title: Oxidant-mediated cAMP response element binding protein activation: calcium regulation and role in apoptosis of lung epithelial cells.
abstract: Oxidant stress-mediated regulation of extracellular signal-regulated kinases (ERK1/2) is linked to pathologic outcomes in lung epithelium, yet a role for Ca2+ and Ca2+/cAMP-response element binding protein (CREB) in ERK1/2 signaling has not been defined. In this study, we tested the hypotheses that oxidants induce Ca2+-mediated phosphorylation of ERK and CREB, and that CREB is required for oxidant-induced proliferation and apoptosis. H2O2 initiated an influx of extracellular Ca2+ that was required for phosphorylation of both ERK and CREB in C10 lung epithelial cells. H2O2-mediated CREB phosphorylation was sensitive to MEK inhibition, suggesting that crosstalk between Ca2+, ERK, and CREB signaling pathways contributes to the oxidant-induced response. Reduction of CREB activity, using a dominant-negative CREB construct, inhibited c-fos steady-state mRNA levels, but unexpectedly enhanced bcl-2 steady-state mRNA levels after H2O2 exposure. Whereas inhibition of CREB activity had no detectable effect on H2O2 stimulation of cell cycle, loss of CREB activity significantly reduced the number of cells undergoing apoptosis. These data support a novel communication between Ca2+-ERK1/2 and CREB elicited by H2O2, and further provide evidence that CREB is an important regulator of apoptosis in oxidant-mediated responses of lung epithelial cells.
authors.affiliation: Department of Pharmacology, University of Vermont, Burlington, VT 05405, USA.
authors.forename: Christy A
authors.initials: CA
authors.lastname: Barlow
authors.forename: Arti
authors.initials: A
authors.lastname: Shukla
authors.forename: Brooke T
authors.initials: BT
authors.lastname: Mossman
authors.forename: Karen M
authors.initials: KM
authors.lastname: Lounsbury
mesh_terms: D000818:Animals; D017209:Apoptosis; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000378:metabolism; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism; D016877:Oxidants / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000166:cytology* / Q000378:metabolism; D015398:Signal Transduction
chemical_list: C492004:Creb1 protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; D004791:Enzyme Inhibitors; D016877:Oxidants; D019253:Proto-Oncogene Proteins c-bcl-2; D016760:Proto-Oncogene Proteins c-fos; D006861:Hydrogen Peroxide; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D002118:Calcium