BACKGROUND: Structural Maintenance of Chromosomes (SMC) complexes are molecular machines driving chromatin organization at higher levels. In eukaryotes, three SMC complexes (cohesin, condensin and SMC5/6) play key roles in cohesion, condensation, replication, transcription and DNA repair. Their physical binding to DNA requires accessible chromatin. RESULTS: We performed a genetic screen in fission yeast to identify novel factors required for SMC5/6 binding to DNA. We identified 79 genes of which histone acetyltransferases (HATs) were the most represented. Genetic and phenotypic analyses suggested a particularly strong functional relationship between the SMC5/6 and SAGA complexes. Furthermore, several SMC5/6 subunits physically interacted with SAGA HAT module components Gcn5 and Ada2. As Gcn5-dependent acetylation facilitates the accessibility of chromatin to DNA-repair proteins, we first analysed the formation of DNA-damage-induced SMC5/6 foci in the Δgcn5 mutant. The SMC5/6 foci formed normally in Δgcn5, suggesting SAGA-independent SMC5/6 localization to DNA-damaged sites. Next, we used Nse4-FLAG chromatin-immunoprecipitation (ChIP-seq) analysis in unchallenged cells to assess SMC5/6 distribution. A significant portion of SMC5/6 accumulated within gene regions in wild-type cells, which was reduced in Δgcn5 and Δada2 mutants. The drop in SMC5/6 levels was also observed in gcn5-E191Q acetyltransferase-dead mutant. CONCLUSION: Our data show genetic and physical interactions between SMC5/6 and SAGA complexes. The ChIP-seq analysis suggests that SAGA HAT module targets SMC5/6 to specific gene regions and facilitates their accessibility for SMC5/6 loading.
- Klíčová slova
- Ada2, Chromatin accessibility, DNA repair, Gcn5, Gene regions, Genetic and protein–protein interactions, Histone H3K9ac acetylation, Nse3 KITE, SAGA histone acetyltransferase module, SMC5/6 complex targeting, rDNA,
- MeSH
- acetyltransferasy genetika MeSH
- buněčné jádro metabolismus MeSH
- chromatin metabolismus MeSH
- chromozomy metabolismus MeSH
- DNA metabolismus MeSH
- histonacetyltransferasy genetika metabolismus MeSH
- proteiny buněčného cyklu genetika metabolismus MeSH
- Schizosaccharomyces pombe - proteiny * genetika metabolismus MeSH
- Schizosaccharomyces * genetika metabolismus MeSH
- transportní proteiny metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- acetyltransferasy MeSH
- chromatin MeSH
- DNA MeSH
- Gcn5 protein, S pombe MeSH Prohlížeč
- histonacetyltransferasy MeSH
- Nse4 protein, S pombe MeSH Prohlížeč
- proteiny buněčného cyklu MeSH
- Schizosaccharomyces pombe - proteiny * MeSH
- Smc5 protein, S pombe MeSH Prohlížeč
- smc6 protein, S pombe MeSH Prohlížeč
- transportní proteiny MeSH
Myoid gonadal stromal tumours (MGST) represent a rare type of testicular sex cord-stromal tumour that has recently been recognised as a distinct entity by the World Health Organization (WHO) classification of genitourinary tumours. MGSTs affect adult men and have been reported to behave in an indolent fashion. Histologically, MGSTs are pure spindle cell neoplasms that coexpress SMA and S100 protein. Given that the molecular features of these neoplasms remain largely undescribed, we evaluated a multi-institutional series of MGSTs using DNA and RNA sequencing. This study included 12 tumours from 12 patients aged 28 to 57 years. Tumour sizes ranged from 0.6 to 4.3 cm. Aggressive histologic features, such as vascular invasion, necrosis, invasive growth, and atypical mitoses were invariably absent. Mitotic activity was low, with a median of less than 1 mitosis per 10 high power fields (HPF; maximum: 3 mitoses per 10 HPF). Molecular analyses did not identify recurrent mutations or gene fusions. All cases with interpretable copy number variant data (9/10 cases sequenced successfully) demonstrated a consistent pattern of chromosome arm-level and whole-chromosome-level copy number gains indicative of ploidy shifts, with recurrent gains involving chromosomes 3, 6, 7, 8, 9, 11, 12, 14q, 15q, 17, 18q, 20, and 21q. Similar findings have also been recognised in pure spindle cell and spindle-cell predominant sex cord-stromal tumours without S100 protein expression. MGSTs are characterised by ploidy shifts and may be part of a larger spectrum of spindle cell-predominant sex cord-stromal tumours, including cases without S100 protein expression.
