Biphasic currents evoked by chemical or thermal activation of the heat-gated ion channel, TRPV3

Man Kyo Chung, Ali D. Güler, Michael J. Caterina

Research output: Contribution to journalArticle

Abstract

2-Aminoethyl diphenylborinate was recently identified as a chemical activator of TRPV1, TRPV2, and TRPV3, three heat-gated members of the transient receptor potential vanilloid (TRPV) ion channel subfamily. Here we demonstrated that two structurally related compounds, diphenylboronic anhydride (DPBA) and diphenyltetrahydrofuran (DPTHF), can also modulate the activity of these channels. DPBA acted as a TRPV3 agonist, whereas DPTHF exhibited prominent antagonistic activity. However, all three diphenyl-containing compounds promoted some degree of channel activation or potentiation, followed by channel block. Strong TRPV3 activation by DPBA often leads to the appearance of a secondary, enhanced, current phase. A similar biphasic response was observed during TRPV3 heat stimulation; an initial, gradually sensitizing phase (I1) was followed by an abrupt transition to a secondary phase (I2). I 2 was characterized by larger current amplitude, loss of outward rectification, and alterations in the following properties: permeability among cations; ruthenium red and DPTHF sensitivity; temperature dependence; and voltage-dependent gating. The I1 to I2 transition depended strongly on TRPV3 current density. Removal of extracellular divalent cations resulted in heat-evoked currents resembling I2, whereas mutation of a putative Ca2+-binding residue in the pore loop domain, aspartate 641, facilitated detection of the I1 to I2 transition, suggesting that the conversion to I2 resulted from the agonist- and time-dependent loss of divalent cationic inhibition. Primary keratinocytes overexpressing exogenous TRPV3 also exhibited biphasic agonist-evoked currents. Thus, strong activation by either chemical or thermal stimuli led to biphasic TRPV3 signaling behavior that may be associated with changes in the channel pore.

Original languageEnglish (US)
Pages (from-to)15928-15941
Number of pages14
JournalJournal of Biological Chemistry
Volume280
Issue number16
DOIs
StatePublished - Apr 22 2005

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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