Functional perturbations of the cohesin complex with subsequent changes in chromatin structure and replication are reported in a multitude of cancers including acute myeloid leukemia (AML). Mutations of its STAG2 subunit may predict unfavorable risk as recognized by the 2022 European Leukemia Net recommendations, but the underlying evidence is limited by small sample sizes and conflicting observations regarding clinical outcomes, as well as scarce information on other cohesion complex subunits. We retrospectively analyzed data from a multi-center cohort of 1615 intensively treated AML patients and identified distinct co-mutational patters for mutations of STAG2, which were associated with normal karyotypes (NK) and concomitant mutations in IDH2, RUNX1, BCOR, ASXL1, and SRSF2. Mutated RAD21 was associated with NK, mutated EZH2, KRAS, CBL, and NPM1. Patients harboring mutated STAG2 were older and presented with decreased white blood cell, bone marrow and peripheral blood blast counts. Overall, neither mutated STAG2, RAD21, SMC1A nor SMC3 displayed any significant, independent effect on clinical outcomes defined as complete remission, event-free, relapse-free or overall survival. However, we found almost complete mutual exclusivity of genetic alterations of individual cohesin subunits. This mutual exclusivity may be the basis for therapeutic strategies via synthetic lethality in cohesin mutated AML.

• MeSH
• akutní myeloidní leukemie * diagnóza   genetika   MeSH
• chromozomální proteiny, nehistonové genetika   MeSH
• lidé MeSH
• mutace MeSH
• prognóza MeSH
• retrospektivní studie MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• multicentrická studie MeSH
• práce podpořená grantem MeSH

Receiving complete and undamaged genetic information is vital for the survival of daughter cells after chromosome segregation. The most critical steps in this process are accurate DNA replication during S phase and a faithful chromosome segregation during anaphase. Any errors in DNA replication or chromosome segregation have dire consequences, since cells arising after division might have either changed or incomplete genetic information. Accurate chromosome segregation during anaphase requires a protein complex called cohesin, which holds together sister chromatids. This complex unifies sister chromatids from their synthesis during S phase, until separation in anaphase. Upon entry into mitosis, the spindle apparatus is assembled, which eventually engages kinetochores of all chromosomes. Additionally, when kinetochores of sister chromatids assume amphitelic attachment to the spindle microtubules, cells are finally ready for the separation of sister chromatids. This is achieved by the enzymatic cleavage of cohesin subunits Scc1 or Rec8 by an enzyme called Separase. After cohesin cleavage, sister chromatids remain attached to the spindle apparatus and their poleward movement on the spindle is initiated. The removal of cohesion between sister chromatids is an irreversible step and therefore it must be synchronized with assembly of the spindle apparatus, since precocious separation of sister chromatids might lead into aneuploidy and tumorigenesis. In this review, we focus on recent discoveries concerning the regulation of Separase activity during the cell cycle.

• MeSH
• anafáze * MeSH
• aparát dělícího vřeténka metabolismus   MeSH
• chromatidy * metabolismus   MeSH
• mitóza MeSH
• proteiny buněčného cyklu metabolismus   MeSH
• segregace chromozomů MeSH
• separasa genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

CCCTC-binding factor (CTCF) can both activate as well as inhibit transcription by forming chromatin loops between regulatory regions and promoters. In this regard, Ctcf binding on non-methylated DNA and its interaction with the Cohesin complex results in differential regulation of the H19/Igf2 locus. Similarly, a role for CTCF has been established in normal hematopoietic development; however its involvement in leukemia remains elusive. Here, we show that Ctcf binds to the imprinting control region of H19/Igf2 in AML blasts. We also demonstrate that Smarca5, which also associates with the Cohesin complex, facilitates Ctcf binding to its target sites on DNA. Furthermore, Smarca5 supports Ctcf functionally and is needed for enhancer-blocking effect at ICR. We next asked whether CTCF and SMARCA5 control the expression of key hematopoiesis regulators. In normally differentiating myeloid cells both CTCF and SMARCA5 together with members of the Cohesin complex are recruited to the SPI1 gene, a key hematopoiesis regulator and leukemia suppressor. Due to DNA methylation, CTCF binding to the SPI1 gene is blocked in AML blasts. Upon AZA-mediated DNA demethylation of human AML blasts, CTCF and SMARCA5 are recruited to the -14.4 Enhancer of SPI1 gene and block its expression. Our data provide new insight into complex SPI1 gene regulation now involving additional key epigenetic factors, CTCF and SMARCA5 that control PU.1 expression at the -14.4 Enhancer.

