MOLECULAR ANALYSIS OF THE CD40 RECEPTOR COMPLEX

B细胞表面抗原CD4O与其配体(CD4OL)的相互作用 活化T细胞上的表达在T-B细胞中起关键作用 合作，特别是在免疫球蛋白(Ig)同型转换方面。 X-连锁高免疫球蛋白M综合征患者CD4OL基因突变 小鼠CD4O或CD4OL基因缺失导致免疫球蛋白缺陷 同型转换。CD4O独特的触发同种异型的能力 B细胞的转换表明，必须有一条新的信号通路 被CD4O利用。 我们最近发现了一种与B细胞相关的26kD蛋白 表面涂有人类CD4O。三种内源性多肽的序列分析 结果表明，P26是一种新的蛋白质。我们有证据表明 P26可能用于CD4O结扎后的信号转导。我们 建议对P26进行表征，分析其与CD4O的相互作用并对其进行解剖 P26和CD4O在免疫球蛋白同型转换中的单独作用 使用CD4O和P26基因被破坏的转基因小鼠。 在目标1中，我们建议通过a)分离和鉴定P26 人和小鼠P26 CDN的序列测定，b)P26抗体的产生 以及P26和P26相关蛋白的检测以及c)研究 P26在B细胞发育过程中的表达 在AIM II中，我们建议分析CD4O和P26之间的相互作用。我们 将a)检查共转染细胞中CD4O和P26的相关性 用CD4O和P26基因和b)确定CD4O在P26表面的作用 通过研究P26在CD4O-/-小鼠B细胞上的表达。 在AIM III中，我们将通过以下方式执行P26信令的功能分析 A)通过抗P26抗体检查信号和b)确定其作用 CD4O-/-小鼠B细胞和B细胞在P26信号转导中的作用 表达CD8：P26嵌合分子。 在目标IV中，我们将研究P26在CD4O信号转导中的作用 P26基因缺陷小鼠的构建及其CD4O信号转导的研究 老鼠。 鉴于CD4O在免疫球蛋白同型转换和B细胞中的中心作用 抗原呈递给T细胞，详细了解 CD4O信号转导机制是设计治疗方案的关键 旨在防止同型转换和/或诱导耐受性的策略 对B细胞呈递的抗原。这些策略适用于 变态反应性和自身免疫性疾病的治疗和预防 同种异体排斥反应。

Interaction of the B cell surface antigen CD4O with its ligand (CD4OL) expressed on activated T cells plays a critical role in T-B cell collaboration, particularly in immunoglobulin (Ig) isotype switching. Mutations in the CD4OL in patients with X-linked Hyper IgM syndrome and disruption of the CD4O or CD4OL genes in mice result in deficient Ig isotype switching. The unique capacity of CD4O to trigger isotype switching in B cells suggests that a novel signaling pathway must be utilized by CD4O. We have recently identified a 26 kD protein associated on the B cell surface with human CD4O. The sequence of three internal peptides derived from p26 indicate that p26 is a novel protein. We have evidence to suggest that p26 may be used to transduce signals following ligation of CD4O. We propose to characterize p26, analyze its interaction with CD4O and dissect the individual role of p26 and CD4O in immunoglobulin isotype switching using transgenic mice with disrupted CD4O and p26 genes. In Aim 1 we propose to clone and characterize p26 by a) isolation and sequencing of human and mouse p26 cDN, b) generation of antibodies to p26 and detection of p26 and of p26 associated proteins and c) studying the expression of p26 during B cell development. In Aim II we propose to analyze the interaction between CD4O and p26. We will a) examine the association of CD4O and p26 in cells cotransfected with CD4O and p26 cDNA and b) determine the role of CD4O in p26 surface expression by studying p26 expression on B cells from CD4O-/- mice. In Aim III we will perform a functional analysis of signaling via p26 by a) examining signaling via anti-p26 antibodies and b) determining the role of CD4O in p26 signaling using B cells from CD4O-/- mice and B cells expressing a CD8:p26 chimeric molecule. In Aim IV we will examine the role of p26 in CD4O signaling by constructing p26 deficient mice and assessing CD4O signaling in these mice. Given the central role of CD4O in Ig isotype switching and in B cell presentation of antigen to T cells, a detailed understanding of the mechanisms of CD4O signalling is critical for devising therapeutic strategies aimed at preventing isotype switching and/or inducing tolerance to antigens presented by B cells. These strategies are applicable to the treatment of allergic and autoimmune diseases and to the prevention of allograft rejection.