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Lukashkina VA, Levic S, Simões P, Xu Z, Li Y, Haugen T, Zuo J, Lukashin AN, Russell IJ. Optogenetics Reveals Roles for Supporting Cells in Force Transmission to and From Outer Hair Cells in the Mouse Cochlea. J Neurosci 2024; 44:e1179232023. [PMID: 38050104 PMCID: PMC10860482 DOI: 10.1523/jneurosci.1179-23.2023] [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: 06/26/2023] [Revised: 11/01/2023] [Accepted: 11/13/2023] [Indexed: 12/06/2023] Open
Abstract
Outer hair cells (OHCs) of the organ of Corti (OoC), acting as bidirectional cellular mechanoelectrical transducers, generate, receive, and exchange forces with other major elements of the cochlear partition, including the sensory inner hair cells (IHCs). Force exchange is mediated via a supporting cell scaffold, including Deiters' (DC) and outer pillar cells (OPC), to enable the sensitivity and exquisite frequency selectivity of the mammalian cochlea and to transmit its responses to the auditory nerve. To selectively activate DCs and OPCs in male and female mice, we conditionally expressed in them a hyperpolarizing halorhodopsin (HOP), a light-gated inward chloride ion pump, and measured extracellular receptor potentials (ERPs) and their DC component (ERPDCs) from the cortilymph, which fills the OoC fluid spaces, and compared the responses with similar potentials from HOP-/- littermates. The compound action potentials (CAP) of the auditory nerve were measured as an indication of IHC activity and transmission of cochlear responses to the CNS. HOP light-activated hyperpolarization of DCs and OPCs suppressed cochlear amplification through changing the timing of its feedback, altered basilar membrane (BM) responses to tones at all measured levels and frequencies, and reduced IHC excitation. HOP activation findings reported here complement recent studies that revealed channelrhodopsin activation depolarized DCs and OPCs and effectively bypassed, rather than blocked, the control of OHC mechanical and electrical responses to sound and their contribution to timed and directed electromechanical feedback to the mammalian cochlea. Moreover, our findings identify DCs and OPCs as potential targets for the treatment of noise-induced hearing loss.
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Affiliation(s)
- Victoria A Lukashkina
- Sensory Neuroscience Research Group, School of Applied Sciences, University of Brighton, Brighton BN2 4GJ, United Kingdom
| | - Snezana Levic
- Sensory Neuroscience Research Group, School of Applied Sciences, University of Brighton, Brighton BN2 4GJ, United Kingdom
- Brighton and Sussex Medical School, University of Sussex, Brighton BN1 9PX, United Kingdom
| | - Patricio Simões
- Sensory Neuroscience Research Group, School of Applied Sciences, University of Brighton, Brighton BN2 4GJ, United Kingdom
| | - Zhenhang Xu
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska 68178
| | - Yuju Li
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska 68178
| | - Trevor Haugen
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska 68178
| | - Jian Zuo
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, Nebraska 68178 ,
- Ting Therapeutics, 9310 Athena Circle, San Diego, California 92037
| | - Andrei N Lukashin
- Sensory Neuroscience Research Group, School of Applied Sciences, University of Brighton, Brighton BN2 4GJ, United Kingdom ,
| | - Ian J Russell
- Sensory Neuroscience Research Group, School of Applied Sciences, University of Brighton, Brighton BN2 4GJ, United Kingdom ,
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Beaulac HJ, Munnamalai V. Localization of Cadherins in the postnatal cochlear epithelium and their relation to space formation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.09.30.560287. [PMID: 37808730 PMCID: PMC10557783 DOI: 10.1101/2023.09.30.560287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
The sensory epithelium of the cochlea, the organ of Corti, has complex cytoarchitecture consisting of mechanosensory hair cells intercalated by epithelial support cells. The support cells provide important trophic and structural support to the hair cells. Thus, the support cells must be stiff yet compliant enough to withstand and modulate vibrations to the hair cells. Once the sensory cells are properly patterned, the support cells undergo significant remodeling from a simple epithelium into a structurally rigid epithelium with fluid-filled spaces in the murine cochlea. Cell adhesion molecules such as cadherins are necessary for sorting and connecting cells in an intact epithelium. To create the fluid-filled spaces, cell adhesion properties of adjoining cell membranes between cells must change to allow the formation of spaces within an epithelium. However, the dynamic localization of cadherins has not been properly analyzed as these spaces are formed. There are three cadherins that are reported to be expressed during the first postnatal week of development when the tunnel of Corti forms in the cochlea. In this study, we characterize the dynamic localization of cadherins that are associated with cytoskeletal remodeling at the contacting membranes of the inner and outer pillar cells flanking the tunnel of Corti. Key findings F-actin remodeling occurs between E18.5 to P7 in the cochlear sensory epithelium.Transient changes of F-actin cytoskeleton drives epithelial morphogenesis.Fluid-filled spaces in epithelium is driven by changes in cell adhesion.
