AJP - Gastrointestinal and Liver Physiology, Vol 262, Issue 6 983-G989, Copyright © 1992 by American Physiological Society
Altered regulation of regional sucrase-isomaltase expression in diabetic rat intestine
L. R. Hoffman and E. B. Chang
Department of Medicine, University of Chicago, Illinois 60637.
Increased sucrase-isomaltase (SI) expression is a prominent feature of
adaptive changes observed in the small intestine of streptozocin-treated
chronically diabetic (CD) rats. In this study, we examine the cellular and
molecular basis of increased SI expression in CD rats by determining SI
specific activities and mRNA abundance in sequentially isolated enterocytes
along the villus-to-crypt axis of proximal jejunum and distal ileum. In all
regions, two- to fourfold increases in sucrase activity in diabetic rat
enterocytes were paralleled by increases in SI mRNA. However, analogous to
nondiabetic rat intestine, no differences in SI mRNA abundance were
observed between corresponding enterocyte fractions from ileum and jejunum
of diabetic rat intestine. By nuclear run-on assays, differences in rates
of SI gene transcription were not observed in diabetic and nondiabetic
intestinal tissues. We conclude that diabetes induces increased total and
specific activities and mRNA abundance of intestinal SI, largely through
the stabilization of SI mRNA. Furthermore, analogous to nondiabetic small
intestine, differences in proximal-to-distal SI expression appear to be
determined at the translational or posttranslational level.
