title: Nuclear transfer-derived epiblast stem cells are transcriptionally and epigenetically distinguishable from their fertilized-derived counterparts.
abstract: Mouse embryonic pluripotent stem cells can be obtained from the inner cell mass at the blastocyst stage (embryonic stem cells, ESCs) or from the late epiblast of postimplantation embryos (epiblast stem cells, EpiSCs). During normal development, the transition between these two stages is marked by major epigenetic and transcriptional changes including DNA de novo methylation. These modifications represent an epigenetic mark conserved in ESCs and EpiSCs. Pluripotent ESCs derived from blastocysts generated by nuclear transfer (NT) have been shown to be correctly reprogrammed. However, NT embryos frequently undergo abnormal development. In the present study, we have examined whether pluripotent cells could be derived from the epiblast of postimplantation NT embryos and whether the reprogramming process would affect the epigenetic changes occurring at this stage, which could explain abnormal development of NT embryos. We showed that EpiSCs could be derived with the same efficiency from NT embryos and from their fertilized counterparts. However, gene expression profile analyses showed divergence between fertilized- and nuclear transfer-EpiSCs with a surprising bias in the distribution of the differentially expressed genes, 30% of them being localized on chromosome 11. A majority of these genes were downregulated in NT-EpiSCs and imprinted genes represented a significant fraction of them. Notably, analysis of the epigenetic status of a downregulated imprinted gene in NT-EpiSCs revealed complete methylation of the two alleles. Therefore, EpiSCs derived from NT embryos appear to be incorrectly reprogrammed, indicating that abnormal epigenetic marks are imposed on cells in NT embryos during the transition from early to late epiblast.
authors.affiliation: Sino-French Laboratory LABIOCEM, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Julien
authors.initials: J
authors.lastname: Maruotti
authors.forename: Xiang Peng
authors.initials: XP
authors.lastname: Dai
authors.forename: Vincent
authors.initials: V
authors.lastname: Brochard
authors.forename: Luc
authors.initials: L
authors.lastname: Jouneau
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Amélie
authors.initials: A
authors.lastname: Bonnet-Garnier
authors.forename: Hélène
authors.initials: H
authors.lastname: Jammes
authors.forename: Ludovic
authors.initials: L
authors.lastname: Vallier
authors.forename: I Gabrielle M
authors.initials: IG
authors.lastname: Brons
authors.forename: Roger
authors.initials: R
authors.lastname: Pedersen
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Renard
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhou
authors.forename: Alice
authors.initials: A
authors.lastname: Jouneau
mesh_terms: D000818:Animals; D015415:Biomarkers; D002460:Cell Line; D049109:Cell Proliferation; D048430:Cell Shape; D044127:Epigenesis, Genetic; D005307:Fertilization in Vitro; D020869:Gene Expression Profiling; D005855:Germ Layers / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D053652:Nuclear Transfer Techniques; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*
chemical_list: D015415:Biomarkers