1
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Xu S, Yang N. The Role and Research Progress of Mitochondria in Sensorineural Hearing Loss. Mol Neurobiol 2024:10.1007/s12035-024-04470-4. [PMID: 39292339 DOI: 10.1007/s12035-024-04470-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 08/30/2024] [Indexed: 09/19/2024]
Abstract
Hearing loss is one of the most common human diseases, seriously affecting everyday lives. Mitochondria, as the energy metabolism center in cells, are also involved in regulating active oxygen metabolism and mediating the occurrence of inflammation and apoptosis. Mitochondrial defects are closely related to hearing diseases. Studies have shown that mitochondrial DNA mutations are one of the causes of hereditary hearing loss. In addition, changes in mitochondrial homeostasis are directly related to noise-induced hearing loss and presbycusis. This review mainly summarizes and discusses the effects of mitochondrial dysfunction and mitophagy on hearing loss. Subsequently, we introduce the recent research progress of targeted mitochondria therapy in the hearing system.
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Affiliation(s)
- Shan Xu
- Department of Otolaryngology, The First Hospital of China Medical University, Shenyang, 110001, China
| | - Ning Yang
- Department of Otolaryngology, The First Hospital of China Medical University, Shenyang, 110001, China.
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2
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Boldizar H, Friedman A, Stanley T, Padilla M, Galdieri J, Sclar A, Stawicki TM. The role of cilia in the development, survival, and regeneration of hair cells. Biol Open 2024; 13:bio061690. [PMID: 39263863 DOI: 10.1242/bio.061690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2024] [Accepted: 08/15/2024] [Indexed: 09/13/2024] Open
Abstract
Mutations impacting cilia genes lead to a class of human diseases known as ciliopathies. This is due to the role of cilia in the development, survival, and regeneration of many cell types. We investigated the extent to which disrupting cilia impacted these processes in lateral line hair cells of zebrafish. We found that mutations in two intraflagellar transport (IFT) genes, ift88 and dync2h1, which lead to the loss of kinocilia, caused increased hair cell apoptosis. IFT gene mutants also have a decreased mitochondrial membrane potential, and blocking the mitochondrial uniporter causes a loss of hair cells in wild-type zebrafish but not mutants, suggesting mitochondria dysfunction may contribute to the apoptosis seen in these mutants. These mutants also showed decreased proliferation during hair cell regeneration but did not show consistent changes in support cell number or proliferation during hair cell development. These results show that the loss of hair cells seen following disruption of cilia through either mutations in anterograde or retrograde IFT genes appears to be due to impacts on hair cell survival but not necessarily development in the zebrafish lateral line.
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Affiliation(s)
- Hope Boldizar
- Neuroscience Program, Lafayette College, Easton, PA 18042, USA
| | - Amanda Friedman
- Neuroscience Program, Lafayette College, Easton, PA 18042, USA
| | - Tess Stanley
- Neuroscience Program, Lafayette College, Easton, PA 18042, USA
| | - María Padilla
- Biology Department, Lafayette College, Easton, PA 18042, USA
| | | | - Arielle Sclar
- Neuroscience Program, Lafayette College, Easton, PA 18042, USA
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3
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Castranova D, Kenton MI, Kraus A, Dell CW, Park JS, Galanternik MV, Park G, Lumbantobing DN, Dye L, Marvel M, Iben J, Taimatsu K, Pham V, Willms RJ, Blevens L, Robertson TF, Hou Y, Huttenlocher A, Foley E, Parenti LR, Frazer JK, Narayan K, Weinstein BM. The axillary lymphoid organ - an external, experimentally accessible immune organ in the zebrafish. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.25.605139. [PMID: 39091802 PMCID: PMC11291151 DOI: 10.1101/2024.07.25.605139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
Lymph nodes and other secondary lymphoid organs play critical roles in immune surveillance and immune activation in mammals, but the deep internal locations of these organs make it challenging to image and study them in living animals. Here, we describe a previously uncharacterized external immune organ in the zebrafish ideally suited for studying immune cell dynamics in vivo, the axillary lymphoid organ (ALO). This small, translucent organ has an outer cortex teeming with immune cells, an inner medulla with a mesh-like network of fibroblastic reticular cells along which immune cells migrate, and a network of lymphatic vessels draining to a large adjacent lymph sac. Noninvasive high-resolution imaging of transgenically marked immune cells can be carried out in the lobes of living animals, and the ALO is readily accessible to external treatment. This newly discovered tissue provides a superb model for dynamic live imaging of immune cells and their interaction with pathogens and surrounding tissues, including blood and lymphatic vessels.
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Affiliation(s)
- Daniel Castranova
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD 20814, USA
| | - Madeleine I. Kenton
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD 20814, USA
| | - Aurora Kraus
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD 20814, USA
| | - Christopher W. Dell
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA and Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Jong S. Park
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD 20814, USA
| | - Marina Venero Galanternik
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD 20814, USA
| | - Gilseung Park
- Section of Pediatric Hematology-Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Daniel N. Lumbantobing
- Division of Fishes, Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA
| | - Louis Dye
- Microscopy and Imaging Core, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD 20814, USA
| | - Miranda Marvel
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD 20814, USA
| | - James Iben
- Molecular Genomics Core, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD 20814, USA
| | - Kiyohito Taimatsu
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD 20814, USA
| | - Van Pham
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD 20814, USA
| | - Reegan J. Willms
- Department of Medical Microbiology and Immunology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Lucas Blevens
- Section of Pediatric Hematology-Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Tanner F. Robertson
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706
| | - Yiran Hou
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706
| | - Anna Huttenlocher
- Department of Medical Microbiology and Immunology, University of Wisconsin-Madison, Madison, WI 53706
| | - Edan Foley
- Department of Medical Microbiology and Immunology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Lynne R. Parenti
- Division of Fishes, Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA
| | - J. Kimble Frazer
- Section of Pediatric Hematology-Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA
| | - Kedar Narayan
- Center for Molecular Microscopy, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA and Cancer Research Technology Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Brant M. Weinstein
- Division of Developmental Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, MD 20814, USA
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Lee DS, Schrader A, Zou J, Ang WH, Warchol M, Sheets L. Cisplatin drives mitochondrial dysregulation in sensory hair cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.29.577846. [PMID: 38352581 PMCID: PMC10862698 DOI: 10.1101/2024.01.29.577846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2024]
Abstract
Cisplatin is a chemotherapy drug that causes permanent hearing loss by injuring cochlear hair cells. The mechanisms that initiate injury are not fully understood, but mitochondria have emerged as potential mediators of hair cell cytotoxicity. Using in vivo live imaging of hair cells in the zebrafish lateral-line organ expressing a genetically encoded indicator of cumulative mitochondrial activity, we first demonstrate that greater redox history increases susceptibility to cisplatin. Next, we conducted time-lapse imaging to understand dynamic changes in mitochondrial homeostasis and observe elevated mitochondrial and cytosolic calcium that surge prior to hair cell death. Furthermore, using a localized probe that fluoresces in the presence of cisplatin, we show that cisplatin directly accumulates in hair cell mitochondria, and this accumulation occurs before mitochondrial dysregulation and apoptosis. Our findings provide evidence that cisplatin directly targets hair cell mitochondria and support that the mitochondria are integral to cisplatin cytotoxicity in hair cells.
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Molnar N, Miskolci V. Imaging immunometabolism in situ in live animals. IMMUNOMETABOLISM (COBHAM, SURREY) 2024; 6:e00044. [PMID: 39296471 PMCID: PMC11406703 DOI: 10.1097/in9.0000000000000044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/21/2024]
Abstract
Immunometabolism is a rapidly developing field that holds great promise for diagnostic and therapeutic benefits to human diseases. The field has emerged based on seminal findings from in vitro and ex vivo studies that established the fundamental role of metabolism in immune cell effector functions. Currently, the field is acknowledging the necessity of investigating cellular metabolism within the natural context of biological processes. Examining cells in their native microenvironment is essential not only to reveal cell-intrinsic mechanisms but also to understand how cross-talk between neighboring cells regulates metabolism at the tissue level in a local niche. This necessity is driving innovation and advancement in multiple imaging-based technologies to enable analysis of dynamic intracellular metabolism at the single-cell level, with spatial and temporal resolution. In this review, we tally the currently available imaging-based technologies and explore the emerging methods of Raman and autofluorescence lifetime imaging microscopy, which hold significant potential and offer broad applications in the field of immunometabolism.
