Expression of apolipoprotein and fatty acid binding protein genes
in the adapting small intestine: evidence for a specific enterocytic
response.
Rubin, Deborah C., Elzbieta A. Swietlicki, Joseph Wang, Brian Dodson,
and Marc S. Levin.
Division of Gastroenterology, Washington University School of
Medicine, Box 8124, 660 South Euclid Avenue, St. Louis, Mo. 63110,
314-362-8940, 314-362-8959 (FAX)
APStracts 2:0140G, 1995.
After massive small bowel resection, the remnant gut epithelium
undergoes an adaptive response marked by an increase in villus
height, crypt depth, and crypt cell production rate. Although
morphologic features of gut adaptation have been well-characterized,
the differentiation status and response of epithelial cells
populating the adaptive villus is unclear. To address these issues,
cell-specific and spatial patterns of expression of a set of
enterocytic genes were characterized in rats following 70% small
bowel resection. The liver (L) and intestinal (I) fatty acid binding
protein (FABP) and apolipoprotein (apo) AI and AIV genes were studied
because they exhibit unique regional and cell-specific patterns of
expression in the developing and adult gut. At 48 h after surgery,
apo AIV and I-FABP mRNA levels were increased up to 3.5 fold in
adaptive remnant ileum compared to sham-operated or sham-resected
control ileum. In situ hybridization and immunohistochemical analyses
revealed a marked increase in enterocytic apo AIV mRNA and protein
expression in the adaptive ileum, from villus base to tip but not in
crypts. By 1 week after resection, apo AIV but not I-FABP mRNA levels
remained elevated in remnant ileum, although duodenal I-FABP mRNA
levels were still increased. In contrast, apo AI mRNA levels were not
significantly induced. These results indicate that in addition to
crypt cells, the enterocyte can respond acutely to loss of small
bowel surface area by increasing expression of several genes. This
compensatory enterocytic response is spatially (from duodenum to
ileum) and temporally regulated. These results suggest initiation of
the adaptive response occurs by way of a complex set of molecular
pathways involving villus and crypt cells.
Received 24 January 1995; accepted in final form 5 July 1995.
APS Manuscript Number G30-5.
Article publication pending Am. J. Physiol. (Gastrointest. Liver
Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 18 July 1995.