title: Aldosterone interaction with epidermal growth factor receptor signaling in MDCK cells.
abstract: Epidermal growth factor (EGF) regulates cell proliferation, differentiation, and ion transport by using extracellular signal-regulated kinase (ERK)1/2 as a downstream signal. Furthermore, the EGF-receptor (EGF-R) is involved in signaling by G protein-coupled receptors, growth hormone, and cytokines by means of transactivation. It has been suggested that steroids interact with peptide hormones, in part, by rapid, potentially nongenomic, mechanisms. Previously, we have shown that aldosterone modulates Na(+)/H(+) exchange in Madin-Darby canine kidney (MDCK) cells by means of ERK1/2 in a way similar to growth factors. Here, we tested the hypothesis that aldosterone uses the EGF-R as a heterologous signal transducer in MDCK cells. Nanomolar concentrations of aldosterone induce a rapid increase in ERK1/2 phosphorylation, cellular Ca(2+) concentration, and Na(+)/H(+) exchange activity similar to increases induced by EGF. Furthermore, aldosterone induced a rapid increase in EGF-R-Tyr phosphorylation, and inhibition of EGF-R kinase abolished aldosterone-induced signaling. Inhibition of ERK1/2 phosphorylation reduced the Ca(2+) response, whereas prevention of Ca(2+) influx did not abolish ERK1/2 phosphorylation. Our data show that aldosterone uses the EGF-R-ERK1/2 signaling cascade to elicit its rapid effects in MDCK cells.
authors.affiliation: Physiologisches Institut, University of Würzburg, 97070 Würzburg, Germany. michael.gekle@mail.uni-wuerzburg.de
authors.forename: Michael
authors.initials: M
authors.lastname: Gekle
authors.forename: Ruth
authors.initials: R
authors.lastname: Freudinger
authors.forename: Sigrid
authors.initials: S
authors.lastname: Mildenberger
authors.forename: Stefan
authors.initials: S
authors.lastname: Silbernagl
mesh_terms: D000450:Aldosterone / Q000494:pharmacology*; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004285:Dogs; D004797:Enzyme-Linked Immunosorbent Assay; D066246:ErbB Receptors / Q000187:drug effects*; D019204:GTP-Binding Proteins / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D011233:Precipitin Tests; D015398:Signal Transduction / Q000187:drug effects*
chemical_list: D016718:Arachidonic Acid; D000450:Aldosterone; D015544:Inositol 1,4,5-Trisphosphate; D066246:ErbB Receptors; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D019204:GTP-Binding Proteins; D002118:Calcium