The Genomic History of the Bronze Age Southern Levant.

We report genome-wide DNA data for 73 individuals from five archaeological sites across the Bronze and Iron Ages Southern Levant. These individuals, who share the "Canaanite" material culture, can be modeled as descending from two sources: (1) earlier local Neolithic populations and (2) populations related to the Chalcolithic Zagros or the Bronze Age Caucasus. The non-local contribution increased over time, as evinced by three outliers who can be modeled as descendants of recent migrants. We show evidence that different "Canaanite" groups genetically resemble each other more than other populations. We find that Levant-related modern populations typically have substantial ancestry coming from populations related to the Chalcolithic Zagros and the Bronze Age Southern Levant. These groups also harbor ancestry from sources we cannot fully model with the available data, highlighting the critical role of post-Bronze-Age migrations into the region over the past 3,000 years.

A sterol-PI(4)P exchanger modulates the Tel1/ATM axis of the DNA damage response.

Upon DNA damage, cells activate the DNA damage response (DDR) to coordinate proliferation and DNA repair. Dietary, metabolic, and environmental inputs are emerging as modulators of how DNA surveillance and repair take place. Lipids hold potential to convey these cues, although little is known about how. We observed that lipid droplet (LD) number specifically increased in response to DNA breaks. Using Saccharomyces cerevisiae and cultured human cells, we show that the selective storage of sterols into these LD concomitantly stabilizes phosphatidylinositol-4-phosphate (PI(4)P) at the Golgi, where it binds the DDR kinase ATM. In turn, this titration attenuates the initial nuclear ATM-driven response to DNA breaks, thus allowing processive repair. Furthermore, manipulating this loop impacts the kinetics of DNA damage signaling and repair in a predictable manner. Thus, our findings have major implications for tackling genetic instability pathologies through dietary and pharmacological interventions.

Thermodynamic and structural investigation of the interaction of quaternized 2,3-octakis-[(2-mercaptopyridine)phthalocyaninato] copper (II) sulfate (CuPc) with parallel and hybrid type G-quadruplex.

G-quadruplexes are important drug targets and get attention due to their existence in telomere, ribosomal DNA, promoter regions of some oncogenes, and the untranslated regions of mRNA. Due to the biological roles of G-quadruplexes, investigating of the G-quadruplex-small molecule interaction is essential. The primary motivation for these studies is the possibility of inhibiting cell functions associated with G-quadruplex sequences by binding with small molecules. Targeting the small molecules to desired tissue with the G-quadruplex vehicles is the second important goal of the G-quadruplex-small molecule interaction studies. In the present study, the new peripherally 2-mercaptopyridine octasubstituted copper(II) phthalocyanine and its quaternized derivative (CuPc) were synthesized and characterized by elemental analysis FT-IR, UV-Vis, and mass spectra. The excellent solubility of CuPc in water is essential for its transport in the organism. Because of this feature, its affinity toward G-quadruplex forming aptamers, AS1411, Tel21, and Tel45, was investigated. The UV-Vis spectrophotometric titration data confirmed the prevention of aggregation upon interaction with G-quadruplex, which is very important for biomedical applications. The CD spectroscopic analyses and binding stoichiometry confirmed the "end stacking" model for interaction of AS1411 with CuPc. The interaction of CuPc caused the equilibrium shift from hybrid conformation to antiparallel conformation for Tel21 and Tel45. The isothermal titration calorimeter (ITC) was used for the determination of thermodynamic parameters. The thermodynamic data of the interaction was fitted well with the one-site model. The negative values of Gibbs free energy change confirmed the spontaneous nature of the reactions. Besides, the negative values of enthalpy change and entropy change proved that the nature of processes was "enthalpy driven." The interaction stoichiometry was 2 for AS1411 and Tel21 and 1.5 for Tel45. The binding constants were 1.3(±0.3) × 105 , 3.2(±0.4) × 105 , and 1.1(±0.3) × 105 M-1 , which were at the level of ethidium bromide intercalation binding constant given in the literature. The DNA polymerase stop assay further supported the interaction of CuPc with G-quadruplex DNA. The experimental results confirm that the CuPc has a potential photosensitizer behaviour for photodynamic therapy.

Novel insights into the mechanism of cell cycle kinases Mec1(ATR) and Tel1(ATM).

