ACCESSORY CELL ACTIVATION OF THE IMMUNE RESPONSE

单核细胞表达至少两种不同类型的细胞类型特异性基因。 一类，例如戈伊M-CSF受体基因c-fms，是组成型表达的，并依赖于分化状态。 以IL-1 β基因（il 1b）为代表的另一类基因通常也是单核细胞特异性的，但仅在响应于刺激事件时立即表达，该刺激事件与静息单核细胞向活化单核细胞/巨噬细胞的转化平行。 对il 1b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：细胞类型特异性143 bp基础启动子和信号响应性上游增强子。 增强子功能取决于几种广泛表达的信号响应性转录因子（例如，C/EBP β、CREB、c-Jun和NF-κ B），包括一种新的STAT样因子，而71 bp的基础启动子似乎依赖于一种单髓样因子Spi-1/PU. 1（Spi-1）分子的结合，该因子在单核细胞发育和细胞类型特异性基因表达中起关键作用。 基础启动子和增强子之间的功能性相互作用需要一个关键的额外的73 bp元件，该元件需要额外的Spi-1分子的结合。 在IE 2（一种巨细胞病毒蛋白）存在下，该元件不是增强子非依赖性活性所必需的。 IE 2似乎直接与Spi-1 ETS结构域相互作用。 该区域存在于所有ETS蛋白中，并介导与广泛的其他蛋白质的关联，调节双方的功能。 本提案的目的是阐明Spi-1与其他蛋白相互作用并将增强子功能整合到核心启动子中的机制，并试图克隆响应LPS、IL-1和IL-6而激活的新型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.