Temafloxacin hydrochloride mg Our data are consistent with a

Our data are consistent with a role for RAD52 in BIR. Conventional BIR in yeast requires both Rad51 and Rad52 for homology-mediated template switching. In contrast, the microhomology-driven branch of BIR, MMBIR, can, under certain circumstances, be Rad51 independent (Anand et al., 2013, Hastings et al., 2009, Ottaviani et al., 2014, Sakofsky et al., 2015). Moreover, in yeast, some Rad52-dependent events involving annealing of regions of homology, such as would occur during BIR (Anand et al., 2013, Hastings et al., 2009, Mott and Symington, 2011), create DNA substrates that can be resolved efficiently by MUS81-EME1 (Gaillard et al., 2003, Osman et al., 2003). Both BIR and MMBIR require Pol32, whereas HR-mediated gene conversion does not (Donnianni and Symington, 2013, Hicks et al., 2010, Lydeard et al., 2007, Lydeard et al., 2010, Mayle et al., 2015, Sakofsky et al., 2015). Based on these considerations, therefore, we propose that MiDAS most likely occurs via a RAD51-independent MMBIR process in human cells. Given that RAD51-independent MMBIR requires much less homology (1–6 nucleotides) for template switching (Hastings et al., 2009, Ottaviani et al., 2014), this process would be optimal during the narrow time window in early mitosis when MiDAS occurs, as it negates the need for extensive DNA end resection and Rad51-driven homology searching. In the context of a collapsed replication fork, where the sister Temafloxacin hydrochloride mg is in very close proximity, an extensive homology search is unnecessary and could even be undesirable. As illustrated in the model presented in Figure 4H, RAD52-mediated DNA annealing from a collapsed replication fork into regions of micro-homology could fulfill the requirement for a rapid completion of DNA synthesis to take place in mitosis, albeit at the potential cost of increased mutagenesis and CNVs at CFSs. Given the widespread occurrence of oncogene-induced RS and the increasing clinical interest in small molecule inhibitors that further exacerbate RS in human cancers (such as ATR inhibitors), our findings point to a protective role for RAD52 in the maintenance of cancer cell viability. As such, RAD52 could be a plausible target for therapies targeted at tumors with excessive RS and/or those exposed to agents that generate additional RS, such as ATRi. Furthermore, RAD52 inhibition might be selective, given the apparently limited role of RAD52 in genome maintenance in normal cells (Feng et al., 2011, Lok et al., 2013, Lok and Powell, 2012, Rijkers et al., 1998). Of possible relevance to this, abrogation of RAD52 function leads to increased cell death in lung tumors and in BRCA2-deficient cancer cells (Feng et al., 2011, Lok et al., 2013). We propose that this could be due to the abrogation of MiDAS, which is required to sustain viability in these cells. Additionally, amplification of the 12p13.33 locus comprising the RAD52 gene is associated with the development of squamous cell carcinomas of the lung (Lieberman et al., 2016). Hence, we propose that the treatment of patients with MiDAS inhibitors, in combination with agents such as ATR inhibitors, might synergistically and selectively target tumors exhibiting oncogene-activated RS.