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Iwasa KH. Multiple Modes of Motion for the Effectiveness of Outer Hair Cells at High Frequencies. ARXIV 2024:arXiv:2404.01062v3. [PMID: 38903735 PMCID: PMC11188145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 06/22/2024]
Abstract
Outer hair cells (OHCs) are essential for the sensitivity and frequency specificity of the mammalian ear. To perform this function, OHCs need to amplify the motion of the basilar membrane (BM), which is much stiffer than themselves. If OHCs and the BM are components of a single oscillator, this impedance mismatch seriously limits the effectiveness of OHCs. However, the elaborated structure of the organ of Corti can support multiple modes of motion. Here, systems of two coupled oscillators are examined as the simplest models of the system with multiple modes of motion. It is found that some of these model systems have conditions, under which an OHC can function as an effective amplifier, overcoming the impedance mismatch. The present examination suggests that the presence of multiple modes of motion is a key to the exquisite performance of the mammalian ear.
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Affiliation(s)
- Kuni H Iwasa
- NIDCD, National Institutes of Health Bethesda, MD 20892, USA
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Lutze RD, Ingersoll MA, Kelmann RG, Teitz T. Trametinib, a MEK1/2 Inhibitor, Protects Mice from Cisplatin- and Noise-Induced Hearing Loss. Pharmaceuticals (Basel) 2024; 17:735. [PMID: 38931403 PMCID: PMC11206450 DOI: 10.3390/ph17060735] [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: 05/20/2024] [Revised: 05/30/2024] [Accepted: 06/04/2024] [Indexed: 06/28/2024] Open
Abstract
Hearing loss is one of the most common types of disability; however, there is only one FDA-approved drug to prevent any type of hearing loss. Treatment with the highly effective chemotherapy agent, cisplatin, and exposure to high-decibel noises are two of the most common causes of hearing loss. The mitogen-activated protein kinase (MAPK) pathway, a phosphorylation cascade consisting of RAF, MEK1/2, and ERK1/2, has been implicated in both types of hearing loss. Pharmacologically inhibiting BRAF or ERK1/2 is protective against noise- and cisplatin-induced hearing loss in multiple mouse models. Trametinib, a MEK1/2 inhibitor, protects from cisplatin-induced outer hair cell death in mouse cochlear explants; however, to the best of our knowledge, inhibiting MEK1/2 has not yet been shown to be protective against hearing loss in vivo. In this study, we demonstrate that trametinib protects against cisplatin-induced hearing loss in a translationally relevant mouse model and does not interfere with cisplatin's tumor-killing efficacy in cancer cell lines. Higher doses of trametinib were toxic to mice when combined with cisplatin, but lower doses of the drug were protective against hearing loss without any known toxicity. Trametinib also protected mice from noise-induced hearing loss and synaptic damage. This study shows that MEK1/2 inhibition protects against both insults of hearing loss, as well as that targeting all three kinases in the MAPK pathway protects mice from cisplatin- and noise-induced hearing loss.
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Affiliation(s)
- Richard D. Lutze
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE 68178, USA; (R.D.L.); (M.A.I.); (R.G.K.)
| | - Matthew A. Ingersoll
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE 68178, USA; (R.D.L.); (M.A.I.); (R.G.K.)
| | - Regina G. Kelmann
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE 68178, USA; (R.D.L.); (M.A.I.); (R.G.K.)
| | - Tal Teitz
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE 68178, USA; (R.D.L.); (M.A.I.); (R.G.K.)
- The Scintillon Research Institute, San Diego, CA 92121, USA
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Takahashi S, Zhou Y, Cheatham MA, Homma K. The frequency dependence of prestin-mediated fast electromotility for mammalian cochlear amplification. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.22.595389. [PMID: 38826260 PMCID: PMC11142200 DOI: 10.1101/2024.05.22.595389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Prestin's voltage-driven motor activity confers sound-elicited somatic electromotility in auditory outer hair cells (OHCs) and is essential for the exquisite sensitivity and frequency selectivity of mammalian hearing. Lack of prestin results in hearing threshold shifts across frequency, supporting the causal association of variants in the prestin-coding gene, SLC26A5 , with human hearing loss, DFNB61. However, cochlear function can tolerate reductions in prestin-mediated OHC electromotility. We found that two deafness-associated prestin variants, p.A100T and p.P119S, do not deprive prestin of its fast motor function but significantly reduce membrane expression, leading to large reductions in OHC electromotility that were only ∼30% of wildtype (WT). Mice harboring these missense variants suffered congenital hearing loss that was worse at high frequencies; however, they retained WT-like auditory brainstem response thresholds at 8 kHz, which is processed at the apex of the mouse cochlea. This observation suggests the increasing importance of prestin-driven cochlear amplification at higher frequencies relevant to mammalian hearing. The observation also suggests the promising clinical possibility that small enhancements of OHC electromotility could significantly ameliorate DFNB61 hearing loss in human patients. SIGNIFICANCE Prestin is abundantly expressed in the auditory outer hair cells and is essential for normal cochlear operation. Hence, reduction of prestin expression is often taken as indicative of reduced cochlear function in diseased or aged ears. However, this assumption overlooks the fact that cochlear function can tolerate large reductions in prestin motor activity. DFNB61 mouse models generated and characterized in this study provide an opportunity to gauge the amount of prestin motor activity needed to sustain normal hearing sensitivity. This knowledge is crucial not only for understanding the pathogenic roles of deafness-associated variants that impair OHC electromotility but also for unraveling how prestin contributes to cochlear amplification.
