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Postgraduate medical journal, 94, 398--403
2018

Adenotonsillar microbiome: an update.

Johnston, James Jordan, Douglas, Richard

Pathogenic bacteria associated with the adenoids and tonsils cause much morbidity in the paediatric population. Hyperplasia of the adenoids is associated with otitis media with effusion and hyperplasia of the palatine tonsils is associated with both recurrent tonsillitis and obstructive sleep apnoea. Most current knowledge of the microbiology of the upper airways has been derived from culture-based studies, which usually reflect only a small fraction of the bacteria present on the mucosal surface. Culture-independent molecular surveys based on 16S ribosomal RNA sequencing are now being employed to determine the microbiota on the surface and within the tissue of adenoids and palatine tonsils. This review describes the new techniques applied in determining the microbiome and summarises the results of studies employing these techniques.

Digital object identifier (DOI): 10.1136/postgradmedj-2018-135602

Sexual development : genetics, molecular biology, evolution, endocrinology, embryology, and pathology of sex determination and differentiation
2018

Triploid Colubrid Snake Provides Insight into the Mechanism of Sex Determination in Advanced Snakes.

Rovatsos, Michail, Augstenová, Barbora, Altmanová, Marie, Sloboda, Michal, Kodym, Petr, Kratochvíl, Lukáš

The advanced snakes (Caenophidia), the important amniote lineage encompassing more than 3,000 living species, possess highly conserved female heterogamety across all families. However, we still lack any knowledge on the gene(s) and the molecular mechanism controlling sex determination. Triploid individuals spontaneously appear in populations of diploid species and can provide an important insight into the evolution of sex determination. Here, we report a case of spontaneous triploidy in a male of the twin-spotted ratsnake (Elaphe bimaculata) with ZZW sex chromosomes. We speculate that as both ZZ and ZZW individuals develop male gonads, the ratio between the number of Z chromosomes and autosomes, and not the presence of the W chromosome in the genome, drives sex determination in the advanced snakes.

Digital object identifier (DOI): 10.1159/000490124

Journal of Pathology Informatics, 9(1), 13
2018

Constant quest for quality: Digital cytopathology

Van Es, Simone L., Greaves, Janelle, Gay, Stephanie, Ross, Jennifer, Holzhauser, Derek, Badrick, Tony

Background: Special consideration should be given when creating and selecting cytopathology specimens for digitization to maximize quality. Advances in scanning and viewing technology can also improve whole-slide imaging (WSI) output quality. Methods: Accumulated laboratory experience with digitization of glass cytopathology slides was collected. Results: This paper describes characteristics of a cytopathology glass slide that can reduce quality on resulting WSI. Important points in the glass cytopathology slide selection process, preparation, scanning, and WSI-editing process that will maximize the quality of the resulting acquired digital image are covered. The paper outlines scanning solutions which have potential to predict issues with a glass cytopathology slide before image acquisition, allowing for adjustment of the scanning approach. WSI viewing solutions that better simulate the traditional microscope experience are also discussed. Conclusion: In addition to taking advantage of technical advances, practical steps can taken to maximize quality of cytopathology WSI.

Digital object identifier (DOI): 10.4103/jpi.jpi_6_18

Hypertension research : official journal of the Japanese Society of Hypertension, 41, 426--434
2018

XRCC3 polymorphism is associated with hypertension-induced left ventricular hypertrophy.

Ariyandy, Andi, Sakai, Chiemi, Ishida, Mari, Mizuta, Ryusei, Miyagawa, Kiyoshi, Tashiro, Satoshi, Kinomura, Aiko, Hiraaki, Koji, Ueda, Keitaro, Yoshizumi, Masao, Ishida, Takafumi

