TSE3 is an orphan gene essential for thymocytes development (160.3)

Abstract The development of T cells in the thymus involves several differentiation and proliferation events, during which hematopoietic precursors give rise to single positive mature T cells. T cell antigen receptor (TCR) signaling during CD4+CD8+ double-positive stage determines cell survival (thymocytes selection) and lineage commitment (CD4-versus-CD8 lineage choice). However, this process is also regulated by other signaling pathways, which are not fully characterized. To explore this field, we analyzed several expressed sequence tag (EST) libraries from murine thymus and identified several ESTs specifically expressed in thymus including a previous uncharacterized transcript TSE3 (Thymic specific expression, number 3). TSE3 encodes a protein without any known domains or motifs but is conserved among vertebrates. We found that TSE3 is highly expression in different stages of T cell development especially in double positive thymocytes. In TSE3-deficient mice, thymocytes development was impaired reflected by decreased numbers and percentages of mature single positive CD4 and CD8 T cells in both thymus and peripheral lymphoid organs. We are further characterizing the TSE3 deficient mice to reveal the underlying mechanism used by TSE3 to participate in the thymic T cells development.