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Affiliation(s)
- Nicole Molnar
- Department of Microbiology, Biochemistry and Molecular Genetics, New Jersey Medical School, Rutgers Health, Rutgers University, Newark, NJ, USA
- Center for Cell Signaling, Rutgers Health, Rutgers University, Newark, NJ, USA
- Center for Immunity and Inflammation, Rutgers Health, Rutgers University, Newark, NJ, USA
| | - Veronika Miskolci
- Department of Microbiology, Biochemistry and Molecular Genetics, New Jersey Medical School, Rutgers Health, Rutgers University, Newark, NJ, USA
- Center for Cell Signaling, Rutgers Health, Rutgers University, Newark, NJ, USA
- Center for Immunity and Inflammation, Rutgers Health, Rutgers University, Newark, NJ, USA
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6
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Liu Z, Zhang H, Hong G, Bi X, Hu J, Zhang T, An Y, Guo N, Dong F, Xiao Y, Li W, Zhao X, Chu B, Guo S, Zhang X, Chai R, Fu X. Inhibition of Gpx4-mediated ferroptosis alleviates cisplatin-induced hearing loss in C57BL/6 mice. Mol Ther 2024; 32:1387-1406. [PMID: 38414247 PMCID: PMC11081921 DOI: 10.1016/j.ymthe.2024.02.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 01/29/2024] [Accepted: 02/24/2024] [Indexed: 02/29/2024] Open
Abstract
Cisplatin-induced hearing loss is a common side effect of cancer chemotherapy in clinics; however, the mechanism of cisplatin-induced ototoxicity is still not completely clarified. Cisplatin-induced ototoxicity is mainly associated with the production of reactive oxygen species, activation of apoptosis, and accumulation of intracellular lipid peroxidation, which also is involved in ferroptosis induction. In this study, the expression of TfR1, a ferroptosis biomarker, was upregulated in the outer hair cells of cisplatin-treated mice. Moreover, several key ferroptosis regulator genes were altered in cisplatin-damaged cochlear explants based on RNA sequencing, implying the induction of ferroptosis. Ferroptosis-related Gpx4 and Fsp1 knockout mice were established to investigate the specific mechanisms associated with ferroptosis in cochleae. Severe outer hair cell loss and progressive damage of synapses in inner hair cells were observed in Atoh1-Gpx4-/- mice. However, Fsp1-/- mice showed no significant hearing phenotype, demonstrating that Gpx4, but not Fsp1, may play an important role in the functional maintenance of HCs. Moreover, findings showed that FDA-approved luteolin could specifically inhibit ferroptosis and alleviate cisplatin-induced ototoxicity through decreased expression of transferrin and intracellular concentration of ferrous ions. This study indicated that ferroptosis inhibition through the reduction of intracellular ferrous ions might be a potential strategy to prevent cisplatin-induced hearing loss.
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MESH Headings
- Animals
- Cisplatin/adverse effects
- Ferroptosis/drug effects
- Ferroptosis/genetics
- Mice
- Hearing Loss/chemically induced
- Hearing Loss/genetics
- Hearing Loss/metabolism
- Mice, Knockout
- Phospholipid Hydroperoxide Glutathione Peroxidase/metabolism
- Phospholipid Hydroperoxide Glutathione Peroxidase/genetics
- Mice, Inbred C57BL
- Disease Models, Animal
- Receptors, Transferrin/metabolism
- Receptors, Transferrin/genetics
- Reactive Oxygen Species/metabolism
- Lipid Peroxidation/drug effects
- Hair Cells, Auditory, Outer/metabolism
- Hair Cells, Auditory, Outer/drug effects
- Hair Cells, Auditory, Outer/pathology
- Ototoxicity/etiology
- Ototoxicity/metabolism
- Antineoplastic Agents/adverse effects
- Apoptosis/drug effects
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Affiliation(s)
- Ziyi Liu
- Medical Science and Technology Innovation Center, Institute of Brain Science and Brain-inspired Research, Shandong Provincial Hospital, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong 250117, China
| | - Hanbing Zhang
- Department of Otorhinolaryngology, Qilu Hospital of Shandong University, NHC Key Laboratory of Otorhinolaryngology (Shandong University), Jinan, Shandong 250012, China
| | - Guodong Hong
- Medical Science and Technology Innovation Center, Institute of Brain Science and Brain-inspired Research, Shandong Provincial Hospital, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong 250117, China
| | - Xiuli Bi
- Medical Science and Technology Innovation Center, Institute of Brain Science and Brain-inspired Research, Shandong Provincial Hospital, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong 250117, China
| | - Jun Hu
- Otolaryngology-Head and Neck Surgery, First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Tiancheng Zhang
- Otolaryngology-Head and Neck Surgery, First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Yachun An
- School of Life Science, Shandong University, Qingdao, Shandong 266237, China
| | - Na Guo
- Medical Science and Technology Innovation Center, Institute of Brain Science and Brain-inspired Research, Shandong Provincial Hospital, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong 250117, China
| | - Fengyue Dong
- School of Life Science, Shandong University, Qingdao, Shandong 266237, China
| | - Yu Xiao
- School of Life Science, Shandong University, Qingdao, Shandong 266237, China
| | - Wen Li
- Medical Science and Technology Innovation Center, Institute of Brain Science and Brain-inspired Research, Shandong Provincial Hospital, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong 250117, China
| | - Xiaoxu Zhao
- Medical Science and Technology Innovation Center, Institute of Brain Science and Brain-inspired Research, Shandong Provincial Hospital, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong 250117, China
| | - Bo Chu
- Department of Cell Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, Shandong 250102, China
| | - Siwei Guo
- School of Life Science, Shandong University, Qingdao, Shandong 266237, China
| | - Xiaohan Zhang
- Medical Science and Technology Innovation Center, Institute of Brain Science and Brain-inspired Research, Shandong Provincial Hospital, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong 250117, China
| | - Renjie Chai
- Otolaryngology-Head and Neck Surgery, First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325035, China; State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Life Sciences and Technology, School of Medicine, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, Jiangsu 210096, China; Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu 226001, China; Department of Neurology, Aerospace Center Hospital, School of Life Science, Beijing Institute of Technology, Beijing 100081, China; Department of Otolaryngology Head and Neck Surgery, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, Sichuan 610072, China; Southeast University Shenzhen Research Institute, Shenzhen, Guangdong 518063, China.
| | - Xiaolong Fu
- Medical Science and Technology Innovation Center, Institute of Brain Science and Brain-inspired Research, Shandong Provincial Hospital, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong 250117, China.
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Cirqueira F, Figueirêdo LPD, Malafaia G, Rocha TL. Zebrafish neuromast sensory system: Is it an emerging target to assess environmental pollution impacts? ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 344:123400. [PMID: 38272167 DOI: 10.1016/j.envpol.2024.123400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 12/29/2023] [Accepted: 01/17/2024] [Indexed: 01/27/2024]
Abstract
Environmental pollution poses risks to ecosystems. Among these risks, one finds neurotoxicity and damage to the lateral line structures of fish, such as the neuromast and its hair cells. Zebrafish (Danio rerio) is recommended as model species to be used in ecotoxicological studies and environmental biomonitoring programs aimed at assessing several biomarkers, such as ototoxicity. However, little is known about the history of and knowledge gaps on zebrafish ototoxicity. Thus, the aim of the current study is to review data available in the scientific literature about using zebrafish as animal model to assess neuromast toxicity. It must be done by analyzing the history and publication category, world production, experimental design, developmental stages, chemical classes, neuromasts and hair cell visualization methods, and zebrafish strains. Based on the results, number, survival and fluorescence intensity of neuromasts, and their hair cells, were the parameters oftentimes used to assess ototoxicity in zebrafish. The wild AB strain was the most used one, and it was followed by Tübingen and transgenic strains with GFP markers. DASPEI was the fluorescent dye most often applied as method to visualize neuromasts, and it was followed by Yo-Pro-1 and GFP transgenic lines. Antibiotics, antitumorals, metals, nanoparticles and plant extracts were the most frequent classes of chemicals used in the analyzed studies. Overall, pollutants can harm zebrafish's mechanosensory system, as well as affect their behavior and survival. Results have shown that zebrafish is a suitable model system to assess ototoxicity induced by environmental pollution.