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Lutze RD, Ingersoll MA, Kelmann RG, Teitz T. FDA-Approved MEK1/2 Inhibitor, Trametinib, Protects Mice from Cisplatin and Noise-Induced Hearing Loss. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.20.595056. [PMID: 38826449 PMCID: PMC11142120 DOI: 10.1101/2024.05.20.595056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
Hearing loss is one of the most common types of disability; however, there is only one FDA-approved drug to prevent any type of hearing loss. Treatment with the highly effective chemotherapy agent, cisplatin, and exposure to high decibel noises are two of the most common causes of hearing loss. The mitogen activated protein kinase (MAPK) pathway, a phosphorylation cascade consisting of RAF, MEK1/2, and ERK1/2, has been implicated in both types of hearing loss. Pharmacologically inhibiting BRAF or ERK1/2 is protective from noise and cisplatin-induced hearing loss in multiple mouse models. Trametinib, a MEK1/2 inhibitor, protects from cisplatin induced outer hair cell death in mouse cochlear explants; however, to the best of our knowledge, inhibiting MEK1/2 has not yet been shown to be protective from hearing loss in vivo. In this study, we demonstrate that trametinib protects from cisplatin-induced hearing loss in a translationally relevant mouse model and does not interfere with cisplatin's tumor killing efficacy in cancer cell lines. Higher doses of trametinib were toxic to mice when combined with cisplatin but lower doses of the drug were protective from hearing loss without any known toxicity. Trametinib also protected mice from noise-induced hearing loss and synaptic damage. This study shows that MEK1/2 inhibition protects from both insults of hearing loss and that targeting all three kinases in the MAPK pathway protect from cisplatin and noise-induced hearing loss in mice.
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Affiliation(s)
- Richard D. Lutze
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE 68178, USA
| | - Matthew A. Ingersoll
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE 68178, USA
| | - Regina G. Kelmann
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE 68178, USA
| | - Tal Teitz
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE 68178, USA
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Sailor-Longsworth E, Lutze RD, Ingersoll MA, Kelmann RG, Ly K, Currier D, Chen T, Zuo J, Teitz T. Oseltamivir (Tamiflu), a Commonly Prescribed Antiviral Drug, Mitigates Hearing Loss in Mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.06.592815. [PMID: 38765999 PMCID: PMC11100672 DOI: 10.1101/2024.05.06.592815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Hearing loss affects up to 10% of all people worldwide, but currently there is only one FDA-approved drug for its prevention in a subgroup of cisplatin-treated pediatric patients. Here, we performed an unbiased screen of 1,300 FDA-approved drugs for protection against cisplatin-induced cell death in an inner ear cell line, and identified oseltamivir phosphate (brand name Tamiflu), a common influenza antiviral drug, as a top candidate. Oseltamivir phosphate was found to be otoprotective by oral delivery in multiple established cisplatin and noise exposure mouse models. The drug conferred permanent hearing protection of 15-25 dB SPL for both female and male mice. Oseltamivir treatment reduced in mice outer hair cells death after cisplatin treatment and mitigated cochlear synaptopathy after noise exposure. A potential binding protein, ERK1/2, associated with inflammation, was shown to be activated with cisplatin treatment and reduced by oseltamivir cotreatment in cochlear explants. Importantly, the number of infiltrating immune cells to the cochleae in mice post noise exposure, were significantly reduced with oseltamivir treatment, suggesting an anti-inflammatory mechanism of action. Our results support oseltamivir, a widespread drug for influenza with low side effects, as a promising otoprotective therapeutic candidate in both cisplatin chemotherapy and traumatic noise exposure.
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Affiliation(s)
- Emma Sailor-Longsworth
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE 68178, USA
| | - Richard D. Lutze
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE 68178, USA
| | - Matthew A. Ingersoll
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE 68178, USA
| | - Regina G. Kelmann
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE 68178, USA
| | - Kristina Ly
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE 68178, USA
| | - Duane Currier
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN, 38105, USA
| | - Taosheng Chen
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN, 38105, USA
| | - Jian Zuo
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE 68178, USA
| | - Tal Teitz
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE 68178, USA
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Takahashi S, Zhou Y, Cheatham MA, Homma K. The pathogenic roles of the p.R130S prestin variant in DFNB61 hearing loss. J Physiol 2024; 602:1199-1210. [PMID: 38431907 PMCID: PMC10942758 DOI: 10.1113/jp285599] [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: 08/31/2023] [Accepted: 02/05/2024] [Indexed: 03/05/2024] Open
Abstract
DFNB61 is a recessively inherited nonsyndromic hearing loss caused by mutations in SLC26A5, the gene that encodes the voltage-driven motor protein, prestin. Prestin is abundantly expressed in the auditory outer hair cells that mediate cochlear amplification. Two DFNB61-associated SLC26A5 variants, p.W70X and p.R130S, were identified in patients who are compound heterozygous for these nonsense and missense changes (SLC26A5W70X/R130S ). Our recent study showed that mice homozygous for p.R130S (Slc26a5R130S/R130S ) suffer from hearing loss that is ascribed to significantly reduced motor kinetics of prestin. Given that W70X-prestin is nonfunctional, compound heterozygous Slc26a5R130S/- mice were used as a model for human SLC26A5W70X/R130S . By examining the pathophysiological consequences of p.R130S prestin when it is the sole allele for prestin protein production, we determined that this missense change results in progressive outer hair cell loss in addition to its effects on prestin's motor action. Thus, this study defines the pathogenic roles of p.R130S prestin and identifies a limited time window for potential clinical intervention. KEY POINTS: The voltage-driven motor protein, prestin, is encoded by SLC26A5 and expressed abundantly in cochlear outer hair cells (OHCs). The importance of prestin for normal hearing was demonstrated in mice lacking prestin; however, none of the specific SLC26A5 variants identified to date in human patients has been experimentally demonstrated to be pathogenic. In this study we used both cell lines and a mouse model to define the pathogenic role of compound heterozygous p.W70X (c.209G>A) and p.R130S (c.390A>C) SLC26A5 variants identified in patients with moderate to profound hearing loss. As in patients, mice carrying one copy of p.R130S Slc26a5 showed OHC dysfunction and progressive degeneration, which results in congenital progressive hearing loss. This is the first functional study reporting pathogenic SLC26A5 variants and pointing to the presence of a therapeutic time window for potential clinical interventions targeting the affected OHCs before they are lost.
