1
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Zhang Y, Lin G, Xue N, Wang Y, Du T, Liu H, Xiong W, Shang W, Wu H, Song L. Differential outcomes of high-fat diet on age-related rescaling of cochlear frequency place coding. FASEB J 2023; 37:e23167. [PMID: 37651093 DOI: 10.1096/fj.202300457rr] [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] [Received: 03/09/2023] [Revised: 08/01/2023] [Accepted: 08/14/2023] [Indexed: 09/01/2023]
Abstract
Auditory frequency coding is place-specific, which depends on the mechanical coupling of the basilar membrane-outer hair cell (OHC)-tectorial membrane network. Prestin-based OHC electromotility improves cochlear frequency selectivity and sensitivity. Cochlear amplification determines the frequency coding wherein discrete sound frequencies find a 'best' place along the cochlear length. Loss of OHC is the leading cause of age-related hearing loss (ARHL) and is the most common cause of sensorineural hearing loss and compromised speech perception. Lipid interaction with Prestin impacts OHC function. It has been established that high-fat diet (HFD) is associated with ARHL. To determine whether genetic background and metabolism preserve cochlear frequency place coding, we examined the effect of HFD in C57BL/6J (B6) and CBA/CaJ (CBA) on ARHL.We found a significant rescuing effect on ARHL in aged B6 HFD cohort. Prestin levels and cell sizes were better maintained in the experimental B6-HFD group. We also found that distortion product otoacoustic emission (DPOAE) group delay measurement was preserved, which suggested stable frequency place coding. In contrast, the response to HFD in the CBA cohort was modest with no appreciable benefit to hearing threshold. Notably, group delay was shortened with age along with the control. In addition, the frequency dependent OHC nonlinear capacitance gradient was most pronounced at young age but decreased with age. Cochlear RNA-seq analysis revealed differential TRPV1 expression and lipid homeostasis. Activation of TRPV1 and downregulation of arachidonic acid led to downregulation of inflammatory response in B6 HFD, which protects the cochlea from ARHL. The genetic background and metabolic state-derived changes in OHC morphology and function collectively contribute to a redefined cochlear frequency place coding and improved age-related pitch perception.
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Affiliation(s)
- Yu Zhang
- Department of Otolaryngology, Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Guotong Lin
- Department of Otolaryngology, Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Na Xue
- Department of Otolaryngology, Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Yi Wang
- School of Life Sciences, Tsinghua University, Beijing, China
| | - Tingting Du
- Department of Otolaryngology, Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Huihui Liu
- Department of Otolaryngology, Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Wei Xiong
- Chinese Institute for Brain Research, Beijing, China
| | - Wei Shang
- Navy Clinical Medical School, Anhui Medical University, Hefei, China
- In Vitro Fertility (IVF) Center Department of Obstetrics and Gynecology, the Sixth Medical Center of PLA General Hospital, Beijing, China
- Department of Obstetrics and Gynecology, Chinese PLA General Hospital, Beijing, China
| | - Hao Wu
- Department of Otolaryngology, Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Lei Song
- Department of Otolaryngology, Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
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2
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Ganeson K, Tan Xue May C, Abdullah AAA, Ramakrishna S, Vigneswari S. Advantages and Prospective Implications of Smart Materials in Tissue Engineering: Piezoelectric, Shape Memory, and Hydrogels. Pharmaceutics 2023; 15:2356. [PMID: 37765324 PMCID: PMC10535616 DOI: 10.3390/pharmaceutics15092356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 09/11/2023] [Accepted: 09/18/2023] [Indexed: 09/29/2023] Open
Abstract
Conventional biomaterial is frequently used in the biomedical sector for various therapies, imaging, treatment, and theranostic functions. However, their properties are fixed to meet certain applications. Smart materials respond in a controllable and reversible way, modifying some of their properties because of external stimuli. However, protein-based smart materials allow modular protein domains with different functionalities and responsive behaviours to be easily combined. Wherein, these "smart" behaviours can be tuned by amino acid identity and sequence. This review aims to give an insight into the design of smart materials, mainly protein-based piezoelectric materials, shape-memory materials, and hydrogels, as well as highlight the current progress and challenges of protein-based smart materials in tissue engineering. These materials have demonstrated outstanding regeneration of neural, skin, cartilage, bone, and cardiac tissues with great stimuli-responsive properties, biocompatibility, biodegradability, and biofunctionality.
