The nuclear lamina is the main component of the nuclear cytoskeleton that maintains the integrity of the nucleus. However, it represents a natural barrier for viruses replicating in the cell nucleus. The lamina blocks viruses from being trafficked to the nucleus for replication, but it also impedes the nuclear egress of the progeny of viral particles. Thus, viruses have evolved mechanisms to overcome this obstacle. Large viruses induce the assembly of multiprotein complexes that are anchored to the inner nuclear membrane. Important components of these complexes are the viral and cellular kinases phosphorylating the lamina and promoting its disaggregation, therefore allowing virus egress. Small viruses also use cellular kinases to induce lamina phosphorylation and the subsequent disruption in order to facilitate the import of viral particles during the early stages of infection or during their nuclear egress. Another component of the nuclear cytoskeleton, nuclear actin, is exploited by viruses for the intranuclear movement of their particles from the replication sites to the nuclear periphery. This study focuses on exploitation of the nuclear cytoskeleton by viruses, although this is just the beginning for many viruses, and promises to reveal the mechanisms and dynamic of physiological and pathological processes in the nucleus.
- MeSH
- aktiny metabolismus MeSH
- buněčné jádro metabolismus MeSH
- cytoskelet genetika metabolismus MeSH
- druhová specificita MeSH
- interakce hostitele a patogenu * MeSH
- jaderná lamina metabolismus MeSH
- jaderný obal metabolismus MeSH
- laminy metabolismus MeSH
- lidé MeSH
- náchylnost k nemoci * MeSH
- regulace exprese virových genů MeSH
- replikace viru MeSH
- virové nemoci etiologie metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
The nuclear lamina supports many functions, including maintaining nuclear structure and gene expression control, and correct spatio-temporal assembly is vital to meet these activities. Recently, multiple lamina systems have been described that, despite independent evolutionary origins, share analogous functions. In trypanosomatids the two known lamina proteins, NUP-1 and NUP-2, have molecular masses of 450 and 170 kDa, respectively, which demands a distinct architecture from the ∼60 kDa lamin-based system of metazoa and other lineages. To uncover organizational principles for the trypanosome lamina we generated NUP-1 deletion mutants to identify domains and their arrangements responsible for oligomerization. We found that both the N- and C-termini act as interaction hubs, and that perturbation of these interactions impacts additional components of the lamina and nuclear envelope. Furthermore, the assembly of NUP-1 terminal domains suggests intrinsic organizational capacity. Remarkably, there is little impact on silencing of telomeric variant surface glycoprotein genes. We suggest that both terminal domains of NUP-1 have roles in assembling the trypanosome lamina and propose a novel architecture based on a hub-and-spoke configuration.
Differentiated nuclei can be reprogrammed/remodelled to totipotency after their transfer to enucleated metaphase II (MII) oocytes. The process of reprogramming/remodelling is, however, only partially characterized. It has been shown that the oocyte nucleus (germinal vesicle - GV) components are essential for a successful remodelling of the transferred nucleus by providing the materials for pseudo-nucleus formation. However, the nucleus is a complex structure and exactly what nuclear components are required for a successful nucleus remodelling and reprogramming is unknown. Till date, the only nuclear sub-structure experimentally demonstrated to be essential is the oocyte nucleolus (nucleolus-like body, NLB). In this study, we investigated what other GV components might be necessary for the formation of normal-sized pseudo-pronuclei (PNs). Our results showed that the removal of the GV nuclear envelope with attached chromatin and chromatin-bound factors does not substantially influence the size of the remodelled nuclei in reconstructed cells and that their nuclear envelopes seem to have normal parameters. Rather than the insoluble nuclear lamina, the GV content, which is dissolved in the cytoplasm with the onset of oocyte maturation, influences the characteristics and size of transferred nuclei.
- MeSH
- buněčné jadérko metabolismus MeSH
- buněčné jádro metabolismus MeSH
- chromatin metabolismus MeSH
- cytoplazma metabolismus MeSH
- jaderná lamina metabolismus MeSH
- jaderný obal metabolismus MeSH
- messenger RNA metabolismus MeSH
- myši MeSH
- oocyty cytologie metabolismus MeSH
- oogeneze MeSH
- ovariální folikul metabolismus MeSH
- přeprogramování buněk * MeSH
- techniky jaderného přenosu * MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
The organization of the nuclear periphery is crucial for many nuclear functions. Nuclear lamins form dense network at the nuclear periphery and play a substantial role in chromatin organization, transcription regulation and in organization of nuclear pore complexes (NPCs). Here, we show that TPR, the protein located preferentially within the nuclear baskets of NPCs, associates with lamin B1. The depletion of TPR affects the organization of lamin B1 but not lamin A/C within the nuclear lamina as shown by stimulated emission depletion microscopy. Finally, reduction of TPR affects the distribution of NPCs within the nuclear envelope and the effect can be reversed by simultaneous knock-down of lamin A/C or the overexpression of lamin B1. Our work suggests a novel role for the TPR at the nuclear periphery: the TPR contributes to the organization of the nuclear lamina and in cooperation with lamins guards the interphase assembly of nuclear pore complexes.