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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
| | - Yingjie Zhou
- 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
- The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders
| | - 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
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Ingersoll MA, Lutze RD, Pushpan CK, Kelmann RG, Liu H, May MT, Hunter WJ, He DZ, Teitz T. Dabrafenib protects from cisplatin-induced hearing loss in a clinically relevant mouse model. JCI Insight 2023; 8:e171140. [PMID: 37934596 PMCID: PMC10807719 DOI: 10.1172/jci.insight.171140] [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: 04/03/2023] [Accepted: 11/02/2023] [Indexed: 11/09/2023] Open
Abstract
The widely used chemotherapy cisplatin causes permanent hearing loss in 40%-60% of patients with cancer. One drug, sodium thiosulfate, is approved by the FDA for use in pediatric patients with localized solid tumors for preventing cisplatin-induced hearing loss, but more drugs are desperately needed. Here, we tested dabrafenib, an FDA-approved BRAF kinase inhibitor and anticancer drug, in a clinically relevant multidose cisplatin mouse model. The protective effects of dabrafenib, given orally twice daily with cisplatin, were determined by functional hearing tests and cochlear outer hair cell counts. Toxicity of the drug cotreatment was evaluated, and levels of phosphorylated ERK were measured. A dabrafenib dose of 3 mg/kg BW, twice daily, in mice, was determined to be the minimum effective dose, and it is equivalent to one-tenth of the daily FDA-approved dose for human cancer treatment. The levels of hearing protection acquired, 20-25 dB at the 3 frequencies tested, in both female and male mice, persisted for 4 months after completion of treatments. Moreover, dabrafenib exhibited a good in vivo therapeutic index (> 25), protected hearing in 2 mouse strains, and diminished cisplatin-induced weight loss. This study demonstrates that dabrafenib is a promising candidate drug for protection from cisplatin-induced hearing loss.
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Affiliation(s)
| | | | | | | | | | | | - William J. Hunter
- Department of Pathology, School of Medicine, Creighton University, Omaha, Nebraska, USA
| | | | - Tal Teitz
- Department of Pharmacology and Neuroscience
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Takahashi S, Zhou Y, Cheatham MA, Homma K. The pathogenic roles of the p.R130S prestin variant in DFNB61 hearing loss. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.21.554157. [PMID: 37662362 PMCID: PMC10473669 DOI: 10.1101/2023.08.21.554157] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
DFNB61 is a recessively inherited nonsyndromic hearing loss caused by mutations in SLC26A5 , the gene that encodes the voltage-driven motor protein, prestin. Prestin is abundantly expressed in the auditory outer hair cells that mediate cochlear amplification. Two DFNB61-associated SLC26A5 variants, p.W70X and p.R130S, were identified in patients who are compound heterozygous for these nonsense and missense changes ( SLC26A5 W70X/R130S ). Our recent study showed that mice homozygous for p.R130S ( Slc26a5 R130S/R130S ) suffer from hearing loss that is ascribed to significantly reduced motor kinetics of prestin. Given that W70X-prestin is nonfunctional, compound heterozygous Slc26a5 R130S/- mice were used as a model for human SLC26A5 W70X/R130S . By examining the pathophysiological consequences of p.R130S prestin when it is the sole allele for prestin protein production, we determined that this missense change results in progressive outer hair cell loss in addition to its effects on prestin's motor action. Thus, this study fully defines the pathogenic roles for the p.R130S prestin, which points to the presence of a limited time window for potential clinical intervention.
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Takahashi S, Zhou Y, Kojima T, Cheatham MA, Homma K. Prestin's fast motor kinetics is essential for mammalian cochlear amplification. Proc Natl Acad Sci U S A 2023; 120:e2217891120. [PMID: 36893263 PMCID: PMC10089206 DOI: 10.1073/pnas.2217891120] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 02/06/2023] [Indexed: 03/11/2023] Open
Abstract
Prestin (SLC26A5)-mediated voltage-driven elongations and contractions of sensory outer hair cells within the organ of Corti are essential for mammalian cochlear amplification. However, whether this electromotile activity directly contributes on a cycle-by-cycle basis is currently controversial. By restoring motor kinetics in a mouse model expressing a slowed prestin missense variant, this study provides experimental evidence acknowledging the importance of fast motor action to mammalian cochlear amplification. Our results also demonstrate that the point mutation in prestin disrupting anion transport in other proteins of the SLC26 family does not alter cochlear function, suggesting that the potential weak anion transport of prestin is not essential in the mammalian cochlea.
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Affiliation(s)
- Satoe Takahashi
- Department of Otolaryngology–Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL60611
| | - Yingjie Zhou
- Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL60208
| | - Takashi Kojima
- Department of Otolaryngology–Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL60611
| | - Mary Ann Cheatham
- Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL60208
- The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University, Evanston, IL60208
| | - Kazuaki Homma
- Department of Otolaryngology–Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL60611
- The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University, Evanston, IL60208
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Homma K, Takahashi S, Cheatham MA. How much prestin motor activity is required for normal hearing? Hear Res 2022; 423:108376. [PMID: 34848118 PMCID: PMC9091054 DOI: 10.1016/j.heares.2021.108376] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 10/07/2021] [Accepted: 10/13/2021] [Indexed: 12/20/2022]
Abstract
Prestin (SLC26A5) is a membrane-based voltage-dependent motor protein responsible for outer hair cell (OHC) somatic electromotility. Its importance for mammalian cochlear amplification has been demonstrated using mouse models lacking prestin (prestin-KO) and expressing dysfunctional prestin, prestinV499G/Y501H (499-prestin-KI). However, it is still not elucidated how prestin contributes to the mechanical amplification process in the cochlea. In this study, we characterized several prestin mouse models in which prestin activity in OHCs was variously manipulated. We found that near-normal cochlear function can be maintained even when prestin activity is significantly reduced, suggesting that the relationship between OHC electromotility and the peripheral sensitivity to sound may not be linear. This result is counterintuitive given the large threshold shifts in prestin-KO and 499-prestin-KI mice, as reported in previous studies. To reconcile these apparently opposing observations, we entertain a voltage- and turgor pressure-based cochlear amplification mechanism that requires prestin but is insensitive to significant reductions in prestin protein expression. 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)
- 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 60208, USA.
| | - Satoe Takahashi
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Mary Ann Cheatham
- The Hugh Knowles Center for Clinical and Basic Science in Hearing and Its Disorders, Northwestern University, Evanston, IL 60208, USA; Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL 60208, USA.
