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Renigunta V, Xhaferri N, Shaikh IG, Schlegel J, Bisen R, Sanvido I, Kalpachidou T, Kummer K, Oliver D, Leitner MG, Lindner M. A versatile functional interaction between electrically silent K V subunits and K V7 potassium channels. Cell Mol Life Sci 2024; 81:301. [PMID: 39003683 PMCID: PMC11335225 DOI: 10.1007/s00018-024-05312-1] [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: 03/12/2024] [Revised: 05/23/2024] [Accepted: 06/10/2024] [Indexed: 07/15/2024]
Abstract
Voltage-gated K+ (KV) channels govern K+ ion flux across cell membranes in response to changes in membrane potential. They are formed by the assembly of four subunits, typically from the same family. Electrically silent KV channels (KVS), however, are unable to conduct currents on their own. It has been assumed that these KVS must obligatorily assemble with subunits from the KV2 family into heterotetrameric channels, thereby giving rise to currents distinct from those of homomeric KV2 channels. Herein, we show that KVS subunits indeed also modulate the activity, biophysical properties and surface expression of recombinant KV7 isoforms in a subunit-specific manner. Employing co-immunoprecipitation, and proximity labelling, we unveil the spatial coexistence of KVS and KV7 within a single protein complex. Electrophysiological experiments further indicate functional interaction and probably heterotetramer formation. Finally, single-cell transcriptomic analyses identify native cell types in which this KVS and KV7 interaction may occur. Our findings demonstrate that KV cross-family interaction is much more versatile than previously thought-possibly serving nature to shape potassium conductance to the needs of individual cell types.
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Affiliation(s)
- Vijay Renigunta
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037, Marburg, Germany
| | - Nermina Xhaferri
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037, Marburg, Germany
| | - Imran Gousebasha Shaikh
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037, Marburg, Germany
| | - Jonathan Schlegel
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037, Marburg, Germany
| | - Rajeshwari Bisen
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037, Marburg, Germany
| | - Ilaria Sanvido
- Institute of Physiology, Medical University of Innsbruck, Innsbruck, Austria
| | | | - Kai Kummer
- Institute of Physiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Dominik Oliver
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037, Marburg, Germany
| | - Michael G Leitner
- Institute of Physiology, Medical University of Innsbruck, Innsbruck, Austria.
| | - Moritz Lindner
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037, Marburg, Germany.
- The Nuffield Laboratory of Ophthalmology, Sleep and Circadian Neuroscience Institute, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK.
- Department of Ophthalmology, Philipps University Marburg, 35037, Marburg, Germany.
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Lee J, Fernandez K, Cunningham LL. Hear and Now: Ongoing Clinical Trials to Prevent Drug-Induced Hearing Loss. Annu Rev Pharmacol Toxicol 2024; 64:211-230. [PMID: 37562496 DOI: 10.1146/annurev-pharmtox-033123-114106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Each year over half a million people experience permanent hearing loss caused by treatment with therapeutic drugs with ototoxic side effects. There is a major unmet clinical need for therapies that protect against this hearing loss without reducing the therapeutic efficacy of these lifesaving drugs. At least 17 clinical trials evaluating 10 therapeutics are currently underway for therapies aimed at preventing aminoglycoside- and/or cisplatin-induced ototoxicity. This review describes the preclinical and clinical development of each of these approaches, provides updates on the status of ongoing trials, and highlights the importance of appropriate outcome measures in trial design and the value of reporting criteria in the dissemination of results.
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Affiliation(s)
- John Lee
- Laboratory of Hearing Biology and Therapeutics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, USA;
| | - Katharine Fernandez
- Laboratory of Hearing Biology and Therapeutics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, USA;
| | - Lisa L Cunningham
- Laboratory of Hearing Biology and Therapeutics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, USA;
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Choi JS, Ahn YJ, Lee S, Park DJ, Park J, Ha SM, Seo YJ. Role of Kir4.1 Channels in Aminoglycoside-Induced Ototoxicity of Hair Cells. BIOMED RESEARCH INTERNATIONAL 2023; 2023:4191999. [PMID: 38143588 PMCID: PMC10748730 DOI: 10.1155/2023/4191999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 10/27/2023] [Accepted: 11/14/2023] [Indexed: 12/26/2023]
Abstract
The Kir4.1 channel, an inwardly rectifying potassium ion (K+) channel, is located in the hair cells of the organ of Corti as well as the intermediate cells of the stria vascularis. The Kir4.1 channel has a crucial role in the generation of endolymphatic potential and maintenance of the resting membrane potential. However, the role and functions of the Kir4.1 channel in the progenitor remain undescribed. To observe the role of Kir4.1 in the progenitor treated with the one-shot ototoxic drugs (kanamycin and furosemide), we set the proper condition in culturing Immortomouse-derived HEI-OC1 cells to express the potassium-related channels well. And also, that was reproduced in mice experiments to show the important role of Kir4.1 in the survival of hair cells after treating the ototoxicity drugs. In our results, when kanamycin and furosemide drugs were cotreated with HEI-OC1 cells, the Kir4.1 channel did not change, but the expression levels of the NKCC1 cotransporter and KCNQ4 channel are decreased. This shows that inward and outward channels were blocked by the two drugs (kanamycin and furosemide). However, noteworthy here is that the expression level of Kir4.1 channel increased when kanamycin was treated alone. This shows that Kir4.1, an inwardly rectifying potassium channel, acts as an outward channel in place of the corresponding channel when the KCNQ4 channel, an outward channel, is blocked. These results suggest that the Kir4.1 channel has a role in maintaining K+ homeostasis in supporting cells, with K+ concentration compensator when the NKCC1 cotransporter and Kv7.4 (KCNQ4) channels are deficient.
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Affiliation(s)
- Jin Sil Choi
- Research Institute of Hearing Enhancement, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
- Department of Otorhinolaryngology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Ye Ji Ahn
- Research Institute of Hearing Enhancement, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
- Department of Otorhinolaryngology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - SuHoon Lee
- Research Institute of Hearing Enhancement, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
- Department of Otorhinolaryngology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Dong Jun Park
- Research Institute of Hearing Enhancement, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
- Department of Otorhinolaryngology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - JeongEun Park
- Research Institute of Hearing Enhancement, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
- Department of Otorhinolaryngology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Sun Mok Ha
- Research Institute of Hearing Enhancement, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
- Department of Otorhinolaryngology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
| | - Young Joon Seo
- Research Institute of Hearing Enhancement, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
- Department of Otorhinolaryngology, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea
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Janky K, Steyger PS. Mechanisms and Impact of Aminoglycoside-Induced Vestibular Deficits. Am J Audiol 2023; 32:746-760. [PMID: 37319406 PMCID: PMC10721243 DOI: 10.1044/2023_aja-22-00199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 01/26/2023] [Accepted: 03/06/2023] [Indexed: 06/17/2023] Open
Abstract
PURPOSE Acquired vestibulotoxicity from hospital-prescribed medications such as aminoglycoside antibiotics affects as many as 40,000 people each year in North America. However, there are no current federally approved drugs to prevent or treat the debilitating and permanent loss of vestibular function caused by bactericidal aminoglycoside antibiotics. This review will cover our current understanding of the impact of, and mechanisms underlying, aminoglycoside-induced vestibulotoxicity and highlight the gaps in our knowledge that remain. CONCLUSIONS Aminoglycoside-induced vestibular deficits have long-term impacts on patients across the lifespan. Additionally, the prevalence of aminoglycoside-induced vestibulotoxicity appears to be greater than cochleotoxicity. Thus, monitoring for vestibulotoxicity should be independent of auditory monitoring and encompass patients of all ages from young children to older adults before, during, and after aminoglycoside therapy.
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Affiliation(s)
- Kristen Janky
- Department of Audiology, Boys Town National Research Hospital, Omaha, NE
| | - Peter S. Steyger
- Bellucci Translational Hearing Center, Creighton University, Omaha, NE
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Rivetti S, Romano A, Mastrangelo S, Attinà G, Maurizi P, Ruggiero A. Aminoglycosides-Related Ototoxicity: Mechanisms, Risk Factors, and Prevention in Pediatric Patients. Pharmaceuticals (Basel) 2023; 16:1353. [PMID: 37895824 PMCID: PMC10610175 DOI: 10.3390/ph16101353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Revised: 09/17/2023] [Accepted: 09/21/2023] [Indexed: 10/29/2023] Open
Abstract
Aminoglycosides are broad-spectrum antibiotics largely used in children, but they have potential toxic side effects, including ototoxicity. Ototoxicity from aminoglycosides is permanent and is a consequence of its action on the inner ear cells via multiple mechanisms. Both uncontrollable risk factors and controllable risk factors are involved in the pathogenesis of aminoglycoside-related ototoxicity and, because of the irreversibility of ototoxicity, an important undertaking for preventing ototoxicity includes antibiotic stewardship to limit the use of aminoglycosides. Aminoglycosides are fundamental in the treatment of numerous infectious conditions at neonatal and pediatric age. In childhood, normal auditory function ensures adequate neurocognitive and social development. Hearing damage from aminoglycosides can therefore strongly affect the normal growth of the child. This review describes the molecular mechanisms of aminoglycoside-related ototoxicity and analyzes the risk factors and the potential otoprotective strategies in pediatric patients.
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Affiliation(s)
- Serena Rivetti
- Pediatric Oncology Unit, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, 00168 Rome, Italy; (S.R.); (A.R.); (S.M.); (G.A.); (P.M.)
| | - Alberto Romano
- Pediatric Oncology Unit, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, 00168 Rome, Italy; (S.R.); (A.R.); (S.M.); (G.A.); (P.M.)
| | - Stefano Mastrangelo
- Pediatric Oncology Unit, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, 00168 Rome, Italy; (S.R.); (A.R.); (S.M.); (G.A.); (P.M.)
- Dipartimento di Scienze della Vita e Sanità Pubblica, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Giorgio Attinà
- Pediatric Oncology Unit, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, 00168 Rome, Italy; (S.R.); (A.R.); (S.M.); (G.A.); (P.M.)
| | - Palma Maurizi
- Pediatric Oncology Unit, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, 00168 Rome, Italy; (S.R.); (A.R.); (S.M.); (G.A.); (P.M.)
- Dipartimento di Scienze della Vita e Sanità Pubblica, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
| | - Antonio Ruggiero
- Pediatric Oncology Unit, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, 00168 Rome, Italy; (S.R.); (A.R.); (S.M.); (G.A.); (P.M.)
- Dipartimento di Scienze della Vita e Sanità Pubblica, Università Cattolica del Sacro Cuore, 00168 Rome, Italy
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Hu S, Sun Q, Xu F, Jiang N, Gao J. Age-related hearing loss and its potential drug candidates: a systematic review. Chin Med 2023; 18:121. [PMID: 37730634 PMCID: PMC10512576 DOI: 10.1186/s13020-023-00825-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Accepted: 08/25/2023] [Indexed: 09/22/2023] Open
Abstract
BACKGROUND Age-related hearing loss (ARHL) is one of the main illnesses afflicting the aged population and has a significant negative impact on society, economy, and health. However, there is presently no appropriate therapeutic treatment of ARHL due to the absence of comprehensive trials. OBJECTIVES The goal of this review is to systematically evaluate and analyze recent statistics on the pathologic classifications, risk factors, treatment strategies, and drug candidates of ARHL, including that from traditional Chinese medicine (TCM), to provide potential new approaches for preventing and treating ARHL. METHODS Literature related to ARHL was conducted in databases such as PubMed, WOS, China National Knowledge Infrastructure (CNKI), and Wanfang from the establishment of the database to Jan, 2023. The pathology, causal factor, pathophysiological mechanism, treatment strategy, and the drug candidate of ARHL were extracted and pooled for synthesis. RESULTS Many hypotheses about the etiology of ARHL are based on genetic and environmental elements. Most of the current research on the pathology of ARHL focuses on oxidative damage, mitochondrial dysfunction, inflammation, cochlear blood flow, ion homeostasis, etc. In TCM, herbs belonging to the kidney, lung, and liver meridians exhibit good hearing protection. Seven herbs belonging to the kidney meridian, 9 belonging to the lung meridian, and 4 belonging to the liver meridian were ultimately retrieved in this review, such as Polygonum multiflorum Thunb., Panax ginseng C.A. Mey, and Pueraria lobata (Willd.) Ohwi. Their active compounds, 2,3,4',5-Tetrahydroxystilbene-2-O-D-glucoside, ginsenoside Rb1, and puerarin, may act as the molecular substance for their anti-ARHL efficacy, and show anti-oxidative, neuroprotective, anti-inflammatory, anti-apoptotic, or mitochondrial protective effects. CONCLUSION Anti-oxidants, modulators of mitochondrial function, anti-inflammation agents, vasodilators, K+ channel openers, Ca2+ channel blockers, JNK inhibitors, and nerve growth factors/neurotrophic factors all contribute to hearing protection, and herbs are an important source of potential anti-ARHL drugs.