DNA replication is a highly precise process which usually functions in a perfect rhythm with cell cycle progression. However, cells are constantly faced with various kinds of obstacles such as blocks in DNA replication, lack of availability of precursors and improper chromosome alignment. When these problems are not addressed, they may lead to chromosome instability and the accumulation of mutations, and even cell death. Therefore, the cell has developed response mechanisms to keep most of these situations under control. Of the many factors that participate in this DNA damage response, members of the family of phosphatidylinositol 3-kinase-related protein kinases (PIKKs) orchestrate the response landscape. Our understanding of two members of the PIKK family, human ATR (yeast Mec1) and ATM (yeast Tel1), and their associated partner proteins, has shown substantial progress through recent biochemical and structural studies. Emerging structural information of these unique kinases show common features that reveal the mechanism of kinase activity.

Visualisation Approaches in Technology-Enhanced Medical Simulation Learning: Current Evidence and Future Directions.

Technology-enhanced learning (TEL) has been proposed as an approach to minimise the healthcare workforce shortage preventing universal healthcare coverage. Simulation-based medical education is a well-established teaching method. Little is known about effective strategies to translate in-person medical simulation teaching into a virtual world. This work aimed to review the literature on approaches to visualisation in technology-enhanced medical simulation. A systematic search strategy was optimised using three databases: Embase, MEDLINE, and APA PsycInfo. Additional papers were identified through cross-referencing. The last date of this search was 3 January 2022. The articles were analysed qualitatively. The risk of bias was assessed using ROBINS-I and RoB 2 tools. The search yielded 656 results with 9 additional papers identified through cross-referencing. Following deduplication and exclusions, 23 articles were included in a qualitative synthesis of evidence. Offline and online computer-based modules with virtual patient cases or practical skills simulations were identified as the most prevalent clinical simulation teaching modalities. Visualisation approaches included text, images, animations, videos, and 3D environments. Significant heterogeneity of study designs with a moderate risk of bias was established. Based on the current data, the virtual patient scenarios should use natural language input interfaces enriched with video and voice recordings, 3D animations, and short text descriptions to make the patient management experience more lifelike and increase knowledge retention. However, there is no agreed framework for assessing the pedagogical value of these innovations. High-quality randomised controlled trials of TEL-based clinical simulation are essential to advance the field.

Dynamic Properties of the DNA Damage Response Mre11/Rad50 Complex.

DNA double-strand breaks (DSBs) are a significant threat to cell viability due to the induction of genome instability and the potential loss of genetic information. One of the key players for early DNA damage response is the conserved Mre11/Rad50 Nbs1/Xrs2 (MRN/X) complex, which is quickly recruited to the DNA's ruptured ends and is required for their tethering and their subsequent repair via different pathways. The MRN/X complex associates with several other proteins to exert its functions, but it also exploits sophisticated internal dynamic properties to orchestrate the several steps required to address the damage. In this review, we summarize the intrinsic molecular features of the MRN/X complex through biophysical, structural, and computational analyses in order to describe the conformational transitions that allow for this complex to accomplish its multiple functions.

TTT (Tel2-Tti1-Tti2) Complex, the Co-Chaperone of PIKKs and a Potential Target for Cancer Chemotherapy.

The heterotrimeric Tel2-Tti1-Tti2 or TTT complex is essential for cell viability and highly observed in eukaryotes. As the co-chaperone of ATR, ATM, DNA-PKcs, mTOR, SMG1, and TRRAP, the phosphatidylinositol 3-kinase-related kinases (PIKKs) and a group of large proteins of 300-500 kDa, the TTT plays crucial roles in genome stability, cell proliferation, telomere maintenance, and aging. Most of the protein kinases in the kinome are targeted by co-chaperone Cdc37 for proper folding and stability. Like Cdc37, accumulating evidence has established the mechanism by which the TTT interacts with chaperone Hsp90 via R2TP (Rvb1-Rvb2-Tah1-Pih1) complex or other proteins for co-translational maturation of the PIKKs. Recent structural studies have revealed the α-solenoid structure of the TTT and its interactions with the R2TP complex, which shed new light on the co-chaperone mechanism and provide new research opportunities. A series of mutations of the TTT have been identified that cause disease syndrome with neurodevelopmental defects, and misregulation of the TTT has been shown to contribute to myeloma, colorectal, and non-small-cell lung cancers. Surprisingly, Tel2 in the TTT complex has recently been found to be a target of ivermectin, an antiparasitic drug that has been used by millions of patients. This discovery provides mechanistic insight into the anti-cancer effect of ivermectin and thus promotes the repurposing of this Nobel-prize-winning medicine for cancer chemotherapy. Here, we briefly review the discovery of the TTT complex, discuss the recent studies, and describe the perspectives for future investigation.

