scholarly journals Putative pore-forming subunits of the mechano-electrical transduction channel, Tmc1/2b, require Tmie to localize to the site of mechanotransduction in zebrafish sensory hair cells

2018 ◽  
Author(s):  
Itallia V. Pacentine ◽  
Teresa Nicolson
Keyword(s):  
Hair Cell ◽  
Inner Ear ◽  
Hair Cells ◽  
Transmembrane Domain ◽  
Cell Activity ◽  
Sensory Hair ◽  
Transmembrane Channel ◽  
Extracellular Region ◽  
Normal Site ◽  
Sensory Hair Cells

AbstractMutations in transmembrane inner ear (TMIE) cause deafness in humans; previous studies suggest involvement in the mechano-electrical transduction (MET) complex in sensory hair cells, but TMIE’s precise role is unclear. In tmie zebrafish mutants, we observed that GFP-tagged Tmc1 and Tmc2b, which are putative subunits of the MET channel, fail to target to the hair bundle. In contrast, overexpression of Tmie strongly enhances the targeting of Tmc2b-GFP to stereocilia. To identify the motifs of Tmie underlying the regulation of the Tmcs, we systematically deleted or replaced peptide segments. We then assessed localization and functional rescue of each mutated/chimeric form of Tmie in tmie mutants. We determined that the first putative helix was dispensable and identified a novel critical region of Tmie, the extracellular region and transmembrane domain, which mediates both mechanosensitivity and Tmc2b-GFP expression in bundles. Collectively, our results suggest that Tmie’s role in sensory hair cells is to target and stabilize Tmc subunits to the site of MET.Author summaryHair cells mediate hearing and balance through the activity of a pore-forming channel in the cell membrane. The transmembrane inner ear (TMIE) protein is an essential component of the protein complex that gates this so-called mechanotransduction channel. While it is known that loss of TMIE results in deafness, the function of TMIE within the complex is unclear. Using zebrafish as a deafness model, Pacentine and Nicolson demonstrate that Tmie is required for the localization of other essential complex members, the transmembrane channel-like (Tmc) proteins, Tmc1/2b. They then evaluate twelve unique versions of Tmie, each containing mutations to different domains of Tmie. This analysis reveals that some mutations in Tmie cause dysfunctional gating of the channel as demonstrated through reduced hair cell activity, and that these same dysfunctional versions also display reduced Tmc expression at the normal site of the channel. These findings link hair cell activity with the levels of Tmc in the bundle, reinforcing the currently-debated notion that the Tmcs are the pore-forming subunits of the mechanotransduction channel. The authors conclude that Tmie, through distinct regions, is involved in both trafficking and stabilizing the Tmcs at the site of mechanotransduction.

scholarly journals Identification of a 275-kD protein associated with the apical surfaces of sensory hair cells in the avian inner ear.

1990 ◽  
Vol 110 (4) ◽  
pp. 1055-1066 ◽  
Author(s):  
G P Richardson ◽  
S Bartolami ◽  
I J Russell
Keyword(s):  
Hair Cell ◽  
Inner Ear ◽  
Hair Cells ◽  
Proximal Region ◽  
Basilar Papilla ◽  
Relative Molecular Mass ◽  
Apical Surface ◽  
Sensory Hair ◽  
Sensory Hair Cells ◽  
Avian Inner Ear

Immunological techniques have been used to generate both polyclonal and monoclonal antibodies specific for the apical ends of sensory hair cells in the avian inner ear. The hair cell antigen recognized by these antibodies is soluble in nonionic detergent, behaves on sucrose gradients primarily as a 16S particle, and, after immunoprecipitation, migrates as a polypeptide with a relative molecular mass of 275 kD on 5% SDS gels under reducing conditions. The antigen can be detected with scanning immunoelectron microscopy on the apical surface of the cell and on the stereocilia bundle but not on the kinocilium. Double label studies indicate that the entire stereocilia bundle is stained in the lagena macula (a vestibular organ), whereas in the basilar papilla (an auditory organ) only the proximal region of the stereocilia bundle nearest to the apical surface is stained. The monoclonal anti-hair cell antibodies do not stain brain, tongue, lung, liver, heart, crop, gizzard, small intestine, skeletal muscle, feather, skin, or eye tissues but do specifically stain renal corpuscles in the kidney. Experiments using organotypic cultures of the embryonic lagena macula indicate that the antibodies cause a significant increase in the steady-state stiffness of the stereocilia bundle but do not inhibit mechanotransduction. The antibodies should provide a suitable marker and/or tool for the purification of the apical sensory membrane of the hair cell.