- MeSH
- HeLa buňky MeSH
- jaderná lamina metabolismus ultrastruktura MeSH
- jaderný obal metabolismus ultrastruktura MeSH
- komplex proteinů jaderného póru antagonisté a inhibitory genetika metabolismus MeSH
- lamin typ A antagonisté a inhibitory genetika metabolismus MeSH
- lamin typ B genetika metabolismus MeSH
- lidé MeSH
- malá interferující RNA genetika metabolismus MeSH
- molekulární zobrazování MeSH
- protoonkogenní proteiny antagonisté a inhibitory genetika metabolismus MeSH
- regulace genové exprese MeSH
- signální transdukce MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The replication of the genome is a highly organized process, both spatially and temporally. Although a lot is known on the composition of the basic replication machinery, how its activity is regulated is mostly unknown. Several chromatin properties have been proposed as regulators, but a potential role of the nuclear DNA position remains unclear. We made use of the prominent structure and well-defined heterochromatic landscape of mouse pericentric chromosome domains as a well-studied example of late replicating constitutive heterochromatin. We established a method to manipulate its nuclear position and evaluated the effect on replication timing, DNA compaction and epigenetic composition. Using time-lapse microscopy, we observed that constitutive heterochromatin, known to replicate during late S-phase, was replicated in mid S-phase when repositioned to the nuclear periphery. Out-of-schedule replication resulted in deficient post-replicative maintenance of chromatin modifications, namely silencing marks. We propose that repositioned constitutive heterochromatin was activated in trans according to the domino model of origin firing by nearby (mid S) firing origins. In summary, our data provide, on the one hand, a novel approach to manipulate nuclear DNA position and, on the other hand, establish nuclear DNA position as a novel mechanism regulating DNA replication timing and epigenetic maintenance.
- MeSH
- buněčné jádro genetika ultrastruktura MeSH
- buněčné linie MeSH
- DNA analýza MeSH
- heterochromatin * MeSH
- histonový kód * MeSH
- histony metabolismus MeSH
- jaderná lamina ultrastruktura MeSH
- jaderný pór ultrastruktura MeSH
- metylace MeSH
- myši MeSH
- načasování replikace DNA * MeSH
- S fáze genetika MeSH
- umlčování genů MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The nuclear lamina represents a multifunctional platform involved in such diverse yet interconnected processes as spatial organization of the genome, maintenance of mechanical stability of the nucleus, regulation of transcription and replication. Most of lamina activities are exerted through tethering of lamina-associated chromatin domains (LADs) to the nuclear periphery. Yet, the lamina is a dynamic structure demonstrating considerable expansion during the cell cycle to accommodate increased number of LADs formed during DNA replication. We analyzed dynamics of nuclear growth during interphase and changes in lamina structure as a function of cell cycle progression. The nuclear lamina demonstrates steady growth from G1 till G2, while quantitative analysis of lamina meshwork by super-resolution microscopy revealed that microdomain organization of the lamina is maintained, with lamin A and lamin B microdomain periodicity and interdomain gap sizes unchanged. FRAP analysis, in contrast, demonstrated differences in lamin A and B1 exchange rates; the latter showing higher recovery rate in S-phase cells. In order to further analyze the mechanism of lamina growth in interphase, we generated a lamina-free nuclear envelope in living interphase cells by reversible hypotonic shock. The nuclear envelope in nuclear buds formed after such a treatment initially lacked lamins, and analysis of lamina formation revealed striking difference in lamin A and B1 assembly: lamin A reassembled within 30 min post-treatment, whereas lamin B1 did not incorporate into the newly formed lamina at all. We suggest that in somatic cells lamin B1 meshwork growth is coordinated with replication of LADs, and lamin A meshwork assembly seems to be chromatin-independent process.
- MeSH
- Cricetulus MeSH
- interfáze * MeSH
- jaderná lamina chemie metabolismus MeSH
- kultivované buňky MeSH
- lidé MeSH
- myši MeSH
- prasata MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- buňky cytologie imunologie patologie MeSH
- DNA nádorová genetika MeSH
- finanční podpora výzkumu jako téma MeSH
- indukovaná hypertermie metody využití MeSH
- jaderná matrix genetika MeSH
- lékové transportní systémy využití MeSH
- lidé MeSH
- nádorové procesy MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- srovnávací studie MeSH
- MeSH
- apoptóza fyziologie genetika MeSH
- biologické markery MeSH
- biologie buňky * organizace a řízení přístrojové vybavení trendy MeSH
- biomedicínský výzkum metody trendy MeSH
- buněčná diferenciace fyziologie genetika imunologie MeSH
- buněčná membrána fyziologie genetika imunologie MeSH
- buněčné jadérko fyziologie genetika klasifikace MeSH
- cytoskelet fyziologie genetika MeSH
- financování organizované MeSH
- intranukleární prostor fyziologie ultrastruktura MeSH
- jaderná matrix fyziologie mikrobiologie MeSH
- lidé MeSH
- mikrotubuly fyziologie genetika MeSH
- mitochondrie fyziologie genetika MeSH
- struktury buněčného jádra fyziologie genetika MeSH
- telomerasa fyziologie genetika MeSH
- výzkumné techniky MeSH
- Check Tag
- lidé MeSH