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Affiliation(s)
- Keisheni Ganeson
- Institute of Climate Adaptation and Marine Biotechnolgy (ICAMB), Kuala Nerus 21030, Terengganu, Malaysia;
| | - Cindy Tan Xue May
- Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, Kuala Nerus 21030, Terengganu, Malaysia;
| | - Amirul Al Ashraf Abdullah
- School of Biological Sciences, Universiti Sains Malaysia, Bayan Lepas 11800, Penang, Malaysia;
- Malaysian Institute of Pharmaceuticals and Nutraceuticals, National Institutes of Biotechnology Malaysia, Gelugor 11700, Penang, Malaysia
- Centre for Chemical Biology, Universiti Sains Malaysia, Bayan Lepas 11800, Penang, Malaysia
| | - Seeram Ramakrishna
- Center for Nanofibers and Nanotechnology, Department of Mechanical Engineering, National University of Singapore, Singapore 117581, Singapore
| | - Sevakumaran Vigneswari
- Institute of Climate Adaptation and Marine Biotechnolgy (ICAMB), Kuala Nerus 21030, Terengganu, Malaysia;
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3
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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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Santos-Sacchi J, Tan WJT. Coupling between outer hair cell electromotility and prestin sensor charge depends on voltage operating point. Hear Res 2022; 423:108373. [PMID: 34776274 PMCID: PMC9054947 DOI: 10.1016/j.heares.2021.108373] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/16/2021] [Accepted: 10/13/2021] [Indexed: 11/16/2022]
Abstract
The OHC drives cochlear amplification, and prestin activity is the basis. The frequency response of nonlinear capacitance (NLC), which is a ratiometric measure of prestin's voltage-sensor charge movement (dQp/dVm), depends on the location of AC voltage excitation along prestin's operating voltage range, being slowest at the voltage (Vh) where NLC peaks. Here we directly investigate the coupling between prestin charge movement (Qp) and electromotility (eM) at frequencies up to 6.25 kHz, and find tight correspondence between the two at operating voltages displaced from Vh. Near Vh, however, eM shows a slower frequency response than Qp. We reason that coupling is more susceptible to molecular/cellular loads at Vh, where prestin compliance is expected to be maximal. Recent cryo-EM studies have begun to shed light on structural features of prestin that impact its performance against loads. This article is part of the Special Issue Outer hair cell Edited by Joseph Santos-Sacchi and Kumar Navaratnam.
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Affiliation(s)
- Joseph Santos-Sacchi
- Surgery (Otolaryngology), 333 Cedar Street, New Haven, CT 06510, USA; Neuroscience, 333 Cedar Street, New Haven, CT 06510, USA; Cellular and Molecular Physiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510, USA.
| | - Winston J T Tan
- Surgery (Otolaryngology), 333 Cedar Street, New Haven, CT 06510, USA
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5
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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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6
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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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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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8
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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] [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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Diflunisal inhibits prestin by chloride-dependent mechanism. PLoS One 2017; 12:e0183046. [PMID: 28817613 PMCID: PMC5560734 DOI: 10.1371/journal.pone.0183046] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 07/30/2017] [Indexed: 11/19/2022] Open
Abstract
The motor protein prestin is a member of the SLC26 family of anion antiporters and is essential to the electromotility of cochlear outer hair cells and for hearing. The only direct inhibitor of electromotility and the associated charge transfer is salicylate, possibly through direct interaction with an anion-binding site on prestin. In a screen to identify other inhibitors of prestin activity, we explored the effect of the non-steroid anti-inflammatory drug diflunisal, which is a derivative of salicylate. We recorded prestin activity by whole-cell patch clamping HEK cells transiently expressing prestin and mouse outer hair cells. We monitored the impact of diflunisal on the prestin-dependent non-linear capacitance and electromotility. We found that diflunisal triggers two prestin-associated effects: a chloride independent increase in the surface area and the specific capacitance of the membrane, and a chloride dependent inhibition of the charge transfer and the electromotility in outer hair cells. We conclude that diflunisal affects the cell membrane organization and inhibits prestin-associated charge transfer and electromotility at physiological chloride concentrations. The inhibitory effects on hair cell function are noteworthy given the proposed use of diflunisal to treat neurodegenerative diseases.