- Klíčová slova
- myoid gonadal stromal tumour, sex cord-stromal tumour, spindle cell tumour, testicular tumour, testis,
- MeSH
- chromozomy metabolismus MeSH
- dospělí MeSH
- gonadální stromální nádory * genetika patologie MeSH
- lidé středního věku MeSH
- lidé MeSH
- proteiny S100 MeSH
- testikulární nádory * patologie MeSH
- variabilita počtu kopií segmentů DNA MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- multicentrická studie MeSH
- Názvy látek
- proteiny S100 MeSH
Faithful chromosome segregation into gametes depends on Spo11-induced DNA double-strand breaks (DSBs). These yield single-stranded 3' tails upon resection to promote crossovers (COs). While early Mre11-dependent end resection is the predominant pathway in most organisms, Exo1 or Dna2/BLM can also contribute to the efficient processing of meiotic DSBs. Although its enzymatic activity has been thoroughly dissected, the temporal dynamics underlying Spo11 activity have remained mostly elusive. We show that, in Caenorhabditis elegans, SPO-11-mediated DSB induction takes place throughout early meiotic prophase I until mid-late pachynema. We find that late DSBs are essential for CO formation and are preferentially processed by EXO-1 and DNA-2 in a redundant fashion. Further, EXO-1-DNA-2-mediated resection ensures completion of conservative DSB repair and discourages activation of KU-dependent end joining. Taken together, our data unveil important temporal aspects of DSB induction and identify previously unknown functional implications for EXO-1-DNA-2-mediated resection activity in C. elegans.
- Klíčová slova
- CP: Cell biology, CP: Molecular biology,
- MeSH
- Caenorhabditis elegans * genetika metabolismus MeSH
- chromozomy metabolismus MeSH
- dvouřetězcové zlomy DNA MeSH
- meióza MeSH
- oprava DNA MeSH
- proteiny Caenorhabditis elegans * genetika metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
- Názvy látek
- proteiny Caenorhabditis elegans * MeSH
Cellular leiomyoma (CL) represents an uncommon variant of uterine leiomyoma with limited data concerning its immunohistochemical and molecular profile. We performed a comprehensive analysis of 52 CL cases all of which were analyzed immunohistochemically. Molecular analysis was possible in 32 cases with sufficient DNA, and 38 cases with sufficient RNA. The immunohistochemical results showed a high expression of smooth muscle markers (calponin (100%), desmin (100%), smooth muscle actin (98.1%), caldesmon (96.1%), transgelin (96.1%), smooth muscle myosin heavy chain (86.5%), and smoothelin (61.5%)). Concerning markers of endometrial stromal differentiation, the expression of CD10 was observed in 65.4% cases (42.2% with H-score > 50), and IFITM1 in 36.5% cases (1.9% with H-score > 50). 36.5% showed HMGA2 overexpression at the IHC level, associated with increased mRNA expression in 14/14 cases. The rearrangement of the HMGA2 gene was detected in 13.2%. Chromosome 1p deletion was found in 19.3%, while 9.4% of tumors showed a pathogenic mutation in the MED12 gene. In conclusion, CL is immunohistochemically characterized by a high expression of "smooth muscle" markers commonly associated with a co-expression of "endometrial stromal" markers, where IFITM1 shows superior performance compared to CD10 regarding its specificity for differentiation from endometrial stromal tumors. The sensitivity of smoothelin in CL seems rather low, but no data is available to assess its specificity. On a molecular level, the most common mutually exclusive aberration in CL affects HMGA2, followed by chromosome 1p deletions and MED12 mutations.
