Glutamine synthetase is essential in early mouse embryogenesis
Glutamine synthetase is essential in early mouse embryogenesis
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DOI：
10.1002/dvdy.21185
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发表时间：
2007-07-01
影响因子：
2.5
通讯作者：
Van Roon, Maria A.
中科院分区：
文献类型：
--
作者：
He, Youji;Hakvoort, Theodorus B. M.;Van Roon, Maria A.
谷氨酰胺合成酶（GS）以组织特异性和发育控制的方式表达，具有去除氨或谷氨酸的功能。此外，它是唯一能合成谷氨酰胺从头合成的酶。由于先天性GS缺乏尚未报道，我们研究了其在早期发育中的作用。由于GS在胚胎干细胞中表达，我们用β -半乳糖苷酶-新霉素融合基因替换框架内的一个GS等位基因，产生了一个零突变体。GS（+/LacZ）小鼠没有表型，但GS（LacZ/LacZ）小鼠在ED3.5时死亡，表明GS在早期胚胎发生中至关重要。虽然来自ED2.5 GS（LacZ/LacZ）胚胎和GS(GFP/LacZ) ES细胞的细胞在体外含谷氨酰胺的培养基中存活，但这些GS缺陷细胞在嵌合体分析中显示出较低的适应性，并且在四倍体互补试验中无法存活。重度嵌合小鼠（> 90%）的存活率至少达到ED16.5，这表明GS缺乏不会引起细胞自主效应，并且在植入后，GS活性至少在胎儿期之前不是必需的。我们假设GS缺陷胚胎在从输卵管转移到更恶劣的子宫环境时死亡，在子宫环境中，胚胎必须分解氨基酸以产生能量，因此必须解毒氨，这需要GS活性。科学进展，2006(6):555 - 557。(c) 2007 Wiley-Liss, Inc。
Glutamine synthetase (GS) is expressed in a tissue-specific and developmentally controlled manner, and functions to remove ammonia or glutamate. Furthermore, it is the only enzyme that can synthesize glutamine de novo. Since congenital deficiency of GS has not been reported, we investigated its role in early development. Because GS is expressed in embryonic stem (ES) cells, we generated a null mutant by replacing one GS allele in-frame with a beta-galactosidase-neomycine fusion gene. GS(+/LacZ) mice have no phenotype, but GS(LacZ/LacZ) mice die at ED3.5, demonstrating GS is essential in early embryogenesis. Although cells from ED2.5 GS(LacZ/LacZ) embryos and GS(GFP/LacZ) ES cells survive in vitro in glutamine containing medium, these GS-deficient cells show a reduced fitness in chimera analysis and fail to survive in tetraploid-complementation assays. The survival of heavily (> 90%) chimeric mice up to at least ED16.5 indicates that GS deficiency does not entail cell-autonomous effects and that, after implantation, GS activity is not essential until at least the fetal period. We hypothesize that GS-deficient embryos die when they move from the uterine tube to the harsher uterine environment, where the embryo has to catabolize amino acids to generate energy and, hence, has to detoxify ammonia, which requires GS activity. Developmental Dynamics 236:1865-1875, 2007. (c) 2007 Wiley-Liss, Inc.