Krüppel-like factor 5 activates MEK/ERK signaling via EGFR in primary squamous epithelial cells

FASEB J. 2007 Feb;21(2):543-50. doi: 10.1096/fj.06-6694com. Epub 2006 Dec 8.

Abstract

Rapid cell proliferation is a hallmark of transit amplifying cells, but the mechanisms of this localized proliferation are not well understood. The Krüppel-like factor family member Klf5 (IKLF; BTEB2) promotes cell proliferation and is highly expressed in squamous epithelia, in regions of active proliferation. Here, using mouse primary esophageal keratinocytes as a model, we identify a critical role for Klf5 in regulating squamous epithelial proliferation via the epidermal growth factor receptor (EGFR), which, like Klf5, is localized to basal cells in squamous epithelia. We show that Klf5 increases proliferation, transcriptionally up-regulates EGFR, and activates MEK/ERK signaling, as indicated by increased phosphorylation of MEK and ERK. By chromatin immunoprecipitation, we demonstrate that Klf5 binds directly to the 5' regulatory region of EGFR. In addition, we show that regulation of proliferation by Klf5 is dependent on EGFR and MEK/ERK signaling, as the proliferative response to Klf5 is blocked by pharmacologic inhibition of EGFR or MEK. Inhibition of EGFR or MEK also decreases Klf5 expression. Thus, Klf5 regulates MEK/ERK signaling via EGFR and is also downstream of MAPK signaling, providing a novel mechanism for signal amplification or suppression and control of proliferation in basal cells.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Blotting, Western
  • Cell Proliferation
  • Cells, Cultured
  • Chromatin Immunoprecipitation
  • Epithelial Cells / cytology
  • Epithelial Cells / metabolism*
  • ErbB Receptors / metabolism*
  • Extracellular Signal-Regulated MAP Kinases / metabolism*
  • Gene Expression
  • Kruppel-Like Transcription Factors / genetics
  • Kruppel-Like Transcription Factors / metabolism
  • Kruppel-Like Transcription Factors / physiology*
  • MAP Kinase Signaling System / physiology
  • Mice
  • Mitogen-Activated Protein Kinase Kinases / metabolism*
  • Protein Binding
  • Transfection

Substances

  • Kruppel-Like Transcription Factors
  • ErbB Receptors
  • Extracellular Signal-Regulated MAP Kinases
  • Mitogen-Activated Protein Kinase Kinases