Development of Sensory and Neural Structures in the Mammalian Cochlea

Pujol, Rémy; Lavigne‐Rebillard, Mireille; Lenoir, Marc

doi:10.1007/978-1-4612-2186-9_4

Cited by 149 publications

(182 citation statements)

References 117 publications

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“…Morphologically, IHCs of TH-deficient organs of Corti continued to have large numbers of ribbons and immature synaptic contacts (e.g., showing several ribbons) at least up to P15, when normal maturation and pruning have resulted in fewer and confined single ribbon synapses (Pujol et al, 1980;Shnerson et al, 1981;Sobkowicz et al, 1982;Pujol et al, 1997; this study). The IHCs of 2-week-old Pax8 Ϫ/Ϫ mice were also functionally comparable with immature wt IHCs (Fig.…”

Section: Discussionmentioning

confidence: 52%

“…Morphologically, this stage is characterized by large active zones anchoring multiple ribbons and branched afferent fibers, giving rise to multiple postsynaptic terminals (Shnerson et al, 1981;Sobkowicz et al, 1982). The number of synapses declines and active zones assume a more confined appearance anchoring a single ribbon at approximately the onset of hearing (Shnerson et al, 1981;Sobkowicz et al, 1982;Pujol et al, 1997;Nemzou et al, 2006). This structural maturation goes along with a decline of the presynaptic Ca 2ϩ current and an improvement of stimulus secretion coupling Johnson et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

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Maturation of Ribbon Synapses in Hair Cells Is Driven by Thyroid Hormone

Sendin¹,

Bulankina²,

Riedel

et al. 2007

J. Neurosci.

107

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Ribbon synapses of inner hair cells (IHCsϪ/Ϫ mice maintained the normally temporary efferent innervation. Moreover, they lacked large-conductance Ca 2ϩ -activated K ϩ channels and KCNQ4 channels. This together with the persistently increased Ca 2ϩ influx permitted continued action potential generation. We conclude that TH regulates IHC differentiation and is essential for morphological and functional maturation of their ribbon synapses. We suggest that presynaptic dysfunction of IHCs is a mechanism in congenital hypothyroid deafness.

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Section: Discussionmentioning

confidence: 52%

Section: Introductionmentioning

confidence: 99%

Maturation of Ribbon Synapses in Hair Cells Is Driven by Thyroid Hormone

Sendin¹,

Bulankina²,

Riedel

et al. 2007

J. Neurosci.

107

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“…3 H and I). During the first week of postnatal development, afferent endings onto IHCs, which show extensive branching up to this point, normally undergo pruning that results in the typical one-to-one conformation observed in adult cells (33). The disorganized afferent endings in Dmdo/Dmdo mice suggest that fibers had not undergone such pruning, further supporting the requirement of WT miR-96 for the maturation of the mammalian cochlea.…”

Section: Hair Cell Synaptic Morphology and Innervation Pattern Remainmentioning

confidence: 87%

miR-96 regulates the progression of differentiation in mammalian cochlear inner and outer hair cells

