scholarly journals Mosaic Complementation Demonstrates a Regulatory Role for Myosin VIIa in Actin Dynamics of Stereocilia

2007 ◽  
Vol 28 (5) ◽  
pp. 1702-1712 ◽  
Author(s):  
Haydn M. Prosser ◽  
Agnieszka K. Rzadzinska ◽  
Karen P. Steel ◽  
Allan Bradley
Keyword(s):  
Bacterial Artificial Chromosome ◽  
X Chromosome ◽  
Hair Cells ◽  
Artificial Chromosome ◽  
Actin Dynamics ◽  
Null Mutant ◽  
Auditory Hair Cells ◽  
Sensory Hair Cells ◽  
Myosin Viia ◽  
Myosin Xva

ABSTRACT We have developed a bacterial artificial chromosome transgenesis approach that allowed the expression of myosin VIIa from the mouse X chromosome. We demonstrated the complementation of the Myo7a null mutant phenotype producing a fine mosaic of two types of sensory hair cells within inner ear epithelia of hemizygous transgenic females due to X inactivation. Direct comparisons between neighboring auditory hair cells that were different only with respect to myosin VIIa expression revealed that mutant stereocilia are significantly longer than those of their complemented counterparts. Myosin VIIa-deficient hair cells showed an abnormally persistent tip localization of whirlin, a protein directly linked to elongation of stereocilia, in stereocilia. Furthermore, myosin VIIa localized at the tips of all abnormally short stereocilia of mice deficient for either myosin XVa or whirlin. Our results strongly suggest that myosin VIIa regulates the establishment of a setpoint for stereocilium heights, and this novel role may influence their normal staircase-like arrangement within a bundle.

scholarly journals The challenge of hair cell regeneration

2010 ◽  
Vol 235 (4) ◽  
pp. 434-446 ◽  
Author(s):  
Andrew K Groves
Keyword(s):  
Hair Cell ◽  
Hair Cells ◽  
Electrical Energy ◽  
Cell Regeneration ◽  
Hair Cell Regeneration ◽  
Therapeutic Approaches ◽  
Auditory Hair Cells ◽  
Sensory Hair Cells ◽  
Ototoxic Drugs ◽  
Effects Of Aging

Sensory hair cells of the inner ear are responsible for translating auditory or vestibular stimuli into electrical energy that can be perceived by the nervous system. Although hair cells are exquisitely mechanically sensitive, they can be easily damaged by excessive stimulation by ototoxic drugs and by the effects of aging. In mammals, auditory hair cells are never replaced, such that cumulative damage to the ear causes progressive and permanent deafness. In contrast, non-mammalian vertebrates are capable of replacing lost hair cells, which has led to efforts to understand the molecular and cellular basis of regenerative responses in different vertebrate species. In this review, we describe recent progress in understanding the limits to hair cell regeneration in mammals and discuss the obstacles that currently exist for therapeutic approaches to hair cell replacement.

scholarly journals The stable actin core of mechanosensory stereocilia features continuous turnover of actin cross-linkers

2018 ◽  
Vol 29 (15) ◽  
pp. 1856-1865 ◽  
Author(s):  
Pallabi Roy ◽  
Benjamin J. Perrin
Keyword(s):  
Hair Cell ◽  
Hair Cells ◽  
Head Movement ◽  
Actin Filaments ◽  
Actin Dynamics ◽  
Actin Binding ◽  
Cross Linking ◽  
Sensory Hair Cells ◽  
Actin Turnover ◽  
Cross Linker

Stereocilia are mechanosensitive protrusions on the surfaces of sensory hair cells in the inner ear that detect sound, gravity, and head movement. Their cores are composed of parallel actin filaments that are cross-linked and stabilized by several actin-binding proteins, including fascin-2, plastin-1, espin, and XIRP2. The actin filaments are the most stable known, with actin turnover primarily occurring at the stereocilia tips. While stereocilia actin dynamics has been well studied, little is known about the behavior of the actin cross-linking proteins, which are the most abundant type of protein in stereocilia after actin and are critical for stereocilia morphogenesis and maintenance. Here, we developed a novel transgenic mouse to monitor EGFP-fascin-2 incorporation . In contrast to actin, EGFP-fascin-2 readily enters the stereocilia core. We also compared the effect of EGFP-fascin-2 expression on developing and mature stereocilia. When it was induced during hair cell development, we observed increases in both stereocilia length and width. Interestingly, stereocilia size was not affected when EGFP-fascin-2 was induced in adult stereocilia. Regardless of the time of induction, EGFP-fascin-2 displaced both espin and plastin-1 from stereocilia. Altering the actin cross-linker composition, even as the actin filaments exhibit little to no turnover, provides a mechanism for ongoing remodeling and repair important for stereocilia homeostasis.

