MOLECULAR ANALYSIS OF THE CD40 RECEPTOR COMPLEX

B细胞表面抗原CD 4 O与其配体（CD 4 OL）的相互作用 在活化的T细胞上表达的蛋白在T-B细胞中起关键作用， 合作，特别是在免疫球蛋白（IG）同种型转换。 X-连锁高IgM综合征患者CD 4 OL突变及 小鼠中CD 4 O或CD 4 OL基因的破坏导致IG缺陷 同种型转换CD 4 O触发同种型的独特能力 在B细胞中的转换表明， 使用CD 4 O。 我们最近鉴定了一种与B细胞相关的26 kD蛋白 人CD 4 O表面。三个内部肽的序列 表明p26是一种新的蛋白质。我们有证据表明 p26可用于阻断CD 40连接后的信号。我们 我建议对p26进行表征，分析其与CD 4 O的相互作用，并分析其与CD 4 O的相互作用。 p26和CD 4 O在免疫球蛋白同种型转换中作用 使用具有破坏的CD 40和p26基因的转基因小鼠。 在目的1中，我们提出通过a）分离和鉴定p26， 人和小鼠p26 cDNA的测序，B）产生针对p26的抗体 以及检测p26和p26相关蛋白，以及c）研究 p26在B细胞发育过程中的表达。 在目的II中，我们建议分析CD 4 O和p26之间的相互作用。我们 a）检测共转染细胞中CD 40和p26的结合 与CD 4 O和p26 cDNA的结合，和B）确定CD 4 O在p26表面的作用 通过研究来自CD 40-/-小鼠的B细胞上的p26表达来表达。 在Aim III中，我们将通过以下方法对通过p26的信号传导进行功能分析： a）检查通过抗p26抗体的信号传导，和B）确定 使用来自CD 4 O-/-小鼠的B细胞和B细胞的p26信号传导中的CD 4 O 表达CD 8：p26嵌合分子。 在目的IV中，我们将通过以下方法研究p26在CD 4 O信号转导中的作用： 构建p26缺陷小鼠并评估这些小鼠中的CD 4 O信号传导。 小鼠 鉴于CD 4 O在IG同种型转换和B细胞中的中心作用， 抗原呈递给T细胞，详细了解 CD 4 O信号传导机制对于设计治疗方案至关重要。 旨在防止同种型转换和/或诱导耐受性的策略 B细胞呈递的抗原。这些策略适用于 治疗过敏性和自身免疫性疾病以及预防 同种异体移植排斥反应。

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.