Molecular Identity and Functional Properties of a Novel T-Type Ca²⁺ Channel Cloned From the Sensory Epithelia of the Mouse Inner Ear

Abstract

son GP, Yamoah EN. Molecular identity and functional properties of a novel T-type Ca 2ϩ channel cloned from the sensory epithelia of the mouse inner ear.

Postnatal Expression of an Apamin-Sensitive K(Ca) Current in Vestibular Calyx Terminals

“…However rat cultured vestibular ganglion neurons (ages P7–P10) expressed both low- (T-type) and high-voltage activated inward calcium currents (Limón et al 2005). We found no evidence for a T-type Ca 2+ current in postnatal calyx terminals, which is consistent with a lack of Cav3.1 immunoreactivity in afferent terminals in early postnatal mouse saccule and crista (Nie et al 2008). The transient inward current in calyx terminals aged P8–P24 was blocked > 95 % by 500 nM tetrodotoxin (Fig.…”

Otoferlin Is Critical for a Highly Sensitive and Linear Calcium-Dependent Exocytosis at Vestibular Hair Cell Ribbon Synapses

“…Such a configuration has already been reported in neuronal synapses and adrenal chromaffin cells in which different Ca 2+ sensors may coexist (Xu et al, 2007; Schonn et al, 2008). Since mature hair cells, unlike neurons, do not fire spontaneous action potential, spontaneous transmitter release could involve low voltage-activated Ca 2+ channels such as Ca v 3.1 T-type channels (Nie et al, 2008) that can be readily activated near resting membrane potential. The mechanisms of otoferlin-independent vesicular release that drives spontaneous activity in vestibular hair cells remain be elucidated.…”

The Physiology, Pathology, and Pharmacology of Voltage-Gated Calcium Channels and Their Future Therapeutic Potential

“…Alternative splicing events in the domain I-II linker of Ca V 3.1, leading to exclusion of exon 8, result in enhanced cell surface expression and thus elevated current densities (Shcheglovitov et al, 2008), indicating that this region may be involved in either endoplasmic reticulum retention or cell surface trafficking. A Ca V 3.1 splice isoform isolated from the mouse inner ear, including exons 14, 25A, 34, and 35, displays unique permeation characteristics (Nie et al, 2008). Multiple splice isoforms of Ca V 3.1 in the domain III-IV linker region that arise from different combinations of exons 25A, 25B, and 26 have been identified and shown to exhibit altered activation and inactivation kinetics, as has splicing of exon 14 in the II-III linker region (Chemin et al, 2001a).…”