Voltage-gated Ca2+ channel CaV1.3 subunit expressed in the hair cell epithelium of the sacculus of the trout Oncorhynchus mykiss: cloning and comparison across vertebrate classes

Ramakrishnan, Neeliyath A.; Green, Glenn E.; Pasha, Raza; Drescher, Marian J.; Swanson, Gregory S; Perin, Paola; Lakhani, Raam; Ahsan, Syed F.; Hatfield, James S.; Khan, Khalid M.; Drescher, Dennis G.

doi:10.1016/s0169-328x(02)00522-3

Cited by 17 publications

(13 citation statements)

References 88 publications

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“…Previous studies proposed that Ca V 1.3 splice variants may be involved (Green et al, 1996;Kollmar et al, 1997a,b;Ramakrishnan et al, 2002). In particular, Ca V 1.3 of the chicken basilar papilla (Kollmar et al, 1997a,b) has an additional 26 amino acids within the I-II loop region (exon 9a) of Ca V 1.3, and the I-II loop has been proposed as a "hinged lid" to obstruct the channel pore and bring about inactivation.…”

Section: Discussionmentioning

confidence: 95%

“…The auxiliary subunits when coexpressed with the ␣ 1 subunits modulate the kinetics and properties of channel gating (Lacerda et al, 1991;Singer et al, 1991;Varadi et al, 1991). However, in all of these previous screens, either no explicit functional confirmation of altered CDI was performed (Green et al, 1996;Kollmar et al, 1997a,b;Ramakrishnan et al, 2002), or the blunting of CDI was insufficient to explain the profile of native channels (Song et al, 2003). It has been shown that alternative splicing of the Ca V 1.2 gene (Soldatov et al, 1997;Zuhlke and Reuter, 1998;Zuhlke et al, 2000;Tang et al, 2004) contributed to functional diversity of these L-type channels.…”

Section: Discussionmentioning

confidence: 99%

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Alternative Splicing of the Ca_V1.3 Channel IQ Domain, a Molecular Switch for Ca²⁺-Dependent Inactivation within Auditory Hair Cells

Shen¹,

Yu²,

Hiel³

et al. 2006

J. Neurosci.

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Native Ca V 1.3 channels within cochlear hair cells exhibit a surprising lack of Ca 2ϩ -dependent inactivation (CDI), given that heterologously expressed Ca V 1.3 channels show marked CDI. To determine whether alternative splicing at the C terminus of the Ca V 1.3 gene may produce a hair cell splice variant with weak CDI, we transcript-scanned mRNA obtained from rat cochlea. We found that the alternate use of exon 41 acceptor sites generated a splice variant that lost the calmodulin-binding IQ motif of the C terminus. These Ca V 1.3 IQ⌬ ("IQ deleted") channels exhibited a lack of CDI, which was independent of the type of coexpressed ␤-subunits. Ca V 1.3 IQ⌬ channel immunoreactivity was preferentially localized to cochlear outer hair cells (OHCs), whereas that of Ca V 1.3 IQfull channels (IQ-possessing) labeled inner hair cells (IHCs). The preferential expression of Ca V 1.3 IQ⌬ within OHCs suggests that these channels may play a role in processes such as electromotility or activity-dependent gene transcription rather than neurotransmitter release, which is performed predominantly by IHCs in the cochlea.

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Section: Discussionmentioning

confidence: 95%

Section: Discussionmentioning

confidence: 99%

Alternative Splicing of the Ca_V1.3 Channel IQ Domain, a Molecular Switch for Ca²⁺-Dependent Inactivation within Auditory Hair Cells

Shen¹,

Yu²,

Hiel³

et al. 2006

J. Neurosci.

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“…Surprisingly, the last rounds of cav1.3a 5Ј rapid amplification of cDNA ends PCR-yielded products with an apparently premature, in-frame stop codon when compared with other vertebrate cav1.3 orthologs; predicted protein sequence upstream of this stop codon aligned well to higher vertebrate Ca v 1.3 N termini. However, the recent cloning of a cav1.3 ortholog from trout (Ramakrishnan et al, 2002) indicates that this apparent stop codon is conserved among teleosts and likely belongs to the 5Ј UTR. Genscan (http://genes.mit.edu/GENSCAN.html), Promoter 2.0, and Netstart 1.0 (http://www.cbs.dtu.dk/services/) analyses of the zebrafish genome draft assembly (z06) contigs (http://www.ensembl.…”