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Affiliation(s)
- Shiyu Hu
- School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, 310053, Zhejiang, People's Republic of China
| | - Qingru Sun
- School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, 310053, Zhejiang, People's Republic of China
| | - Fei Xu
- School of Medical Technology and Information Engineering, Zhejiang Chinese Medical University, Hangzhou, 310053, Zhejiang, People's Republic of China
| | - Ninghua Jiang
- Department of Pharmacy, The Second Affiliated Hospital of Jiaxing University, Jiaxing, 314000, Zhejiang, People's Republic of China
| | - Jianli Gao
- School of Pharmaceutical Sciences, Zhejiang Chinese Medical University, Hangzhou, 310053, Zhejiang, People's Republic of China.
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Manickam R, Virzi J, Potti A, Cheng F, Russ DW, Tipparaju SM. Genetic deletion of Kvβ2 (AKR6) causes loss of muscle function and increased inflammation in mice. FRONTIERS IN AGING 2023; 4:1175510. [PMID: 37377453 PMCID: PMC10292803 DOI: 10.3389/fragi.2023.1175510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 05/25/2023] [Indexed: 06/29/2023]
Abstract
The voltage-gated potassium channels (Kv) are complex ion channels with distinct roles in neurotransmission, electrical conductivity of the heart, and smooth and striated muscle functions. Previously, we demonstrated that deletion of Kvβ2 in mice results in decreased Pax7 protein levels, hindlimb muscles and body weights, and fiber type switching. In the present study, we tested the hypothesis that Kvβ2 regulates skeletal muscle function in mice. The young and old Kvβ2 knockout (KO) and wildtype (WT) mice were utilized to test the aging phenotype and skeletal muscle function. Consistent with our previous finding, we found a significant reduction in hindlimb skeletal muscles mass and body weight in young Kvβ2 KO mice, which was also significantly reduced in old Kvβ2 KO mice compared with age-matched WT mice. Forelimb grip strength, and the hindleg extensor digitorum longus (EDL) muscles force-frequency relations were significantly decreased in young and old Kvβ2 KO mice compared to age-matched WT mice. Analysis of transmission electron microscopy images of EDL muscles in young mice revealed a significant reduction in the sarcomere length for Kvβ2 KO vs. WT. Hematoxylin and eosin-stained tibialis anterior muscles cryosections displayed a significant decrease in the number of medium (2,000-4,000 µm2) and largest (>4,000 µm2) myofibers area in young Kvβ2 KO vs. WT mice. We also found a significant increase in fibrotic tissue area in young Kvβ2 KO mice compared with age-matched WT mice. Analysis of RNA Seq data of the gastrocnemius muscles (GAS) identified significant increase in genes involved in skeletal muscle development, proliferation and cell fate determination, atrophy, energy metabolism, muscle plasticity, inflammation, and a decrease in circadian core clock genes in young Kvβ2 KO vs. WT mice. Several genes were significantly upregulated (384 genes) and downregulated (40 genes) in young Kvβ2 KO mice compared to age-matched WT mice. Further, RT-qPCR analysis of the GAS muscles displayed a significant increase in pro-inflammatory marker Il6 expression in young Kvβ2 KO mice compared to age-matched WT mice. Overall, the present study shows that deletion of Kvβ2 leads to decreased muscles strength and increased inflammation.
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Affiliation(s)
- Ravikumar Manickam
- Department of Pharmaceutical Sciences, Taneja College of Pharmacy, University of South Florida, Tampa, FL, United States
| | - Jazmine Virzi
- Department of Pharmaceutical Sciences, Taneja College of Pharmacy, University of South Florida, Tampa, FL, United States
| | - Anish Potti
- Department of Pharmaceutical Sciences, Taneja College of Pharmacy, University of South Florida, Tampa, FL, United States
| | - Feng Cheng
- Department of Pharmaceutical Sciences, Taneja College of Pharmacy, University of South Florida, Tampa, FL, United States
| | - David W. Russ
- School of Physical Therapy and Rehabilitation Sciences, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
| | - Srinivas M. Tipparaju
- Department of Pharmaceutical Sciences, Taneja College of Pharmacy, University of South Florida, Tampa, FL, United States
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Kim YR, Baek JI, Lee KY, Kim UK. Berberine chloride protects cochlear hair cells from aminoglycoside-induced ototoxicity by reducing the accumulation of mitochondrial reactive oxygen species. Free Radic Biol Med 2023; 204:177-183. [PMID: 37119862 DOI: 10.1016/j.freeradbiomed.2023.04.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 04/22/2023] [Accepted: 04/26/2023] [Indexed: 05/01/2023]
Abstract
Aminoglycoside, a medicinal category of antibiotics, are used in treatment of Gram-negative bacterial infections. Although they are the most widely-used antibiotics due to their high efficacy and low cost, several main adverse effects have been reported including nephrotoxicity and ototoxicity. Since drug-induced ototoxicity is one of the major etiological causes of acquired hearing loss, we examined cochlear hair cell damages caused by three aminoglycosides (amikacin, kanamycin, and gentamicin), and investigated protective property of an isoquinoline-type alkaloid, Berberine chloride (BC). Berberine, a well-known bioactive compound found from medicinal plants, has been known to have anti-inflammatory, antimicrobial effects. To determine protective effect of BC in aminoglycoside-induced ototoxicity, hair cell damages in aminoglycoside- and/or BC-treated hair cells using ex vivo organotypic culture system of mouse cochlea. Mitochondrial ROS levels and depolarization of mitochondrial membrane potential were analyzed, and TUNEL assay and immunostaining of cleaved caspase-3 were performed to detect apoptosis signals. As the results, it was found that BC significantly prevented aminoglycoside-induced hair cell loss and stereocilia degeneration by inhibiting excessive accumulation of mitochondrial ROS and subsequent loss of mitochondrial membrane potential. It eventually inhibited DNA fragmentation and caspase-3 activation, which were significant for all three aminoglycosides. This study is the first report suggested the preventative effect of BC against aminoglycoside-induced ototoxicity. Our data also suggests a possibility that BC has the potential to exert a protective effect against ototoxicity caused by various ototoxic drugs leading to cellular oxidative stress, not limited to aminoglycoside antibiotics.
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Affiliation(s)
- Ye-Ri Kim
- Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu, 41566, Republic of Korea
| | - Jeong-In Baek
- Department of Companion Animal Health, College of Rehabilitation and Health, Daegu Haany University, Gyeongsan, 38610, Republic of Korea
| | - Kyu-Yup Lee
- Department of Otorhinolaryngology-Head and Neck Surgery, School of Medicine, Kyungpook National University, Daegu, Republic of Korea.
| | - Un-Kyung Kim
- Department of Biology, College of Natural Sciences, Kyungpook National University, Daegu, 41566, Republic of Korea; School of Life Sciences, KNU Creative BioResearch Group (BK21 Plus Project), Kyungpook National University, Daegu, 41566, Republic of Korea.
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Fogliano C, Motta CM, Avallone B. Salicylate attenuates gentamicin-induced ototoxicity and facilitates the recovery in the basilar papilla of the lizard Podarcis siculus. Neurotoxicology 2022; 93:301-310. [DOI: 10.1016/j.neuro.2022.10.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 10/24/2022] [Accepted: 10/24/2022] [Indexed: 11/15/2022]
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Peixoto Pinheiro B, Müller M, Bös M, Guezguez J, Burnet M, Tornincasa M, Rizzetto R, Rolland JF, Liberati C, Lohmer S, Adel Y, Löwenheim H. A potassium channel agonist protects hearing function and promotes outer hair cell survival in a mouse model for age-related hearing loss. Cell Death Dis 2022; 13:595. [PMID: 35817766 PMCID: PMC9273644 DOI: 10.1038/s41419-022-04915-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 04/29/2022] [Accepted: 05/04/2022] [Indexed: 01/21/2023]
Abstract
Age-related hearing loss (ARHL) is the most common sensory impairment mainly caused by degeneration of sensory hair cells in the cochlea with no causal medical treatment available. Auditory function and sensory hair cell survival critically depend on the Kv7.4 (KCNQ4) channel, a voltage-gated potassium channel expressed in outer hair cells (OHCs), with its impaired function or reduced activity previously associated with ARHL. Here, we investigated the effect of a potent small-molecule Kv7.4 agonist on ARHL in the senescence-accelerated mouse prone 8 (SAMP8) model. For the first time in vivo, we show that Kv7.4 activation can significantly reduce age-related threshold shifts of auditory brainstem responses as well as OHC loss in the SAMP8 model. Pharmacological activation of Kv7.4 thus holds great potential as a therapeutic approach for ARHL as well as other hearing impairments related to Kv7.4 function.
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Affiliation(s)
- Barbara Peixoto Pinheiro
- grid.10392.390000 0001 2190 1447Translational Hearing Research, Tübingen Hearing Research Center, Department of Otolaryngology, Head & Neck Surgery, University of Tübingen, 72076 Tübingen, Germany
| | - Marcus Müller
- grid.10392.390000 0001 2190 1447Translational Hearing Research, Tübingen Hearing Research Center, Department of Otolaryngology, Head & Neck Surgery, University of Tübingen, 72076 Tübingen, Germany
| | - Michael Bös
- Acousia Therapeutics, 72070 Tübingen, Germany
| | | | | | - Mara Tornincasa
- grid.427692.c0000 0004 1794 5078Axxam, Bresso, 20091 Milan, Italy
| | | | | | - Chiara Liberati
- grid.427692.c0000 0004 1794 5078Axxam, Bresso, 20091 Milan, Italy
| | - Stefan Lohmer
- grid.427692.c0000 0004 1794 5078Axxam, Bresso, 20091 Milan, Italy
| | - Youssef Adel
- grid.10392.390000 0001 2190 1447Translational Hearing Research, Tübingen Hearing Research Center, Department of Otolaryngology, Head & Neck Surgery, University of Tübingen, 72076 Tübingen, Germany
| | - Hubert Löwenheim
- grid.10392.390000 0001 2190 1447Translational Hearing Research, Tübingen Hearing Research Center, Department of Otolaryngology, Head & Neck Surgery, University of Tübingen, 72076 Tübingen, Germany
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11
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Singh SP, William M, Malavia M, Chu XP. Behavior of KCNQ Channels in Neural Plasticity and Motor Disorders. MEMBRANES 2022; 12:membranes12050499. [PMID: 35629827 PMCID: PMC9143857 DOI: 10.3390/membranes12050499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 04/26/2022] [Accepted: 05/03/2022] [Indexed: 02/01/2023]
Abstract
The broad distribution of voltage-gated potassium channels (VGKCs) in the human body makes them a critical component for the study of physiological and pathological function. Within the KCNQ family of VGKCs, these aqueous conduits serve an array of critical roles in homeostasis, especially in neural tissue. Moreover, the greater emphasis on genomic identification in the past century has led to a growth in literature on the role of the ion channels in pathological disease as well. Despite this, there is a need to consolidate the updated findings regarding both the pharmacotherapeutic and pathological roles of KCNQ channels, especially regarding neural plasticity and motor disorders which have the largest body of literature on this channel. Specifically, KCNQ channels serve a remarkable role in modulating the synaptic efficiency required to create appropriate plasticity in the brain. This role can serve as a foundation for clinical approaches to chronic pain. Additionally, KCNQ channels in motor disorders have been utilized as a direction for contemporary pharmacotherapeutic developments due to the muscarinic properties of this channel. The aim of this study is to provide a contemporary review of the behavior of these channels in neural plasticity and motor disorders. Upon review, the behavior of these channels is largely dependent on the physiological role that KCNQ modulatory factors (i.e., pharmacotherapeutic options) serve in pathological diseases.
