The pattern of rat intestinal brush-border enzyme gene expression
changes with epithelial growth state.
Hodin, Richard A., Sherman M. Chamberlain, and Shufen Meng.
Department of Surgery, Beth Israel Hospital, Harvard Medical School
and Harvard Digestive Diseases Center, 330 Brookline Ave., Boston,
Mass. 02215
APStracts 2:0086C, 1995.
Enterocyte growth and differentiation occur simultaneously within the
epithelium, but little is known regarding any relationship between
these two processes. Four rat models of small intestinal epithelial
hypo- and hyperplasia (neonatal ontogeny, fasting/refeeding, hypo
-/hyperthyroidism, and bombesin treatment) were used to study the
regulation of enterocyte gene expression in relation to epithelial
growth state. Mucosal scrapings, as well as crypt and villus cell
populations, were subjected to Northern blot analyses using
radiolabeled cDNA probes corresponding to lactase, intestinal
alkaline phosphatase, villin, ornithine decarboxylase, and the actin
control. In all four models, the hypoplastic (atrophic) condition is
characterized by high levels of lactase and low levels of the 3.0 kb
intestinal alkaline phosphatase mRNAs, whereas under hyperplastic
conditions this pattern is reversed. The changes in intestinal
alkaline phosphatase and lactase are qualitatively similar along the
longitudinal axis of the intestine and are proportional to the degree
of hyperplasia, as verified by ornithine decarboxylase mRNA levels.
Furthermore, the crypt-villus axis of differentiation is maintained
regardless of epithelial growth state. In conclusion, the pattern of
brush-border enzyme gene expression changes as a function of
epithelial growth state, indicating a previously unrecognized degree
of plasticity to the state of enterocyte differentiation.
Received 4 October 1994; accepted in final form 24 January 1995.
APS Manuscript Number C596-4.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 28 February 1995.