Searching for the factors concerning hematopoiesis

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One of the purposes of this study is cloning the genes of the factors that have some roles in early hematopoiesis. For this purpose, we combined the in vitro hematopoietic differentiation induction method from mouse embryonic stem cells and the signal sequence trap method that is a method to select secretory proteins containing signal peptide. cDNA library was constructed from the day 5 induced mesodermal cell colonies in which hemangioblasts and hematopoietic progenitors existed. As a result, cDNA named ESOP-1 was cloned. The deduced amino acid sequence shows 160 amino acids protein. Human ESOP-1 was also cloned and shows 64% homology. ESOP-1 cDNA was highly expressed in embryos at day 7.5 of gestation. This gene was also expressed in both adult and embryonic hematopoietic system. Antibody was produced against this protein and immuno staining revealed that the protein was expressed in yolk sac, developing nervous system and adult genital organs.The other outcome is the analysis of the … More fuction of Bcl-X gene on erythropoiesis. We utilized Bcl-X null mouse embryonic stem cells (ES cells), and showed that Bcl-X is indispensable for the production of both embryonic primitive erythrocytes (EryP) and adult definitive erythrocytes (EryD) at the end of their maturation. In vivo, bcl-x null ES cells did not contribute to circulating EryD in adult chimeric mice that were produced by blastocyst microinjection of the bcl-x null ES cells. bcl-x null EryP and EryD were produced by in vitro differentiation induction of ES cells on a macrophage colony-stimulating factor deficient stromal cell line OP9, and further analysis was carried out. The emergence of immature EryP and EryD from bcl-x null ES cells was similar to that from normal ES cells. However, prominent cell death of bcl-x null EryP and EryD occurred when the cells matured. Erythropoietin is thought to prevent the apoptotic cell death of erythroid progenitor cells, while the anti-apoptotic function of bcl-x acts at the very end of maturation. Less