Spinocerebellar ataxia type-1 (SCA1) is caused by an abnormally expanded polyglutamine (polyQ) tract in ataxin-1. These expansions are responsible for protein misfolding and self-assembly into intranuclear inclusion bodies (IIBs) that are somehow linked to neuronal death. However, owing to lack of a suitable cellular model, the downstream consequences of IIB formation are yet to be resolved. Here, we describe a nuclear protein aggregation model of pathogenic human ataxin-1 and characterize IIB effects. Using an inducible Sleeping Beauty transposon system, we overexpressed the ATXN1(Q82) gene in human mesenchymal stem cells that are resistant to the early cytotoxic effects caused by the expression of the mutant protein. We characterized the structure and the protein composition of insoluble polyQ IIBs which gradually occupy the nuclei and are responsible for the generation of reactive oxygen species. In response to their formation, our transcriptome analysis reveals a cerebellum-specific perturbed protein interaction network, primarily affecting protein synthesis. We propose that insoluble polyQ IIBs cause oxidative and nucleolar stress and affect the assembly of the ribosome by capturing or down-regulating essential components. The inducible cell system can be utilized to decipher the cellular consequences of polyQ protein aggregation. Our strategy provides a broadly applicable methodology for studying polyQ diseases.

• MeSH
• ataxin-1 genetika   metabolismus   MeSH
• intranukleární inkluzní tělíska * metabolismus   MeSH
• jaderné proteiny genetika   metabolismus   MeSH
• lidé MeSH
• oxidační stres MeSH
• proteiny nervové tkáně * genetika   metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The bulk of DNA damage caused by ionizing radiation (IR) is generally repaired within hours, yet a subset of DNA lesions may persist even for long periods of time. Such persisting IR-induced foci (pIRIF) co-associate with PML nuclear bodies (PML-NBs) and are among the characteristics of cellular senescence. Here we addressed some fundamental questions concerning the nature and determinants of this co-association, the role of PML-NBs at such sites, and the reason for the persistence of DNA damage in human primary cells. We show that the persistent DNA lesions are devoid of homologous recombination (HR) proteins BRCA1 and Rad51. Our super-resolution microscopy-based analysis showed that PML-NBs are juxtaposed to and partially overlap with the pIRIFs. Notably, depletion of 53BP1 resulted in decreased intersection between PML-NBs and pIRIFs implicating the RNF168-53BP1 pathway in their interaction. To test whether the formation and persistence of IRIFs is PML-dependent and to investigate the role of PML in the context of DNA repair and senescence, we genetically deleted PML in human hTERT-RPE-1 cells. Unexpectedly, upon high-dose IR treatment, cells displayed similar DNA damage signalling, repair dynamics and kinetics of cellular senescence regardless of the presence or absence of PML. In contrast, the PML knock-out cells showed increased sensitivity to low doses of IR and DNA-damaging agents mitomycin C, cisplatin and camptothecin that all cause DNA lesions requiring repair by HR. These results, along with enhanced sensitivity of the PML knock-out cells to DNA-PK and PARP inhibitors implicate PML as a factor contributing to HR-mediated DNA repair.

• MeSH
• 53BP1 metabolismus   MeSH
• genový knockout MeSH
• intranukleární inkluzní tělíska metabolismus   účinky záření   MeSH
• lidé MeSH
• oprava DNA * účinky záření   MeSH
• poškození DNA * MeSH
• protein promyelocytické leukemie nedostatek   genetika   metabolismus   MeSH
• stárnutí buněk genetika   účinky záření   MeSH
• ubikvitinligasy metabolismus   MeSH
• vztah dávky záření a odpovědi MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

The cell nucleus contains a number of different dynamic bodies that are variously composed of proteins and generally, but not always, specific RNA molecules. Recent studies have revealed new understanding about nuclear body formation and function in different aspects of nuclear metabolism. Here, we focus on findings describing the role of nuclear bodies in the biogenesis of specific ribonucleoprotein complexes, processing of key mRNAs, and subnuclear sequestration of protein factors. We highlight how nuclear bodies are involved in stress responses, innate immunity and tumorigenesis. We further review organization of nuclear bodies and principles that govern their assembly, highlighting the pivotal role of scaffolding noncoding RNAs, and liquid-liquid phase separation, which are transforming our picture of nuclear body formation.

