Epigenetic reprogramming during early development in mammals.

摘要: Epigenetic modifications serve as an extension of the information content by which underlying genetic code may be interpreted. These mark genomic regions and act heritable stable instructions for specification chromatin organisation structure that dictate transcriptional states. In mammals, DNA methylation modification histones account major epigenetic alterations. Two cycles reprogramming have been characterised. During germ cell development, resets parent-of-origin based imprints restores totipotency to gametes. On fertilisation, second cycle is triggered resulting in asymmetric difference between parental genomes. Further asymmetry evident establishment first two lineages at blastocyst stage. This differentiative event sets characteristics derivatives inner mass (somatic) trophectoderm (extra-embryonic). It erasure subsequent re-tracing checkpoints pose most serious obstacles somatic nuclear transfer. Elaboration mechanisms these interactions will invaluable our fundamental understanding biological processes achieving substantial therapeutic advances.