Functional full-term placentas formed from parthenogenetic embryos using serial nuclear transfer
Functional full-term placentas formed from parthenogenetic embryos using serial nuclear transfer
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DOI：
10.1242/dev.051375
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发表时间：
2010-09-01
期刊：
影响因子：
4.6
通讯作者：
Wakayama, Teruhiko
中科院分区：
文献类型：
--
作者：
Hikichi, Takafusa;Ohta, Hiroshi;Wakayama, Teruhiko
哺乳动物孤雌生殖胚胎总是在妊娠中期死于印记基因缺陷和胎盘发育不全。根据嵌合体实验，在没有男性基因组的情况下，滋养细胞的增殖被认为是被抑制的。在这里，我们展示了孤雌生殖的小鼠胚胎细胞核可以通过连续几轮的核移植重新编程，而不需要使用任何遗传修改。来自绿色荧光蛋白(GFP)标记的孤雌生殖细胞核的克隆胎儿通过重复核移植延长了在子宫中的存活时间。经过5次重复后，获得了活的克隆胎儿，直到怀孕14.5天；然而，即使我们重复核移植9次，它们也没有存活更长的时间。所有胎儿均表现为肠突出，胎盘扩张良好。将来自受精胚胎的胚胎干细胞与克隆胚胎聚集，从嵌合胚胎中获得具有大胎盘的足月后代。从GFP的表达来看，这些胎盘来自孤雌生殖细胞核。印记基因的表达模式和甲基化状态与其孤雌生殖起源相似，但Peg10的表达水平与正常胎盘相同。这些结果表明，通过重复几轮核移植对印记基因进行重新编程的能力对胎儿发育是有限的。然而，孤雌胚胎的胎盘在使用核移植技术发育时可以逃脱表观遗传调控，并可以支持胎儿发育到完全怀孕。
Mammalian parthenogenetic embryos invariably die in mid-gestation from imprinted gene defects and placental hypoplasia. Based on chimera experiments, trophoblastic proliferation is supposed to be inhibited in the absence of a male genome. Here, we show that parthenogenetic mouse embryonic cell nuclei can be reprogrammed by serial rounds of nuclear transfer without using any genetic modification. The durations of survival in uteri of cloned foetuses derived from green fluorescent protein (GFP)-labelled parthenogenetic cell nuclei were extended with repeated nuclear transfers. After five repeats, live cloned foetuses were obtained up to day 14.5 of gestation; however, they did not survive longer even when we repeated nuclear transfer up to nine times. All foetuses showed intestinal herniation and possessed well-expanded large placentas. When embryonic stem (ES) cells derived from fertilised embryos were aggregated with the cloned embryos, full-term offspring with large placentas were obtained from the chimeric embryos. Those placentas were derived from parthenogenetic cell nuclei, judging from GFP expression. The patterns of imprinted gene expression and methylation status were similar to their parthenogenetic origin, except for Peg10, which showed the same level as in the normal placenta. These results suggest that there is a limitation for foetal development in the ability to reprogramme imprinted genes by repeated rounds of nuclear transfer. However, the placentas of parthenogenetic embryos can escape epigenetic regulation when developed using nuclear transfer techniques and can support foetal development to full gestation.