AJP - Gastrointestinal and Liver Physiology, Vol 272, Issue 4 794-G801, Copyright © 1997 by American Physiological Society
Mechanisms of CCK regulation of monitor peptide mRNA expression in pancreatic acinar AR42J cells
T. Kinouchi, S. Tsuzuki, C. Minami, Y. Hayashi, E. Sugimoto and T. Fushiki
Department of Food Science and Technology, Faculty of Agriculture, Kyoto University, Japan.
We explored the mechanism(s) by which cholecystokinin (CCK) stimulation of
AR42J rat pancreatoma cells results in increased mRNA expression of a
CCK-releasing peptide [monitor peptide (MP)]. With the use of a newly
established reverse transcription-polymerase chain reaction assay system,
CCK was shown to increase the level of MP mRNA by about ninefold. When
protein synthesis was blocked by addition of cycloheximide, the MP mRNA
level remained unchanged in the presence of CCK. Inhibition of
transcription with actinomycin D resulted in a half-life for MP mRNA of
approximately 17 h, and this rate remained unchanged after CCK treatment,
suggesting that CCK may regulate the MP mRNA level by influencing gene
transcription. A-23187, bombesin, substance P, and carbachol increased the
MP mRNA level. CoCl(2) abolished actions of both CCK and A-23187 on MP mRNA
expression. Dibutyryl-adenosine 3',5'-cyclic monophosphate, forskolin,
secretin, and vasoactive intestinal polypeptide had no effect on MP mRNA
expression. 12-O-tetradecanoylphorbol-13-acetate and phorbol
12,13-dibutyrate also failed to increase MP mRNA. It was therefore proposed
that CCK stimulates MP mRNA expression of AR42J cells in a Ca2+-dependent
and protein kinase C-independent manner.