Section: Methodsmentioning

confidence: 99%

“…Protein sequence alignments and phylogenetic analyses were performed using ClustalW and Phylip algorithms (http://clustalw.genome.ad.jp/). The domain structure of Ca v 1.3a and Ca v 1.3b proteins were deduced from SMART analysis (http:// smart.embl-heidelberg.de) and from sequence comparisons with previously proposed mammalian, avian, and teleost Ca v 1.3 domains (Soldatov, 1992;Kollmar et al, 1997b;Ramakrishnan et al, 2002). Template cDNAs used in all PCRs above were obtained from 5 dpf larval total RNA extracts (Nucleospin RNAII; Macherey-Nagel) using standard or RACE first-strand cDNA synthesis RT reactions according to the instructions of the manufacturer.…”

Section: Methodsmentioning

confidence: 99%

geminiEncodes a Zebrafish L-Type Calcium Channel That Localizes at Sensory Hair Cell Ribbon Synapses

Sidi¹,

Busch-Nentwich²,

Friedrich³

et al. 2004

J. Neurosci.

126

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L-type Ca2ϩ channels (LTCCs) drive the bulk of voltage-gated Ca 2ϩ entry in vertebrate inner ear hair cells (HCs) and are essential for mammalian auditory processing. LTCC currents have been implicated in neurotransmitter release at the HC afferent active zone, the ribbon synapse. It is likely that LTCCs play a direct role in vesicle fusion; however, the subcellular localization of the channels in HCs has not been fully resolved. Via positional cloning, we show that mutations in a zebrafish LTCC encoding gene, cav1.3a, underlie the auditoryvestibular defects of gemini ( gem) circler mutants. gem homozygous receptor mutant HCs display normal cell viability, afferent synaptogenesis, and peripheral innervation, yet exhibit strongly reduced extracellular potentials (ϳ50% of wild-type potentials). Apical FM1-43 uptake, however, is unaffected in gem mutant HCs, suggesting that mechanotransduction channels are functional. Using a Gem-specific antibody, we show that the bulk of Gem/Ca v 1.3a immunoreactivity in HCs is restricted to basally located focal spots. The number and location of focal spots relative to nerve terminals, and their remarkable ring-shaped structure, which is reminiscent of synaptic dense bodies, are consistent with Gem/Ca v 1.3a channels clustering at HC ribbon synapses.

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“…Cyclic AMP, produced via adenylyl cyclase (AC), increases the rate of adaptation of hair cell mechanosensory transduction (Ricci and Fettiplace, 1997). Cyclic AMP also directly targets HCN channels (DiFrancesco and Tortora, 1991) and indirectly (via PKA) L-type and N-type voltage-gated calcium channels (Lü and Dunlap, 1999; Rotman et al, 1992) found in vestibular hair cells (Cho et al, 2003; Ramakrishnan et al 2002; 2006), thus putatively regulating receptoneural transmission (Holt and Eatock, 1995; Sugihara and Furukawa, 1996; Bao et al, 2003; Su et al, 1995). Ten AC isoforms are presently known to underlie AC enzymatic activity.…”

mentioning

confidence: 99%

An adenylyl cyclase signaling pathway predicts direct dopaminergic input to vestibular hair cells

