Protein kinase Calpha is implicated in cholecystokinin-induced activation of 70-kd S6 kinase in AR42J cells.
OBJECTIVE
We showed previously that cholecystokinin (CCK)-induced 70-kd S6 kinase activation is partly mediated by protein kinase C (PKC) in pancreatic acinar AR42J cells. Here, we examined which isoform of PKC is involved in this process.


METHODS
AR42J cells were infected with adenovirus vectors carrying the kinase-deficient alpha, delta, and epsilon isoforms of PKC, the dominant-negative form of the 85-kd regulatory subunit of phosphatidylinositol (PI) 3-kinase, and the dominant-negative form of Sos. CCK-induced p70 S6 kinase activation was determined in AR42J cells infected with these adenovirus vectors.


RESULTS
CCK-induced p70 S6 kinase activity was significantly reduced in cells overexpressing the dominant-negative p85 subunit of PI 3-kinase but not in cells overexpressing dominant-negative Sos or beta-galactosidase. CCK-induced p70 S6 kinase activity was inhibited in parallel with the expression levels of kinase-deficient PKCalpha, whereas it was unaffected by the expression of kinase-deficient PKCdelta or PKCepsilon.


CONCLUSIONS
PKCalpha is implicated in CCK-induced activation of p70 S6 kinase in AR42J cells.
Yutsudo
Yoshihiro
Y
Division of Diabetes, Digestive and Kidney Diseases, Department of Clinical Molecular Medicine, Kobe University Graduate School of Medicine, Kobe, Japan.
Kido
Yoshiaki
Y
Okabayashi
Yoshinori
Y
Matsumoto
Michihiro
M
Ogawa
Wataru
W
Ohba
Motoi
M
Kuroki
Toshio
T
Kasuga
Masato
M
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D002766:Cholecystokinin / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D015870:Gene Expression; D016296:Mutagenesis; D046790:Pancreas, Exocrine / Q000166:cytology / Q000201:enzymology*; D010190:Pancreatic Neoplasms; D051571:Protein Kinase C-alpha / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D002766:Cholecystokinin; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D051571:Protein Kinase C-alpha