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12
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Steyger PS. Mechanisms of Aminoglycoside- and Cisplatin-Induced Ototoxicity. Am J Audiol 2021; 30:887-900. [PMID: 34415784 PMCID: PMC9126111 DOI: 10.1044/2021_aja-21-00006] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 04/30/2021] [Accepted: 05/14/2021] [Indexed: 12/11/2022] Open
Abstract
Purpose This review article summarizes our current understanding of the mechanisms underlying acquired hearing loss from hospital-prescribed medications that affects as many as 1 million people each year in Western Europe and North America. Yet, there are currently no federally approved drugs to prevent or treat the debilitating and permanent hearing loss caused by the life-saving platinum-based anticancer drugs or the bactericidal aminoglycoside antibiotics. Hearing loss has long-term impacts on quality-of-life measures, especially in young children and older adults. This review article also highlights some of the current knowledge gaps regarding iatrogenic causes of hearing loss. Conclusion Further research is urgently needed to further refine clinical practice and better ameliorate iatrogenic drug-induced hearing loss.
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Affiliation(s)
- Peter S. Steyger
- Translational Hearing Center, Creighton University, Omaha, NE
- National Center for Rehabilitative Auditory Research, VA Portland Health Care System, OR
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13
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Pipatpolkai T, Quetschlich D, Stansfeld PJ. From Bench to Biomolecular Simulation: Phospholipid Modulation of Potassium Channels. J Mol Biol 2021; 433:167105. [PMID: 34139216 PMCID: PMC8361781 DOI: 10.1016/j.jmb.2021.167105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 06/09/2021] [Accepted: 06/10/2021] [Indexed: 12/05/2022]
Abstract
Potassium (K+) ion channels are crucial in numerous cellular processes as they hyperpolarise a cell through K+ conductance, returning a cell to its resting potential. K+ channel mutations result in multiple clinical complications such as arrhythmia, neonatal diabetes and migraines. Since 1995, the regulation of K+ channels by phospholipids has been heavily studied using a range of interdisciplinary methods such as cellular electrophysiology, structural biology and computational modelling. As a result, K+ channels are model proteins for the analysis of protein-lipid interactions. In this review, we will focus on the roles of lipids in the regulation of K+ channels, and how atomic-level structures, along with experimental techniques and molecular simulations, have helped guide our understanding of the importance of phospholipid interactions.
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Affiliation(s)
- Tanadet Pipatpolkai
- Department of Biochemistry, South Parks Road, Oxford OX1 3QU, UK; Department of Physiology Anatomy and Genetics, Parks Road, Oxford OX1 3PT, UK; OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford OX1 3PT, UK
| | - Daniel Quetschlich
- Department of Biochemistry, South Parks Road, Oxford OX1 3QU, UK; Department of Chemistry, South Parks Road, Oxford OX1 3QZ, UK
| | - Phillip J Stansfeld
- School of Life Sciences & Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
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14
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Optimized Tuning of Auditory Inner Hair Cells to Encode Complex Sound through Synergistic Activity of Six Independent K + Current Entities. Cell Rep 2021; 32:107869. [PMID: 32640234 DOI: 10.1016/j.celrep.2020.107869] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 04/08/2020] [Accepted: 06/16/2020] [Indexed: 02/06/2023] Open
Abstract
Auditory inner hair cells (IHCs) convert sound vibrations into receptor potentials that drive synaptic transmission. For the precise encoding of sound qualities, receptor potentials are shaped by K+ conductances tuning the properties of the IHC membrane. Using patch-clamp and computational modeling, we unravel this membrane specialization showing that IHCs express an exclusive repertoire of six voltage-dependent K+ conductances mediated by Kv1.8, Kv7.4, Kv11.1, Kv12.1, and BKCa channels. All channels are active at rest but are triggered differentially during sound stimulation. This enables non-saturating tuning over a far larger potential range than in IHCs expressing fewer current entities. Each conductance contributes to optimizing responses, but the combined activity of all channels synergistically improves phase locking and the dynamic range of intensities that IHCs can encode. Conversely, hypothetical simpler IHCs appear limited to encode only certain aspects (frequency or intensity). The exclusive channel repertoire of IHCs thus constitutes an evolutionary adaptation to encode complex sound through multifaceted receptor potentials.
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15
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Ashmore J. Tonotopy of cochlear hair cell biophysics (excl. mechanotransduction). CURRENT OPINION IN PHYSIOLOGY 2020. [DOI: 10.1016/j.cophys.2020.06.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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16
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Martelletti E, Ingham NJ, Houston O, Pass JC, Chen J, Marcotti W, Steel KP. Synaptojanin2 Mutation Causes Progressive High-frequency Hearing Loss in Mice. Front Cell Neurosci 2020; 14:561857. [PMID: 33100973 PMCID: PMC7546894 DOI: 10.3389/fncel.2020.561857] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 08/14/2020] [Indexed: 12/04/2022] Open
Abstract
Progressive hearing loss is very common in the human population but we know little about the underlying molecular mechanisms. Synaptojanin2 (Synj2) has been reported to be involved, as a mouse mutation led to a progressive increase in auditory thresholds with age. Synaptojanin2 is a phosphatidylinositol (PI) phosphatase that removes the five-position phosphates from phosphoinositides, such as PIP2 and PIP3, and is a key enzyme in clathrin-mediated endocytosis. To investigate the mechanisms underlying progressive hearing loss, we have studied a different mutation of mouse Synj2 to look for any evidence of involvement of vesicle trafficking particularly affecting the synapses of sensory hair cells. Auditory brainstem responses (ABR) developed normally at first but started to decline between 3 and 4 weeks of age in Synj2tm1b mutants. At 6 weeks old, some evidence of outer hair cell (OHC) stereocilia fusion and degeneration was observed, but this was only seen in the extreme basal turn so cannot explain the raised ABR thresholds that correspond to more apical regions of the cochlear duct. We found no evidence of any defect in inner hair cell (IHC) exocytosis or endocytosis using single hair cell recordings, nor any sign of hair cell synaptic abnormalities. Endocochlear potentials (EP) were normal. The mechanism underlying progressive hearing loss in these mutants remains elusive, but our findings of raised distortion product otoacoustic emission (DPOAE) thresholds and signs of OHC degeneration both suggest an OHC origin for the hearing loss. Synaptojanin2 is not required for normal development of hearing but it is important for its maintenance.
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Affiliation(s)
- Elisa Martelletti
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Neil J Ingham
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Oliver Houston
- Department of Biomedical Sciences, University of Sheffield, Sheffield, United Kingdom
| | - Johanna C Pass
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Jing Chen
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
| | - Walter Marcotti
- Department of Biomedical Sciences, University of Sheffield, Sheffield, United Kingdom.,Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom
| | - Karen P Steel
- Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom
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17
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Shao W, Zhong D, Jiang H, Han Y, Yin Y, Li R, Qian X, Chen D, Jing L. A new aminoglycoside etimicin shows low nephrotoxicity and ototoxicity in zebrafish embryos. J Appl Toxicol 2020; 41:1063-1075. [PMID: 33094525 DOI: 10.1002/jat.4093] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 09/21/2020] [Accepted: 10/04/2020] [Indexed: 01/06/2023]
Abstract
Aminoglycoside antibiotics are widely used for many life-threatening infections. The use of aminoglycosides is often comprised by their deleterious side effects to the kidney and inner ear. A novel semisynthetic antibiotic, etimicin, has good antimicrobial activity against both gram-positive and gram-negative bacteria. But its toxicity profile analysis is still lacking. In the present study, we compared the in vivo toxic effects of three aminoglycosides, gentamicin, amikacin, and etimicin, in zebrafish embryos. We examined the embryotoxicity, nephrotoxicity, and the damage to the neuromast hair cells. Our results revealed that etimicin and amikacin exhibit more developmental toxicities to the young embryos than gentamicin. But at subtoxic doses, etimicin and amikacin show significantly reduced toxicities towards kidney and neuromast hair cells. We further demonstrated that fluorescently conjugated aminoglycosides (gentamicin-Texas red [GTTR], amikacin-Texas red [AMTR], and etimicin-Texas red [ETTR]) all enter the hair cells properly. Inside the hair cells, gentamicin, not etimicin and amikacin, displays robust reactive oxygen species generation and induces apoptosis. Our data support that the different intracellular cytotoxicity underlies the different ototoxicity of the three aminoglycosides and that etimicin is a new aminoglycoside with reduced risk of nephrotoxicity and ototoxicity.
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Affiliation(s)
- Weihao Shao
- Engineering Research Center of Cell & Therapeutic Antibody, Ministry of Education, School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
| | - Dan Zhong
- Engineering Research Center of Cell & Therapeutic Antibody, Ministry of Education, School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
| | - Haowei Jiang
- Engineering Research Center of Cell & Therapeutic Antibody, Ministry of Education, School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
| | - Yujie Han
- Engineering Research Center of Cell & Therapeutic Antibody, Ministry of Education, School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
| | - Yu Yin
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
| | - Ruining Li
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
| | - Xiuping Qian
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
| | - Daijie Chen
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
| | - Lili Jing
- Engineering Research Center of Cell & Therapeutic Antibody, Ministry of Education, School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
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Kovacik A, Tvrda E, Jambor T, Fulopova D, Kovacikova E, Hleba L, Kołodziejczyk ŁM, Hlebova M, Gren A, Massanyi P. Cytotoxic effect of aminoglycoside antibiotics on the mammalian cell lines. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2020; 56:1-8. [PMID: 33040680 DOI: 10.1080/10934529.2020.1830653] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 09/25/2020] [Accepted: 09/26/2020] [Indexed: 06/11/2023]
Abstract
Aminoglycoside antibiotics have been used for treating serious but also routine infections in veterinary and human medicine for many years. The basic aim of this work is to evaluate the cytotoxicity of dihydrostreptomycin and neomycin in vitro on three cell cultures - BHK-21 (Syrian golden hamster kidney fibroblast), VERO (African green monkey kidney fibroblast) and FEA (feline embryonic fibroblast) cells. The morphological changes were examined by Giemsa staining. Cells were dried and visualized under fluorescence microscope. After the exposure to different experimental doses of dihydrostreptomycin (812.5-20000 µg/mL) and neomycin (1000-20000 µg/mL) during 24 h, the viability of BHK-21, FEA and VERO cell lines were evaluated by MTT assay. Viability of BHK-21 cells significantly (P < 0.001) decreased after treatment with 3500; 5500 and 7500 µg/mL of dihydrostreptomycin and 9000; 10000 and 20000 µg/mL of neomycin. The FEA cell viability decreased significantly (P < 0.001; P < 0.01) at 2500 and 3000 µg/mL dihydrostreptomycin and at 3000 µg/mL of neomycin treatment. Only the highest concentration of dihydrostreptomycin (20000 µg/mL) reduced VERO cell viability significantly (P < 0.01). Based on or results we can assume the effect of different antibiotics in different concentrations on cell lines is various. Detection of antibiotic toxicity to animal cells is very important because of the increasing resistance of bacteria. One of the solutions is drug dose increasing, but only to a certain concentration, since the toxic effect over the therapeutic one will prevail, which we have also shown in this work.
