期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2016
卷号：113
期号：51
页码：14492-14501
DOI：10.1073/pnas.1520945114
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceCloning cattle by somatic cell nuclear transfer (SCNT) is an agriculturally important technology and is also used as a model system for the study of mammalian development. The SCNT process is inefficient, typically yielding fewer than 10% live offspring. The majority of losses are the result of embryonic death, failure of the implantation process, and development of a defective placenta. A critical period is the implantation window, when survival of the conceptus depends on factors including genetics, epigenetics, and the communication between conceptus and the endometrium. Our study of gene expression in cloned conceptuses and endometrial tissues during the periimplantation period enhances understanding of the mechanisms that lead to pregnancy failure in SCNT cloning. The results have wide implications for cloning of other mammals. A major unresolved issue in the cloning of mammals by somatic cell nuclear transfer (SCNT) is the mechanism by which the process fails after embryos are transferred to the uterus of recipients before or during the implantation window. We investigated this problem by using RNA sequencing (RNA-seq) to compare the transcriptomes in cattle conceptuses produced by SCNT and artificial insemination (AI) at day (d) 18 (preimplantation) and d 34 (postimplantation) of gestation. In addition, endometrium was profiled to identify the communication pathways that might be affected by the presence of a cloned conceptus, ultimately leading to mortality before or during the implantation window. At d 18, the effects on the transcriptome associated with SCNT were massive, involving more than 5,000 differentially expressed genes (DEGs). Among them are 121 genes that have embryonic lethal phenotypes in mice, cause defects in trophoblast and placental development, and/or affect conceptus survival in mice. In endometria at d 18, <0.4% of expressed genes were affected by the presence of a cloned conceptus, whereas at d 34, [~]36% and <0.7% of genes were differentially expressed in intercaruncular and caruncular tissues, respectively. Functional analysis of DEGs in placental and endometrial tissues suggests a major disruption of signaling between the cloned conceptus and the endometrium, particularly the intercaruncular tissue. Our results support a "bottleneck" model for cloned conceptus survival during the periimplantation period determined by gene expression levels in extraembryonic tissues and the endometrial response to altered signaling from clones.
关键词：somatic cell nuclear transfer ; conceptus ; placentation ; conceptus–maternal communication
