Regulation of TRAF2 Activity in Normal and Tumor Cells

正常细胞和肿瘤细胞中 TRAF2 活性的调节

• 批准号: 7034445
• 负责人: HASEM HABELHAH
• 金额: $ 20.95万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-02-17 至 2010-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7034445
• 关键词: DNA binding protein; JUN kinase; RNA interference; antiantibody; apoptosis; binding proteins; biological signal transduction; cell line; melanoma; neoplastic cell; nuclear factor kappa beta; nuclear proteins; phosphorylation; protein degradation; protein kinase C; protein structure function; tumor necrosis factor alpha

DESCRIPTION (provided by applicant): 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 response to stress stimulation. We also demonstrated that 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.

描述（由申请人提供）：TRAF2是一种关键衔接蛋白，可响应细胞因子和应力，调节IKK，JNK和P38信号通路，从而激活关键转录因子AP-1和NF-KB。人类肿瘤通常表现出升高的表达或改变TRAF2的定位，从而导致构型IKK激活并增加对应激诱导的凋亡的抗性。癌细胞中TRAF2稳定性和活性导致这种失调的机制仍然难以捉摸。在较早的研究中，我们证明了SIAH2在调节TRAF2稳定性方面的作用，以应对应力刺激。我们还证明了TRAF2自己的环依赖性泛素化诱导其转移到膜筏和JNK的同时激活，但不是IKK的激活。但是，TRAF2活性调节的基础机制远非被理解。我们绘制了TNFA诱导的和AKT/PKC介导的TRAF2磷酸化位点。重要的是，TRAF2介导的IKK激活需要环手指结构域内的TRAF2磷酸化，而TRAF结构域内的磷酸化对于限制TNFA诱导的IKK激活很重要。这些发现为我们的假设奠定了基础，即Traf2介导的信号传导受翻译后磷酸化的严格调节。 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和NF-KB途径。 2。评估AKT和PKC在JNK和NF-KB途径的TRAF2和TRAF2介导的激活中的作用。 3。定义AKT和PKC介导的TRAF2磷酸化与应力诱导的细胞死亡之间的关系。 AIM-4。评估TRAF2磷酸化在黑色素瘤细胞抗应激诱导的细胞死亡中的病理生理相关性。我们的工作将为PKC和AKT对TRAF2磷酸化的调节及其在调节肿瘤细胞抗应激诱导的细胞死亡的耐药性中的作用提供新的启示。