Precise recapitulation of methylation change in early cloned embryos.
Change of DNA methylation during preimplantation development is very dynamic, which brings this term to the most attractive experimental target for measuring the capability of cloned embryo to reprogram its somatic genome. However, one weak point is that the preimplantation stage carries little information on genomic sequences showing a site-specific re-methylation after global demethylation; these sequences, if any, may serve as an advanced subject to test how exactly the reprogramming/programming process is recapitulated in early cloned embryos. Here, we report a unique DNA methylation change occurring at bovine neuropeptide galanin gene sequence. The galanin gene sequence in early bovine embryos derived by in vitro fertilization (IVF) maintained a undermethylated status till the morula stage. By the blastocyst, certain CpG sites became methylated specifically, which may be an epigenetic sign for the galanin gene to start a differentiation programme. The same sequence was moderately methylated in somatic donor cell and, after transplanted into an enucleated oocyte by nuclear transfer (NT), came rapidly demethylated to a completion, and then, at the blastocyst stage, re-methylated at exactly the same CpG sites, as observed so in normal blastocysts. The precise recapitulation of normal methylation reprogramming and programming at the galanin gene sequence in bovine cloned embryos gives a cue for the potential of cloned embryo to superintend the epigenetic states of foreign genome, even after global demethylation.
Kang
Yong-Kook
YK
Laboratory of Development and Differentiation, Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea. ykkang@kribb.re.kr
Yeo
Seungeun
S
Kim
Seok-Ho
SH
Koo
Deog-Bon
DB
Park
Jung Sun
JS
Wee
Gabbine
G
Han
Jee-Soo
JS
Oh
Keon Bong
KB
Lee
Kyung-Kwang
KK
Han
Yong-Mahn
YM
D000818:Animals; D001755:Blastocyst / Q000378:metabolism*; D002417:Cattle; D019976:Cloning, Organism; D004247:DNA / Q000378:metabolism*; D019175:DNA Methylation; D019004:Galanin / Q000235:genetics; D007438:Introns; D053652:Nuclear Transfer Techniques; D016133:Polymerase Chain Reaction; D013997:Time Factors
D019004:Galanin; D004247:DNA