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Sun Y, Zhang Y, Zhang D, Wang G, Song L, Liu Z. In vivo CRISPR-Cas9-mediated DNA chop identifies a cochlear outer hair cell-specific enhancer. FASEB J 2022; 36:e22233. [PMID: 35225354 DOI: 10.1096/fj.202100421rr] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 02/06/2022] [Accepted: 02/14/2022] [Indexed: 01/18/2023]
Abstract
Cochlear outer hair cells (OHCs) are essential for hearing. A short, OHC-specific enhancer is necessary but not yet available for gene therapeutic applications in OHC damage. Such damage is a major cause of deafness. Prestin is a motor protein exclusively expressed in OHCs. We hypothesized that the cis-regulatory DNA fragment deletion of Slc26a5 would affect its expression. We tested this hypothesis by conducting CRISPR/Cas9-mediated large DNA fragment deletion of mouse Slc26a5 intron regions. First, starting from a ~13 kbp fragment, step-by-step, we narrowed down the sequence to a 1.4 kbp segment. By deleting either a 13 kbp or 1.4 kbp fragment, we observed delayed Prestin expression. Second, we showed that 1.4 kbp was an OHC-specific enhancer because enhanced green fluorescent protein (EGFP) was highly and specifically expressed in OHCs in a transgenic mouse where EGFP was driven by the 1.4 kbp segment. More importantly, specific EGFP was also driven by its homologous 398 bp fragment in human Slc26a5. This suggests that the enhancer is likely to be evolutionarily conserved across different species.
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Affiliation(s)
- Yuwei Sun
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yu Zhang
- Department of Otolaryngology-Head and Neck Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Di Zhang
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Guangqin Wang
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Lei Song
- Department of Otolaryngology-Head and Neck Surgery, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.,Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zhiyong Liu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China.,Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai, China
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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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Ingersoll MA, Malloy EA, Caster LE, Holland EM, Xu Z, Zallocchi M, Currier D, Liu H, He DZZ, Min J, Chen T, Zuo J, Teitz T. BRAF inhibition protects against hearing loss in mice. SCIENCE ADVANCES 2020; 6:6/49/eabd0561. [PMID: 33268358 PMCID: PMC7821884 DOI: 10.1126/sciadv.abd0561] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 10/20/2020] [Indexed: 05/13/2023]
Abstract
Hearing loss caused by noise, aging, antibiotics, and chemotherapy affects 10% of the world population, yet there are no Food and Drug Administration (FDA)-approved drugs to prevent it. Here, we screened 162 small-molecule kinase-specific inhibitors for reduction of cisplatin toxicity in an inner ear cell line and identified dabrafenib (TAFINLAR), a BRAF kinase inhibitor FDA-approved for cancer treatment. Dabrafenib and six additional kinase inhibitors in the BRAF/MEK/ERK cellular pathway mitigated cisplatin-induced hair cell death in the cell line and mouse cochlear explants. In adult mice, oral delivery of dabrafenib repressed ERK phosphorylation in cochlear cells, and protected from cisplatin- and noise-induced hearing loss. Full protection was achieved in mice with co-treatment with oral AZD5438, a CDK2 kinase inhibitor. Our study explores a previously unidentified cellular pathway and molecular target BRAF kinase for otoprotection and may advance dabrafenib into clinics to benefit patients with cisplatin- and noise-induced ototoxicity.
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Affiliation(s)
- Matthew A Ingersoll
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE 68178, USA
| | - Emma A Malloy
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE 68178, USA
| | - Lauryn E Caster
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE 68178, USA
| | - Eva M Holland
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE 68178, USA
| | - Zhenhang Xu
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE 68178, USA
- Department of Otolaryngology, Xiangya Hospital, Central South University, Changsha 410008, China
| | - Marisa Zallocchi
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE 68178, USA
| | - Duane Currier
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Huizhan Liu
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE 68178, USA
| | - David Z Z He
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE 68178, USA
| | - Jaeki Min
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Taosheng Chen
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Jian Zuo
- Department of Biomedical Sciences, School of Medicine, Creighton University, Omaha, NE 68178, USA
| | - Tal Teitz
- Department of Pharmacology and Neuroscience, School of Medicine, Creighton University, Omaha, NE 68178, USA.
