in sulfate secretion in the kidney are localized in the renal proximal tubule II of the elephant fish (Callorhinchus milii). Am J Physiol Regul Integr Comp Physiol 2016; 311:R66-78. [PMID: 27122370 PMCID: PMC4967232 DOI: 10.1152/ajpregu.00477.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Accepted: 03/22/2016] [Indexed: 11/22/2022]
Abstract
Most vertebrates, including cartilaginous fishes, maintain their plasma SO4 (2-) concentration ([SO4 (2-)]) within a narrow range of 0.2-1 mM. As seawater has a [SO4 (2-)] about 40 times higher than that of the plasma, SO4 (2-) excretion is the major role of kidneys in marine teleost fishes. It has been suggested that cartilaginous fishes also excrete excess SO4 (2-) via the kidney. However, little is known about the underlying mechanisms for SO4 (2-) transport in cartilaginous fish, largely due to the extraordinarily elaborate four-loop configuration of the nephron, which consists of at least 10 morphologically distinguishable segments. In the present study, we determined cDNA sequences from the kidney of holocephalan elephant fish (Callorhinchus milii) that encoded solute carrier family 26 member 1 (Slc26a1) and member 6 (Slc26a6), which are SO4 (2-) transporters that are expressed in mammalian and teleost kidneys. Elephant fish Slc26a1 (cmSlc26a1) and cmSlc26a6 mRNAs were coexpressed in the proximal II (PII) segment of the nephron, which comprises the second loop in the sinus zone. Functional analyses using Xenopus oocytes and the results of immunohistochemistry revealed that cmSlc26a1 is a basolaterally located electroneutral SO4 (2-) transporter, while cmSlc26a6 is an apically located, electrogenic Cl(-)/SO4 (2-) exchanger. In addition, we found that both cmSlc26a1 and cmSlc26a6 were abundantly expressed in the kidney of embryos; SO4 (2-) was concentrated in a bladder-like structure of elephant fish embryos. Our results demonstrated that the PII segment of the nephron contributes to the secretion of excess SO4 (2-) by the kidney of elephant fish. Possible mechanisms for SO4 (2-) secretion in the PII segment are discussed.
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Affiliation(s)
- Kumi Hasegawa
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan;
| | - Akira Kato
- Center for Biological Resources and Informatics and Department of Biological Sciences, Tokyo Institute of Technology, Yokohama, Japan; Departments of Physiology and Biomedical Engineering, Nephrology, and Hypertension, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Taro Watanabe
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
| | - Wataru Takagi
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan; Evolutionary Morphology Laboratory, RIKEN Center for Life Science and Technologies, Kobe, Japan
| | - Michael F Romero
- Departments of Physiology and Biomedical Engineering, Nephrology, and Hypertension, Mayo Clinic College of Medicine, Rochester, Minnesota
| | - Justin D Bell
- School of Life and Environmental Sciences, Deakin University, Geelong, Australia; and Institute for Marine and Antarctic Studies, The University of Tasmania, Taroona, Australia
| | - Tes Toop
- School of Life and Environmental Sciences, Deakin University, Geelong, Australia; and
| | - John A Donald
- School of Life and Environmental Sciences, Deakin University, Geelong, Australia; and
| | - Susumu Hyodo
- Laboratory of Physiology, Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
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43
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The R130S mutation significantly affects the function of prestin, the outer hair cell motor protein. J Mol Med (Berl) 2016; 94:1053-62. [PMID: 27041369 DOI: 10.1007/s00109-016-1410-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 02/01/2016] [Accepted: 02/29/2016] [Indexed: 01/29/2023]
Abstract
UNLABELLED A missense mutation, R130S, was recently found in the prestin gene, SLC26A5, of patients with moderate to severe hearing loss (DFNB61). In order to define the pathology of hearing loss associated with this missense mutation, a recombinant prestin construct harboring the R130S mutation (R130S-prestin) was generated, and its functional consequences examined in a heterologous expression system. We found that R130S-prestin targets the plasma membrane but less efficiently compared to wild-type. The voltage operating point and voltage sensitivity of the motor function of R130S-prestin were similar to wild-type prestin. However, the motor activity of R130S-prestin is greatly reduced at higher voltage stimulus frequencies, indicating a reduction in motor kinetics. Our study thus provides experimental evidence that supports a causal relationship between the R130S mutation in the prestin gene and hearing loss found in patients with this missense mutation. KEY MESSAGE Membrane targeting of prestin is impaired by the R130S missense mutation. The fast motor kinetics of prestin is impaired by the R130S missense mutation. Our study strongly suggests that the prestin R130S missense mutation is pathogenic.
