Topoisomerase II (TOP2) relieves torsional stress by forming transient cleavage complex intermediates (TOP2ccs) that contain TOP2-linked DNA breaks (DSBs). While TOP2ccs are normally reversible, they can be "trapped" by chemotherapeutic drugs such as etoposide and subsequently converted into irreversible TOP2-linked DSBs. Here, we have quantified etoposide-induced trapping of TOP2ccs, their conversion into irreversible TOP2-linked DSBs, and their processing during DNA repair genome-wide, as a function of time. We find that while TOP2 chromatin localization and trapping is independent of transcription, it requires pre-existing binding of cohesin to DNA. In contrast, the conversion of trapped TOP2ccs to irreversible DSBs during DNA repair is accelerated 2-fold at transcribed loci relative to non-transcribed loci. This conversion is dependent on proteasomal degradation and TDP2 phosphodiesterase activity. Quantitative modeling shows that only two features of pre-existing chromatin structure-namely, cohesin binding and transcriptional activity-can be used to predict the kinetics of TOP2-induced DSBs.

• MeSH
• chromozomy genetika   MeSH
• DNA vazebné proteiny chemie   genetika   MeSH
• DNA-topoisomerasy typu II chemie   genetika   MeSH
• DNA chemie   genetika   MeSH
• dvouřetězcové zlomy DNA * MeSH
• etoposid chemie   MeSH
• genetická transkripce MeSH
• genová konverze genetika   MeSH
• HCT116 buňky MeSH
• inhibitory topoisomerasy II chemie   farmakologie   MeSH
• kinetika MeSH
• lidé MeSH
• multiproteinové komplexy chemie   genetika   MeSH
• oprava DNA genetika   MeSH
• proteiny vázající poly-ADP-ribosu chemie   genetika   MeSH
• torze mechanická MeSH
• translokace genetická genetika   MeSH
• zlomy chromozomů MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Intramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH

It has been hypothesized that species with holocentric chromosomes have a selective evolutionary advantage for developmental and reproductive success because holocentric chromosomes are less susceptible to chromosome breakage than monocentric chromosomes. We analyzed data on sterilizing doses of ionizing radiation for more than 250 species of arthropods to test whether the minimal dose for reproductive sterilization is higher for species with holocentric chromosomes than for species with monocentric chromosomes. Using linear mixed models that account for phylogeny, we show that holocentric arthropods are more tolerant of sterilizing radiation than monocentrics. Moreover, higher dose rates correlate with lower sterilizing doses in monocentrics, but not in holocentrics, which is a novel finding that may be of importance for radiosanitation practice. Under the dose rate of 1 Gy/min, holocentric arthropods are sterilized on average with a 2.9 times higher minimal dose than monocentrics. Life stage and sex have significant but considerably weaker effects on sterilizing dose than chromosome type. Adults and males require 1.2 and 1.4 times higher sterilizing doses than juveniles and females, respectively. These results support the hypothesis that holocentric lineages may originate and thrive better in times of increased exposure to chromosome-breaking factors.

• MeSH
• chromozomy účinky záření   MeSH
• členovci genetika   účinky záření   MeSH
• kontrola škůdců * MeSH
• sterilizace * MeSH
• zlomy chromozomů účinky záření   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Chromosomal rearrangements of the human MLL/KMT2A gene are associated with infant, pediatric, adult and therapy-induced acute leukemias. Here we present the data obtained from 2345 acute leukemia patients. Genomic breakpoints within the MLL gene and the involved translocation partner genes (TPGs) were determined and 11 novel TPGs were identified. Thus, a total of 135 different MLL rearrangements have been identified so far, of which 94 TPGs are now characterized at the molecular level. In all, 35 out of these 94 TPGs occur recurrently, but only 9 specific gene fusions account for more than 90% of all illegitimate recombinations of the MLL gene. We observed an age-dependent breakpoint shift with breakpoints localizing within MLL intron 11 associated with acute lymphoblastic leukemia and younger patients, while breakpoints in MLL intron 9 predominate in AML or older patients. The molecular characterization of MLL breakpoints suggests different etiologies in the different age groups and allows the correlation of functional domains of the MLL gene with clinical outcome. This study provides a comprehensive analysis of the MLL recombinome in acute leukemia and demonstrates that the establishment of patient-specific chromosomal fusion sites allows the design of specific PCR primers for minimal residual disease analyses for all patients.