Comparison of diagnostic criteria for children with familial Mediterranean fever.

Familial Mediterranean fever (FMF) is an autoinflammatory disease characterized by recurrent attacks of fever and serositis. Diagnosis is made according to clinical findings and supported by genetic analysis. The most commonly used adult diagnostic criteria are the Tel-Hashomer criteria. Pediatric criteria for FMF diagnosis were described in 2009, but their reliability should be supported by additional reports. In this study, we aimed to compare the pediatric criteria and the Tel-Hashomer and 2019 Eurofever/PRINTO classification criteria using our FMF cohort. A total of 113 patients diagnosed with FMF were included. Demographic features and laboratory findings were retrospectively collected from the patients' files. The patients were evaluated with the Tel-Hashomer, pediatric and Eurofever/PRINTO classification criteria. At least two of five new pediatric criteria were as sensitive (89%) and specific (85%) as the Tel-Hashomer criteria (sensitivity 70%, specificity 96%). We also evaluated the Eurofever/PRINTO classification criteria using our cohort and found a sensitivity of 94% and specificity of 91%.   Conclusion: Using pediatric criteria for the diagnosis of FMF in children is a feasible and simple approach that can diagnose the disease based on at least two criteria. Therefore, our study supports the use of pediatric criteria in FMF diagnosis of children. Our results also confirm that the Eurofever/PRINTO classification criteria can be successfully applied for the diagnosis of FMF due to their high sensitivity (94%) and specificity (91%). What is Known: • The FMF diagnosis is made according clinical findings and supported by genetic analysis. • The use of adult diagnostic criteria in pediatric FMF patients is controversial since classical clinical presentation is often absent in children. What is New: • Our study supports both the use of pediatric criteria and Eurofever/PRINTO classification criteria in clinical practice.

Design analysis and validation of coaxial probe for tissue dielectric properties evaluation used in specific absorption rate measurement.

This study distinguishes the design and analysis of a coaxial probe for measurement of biological body dielectric properties, in this measurement estimating the human tissue-equivalent liquid (TEL) permittivity and conductivity, to monitor and maintain the international standards for specific absorption rate (SAR) evaluation over the frequency band of 800 MHz-5 GHz. In addition, deionized (DI) water and ethanediol dielectric properties have been evaluated and the designed probe results compared to the commercial Dielectric Assessment kit (DAK) 3.5 probe. The obtained results are in good agreement with each other, moreover, the SAR calculation and each source of uncertainty budget analysis are estimated. Therefore, this fabricated probe may be suitable for liquid dielectric properties measurement.

Budding yeast Rad51: a paradigm for how phosphorylation and intrinsic structural disorder regulate homologous recombination and protein homeostasis.

The RecA-family recombinase Rad51 is the central player in homologous recombination (HR), the faithful pathway for repairing DNA double-strand breaks (DSBs) during both mitosis and meiosis. The behavior of Rad51 protein in vivo is fine-tuned via posttranslational modifications conducted by multiple protein kinases in response to cell cycle cues and DNA lesions. Unrepaired DSBs and ssDNA also activate Mec1ATR and Tel1ATM family kinases to initiate the DNA damage response (DDR) that safeguards genomic integrity. Defects in HR and DDR trigger genome instability and result in cancer predisposition, infertility, developmental defects, neurological diseases or premature aging. Intriguingly, yeast Mec1ATR- and Tel1ATM-dependent phosphorylation promotes Rad51 protein stability during DDR, revealing how Mec1ATR can alleviate proteotoxic stress. Moreover, Mec1ATR- and Tel1ATM-dependent phosphorylation also occurs on DDR-unrelated proteins, suggesting that Mec1ATR and Tel1ATM have a DDR-independent function in protein homeostasis. In this minireview, we first describe how human and budding yeast Rad51 are phosphorylated by multiple protein kinases at different positions to promote homology-directed DNA repair and recombination (HDRR). Then, we discuss recent findings showing that intrinsic structural disorder and Mec1ATR/Tel1ATM-dependent phosphorylation are coordinated in yeast Rad51 to regulate both HR and protein homeostasis.

