MOLECULAR BASIS FOR INTERFERON SPECIFICITY

快速转录激活的基础是 细胞外刺激是细胞生物学的基本问题。 当然，这种对淋巴因子刺激反应的激活， 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，以解决机械方面的 这个问题，特别是因为它显示了多层次的特异性。 这项提案的目的是确定基因激活的机制 被一类干扰素干扰素γ所感染 许多早期反应基因参与巨噬细胞活化 是由IFN-γ而不是IFN-α诱导的。 其中包括基因 编码IgG的高亲和力受体Fc γ RI。 我们发现 一个39个核苷酸的DNA序列，IFN-γ反应区（GRR）， 存在于迄今为止表征的所有Fc γ RI启动子中，并且 对于那些启动子的转录诱导是必要的和充分的 IFN-γ 我们还发现了一个91 kDa的蛋白质， 作为干扰素-α诱导的转录复合物ISGF 3的组成部分， 将在GRR的3'端组装，以响应IFN-γ或IFN-γ 或IFN-γ。 由于Fc γ RI和GRR-报告基因构建体均不表达， 这些启动子的IFN-γ特异性 似乎是由与GRR相互作用的其他蛋白质引起的 IFN-γ暴露后。 支持这种相互作用的证据 包括UV交联实验，其显示40- GRR的50 kDa蛋白，以及GRR的突变分析 证明了在5'端组装的蛋白质复合物， 与91，是必要的最佳反应IFN-γ。 的 我们计划的目标是鉴定和表征 在GRR处介导IFN-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.