The human CCKB/gastrin receptor transfected into rat1 fibroblasts mediates activation of MAP kinase, p74raf-1 kinase, and mitogenesis.
The human cholecystokinin (CCK)B/gastrin receptor was stably transfected into Rat1 fibroblasts to examine the signaling pathways mediated by this seven-transmembrane, G protein-linked receptor. We report here that binding of CCK-8 or gastrin to the CCKB/gastrin receptor induced phosphoinositide breakdown and led to a rapid, transient, and concentration-dependent increase in intracellular Ca2+, which was completely blocked by a specific CCKB receptor antagonist. The peptides also stimulated tyrosine phosphorylation of focal adhesion kinase (p125FAK) and paxillin. Both CCK-8 and gastrin induced a dose- and time-dependent activation of MAP kinase and p74raf-1 kinase in the transfected Rat1 cells. These effects could be dissociated from protein kinase C activation and were not dependent on a functional Gi protein. Finally, both CCK-8 and gastrin induced DNA synthesis in Rat1 cells transfected with the human CCKB/gastrin receptor through a pertussis toxin-insensitive pathway. These results indicate that the neuropeptides gastrin and CCK can activate multiple signal transduction pathways and act as sole mitogens by binding to the CCKB/gastrin receptor transfected into Rat1 fibroblasts.
Seufferlein
T
T
Imperial Cancer Research Fund, London, United Kingdom.
Withers
D J
DJ
Broad
S
S
Herget
T
T
Walsh
J H
JH
Rozengurt
E
E
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000096:biosynthesis*; D005347:Fibroblasts / Q000502:physiology; D018014:Gene Transfer Techniques; D006801:Humans; D008938:Mitosis / Q000502:physiology; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis*; D019908:Proto-Oncogene Proteins c-raf; D051381:Rats; D011949:Receptors, Cholecystokinin / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D012844:Sincalide / Q000378:metabolism
D011949:Receptors, Cholecystokinin; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D012844:Sincalide