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

DNA损伤抗癌剂，包括电离辐射（IR）激活NF-κ B，已成为恶性细胞行为的重要调节因子，如对凋亡细胞死亡的抵抗。这一信号转导途径也可作为理解核DNA损伤如何诱导核-胞质信号转导途径的范例。我们以前发现了一种新的核质NF-κ B信号通路诱导IR和其他代理，可以诱导DNA双链断裂（DSB）。该信号通路涉及SUMO-1（小泛素样修饰物1）对NEMO（NF-κ B必需调节物）/IKK 3（I：B激酶（IKK）复合物的调节亚基）的翻译后修饰（PTM）。我们现在产生了一种新的Nemo[DK]敲入小鼠，其具有sumoylation位点的种系突变。在目前的建议中，我们将通过直接评估NEMO类小泛素化在体内的作用，并进一步剖析关键的上游和下游机制，建立这种新的NF-κ B信号通路在IR反应中的生理重要性。以下三个目标将解决我们的中心假设，即NEMO类小泛素化在介导NF-κ B活化中起着关键的生理作用，通过IR来调节体内辐射敏感性：目的1：确定NEMO类小泛素化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类小泛素化中的上游作用。目标3.阐明SUMO-1对NEMO功能的特异性下游调控。我们认为，这项研究之所以重要，主要有两个原因。首先，所描述的研究将揭示新的NF-κ B信号转导机制响应DNA损伤刺激。其次，了解DNA损伤剂激活NF-κ B的机制可能有助于确定新的药物靶点，以改善目前的癌症治疗方法。

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.