et al. 2010

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Adenylyl cyclase signaling pathways have been identified in a model hair cell preparation from the trout saccule, for which the hair cell is the only intact cell type. The use of degenerate primers targeting cDNA sequence conserved across adenylyl cyclase (AC) isoforms, and RT-PCR, coupled with cloning of amplification products, indicated expression of AC9, AC7 and AC5/6, with cloning efficiencies of 11:5:2. AC9 and AC5/6 are inhibited by Ca2+, the former in conjunction with calcineurin, and message for calcineurin has also been identified in the trout saccular hair cell layer. AC7 is independent of Ca2+. Given the lack of detection of calcium/calmodulin-activated isoforms previously suggested to mediate adenylyl cyclase activation in the absence of Gαs in mammalian cochlear hair cells, the issue of hair-cell Gαs mRNA expression was re-examined in the teleost vestibular hair cell model. Two full-length coding sequences were obtained for Gαs/olf in the vestibular type II-like hair cells of the trout saccule. Two messages for Gαi have also been detected in the hair cell layer, one with homology to Gαi1 and the second with homology to Gαi3 of higher vertebrates. Both Gαs/olf protein and Gαi1/Gαi3 protein were immunolocalized to stereocilia and to the base of the hair cell, the latter consistent with sites of efferent input. While a signaling event coupling to Gαs/olf and Gαi1/Gαi3 in the stereocilia is currently unknown, signaling with Gαs/olf, Gαi3, and AC5/6 at the base of the hair cell would be consistent with transduction pathways activated by dopaminergic efferent input. mRNA for dopamine receptors D1A4 and five forms of dopamine D2 were found to be expressed in the teleost saccular hair cell layer, representing information on vestibular hair cell expression not directly available for higher vertebrates. Dopamine D1A receptor would couple to Gαolf and activation of AC5/6. Co-expression with dopamine D2 receptor, which itself couples to Gαi3 and AC5/6, will down-modulate levels of cAMP, thus fine-tuning and gradating the hair-cell response to dopamine D1A. As predicted by the trout saccular hair cell model, evidence has been obtained for the first time that hair cells of mammalian otolithic vestibular end organs (rat/mouse saccule/utricle) express dopamine D1A and D2L receptors, and each receptor co-localizes with AC5/6, with a marked presence of all three proteins in subcuticular regions of type I vestibular hair cells. A putative efferent, presynaptic source of dopamine was identified in tyrosine hydroxylase-positive nerve fibers which passed from underlying connective tissue to the sensory epithelia, ending on type I and type II vestibular hair cells and on afferent calyces.

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Voltage-gated Ca2+ channel CaV1.3 subunit expressed in the hair cell epithelium of the sacculus of the trout Oncorhynchus mykiss: cloning and comparison across vertebrate classes

Cited by 17 publications

References 88 publications

Alternative Splicing of the Ca_V1.3 Channel IQ Domain, a Molecular Switch for Ca²⁺-Dependent Inactivation within Auditory Hair Cells

Alternative Splicing of the Ca_V1.3 Channel IQ Domain, a Molecular Switch for Ca²⁺-Dependent Inactivation within Auditory Hair Cells

geminiEncodes a Zebrafish L-Type Calcium Channel That Localizes at Sensory Hair Cell Ribbon Synapses

An adenylyl cyclase signaling pathway predicts direct dopaminergic input to vestibular hair cells

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Voltage-gated Ca2+ channel CaV1.3 subunit expressed in the hair cell epithelium of the sacculus of the trout Oncorhynchus mykiss: cloning and comparison across vertebrate classes

Cited by 17 publications

References 88 publications

Alternative Splicing of the CaV1.3 Channel IQ Domain, a Molecular Switch for Ca2+-Dependent Inactivation within Auditory Hair Cells

Alternative Splicing of the CaV1.3 Channel IQ Domain, a Molecular Switch for Ca2+-Dependent Inactivation within Auditory Hair Cells

geminiEncodes a Zebrafish L-Type Calcium Channel That Localizes at Sensory Hair Cell Ribbon Synapses

An adenylyl cyclase signaling pathway predicts direct dopaminergic input to vestibular hair cells

Contact Info

Product

Resources

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Alternative Splicing of the Ca_V1.3 Channel IQ Domain, a Molecular Switch for Ca²⁺-Dependent Inactivation within Auditory Hair Cells

Alternative Splicing of the Ca_V1.3 Channel IQ Domain, a Molecular Switch for Ca²⁺-Dependent Inactivation within Auditory Hair Cells