Biological role of the lineage-determining transcription factor Spi-C in B cells

B淋巴细胞是我们体内的白血球，它能产生对抗细菌和病毒感染所必需的抗体。B淋巴细胞在骨髓中发育，经历了分裂(增殖)或静止(静止)交替的一系列阶段。为了制造抗体，B淋巴细胞必须使用一种名为重组酶激活基因(RAG)的危险酶来重组它们的免疫球蛋白基因。如果在细胞分裂过程中发生重组，非靶点效应可能会导致DNA损伤和细胞死亡。Spi-C是一种转录因子，是一种位于细胞核中的蛋白质，可以打开或关闭其他基因。Spi-C是一种谱系决定转录因子：它可以通过激活或抑制基因表达程序来告诉细胞如何发育。已知在B细胞发育过程中，SPI-C的表达是对RAG诱导的DNA损伤的反应。在初步数据中，我们发现Spic在血红素或诱导静止的培养条件下上调；而Spic在诱导细胞分裂的细胞因子反应中下调。这项研究计划的长期目标是确定在发育中的B细胞中控制细胞周期停滞和细胞周期进入的因素。我们研究计划的短期目标是确定哪些细胞外因素激活SPI-C表达，确定哪些基因表达程序受SPI-C调控，并确定SPI-C调节如何影响抗体产生。根据我们的初步数据，我们假设Spic在核因子-kappaB依赖或血红素诱导的信号传导中上调，而在细胞周期进展中下调。为了验证这一假设，我们将调查是什么调控SPI-C的表达(上游)，以及哪些基因受到SPI-C的调控(下游)。上游，我们将确定SPI-C上调的详细机制，以响应血红素或核因子-kappaB信号；以及SPI-C下调的机制，以响应细胞周期进展。在SPI-C下游，我们将使用多西环素诱导系统确定B细胞中的直接靶基因。最后，我们将确定SPI-C在B细胞谱系中对溶血产生的细胞内和细胞外血红素的反应中的体内作用。这项工作很重要，因为它将为B细胞分化对环境信号的反应机制提供重要的见解。这一知识可用于提高对细菌或病毒感染的抗体反应。这项工作将由总部主要在硕士和本科生层面进行，提供研究、口头陈述和写作技能方面的培训，可用于未来的就业和进一步的专业培训。

B lymphocytes are white blood cells in our bodies that make antibodies necessary to fight infection by bacteria and viruses. B lymphocytes develop in the bone marrow through a series of stages that alternate between dividing (proliferating) or resting (quiescent). To make antibodies, B lymphocytes must recombine their immunoglobulin genes using a dangerous enzyme called the recombinase-activating gene (RAG). If recombination occurs during cell division, off-target effects could lead to DNA damage and cell death. Spi-C is a transcription factor, a protein located in the nucleus of cells, that turns other genes on or off. Spi-C is a lineage-determining transcription factor: it can tell cells how to develop by activating or repressing programs of gene expression. Spi-C is known to be expressed in response to RAG-induced DNA damage during B cell development. In preliminary data, we show that Spic is upregulated in response to heme or culture conditions that induce quiescence; whereas Spic is downregulated in response to cytokines that induce cell division. The long-term goal of this research program is to identify the factors that govern cell cycle arrest and cell cycle entry in developing B cells. The short-term goals of our research program are to determine what factors outside the cell activate Spi-C expression, to determine what gene expression programs are regulated by Spi-C, and to determine how Spi-C regulation impacts antibody production. Based on our preliminary data, we hypothesize that Spic is upregulated in response to NF-kappaB-dependent or heme-induced signaling; and downregulated in response to cell cycle progression. To test this hypothesis, we will investigate what regulates Spi-C expression (upstream) and what genes are regulated by Spi-C (downstream). Upstream, we will determine the detailed mechanism by which Spi-C is upregulated in response to heme or NF-kappaB signaling; and the mechanism by which Spi-C is downregulated in response to cell cycle progression. Downstream of Spi-C, we will determine the direct target genes in B cells using a doxycycline-inducible system. Finally, we will determine the in vivo role of Spi-C in the B cell lineage in response to intracellular heme and extracellular heme generated by hemolysis. This work is important because it will provide important insight into the mechanisms underlying B cell differentiation in response to environmental signals. This knowledge can be used to improve antibody responses to bacterial or viral infections. This work will be carried out by HQP primarily at the Masters and undergraduate levels, providing training in research, oral presentation, and writing skills that can be leveraged for future employment and further professional training.