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Affiliation(s)
- Felipe Cirqueira
- Laboratory of Environmental Biotechnology and Ecotoxicology, Institute of Tropical Pathology and Public Health, Federal University of Goiás, Goiânia, Goiás, Brazil
| | - Livia Pitombeira de Figueirêdo
- Laboratory of Environmental Biotechnology and Ecotoxicology, Institute of Tropical Pathology and Public Health, Federal University of Goiás, Goiânia, Goiás, Brazil
| | - Guilherme Malafaia
- Laboratory of Toxicology Applied to the Environment, Goiano Federal Institute - Urutaí Campus, Goiás, Brazil
| | - Thiago Lopes Rocha
- Laboratory of Environmental Biotechnology and Ecotoxicology, Institute of Tropical Pathology and Public Health, Federal University of Goiás, Goiânia, Goiás, Brazil.
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8
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Craig EW, Black EC, Goo CE, Swearer AA, Yee NG, Rasmussen JP. Dendritic atoh1a+ cells serve as transient intermediates during zebrafish Merkel cell development and regeneration. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.14.557830. [PMID: 37745341 PMCID: PMC10515958 DOI: 10.1101/2023.09.14.557830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
Sensory cells often adopt specific morphologies that aid in the detection of external stimuli. Merkel cells encode gentle touch stimuli in vertebrate skin and adopt a reproducible shape characterized by spiky, actin-rich microvilli that emanate from the cell surface. The mechanism by which Merkel cells acquire this stereotyped morphology from basal keratinocyte progenitors is unknown. Here, we establish that dendritic Merkel cells (dMCs) express atonal homolog 1a (atoh1a), extend dynamic filopodial processes, and arise in transient waves during zebrafish skin development and regeneration. We find that dMCs share molecular similarities with both basal keratinocytes and Merkel cells, yet display mesenchymal-like behaviors, including local cell motility and proliferation within the epidermis. Furthermore, dMCs can directly adopt the mature, microvilliated Merkel cell morphology through substantial remodeling of the actin cytoskeleton. Loss of Ectodysplasin A signaling alters the morphology of dMCs and Merkel cells within specific skin regions. Our results show that dMCs represent an intermediate state in the Merkel cell maturation program and identify Ectodysplasin A signaling as a key regulator of Merkel cell morphology.
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Affiliation(s)
- Evan W. Craig
- Department of Biology, University of Washington, Seattle, WA, USA
| | - Erik C. Black
- Department of Biology, University of Washington, Seattle, WA, USA
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA
| | - Camille E.A. Goo
- Department of Biology, University of Washington, Seattle, WA, USA
| | - Avery Angell Swearer
- Department of Biology, University of Washington, Seattle, WA, USA
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA
| | - Nathaniel G. Yee
- Department of Biology, University of Washington, Seattle, WA, USA
| | - Jeffrey P. Rasmussen
- Department of Biology, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, USA
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9
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Michanski S, Henneck T, Mukhopadhyay M, Steyer AM, Gonzalez PA, Grewe K, Ilgen P, Gültas M, Fornasiero EF, Jakobs S, Möbius W, Vogl C, Pangršič T, Rizzoli SO, Wichmann C. Age-dependent structural reorganization of utricular ribbon synapses. Front Cell Dev Biol 2023; 11:1178992. [PMID: 37635868 PMCID: PMC10447907 DOI: 10.3389/fcell.2023.1178992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Accepted: 07/17/2023] [Indexed: 08/29/2023] Open
Abstract
In mammals, spatial orientation is synaptically-encoded by sensory hair cells of the vestibular labyrinth. Vestibular hair cells (VHCs) harbor synaptic ribbons at their presynaptic active zones (AZs), which play a critical role in molecular scaffolding and facilitate synaptic release and vesicular replenishment. With advancing age, the prevalence of vestibular deficits increases; yet, the underlying mechanisms are not well understood and the possible accompanying morphological changes in the VHC synapses have not yet been systematically examined. We investigated the effects of maturation and aging on the ultrastructure of the ribbon-type AZs in murine utricles using various electron microscopic techniques and combined them with confocal and super-resolution light microscopy as well as metabolic imaging up to 1 year of age. In older animals, we detected predominantly in type I VHCs the formation of floating ribbon clusters, mostly consisting of newly synthesized ribbon material. Our findings suggest that VHC ribbon-type AZs undergo dramatic structural alterations upon aging.
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Affiliation(s)
- Susann Michanski
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience, InnerEarLab and Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, Göttingen, Germany
| | - Timo Henneck
- Biology Bachelor Program, University of Göttingen, Göttingen, Germany
| | - Mohona Mukhopadhyay
- Experimental Otology Group, InnerEarLab, Department of Otolaryngology, Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany
| | - Anna M. Steyer
- Electron Microscopy-City Campus, Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Center Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), University of Göttingen, Göttingen, Germany
| | - Paola Agüi Gonzalez
- Department for Neuro-and Sensory Physiology, University Medical Center Göttingen, Center for Biostructural Imaging of Neurodegeneration (BIN), Göttingen, Germany
| | - Katharina Grewe
- Department for Neuro-and Sensory Physiology, University Medical Center Göttingen, Center for Biostructural Imaging of Neurodegeneration (BIN), Göttingen, Germany
| | - Peter Ilgen
- Clinic of Neurology, University Medical Center Göttingen, Göttingen, Germany
- Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Translational Neuroinflammation and Automated Microscopy TNM, Göttingen, Germany
| | - Mehmet Gültas
- Faculty of Agriculture, South Westphalia University of Applied Sciences, Soest, Germany
| | - Eugenio F. Fornasiero
- Department for Neuro-and Sensory Physiology, University Medical Center Göttingen, Center for Biostructural Imaging of Neurodegeneration (BIN), Göttingen, Germany
| | - Stefan Jakobs
- Clinic of Neurology, University Medical Center Göttingen, Göttingen, Germany
- Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMP, Translational Neuroinflammation and Automated Microscopy TNM, Göttingen, Germany
| | - Wiebke Möbius
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, Göttingen, Germany
- Electron Microscopy-City Campus, Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Christian Vogl
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Presynaptogenesis and Intracellular Transport in Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, Göttingen, Germany
- Auditory Neuroscience Group, Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
| | - Tina Pangršič
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, Göttingen, Germany
- Experimental Otology Group, InnerEarLab, Department of Otolaryngology, Institute for Auditory Neuroscience, University Medical Center Göttingen, Göttingen, Germany
| | - Silvio O. Rizzoli
- Department for Neuro-and Sensory Physiology, University Medical Center Göttingen, Center for Biostructural Imaging of Neurodegeneration (BIN), Göttingen, Germany
| | - Carolin Wichmann
- Molecular Architecture of Synapses Group, Institute for Auditory Neuroscience, InnerEarLab and Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
- Collaborative Research Center 889, University of Göttingen, Göttingen, Germany
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, Göttingen, Germany
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10
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Wong HTC, Lukasz D, Drerup CM, Kindt KS. In vivo investigation of mitochondria in lateral line afferent neurons and hair cells. Hear Res 2023; 431:108740. [PMID: 36948126 PMCID: PMC10079644 DOI: 10.1016/j.heares.2023.108740] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 02/17/2023] [Accepted: 03/12/2023] [Indexed: 03/16/2023]
Abstract
To process sensory stimuli, intense energy demands are placed on hair cells and primary afferents. Hair cells must both mechanotransduce and maintain pools of synaptic vesicles for neurotransmission. Furthermore, both hair cells and afferent neurons must continually maintain a polarized membrane to propagate sensory information. These processes are energy demanding and therefore both cell types are critically reliant on mitochondrial health and function for their activity and maintenance. Based on these demands, it is not surprising that deficits in mitochondrial health can negatively impact the auditory and vestibular systems. In this review, we reflect on how mitochondrial function and dysfunction are implicated in hair cell-mediated sensory system biology. Specifically, we focus on live imaging approaches that have been applied to study mitochondria using the zebrafish lateral-line system. We highlight the fluorescent dyes and genetically encoded biosensors that have been used to study mitochondria in lateral-line hair cells and afferent neurons. We then describe the impact this in vivo work has had on the field of mitochondrial biology as well as the relationship between mitochondria and sensory system development, function, and survival. Finally, we delineate the areas in need of further exploration. This includes in vivo analyses of mitochondrial dynamics and biogenesis, which will round out our understanding of mitochondrial biology in this sensitive sensory system.
