Ubiquitin-Mediated Activation of the IkB Kinase Complex

描述(申请人提供)：转录因子NF-kappaB为 主要通过与抑制蛋白的结合来调节 IkappaB。核因子-kappaB/IkappaB复合体通常隔离在细胞质中 直到细胞被白介素1(IL-1)、肿瘤等激动剂刺激 肿瘤坏死因子(TNF)和脂多糖(LPS)。在刺激的时候 细胞，IkappaB被IkappaB激酶复合体(IKK)迅速磷酸化，并且 然后被泛素-蛋白酶体途径降解。1kappaB的降解 允许核因子-kappaB进入细胞核以启动下游基因，许多 它们在细胞的生死中起着关键作用。 核因子-kappaB信号通路中的一个关键步骤是IkappaB的磷酸化 在IKK建筑群旁边。该激酶复合体整合了来自多个 途径包括由IL-1和内毒素产生的途径。遗传学研究已经 证明了TRAF6，一种环指结构域蛋白，以及 IKK复合体是IL-1和内毒素诱导的核因子-kappaB活化所必需的。 然而，尚不清楚TRAF6是如何激活IKK的。世界银行最近的研究 首席研究员的实验室表明，IKK的激活 TRAF6的复合体需要二聚体泛素结合酶复合体， UBC13/Uev1A，并形成一条独特的多泛素链 泛素的赖氨酸-63(K63)。这项建议的目标是了解 泛素依赖的IKK复合体激活的新机制。 具体地说，实验是为了1)研究其结构和功能 与IKK激活相关的Ubcl3/Uev1a和TRAF6；2)鉴定和 描述TKAF6激活IKK所需的其他因素，包括 泛素化靶标；3)鉴定和鉴定K63 多泛素链结合蛋白；4)探讨其作用机制。 TRAF6依赖泛素激活IKK。总而言之，这些研究 应该填补核因子-kappaB信号通路中的显著空白，并提供 解开IKB之谜所需的重要片段 泛素激活的激酶。鉴于核因子-kappaB在人类中的重要性 疾病，从拟议的研究中获得的信息将是直接的 与生物医学的相关性，包括发现新的治疗靶点。

DESCRIPTION (provided by applicant): The transcription factor NF-kappaB is regulated primarily through its association with the inhibitory protein IkappaB. The NF-kappaB/IkappaB complex is normally sequestered in the cytoplasm until cells are stimulated with an agonist such as interleukin-1 (IL-1), tumor necrosis factor (TNF), and lipopolysaccharides (LPS). Upon stimulation of cells, IkappaB is rapidly phosphorylated by an IkappaB kinase complex (IKK) and then degraded by the ubiquitin-proteasome pathway. The degradation of 1kappaB allows NF-kappaB to enter the nucleus to turn on downstream genes, many of which play pivotal roles in the life and death of cells. A key step in the NF-kappaB signaling pathway is the phosphorylation of IkappaB by the IKK complex. This kinase complex integrates signals from multiple pathways including those emanating from IL-1 and LPS. Genetics studies have demonstrated that TRAF6, a RING finger domain protein, and components of the IKK complex are essential for NF-kappaB activation in response to IL-1 and LPS. However, it is not known how TRAF6 activates IKK. Recent studies by the principal investigator's laboratory have shown that the activation of IKK complex by TRAF6 requires a dimeric ubiquitin conjugating enzyme complex, Ubc13/Uev1A, and the formation of a unique polyubiquitin chain linked through lysine-63 (K63) of ubiquitin. The goal of this proposal is to understand the novel mechanisms of ubiquitin-dependent activation of the IKK complex. Specifically, experiments are proposed to 1) study the structure and function of Ubcl3/Uev1A and TRAF6 as related to IKK activation; 2) identify and characterize additional factors required for IKK activation by TKAF6, including the ubiquitination target; 3) identify and characterize the K63-linked polyubiquitin chain binding protein; 4) investigate the mechanisms of ubiquitin-dependent activation of IKK by TRAF6. Taken together, these studies should fill significant gaps in the NF-kappaB signaling pathway, and provide the important pieces that together are required to solve the puzzle of IKB kinase activation by ubiquitin. Given the importance of NF-kappaB in human diseases, information gained from the proposed studies will be of direct relevance to biomedicine, including discovery of novel therapeutic targets.