Role of K(+) channel expression in polyamine-dependent intestinal epithelial cell migration

Am J Physiol Cell Physiol. 2000 Feb;278(2):C303-14. doi: 10.1152/ajpcell.2000.278.2.C303.

Abstract

Polyamines are essential for cell migration during early mucosal restitution after wounding in the gastrointestinal tract. Activity of voltage-gated K(+) channels (Kv) controls membrane potential (E(m)) that regulates cytoplasmic free Ca(2+) concentration ([Ca(2+)](cyt)) by governing the driving force for Ca(2+) influx. This study determined whether polyamines are required for the stimulation of cell migration by altering K(+) channel gene expression, E(m), and [Ca(2+)](cyt) in intestinal epithelial cells (IEC-6). The specific inhibitor of polyamine synthesis, alpha-difluoromethylornithine (DFMO, 5 mM), depleted cellular polyamines (putrescine, spermidine, and spermine), selectively inhibited Kv1.1 channel (a delayed-rectifier Kv channel) expression, and resulted in membrane depolarization. Because IEC-6 cells did not express voltage-gated Ca(2+) channels, the depolarized E(m) in DFMO-treated cells decreased [Ca(2+)](cyt) as a result of reduced driving force for Ca(2+) influx through capacitative Ca(2+) entry. Migration was reduced by 80% in the polyamine-deficient cells. Exogenous spermidine not only reversed the effects of DFMO on Kv1.1 channel expression, E(m), and [Ca(2+)](cyt) but also restored cell migration to normal. Removal of extracellular Ca(2+) or blockade of Kv channels (by 4-aminopyridine, 1-5 mM) significantly inhibited normal cell migration and prevented the restoration of cell migration by exogenous spermidine in polyamine-deficient cells. These results suggest that polyamine-dependent intestinal epithelial cell migration may be due partially to an increase of Kv1.1 channel expression. The subsequent membrane hyperpolarization raises [Ca(2+)](cyt) by increasing the driving force (the electrochemical gradient) for Ca(2+) influx and thus stimulates cell migration.

Publication types

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

MeSH terms

  • Animals
  • Antisense Elements (Genetics)
  • Calcium / metabolism
  • Calcium / pharmacokinetics
  • Calcium Channels / metabolism
  • Cell Movement / drug effects*
  • Cells, Cultured
  • Eflornithine / pharmacology
  • Enzyme Inhibitors / pharmacology
  • Epithelial Cells / chemistry
  • Epithelial Cells / cytology*
  • Epithelial Cells / enzymology
  • Gene Expression / drug effects
  • Gene Expression / physiology
  • Image Processing, Computer-Assisted
  • Intestines / cytology
  • Kv1.1 Potassium Channel
  • Ornithine Decarboxylase Inhibitors
  • Polyamines / pharmacology*
  • Potassium Channels / genetics*
  • Potassium Channels / metabolism
  • Potassium Channels, Voltage-Gated*
  • Rats
  • Spermidine / pharmacology

Substances

  • Antisense Elements (Genetics)
  • Calcium Channels
  • Enzyme Inhibitors
  • Ornithine Decarboxylase Inhibitors
  • Polyamines
  • Potassium Channels
  • Potassium Channels, Voltage-Gated
  • Kv1.1 Potassium Channel
  • Calcium
  • Spermidine
  • Eflornithine