Expression changes in intestinal crypts upon deletion of beta-catenin

The Wnt signaling pathway is deregulated in over 90% of human colorectal cancers. β Catenin, the central signal transducer of the Wnt pathway, can directly modulate gene expression by interacting with transcription factors of the TCF/LEF-family. In the present study we investigate the role of Wnt signaling in the homeostasis of intestinal epithelium using tissue-specific, inducible beta-catenin gene ablation in adult mice. Block of Wnt/beta-catenin signaling resulted in rapid loss of transient-amplifying cells and crypt structures. Importantly, intestinal stem cells were induced to terminally differentiate upon deletion of beta-catenin resulting in a complete block of intestinal homeostasis and fatal loss of intestinal function. Transcriptional profiling of mutant crypt mRNA isolated by laser capture micro dissection confirmed those observations and allowed to identify genes potentially responsible for the functional preservation of intestinal stem cells. Keywords: genetic modification laser capture microdissection of intestinal crypts, control vs. beta-catenin mutant (2days after induction of deletion by tamoxifen), two rounds of amplification of mRNA