• MeSH
• buněčné jádro metabolismus   MeSH
• intranukleární inkluzní tělíska chemie   metabolismus   patologie   MeSH
• jaderné proteiny metabolismus   MeSH
• lidé MeSH
• nekódující RNA metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

Nuclear bodies are membraneless organelles that play important roles in genome functioning. A specific type of nuclear bodies known as interphase prenucleolar bodies (iPNBs) are formed in the nucleoplasm after hypotonic stress from partially disassembled nucleoli. iPNBs are then disassembled, and the nucleoli are reformed simultaneously. Here, we show that diffusion of B23 molecules (also known as nucleophosmin, NPM1) from iPNBs, but not fusion of iPNBs with the nucleoli, contributes to the transfer of B23 from iPNBs to the nucleoli. Maturation of pre-ribosomal RNAs (rRNAs) and the subsequent outflow of mature rRNAs from iPNBs led to the disassembly of iPNBs. We found that B23 transfer was dependent on the synthesis of pre-rRNA molecules in nucleoli; these pre-rRNA molecules interacted with B23 and led to its accumulation within nucleoli. The transfer of B23 between iPNBs and nucleoli was accomplished through a nucleoplasmic pool of B23, and increased nucleoplasmic B23 content retarded disassembly, whereas B23 depletion accelerated disassembly. Our results suggest that iPNB disassembly and nucleolus assembly might be coupled through RNA-dependent exchange of nucleolar proteins, creating a highly dynamic system with long-distance correlations between spatially distinct processes.

• MeSH
• adenosintrifosfát metabolismus   MeSH
• buněčné jadérko metabolismus   MeSH
• difuze MeSH
• fyziologický stres MeSH
• HeLa buňky MeSH
• interfáze MeSH
• intranukleární inkluzní tělíska metabolismus   MeSH
• lidé MeSH
• posttranskripční úpravy RNA MeSH
• RNA metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

We studied epigenetics, distribution pattern, kinetics, and diffusion of proteins recruited to spontaneous and γ-radiation-induced DNA lesions. We showed that PML deficiency leads to an increased number of DNA lesions, which was accompanied by changes in histone signature. In PML wt cells, we observed two mobile fractions of 53BP1 protein with distinct diffusion in spontaneous lesions. These protein fractions were not detected in PML-deficient cells, characterized by slow-diffusion of 53BP1. Single particle tracking analysis revealed limited local motion of 53BP1 foci in PML double null cells and local motion 53BP1 foci was even more reduced after γ-irradiation. However, radiation did not change co-localization between 53BP1 nuclear bodies and interchromatin granule-associated zones (IGAZs), nuclear speckles, or chromocenters. This newly observed interaction pattern imply that 53BP1 protein could be a part of not only DNA repair, but also process mediated via components accumulated in IGAZs, nuclear speckles, or paraspeckles. Together, PML deficiency affected local motion of 53BP1 nuclear bodies and changed composition and a number of irradiation-induced foci. J. Cell. Biochem. 117: 2583-2596, 2016. © 2016 Wiley Periodicals, Inc.

• MeSH
• 53BP1 metabolismus   MeSH
• akutní promyelocytární leukemie metabolismus   patologie   radioterapie   MeSH
• fluorescenční protilátková technika MeSH
• intranukleární inkluzní tělíska metabolismus   patologie   účinky záření   MeSH
• konfokální mikroskopie MeSH
• lidé MeSH
• nádorové buňky kultivované MeSH
• oprava DNA fyziologie   účinky záření   MeSH
• poškození DNA fyziologie   účinky záření   MeSH
• vztah dávky záření a odpovědi MeSH
• western blotting MeSH
• záření gama škodlivé účinky   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH

We used hybrid detectors (HyDs) to monitor the trajectories and interactions of promyelocytic leukemia (GFP-PML) nuclear bodies (NBs) and mCherry-53BP1-positive DNA lesions. 53BP1 protein accumulates in NBs that occur spontaneously in the genome or in γ-irradiation-induced foci. When we induced local DNA damage by ultraviolet irradiation, we also observed accumulation of 53BP1 proteins into discrete bodies, instead of the expected dispersed pattern. In comparison with photomultiplier tubes, which are used for standard analysis by confocal laser scanning microscopy, HyDs significantly eliminated photobleaching of GFP and mCherry fluorochromes during image acquisition. The low laser intensities used for HyD-based confocal analysis enabled us to observe NBs for the longer time periods, necessary for studies of the trajectories and interactions of PML and 53BP1 NBs. To further characterize protein interactions, we used resonance scanning and a novel bioinformatics approach to register and analyze the movements of individual PML and 53BP1 NBs. The combination of improved HyD-based confocal microscopy with a tailored bioinformatics approach enabled us to reveal damage-specific properties of PML and 53BP1 NBs.