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Affiliation(s)
- Anton Kovacik
- Department of Animal Physiology, Faculty of Biotechnology and Food Sciences, Slovak University of Agriculture in Nitra, Nitra, Slovak Republic
| | - Eva Tvrda
- Department of Animal Physiology, Faculty of Biotechnology and Food Sciences, Slovak University of Agriculture in Nitra, Nitra, Slovak Republic
| | - Tomas Jambor
- BioFood Centre, Faculty of Biotechnology and Food Sciences, Slovak University of Agriculture in Nitra, Nitra, Slovak Republic
| | - Diana Fulopova
- Institute for State Control of Veterinary Biologicals and Medicaments, Nitra, Slovak Republic
| | - Eva Kovacikova
- AgroBioTech Research Centre, Slovak University of Agriculture in Nitra, Nitra, Slovak Republic
| | - Lukas Hleba
- Department of Microbiology, Faculty of Biotechnology and Food Sciences, Slovak University of Agriculture in Nitra, Nitra, Slovak Republic
| | - Łukasz M Kołodziejczyk
- Department of Animal Physiology, Institute of Biology, Pedagogical University of Cracow, Kraków, Poland
| | - Miroslava Hlebova
- Department of Biology, Faculty of Natural Sciences, University of Ss. Cyril and Methodius in Trnava, Trnava, Slovak Republic
| | - Agnieszka Gren
- Department of Animal Physiology, Institute of Biology, Pedagogical University of Cracow, Kraków, Poland
| | - Peter Massanyi
- Department of Animal Physiology, Faculty of Biotechnology and Food Sciences, Slovak University of Agriculture in Nitra, Nitra, Slovak Republic
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Morán-Zendejas R, Delgado-Ramírez M, Xu J, Valdés-Abadía B, Aréchiga-Figueroa IA, Cui M, Rodríguez-Menchaca AA. In vitro and in silico characterization of the inhibition of Kir4.1 channels by aminoglycoside antibiotics. Br J Pharmacol 2020; 177:4548-4560. [PMID: 32726456 DOI: 10.1111/bph.15214] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 06/11/2020] [Accepted: 07/15/2020] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Aminoglycoside antibiotics are positively charged molecules that are known to inhibit several ion channels. In this study, we have shown that aminoglycosides also inhibit the activity of Kir4.1 channels. Aminoglycosides inhibit Kir4.1 channels by a pore-blocking mechanism, plugging the central vestibule of the channel. EXPERIMENTAL APPROACH Patch-clamp recordings were made in HEK-293 cells transiently expressing Kir4.1 channels to analyse the effects of gentamicin, neomycin and kanamycin. In silico modelling followed by mutagenesis were realized to identify the residues critical for aminoglycosides binding to Kir4.1. KEY RESULTS Aminoglycoside antibiotics block Kir4.1 channels in a concentration- and voltage-dependent manner, getting access to the protein from the intracellular side of the plasma membrane. Aminoglycosides block Ki4.1 with a rank order of potency as follows: gentamicin ˃ neomycin ˃ kanamycin. The residues T128 and principally E158, facing the central cavity of Kir4.1, are important structural determinants for aminoglycosides binding to the channel, as determined by our in silico modelling and confirmed by mutagenesis experiments. CONCLUSION AND IMPLICATIONS Kir4.1 channels are also target of aminoglycoside antibiotics, which could affect potassium transport in several tissues.
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Affiliation(s)
- Rita Morán-Zendejas
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico
| | - Mayra Delgado-Ramírez
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico
| | - Jie Xu
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China.,Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Belkis Valdés-Abadía
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico
| | | | - Meng Cui
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Aldo A Rodríguez-Menchaca
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico
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20
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Kros CJ, Steyger PS. Aminoglycoside- and Cisplatin-Induced Ototoxicity: Mechanisms and Otoprotective Strategies. Cold Spring Harb Perspect Med 2019; 9:cshperspect.a033548. [PMID: 30559254 DOI: 10.1101/cshperspect.a033548] [Citation(s) in RCA: 98] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Ototoxicity refers to damage of inner ear structures (i.e., the cochlea and vestibule) and their function (hearing and balance) following exposure to specific in-hospital medications (i.e., aminoglycoside antibiotics, platinum-based drugs), as well as a variety of environmental or occupational exposures (e.g., metals and solvents). This review provides a narrative derived from relevant papers describing factors contributing to (or increasing the risk of) aminoglycoside and cisplatin-induced ototoxicity. We also review current strategies to protect against ototoxicity induced by these indispensable pharmacotherapeutic treatments for life-threatening infections and solid tumors. We end by highlighting several interventional strategies that are currently in development, as well as the diverse challenges that still need to be overcome to prevent drug-induced hearing loss.
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Affiliation(s)
- Corné J Kros
- Sussex Neuroscience, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9QG, United Kingdom
| | - Peter S Steyger
- Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon 97239.,National Center for Rehabilitative Auditory Research, VA Portland Health Care System, Portland, Oregon 97239
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21
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β-Secretase BACE1 Is Required for Normal Cochlear Function. J Neurosci 2019; 39:9013-9027. [PMID: 31527119 DOI: 10.1523/jneurosci.0028-19.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 08/30/2019] [Accepted: 09/04/2019] [Indexed: 12/20/2022] Open
Abstract
Cleavage of amyloid precursor protein (APP) by β-secretase BACE1 initiates the production and accumulation of neurotoxic amyloid-β peptides, which is widely considered an essential pathogenic mechanism in Alzheimer's disease (AD). Here, we report that BACE1 is essential for normal auditory function. Compared with wild-type littermates, BACE1-/- mice of either sex exhibit significant hearing deficits, as indicated by increased thresholds and reduced amplitudes in auditory brainstem responses (ABRs) and decreased distortion product otoacoustic emissions (DPOAEs). Immunohistochemistry revealed aberrant synaptic organization in the cochlea and hypomyelination of auditory nerve fibers as predominant neuropathological substrates of hearing loss in BACE1-/- mice. In particular, we found that fibers of spiral ganglion neurons (SGN) close to the organ of Corti are disorganized and abnormally swollen. BACE1 deficiency also engenders organization defects in the postsynaptic compartment of SGN fibers with ectopic overexpression of PSD95 far outside the synaptic region. During postnatal development, auditory fiber myelination in BACE1-/- mice lags behind dramatically and remains incomplete into adulthood. We relate the marked hypomyelination to the impaired processing of Neuregulin-1 when BACE1 is absent. To determine whether the cochlea of adult wild-type mice is susceptible to AD treatment-like suppression of BACE1, we administered the established BACE1 inhibitor NB-360 for 6 weeks. The drug suppressed BACE1 activity in the brain, but did not impair hearing performance and, upon neuropathological examination, did not produce the characteristic cochlear abnormalities of BACE1-/- mice. Together, these data strongly suggest that the hearing loss of BACE1 knock-out mice represents a developmental phenotype.SIGNIFICANCE STATEMENT Given its crucial role in the pathogenesis of Alzheimer's disease (AD), BACE1 is a prime pharmacological target for AD prevention and therapy. However, the safe and long-term administration of BACE1-inhibitors as envisioned in AD requires a comprehensive understanding of the various physiological functions of BACE1. Here, we report that BACE1 is essential for the processing of auditory signals in the inner ear, as BACE1-deficient mice exhibit significant hearing loss. We relate this deficit to impaired myelination and aberrant synapse formation in the cochlea, which manifest during postnatal development. By contrast, prolonged pharmacological suppression of BACE1 activity in adult wild-type mice did not reproduce the hearing deficit or the cochlear abnormalities of BACE1 null mice.
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22
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Dierich M, van Ham WB, Stary‐Weinzinger A, Leitner MG. Histidine at position 462 determines the low quinine sensitivity of ether-à-go-go channel superfamily member K v 12.1. Br J Pharmacol 2019; 176:2708-2723. [PMID: 31032878 PMCID: PMC6609544 DOI: 10.1111/bph.14693] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 04/03/2019] [Accepted: 04/15/2019] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE The ether-à-go-go (Eag) Kv superfamily comprises closely related Kv 10, Kv 11, and Kv 12 subunits. Kv 11.1 (termed hERG in humans) gained much attention, as drug-induced inhibition of these channels is a frequent cause of sudden death in humans. The exclusive drug sensitivity of Kv 11.1 can be explained by central drug-binding pockets that are absent in most other channels. Currently, it is unknown whether Kv 12 channels are equipped with an analogous drug-binding pocket and whether drug-binding properties are conserved in all Eag superfamily members. EXPERIMENTAL APPROACH We analysed sensitivity of recombinant Kv 12.1 channels to quinine, a substituted quinoline that blocks Kv 10.1 and Kv 11.1 at low micromolar concentrations. KEY RESULTS Quinine inhibited Kv 12.1, but its affinity was 10-fold lower than for Kv 11.1. Contrary to Kv 11.1, quinine inhibited Kv 12.1 in a largely voltage-independent manner and induced channel opening at more depolarised potentials. Low sensitivity of Kv 12.1 and characteristics of quinine-dependent inhibition were determined by histidine 462, as site-directed mutagenesis of this residue into the homologous tyrosine of Kv 11.1 conferred Kv 11.1-like quinine block to Kv 12.1(H462Y). Molecular modelling demonstrated that the low affinity of Kv 12.1 was determined by only weak interactions of residues in the central cavity with quinine. In contrast, more favourable interactions can explain the higher quinine sensitivity of Kv 12.1(H462Y) and Kv 11.1 channels. CONCLUSIONS AND IMPLICATIONS The quinoline-binding "motif" is not conserved within the Eag superfamily, although the overall architecture of these channels is apparently similar. Our findings highlight functional and pharmacological diversity in this group of evolutionary-conserved channels.
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Affiliation(s)
- Marlen Dierich
- Department of Neurophysiology, Institute of Physiology and PathophysiologyPhilipps‐University MarburgMarburgGermany
| | - Willem B. van Ham
- Department of Medical PhysiologyUniversity Medical Center UtrechtUtrechtThe Netherlands
- Department of Pharmacology and ToxicologyUniversity of ViennaViennaAustria
| | | | - Michael G. Leitner
- Department of Neurophysiology, Institute of Physiology and PathophysiologyPhilipps‐University MarburgMarburgGermany
- Division of Physiology, Department of Physiology and Medical PhysicsMedical University of InnsbruckInnsbruckAustria
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Carignano C, Barila EP, Rías EI, Dionisio L, Aztiria E, Spitzmaul G. Inner Hair Cell and Neuron Degeneration Contribute to Hearing Loss in a DFNA2-Like Mouse Model. Neuroscience 2019; 410:202-216. [PMID: 31102762 DOI: 10.1016/j.neuroscience.2019.05.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 04/03/2019] [Accepted: 05/07/2019] [Indexed: 01/19/2023]
Abstract
DFNA2 is a progressive deafness caused by mutations in the voltage-activated potassium channel KCNQ4. Hearing loss develops with age from a mild increase in the hearing threshold to profound deafness. Studies using transgenic mice for Kcnq4 expressed in a mixed background demonstrated the implication of outer hair cells at the initial phase. However, it could not explain the last phase mechanisms of the disease. Genetic backgrounds are known to influence disease expressivity. To unmask the cause of profound deafness phenotype, we backcrossed the Kcnq4 knock-out allele to the inbred strain C3H/HeJ and investigated inner and outer hair cell and spiral ganglion neuron degeneration across the lifespan. In addition to the already reported outer hair cell death, the C3H/HeJ strain also exhibited inner hair cell and spiral ganglion neuron death. We tracked the spatiotemporal survival of cochlear cells by plotting cytocochleograms and neuronal counts at different ages. Cell loss progressed from basal to apical turns with age. Interestingly, the time-course of cell degeneration was different for each cell-type. While for outer hair cells it was already present by week 3, inner hair cell and neuronal loss started 30 weeks later. We also established that outer hair cell loss kinetics slowed down from basal to apical regions correlating with KCNQ4 expression pattern determined in wild-type mice. Our findings indicate that KCNQ4 plays differential roles in each cochlear cell-type impacting in their survival ability. Inner hair cell and spiral ganglion neuron death generates severe hearing loss that could be associated with the last phase of DFNA2.