<p>Deficiency of X-ray repair cross-complementing protein 3 (XRCC3), a DNA-damage repair molecule, and the 241Met variant of XRCC3 have been reported to increase endoreduplication, which induces polyploidy. The aims of this study were to determine the impact of the XRCC3 polymorphism on the incidence of hypertension-induced left ventricular hypertrophy (LVH) and to investigate the mechanisms underlying any potential relationship. Patients undergoing chronic hemodialysis (<em>n</em> = 77) were genotyped to assess for the XRCC3 Thr241Met polymorphism. The XRCC3 241Thr/Met genotype was more frequent in the LVH (+) group than in the LVH (-) group (42.3 vs. 13.7%, χ2 = 7.85, <em>p</em> = 0.0051). To investigate possible mechanisms underlying these observations, human XRCC3 cDNA of 241Thr or that of 241Met was introduced into cultured CHO cells. The surface area of CHO cells expressing XRCC3 241Met was larger than that expressing 241Thr. Spontaneous DNA double-strand breaks accumulated to a greater degree in NIH3T3 cells expressing 241Met (3T3-241Met) than in those expressing 241Thr (3T3-241Thr). DNA damage caused by radiation induced cell senescence more frequently in 3T3-241Met. The levels of basal and TNF-α-stimulated MCP-1 mRNA and protein secretion were higher in 3T3-241Met. Finally, FACS analysis revealed that the cell percentage in G2/M phase including polyploidy was significantly higher in 3T3-241Met than in 3T3-241Thr. Furthermore, the basal level of MCP-1 mRNA positively correlated with the cell percentage in G2/M phase and polyploidy. These data suggest that the XRCC3 241Met increases the risk of LVH via accumulation of DNA damage, thereby altering cell cycle progression and inducing cell senescence and a proinflammatory phenotype.</p>

Digital object identifier (DOI): 10.1038/s41440-018-0038-0

Evolution; international journal of organic evolution
2018

ZW, XY, and yet ZW: Sex chromosome evolution in snakes even more complicated.

Augstenová, Barbora, Johnson Pokorná, Martina, Altmanová, Marie, Frynta, Daniel, Rovatsos, Michail, Kratochvíl, Lukáš

Snakes are historically important in the formulation of several central concepts on the evolution of sex chromosomes. For over 50 years, it was believed that all snakes shared the same ZZ/ZW sex chromosomes, which are homomorphic and poorly differentiated in "basal" snakes such as pythons and boas, while heteromorphic and well differentiated in "advanced" (caenophidian) snakes. Recent molecular studies revealed that differentiated sex chromosomes are indeed shared among all families of caenophidian snakes, but that boas and pythons evolved likely independently male heterogamety (XX/XY sex chromosomes). The historical report of heteromorphic ZZ/ZW sex chromosomes in a boid snake was previously regarded as ambiguous. In the current study, we document heteromorphic ZZ/ZW sex chromosomes in a boid snake. A comparative approach suggests that these heteromorphic sex chromosomes evolved very recently and that they are poorly differentiated at the sequence level. Interestingly, two snake lineages with confirmed male heterogamety possess homomorphic sex chromosomes, but heteromorphic sex chromosomes are present in both snake lineages with female heterogamety. We point out that this phenomenon is more common across squamates. The presence of female heterogamety in non-caenophidian snakes indicates that the evolution of sex chromosomes in this lineage is much more complex than previously thought, making snakes an even better model system for the evolution of sex chromosomes.

Digital object identifier (DOI): 10.1111/evo.13543

Biological procedures online, 20, 13
2018

Optimization of Immunofluorescent Detection of Bone Marrow Disseminated Tumor Cells.

Axelrod, Haley D, Pienta, Kenneth J, Valkenburg, Kenneth C

Cancer metastasis is the primary cause of cancer-related deaths and remains incurable. Current clinical methods for predicting metastatic recurrence are not sensitive enough to detect individual cancer cells in the body; therefore, current efforts are directed toward liquid biopsy-based assays to capture circulating and disseminated tumor cells (CTCs and DTCs) in the blood and bone marrow, respectively. The most promising strategy is fluorescence-based immunostaining using cancer cell-specific markers. However, despite recent efforts to develop robust processing and staining platforms, results from these platforms have been discordant among groups, particularly for DTC detection. While the choice of cancer cell-specific markers is a large factor in this discordance, we have found that marker-independent factors causing false signal are just as critical to consider. Bone marrow is particularly challenging to analyze by immunostaining because endogenous immune cell properties and bone marrow matrix components typically generate false staining. For immunostaining of whole tumor tissue containing ample cancer cells, this background staining can be overcome. Application of fluorescent-based staining for rare cells, however, is easily jeopardized by immune cells and autofluorescence that lead to false signal. We have specifically found two types of background staining in bone marrow samples: autofluorescence of the tissue and non-specific binding of secondary antibodies. We systematically optimized a basic immunofluorescence protocol to eliminate this background using cancer cells spiked into human bone marrow. This enhanced the specificity of automated scanning detection software. Our optimized protocol also outperformed a commercial rare cell detection protocol in detecting candidate DTCs from metastatic patient bone marrow. Robust optimization to increase the signal-to-noise ratio of immunofluorescent staining of bone marrow is required in order to achieve the necessary sensitivity and specificity for rare cell detection. Background immunofluorescent staining in bone marrow causes uncertainty and inconsistency among investigators, which can be overcome by systematically addressing each contributing source. Our optimized assay eliminates sources of background signal, and is adaptable to automated staining platforms for high throughput analysis.

