scholarly journals Regulation of otocyst patterning by Tbx2 and Tbx3 is required for inner ear morphogenesis in the mouse

Development ◽  
2021 ◽  
Vol 148 (8) ◽  
Author(s):  
Marina Kaiser ◽  
Irina Wojahn ◽  
Carsten Rudat ◽  
Timo H. Lüdtke ◽  
Vincent M. Christoffels ◽  
...  
Keyword(s):  
Inner Ear ◽  
Hair Cells ◽  
Regulatory Network ◽  
Transcriptional Repressors ◽  
Afferent Neurons ◽  
Loss Of Function ◽  
Sensory Hair ◽  
T Box ◽  
Sensory Hair Cells ◽  
Fgf Signalling

ABSTRACT All epithelial components of the inner ear, including sensory hair cells and innervating afferent neurons, arise by patterning and differentiation of epithelial progenitors residing in a simple sphere, the otocyst. Here, we identify the transcriptional repressors TBX2 and TBX3 as novel regulators of these processes in the mouse. Ablation of Tbx2 from the otocyst led to cochlear hypoplasia, whereas loss of Tbx3 was associated with vestibular malformations. The loss of function of both genes (Tbx2/3cDKO) prevented inner ear morphogenesis at midgestation, resulting in indiscernible cochlear and vestibular structures at birth. Morphogenetic impairment occurred concomitantly with increased apoptosis in ventral and lateral regions of Tbx2/3cDKO otocysts around E10.5. Expression analyses revealed partly disturbed regionalisation, and a posterior-ventral expansion of the neurogenic domain in Tbx2/3cDKO otocysts at this stage. We provide evidence that repression of FGF signalling by TBX2 is important to restrict neurogenesis to the anterior-ventral otocyst and implicate another T-box factor, TBX1, as a crucial mediator in this regulatory network.

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

Cod106, a novel synaptic protein expressed in sensory hair cells of the inner ear and in CNS neurons

2005 ◽  
Vol 28 (1) ◽  
pp. 106-117 ◽  
Author(s):  
Ellen Reisinger ◽  
Ulrike Zimmermann ◽  
Marlies Knipper ◽  
Jost Ludwig ◽  
Nikolaj Klöcker ◽  
...  
Keyword(s):  
Inner Ear ◽  
Hair Cells ◽  
Synaptic Protein ◽  
Sensory Hair ◽  
Sensory Hair Cells ◽  
Cns Neurons

scholarly journals HCN Channels Are Not Required for Mechanotransduction in Sensory Hair Cells of the Mouse Inner Ear

PLoS ONE ◽  
2010 ◽  
Vol 5 (1) ◽  
pp. e8627 ◽  
Author(s):  
Geoffrey C. Horwitz ◽  
Andrea Lelli ◽  
Gwenaëlle S. G. Géléoc ◽  
Jeffrey R. Holt
Keyword(s):  
Inner Ear ◽  
Hair Cells ◽  
Hcn Channels ◽  
Sensory Hair ◽  
Sensory Hair Cells

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.

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