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Affiliation(s)
- Camila Carignano
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad Nacional del Sur (UNS), Camino La Carrindanga Km 7, B8000FWB, Bahía Blanca, Argentina
| | - Esteban Pablo Barila
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad Nacional del Sur (UNS), Camino La Carrindanga Km 7, B8000FWB, Bahía Blanca, Argentina
| | - Ezequiel Ignacio Rías
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad Nacional del Sur (UNS), Camino La Carrindanga Km 7, B8000FWB, Bahía Blanca, Argentina.; Departamento de Biología, Bioquímica y Farmacia (BByF)-UNS, San Juan 670, 8000 Bahía Blanca, Argentina
| | - Leonardo Dionisio
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad Nacional del Sur (UNS), Camino La Carrindanga Km 7, B8000FWB, Bahía Blanca, Argentina.; Departamento de Biología, Bioquímica y Farmacia (BByF)-UNS, San Juan 670, 8000 Bahía Blanca, Argentina
| | - Eugenio Aztiria
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad Nacional del Sur (UNS), Camino La Carrindanga Km 7, B8000FWB, Bahía Blanca, Argentina.; Departamento de Biología, Bioquímica y Farmacia (BByF)-UNS, San Juan 670, 8000 Bahía Blanca, Argentina
| | - Guillermo Spitzmaul
- Instituto de Investigaciones Bioquímicas de Bahía Blanca (INIBIBB)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)-Universidad Nacional del Sur (UNS), Camino La Carrindanga Km 7, B8000FWB, Bahía Blanca, Argentina.; Departamento de Biología, Bioquímica y Farmacia (BByF)-UNS, San Juan 670, 8000 Bahía Blanca, Argentina..
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Castañeda R, Natarajan S, Jeong SY, Hong BN, Kang TH. Traditional oriental medicine for sensorineural hearing loss: Can ethnopharmacology contribute to potential drug discovery? JOURNAL OF ETHNOPHARMACOLOGY 2019; 231:409-428. [PMID: 30439402 DOI: 10.1016/j.jep.2018.11.016] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 11/06/2018] [Accepted: 11/06/2018] [Indexed: 06/09/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE In Traditional Oriental Medicine (TOM), the development of hearing pathologies is related to an inadequate nourishment of the ears by the kidney and other organs involved in regulation of bodily fluids and nutrients. Several herbal species have historically been prescribed for promoting the production of bodily fluids or as antiaging agents to treat deficiencies in hearing. AIM OF REVIEW The prevalence of hearing loss has been increasing in the last decade and is projected to grow considerably in the coming years. Recently, several herbal-derived products prescribed in TOM have demonstrated a therapeutic potential for acquired sensorineural hearing loss and tinnitus. Therefore, the aims of this review are to provide a comprehensive overview of the current known efficacy of the herbs used in TOM for preventing different forms of acquired sensorineural hearing loss and tinnitus, and associate the traditional principle with the demonstrated pharmacological mechanisms to establish a solid foundation for directing future research. METHODS The present review collected the literature related to herbs used in TOM or related compounds on hearing from Chinese, Korean, and Japanese herbal classics; library catalogs; and scientific databases (PubMed, Scopus, Google Scholar; and Science Direct). RESULTS This review shows that approximately 25 herbal species and 40 active compounds prescribed in TOM for hearing loss and tinnitus have shown in vitro or in vivo beneficial effects for acquired sensorineural hearing loss produced by noise, aging, ototoxic drugs or diabetes. The inner ear is highly vulnerable to ischemia and oxidative damage, where several TOM agents have revealed a direct effect on the auditory system by normalizing the blood supply to the cochlea and increasing the antioxidant defense in sensory hair cells. These strategies have shown a positive impact on maintaining the inner ear potential, sustaining the production of endolymph, reducing the accumulation of toxic and inflammatory substances, preventing sensory cell death and preserving sensory transmission. There are still several herbal species with demonstrated therapeutic efficacy whose mechanisms have not been deeply studied and others that have been traditionally used in hearing loss but have not been tested experimentally. In clinical studies, Ginkgo biloba, Panax ginseng, and Astragalus propinquus have demonstrated to improve hearing thresholds in patients with sensorineural hearing loss and alleviated the symptoms of tinnitus. However, some of these clinical studies have been limited by small sample sizes, lack of an adequate control group or contradictory results. CONCLUSIONS Current therapeutic strategies have proven that the goal of the traditional oriental medicine principle of increasing bodily fluids is a relevant approach for reducing the development of hearing loss by improving microcirculation in the blood-labyrinth barrier and increasing cochlear blood flow. The potential benefits of TOM agents expand to a multi-target approach on different auditory structures of the inner ear related to increased cochlear blood flow, antioxidant, anti-inflammatory, anti-apoptotic and neuroprotective activities. However, more research is required, given the evidence is very limited in terms of the mechanism of action at the preclinical in vivo level and the scarce number of clinical studies published.
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Affiliation(s)
- Rodrigo Castañeda
- Graduate School of Biotechnology, Kyung Hee University, Republic of Korea; Department of Oriental Medicine Biotechnology, College of Life Sciences, Kyung Hee University, Global Campus, Gyeonggi, Republic of Korea.
| | - Sathishkumar Natarajan
- Graduate School of Biotechnology, Kyung Hee University, Republic of Korea; Department of Oriental Medicine Biotechnology, College of Life Sciences, Kyung Hee University, Global Campus, Gyeonggi, Republic of Korea.
| | - Seo Yule Jeong
- Graduate School of Biotechnology, Kyung Hee University, Republic of Korea; Department of Oriental Medicine Biotechnology, College of Life Sciences, Kyung Hee University, Global Campus, Gyeonggi, Republic of Korea.
| | - Bin Na Hong
- Graduate School of Biotechnology, Kyung Hee University, Republic of Korea.
| | - Tong Ho Kang
- Graduate School of Biotechnology, Kyung Hee University, Republic of Korea; Department of Oriental Medicine Biotechnology, College of Life Sciences, Kyung Hee University, Global Campus, Gyeonggi, Republic of Korea.
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Wang X, Chen Y, Tao Y, Gao Y, Yu D, Wu H. A666-conjugated nanoparticles target prestin of outer hair cells preventing cisplatin-induced hearing loss. Int J Nanomedicine 2018; 13:7517-7531. [PMID: 30532536 PMCID: PMC6241721 DOI: 10.2147/ijn.s170130] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Background The delivery of treatment agents to inner ear with drug delivery system (DDS) has been under investigation to overcome the limitations of the conventional therapeutic agents in curing or alleviating the cisplatin ototoxicity. Methods In the present study, a novel targeted dexamethasone (DEX)-loaded DDS, A666-DEX-NP, was constructed for prevention from cisplatin-induced hearing loss. A666-(CLEPRWGFGWWLH) peptides specifically bind to prestin, which is limited to the outer hair cells (OHCs). HEI-OC1 and cisplatin-treated guinea pigs (12 mg/kg, intraperitoneal) were used as in vitro and in vivo models for investigating the targeting and protective efficiency against cisplatin. Results As expected, compared to A666-unconjugated nanoparticles (NP), A666-conjugated coumarin 6-labeled NP showed active targeting to OHCs. Furthermore, A666-coumarin 6-labeled NP could be significantly internalized by HEI-OC1 cells via the A666-prestin interaction. This facilitated the uptake of cells pretreated with A666-DEX-NP, followed by the cisplatin-treated group, which led to enhanced cell viability, reduced apoptotic properties, and decreased reactive oxygen species levels as compared to cells pretreated with DEX or DEX-NP, 4 hours in advance of cisplatin treatment. In cisplatin-treated guinea pigs, pretreatment with A666-DEX-NP effectively preserved OHCs and showed significant hearing protection at 4, 8, and 16 kHz as compared to pretreatment with saline, DEX, or DEX-NP formulation. Conclusion This OHC-targeting DDS provides a novel strategy for DEX application that can be potentially used to combat cisplatin ototoxicity.
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Affiliation(s)
- Xueling Wang
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China, ; .,Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China, ; .,Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, People's Republic of China, ;
| | - Yuming Chen
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China, ; .,Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China, ; .,Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, People's Republic of China, ;
| | - Yong Tao
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China, ; .,Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China, ; .,Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, People's Republic of China, ;
| | - Yunge Gao
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China, ; .,Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China, ; .,Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, People's Republic of China, ;
| | - Dehong Yu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China, ; .,Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China, ; .,Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, People's Republic of China, ;
| | - Hao Wu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China, ; .,Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, People's Republic of China, ; .,Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, People's Republic of China, ;
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Dierich M, Leitner MG. K v12.1 channels are not sensitive to G qPCR-triggered activation of phospholipase Cβ. Channels (Austin) 2018; 12:228-239. [PMID: 30136882 PMCID: PMC6986784 DOI: 10.1080/19336950.2018.1475783] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Kv12.1 K+ channels are expressed in several brain areas, but no physiological function could be attributed to these subunits so far. As genetically-modified animal models are not available, identification of native Kv12.1 currents must rely on characterization of distinct channel properties. Recently, it was shown in Xenopus laevis oocytes that Kv12.1 channels were modulated by membrane PI(4,5)P2. However, it is not known whether these channels are also sensitive to physiologically-relevant PI(4,5)P2 dynamics. We thus studied whether Kv12.1 channels were modulated by activation of phospholipase C β (PLCβ) and found that they were insensitive to receptor-triggered depletion of PI(4,5)P2. Thus, Kv12.1 channels add to the growing list of K+ channels that are insensitive to PLCβ signaling, although modulated by PI(4,5)P2 in Xenopus laevis oocytes.
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Affiliation(s)
- Marlen Dierich
- a Department of Neurophysiology , Institute of Physiology and Pathophysiology, Philipps-University Marburg , Marburg , Germany
| | - Michael G Leitner
- a Department of Neurophysiology , Institute of Physiology and Pathophysiology, Philipps-University Marburg , Marburg , Germany.,b Division of Physiology, Department of Physiology and Medical Physics , Medical University of Innsbruck , Innsbruck , Austria
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Leitner MG, Thallmair V, Wilke BU, Neubert V, Kronimus Y, Halaszovich CR, Oliver D. The N-terminal homology (ENTH) domain of Epsin 1 is a sensitive reporter of physiological PI(4,5)P 2 dynamics. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1864:433-442. [PMID: 30670192 DOI: 10.1016/j.bbalip.2018.08.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 06/18/2018] [Accepted: 08/04/2018] [Indexed: 11/15/2022]
Abstract
Phospholipase Cβ (PLCβ)-induced depletion of phosphatidylinositol-(4,5)-bisphosphate (PI(4,5)P2) transduces a plethora of signals into cellular responses. Importance and diversity of PI(4,5)P2-dependent processes led to strong need for biosensors of physiological PI(4,5)P2 dynamics applicable in live-cell experiments. Membrane PI(4,5)P2 can be monitored with fluorescently-labelled phosphoinositide (PI) binding domains that associate to the membrane depending on PI(4,5)P2 levels. The pleckstrin homology domain of PLCδ1 (PLCδ1-PH) and the C-terminus of tubby protein (tubbyCT) are two such sensors widely used to study PI(4,5)P2 signaling. However, certain limitations apply to both: PLCδ1-PH binds cytoplasmic inositol-1,4,5-trisphosphate (IP3) produced from PI(4,5)P2 through PLCβ, and tubbyCT responses do not faithfully report on PLCβ-dependent PI(4,5)P2 dynamics. In searching for an improved biosensor, we fused N-terminal homology domain of Epsin1 (ENTH) to GFP and examined use of this construct as genetically-encoded biosensor for PI(4,5)P2 dynamics in living cells. We utilized recombinant tools to manipulate PI or Gq protein-coupled receptors (GqPCR) to stimulate PLCβ signaling and characterized PI binding properties of ENTH-GFP with total internal reflection (TIRF) and confocal microscopy. ENTH-GFP specifically recognized membrane PI(4,5)P2 without interacting with IP3, as demonstrated by dialysis of cells with the messenger through a patch pipette. Utilizing Ci-VSP to titrate PI(4,5)P2 levels, we found that ENTH-GFP had low PI(4,5)P2 affinity. Accordingly, ENTH-GFP was highly sensitive to PLCβ-dependent PI(4,5)P2 depletion, and in contrast to PLCδ1-PH, overexpression of ENTH-GFP did not attenuate GqPCR signaling. Taken together, ENTH-GFP detects minute changes of PI(4,5)P2 levels and provides an important complementation of experimentally useful reporters of PI(4,5)P2 dynamics in physiological pathways.