Hearing loss caused by progressive degeneration of cochlear hair cells in mice deficient for the Barhl1 homeobox gene

Development ◽  
2002 ◽  
Vol 129 (14) ◽  
pp. 3523-3532 ◽  
Author(s):  
Shengguo Li ◽  
Sandy M. Price ◽  
Hugh Cahill ◽  
David K. Ryugo ◽  
Michael M. Shen ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Hair Cell ◽  
Inner Ear ◽  
Hair Cells ◽  
Organ Of Corti ◽  
Cochlear Hair Cells ◽  
Sensory Hair ◽  
Progressive Degeneration ◽  
Age Related ◽  
Sensory Hair Cells

The cochlea of the mammalian inner ear contains three rows of outer hair cells and a single row of inner hair cells. These hair cell receptors reside in the organ of Corti and function to transduce mechanical stimuli into electrical signals that mediate hearing. To date, the molecular mechanisms underlying the maintenance of these delicate sensory hair cells are unknown. We report that targeted disruption of Barhl1, a mouse homolog of the Drosophila BarH homeobox genes, results in severe to profound hearing loss, providing a unique model for the study of age-related human deafness disorders. Barhl1 is expressed in all sensory hair cells during inner ear development, 2 days after the onset of hair cell generation. Loss of Barhl1 function in mice results in age-related progressive degeneration of both outer and inner hair cells in the organ of Corti, following two reciprocal longitudinal gradients. Our data together indicate an essential role for Barhl1 in the long-term maintenance of cochlear hair cells, but not in the determination or differentiation of these cells.

The role of Math1 in inner ear development: Uncoupling the establishment of the sensory primordium from hair cell fate determination

Development ◽  
2002 ◽  
Vol 129 (10) ◽  
pp. 2495-2505 ◽  
Author(s):  
Ping Chen ◽  
Jane E. Johnson ◽  
Huda Y. Zoghbi ◽  
Neil Segil
Keyword(s):  
Hair Cell ◽  
Inner Ear ◽  
Cell Fate ◽  
Hair Cells ◽  
Organ Of Corti ◽  
Sensory Epithelium ◽  
Proliferating Cells ◽  
Sensory Hair ◽  
Sensory Hair Cells ◽  
Hair Cell Differentiation

During embryonic development of the inner ear, the sensory primordium that gives rise to the organ of Corti from within the cochlear epithelium is patterned into a stereotyped array of inner and outer sensory hair cells separated from each other by non-sensory supporting cells. Math1, a close homolog of the Drosophila proneural gene atonal, has been found to be both necessary and sufficient for the production of hair cells in the mouse inner ear. Our results indicate that Math1 is not required to establish the postmitotic sensory primordium from which the cells of the organ of Corti arise, but instead is limited to a role in the selection and/or differentiation of sensory hair cells from within the established primordium. This is based on the observation that Math1 is only expressed after the appearance of a zone of non-proliferating cells that delineates the sensory primordium within the cochlear anlage. The expression of Math1 is limited to a subpopulation of cells within the sensory primordium that appear to differentiate exclusively into hair cells as the sensory epithelium matures and elongates through a process that probably involves radial intercalation of cells. Furthermore, mutation of Math1 does not affect the establishment of this postmitotic sensory primordium, even though the subsequent generation of hair cells is blocked in these mutants. Finally, in Math1 mutant embryos, a subpopulation of the cells within the sensory epithelium undergo apoptosis in a temporal gradient similar to the basal-to-apical gradient of hair cell differentiation that occurs in the cochlea of wild-type animals.

scholarly journals Cross-regulation of Ngn1 and Math1 coordinates the production of neurons and sensory hair cells during inner ear development

Development ◽  
2007 ◽  
Vol 134 (24) ◽  
pp. 4405-4415 ◽  
Author(s):  
S. Raft ◽  
E. J. Koundakjian ◽  
H. Quinones ◽  
C. S. Jayasena ◽  
L. V. Goodrich ◽  
...  
Keyword(s):  
Inner Ear ◽  
Hair Cells ◽  
Sensory Hair ◽  
Ear Development ◽  
Inner Ear Development ◽  
Sensory Hair Cells

scholarly journals Multiple PDZ domain protein maintains patterning of the apical cytoskeleton in sensory hair cells

Development ◽  
2021 ◽  
Author(s):  
Amandine Jarysta ◽  
Basile Tarchini
Keyword(s):  
Hair Cell ◽  
Hair Cells ◽  
Critical Role ◽  
Pdz Domain ◽  
Hair Bundle ◽  
Structural Defects ◽  
Sensory Hair ◽  
High Frequencies ◽  
Sensory Hair Cells ◽  
Sound Transduction