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Patil MJ, Kim SH, Bahia PK, Nair SS, Darcey TS, Fiallo J, Zhu XX, Frisina RD, Hadley SH, Taylor-Clark TE. A Novel Flp Reporter Mouse Shows That TRPA1 Expression Is Largely Limited to Sensory Neuron Subsets. eNeuro 2023; 10:ENEURO.0350-23.2023. [PMID: 37989590 PMCID: PMC10698635 DOI: 10.1523/eneuro.0350-23.2023] [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: 09/11/2023] [Revised: 11/09/2023] [Accepted: 11/11/2023] [Indexed: 11/23/2023] Open
Abstract
Transient receptor potential ankyrin 1 (TRPA1) is a polymodal cation channel that is activated by electrophilic irritants, oxidative stress, cold temperature, and GPCR signaling. TRPA1 expression has been primarily identified in subsets of nociceptive sensory afferents and is considered a target for future analgesics. Nevertheless, TRPA1 has been implicated in other cell types including keratinocytes, epithelium, enterochromaffin cells, endothelium, astrocytes, and CNS neurons. Here, we developed a knock-in mouse that expresses the recombinase FlpO in TRPA1-expressing cells. We crossed the TRPA1Flp mouse with the R26ai65f mouse that expresses tdTomato in a Flp-sensitive manner. We found tdTomato expression correlated well with TRPA1 mRNA expression and sensitivity to TRPA1 agonists in subsets of TRPV1 (transient receptor potential vanilloid receptor type 1)-expressing neurons in the vagal ganglia and dorsal root ganglia (DRGs), although tdTomato expression efficiency was limited in DRG. We observed tdTomato-expressing afferent fibers centrally (in the medulla and spinal cord) and peripherally in the esophagus, gut, airways, bladder, and skin. Furthermore, chemogenetic activation of TRPA1-expressing nerves in the paw evoked flinching behavior. tdTomato expression was very limited in other cell types. We found tdTomato in subepithelial cells in the gut mucosa but not in enterochromaffin cells. tdTomato was also observed in supporting cells within the cochlea, but not in hair cells. Lastly, tdTomato was occasionally observed in neurons in the somatomotor cortex and the piriform area, but not in astrocytes or vascular endothelium. Thus, this novel mouse strain may be useful for mapping and manipulating TRPA1-expressing cells and deciphering the role of TRPA1 in physiological and pathophysiological processes.