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Affiliation(s)
- Michael G Leitner
- Division of Physiology, Department of Physiology and Medical Physics, Medical University of Innsbruck, 6020 Innsbruck, Austria; Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037 Marburg, Germany.
| | - Veronika Thallmair
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037 Marburg, Germany
| | - Bettina U Wilke
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037 Marburg, Germany
| | - Valentin Neubert
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037 Marburg, Germany
| | - Yannick Kronimus
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037 Marburg, Germany
| | - Christian R Halaszovich
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037 Marburg, Germany
| | - Dominik Oliver
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps-University Marburg, 35037 Marburg, Germany; DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodeling, GRK 2213, Philipps-University, Germany; Center for Mind, Brain and Behavior (CMBB), Universities of Marburg and Giessen, Germany
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28
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Dierich M, Evers S, Wilke BU, Leitner MG. Inverse Modulation of Neuronal K v12.1 and K v11.1 Channels by 4-Aminopyridine and NS1643. Front Mol Neurosci 2018; 11:11. [PMID: 29440988 PMCID: PMC5797642 DOI: 10.3389/fnmol.2018.00011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 01/09/2018] [Indexed: 01/24/2023] Open
Abstract
The three members of the ether-à-go-go-gene-like (Elk; Kv12.1-Kv12.3) family of voltage-gated K+ channels are predominantly expressed in neurons, but only little information is available on their physiological relevance. It was shown that Kv12.2 channels modulate excitability of hippocampal neurons, but no native current could be attributed to Kv12.1 and Kv12.3 subunits yet. This may appear somewhat surprising, given high expression of their mRNA transcripts in several brain areas. Native Kv12 currents may have been overlooked so far due to limited knowledge on their biophysical properties and lack of specific pharmacology. Except for Kv12.2, appropriate genetically modified mouse models have not been described; therefore, identification of Kv12-mediated currents in native cell types must rely on characterization of unique properties of the channels. We focused on recombinant human Kv12.1 to identify distinct properties of these channels. We found that Kv12.1 channels exhibited significant mode shift of activation, i.e., stabilization of the voltage sensor domain in a “relaxed” open state after prolonged channel activation. This mode shift manifested by a slowing of deactivation and, most prominently, a significant shift of voltage dependence to hyperpolarized potentials. In contrast to related Kv11.1, mode shift was not sensitive to extracellular Na+, which allowed for discrimination between these isoforms. Sensitivity of Kv12.1 and Kv11.1 to the broad-spectrum K+ antagonist 4-aminopyridine was similar. However, 4-AP strongly activated Kv12.1 channels, but it was an inhibitor of Kv11 channels. Interestingly, the agonist of Kv11 channels NS1643 also differentially modulated the activity of these channels, i.e., NS1643 activated Kv11.1, but strongly inhibited Kv12.1 channels. Thus, these closely related channels are distinguished by inverse pharmacological profiles. In summary, we identified unique biophysical and pharmacological properties of Kv12.1 channels and established straightforward experimental protocols to characterize Kv12.1-mediated currents. Identification of currents in native cell types with mode shift that are activated through 4-AP and inhibited by NS1643 can provide strong evidence for contribution of Kv12.1 to whole cell currents.
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Affiliation(s)
- Marlen Dierich
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University of Marburg, Marburg, Germany
| | - Saskia Evers
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University of Marburg, Marburg, Germany
| | - Bettina U Wilke
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University of Marburg, Marburg, Germany
| | - Michael G Leitner
- Department of Neurophysiology, Institute of Physiology and Pathophysiology, Philipps University of Marburg, Marburg, Germany.,Division of Physiology, Department of Physiology and Medical Physics, Innsbruck Medical University, Innsbruck, Austria
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29
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Yan S, Lu Y, He L, Zhao X, Wu L, Zhu H, Jiang M, Su Y, Cao W, Tian W, Xing Q. Dynamic Editome of Zebrafish under Aminoglycosides Treatment and Its Potential Involvement in Ototoxicity. Front Pharmacol 2017; 8:854. [PMID: 29213239 PMCID: PMC5702851 DOI: 10.3389/fphar.2017.00854] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 11/08/2017] [Indexed: 11/17/2022] Open
Abstract
RNA editing is an important co- and post-transcriptional event that generates RNA and protein diversity. Aminoglycosides are a group of bactericidal antibiotics and a mainstay of antimicrobial therapy for several life-threatening infections. However, aminoglycosides can induce ototoxicity, resulting in damage to the organs responsible for hearing and balance. At low concentrations, aminoglycosides can bind to many RNA sequences and critically influence RNA editing. We used a bioinformatics approach to investigate the effect of aminoglycosides on global mRNA editing events to gain insight into the interactions between mRNA editing and aminoglycoside ototoxicity. We identified 6,850 mRNA editing sites in protein coding genes in embryonic zebrafish, and in about 10% of these, the degree of RNA editing changed more than 15% under aminoglycosides treatment. Twelve ear-development or ototoxicity related genes, including plekhm1, fgfr1a, sox9a, and calrl2, exhibited remarkable changes in mRNA editing levels in zebrafish treated with aminoglycosides. Our results indicate that aminoglycosides may have a widespread and complicated influence on the progress of mRNA editing and expression. Furthermore, these results highlight the potential importance of mRNA editing in the pathogenesis and etiology of aminoglycoside-induced ototoxicity.
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Affiliation(s)
- Sijia Yan
- Institutes of Biomedical Sciences and Children's Hospital, Fudan University, Shanghai, China
| | - Yulan Lu
- Children's Hospital, Fudan University, Shanghai, China
| | - Lin He
- Institutes of Biomedical Sciences and Children's Hospital, Fudan University, Shanghai, China.,Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, China
| | - Xinzhi Zhao
- Institutes of Biomedical Sciences and Children's Hospital, Fudan University, Shanghai, China
| | - Lihua Wu
- Zhengzhou People's Hospital, Zhengzhou, China
| | - Huizhong Zhu
- Institutes of Biomedical Sciences and Children's Hospital, Fudan University, Shanghai, China
| | - Menglin Jiang
- Institutes of Biomedical Sciences and Children's Hospital, Fudan University, Shanghai, China
| | - Yu Su
- Institutes of Biomedical Sciences and Children's Hospital, Fudan University, Shanghai, China
| | - Wei Cao
- Zhengzhou Central Hospital, Zhengzhou University, Zhengzhou, China
| | - Weidong Tian
- Department of Biostatistics and Computational Biology, School of Life Science, Fudan University, Shanghai, China
| | - Qinghe Xing
- Institutes of Biomedical Sciences and Children's Hospital, Fudan University, Shanghai, China
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Esposito S, Canevini MP, Principi N. Complications associated with antibiotic administration: neurological adverse events and interference with antiepileptic drugs. Int J Antimicrob Agents 2017; 50:1-8. [PMID: 28414069 DOI: 10.1016/j.ijantimicag.2017.01.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Accepted: 01/28/2017] [Indexed: 11/19/2022]
Abstract
Antibiotic use is associated with toxic effects involving the peripheral and central nervous systems and it may interfere with antiepileptic drugs, causing significant variations in their serum levels and activity. Prompt identification of neurological complications during antibiotic therapy is important in order to make appropriate modifications to medication. Characteristics of the drug and the patient, including age and underlying diseases, may favour these complications. The main aim of this study was to review the neurological adverse events that may follow antibiotic administration, the mechanisms that cause them, and the possibility of prevention and treatment. Moreover, the interference of antibiotics with serum levels and the activity of antiepileptic drugs are discussed. The results demonstrate that antibiotic-associated adverse events involving the nervous system are relatively uncommon and are only rarely severe and irreversible, although neurotoxicity has been reported for several antibiotics. Moreover, for patients receiving antiepileptic drugs, monitoring of drug serum levels to avoid the risk of toxicity or inadequate therapy is mandatory during antibiotic treatment. Areas for future research include the effects of combined antibiotic therapies as well as multiple antiepileptic drugs in study populations with an adequate sample size, including neonates and infants, patients with pharmacoresistant epilepsy and elderly patients.
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Affiliation(s)
- Susanna Esposito
- Pediatric Clinic, Università degli Studi di Perugia, Perugia, Italy.
| | - Maria Paola Canevini
- Child Neurology Unit-Epilepsy Center, San Paolo Hospital, Department of Health Sciences, Università degli Studi di Milano, Milan, Italy
| | - Nicola Principi
- Pediatric Highly Intensive Care Unit, Department of Pathophysiology and Transplantation, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Università degli Studi di Milano, Milan, Italy
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31
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Leitner MG, Michel N, Behrendt M, Dierich M, Dembla S, Wilke BU, Konrad M, Lindner M, Oberwinkler J, Oliver D. Direct modulation of TRPM4 and TRPM3 channels by the phospholipase C inhibitor U73122. Br J Pharmacol 2016; 173:2555-69. [PMID: 27328745 DOI: 10.1111/bph.13538] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 06/10/2016] [Accepted: 06/15/2016] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND AND PURPOSE Signalling through phospholipase C (PLC) controls many cellular processes. Much information on the relevance of this important pathway has been derived from pharmacological inhibition of the enzymatic activity of PLC. We found that the most frequently employed PLC inhibitor, U73122, activates endogenous ionic currents in widely used cell lines. Given the extensive use of U73122 in research, we set out to identify these U73122-sensitive ion channels. EXPERIMENTAL APPROACH We performed detailed biophysical analysis of the U73122-induced currents in frequently used cell lines. KEY RESULTS At concentrations required to inhibit PLC, U73122 modulated the activity of transient receptor potential melastatin (TRPM) channels through covalent modification. U73122 was shown to be a potent agonist of ubiquitously expressed TRPM4 channels and activated endogenous TRPM4 channels in CHO cells independently of PLC and of the downstream second messengers PI(4,5)P2 and Ca(2+) . U73122 also potentiated Ca(2) (+) -dependent TRPM4 currents in human Jurkat T-cells, endogenous TRPM4 in HEK293T cells and recombinant human TRPM4. In contrast to TRPM4, TRPM3 channels were inhibited whereas the closely related TRPM5 channels were insensitive to U73122, showing that U73122 exhibits high specificity within the TRPM channel family. CONCLUSIONS AND IMPLICATIONS Given the widespread expression of TRPM4 and TRPM3 channels, these actions of U73122 must be considered when interpreting its effects on cell function. U73122 may also be useful for identifying and characterizing TRPM channels in native tissue, thus facilitating the analysis of their physiology.