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14
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Takahashi S, Yamashita T, Homma K, Zhou Y, Zuo J, Zheng J, Cheatham MA. Deletion of exons 17 and 18 in prestin's STAS domain results in loss of function. Sci Rep 2019; 9:6874. [PMID: 31053797 PMCID: PMC6499820 DOI: 10.1038/s41598-019-43343-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 04/23/2019] [Indexed: 12/03/2022] Open
Abstract
Cochlear outer hair cells (OHC) express the motor protein, prestin, which is required for sensitivity and frequency selectivity. Because our previous work showed that a calmodulin binding site (CBS) was located in prestin's C-terminal, specifically within the intrinsically disordered region, we sought to delete the IDR to study the functional significance of calcium-dependent, calmodulin binding on OHC function. Although the construct lacking the IDR (∆IDR prestin) demonstrated wildtype-like nonlinear capacitance (NLC) in HEK293T cells, the phenotype in ∆IDR prestin knockins (KI) was similar to that in prestin knockouts: thresholds were elevated, NLC was absent and OHCs were missing from basal regions of the cochlea. Although ∆IDR prestin mRNA was measured, no prestin protein was detected. At the mRNA level, both of prestin's exons 17 and 18 were entirely removed, rather than the smaller region encoding the IDR. Our hybrid exon that contained the targeted deletion (17-18 ∆IDR) failed to splice in vitro and prestin protein lacking exons 17 and 18 aggregated and failed to target the cell membrane. Hence, the absence of prestin protein in ∆IDR KI OHCs may be due to the unexpected splicing of the hybrid 17-18 ∆IDR exon followed by rapid degradation of nonfunctional prestin protein.
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Affiliation(s)
- Satoe Takahashi
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Tetsuji Yamashita
- St. Jude Children's Research Hospital, Department of Developmental Neurobiology, Memphis, TN, USA
| | - Kazuaki Homma
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Knowles Hearing Center, Northwestern University, Evanston, IL, USA
| | - Yingjie Zhou
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL, USA
| | - Jian Zuo
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, USA
| | - Jing Zheng
- Department of Otolaryngology - Head and Neck Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Knowles Hearing Center, Northwestern University, Evanston, IL, USA
| | - Mary Ann Cheatham
- Knowles Hearing Center, Northwestern University, Evanston, IL, USA.
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL, USA.
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15
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Santos-Sacchi J, Tan W. The Frequency Response of Outer Hair Cell Voltage-Dependent Motility Is Limited by Kinetics of Prestin. J Neurosci 2018; 38:5495-5506. [PMID: 29899032 PMCID: PMC6001036 DOI: 10.1523/jneurosci.0425-18.2018] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 05/14/2018] [Accepted: 05/16/2018] [Indexed: 01/07/2023] Open
Abstract
The voltage-dependent protein SLC26a5 (prestin) underlies outer hair cell electromotility (eM), which is responsible for cochlear amplification in mammals. The electrical signature of eM is a bell-shaped nonlinear capacitance (NLC), deriving from prestin sensor-charge (Qp) movements, which peaks at the membrane voltage, Vh, where charge is distributed equally on either side of the membrane. Voltage dependencies of NLC and eM differ depending on interrogation frequency and intracellular chloride, revealing slow intermediate conformational transitions between anion binding and voltage-driven Qp movements. Consequently, NLC exhibits low-pass characteristics, substantially below prevailing estimates of eM frequency response. Here we study in guinea pig and mouse of either sex synchronous prestin electrical (NLC, Qp) and mechanical (eM) activity across frequencies under voltage clamp (whole cell and microchamber). We find that eM and Qp magnitude and phase correspond, indicating tight piezoelectric coupling. Electromechanical measures (both NLC and eM) show dual-Lorentzian, low-pass behavior, with a limiting (τ2) time constant at Vh of 32.6 and 24.8 μs, respectively. As expected for voltage-dependent kinetics, voltage excitation away from Vh has a faster, flatter frequency response, with our fastest measured τ2 for eM of 18.2 μs. Previous observations of ultrafast eM (τ ≈ 2 μs) were obtained at offsets far removed from Vh We hypothesize that trade-offs in eM gain-bandwith arising from voltage excitation at membrane potentials offset from Vh influence the effectiveness of cochlear amplification across frequencies.SIGNIFICANCE STATEMENT Of two types of hair cells within the organ of Corti, inner hair cells and outer hair cells, the latter evolved to boost sensitivity to sounds. Damage results in hearing loss of 40-60 dB, revealing amplification gains of 100-1000× that arise from voltage-dependent mechanical responses [electromotility (eM)]. eM, driven by the membrane protein prestin, may work beyond 70 kHz. However, this speed exceeds, by over an order of magnitude, kinetics of typical voltage-dependent membrane proteins. We find eM is actually low pass in nature, indicating that prestin bears kinetics typical of other membrane proteins. These observations highlight potential difficulties in providing sufficient amplification beyond a cutoff frequency near 20 kHz. Nevertheless, observed trade-offs in eM gain-bandwith may sustain cochlear amplification across frequency.
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Affiliation(s)
- Joseph Santos-Sacchi
- Department of Surgery (Otolaryngology),
- Department of Neuroscience, and
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06510
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16
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Teitz T, Fang J, Goktug AN, Bonga JD, Diao S, Hazlitt RA, Iconaru L, Morfouace M, Currier D, Zhou Y, Umans RA, Taylor MR, Cheng C, Min J, Freeman B, Peng J, Roussel MF, Kriwacki R, Guy RK, Chen T, Zuo J. CDK2 inhibitors as candidate therapeutics for cisplatin- and noise-induced hearing loss. J Exp Med 2018. [PMID: 29514916 PMCID: PMC5881471 DOI: 10.1084/jem.20172246] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Hearing loss caused by aging, noise, cisplatin toxicity, or other insults affects 360 million people worldwide, but there are no Food and Drug Administration-approved drugs to prevent or treat it. We screened 4,385 small molecules in a cochlear cell line and identified 10 compounds that protected against cisplatin toxicity in mouse cochlear explants. Among them, kenpaullone, an inhibitor of multiple kinases, including cyclin-dependent kinase 2 (CDK2), protected zebrafish lateral-line neuromasts from cisplatin toxicity and, when delivered locally, protected adult mice and rats against cisplatin- and noise-induced hearing loss. CDK2-deficient mice displayed enhanced resistance to cisplatin toxicity in cochlear explants and to cisplatin- and noise-induced hearing loss in vivo. Mechanistically, we showed that kenpaullone directly inhibits CDK2 kinase activity and reduces cisplatin-induced mitochondrial production of reactive oxygen species, thereby enhancing cell survival. Our experiments have revealed the proapoptotic function of CDK2 in postmitotic cochlear cells and have identified promising therapeutics for preventing hearing loss.