• MeSH
• akutní lymfatická leukemie genetika   MeSH
• akutní myeloidní leukemie genetika   MeSH
• chromozomální aberace MeSH
• dítě MeSH
• dospělí MeSH
• fúzní onkogenní proteiny genetika   MeSH
• genová přestavba genetika   MeSH
• histonlysin-N-methyltransferasa genetika   MeSH
• kojenec MeSH
• lidé MeSH
• protoonkogenní protein MLL genetika   MeSH
• translokace genetická genetika   MeSH
• zlomy chromozomů MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• kojenec MeSH
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

We used the genomic breakpoint between BCR and ABL1 genes for the DNA-based monitoring of minimal residual disease (MRD) in 48 patients with childhood acute lymphoblastic leukemia (ALL). Comparing the results with standard MRD monitoring based on immunoglobulin/T-cell receptor (Ig/TCR) gene rearrangements and with quantification of IKZF1 deletion, we observed very good correlation for the methods in a majority of patients; however, >20% of children (25% [8/32] with minor and 12.5% [1/8] with major-BCR-ABL1 variants in the consecutive cohorts) had significantly (>1 log) higher levels of BCR-ABL1 fusion than Ig/TCR rearrangements and/or IKZF1 deletion. We performed cell sorting of the diagnostic material and assessed the frequency of BCR-ABL1-positive cells in various hematopoietic subpopulations; 12% to 83% of non-ALL B lymphocytes, T cells, and/or myeloid cells harbored the BCR-ABL1 fusion in patients with discrepant MRD results. The multilineage involvement of the BCR-ABL1-positive clone demonstrates that in some patients diagnosed with BCR-ABL1-positive ALL, a multipotent hematopoietic progenitor is affected by the BCR-ABL1 fusion. These patients have BCR-ABL1-positive clonal hematopoiesis resembling a chronic myeloid leukemia (CML)-like disease manifesting in "lymphoid blast crisis." The biological heterogeneity of BCR-ABL1-positive ALL may impact the patient outcomes and optimal treatment (early stem cell transplantation vs long-term administration of tyrosine-kinase inhibitors) as well as on MRD testing. Therefore, we recommend further investigations on CML-like BCR-ABL1-positive ALL.

• MeSH
• akutní lymfatická leukemie krev   genetika   MeSH
• bcr-abl fúzové proteiny genetika   MeSH
• chronická myeloidní leukemie krev   genetika   MeSH
• delece genu MeSH
• dítě MeSH
• genom lidský * MeSH
• hematopoéza MeSH
• lidé MeSH
• mladiství MeSH
• počet leukocytů MeSH
• předškolní dítě MeSH
• receptory antigenů T-buněk genetika   MeSH
• reziduální nádor genetika   MeSH
• transkripční faktor Ikaros genetika   MeSH
• výsledek terapie MeSH
• zlomy chromozomů * MeSH
• Check Tag
• dítě MeSH
• lidé MeSH
• mladiství MeSH
• předškolní dítě MeSH
• Publikační typ
• časopisecké články MeSH

Curcumin has been documented to exert anticancer effects by interacting with altered proliferative and apoptotic pathways in cancer models. In this study, we evaluated the potential of curcumin to reverse promoter methylation of the p15 gene in Raji cells and its ability to induce apoptosis and genomic instability. Anti-neoplastic action of curcumin showed an augmentation in reactive oxygen species (ROS) and cell cycle arrest in G1 phase. Subsequently, curcumin- exposed Raji cells showed structural abnormalities in chromosomes. These observations suggest that curcumin also causes ROS-mediated apoptosis and genomic instability. The treatment of Raji cell line with 10 μM curcumin caused hypomethylation of the p15 promoter after six days. Hypomethylation of p15 was further found to be favoured by downregulation of DNA methyltransferase 1 after 10 μM curcumin treatment for six days. Methylation-specific PCR suggested demethylation of the p15 promoter. Demethylation was further validated by DNA sequencing. Reverse-transcription PCR demonstrated that treatment with curcumin (10 μM) for six days led to the up-regulation of p15 and down-regulation of DNA methyltransferase 1. Furthermore, curcumin- mediated reversal of p15 promoter methylation might be potentiated by down-regulation of DNA methyltransferase 1 expression, which was supported by cell cycle analysis. Furthermore, curcumin acts as a double-pronged agent, as it caused apoptosis and promoter hypomethylation in Raji cells.

