epigenetics

In human DNA, 5-methylcytosine is found in approximately 1.5% of genomic DNA. In somatic cells, 5-mC occurs almost exclusively in the context of paired symmetrical methylation of a CpG site. An exception to this is seen in embryonic stem (ES) cells, where a substantial amount of 5-mC is also observed in non-CpG contexts. In the bulk of genomic DNA, most CpG sites are heavily methylated while CpG islands (sites of CpG clusters) in germ-line tissues and located near promoters of [more…]

Robust and versatile technologies that enable optical modulation of transcription in the mammalian endogenous genome have been difficult to achieve for a while. To solve this problem, scientists at the Broad Institute of MIT and Harvard developed light-inducible transcriptional effectors (LITEs) — an optogenetic two-hybrid system integrating the TALE DNA-binding domain with a light-sensitive cryptochrome 2 protein and its partner CIB1 from the Arabidopsis thaliana plant. LITEs can be customized to target many endogenous genomic loci and can be quickly [more…]