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Takahashi S, Homma K, Zhou Y, Nishimura S, Duan C, Chen J, Ahmad A, Cheatham MA, Zheng J. Susceptibility of outer hair cells to cholesterol chelator 2-hydroxypropyl-β-cyclodextrine is prestin-dependent. Sci Rep 2016; 6:21973. [PMID: 26903308 PMCID: PMC4763217 DOI: 10.1038/srep21973] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 01/29/2016] [Indexed: 12/19/2022] Open
Abstract
Niemann-Pick type C1 disease (NPC1) is a fatal genetic disorder caused by impaired intracellular cholesterol trafficking. Recent studies reported ototoxicity of 2-hydroxypropyl- β-cyclodextrin (HPβCD), a cholesterol chelator and the only promising treatment for NPC1. Because outer hair cells (OHCs) are the only cochlear cells affected by HPβCD, we investigated whether prestin, an OHC-specific motor protein, might be involved. Single, high-dose administration of HPβCD resulted in OHC death in prestin wildtype (WT) mice whereas OHCs were largely spared in prestin knockout (KO) mice in the basal region, implicating prestin's involvement in ototoxicity of HPβCD. We found that prestin can interact with cholesterol in vitro, suggesting that HPβCD-induced ototoxicity may involve disruption of this interaction. Time-lapse analysis revealed that OHCs isolated from WT animals rapidly deteriorated upon HPβCD treatment while those from prestin-KOs tolerated the same regimen. These results suggest that a prestin-dependent mechanism contributes to HPβCD ototoxicity.
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MESH Headings
- 2-Hydroxypropyl-beta-cyclodextrin
- Animals
- Brain/drug effects
- Brain/metabolism
- Brain/pathology
- Cell Death/drug effects
- Chelating Agents/administration & dosage
- Chelating Agents/adverse effects
- Cholesterol/metabolism
- Disease Susceptibility
- Gene Expression
- Hair Cells, Auditory, Outer/drug effects
- Hair Cells, Auditory, Outer/metabolism
- Hair Cells, Auditory, Outer/pathology
- Hearing Loss, Sensorineural/chemically induced
- Hearing Loss, Sensorineural/genetics
- Hearing Loss, Sensorineural/pathology
- Humans
- Mice
- Mice, Knockout
- Molecular Motor Proteins/deficiency
- Molecular Motor Proteins/genetics
- Neuroprotective Agents/administration & dosage
- Neuroprotective Agents/adverse effects
- Niemann-Pick Disease, Type C/drug therapy
- Niemann-Pick Disease, Type C/genetics
- Niemann-Pick Disease, Type C/metabolism
- Niemann-Pick Disease, Type C/pathology
- Time-Lapse Imaging
- beta-Cyclodextrins/administration & dosage
- beta-Cyclodextrins/adverse effects
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Affiliation(s)
- Satoe Takahashi
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago IL 60611, USA
| | - Kazuaki Homma
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago IL 60611, USA
- Knowles Hearing Center, Northwestern University, Evanston, IL 60208, USA
| | - Yingjie Zhou
- Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL 60208, USA
| | - Shinichi Nishimura
- Division of Bioinformatics and Chemical Genomics, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, 606-8501, Japan
- Chemical Genomics Research Group, RIKEN Center for Sustainable Resource Science, Wako, Saitama 351-0198, Japan
| | - Chongwen Duan
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago IL 60611, USA
| | - Jessie Chen
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago IL 60611, USA
| | - Aisha Ahmad
- Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL 60208, USA
| | - Mary Ann Cheatham
- Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL 60208, USA
- Knowles Hearing Center, Northwestern University, Evanston, IL 60208, USA
| | - Jing Zheng
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago IL 60611, USA
- Knowles Hearing Center, Northwestern University, Evanston, IL 60208, USA
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11
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The capacitance and electromechanical coupling of lipid membranes close to transitions: the effect of electrostriction. Biophys J 2013; 103:918-29. [PMID: 23009841 DOI: 10.1016/j.bpj.2012.07.010] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 07/09/2012] [Accepted: 07/10/2012] [Indexed: 01/24/2023] Open
Abstract
Biomembranes are thin capacitors with the unique feature of displaying phase transitions in a physiologically relevant regime. We investigate the voltage and lateral pressure dependence of their capacitance close to their chain melting transition. Because the gel and the fluid membrane have different area and thickness, the capacitance of the two membrane phases is different. In the presence of external fields, charges exert forces that can influence the state of the membrane, thereby influencing the transition temperature. This phenomenon is called "electrostriction". We show that this effect allows us to introduce a capacitive susceptibility that assumes a maximum in the melting transition with an associated excess charge. As a consequence, voltage regimes exist in which a small change in voltage can lead to a large uptake of charge and a large capacitive current. Furthermore, we consider electromechanical behavior such as pressure-induced changes in capacitance, and the application of such concepts in biology.
