The mammalian INO80 chromatin remodeling complex is required for replication stress recovery

Abstract

A number of studies have implicated the yeast INO80 chromatin remodeling complex in DNA replication, but the function of the human INO80 complex during S phase remains poorly understood. Here, we have systematically investigated the involvement of the catalytic subunit of the human INO80 complex during unchallenged replication and under replication stress by following the effects of its depletion on cell survival, S-phase checkpoint activation, the fate of individual replication forks, and the consequences of fork collapse. We report that INO80 was specifically needed for efficient replication elongation, while it was not required for initiation of replication. In the absence of the Ino80 protein, cells became hypersensitive to hydroxyurea and displayed hyperactive ATR-Chk1 signaling. Using bulk and fiber labeling of DNA, we found that cells deficient for Ino80 and Arp8 had impaired replication restart after treatment with replication inhibitors and accumulated double-strand breaks as evidenced by the formation of γ-H2AX and Rad51 foci. These data indicate that under conditions of replication stress mammalian INO80 protects stalled forks from collapsing and allows their subsequent restart.

ATP-dependent chromatin remodeling during mammalian development

“…Finally, INO80 is required for meiotic recombination during spermatogenesis (Serber et al, 2015). Conditional spermatogonial mutation of Ino80 before meiosis results in impaired synapse formation and double-strand break defects, consistent with its role in DNA replication and DNA damage repair processes (Kato et al, 2012;Vassileva et al, 2014).…”

Understanding nucleosome dynamics and their links to gene expression and DNA replication

“…INO80 also has roles beyond H2A.Z–H2B dimer exchange at the +1 and the −1 nucleosomes. INO80 is involved in DNA replication elongation, implicating it in general nucleosome mobilization that promotes DNA accessibility for replication factors 58 . INO80 and its partners are also involved in DNA damage repair 59 , which is likely to resolve the inhibitory effect of nucleosomes on the repair proteins 60 .…”

“…Many chromatin remodellers have the ability to respond to cell stresses and can be triggered on demand to dynamically restructure the chromatin landscape 14,80,81 . In vivo , these chromatin remodellers appear to be enriched at specific nucleosome positions relative to genomic regions such as TSSs and origins of replication, and they possess both redundant and distinct functionality 25,58,79 .…”

Common Chemical Inductors of Replication Stress: Focus on Cell‐Based Studies

“…The most commonly used concentrations are around 2 mM. HU is used for cell cycle synchronization [269], replication fork stability studies [249,252], studies of recovery mechanisms after the release of RS [242] and checkpoint responses [241]. Lower concentrations are used for RS induction [254], induction of senescence [74], apoptosis [257], and repair pathways induction [217].…”