• MeSH
• buněčná smrt MeSH
• buněčné jadérko fyziologie   účinky léků   MeSH
• cisplatina toxicita   MeSH
• HeLa buňky enzymologie   genetika   účinky léků   MeSH
• jaderné proteiny metabolismus   MeSH
• kaspasy fyziologie   účinky léků   MeSH
• lidé MeSH
• RNA jaderná fyziologie   účinky léků   MeSH
• techniky in vitro MeSH
• Check Tag
• lidé MeSH

Diverse stress insults trigger interactions of PML with nucleolus, however, the function of these PML nucleolar associations (PNAs) remains unclear. Here we show that during induction of DNA damage-induced senescence in human non-cancerous cells, PML accumulates at the nucleolar periphery simultaneously with inactivation of RNA polymerase I (RNAP I) and nucleolar segregation. Using time-lapse and high-resolution microscopy, we followed the genesis, structural transitions and destiny of PNAs to show that: 1) the dynamic structural changes of the PML-nucleolar interaction are tightly associated with inactivation and reactivation of RNAP I-mediated transcription, respectively; 2) the PML-nucleolar compartment develops sequentially under stress and, upon stress termination, it culminates in either of two fates: disappearance or persistence; 3) all PNAs stages can associate with DNA damage markers; 4) the persistent, commonly long-lasting PML multi-protein nucleolar structures (PML-NDS) associate with markers of DNA damage, indicating a role of PNAs in persistent DNA damage response characteristic for senescent cells. Given the emerging evidence implicating PML in homologous recombination-directed DNA repair, we propose that PNAs contribute to sequestration and faithful repair of the highly unstable ribosomal DNA repeats, a fundamental process to maintain a precise balance between DNA repair mechanisms, with implications for genomic integrity and aging.

• MeSH
• buněčné jadérko metabolismus   MeSH
• doxorubicin MeSH
• fyziologický stres MeSH
• kultivované buňky MeSH
• lidé MeSH
• poškození DNA * MeSH
• protein promyelocytické leukemie metabolismus   MeSH
• stárnutí buněk * MeSH
• zobrazování trojrozměrné MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Promyelocytic leukemia protein (PML), a tumor suppressor, forms in most human cell types discrete multiprotein complexes termed PML nuclear bodies. Here, we have used indirect immunofluorescence and confocal microscopy to describe various forms of a novel nuclear PML compartment associated with nucleoli that is found under growth-permitting conditions in human mesenchymal stem cells (hMSC) and skin fibroblasts but not in several immortal cell lines with defects in the p53 and pRb pathways. In addition, we found that shut-off of rRNA synthesis induced by actinomycin D causes PML translocation to the surface of segregated nucleoli. This translocation is dynamic and reversible, following changes in nucleolar activity. Intriguingly, treatment causing premature senescence restores PML binding to nucleoli-derived structures and to the surface of segregated nucleoli in HeLa cells. These findings indicate that PML may be involved in nucleolar functions of normal non-transformed or senescent cells. The absence of nucleolar PML compartment in rapidly growing tumor-derived cells suggests that PML association with the nucleolus might be important for cell-cycle regulation.

• MeSH
• buněčné jadérko chemie   ultrastruktura   MeSH
• buněčné linie MeSH
• fibroblasty cytologie   MeSH
• financování organizované MeSH
• fluorescenční mikroskopie MeSH
• HeLa buňky MeSH
• jaderné proteiny analýza   metabolismus   MeSH
• lidé MeSH
• mezenchymální kmenové buňky cytologie   MeSH
• nádorové buněčné linie MeSH
• nádorové proteiny analýza   metabolismus   MeSH
• nádorové supresorové proteiny analýza   metabolismus   MeSH
• nádory patologie   MeSH
• stárnutí buněk MeSH
• transkripční faktory analýza   metabolismus   MeSH
• transport proteinů MeSH
• Check Tag
• lidé MeSH

