Epigenetic marks in somatic chromatin are remodelled to resemble pluripotent nuclei by amphibian oocyte extracts.
Reprogramming pluripotency after nuclear transplantation shows that molecules in oocytes can remodel somatic chromatin to a stem cell state. Here we report on an ex-ovo system using axolotl oocyte extracts to remodel epigenetic marks of somatic chromatin. Molecules present in axolotl oocyte extracts induce the reduction of the overall levels of H3K9me3, HP1alpha and DNA methylation of somatic cells, and they increase the levels of H3K9ac. The levels of signal intensity detected in treated differentiated cells resemble those detected in embryonic stem cells, which are, in contrast, unaffected by these extracts. Analysis of specific genome sequences shows that somatic cells exposed to oocyte extracts undergo demethylation of LINE-1 repeats but Major Satellite repeats and the imprinted gene H19 remain unchanged. In addition, they induce demethylation of the Oct-4 promoter. Finally, the kinetics of activation of Oct-4 and Nanog expression from MEF nuclei treated in extracts suggests that these genes are subject to different levels of epigenetic control. The results demonstrate that axolotl oocyte extracts are a useful tool for studying epigenetic remodelling of somatic cells to a stem cell configuration, and for elucidating oocyte specific mechanisms of nuclear reprogramming.
Division of Animal Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, UK.
Yuhong
Y
Bian
Ramiro
R
Alberio
Cinzia
C
Allegrucci
Keith H
KH
Campbell
Andrew D
AD
Johnson
D000557:Ambystoma; D000818:Animals; D002454:Cell Differentiation / Q000235:genetics*; D002457:Cell Extracts / Q000494:pharmacology; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism*; D042002:Chromatin Assembly and Disassembly / Q000235:genetics*; D019175:DNA Methylation; D004276:DNA, Satellite / Q000378:metabolism; D044127:Epigenesis, Genetic / Q000187:drug effects; D005819:Genetic Markers; D020084:Long Interspersed Nucleotide Elements; D051379:Mice; D053652:Nuclear Transfer Techniques; D050814:Octamer Transcription Factor-3; D009865:Oocytes; D039904:Pluripotent Stem Cells / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D017422:Sequence Analysis, DNA
D002457:Cell Extracts; D002843:Chromatin; D004276:DNA, Satellite; D005819:Genetic Markers; D050814:Octamer Transcription Factor-3