Mm. Ehrman et al., The expression of preprosomatostatin II mRNAs in the Brockmann bodies of rainbow trout, Oncorhynchus mykiss, is regulated by glucose, GEN C ENDOC, 118(1), 2000, pp. 150-160
We previously characterized two cDNAs that encode for distinct preprosomato
statin molecules containing [Tyr(7), Gly(10)]-somatostatin-14 at their C-te
rmini (PPSS II' and PPSS II ") and found that, these cDNAs were differentia
lly expressed in the endocrine pancreas (Brockmann body) of rainbow trout,
Oncorhynchus mykiss. In this study, we examined the control of PPSSII' mRNA
and PPSS II " mRNA expression by glucose. Fish injected with glucose displ
ayed elevated plasma levels of glucose in association with nearly three-fol
d higher levels of PPSS II mRNAs compared to saline-injected control animal
s. Glucose directly stimulated the expression of both PPSS II mRNAs in vitr
o in a dose-dependent manner; however, glucose was a more potent stimulator
of PPSS II " expression than of PPSS II' expression. The hexoses, mannose,
galactose, and fructose, as well as glucose, all induced the expression of
PPSS II mRNAs, whereas, sucrose and the glucose analogs, 3-o-methylglucose
and 2-deoxyglucose, were without effect. In addition, the expression of PP
SS II mRNAs was stimulated by dihydroxyacetone,, pyruvate, lactate, acetate
, and citrate. Furthermore, the expression of PPSS II mRNAs was inhibited b
y iodoacetate, an inhibitor of glycolysis, but was stimulated by dichloroac
etate, a stimulator of Krebs cycle flux via pyruvate dehydrogenase activati
on. Finally, glucose-stimulated PPSS II expression was inhibited by actinom
ycin. These results indicate that the expression of PPSS II mRNAs in the Br
ockmann body of trout is regulated by nutrients such as glucose and suggest
that glucose-stimulated expression of PPSS II mRNAs requires the uptake an
d subsequent metabolism of the sugar and is transcription sensitive. (C) 20
00 Academic Press.