The small conductance K+ channel, KCNQ1: expression, function, and subunit composition in murine trachea

J Biol Chem. 2001 Nov 9;276(45):42268-75. doi: 10.1074/jbc.M105014200. Epub 2001 Aug 29.

Abstract

The gene KCNQ1 encodes a K(+) channel alpha-subunit important for cardiac repolarization, formerly known as K(v)LQT1. In large and small intestine a channel complex consisting of KCNQ1 and the beta-subunit KCNE3 (MiRP2) is known to mediate the cAMP-activated basolateral K(+) current, which is essential for luminal Cl(-) secretion. Northern blot experiments revealed an expression of both subunits in lung tissue. However, previous reports suggested a role of KCNE1 (minK, Isk) but not KCNE3 in airway epithelial cells. Here we give evidence that KCNE1 is not detected in murine tracheal epithelial cells and that Cl(-) secretion by these cells is not reduced by the knock-out of the KCNE1 gene. In contrast we show that a complex consisting of KCNQ1 and KCNE3 probably forms a basolateral K(+) channel in murine tracheal epithelial cells. As described for colonic epithelium, the current through KCNQ1 complexes in murine trachea is specifically inhibited by the chromanol 293B. A 293B-sensitive current was present after stimulation with forskolin and agonists that increase Ca(2+) as well as after administration of the pharmacological K(+) channel activator, 1-EBIO. A 293B-inhibitable current was already present under control conditions and reduced after administration of amiloride indicating a role of this K(+) channel not only for Cl(-) secretion but also for Na(+) reabsorption. We conclude that at least in mice a KCNQ1 channel complex seems to be the dominant basolateral K(+) conductance in tracheal epithelial cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / pharmacology
  • Animals
  • Calcium / metabolism
  • Chlorides / metabolism
  • Cyclic AMP / physiology
  • Indoles / pharmacology
  • KCNQ Potassium Channels
  • KCNQ1 Potassium Channel
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Potassium Channels / chemistry
  • Potassium Channels / genetics
  • Potassium Channels / physiology*
  • Potassium Channels, Voltage-Gated*
  • Protein Subunits
  • Trachea / chemistry*

Substances

  • Chlorides
  • Indoles
  • KCNQ Potassium Channels
  • KCNQ1 Potassium Channel
  • Kcnq1 protein, mouse
  • Potassium Channels
  • Potassium Channels, Voltage-Gated
  • Protein Subunits
  • Adenosine Triphosphate
  • Cyclic AMP
  • Calcium
  • cyclopiazonic acid