Clioquinol and pyrithione activate TRPA1 by increasing intracellular Zn2+.
The antifungal and amoebicidal drug clioquinol (CQ) was withdrawn from the market when it was linked to an epidemic of subacute myelo-optico-neuropathy (SMON). Clioquinol exerts its anti-parasitic actions by acting as a Cu/Zn chelator and ionophore. Here we show that local injections of CQ produce mechanical hyperalgesia and cold hypersensitivity through a mechanism involving TRPA1 in mice. We also show that CQ activates TRPA1 in a Zn(2+)-dependent manner. Using a different Zn(2+)-ionophore, zinc pyrithione (ZnPy), we demonstrate that low, nanomolar concentrations of intracellular Zn(2+) ([Zn(2+)](i)) stimulate TRPA1. Direct application of Zn(2+) to the intracellular face of excised, inside-out patches activates TRPA1 with an EC(50) value of 7.5 +/- 1 nM. TRPA1 is expressed in a subpopulation of nociceptive dorsal root ganglion (DRG) neurons, where it acts as a sensory receptor for environmental irritants and oxidants. Using cultured DRG neurons from wild-type and TRPA1-deficient mice, we demonstrate that TRPA1 is the principal excitatory receptor for increased [Zn(2+)](i) in DRG neurons. In conclusion, we have discovered that TRPA1 acts a sensor of intracellular Zn(2+), and that Zn(2+) ionophores, such as CQ and ZnPy, activate TRPA1 by increasing [Zn(2+)](i). We also demonstrate that CQ-evoked mechanical hyperalgesia and cold allodynia require TRPA1 in vivo.
Wolfson Centre for Age-Related Diseases, King's College London, London, United Kingdom. david.andersson@kcl.ac.uk.
David A
DA
Andersson
Clive
C
Gentry
Sian
S
Moss
Stuart
S
Bevan
D000818:Animals; D000935:Antifungal Agents; D000977:Antiparasitic Agents; D002478:Cells, Cultured; D002614:Chelating Agents / Q000494:pharmacology; D007464:Clioquinol / Q000494:pharmacology*; D005727:Ganglia, Spinal; D006930:Hyperalgesia / Q000139:chemically induced; D051379:Mice; D009474:Neurons; D011725:Pyridines / Q000494:pharmacology*; D000074025:TRPA1 Cation Channel; D013697:Thermosensing / Q000187:drug effects; D013871:Thiones / Q000494:pharmacology*; D050051:Transient Receptor Potential Channels / Q000378:metabolism*; D015032:Zinc / Q000032:analysis*
D000935:Antifungal Agents; D000977:Antiparasitic Agents; D002614:Chelating Agents; D011725:Pyridines; D000074025:TRPA1 Cation Channel; D013871:Thiones; D050051:Transient Receptor Potential Channels; C475685:Trpa1 protein, mouse; C008704:pyrithione; D007464:Clioquinol; D015032:Zinc