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Affiliation(s)
- Tal Teitz
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN
| | - Jie Fang
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN
| | - Asli N Goktug
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN
| | - Justine D Bonga
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN
| | - Shiyong Diao
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN
| | - Robert A Hazlitt
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN
| | - Luigi Iconaru
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN.,Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN
| | - Marie Morfouace
- Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, TN
| | - Duane Currier
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN
| | - Yinmei Zhou
- Department of Biostatistics, St. Jude Children's Research Hospital, Memphis, TN
| | - Robyn A Umans
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN
| | - Michael R Taylor
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN
| | - Cheng Cheng
- Department of Biostatistics, St. Jude Children's Research Hospital, Memphis, TN
| | - Jaeki Min
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN
| | - Burgess Freeman
- Preclinical PK Shared Resource, St. Jude Children's Research Hospital, Memphis, TN
| | - Junmin Peng
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN.,Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN
| | - Martine F Roussel
- Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, TN
| | - Richard Kriwacki
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN
| | - R Kiplin Guy
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN
| | - Taosheng Chen
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, TN
| | - Jian Zuo
- Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN
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17
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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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18
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Prestin-Dependence of Outer Hair Cell Survival and Partial Rescue of Outer Hair Cell Loss in PrestinV499G/Y501H Knockin Mice. PLoS One 2015; 10:e0145428. [PMID: 26682723 PMCID: PMC4684303 DOI: 10.1371/journal.pone.0145428] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 10/23/2015] [Indexed: 12/23/2022] Open
Abstract
A knockin (KI) mouse expressing mutated prestinV499G/Y501H (499 prestin) was created to study cochlear amplification. Recordings from isolated outer hair cells (OHC) in this mutant showed vastly reduced electromotility and, as a consequence, reduced hearing sensitivity. Although 499 prestin OHCs were normal in stiffness and longer than OHCs lacking prestin, accelerated OHC death was unexpectedly observed relative to that documented in prestin knockout (KO) mice. These observations imply an additional role of prestin in OHC maintenance besides its known requirement for mammalian cochlear amplification. In order to gain mechanistic insights into prestin-associated OHC loss, we implemented several interventions to improve survival. First, 499 prestin KI’s were backcrossed to Bak KO mice, which lack the mitochondrial pro-apoptotic gene Bak. Because oxidative stress is implicated in OHC death, another group of 499 prestin KI mice was fed the antioxidant diet, Protandim. 499 KI mice were also backcrossed onto the FVB murine strain, which retains excellent high-frequency hearing well into adulthood, to reduce the compounding effect of age-related hearing loss associated with the original 499 prestin KIs. Finally, a compound heterozygous (chet) mouse expressing one copy of 499 prestin and one copy of KO prestin was also created to reduce quantities of 499 prestin protein. Results show reduction in OHC death in chets, and in 499 prestin KIs on the FVB background, but only a slight improvement in OHC survival for mice receiving Protandim. We also report that improved OHC survival in 499 prestin KIs had little effect on hearing phenotype, reaffirming the original contention about the essential role of prestin’s motor function in cochlear amplification.
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19
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Yamashita T, Hakizimana P, Wu S, Hassan A, Jacob S, Temirov J, Fang J, Mellado-Lagarde M, Gursky R, Horner L, Leibiger B, Leijon S, Centonze VE, Berggren PO, Frase S, Auer M, Brownell WE, Fridberger A, Zuo J. Outer Hair Cell Lateral Wall Structure Constrains the Mobility of Plasma Membrane Proteins. PLoS Genet 2015; 11:e1005500. [PMID: 26352669 PMCID: PMC4564264 DOI: 10.1371/journal.pgen.1005500] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 08/14/2015] [Indexed: 12/02/2022] Open
Abstract
Nature’s fastest motors are the cochlear outer hair cells (OHCs). These sensory cells use a membrane protein, Slc26a5 (prestin), to generate mechanical force at high frequencies, which is essential for explaining the exquisite hearing sensitivity of mammalian ears. Previous studies suggest that Slc26a5 continuously diffuses within the membrane, but how can a freely moving motor protein effectively convey forces critical for hearing? To provide direct evidence in OHCs for freely moving Slc26a5 molecules, we created a knockin mouse where Slc26a5 is fused with YFP. These mice and four other strains expressing fluorescently labeled membrane proteins were used to examine their lateral diffusion in the OHC lateral wall. All five proteins showed minimal diffusion, but did move after pharmacological disruption of membrane-associated structures with a cholesterol-depleting agent and salicylate. Thus, our results demonstrate that OHC lateral wall structure constrains the mobility of plasma membrane proteins and that the integrity of such membrane-associated structures are critical for Slc26a5’s active and structural roles. The structural constraint of membrane proteins may exemplify convergent evolution of cellular motors across species. Our findings also suggest a possible mechanism for disorders of cholesterol metabolism with hearing loss such as Niemann-Pick Type C diseases. Nature’s fastest motor is the cochlear outer hair cell (OHC) in the mammalian inner ear. These cells can contract and elongate thousands of times per second. Slc26a5 (prestin) is the essential protein in the fast motor and resides in the plasma membrane of OHC lateral wall. Slc26a5 undergoes voltage-dependent conformational changes associated with the rapid changes in cell length to increase mammalian hearing sensitivity. However, it remains unclear how Slc26a5 transfers the force created to the entire cell. In this study, we show the importance of association between Slc26a5 and specialized membrane structures of the OHC lateral wall. Mobility of Slc26a5 was normally constrained in membrane-associated structures and disruption of these structures by a cholesterol depleting reagent and salicylate liberated Slc26a5 and four other heterologously expressed membrane proteins. These observations provide evidence that OHC lateral wall structure constrains the mobility of plasma membrane proteins and such membrane-associated structures are critical for Slc26a5’s functional roles. Our findings also shed light on other cellular motors across species and suggest a mechanism for cholesterol metabolic disorders in humans.
