The Ino80 chromatin-remodeling enzyme regulates replisome function and stability

Abstract

Previous studies have demonstrated essential roles for ATP-dependent chromatin-remodeling and chromatin-modifying enzymes in gene transcription and DNA repair, but few studies have addressed how the replication machinery deals with chromatin. Here we show that the Ino80 remodeling enzyme is recruited to replication origins as cells enter S phase. Inducible degradation of Ino80 shows that it is required continuously for efficient progression of forks, especially when cells are confronted with low levels of replication stress. Furthermore, we show that stalling of replication forks in an ino80 mutant is a lethal event, and that much of the replication machinery dissociates from the stalled fork. Our data indicate that the chromatin-remodeling activity of Ino80 regulates efficient progression of replication forks and that Ino80 has a crucial role in stabilizing a stalled replisome to ensure proper restart of DNA replication.

Chromatin modification and NBS1: their relationship in DNA double-strand break repair

“…INO80-deficient mammalian cells show sensitivity to hydroxyurea, and are defective in both S-phase progression and recovery from replication stress (Hur et al, 2010;Min et al, 2013;Vassileva et al, 2014). Enrichment of INO80 at stalled replication forks has been detected in yeast by ChIP analysis (Papamichos-Chronakis and Peterson, 2008;Shimada et al, 2008). Furthermore, yeast lacking in functions of both INO80 and ISW2 cannot recover from the S-phase checkpoint (Au et al, 2011).…”

Nucleosome assembly and epigenetic inheritance

“…Other evidence showed that ISWI type nucleosome remodeling complex SNF2h is recruited to replication fork by WTSF, RNAi mediated knock down of SNF2h or WTSF caused reduction of DNA replication efficiency during S phase (Poot et al, 2004). In S. cerevisia INO80 complex is enriched in replication origins and stalled replication forks under replicative stress (Papamichos-Chronakis and Peterson, 2008;Vincent et al, 2008). Furthermore, mutation of INO80 leads to loss of replisome proteins under replicative stress (Papamichos-Chronakis and Peterson, 2008).…”

“…In S. cerevisia INO80 complex is enriched in replication origins and stalled replication forks under replicative stress (Papamichos-Chronakis and Peterson, 2008;Vincent et al, 2008). Furthermore, mutation of INO80 leads to loss of replisome proteins under replicative stress (Papamichos-Chronakis and Peterson, 2008).…”

Keeping chromatin quiet

“…2,3 To plough through chromatin the replication machinery needs to mobilize and evict nucleosomes and there is evidence that nucleosome remodeling helps to clear the path for efficient progression of the replication fork. [4][5][6] Remodeling may also be involved in the initiation of replication and origin definition, although less is known about this aspect. 2,7 Behind the replication fork, nucleosome remodeling contributes to the reformation of higher order chromatin structures.…”

“…[24][25][26][27][28][29] Depletion of SMARCAD1 in human cancer cell lines leads to the global accumulation of acetylated histones H3 and H4, a stalled replication forks. 5,[11][12][13] The ACF complex, consisting of the ATPase SNF2h and Acf1, appears to facilitate the progression of replication through highly condensed mammalian chromatin; its depletion causes a delay in S-phase progression that is reversible upon chromatin decondensation. 4 This suggests a function for ACF in establishing an accessible chromatin structure ahead of the replication machinery.…”