Wnt signaling components in the chicken intestinal tract.

Wnt signal transduction has emerged as an increasingly complex pathway due to the numerous ligands, receptors, and modulators identified in multiple developmental systems. Wnt signaling has been implicated in the renewal of the intestinal epithelium within adult animals and the progression of cancer in the colon. The Wnt family, however, has not been explored for function during embryonic gut development. Thus, to dissect the role of Wnt signaling in the developing gastrointestinal tract, it is necessary to first obtain a complete picture of the spatiotemporal expression of the Wnt signaling factors with respect to the different tissue layers of the gut. Here, we offer an in depth in situ gene expression study of Wnt ligands, frizzled receptors, and frizzled related modulators over several days of chicken gut development. These data show some expected locations of Wnt signaling as well as a surprising lack of expression of factors in the hindgut. This paper describes the first comprehensive characterization of the dynamic expression of Wnt signaling molecules during gut development. These data form the basis for future studies to determine the role of Wnt signaling in the developing gastrointestinal tract.