In this study we observed that human GD1c/GT1a/GQ1b synthase (hST8Sia V) is particularly expressed in human glioblastoma cells. To address the mechanism regulating human glioblastoma-specific gene expression of the hST8Sia V, after the transcription start site (TSS) was identified by the 5’-rapid amplification of cDNA end with total RNA from human glioblastoma U87MG cells, the 5’-flanking region (2.5 kb) of the hST8Sia V gene was isolated and its promoter activity was examined. By luciferase reporter assay, this 5’-flanking region revealed strong promoter activity in only U-87MG cells, but not in other tissue-derived cancer cells. 5’-deletion mutant analysis showed that the region from -1140 to -494 is crucial for transcription of the hST8Sia V gene in U87MG cells. This region contains the activator protein-1 (AP-1) binding site, the main target of the c-Jun N-terminal kinase (JNK) downstream. The AP-1 binding site at -1043/-1037 was proved to be indispensable for the hST8Sia V gene-specific expression in U87MG cells by site-directed mutagenesis. Moreover, the transcriptional activation of hST8Sia V gene in U87MG cells was strongly inhibited by a specific JNK inhibitor, SP600125. These results suggest that the hST8Sia V gene-specific expression in U87MG cells is controlled by JNK/AP-1 signaling pathway.

在这项研究中，我们观察到人 GD1c/GT1a/GQ1b 合酶 (hST8Sia V) 在人胶质母细胞瘤细胞中特别表达。为了解决 hST8Sia V 人胶质母细胞瘤特异性基因表达的调节机制，通过用人胶质母细胞瘤 U87MG 细胞的总 RNA 快速扩增 cDNA 末端，鉴定转录起始位点 (TSS) 后，将 5' 侧翼分离hST8Sia V基因的区域(2.5kb)并检查其启动子活性。通过荧光素酶报告基因检测，该 5' 侧翼区域仅在 U-87MG 细胞中显示出强启动子活性，但在其他组织来源的癌细胞中则没有。5'-缺失突变体分析表明-1140至-494区域对于U87MG细胞中hST8Sia V基因的转录至关重要。该区域包含激活蛋白 1 (AP-1) 结合位点，是 c-Jun N 末端激酶 (JNK) 下游的主要靶标。通过定点诱变证明-1043/-1037处的AP-1结合位点对于U87MG细胞中hST8Sia V基因特异性表达是必不可少的。此外，U87MG细胞中hST8Sia V基因的转录激活被特异性JNK抑制剂SP600125强烈抑制。这些结果表明U87MG细胞中hST8Sia V基因特异性表达受JNK/AP-1信号通路控制。