The epidermal growth factor receptor is coupled to a phospholipase A2-specific pertussis toxin-inhibitable guanine nucleotide-binding regulatory protein in cultured rat inner medullary collecting tubule cells.
Studies were performed to examine a potential role for a guanine nucleotide-binding protein in epidermal growth factor (EGF)-stimulated phospholipase A2 (PLA2) activity. EGF increased prostaglandin E2 (PGE2) production in intact or saponin-permeabilized rat inner medullary collecting tubule (RIMCT) cells. Incubation of permeabilized cells with guanosine 5'-O-(thiotriphosphate) (GTP gamma S) enhanced and with guanosine 5'-O-(2-thiodiphosphate) (GDP beta S) inhibited the response to EGF. GDP beta S had no effect on ionomycin-stimulated PGE2 production. Exposure of intact cells to 25 mM NaF + 10 microM AlCl3 enhanced both basal and EGF-stimulated PGE2 production. Pertussis toxin ADP-ribosylated a 41-kDa protein in RIMCT cell membranes. Pretreatment of cells with pertussis toxin (100 ng/ml for 16 h) eliminated the response to EGF in intact cells and the response to EGF + GTP gamma S in permeabilized cells. Pertussis toxin had no effect on the response to ionomycin. The effect of pertussis toxin was not due to alterations in cAMP as cellular cAMP levels were unaffected by pertussis toxin both in the basal state and in the presence of EGF. PGE2 production in response to EGF was not transduced by a G protein coupled to phospholipase C (PLC) as neomycin, which inhibited PLC, did not decrease EGF-stimulated PGE2 production. Also, PGE2 production was not increased by inositol trisphosphate and did not require the presence of extracellular Ca2+. In contrast to EGF-stimulated PLC activity, stimulation of PLA2 by EGF was not susceptible to inhibition by phorbol 12-myristate 13-acetate. These results clearly demonstrate the existence of a PLA2-specific pertussis toxin-inhibitable guanine nucleotide-binding protein coupled to the EGF receptor in RIMCT cells.
Teitelbaum
I
I
Department of Medicine, University of Colorado School of Medicine, Denver 80262.
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000535:Aluminum / Q000494:pharmacology; D017607:Aluminum Compounds; D000818:Animals; D002118:Calcium / Q000502:physiology; D002478:Cells, Cultured; D015232:Dinoprostone / Q000096:biosynthesis; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism*; D005459:Fluorides / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D007679:Kidney Medulla / Q000378:metabolism*; D007684:Kidney Tubules / Q000378:metabolism*; D007685:Kidney Tubules, Collecting / Q000378:metabolism*; D007700:Kinetics; D037342:Pertussis Toxin; D010716:Phosphatidylinositols / Q000378:metabolism; D010740:Phospholipases / Q000378:metabolism*; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
D017607:Aluminum Compounds; D010716:Phosphatidylinositols; D013873:Thionucleotides; D010566:Virulence Factors, Bordetella; D006153:Guanosine Diphosphate; D000246:Adenosine Diphosphate Ribose; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D004815:Epidermal Growth Factor; C023427:guanosine 5'-O-(2-thiodiphosphate); D006160:Guanosine Triphosphate; D000535:Aluminum; D037342:Pertussis Toxin; D066246:ErbB Receptors; D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2; D019204:GTP-Binding Proteins; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate; D005459:Fluorides; D002118:Calcium; C032311:aluminum fluoride