STRUCTURE/FUNCTION B CELL DIFFERENTIATION ANTIGENS

两种B细胞分子，CD 40和CD 80（以前称为B7/BB 1），两者都不是 整合素或选择素，已配对的辅受体上发现的 活化（CD 40 L）或静息（CD 28）T细胞。这些受体配体对 是新颖的，因为他们在同源T-B对话中参与，并允许 T细胞和B细胞来感知其伴侣的激活状态， 然后做出适当的回应。这两个受体配体对 T细胞依赖性B细胞成熟过程中的连接。CD 40提供了一种 从活化的CD 4 + T细胞到B细胞的基本信号。两种CD 40 L X连锁高IgM综合征和CD 40缺陷型患者 抗原刺激后的小鼠不能形成生发中心或转换 从IgM到其他IG类或亚类。本项目的主要目标是 目的是阐明CD 40 L-CD 40的信号转导和调控 途径，并确定其他新的表面分子对人类B 调节T细胞依赖性B细胞成熟的淋巴细胞。我们的目标 是：1.明确B淋巴细胞中CD 40的信号通路。我们有 发现交联CD 40快速诱导NF-kB的活化。我们 将使用NF-kB反应来定义CD 40信号传导中的早期事件， 上游和下游的NF-κ B表达的激活。我们将 使用NF-kB和蛋白酪氨酸激酶（PTK）反义寡核苷酸 为了检验CD 40依赖性诱导IL-6，拯救 细胞凋亡或同种型类别转换需要NF-κ B和/或某些PTK; 目标二。为了验证这一假设， 类转换需要CD 40在非B细胞上表达， 细胞（DC）和滤泡树突状细胞（FDC）。我们将制作一个 在κ启动子/增强子上表达小鼠CD 40的转基因小鼠系 （CD 40-B），即，仅在B细胞中表达CD 40，以检验这一假设; 目标3。表征CD 40表达的调节 配体（CD 40 L）。我们已经发现，交联CD 28 T细胞上的受体强烈诱导CD 40 L mRNA和表面的表达， 蛋白使用小鼠CD 40 L的基因组克隆，我们将测序和 表征CD 40 L启动子区。我们将在 可通过交联CD 3和/或CD 28激活的CD 40 L启动子 受体;目的4.为了验证Bgp 95和IPO-3 B细胞 表面分子起调节T细胞依赖性B细胞作用 成熟虽然CD 40 L-CD 40相互作用对于T细胞是必不可少的， 依赖于B细胞活化，B淋巴细胞上的其它受体也可 在调节B细胞成熟中是重要的。我们定义了小说 人B细胞上的糖蛋白，调节B细胞的Bgp 95和IPO-3 activation.我们将分离编码Bgp 95和IPO-3的cDNA，并使用 cDNA来定义这些分子的表达和功能。这些 这些研究将使我们更好地了解人类B细胞的活化 成熟是由T细胞调节的，这将有助于识别 B细胞相关自身免疫性疾病中调节异常的潜在位点 疾病和肿瘤。

Two B cell molecules, CD40 and CD80 (formerly B7/BB1), which are neither integrins nor selectins, have been paired to coreceptors found on activated (CD40L) or resting (CD28) T cells. These receptor-ligand pairs are novel in that they engage during the cognate T-B dialogues and allow T cells and B cells to sense the state of their partner's activation and then respond appropriately. These two receptor-ligand pairs intimately link during T cell-dependent B cell maturation. CD40 provides an essential signal to B cells from activated CD4+ T cells. Both CD40L deficient patients with X-linked hyper-IgM syndrome and CD40-deficient mice after antigen stimulation cannot form germinal centers or switch from IgM to other Ig classes or subclasses. The major goals of this proposal are to elucidate the signaling and regulation of the CD40L-CD40 pathway and to define other novel surface molecules on human B lymphocytes which regulate T-cell-dependent B cell maturation. Our Aims are: 1. To define the signaling pathway by CD40 in B lymphocytes. We have found that crosslinking CD40 rapidly induces the activation of NF-kB. We will use the NF-kB response to define early events in CD40 signaling both upstream and downstream from the activation of NF-kB expression. We will use NF-kB and protein tyrosine kinase (PTK) antisense oligonucleotides to test the hypothesis that CD40-dependent induction of IL-6, rescue of apoptosis or isotype class switching requires NF-kB and/or certain PTK; Aim 2. To test the hypothesis that germinal center formation and isotype class switching require CD40 expression on non-B cells such as dendritic cells (DC) and follicular dendritic cells (FDC). We will produce a transgenic mouse line expressing mouse CD40 on a kappa promoter/enhancer (CD40-B), i.e., expressing CD40 only in B cells, to test this hypothesis; Aim 3. To characterize the regulation of the expression of the CD40 ligand (CD40L) in T lymphocytes. We have found that crosslinking the CD28 receptor on T cells strongly induces expression of CD40L mRNA and surface protein. Using a genomic clone of mouse CD40L, we Will sequence and characterize the CD40L promoter region. We will define elements in the CD40L promoter that can be activated by crosslinking CD3 and/or CD28 receptors; Aim 4. To test the hypothesis that Bgp95 and IPO-3 B cell surface molecules function to regulate T-cell-dependent B cell maturation. Although the CD40L-CD40 interaction is essential for T-cell- dependent B cell activation, other receptors on B lymphocytes may also be important in regulating B cell maturation. We have defined novel glycoproteins on human B cells, Bgp95 and IPO-3 that regulate B cell activation. We will isolate cDNAs encoding Bgp95 and IPO-3 and use the cDNAs to define the expression and function of these molecules. These studies will lead to better understanding of how human B cell activation and maturation is regulated by T cells and will help to identify potential sites for dysregulation in B-cell-associated autoimmune diseases and neoplasms.