An in situ hybridization screen reveals new transcriptional regulators of third pharyngeal pouch and thymic epithelial cell differentiation. (86.12)

Abstract

Abstract Thymic epithelial cells (TECs) are the major component of the non-lymphoid framework of the thymus and are essential for normal T cell development. In mice, TECs develop from a domain of the embryonic third pharyngeal pouch endoderm marked by Foxn1 expression. Although Foxn1 is necessary for proliferation and differentiation of TECs, it is not required for specification of TECs from the pouch endoderm. Also, some aspects of TEC differentiation are Foxn1-independent. This suggests that there are additional transcription factors expressed within the third pouch endoderm that are responsible for early specification and differentiation of TECs. To identify additional transcriptional regulators of third pouch and TEC differentiation, we performed an in situ hybridization screen on a set of candidate transcription factors identified through a systematic analysis of gene expression databases. We found that most of the genes selected for detailed characterization were expressed in the third pharyngeal pouch endoderm and many of them were specifically expressed in the thymus domain of the pouch. These transcription factors are highly likely to be involved in the earliest steps of TEC development. Our work also shows that data mining of gene expression databases is an efficient way to identify genes involved in the development of a specific tissue or organ.