The effect of concomitant stimulation with cholecystokinin and epidermal growth factor on extracellular signal-regulated kinase (ERK) activity in pancreatic acinar cells.
The transmission of extracellular proliferation and differentiation signals into their intracellular targets is mediated by a signaling cascade culminating in mitogen-activated protein kinase (MAPK) also known as ERK. In pancreatic acinar cells both cholecystokinin (CCK) and epidermal growth factor (EGF) are known to stimulate ERK. Regulatory interactions among individual receptor-coupled signaling cascades are critically important for establishing cellular responses in the face of multiple stimuli. The aim of our study was to evaluate the effect of concomitant stimulation of G protein-coupled receptors (GPCR) and EGF receptors on ERK activity in isolated pancreatic acinar cells. ERK activity was determined by means of Western-blotting, with the use of the antibody which recognizes active, tyrosine-phosphorylated kinase (pY-ERK). pY-ERK level was strongly elevated by 10 nM CCK-8, 100 microM carbachol (CAR), or 100 nM EGF. The addition of EGF to 60 min-lasting incubations of acini with CCK-8 or CAR caused abrupt decrease of pY-ERK level to 56 and 59% of control, respectively. Similar phenomenon was observed when short stimulation with CCK-8 or CAR was superimposed on the effect of EGF. After the addition of EGF to acini incubated previously with phorbol ester TPA, strong decrease in pY-ERK level was also observed. In conclusion, in pancreatic acinar cells, concomitant stimulation with CCK or CAR and EGF has strong inhibitory effect on ERK cascade. This inhibitory cross-talk may be mediated, at least partially, by protein kinase C (PKC). These mutual inhibitory interactions demonstrate novel mechanism for integration of multiple signals generated by activation of G-protein-coupled and growth factor receptors in pancreatic acinar cells.
Daniluk
J
J
Department of Gastroenterology and Internal Medicine, Medical University of Bialystok, Poland. danilukj@poczta.onet.pl
Dabrowski
A
A
D000818:Animals; D015153:Blotting, Western; D002217:Carbachol / Q000494:pharmacology; D002766:Cholecystokinin / Q000494:pharmacology*; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D066246:ErbB Receptors / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D008297:Male; D018721:Muscarinic Agonists / Q000494:pharmacology; D046790:Pancreas, Exocrine / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D012844:Sincalide / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors
D018721:Muscarinic Agonists; D043562:Receptors, G-Protein-Coupled; D004815:Epidermal Growth Factor; D002217:Carbachol; D002766:Cholecystokinin; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D012844:Sincalide; D013755:Tetradecanoylphorbol Acetate