The regulation of the DNA damage response at telomeres: focus on kinases.

The natural ends of linear chromosomes resemble those of accidental double-strand breaks (DSBs). DSBs induce a multifaceted cellular response that promotes the repair of lesions and slows down cell cycle progression. This response is not elicited at chromosome ends, which are organized in nucleoprotein structures called telomeres. Besides counteracting DSB response through specialized telomere-binding proteins, telomeres also prevent chromosome shortening. Despite of the different fate of telomeres and DSBs, many proteins involved in the DSB response also localize at telomeres and participate in telomere homeostasis. In particular, the DSB master regulators Tel1/ATM and Mec1/ATR contribute to telomere length maintenance and arrest cell cycle progression when chromosome ends shorten, thus promoting a tumor-suppressive process known as replicative senescence. During senescence, the actions of both these apical kinases and telomere-binding proteins allow checkpoint activation while bulk DNA repair activities at telomeres are still inhibited. Checkpoint-mediated cell cycle arrest also prevents further telomere erosion and deprotection that would favor chromosome rearrangements, which are known to increase cancer-associated genome instability. This review summarizes recent insights into functions and regulation of Tel1/ATM and Mec1/ATR at telomeres both in the presence and in the absence of telomerase, focusing mainly on discoveries in budding yeast.

Presentation of a new mutation in FMF and evaluating the frequency of distribution of the MEFV gene mutation in our region with clinical findings.

Familial Mediterranean Fever (FMF), which is an autosomal recessive disease characterized by recurrent self-limiting fever, peritonitis, pleuritis, arthritis and erysipelas-like erythemas, has been common among ethnic groups such as Turkish, Armenian, Arabic and Jewish. The clinical presentation is caused by mutations in the MEFV gene encoding the Pyrin protein. In this study, we aimed to present a new mutation that has not been previously defined from the mutations in the MEFV gene which is responsible for the genetic pathology of familial Mediterranean fever and to evaluate the frequency of distribution of the MEFV gene mutation among different ethnic groups living in our region. In present retrospective study, a total of 2639 clinically suspected FMF patients who were referred to Hatay Mustafa Kemal University Hospital between 2010 and 2017 were recorded. MEFV gene mutations were observed using DNA sequence analysis. MEFV mutations were found in 2079 of the 2639 patients (78.7%) Among these patients 184 (6.97%) were homozygous, while 1365 (51.72%) were heterozygous. The most frequently observed mutation was R202Q (1319, 19.55%) followed by E148Q (n = 476, 7.05%), M694V (n = 439, 6.51%), V726A (n = 146, 2.16%) and M680I (n = 135, 2%). In a case clinically diagnosed as FMF, a new mutation called S145G (p. Ser145Gly, c.433A > G) was identified in exon 2 of the MEFV gene. Besides, addition of a new pathogenic MEFV variant to the literature, the relationship between the FMF clinic and homozygous form of R202Q, which was previously considered as a polymorphism, was highlighted.

Continuing Professional Development Needs Amongst University of Toronto's Department of Radiation Oncology Faculty.

Continuing professional development (CPD) and lifelong learning are core tenets of most healthcare disciplines. Where undergraduate coursework lays the foundation for entry into practice, CPD courses and offerings are designed to aid clinicians in maintaining these competencies. CPD offerings need to be frequently revised and updated to ensure their continued utility. The purpose of this qualitative study was to better understand the CPD needs of members of the University of Toronto's Department of Radiation Oncology (UTDRO) and determine how these needs could be generalized to other CPD programs. Given that UTDRO consists of members of various health disciplines (radiation therapist, medical physicists, radiation oncologists, etc.), eleven semi-structured interviews were conducted with various health professionals from UTDRO. Inductive thematic analysis using qualitative data processing with NVivo® was undertaken. The data was coded, sorted into categories, and subsequently reviewed for emergent themes. Participants noted that a general lack of awareness and lack of access made participation in CPD programs difficult. Members also noted that topics were often impractical, irrelevant, or not inclusive of different professions. Some participants did not feel motivated to engage in CPD offerings due to a general lack of time and lack of incentive. To address the deficiencies of CPD programs, a formal needs assessment that engages stakeholders from different centers and health professions is required. Needs assessments of CPD programs should include analyzing elements related to access, how to utilize technology-enhanced learning (TEL), determine barriers to participation, and understand how to better engage members.