Ultrastructure of superficial neuromasts in the mottled sculpin, Cottus bairdi

1989 ◽  
Vol 47 ◽  
pp. 958-959
Author(s):  
W.R. Jones ◽  
S. Coombs ◽  
J. Janssen
Keyword(s):  
Hair Cells ◽  
Lateral Line System ◽  
Electron Microscopic ◽  
Line System ◽  
Dense Cores ◽  
Sensory Hair Cells ◽  
Cytoplasmic Vesicles ◽  
Cottus Bairdi ◽  
Mottled Sculpin ◽  
Upper Third

The lateral line system of the mottled sculpin, like that of most bony fish, has both canal (CNM) and superficial (SNM) sensory end organs, neuromasts, which are distributed on the head and trunk in discrete, readily identifiable groupings (Fig. 1). CNM and SNM differ grossly in location and in overall size and shape. The former are located in subdermal canals and are larger and asymmetric in shape, The latter are located directly on the surface of the skin and are much smaller and more symmetrical It has been suggested that the two may differ at a more fundamental level in such functionally related parameters as extent of myelination of innervating fibers and the absence of efferent innervation in SNM. The present study addresses the validity of these last two features as distinguishing criteria by examining the structure of those SNM populations indicated in Fig. 1 at both the light and electron microscopic levels.All of the populations of SNM examined conform in general to previously published descriptions, consisting of a neuroepithelium composed of sensory hair cells, support cells and mantle cells, Several significant differences from these accounts have, however, emerged. Firstly, the structural composition of the innervating fibers is heterogeneous with respect to the extent of myelination. All SNM groups, with the possible exception of the TRrs and CFLs, possess both myelinated and unmyelinated fibers within the neuroepithelium proper (Fig. 2), just as do CNM. The extent of myelina- tion is quite variable, with some fibers sheath terminating just before crossing the neuroepithelial basal lamina, some just after and a few retaining their myelination all the way to the base of the hair cells in the upper third of the neuroepithelium. Secondly, all SNMs possess fibers that may, on the basis of ultrastructural criteria, be identified as efferent. Such fibers contained numerous cytoplasmic vesicles, both clear and with dense cores. In regions where such fibers closely apposed hair cells, subsynaptic cisternae were observed in the hair cell (Fig. 3).

scholarly journals Targeting CreERT2 expression to keratin 8-expressing murine simple epithelia using bacterial artificial chromosome transgenesis

2012 ◽  
Vol 21 (5) ◽  
pp. 1117-1123 ◽  
Author(s):  
Li Zhang ◽  
Boyu Zhang ◽  
Sang Jun Han ◽  
Amy N. Shore ◽  
Jeffrey M. Rosen ◽  
...  
Keyword(s):  
Bacterial Artificial Chromosome ◽  
Artificial Chromosome ◽  
Keratin 8

scholarly journals Revising the Chromosome-Specific Probes of White Hawk (Leucopternis albicollis)

Proceedings ◽  
2020 ◽  
Vol 76 (1) ◽  
pp. 1
Author(s):  
Ivanete Furo ◽  
Rafael Kretschmer ◽  
Jorge Pereira ◽  
Darren Griffin ◽  
Rebecca O’Connor ◽  
...  
Keyword(s):  
Bacterial Artificial Chromosome ◽  
Artificial Chromosome ◽  
Bird Of Prey ◽  
Inaccurate Data ◽  
Intrachromosomal Rearrangements

Leucopternis albicollis is a diurnal bird of prey with extensive karyotype reorganization. Chromosome-specific probes from this species have been used successfully to detect intrachromosomal rearrangements in different species of bird since 2010. However, some gaps were detected in this first set of probes. Here, we have obtained a new set of whole chromosome probes in order to improve the previous one; also, we have performed experiments using bacterial artificial chromosome (BAC) from chicken microchromosomes. Our results demonstrated that the microchromosomes were involved in fusion events. In addition, a new nomenclature has been proposed for the new set of probes and some inaccurate data were corrected.

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