Region-specific expression of chicken Sox2 in the developing gut and lung epithelium: Regulation by epithelial-mesenchymal interactions

In situ analysis of the chicken cSox2 gene, a member of the transcription f actor family containing an Sry-like high-mobility group (HMG) box, demonstr ated localized expression in the embryonic endoderm, Transcripts of cSox2 a ppeared before commencement of morphogenesis and cytodifferentiation in the rostral gut epithelium from the pharynx to the stomach. The caudal limit o f cSox2 expression coincided with that of the region competent for proventr icular differentiation and to the rostral limit of the domain of CdxA, a ho mologue of Drosophila caudal, During morphogenesis, the level of transcript s of cSox2 decreased in epithelia invaginating into surrounding mesenchyme to form glandular or tubular structures, such as the primordia of the thyro id and lung, glandular epithelium of the proventriculus, and secondary bron chus of the lung, Tissue recombination experiments demonstrated that cSox2 expression is regulated by the underlying mesenchyme as well as morphogenes is and cytodifferentiation. The results suggest that cSox2 plays pivotal ro les in generating morphologically and physiologically distinct types of epi thelial cells in the gut. Dev. Dyn. 1998;213:464-475. (C) 1998 Wiley-Liss, Inc.