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Affiliation(s)
- Michael G Leitner
- Institute of Physiology and Pathophysiology, Department of Neurophysiology, Philipps-University Marburg, Marburg, Germany
| | - Niklas Michel
- Institute of Physiology and Pathophysiology, Department of Neurophysiology, Philipps-University Marburg, Marburg, Germany
| | - Marc Behrendt
- Institute of Physiology and Pathophysiology, Department of Neurophysiology, Philipps-University Marburg, Marburg, Germany
| | - Marlen Dierich
- Institute of Physiology and Pathophysiology, Department of Neurophysiology, Philipps-University Marburg, Marburg, Germany
| | - Sandeep Dembla
- Institute of Physiology and Pathophysiology, Department of Neurophysiology, Philipps-University Marburg, Marburg, Germany
| | - Bettina U Wilke
- Institute of Physiology and Pathophysiology, Department of Neurophysiology, Philipps-University Marburg, Marburg, Germany
| | - Maik Konrad
- Institute of Physiology and Pathophysiology, Department of Neurophysiology, Philipps-University Marburg, Marburg, Germany
| | - Moritz Lindner
- Institute of Physiology and Pathophysiology, Department of Neurophysiology, Philipps-University Marburg, Marburg, Germany.,Department of Ophthalmology, University of Bonn, Bonn, Germany
| | - Johannes Oberwinkler
- Institute of Physiology and Pathophysiology, Department of Neurophysiology, Philipps-University Marburg, Marburg, Germany
| | - Dominik Oliver
- Institute of Physiology and Pathophysiology, Department of Neurophysiology, Philipps-University Marburg, Marburg, Germany
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Tóth BI, Konrad M, Ghosh D, Mohr F, Halaszovich CR, Leitner MG, Vriens J, Oberwinkler J, Voets T. Regulation of the transient receptor potential channel TRPM3 by phosphoinositides. ACTA ACUST UNITED AC 2016; 146:51-63. [PMID: 26123194 PMCID: PMC4485019 DOI: 10.1085/jgp.201411339] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
TRPM3 is dynamically regulated by plasma membrane PI(4,5)P2 and related PIPs. The transient receptor potential (TRP) channel TRPM3 is a calcium-permeable cation channel activated by heat and by the neurosteroid pregnenolone sulfate (PregS). TRPM3 is highly expressed in sensory neurons, where it plays a key role in heat sensing and inflammatory hyperalgesia, and in pancreatic β cells, where its activation enhances glucose-induced insulin release. However, despite its functional importance, little is known about the cellular mechanisms that regulate TRPM3 activity. Here, we provide evidence for a dynamic regulation of TRPM3 by membrane phosphatidylinositol phosphates (PIPs). Phosphatidylinositol 4,5-bisphosphate (PI[4,5]P2) and ATP applied to the intracellular side of excised membrane patches promote recovery of TRPM3 from desensitization. The stimulatory effect of cytosolic ATP on TRPM3 reflects activation of phosphatidylinositol kinases (PI-Ks), leading to resynthesis of PIPs in the plasma membrane. Various PIPs directly enhance TRPM3 activity in cell-free inside-out patches, with a potency order PI(3,4,5)P3 > PI(3,5)P2 > PI(4,5)P2 ≈ PI(3,4)P2 >> PI(4)P. Conversely, TRPM3 activity is rapidly and reversibly inhibited by activation of phosphatases that remove the 5-phosphate from PIPs. Finally, we show that recombinant TRPM3, as well as the endogenous TRPM3 in insuloma cells, is rapidly and reversibly inhibited by activation of phospholipase C–coupled muscarinic acetylcholine receptors. Our results reveal basic cellular mechanisms whereby membrane receptors can regulate TRPM3 activity.
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Affiliation(s)
- Balázs I Tóth
- Laboratory of Ion Channel Research and TRP Research Platform Leuven (TRPLe) and Laboratory of Obstetrics and Experimental Gynaecology, KU Leuven, 3000 Leuven, Belgium
| | - Maik Konrad
- Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, 35037 Marburg, Germany
| | - Debapriya Ghosh
- Laboratory of Ion Channel Research and TRP Research Platform Leuven (TRPLe) and Laboratory of Obstetrics and Experimental Gynaecology, KU Leuven, 3000 Leuven, Belgium
| | - Florian Mohr
- Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, 35037 Marburg, Germany
| | - Christian R Halaszovich
- Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, 35037 Marburg, Germany
| | - Michael G Leitner
- Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, 35037 Marburg, Germany
| | - Joris Vriens
- Laboratory of Ion Channel Research and TRP Research Platform Leuven (TRPLe) and Laboratory of Obstetrics and Experimental Gynaecology, KU Leuven, 3000 Leuven, Belgium Laboratory of Ion Channel Research and TRP Research Platform Leuven (TRPLe) and Laboratory of Obstetrics and Experimental Gynaecology, KU Leuven, 3000 Leuven, Belgium
| | - Johannes Oberwinkler
- Institut für Physiologie und Pathophysiologie, Philipps-Universität Marburg, 35037 Marburg, Germany
| | - Thomas Voets
- Laboratory of Ion Channel Research and TRP Research Platform Leuven (TRPLe) and Laboratory of Obstetrics and Experimental Gynaecology, KU Leuven, 3000 Leuven, Belgium
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Schmitz HM, Johnson SB, Santi PA. Kanamycin-furosemide ototoxicity in the mouse cochlea: a 3-dimensional analysis. Otolaryngol Head Neck Surg 2014; 150:666-72. [PMID: 24415490 DOI: 10.1177/0194599813519071] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVE Administration of an aminoglycoside antibiotic and loop diuretic causes damage to hair cells in the organ of Corti, resulting in their death and the death of their corresponding spiral ganglion neurons. While this phenomenon has been studied previously, analysis of its effects in the whole cochlea has not been reported. The authors sought to evaluate the effects of a combination dose of kanamycin and furosemide in mice cochlea using an imaging system and computer analysis that allowed for nondestructive, whole-cochlea visualization. STUDY DESIGN Study using an animal model. SETTING Cochlear analysis laboratory. SUBJECTS AND METHODS Five mice received kanamycin and furosemide and 3 mice received saline. Cochleas were harvested and imaged with scanning thin-sheet laser imaging microscopy (sTSLIM) to analyze sensory cells and cochlea structures. RESULTS The drug-treated animals showed substantial loss of inner hair cells and complete outer hair cell loss. All treated mice showed spiral ganglion neuron loss with fewer neurons than control animals and decreased cell density in the middle turn of the cochlea. The spiral ligament and spiral limbus in the treated animals also showed a decrease in fibrocyte cell density in the middle to apical portion of the cochlea. The stria vascularis appeared normal in all animals. CONCLUSION Imaging methods that allow for whole-cochlea analysis provide insight into changes that occur in the cochlea after ototoxic insult. Trends that may not be apparent in cross-section samples of the cochlea can be observed. Computer analysis of these trends allows them to be assessed accurately.
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Affiliation(s)
- Heather M Schmitz
- Department of Otolaryngology, University of Minnesota, Minneapolis, Minnesota, USA
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Wang T, Yang YQ, Karasawa T, Wang Q, Phillips A, Guan BC, Ma KT, Jiang M, Xie DH, Steyger PS, Jiang ZG. Bumetanide hyperpolarizes madin-darby canine kidney cells and enhances cellular gentamicin uptake by elevating cytosolic Ca(2+) thus facilitating intermediate conductance Ca(2+)--activated potassium channels. Cell Biochem Biophys 2013; 65:381-98. [PMID: 23109177 DOI: 10.1007/s12013-012-9442-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Loop diuretics such as bumetanide and furosemide enhance aminoglycoside ototoxicity when co-administered to patients and animal models. The underlying mechanism(s) is poorly understood. We investigated the effect of these diuretics on cellular uptake of aminoglycosides, using Texas Red-tagged gentamicin (GTTR), and intracellular/whole-cell recordings of Madin-Darby canine kidney (MDCK) cells. We found that bumetanide and furosemide dose-dependently enhanced cytoplasmic GTTR fluorescence by ~60 %. This enhancement was suppressed by La(3+), a non-selective cation channel (NSCC) blocker, and by K(+) channel blockers Ba(2+) and clotrimazole, but not by tetraethylammonium (TEA), 4-aminopyridine (4-AP) or glipizide, nor by Cl(-) channel blockers diphenylamine-2-carboxylic acid (DPC), niflumic acid (NFA), and CFTRinh-172. Bumetanide and furosemide hyperpolarized MDCK cells by ~14 mV, increased whole-cell I/V slope conductance; the bumetanide-induced net current I/V showed a reversal potential (V r) ~-80 mV. Bumetanide-induced hyperpolarization and I/V change was suppressed by Ba(2+) or clotrimazole, and absent in elevated [Ca(2+)]i, but was not affected by apamin, 4-AP, TEA, glipizide, DPC, NFA, or CFTRinh-172. Bumetanide and furosemide stimulated a surge of Fluo-4-indicated cytosolic Ca(2+). Ba(2+) and clotrimazole alone depolarized cells by ~18 mV and reduced I/V slope with a net current V r near -85 mV, and reduced GTTR uptake by ~20 %. La(3+) alone hyperpolarized the cells by ~-14 mV, reduced the I/V slope with a net current V r near -10 mV, and inhibited GTTR uptake by ~50 %. In the presence of La(3+), bumetanide-caused negligible change in potential or I/V. We conclude that NSCCs constitute a major cell entry pathway for cationic aminoglycosides; bumetanide enhances aminoglycoside uptake by hyperpolarizing cells that increases the cation influx driving force; and bumetanide-induced hyperpolarization is caused by elevating intracellular Ca(2+) and thus facilitating activation of the intermediate conductance Ca(2+)-activated K(+) channels.
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Affiliation(s)
- Tian Wang
- Oregon Hearing Research Center, NRC04, Department of Otolaryngology, Oregon Health & Science University, Portland, OR 97239, USA
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Svalø J, Bille M, Parameswaran Theepakaran N, Sheykhzade M, Nordling J, Bouchelouche P. Bladder contractility is modulated by Kv7 channels in pig detrusor. Eur J Pharmacol 2013; 715:312-20. [PMID: 23707187 DOI: 10.1016/j.ejphar.2013.05.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 04/28/2013] [Accepted: 05/11/2013] [Indexed: 12/15/2022]
Abstract
Kv7 channels are involved in smooth muscle relaxation, and accordingly we believe that they constitute potential targets for the treatment of overactive bladder syndrome. We have therefore used myography to examine the function of Kv7 channels in detrusor, i.e. pig bladder, with a view to determining the effects of the following potassium channel activators: ML213 (Kv7.2/Kv7.4 channels) and retigabine (Kv7.2-7.5 channels). Retigabine produced a concentration-dependent relaxation of carbachol- and electric field-induced contractions. The potency was similar in magnitude to that of ML213-induced relaxation, suggesting that Kv7.2 and/or Kv7.4 channels constitute the subtypes that are relevant to bladder contractility. The effects of retigabine and ML213 were attenuated by pre-incubation with 10µM XE991 (Kv7.1-7.5 channel blocker) (P<0.05), which in turn confirmed Kv7 channel selectivity. Subtype-selective effects were further investigated by incubating the detrusor with 10µM chromanol 293B (Kv7.1 channel blocker). Regardless of the experimental protocol, this did not cause a further increase in the evoked contraction. In contrast, the addition of XE991 potentiated the KCl-induced contractions, but not those induced by carbachol or electric field, indicating the presence of a phosphatidyl-inositol-4,5-biphosphate-dependent mechanism amongst the Kv7 channels in detrusor. qRT-PCR studies of the mRNA transcript level of Kv7.3-7.5 channels displayed a higher level of Kv7.4 transcript in detrusor compared to that present in brain cortex and heart tissues. Thus, we have shown that Kv7.4 channels are expressed and functionally active in pig detrusor, and that the use of selective Kv7.4 channel modulators in the treatment of detrusor overactivity seems promising.
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Affiliation(s)
- Julie Svalø
- Smooth Muscle Research Center, Department of Clinical Biochemistry, Copenhagen University Hospital at Koege, Denmark.