Sound transduction occurs in the hair bundle, the apical compartment of sensory hair cells in the inner ear. The hair bundle is formed of actin-based stereocilia aligned in rows of graded heights. It was previously shown that the GNAI-GPSM2 complex is part of a developmental blueprint that defines the polarized organization of the apical cytoskeleton in hair cells, including stereocilia distribution and elongation. Here we report a novel and critical role for Multiple PDZ domain (MPDZ) protein during apical hair cell morphogenesis. We show that MPDZ is enriched at the hair cell apical membrane along with MAGUK p55 subfamily member 5 (MPP5/PALS1) and the Crumbs protein CRB3. MPDZ is required there to maintain the proper segregation of apical blueprints proteins, including GNAI-GPSM2. Loss of the blueprint coincides with misaligned stereocilia placement in Mpdz mutant hair cells, and results in permanently misshapen hair bundles. Graded molecular and structural defects along the cochlea can explain the profile of hearing loss in Mpdz mutants, where deficits are most severe at high frequencies.

Comparing Sensory Organs to Define the Path for Hair Cell Regeneration

2019 ◽  
Vol 35 (1) ◽  
pp. 567-589 ◽  
Author(s):  
Nicolas Denans ◽  
Sungmin Baek ◽  
Tatjana Piotrowski
Keyword(s):  
Hair Cell ◽  
Olfactory Epithelium ◽  
Current Literature ◽  
Hair Cells ◽  
Sensory Cell ◽  
Cell Regeneration ◽  
Hair Cell Regeneration ◽  
Sensory Hair ◽  
Sensory Hair Cells ◽  
Technical Advances

Deafness or hearing deficits are debilitating conditions. They are often caused by loss of sensory hair cells or defects in their function. In contrast to mammals, nonmammalian vertebrates robustly regenerate hair cells after injury. Studying the molecular and cellular basis of nonmammalian vertebrate hair cell regeneration provides valuable insights into developing cures for human deafness. In this review, we discuss the current literature on hair cell regeneration in the context of other models for sensory cell regeneration, such as the retina and the olfactory epithelium. This comparison reveals commonalities with, as well as differences between, the different regenerating systems, which begin to define a cellular and molecular blueprint of regeneration. In addition, we propose how new technical advances can address outstanding questions in the field.

scholarly journals In vivo base editing restores sensory transduction and transiently improves auditory function in a mouse model of recessive deafness

2020 ◽  
Vol 12 (546) ◽  
pp. eaay9101 ◽  
Author(s):  
Wei-Hsi Yeh ◽  
Olga Shubina-Oleinik ◽  
Jonathan M. Levy ◽  
Bifeng Pan ◽  
Gregory A. Newby ◽  
...  
Keyword(s):  
Hair Cell ◽  
Point Mutation ◽  
Hair Cells ◽  
Point Mutations ◽  
Sensory Transduction ◽  
Auditory Function ◽  
Sensory Hair ◽  
Base Editing ◽  
Sensory Hair Cells

Most genetic diseases arise from recessive point mutations that require correction, rather than disruption, of the pathogenic allele to benefit patients. Base editing has the potential to directly repair point mutations and provide therapeutic restoration of gene function. Mutations of transmembrane channel-like 1 gene (TMC1) can cause dominant or recessive deafness. We developed a base editing strategy to treat Baringo mice, which carry a recessive, loss-of-function point mutation (c.A545G; resulting in the substitution p.Y182C) in Tmc1 that causes deafness. Tmc1 encodes a protein that forms mechanosensitive ion channels in sensory hair cells of the inner ear and is required for normal auditory function. We found that sensory hair cells of Baringo mice have a complete loss of auditory sensory transduction. To repair the mutation, we tested several optimized cytosine base editors (CBEmax variants) and guide RNAs in Baringo mouse embryonic fibroblasts. We packaged the most promising CBE, derived from an activation-induced cytidine deaminase (AID), into dual adeno-associated viruses (AAVs) using a split-intein delivery system. The dual AID-CBEmax AAVs were injected into the inner ears of Baringo mice at postnatal day 1. Injected mice showed up to 51% reversion of the Tmc1 c.A545G point mutation to wild-type sequence (c.A545A) in Tmc1 transcripts. Repair of Tmc1 in vivo restored inner hair cell sensory transduction and hair cell morphology and transiently rescued low-frequency hearing 4 weeks after injection. These findings provide a foundation for a potential one-time treatment for recessive hearing loss and support further development of base editing to correct pathogenic point mutations.

Sign in / Sign up

Export Citation Format

Share Document