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Affiliation(s)
- Hiu-Tung C Wong
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Daria Lukasz
- Section on Sensory Cell Development and Function, National Institute of Deafness and other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Catherine M Drerup
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI 53706, USA.
| | - Katie S Kindt
- Section on Sensory Cell Development and Function, National Institute of Deafness and other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA.
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11
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McQuate A, Knecht S, Raible DW. Activity regulates a cell type-specific mitochondrial phenotype in zebrafish lateral line hair cells. eLife 2023; 12:e80468. [PMID: 36912880 PMCID: PMC10129330 DOI: 10.7554/elife.80468] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Accepted: 03/10/2023] [Indexed: 03/14/2023] Open
Abstract
Hair cells of the inner ear are particularly sensitive to changes in mitochondria, the subcellular organelles necessary for energy production in all eukaryotic cells. There are over 30 mitochondrial deafness genes, and mitochondria are implicated in hair cell death following noise exposure, aminoglycoside antibiotic exposure, as well as in age-related hearing loss. However, little is known about the basic aspects of hair cell mitochondrial biology. Using hair cells from the zebrafish lateral line as a model and serial block-face scanning electron microscopy, we have quantifiably characterized a unique hair cell mitochondrial phenotype that includes (1) a high mitochondrial volume and (2) specific mitochondrial architecture: multiple small mitochondria apically, and a reticular mitochondrial network basally. This phenotype develops gradually over the lifetime of the hair cell. Disrupting this mitochondrial phenotype with a mutation in opa1 impacts mitochondrial health and function. While hair cell activity is not required for the high mitochondrial volume, it shapes the mitochondrial architecture, with mechanotransduction necessary for all patterning, and synaptic transmission necessary for the development of mitochondrial networks. These results demonstrate the high degree to which hair cells regulate their mitochondria for optimal physiology and provide new insights into mitochondrial deafness.
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Affiliation(s)
- Andrea McQuate
- Department of Biological Structure, University of WashingtonSeattleUnited States
- Department of Otolaryngology-HNS, University of WashingtonSeattleUnited States
| | - Sharmon Knecht
- Department of Biological Structure, University of WashingtonSeattleUnited States
| | - David W Raible
- Department of Biological Structure, University of WashingtonSeattleUnited States
- Department of Otolaryngology-HNS, University of WashingtonSeattleUnited States
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12
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Finding the balance: The elusive mechanisms underlying auditory hair cell mitochondrial biogenesis and mitophagy. Hear Res 2023; 428:108664. [PMID: 36566644 DOI: 10.1016/j.heares.2022.108664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 11/23/2022] [Accepted: 12/07/2022] [Indexed: 12/13/2022]
Abstract
In all cell types, mitochondrial biogenesis is balanced with mitophagy to maintain a healthy mitochondrial pool that sustains specific energetic demands. Cell types that have a higher energetic burden, such as skeletal muscle cells and cardiomyocytes, will subsequently develop high mitochondrial volumes. In these cells, calcium influx during activity triggers cascades leading to activation of the co-transcriptional regulation factor PGC-1α, a master regulator of mitochondrial biogenesis, in a well-defined pathway. Despite the advantages in ATP production, high mitochondrial volumes might prove to be perilous, as it increases exposure to reactive oxygen species produced during oxidative phosphorylation. Mechanosensory hair cells are highly metabolically active cells, with high total mitochondrial volumes to meet that demand. However, the mechanisms leading to expansion and maintenance of the hair cell mitochondrial pool are not well defined. Calcium influx during mechanotransduction and synaptic transmission regulate hair cell mitochondria, leading to a possibility that similar to skeletal muscle and cardiomyocytes, intracellular calcium underlies the expansion of the hair cell mitochondrial volume. This review briefly summarizes the potential mechanisms underlying mitochondrial biogenesis in other cell types and in hair cells. We propose that hair cell mitochondrial biogenesis is primarily product of cellular differentiation rather than calcium influx, and that the hair cell high mitochondrial volume renders them more susceptible to reactive oxygen species increased by calcium flux than other cell types.
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13
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O'Sullivan JDB, Bullen A, Mann ZF. Mitochondrial form and function in hair cells. Hear Res 2023; 428:108660. [PMID: 36525891 DOI: 10.1016/j.heares.2022.108660] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 11/07/2022] [Accepted: 11/23/2022] [Indexed: 11/27/2022]
Abstract
Hair cells (HCs) are specialised sensory receptors residing in the neurosensory epithelia of inner ear sense organs. The precise morphological and physiological properties of HCs allow us to perceive sound and interact with the world around us. Mitochondria play a significant role in normal HC function and are also intricately involved in HC death. They generate ATP essential for sustaining the activity of ion pumps, Ca2+ transporters and the integrity of the stereociliary bundle during transduction as well as regulating cytosolic calcium homoeostasis during synaptic transmission. Advances in imaging techniques have allowed us to study mitochondrial populations throughout the HC, and how they interact with other organelles. These analyses have identified distinct mitochondrial populations between the apical and basolateral portions of the HC, in which mitochondrial morphology appears determined by the physiological processes in the different cellular compartments. Studies in HCs across species show that ototoxic agents, ageing and noise damage directly impact mitochondrial structure and function resulting in HC death. Deciphering the molecular mechanisms underlying this mitochondrial sensitivity, and how their morphology relates to their function during HC death, requires that we first understand this relationship in the context of normal HC function.
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Affiliation(s)
- James D B O'Sullivan
- Centre for Craniofacial and Regenerative Biology, Faculty of Dentistry, Oral, Craniofacial Sciences, King's College London, London SE1 9RT, U.K
| | - Anwen Bullen
- UCL Ear Institute, University College London, London WC1×8EE, U.K.
| | - Zoë F Mann
- Centre for Craniofacial and Regenerative Biology, Faculty of Dentistry, Oral, Craniofacial Sciences, King's College London, London SE1 9RT, U.K.
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14
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Brown TL, Horton EC, Craig EW, Goo CEA, Black EC, Hewitt MN, Yee NG, Fan ET, Raible DW, Rasmussen JP. Dermal appendage-dependent patterning of zebrafish atoh1a+ Merkel cells. eLife 2023; 12:85800. [PMID: 36648063 PMCID: PMC9901935 DOI: 10.7554/elife.85800] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 01/11/2023] [Indexed: 01/18/2023] Open
Abstract
Touch system function requires precise interactions between specialized skin cells and somatosensory axons, as exemplified by the vertebrate mechanosensory Merkel cell-neurite complex. Development and patterning of Merkel cells and associated neurites during skin organogenesis remain poorly understood, partly due to the in utero development of mammalian embryos. Here, we discover Merkel cells in the zebrafish epidermis and identify Atonal homolog 1a (Atoh1a) as a marker of zebrafish Merkel cells. We show that zebrafish Merkel cells derive from basal keratinocytes, express neurosecretory and mechanosensory machinery, extend actin-rich microvilli, and complex with somatosensory axons, all hallmarks of mammalian Merkel cells. Merkel cells populate all major adult skin compartments, with region-specific densities and distribution patterns. In vivo photoconversion reveals that Merkel cells undergo steady loss and replenishment during skin homeostasis. Merkel cells develop concomitant with dermal appendages along the trunk and loss of Ectodysplasin signaling, which prevents dermal appendage formation, reduces Merkel cell density by affecting cell differentiation. By contrast, altering dermal appendage morphology changes the distribution, but not density, of Merkel cells. Overall, our studies provide insights into touch system maturation during skin organogenesis and establish zebrafish as an experimentally accessible in vivo model for the study of Merkel cell biology.
