A possible role for the canonical Wnt pathway in endocrine cell development in chicks

Writ signalling is involved in many developmental processes such as proliferation, differentiation, cell fate decisions, and morphogenesis. However, little is known about Wnt signalling during pancreas development. Multiple Writ ligands and Frizzled receptors are expressed in the embryonic mouse pancreas, the surrounding mesenchyme, and have also been detected in the chicken endoderm during development. The aim of this study was to investigate the role of canonical Writ signalling on endocrine cell development by use of the in ovo electroporation of the chicken endoderm. Overexpression with a constitutive active form of beta-catenin in combination with Ngn3 resulted in reduced numbers of glucagon cells. dnLEF-1 or naked-1 did not alter endocrine cell differentiation when co-expressed with Ngn3, but dnLEF-I appeared to have some potential for inhibiting delamination of Ngn3 cells. In addition, neuronal beta-III-tubulin, which had previously been considered a specific marker for neuronal cells, was observed in the pancreas and was upregulated in the electroporated Ngn3 cells and thus may be a new endocrine marker in the chicken. (c) 2005 Elsevier Inc. All rights reserved.