CD40 SIGNAL TRANSDUCTION

描述：(改编自研究人员的摘要)CD40是一种细胞 B细胞表面跨膜型45 kDa糖蛋白受体的表达 淋巴细胞。CD40的激活对B细胞的增殖至关重要， 免疫球蛋白类别转换。NFkB的激活与生殖细胞的挽救 中心B细胞在体细胞突变后不会发生凋亡。抵抗力 通过诱导抗死亡基因来诱导细胞凋亡。 产品，Bclx。CD40是肿瘤坏死因子受体的成员 家庭，和其他成员一样，它似乎没有内在的 信号传递能力(例如，激酶活性)，表明该信号 转导很可能是由联合分子介导的。要确定 利用酵母双杂交系统克隆了这些分子的cDNA 编码与CD40细胞质结构域结合的蛋白质。这样的一个 相互作用蛋白，命名为CD40结合蛋白(CD40BP)，具有一个N- 终端无名指图案和突出的中央盘绕线圈段 这可能会允许同种或异种齐聚。值得注意的是，C- 末端与肿瘤坏死因子有很大的同源性 在两种蛋白质中发现的受体相关因子(TRAF)结构域 (TRAF1和TRAF2)与细胞质区相关 相关的75kD肿瘤坏死因子受体。显性负值CD40bp 抑制CD40激活对Bclx的诱导 暗示了它在信号传递中的重要作用。第二个CD40相互作用 鉴定的蛋白质是TRAF2，它的过度表达导致了 核因子-kB的激活。值得注意的是，显性负TRAF2完全 阻断CD40对NFkB的激活，证实TRAF2偶联 核因子-k B途径的受体。这笔赠款的目的是 应用程序，以利用这些发现。以下是具体的 AIMS将被实施。具体目标1：确认内源性CD40BP TRAF2以配体依赖的方式与CD40结合，而TRAF 结构域确实负责受体的关联。具体目标2： 使用酵母双杂交和互补生化方法来 CD40BP和TRAF2相互作用蛋白的克隆和鉴定。特定的 目标3：确定CD40BP和TRAF2是否调制其他CD40信号 包括胞浆src样激酶和PI3激活的事件 激活剂。

DESCRIPTION: (adapted from the investigator's abstract) CD40 is a cell surface transmembrane 45kDa glycoprotein receptor expressed on B- lymphocytes. CD40 activation is critical for B-cell proliferation, immunoglobulin class switching. NfkB activation and rescue of germinal center B-cells from apoptosis following somatic mutation. Resistance to apoptosis is conferred by the induction of the anti-death gene product, Bcl-x. CD40 is a member of the tumor necrosis factor receptor family and, like other members, it appears to possess no intrinsic signalling capacity (e.g. kinase activity), suggesting that signal transduction is likely mediated by associating molecules. To identify such molecules, the yeast two hybrid system was used to clone cDNAs encoding proteins that bind to the CD40 cytoplasmic domain. One such interacting protein, designated CD40-binding protein (CD40bp), has a N- terminal RING finger motif and a prominent central coiled-coil segment that may allow homo- or hetero-oligomerization. Significantly, the C- terminus possesses substantial homology to the tumor necrosis factor receptor-associated factor (TRAF) domain that is found in two proteins (TRAF1 and TRAF2) that associate with the cytoplasmic domain of the related 75kD tumor necrosis factor receptor. Dominant-negative CD40bp inhibited the induction of Bcl-x in response to CD40 activation suggesting an important role in signaling. The second CD40 interacting protein identified was TRAF2, over- expression of which resulted in the activation of NF-kB. Notably, dominant- negative TRAF2 completely abrogated the activation of NfkB by CD40, confirming that TRAF2 couples the receptor to the NF-k B pathway. It is the intention of this grant application to capitalize on these findings. The following Specific Aims will be undertaken. Specific Aim 1: Confirm that endogenous CD40bp and TRAF2 bind CD40 in a ligand dependent fashion and that the TRAF domain is indeed responsible for receptor association. Specific Aim 2: Use the yeast two-hybrid and complementary biochemical approaches to clone and characterize CD40bp and TRAF2 interacting proteins. Specific Aim 3: Determine if CD40bp and TRAF2 modulate other CD40 signaling events including activation of cytoplasmic src-like kinases and PI3 kinase.