NF-kB regulation by p105 and p100

描述（由申请人提供）：转录因子NF-κB和i -κB抑制剂家族成员是多种细胞信号通路的关键调节因子，对细胞生理，特别是免疫调节，细胞存活和增殖具有深远的影响。NF-κB1（也称为p105/p50）和NF-κB2（也称为p100/p52）属于NF-κB和i -κB家族。p105和p100是加工成更小的产物p50和p52的前体，是NF-κB家族的成员。前体具有NF-κB抑制剂的功能，包括它们自身的加工产物。加工必须严格规范，以产生适当比例的未加工和加工的形式。许多人类疾病，如自身免疫性疾病和癌症，都与p100和p105不受控制的加工有关。p105和p100通过产生所有NF-κB p50和p52蛋白并抑制所有5种NF-κB蛋白的近一半，揭示NF-κB信号传导模块中高度复杂的调控事件。与典型的i -κB抑制剂、i -κB α、- β和- ε一样，p105和p100抑制剂也会完全降解，释放NF-κB转录因子。然而，在处理事件的背景下很难观察到完全的降解事件，因此不太受重视。p105的加工是本构性的，而p100的加工是诱导性的。本课题旨在研究加工、完全降解和两者耦合的生化机制。根据我们的初步结果和发表的报告，我们的假设是，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传导改变。我们认为p105-自相互作用诱导了一种有利于本构加工的结构状态，而p100仅通过信号传导才能达到这种状态。我们进一步提出，作为完全组装的NF-κB抑制复合物，p105和p100的加工位点被掩盖。这些组装的复合物中的p105和p100必须经过细胞信号的完全降解才能释放结合的NF-κB。我们将通过以下方法来验证我们的假设：i)利用x射线晶体学确定p105/p100与NF-κ b结合的三维结构，ii)确定p105/p100与NF-κ b复合物的相互作用策略和能量，最后，iii)研究前体的加工和降解。

DESCRIPTION (provided by applicant): Members of the transcription factor NF-κB and inhibitor IκB 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-κB1 (also called p105/p50) and NF-κB2 (also called p100/p52) belong to both the NF-κB and IκB families. p105 and p100 are the precursors which processed into smaller products, p50 and p52, members of the NF-κB family. Precursors function as inhibitors of NF-κB, 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-κB signaling module by generating all of NF-κB p50 and p52 proteins and inhibiting nearly half of all five NF-κB proteins. Like the prototypical IκB inhibitors, IκBα,-ß and -ϵ, p105 and p100 inhibitors also undergo complete degradation releasing NF-κB 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-κB 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-κB. We will test our hypothesis by i) determining the three-dimensional structures of p105/p100 bound to NF-κB using x- ray crystallography, ii) identifying interaction strategies and energies of the p105/p100:NF-κB complexes, and finally, iii) studying the processing and degradation of the precursors.