RT Journal Article SR Electronic T1 The Drosophila Dosage Compensation Complex activates target genes by chromosome looping within the active compartment JF bioRxiv FD Cold Spring Harbor Laboratory SP 101634 DO 10.1101/101634 A1 Tamás Schauer A1 Yad Ghavi-Helm A1 Tom Sexton A1 Christian Albig A1 Catherine Regnard A1 Giacomo Cavalli A1 Eileen E M Furlong A1 Peter B Becker YR 2017 UL http://biorxiv.org/content/early/2017/01/19/101634.abstract AB X chromosome dosage compensation in Drosophila requires chromosome-wide coordination of gene activation. The male-specific-lethal dosage compensation complex (DCC) identifies X chromosomal High Affinity Sites (HAS) from which it boosts transcription. A sub-class of HAS, PionX sites, represent first contacts on the X. Here, we explored the chromosomal interactions of representative PionX sites by high-resolution 4C and determined the global chromosome conformation by Hi-C in sex-sorted embryos. Male and female X chromosomes display similar nuclear architecture, concordant with clustered, constitutively active genes. PionX sites, like HAS, are evenly distributed in the active compartment and engage in short- and long-range interactions beyond compartment boundaries. By de novo induction of DCC in female cells, we monitored the extent of activation surrounding PionX sites. This revealed a remarkable range of DCC action not only in linear proximity, but also at megabase distance if close in space, suggesting that DCC profits from pre-existing chromosome folding to activate genes.