Cailleau-Thomas A, Coullin P, Candelier J J, Balanzino L, Mennesson B, Oriol R, Mollicone R
U 504 INSERM, Université de Paris Sud XI, 94807 Villejuif, France.
Glycobiology. 2000 Aug;10(8):789-802. doi: 10.1093/glycob/10.8.789.
The Le(x) oligosaccharide is expressed in organ buds progressing in mesenchyma, during human embryogenesis. Myeloid-like alpha3-fucosyltransferases are good candidates to synthesize this oligosaccharide. We investigated by Northern analysis all the alpha3-fucosyltransferase gene transcripts and only FUT4 and FUT9 were detected. The enzymes encoded by the FUT4 and FUT9 genes are the first alpha3-fucosyltransferases strongly expressed during the first two months of embryogenesis. The Northern profile of expression of the embryo FUT4 transcripts is similar in size and sequence to the known FUT4 transcripts of 6 kb, 3 kb, and 2.3 kb, but a new FUT9 transcript of 2501 bp, different from the known mouse (2170 bp) and human (3019 bp) transcripts was cloned. FUT3, FUT5, FUT6, and FUT7 were not detected by Northern blot. The FUT3 and FUT6 transcripts start to appear at this stage, but are only detected by reverse transcriptase-PCR analysis. The expression of FUT5 is weaker than FUT3 and FUT6 and the RT-PCR signal is faint and irregular. FUT7 is not detected at all. Using mRNA from 40- to 65-day-old embryos, we have prepared different hexamer and oligo-dT cDNA libraries and cloned, by rapid amplification cDNA ends-PCR, FUT4 and FUT9 alpha3-fucosyltransferase transcripts. The tissue expression of the embryonic FUT9 transcript is closer to that observed for the mouse (brain), than to the known human (stomach) transcripts. The acceptor specificity and the kinetics of the alpha3-fucosyltransferase encoded by this FUT9 transcript are similar to the FUT4 enzyme, except for the utilization of the lac-di-NAc acceptor which is not efficiently transformed by the FUT9 enzyme. Like FUT4, this embryonic FUT9 is N-ethylmaleimide and heat resistant and the corresponding gene was confirmed to be localized in the chromosome band 6q16. Finally, this FUT9 transcript has a single expressed exon as has been observed for most of the other vertebrate alpha2- and alpha3-fucosyltransferases.
在人类胚胎发育过程中，Le(x)寡糖在间充质中发育的器官芽中表达。类髓样α3-岩藻糖基转移酶是合成这种寡糖的良好候选酶。我们通过Northern分析研究了所有α3-岩藻糖基转移酶基因转录本，仅检测到FUT4和FUT9。FUT4和FUT9基因编码的酶是在胚胎发育的前两个月中强烈表达的首批α3-岩藻糖基转移酶。胚胎FUT4转录本的Northern表达谱在大小和序列上与已知的6 kb、3 kb和2.3 kb的FUT4转录本相似，但克隆到了一个2501 bp的新FUT9转录本，它与已知的小鼠（2170 bp）和人类（3019 bp）转录本不同。Northern印迹未检测到FUT3、FUT5、FUT6和FUT7。FUT3和FUT6转录本在此阶段开始出现，但仅通过逆转录酶-PCR分析检测到。FUT5的表达弱于FUT3和FUT6，RT-PCR信号微弱且不规则。根本未检测到FUT7。使用40至65日龄胚胎的mRNA，我们制备了不同的六聚体和oligo-dT cDNA文库，并通过快速扩增cDNA末端-PCR克隆了FUT4和FUT9α3-岩藻糖基转移酶转录本。胚胎FUT9转录本的组织表达与小鼠（脑）中观察到的更接近，而与已知的人类（胃）转录本不同。该FUT9转录本编码的α3-岩藻糖基转移酶的受体特异性和动力学与FUT4酶相似，除了对lac-di-NAc受体的利用，FUT9酶不能有效地转化该受体。与FUT4一样，这种胚胎FUT9对N-乙基马来酰亚胺和热具有抗性，并且相应基因被证实定位于染色体带6q16。最后，该FUT9转录本有一个单一的表达外显子，这与大多数其他脊椎动物的α2-和α3-岩藻糖基转移酶情况相同。