• MeSH
• apoptóza účinky záření   MeSH
• buněčné jádro ultrastruktura   MeSH
• cisplatina farmakologie   MeSH
• frakcionace buněk MeSH
• HeLa buňky MeSH
• kaspasy metabolismus   MeSH
• lidé MeSH
• Check Tag
• lidé MeSH

Heat shock transcription factors (Hsfs) are involved in multiple aspects of stress response and plant growth. However, their role during male gametophyte development is largely unknown, although the generative phase is the most sensitive and critical period in the plant life cycle. Based on a wide screen of T-DNA mutant lines, we identified the atren1 mutation (restricted to nucleolus1) in early male gametophytic gene At1g77570, which has the closest homology to HSFA5 gene, the member of a heat shock transcription factor (HSF) gene family. The mutation causes multiple defects in male gametophyte development in both structure and function. Because the mutation disrupts an early acting (AtREN1) gene, these pollen phenotype abnormalities appear from bicellular pollen stage to pollen maturation. Moreover, the consequent progamic phase is compromised as well as documented by pollen germination defects and limited transmission via male gametophyte. In addition, atren1/- plants are defective in heat stress (HS) response and produce notably higher proportion of aberrant pollen grains. AtREN1 protein is targeted specifically to the nucleolus that, together with the increased size of the nucleolus in atren1 pollen, suggests that it is likely to be involved in ribosomal RNA biogenesis or other nucleolar functions.

• MeSH
• alely MeSH
• Arabidopsis cytologie   růst a vývoj   metabolismus   MeSH
• buněčné jadérko metabolismus   MeSH
• DNA bakterií genetika   MeSH
• DNA vazebné proteiny genetika   metabolismus   MeSH
• exony genetika   MeSH
• fenotyp MeSH
• klíčení MeSH
• mutace genetika   MeSH
• penetrance MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• pyl cytologie   genetika   růst a vývoj   MeSH
• pylová láčka cytologie   genetika   růst a vývoj   MeSH
• reakce na tepelný šok * genetika   MeSH
• regulace genové exprese u rostlin MeSH
• segregace chromozomů genetika   MeSH
• testy genetické komplementace MeSH
• transport proteinů MeSH
• vývojová regulace genové exprese MeSH
• zelené fluorescenční proteiny metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

PML, a multifunctional protein, is crucial for forming PML-nuclear bodies involved in stress responses. Under specific conditions, PML associates with nucleolar caps formed after RNA polymerase I (RNAPI) inhibition, leading to PML-nucleolar associations (PNAs). This study investigates PNAs-inducing stimuli by exposing cells to various genotoxic stresses. We found that the most potent inducers of PNAs introduced topological stress and inhibited RNAPI. Doxorubicin, the most effective compound, induced double-strand breaks (DSBs) in the rDNA locus. PNAs co-localized with damaged rDNA, segregating it from active nucleoli. Cleaving the rDNA locus with I-PpoI confirmed rDNA damage as a genuine stimulus for PNAs. Inhibition of ATM, ATR kinases, and RAD51 reduced I-PpoI-induced PNAs, highlighting the importance of ATM/ATR-dependent nucleolar cap formation and homologous recombination (HR) in their triggering. I-PpoI-induced PNAs co-localized with rDNA DSBs positive for RPA32-pS33 but deficient in RAD51, indicating resected DNA unable to complete HR repair. Our findings suggest that PNAs form in response to persistent rDNA damage within the nucleolar cap, highlighting the interplay between PML/PNAs and rDNA alterations due to topological stress, RNAPI inhibition, and rDNA DSBs destined for HR. Cells with persistent PNAs undergo senescence, suggesting PNAs help avoid rDNA instability, with implications for tumorigenesis and aging.