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Affiliation(s)
- Mayur J Patil
- Molecular Pharmacology & Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612
| | - Seol-Hee Kim
- Molecular Pharmacology & Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612
| | - Parmvir K Bahia
- Molecular Pharmacology & Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612
| | - Sanjay S Nair
- Molecular Pharmacology & Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612
| | - Teresa S Darcey
- Molecular Pharmacology & Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612
| | - Jailene Fiallo
- Molecular Pharmacology & Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612
| | - Xiao Xia Zhu
- Medical Engineering, College of Engineering, University of South Florida, Tampa, Florida 33620
| | - Robert D Frisina
- Medical Engineering, College of Engineering, University of South Florida, Tampa, Florida 33620
| | - Stephen H Hadley
- Molecular Pharmacology & Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612
| | - Thomas E Taylor-Clark
- Molecular Pharmacology & Physiology, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612
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Lazzeri G, Biagioni F, Ferrucci M, Puglisi-Allegra S, Lenzi P, Busceti CL, Giannessi F, Fornai F. The Relevance of Autophagy within Inner Ear in Baseline Conditions and Tinnitus-Related Syndromes. Int J Mol Sci 2023; 24:16664. [PMID: 38068993 PMCID: PMC10706730 DOI: 10.3390/ijms242316664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 11/07/2023] [Accepted: 11/21/2023] [Indexed: 12/18/2023] Open
Abstract
Tinnitus is the perception of noise in the absence of acoustic stimulation (phantom noise). In most patients suffering from chronic peripheral tinnitus, an alteration of outer hair cells (OHC) starting from the stereocilia (SC) occurs. This is common following ototoxic drugs, sound-induced ototoxicity, and acoustic degeneration. In all these conditions, altered coupling between the tectorial membrane (TM) and OHC SC is described. The present review analyzes the complex interactions involving OHC and TM. These need to be clarified to understand which mechanisms may underlie the onset of tinnitus and why the neuropathology of chronic degenerative tinnitus is similar, independent of early triggers. In fact, the fine neuropathology of tinnitus features altered mechanisms of mechanic-electrical transduction (MET) at the level of OHC SC. The appropriate coupling between OHC SC and TM strongly depends on autophagy. The involvement of autophagy may encompass degenerative and genetic tinnitus, as well as ototoxic drugs and acoustic trauma. Defective autophagy explains mitochondrial alterations and altered protein handling within OHC and TM. This is relevant for developing novel treatments that stimulate autophagy without carrying the burden of severe side effects. Specific phytochemicals, such as curcumin and berberin, acting as autophagy activators, may mitigate the neuropathology of tinnitus.
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Affiliation(s)
- Gloria Lazzeri
- Human Anatomy, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, PI, Italy; (G.L.); (M.F.); (P.L.); (F.G.)
| | - Francesca Biagioni
- IRCCS, Istituto di Ricovero e Cura a Carattere Scientifico, Neuromed, 86077 Pozzilli, IS, Italy; (F.B.); (S.P.-A.); (C.L.B.)
| | - Michela Ferrucci
- Human Anatomy, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, PI, Italy; (G.L.); (M.F.); (P.L.); (F.G.)
| | - Stefano Puglisi-Allegra
- IRCCS, Istituto di Ricovero e Cura a Carattere Scientifico, Neuromed, 86077 Pozzilli, IS, Italy; (F.B.); (S.P.-A.); (C.L.B.)
| | - Paola Lenzi
- Human Anatomy, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, PI, Italy; (G.L.); (M.F.); (P.L.); (F.G.)
| | - Carla Letizia Busceti
- IRCCS, Istituto di Ricovero e Cura a Carattere Scientifico, Neuromed, 86077 Pozzilli, IS, Italy; (F.B.); (S.P.-A.); (C.L.B.)
| | - Francesco Giannessi
- Human Anatomy, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, PI, Italy; (G.L.); (M.F.); (P.L.); (F.G.)
| | - Francesco Fornai
- Human Anatomy, Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, 56126 Pisa, PI, Italy; (G.L.); (M.F.); (P.L.); (F.G.)
- IRCCS, Istituto di Ricovero e Cura a Carattere Scientifico, Neuromed, 86077 Pozzilli, IS, Italy; (F.B.); (S.P.-A.); (C.L.B.)
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