COMPLEX ASPARAGINE-LINKED OLIGOSACCHARIDES IN MGAT1-NULL EMBRYOS
COMPLEX ASPARAGINE-LINKED OLIGOSACCHARIDES IN MGAT1-NULL EMBRYOS
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DOI：
10.1093/glycob/5.5.535
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发表时间：
1995-07-01
期刊：
影响因子：
4.3
通讯作者：
MARTH, JD
中科院分区：
文献类型：
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作者：
CAMPBELL, RM;METZLER, M;MARTH, JD
为了研究复合n -连接寡糖的发育作用，我们先前灭活了小鼠Mgat1基因，该基因编码udp - n -乙酰氨基葡萄糖：α -3- d -甘露糖β -1,2- n -乙酰氨基葡萄糖转移酶I （GlcNAc-TI）。mgat1缺失的胚胎在胚胎日(E) 9.5时出现形态发生异常，在胚胎日(E) 10.5后不能存活。在E8.5之前，突变型和野生型胚胎在表型上无法区分，这提出了意想不到的可能性，即早期胚胎发育可能不需要复杂的n -聚糖。我们现在使用原位RNA杂交来评估正常胚胎中Mgat1表达的时空模式，并使用凝集素组织化学来确定在e9.5前发育阶段Mgat1缺失的胚胎是否缺乏复杂的n -聚糖。原位RNA分析表明，在突变胚胎死亡前1-2天，Mgaf1转录本在E7.0和E9.5之间通常显著增加。然而，在植入前E3.5的mgat1缺失胚胎中，复合n -聚糖的水平明显正常，到E7.5时下降到无法检测到的水平。在E7.5-E9.5 mgat1缺失的胚胎中没有观察到复杂的n -聚糖，但内脏胚胎外内胚层细胞内的囊泡结构除外，这可能反映了这些细胞吸收和运输母源性糖蛋白的能力。在母体衍生的复合n -聚糖存在的情况下，mgat1缺失的胚胎似乎可以完成植入前发育，并可能在E7.5后的后期阶段死亡，当对胚胎衍生的复合n -聚糖的需求出现时。
To investigate the developmental role of complex N-linked oligosaccharides, we previously inactivated the mouse Mgat1 gene which encodes UDP-N-acetylglucosamine: alpha-3-D-mannoside beta-1,2-N-acetylglucosaminyltransferase I (GlcNAc-TI). Mgat1-null embryos developed morphogenic abnormalities by embryonic day (E) 9.5 and failed to survive beyond E10.5. Prior to E8.5, mutant and wild-type embryos were phenotypically indistinguishable, raising the unexpected possibility that earlier embryonic development may not require complex N-glycans. We have now used in situ RNA hybridization to assess the temporal and spatial pattern of Mgat1 expression in normal embryos, and lectin histochemistry to determine whether Mgat1-null embryos lack complex N-glycans at pre-E9.5 developmental stages. In situ RNA analysis indicated that Mgaf1 transcripts normally increase dramatically between E7.0 and E9.5, 1-2 days prior to the death of mutant embryos. However, apparently normal levels of complex N-glycans were observed in E3.5 pre-implantation Mgat1-null embryos prior to declining to undetectable levels by E7.5. Complex N-glycans were not observed in E7.5-E9.5 Mgat1-null embryos with the notable exception of vesicular structures within cells of the visceral extra-embryonic endoderm, perhaps reflecting the ability of these cells to take up and transport maternally derived glycoproteins. Mgat1-null embryos appear to complete pre-implantation development in the presence of maternally derived complex N-glycans, and may die at later stages, post E7.5, when a requirement for embyronically derived complex N-glycans arises.