Interplay of Epigenetics, Genome Rearrangement, and Environment During Development

Genome rearrangement, characterized by insertion, deletion, amplification, inversion, and/or transposition of DNA segments, during development has been observed in multiple cell types, such as, B-cell and T-cell lymphocytes, and non-mammalian organisms, such as ciliates. These genome restructuring processes are driven by epigenetic markings, including DNA methylation status, histone modification, and/or noncoding RNA transcription, which are modifiable by external and internal environments. In turn, the genome rearrangement establishes a new state of genomic control via epigenetic marks regulating expressions of genes in specific cell types or stages. Epigenetic reprogramming occurs during mammalian development. Direct evidence of ontogeny-driven genome rearrangement in mammals at organismal level is still missing. It is arguable that genome rearrangement, which introduces genome diversity, is a driving force of mammalian development. There are some indirect evidence supporting that such genome rearrangement occurs at organismal level.