eme1

SLX4 provides a molecular scaffold for the assembly of multiple protein complexes required for the maintenance of genome stability. It is involved in the repair of DNA crosslinks, the resolution of recombination intermediates, the response to replication stress and the maintenance of telomere length. To carry out these diverse functions, SLX4 interacts with three structure-selective endonucleases, MUS81-EME1, SLX1 and XPF-ERCC1, as well as the telomere binding proteins TRF2, RTEL1 and SLX4IP. Recently, SLX4 was shown to interact with MutSβ, a heterodimeric protein involved in DNA mismatch repair, trinucleotide repeat instability, crosslink repair and recombination...

Chromosome instability (CIN) underpins cancer evolution and is associated with drug resistance and poor prognosis. Understanding the mechanistic basis of CIN is thus a priority. The structure-specific endonuclease Mus81-Eme1 is known to prevent CIN. Intriguingly, however, here we show that the aberrant processing of late replication intermediates by Mus81-Eme1 is a source of CIN. Upon depletion of checkpoint kinase 1 (Chk1), Mus81-Eme1 cleaves under-replicated DNA engaged in mitotic DNA synthesis, leading to chromosome segregation defects...

MutSα and MutSβ play important roles in DNA mismatch repair and are linked to inheritable cancers and degenerative disorders. Here, we show that MSH2 and MSH3, the two components of MutSβ, bind SLX4 protein, a scaffold for the assembly of the SLX1-SLX4-MUS81-EME1-XPF-ERCC1 (SMX) trinuclease complex. SMX promotes the resolution of Holliday junctions (HJs), which are intermediates in homologous recombinational repair. We find that MutSβ binds HJs and stimulates their resolution by SLX1-SLX4 or SMX in reactions dependent upon direct interactions between MutSβ and SLX4...

Introduction: Among the Jordanian population, brain tumors are the tenth most common type of cancers in both males and females, comprising 2.8% of all newly diagnosed neoplasms. Diffuse gliomas are the most prevalent and the most aggressive primary brain tumors in adults. The incidence of diffuse gliomas varies among different populations; this variation is partially linked to genetic polymorphisms. The purpose of the study is to examine the association between (BRCA1 rs799917G>A, rs1799966T>C, EXO1 rs1047840G>A, EME1 rs12450550T>C, ERCC2 rs13181T>G, rs1799793C>T, and XRCC1 rs1799782G>A) DNA repair gene polymorphisms and glioblastoma multiforme (GBM) susceptibility, and survival in the Jordanian Arab population...

Multiple myeloma stem-like cells (MMSCs) are responsible for initiation and relapse, though novel treatment paradigms that effectively eradicate MMSCs are yet to be developed. Selective inhibition of the cell cycle regulatory kinase Wee1 by MK1775 is being explored as a potential anti-cancer therapeutic. We report that higher expression of Wee1 is correlated with poor survival in multiple myeloma (MM). The MM models and patient-derived CD138+ plasma cells are particularly sensitive to the growth-inhibitory effects of the Wee1 inhibitor MK1775...

BACKGROUND: Zika virus (ZIKV) is a major human pathogen and member of the Flavivirus genus. Previous studies have identified neutralizing antibodies from Zika patients that bind to quaternary epitopes across neighboring envelope (E) proteins, called E dimer epitopes (EDE). An asparagine-linked glycan on the "glycan loop" (GL) of the ZIKV envelope protein protects the functionally important "fusion loop" on the opposite E subunit in the dimer, and EDE antibodies have been shown to bind to both of these loops...

Elevated replication stress is evident at telomeres of about 10-15% of cancer cells, which maintain their telomeres via a homologous recombination (HR)-based mechanism, referred to as alternative lengthening of telomeres (ALT). How ALT cells resolve replication stress to support their growth remains incompletely characterized. Here we report that CSB promotes recruitment of HR repair proteins (MRN, BRCA1, BLM, RPA32) and POLD3 to ALT telomeres, a process that requires CSB's ATPase activity and is controlled by ATM- and CDK2-dependent phosphorylation...

Formation of co-transcriptional R-loops underlies replication fork stalling upon head-on transcription-replication encounters. Here, we demonstrate that RAD51-dependent replication fork reversal induced by R-loops is followed by the restart of semiconservative DNA replication mediated by RECQ1 and RECQ5 helicases, MUS81/EME1 endonuclease, RAD52 strand-annealing factor, the DNA ligase IV (LIG4)/XRCC4 complex, and the non-catalytic subunit of DNA polymerase δ, POLD3. RECQ5 disrupts RAD51 filaments assembled on stalled forks after RECQ1-mediated reverse branch migration, preventing a new round of fork reversal and facilitating fork cleavage by MUS81/EME1...

During meiotic prophase I, double-strand breaks (DSBs) initiate homologous recombination leading to non-crossovers (NCOs) and crossovers (COs). In mouse, 10% of DSBs are designated to become COs, primarily through a pathway dependent on the MLH1-MLH3 heterodimer (MutLγ). Mlh3 contains an endonuclease domain that is critical for resolving COs in yeast. We generated a mouse (Mlh3DN/DN) harboring a mutation within this conserved domain that is predicted to generate a protein that is catalytically inert. Mlh3DN/DN males, like fully null Mlh3-/- males, have no spermatozoa and are infertile, yet spermatocytes have grossly normal DSBs and synapsis events in early prophase I...

Holliday junctions (HJs) are DNA intermediates in homology-directed DNA repair and replication stalling, but until recently were undetectable in living cells. We review how an engineered protein that traps and labels HJs in Escherichia coli illuminates the biology of DNA and cancer. HJ chromatin immunoprecipitation with deep sequencing (ChIP-seq) analysis showed the directionality of double-strand break (DSB) repair in the E. coli genome. Quantification of HJs as fluorescent foci in live cells revealed that the commonest spontaneous problem repaired via HJs is replication-dependent single-stranded DNA gaps, not DSBs...

