| In the past 10 years, molecular genetic and tissue engineering has played an important role in understanding molecular organogenesis. We assume that some events occurring in cancer would recapitulate events occurring during different developmental stages. Therefore, a better understanding of the developmental progression may lead us to find the way of controlling cancer in the future. Here, the studies of epithelial organogenesis of the liver and skin appendage in chicken embryos were examined.; We identified the localized growth zone (LoGZ) in the chicken liver that enriched the proliferative regulating factor called beta-catenin. Expression of constitutively active beta-catenin caused an expansion of the liver precursor cell population, resulting in hepatomegaly. In contrast, inhibition of Wnt signaling with the universal antagonist, Dkk, caused a dramatic reduction in liver mass.; We then examined the role of BMP-4 and found that this signal from the mesenchymal sinusoidal endothelial cells (MSECs) is important for the differentiation and formation of hepatic cords. By over-expressing BMP-4, the liver cells were accelerated and enhanced their differentiation, forming the hepatic cord precociously. Blocking the BMP signal with its antagonist, Noggin slowed the process and led to the accumulation of premature hepatic cords.; In addition, we looked into cell shape and size changes that are essential for boundary formation during feather development. We found that ephrin-B1, which is a cell membrane-bound molecule, is involved in this process. By using the soluble ephrin-B1/Fc recombinant we were able to block the reverse signal, generated through ephrin-B1 which resulted in immature invagination of the epithelium due to interrupted cell shape changes.; Taken together, interactions between epithelial and mesenchymal cells are very important for epithelial organ to form properly. There are three steps during the process: initiation, morphogenesis, and differentiation. A better understanding of these processes would enhance our understanding of tumor biology and aid in finding a way to control or prevent cancer in the future. |