• MeSH
• adenosintrifosfatasy genetika   metabolismus   MeSH
• akutní erytroblastická leukemie genetika   metabolismus   patologie   MeSH
• akutní nemoc MeSH
• azacytidin farmakologie   MeSH
• buňky K562 MeSH
• chromozomální proteiny, nehistonové genetika   metabolismus   MeSH
• epigeneze genetická * MeSH
• genomový imprinting MeSH
• HeLa buňky MeSH
• imunoblotting MeSH
• insulinu podobný růstový faktor II genetika   metabolismus   MeSH
• konfokální mikroskopie MeSH
• lidé MeSH
• metylace DNA účinky léků   MeSH
• myeloidní leukemie genetika   metabolismus   patologie   MeSH
• nádorové buněčné linie MeSH
• polymerázová řetězová reakce s reverzní transkripcí MeSH
• protoonkogenní proteiny genetika   metabolismus   MeSH
• regulace genové exprese u nádorů MeSH
• represorové proteiny genetika   metabolismus   MeSH
• RNA dlouhá nekódující genetika   metabolismus   MeSH
• RNA interference MeSH
• trans-aktivátory genetika   metabolismus   MeSH
• vazba proteinů MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

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

Chromosome organization, dynamics and stability are required for successful passage through cellular generations and transmission of genetic information to offspring. The key components involved are Structural maintenance of chromosomes (SMC) complexes. Cohesin complex ensures proper chromatid alignment, condensin complex chromosome condensation and the SMC5/6 complex is specialized in the maintenance of genome stability. Here we summarize recent knowledge on the composition and molecular functions of SMC5/6 complex. SMC5/6 complex was originally identified based on the sensitivity of its mutants to genotoxic stress but there is increasing number of studies demonstrating its roles in the control of DNA replication, sister chromatid resolution and genomic location-dependent promotion or suppression of homologous recombination. Some of these functions appear to be due to a very dynamic interaction with cohesin or other repair complexes. Studies in Arabidopsis indicate that, besides its canonical function in repair of damaged DNA, the SMC5/6 complex plays important roles in regulating plant development, abiotic stress responses, suppression of autoimmune responses and sexual reproduction.

• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Cornelia de Lange syndrome (CdLS) is a rare autosomal-dominant genetic disorder characterised by prenatal and postnatal growth and mental retardation, facial dysmorphism and upper limb abnormalities. Germline mutations of cohesin complex genes SMC1A, SMC3, RAD21 or their regulators NIPBL and HDAC8 have been identified in CdLS as well as somatic mutations in myeloid disorders. We describe the first case of a paediatric patient with CdLS with B-cell precursor Acute Lymphoblastic Leukaemia (ALL). The patient did not show any unusual cytogenetic abnormality, and he was enrolled into the high risk arm of AIEOP-BFM ALL2009 protocol because of slow early response, but 3 years after discontinuation, he experienced an ALL relapse. We identified a heterozygous mutation in exon 46 of NIPBL, causing frameshift and a premature stop codon (RNA-Targeted Next generation Sequencing Analysis). The analysis of the family indicated a de novo origin of this previously not reported deleterious variant. As for somatic cohesin mutations in acute myeloid leukaemia, also this ALL case was not affected by aneuploidy, thus suggesting a major impact of the non-canonical role of NIPBL in gene regulation. A potential biological role of NIPBL in leukaemia has still to be dissected.

• MeSH
• de Langeové syndrom diagnóza   genetika   MeSH
• dědičnost MeSH
• fenotyp MeSH
• genetická predispozice k nemoci MeSH
• lidé MeSH
• mutace * MeSH
• mutační analýza DNA MeSH
• pre-B-buněčná leukemie diagnóza   genetika   terapie   MeSH
• předškolní dítě MeSH
• proteiny genetika   MeSH
• recidiva MeSH
• rodokmen MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• kazuistiky MeSH

The maintenance of genome integrity over cell divisions is critical for plant development and the correct transmission of genetic information to the progeny. A key factor involved in this process is the STRUCTURAL MAINTENANCE OF CHROMOSOME5 (SMC5) and SMC6 (SMC5/6) complex, related to the cohesin and condensin complexes that control sister chromatid alignment and chromosome condensation, respectively. Here, we characterize NON-SMC ELEMENT4 (NSE4) paralogs of the SMC5/6 complex in Arabidopsis (Arabidopsis thaliana). NSE4A is expressed in meristems and accumulates during DNA damage repair. Partial loss-of-function nse4a mutants are viable but hypersensitive to DNA damage induced by zebularine. In addition, nse4a mutants produce abnormal seeds, with noncellularized endosperm and embryos that maximally develop to the heart or torpedo stage. This phenotype resembles the defects in cohesin and condensin mutants and suggests a role for all three SMC complexes in differentiation during seed development. By contrast, NSE4B is expressed in only a few cell types, and loss-of-function mutants do not have any obvious abnormal phenotype. In summary, our study shows that the NSE4A subunit of the SMC5-SMC6 complex is essential for DNA damage repair in somatic tissues and plays a role in plant reproduction.