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Affiliation(s)
- Tanya L Brown
- Department of Biology, University of WashingtonSeattleUnited States
| | - Emma C Horton
- Department of Biology, University of WashingtonSeattleUnited States
| | - Evan W Craig
- Department of Biology, University of WashingtonSeattleUnited States
| | - Camille EA Goo
- Department of Biology, University of WashingtonSeattleUnited States
| | - Erik C Black
- Department of Biology, University of WashingtonSeattleUnited States
- Molecular and Cellular Biology Program, University of WashingtonSeattleUnited States
| | - Madeleine N Hewitt
- Molecular and Cellular Biology Program, University of WashingtonSeattleUnited States
- Department of Biological Structure, University of WashingtonSeattleUnited States
| | - Nathaniel G Yee
- Department of Biology, University of WashingtonSeattleUnited States
| | - Everett T Fan
- Department of Biology, University of WashingtonSeattleUnited States
| | - David W Raible
- Department of Biological Structure, University of WashingtonSeattleUnited States
- Department of Otolaryngology - Head and Neck Surgery, University of WashingtonSeattleUnited States
- Institute for Stem Cell and Regenerative Medicine, University of WashingtonSeattleUnited States
| | - Jeffrey P Rasmussen
- Department of Biology, University of WashingtonSeattleUnited States
- Institute for Stem Cell and Regenerative Medicine, University of WashingtonSeattleUnited States
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15
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Barrallo-Gimeno A, Llorens J. Hair cell toxicology: With the help of a little fish. Front Cell Dev Biol 2022; 10:1085225. [PMID: 36582469 PMCID: PMC9793777 DOI: 10.3389/fcell.2022.1085225] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Accepted: 11/28/2022] [Indexed: 12/15/2022] Open
Abstract
Hearing or balance loss are disabling conditions that have a serious impact in those suffering them, especially when they appear in children. Their ultimate cause is frequently the loss of function of mechanosensory hair cells in the inner ear. Hair cells can be damaged by environmental insults, like noise or chemical agents, known as ototoxins. Two of the most common ototoxins are life-saving medications: cisplatin against solid tumors, and aminoglycoside antibiotics to treat infections. However, due to their localization inside the temporal bone, hair cells are difficult to study in mammals. As an alternative animal model, zebrafish larvae have hair cells similar to those in mammals, some of which are located in a fish specific organ on the surface of the skin, the lateral line. This makes them easy to observe in vivo and readily accessible for ototoxins or otoprotective substances. These features have made possible advances in the study of the mechanisms mediating ototoxicity or identifying new potential ototoxins. Most importantly, the small size of the zebrafish larvae has allowed screening thousands of molecules searching for otoprotective agents in a scale that would be highly impractical in rodent models. The positive hits found can then start the long road to reach clinical settings to prevent hearing or balance loss.
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Affiliation(s)
- Alejandro Barrallo-Gimeno
- Department de Ciències Fisiològiques, Facultat de Medicina i Ciències de la Salut, Campus de Bellvitge, Universitat de Barcelona, L’Hospitalet de Llobregat, Spain
- Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
- Institut D'Investigació Biomèdica de Bellvitge, IDIBELL, L’Hospitalet de Llobregat, Spain
| | - Jordi Llorens
- Department de Ciències Fisiològiques, Facultat de Medicina i Ciències de la Salut, Campus de Bellvitge, Universitat de Barcelona, L’Hospitalet de Llobregat, Spain
- Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain
- Institut D'Investigació Biomèdica de Bellvitge, IDIBELL, L’Hospitalet de Llobregat, Spain
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16
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Lee DS, Schrader A, Warchol M, Sheets L. Cisplatin exposure acutely disrupts mitochondrial bioenergetics in the zebrafish lateral-line organ. Hear Res 2022; 426:108513. [PMID: 35534350 PMCID: PMC9745743 DOI: 10.1016/j.heares.2022.108513] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 04/18/2022] [Accepted: 05/02/2022] [Indexed: 12/16/2022]
Abstract
Cisplatin is a commonly used chemotherapeutic agent that causes debilitating high-frequency hearing loss. No targeted therapies currently exist to treat cisplatin ototoxicity, partly because the underlying mechanisms of cisplatin-induced hair cell damage are not completely defined. Zebrafish may offer key insights to cisplatin ototoxicity because their lateral-line organ contains hair cells that are remarkably similar to those within the cochlea but are optically accessible, permitting observation of cisplatin injury in live intact hair cells. In this study, we used a combination of genetically encoded biosensors in zebrafish larvae and fluorescent indicators to characterize changes in mitochondrial bioenergetics in response to cisplatin. Following exposure to cisplatin, confocal imaging of live intact neuromasts demonstrated increased mitochondrial activity. Staining with fixable fluorescent dyes that accumulate in active mitochondria similarly showed hyperpolarized mitochondrial membrane potential. Zebrafish expressing a calcium indicator within their hair cells revealed elevated levels of mitochondrial calcium immediately following completion of cisplatin treatment. A fluorescent ROS indicator demonstrated that these changes in mitochondrial function were associated with increased oxidative stress. After a period of recovery, cisplatin-exposed zebrafish demonstrated caspase-3-mediated apoptosis. Altogether, these findings suggest that cisplatin acutely disrupts mitochondrial bioenergetics and may play a key role in initiating cisplatin ototoxicity.
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Affiliation(s)
- David S. Lee
- Department of Otolaryngology – Head and Neck Surgery, Washington University School of Medicine, 660 S. Euclid Ave. Campus Box 8115, St. Louis, MO 63110, USA,Corresponding author at: Department of Otolaryngology – Head and Neck Surgery, Washington University School of Medicine, 660 S. Euclid Ave. Campus Box 8115, St. Louis, MO 63110, USA. (D.S. Lee)
| | - Angela Schrader
- Department of Otolaryngology – Head and Neck Surgery, Washington University School of Medicine, 660 S. Euclid Ave. Campus Box 8115, St. Louis, MO 63110, USA
| | - Mark Warchol
- Department of Otolaryngology – Head and Neck Surgery, Washington University School of Medicine, 660 S. Euclid Ave. Campus Box 8115, St. Louis, MO 63110, USA,Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Lavinia Sheets
- Department of Otolaryngology – Head and Neck Surgery, Washington University School of Medicine, 660 S. Euclid Ave. Campus Box 8115, St. Louis, MO 63110, USA,Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
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17
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Lukasz D, Beirl A, Kindt K. Chronic neurotransmission increases the susceptibility of lateral-line hair cells to ototoxic insults. eLife 2022; 11:77775. [PMID: 36047587 PMCID: PMC9473691 DOI: 10.7554/elife.77775] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 08/30/2022] [Indexed: 11/27/2022] Open
Abstract
Sensory hair cells receive near constant stimulation by omnipresent auditory and vestibular stimuli. To detect and encode these stimuli, hair cells require steady ATP production, which can be accompanied by a buildup of mitochondrial byproducts called reactive oxygen species (ROS). ROS buildup is thought to sensitize hair cells to ototoxic insults, including the antibiotic neomycin. Work in neurons has shown that neurotransmission is a major driver of ATP production and ROS buildup. Therefore, we tested whether neurotransmission is a significant contributor to ROS buildup in hair cells. Using genetics and pharmacology, we disrupted two key aspects of neurotransmission in zebrafish hair cells: presynaptic calcium influx and the fusion of synaptic vesicles. We find that chronic block of neurotransmission enhances hair-cell survival when challenged with the ototoxin neomycin. This reduction in ototoxin susceptibility is accompanied by reduced mitochondrial activity, likely due to a reduced ATP demand. In addition, we show that mitochondrial oxidation and ROS buildup are reduced when neurotransmission is blocked. Mechanistically, we find that it is the synaptic vesicle cycle rather than presynaptic- or mitochondrial-calcium influx that contributes most significantly to this metabolic stress. Our results comprehensively indicate that, over time, neurotransmission causes ROS buildup that increases the susceptibility of hair cells to ototoxins.
