Regulation of NEMO modifications in radiation-induced NF-kB signaling

包括电离辐射（IR）在内的dna损伤抗癌药物激活NF-kB，已成为恶性细胞行为（如对凋亡细胞死亡的抵抗）的重要调节剂。这种信号转导途径也可以作为理解核DNA损伤如何诱导核-胞质信号转导途径的范例。我们之前已经发现了一种新的由IR和其他可以诱导DNA双链断裂（DSBs）的药物诱导的核到细胞质NF-kB信号通路。该信号通路涉及到I:B激酶（IKK）复合体的调控亚基NEMO （NF-kB必需调节剂）/IKK3被SUMO-1（小泛素样调节剂1）的翻译后修饰（PTM）。我们现在培育了一种新的Nemo[DK]敲入小鼠，这种小鼠携带了sumoylation位点的种系突变。在目前的提案中，我们将通过直接评估NEMO summoylation在体内的作用来确定这种新的NF-kB信号通路在响应IR中的生理重要性，并进一步剖析其关键的上游和下游机制。以下三个目标将解决我们的中心假设，即NEMO summoylation在通过IR介导NF-kB激活以调节体内辐射敏感性方面发挥关键的生理作用：目标1：确定NEMO summoylation在调节体内辐射敏感性中的作用。目的2：揭示NEMO锌指在促进NEMO酰化中的上游作用。目标3。阐明SUMO-1对NEMO功能的特异性下游调控。我们认为，提出的研究很重要，主要有两个原因。首先，所描述的研究将揭示新的NF-kB信号转导机制，以响应DNA损伤刺激。其次，了解DNA损伤剂激活NF-kB的机制可能有助于确定新的药物靶点，以改进当前的癌症治疗方法。

Activation of NF-kB by DNA-damaging anticancer agents, including ionizing radiation (IR), has emerged as an important modulator of malignant cell behaviors, such as resistance to apoptotic cell death. This signal transduction pathway also serves as a paradigm to understand how nuclear DNA damage may induce nucleus-to-cytoplasmic signal transduction pathways. We have previously discovered a novel nucleus-to-cytoplasmic NF-kB signaling pathway induced by IR and other agents that can induce DNA double strand breaks (DSBs). This signaling pathway involves a post-translational modification (PTM) of NEMO (NF-kB essential modulator)/IKK3, the regulatory subunit of the I:B kinase (IKK) complex, by SUMO-1 (small ubiquitin-like modifier 1). We now generated a novel Nemo[DK] knockin mice harboring a germ-line mutation of the sumoylation sites. In the current proposal, we will establish the physiological importance of this new NF-kB signaling pathway in response to IR by directly evaluating the role of NEMO sumoylation in vivo and further dissect the critical upstream and downstream mechanisms. The following three aims will address our central hypothesis that NEMO sumoylation plays a critical physiological role in mediating NF-kB activation by IR to modulate radiation sensitivity in vivo: Aim 1: Determine the roles of NEMO sumoylation in modulating radiation sensitivity in vivo. Aim 2: Reveal the upstream role of NEMO zinc finger in promoting NEMO sumoylation. Aim 3. Elucidate SUMO-1 specific downstream regulation of NEMO function. We believe that the proposed research is important for two major reasons. First, the described research will uncover novel NF-kB signal transduction mechanisms in response to DNA damage stimuli. Second, understanding the mechanisms of NF-kB activation by DNA damaging agents may help identify novel drug targets to improve the current methods of cancer therapy.