Transcription-driven cohesin accumulation is associated with secretory phenotype of senescence [HiC]

Senescence is a stable form of cell cycle arrest that is triggered in response to various pathophysiological stimuli. The three-dimensional structure of senescent cells has been previously characterised, mostly in terms of macro-domains or changes between large heterochromatic regions. In the present body of work, using a combination of HiC and targetted Capture Hi-C, we aimed to investigate the association between gene expression and local chromatin structure in senescence, particularly focusing on enhancer-promoter (EP) interactions. We show that many EP contacts are rewired in RAS-induced Senescence compared to ‘normal’, growing cells and that these are associated with cohesin binding changes and possible loop re-organisation. The genes affected by altered chromatin interactions correspond to the two main axes of senescence gene regulation: cell cycle and inflammation. Our findings are potentially relevant during ageing and in cancers with cohesin mutations, where cell cycle and inflammation are also deregulated. HiC and Capture HiC of growing and (RAS-induced) senescent IMR90 fibroblasts