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: 7187428
• 负责人: HASEM HABELHAH
• 金额: $ 20.34万
• 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 2009-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7187428
• 关键词: Abbreviations; Adaptor Signaling Protein; Antibodies; Apoptosis; Appendix; Binding; C-terminal; Cell Death; Cells; Condition; Doctor of Philosophy; Exhibits; Fingers; Foundations; Human; Hydrogen Peroxide; Ink; Light; MAPK14 gene; MAPK8 gene; Maps; Mediating; Melanoma Cell; Membrane; Molecular; N-terminal; NF-kappa B; Nature; Pathway interactions; Phosphorylation; Phosphorylation Site; Physiological; RNA Interference; Regulation; Resistance; Role; Serine Phosphorylation Site; Signal Pathway; Signal Transduction; Site; Stress; TNF receptor-associated factor 2; TRAF Domain; TRAF2 gene; Technology; Transcription Factor AP-1; Tumor Necrosis Factor Receptor; Ubiquitination; Work; cancer cell; cytokine; in vivo; neoplastic cell; response; tumor; ubiquitin-protein ligase

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）：TRAF 2是一种关键衔接蛋白，其调节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-κ B的激活。人类肿瘤通常表现出TRAF 2的表达升高或定位改变，导致组成性IKK激活和对应激诱导的细胞凋亡的抗性增加。导致癌细胞中TRAF 2稳定性和活性失调的机制仍然难以捉摸。在早期的研究中，我们证明了Siah 2在调节TRAF 2稳定性以响应应激刺激中的作用。我们还证明了TRAF 2自身的RING依赖性泛素化诱导其易位到膜筏，并伴随JNK的激活，但不诱导IKK的激活。然而，TRAF 2活性调节的分子机制还远未被理解。我们绘制了TNF α诱导的和Akt/PKC介导的TRAF 2磷酸化位点。重要的是，TRAF 2环指结构域内的TRAF 2磷酸化是TRAF 2介导的IKK激活所必需的，而TRAF结构域内的磷酸化被发现对限制TNF α诱导的IKK激活很重要。这些发现为我们的假设提供了基础，即TRAF 2介导的信号转导受到翻译后磷酸化的严格调控。在第二次修订中，我们将重点关注Akt/PKC介导的TRAF 2磷酸化，并阐明其在TRAF 2介导的多种信号通路激活中的生理和病理生理意义，我们提出了以下具体目标：1.描述新发现的TRAF 2磷酸化调节TNF α诱导和TRAF 2介导的JNK和NF-κ B通路激活的机制。2.评估Akt和PKC在TRAF 2磷酸化和TRAF 2介导的JNK和NF-kB通路激活中的作用。3.确定Akt和PKC介导的TRAF 2磷酸化和应激诱导的细胞死亡之间的关系。目标四评估TRAF 2磷酸化在黑色素瘤细胞对应激诱导的细胞死亡的抵抗中的病理生理学相关性。我们的工作将为PKC和Akt对TRAF 2磷酸化的调节以及它们在调节肿瘤细胞抵抗应激诱导的细胞死亡中的作用提供新的线索。