ATF3 drives senescence by reconstructing accessible chromatin profiles.

Chromatin organization and transcriptional profiles undergo tremendous reordering during senescence. However, uncovering the regulatory mechanisms between chromatin reconstruction and gene expression in senescence has been elusive. Here, we depicted the landscapes of both chromatin accessibility and gene expression to reveal gene regulatory networks in human umbilical vein endothelial cell (HUVEC) senescence and found that chromatin accessibilities are redistributed during senescence. Particularly, the intergenic chromatin was massively shifted with the increased accessibility regions (IARs) or decreased accessibility regions (DARs), which were mainly enhancer elements. We defined AP-1 transcription factor family as being responsible for driving chromatin accessibility reconstruction in IARs, where low DNA methylation improved binding affinity of AP-1 and further increased the chromatin accessibility. Among AP-1 transcription factors, we confirmed ATF3 was critical to reconstruct chromatin accessibility to promote cellular senescence. Our results described a dynamic landscape of chromatin accessibility whose remodeling contributes to the senescence program, we identified that AP-1 was capable of reorganizing the chromatin accessibility profile to regulate senescence.