ATP, Mg2+, nuclear phase separation, and genome accessibility

Misregulation of the processes controlling eukaryotic gene expression can result in disease. Gene expression is influenced by the surrounding chromatin; hence the nuclear environment is also of vital importance. Recently, understanding of chromatin hierarchical folding has increased together with the discovery of membrane-less organelles which are distinct, dynamic liquid droplets that merge and expand within the nucleus. These 'sieve'-like regions may compartmentalize and separate functionally distinct regions of chromatin. This article aims to discuss recent studies on nuclear phase within the context of poly(ADP-ribose), ATP, and Mg2+ levels, and we propose a combinatorial complex role for these molecules in phase separation and genome regulation. We also discuss the implications of this process for gene regulation and discuss possible strategies to test this.The experimental work mentioned was supported by the European Research Council (Project 4D Genome 609989), the Ministerio de Economía y Competitividad (project G62426937), and the Generalitat de Catalunya (project Agència de Gestió d'Ajuts Universitaris i de Recerca SGR 575)