CELLULAR AND MOLECULAR EVENTS IN B LYMPHOCYTE ACTIVATION

小鼠乳腺肿瘤前病毒（MMTV）基因组成型表达 在B谱系的细胞中，并且可以在B细胞 分化一个MMTV基因，其3'端的开放阅读框（ORF）， 长末端重复序列（LTR）已被证明编码“内源性 超级抗原”。当内源性表达时， 表达适当的V β元件的细胞。3' LTR ORF还 编码作为反式激活因子的蛋白质。的功能 反式激活因子是未知的，但它可能是重要的病毒生活 循环，并可能有助于病毒的转化潜力。的 本提案中概述的实验旨在表征 调节B谱系细胞中MMTV基因表达，以及 确定LTR衍生蛋白的功能。我们将评估 调节超抗原在B淋巴细胞中的表达，并在 超抗原的功能性表达是什么水平， 严格监管。我们将确定结构和细胞 MMTV 3' LTR ORF功能性反式激活的要求，和 确定反式激活是否是B细胞限制性效应或需要 3' LTR蛋白和II类分子的结合。我们将评估 这些蛋白质之间的关系 反式激活和超抗原活性。我们将描述 在B细胞中被反式激活的细胞基因，并决定 介导反式激活的中间蛋白。我们 将表征U3区域的顺式调节序列 MMTV LTR，其控制MMTV中的组成型和上调基因表达， LPS和IL-5刺激B细胞，并测定其蛋白质， 结合这些序列类似于其他已知的转录 调节蛋白我们将确定免疫系统在 MMTV的生命周期，测试的假设， 需要超抗原反应性T细胞和病毒感染的B细胞 病毒在受感染小鼠体内的水平传播。最后， 我们将使用转染的细胞和转基因小鼠组成， 表达3' LTR ORF基因以确定是否有其它原癌基因 在细胞转化中与该MMTV编码基因协同作用。的 在本申请中提出的研究将解决关于 B淋巴细胞的生物学，病毒与淋巴细胞的相互作用， 免疫系统，以及有关免疫系统性质的基本问题 反式激活蛋白、转化和肿瘤发生。

Mouse mammary tumor proviral (MMTV) genes are constitutively expressed in cells of the B lineage and can be regulated during B cell differentiation. One MMTV gene, the open reading frame (ORF) of the 3' long terminal repeat (LTR), has been shown to encode "endogenous superantigens". When expressed endogenously, superantigens delete T cells expressing appropriate V Beta elements. The 3' LTR ORF also encodes a protein(s) that is a transactivator. The function of the transactivator is no known, but it may be important in the viral life cycle and may contribute to the transforming potential of the virus. The experiments outlined in this proposal are designed to characterize the regulation of MMTV gene expression in cells of the B lineage, and to determine the function(s) of LTR-derived proteins. We will evaluate the regulation of superantigen expression in B lymphocytes, and determine at what level(s) the functional expression of superantigens is post- translationally regulated. We will determine the structural and cellular requirements for functional transactivation by the MMTV 3' LTR ORF, and determine if transactivation is a B cell restricted effect or requires association of the 3' LTR protein and class II molecules. We will assess the relationship between the proteins that are responsible for transactivation and superantigen activities. We will characterize the cellular genes that are transactivated in B cells, and determine the intermediary protein(s) through which transactivation is mediated. We will characterize the cis-regulatory sequences in the U3 region of the MMTV LTR which control constitutive and upregulated gene expression in LPS and IL-5 stimulated B cells, and determine of the proteins which bind these sequences are similar to other known transcriptional regulatory proteins. We will determine the role of the immune system in the MMTV life cycle, testing the hypothesis that interactions between superantigen reactive T cells and virally infected B cells are required for the horizontal transmission of the virus in infected mice. Finally, we will use transfected cells and transgenic mice constitutively expressing the 3' LTR ORF gene to determine if other protooncogenes cooperate with this MMTV encoded gene in cellular transformation. The studies proposed in this application will address issues concerning the biology of B lymphocytes, the interactions of viruses with cells of the immune system, and fundamental problems concerning the nature of transactivating proteins, transformation, and oncogenesis.