Somatic cell nuclear transfer (SCNT) has great potential for agricultural applications, generation of medical model animals, transgenic farm animals or generating human embryonic stem cells for treatment of human diseases. Cloned animals derived from somatic cells have been generated in several mammal species, but there are still some unsolved problems with current cloning technology, for example, the low efficiency of animal cloning and the abnormal development of cloned animals. One critical factor of these developmental failures of cloned embryos is the aberrant epigenetic reprogramming. This review focuses on DNA methylation and histone modifications and the relationship between these two epigenetic modifications and the development of cloned embryos. Understanding the mechanisms of epigenetic regulation will be useful to solve the technical problems of SCNT and enable better applications of this technology.
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