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44
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Harasztosi C, Gummer AW. The chloride-channel blocker 9-anthracenecarboxylic acid reduces the nonlinear capacitance of prestin-associated charge movement. Eur J Neurosci 2016; 43:1062-74. [PMID: 26869218 PMCID: PMC5111741 DOI: 10.1111/ejn.13209] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 02/09/2016] [Accepted: 02/09/2016] [Indexed: 02/01/2023]
Abstract
The basis of the extraordinary sensitivity and frequency selectivity of the cochlea is a chloride-sensitive protein called prestin which can produce an electromechanical response and which resides in the basolateral plasma membrane of outer hair cells (OHCs). The compound 9-anthracenecarboxylic acid (9-AC), an inhibitor of chloride channels, has been found to reduce the electromechanical response of the cochlea and the OHC mechanical impedance. To elucidate these 9-AC effects, the functional electromechanical status of prestin was assayed by measuring the nonlinear capacitance of OHCs from the guinea-pig cochlea and of prestin-transfected human embryonic kidney 293 (HEK 293) cells. Extracellular application of 9-AC caused reversible, dose-dependent and chloride-sensitive reduction in OHC nonlinear charge transfer, Qmax . Prestin-transfected cells also showed reversible reduction in Qmax . For OHCs, intracellular 9-AC application as well as reduced intracellular pH had no detectable effect on the reduction in Qmax by extracellularly applied 9-AC. In the prestin-transfected cells, cytosolic application of 9-AC approximately halved the blocking efficacy of extracellularly applied 9-AC. OHC inside-out patches presented the whole-cell blocking characteristics. Disruption of the cytoskeleton by preventing actin polymerization with latrunculin A or by decoupling of spectrin from actin with diamide did not affect the 9-AC-evoked reduction in Qmax . We conclude that 9-AC acts on the electromechanical transducer principally by interaction with prestin rather than acting via the cytoskeleton, chloride channels or pH. The 9-AC block presents characteristics in common with salicylate, but is almost an order of magnitude faster. 9-AC provides a new tool for elucidating the molecular dynamics of prestin function.
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Affiliation(s)
- Csaba Harasztosi
- Section of Physiological Acoustics and Communication, Faculty of Medicine, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
| | - Anthony W Gummer
- Section of Physiological Acoustics and Communication, Faculty of Medicine, Eberhard Karls University Tübingen, 72076, Tübingen, Germany
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45
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The STAS domain of mammalian SLC26A5 prestin harbours an anion-binding site. Biochem J 2016; 473:365-70. [DOI: 10.1042/bj20151089] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 12/03/2015] [Indexed: 01/08/2023]
Abstract
The STAS domain of mammalian prestin harbours an anion-binding site absent from non-mammalian homologues. This is correlated to different prestin functions, full anion transport in non-mammals and incomplete transport coupled to electromotility and a mechanically amplified hearing process in mammals.
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46
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Park C, Thein P, Kalinec G, Kalinec F. HEI-OC1 cells as a model for investigating prestin function. Hear Res 2016; 335:9-17. [PMID: 26854618 DOI: 10.1016/j.heares.2016.02.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Revised: 12/05/2015] [Accepted: 02/03/2016] [Indexed: 10/22/2022]
Abstract
The House Ear Institute-Organ of Corti 1 (HEI-OC1) is a mouse auditory cell line that endogenously express, among other several markers of cochlear hair cells, the motor protein prestin (SLC26A5). Since its discovery fifteen years ago, and because of the difficulties associated with working with outer hair cells, prestin studies have been performed mostly by expressing it exogenously in non-specific systems such as HEK293 and TSA201, embryonic kidney cells from human origin, or Chinese Hamster Ovary (CHO) cells. Here, we report flow cytometry and confocal laser scanning microscopy studies on the pattern of prestin expression, as well as nonlinear capacitance (NLC) and whole cell-patch clamping studies on prestin motor function, in HEI-OC1 cells cultured at permissive and non-permissive conditions. Our results indicate that both total prestin expression and plasma membrane localization increase in a time-dependent manner when HEI-OC1 cells differentiate under non-permissive culture conditions. In addition, we demonstrate that HEI-OC1 cells have a robust NLC associated to prestin motor function, which decreases when the density of prestin molecules present at the plasma membrane increases. Altogether, our results show that the response of endogenously expressed prestin in HEI-OC1 cells is different from the response of prestin expressed exogenously in non-auditory cells, and suggest that the HEI-OC1 cell line may be an important additional tool for investigating prestin function.
