Long‐distance signal transfer in transcriptionally active chromatin – how does it occur?

Gene transcription in eukaryotes is associated with conformational changes of a large area of chromatin adjacent to a gene. This rearrangement may involve the whole loop (topological domain) to which a given gene belongs. Regulatory events associated with activation or inactivation of transcription are found to act through relatively short nucleotide sequences, often located several thousand base pairs apart from gene. These sequences, termed enhancers may act independently on their distance from or orientation with respect to the gene. Both long‐range conformational rearrangements of chromatin and any long distance effects of enhancers may be associated with elastic torsional strain in DNA, arising in transcriptionally active chromatin loops. Enhancer effects, in particular, may be associated with conformational transitions in DNA competing for the energy deposited in the elastic spring of the DNA.