• MeSH
• buněčné jadérko * metabolismus   MeSH
• dvouřetězcové zlomy DNA MeSH
• lidé MeSH
• poškození DNA MeSH
• protein promyelocytické leukemie * metabolismus   genetika   MeSH
• ribozomální DNA * genetika   metabolismus   MeSH
• RNA-polymerasa I metabolismus   genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

• MeSH
• apoptóza MeSH
• buněčné jadérko fyziologie   ultrastruktura   MeSH
• ischemie MeSH
• koronární cévy MeSH
• krysa rodu rattus MeSH
• myokard cytologie   MeSH
• srdce MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• zvířata MeSH
• Publikační typ
• srovnávací studie MeSH

• MeSH
• buněčná smrt MeSH
• buněčné jadérko fyziologie   účinky léků   ultrastruktura   MeSH
• buněčné jádro fyziologie   MeSH
• doxorubicin toxicita   MeSH
• kosterní svalová vlákna fyziologie   účinky léků   ultrastruktura   MeSH
• krysa rodu rattus MeSH
• myokard cytologie   MeSH
• srdce účinky léků   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• zvířata MeSH

Homologous chromosome segregation during meiosis I (MI) in mammalian oocytes is carried out by the acentrosomal MI spindles. Whereas studies in human oocytes identified Ran GTPase as a crucial regulator of the MI spindle function, experiments in mouse oocytes questioned the generality of this notion. Here, we use live-cell imaging with fluorescent probes and Förster resonance energy transfer (FRET) biosensors to monitor the changes in Ran and importin β signaling induced by perturbations of Ran in mouse oocytes while examining the MI spindle dynamics. We show that unlike RanT24N employed in previous studies, a RanT24N, T42A double mutant inhibits RanGEF without perturbing cargo binding to importin β and disrupts MI spindle function in chromosome segregation. Roles of Ran and importin β in the coalescence of microtubule organizing centers (MTOCs) and MI spindle assembly are further supported by the use of the chemical inhibitor importazole, whose effects are partially rescued by the GTP hydrolysis-resistant RanQ69L mutant. These results indicate that RanGTP is essential for MI spindle assembly and function both in humans and mice.

• MeSH
• aparát dělícího vřeténka fyziologie   MeSH
• beta karyoferiny genetika   metabolismus   MeSH
• jaderné proteiny genetika   metabolismus   MeSH
• meióza fyziologie   MeSH
• mikrotubuly metabolismus   MeSH
• mutace MeSH
• myši MeSH
• oocyty cytologie   metabolismus   MeSH
• proteiny buněčného cyklu genetika   metabolismus   MeSH
• ran protein vázající GTP genetika   metabolismus   MeSH
• segregace chromozomů MeSH
• výměnné faktory guaninnukleotidů genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

Karyotypes of eight populations of Sphaerium corneum and two populations of S. nucleus (Bivalvia: Sphaeriidae) from central Europe were compared. The basic set of these hermaphroditic molluscs is formed by 30 biarmed autosomes and exhibits only slight interpopulational variation in morphology. These differences are not species-specific. One pair of nucleolar organiser regions was detected by silver staining. The prophase and metaphase of the first meiotic division is highly modified in both species. Pachytene is followed by a diffuse stage, characterized by decondensation of chromosomes and by enhanced metabolic activity. The diffuse stage has not been reported in bivalves so far. Bivalents of the following stages are achiasmatic both in the testicular and ovarian part of the gonad. The two species are further peculiar for occurrence of B chromosomes, which is a rare phenomenon in organisms with achiasmatic meiotic systems. The small metacentric B chromosomes exhibit intra- and interindividual variability in number, they show irregular meiotic pairing and segregation (formation of bivalents or univalents), and possess larger proportional amount of constitutive heterochromatin than the A chromosomes. Interestingly, the B chromosomes also undergo decondensation during the diffuse stage like A chromosomes which may indicate their transcriptional activity.

• MeSH
• barvení stříbrem metody   MeSH
• buněčné jádro genetika   MeSH
• chromozomy fyziologie   MeSH
• heterochromatin MeSH
• karyotypizace MeSH
• meióza fyziologie   MeSH
• mlži genetika   MeSH
• organizátor jadérka metabolismus   MeSH
• ovarium cytologie   MeSH
• profáze meiózy I fyziologie   MeSH
• testis cytologie   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• srovnávací studie MeSH