Lineage specification and pluripotency revealed by transcriptome analysis from oocyte to blastocyst in pig. Lineage specification and pluripotency revealed by transcriptome analysis from oocyte to blastocyst in pig

The inner cell mass in blastocyst is the origin of all the somatic and germ cells in mammals, and of pluripotent stem cells in vitro. As the conserved principles between pig and human, here we performed comprehensive single-cell RNA-seq for porcine early embryos from oocyte to early blastocyst. We show the specification of inner cell mass and trophectoderm in morula, and the molecular signature of the precursors. We demonstrate the existence of naïve pluripotency signature in morula and inner cell mass of early blastocyst, and the specific pluripotent genes and the activity of signalling pathways highlight the characteristics of the naïve pluripotency. We observe absence of dosage compensation with respect to X-chromosome in morula, and incomplete dosage compensation in early blastocyst. However, the dynamics of dosage compensation may be independent on the expression of XIST induced X-chromosome inactivation. Our study describes molecular landmarks of embryogenesis in pig that will provide a better strategy for derivation of porcine pluripotent stem cells and improve the research in regenerative medicine. Overall design: scRNA-seq of pig preimplantation embryos

囊胚（blastocyst）内的内细胞团（inner cell mass）是哺乳动物体内所有体细胞、生殖细胞以及体外多能干细胞的起源。鉴于猪与人类之间的保守进化特性，本研究针对猪从卵母细胞到早期囊胚的早期胚胎开展了全面的单细胞RNA测序（single-cell RNA-seq, scRNA-seq）。本研究揭示了桑椹胚（morula）内细胞团与滋养层细胞（trophectoderm）的特化过程，及其前体细胞的分子特征；证实了桑椹胚与早期囊胚内细胞团中存在初始多能性（naïve pluripotency）特征，特异性多能基因的表达与信号通路活性共同凸显了初始多能性的核心特质。研究团队观察到，桑椹胚阶段不存在X染色体剂量补偿，而早期囊胚阶段的剂量补偿并不完全；不过，剂量补偿的动态变化可能并不依赖于XIST诱导的X染色体失活（X-chromosome inactivation）的表达。本研究阐明了猪胚胎发育的分子标志性事件，可为猪多能干细胞的诱导建系提供更优化的策略，同时推动再生医学领域的相关研究。实验设计概述：猪植入前胚胎的单细胞RNA测序。