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Updated: Aug 28, 2025

Analysis of Chromosome Segregation, Histone Acetylation, and Spindle Morphology in Horse Oocytes
Published on: May 11, 2017
Epigenetic dynamics of H4K20me3 modification during oocyte maturation and early reprogramming of somatic cell nuclear
Zhihui Liu1, Mingyang Li1, Yu Sun1
1Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University Nanjing 210046, Jiangsu, PR China.
Objective:
We examined the epigenetic dynamics of histone H4K20 trimethylation (H4K20me3), a repressive signature in heterochromatin, during goat oocyte meiosis and the reprogramming of somatic cell nuclear transfer (NT) embryos through the first three cell divisions.
Methods:
Following NT, oocytes were treated with parthenogenetic activation (PA), by 5 µM calcium ionophore A23187 for 5 min followed by incubation in 2.0 mM 6-dimethylaminopurine with 5 µg/mL cycloheximide for 4 h. NT embryos up to 8-celled stage were incubated with H4K20me3 antibody.
Results:
Immunofluorescence microscopy revealed the existence of a persistent H4K20me3 signature during oocyte maturation from germinal vesicle phase to metaphase I, anaphase I, telophase I, and metaphase II, with a gradual reduction in staining intensity. NT embryos at the 2-, 4- and 8-celled stage showed lower H4K20me3 intensity than PA and IVF embryos (P < 0.05).
Conclusion:
These results indicate that NT embryos exhibit insufficient H4K20me3 modification compared with IVF and PA embryos during early reprogramming, suggesting the existence of a resistant memory of differentiated cell nuclear architecture. These findings help unravel the epigenetic mechanism of histone H4K20me3 in goat nuclear transfer reprogramming.
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