DNA methylation at a bovine alpha satellite I repeat CpG site during development following fertilization and somatic cell nuclear transfer.
DNA methylation at a bovine alpha satellite I repeat CpG site during development following fertilization and somatic cell nuclear transfer.
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DOI：
10.1371/journal.pone.0055153
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Wells DN
中科院分区：
文献类型：
--
作者：
Couldrey C;Wells DN
不完全的表观遗传重编程被认为是体细胞核移植（SCNT）后发育成功率低的原因。在这里，我们描述了在人工授精（AI）或体外受精（IVF）和SCNT产生的牛发育过程中，α卫星I CpG位点（αsatI-5）DNA甲基化的表观遗传重编程。定量甲基化分析表明，SCNT供体细胞在αsatI-5高度甲基化，产生的SCNT囊胚比IVF囊胚显示出显著更多的甲基化。在植入时，在αsatI-5的滋养层组织中未观察到SCNT和AI之间的甲基化差异，然而，在该时间点，与AI对照相比，SCNT胚胎显著高甲基化。植入后，AI胎盘组织中αsatI-5的DNA甲基化降低，但SCNT胎盘组织中没有。与胎盘相反，在发育过程中，肾上腺、肾脏和肌肉组织中αsatI-5甲基化的比例仍然很高。体细胞组织中平均甲基化比例的差异小于胎盘组织，但平均而言，SCNT体细胞组织在αsatI-5处高度甲基化。尽管所有公牛的精子在αsatI-5位点的甲基化程度低于体细胞组织，但与对照公牛相比，克隆公牛精子中该位点平均仍保持高甲基化。这种发育时间过程证实，表观遗传重编程确实发生，至少在某种程度上，以下SCNT。然而，在SCNT囊胚和细胞衍生物中观察到的甲基化水平升高意味着卵母细胞中没有足够的时间或足够的适当重编程因子来确保完全重编程。该CpG位点的不完全重编程可能是SCNT成功率低的一个因素，但更可能代表不完全重编程的冰山一角。在方案确保分化体细胞的表观遗传特征被重置为类似全能性的状态之前，SCNT的效率可能会保持较低。
Incomplete epigenetic reprogramming is postulated to contribute to the low developmental success following somatic cell nuclear transfer (SCNT). Here, we describe the epigenetic reprogramming of DNA methylation at an alpha satellite I CpG site (αsatI-5) during development of cattle generated either by artificial insemination (AI) or in vitro fertilization (IVF) and SCNT. Quantitative methylation analysis identified that SCNT donor cells were highly methylated at αsatI-5 and resulting SCNT blastocysts showed significantly more methylation than IVF blastocysts. At implantation, no difference in methylation was observed between SCNT and AI in trophoblast tissue at αsatI-5, however, SCNT embryos were significantly hyper-methylated compared to AI controls at this time point. Following implantation, DNA methylation at αsatI-5 decreased in AI but not SCNT placental tissues. In contrast to placenta, the proportion of methylation at αsatI-5 remained high in adrenal, kidney and muscle tissues during development. Differences in the average proportion of methylation were smaller in somatic tissues than placental tissues but, on average, SCNT somatic tissues were hyper-methylated at αsatI-5. Although sperm from all bulls was less methylated than somatic tissues at αsatI-5, on average this site remained hyper-methylated in sperm from cloned bulls compared with control bulls. This developmental time course confirms that epigenetic reprogramming does occur, at least to some extent, following SCNT. However, the elevated methylation levels observed in SCNT blastocysts and cellular derivatives implies that there is either insufficient time or abundance of appropriate reprogramming factors in oocytes to ensure complete reprogramming. Incomplete reprogramming at this CpG site may be a contributing factor to low SCNT success rates, but more likely represents the tip of the iceberg in terms of incompletely reprogramming. Until protocols ensure the epigenetic signature of a differentiated somatic cell is reset to a state resembling totipotency, the efficiency of SCNT is likely to remain low.
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影响因子：
3.6
作者：
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通讯作者：
Piedrahita, JA
影响因子：
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