- Klíčová slova
- Cellular leiomyoma, Chromosome 1p, HMGA2, MED12, NGS, ddPCR,
- MeSH
- chromozomy chemie metabolismus MeSH
- leiomyom * patologie MeSH
- lidé MeSH
- mediátorový komplex genetika metabolismus MeSH
- mutace MeSH
- nádory dělohy * patologie MeSH
- nádory endometria * genetika MeSH
- neprilysin analýza MeSH
- protein HMGA2 MeSH
- Check Tag
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- HMGA2 protein, human MeSH Prohlížeč
- MED12 protein, human MeSH Prohlížeč
- mediátorový komplex MeSH
- neprilysin MeSH
- protein HMGA2 MeSH
Chromera velia is an alveolate alga which represents the closest known phototrophic relative to apicomplexan parasites. Although the nuclear, mitochondrial, and plastid genomes of this alga have been sequenced, the number of chromosomes and ploidy of C. velia are unknown. We explored ploidy in the vegetative cell, the predominant stage in cultures of Chromera, using the tyramide signal amplification-fluorescence in situ hybridization (TSA-FISH) in isolated nuclei of C. velia. Probes were derived from three single copy genes coding for 4-diphosphocytidyl-2-C-methyl-D-erythritol (CDP-ME) kinase, 2-C-methyl-D-erythritol 2,4-cyclodiphosphate (MEcPP) synthase and Topoisomerase II. Our results indicate that the vegetative cell of C. velia is haploid, as each probe produced a single fluorescent signal, although the possibility of diploidy with somatic pairing of homologous chromosomes cannot be completely excluded. Restriction analysis and hybridization with the telomere probe produced eight bands suggesting the presence of four chromosomes in haploid vegetative cells of C. velia. However, when the chromerid-specific telomere probe (TTTAGGG)4 was used for TSA-FISH, we consistently obtained a double signal. This may indicate that the four chromosomes are organized in clusters in interphase nuclei of C. velia, which is a chromosome organization similar to that of their apicomplexan relatives.
- Klíčová slova
- Life cycles, TSA-FISH, haploid, telomere fingerprinting.,
- MeSH
- Alveolata genetika růst a vývoj metabolismus MeSH
- buněčné jádro genetika metabolismus MeSH
- chromozomy genetika metabolismus MeSH
- hybridizace in situ fluorescenční MeSH
- plastidy genetika metabolismus MeSH
- ploidie * MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Nitric Oxide (NO) has been involved in both intra- and extra-cellular signaling pathways in a wide range of organisms, and can be detected in some reproductive tissues. Based upon previous results reporting that NO-donor SNAP (s-nitroso-n-acetyl penicillamine) promoted the release from the metaphase II-anaphase II block in amphibian eggs, the aim of the present study was to assess the influence of SNAP on the activation of the molecular mechanisms triggering meiotic resumption of Xenopus oocytes, analogous to G2/M transition of the cell cycle. A high concentration of SNAP (2.5 mM) was found to inhibit the appearance of the white spot (meiotic resumption) and promoted alteration of spindle morphogenesis leading to atypical structures lacking bipolarity and correct chromosomes equatorial alignment. The medium acidification (pH = 4) promoted by SNAP specifically impacted the white spot occurrence. However, even when pH was restored to 7.4 in SNAP medium, observed spindles remained atypical (microtubule disorganization), suggesting SNAP impacted spindle assembly regardless of the pH. n-Acetyl-d,l-penicillamine disulfide, a degradation product of SNAP with the same molecular characteristics, albeit without release of NO, yielded spindle assemblies typical of metaphase II suggesting the specificity of NO action on meiotic spindle morphogenesis in Xenopus oocytes.