Digital object identifier (DOI): 10.1186/s12575-018-0078-5

British journal of cancer
2018

Heterogeneous MYCN amplification in neuroblastoma: a SIOP Europe Neuroblastoma Study.

Berbegall, Ana P, Bogen, Dominik, Pötschger, Ulrike, Beiske, Klaus, Bown, Nick, Combaret, Valérie, Defferrari, Raffaella, Jeison, Marta, Mazzocco, Katia, Varesio, Luigi, Vicha, Ales, Ash, Shifra, Castel, Victoria, Coze, Carole, Ladenstein, Ruth, Owens, Cormac, Papadakis, Vassilios, Ruud, Ellen, Amann, Gabriele, Sementa, Angela R, Navarro, Samuel, Ambros, Peter F, Noguera, Rosa, Ambros, Inge M

<p>In neuroblastoma (NB), the most powerful prognostic marker, the MYCN amplification (MNA), occasionally shows intratumoural heterogeneity (ITH), i.e. coexistence of MYCN-amplified and non-MYCN-amplified tumour cell clones, called heterogeneous MNA (hetMNA). Prognostication and therapy allocation are still unsolved issues. The SIOPEN Biology group analysed 99 hetMNA NBs focussing on the prognostic significance of MYCN ITH. Patients &lt;18 months (18 m) showed a better outcome in all stages as compared to older patients (5-year OS in localised stages: &lt;18 m: 0.95 ± 0.04, &gt;18 m: 0.67 ± 0.14, <em>p</em> = 0.011; metastatic: &lt;18 m: 0.76 ± 0.15, &gt;18 m: 0.28 ± 0.09, <em>p</em> = 0.084). The genomic 'background', but not MNA clone sizes, correlated significantly with relapse frequency and OS. No relapses occurred in cases of only numerical chromosomal aberrations. Infiltrated bone marrows and relapse tumour cells mostly displayed no MNA. However, one stage 4s tumour with segmental chromosomal aberrations showed a homogeneous MNA in the relapse. This study provides a rationale for the necessary distinction between heterogeneous and homogeneous MNA. HetMNA tumours have to be evaluated individually, taking age, stage and, most importantly, genomic background into account to avoid unnecessary upgrading of risk/overtreatment, especially in infants, as well as in order to identify tumours prone to developing homogeneous MNA.</p>

Digital object identifier (DOI): 10.1038/s41416-018-0098-6

The American journal of surgical pathology, 42, 656--664
2018

Clarifying the Distinction Between Malignant Peripheral Nerve Sheath Tumor and Dedifferentiated Liposarcoma: A Critical Reappraisal of the Diagnostic Utility of MDM2 and H3K27me3 Status.

Makise, Naohiro, Sekimizu, Masaya, Kubo, Takashi, Wakai, Susumu, Hiraoka, Nobuyoshi, Komiyama, Motokiyo, Fukayama, Masashi, Kawai, Akira, Ichikawa, Hitoshi, Yoshida, Akihiko

