BETA R1 GENE: MODEL SYSTEM TO STUDY IFN BETA SIGNALING

I型干扰素包括10多种亚型的干扰素-α，以及干扰素-β、干扰素-tau和干扰素-omega。这些相关的细胞因子都通过干扰素α/β受体发出信号，干扰素α/β受体是由两个跨膜成分(IFNAR-L/2)和两个非受体蛋白酪氨酸激酶TYK2和JAK1组成的复合体。最近已经清楚的是，通过这种受体复合体与其各种配体的结合可以产生不同的信号。已经描述了干扰素-β治疗的两个不同的结果：被称为β-R1的基因的可诱导转录，以及与两个受体链组装的稳定的干扰素-β复合体。我们认为，β-RL的诱导既需要共同的信号，也需要通过IFNAR-L/2复合体的独特信号。这一假设是基于我们的初步结果，该结果表明，β-RI转录依赖于形成转录因子ISGF3所需的所有成分，但对磷酸肌醇-3激酶(PI3K)抑制剂非典型地敏感，并对催化活性TYK2表现出不寻常的要求。这项研究建议解决了这样的假设，即与干扰素-α相比，13-RI转录依赖于通过IFNAR-1/2复合体对干扰素-β的反应的构象依赖的信号。该信号通路通过催化TYK2和PI3K以及ISGF3发挥作用。其具体目的是：L)确定β干扰素向β3-RL启动子传递信号的特征；2)产生对β干扰素选择性不反应的细胞；3)确定受β干扰素选择性调控的基因表达。这些目标的实现将有助于深入了解干扰素-β特异性信号转导，并有助于阐明辅助成分，如PI3K，在I型干扰素反应途径中的功能作用。

Type I interferons include more than l0 subtypes of IFN-alpha, as well as IFN-beta, IFN-tau and IFN-omega. These related cytokines all signal through the IFN alpha/beta receptor, a complex composed of two transmembrane components (IFNAR-l/2) and two nonreceptor protein tyrosine kinases, TYK2 and JAK1. It has recently become clear that diverse signals can be generated by engagement of this receptor complex with its various ligands. Two distinctive outcomes of treatment with IFN-beta have been described: inducible transcription of a gene termed beta-R1, and assembly of a stable complex of IFN-beta with the two receptor chains. We propose that the induction of beta-Rl requires both common and unique signaling through the IFNAR-l/2 complex. This hypothesis is based on our preliminary results, which demonstrate that beta-RI transcription is dependent on all components needed to form the transcription factor ISGF3, but is atypically sensitive to phosphoinositol-3 kinase (PI3K) inhibitors and exhibits an unusual requirement for catalytically active TYK2. This research proposal addresses the hypothesis that 13-RI transcription depends on conformation-dependent signaling through the IFNAR-1/2 complex in response to IFN-beta as compared with IFN-alpha. This signaling pathway acts through catalytic TYK2 and PI3K, as well as ISGF3. The specific aims are to: l) characterize IFN-beta signaling to the beta3-Rl promoter; 2) generate cells selectively unresponsive to IFN-beta and 3) determine gene expression selectively regulated by IFN-beta. Performance of these aims will provide insight into IFN-beta-specific signaling and help clarify the functional roles of accessory components, such as PI3K, in type I IFN response pathway.