Predoctoral Fellowship for Minority Students

造血是祖细胞分化成不同血细胞谱系的发育过程。Ets蛋白在这个过程中至关重要。Ets蛋白PU.1在B细胞、单核细胞、粒细胞、巨核细胞、肥大细胞和未成熟红细胞中表达。Spi-B与PU.1高度相关，主要在B细胞中表达。PU.1和Spi-B结合相同的DNA元件，因此它们可能激活相似的靶基因。PU.1-/-突变小鼠在胚胎第16.5天死亡，缺乏B细胞、T细胞、单核细胞和粒细胞。Spi-B /-小鼠是存活的，但在B细胞中表现出功能缺陷。鉴于突变小鼠表现出的独特表型，本提案中描述的实验旨在鉴定这些相关蛋白质的重叠和独特功能。Spi-B和Ets-1（一种与PU.1高度不同的Ets蛋白）将被插入ES细胞的PU.1位点。为了确定Spi-B和Ets-1是否补充PU.1缺陷，将通过体外分化来分析这些蛋白质以观察骨髓细胞。接下来，将使用体外B细胞培养系统和RAG嵌合体小鼠来观察Spi-B的B细胞拯救。最后，将产生在PU.1基因座中具有Spi-B的小鼠，以确定是否挽救了胚胎致死性以及是否产生了适当数量的血细胞。上述实验将启发我们了解PU.1和Spi-B共享的功能以及每种蛋白质独特的功能。

Hematopoiesis is the developmental process in which progenitor cells differentiate into different blood cell lineages. Ets proteins are critical to this process. The Ets protein PU.1 is expressed in B cells, monocytes, granulocytes, megakaryocytes, mast cells and immature erythrocytes. Spi-B, which is highly related to PU.1 is predominantly expressed in B cells. PU.1 and Spi-B bind the same DNA elements, so they may activate similar target genes. PU.1-/- mutant mice die at embryonic day 16.5 lacking B cells , T cells, monocytes and granulocytes. Spi-B /- mice are viable but exhibit functional defects in B cells. Given the distinct phenotypes exhibited by mutant mice, the experiments described in this proposal are designed to identify overlapping and unique functions of these related proteins. Spi-B and Ets-1 (an Ets protein highly divergent from PU.1) will be Inserted into the PU.1 locus in ES cells. To determine if Spi-B and Ets-1 complement PU.1 deficiency, these proteins will be analyzed by in vitro differentiation to look at myeloid cells. Next an in vitro B cell culture system and RAG chimera mice will be used to look at B cell rescue by Spi-B. Finally, mice with Spi-B in the PU.1 locus will be generated to determine if the embryonic lethality is rescued and if blood cells are produced in appropriate numbers. The experiments outlined above will enlighten us to the functions PU.1 and Spi-B share and the functions unique to each protein.