小鼠核移植胚胎胎盘发育表观遗传缺陷的对比研究

体细胞核移植（SCNT）胚胎胎盘往往异常增大，是胚胎发育率低的重要因素之一，也阻碍了SCNT的应用。但造成SCNT胎盘过大的机制并不清楚，且目前缺乏不破坏基因组又有效挽救胎盘的方法。我们的研究鉴定并揭示转录因子DUX一定程度上缩小SCNT胎盘。在此基础上，本项目拟研究自然受精、SCNT、过表达Dux或敲降Dnmt3a/b的SCNT胎盘，测定其单细胞转录与染色质开放，阐述SCNT胎盘不同类型细胞染色质重塑的异常及过表达Dux或敲降Dnmt3a/b对其挽救的模式与机制。结合早期胚胎不同时期的表观数据，鉴定造成SCNT胎盘异常的特定区域表观修饰与关键转录因子，并揭示其调控机制。再通过CRISPR-表观修饰酶或转录因子靶向修复SCNT胚胎中异常表观修饰，实现对胎盘缺陷的挽救并提高SCNT胚胎发育率。本项目成果将完善SCNT效率的调控机制，促进其在基础研究、畜牧业育种与濒危物种保护中的应用。

The placenta of somatic cell nuclear transfer (SCNT) embryos is often abnormally large, which is one of the important factors for low embryo development rate and hinders the application of SCNT. However, the mechanisms responsible for the oversized placenta in SCNT are not clear, and there is a lack of methods to effectively rescue the placenta without preserving the integrity the genome. Our study identifies and reveals that the transcription factor DUX shrinks the SCNT placenta to some extent. Based on this, we propose to study SCNT placentas with natural fertilization, SCNT, overexpression of Dux or knockdown of Dnmt3a/b, to depict their single-cell transcription and chromatin opening, and to elucidate the abnormalities of chromatin remodeling in different cell types of SCNT placentas and and mechanism of their rescue by overexpression of Dux or knockdown of Dnmt3a/b. By combining epigenetic data from different periods of early embryos, we could identify specific regional epigenetic modifications and key transcription factors causing SCNT placenta abnormalities and reveal their regulatory mechanisms. The abnormal epigenetic modifications in SCNT embryos will then be targeted by CRISPR-epigenetic modifying enzymes or transcription factors to repair the abnormal epigenetic modifications and to achieve rescue of placental defects and to finally improve the developmental rate of SCNT embryos. The results of this project will improve the efficiency of SCNT and broaden its application in scientific research, livestock breeding and endangered species conservation.