• MeSH
• akutní lymfatická leukemie patologie   MeSH
• antitumorózní látky fytogenní farmakologie   toxicita   MeSH
• apoptóza účinky léků   MeSH
• buněčný cyklus účinky léků   MeSH
• DNA-(cytosin-5-)methyltransferasa biosyntéza   genetika   MeSH
• down regulace účinky léků   MeSH
• enzymová indukce účinky léků   MeSH
• inhibitor p15 cyklin-dependentní kinasy biosyntéza   genetika   MeSH
• kurkumin farmakologie   toxicita   MeSH
• léky antitumorózní - screeningové testy MeSH
• lidé MeSH
• metylace DNA účinky léků   MeSH
• nádorové buněčné linie MeSH
• nádorové proteiny biosyntéza   genetika   MeSH
• nestabilita genomu účinky léků   MeSH
• promotorové oblasti (genetika) účinky léků   MeSH
• reaktivní formy kyslíku metabolismus   MeSH
• regulace genové exprese u leukemie účinky léků   MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• zlomy chromozomů účinky léků   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Species with holocentric chromosomes are often characterized by a rapid karyotype evolution. In contrast to species with monocentric chromosomes where acentric fragments are lost during cell division, breakage of holocentric chromosomes creates fragments with normal centromere activity. To decipher the mechanism that allows holocentric species an accelerated karyotype evolution via chromosome breakage, we analyzed the chromosome complements of irradiated Luzula elegans plants. The resulting chromosomal fragments and rearranged chromosomes revealed holocentromere-typical CENH3 and histone H2AThr120ph signals as well as the same mitotic mobility like unfragmented chromosomes. Newly synthesized telomeres at break points become detectable 3 weeks after irradiation. The presence of active telomerase suggests a telomerase-based mechanism of chromosome healing. A successful transmission of holocentric chromosome fragments across different generations was found for most offspring of irradiated plants. Hence, a combination of holokinetic centromere activity and the fast formation of new telomeres at break points enables holocentric species a rapid karyotype evolution involving chromosome fissions and rearrangements.

• MeSH
• autoantigeny MeSH
• centromera * MeSH
• chromozomální proteiny, nehistonové MeSH
• chromozomy rostlin genetika   MeSH
• histony MeSH
• karyotyp * MeSH
• Magnoliopsida genetika   metabolismus   MeSH
• molekulární evoluce * MeSH
• rostlinné proteiny MeSH
• telomery * MeSH
• zlomy chromozomů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

H2AX is a variant of histone H2A found in nuclei of eukaryotic cells. In 1998 it was found that after formation of double-strand breaks of DNA (DSB) due to ionizing radiation, H2AX is phosphorylated on serine 139 in the conserved COOH-terminal region. This phosphorylated form is termed ?H2AX. Further studies revealed that ?H2AX formation is an early event in DSB recognition and, subsequently, many proteins engaged in DNA repair, cell cycle regulation, chromatin remodeling and apoptosis are recruited to the DSB site. The ?H2AX presence is limited to the sites around DSB and the phosphorylation is proportional to the DNA damage extent. Methods such as Western blotting, flow cytometry and immunocytochemistry are used to detect ?H2AX. Detection of ?H2AX foci is useful to visualize localized DSB. Quantification of ?H2AX is useful for monitoring DNA damage. Further, ?H2AX is a potential molecular marker in aging and cancer. The present review covers current knowledge of the role of ?H2AX and of methods for its detection and quantification.

• MeSH
• dvouřetězcové zlomy DNA MeSH
• fosforylace MeSH
• histony MeSH
• poškození DNA MeSH
• průtoková cytometrie MeSH
• zlomy chromozomů MeSH

• Klíčová slova
• komplexní přestavby,
• MeSH
• akutní myeloidní leukemie genetika   MeSH
• body zlomu chromozomu MeSH
• cytogenetické vyšetření metody   MeSH
• financování organizované MeSH
• hybridizace in situ fluorescenční využití   MeSH
• lidé MeSH
• lidské chromozomy, pár 11 ultrastruktura   MeSH
• zlomy chromozomů MeSH
• Check Tag
• lidé MeSH

