Upstream DNA sequences required for tissue-specific expression of the HLA-DRa gene
Upstream DNA sequences required for tissue-specific expression of the HLA-DRa gene
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通讯作者：
Paula A. Sherman;Patricia V. BASTAt;J. P. Ting
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作者：
Paula A. Sherman;Patricia V. BASTAt;J. P. Ting
我们使用体外缺失诱变与DNA转染相结合的方法来寻找与人类H类主要组织相容性复合体基因的组织特异性表达相关的顺式调控元件。一个140碱基对的5'侧翼片段包含II类盒一致序列和一个八聚体序列（AT- TTGCAT），赋予HLA-DRx基因启动子的组织特异性。含有与细菌氯霉素乙酰转移酶基因编码序列融合的DRa基因片段的重组DNA质粒在人b细胞系中的表达水平高于在人t细胞系中的表达水平。我们已经证明，II类盒中最多的5'对于组织特异性DRa启动子功能是必不可少的。此外，使用电泳迁移率转移测定来鉴定DNA结合蛋白，我们已经检测到核蛋白与含有II类盒和八聚体序列的DNA探针的结合。一种与八聚体结合的蛋白质在b细胞系的核提取物中比在其他细胞系中含量更高。这种蛋白可能对HLA-DRx基因的组织特异性表达很重要。
We have used in vitro deletion mutagenesis in combination with DNA transfection to search for cis-acting regulatory elements involved in the tissue-specific expression of a human class H major histocompatibility complex gene. A 140-base-pair 5' flanking fragment that contains the class II box consensus sequences and an octamer sequence (AT- TTGCAT) confers tissue specificity on the promoter of the HLA-DRx gene. Recombinant DNA plasmids containing this DRa gene segment fused to the coding sequence of the bacterial chloramphenicol acetyltransferase gene are expressed at higher levels in human B-cell lines than in human T-cell lines. We have demonstrated that the most 5' of the class II boxes is essential for tissue-specific DRa promoter function. In addition, using an electrophoretic mobility shift assay to identify DNA binding proteins, we have detected binding of nuclear proteins to DNA probes containing the class II boxes and the octamer sequence. A protein that binds to the octamer is present at higher levels in nuclear extracts of B-cell lines than in other cell lines examined. This protein may be important for the tissue-specific expression of the HLA-DRx gene.