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Affiliation(s)
- Tetsuji Yamashita
- Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Pierre Hakizimana
- Department of Clinical and Experimental Medicine, Neuroscience, Linköping University, Linköping, Sweden
- Karolinska Institutet, Center for Hearing and Communication Research, Department of Clinical Science, Intervention, and Technology, M1, Karolinska University Hospital, Stockholm, Sweden
| | - Siva Wu
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Ahmed Hassan
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - Stefan Jacob
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Jamshid Temirov
- Cell and Tissue Imaging Facility, St Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Jie Fang
- Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Marcia Mellado-Lagarde
- Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Brighton, United Kingdom
| | - Richard Gursky
- Cell and Tissue Imaging Facility, St Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Linda Horner
- Cell and Tissue Imaging Facility, St Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Barbara Leibiger
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Sara Leijon
- Karolinska Institutet, Center for Hearing and Communication Research, Department of Clinical Science, Intervention, and Technology, M1, Karolinska University Hospital, Stockholm, Sweden
| | - Victoria E. Centonze
- Cell and Tissue Imaging Facility, St Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Per-Olof Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Sharon Frase
- Cell and Tissue Imaging Facility, St Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
| | - Manfred Auer
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
| | - William E. Brownell
- Bobby R. Alford Department of Otolaryngology, Head & Neck Surgery, and Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
| | - Anders Fridberger
- Department of Clinical and Experimental Medicine, Neuroscience, Linköping University, Linköping, Sweden
- Karolinska Institutet, Center for Hearing and Communication Research, Department of Clinical Science, Intervention, and Technology, M1, Karolinska University Hospital, Stockholm, Sweden
| | - Jian Zuo
- Department of Developmental Neurobiology, St. Jude Children’s Research Hospital, Memphis, Tennessee, United States of America
- * E-mail:
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20
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Cai Q, Wang B, Coling D, Zuo J, Fang J, Yang S, Vera K, Hu BH. Reduction in noise-induced functional loss of the cochleae in mice with pre-existing cochlear dysfunction due to genetic interference of prestin. PLoS One 2014; 9:e113990. [PMID: 25486270 PMCID: PMC4259315 DOI: 10.1371/journal.pone.0113990] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 11/02/2014] [Indexed: 11/18/2022] Open
Abstract
Various cochlear pathologies, such as acoustic trauma, ototoxicity and age-related degeneration, cause hearing loss. These pre-existing hearing losses can alter cochlear responses to subsequent acoustic overstimulation. So far, the knowledge on the impacts of pre-existing hearing loss caused by genetic alteration of cochlear genes is limited. Prestin is the motor protein expressed exclusively in outer hair cells in the mammalian cochlea. This motor protein contributes to outer hair cell motility. At present, it is not clear how the interference of prestin function affects cochlear responses to acoustic overstimulation. To address this question, a genetic model of prestin dysfunction in mice was created by inserting an internal ribosome entry site (IRES)-CreERT2-FRT-Neo-FRT cassette into the prestin locus after the stop codon. Homozygous mice exhibit a threshold elevation of auditory brainstem responses with large individual variation. These mice also display a threshold elevation and a shift of the input/output function of the distortion product otoacoustic emission, suggesting a reduction in outer hair cell function. The disruption of prestin function reduces the threshold shifts caused by exposure to a loud noise at 120 dB (sound pressure level) for 1 h. This reduction is positively correlated with the level of pre-noise cochlear dysfunction and is accompanied by a reduced change in Cdh1 expression, suggesting a reduction in molecular responses to the acoustic overstimulation. Together, these results suggest that prestin interference reduces cochlear stress responses to acoustic overstimulation.
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Affiliation(s)
- Qunfeng Cai
- Center for Hearing and Deafness, University at Buffalo, Buffalo, New York, United States of America
| | - Bo Wang
- Department of Otolaryngology and Head & Neck Surgery, Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, China
| | - Donald Coling
- Center for Hearing and Deafness, University at Buffalo, Buffalo, New York, United States of America
| | - Jian Zuo
- Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America
| | - Jie Fang
- Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, United States of America
| | - Shiming Yang
- Department of Otolaryngology and Head & Neck Surgery, Institute of Otolaryngology, Chinese PLA General Hospital, Beijing, China
| | - Krystal Vera
- Center for Hearing and Deafness, University at Buffalo, Buffalo, New York, United States of America
| | - Bo Hua Hu
- Center for Hearing and Deafness, University at Buffalo, Buffalo, New York, United States of America
- * E-mail:
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21
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Xia A, Song Y, Wang R, Gao SS, Clifton W, Raphael P, Chao SI, Pereira FA, Groves AK, Oghalai JS. Prestin regulation and function in residual outer hair cells after noise-induced hearing loss. PLoS One 2013; 8:e82602. [PMID: 24376553 PMCID: PMC3869702 DOI: 10.1371/journal.pone.0082602] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 10/25/2013] [Indexed: 12/27/2022] Open
Abstract
The outer hair cell (OHC) motor protein prestin is necessary for electromotility, which drives cochlear amplification and produces exquisitely sharp frequency tuning. TectaC1509G transgenic mice have hearing loss, and surprisingly have increased OHC prestin levels. We hypothesized, therefore, that prestin up-regulation may represent a generalized response to compensate for a state of hearing loss. In the present study, we sought to determine the effects of noise-induced hearing loss on prestin expression. After noise exposure, we performed cytocochleograms and observed OHC loss only in the basal region of the cochlea. Next, we patch clamped OHCs from the apical turn (9–12 kHz region), where no OHCs were lost, in noise-exposed and age-matched control mice. The non-linear capacitance was significantly higher in noise-exposed mice, consistent with higher functional prestin levels. We then measured prestin protein and mRNA levels in whole-cochlea specimens. Both Western blot and qPCR studies demonstrated increased prestin expression after noise exposure. Finally, we examined the effect of the prestin increase in vivo following noise damage. Immediately after noise exposure, ABR and DPOAE thresholds were elevated by 30–40 dB. While most of the temporary threshold shifts recovered within 3 days, there were additional improvements over the next month. However, DPOAE magnitudes, basilar membrane vibration, and CAP tuning curve measurements from the 9–12 kHz cochlear region demonstrated no differences between noise-exposed mice and control mice. Taken together, these data indicate that prestin is up-regulated by 32–58% in residual OHCs after noise exposure and that the prestin is functional. These findings are consistent with the notion that prestin increases in an attempt to partially compensate for reduced force production because of missing OHCs. However, in regions where there is no OHC loss, the cochlea is able to compensate for the excess prestin in order to maintain stable auditory thresholds and frequency discrimination.