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Tan J, Prakash MD, Kaiserman D, Bird PI. Absence of SERPINB6A causes sensorineural hearing loss with multiple histopathologies in the mouse inner ear. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 183:49-59. [PMID: 23669344 DOI: 10.1016/j.ajpath.2013.03.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Revised: 02/28/2013] [Accepted: 03/05/2013] [Indexed: 11/26/2022]
Abstract
A homozygous mutation of SERPINB6, a gene encoding an intracellular protease inhibitor, has recently been associated with post-lingual, autosomal-recessive, nonsyndromic hearing loss in humans (DFNB91). Herein, we describe the physiological changes underlying SERPINB6 deficiency by analyzing mutant mice in which the orthologous gene is replaced by enhanced green fluorescent protein. SERPINB6A is present in the neurosensory epithelium, lateral wall, and spiral limbus of the cochlea, with highest levels in the inner and outer hair cells of the organ of Corti, cells lining the inner sulcus, and supporting cells distributed along the epithelial gap junction layer to the outer sulcus. Measurements of hearing thresholds in these mice demonstrated age-related hearing loss in all homozygous-null, but not heterozygous, mice. Hearing impairment was first detected at 3 weeks of age, affecting only high frequencies before spreading to other frequencies as the mice aged. The defect is associated with progressive cellular degeneration within the cochlea. This begins with the hair cells, then involves the primary auditory neurons, and, finally, the fibrocytes in the lateral wall. These findings establish these mutant mice as a suitable model system to elucidate how SERPINB6 deficiency causes deafness in humans.
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Affiliation(s)
- Justin Tan
- Department of Otolaryngology, University of Melbourne, East Melbourne, Australia
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Mann SE, Johnson M, Meredith FL, Rennie KJ. Inhibition of K+ Currents in Type I Vestibular Hair Cells by Gentamicin and Neomycin. ACTA ACUST UNITED AC 2013; 18:317-26. [DOI: 10.1159/000354056] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Accepted: 06/24/2013] [Indexed: 11/19/2022]
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Schacht J, Talaska AE, Rybak LP. Cisplatin and aminoglycoside antibiotics: hearing loss and its prevention. Anat Rec (Hoboken) 2012; 295:1837-50. [PMID: 23045231 DOI: 10.1002/ar.22578] [Citation(s) in RCA: 244] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Accepted: 07/24/2012] [Indexed: 12/19/2022]
Abstract
This review introduces the pathology of aminoglycoside antibiotic and the cisplatin chemotherapy classes of drugs, discusses oxidative stress in the inner ear as a primary trigger for cell damage, and delineates the ensuing cell death pathways. Among potentially ototoxic (damaging the inner ear) therapeutics, the platinum-based anticancer drugs and the aminoglycoside antibiotics are of critical clinical importance. Both drugs cause sensorineural hearing loss in patients, a side effect that can be reproduced in experimental animals. Hearing loss is reflected primarily in damage to outer hair cells, beginning in the basal turn of the cochlea. In addition, aminoglycosides might affect the vestibular system while cisplatin seems to have a much lower likelihood to do so. Finally, based on an understanding the mechanisms of ototoxicity pharmaceutical ways of protection of the cochlea are presented.
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Affiliation(s)
- Jochen Schacht
- Department of Otolaryngology, Kresge Hearing Research Institute, University of Michigan, Ann Arbor, Michigan 48109-5616, USA.
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Leitner MG, Feuer A, Ebers O, Schreiber DN, Halaszovich CR, Oliver D. Restoration of ion channel function in deafness-causing KCNQ4 mutants by synthetic channel openers. Br J Pharmacol 2012; 165:2244-59. [PMID: 21951272 DOI: 10.1111/j.1476-5381.2011.01697.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND AND PURPOSE DFNA2 is a frequent hereditary hearing disorder caused by loss-of-function mutations in the voltage-gated potassium channel KCNQ4 (Kv7.4). KCNQ4 mediates the predominant K(+) conductance, I(K,n) , of auditory outer hair cells (OHCs), and loss of KCNQ4 function leads to degeneration of OHCs resulting in progressive hearing loss. Here we explore the possible recovery of channel activity of mutant KCNQ4 induced by synthetic KCNQ channel openers. EXPERIMENTAL APPROACH Whole cell patch clamp recordings were performed on CHO cells transiently expressing KCNQ4 wild-type (wt) and DFNA2-relevant mutants, and from acutely isolated OHCs. KEY RESULTS Various known KCNQ channel openers robustly enhanced KCNQ4 currents. The strongest potentiation was observed with a combination of zinc pyrithione plus retigabine. A similar albeit less pronounced current enhancement was observed with native I(K,n) currents in rat OHCs. DFNA2 mutations located in the channel's pore region abolished channel function and these mutant channels were completely unresponsive to channel openers. However, the function of a DFNA2 mutation located in the proximal C-terminus was restored by the combined application of both openers. Co-expression of wt and KCNQ4 pore mutants suppressed currents to barely detectable levels. In this dominant-negative situation, channel openers essentially restored currents back to wt levels, most probably through strong activation of only the small fraction of homomeric wt channels. CONCLUSIONS AND IMPLICATIONS Our data suggest that by stabilizing the KCNQ4-mediated conductance in OHCs, chemical channel openers can protect against OHC degeneration and progression of hearing loss in DFNA2.
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Affiliation(s)
- Michael G Leitner
- Department of Neurophysiology, Philipps-University Marburg, Marburg, Germany
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Matt T, Ng CL, Lang K, Sha SH, Akbergenov R, Shcherbakov D, Meyer M, Duscha S, Xie J, Dubbaka SR, Perez-Fernandez D, Vasella A, Ramakrishnan V, Schacht J, Böttger EC. Dissociation of antibacterial activity and aminoglycoside ototoxicity in the 4-monosubstituted 2-deoxystreptamine apramycin. Proc Natl Acad Sci U S A 2012; 109:10984-9. [PMID: 22699498 PMCID: PMC3390888 DOI: 10.1073/pnas.1204073109] [Citation(s) in RCA: 160] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Aminoglycosides are potent antibacterials, but therapy is compromised by substantial toxicity causing, in particular, irreversible hearing loss. Aminoglycoside ototoxicity occurs both in a sporadic dose-dependent and in a genetically predisposed fashion. We recently have developed a mechanistic concept that postulates a key role for the mitochondrial ribosome (mitoribosome) in aminoglycoside ototoxicity. We now report on the surprising finding that apramycin, a structurally unique aminoglycoside licensed for veterinary use, shows little activity toward eukaryotic ribosomes, including hybrid ribosomes which were genetically engineered to carry the mitoribosomal aminoglycoside-susceptibility A1555G allele. In ex vivo cultures of cochlear explants and in the in vivo guinea pig model of chronic ototoxicity, apramycin causes only little hair cell damage and hearing loss but it is a potent antibacterial with good activity against a range of clinical pathogens, including multidrug-resistant Mycobacterium tuberculosis. These data provide proof of concept that antibacterial activity can be dissected from aminoglycoside ototoxicity. Together with 3D structures of apramycin-ribosome complexes at 3.5-Å resolution, our results provide a conceptual framework for further development of less toxic aminoglycosides by hypothesis-driven chemical synthesis.
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Affiliation(s)
- Tanja Matt
- Institut für Medizinische Mikrobiologie, Universität Zürich, 8006 Zürich, Switzerland
| | - Chyan Leong Ng
- Structural Studies Division, Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Kathrin Lang
- Structural Studies Division, Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Su-Hua Sha
- Kresge Hearing Research Institute, Department of Otolaryngology, Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109; and
| | - Rashid Akbergenov
- Institut für Medizinische Mikrobiologie, Universität Zürich, 8006 Zürich, Switzerland
| | - Dmitri Shcherbakov
- Institut für Medizinische Mikrobiologie, Universität Zürich, 8006 Zürich, Switzerland
| | - Martin Meyer
- Institut für Medizinische Mikrobiologie, Universität Zürich, 8006 Zürich, Switzerland
| | - Stefan Duscha
- Institut für Medizinische Mikrobiologie, Universität Zürich, 8006 Zürich, Switzerland
| | - Jing Xie
- Kresge Hearing Research Institute, Department of Otolaryngology, Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109; and
| | - Srinivas R. Dubbaka
- Laboratorium für Organische Chemie, Eidgenössische Technische Hochschule Zürich, 8093 Zürich, Switzerland
| | - Déborah Perez-Fernandez
- Laboratorium für Organische Chemie, Eidgenössische Technische Hochschule Zürich, 8093 Zürich, Switzerland
| | - Andrea Vasella
- Laboratorium für Organische Chemie, Eidgenössische Technische Hochschule Zürich, 8093 Zürich, Switzerland
| | - V. Ramakrishnan
- Structural Studies Division, Medical Research Council (MRC) Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Jochen Schacht
- Kresge Hearing Research Institute, Department of Otolaryngology, Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109; and
| | - Erik C. Böttger
- Institut für Medizinische Mikrobiologie, Universität Zürich, 8006 Zürich, Switzerland
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Surovtseva EV, Johnston AH, Zhang W, Zhang Y, Kim A, Murakoshi M, Wada H, Newman TA, Zou J, Pyykkö I. Prestin binding peptides as ligands for targeted polymersome mediated drug delivery to outer hair cells in the inner ear. Int J Pharm 2011; 424:121-7. [PMID: 22227343 DOI: 10.1016/j.ijpharm.2011.12.042] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 12/21/2011] [Accepted: 12/22/2011] [Indexed: 12/16/2022]
Abstract
Targeted delivery of treatment agents to the inner ear using nanoparticles is an advanced therapeutic approach to cure or alleviate hearing loss. Designed to target the outer hair cells of the cochlea, two 12-mer peptides (A(665) and A(666)) with affinity to prestin were identified following 3 rounds of sequential phage display. Two-round display with immobilized prestin protein was used to enrich the library for full-length prestin. The last round was performed using Cos-7 cells transiently transfected with a cCFP-prestin plasmid to display phages expressing peptides restrictive to the extracellular loops of prestin. The binding properties of A(665) and A(666) shown by flow cytometry demonstrated selectivity to prestin-expressing Chinese hamster ovary cells. PEG6K-b-PCL19K polymersomes covalently labelled with these peptides demonstrated effective targeting to outer hair cells in a rat cochlear explant study.
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Karasawa T, Steyger PS. Intracellular mechanisms of aminoglycoside-induced cytotoxicity. Integr Biol (Camb) 2011; 3:879-86. [PMID: 21799993 DOI: 10.1039/c1ib00034a] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Since introduction into clinical practice over 60 years ago, aminoglycoside antibiotics remain important drugs in the treatment of bacterial infections, cystic fibrosis and tuberculosis. However, the ototoxic and nephrotoxic properties of these drugs are still a major clinical problem. Recent advances in molecular biology and biochemistry have begun to uncover the intracellular actions of aminoglycosides that lead to cytotoxicity. In this review, we discuss intracellular binding targets of aminoglycosides, highlighting specific aminoglycoside-binding proteins (HSP73, calreticulin and CLIMP-63) and their potential for triggering caspases and Bcl-2 signalling cascades that are involved in aminoglycoside-induced cytotoxicity. We also discuss potential strategies to reduce aminoglycoside cytotoxicity, which are necessary for greater bactericidal efficacy during aminoglycoside pharmacotherapy.
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Affiliation(s)
- Takatoshi Karasawa
- Oregon Hearing Research Center, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
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Xie J, Talaska AE, Schacht J. New developments in aminoglycoside therapy and ototoxicity. Hear Res 2011; 281:28-37. [PMID: 21640178 DOI: 10.1016/j.heares.2011.05.008] [Citation(s) in RCA: 190] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Revised: 04/26/2011] [Accepted: 05/11/2011] [Indexed: 01/13/2023]
Abstract
After almost seven decades in clinical use, aminoglycoside antibiotics still remain indispensible drugs for acute infections and specific indications such as tuberculosis or the containment of pseudomonas bacteria in patients with cystic fibrosis. The review will describe the pathology and pathophysiology of aminoglycoside-induced auditory and vestibular toxicity in humans and experimental animals and explore contemporary views of the mechanisms of cell death. It will also outline the current state of protective therapy and recent advances in the development of aminoglycoside derivatives with low toxicity profiles for antimicrobial treatment and for stop-codon suppression in the attenuation of genetic disorders.
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Affiliation(s)
- Jing Xie
- Kresge Hearing Research Institute, University of Michigan, 1150 West Medical Center Drive, Ann Arbor, MI 48109-5616, USA
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