During meiosis, induction of DNA double strand breaks (DSB) leads to recombination between homologous chromosomes, resulting in crossovers (CO) and non-crossovers (NCO). In the mouse, only 10% of DSBs resolve as COs, mostly through a class I pathway dependent on MutSg (MSH4/ MSH5) and MutLg (MLH1/MLH3), the latter representing the ultimate marker of these CO events. A second Class II CO pathway accounts for only a few COs, but is not thought to involve MutSg/ MutLg, and is instead dependent on MUS81-EME1. For class I events, loading of MutLg is thought to be dependent on MutSg, however MutSg loads very early in prophase I at a frequency that far exceeds the final number of class I COs...

BACKGROUND AND OBJECTIVES: Bladder cancer is one of the most common and highly recurrent cancers worldwide. Recurrence-associated genes may potentially predict cancer recurrence. We aimed to construct a recurrence-associated gene panel to improve the prognostic prediction of bladder cancer. METHODS: Based on DNA sequencing and clinical data from the TCGA-BLCA project, we identified 10 potential driver genes significantly associated with recurrence of bladder cancer...

Holliday junction (HJ) resolution by resolving enzymes is essential for chromosome segregation and recombination-mediated DNA repair. HJs undergo two types of structural dynamics that determine the outcome of recombination: conformer exchange between two isoforms and branch migration. However, it is unknown how the preferred branch point and conformer are achieved between enzyme binding and HJ resolution given the extensive binding interactions seen in static crystal structures. Single-molecule fluorescence resonance energy transfer analysis of resolving enzymes from bacteriophages (T7 endonuclease I), bacteria (RuvC), fungi (GEN1) and humans (hMus81-Eme1) showed that both types of HJ dynamics still occur after enzyme binding...

The SLX4/FANCP tumor suppressor has emerged as a key player in the maintenance of genome stability, making pivotal contributions to the repair of interstrand cross-links, homologous recombination, and in response to replication stress genome-wide as well as at specific loci such as common fragile sites and telomeres. SLX4 does so in part by acting as a scaffold that controls and coordinates the XPF-ERCC1, MUS81-EME1, and SLX1 structure-specific endonucleases in different DNA repair and recombination mechanisms...

During meiosis, crossover recombination promotes the establishment of physical connections between homologous chromosomes, enabling their bipolar segregation. To ensure that persistent recombination intermediates are disengaged prior to the completion of meiosis, the Yen1(GEN1) resolvase is strictly activated at the onset of anaphase II. Whether controlled activation of Yen1 is important for meiotic crossing-over is unknown. Here, we show that CDK-mediated phosphorylation of Yen1 averts its pervasive recruitment to recombination intermediates during prophase I...

The canonical role of cohesin is to mediate sister chromatid cohesion. In addition, cohesin plays important roles in processes such as DNA repair and regulation of gene expression. Mounting evidence suggests that various post-translational modifications, including phosphorylation, acetylation and sumoylation regulate cohesin functions. Our mass spectrometry analysis of cohesin purified from Schizosaccharomyces pombe cells revealed that the cohesin subunit Psm1 is methylated on two evolutionarily conserved lysine residues, K536 and K1200...

The MUS81 complex is crucial for preserving genome stability through the resolution of branched DNA intermediates in mitosis. However, untimely activation of the MUS81 complex in S-phase is dangerous. Little is known about the regulation of the human MUS81 complex and how deregulated activation affects chromosome integrity. Here, we show that the CK2 kinase phosphorylates MUS81 at Serine 87 in late-G2/mitosis, and upon mild replication stress. Phosphorylated MUS81 interacts with SLX4, and this association promotes the function of the MUS81 complex...

Oxaliplatin-based chemotherapy is used to treat patients with esophageal adenocarcinoma (EAC), but no biomarkers are currently available for patient selection. We performed a prospective, clinical trial to identify potential biomarkers associated with clinical outcomes. Tumor tissue was obtained from 38 patients with resectable EAC before and after 2 cycles of oxaliplatin-fluorouracil chemotherapy. Pre-treatment mRNA expression of 280 DNA repair (DNAR) genes was tested for association with histopathological regression at surgery, disease-free survival (DFS) and overall survival (OS)...

Mus81 is a well-conserved DNA structure-specific endonuclease which belongs to the XPF/Rad1 family of proteins that are involved in DNA nucleotide excision repair. Mus81 forms a heterodimer with a non-catalytic subunit, Mms4, in Saccharomyces cerevisiae (Eme1/EME1 in Schizosaccharomyces pombe and mammals). Recent evidence shows that Mus81 functions redundantly with Sgs1, a member of the ubiquitous RecQ family of DNA helicases, to process toxic recombinant intermediates. In budding yeast, homologous recombination is regulated by the Rad52 epistasis group of proteins, including Rad52, which stimulates the main steps of DNA sequence-homology searching...

Telomeres resemble common fragile sites (CFSs) in that they are difficult-to-replicate and exhibit fragility in mitosis in response to DNA replication stress. At CFSs, this fragility is associated with a delay in the completion of DNA replication until early mitosis, whereupon cells are proposed to switch to a RAD52-dependent form of break-induced replication. Here, we show that this mitotic DNA synthesis (MiDAS) is also a feature of human telomeres. Telomeric MiDAS is not restricted to those telomeres displaying overt fragility, and is a feature of a wide range of cell lines irrespective of whether their telomeres are maintained by telomerase or by the alternative lengthening of telomeres (ALT) mechanism...