Unpacking smart education's soft smartness variables: Leadership and human resources capacities as key participatory actors.

The education system has been radically transformed by technological impetuses owed to the Fourth Industrial Revolution (4.0). Most recently, developing nations expedited smart education implementation to combat the negative effects COVID-19 has on education; thus, presenting managerial issues. A review of the literature on smart education shows that past studies focused primarily on the smart learning environment, substantially ignoring the importance of leadership and human resources capacity in the management of smart education. This study addresses the deficiency observed in the literature as it relates to the key factors that enable success in the management of smart education. The study applied a quantitative approach that derived data from a structured survey of probability simple random sampled Grenadian employees belonging to tertiary education. The Hayes multiple moderated mediation, Model 23, supported by SPSS-PROCESS Macro software was used to examine the study's model. Results showed that human resources capacity has a conditional indirect effect on smart education through the mediating variable of leadership capacity. Additionally, the moderating variables of additional investment in the 'ɑ' path and student demographics in the 'ɓ' path both displayed significant moderating effects. The findings of the study have provided several valuable insights into the theoretical and practical implications of the influence of leadership and human resources capacity in the implementation of smart education. Therefore, it is recommended, that the soft variables assessed in this paper need to be harnessed accordingly to achieve smart education.

The telomere-binding protein Rif2 and ATP-bound Rad50 have opposing roles in the activation of yeast Tel1ATM kinase.

Saccharomyces cerevisiae Tel1 is the ortholog of human ATM kinase and initiates a cell cycle checkpoint in response to dsDNA breaks (DSBs). Tel1ATM kinase is activated synergistically by naked dsDNA and the Mre11-Rad50-Xrs2NBS1 complex (MRX). A multisubunit protein complex, which is related to human shelterin, protects telomeres from being recognized as DSBs, thereby preventing a Tel1ATM checkpoint response. However, at very short telomeres, Tel1ATM can be recruited and activated by the MRX complex, resulting in telomere elongation. Conversely, at long telomeres, Rap1-interacting-factor 2 (Rif2) is instrumental in suppressing Tel1 activity. Here, using an in vitro reconstituted Tel1 kinase activation assay, we show that Rif2 inhibits MRX-dependent Tel1 kinase activity. Rif2 discharges the ATP-bound form of Rad50, which is essential for all MRX-dependent activities. This conclusion is further strengthened by experiments with a Rad50 allosteric ATPase mutant that maps outside the conserved ATP binding pocket. We propose a model in which Rif2 attenuates Tel1 activity at telomeres by acting directly on Rad50 and discharging its activated ATP-bound state, thereby rendering the MRX complex incompetent for Tel1 activation. These findings expand our understanding of the mechanism by which Rif2 controls telomere length.

Targeting lung cancer stem cells using combination of Tel and Docetaxel liposomes in 3D cultures and tumor xenografts.

Cancer stem cells (CSCs) accounts for recurrence and resistance to chemotherapy in various tumors. Efficacy of chemotherapeutic drugs is limited by tumor stromal barriers, which hinder their penetration into deep tumor sites. We have earlier shown telmisartan (Tel) pretreatment prior to Docetaxel (DTX) administration enhances anti-cancer effects in non-small cell lung cancer (NSCLC). Herein, we demonstrated for the first time the efficacy of Docetaxel liposomes (DTXPL) in combination with Tel in 3D cultures of H460 cells by using polysaccharide-based hydrogels (TheWell Biosciences) and also in xenograft model of DTX resistant H460 derived CD133+ lung tumors. DTXPL and Tel combination showed enhanced cytotoxicity in H460 WT 3D cultures by two folds. In H460 3D cultures, Tel pretreatment showed increased liposomal uptake. DTXPL and Tel combination treated tumors showed reduction in tumor volume (p < .001), increased apoptosis and downregulation of CSC markers (p < .01) in H460 WT and DTX resistant CD133+ xenograft models.

Tel1/ATM prevents degradation of replication forks that reverse after topoisomerase poisoning.