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Affiliation(s)
- Daria Lukasz
- Section on Sensory Cell Development and Function, National Institutes of Health, Bethesda, United States
| | - Alisha Beirl
- Section on Sensory Cell Development and Function, National Institutes of Health, Bethesda, United States
| | - Katie Kindt
- Section on Sensory Cell Development and Function, National Institutes of Health, Bethesda, United States
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18
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Sabharwal A, Campbell JM, Schwab TL, WareJoncas Z, Wishman MD, Ata H, Liu W, Ichino N, Hunter DE, Bergren JD, Urban MD, Urban RM, Holmberg SR, Kar B, Cook A, Ding Y, Xu X, Clark KJ, Ekker SC. A Primer Genetic Toolkit for Exploring Mitochondrial Biology and Disease Using Zebrafish. Genes (Basel) 2022; 13:1317. [PMID: 35893052 PMCID: PMC9331066 DOI: 10.3390/genes13081317] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Revised: 07/14/2022] [Accepted: 07/19/2022] [Indexed: 02/04/2023] Open
Abstract
Mitochondria are a dynamic eukaryotic innovation that play diverse roles in biology and disease. The mitochondrial genome is remarkably conserved in all vertebrates, encoding the same 37-gene set and overall genomic structure, ranging from 16,596 base pairs (bp) in the teleost zebrafish (Danio rerio) to 16,569 bp in humans. Mitochondrial disorders are amongst the most prevalent inherited diseases, affecting roughly 1 in every 5000 individuals. Currently, few effective treatments exist for those with mitochondrial ailments, representing a major unmet patient need. Mitochondrial dysfunction is also a common component of a wide variety of other human illnesses, ranging from neurodegenerative disorders such as Huntington's disease and Parkinson's disease to autoimmune illnesses such as multiple sclerosis and rheumatoid arthritis. The electron transport chain (ETC) component of mitochondria is critical for mitochondrial biology and defects can lead to many mitochondrial disease symptoms. Here, we present a publicly available collection of genetic mutants created in highly conserved, nuclear-encoded mitochondrial genes in Danio rerio. The zebrafish system represents a potentially powerful new opportunity for the study of mitochondrial biology and disease due to the large number of orthologous genes shared with humans and the many advanced features of this model system, from genetics to imaging. This collection includes 15 mutant lines in 13 different genes created through locus-specific gene editing to induce frameshift or splice acceptor mutations, leading to predicted protein truncation during translation. Additionally, included are 11 lines created by the random insertion of the gene-breaking transposon (GBT) protein trap cassette. All these targeted mutant alleles truncate conserved domains of genes critical to the proper function of the ETC or genes that have been implicated in human mitochondrial disease. This collection is designed to accelerate the use of zebrafish to study many different aspects of mitochondrial function to widen our understanding of their role in biology and human disease.
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Affiliation(s)
- Ankit Sabharwal
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA; (A.S.); (J.M.C.); (T.L.S.); (Z.W.); (M.D.W.); (H.A.); (W.L.); (N.I.); (D.E.H.); (J.D.B.); (M.D.U.); (R.M.U.); (S.R.H.); (B.K.); (A.C.); (Y.D.); (X.X.); (K.J.C.)
| | - Jarryd M. Campbell
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA; (A.S.); (J.M.C.); (T.L.S.); (Z.W.); (M.D.W.); (H.A.); (W.L.); (N.I.); (D.E.H.); (J.D.B.); (M.D.U.); (R.M.U.); (S.R.H.); (B.K.); (A.C.); (Y.D.); (X.X.); (K.J.C.)
| | - Tanya L. Schwab
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA; (A.S.); (J.M.C.); (T.L.S.); (Z.W.); (M.D.W.); (H.A.); (W.L.); (N.I.); (D.E.H.); (J.D.B.); (M.D.U.); (R.M.U.); (S.R.H.); (B.K.); (A.C.); (Y.D.); (X.X.); (K.J.C.)
| | - Zachary WareJoncas
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA; (A.S.); (J.M.C.); (T.L.S.); (Z.W.); (M.D.W.); (H.A.); (W.L.); (N.I.); (D.E.H.); (J.D.B.); (M.D.U.); (R.M.U.); (S.R.H.); (B.K.); (A.C.); (Y.D.); (X.X.); (K.J.C.)
| | - Mark D. Wishman
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA; (A.S.); (J.M.C.); (T.L.S.); (Z.W.); (M.D.W.); (H.A.); (W.L.); (N.I.); (D.E.H.); (J.D.B.); (M.D.U.); (R.M.U.); (S.R.H.); (B.K.); (A.C.); (Y.D.); (X.X.); (K.J.C.)
| | - Hirotaka Ata
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA; (A.S.); (J.M.C.); (T.L.S.); (Z.W.); (M.D.W.); (H.A.); (W.L.); (N.I.); (D.E.H.); (J.D.B.); (M.D.U.); (R.M.U.); (S.R.H.); (B.K.); (A.C.); (Y.D.); (X.X.); (K.J.C.)
| | - Wiebin Liu
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA; (A.S.); (J.M.C.); (T.L.S.); (Z.W.); (M.D.W.); (H.A.); (W.L.); (N.I.); (D.E.H.); (J.D.B.); (M.D.U.); (R.M.U.); (S.R.H.); (B.K.); (A.C.); (Y.D.); (X.X.); (K.J.C.)
- Division of Cardiovascular Diseases, Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA
| | - Noriko Ichino
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA; (A.S.); (J.M.C.); (T.L.S.); (Z.W.); (M.D.W.); (H.A.); (W.L.); (N.I.); (D.E.H.); (J.D.B.); (M.D.U.); (R.M.U.); (S.R.H.); (B.K.); (A.C.); (Y.D.); (X.X.); (K.J.C.)
| | - Danielle E. Hunter
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA; (A.S.); (J.M.C.); (T.L.S.); (Z.W.); (M.D.W.); (H.A.); (W.L.); (N.I.); (D.E.H.); (J.D.B.); (M.D.U.); (R.M.U.); (S.R.H.); (B.K.); (A.C.); (Y.D.); (X.X.); (K.J.C.)
| | - Jake D. Bergren
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA; (A.S.); (J.M.C.); (T.L.S.); (Z.W.); (M.D.W.); (H.A.); (W.L.); (N.I.); (D.E.H.); (J.D.B.); (M.D.U.); (R.M.U.); (S.R.H.); (B.K.); (A.C.); (Y.D.); (X.X.); (K.J.C.)
| | - Mark D. Urban
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA; (A.S.); (J.M.C.); (T.L.S.); (Z.W.); (M.D.W.); (H.A.); (W.L.); (N.I.); (D.E.H.); (J.D.B.); (M.D.U.); (R.M.U.); (S.R.H.); (B.K.); (A.C.); (Y.D.); (X.X.); (K.J.C.)
| | - Rhianna M. Urban
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA; (A.S.); (J.M.C.); (T.L.S.); (Z.W.); (M.D.W.); (H.A.); (W.L.); (N.I.); (D.E.H.); (J.D.B.); (M.D.U.); (R.M.U.); (S.R.H.); (B.K.); (A.C.); (Y.D.); (X.X.); (K.J.C.)
| | - Shannon R. Holmberg
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA; (A.S.); (J.M.C.); (T.L.S.); (Z.W.); (M.D.W.); (H.A.); (W.L.); (N.I.); (D.E.H.); (J.D.B.); (M.D.U.); (R.M.U.); (S.R.H.); (B.K.); (A.C.); (Y.D.); (X.X.); (K.J.C.)
| | - Bibekananda Kar
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA; (A.S.); (J.M.C.); (T.L.S.); (Z.W.); (M.D.W.); (H.A.); (W.L.); (N.I.); (D.E.H.); (J.D.B.); (M.D.U.); (R.M.U.); (S.R.H.); (B.K.); (A.C.); (Y.D.); (X.X.); (K.J.C.)
| | - Alex Cook
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA; (A.S.); (J.M.C.); (T.L.S.); (Z.W.); (M.D.W.); (H.A.); (W.L.); (N.I.); (D.E.H.); (J.D.B.); (M.D.U.); (R.M.U.); (S.R.H.); (B.K.); (A.C.); (Y.D.); (X.X.); (K.J.C.)
| | - Yonghe Ding
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA; (A.S.); (J.M.C.); (T.L.S.); (Z.W.); (M.D.W.); (H.A.); (W.L.); (N.I.); (D.E.H.); (J.D.B.); (M.D.U.); (R.M.U.); (S.R.H.); (B.K.); (A.C.); (Y.D.); (X.X.); (K.J.C.)
- Division of Cardiovascular Diseases, Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA
| | - Xiaolei Xu
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA; (A.S.); (J.M.C.); (T.L.S.); (Z.W.); (M.D.W.); (H.A.); (W.L.); (N.I.); (D.E.H.); (J.D.B.); (M.D.U.); (R.M.U.); (S.R.H.); (B.K.); (A.C.); (Y.D.); (X.X.); (K.J.C.)
- Division of Cardiovascular Diseases, Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA
| | - Karl J. Clark
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA; (A.S.); (J.M.C.); (T.L.S.); (Z.W.); (M.D.W.); (H.A.); (W.L.); (N.I.); (D.E.H.); (J.D.B.); (M.D.U.); (R.M.U.); (S.R.H.); (B.K.); (A.C.); (Y.D.); (X.X.); (K.J.C.)
| | - Stephen C. Ekker
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA; (A.S.); (J.M.C.); (T.L.S.); (Z.W.); (M.D.W.); (H.A.); (W.L.); (N.I.); (D.E.H.); (J.D.B.); (M.D.U.); (R.M.U.); (S.R.H.); (B.K.); (A.C.); (Y.D.); (X.X.); (K.J.C.)
