Expression of the Osmotically Responsive Cationic Channel TRPV4 in the Endolymphatic Sac

Kumagami, Hidetaka; Terakado, Mariko; Sainoo, Yuzuru; Baba, Akiko; Fujiyama, Daisuke; Fukuda, Tomomi; Takasaki, Kenji; Takahashi, Haruo

doi:10.1159/000180290

Cited by 19 publications

(18 citation statements)

References 49 publications

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“…Therefore, in the present study, we investigated TRPV4 expression in VG neurons, using a combination of histological and physiological methods. Immunohistochemistry and RT-PCR analysis revealed moderate to low levels of TRPV4 expression in the VG, consistent with previous reports [Ishibashi et al, 2009;Kitahara et al, 2005;Kumagami et al, 2009;Takumida et al, 2005]. Immunoblotting con- firmed specificity of the anti-TRPV4 antibody and positive expression of TRPV4 protein in rat VG neurons.…”

Section: Discussionsupporting

confidence: 90%

“…Hypotonicity-and 4α-PDDinduced [Ca 2+ ] i increases are assumed to be mainly due to the influx of extracellular calcium ions. TRPV4 expression in the vestibular system has been reported in endolymphatic sac and vestibular sensory cells as well as in the VG [Ishibashi et al, 2009;Kumagami et al, 2009;Taguchi et al, 2007;Takumida et al, 2005]. Moreover, cell volume regulation by TRPV4 was observed in rat endolymphatic sac tissue culture [Kumagami et al, 2009].…”

Section: Discussionmentioning

confidence: 92%

“…TRPV4 is known to be expressed histologically in VG neurons [Ishibashi et al, 2009;Kitahara et al, 2005;Kumagami et al, 2009;Takumida et al, 2005]. However, its role in the VG is still under discussion, and it remains unknown whether the channel is activated by its usual stimuli such as 4α-PDD and hypotonicity.…”

Section: Discussionmentioning

confidence: 99%

“…In the vestibular system, histological experiments have shown that TRPV4 is expressed in the vestibular ganglion (VG), endolymphatic sac, sensory cells, and dark cells in the vestibular end organs [Ishibashi et al, 2009;Kitahara et al, 2005;Kumagami et al, 2009;Taguchi et al, 2007;Takumida et al, 2005], and a significant downregulation of TRPV4 mRNA was observed in the mouse VG after kanamycin treatment [Kitahara et al, 2005]. However, it is unknown whether TRPV4 channels in VG neurons can be stimulated by 4α-PDD and hypotonicity, such as those in the mouse outer hair cells.…”

Section: Introductionmentioning

confidence: 99%

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Functional Expression of an Osmosensitive Cation Channel, Transient Receptor Potential Vanilloid 4, in Rat Vestibular Ganglia

Kamakura

Kondo²,

Koyama³

et al. 2016

Audiol Neurotol

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Transient receptor potential vanilloid (TRPV) 4 is a nonselective cation channel expressed in sensory neurons such as those in the dorsal root and trigeminal ganglia, kidney, and inner ear. TRPV4 is activated by mechanical stress, heat, low osmotic pressure, low pH, and phorbol derivatives such as 4α-phorbol 12,13-didecanoate (4α-PDD). We investigated the expression of TRPV4 in rat vestibular ganglion (VG) neurons. The TRPV4 gene was successfully amplified from VG neuron mRNA using reverse-transcription polymerase chain reaction. Furthermore, immunoblotting showed positive expression of TRPV4 protein in VG neurons. Immunohistochemistry indicated that TRPV4 was localized predominantly on the plasma membrane of VG neurons. Calcium (Ca²⁺) imaging of VG neurons showed that 4α-PDD and/or hypotonic stimuli caused an increase in intracellular Ca²⁺ concentration ([Ca²⁺]_i) that was almost completely inhibited by ruthenium red, a selective antagonist of TRPV channels. Interestingly, a [Ca²⁺]_i increase was evoked by both hypotonic stimuli and 4α-PDD in approximately 38% of VG neurons. These data indicate that TRPV4 is functionally expressed in VG neurons as an ion channel and that TRPV4 likely participates in VG neurons for vestibular neurotransmission as an osmoreceptor and/or mechanoreceptor.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Functional Expression of an Osmosensitive Cation Channel, Transient Receptor Potential Vanilloid 4, in Rat Vestibular Ganglia

Kamakura

Kondo²,

Koyama³

et al. 2016

Audiol Neurotol

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“…All TRPVs (TRPV1-6) are expressed in vestibular and cochlear sensory epithelia (Ishibashi et al 2008;Takumida et al 2009). In addition, TRPV4 is also present in the endolymphatic sac and presumably acts as an osmoreceptor in cell and fluid volume regulation (Kumagami et al 2009). Both TRPV5 and TRPV6 are found in vestibular semicircular canal ducts (Yamauchi et al 2010).…”

Section: Transient Receptor Potential Vanilloids (Trpvs) May Also Regmentioning

confidence: 99%

Proteins Involved in Otoconia Formation and Maintenance

Lundberg¹,

Xu²

2012

Otolaryngology

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Mechanisms of otoconia and otolith development

Lundberg

Thiessen

et al. 2014

Developmental Dynamics

128

134

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Otoconia are bio-crystals which couple mechanic forces to the sensory hair cells in the utricle and saccule, a process essential for us to sense linear acceleration and gravity for the purpose of maintaining bodily balance. In fish, structurally similar bio-crystals called otoliths mediate both balance and hearing. Otoconia abnormalities are common and can cause vertigo and imbalance in humans. However, the molecular etiology of these illnesses is unknown, as investigators have only begun to identify genes important for otoconia formation in recent years. To date, in-depth studies of selected mouse otoconial proteins have been performed, and about 75 zebrafish genes have been identified to be important for otolith development. This review will summarize recent findings as well as compare otoconia and otolith development. It will provide an updated brief review of otoconial proteins along with an overview of the cells and cellular processes involved. While continued efforts are needed to thoroughly understand the molecular mechanisms underlying otoconia and otolith development, it is clear that the process involves a series of temporally and spatially specific events that are tightly coordinated by numerous proteins. Such knowledge will serve as the foundation to uncover the molecular causes of human otoconia-related disorders.

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Expression of the Osmotically Responsive Cationic Channel TRPV4 in the Endolymphatic Sac

Cited by 19 publications

References 49 publications

Functional Expression of an Osmosensitive Cation Channel, Transient Receptor Potential Vanilloid 4, in Rat Vestibular Ganglia

Functional Expression of an Osmosensitive Cation Channel, Transient Receptor Potential Vanilloid 4, in Rat Vestibular Ganglia

Proteins Involved in Otoconia Formation and Maintenance

Mechanisms of otoconia and otolith development

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