Malignant peripheral nerve sheath tumor (MPNST) and dedifferentiated liposarcoma (DDLPS) are 2 major types of pleomorphic spindle cell sarcoma. The differentiation of MPNST and DDLPS by histomorphology alone can be problematic. Although MDM2 amplification and PRC2 alteration leading to H3K27me3 deficiency are genetic hallmarks of DDLPS and MPNST, respectively, a small number of MDM2-amplified MPNSTs and H3K27me3-deficient DDLPSs have been reported in the literature. We systematically compared MDM2 and H3K27me3 status in 68 MPNSTs and 47 DDLPSs. Of the 62 MPNSTs, 22 were immunopositive for MDM2, mostly in a weak and/or focal manner. Of the 21 MDM2-positive MPNSTs successfully tested by fluorescence in situ hybridization, high-level MDM2 amplification was observed in 1 case. In contrast, MDM2 staining and high-level MDM2 amplification were positive in all the DDLPS tested (28/28 and 20/20). Of the 68 MPNSTs, 42 cases (62%) exhibited complete loss of H3K27me3. All the 13 MPNSTs that showed heterologous differentiation were deficient in H3K27me3. Of the 47 DDLPSs, 3 cases (6%) had complete loss of H3K27me3, all of which exhibited heterologous differentiation. One case of H3K27me3-deficient DDLPS exhibited homozygous loss of EED according to targeted next-generation sequencing, whereas there were no alterations in NF1 and CDKN2A. In conclusion, high-level MDM2 amplification strongly suggests DDLPS over MPNST. Although a good marker for MPNST, H3K27me3 deficiency also uncommonly occurs in DDLPS in association with PRC2 mutational inactivation. Because both markers are imperfectly specific, rare sarcomas with dual features could be encountered, and their classification should integrate other parameters.

Digital object identifier (DOI): 10.1097/PAS.0000000000001014

Basic and clinical andrology, 28, 5
2018

Is sperm FISH analysis still useful for Robertsonian translocations? Meiotic analysis for 23 patients and review of the literature.

Lamotte, Anna, Martinez, Guillaume, Devillard, Françoise, Hograindleur, Jean-Pascal, Satre, Véronique, Coutton, Charles, Harbuz, Radu, Amblard, Florence, Lespinasse, James, Benchaib, Mehdi, Bessonnat, Julien, Brouillet, Sophie, Hennebicq, Sylviane

<p>Robertsonian translocations (RobT) are common structural chromosome rearrangements where carriers display a majority of chromosomally balanced spermatozoa from alternate segregation mode. According to some monotony observed in the rates of balanced segregation, is sperm FISH analysis obsolete for RobT carriers? Retrospective cohort research study on 23 patients analyzed in our center from 2003 to 2017 and compared to the data of 187 patients in literature from 1983 to 2017.Robertsonian translocation carriers were divided in six groups according to the chromosomes involved in the translocation: 9 patients from our center and 107 from literature carrying 45,XY,der(13;14) karyotype, 3 and 35 patients respectively with 45,XY,der(14;21), 5 and 11 patients respectively with 45,XY,der(13;15), 4 and 7 patients respectively with 45,XY,der(14;15), 1 and 4 patients respectively with 45,XY,der(13;22),and 1 and 10 patients respectively with 45,XY,der(14;22). Alternate segregation mode is predominant in our group of Robertsonian translocation carriers with 73.45% ± 8.05 of balanced spermatozoa (min 50.92%; max 89.99%). These results are compliant with the data from literature for all translocations types (<em>p</em> &gt; 0.05) and are consistent among the different types of Robertsonian translocations (<em>p</em> &gt; 0.05) except for der(13;15) that exhibit lower balanced spermatozoa rates (<em>p</em> &gt; 0.05 versus der(13;14), der(14;21), (13;21) and der(15;22)). Normozoospermic patients also display a significantly (<em>p</em> &lt; 0.01) higher rate of balanced sperm cells than patients with abnormal seminograms whatever the defect implied. According to the discrepancies observed between der(13;15) and all the other Rob T carriers, the differences observed among patients presenting normal and abnormal sperm parameters and the input in genetical counselling, sperm FISH does not seem obsolete for these patients. Moreover, it seems important to collect more data for rare RobT.</p>

Digital object identifier (DOI): 10.1186/s12610-018-0069-z

Environmental science and pollution research international
2018

Toxicological evaluation of nail polish waste discarded in the environment.

Felzenszwalb, Israel, Fernandes, Andreia da Silva, Brito, Lara Barroso, Oliveira, Gisele Augusto Rodrigues, Silva, Paula Aquino Soeiro, Arcanjo, Maria Elena, Marques, Monica Regina da Costa, Vicari, Taynah, Leme, Daniela Morais, Cestari, Marta Margarete, Ferraz, Elisa Raquel Anastacio

Nail polish has been widely used around the world. However, the hazards of nail polishes discarded in the environment are still poorly investigated. Thus, the toxicogenetic effects of solubilized (SE) and leached (LE) extracts from nail polishes were investigated, simulating their disposal on water and landfill, respectively, and identifying their physicochemical properties and chemical constituents. Organic compounds and metals were detected in both extracts. SE and LE only induced mutagenic effects in TA98 Salmonella strain in the presence and absence of exogenous metabolic activation. Although both extracts did not significantly increase the frequency of micronucleated HepG2 cells, the cell viability was affected by 24-h exposure. No DNA damage was observed in gonad fish cells (RTG-2) exposed to both extracts; however, the highest SE and LE concentrations induced significant lethal and sublethal effects on zebrafish early-life stages during 96-h exposure. Based on our findings, it can be concluded that if nail polishes enter aquatic systems, it may cause negative impacts to the environment.

