Restoration of ENaC expression by glucocorticoid receptor transfection in human HT-29/B6 colon cells

Biochem Biophys Res Commun. 2006 Jun 16;344(4):1065-70. doi: 10.1016/j.bbrc.2006.04.012. Epub 2006 Apr 19.

Abstract

The epithelial sodium channel (ENaC) controls colonic sodium absorption. So far, investigation of ENaC was limited by an unexplained lack of steroid-dependent ENaC expression in cultured intestinal cells, which we aimed to resolve. HT-29/B6 cells constitutively expressed the alpha-ENaC subunit, while beta- and gamma-ENaC subunits could not be detected due to deficient basal as well as corticosteroid-induced transcription. This was due to a lack of expression of both activating and inhibiting isoforms of glucocorticoid receptor (GR-alpha, -beta) and mineralocorticoid receptor. Stable transfection of GR-alpha restored intestine-specific glucocorticoid upregulation of beta- and gamma-ENaC in HT-29/B6 cells, which was followed by intact targeting of ENaC channels to the apical cell membrane and dose-dependent induction of electrogenic sodium absorption. In conclusion, ENaC deficiency is due to a lack of steroid receptors and not the consequence of a crypt-like phenotype of cultured intestinal cells. By stable GR transfection we obtained a model, in which ENaC regulation can be studied.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Colon / drug effects
  • Colon / metabolism
  • Colon / physiology*
  • Epithelial Sodium Channels
  • Glucocorticoids / metabolism*
  • Glucocorticoids / pharmacology
  • Humans
  • Potassium / metabolism
  • RNA, Messenger / analysis
  • RNA, Messenger / metabolism
  • Receptors, Glucocorticoid / genetics
  • Receptors, Glucocorticoid / physiology*
  • Sodium Channels / genetics
  • Sodium Channels / metabolism*
  • Transfection

Substances

  • Epithelial Sodium Channels
  • Glucocorticoids
  • RNA, Messenger
  • Receptors, Glucocorticoid
  • Sodium Channels
  • glucocorticoid receptor alpha
  • Potassium