title: Krüppel-like factor 5 activates MEK/ERK signaling via EGFR in primary squamous epithelial cells.
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.
authors.affiliation: Department of Medicine, Gastroenterology Division, University of Pennsylvania School of Medicine, 415 Curie Blvd., Philadelphia, Pennsylvania 19104-6140, USA.
authors.forename: Yizeng
authors.initials: Y
authors.lastname: Yang
authors.forename: Bree G
authors.initials: BG
authors.lastname: Goldstein
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakagawa
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Katz
mesh_terms: D000818:Animals; D015153:Blotting, Western; D049109:Cell Proliferation; D002478:Cells, Cultured; D047369:Chromatin Immunoprecipitation; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D066246:ErbB Receptors / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D015870:Gene Expression; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020935:MAP Kinase Signaling System / Q000502:physiology; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism*; D011485:Protein Binding; D014162:Transfection
chemical_list: D051741:Kruppel-Like Transcription Factors; D066246:ErbB Receptors; D048049:Extracellular Signal-Regulated MAP Kinases; D020929:Mitogen-Activated Protein Kinase Kinases