Disruption of imprinted gene methylation and expression in cloned preimplantation stage mouse embryos.
Cloning by somatic cell nuclear transfer requires that epigenetic information possessed by the donor nucleus be reprogrammed to an embryonic state. Little is known, however, about this remodeling process, including when it occurs, its efficiency, and how well epigenetic markings characteristic of normal development are maintained. Examining the fate of epigenetic information associated with imprinted genes during clonal development offers one means of addressing these questions. We examined transcript abundance, allele specificity of imprinted gene expression, and parental allele-specific DNA methylation in cloned mouse blastocysts. Striking disruptions were seen in total transcript abundance and allele specificity of expression for five imprinted genes. Only 4% of clones recapitulated a blastocyst mode of expression for all five genes. Cloned embryos also exhibited extensive loss of allele-specific DNA methylation at the imprinting control regions of the H19 and Snprn genes. Thus, epigenetic errors arise very early in clonal development in the majority of embryos, indicating that reprogramming is inefficient and that some epigenetic information may be lost.
Howard Hughes Medical Institute and Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
Mellissa R W
MR
Mann
Young Gie
YG
Chung
Leisha D
LD
Nolen
Raluca I
RI
Verona
Keith E
KE
Latham
Marisa S
MS
Bartolomei
D022981:Allelic Imbalance / Q000235:genetics; D000818:Animals; D001755:Blastocyst / Q000378:metabolism*; D019976:Cloning, Organism; D019175:DNA Methylation; D044127:Epigenesis, Genetic / Q000235:genetics*; D005260:Female; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D018392:Genomic Imprinting; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D053652:Nuclear Transfer Techniques