title: K+ Channel Inhibition Differentially Regulates Migration of Intestinal Epithelial Cells in Inflamed vs. Non-Inflamed Conditions in a PI3K/Akt-Mediated Manner.
abstract: BACKGROUND
  Potassium channels have been shown to determine wound healing in different tissues, but their role in intestinal epithelial restitution--the rapid closure of superficial wounds by intestinal epithelial cells (IEC)--remains unclear.
  
  
  METHODS
  In this study, the regulation of IEC migration by potassium channel modulation was explored with and without additional epidermal growth factor (EGF) under baseline and interferon-γ (IFN-γ)-pretreated conditions in scratch assays and Boyden chamber assays using the intestinal epithelial cell lines IEC-18 and HT-29. To identify possibly involved subcellular pathways, Western Blot (WB)-analysis of ERK and Akt phosphorylation was conducted and PI3K and ERK inhibitors were used in scratch assays. Furthermore, mRNA-levels of the potassium channel KCNN4 were determined in IEC from patients suffering from inflammatory bowel diseases (IBD).
  
  
  RESULTS
  Inhibition of Ca(2+)-dependent potassium channels significantly increased intestinal epithelial restitution, which could not be further promoted by additional EGF. In contrast, inhibition of KCNN4 after pretreatment with IFN-γ led to decreased or unaffected migration. This effect was abolished by EGF. Changes in Akt, but not in ERK phosphorylation strongly correlated with these findings and PI3K but not ERK inhibition abrogated the effect of KCNN4 inhibition. Levels of KCNN4 mRNA were higher in samples from IBD patients compared with controls.
  
  
  CONCLUSIONS
  Taken together, we demonstrate that inhibition of KCNN4 differentially regulates IEC migration in IFN-γ-pretreated vs. non pretreated conditions. Moreover, our data propose that the PI3K signaling cascade is responsible for this differential regulation. Therefore, we present a cellular model that contributes new aspects to epithelial barrier dysfunction in chronic intestinal inflammation, resulting in propagation of inflammation and symptoms like ulcers or diarrhea.
authors.affiliation: Department of Internal Medicine I, Regensburg University Medical Center, Regensburg, Germany.|Department of Medicine 1, University of Erlangen-Nuremberg, Kussmaul Campus for Medical Research & Translational Research Center, Erlangen, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Zundler
authors.affiliation: Department of Internal Medicine I, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Caioni
authors.affiliation: Department of Internal Medicine I, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Martina
authors.initials: M
authors.lastname: Müller
authors.affiliation: Department of Internal Medicine I, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Strauch
authors.affiliation: Department of Internal Medicine I, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Kunst
authors.affiliation: Department of Internal Medicine I, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Gisela
authors.initials: G
authors.lastname: Woelfel
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001681:Biological Assay; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects; D015194:Diffusion Chambers, Culture; D004815:Epidermal Growth Factor / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation; D019073:HT29 Cells; D006801:Humans; D007082:Ileum / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015212:Inflammatory Bowel Diseases / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D007371:Interferon-gamma / Q000494:pharmacology; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D061251:Primary Cell Culture; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction; D014945:Wound Healing / Q000187:drug effects
chemical_list: D004815:Epidermal Growth Factor; D007371:Interferon-gamma; D051660:Intermediate-Conductance Calcium-Activated Potassium Channels; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; C496923:KCNN4 protein, human; C491575:Kcnn4 protein, rat
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