Lamins, the nuclear intermediate filaments, are important regulators of nuclear structural integrity as well as nuclear functional processes such as DNA transcription, replication and repair, and epigenetic regulations. A portion of phosphorylated lamin A/C localizes to the nuclear interior in interphase, forming a lamin A/C pool with specific properties and distinct functions. Nucleoplasmic lamin A/C molecular functions are mainly dependent on its binding partners; therefore, revealing new interactions could give us new clues on the lamin A/C mechanism of action. In the present study, we show that lamin A/C interacts with nuclear phosphoinositides (PIPs), and with nuclear myosin I (NM1). Both NM1 and nuclear PIPs have been previously reported as important regulators of gene expression and DNA damage/repair. Furthermore, phosphorylated lamin A/C forms a complex with NM1 in a phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2)-dependent manner in the nuclear interior. Taken together, our study reveals a previously unidentified interaction between phosphorylated lamin A/C, NM1, and PI(4,5)P2 and suggests new possible ways of nucleoplasmic lamin A/C regulation, function, and importance for the formation of functional nuclear microdomains.

• Klíčová slova
• NM1, PI(4,5)P2, cell nucleus, lamin A/C, nuclear lamina, nuclear myosin 1, nucleoplasm, phosphoinositides, phosphorylation,
• MeSH
• buněčné jádro * metabolismus   MeSH
• interfáze MeSH
• intermediární filamenta metabolismus   MeSH
• lamin typ A * metabolismus   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• lamin typ A * MeSH

At first glance the nucleus is a highly conserved organelle. Overall nuclear morphology, the octagonal nuclear pore complex, the presence of peripheral heterochromatin and the nuclear envelope appear near constant features right down to the ultrastructural level. New work is revealing significant compositional divergence within these nuclear structures and their associated functions, likely reflecting adaptations and distinct mechanisms between eukaryotic lineages and especially the trypanosomatids. While many examples of mechanistic divergence currently lack obvious functional interpretations, these studies underscore the malleability of nuclear architecture. I will discuss some recent findings highlighting these facets within trypanosomes, together with the underlying evolutionary framework and make a call for the exploration of nuclear function in non-canonical experimental organisms.

• Klíčová slova
• Eukaryogenesis, Lamina, Lamins, Molecular evolution, Nuclear architecture, Nuclear envelope, Nuclear pore complex, Trypanosomes,
• MeSH
• buněčné jádro metabolismus   MeSH
• jaderná lamina metabolismus   MeSH
• jaderný obal metabolismus   MeSH
• jaderný pór metabolismus   MeSH
• komplex proteinů jaderného póru * MeSH
• laminy metabolismus   MeSH
• molekulární evoluce MeSH
• Trypanosoma * metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• komplex proteinů jaderného póru * MeSH
• laminy MeSH

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.

• Klíčová slova
• adenovirus, baculovirus, circovirus, herpesvirus, lamin, nuclear actin, nuclear cytoskeleton, papillomavirus, parvovirus, polyomavirus,
• 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
• Názvy látek
• aktiny MeSH
• laminy 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.

• Klíčová slova
• Heterochromatin, Lamina, Macromolecular assembly, Nuclear organization, Trypanosomatid,
• MeSH
• buněčné jádro MeSH
• jaderná lamina * genetika   MeSH
• jaderný obal MeSH
• laminy genetika   MeSH
• telomery MeSH
• Trypanosoma * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• laminy MeSH

The essential components of splicing are the splicing factors accumulated in nuclear speckles; thus, we studied how DNA damaging agents and A-type lamin depletion affect the properties of these regions, positive on the SC-35 protein. We observed that inhibitor of PARP (poly (ADP-ribose) polymerase), and more pronouncedly inhibitors of RNA polymerases, caused DNA damage and increased the SC35 protein level. Interestingly, nuclear blebs, induced by PARP inhibitor and observed in A-type lamin-depleted or senescent cells, were positive on both the SC-35 protein and another component of the spliceosome, SRRM2. In the interphase cell nuclei, SC-35 interacted with the phosphorylated form of RNAP II, which was A-type lamin-dependent. In mitotic cells, especially in telophase, the SC35 protein formed a well-visible ring in the cytoplasmic fraction and colocalized with β-catenin, associated with the plasma membrane. The antibody against the SRRM2 protein showed that nuclear speckles are already established in the cytoplasm of the late telophase and at the stage of early cytokinesis. In addition, we observed the occurrence of splicing factors in the nuclear blebs and micronuclei, which are also sites of both transcription and splicing. This conclusion supports the fact that splicing proceeds transcriptionally. According to our data, this process is A-type lamin-dependent. Lamin depletion also reduces the interaction between SC35 and β-catenin in mitotic cells.

