Geneviève Almouzni, Alberto Gatto, Audrey Forest, Jean-Pierre Quivy, Guillermo A. Orsi, Zachary A. Gurard-Levin, Mickaël Garnier, Judith Miné-Hattab, Bassam Hajj, Ekaterina Boyarchuk, Camille Clément, Dynamique du noyau [Institut Curie], Institut Curie [Paris]-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut Curie [Paris], Université Paris sciences et lettres (PSL), Sorbonne Université - Faculté de Médecine (SU FM), Sorbonne Université (SU), Laboratoire Physico-Chimie Curie [Institut Curie] (PCC), and Institut Curie [Paris]-Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
DNA replication is a challenge for the faithful transmission of parental information to daughter cells, as both DNA and chromatin organization must be duplicated. Replication stress further complicates the safeguard of epigenome integrity. Here, we investigate the transmission of the histone variants H3.3 and H3.1 during replication. We follow their distribution relative to replication timing, first in the genome and, second, in 3D using super-resolution microscopy. We find that H3.3 and H3.1 mark early- and late-replicating chromatin, respectively. In the nucleus, H3.3 forms domains, which decrease in density throughout replication, while H3.1 domains increase in density. Hydroxyurea impairs local recycling of parental histones at replication sites. Similarly, depleting the histone chaperone ASF1 affects recycling, leading to an impaired histone variant landscape. We discuss how faithful transmission of histone variants involves ASF1 and can be impacted by replication stress, with ensuing consequences for cell fate and tumorigenesis., Epigenetic modifications are a key contributor to cell identity, and their propagation is crucial for proper development. Here the authors use a super-resolution microscopy approach to reveal how histone variants are faithfully transmitted during genome duplication, and reveal an important role for the histone chaperone ASF1 in the redistribution of parental histones.