Tissue Specific Deletion of ZBP-89 in the Mouse Intestine Results in Expansion of Goblet and Paneth Cell Lineages.

Abstract

ZBP-89 (ZNF148, Zfp148) is a Kruppel-type transcription factor ubiquitously expressed in mice and humans. This factor is known to be associated with genes involved in embryogenesis, cellular proliferation, differentiation, growth arrest and apoptosis. In addition, in vitro studies using colorectal and gastric cancer cell lines have shown an increase in ZBP-89 mRNA, suggesting a role for ZBP-89 in cancers of the gastrointestinal tract. However to specifically define the in vivo role of ZBP-89 in cellular processes, it is necessary to study the effect of a null locus. Since previous studies have failed to generate a ZBP-89 null locus, we used a conditional targeting strategy to generate viable mice for analysis. Subsequently, mice containing loxP sites flanking exons 8 and 9 of ZBP-89 were produced by homologous recombination. However, the neomycin antibiotic resistance gene inserted into the locus for ES cell selection disrupted normal ZBP-89 gene function resulting in non-viable targeted mice. Therefore I removed the selectable marker from the locus by breeding the gene targeted mice to mice expressing FLP recombinase and restored ZBP-89 mRNA and protein expression levels. Following removal of the selectable marker from the locus, the mice were bred to transgenic mice expressing Cre recombinase under the control of the mouse villin promoter, which is active throughout the intestinal epithelium of adult mice. Deletion of ZBP-89 in the intestinal epithelium resulted in the expansion of the goblet and Paneth cell secretory lineages. Meanwhile the overall numbers of enteroendocrine cells, also a part of the secretory lineage, remained unaltered. This secretory expansion was at the expense of the absorptive enterocytes, whose cell numbers were dramatically decreased. Together these results suggest that ZBP-89 regulates cell fate in the small intestine.