Analysis of cooperative expression of the genes encoding glycosyltransferases involved in the histo-blood group ABH antigens.

组织血型ABH抗原的合成需要几种糖基转移酶。A/B抗原是由特定糖基转移酶催化的糖的顺序加成合成的末端碳水化合物。这些转移酶需要对前体寡核苷酸进行α(1，2)岩藻糖修饰，因此A和B抗原只能由H抗原合成。控制糖基转移酶基因的分子基础对于深入了解这些基因产物的调控和组织特异性表达具有重要意义。在本研究中，我们展示了反义转录产物的表达，它补充了编码ABO糖基转移酶基因的基因组DNA编码链。据报道，自然发生的反义转录通过各种生物学机制来调节基因的表达。因此，该反义转录本可能参与了ABO基因表达的调控。我们还需要进一步研究编码α(1，2)岩藻糖基转移酶的FUT1和FUT2基因以及ABO基因的反义RNA的存在。此外，我们已经证实ABO基因的表达受到启动子上游N-box的负调控，N-box与一种名为RACP的核因子结合。N-box被bHLH因子成员识别。BHLH家族转录调控因子在各种器官和细胞类型的发育中起着至关重要的作用。在此之前，我们证明了ABO基因与FUT1和FUT2基因共表达。对FUT1和FUT2基因上游区的核苷酸序列进行检测，发现了bHLH蛋白的可能结合部位，提示bHLH因子可能在基因表达中起关键作用。因此，包括RACP在内的N-box结合蛋白可能介导ABH抗原中编码糖基转移酶的基因的协同表达。

Synthesis of the histo-blood group ABH antigens requires several glycosyltransferases. The A/B antigens are terminal carbohydrates synthesized by the sequential addition of sugers catalyzed by specific glycosyltransferases. These transferases require α(1,2) fucose modification of the precursor oligonucleotides, and thus A and B antigens can only be synthesized from H antigen. The molecular basis of control of the glycosyltransferase genes is of importance in obtaining a deeper understanding of the regulation and tissue specific expression of the products of those genes.In this study, we demonstrated the expression of antisense transcripts, complementary to the genomic DNA coding strand for the ABO gene encoding ABO glycosyltransferase. Naturally occurring antisense transcriptions have been reported to regulate gene expression through a variety of biological mechanisms. Therefore, the antisense transcript might be involved in the regulation of the ABO gene expression. Further studies will be needed to investigate the presence of antisense RNA to the FUT1 and FUT2 genes encoding α(1,2) fucosytransferase as well as the ABO gene.Moreover, we have confirmed that the ABO gene expression is negatively regulated by N-box upstream of the promoter and that the N box binds with a nuclear factor termed RACP. N-box is recognized by members of bHLH factor. The bHLH family of transcriptional regulators plays crucial roles in the development of various organs and cell types. Previously, we demonstrated that the ABO gene was co-expressed with the FUT1 and FUT2 genes. Inspection of the nucleotide sequences of the upstream region of the FUT1 and FUT2 genes revealed putative binding site of bHLH proteins, suggesting that the bHLH factors could play crucial roles in expression of the genes. Therefore, the N-box binding protein including to the RACP might mediate regulation for cooperative expression of those genes encoding glycosyltransferases involved in the ABH antigens.