Acetylation-Dependent IFN Signal Transduction

I型干扰素影响几乎所有种类的细胞分化、增殖和存活 的细胞类型，并有效治疗恶性肿瘤，如慢性 粒细胞白血病近年来，干扰素用于实体瘤化疗的应用 受到了相当大的关注。IFN-γ激活的STAT 2、STAT 1和IRF 9形成 转录因子IFN-刺激的基因因子-3（ISGF 3）复合物，其结合 干扰素刺激应答元件（ISRE）序列用于转录激活。 干扰素激活的STAT蛋白也形成同或异二聚体， 元件（SIE）来调节基因表达。干扰素受体（IFN R）由两个同源 亚基：IFN <$R1和IFN <$R2。IFN结合IFN R2以促使其结合 IFN R1 IFN <$R1和IFN <$R2通过其相关的 酪氨酸激酶（Jak 1和Tyk 2），随后是STAT 2和STAT 1 募集和磷酸化激活。IFN激活的机制 IRF 9未知。IRF 9依赖性转录激活可以通过治疗增强。 用去乙酰化酶抑制剂处理细胞，表明IRF 9的激活涉及乙酰化。我们 通过募集肿瘤抑制因子样转录辅因子检测IFN <$R2乙酰化 CREB结合蛋白（CBP）或其同源p300。乙酰化IFN R 2可以 招募IRF 9。IRF 9以及STAT 2和STAT 1都在 形成转录活性ISGF 3复合物。干扰素R也招募脱乙酰酶 包括SIRT和HDAC成员。虽然酪氨酸磷酸化长期以来一直是 我们的研究发现， 基于初步数据和蛋白质二级结构分析， 概念.这里要检验的首要假设是CBP/p300介导的 由IFN？引发的乙酰化级联反应在信号转导中起着不可或缺的作用 用于抗增殖、促细胞凋亡和抗转移基因调节。干扰素R 和脱乙酰酶与脱乙酰酶抑制剂的联合可以改善治疗效果。 干扰素在癌症中的作用我们将应用定点突变，FRET技术，作为 以及我们实验室开发的抗体阵列技术，以便（1）定义 乙酰转移酶活性与CBP/p300对细胞内IFN？R活化相关 （2）通过HDAC或SIRT分析IFN R、STAT 1和ISGF 3的脱乙酰化， 信号终止;和（3）确定乙酰化STAT 1二聚体或ISGF 3 复合物对于IFN？介导的抗增殖、促凋亡和抗转移至关重要 癌细胞的基因调控。这些方法将有助于阐明 乙酰化和去乙酰化在调节IFN R活化，STAT二聚体，和 ISGF 3复合物形成的信号转导和转录，并允许我们 最大限度地发挥干扰素对癌症的治疗作用。

Type I interferon (v affect cell differentiation, proliferation, and survival in nearly all kinds of cell types, and are efficacious in the treatment of malignancies such as chronic myeloid leukemia. In recent years, the usage of IFN¿ for solid cancer chemotherapy has received considerable attention. IFN¿-activated STAT2, STAT1, and IRF9 form the transcription factor IFN-stimulated gene factor-3 (ISGF3) complex, which binds to interferon stimulated response element (ISRE) sequence for transcriptional activation. IFN¿ activated STAT proteins also form homo- or hetero-dimer that bind to sis-inducible element (SIE) to regulate gene expression. IFN¿ receptor (IFN¿R) consist two cognate subunits: IFN¿R1 and IFN¿R2. IFN¿ binds IFN¿R2 to instigate its association with IFN¿R1. IFN¿R1 and IFN¿R2 are cross-phosphorylated by their associated tyrosine kinases (Jak1 and Tyk2), followed by subsequent STAT2 and STAT1 recruitment and phosphorylational activation. The mechanism of how IFN¿ activates IRF9 is unknown. IRF9-dependent transcriptional activation can be enhanced by treating the cells with deacetylase inhibitors, suggesting IRF9 activation involves acetylation. We detected IFN¿R2 acetylation by recruiting tumor suppressor-like transcription cofactor CREB-binding protein (CBP) or its homologous p300. Acetylated IFN¿R2 can then recruit IRF9. IRF9 as well as STAT2 and STAT1 are all acetylated by CBP prior to forming the transcriptional active ISGF3 complex. IFN¿R also recruits deacetylases including SIRT and HDAC members. Although tyrosine phosphorylation has long been accepted to play a paramount role in cytokine receptor signal transduction, our findings based upon preliminary data and protein secondary structural analysis challenge this concept. The overarching hypothesis to be tested here is that CBP/p300-mediated acetylation cascade triggered by IFN¿ plays an indispensable role in signal transduction for anti-proliferation, proapotosis, and anti-metastasis gene regulation. Disrupting IFN¿R and deacetylase association with deacetylase inhibitors may improve the therapeutic effects of IFN¿ in cancer. We will apply site-directed mutagenesis, FRET technology, as well as the antibody array technology developed in our lab in order to (1) define the acetyltransferase activity associated with CBP/p300 on IFN¿R activation in intracellular signaling; (2) analyze IFN¿R, STAT1 and ISGF3 deacetylation by HDAC or SIRT in signal termination; and (3) determine whether acetylated STAT1 dimer or ISGF3 complex is critical for IFN¿- mediated anti-proliferation, proapoptosis, and antimetastasis gene regulation in cancer cells. These approaches will help elucidate the function of acetylation and deacetylation in the regulation of IFN¿R activation, STAT dimer, and ISGF3 complex formation for signal transduction and transcription, and allow us to maximize the therapeutic applications of IFN¿ for cancer.