Chromatin topology and the timing of enhancer function at the <i>HoxD</i> locus
Eddie Rodríguez-Carballo, Lucille Lopez‐Delisle, Andréa Willemin, Leonardo Beccari, Sandra Gitto, Bénédicte Mascrez, Denis Duboule
Abstract
Significance Many genes important for vertebrate development are surrounded by multiple series of remote enhancer sequences. Such regulatory landscapes and their target genes are usually located within the same chromatin domains, which appears to constrain the action of these regulatory sequences and hence to facilitate enhancer–promoter recognition and gene expression. We used the HoxD locus to assess the impact of modifying the regulatory topology upon gene activation in space and time. A series of chromosomal rearrangements involving deletions and inversions reveals that the enhancer topology plays a role in the timing of gene activation. However, gene expression was often recovered subsequently, illustrating the intrinsic capacity of some enhancers to find their target promoters despite an apparently adverse chromatin topology.