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Homma K, Duan C, Zheng J, Cheatham MA, Dallos P. The V499G/Y501H mutation impairs fast motor kinetics of prestin and has significance for defining functional independence of individual prestin subunits. J Biol Chem 2012; 288:2452-63. [PMID: 23212912 DOI: 10.1074/jbc.m112.411579] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Outer hair cells (OHCs) are a mammalian innovation for mechanically amplifying sound energy to overcome the viscous damping of the cochlear partition. Although the voltage-dependent OHC membrane motor, prestin, has been demonstrated to be essential for mammalian cochlear amplification, the molecular mechanism by which prestin converts electrical energy into mechanical displacement/force remains elusive. Identifying mutations that alter the motor function of prestin provides vital information for unraveling the energy transduction mechanism of prestin. We show that the V499G/Y501H mutation does not deprive prestin of its voltage-induced motor activity, but it does significantly impair the fast motor kinetics and voltage operating range. Furthermore, mutagenesis studies suggest that Val-499 is the primary site responsible for these changes. We also show that V499G/Y501H prestin forms heteromers with wild-type prestin and that the fast motor kinetics of wild-type prestin is not affected by heteromer formation with V499G/Y501H prestin. These results suggest that prestin subunits are individually functional within a given multimer.
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Affiliation(s)
- Kazuaki Homma
- Department of Otolaryngology-Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
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Kamar RI, Organ-Darling LE, Raphael RM. Membrane cholesterol strongly influences confined diffusion of prestin. Biophys J 2012; 103:1627-36. [PMID: 23083705 DOI: 10.1016/j.bpj.2012.07.052] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2011] [Revised: 07/18/2012] [Accepted: 07/25/2012] [Indexed: 01/04/2023] Open
Abstract
Prestin is the membrane motor protein that drives outer hair cell (OHC) electromotility, a process that is essential for mammalian hearing. Prestin function is sensitive to membrane cholesterol levels, and numerous studies have suggested that prestin localizes in cholesterol-rich membrane microdomains. Previously, fluorescence recovery after photobleaching experiments were performed in HEK cells expressing prestin-GFP after cholesterol manipulations, and revealed evidence of transient confinement. To further characterize this apparent confined diffusion of prestin, we conjugated prestin to a photostable fluorophore (tetramethylrhodamine) and performed single-molecule fluorescence microscopy. Using single-particle tracking, we determined the microscopic diffusion coefficient from the full time course of the mean-squared deviation. Our results indicate that prestin undergoes diffusion in confinement regions, and that depletion of membrane cholesterol increases confinement size and decreases confinement strength. By interpreting the data in terms of a mathematical model of hop-diffusion, we quantified these cholesterol-induced changes in membrane organization. A complementary analysis of the distribution of squared displacements confirmed that cholesterol depletion reduces prestin confinement. These findings support the hypothesis that prestin function is intimately linked to membrane organization, and further promote a regulatory role for cholesterol in OHC and auditory function.
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Affiliation(s)
- R I Kamar
- Department of Physics and Astronomy, Rice University, Houston, Texas, USA
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Membrane thickness sensitivity of prestin orthologs: the evolution of a piezoelectric protein. Biophys J 2011; 100:2614-22. [PMID: 21641306 DOI: 10.1016/j.bpj.2011.04.032] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 04/08/2011] [Accepted: 04/14/2011] [Indexed: 01/23/2023] Open
Abstract
How proteins evolve new functionality is an important question in biology; prestin (SLC26A5) is a case in point. Prestin drives outer hair cell somatic motility and amplifies mechanical vibrations in the mammalian cochlea. The motility of mammalian prestin is analogous to piezoelectricity, in which charge transfer is coupled to changes in membrane area occupied by the protein. Intriguingly, nonmammalian prestin orthologs function as anion exchangers but are apparently nonmotile. We previously found that mammalian prestin is sensitive to membrane thickness, suggesting that prestin's extended conformation has a thinner hydrophobic height in the lipid bilayer. Because prestin-based motility is a mammalian specialization, we initially hypothesized that nonmotile prestin orthologs, while functioning as anion transporters, should be much less sensitive to membrane thickness. We found the exact opposite to be true. Chicken prestin was the most sensitive to thickness changes, displaying the largest shift in voltage dependence. Platypus prestin displayed an intermediate response to membrane thickness and gerbil prestin was the least sensitive. To explain these observations, we present a theory where force production, rather than displacement, was selected for the evolution of prestin as a piezoelectric membrane motor.
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