title: Superantigen immune stimulation activates epithelial STAT-1 and PI 3-K: PI 3-K regulation of permeability.
abstract: Signal transducers and activators of transcription (STATs) are critical intracellular signaling molecules for many cytokines. We compared the ability of T84 epithelial cells to activate STATs in response to cytokines [interferon-gamma (IFN-gamma), interleukin (IL)-4, IL-10, and tumor necrosis factor-alpha (10 ng/ml)] and conditioned medium from superantigen [Staphylococcus aureus enterotoxin B (SEB)]-activated peripheral blood mononuclear cells (PBMC) using electrophoretic mobility shift assays (EMSA). Of the cytokines tested, only IFN-gamma caused a STAT-1 response. Exposure to SEB-PBMC-conditioned medium resulted in STAT-1 or STAT-1/3 activation, and inclusion of anti-IFN-gamma antibodies in the conditioned medium abolished the STAT-1 signal. Cells treated with transcription factor decoys, DNA oligonucleotides bearing the STAT-1 recognition motif, and then SEB-PBMC-conditioned medium displayed a reduced STAT-1 signal on EMSA, yet this treatment did not prevent the drop in transepithelial resistance (measured in Ussing chambers) caused by SEB-PBMC-conditioned medium. In contrast, the phosphatidylinositol 3'-kinase (PI 3-K) inhibitor LY-294002 significantly reduced the drop in transepithelial resistance caused by SEB-PBMC-conditioned medium. Thus data are presented showing STAT-1 (+/-STAT-3) and PI 3-K activation in epithelial cells in response to immune mediators released by superantigen immune activation. Although the involvement of STAT-1/-3 in the control of barrier function remains a possibility, PI-3K has been identified as a regulator of T84 paracellular permeability.
authors.affiliation: Intestinal Disease Research Programme, McMaster University, Hamilton, Ontario, Canada L8N 3Z5. mckayd@fhs.mcmaster.ca
authors.forename: D M
authors.initials: DM
authors.lastname: McKay
authors.forename: F
authors.initials: F
authors.lastname: Botelho
authors.forename: P J
authors.initials: PJ
authors.lastname: Ceponis
authors.forename: C D
authors.initials: CD
authors.lastname: Richards
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D003106:Colon / Q000166:cytology; D004268:DNA-Binding Proteins / Q000378:metabolism*; D017097:Electric Impedance; D004768:Enterotoxins / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019833:Genistein / Q000494:pharmacology; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000166:cytology / Q000201:enzymology* / Q000276:immunology; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011725:Pyridines / Q000494:pharmacology; D050794:STAT1 Transcription Factor; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D018089:Superantigens / Q000494:pharmacology*; D015534:Trans-Activators / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D002867:Chromones; D004268:DNA-Binding Proteins; D004768:Enterotoxins; D004791:Enzyme Inhibitors; D019833:Genistein; D007093:Imidazoles; D007371:Interferon-gamma; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011725:Pyridines; D050794:STAT1 Transcription Factor; D018089:Superantigens; D015534:Trans-Activators; C494079:STAT1 protein, human; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C031818:enterotoxin B, staphylococcal; C093642:SB 203580