Digital object identifier (DOI): 10.1007/s11356-018-1880-y

Mutation research, 826, 47--52
2018

Folate modulates guanine-quadruplex frequency and DNA damage in Werner syndrome.

Tavakoli Shirazi, Paniz, Leifert, Wayne Richard, Fenech, Michael Felix, François, Maxime

<p>Guanine-quadruplexes (G4) are stable tetra-stranded DNA structures that may cause DNA replication stress and inhibit gene expression. Defects in unwinding these structures by DNA helicases may result in telomere shortening and DNA damage. Furthermore, due to mutations in WRN helicase genes in Werner syndrome, G4 motifs are likely to be key elements in the expression of premature aging phenotypes. The methylation of DNA plays a significant role in the stability and occurrence of G4. Thus, G4 frequency and DNA methylation mechanisms may be affected by excesses or deficiencies in methyl donors such as folate. B-Lymphocytes from Werner patients (n=5) and healthy individuals (n=5) were cultured in RPMI medium under condition of folate deficiency (20 nM ) or sufficiency (200 nM) for 14 days. Cells were fixed on microscope slides for immunofluorescent staining to measure G4 frequency and γH2AX (a marker of DNA strand breaks) intensity, using automated quantitative imaging fluorescent microscopy.</p>

Digital object identifier (DOI): 10.1016/j.mrgentox.2017.12.002

Environmental and molecular mutagenesis
August, 2017

Sesamol ameliorates radiation induced DNA damage in hematopoietic system of whole body γ-irradiated mice.

Kumar, Arun, Choudhary, Sandeep, Adhikari, Jawahar S, Chaudhury, Nabo K

<p>Ionizing radiation exposure is harmful and at high doses can lead to acute hematopoietic radiation syndrome. Therefore, agents that can protect hematopoietic system are important for development of radioprotector. Sesamol is a potential molecule for development of radioprotector due to its strong free radical scavenging and antioxidant properties. In the present study, sesamol was evaluated for its role in DNA damage and repair in hematopoietic system of γ-irradiated CB57BL/6 mice and compared with amifostine. C57BL/6 male mice were administered with sesamol 20 mg/kg (i.p.) followed by 2 Gy whole body irradiation (WBI) at 30 min. Mice were sacrificed at 0.5, 3, 24 h postirradiation; bone marrow, splenocytes, and peripheral blood lymphocytes were isolated to measure DNA damages and repair using alkaline comet, γ-H2AX and micronucleus assays. An increase in % of tail DNA was observed in all organs of WBI mice. Whereas in pre-administered sesamol reduced %DNA in tail (P ≤ 0.05). Sesamol has also reduced formation of radiation induced γ-H2AX foci after 0.5 h in these organs and further lowered to respective control values at 24 h of WBI. Similar reduction of % DNA in tail and γ-H2AX foci were observed with amifostine (P ≤ 0.05). Analysis of mnPCE frequency at 24 h has revealed similar extent of protection by sesamol and amifostine. Interestingly, both sesamol and amifostine, alone and with radiation, also increased the granulocytes count significantly compared to the control (P ≤ 0.05). These findings suggest that sesamol has strong potential to protect hematopoietic system by lowering radiation induced DNA damages and can prevent acute hematopoietic syndrome in mice. Environ. Mol. Mutagen., 2017. © 2017 Wiley Periodicals, Inc.</p>

Digital object identifier (DOI): 10.1002/em.22118

Scientific reports, 7, 3291
June, 2017

Transmission of Induced Chromosomal Aberrations through Successive Mitotic Divisions in Human Lymphocytes after In Vitro and In Vivo Radiation.