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Affiliation(s)
- Channy Park
- Laboratory of Auditory Cell Biology, Department of Head & Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Pru Thein
- Laboratory of Auditory Cell Biology, Department of Head & Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Gilda Kalinec
- Laboratory of Auditory Cell Biology, Department of Head & Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Federico Kalinec
- Laboratory of Auditory Cell Biology, Department of Head & Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
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Abstract
Conclusion Auditory phenotypes of two children harboring prestin gene mutations were congenital or pre-lingual onset, moderate to profound, slowly progressive or non-progressive, and audiograms with either flat configuration or prominently elevated thresholds at middle and high frequencies. Objectives Despite the essential role of the prestin gene in hearing, only one mutation in two families and a missense variant in a family had been reported previously before our study reporting another family. The purpose of this study was to characterize auditory phenotypes in children recently found to harbor novel mutations in the prestin gene. Methods The subjects were two sisters with bilateral sensorineural hearing loss who were compound heterozygotes for c.209G > A (p.W70X) and c.390A > C (p.R130S) mutations in the prestin gene. Clinical history and auditory test results were collected and analyzed. Results Hearing loss was present from birth in the younger sister and occurred before 6 years of age in the elder sister. The degree of hearing loss was profound in the elder sister with little progression, and moderate in the younger sister with no progression. The audiogram of the elder sister showed prominently elevated thresholds at middle and high frequencies, while that of the younger sister demonstrated a flat configuration.
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Affiliation(s)
- Tatsuo Matsunaga
- a Laboratory of Auditory Disorders/Department of Otolaryngology/Medical Genetics Center , National Institute of Sensory Organs, National Tokyo Medical Center , Tokyo , Japan
| | - Noriko Morimoto
- b Division of Otolaryngology , National Center for Child Health and Development , Tokyo , Japan
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48
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Novel Roles for Chloride Channels, Exchangers, and Regulators in Chronic Inflammatory Airway Diseases. Mediators Inflamm 2015; 2015:497387. [PMID: 26612971 PMCID: PMC4647060 DOI: 10.1155/2015/497387] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 10/13/2015] [Indexed: 01/14/2023] Open
Abstract
Chloride transport proteins play critical roles in inflammatory airway diseases, contributing to the detrimental aspects of mucus overproduction, mucus secretion, and airway constriction. However, they also play crucial roles in contributing to the innate immune properties of mucus and mucociliary clearance. In this review, we focus on the emerging novel roles for a chloride channel regulator (CLCA1), a calcium-activated chloride channel (TMEM16A), and two chloride exchangers (SLC26A4/pendrin and SLC26A9) in chronic inflammatory airway diseases.
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49
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50
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Geertsma ER, Chang YN, Shaik FR, Neldner Y, Pardon E, Steyaert J, Dutzler R. Structure of a prokaryotic fumarate transporter reveals the architecture of the SLC26 family. Nat Struct Mol Biol 2015; 22:803-8. [PMID: 26367249 DOI: 10.1038/nsmb.3091] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 08/20/2015] [Indexed: 12/18/2022]
Abstract
The SLC26 family of membrane proteins combines a variety of functions within a conserved molecular scaffold. Its members, besides coupled anion transporters and channels, include the motor protein Prestin, which confers electromotility to cochlear outer hair cells. To gain insight into the architecture of this protein family, we characterized the structure and function of SLC26Dg, a facilitator of proton-coupled fumarate symport, from the bacterium Deinococcus geothermalis. Its modular structure combines a transmembrane unit and a cytoplasmic STAS domain. The membrane-inserted domain consists of two intertwined inverted repeats of seven transmembrane segments each and resembles the fold of the unrelated transporter UraA. It shows an inward-facing, ligand-free conformation with a potential substrate-binding site at the interface between two helix termini at the center of the membrane. This structure defines the common framework for the diverse functional behavior of the SLC26 family.
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Affiliation(s)
- Eric R Geertsma
- Department of Biochemistry, University of Zurich, Zurich, Switzerland.,Institute of Biochemistry, Biocenter, Goethe-University Frankfurt, Frankfurt am Main, Germany
| | - Yung-Ning Chang
- Department of Biochemistry, University of Zurich, Zurich, Switzerland.,Institute of Biochemistry, Biocenter, Goethe-University Frankfurt, Frankfurt am Main, Germany
| | - Farooque R Shaik
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Yvonne Neldner
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Els Pardon
- Structural Biology Research Center, Vlaams Instituut voor Biotechnologie, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Jan Steyaert
- Structural Biology Research Center, Vlaams Instituut voor Biotechnologie, Brussels, Belgium.,Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium
| | - Raimund Dutzler
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
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