Altered channel gating mechanism for CFTR inhibition by a high-affinity thiazolidinone blocker

FEBS Lett. 2004 Jan 30;558(1-3):52-6. doi: 10.1016/S0014-5793(04)00011-0.

Abstract

The thiazolidinone CFTR(inh)-172 was identified recently as a potent and selective blocker of the cystic fibrosis transmembrane conductance regulator (CFTR) Cl(-) channel. Here, we characterized the CFTR(inh)-172 inhibition mechanism by patch-clamp and short-circuit analysis using cells stably expressing wild-type and mutant CFTRs. CFTR(inh)-172 did not alter CFTR unitary conductance (8 pS), but reduced open probability by >90% with K(i) approximately 0.6 microM. This effect was due to increased mean channel closed time without changing mean channel open time. Short-circuit current experiments indicated similar CFTR(inh)-172 inhibitory potency (K(i) approximately 0.5 microM) for inhibition of Cl(-) current in wild-type, G551D, and G1349D CFTR; however, K(i) was significantly reduced to 0.2 microM for DeltaF508 CFTR. Our studies provide evidence for CFTR inhibition by CFTR(inh)-172 by a mechanism involving altered CFTR gating.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Chloride Channels / antagonists & inhibitors*
  • Chloride Channels / drug effects
  • Chloride Channels / metabolism
  • Cystic Fibrosis Transmembrane Conductance Regulator / antagonists & inhibitors*
  • Cystic Fibrosis Transmembrane Conductance Regulator / genetics
  • Cystic Fibrosis Transmembrane Conductance Regulator / metabolism
  • Dose-Response Relationship, Drug
  • Fibroblasts / drug effects
  • Fibroblasts / metabolism
  • Ion Channel Gating / drug effects*
  • Mice
  • Mutation
  • NIH 3T3 Cells
  • Patch-Clamp Techniques
  • Rats
  • Rats, Inbred F344
  • Thiazoles / pharmacology*

Substances

  • Chloride Channels
  • Thiazoles
  • Cystic Fibrosis Transmembrane Conductance Regulator