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色血细胞，它可以产生对抗细菌和病毒感染所必需的抗体。B淋巴细胞在骨髓中通过一系列在分裂（增殖）或静止（静止）之间交替的阶段发育。为了制造抗体，B淋巴细胞必须利用一种叫做重组酶激活基因（RAG）的危险酶重组它们的免疫球蛋白基因。如果在细胞分裂期间发生重组，脱靶效应可能导致DNA损伤和细胞死亡。Spi-C是一种转录因子，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Spi-C在B细胞发育期间响应于RAG诱导的DNA损伤而表达。在初步的数据中，我们表明，Spic是上调血红素或培养条件下，诱导静止，而Spic是下调细胞因子诱导细胞分裂。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细胞外哪些因素激活Spi-C表达，确定Spi-C调控哪些基因表达程序，并确定Spi-C调控如何影响抗体产生。基于我们的初步数据，我们假设Spic在响应NF-κ B依赖性或血红素诱导的信号传导时上调;在响应细胞周期进展时下调。为了验证这一假设，我们将研究什么调节Spi-C表达（上游）和哪些基因受Spi-C（下游）调节。在上游，我们将确定Spi-C响应血红素或NF-κ B信号传导而上调的详细机制;以及Spi-C响应细胞周期进程而下调的机制。在Spi-C下游，我们将使用强力霉素诱导系统确定B细胞中的直接靶基因。最后，我们将确定Spi-C在B细胞系中对溶血产生的细胞内血红素和细胞外血红素的体内作用。这项工作是重要的，因为它将提供重要的洞察B细胞分化的机制，在响应环境信号。这些知识可用于改善对细菌或病毒感染的抗体反应。这项工作将由HQP主要在硕士和本科阶段进行，提供研究，口头陈述和写作技能的培训，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.