Ocsyn, a Novel Syntaxin-Interacting Protein Enriched in the Subapical Region of Inner Hair Cells

Safieddine, Saaïd; Ly, Calvin; Wang, Y.-X.; Wang, C.Y.; Kachar, Bechara; Petralia, Ronald S.; Wenthold, Robert J.

doi:10.1006/mcne.2002.1120

Cited by 15 publications

(12 citation statements)

References 51 publications

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“…Further, both dopamine D1A and D2L receptors were immunolocalized to subcuticular regions of type I vestibular hair cells, with a distribution similar to that of ocsyn, a novel syntaxin-interacting protein. Ocsyn, originally identified in subapical regions of cochlear inner hair cells and thought to be involved in endosome protein recycling (Safieddine et al, 2002), was later detected in type I and type II vestibular hair cells in rat crista, immunolocalized to subcuticular mitochondrialcanalicular complexes (Vautrin et al, 2006). We hypothesize that dopamine D1A and D2 receptors could be recycled from these subcuticular sites.…”

Section: Discussionmentioning

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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Section: Discussionmentioning

confidence: 99%

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

et al. 2010

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“…Preembedding immunoperoxidase and immunofluorescence methods were described previously in Petralia et al . (1997) and Safieddine et al . (2002).…”

Section: Methodsmentioning

confidence: 96%

Identification of a novel SNAP25 interacting protein (SIP30)

Lee

Safieddine

Petralia

et al. 2002

Journal of Neurochemistry

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Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs), including synaptosome-associated proteins of 25 kDa (SNAP25), syntaxins, and vesicle-associated membrane proteins (VAMP), are essential for regulated exocytosis of synaptic vesicles in neurotransmission. We identified a cDNA coding for a novel protein of 266 amino acids that we have named SIP30 (S NAP25 interacting protein of 30 kDa). SIP30 is expressed abundantly in brain and slightly in testis and kidney. In brain, SIP30 is highly expressed in the inferior and superior colliculi, which contain important relay nuclei of the auditory and visual systems. GST-pull-down and immunoprecipitation assays showed direct binding of SIP30 to SNAP25. Although SIP30 does not directly interact with syntaxin based on pull-down assays, syntaxin does co-immunoprecipitate with SIP30 suggesting that syntaxin is indirectly associated with SIP30, perhaps through SNAP25.

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“…In the immunoblot homogenates of rat vestibular organs and guinea pig cochlea, ocsyn was detected as a single band migrating at approximately 75 kDa. Safieddine et al (2002) detected ocsyn in guinea pig brain and cochlea and in rat brain at a slightly lower molecular weight of 65 kDa. Ocsyn was revealed as a light band in rat vestibule and was not detected in guinea pig vestibule, indicating a very small amount of this protein in the vestibular end-organs.…”

Section: Discussionmentioning

confidence: 97%

“…Indeed, Safieddine et al (2002) showed the presence of ocsyn on immunoblots of rat and guinea pig brains and in rat heart, kidney, liver and testis. Furthermore, live recording in outer hair cell revealed a complex membrane trafficking in distinct intracellular compartments that are part of the tubulo-vesicular system (Kachar et al, 1997;Griesinger et al, 2004).…”

Section: Discussionmentioning

confidence: 98%

“…At the basal pole, the presynaptic region where neurotransmission operates at very high rates of release, synaptic ribbons formed by elongated or spherical components covered with synaptic vesicles, are present. In cochlear inner hair cells, several Nethylmaleimide-sensitive factor receptor (SNARE) proteins including syntaxin1A, SNAP25 and VAMP1 have been found (Safieddine and Wenthold, 1999;Eybalin et al, 2002;Safieddine et al, 2002), and also proteins associated with synaptic vesicle function such as cystein string proteins (Eybalin et al, 2002). All these proteins were detected at both the apical and basal poles of the inner hair cells.…”

Section: Introductionmentioning

confidence: 97%

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