FM1-43 dye behaves as a permeant blocker of the hair-cell mechanotransducer channel

Gale, J E, Marcotti, W, Kennedy, H J, Kros, C J and Richardson, G P (2001) FM1-43 dye behaves as a permeant blocker of the hair-cell mechanotransducer channel. Journal of Neuroscience, 21 (18). pp. 7013-7025. ISSN 0270-6474

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Abstract

Hair cells in mouse cochlear cultures are selectively labeled by brief exposure to FM1-43, a styryl dye used to study endocytosis and exocytosis. Real-time confocal microscopy indicates that dye entry is rapid and via the apical surface. Cooling to 4°C and high extracellular calcium both reduce dye loading. Pretreatment with EGTA, a condition that breaks tip links and prevents mechanotransducer channel gating, abolishes subsequent dye loading in the presence of calcium. Dye loading recovers after calcium chelation with a time course similar to that described for tip-link regeneration.Myo7a mutant hair cells, which can transduce but have all mechanotransducer channels normally closed at rest, do not label with FM1-43 unless the bundles are stimulated by large excitatory stimuli. Extracellular perfusion of FM1-43 reversibly blocks mechanotransduction with half-blocking concentrations in the low micromolar range. The block is reduced by high extracellular calcium and is voltage dependent, decreasing at extreme positive and negative potentials, indicating that FM1-43 behaves as a permeant blocker of the mechanotransducer channel. The time course for the relief of block after voltage steps to extreme potentials further suggests that FM1-43 competes with other cations for binding sites within the pore of the channel. FM1-43 does not block the transducer channel from the intracellular side at concentrations that would cause complete block when applied extracellularly. Calcium chelation and FM1-43 both reduce the ototoxic effects of the aminoglycoside antibiotic neomycin sulfate, suggesting that FM1-43 and aminoglycosides enter hair cells via the same pathway.

Item Type: Article
Additional Information: GPR and CJK directed the research and were joint corresponding authors. The paper is the first to show that the styryl dye FM1-43 enters hair cells through their mechanotransducer channels and provides the basis for a method now widely used for rapidly monitoring for the presence of functional hair cells. Note that JE Gale was a postodc in my lab when this work was done
Schools and Departments: School of Life Sciences > Neuroscience
Depositing User: Corne Kros
Date Deposited: 06 Feb 2012 18:50
Last Modified: 13 Mar 2017 23:44
URI: http://sro.sussex.ac.uk/id/eprint/18577

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