Novel roles of IKK complex to program gene expression

诱导IKK信号复合体的核因子-kappaB是一系列细胞外应激样和炎症反应刺激的最终接受者和整合者。IKK复合体由两个丝氨酸苏氨酸激酶(IKKalpha和IKKbeta)和一个共催化调节/对接蛋白(Nemo/Ikky)组成。IKK(3)和Nemo/IKKGamma是在炎症反应的介质如TNFpha和IL-1的作用下诱导NF-KB核转位和DNA结合活性所必需的，而IKKalpha被认为是通过这些刺激激活NF-kappaB所必需的。令人惊讶的是，我们最近发现IKKalpha对于诱导 核因子-kappaB亚基对炎性细胞因子的转录能力，这意味着它在激活核因子-kB中发挥着关键作用，而不依赖于其DNA结合活性。因此，这项建议的目的之一将是阐述IKKalpha作为最终导致NF-kappaB激活的应激样反应的共同全局介体(与IKKbeta和Nemo/IKKGamma一起)的分子要求和作用机制。 我们还发现，IKK信号体同时协调细胞基因表达的全球诱导和抑制。在第二个目标中，我们将阐述IKK信号体作为依赖于NF-kappaB的基因抑制的中介的作用机制。我们假设IKK介导的核因子-kappaB的激活就像一个协调控制的开/关开关，改变了体内的生理反应。有趣的是，这些基因的一个子集也是E2F-I的诱导靶点，这些基因在细胞外刺激依赖和IKK介导的NF-KB激活时被抑制。E2F-1能够诱导细胞周期停滞、凋亡和细胞周期进展，这取决于它的程度。 细胞的激活和生理状态。将在原代和已建立的细胞中建立实验条件，从而导致核因子-KB和E2F在特定基因组靶点上的干扰。还将评估IKK/NF-kappaB介导的抑制细胞周期调控的E2F靶基因的生理效应。

The NF-KappaB inducing IKK signalsome complex is the final receiver and integrator of a host of extracellular stress-like and inflammatory response stimuli. The IKK complex consists of two serinelthreonine kinases (IKKalpha and IKKbeta) and a con-catalytic regulatory/docking protein (NEMO/IKKy). IKK(3 and NEMO/IKKgamma are essential for inducing NF-KB nuclear translocation and DNA binding activity in response to mediators of inflammatory responses like TNFalpha and IL-1, while IKKalpha is largely believed to be dispensible for activating NF-KappaB by these stimuli. Surprisingly, we have recently found that IKKalpha is essential for inducing the transcriptional competence of nuclear NF-KappaB subunits in response to inflammatory cytokines, implying that it plays a critical role in activating NF-KB independent of its DNA binding activity. Consequently, one aim of this proposal will be to elaborate the molecular requirements and mechanisms of action of IKKalpha as a co-global mediator (along with IKKbeta and NEMO/IKKgamma) of stress-like responses culminating in NF-kappaB activation. We have also discovered that the IKK signalsome simultaneously co-ordinates the global induction and repression of cellular gene expression. In a second aim we will elaborate the mechanisms of action of the IKK signalsome as a mediator of NF-KappaB dependent gene repression. We have hypothesized that IKK mediated NF-KappaB activation operates like a co-ordinately controlled on/off switch that alters physiological responses in vivo. Interestingly a subset of the genes, which are repressed in response to extracellular stimulus dependent and IKK mediated NF-KB activation, are also induced targets of the E2F-I. E2F-1 is capable of inducing cell cycle arrest, apoptosis and cell cycle progression depending on its degree of activation and the physiological state of the cell. Experimental conditions in primary and established cells will be established, which lead to interference between NF-KB and E2F on specific genomic targets. The physiological effects of IKK/NF-KappaB mediated repression of cell cycle regulated, E2F target genes will also be evaluated.