A YY1–INO80 complex regulates genomic stability through homologous recombination–based repair

Abstract

DNA damage repair is crucial for the maintenance of genome integrity and cancer suppression. We found that loss of the mouse transcription factor YY1 resulted in polyploidy and chromatid aberrations, which are signatures of defects in homologous recombination. Further biochemical analyses identified a YY1 complex comprising components of the evolutionarily conserved INO80 chromatin-remodeling complex. Notably, RNA interference-mediated knockdown of YY1 and INO80 increased cellular sensitivity toward DNA-damaging agents. Functional assays revealed that both YY1 and INO80 are essential in homologous recombination-based DNA repair (HRR), which was further supported by the finding that YY1 preferentially bound a recombination-intermediate structure in vitro. Collectively, these observations reveal a link between YY1 and INO80 and roles for both in HRR, providing new insight into mechanisms that control the cellular response to genotoxic stress.Genomic instability is a hallmark of cancer development and progression. Defects in DNA double-strand break (DSB) repair are believed to be responsible for chromosomal rearrangements and can be rectified by homologous recombination, which is particularly active in the S and G2 phases of the cell cycle, or by nonhomologous end joining (NHEJ), active in G1 phase 1,2 . Homologous recombination is an important mechanism for the repair of damaged chromosomes and damaged replication forks, and for several other aspects of chromosome maintenance 3 . Furthermore, impairment of homologous recombination is probably one of the underlying causes of breast, ovarian and other cancers 4,5 . INO80, a member of the Snf2p family of DNA-dependent ATPases, has been shown to positively regulate homologous recombination in a number of organisms [6][7][8] . The Ino80 complex is evolutionarily conserved, and components of the complex have been identified in mammalian cells 9 induces phosphorylation of histone H2A, and the yeast INO80 complex is known to be recruited directly to DSBs through an interaction with the phosphorylated histone H2A 7,8,10,11 ; however, the precise function of INO80 in DSB repair and its recruitment to the damage site are not completely understood 12 .Yin Yang-1 (YY1) is a zinc finger-containing Polycomb group (PcG) transcription factor that is essential in development [13][14][15][16] . Recently, a number of studies have shown that loss of YY1 increases the p53 protein level 17,18 , raising the possibility that YY1 may contribute to the regulation of genomic integrity. To investigate this possibility, we used genetic, biochemical and proteomic approaches. We discovered essential roles for YY1 in the cellular response to genotoxic stress and in the maintenance of chromosomal stability. Furthermore, we found multiple lines of evidence that link YY1 and the ATP-dependent chromatin-remodeling complex INO80 in DNA repair. We identified a YY1 complex containing components of the INO80 complex and confirmed this interaction of YY1 with components of the INO80 complex by ad...

The mINO80 chromatin remodeling complex is required for efficient telomere replication and maintenance of genome stability

“…IR-and UV-induced DNA damages persist in mIno80 ∆/∆ MEFs, suggesting that mIno80 is required for their efficient repair (Figure 3). In addition, we found that mIno80 is required for the generation of ssDNA to mediate HDR at sites of DSBs (Figure 4), in agreement with previous results showing that siRNA-mediated depletion of hIno80 impairs HDR [20,23].…”

“…As mIno80 promotes DNA repair and represses genome instability, we postulate that the mIno80 complex also plays a role in tumor prevention. This notion is supported by the observation that hIno80 and its associated protein YY-1 are required to maintain genome stability by promoting proper chromosome segregation [20,22]. We found that deletion of mIno80 severely compromised the tumorigenic potential of transformed mouse cell lines by reducing cellular proliferative capacity and the ability to form soft agar colonies in culture ( Figure 6).…”

“…Recent studies of mammalian INO80 functions by siRNA-mediated knockdown approaches revealed that this complex plays critical roles in the repair of DSBs and maintenance of genome stability [20][21][22][23][24]. However, little is known about INO80's function at mammalian telomeres.…”

Overexpression of a Chromatin Remodeling Factor, RSF-1/HBXAP, Correlates with Aggressive Oral Squamous Cell Carcinoma

“…At the molecular level, it has been demonstrated that regulation of nucleosome deposition is essential for transcriptional activation or repression, 28 -30 DNA replication, 31,32 DNA damage repair, 4,33,34 and cell cycle progression. [35][36][37] Chromatin remodeling factors that control DNA winding/unwinding cycles are therefore believed to be involved in these processes.…”

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

“…Yeast INO80 and SWR1 chromatin remodeling complexes interact with γ-H2A and facilitate DSB repair (van Attikum et al, 2007;Park et al, 2009). Wu and colleagues showed that knockdown models of human INO80, or of its binding partner YY1, increased cellular sensitivity toward DNAdamaging agents, and in their study they highlighted the essentiality of both INO80 and YY1 for HR repair (Wu, S. et al, 2007). However, a recent report indicated that H2A phosphorylation is dispensable for recruitment of the chromatin remodelers INO80 and SNF6 (a component of SWI/SNF) to DSB sites in yeast (Bennett et al, 2013), suggesting that the interaction with γ-H2AX may not be essential for directing the accumulation of histone remodelers at DSB damage sites.…”