Kaddour, Akram, Colicchio, Bruno, Buron, Diane, El Maalouf, Elie, Laplagne, Eric, Borie, Claire, Ricoul, Michelle, Lenain, Aude, Hempel, William M, Morat, Luc, Al Jawhari, Mustafa, Cuceu, Corina, Heidingsfelder, Leonhard, Jeandidier, Eric, Deschênes, Georges, Dieterlen, Alain, El May, Michèle, Girinsky, Theodore, Bennaceur-Griscelli, Annelise, Carde, Patrice, Sabatier, Laure, M'kacher, Radhia

<p>The mechanisms behind the transmission of chromosomal aberrations (CA) remain unclear, despite a large body of work and major technological advances in chromosome identification. We reevaluated the transmission of CA to second- and third-division cells by telomere and centromere (TC) staining followed by M-FISH. We scored CA in lymphocytes of healthy donors after in vitro irradiation and those of cancer patients treated by radiation therapy more than 12 years before. Our data demonstrate, for the first time, that dicentric chromosomes (DCs) decreased by approximately 50% per division. DCs with two centromeres in close proximity were more efficiently transmitted, representing 70% of persistent DCs in ≥M3 cells. Only 1/3 of acentric chromosomes (ACs), ACs with four telomeres, and interstitial ACs, were paired in M2 cells and associated with specific DCs configurations. In lymphocytes of cancer patients, 82% of detected DCs were characterized by these specific configurations. Our findings demonstrate the high stability of DCs with two centromeres in close proximity during cell division. The frequency of telomere deletion increased during cell cycle progression playing an important role in chromosomal instability. These findings could be exploited in the follow-up of exposed populations.</p>

Digital object identifier (DOI): 10.1038/s41598-017-03198-7

Oncotarget, 8, 26269–26280
April, 2017

Opposite effects of GCN5 and PCAF knockdowns on the alternative mechanism of telomere maintenance.

Jeitany, Maya, Bakhos-Douaihy, Dalal, Silvestre, David C, Pineda, Jose R, Ugolin, Nicolas, Moussa, Angela, Gauthier, Laurent R, Busso, Didier, Junier, Marie-Pierre, Chneiweiss, Hervé, Chevillard, Sylvie, Desmaze, Chantal, Boussin, François D

<p>Cancer cells can use a telomerase-independent mechanism, known as alternative lengthening of telomeres (ALT), to elongate their telomeres. General control non-derepressible 5 (GCN5) and P300/CBP-associated factor (PCAF) are two homologous acetyltransferases that are mutually exclusive subunits in SAGA-like complexes. Here, we reveal that down regulation of GCN5 and PCAF had differential effects on some phenotypic characteristics of ALT cells. Our results suggest that GCN5 is present at telomeres and opposes telomere recombination, in contrast to PCAF that may indirectly favour them in ALT cells.</p>

Digital object identifier (DOI): 10.18632/oncotarget.15447

Leukemia
March, 2017

RECQ1 helicase is involved in replication stress survival and drug resistance in multiple myeloma.

Viziteu, E, Klein, B, Basbous, J, Lin, Y-L, Hirtz, C, Gourzones, C, Tiers, L, Bruyer, A, Vincent, L, Grandmougin, C, Seckinger, A, Goldschmidt, H, Constantinou, A, Pasero, P, Hose, D, Moreaux, J

<p>Multiple myeloma (MM) is a plasma cell cancer with poor survival, characterized by the expansion of multiple myeloma cells (MMCs) in the bone marrow. Using a microarray-based genome-wide screen for genes responding to DNA methyltransferases (DNMT) inhibition in MM cells, we identified RECQ1 among the most downregulated genes. RecQ helicases are DNA unwinding enzymes involved in the maintenance of chromosome stability. Here we show that RECQ1 is significantly overexpressed in MMCs compared to normal plasma cells and that increased RECQ1 expression is associated with poor prognosis in three independent cohorts of patients. Interestingly, RECQ1 knockdown inhibits cells growth and induces apoptosis in MMCs. Moreover, RECQ1 depletion promotes the development of DNA double-strand breaks, as evidenced by the formation of 53BP1 foci and the phosphorylation of ataxia-telangiectasia mutated (ATM) and histone variant H2A.X (H2AX). In contrast, RECQ1 overexpression protects MMCs from melphalan and bortezomib cytotoxicity. RECQ1 interacts with PARP1 in MMCs exposed to treatment and RECQ1 depletion sensitizes MMCs to poly(ADP-ribose) polymerase (PARP) inhibitor. DNMT inhibitor treatment results in RECQ1 downregulation through miR-203 deregulation in MMC. Altogether, these data suggest that association of DNA damaging agents and/or PARP inhibitors with DNMT inhibitors may represent a therapeutic approach in patients with high RECQ1 expression associated with a poor prognosis.</p>

Digital object identifier (DOI): 10.1038/leu.2017.54

Oncotarget
March, 2017

Low numbers of pre-leukemic fusion genes are frequently present in umbilical cord blood without affecting DNA damage response.

