Chromatin structure mutes enhancer activity

In early embryos it is not possible to distinguish between arms and legs: their developmental precursors are virtually identical. Dynamic changes in the 3D structure of the chromatin in the leg precursor cells bring the Pen enhancer into spatial proximity to the Pitx1 gene, thus enabling the activation of this critical gene specifically in the future leg. As a result, forelimb and hindlimb buds subsequently differentiate from each other and produce arms and legs, respectively. This surprising molecular mechanism has been discovered by scientists around Stefan Mundlos and Guillaume Andrey from the Max Planck Institute for Molecular Genetics and the Charitè-Universitätsmedizin Berlin. (Mehr in: Pressemitteilungen – idw – Informationsdienst Wissenschaft)