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19
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Plazas PV, Elgoyhen AB. The Cholinergic Lateral Line Efferent Synapse: Structural, Functional and Molecular Similarities With Those of the Cochlea. Front Cell Neurosci 2021; 15:765083. [PMID: 34712122 PMCID: PMC8545859 DOI: 10.3389/fncel.2021.765083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 09/21/2021] [Indexed: 11/25/2022] Open
Abstract
Vertebrate hair cell (HC) systems are innervated by efferent fibers that modulate their response to external stimuli. In mammals, the best studied efferent-HC synapse, the cholinergic medial olivocochlear (MOC) efferent system, makes direct synaptic contacts with HCs. The net effect of MOC activity is to hyperpolarize HCs through the activation of α9α10 nicotinic cholinergic receptors (nAChRs) and the subsequent activation of Ca2+-dependent SK2 potassium channels. A serious obstacle in research on many mammalian sensory systems in their native context is that their constituent neurons are difficult to access even in newborn animals, hampering circuit observation, mapping, or controlled manipulation. By contrast, fishes and amphibians have a superficial and accessible mechanosensory system, the lateral line (LL), which circumvents many of these problems. LL responsiveness is modulated by efferent neurons which aid to distinguish between external and self-generated stimuli. One component of the LL efferent system is cholinergic and its activation inhibits LL afferent activity, similar to what has been described for MOC efferents. The zebrafish (Danio rerio) has emerged as a powerful model system for studying human hearing and balance disorders, since LL HC are structurally and functionally analogous to cochlear HCs, but are optically and pharmacologically accessible within an intact specimen. Complementing mammalian studies, zebrafish have been used to gain significant insights into many facets of HC biology, including mechanotransduction and synaptic physiology as well as mechanisms of both hereditary and acquired HC dysfunction. With the rise of the zebrafish LL as a model in which to study auditory system function and disease, there has been an increased interest in studying its efferent system and evaluate the similarity between mammalian and piscine efferent synapses. Advances derived from studies in zebrafish include understanding the effect of the LL efferent system on HC and afferent activity, and revealing that an α9-containing nAChR, functionally coupled to SK channels, operates at the LL efferent synapse. In this review, we discuss the tools and findings of these recent investigations into zebrafish efferent-HC synapse, their commonalities with the mammalian counterpart and discuss several emerging areas for future studies.
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Affiliation(s)
- Paola V Plazas
- Instituto de Farmacología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Ana Belén Elgoyhen
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
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20
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Holmgren M, Sheets L. Influence of Mpv17 on Hair-Cell Mitochondrial Homeostasis, Synapse Integrity, and Vulnerability to Damage in the Zebrafish Lateral Line. Front Cell Neurosci 2021; 15:693375. [PMID: 34413725 PMCID: PMC8369198 DOI: 10.3389/fncel.2021.693375] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 06/16/2021] [Indexed: 01/27/2023] Open
Abstract
Noise exposure is particularly stressful to hair-cell mitochondria, which must produce enough energy to meet high metabolic demands as well as regulate local intracellular Ca2+ concentrations. Mitochondrial Inner Membrane Protein 17 (Mpv17) functions as a non-selective cation channel and plays a role in maintaining mitochondrial homeostasis. In zebrafish, hair cells in mpv17a9/a9 mutants displayed elevated levels of reactive oxygen species (ROS), elevated mitochondrial calcium, hyperpolarized transmembrane potential, and greater vulnerability to neomycin, indicating impaired mitochondrial function. Using a strong water current to overstimulate hair cells in the zebrafish lateral line, we observed mpv17a9/a9 mutant hair cells were more vulnerable to morphological disruption than wild type (WT) siblings simultaneously exposed to the same stimulus. To determine the role of mitochondrial homeostasis on hair-cell synapse integrity, we surveyed synapse number in mpv17a9/a9 mutants and WT siblings as well as the sizes of presynaptic dense bodies (ribbons) and postsynaptic densities immediately following stimulus exposure. We observed mechanically injured mpv17a9/a9 neuromasts were not more vulnerable to synapse loss; they lost a similar number of synapses per hair cell relative to WT. Additionally, we quantified the size of hair cell pre- and postsynaptic structures following stimulation and observed significantly enlarged WT postsynaptic densities, yet relatively little change in the size of mpv17a9/a9 postsynaptic densities following stimulation. These results suggest chronically impaired hair-cell mitochondrial activity influences postsynaptic size under homeostatic conditions but does not exacerbate synapse loss following mechanical injury.
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Affiliation(s)
- Melanie Holmgren
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO, United States
| | - Lavinia Sheets
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO, United States
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, United States
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21
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Cheung KY, Jesuthasan SJ, Baxendale S, van Hateren NJ, Marzo M, Hill CJ, Whitfield TT. Olfactory Rod Cells: A Rare Cell Type in the Larval Zebrafish Olfactory Epithelium With a Large Actin-Rich Apical Projection. Front Physiol 2021; 12:626080. [PMID: 33716772 PMCID: PMC7952648 DOI: 10.3389/fphys.2021.626080] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 01/25/2021] [Indexed: 11/13/2022] Open
Abstract
We report the presence of a rare cell type, the olfactory rod cell, in the developing zebrafish olfactory epithelium. These cells each bear a single actin-rich rod-like apical projection extending 5–10 μm from the epithelial surface. Live imaging with a ubiquitous Lifeact-RFP label indicates that the olfactory rods can oscillate. Olfactory rods arise within a few hours of the olfactory pit opening, increase in numbers and size during larval stages, and can develop in the absence of olfactory cilia. Olfactory rod cells differ in morphology from the known classes of olfactory sensory neuron, but express reporters driven by neuronal promoters. A sub-population of olfactory rod cells expresses a Lifeact-mRFPruby transgene driven by the sox10 promoter. Mosaic expression of this transgene reveals that olfactory rod cells have rounded cell bodies located apically in the olfactory epithelium and have no detectable axon. We offer speculation on the possible function of these cells in the Discussion.
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Affiliation(s)
- King Yee Cheung
- Department of Biomedical Science, Bateson Centre and Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom
| | - Suresh J Jesuthasan
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore.,Institute of Molecular and Cell Biology, Singapore, Singapore
| | - Sarah Baxendale
- Department of Biomedical Science, Bateson Centre and Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom
| | - Nicholas J van Hateren
- Department of Biomedical Science, Bateson Centre and Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom
| | - Mar Marzo
- Department of Biomedical Science, Bateson Centre and Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom
| | - Christopher J Hill
- Department of Biomedical Science, Bateson Centre and Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom
| | - Tanya T Whitfield
- Department of Biomedical Science, Bateson Centre and Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom
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22
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Holmgren M, Sheets L. Using the Zebrafish Lateral Line to Understand the Roles of Mitochondria in Sensorineural Hearing Loss. Front Cell Dev Biol 2021; 8:628712. [PMID: 33614633 PMCID: PMC7892962 DOI: 10.3389/fcell.2020.628712] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 12/23/2020] [Indexed: 01/05/2023] Open
Abstract
Hair cells are the mechanosensory receptors of the inner ear and can be damaged by noise, aging, and ototoxic drugs. This damage often results in permanent sensorineural hearing loss. Hair cells have high energy demands and rely on mitochondria to produce ATP as well as contribute to intracellular calcium homeostasis. In addition to generating ATP, mitochondria produce reactive oxygen species, which can lead to oxidative stress, and regulate cell death pathways. Zebrafish lateral-line hair cells are structurally and functionally analogous to cochlear hair cells but are optically and pharmacologically accessible within an intact specimen, making the zebrafish a good model in which to study hair-cell mitochondrial activity. Moreover, the ease of genetic manipulation of zebrafish embryos allows for the study of mutations implicated in human deafness, as well as the generation of transgenic models to visualize mitochondrial calcium transients and mitochondrial activity in live organisms. Studies of the zebrafish lateral line have shown that variations in mitochondrial activity can predict hair-cell susceptibility to damage by aminoglycosides or noise exposure. In addition, antioxidants have been shown to protect against noise trauma and ototoxic drug–induced hair-cell death. In this review, we discuss the tools and findings of recent investigations into zebrafish hair-cell mitochondria and their involvement in cellular processes, both under homeostatic conditions and in response to noise or ototoxic drugs. The zebrafish lateral line is a valuable model in which to study the roles of mitochondria in hair-cell pathologies and to develop therapeutic strategies to prevent sensorineural hearing loss in humans.