Kosik, Pavol, Skorvaga, Milan, Durdik, Matus, Jakl, Lukas, Nikitina, Ekaterina, Markova, Eva, Kozics, Katarina, Horvathova, Eva, Belyaev, Igor

Despite widely accepted notion that many childhood leukemias are likely developed from hematopoietic stem/progenitor cells (HSPC) with pre-leukemic fusion genes (PFG) formed in embryonic/fetal development, the data on PFG incidence in newborns are contradictive. To provide a better understanding of a prenatal origin of leukemia, umbilical cord blood from 500 newborns was screened for the presence of the most frequent PFG associated with pediatric B-cell acute lymphoblastic leukemia. This screening revealed relatively high incidence of ETV6-RUNX1, BCR-ABL1 (p190) and MLL-AF4 at very low frequencies, averaging ~14 copies per 100,000 cells. We assume that most of these PFG might originate relatively late in embryonic/fetal development and will be eliminated later during postnatal development. The obtained results suggested that higher PFG copy numbers originating in specific time windows of the hematopoietic stem cell hierarchy may define a better prognostic tool for the assessment of leukemogenic potential. We have observed no significant effect of low-copy PFG on radiation-induced DNA damage response, accumulation of endogenous DNA double-stranded breaks, and apoptosis in either lymphocytes or HSPC. Imaging flow cytometry showed lower level of γH2AX foci in HSPC in comparison to lymphocytes suggesting better protection of HSPC from DNA damage.

Digital object identifier (DOI): 10.18632/oncotarget.16211

Archives of toxicology
February, 2017

Dose-response relationship of temozolomide, determined by the Pig-a, comet, and micronucleus assay.

Guérard, M, Johnson, G, Dertinger, S, Duran-Pacheco, G, Funk, J, Zeller, A

<p>Temozolomide (TMZ), a monofunctional alkylating agent, was selected as a model compound to determine its quantitative genotoxic dose-response relationship in different tissues (blood, liver, and jejunum) and endpoints [Pig-a-, comet-, and micronucleus assay (MNT)] in male rats. TMZ was administered p.o. over 5 consecutive days (day 1-5), followed by a treatment-free period of 50 days (day 6-56) and a final administration prior to necropsy (day 57-59). TMZ showed a dose-dependent increase in DNA damage in all interrogated endpoints. A statistically significant increase in Pig-a mutant phenotypes was observed on day 44 starting at 7.5 mg/kg/day for mutant reticulocytes (for RET(CD59-)) and at 3.75 mg/kg/day for mutant red blood cells (RBC(CD59-)), respectively. In addition, a statistically significant increase in cytogenetic damage, as measured by micronucleated reticulocytes, was observed starting at 3.75 mg/kg/day on day 3 and 1.5 mg/kg/day on day 59. DNA strand breaks, as detected by the comet assay, showed a dose-dependent and statistically significant increase in liver, blood, and jejunum starting at doses of 3.75, 3.75, and 7.5 mg/kg/day, respectively. The dose-response relationships of the Pig-a, MNT, and comet data were analyzed for possible points of departure (PoD) using the benchmark-dose (BMD) software PROAST with different critical effect sizes (CES) (BMD0.1, BMD0.5, BMD1, and BMD1SD). Overall, PoD values show a high concordance between different tissues and endpoints, underlining the suitability of this experimental design to explore quantitative dose-response relationships in a variety of different tissues and endpoints, while minimizing animal use.</p>

Digital object identifier (DOI): 10.1007/s00204-016-1923-4

Nucleic acids research, 45, 1860–1871
February, 2017

RMI1 and TOP3α limit meiotic CO formation through their C-terminal domains.