- Klíčová slova
- MEIOSIS, NITRIC OXIDE, OOCYTE, SPINDLE, XENOPUS,
- MeSH
- aparát dělícího vřeténka účinky léků MeSH
- chromozomy metabolismus MeSH
- donory oxidu dusnatého farmakologie MeSH
- meióza účinky léků MeSH
- morfogeneze účinky léků MeSH
- oocyty cytologie účinky léků MeSH
- S-nitroso-N-acetylpenicilamin farmakologie MeSH
- Xenopus laevis MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- donory oxidu dusnatého MeSH
- S-nitroso-N-acetylpenicilamin MeSH
The parabasalid protist Trichomonas vaginalis is a widespread parasite that affects humans, frequently causing vaginitis in infected women. Trichomonad mitosis is marked by the persistence of the nuclear membrane and the presence of an asymmetric extranuclear spindle with no obvious direct connection to the chromosomes. No centromeric markers have been described in T. vaginalis, which has prevented a detailed analysis of mitotic events in this organism. In other eukaryotes, nucleosomes of centromeric chromatin contain the histone H3 variant CenH3. The principal aim of this work was to identify a CenH3 homolog in T. vaginalis. We performed a screen of the T. vaginalis genome to retrieve sequences of canonical and variant H3 histones. Three variant histone H3 proteins were identified, and the subcellular localization of their epitope-tagged variants was determined. The localization of the variant TVAG_185390 could not be distinguished from that of the canonical H3 histone. The sequence of the variant TVAG_087830 closely resembled that of histone H3. The tagged protein colocalized with sites of active transcription, indicating that the variant TVAG_087830 represented H3.3 in T. vaginalis. The third H3 variant (TVAG_224460) was localized to 6 or 12 distinct spots at the periphery of the nucleus, corresponding to the number of chromosomes in G(1) phase and G(2) phase, respectively. We propose that this variant represents the centromeric marker CenH3 and thus can be employed as a tool to study mitosis in T. vaginalis. Furthermore, we suggest that the peripheral distribution of CenH3 within the nucleus results from the association of centromeres with the nuclear envelope throughout the cell cycle.
- MeSH
- aktivace transkripce MeSH
- buněčné jádro genetika metabolismus MeSH
- centromera genetika metabolismus MeSH
- chromozomy genetika metabolismus MeSH
- fluorescenční mikroskopie MeSH
- G1 fáze MeSH
- G2 fáze MeSH
- genom protozoální * MeSH
- histony genetika metabolismus MeSH
- jaderný obal metabolismus MeSH
- mitóza MeSH
- molekulární sekvence - údaje MeSH
- nukleozomy metabolismus MeSH
- protozoální proteiny genetika metabolismus MeSH
- sekvence aminokyselin MeSH
- sekvenční analýza proteinů MeSH
- transformace genetická MeSH
- Trichomonas vaginalis genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- histony MeSH
- nukleozomy MeSH
- protozoální proteiny MeSH
During meiosis, pairing of homologous chromosomes and their synapsis are essential prerequisites for normal male gametogenesis. Even limited autosomal asynapsis often leads to spermatogenic impairment, the mechanism of which is not fully understood. The present study was aimed at deliberately increasing the size of partial autosomal asynapsis and analysis of its impact on male meiosis. For this purpose, we studied the effect of t(12) haplotype encompassing four inversions on chromosome 17 on mouse autosomal translocation T(16;17)43H (abbreviated T43H). The T43H/T43H homozygotes were fully fertile in both sexes, while +/T43H heterozygous males, but not females, were sterile with meiotic arrest at late pachynema. Inclusion of the t(12) haplotype in trans to the T43H translocation resulted in enhanced asynapsis of the translocated autosome, ectopic phosphorylation of histone H2AX, persistence of RAD51 foci, and increased gene silencing around the translocation break. Increase was also on colocalization of unsynapsed chromatin with sex body. Remarkably, we found that transcriptional silencing of the unsynapsed autosomal chromatin precedes silencing of sex chromosomes. Based on the present knowledge, we conclude that interference of meiotic silencing of unsynapsed autosomes with meiotic sex chromosome inactivation is the most likely cause of asynapsis-related male sterility.
