IFNAR1 signaling through STAT3, PI-3 kinase and NFkB

描述(申请人提供)：当人们考虑干扰素对癌症、病毒性肝炎和多发性硬化症的治疗潜力，以及它作为了解细胞因子信号转导的模型的作用时，了解干扰素-α(IFNpha)作用的分子基础是一个重要的目标。通过酪氨酸磷酸化和STAT(信号转导和转录激活因子)蛋白家族成员的激活，IFNα通过调节基因表达来发挥其生物学作用。申请人发现，STAT3是急性时相反应基因的转录因子，是干扰素信号转导和诱导干扰素生物学作用的关键元件。此外，研究还发现，干扰素通过参与PI-3K(磷脂酰肌醇-3‘-激酶)、Akt和STAT3的丝氨酸激酶依赖途径激活核因子-kB，从而促进细胞存活。基于这些发现，需要检验的一般假设是，IFNpha受体整合了涉及STAT3、PI-3K和NF-kB的信号通路。在特定的目标1中，将定义STAT3作为转录因子和PI-3K的适配蛋白的作用。这些研究将确定STAT3中哪些特定的氨基酸残基发生干扰素依赖的磷酸化，这些磷酸化事件与干扰素的生物学作用的关系，以及哪些干扰素反应基因受到STAT3的调控。在具体目标2中，将确定核因子-kB在IFNA行动中的作用。这些研究将确定PI-3K/Akt介导的磷酸化事件与干扰素的抗凋亡作用的关系，TRAF(肿瘤坏死因子受体相关因子)和NIK(核因子-kB诱导激酶)在IFN诱导的核因子-kB激活中的作用，核因子-kB在干扰素诱导的基因诱导中的作用，以及IKB激酶复合体在干扰素促进核因子-kB激活和细胞存活中的作用。尽管在IFNpha信号通路方面取得了进展，但其诱导不同生物学作用的机制仍然知之甚少。这项建议侧重于表征信号通路的分子基础，因为它们与干扰素对细胞增殖和生存的作用有关。

DESCRIPTION (provided by applicant): Understanding the molecular basis of interferon-alpha (IFNalpha) action is an important goal when one considers IFN's therapeutic potential in cancer, viral hepatitis, and multiple sclerosis, as well as its role as a model for understanding cytokine signal transduction. IFNalpha elicits its biological actions by regulating gene expression through the tyrosine phosphorylation and activation of members of the STAT (signal transducers and activators of transcription) protein family. The applicant found that STAT3, a transcription factor for acute phase response genes, is a critical element in IFN signaling and induction of IFN's biological actions. In addition, it was also found that IFN promotes cell survival by activating NF-kB (nuclear factor-kB) through a serine kinase-dependent pathway involving PI-3K (phosphatidylinositol-3' kinase) and Akt, as well as STAT3. Based on these findings, the general hypothesis to be tested is that the IFNalpha receptor integrates signaling pathways involving STAT3, PI-3K and NF-kB. In Specific Aim 1, the role of STAT3 as a transcription factor and an adapter protein for PI-3K will be defined. The proposed studies will determine which specific amino acid residues in STAT3 undergo IFN-dependent phosphorylation, the relationship of these phosphorylation events to the biologic actions of IFN, and which IFN-responsive genes are STAT3- regulated. In Specific Aim 2, the role of NF-kB in IFNa action will be defined. The proposed studies will define the relationship between PI-3K/Akt-mediated phosphorylation events and the anti-apoptotic action of IFN, the roles of TRAFs (TNF receptor-associated factors) and NIK (NF-kB-inducing kinase) in IFNinduced NF-kB activation, the role of NF-kB in gene induction by IFN, and the role of the IkB kinase complex in IFN promoted NF-kB activation and cell survival. Despite advances made on the IFNalpha signaling pathway, the mechanisms that underlie the induction of the different biological actions of IFNalpha remain poorly understood. This proposal focuses on characterizing the molecular basis of signaling pathways as they relate to IFN action on cell proliferation and survival.