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Affiliation(s)
- Melanie Holmgren
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO, United States
| | - Lavinia Sheets
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO, United States.,Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO, United States
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23
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Retrograde Mitochondrial Transport Is Essential for Organelle Distribution and Health in Zebrafish Neurons. J Neurosci 2020; 41:1371-1392. [PMID: 33376159 PMCID: PMC7896009 DOI: 10.1523/jneurosci.1316-20.2020] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 11/25/2020] [Accepted: 12/01/2020] [Indexed: 12/12/2022] Open
Abstract
In neurons, mitochondria are transported by molecular motors throughout the cell to form and maintain functional neural connections. These organelles have many critical functions in neurons and are of high interest as their dysfunction is associated with disease. While the mechanics and impact of anterograde mitochondrial movement toward axon terminals are beginning to be understood, the frequency and function of retrograde (cell body directed) mitochondrial transport in neurons are still largely unexplored. While existing evidence indicates that some mitochondria are retrogradely transported for degradation in the cell body, the precise impact of disrupting retrograde transport on the organelles and the axon was unknown. Using long-term, in vivo imaging, we examined mitochondrial motility in zebrafish sensory and motor axons. We show that retrograde transport of mitochondria from axon terminals allows replacement of the axon terminal population within a day. By tracking these organelles, we show that not all mitochondria that leave the axon terminal are degraded; rather, they persist over several days. Disrupting retrograde mitochondrial flux in neurons leads to accumulation of aged organelles in axon terminals and loss of cell body mitochondria. Assays of neural circuit activity demonstrated that disrupting mitochondrial transport and function has no effect on sensory axon terminal activity but does negatively impact motor neuron axons. Taken together, our work supports a previously unappreciated role for retrograde mitochondrial transport in the maintenance of a homeostatic distribution of mitochondria in neurons and illustrates the downstream effects of disrupting this process on sensory and motor circuits. SIGNIFICANCE STATEMENT Disrupted mitochondrial transport has been linked to neurodegenerative disease. Retrograde transport of this organelle has been implicated in turnover of aged organelles through lysosomal degradation in the cell body. Consistent with this, we provide evidence that retrograde mitochondrial transport is important for removing aged organelles from axons; however, we show that these organelles are not solely degraded, rather they persist in neurons for days. Disrupting retrograde mitochondrial transport impacts the homeostatic distribution of mitochondria throughout the neuron and the function of motor, but not sensory, axon synapses. Together, our work shows the conserved reliance on retrograde mitochondrial transport for maintaining a healthy mitochondrial pool in neurons and illustrates the disparate effects of disrupting this process on sensory versus motor circuits.
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24
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Wong HTC, Zhang Q, Beirl AJ, Petralia RS, Wang YX, Kindt K. Synaptic mitochondria regulate hair-cell synapse size and function. eLife 2019; 8:e48914. [PMID: 31609202 PMCID: PMC6879205 DOI: 10.7554/elife.48914] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 10/13/2019] [Indexed: 11/21/2022] Open
Abstract
Sensory hair cells in the ear utilize specialized ribbon synapses. These synapses are defined by electron-dense presynaptic structures called ribbons, composed primarily of the structural protein Ribeye. Previous work has shown that voltage-gated influx of Ca2+ through CaV1.3 channels is critical for hair-cell synapse function and can impede ribbon formation. We show that in mature zebrafish hair cells, evoked presynaptic-Ca2+ influx through CaV1.3 channels initiates mitochondrial-Ca2+ (mito-Ca2+) uptake adjacent to ribbons. Block of mito-Ca2+ uptake in mature cells depresses presynaptic-Ca2+ influx and impacts synapse integrity. In developing zebrafish hair cells, mito-Ca2+ uptake coincides with spontaneous rises in presynaptic-Ca2+ influx. Spontaneous mito-Ca2+ loading lowers cellular NAD+/NADH redox and downregulates ribbon size. Direct application of NAD+ or NADH increases or decreases ribbon size respectively, possibly acting through the NAD(H)-binding domain on Ribeye. Our results present a mechanism where presynaptic- and mito-Ca2+ couple to confer proper presynaptic function and formation.
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MESH Headings
- 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester/pharmacology
- Animals
- Animals, Genetically Modified
- Calcium/metabolism
- Calcium Channel Agonists/pharmacology
- Calcium Channel Blockers/pharmacology
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Calcium Signaling
- Cell Size
- Embryo, Nonmammalian
- Evoked Potentials, Auditory/physiology
- Eye Proteins/chemistry
- Eye Proteins/genetics
- Eye Proteins/metabolism
- Gene Expression
- Hair Cells, Auditory/cytology
- Hair Cells, Auditory/drug effects
- Hair Cells, Auditory/metabolism
- Isradipine/pharmacology
- Mitochondria/drug effects
- Mitochondria/metabolism
- Mitochondria/ultrastructure
- NAD/metabolism
- Oxidation-Reduction
- Protein Binding
- Protein Interaction Domains and Motifs
- Ruthenium Compounds/pharmacology
- Synapses/drug effects
- Synapses/metabolism
- Synapses/ultrastructure
- Synaptic Transmission
- Zebrafish
- Zebrafish Proteins/agonists
- Zebrafish Proteins/antagonists & inhibitors
- Zebrafish Proteins/chemistry
- Zebrafish Proteins/genetics
- Zebrafish Proteins/metabolism
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Affiliation(s)
- Hiu-tung C Wong
- Section on Sensory Cell Development and FunctionNational Institute on Deafness and Other Communication Disorders, National Institutes of HealthBethesdaUnited States
- National Institutes of Health-Johns Hopkins University Graduate Partnership ProgramNational Institute on Deafness and Other Communication Disorders, National Institutes of HealthBethesdaUnited States
| | - Qiuxiang Zhang
- Section on Sensory Cell Development and FunctionNational Institute on Deafness and Other Communication Disorders, National Institutes of HealthBethesdaUnited States
| | - Alisha J Beirl
- Section on Sensory Cell Development and FunctionNational Institute on Deafness and Other Communication Disorders, National Institutes of HealthBethesdaUnited States
| | - Ronald S Petralia
- Advanced Imaging CoreNational Institute on Deafness and Other Communication Disorders, National Institutes of HealthBethesdaUnited States
| | - Ya-Xian Wang
- Advanced Imaging CoreNational Institute on Deafness and Other Communication Disorders, National Institutes of HealthBethesdaUnited States
| | - Katie Kindt
- Section on Sensory Cell Development and FunctionNational Institute on Deafness and Other Communication Disorders, National Institutes of HealthBethesdaUnited States
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25
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Pickett SB, Raible DW. Water Waves to Sound Waves: Using Zebrafish to Explore Hair Cell Biology. J Assoc Res Otolaryngol 2019; 20:1-19. [PMID: 30635804 DOI: 10.1007/s10162-018-00711-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 12/19/2018] [Indexed: 01/09/2023] Open
Abstract
Although perhaps best known for their use in developmental studies, over the last couple of decades, zebrafish have become increasingly popular model organisms for investigating auditory system function and disease. Like mammals, zebrafish possess inner ear mechanosensory hair cells required for hearing, as well as superficial hair cells of the lateral line sensory system, which mediate detection of directional water flow. Complementing mammalian studies, zebrafish have been used to gain significant insights into many facets of hair cell biology, including mechanotransduction and synaptic physiology as well as mechanisms of both hereditary and acquired hair cell dysfunction. Here, we provide an overview of this literature, highlighting some of the particular advantages of using zebrafish to investigate hearing and hearing loss.
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Affiliation(s)
- Sarah B Pickett
- Department of Biological Structure, University of Washington, Health Sciences Building H-501, 1959 NE Pacific Street, Box 357420, Seattle, WA, 98195-7420, USA
- Graduate Program in Neuroscience, University of Washington, 1959 NE Pacific Street, Box 357270, Seattle, WA, 98195-7270, USA
| | - David W Raible
- Department of Biological Structure, University of Washington, Health Sciences Building H-501, 1959 NE Pacific Street, Box 357420, Seattle, WA, 98195-7420, USA.
- Graduate Program in Neuroscience, University of Washington, 1959 NE Pacific Street, Box 357270, Seattle, WA, 98195-7270, USA.
- Virginia Merrill Bloedel Hearing Research Center, University of Washington, 1701 NE Columbia Rd, Box 357923, Seattle, WA, 98195-7923, USA.
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