Flagging up new gene switches

The human genome contains barely more protein-coding genes than that of a fruit fly: May 2016

The human genome contains barely more protein-coding genes than that of a fruit fly. The more complex development and behaviour of mammals lies, not in the number of their genes, but in how those genes are controlled. The genome of mammals is full of switches that control when, where and how genes are switched on. These control switches - called enhancers -  have previously been identified by a chemical flag that is added to the chromatin of enhancers when they are active (switched on). In chromatin, DNA is wrapped around a ball of proteins called histones to package up the genome. The previously known flag at enhancers is on the tail of histone molecules that protrude from chromatin and is thought to act as signal to other proteins. However Pradeepa and colleagues at the MRC Human Genetics Unit, together with a colleague at the Institut of Functional Epigenetics in Munich, have found a new chemical flag on histones that identifies a whole new set of enhancer elements in the genome. This chemical mark acts to physically disrupt the structure of chromatin. Not only does this work improve our understanding of how genes are controlled, but it is also important for understanding how the human genome impacts on health and disease. Most of the genetic variation in the human population that affects the risk of developing common diseases such as; cancer, stroke, diabetes, arthritis etc, is not in genes themselves, but in the enhancer elements that switch genes on.

Histone H3 globular domain acetylation identifies a new class of enhancers

Madapura M Pradeepa, Graeme R Grimes, Yatendra Kumar, Gabrielle Olley, Gillian C A Taylor, Robert Schneider and Wendy A Bickmore

Nature Genetics, 2016  http://dx.doi.org/10.1038/ng.3550