Séguéla-Arnaud, Mathilde, Choinard, Sandrine, Larchevêque, Cécile, Girard, Chloé, Froger, Nicole, Crismani, Wayne, Mercier, Raphael

<p>At meiosis, hundreds of programmed DNA double-strand breaks (DSBs) form and are repaired by homologous recombination. From this large number of DSBs, only a subset yields crossovers (COs), with a minimum of one CO per chromosome pair. All DSBs must be repaired and every recombination intermediate must be resolved to avoid subsequent entanglement and chromosome breakage. The conserved BLM-TOP3α-RMI1 (BTR) complex acts on early and late meiotic recombination intermediates to both limit CO outcome and promote chromosome integrity. In Arabidopsis, the BLM homologues RECQ4A and RECQ4B act redundantly to prevent meiotic extra COs, but recombination intermediates are fully resolved in their absence. In contrast, TOP3α is needed for both processes. Here we show through the characterization of specific mutants that RMI1 is a major anti-CO factor, in addition to being essential to prevent chromosome breakage and entanglement. Further, our findings suggest a specific role of the C-terminal domains of RMI1 and TOP3α, that respectively contain an Oligo Binding domain (OB2) and ZINC finger motifs, in preventing extra-CO. We propose that these domains of TOP3α and RMI1 define a sub-domain of the BTR complex which is dispensable for the resolution of recombination intermediates but crucial to limit extra-COs.</p>

Digital object identifier (DOI): 10.1093/nar/gkw1210

eLife, 6
February, 2017

Epigenetic regulation of lateralized fetal spinal gene expression underlies hemispheric asymmetries.

Ocklenburg, Sebastian, Schmitz, Judith, Moinfar, Zahra, Moser, Dirk, Klose, Rena, Lor, Stephanie, Kunz, Georg, Tegenthoff, Martin, Faustmann, Pedro, Francks, Clyde, Epplen, Jörg T, Kumsta, Robert, Güntürkün, Onur

<p>Lateralization is a fundamental principle of nervous system organization but its molecular determinants are mostly unknown. In humans, asymmetric gene expression in the fetal cortex has been suggested as the molecular basis of handedness. However, human fetuses already show considerable asymmetries in arm movements before the motor cortex is functionally linked to the spinal cord, making it more likely that spinal gene expression asymmetries form the molecular basis of handedness. We analyzed genome-wide mRNA expression and DNA methylation in cervical and anterior thoracal spinal cord segments of five human fetuses and show development-dependent gene expression asymmetries. These gene expression asymmetries were epigenetically regulated by miRNA expression asymmetries in the TGF-β signaling pathway and lateralized methylation of CpG islands. Our findings suggest that molecular mechanisms for epigenetic regulation within the spinal cord constitute the starting point for handedness, implying a fundamental shift in our understanding of the ontogenesis of hemispheric asymmetries in humans.</p>

Digital object identifier (DOI): 10.7554/eLife.22784

Molecular cell
January, 2017

DNA Double-Strand Break Resection Occurs during Non-homologous End Joining in G1 but Is Distinct from Resection during Homologous Recombination.

Biehs, Ronja, Steinlage, Monika, Barton, Olivia, Juhász, Szilvia, Künzel, Julia, Spies, Julian, Shibata, Atsushi, Jeggo, Penny A, Löbrich, Markus

<p>Canonical non-homologous end joining (c-NHEJ) repairs DNA double-strand breaks (DSBs) in G1 cells with biphasic kinetics. We show that DSBs repaired with slow kinetics, including those localizing to heterochromatic regions or harboring additional lesions at the DSB site, undergo resection prior to repair by c-NHEJ and not alt-NHEJ. Resection-dependent c-NHEJ represents an inducible process during which Plk3 phosphorylates CtIP, mediating its interaction with Brca1 and promoting the initiation of resection. Mre11 exonuclease, EXD2, and Exo1 execute resection, and Artemis endonuclease functions to complete the process. If resection does not commence, then repair can ensue by c-NHEJ, but when executed, Artemis is essential to complete resection-dependent c-NHEJ. Additionally, Mre11 endonuclease activity is dispensable for resection in G1. Thus, resection in G1 differs from the process in G2 that leads to homologous recombination. Resection-dependent c-NHEJ significantly contributes to the formation of deletions and translocations in G1, which represent important initiating events in carcinogenesis.</p>

Digital object identifier (DOI): 10.1016/j.molcel.2016.12.016