FUNCTION OF THE PROTEINS PU1 AND SPI-B IN B LYMPHOCYTES

造血是由多能造血干细胞产生淋巴细胞的过程。 我感兴趣的是确定两个Ets结构域转录因子，PU. 1和Spi-B，在B淋巴细胞的分化和功能的作用。在小鼠中使用基因敲除技术，我们先前已经证明PU.1是小鼠胚胎发育的必需蛋白质。 PU.1负/负小鼠缺乏淋巴和骨髓小鼠细胞，并在子宫内死亡。 相反，Spi-B-/-小鼠是存活的，但表现出B细胞对抗原的功能应答的缺陷。 为了更具体地剖析Spi-B和PU. 1介导的独特和冗余功能，我已经产生了基因型PU. 1加/减，Spi-B加/减，PU. 1加/减，Spi-B减/减和PU. 1减/减，Spi-B减/减的小鼠。 PU.1-/-，Spi-B-/-小鼠表现出与PU.1-/-，Spi-B +/+小鼠相同的表型：它们缺乏所有淋巴和骨髓细胞，并在子宫内死亡。 有趣的是，PU. 1 +/-、Spi-B-/-小鼠是存活的，但在骨髓和外周淋巴器官中表现出B220+/IgM+和IgM+/IgD+未成熟和成熟B细胞的数量大大减少。 这些小鼠还表现出成熟B细胞功能的严重缺陷。 我的初步数据强烈表明，通过B细胞受体（BCR）的信号传导在Spi-B-/-和PU. 1 +/-，Spi- B-/-小鼠中在蛋白激酶C（PKC）激活前的近膜步骤是有缺陷的。 我提出的实验（1）表征PU. 1 +/-，Spi-B-/-小鼠中的B细胞发育缺陷，（2）鉴定Spi-B-/-和PU. 1 +/-，Spi-B-/-小鼠中BCR信号传导缺陷的分子基础。

Lymphopoiesis is the process by which lymphocytes are generated from pluripotent hematopoietic stem cells. I am interested in defining the role of two Ets domain transcription factors, PU.1 and Spi-B, in the differentiation and function of B lymphocytes. Using gene knockout technology in mice, we have previously shown that PU.1 is an essential protein for embryonic development in mice. PU.1 minus/minus mice lack both lymphoid and myeloid mice cells and die in utero. In contrast, Spi-B minus/minus mice are viable but exhibit defects in the functional response of B cells to antigen. To dissect both the unique and redundant functions mediated by Spi-B and PU.1 more specifically, I have generated mice with the genotypes PU.1 plus/minus, Spi-B plus/minus, PU.1 plus/minus, Spi-B minus/minus and PU.1 minus/minus, Spi-B minus/minus. PU.1 minus/minus, Spi-B minus/minus mice exhibit the same phenotype as PU.1 minus/minus, Spi-B plus/plus mice: they lack all lymphoid and myeloid cells and die in utero. Interestingly, PU.1 plus/minus, Spi-B minus/minus mice are viable but exhibit greatly decreased numbers of B220+/IgM+ and IgM+/IgD+ immature and mature B cells in the bone marrow and peripheral lymphoid organs. These mice also exhibit severe defects in mature B cell function. My preliminary data strongly suggest that signaling via the B cell receptor (BCR) is defective in Spi-B minus/minus and PU.1 plus/minus, Spi- B minus/minus mice at a membrane-proximal step prior to the activation of protein kinase C (PKC). I propose experiments to (1) characterize the B cell developmental defect in PU.1 plus/minus, Spi-B minus/minus mice and (2) identify the molecular basis of the BCR signaling defect in Spi-B minus/minus and PU.1 plus/minus, Spi-B minus/minus mice.