A murine AP-endonuclease gene-targeted deficiency with post-implantation embryonic progression and ionizing radiation sensitivity
A murine AP-endonuclease gene-targeted deficiency with post-implantation embryonic progression and ionizing radiation sensitivity
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DOI：
10.1016/s0921-8777(98)00039-1
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发表时间：
1998-10-21
期刊：
影响因子：
--
通讯作者：
Chen, DJ
中科院分区：
文献类型：
--
作者：
Ludwig, DL;MacInnes, MA;Chen, DJ
无尿嘧啶/无嘧啶内切酶（APE/REF）在哺乳动物中对基本或单链断裂损伤进行修复切口。这种多功能蛋白在细胞应激转录反应中也被认为是半胱氨酸“还原因子”（REF）。为了评估APE/REF在胚胎畸形中的意义，我们在小鼠中构建了一个更精确靶向的APE/REF缺陷基因型。胚胎干细胞中的Ape/Ref基因替代消除了Ape/Ref蛋白合成的潜力，同时保留了Ape/Ref双向启动子，避免了上游基因的潜在失活。嵌合动物进入Tac:N:NIHS-BC后产生种系传播。纯合子无猿/ ref胚胎成功着床，直到胚胎第7.5天，发育过程几乎正常，随后在第9.5天胚胎形态发生失败和吸附。我们描述了胚胎致死性的细胞事件，并检测了植入前Ape/Ref-null胚胎的电离辐射敏感性。杂合子杂交后，在第6.5天，假定的Ape/ rf -null后代胚胎的孟德尔数显示，胚胎属性-外胚层内的缩裂细胞核增加了数倍。随着有丝分裂的继续，在明显的形态发生破坏之前，外胚层细胞内的细胞核变性增加。有丝分裂反应对外胚层细胞死亡，如果有的话，是无效的替代失去的细胞。胚外卵黄囊，一个滋养外胚层衍生谱系在第9天保持正常外观，外植的纯合子Ape/ REF -null囊胚对γ辐射的敏感性增加，很可能是Ape/ REF切口缺陷的表现。我们的研究表明，这种新的Ape/Ref缺陷基因型肯定能够在着床后发育进展到原肠胚形成的开始。APE/REF在基底损伤切口中的功能，以及对外胚层细胞死亡的有丝分裂反应，对于胚胎生长和发育的原肠胚形成阶段至关重要。(C) 1998 Elsevier Science B.V.版权所有
Apurinic/apyrimidinic endonuclease there designated APE/REF) carries out repair incision at abasic or single-strand break damages in mammals. This multifunctional protein also has putative role(s) as a cysteine 'reducing factor' (REF) in cell-stress transcriptional responses. To assess the significance of APE/REF for embryonic teratogenesis we constructed a more precisely targeted Ape/Ref-deficient genotype in mice. Ape/Ref gene replacement in ES cells eliminated the potential of APE/REF protein synthesis while retaining the Ape/Ref bi-directional promoter that avoided potential inactivation of an upstream gene. Chimeric animals crossed into Tac:N:NIHS-BC produced germline transmission. Homozygous null Ape/Ref-embryos exhibited successful implantation and nearly normal developmental progression until embryonic day 7.5 followed by morphogenetic failure and adsorption of embryos by day 9.5. We characterized the cellular events proceeding to embryonic lethality and examined ionizing radiation sensitivity of pre-implantation Ape/Ref-null embryos. After intermating of heterozygotes, Mendelian numbers of putative Ape/Ref-null progeny embryos at day 6.5 displayed a several-fold elevation of pycnotic, fragmenting cell nuclei within the embryo proper-the epiblast. Increased cell-nucleus degeneration occurred within epiblast cells while mitosis continued and before obvious morphogenetic disruption. Mitogenic response to epiblast cell death, if any, was ineffective for replacement of lost cells. Extra-embryonic yolk sac, a trophectoderm derived lineage retained normal appearance to day 9, Explanted homozygous Ape/Ref-null blastocysts displayed increased sensitivity to gamma-irradiation, most likely a manifestation of APE/REF incision defect. Our study establishes that this new Ape/Ref deficiency genotype is definitely capable of post-implantation developmental progression to the onset of gastrulation. Function(s) of APE/REF in base damage incision and also conceivably in mitogenic responses towards epiblast cell death are critical for transit through the gastrulation stage of embryonic growth and development. (C) 1998 Elsevier Science B.V. All rights reserved.