Two novel threonine phosphorylations of STAT2 impact inflammatory responses to bacterial infection.

项目摘要 驱动对I型干扰素(干扰素-I)反应的主要转录因子是ISGF3，由酪氨酸- 磷酸化的STAT1和STAT2以及DNA结合蛋白IRF9。T387上STAT2的苏氨酸磷酸化 和T404深刻影响干扰素-I驱动基因表达和依赖的生物学功能的能力。 此外，缺乏酪氨酸磷酸化的STAT2(U-STAT2)增强了NF-κB靶基因的表达 它编码几种趋化因子和促炎细胞因子(例如，IL-6)，并抑制 干扰素-γ激活STAT1的酪氨酸磷酸化及下游基因表达。这些非规范的 U-STAT2的功能也受其在T387和T404上的磷酸化的调节。戏剧性的效果是通过 在这两个位点都携带纯合子T-A突变的小鼠。T403A小鼠对干扰素-I的缺陷反应 使他们对水疱性口炎病毒(VSV)或单纯疱疹病毒(HSV)感染高度敏感。 (老鼠的号码是T386和T403。)T403A小鼠对炎症刺激的反应也很大 妥协了。溃疡性结肠炎是一种慢性疾病，结肠内层发炎并发展。 溃疡。在葡聚糖硫酸钠(DSS)诱导的溃疡性结肠炎模型上，T403A/T403A敲门小鼠，其中 这个位点不能被磷酸化，比WT/WT小鼠对DSS诱导的死亡和 减肥。败血症和感染性休克是非冠脉重症监护病房的主要死亡原因。我们有 研究表明，脓毒症的免疫反应从早期/高炎症转变为晚期/低炎症， 与多器官功能障碍相关的免疫抑制表型，涉及肺、心、肾和 肝脏。此外，长期的低炎症与病原体清除受损有关。与野性相比- 类型对照组，T403A/T403A小鼠被保护，T386A/T386A小鼠被致敏 内毒素是感染性休克的诱导剂，其诱导的干扰素-I和IL-6的表达受到抑制。 T403A/T403A小鼠。我们的主要目标如下。1)我们想详细了解磷酸化是如何 这两个苏氨酸残基上的STAT2是受调控的(哪些激活信号？哪种蛋白水解酶？哪一个 磷酸酶？)。2)我们想详细了解STAT2如何影响促炎机制 苏氨酸磷酸化。3)我们希望利用这些信息开发新的治疗方法 对共生细菌的炎症反应，尤其是结肠炎和败血症休克。我们 期待我们能够更好地理解STAT2的苏氨酸磷酸化在 炎症和感染转化为新的治疗方法，以及发现新的治疗方法 改善细菌引起的急性炎症对其他炎症情况也有帮助。

Project Summary The major transcription factor that drives responses to type I interferon (IFN-I) is ISGF3, comprised of tyrosine- phosphorylated STATs 1 and 2 and the DNA binding protein IRF9. The threonine phosphorylation of STAT2 on T387 and T404 profoundly affects the ability of IFN-I to drive gene expression and dependent biological functions. Furthermore, STAT2 lacking tyrosine phosphorylation (U-STAT2) enhances the expression of NF-κB target genes that encode several chemokines and pro-inflammatory cytokines (for example, IL-6), and also inhibits the ability of IFN-γ to activate the tyrosine phosphorylation of STAT1 and downstream gene expression. These non-canonical functions of U-STAT2 are also regulated by its phosphorylation on T387 and T404. Dramatic effects are seen with mice carrying homozygous T-A mutations at each of these two sites. The defective response to IFN-I in T403A mice causes them to be highly susceptible to infections with vesicular stomatitis virus (VSV) or Herpes Simplex virus (HSV). (The numbers for mice are T386 and T403.) The responses of T403A mice to inflammatory stimuli are also greatly compromised. Ulcerative colitis is a chronic disease in which the lining of the colon becomes inflamed and develops ulcers. In the dextran sulfate sodium (DSS)-induced model of ulcerative colitis, T403A/T403A knockin mice, in which this site cannot be phosphorylated, are very much more sensitive than WT/WT mice to DSS-induced mortality and weight loss. Sepsis and septic shock are the leading causes of death in non-coronary intensive care units. We have shown that the immune response in sepsis transitions from an early/hyper-inflammatory to a late/hypo-inflammatory, immunosuppressive phenotype that is associated with multiple organ dysfunction involving lung, heart, kidney and liver. Furthermore, prolonged hypo-inflammation is associated with impaired pathogen clearance. Compared with wild- type controls, T403A/T403A mice are protected from, and T386A/T386A mice are sensitized to challenge with lipopolysaccharide (LPS), an inducer of septic shock, and the induction of IFN-I and IL-6 expression is suppressed in T403A/T403A mice. Our primary objectives follow. 1) We want to understand in detail how the phosphorylation of STAT2 on these two threonine residues is regulated (which activating signals? which kinases? which phosphatases?). 2) We want to understand in detail how pro-inflammatory mechanisms are affected by STAT2 threonine phosphorylation. 3) We want to use this information to develop novel therapeutic approaches to inflammatory responses to commensal bacteria, especially colonic inflammation and septic shock. We anticipate that we can parlay improved understanding of the roles of threonine phosphorylation of STAT2 in inflammation and infection into novel therapeutic approaches, and that the discovery of novel approaches to ameliorate bacterially-induced acute inflammation may also be helpful in other inflammatory conditions.