MOLECULAR BASIS FOR INTERFERON SPECIFICITY

快速转录激活反应的基础 细胞外刺激是细胞生物学的一个基本问题。 当然，这种对淋巴因子刺激的激活是 对适当的免疫反应至关重要。干扰素系统 提供了一个有吸引力的模型，用来解决机械方面的问题 这个问题，特别是当它表现出多个层面的特殊性时。 这项提议的目标是确定基因激活的机制。 一种干扰素，干扰素-伽马。 参与巨噬细胞活化的一些早期反应基因 是由干扰素-γ诱导的，而不是由干扰素-α诱导的。其中有一些基因 编码LGG的高亲和力受体FcGammaRI。我们发现了 一个39个核苷酸的DNA序列，干扰素-伽马反应区(GRR)， 目前为止在所有FcGammaRI启动子中都存在，并且是 对这些启动子的转录诱导是必要的和充分的 通过干扰素-伽马。我们还发现了一个91 kDa的蛋白质，首次鉴定 作为干扰素-α诱导的转录复合体ISGF3的一个组成部分， 将在GRR的3‘端集合，以响应干扰素-伽马 或者干扰素-伽马。因为FcGammaRI和GRR-Report构造都不是 在干扰素-α诱导下，这些启动子的干扰素-γ特异性 似乎来自与GRR相互作用的额外蛋白质 在接触了干扰素-伽玛之后。支持这种互动的证据 包括紫外光交联实验，显示40- GRR基因的50 kDa蛋白及其突变分析 展示了一个蛋白质复合体，它在5‘端组装，相互作用 91，并且是对干扰素-γ的最佳应答所必需的。这个 我们建议的目标是识别和表征 在GRR处介导干扰素-γ的转录诱导。

The basic for rapid transcriptional activation in response to extracellular stimuli is a fundamental question for cell biology. Certainly such activation in response to lymphokine stimulation is critical for an appropriate immune response. The interferon system affords an attractive model with which to address mechanistic aspects of this question, especially as it displays multiple levels of specificity. The goal of this proposal is to define the mechanisms of gene activation by one class of interferon, IFN-gamma. A number of the early-response genes involved in macrophage activation are induced by IFN-gamma but not IFN-alpha. Among these are the genes encoding the high affinity receptor for lgG, FcgammaRI. We have found that a 39 nucleotide DNA sequence, the IFN-gamma response region (GRR), is present in all FcgammaRI promoters characterized thus far, and is necessary and sufficient for transcriptional induction of those promoters by IFN-gamma. We have also found that a 91 kDa protein, fist identified as a component of the IFN-alpha induced transcription complex, ISGF3, will assemble at the 3' end of the GRR in response to either IFN-gamma or IFN-gamma. As neither FcgammaRI nor GRR-reporter constructs are induced by IFN-alpha, the IFN-gamma specificity of these promoters appears to arise from additional proteins which interact with the GRR following IFN-gamma exposure. Evidence supporting such interactions includes UV crosslinking experiments which show specific binding of a 40- 50 kDa protein of the GRR, and mutational analysis of the GRR demonstrating a protein complex which assembles at the 5' end, interacts with 91, and is necessary for optimal responsiveness to IFN-gamma. The goal of our proposal is to identify and characterize the proteins that mediate transcriptional induction by IFN-gamma at the GRR.