Regulation of TRAF2 Activity in Normal and Tumor Cells

TRAF2是一个关键的接头蛋白，调节IKK、JNK和p38信号通路，以响应 细胞因子和应激，导致关键转录因子AP-1和NF-kB的激活。人类肿瘤 通常表现为TRAF2表达升高或定位改变，导致结构性IKK 激活并增强对应激诱导的细胞凋亡的抵抗力。实现这一目标的机制 TRAF2在癌细胞中的稳定性和活性的解除调控仍然难以捉摸。在早期的研究中，我们证明了 Siah2在共振应激刺激中调节TRAF2稳定性的作用我们还证明了 TRAF2的S自身的环依赖泛素化诱导其移位到膜筏和伴随物 激活JNK，但不激活IKK。然而，TRAF2调控的分子机制 人们对这一活动的理解还远远不够。我们定位了TNFa诱导和Akt/PKC介导的TRAF2 磷酸化位点。重要的是，TRAF2在环指区域内的磷酸化是必需的 TRAF2介导的IKK激活，而TRAF结构域内的磷酸化被发现是重要的 用于限制TNFa诱导的IKK激活。这些发现为我们的假设提供了基础 TRAF2介导的信号转导受到翻译后磷酸化的严格调控。就在这一秒 我们将着重于Akt/PKC介导的TRAF2的磷酸化，并阐明其生理和 TRAF2介导的多种信号通路激活的病理生理学意义 建议实现以下具体目标：1.描述新确定的 TRAF2磷酸化调节TNFa诱导和TRAF2介导的JNK和NF-kB活化 小路。2.评估Akt和PKC在TRAF2和TRAF2介导的磷酸化中的作用 JNK和NF-kB信号通路的激活。3.明确Akt和PKC之间的关系 TRAF2的磷酸化与应激诱导的细胞死亡。AIM-4。评估其病理生理学相关性 TRAF2磷酸化在黑色素瘤细胞抵抗应激诱导细胞死亡中的作用。我们的工作将会有新的进展 PKC和Akt对TRAF2磷酸化的调节及其在肿瘤细胞调控中的作用 抵抗应激诱导的细胞死亡。

TRAF2 is a key adaptor protein that regulates the IKK, JNK and p38 signaling pathways in response to cytokines and stress, leading to activation of the critical transcription factors AP-1 and NF-kB. Human tumors often exhibit either elevated expression or altered localization of TRAF2, resulting in constitutive IKK activation and increased resistance to stress-induced apoptosis. The mechanism that brings about such deregulation of TRAF2 stability and activity in cancer cells is still elusive. In earlier studies we demonstrated the role of Siah2 in regulating TRAF2 stability in resonse to stress stimulation. We also demonstratedthat TRAF2's own RING-dependent ubiquitination induces its translocation to membrane rafts and concomitant activation of JNK, but not of IKK. However, the molecular mechanism underlying the regulation of TRAF2 activity is far from being understood. We mapped TNFa-induced and Akt/PKC-mediated TRAF2 phosphorylation sites. Importantly, TRAF2 phosphorylation within the RING finger domain is required for TRAF2-mediated activation of IKK, whereas phosphorylation within the TRAF domain was found important for limiting TNFa-induced IKK activation. These findings provide the foundation to our hypothesis that TRAF2-mediated signaling is tightly regulated by a post-translational phosphorylation. In this second revision, we will focus on Akt/PKC-mediated TRAF2 phosphorylation and elucidate its physiological and pathophysiological significance in TRAF2-mediated activation of diverse signaling pathways, with which we propose to carry out the following specific aims: 1. Characterize the mechanism by which newly identified TRAF2 phosphorylation regulates TNFa-induced and TRAF2-mediated activation of the JNK and NF-kB pathways. 2. Assess the role of Akt and PKC in the phosphorylation of TRAF2 and TRAF2-mediated activation of the JNK and NF-kB pathways. 3. Define the relationship between Akt- and PKC-mediated TRAF2 phosphorylation and stress-induced cell death. Aim-4. Assess the pathophysiological relevance of TRAF2 phosphorylation in melanoma cell resistance to stress-induced cell death. Our work will shed new light on the regulation of TRAF2 phosphorylation by PKC and Akt and their role in the regulation of tumor cell resistance to stress-induced cell death.