title: Epidermal growth factor-induced proliferation of collecting duct cells from Oak Ridge polycystic kidney mice involves activation of Na+/H+ exchanger.
abstract: Epidermal growth factor (EGF) is linked to the pathogenesis of polycystic kidney disease (PKD). We explored signaling pathways activated by EGF in orpk cilia (-) collecting duct cell line derived from a mouse model of PKD (hypomorph of the Tg737/Ift88 gene) with severely stunted cilia, and in a control orpk cilia (+) cell line with normal cilia. RT-PCR demonstrated mRNAs for EGF receptor subunits ErbB1, ErbB2, ErbB3, ErbB4, and mRNAs for Na(+)/H(+) exchangers (NHE), NHE-1, NHE-2, NHE-3, NHE-4, and NHE-5 in both cell lines. EGF stimulated proton efflux in both cell lines. This effect was significantly attenuated by MIA, 5-(n-methyl-N-isobutyl) amiloride, a selective inhibitor of NHE-1 and NHE-2, and orpk cilia (-) cells were more sensitive to MIA than control cells (P < 0.01). EGF significantly induced extracellular signal-regulated kinase (ERK) phosphorylation in both cilia (+) and cilia (-) cells (63.3 and 123.6%, respectively), but the effect was more pronounced in orpk cilia (-) cells (P < 0.01). MIA significantly attenuated EGF-induced ERK phosphorylation only in orpk cilia (-) cells (P < 0.01). EGF increased proliferation of orpk cilia (+) cells and orpk cilia (-) cells, respectively, and MIA at 1-5 μM attenuated EGF-induced proliferation in orpk cilia (-) cells without affecting proliferation of orpk cilia (+) cells. EGF-induced proliferation of both cell lines was significantly decreased by the EGFR tyrosine kinase inhibitor AG1478 and MEK inhibitor PD98059. These results suggest that EGF exerts mitogenic effects in the orpk cilia (-) cells via activation of growth-associated amiloride-sensitive NHEs and ERK.
authors: Department of Medicine, Division of Nephrology, Medical University of South Carolina, Charleston, South Carolina;
authors: Sonya D
authors: SD
authors: Coaxum
authors: Department of Medicine, Division of Nephrology, Medical University of South Carolina, Charleston, South Carolina;
authors: Mary G
authors: MG
authors: Blanton
authors: College of Medicine, Medical University of South Carolina, Charleston, South Carolina;
authors: Alisha
authors: A
authors: Joyner
authors: Department of Medicine, Division of Rheumatology and Immunology, Medical University of South Carolina, Charleston, South Carolina;
authors: Tanjina
authors: T
authors: Akter
authors: Department of Medicine, Division of Nephrology, Medical University of South Carolina, Charleston, South Carolina; Medical and Research Services of the Ralph H. Johnson VAMC, Charleston, Carolina;
authors: P Darwin
authors: PD
authors: Bell
authors: Department of Medicine, Division of Endocrinology, Medical University of South Carolina, Charleston, South Carolina; and.
authors: Louis M
authors: LM
authors: Luttrell
authors: Department of Medicine, Division of Nephrology, Medical College of Wisconsin and the Medical Service of the Clement J. Zablocki VA Medical Center, Milwaukee, Wisconsin.
authors: John R
authors: JR
authors: Raymond
authors: Department of Medicine, Division of Endocrinology, Medical University of South Carolina, Charleston, South Carolina; and.
authors: Mi-Hye
authors: MH
authors: Lee
authors: Department of Medicine, Division of Nephrology, Medical University of South Carolina, Charleston, South Carolina;
authors: Paul A
authors: PA
authors: Blichmann
authors: Department of Medicine, Division of Nephrology, Medical University of South Carolina, Charleston, South Carolina;
authors: Maria N
authors: MN
authors: Garnovskaya
authors: Department of Medicine, Division of Nephrology, Medical University of South Carolina, Charleston, South Carolina; saigusa@musc.edu.
authors: Takamitsu
authors: T
authors: Saigusa
mesh_terms: D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002923:Cilia / Q000201:enzymology / Q000473:pathology; D004195:Disease Models, Animal; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000378:metabolism*; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D007527:Isoenzymes; D007685:Kidney Tubules, Collecting / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D010766:Phosphorylation; D007690:Polycystic Kidney Diseases / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D017923:Sodium-Hydrogen Exchangers; C490898:Tg737Rpw protein, mouse; D025521:Tumor Suppressor Proteins; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D048049:Extracellular Signal-Regulated MAP Kinases
keywords: AG1478; cytosensor microphysiometer; phosphorylation; polycystic kidney disease