LAUSR

SOX2 is expressed throughout the endoderm component. We investigated the involvement of SOX2 in the foregut development using a conditional Sox2-KO mouse line, where Sox2 is inactivated specifically in the endoderm by tamoxifen administration. Endoderm specific Sox2 inactivation resulted in the fusion of esophagus and trachea, bronchi branching directly from the fused duct, and shortening of esophagus. Based on the Sox2-KO embryo phenotypes, we are investigating the following points. 1) Is the loss of Sox2 expression in foregut affect the boundary between foregut and hindgut? 2) How does the loss of SOX2 cause fusion of trachea and esophagus? 3) Are the mesenchymal components involved in the Sox2-KO phenotypes? The complementary or inversely related expression patterns of transcription factors CDX2, NKX2.1, and SOX9 with SOX2 during lung and intestine development have been reported (Que et al., 2007, Gao et al., 2009, Mahony et al., 2014). In addition, the axial identity of digestive tract is considered to be regulated by Hox genes expressed in the mesenchyme at the circumference of the endodermal duct. Investigation is underway to clarify how expression of these transcription factors are affected in the Sox2-KO embryo.