Department of Pediatrics, The First Affiliated Hospital, Nanjing Medical University, Nanjing, Jiangsu, China.
Mol Biol Rep. 2012 Jun;39(6):6987-93. doi: 10.1007/s11033-012-1528-9. Epub 2012 Feb 4.
Interferon regulatory factor 3 (IRF-3), an essential transcriptional regulator of the interferon genes, plays an important role in host defense against viral and microbial infection as well as in cell growth regulation. Promoter plays a crucial role in gene transcription. We have reported the characterization of the wide type of human IRF-3 promoter, but the characterization of the spliced variant of human IRF-3 Int2V1 promoter has not been systematically analyzed. To observe the spliced variant of human IRF-3 promoter, we have cloned the human IRF-3 gene promoter region containing 300 nucleotides upstream the transcription start site (TSS). Transient transfection of 5' deleted promoter-reporter constructs and luciferase assay illustrated the region -159/-100 relative to the TSS is sufficient for full promoter activity. This region contains GATA1 and specific protein-1 (Sp1) transcription factor binding sites. Interestingly, mutation of this Sp1 site reduced the promoter activity by 50%. However, overexpression of Sp1 increased the transcription activity by 2.4-fold. These results indicated that the spliced variant of human IRF-3 gene core promoter was located within the region -159/-100 relative to the TSS. Sp1 transcription factor upregulates the spliced variant of human IRF-3 gene promoter.
干扰素调节因子 3（IRF-3）是干扰素基因的重要转录调节因子，在宿主防御病毒和微生物感染以及细胞生长调节中发挥重要作用。启动子在基因转录中起着至关重要的作用。我们已经报道了人 IRF-3 启动子的野生型特征，但人 IRF-3 Int2V1 启动子剪接变体的特征尚未系统分析。为了观察人 IRF-3 启动子的剪接变体，我们已经克隆了包含转录起始位点（TSS）上游 300 个核苷酸的人 IRF-3 基因启动子区域。瞬时转染 5'缺失启动子-报告构建体和荧光素酶测定表明，相对于 TSS 的-159/-100 区域足以发挥完全启动子活性。该区域包含 GATA1 和特异性蛋白-1（Sp1）转录因子结合位点。有趣的是，该 Sp1 位点的突变使启动子活性降低了 50%。然而，Sp1 的过表达将转录活性增加了 2.4 倍。这些结果表明，人 IRF-3 基因核心启动子的剪接变体位于相对于 TSS 的-159/-100 区域内。Sp1 转录因子上调人 IRF-3 基因启动子的剪接变体。
