The family of heterochromatin protein 1 (HP1) isoforms is essential for chromatin packaging, regulation of gene expression, and repair of damaged DNA. Here we document that γ-radiation reduced the number of HP1α-positive foci, but not HP1β and HP1γ foci, located in the vicinity of the fibrillarin-positive region of the nucleolus. The additional analysis confirmed that γ-radiation has the ability to significantly decrease the level of HP1α in rDNA promoter and rDNA encoding 28S rRNA. By mass spectrometry, we showed that treatment by γ-rays enhanced the HP1β serine 88 phosphorylation (S88ph), but other analyzed modifications of HP1β, including S161ph/Y163ph, S171ph, and S174ph, were not changed in cells exposed to γ-rays or treated by the HDAC inhibitor (HDACi). Interestingly, a combination of HDACi and γ-radiation increased the level of HP1α and HP1γ. The level of HP1β remained identical before and after the HDACi/γ-rays treatment, but HDACi strengthened HP1β interaction with the KRAB-associated protein 1 (KAP1) protein. Conversely, HP1γ did not interact with KAP1, although approximately 40% of HP1γ foci co-localized with accumulated KAP1. Especially HP1γ foci at the periphery of nucleoli were mostly absent of KAP1. Together, DNA damage changed the morphology, levels, and interaction properties of HP1 isoforms. Also, γ-irradiation-induced hyperphosphorylation of the HP1β protein; thus, HP1β-S88ph could be considered as an important marker of DNA damage.

• Klíčová slova
• FLIM-FRET, HP1, epigenetics, irradiation, mass spectrometry, nucleolus, phosphorylation,
• MeSH
• buněčné jadérko metabolismus   MeSH
• chromozomální proteiny, nehistonové metabolismus   MeSH
• fosforylace MeSH
• HeLa buňky MeSH
• homolog proteinu s chromoboxem 5 MeSH
• lidé MeSH
• nádorové buňky kultivované MeSH
• optické zobrazování MeSH
• poškození DNA MeSH
• rezonanční přenos fluorescenční energie MeSH
• serin metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• CBX1 protein, human MeSH Prohlížeč
• CBX5 protein, human MeSH Prohlížeč
• chromozomální proteiny, nehistonové MeSH
• homolog proteinu s chromoboxem 5 MeSH
• serin MeSH

Repair of ribosomal DNA (rDNA) is a very important nuclear process due to the most active transcription of ribosomal genes. Proper repair of rDNA is required for physiological biogenesis of ribosomes. Here, we analyzed the epigenetics of the DNA damage response in a nucleolar compartment, thus in the ribosomal genes studied in nonirradiated and UVA-irradiated mouse embryonic fibroblasts (MEFs). We found that the promoter of ribosomal genes is not abundant on H4K20me2, but it is densely occupied by H4K20me3. Ribosomal genes, regulated via UBF1/2 proteins, were characterized by an interaction between UBF1/2 and H4K20me2/me3. This interaction was strengthened by UVA irradiation that additionally causes a focal accumulation of H4K20me3 in the nucleolus. No interaction has been found between UBF1/2 and H3K9me3. Interestingly, UVA irradiation decreases the levels of H3K9me3 and H4K20me3 at 28S rDNA. Altogether, the UVA light affects the epigenetic status of ribosomal genes at 28S rDNA and strengthens an interaction between UBF1/2 proteins and H4K20me2/me3.

• Klíčová slova
• DNA damage response, DNA repair, Nucleolus, UBF, UVA irradiation,
• MeSH
• buněčné jadérko metabolismus   MeSH
• buněčné jádro metabolismus   MeSH
• chromatinová imunoprecipitace MeSH
• DNA vazebné proteiny MeSH
• epigeneze genetická účinky záření   MeSH
• fluorescenční protilátková technika MeSH
• histony metabolismus   MeSH
• metylace MeSH
• myši MeSH
• promotorové oblasti (genetika) MeSH
• regulace genové exprese účinky záření   MeSH
• ribozomální DNA genetika   MeSH
• transkripční iniciační komplex Pol1 - proteiny metabolismus   MeSH
• ultrafialové záření * MeSH
• vazba proteinů MeSH
• vysoce účinné nukleotidové sekvenování MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA vazebné proteiny MeSH
• histony MeSH
• ribozomální DNA MeSH
• transcription factor UBF MeSH Prohlížeč
• transkripční iniciační komplex Pol1 - proteiny MeSH

