ACCESSORY CELL ACTIVATION OF THE IMMUNE RESPONSE

单核细胞至少表达两种不同类型的细胞类型特异性基因。其中一类，以M-CSF受体基因c-fms为例，是组成型表达并依赖于分化状态。另一类，以il -1 β基因（il1b）为代表，通常也是单核细胞特异性的，但只在刺激事件下立即表达，该刺激事件与静止的单核细胞向活化的单核细胞/巨噬细胞的转化相似。对il1b调控机制的研究揭示了该基因的两个不同且可分离的区域，分别对应于两个标准，一个细胞类型特异性的143bp基础启动子和一个信号响应的上游增强子。增强子的功能取决于几种广泛表达的信号响应转录因子（如C/EBPbeta、CREB、C - jun和NF- kappaB）的协同功能，包括一种新的stat样因子，而71 bp的基础启动子似乎依赖于单髓细胞因子Spi-1/PU.1分子的结合（Spi-1），一个在单核细胞发育和细胞类型特异性基因表达中起核心关键作用的因子。基础启动子和增强子之间的功能相互作用需要一个关键的额外73bp的元件，这需要额外的Spi-1分子的结合。在IE2（一种巨细胞病毒蛋白）存在的情况下，该元件不需要增强剂独立的活性。IE2似乎直接与Spi-1 ETS域交互。该区域存在于所有ETS蛋白中，并介导与广泛的其他蛋白的关联，调节两个伙伴蛋白的功能。本研究的目的是阐明Spi-1与其他蛋白相互作用的机制，并将增强子功能整合到核心启动子中，并试图克隆在LPS、IL-1和IL-6的作用下被激活的新型stat样因子。

Monocytes express at least two different classes of cell-type specific genes. One class, exemplified gy the M-CSF receptor gene, c-fms, is constitutively expressed and dependent upon the differentiated state. Another class, represented by the IL-1beta gene (il1b), is also generally monocyte-specific, but is only expressed immediately in response to a stimulation event that parallels the conversion of the resting monocyte to the activated monocyte/macrophage. Investigation of the il1b regulation mechanisms have revealed two distinct and separable regions of the gene that correspond to each of the two criteria, a cell type specific 143bp basal promoter and a signal-responsive upstream enhancer. The enhancer function depends upon the cooperative function of several broadly expressed signal-responsive transcription factors (e.g., C/EBPbeta, CREB, c-Jun, and NF- kappaB), including a novel STAT-like factor, whereas the 71 bp basal promoter appears to depend upon binding of one molecule of the mono-myeloid factor Spi-1/PU.1 (Spi-1), a factor that plays a central key role in monocyte development and cell type-specific gene expression. The functional interaction between the basal promoter and an enhancer requires a critical additional 73bp element that requires the binding of an additional Spi-1 molecule. This element is not required for enhancer-independent activity in the presence of IE2, a cytomegalovirus protein. IE2 appears to interact directly with the Spi-1 ETS domain. This region is found in all ETS proteins and mediates associations with a broad range of other proteins, modulating function in both partners. The object of this proposal is to elucidate the mechanism by which Spi-1 interacts with other proteins and integrates enhancer function into the core promoter and to attempt to clone the novel STAT-like factor that is activated in response to LPS, IL-1, and IL-6.