We describe a girl with mild facial anomalies, mild mental retardation, and atypical autism with a remarkable behavioral phenotype of persistent anger, aggression, and dysphoria. The occurrence of late-onset tremor and premature ovarian failure in the maternal branch of the family pointed to a possible defect in the FMR1 gene. Indeed, the patient carried a full FMR1 mutation. Unexpectedly, both alleles of the gene were almost completely methylated. Cytogenetic examination of the patient revealed in addition a large de novo deletion in band Xp22 on one of her X chromosomes. The deletion was fine mapped using oligonucleotide array CGH, and its breakpoints were localized using sequencing. The size of the deletion was about 17.4 Mb, and it contained more than 90 protein-coding genes. Microsatellite analysis indicated paternal origin of the aberrant chromosome. The large rearrangement was the most probable cause of the X-inactivation skewing, thus explaining the methylation of not only the expanded (maternal) but also the normal (paternal) FMR1 alleles. This pattern of skewed X-inactivation was confirmed using the analysis of methylation at the AR locus. The relatively mild phenotype of the patient resulted most likely from unmasking of the FMR1 defect. Although the deleted region contained many important genes, the phenotypic contribution of the rearranged X chromosome was probably limited by its almost complete inactivation. However, reduced dose of several genes escaping X-inactivation might also play a role in the phenotype of the patient.

• MeSH
• autistická porucha komplikace   genetika   MeSH
• chromozomální delece MeSH
• dítě MeSH
• dospělí MeSH
• expanze trinukleotidových repetic genetika   MeSH
• genetické lokusy genetika   MeSH
• inaktivace chromozomu X genetika   MeSH
• karyotypizace MeSH
• kojenec MeSH
• lidé středního věku MeSH
• lidé MeSH
• lidské chromozomy X genetika   MeSH
• mentální retardace komplikace   genetika   MeSH
• metylace DNA genetika   MeSH
• protein FMRP genetika   MeSH
• rodiče MeSH
• Southernův blotting MeSH
• těhotenství MeSH
• zlomy chromozomů MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• kojenec MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH
• práce podpořená grantem MeSH

Neplodnost postihuje ve vyspělých zemích kolem 15 % párů a genetická příčina se vyskytuje u mnoha z nich. U 15 % žen a 10 % mužů léčících se pro neplodnost nalézáme nějaký konkrétní genetický problém, nejčastěji chromosomální aberaci nebo mutaci ve známém genu. Přirozená selekce nedovolí přenést genetickou abnormalitu způsobující neplodnost na další generace, ovšem techniky asistované reprodukce dokáží obejít i tyto mechanismy. Nalezení genetické příčiny neplodnosti je proto důležitě právě pro volbu správného postupu v léčbě neplodného páru. Genetická etiologie mužské infertility může být, stejně jako u ostatních onemocnění, chromosomální, monogenní či polygenní - multifaktoriální. Protože v současnosti ještě nejsou podrobně známy všechny základní mechanismy regulující spermatogenezi a funkci spermií, nedaří se u mnoha mužů nalézt příčinu jejich neplodnosti, která je pak diagnostikována jako idiopatická. I v případech, že je genetická podstata neplodnosti známá, jako je tomu například u mikrodelecí na chromosomu Y, nevíme dosud mnoho o zúčastněných genech ani o molekulárních mechanismech.

• MeSH
• aberace pohlavních chromozomů klasifikace   MeSH
• aneuploidie MeSH
• Angelmanův syndrom genetika   MeSH
• Bardetův-Biedlův syndrom genetika   MeSH
• cystická fibróza genetika   MeSH
• cytogenetické vyšetření normy   MeSH
• Downův syndrom genetika   MeSH
• hemochromatóza genetika   MeSH
• hypogonadismus genetika   klasifikace   MeSH
• Kallmannův syndrom genetika   MeSH
• Kartagenerův syndrom genetika   MeSH
• kongenitální adrenální hyperplazie genetika   MeSH
• Laurenceův-Moonův syndrom genetika   MeSH
• mužská infertilita etiologie   genetika   MeSH
• myotonická dystrofie genetika   MeSH
• Noonanové syndrom genetika   MeSH
• polycystické ledviny autozomálně dominantní genetika   MeSH
• Praderův-Williho syndrom genetika   MeSH
• Smithův-Lemliho-Opitzův syndrom MeSH
• syndrom rezistence na androgeny genetika   klasifikace   MeSH
• zlomy chromozomů MeSH
• Check Tag
• mužské pohlaví MeSH