Kuhn

Johnson

Furness

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

107

123

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MicroRNAs (miRNAs) are small noncoding RNAs able to regulate a broad range of protein-coding genes involved in many biological processes. miR-96 is a sensory organ-specific miRNA expressed in the mammalian cochlea during development. Mutations in miR-96 cause nonsyndromic progressive hearing loss in humans and mice. The mouse mutant diminuendo has a single base change in the seed region of the Mir96 gene leading to widespread changes in the expression of many genes. We have used this mutant to explore the role of miR-96 in the maturation of the auditory organ. We found that the physiological development of mutant sensory hair cells is arrested at around the day of birth, before their biophysical differentiation into inner and outer hair cells. Moreover, maturation of the hair cell stereocilia bundle and remodelling of auditory nerve connections within the cochlea fail to occur in miR-96 mutants. We conclude that miR-96 regulates the progression of the physiological and morphological differentiation of cochlear hair cells and, as such, coordinates one of the most distinctive functional refinements of the mammalian auditory system. deafness | mouse model | sensory system | currents | action potentials I n the mammalian cochlea, inner hair cells (IHCs) and outer hair cells (OHCs) transduce sound into electrical responses. IHCs are the primary sensory receptors that relay sound stimuli to the brain with high temporal precision via the release of neurotransmitter from their ribbon synapses onto type I spiral ganglion neurons (1). Synaptic ribbons are specialized organelles able to tether a large number of synaptic vesicles at the cell's active zones and are thought to allow sensory cells to mediate high rates of sustained synaptic transmission, coordinated release of multiple vesicles, and temporally precise transfer of information (2). OHCs provide electromechanical amplification of the cochlear partition to enhance the sensitivity and frequency selectivity of the mammalian cochlea via voltage-dependent electromotility, which is mediated by the motor protein prestin (3) and modulated by the inhibitory efferent cholinergic system (4). Before sound-induced responses begin at the onset of hearing, which occurs at around postnatal day 12 (P12) in most rodents, hair cells undergo a precise developmental program. Although hair cell maturation is known to be influenced by many proteins (5-9), we know little about the mechanisms underlying their biophysical and morphological development, especially those involved in the functional differentiation of IHCs and OHCs that occurs from around birth (10).MicroRNAs (miRNAs) regulate posttranscriptional gene expression programs by decreasing the level of target mRNA in mammals (11) and are involved in tissue development, cell fate specification, morphogenesis, and a range of diseases (12-16). Members of the miR-183 family (miR-96, miR-182, and miR-183) are specific to sensory organs (17, 18) and are highly expressed in the inner ear (19,20), eye (17), and nose (21). In the inner ear...

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“…Because at each stage of maturation, hair cells at basal locations are more advanced than those at the apex (Pujol et al, 1998), changes in either of the parameters with development could explain the apparent tonotopic differences. However, at least for the apex, we had no evidence for developmental changes in either the maximum MET current or the adaptation time constant between P5 and P18 (Kennedy et al, 2003).…”

Section: Activation and Adaptation Of Met Channels In The Rat Cochleamentioning

confidence: 99%

The Transduction Channel Filter in Auditory Hair Cells

Ricci¹,

Kennedy²,

Crawford³

et al. 2005

J. Neurosci.

140

160

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In the first step in auditory transduction, sound-induced vibrations of the stereociliary bundles on the sensory hair cells are converted into electrical signals by opening of mechanotransducer channels. Faithful transduction and hence auditory performance will be limited by the kinetic properties of these channels. We have measured the time course of mechanotransducer currents in turtle and rat auditory hair cells during rapid deflections of the hair bundle. Current activation in the turtle had a time constant that decreased 10-fold with stimulus amplitude to a limiting value of ϳ50 s. Lowering the external Ca 2ϩ concentration slowed both activation and adaptation time constants. Similar effects were seen in hair cells tuned to low and high frequencies, but the overall kinetics was slower in low-frequency cells. In rat outer hair cells, the time courses of both activation and adaptation were at least 10-fold faster. Although activation kinetics was too fast to characterize accurately, the adaptation time constants in the rat, like the turtle, were Ca 2ϩ dependent and faster in hair cells tuned to higher frequencies. The results imply that mechanotransducer channels operate similarly in turtle and rat but are faster in the mammal to accommodate its higher frequency range of hearing. We suggest that the kinetics of channel activation and adaptation imposes a bandpass filter on transduction, with a center frequency matched to the frequencies detected by the hair cell, which may improve the signal-to-noise ratio near threshold.

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Development of Sensory and Neural Structures in the Mammalian Cochlea

Cited by 149 publications

References 117 publications

Maturation of Ribbon Synapses in Hair Cells Is Driven by Thyroid Hormone

Maturation of Ribbon Synapses in Hair Cells Is Driven by Thyroid Hormone

miR-96 regulates the progression of differentiation in mammalian cochlear inner and outer hair cells

The Transduction Channel Filter in Auditory Hair Cells

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