Lymphotoxin-Beta Receptor Signaling

LTF‘R信号转导机制的研究进展 淋巴毒素-p受体(LTPR)信号通路协调 次级淋巴组织通过激活NFicB转录因子家族，包括 NFicB1(relA/p50)和NFicB2(relB/p52)。生化和遗传学证据支持LTPR模型 结扎通过涉及丝氨酸激酶NIK和Ikka的分步事件激活NFxB，NIK和Ikka控制着 P100-&gt；52的蛋白水解性处理。环指蛋白TRAF家族的成员，TRAF2、3和5， 被认为是LTPR的信号适配器，然而，缺乏这些TRAF的小鼠不会复制 LTpR-/-小鼠，因此TRAF在体内LTf5R信号转导中的作用是个谜。这个项目特别寻求 定义TRAF3如何参与激活NFxFI的LTpR信号通路。我们建议TRAF 抑制关键酶活性的功能调节剂和考虑TRAF和NIK的模型 在非活性复合体中预结合，并且在连接时，LTpR竞争性地取代Traf中的Nik， 释放Nik使蛋白质底物磷酸化。各种试剂，包括TRAF和TRAF的晶体 基因定义的细胞系已经被组装起来，以确定TRAF在LTPR信号通路中的作用 在相关的生理反应中。提出了检验该模型的三个目标：第一个目标是竞争性 位移模型预测，Nik-TRAF3相互作用将受到改变的点突变的影响 LTPR-TRAF3相互作用。LTPR、TRAF和NiK的靶向突变将被检测其对 结合相互作用，亚细胞定位和运输，酶活性，NFxB处理和信号转导 基因定义的细胞系来解决这一模型。在目标2中，Nik-TRAF3相互作用的结构基础 将通过使用Nik多肽-TRAFS晶体的X射线衍射来确定。第三个目标将决定 导入LTPR的TRAF结合突变体对LTPR-TRAF相互作用的生理影响 小鼠骨髓细胞构建嵌合体以检测其对NFtcB依赖基因表达的影响 活着。这些方法将为TRAF在LTPR信号通路中的作用提供直接的评估。

MECHANISMS OF LTf'.R SIGNAL TRANSDUCTION The Lymphotoxin-p receptor (LTPR) signaling pathway orchestrates the development and organization of secondary lymphoid tissues through the activation of NFicB family of transcription factors, including NFicB1(relA/p50) and NFicB2(relB/p52). Biochemical and genetic evidence supports a model in which LTPR ligation activates NFxB via a stepwise event involving the serine kinases, NIK and IKKa, which control the proteolytic processing of p100->52. Members of the TRAF family of RING finger proteins, TRAF2, 3 and 5, are thought to act as signal adaptors for LTPR, however mice deficient in these TRAFs do not phenocopy the LTpR-/- mice, thus the role of TRAFs in LTf5R signaling in vivo is enigmatic. This project specifically seeks to define how TRAF3 is involved in LTpR signaling pathways that activate NFxfi. We propose that TRAFs function regulators restraining the activity of key enzymes and consider a model in which TRAFS and NIK are preassociated in an inactive complex, and upon ligation, LTpR competitively displaces NIK from TRAFS, liberating NIK to phosphorylate protein substrates. A variety of reagents, including crystals of TRAFS and genetically defined cell lines, have been assembled to define the roles of TRAFs in LTPR signaling pathway in relevant physiologic responses. Three aims are proposed to test this model: In the first aim the competitive displacement model predicts that the NIK-TRAF3 interaction will be affected by the point mutations that alter LTPR-TRAF3 interactions. Targeted mutations in LTPR, TRAFS and NIK will be examined for their effect on binding interactions, subcellular location and trafficking, enzymatic activity, NFxB processing and signaling in genetically defined cell lines to address this model. In aim 2, the structural basis of NIK-TRAF3 interaction will be determined by X-ray diffraction using NIK peptide-TRAFS crystals. The third aim will determine the physiologic consequence of the LTPR-TRAF interaction by introducing TRAF binding mutants of LTPR into mouse bone marrow cells creating chimeras to examine their effect on NFtcB dependent gene expression in vivo. These approaches will provide a direct assessment of the role of TRAFs in LTPR signaling pathway.