| Abstrakt: |
Regional as well as cell-specific differences in gene expression are established and maintained in the perpetually regenerating intestinal epithelium. We have recently linked regions of the 5′-nontranscribed domain of the rat “liver” fatty acid binding protein (L-FABP) gene which is normally expressed in both liver and intestine, to a reporter, the human growth hormone (hGH) gene, and examined hGH expression in adult transgenic mice (Sweetser, D. A., Birkenmeier, E. H., Hoppe, P. C., McKeel, D. W., and Gordon, J. I. (1988) Genes Dev.2, 1318–1332). Our results indicated that cis-acting elements, including an orientation-independent suppressor, could produce a pattern of cellular and geographic expression of hGH which mimics that of the intact, endogenous murine Fabplgene in both organs. We now show that nucleotides −4000 to +21 of the rat L-FABP gene can direct “appropriate” cell-specific, regional, and temporal expression of the hGH reporter during a period of remarkable cellular expansion, cytodifferentiation, and morphologic transformation of the fetal gut epithelium. These studies also indicate that the polyclonal stem cell population located in the intervillous regions of the late fetal intestine exhibits a different pattern of transgene regulation than does the monoclonally derived crypt stem cell population in adult transgenic mice. |