- MeSH
- biologické modely MeSH
- chromatin metabolismus fyziologie MeSH
- chromozomy genetika metabolismus MeSH
- genetická transkripce genetika MeSH
- hybridizace in situ fluorescenční MeSH
- meióza genetika fyziologie MeSH
- myši inbrední C57BL MeSH
- myši MeSH
- párování chromozomů genetika MeSH
- pohlavní chromozomy genetika metabolismus MeSH
- regulace genové exprese MeSH
- translokace genetická genetika MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- chromatin MeSH
In monocentric organisms with asymmetric meiosis, the kinetochore proteins, such as CENH3 and CENP-C, evolve adaptively to counterbalance the deleterious effects of centromere drive, which is caused by the expansion of centromeric satellite repeats. The selection regimes that act on CENH3 and CENP-C genes have not been analyzed in organisms with holocentric chromosomes, although holocentrism is speculated to have evolved to suppress centromere drive. We tested both CENH3 and CENP-C for positive selection in several species of the holocentric genus Caenorhabditis using the maximum likelihood approach and sliding-window analysis. Although CENP-C did not show any signs of positive selection, positive selection has been detected in the case of CENH3. These results support the hypothesis that centromere drive occurs in Nematoda, at least in the telokinetic meiosis of Caenorhabditis.
- MeSH
- Caenorhabditis elegans genetika metabolismus MeSH
- centromera metabolismus fyziologie MeSH
- chromozomální proteiny, nehistonové genetika metabolismus fyziologie MeSH
- chromozomy metabolismus MeSH
- geneticky modifikované organismy MeSH
- histony genetika fyziologie MeSH
- meióza genetika fyziologie MeSH
- pohyb fyziologie MeSH
- segregace chromozomů genetika fyziologie MeSH
- selekce (genetika) MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- centromere protein C MeSH Prohlížeč
- chromozomální proteiny, nehistonové MeSH
- histony MeSH
The radial position of a gene within its chromosome territory (CT) in the interphase nucleus is thought to depend on the transcriptional activity of the gene and on transcriptional activity, gene density, and conformation of the chromosomal surrounding. In this study we analyzed the position of the cell cycle regulator gene p21 within the CT of human chromosome 6 (HSA6) upon transcriptional activation. Whereas the majority of active p21 genes is located in the interior of the CT of HSA6, induction of p21 transcription correlates with increased variation of gene localization within the CT and with a higher percentage of p21 genes located at the periphery of the CT. Additionally it demonstrates once more that transcription can take place throughout CTs. Comparison of the p21 locus with two non-coding regions on HSA6 showed that both non-coding sequences are located more frequently in the interior of the CT than p21 genes although they are situated in chromosomal neighborhoods with widely differing gene density and regional transcriptional activity. Thus our data support models describing an influence of the transcriptional activity of a gene on the localization within its CT. However, our data also indicate that additional factors such as chromatin remodeling are implicated in the positioning of genes within the respective chromosome territory.
- MeSH
- aktivace transkripce genetika fyziologie MeSH
- chromozomy metabolismus MeSH
- hybridizace in situ fluorescenční MeSH
- inhibitor p21 cyklin-dependentní kinasy genetika MeSH
- lidé MeSH
- nádorové buněčné linie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- inhibitor p21 cyklin-dependentní kinasy MeSH
