NF-kB regulation by p105 and p100

描述(申请人提供)：转录因子NF-B和抑制物I？B家族的成员是多种细胞信号通路的关键调节者，这些信号通路对细胞生理，特别是免疫调节，细胞的生存和增殖具有深远的影响。核因子-β1(又称p105/p50)和核因子-β2(又称p100/p52)都属于核因子-βB和I？B家族。P105和P100是被加工成较小产物的前体，P50和P52是核因子-βB家族的成员。前体作为核因子-βB的抑制剂，包括它们自己的加工产品。必须严格控制加工，以生成适当比例的未加工和已加工表格。许多人类疾病，如自身免疫性疾病和癌症，都与P100和P105的不受调控的加工有关。P105和p100通过产生所有的NF-βp50和p52蛋白并抑制近一半的五种NF-β蛋白，从而揭示了在NF-β信号模块中高度复杂的调控事件。就像典型的I？B抑制剂，I？B？，-？和-β、p105和p100抑制剂也会完全降解，释放出核因子-？B转录因子。然而，在处理事件的背景下很难观察到完整的退化事件，因此不太被理解。P105的加工是构件性的，而P100的加工是诱导的。这项建议旨在研究加工和完全降解的生化机制以及这两个事件之间的耦合。根据我们的初步结果和已发表的报告，我们的假设是，对加工或缺乏加工的基本调节是由P105和P100中几个相互竞争的域间和域内相互作用指导的，这些相互作用可以通过信号来改变。我们认为，P105-自身相互作用诱导了一种有利于构造性加工的结构状态，而P100只有通过信号传递才能达到这种状态。我们进一步提出，作为完全组装的核因子-βB抑制复合体，P105和P100的加工位点被屏蔽了。这些组装的复合体中的P105和P100必须经过细胞信号的完全降解才能释放结合的NF-βB。我们将通过以下几个方面验证我们的假设：1)用X射线结晶学确定P105/P100与NF-？B结合的三维结构；2)确定P105/P100：NF-？B复合体的相互作用策略和能量；3)研究前体的加工和降解。 公共卫生相关性：我们提议的研究有可能解开长期存在的问题，即这两个核因子-kappaB前体蛋白如何作为核因子-kB的转录因子和抑制物执行双重功能。这两种蛋白质的失调与自身免疫性疾病和癌症密切相关。目前治疗多发性骨髓瘤的方法是抑制核因子-kB的异常激活。我们的工作将在寻找新的和更好的抑制剂方面发挥重要作用。

DESCRIPTION (provided by applicant): Members of the transcription factor NF-?B and inhibitor I?B families are the key regulators of diverse array of cell signaling pathways that have profound impact on cell physiology, in particular, immuno-modulation, survival and proliferation of cell. NF-?B1 (also called p105/p50) and NF-?B2 (also called p100/p52) belong to both the NF-?B and I?B families. p105 and p100 are the precursors which processed into smaller products, p50 and p52, members of the NF-?B family. Precursors function as inhibitors of NF-?B, including their own processed products. Processing must be tightly regulated to generate appropriate ratio of unprocessed and processed forms. Many human diseases, such as autoimmune diseases and cancer, are linked to unregulated processing of p100 and p105. p105 and p100 divulge highly complex regulatory events in the NF-?B signaling module by generating all of NF-?B p50 and p52 proteins and inhibiting nearly half of all five NF-?B proteins. Like the prototypical I?B inhibitors, I?B?,-? and -?, p105 and p100 inhibitors also undergo complete degradation releasing NF-?B transcription factors. However, complete degradation events are difficult to observe in the backdrop of the processing events and thus are less appreciated. Processing of p105 is constitutive whereas that of p100 is inducible. This proposal aims to study the biochemical mechanisms of processing and complete degradation and coupling between these two events. Our hypothesis, derived from our preliminary results and published reports, is that the fundamental regulation of processing or lack of it is guided by several competing inter- and intra-domain interactions in p105 and p100, and these interactions can be altered by signaling. We propose that p105-self interaction induces a structural state that is conducive to constitutive processing whereas p100 attains that state only through signaling. We further propose that as the fully assembled NF-?B inhibitory complexes, the processing sites of p105 and p100 are masked. p105 and p100 in these assembled complexes must undergo complete degradation by cell signaling to liberate bound NF-?B. We will test our hypothesis by i) determining the three-dimensional structures of p105/p100 bound to NF-?B using x- ray crystallography, ii) identifying interaction strategies and energies of the p105/p100:NF-?B complexes, and finally, iii) studying the processing and degradation of the precursors. PUBLIC HEALTH RELEVANCE: Our proposed research has the potential to unravel the long-standing question of how the two NF-kappaB precursor proteins carry out dual functions both as transcription factors and inhibitors of NF-kB. Misregulation of both these proteins are strongly linked to auto-immune diseases and cancer. Current therapy against multiple myeloma function as an inhibitor of aberrant NF-kB activation. Our work will play a major role identifying new and better inhibitors.