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Mol. Cell. Biol., 02 1996, 619-625, Vol 16, No. 2
E Suh and PG Traber
Precise regulation of cellular proliferation, differentiation, and
senescence results in the continuous renewal of the intestinal epithelium
with maintenance of a highly ordered tissue architecture. Here we show that
an intestine-specific homeobox gene, Cdx2, is a transcription factor that
regulates both proliferation and differentiation in intestinal epithelial
cells. Conditional expression of Cdx2 in IEC-6 cells, an undifferentiated
intestinal cell line, led to arrest of proliferation for several days
followed by a period of growth resulting in multicellular structures
containing a well-formed columnar layer of cells. The columnar cells had
multiple morphological characteristics of intestinal epithelial cells.
Enterocyte-like cells were polarized with tight junctions, lateral membrane
interdigitations, and well-organized microvilli with associated glycocalyx
located at the apical pole. Remarkably, there were also cells with a goblet
cell-like ultrastructure, suggesting that two of the four intestinal
epithelial cell lineages may arise from IEC-6 cells. Molecular evidence for
differentiation was shown by demonstrating that cells expressing high
levels of Cdx2 expressed sucrase-isomaltase, an enterocyte-specific gene
which is a well-defined target for the Cdx2 protein. Taken together, our
data suggest that Cdx2 may play a role in directing early processes in
intestinal cell morphogenesis and in the maintenance of the differentiated
phenotype by supporting transcription of differentiated gene products. We
propose that Cdx2 is part of a regulatory network that orchestrates a
developmental program of proliferation, morphogenesis, and gene expression
in the intestinal epithelium.
Copyright © 1996, American Society for Microbiology
An intestine-specific homeobox gene regulates proliferation and differentiation
Department of Medicine, University of Pennsylvania, Philadelphia 19104- 6144, USA.
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