Epigenetic Entropy: Yardstick for Measuring Cancer Risk
An earlier post from March described the epigenome, the set of modifications of DNA and chromatin which provide control of gene regulatory networks needed to guide cellular differentiation during development and then maintain stable cellular phenotype in mature tissues. The epigenome, visualized in cell microscopy as nuclear euchromatin and heterochromatin, are chromatin states which either permit or inhibit ‘reading’ of genetic information through control of the access of polymerase enzymes to conduct DNA transcription. This hierarchical control over gene expression affecting the accessibility of RNA polymerases for transcription of specific sets of genes termed a gene network and acts to establish cell phenotype. This regulation allows for flexibility in phenotypic expression permitting the reversal of cell fate from a differentiated towards an undifferentiated state needed for example in tissue response to injury, termed lineage plasticity . Plasticity is a key concept in understan...