Disease relevance of Hair Cells

• Alfalfa root hair cells were impaled with intracellular microelectrodes to measure a membrane potential depolarizing activity in Rhizobium meliloti cell-free filtrates, a plant response dependent on the bacterial nodulation genes [1].
• Cisplatin, a commonly used antineoplastic agent, destroys the sensory hair cells in the cochlear and vestibular system leading to irreversible hearing loss and balance problems [2].
• Detected by immunocytochemistry in staged chicken embryos, in the otocyst, neural cell adhesion molecule, but not L1-cell adhesion molecule, was localized to the ganglion and hair cell precursors [3].
• A cell permeable peptide designed specifically to inhibit JNK signaling has proven successful in in vivo models of both neuronal degeneration following cerebral ischemia and auditory hair cell degeneration following exposure to either acoustic trauma or a toxic level of an aminoglycoside antibiotic [4].
• Gentamicin has preferential toxicity for the hair cells in the central zone of the crista, where irregular afferents predominate [5].

High impact information on Hair Cells

• In specific cases, extracellular and/or CSK proteins (i.e., tethers) may transmit mechanical forces to the process (e.g., hair cell MG channels, MS intracellular Ca(2+) release, and transmitter release) without increasing tension in the lipid bilayer [6].
• Dominant and recessive deafness caused by mutations of a novel gene, TMC1, required for cochlear hair-cell function [7].
• Tmc1 mRNA is expressed in hair cells of the postnatal mouse cochlea and vestibular end organs and is required for normal function of cochlear hair cells [7].
• We demonstrate Cdh23 expression in the neurosensory epithelium and show that during early hair-cell differentiation, stereocilia organization is disrupted in v(2J) homozygotes [8].
• Cochlear hair cells in the av mutants show abnormal stereocilia by 10 days after birth (P10) [9].

Chemical compound and disease context of Hair Cells

• AMPA-type glutamate receptor subunits are expressed in the avian cochlear hair cells and ganglion cells [10].
• We investigated the potential for hair cell regeneration in neonatal rat organs of Corti grown in culture following destruction of hair cells by neomycin toxicity [11].
• Streptomycin-treated rats exhibited almost complete destruction of sensory hair cells in the crista ampullaris, vestibular impairment in the drop test, and hyperkinesia [12].
• GABA-T-like immunoreactivity, indicative of GABA degradation, was found around hair cells, along nerve fibers running through the stroma and within the ganglion cell [13].
• Glutamate (Glu) is neurotoxic in the neonatal rat cochlea, producing hearing impairment which is largely due to the death of spiral ganglion cells, whereas the receptor hair cells are spared [14].

Biological context of Hair Cells

• Retinoic acid-stimulated hair cell regeneration can be blocked by cytosine arabinoside, which suggests that a period of mitosis is required for the regeneration of auditory hair cells in this system [15].
• A developmental conundrum: a stabilized form of beta-catenin lacking the transcriptional activation domain triggers features of hair cell fate in epidermal cells and epidermal cell fate in hair follicle cells [16].
• The alpha9 acetylcholine receptor (alpha9 AChR) is specifically expressed in hair cells of the inner ear and is believed to be involved in synaptic transmission between efferent nerves and hair cells [17].
• The presence of a specific calcium-binding activity at such high levels suggests an important function for cochlear calbindin (BPP23) in hair cell calcium homeostasis and auditory transduction [18].
• In an effort to understand the molecular mechanisms that determine hair cell fate in the inner ear, and with the goal of developing a valuable tool for gene therapy and for the generation of conditional knockouts, we initiated a search for cis-acting DNA sequences that regulate the expression of the murine Myo7a and human MYO7A genes [19].

Anatomical context of Hair Cells

• We showed that, in the mouse inner ear, only the sensory hair cells express harmonin [20].
• In the cochlea, the protein Atp2b2 is localized to stereocilia and the basolateral wall of hair cells in wild-type mice, but is not detected in dfw2J mice [21].
• These mutations affecting Atp2b2 in dfw and dfw2J are the first to be found in a mammalian plasma membrane calcium pump and define a new class of deafness genes that directly affect hair-cell physiology [21].
• The tectorial membrane is an extracellular matrix of the inner ear that contacts the stereocilia bundles of specialized sensory hair cells [22].
• In contrast, treatment with retinoic acid does not stimulate the formation of extra hair cells in control cultures of Corti's organ [15].

Associations of Hair Cells with chemical compounds

• Alpha 9: an acetylcholine receptor with novel pharmacological properties expressed in rat cochlear hair cells [23].
• Our data suggest that integrin alpha8beta1, and potentially other integrins, regulates hair-cell differentiation and stereocilia maturation [24].
• Here we show that proliferation is induced in the undamaged receptor epithelium by agents that increase cyclic AMP levels, and that following this stimulation hair cells become labeled with proliferation markers [25].
• Retinoic acid stimulates regeneration of mammalian auditory hair cells [15].
• We have studied spatial Ca2+ distribution in hair cells filled with the low affinity fluorescent indicator Calcium Green 5N using real-time confocal microscopy and whole-cell recording [26].

Gene context of Hair Cells

• In addition, genetic deletion of Jag2 results in a significant increase in sensory hair cells, presumably as a result of a decrease in Notch activation [27].
• A defect in harmonin, a PDZ domain-containing protein expressed in the inner ear sensory hair cells, underlies Usher syndrome type 1C [20].
• Reduced climbing and increased slipping adaptation in cochlear hair cells of mice with Myo7a mutations [28].
• The transcription factor Math1 (encoded by the gene Atoh1, also called Math1) is required for the formation of mechanosensory hair cells in the inner ear; however, its specific molecular role is unknown [29].
• Accordingly, the gene was given the name "tetraspan membrane protein of hair cell stereocilia," symbol Tmhs [30].

Analytical, diagnostic and therapeutic context of Hair Cells

• 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 [31].
• In both embryonic and postembryonic ears new hair cells have been identified by scanning electron microscopy and through uptake of radioactively labeled thymidine [32].
• In situ hybridization with late embryonic inner ear tissue reveals that Hes1 is expressed in supporting cells, but not hair cells, of the vestibular sensory epithelium [33].
• In addition, double labeling with calretinin and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) revealed that differentiated hair cells underwent apoptosis during normal development at late embryonic and early postnatal stages in vivo and in vitro [34].
• RT-PCR analysis shows that Hes1 is expressed in inner ear during hair cell differentiation and its expression is maintained in adulthood [33].

References