In vertebrates, all blood cells are generated through hematopoiesis. During the definitive hematopoiesis, hematopoietic stem cells (HSCs) are generated and give rise to various blood lineages including lymphoid cells, myeloid cells and erythroid cells. Among these hematopoietic cells, only T lymphoid-primed progenitors are destined to enter the thymus. However the in vivo characterization of this cell population is challenging due to the intrauterine development of mouse embryos. Thus, how the fate of these cells is determined has not been fully defined.

In a recent study, a research group led by Dr. Liu Feng at the Institute of Zoology of Chinese Academy of Sciences, has revealed the mechanism of fate determination of embryonic T lymphoid-primed progenitor by using zebrafish embryo, which is a valuable model to study hematopoiesis including T cell development in vivo. In this study, they observed that the homing of T lymphoid-primed progenitors to the thymus was impaired in the absence of interferon regulatory factor 4 (Irf4). Strikingly, fate mapping assays at the single-cell level showed a fate change of irf4-deficient T lymphoid-primed progenitors to myeloid cells. These data indicated that in addition to regulating the homing process, Irf4 is also essential in T lymphoid-primed progenitors to prevent an alternate fate.

The paper entitled“Irf4 regulates the choice between T lymphoid-primed progenitor and myeloid lineage fates during embryogenesis” was published online by Developmental Cell  on Aug 20, 2015. This work was supported by grants from the National Basic Research Program of China, the National Natural Science Foundation of China, and the Strategic Priority Research Program of the CAS.

Website link: http://www.cell.com/developmental-cell/abstract/S1534-5807(15)00462-1