FIGURE 2.

The 3-dimensional organization of chromatin plays an important role in regulating gene expression. A–B, Illustrations of different ways in which the formation of DNA loops mediated by genome organizing complexes (purple) can regulate gene expression. In A, a regulatory element (RE) that activates gene expression, such as an enhancer, interacts with the promoter of gene Y which, following binding of transcription factors, results in enhancement of transcription. In B, the RE confers a repressive activity, possibly by directing DNA methylation (yellow circles) of gene Y’s promoter, or by facilitating binding of chromatin remodeling proteins that promote repressive histone modifications (red hexagons). This represses transcription of gene Y.