Cell Adhesion Regulation Mechanism by Sialyl-Le^X Structure.

我们通过重塑人b前白血病细胞的糖基转移酶机制，证明细胞表面唾液- lex （sLeX）抗原表达水平受核心2 n -乙酰氨基葡萄糖转移酶（C2GnT）基因控制。此外，我们还披露了以下内容：sLeX抗原不是在每一种蛋白上表达，而是在一个特定的核心糖蛋白上表达，其分子大小为15okda （gp 150）。sLeX抗原决定因子在gplso2的0链低聚糖链末端表达。通过荧光素酶测定、EMSA和RNA印迹分析C2GnT表达的转录调控机制，我们证明了以下几点。(1)在C2GnT转录调控区的3个TATA box中，含有最接近转录起始位点-182 TATA的缺失突变体荧光素酶活性最高。(2) C2GnT基因表达细胞的瞬时转录活性是非表达细胞的10倍。通过抑制细胞分化过程中C2GnT基因的表达，将瞬时转录活性下调至1/10。这与C2GnT信息、C2GnT酶活性和细胞表面sLeX抗原表达水平的变化有很好的一致性。(3)涉及的转录因子结合位点为GATA、NF-IL6和Spi。GATA3、NF-1L6、C/EBPgamma、Sp3、Sp4基因的表达与C2GnT基因表达水平相关。

We have demonstrated through remodeling of the glycosyltrasferase machineries in human pre-B leukemia cells that cell surface sialyl-LeX (sLeX) antigen expression level is controlled by core 2 N-acetylglucosaminyltransferase (C2GnT) gene. In addition, we have revealed the followings.1. sLeX antigen is not expressed on every protein but expressed on a specific core glycoprotein with molecular size of l5OkDa (gp 150). sLeX antigen determinants are expressed at the termini of 0-linked oligosaccharide chains of gplSO.2. Analyzing transcription regulation mechanism of C2GnT expression by luciferase assay, EMSA, and RNA blotting, we have demonstrated the followings.(1) Among three TATA boxes in the C2GnT transcription regulation area, a deletion mutant containing the most proximate -182 TATA to the transcription initiation site showed the highest luciferase activity.(2) C2GnT gene expressing cells had 10-fold transient transcription activity of the non-expressing cells. Transient transcription activity was down-regulated to 1/10 by inhibiting C2GnT gene expression among cell differentiation. These are in a good agreement with changes of C2GnT message, C2GnT enzyme activity, and cell surface sLeX antigen expression levels.(3) Involved transcription factor binding sites are GATA, NF-IL6, and Spi. The expression of GATA3, NF-1L6, C/EBPgamma, Sp3, and Sp4 genes correlated with C2GnT gene expression level.