• MeSH
• Arabidopsis embryologie   genetika   imunologie   MeSH
• duplikace genu MeSH
• genom rostlinný MeSH
• oprava DNA * genetika   MeSH
• podjednotky proteinů metabolismus   MeSH
• poškození DNA * genetika   MeSH
• proteiny buněčného cyklu genetika   metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• pyl genetika   MeSH
• regulace genové exprese u rostlin MeSH
• semena rostlinná genetika   metabolismus   MeSH
• transkriptom genetika   MeSH
• upregulace genetika   MeSH
• vajíčko rostlin genetika   MeSH
• vazba proteinů MeSH
• vývojová regulace genové exprese MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The genome replication process is challenged at many levels. Replication must proceed through different problematic sites and obstacles, some of which can pause or even reverse the replication fork (RF). In addition, replication of DNA within chromosomes must deal with their topological constraints and spatial organization. One of the most important factors organizing DNA into higher-order structures are Structural Maintenance of Chromosome (SMC) complexes. In prokaryotes, SMC complexes ensure proper chromosomal partitioning during replication. In eukaryotes, cohesin and SMC5/6 complexes assist in replication. Interestingly, the SMC5/6 complexes seem to be involved in replication in many ways. They stabilize stalled RFs, restrain RF regression, participate in the restart of collapsed RFs, and buffer topological constraints during RF progression. In this (mini) review, I present an overview of these replication-related functions of SMC5/6.

• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Somatic hypermutation (SHM) introduces point mutations into immunoglobulin (Ig) genes but also causes mutations in other parts of the genome. We have used lentiviral SHM reporter vectors to identify regions of the genome that are susceptible ("hot") and resistant ("cold") to SHM, revealing that SHM susceptibility and resistance are often properties of entire topologically associated domains (TADs). Comparison of hot and cold TADs reveals that while levels of transcription are equivalent, hot TADs are enriched for the cohesin loader NIPBL, super-enhancers, markers of paused/stalled RNA polymerase 2, and multiple important B cell transcription factors. We demonstrate that at least some hot TADs contain enhancers that possess SHM targeting activity and that insertion of a strong Ig SHM-targeting element into a cold TAD renders it hot. Our findings lead to a model for SHM susceptibility involving the cooperative action of cis-acting SHM targeting elements and the dynamic and architectural properties of TADs.

• MeSH
• cytidindeaminasa genetika   metabolismus   MeSH
• HEK293 buňky MeSH
• Lentivirus MeSH
• lidé MeSH
• mutace genetika   MeSH
• nádorové buněčné linie MeSH
• plazmidy genetika   MeSH
• RNA-polymerasa II genetika   metabolismus   MeSH
• somatická hypermutace imunoglobulinových genů genetika   MeSH
• zesilovače transkripce genetika   MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

In mammals, meiotic recombination occurs at 1- to 2-kb genomic regions termed hotspots, whose positions and activities are determined by PRDM9, a DNA-binding histone methyltransferase. We show that the KRAB domain of PRDM9 forms complexes with additional proteins to allow hotspots to proceed into the next phase of recombination. By a combination of yeast-two hybrid assay, in vitro binding, and coimmunoprecipitation from mouse spermatocytes, we identified four proteins that directly interact with PRDM9's KRAB domain, namely CXXC1, EWSR1, EHMT2, and CDYL. These proteins are coexpressed in spermatocytes at the early stages of meiotic prophase I, the limited period when PRDM9 is expressed. We also detected association of PRDM9-bound complexes with the meiotic cohesin REC8 and the synaptonemal complex proteins SYCP3 and SYCP1. Our results suggest a model in which PRDM9-bound hotspot DNA is brought to the chromosomal axis by the action of these proteins, ensuring the proper chromatin and spatial environment for subsequent recombination events.

• MeSH
• chromatin metabolismus   MeSH
• chromozomy genetika   fyziologie   MeSH
• DNA metabolismus   MeSH
• dvouřetězcové zlomy DNA MeSH
• genom MeSH
• histonlysin-N-methyltransferasa genetika   metabolismus   fyziologie   MeSH
• homologní rekombinace MeSH
• meióza fyziologie   MeSH
• myši MeSH
• proteinové domény MeSH
• rekombinace genetická fyziologie   MeSH
• spermatocyty metabolismus   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH