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Charge and lipophilicity are required for effective block of the hair-cell mechano-electrical transducer channel by FM1-43 and its derivatives

Derudas, Marco, O’Reilly, Molly, Kirkwood, Nerissa K., Kenyon, Emma J., Grimsey, Sybil, Kitcher, Siân R., Workman, Shawna, Bull, James C., Ward, Simon E., Kros, Corné J., and others. (2023) Charge and lipophilicity are required for effective block of the hair-cell mechano-electrical transducer channel by FM1-43 and its derivatives. Frontiers in Cell and Developmental Biology, 11 . Article Number 1247324. E-ISSN 2296-634X. (doi:10.3389/fcell.2023.1247324) (KAR id:103430)


The styryl dye FM1-43 is widely used to study endocytosis but behaves as a permeant blocker of the mechano-electrical transducer (MET) channel in sensory hair cells, loading rapidly and specifically into the cytoplasm of hair cells in a MET channel-dependent manner. Patch clamp recordings of mouse outer hair cells (OHCs) were used to determine how a series of structural modifications of FM1-43 affect MET channel block. Fluorescence microscopy was used to assess how the modifications influence hair-cell loading in mouse cochlear cultures and zebrafish neuromasts. Cochlear cultures were also used to evaluate otoprotective potential of the modified FM1-43 derivatives. Structure-activity relationships reveal that the lipophilic tail and the cationic head group of FM1-43 are both required for MET channel block in mouse cochlear OHCs; neither moiety alone is sufficient. The extent of MET channel block is augmented by increasing the lipophilicity/bulkiness of the tail, by reducing the number of positive charges in the head group from two to one, or by increasing the distance between the two charged head groups. Loading assays with zebrafish neuromasts and mouse cochlear cultures are broadly in accordance with these observations but reveal a loss of hair-cell specific labelling with increasing lipophilicity. Although FM1-43 and many of its derivatives are generally cytotoxic when tested on cochlear cultures in the presence of an equimolar concentration of the ototoxic antibiotic gentamicin (5 µM), at a 10-fold lower concentration (0.5 µM), two of the derivatives protect OHCs from cell death caused by 48 h-exposure to 5 µM gentamicin.

Item Type: Article
DOI/Identification number: 10.3389/fcell.2023.1247324
Uncontrolled keywords: FM1-43; mechano-electrical transducer channel; hair cell; zebrafish; hearing; ototoxicity
Subjects: Q Science
Divisions: Divisions > Division of Natural Sciences > Biosciences
Funders: Medical Research Council (
University of Sussex (
Swansea University (
Royal Society (
SWORD Depositor: JISC Publications Router
Depositing User: JISC Publications Router
Date Deposited: 21 Mar 2024 15:12 UTC
Last Modified: 22 Mar 2024 11:29 UTC
Resource URI: (The current URI for this page, for reference purposes)

University of Kent Author Information

Kirkwood, Nerissa K..

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