Spatial organization impacts function

Abstract

Genome Organization Genomes are organized into topologically associating domains (TADs), which concentrate chromatin-chromatin interactions and modulate gene expression. Using the mouse X chromosome–inactivation center (XIC) as a genetic model, van Bemmel et al. quantified the extent to which TADs regulate gene transcription. Xist and Tsix are two noncoding RNAs that overlap in the same genetic locus but are transcribed from opposite directions and thus are sense:antisense. By swapping promoters into each other's TAD and measuring the resulting expression kinetics of Xist and Tsix , the authors showed that spatial partitioning of promoters was essential to ensure the correct developmental timing of X inactivation by XIC. Nat. Genet. 51 , 1024 (2019).