• Klíčová slova
• PARP inhibitor, RNA pol II, SC-35, splicing,
• MeSH
• HeLa buňky MeSH
• laminy metabolismus   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• PARP inhibitory terapeutické užití   MeSH
• poly-ADP-ribóza-polymeráza 1 MeSH
• RNA-polymerasa II metabolismus   MeSH
• sestřihové faktory metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• laminy MeSH
• PARP inhibitory MeSH
• PARP1 protein, human MeSH Prohlížeč
• poly-ADP-ribóza-polymeráza 1 MeSH
• RNA-polymerasa II MeSH
• sestřihové faktory MeSH

Chromatin architect of muscle expression (Charme) is a muscle-restricted long noncoding RNA (lncRNA) that plays an important role in myogenesis. Earlier evidence indicates that the nuclear Charme isoform, named pCharme, acts on the chromatin by assisting the formation of chromatin domains where myogenic transcription occurs. By combining RNA antisense purification (RAP) with mass spectrometry and loss-of-function analyses, we have now identified the proteins that assist these chromatin activities. These proteins-which include a sub-set of splicing regulators, principally PTBP1 and the multifunctional RNA/DNA binding protein MATR3-bind to sequences located within the alternatively spliced intron-1 to form nuclear aggregates. Consistent with the functional importance of pCharme interactome in vivo, a targeted deletion of the intron-1 by a CRISPR-Cas9 approach in mouse causes the release of pCharme from the chromatin and results in cardiac defects similar to what was observed upon knockout of the full-length transcript.

• Klíčová slova
• CRISPR Cas9, alternative splicing, chromatin, epigenetic control, introns, lncRNA, muscle, myogenesis, nuclear aggregates, ribonucleoparticle,
• MeSH
• heterogenní jaderné ribonukleoproteiny metabolismus   MeSH
• introny genetika   MeSH
• lidé MeSH
• myši MeSH
• protein vázající polypyrimidinové úseky RNA metabolismus   MeSH
• proteiny asociované s jadernou matrix metabolismus   MeSH
• proteiny vázající RNA metabolismus   MeSH
• RNA dlouhá nekódující metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• heterogenní jaderné ribonukleoproteiny MeSH
• MATR3 protein, human MeSH Prohlížeč
• protein vázající polypyrimidinové úseky RNA MeSH
• proteiny asociované s jadernou matrix MeSH
• proteiny vázající RNA MeSH
• PTBP1 protein, human MeSH Prohlížeč
• RNA dlouhá nekódující MeSH

Hutchinson-Gilford progeria syndrome (HGPS) is a premature aging disorder caused by a mutation of lamin A, which contributes to nuclear architecture and the spatial organization of chromatin in the nucleus. The expression of a lamin A mutant, named progerin, leads to functional and structural disruption of nuclear organization. Since progerin lacks a part of the actin-binding site of lamin A, we hypothesized that nuclear actin dynamics and function are altered in HGPS cells. Nuclear F-actin is required for the organization of nuclear shape, transcriptional regulation, DNA damage repair, and activation of Wnt/β-catenin signaling. Here we show that the expression of progerin decreases nuclear F-actin and impairs F-actin-regulated transcription. When nuclear F-actin levels are increased by overexpression of nuclear-targeted actin or by using jasplakinolide, a compound that stabilizes F-actin, the irregularity of nuclear shape and defects in gene expression can be reversed. These observations provide evidence for a novel relationship between nuclear actin and the etiology of HGPS.

• Klíčová slova
• Hutchinson-Gilford progeria syndrome, Nuclear actin, gene expression, lamin, nuclear organization, progerin,
• MeSH
• aktiny genetika   metabolismus   MeSH
• buněčné jádro genetika   metabolismus   patologie   MeSH
• buňky NIH 3T3 MeSH
• lamin typ A genetika   metabolismus   MeSH
• lidé MeSH
• myši MeSH
• oprava DNA * MeSH
• progerie genetika   metabolismus   patologie   MeSH
• signální dráha Wnt * MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• audiovizuální média MeSH
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Intramural MeSH
• Názvy látek
• aktiny MeSH
• lamin typ A MeSH
• LMNA protein, human MeSH Prohlížeč
• Lmna protein, mouse MeSH Prohlížeč

Most genes associated with neurodevelopmental disorders (NDDs) were identified with an excess of de novo mutations (DNMs) but the significance in case-control mutation burden analysis is unestablished. Here, we sequence 63 genes in 16,294 NDD cases and an additional 62 genes in 6,211 NDD cases. By combining these with published data, we assess a total of 125 genes in over 16,000 NDD cases and compare the mutation burden to nonpsychiatric controls from ExAC. We identify 48 genes (25 newly reported) showing significant burden of ultra-rare (MAF < 0.01%) gene-disruptive mutations (FDR 5%), six of which reach family-wise error rate (FWER) significance (p < 1.25E-06). Among these 125 targeted genes, we also reevaluate DNM excess in 17,426 NDD trios with 6,499 new autism trios. We identify 90 genes enriched for DNMs (FDR 5%; e.g., GABRG2 and UIMC1); of which, 61 reach FWER significance (p < 3.64E-07; e.g., CASZ1). In addition to doubling the number of patients for many NDD risk genes, we present phenotype-genotype correlations for seven risk genes (CTCF, HNRNPU, KCNQ3, ZBTB18, TCF12, SPEN, and LEO1) based on this large-scale targeted sequencing effort.

• MeSH
• CCCTC-vazebný faktor genetika   MeSH
• DNA vazebné proteiny genetika   MeSH
• draslíkový kanál KCNQ3 genetika   MeSH
• genetická predispozice k nemoci * MeSH
• genetické asociační studie MeSH
• heterogenní jaderný ribonukleoprotein U genetika   MeSH
• kohortové studie MeSH
• lidé MeSH
• mutace MeSH
• mutační analýza DNA MeSH
• neurovývojové poruchy genetika   MeSH
• proteiny vázající RNA genetika   MeSH
• represorové proteiny genetika   MeSH
• studie případů a kontrol MeSH
• transkripční faktory bHLH genetika   MeSH
• transkripční faktory genetika   MeSH
• vysoce účinné nukleotidové sekvenování MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• multicentrická studie MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• CCCTC-vazebný faktor MeSH
• CTCF protein, human MeSH Prohlížeč
• DNA vazebné proteiny MeSH
• draslíkový kanál KCNQ3 MeSH
• heterogenní jaderný ribonukleoprotein U MeSH
• HNRNPU protein, human MeSH Prohlížeč
• KCNQ3 protein, human MeSH Prohlížeč
• LEO1 protein, human MeSH Prohlížeč
• proteiny vázající RNA MeSH
• represorové proteiny MeSH
• SPEN protein, human MeSH Prohlížeč
• TCF12 protein, human MeSH Prohlížeč
• transkripční faktory bHLH MeSH
• transkripční faktory MeSH
• ZBTB18 protein, human MeSH Prohlížeč

The molecular architecture and assembly mechanism of intermediate filaments have been enigmatic for decades. Among those, lamin filaments are of particular interest due to their universal role in cell nucleus and numerous disease-related mutations. Filament assembly is driven by specific interactions of the elementary dimers, which consist of the central coiled-coil rod domain flanked by non-helical head and tail domains. We aimed to investigate the longitudinal 'head-to-tail' interaction of lamin dimers (the so-called ACN interaction), which is crucial for filament assembly. To this end, we prepared a series of recombinant fragments of human lamin A centred around the N- and C-termini of the rod. The fragments were stabilized by fusions to heterologous capping motifs which provide for a correct formation of parallel, in-register coiled-coil dimers. As a result, we established crystal structures of two N-terminal fragments one of which highlights the propensity of the coiled-coil to open up, and one C-terminal rod fragment. Additional studies highlighted the capacity of such N- and C-terminal fragments to form specific complexes in solution, which were further characterized using chemical cross-linking. These data yielded a molecular model of the ACN complex which features a 6.5 nm overlap of the rod ends.

• Klíčová slova
• X-ray crystallography, chemical cross-linking, intermediate filaments, mass spectrometry, nuclear lamins,
• MeSH
• hmotnostní spektrometrie MeSH
• krystalografie rentgenová MeSH
• lamin typ A chemie   MeSH
• lidé MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• lamin typ A MeSH

Background Hutchinson-Gilford progeria syndrome (HGPS) is a rare disease caused by pathogenic variants in the LMNA gene, which leads to premature aging. The median life expectancy is shortened to 13 years due to cardiovascular complications. Case report We present a boy born with a pathogenic LMNA variant c.433G > A, which causes atypical progeria syndrome (APS) and was previously described in one single patient. When investigated for poor growth prior to the diagnosis of APS, his laboratory tests revealed growth hormone (GH) deficiency and magnetic resonance imaging (MRI) of the midbrain showed partial empty sella. GH treatment had only a limited and transient effect. His first ischemic complication manifested at age 4.2 years; at the age of 7 years, he had a fatal haemorrhagic stroke. Conclusion To the best of our knowledge, this is the first patient with APS showing partial empty sella and GH deficiency that might have contributed to his poor growth. GH failed to improve long-term outcome.

• Klíčová slova
• LMNA, atypical progeria syndrome, growth hormone deficiency,
• MeSH
• fatální výsledek MeSH
• kojenec MeSH
• lamin typ A genetika   MeSH
• lidé MeSH
• lidský růstový hormon aplikace a dávkování   nedostatek   MeSH
• mutace * MeSH
• nanismus farmakoterapie   etiologie   MeSH
• předškolní dítě MeSH
• progerie komplikace   genetika   patologie   MeSH
• Check Tag
• kojenec MeSH
• lidé MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• Publikační typ
• kazuistiky MeSH
• Názvy látek
• lamin typ A MeSH
• lidský růstový hormon MeSH
• LMNA protein, human MeSH Prohlížeč