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MESH Headings
- Animals
- Cochlear Microphonic Potentials
- Evoked Potentials, Auditory, Brain Stem
- Gene Expression Regulation
- Hair Cells, Auditory, Outer/metabolism
- Hair Cells, Auditory, Outer/pathology
- Hearing Loss, Noise-Induced/metabolism
- Hearing Loss, Noise-Induced/pathology
- Hearing Loss, Noise-Induced/physiopathology
- Mice
- Models, Biological
- Molecular Motor Proteins/genetics
- Molecular Motor Proteins/metabolism
- Noise
- Otoacoustic Emissions, Spontaneous
- Patch-Clamp Techniques
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
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Affiliation(s)
- Anping Xia
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Yohan Song
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Rosalie Wang
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Simon S. Gao
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
- Department of Bioengineering, Rice University, Houston, Texas, United States of America
| | - Will Clifton
- Bobby R. Alford Department of Otolaryngology – Head and Neck Surgery, Baylor College of Medicine, Houston, Texas, United States of America
| | - Patrick Raphael
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
| | - Sung-il Chao
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
- Department of Otolaryngology–Head and Neck Surgery, Chosun University, Gwangju, South Korea
| | - Fred A. Pereira
- Bobby R. Alford Department of Otolaryngology – Head and Neck Surgery, Baylor College of Medicine, Houston, Texas, United States of America
| | - Andrew K. Groves
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas, United States of America
| | - John S. Oghalai
- Department of Otolaryngology–Head and Neck Surgery, Stanford University, Stanford, California, United States of America
- * E-mail:
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22
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Cimerman J, Waldhaus J, Harasztosi C, Duncker SV, Dettling J, Heidrych P, Bress A, Gampe-Braig C, Frank G, Gummer AW, Oliver D, Knipper M, Zimmermann U. Generation of somatic electromechanical force by outer hair cells may be influenced by prestin-CASK interaction at the basal junction with the Deiter's cell. Histochem Cell Biol 2013; 140:119-35. [PMID: 23542924 DOI: 10.1007/s00418-013-1085-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/08/2013] [Indexed: 01/06/2023]
Abstract
The motor protein, prestin, situated in the basolateral plasma membrane of cochlear outer hair cells (OHCs), underlies the generation of somatic, voltage-driven mechanical force, the basis for the exquisite sensitivity, frequency selectivity and dynamic range of mammalian hearing. The molecular and structural basis of the ontogenetic development of this electromechanical force has remained elusive. The present study demonstrates that this force is significantly reduced when the immature subcellular distribution of prestin found along the entire plasma membrane persists into maturity, as has been described in previous studies under hypothyroidism. This observation suggests that cochlear amplification is critically dependent on the surface expression and distribution of prestin. Searching for proteins involved in organizing the subcellular localization of prestin to the basolateral plasma membrane, we identified cochlear expression of a novel truncated prestin splice isoform named prestin 9b (Slc26A5d) that contains a putative PDZ domain-binding motif. Using prestin 9b as the bait in a yeast two-hybrid assay, we identified a calcium/calmodulin-dependent serine protein kinase (CASK) as an interaction partner of prestin. Co-immunoprecipitation assays showed that CASK and prestin 9b can interact with full-length prestin. CASK was co-localized with prestin in a membrane domain where prestin-expressing OHC membrane abuts prestin-free OHC membrane, but was absent from this area for thyroid hormone deficiency. These findings suggest that CASK and the truncated prestin splice isoform contribute to confinement of prestin to the basolateral region of the plasma membrane. By means of such an interaction, the basal junction region between the OHC and its Deiter's cell may contribute to efficient generation of somatic electromechanical force.
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MESH Headings
- Animals
- Anion Transport Proteins/analysis
- Anion Transport Proteins/genetics
- Anion Transport Proteins/metabolism
- Cells, Cultured
- Electricity
- Female
- Guanylate Kinases/analysis
- Guanylate Kinases/genetics
- Guanylate Kinases/metabolism
- HEK293 Cells
- Hair Cells, Auditory, Outer/chemistry
- Hair Cells, Auditory, Outer/cytology
- Hair Cells, Auditory, Outer/physiology
- Humans
- Immunohistochemistry
- Mechanical Phenomena
- Mice
- Mice, Inbred Strains
- Molecular Motor Proteins/analysis
- Molecular Motor Proteins/genetics
- Molecular Motor Proteins/metabolism
- Rats
- Rats, Wistar
- Sulfate Transporters
- Vestibular Nucleus, Lateral/chemistry
- Vestibular Nucleus, Lateral/cytology
- Vestibular Nucleus, Lateral/metabolism
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Affiliation(s)
- Jelka Cimerman
- Department of Otolaryngology, Tübingen Hearing Research Centre (THRC), Molecular Physiology of Hearing, University of Tübingen, Tübingen, Germany
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