title: Extracellular signal-regulated kinase activation by parathyroid hormone in distal tubule cells.
abstract: The PTH receptor (PTH1R) activates multiple signaling pathways, including extracellular signal-regulated kinases 1 and 2 (ERK1/2). The role of epidermal growth factor receptor (EGFR) transactivation in ERK1/2 activation by PTH in distal kidney cells, a primary site of PTH action, was characterized. ERK1/2 phosphorylation was stimulated by PTH and blocked by the EGFR inhibitor, AG1478. Upon PTH stimulation, metalloprotease cleavage of membrane-bound heparin-binding fragment (HB-EGF) induced EGFR transactivation of ERK. Conditioned media from PTH-treated distal kidney cells activated ERK in HEK-293 cells. AG1478 added to HEK-293 cells ablated transactivation by conditioned media. HB-EGF directly activated ERK1/2 in HEK-293 cells. Pretreatment of distal kidney cells with the metalloprotease inhibitor GM-6001 abolished transactivation of ERK1/2 by PTH. The role of the PTH1R COOH terminus in PTX-sensitive ERK1/2 activation was characterized in HEK-293 cells transfected with wild-type PTH1R, with a PTH1R mutated at its COOH terminus, or with PTH1R truncated at position 480. PTH stimulated ERK by wild-type, mutated and truncated PTH1Rs 21-, 27- and 57-fold, respectively. Thus, the PTH1R COOH terminus exerts an inhibitory effect on ERK activation. EBP50, a scaffolding protein that binds to the PDZ recognition domain of the PTH1R, impaired PTH but not isoproterenol or calcitonin-induced ERK activation. Pertussis toxin inhibited PTH-stimulated ERK1/2 by mutated and truncated PTH1Rs and abolished ERK1/2 activation by wild-type PTH1R. We conclude that ERK phosphorylation in distal kidney cells by PTH requires PTH1R activation of G(i), which leads to stimulation of metalloprotease-mediated cleavage of HB-EGF and transactivation of the EGFR and is regulated by EBP50.
authors.affiliation: Department of Pharmacology, University of Pittsburgh School of Medicine, W-1340 Biomedical Science Tower, Pittsburgh, PA 15261, USA.
authors.forename: W Bruce
authors.initials: WB
authors.lastname: Sneddon
authors.forename: Yanmei
authors.initials: Y
authors.lastname: Yang
authors.forename: Jianming
authors.initials: J
authors.lastname: Ba
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Harinstein
authors.forename: Peter A
authors.initials: PA
authors.lastname: Friedman
mesh_terms: D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D017077:Culture Media, Conditioned / Q000494:pharmacology; D004151:Dipeptides / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066246:ErbB Receptors / Q000037:antagonists & inhibitors; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000037:antagonists & inhibitors; D066257:Heparin-binding EGF-like Growth Factor; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D007686:Kidney Tubules, Distal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009154:Mutation; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology; D037342:Pertussis Toxin / Q000494:pharmacology; D010750:Phosphoproteins / Q000235:genetics; D010766:Phosphorylation / Q000187:drug effects; D011799:Quinazolines; D044168:Receptor, Parathyroid Hormone, Type 1 / Q000235:genetics; D011956:Receptors, Cell Surface / Q000378:metabolism; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics; D014162:Transfection; D020032:Tyrphostins / Q000494:pharmacology
chemical_list: D017077:Culture Media, Conditioned; D004151:Dipeptides; D004791:Enzyme Inhibitors; C587883:HBEGF protein, human; C587884:Hbegf protein, mouse; D066257:Heparin-binding EGF-like Growth Factor; D036341:Intercellular Signaling Peptides and Proteins; C078131:N-(2(R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl)-L-tryptophan methylamide; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D010750:Phosphoproteins; D011799:Quinazolines; D044168:Receptor, Parathyroid Hormone, Type 1; D011956:Receptors, Cell Surface; D017923:Sodium-Hydrogen Exchangers; D020032:Tyrphostins; C101312:parathyroid hormone (1-31); C093376:sodium-hydrogen exchanger regulatory factor; C101044:RTKI cpd; D037342:Pertussis Toxin; D066246:ErbB Receptors; D048049:Extracellular Signal-Regulated MAP Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D019206:GTP-Binding Protein alpha Subunits, Gi-Go