In eukaryotes, transcription proceeds through sequence-specific and context-dependent mechanisms. It has long been observed that the expression of a gene can change when it is translocated to an ectopic site of the genome, a phenomenon known as position effect. For genes transplanted near a centromere, invasion by heterochromatin was proposed as the mechanism of silencing. The recent discovery of additional chromatin types suggests that similar effects may take place away from the centromeres. Here we show that position effects are predominantly driven by spatial contacts with active genes, and more particularly with their terminators. By measuring the expression of ~ 85,000 integrated reporters, we identified the best predictors of expression as chromosomal contacts with the promoters and terminators of active genes. Surprisingly, the chromatin composition at the insertion site and the contacts with enhancers were less informative. These results are substantiated by the existence of ‘paradoxical’ domains, rich in euchromatic features and enhancers, but where the reporters are expressed at low level due to a deficit of interactions with promoters and terminators. Overall our results suggest that the role of contacts with promoters and terminators in gene expression was underappreciated. Our results also provide a mechanism to explain the aggregation of housekeeping genes on Drosophila chromosomes and cast new perspectives on the evolution of genome architectures.
EU Life and the Babraham Institute
EU-LIFE is an alliance of European life science research centers that have joined forces to support, collaborate and strengthen scientific research in Europe, working together to achieve advancement and further understanding in Life Sciences.
The growing consortium currently consists of 13 partner Institutes and over 7,000 scientific staff with the Babraham Institute, currently the only UK representative, joining in 2013.
As part of the collaboration, the Babraham Institute are now proud to host a series of lectures to highlight and support the latest research from fellow members.
If you would like to attend one of our EU Life Lectures, please use the "Contact Us" link below to express interest and arrange site access.