{'fraction_non_alphanumeric': 0.0342031029619182, 'fraction_numerical': 0.026445698166431594, 'mean_word_length': 5.087982832618025, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
cis elements of the human CDX2 gene regulate expression of transgenes in mouse colonic epithelial cells

Proc Amer Assoc Cancer Res, Volume 46, 2005

1975 

BACKGROUND: CDX2 is a caudal -related homeobox transcription factor that is expressed at high levels in epithelial cells of adult small intestine and colon in human and mouse. Previously, we found transcriptional activity of a reporter gene construct containing a 9.5-kb fragment from the 5’ region of the human CDX2 gene was well correlated with endogenous CDX2 expression in colon cancer cell lines (Hinoi T et al. , J. Biol. Chem . 278, 44608-16, 2003). This finding motivated us to assess the activity of the elements in an in vivo model. METHODS: Recombinant DNA constructs, containing 9.5-kb and 0.5-kb fragments from the 5’ region of the human CDX2 gene were cloned upstream of sequences for a nuclear localization signal and a LacZ (β-galactosidase) gene (CDX2P-9.5kb/NLSLacZ and CDX2P-0.5kb/NLSLacZ, respectively), were used to generate transgenic founders. Transgenic mice carrying the CDX2-9.5kb fragment upstream of sequences encoding a nuclear localization signal-Cre recombinase (CDX2P/NLSCre) fusion protein were also generated. β-galactosidase (β-gal) activity was measured by standard methods, and Cre expression/activity was analyzed by generating mice carrying the CDX2P/NLSCre transgene and Gtrosa26tm1Sor targeted mutation, which is a reporter for cells in which Cre recombinase has been active. RESULTS: In mice carrying the CDX2P-9.5kb/NLSLacZ construct, i n situ assays demonstrated strong β-gal expression in essentially all epithelial cells in appendix, colon, and rectal tissues, while minimal β-gal expression was seen in mice carrying CDX2P-0.5kb/NLSLacZ construct. The expression data from adult CDX2P-9.5kb/NLSLacZ transgenic mice contrast with data showing strong endogenous CDX2 expression throughout small intestine and colonic epithelium. Analysis in CDX2P-9.5kb/NLSLacZ staged embryos indicated β-gal expression largely mirrors the expression of CDX2 during development. Cre expression from mice carrying the CDX2P/NLSCre and Gtrosa26tm1Sor mutation was restricted in the gastrointestinal tract to distal ileum, appendix, colon, and rectum. Studies in various adult tissues indicated Cre expression is activated during development in caudal and posterior cells, which normally express CDX2 during development. CONCLUSIONS: A 9.5-kb 5’-flanking region from the human CDX2 gene contains key cis elements for regulating transcription predominantly in colonic epithelium of adult mice. Our studies with CDX2P/NLSCre mice suggest the mice may be very useful for somatic targeting of genes containing lox P sites preferentially in colonic epithelial cells of the adult mouse, perhaps allowing generation of new mouse colon cancer progression models.