S. Carreira et al., DIETARY MODULATION OF THE MESSENGER-RNA STABILITY OF TRYPSIN ISOZYMESAND THE 2 FORMS OF SECRETORY TRYPSIN-INHIBITOR IN THE RAT PANCREAS, European journal of biochemistry, 239(1), 1996, pp. 117-123
The stability of the mRNAs encoding pancreatic trypsin isozymes, namel
y the cationic form and the two anionic forms I and II, as well as tha
t of the secretory trypsin inhibitors I and II, were studied in rats f
ed on either a high-protein diet, or a protein-free diet compared with
a standard diet for a 10-day period. Either immediately or 3 h and 6
h after injecting the transcription inhibitor, actinomycin D, the mRNA
levels were quantified by performing dot-blot hybridization with spec
ific oligonucleotide probes. Under high-protein dietary conditions, th
e stability of the mRNAs coding for anionic trypsin II and cationic tr
ypsin showed no change, whereas that of anionic trypsin I and the two
forms of secretory trypsin inhibitor were affected. The mRNA half-life
of anionic trypsin I and trypsin inhibitor II increased, in sharp con
trast with that of trypsin inhibitor I, which decreased. When rats wer
e fed on a protein-free diet, the stabilities of both anionic trypsin
forms and trypsin inhibitor I increased, whereas that of trypsin inhib
itor II decreased and that of cationic trypsin remained unchanged. The
present results show the existence of differences in the mechanisms w
hereby gene expression of trypsin isozymes and secretory trypsin inhib
itors is regulated, although they are synthesized in parallel in the p
ancreatic acinar cell and stored in zymogen granules before being secr
eted into the intestinal lumen.