Brucet M, Marqués L, Sebastián C, Lloberas J, Celada A
Group of Macrophage Biology, Institute of Biomedical Research of Barcelona, Barcelona Science Park, University of Barcelona, Spain.
Genes Immun. 2004 Jan;5(1):26-35. doi: 10.1038/sj.gene.6364035.
The genes of the transporter associated with antigen processing (Tap)-1, and the low molecular weight peptide (Lmp)-2, are crucial for class I major histocompatibility complex function and share a common bidirectional promoter. In murine bone marrow-derived macrophages, interferon gamma (IFN-gamma) induced Tap-1 and upregulated Lmp-2, which is constitutively expressed at low levels. The IFN-gamma-induction was independent of early gene synthesis. The mRNA induced by IFN-gamma was very stable. In macrophages from STAT1 knockout mice, IFN-gamma did not induce the expression of Tap-1 or Lmp-2. Several areas in the promoter can be controlled by IFN-gamma, such as proximal and distal GAS boxes in the direction of the Tap-1 gene, NFgammaB and IRF-1 boxes. By making deletions of the promoter, we found that only the proximal GAS and IRF-1 boxes are required for IFN-gamma induction of Tap-1 and Lmp-2. Experiments using nuclear extracts from macrophages treated for 30 min with IFN-gamma and gel shift analysis indicated that STAT1 binds to the GAS box. The nuclear extracts from macrophages treated for at least 2 h with IFN-gamma bound to the IRF-1 box. These results indicate that both STAT1 and IRF-1 are required for the IFN-gamma induction of Tap-1 and Lmp-2 genes.
与抗原加工相关的转运体（Tap）-1基因和低分子量肽（Lmp）-2基因对于I类主要组织相容性复合体功能至关重要，且共享一个共同的双向启动子。在小鼠骨髓来源的巨噬细胞中，γ干扰素（IFN-γ）诱导Tap-1表达并上调Lmp-2表达，Lmp-2基因通常以低水平组成性表达。IFN-γ的诱导作用不依赖早期基因合成。IFN-γ诱导产生的mRNA非常稳定。在STAT1基因敲除小鼠的巨噬细胞中，IFN-γ不能诱导Tap-1或Lmp-2表达。启动子中的几个区域可受IFN-γ调控，如在Tap-1基因方向上的近端和远端GAS框、NFγB和IRF-1框。通过对启动子进行缺失操作，我们发现IFN-γ诱导Tap-1和Lmp-2表达仅需要近端GAS框和IRF-1框。使用经IFN-γ处理30分钟的巨噬细胞核提取物进行凝胶迁移分析的实验表明，STAT1与GAS框结合。经IFN-γ处理至少2小时的巨噬细胞核提取物与IRF-1框结合。这些结果表明，STAT1和IRF-1对于IFN-γ诱导Tap-1和Lmp-2基因表达均是必需的。