• MeSH
• akutní promyelocytární leukemie metabolismus   patologie   MeSH
• časosběrné zobrazování MeSH
• DNA chemie   metabolismus   MeSH
• intracelulární signální peptidy a proteiny metabolismus   MeSH
• intranukleární inkluzní tělíska metabolismus   ultrastruktura   MeSH
• konfokální mikroskopie přístrojové vybavení   metody   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• poškození DNA MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• práce podpořená grantem MeSH

BACKGROUND INFORMATION: Promyelocytic leukaemia (PML) bodies are specific nuclear structures with functional significance for acute promyelocytic leukaemia. In this study, we analysed the trajectories of PML bodies using single-particle tracking. RESULTS: We observed that the recovery of PML protein after photobleaching was ATP dependent in both wild-type (wt) and A-type lamin-deficient cells. The movement of PML bodies was faster and the nuclear area occupied by particular PML bodies was larger in A-type lamin-deficient fibroblasts compared with their wt counterparts. Moreover, dysfunction of the LMNA gene increased the frequency of mutual interactions between individual PML bodies and influenced the morphology of these domains at the ultrastructural level. As a consequence of A-type lamin deficiency, PML protein accumulated in nuclear blebs and frequently appeared at the nuclear periphery. CONCLUSIONS: We suggest that the physiological function of lamin A proteins is important for events that occur in the compartment of PML bodies. This observation was confirmed in other experimental models characterised by lamin changes, including apoptosis or the differentiation of mouse embryonic stem cells.

• MeSH
• akutní promyelocytární leukemie metabolismus   MeSH
• apoptóza MeSH
• embryo savčí cytologie   MeSH
• embryonální kmenové buňky cytologie   metabolismus   MeSH
• fibroblasty cytologie   metabolismus   ultrastruktura   MeSH
• FRAP MeSH
• intranukleární inkluzní tělíska metabolismus   ultrastruktura   MeSH
• kinetika MeSH
• lamin typ A nedostatek   metabolismus   MeSH
• myši MeSH
• reprodukovatelnost výsledků MeSH
• zelené fluorescenční proteiny metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Telomeres are specialized chromatin structures that are situated at the end of linear chromosomes and play an important role in cell senescence and immortalization. Here, we investigated whether changes in histone signature influence the nuclear arrangement and positioning of telomeres. Analysis of mouse embryonic fibroblasts revealed that telomeres were organized into specific clusters that partially associated with centromeric clusters. This nuclear arrangement was influenced by deficiency of the histone methyltransferase SUV39h, LMNA deficiency, and the histone deacetylase inhibitor Trichostatin A (TSA). Similarly, nuclear radial distributions of telomeric clusters were preferentially influenced by TSA, which caused relocation of telomeres closer to the nuclear center. Telomeres also co-localized with promyelocytic leukemia bodies (PML). This association was increased by SUV39h deficiency and decreased by LMNA deficiency. These differences could be explained by differing levels of the telomerase subunit, TERT, in SUV39h- and LMNA-deficient fibroblasts. Taken together, our data show that SUV39h and A-type lamins likely play a key role in telomere maintenance and telomere nuclear architecture.

• MeSH
• DNA vazebné proteiny metabolismus   MeSH
• epigeneze genetická MeSH
• fibroblasty metabolismus   MeSH
• genová přestavba MeSH
• intranukleární inkluzní tělíska metabolismus   MeSH
• lamin typ A metabolismus   MeSH
• lidé MeSH
• methyltransferasy metabolismus   MeSH
• myši MeSH
• protein TRF1 metabolismus   MeSH
• průtoková cytometrie MeSH
• rap1 proteiny vázající GTP metabolismus   MeSH
• represorové proteiny metabolismus   MeSH
• telomerasa metabolismus   MeSH
• telomery genetika   metabolismus   MeSH
• transport proteinů MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH