INTRODUCTION: Neurodegenerative diseases of childhood present with progressive decline in cognitive, social, and motor function and are frequently associated with seizures in different stages of the disease. Here we report a patient with severe progressive neurodegeneration with drug-resistant epilepsy of unknown etiology from the age of 2 years. METHODS AND RESULTS: Using whole exome sequencing, we found heterozygous missense de novo variant c.628G > A (p.Glu210Lys) in the UBTF gene. This variant was recently described as de novo in 11 patients with similar neurodegeneration characterized by developmental decline initially confined to motor development followed by language regression, appearance of an extrapyramidal movement disorder, and leading to severe intellectual disability. In 3 of the 11 patients described so far, seizures were also present. CONCLUSIONS: Our report expands the complex phenotype of neurodegeneration associated with the c.628G > A variant in the UBTF gene and helps to clarify the relation between this one single recurrent pathogenic variant described in this gene to date and its phenotype. The UBTF gene should be considered a novel candidate gene in neurodegeneration with or without epilepsy.
- MeSH
- fenotyp * MeSH
- lidé MeSH
- mladiství MeSH
- mutace genetika MeSH
- neurodegenerativní nemoci komplikace diagnostické zobrazování genetika MeSH
- refrakterní epilepsie komplikace diagnostické zobrazování genetika MeSH
- transkripční iniciační komplex Pol1 - proteiny genetika MeSH
- Check Tag
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- kazuistiky MeSH
The nucleolus is a well-organized site of ribosomal gene transcription. Moreover, many DNA repair pathway proteins, including ATM, ATR kinases, MRE11, PARP1 and Ku70/80, localize to the nucleolus (Moore et al., 2011 ). We analyzed the consequences of DNA damage in nucleoli following ultraviolet A (UVA), C (UVC), or γ-irradiation in order to test whether and how radiation-mediated genome injury affects local motion and morphology of nucleoli. Because exposure to radiation sources can induce changes in the pattern of UBF1-positive nucleolar regions, we visualized nucleoli in living cells by GFP-UBF1 expression for subsequent morphological analyses and local motion studies. UVA radiation, but not 5 Gy of γ-rays, induced apoptosis as analyzed by an advanced computational method. In non-apoptotic cells, we observed that γ-radiation caused nucleolar re-positioning over time and changed several morphological parameters, including the size of the nucleolus and the area of individual UBF1-positive foci. Radiation-induced nucleoli re-arrangement was observed particularly in G2 phase of the cell cycle, indicating repair of ribosomal genes in G2 phase and implying that nucleoli are less stable, thus sensitive to radiation, in G2 phase.
- MeSH
- apoptóza účinky záření MeSH
- buněčné jadérko účinky záření MeSH
- buněčné linie MeSH
- buněčný cyklus účinky záření MeSH
- G2 fáze účinky záření MeSH
- genetická transkripce MeSH
- myši MeSH
- nádorové buněčné linie MeSH
- poškození DNA účinky záření MeSH
- transkripční iniciační komplex Pol1 - proteiny genetika metabolismus MeSH
- ultrafialové záření MeSH
- výpočetní biologie MeSH
- záření gama škodlivé účinky MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
RNA polymerase I (Pol I) transcription is essential for the cell cycle, growth and protein synthesis in eukaryotes. In the present study, we found that phosphatidylinositol 4,5-bisphosphate (PIP2) is a part of the protein complex on the active ribosomal promoter during transcription. PIP2 makes a complex with Pol I and the Pol I transcription factor UBF in the nucleolus. PIP2 depletion reduces Pol I transcription, which can be rescued by the addition of exogenous PIP2. In addition, PIP2 also binds directly to the pre-rRNA processing factor fibrillarin (Fib), and co-localizes with nascent transcripts in the nucleolus. PIP2 binding to UBF and Fib modulates their binding to DNA and RNA, respectively. In conclusion, PIP2 interacts with a subset of Pol I transcription machinery, and promotes Pol I transcription.
- MeSH
- buněčné jadérko genetika metabolismus MeSH
- chromozomální proteiny, nehistonové genetika metabolismus MeSH
- DNA vazebné proteiny genetika metabolismus MeSH
- fosfatidylinositol-4,5-difosfát genetika metabolismus MeSH
- genetická transkripce genetika MeSH
- HeLa buňky MeSH
- lidé MeSH
- nádorové buněčné linie MeSH
- prekurzory RNA genetika metabolismus MeSH
- promotorové oblasti (genetika) genetika MeSH
- RNA-polymerasa I genetika metabolismus MeSH
- transkripční iniciační komplex Pol1 - proteiny genetika metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
In mammalian cells, transcriptionally active ribosomal genes are replicated in the early S phase, and the silent ribosomal genes in the late S phase, though mechanisms of this timing remain unknown. UBF (Upstream Binding Factor), a DNA binding protein and component of the pol I transcription machinery, is considered to be responsible for the loose chromatin structure of the active rDNA. Here we question whether such structure alone can ensure early replication of DNA. We investigate this problem on the model of pseudo-NORs, the tandem arrays of heterologous DNA sequence with high affinity for UBF, introduced into human chromosomes. Such arrays are not transcribed, yet efficiently bind UBF and mimic the chromatin structure of active rDNA. In our study, a human derived stable cell line containing one pseudo-NOR on the chromosome 10 was transiently transfected with UBF-GFP and PCNA-RFP, which allowed us to observe in vivo the growth of pseudo-NORs resulted from their replication. We found that replication of pseudo-NORs is not restricted to the early S phase, but continues in the late S phase at a significant level. These results were confirmed in the experiments with incorporation of thymidin analog EdU and BrdU ChIP assay. Similar results were obtained with another cell line containing pseudo-NOR on the chromosome 7. Our data indicate that the specific loose structure of chromatin, produced by the architect protein UBF, is not sufficient for the early replication.
- MeSH
- imunohistochemie MeSH
- lidé MeSH
- nádorové buněčné linie MeSH
- organizátor jadérka genetika metabolismus MeSH
- proliferační antigen buněčného jádra genetika metabolismus MeSH
- ribozomální DNA genetika metabolismus MeSH
- S fáze genetika fyziologie MeSH
- transkripční iniciační komplex Pol1 - proteiny genetika metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Ribosomal genes are organized in clusters termed Nucleolus Organizer Regions (NORs). Essential components of the RNA polymerase I transcription machinery, including Upstream Binding Factor (UBF), can be detected on some NORs during mitosis; these NORs, termed competent, are believed to be transcriptionally active during interphase. In cultured mammalian cycling cells, the number of competent NORs, and their distribution among the different chromosomes, does not vary significantly in the sequential cell cycles. In this work we investigate whether this stable state is achieved by equal distribution of competent NORs during cell division. To answer this question we first studied the state of NORs in telophase HeLa and LEP cells. In both cell lines we found a small but significant difference between the emerging daughter cells in the number of UBF-loaded NORs. To reveal the cause of this difference, we followed the fate of individual NOR using HeLa derived cell line stably expressing UBF-GFP. We demonstrated that some NORs in metaphase are "asymmetrical", i.e. they lack the signal of competence on one of the sister chromatids. Regular presence of such NORs can account for the difference in the number of competent NORs obtained by the daughter cells emerging in mitosis.