In both yeast and mammals, the topoisomerase poison camptothecin (CPT) induces fork reversal, which has been proposed to stabilize replication forks, thus providing time for the repair of CPT-induced lesions and supporting replication restart. We show that Tel1, the Saccharomyces cerevisiae orthologue of human ATM kinase, stabilizes CPT-induced reversed forks by counteracting their nucleolytic degradation by the MRX complex. Tel1-lacking cells are hypersensitive to CPT specifically and show less reversed forks in the presence of CPT The lack of Mre11 nuclease activity restores wild-type levels of reversed forks in CPT-treated tel1Δ cells without affecting fork reversal in wild-type cells. Moreover, Mrc1 inactivation prevents fork reversal in wild-type, tel1Δ, and mre11 nuclease-deficient cells and relieves the hypersensitivity of tel1Δ cells to CPT Altogether, our data indicate that Tel1 counteracts Mre11 nucleolytic activity at replication forks that undergo Mrc1-mediated reversal in the presence of CPT.

Single center experiences with telemetric intracranial pressure measurements in patients with CSF circulation disturbances.

BACKGROUND: Hydrocephalus may present with heterogeneous signs and symptoms. The indication for its treatment and the optimal drainage in complex cases may be challenging. Telemetric intracranial pressure measurements (TICPM) may open new perspectives for those circumstances. We report our experiences using the Neurovent-P-tel and the Sensor Reservoir in a retrospective study. METHODS: A series of 21 patients (age range 10-39.5 years) treated in our Pediatric Neurosurgical Unit receiving a TICPM was analyzed. In 8 patients, a Neurovent-P-Tel was implanted; 13 patients received a Sensor Reservoir, 6 of which as a stand-alone implant, while 7 were already shunted. TICPM were performed on an outpatient basis. Possible complications, follow-up surgeries, and TICPM were analyzed. RESULTS: Concerning the complications, one infection was seen in each group and one postoperative seizure was observed in the P-tel group. TICPM-assisted shunt adjustments lead to clinical improvements in six patients in the P-tel group and six patients in the Sensor Reservoir group. In four out of six non-shunted patients, TICPM contributed to the indication toward shunt implantation. CONCLUSIONS: TICPM seems to be a promising tool to improve clinical management of shunted patients with complex hydrocephalus. The two available systems will need further technical improvements, concerning implantation time, measurements, and data analysis in order to optimize handling and interpretation of the data.

Transformative instruction or old wine in new skins? Exploring how and why educators use HyperDocs.

HyperDocs are interactive, digital teaching and learning materials created, disseminated, and remixed by educators. To date, HyperDocs have not been the subject of published, peer-reviewed research. To address this research gap, we engaged in exploratory, primarily qualitative research to systematically examine how and why teachers use HyperDocs. We used an online survey to gather data on educators' (N = 261) uses of and perceptions regarding HyperDocs. Analysis suggested a wide range of definitions of, purposes for, and approaches to HyperDoc use, indicating that educators are adapting HyperDocs to their practice in myriad ways. Consistent with the openness and flexibility in finding, remixing, and using HyperDocs, educators identified a number of benefits of using these tools in their practice, including changes in student engagement and learning, shifts in instructional design and delivery, and changes in their own support and dispositions. Analysis of examples of HyperDocs shared by a subset of participants suggested some mismatch between rhetoric about HyperDocs and what was actually incorporated into them. We discuss these findings in relation to the work of educators and the future of research on HyperDocs and other crowdsourced teaching and learning initiatives.

Structure-function relationships of the Mre11 protein in the control of DNA end bridging and processing.

The evolutionarily conserved Mre11-Rad50-Xrs2 (MRX) complex cooperates with the Sae2 protein in initiating resection of DNA double-strand breaks (DSBs) and in maintaining the DSB ends tethered to each other for their accurate repair. How these MRX-Sae2 functions contribute to DNA damage resistance is not understood. By taking advantage of mre11 alleles that suppress the hypersensitivity of sae2∆ cells to genotoxic agents, we have recently found that Mre11 can be divided in two structurally distinct domains that support resistance to genotoxic agents by mediating different processes. While the Mre11 N-terminal domain impacts on the resection activity of long-range resection nucleases by mediating MRX and Tel1/ATM association to DNA DSBs, the C-terminus influences the MRX-tethering activity by its virtue to interact with Rad50. Given the evolutionary conservation of the MRX complex, our results have implications for understanding the consequences of its dysfunctions in human diseases.