Although histone acetylation is one of the most widely studied epigenetic modifications, there is still a lack of information regarding how the acetylome is regulated during brain development and pathophysiological processes. We demonstrate that the embryonic brain (E15) is characterized by an increase in H3K9 acetylation as well as decreases in the levels of HDAC1 and HDAC3. Moreover, experimental induction of H3K9 hyperacetylation led to the overexpression of NCAM in the embryonic cortex and depletion of Sox2 in the subventricular ependyma, which mimicked the differentiation processes. Inducing differentiation in HDAC1-deficient mouse ESCs resulted in early H3K9 deacetylation, Sox2 downregulation, and enhanced astrogliogenesis, whereas neuro-differentiation was almost suppressed. Neuro-differentiation of (wt) ESCs was characterized by H3K9 hyperacetylation that was associated with HDAC1 and HDAC3 depletion. Conversely, the hippocampi of schizophrenia-like animals showed H3K9 deacetylation that was regulated by an increase in both HDAC1 and HDAC3. The hippocampi of schizophrenia-like brains that were treated with the cannabinoid receptor-1 inverse antagonist AM251 expressed H3K9ac at the level observed in normal brains. Together, the results indicate that co-regulation of H3K9ac by HDAC1 and HDAC3 is important to both embryonic brain development and neuro-differentiation as well as the pathophysiology of a schizophrenia-like phenotype.

• Klíčová slova
• H3K9 acetylation, HDACs, acetylome, mouse neurogenesis, schizophrenia,
• MeSH
• acetylace MeSH
• antagonisté kanabinoidních receptorů farmakologie   MeSH
• antipsychotika farmakologie   MeSH
• časové faktory MeSH
• epigeneze genetická MeSH
• gestační stáří MeSH
• histondeacetylasa 1 antagonisté a inhibitory   genetika   metabolismus   MeSH
• histondeacetylasy genetika   metabolismus   MeSH
• histony metabolismus   MeSH
• inhibitory histondeacetylas farmakologie   MeSH
• methylazoxymethanolacetát MeSH
• modely nemocí na zvířatech MeSH
• molekuly buněčné adheze nervové genetika   metabolismus   MeSH
• mozek účinky léků   embryologie   enzymologie   patologie   MeSH
• myši inbrední C57BL MeSH
• neurogeneze * účinky léků   MeSH
• neurony účinky léků   enzymologie   patologie   MeSH
• posttranslační úpravy proteinů MeSH
• potkani Sprague-Dawley MeSH
• receptor kanabinoidní CB1 antagonisté a inhibitory   metabolismus   MeSH
• schizofrenie chemicky indukované   farmakoterapie   enzymologie   genetika   MeSH
• signální transdukce MeSH
• transkripční faktory SOXB1 genetika   metabolismus   MeSH
• vývojová regulace genové exprese MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antagonisté kanabinoidních receptorů MeSH
• antipsychotika MeSH
• Cnr1 protein, rat MeSH Prohlížeč
• Hdac1 protein, mouse MeSH Prohlížeč
• Hdac1 protein, rat MeSH Prohlížeč
• histondeacetylasa 1 MeSH
• histondeacetylasy MeSH
• histone deacetylase 3 MeSH Prohlížeč
• histony MeSH
• inhibitory histondeacetylas MeSH
• methylazoxymethanolacetát MeSH
• molekuly buněčné adheze nervové MeSH
• receptor kanabinoidní CB1 MeSH
• Sox2 protein, mouse MeSH Prohlížeč
• transkripční faktory SOXB1 MeSH

Protein arginine methyltransferases (PRMTs) are responsible for symmetric and asymmetric methylation of arginine residues of nuclear and cytoplasmic proteins. In the nucleus, PRMTs belong to important chromatin modifying enzymes of immense functional significance that affect gene expression, splicing and DNA repair. By time-lapse microscopy we have studied the sub-cellular localization and kinetics of PRMT1 after inhibition of PRMT1 and after irradiation. Both transiently expressed and endogenous PRMT1 accumulated in cytoplasmic bodies that were located in the proximity of the cell nucleus. The shape and number of these bodies were stable in untreated cells. However, when cell nuclei were microirradiated by UV-A, the mobility of PRMT1 cytoplasmic bodies increased, size was reduced, and disappeared within approximately 20 min. The same response occurred after γ-irradiation of the whole cell population, but with delayed kinetics. Treatment with PRMT1 inhibitors induced disintegration of these PRMT1 cytoplasmic bodies and prevented formation of 53BP1 nuclear bodies (NBs) that play a role during DNA damage repair. The formation of 53BP1 NBs was not influenced by PRMT1 overexpression. Taken together, we show that PRMT1 concentrates in cytoplasmic bodies, which respond to DNA injury in the cell nucleus, and to treatment with various PRMT1 inhibitors.

• MeSH
• 53BP1 MeSH
• chromozomální proteiny, nehistonové genetika   metabolismus   MeSH
• cytoplazma enzymologie   MeSH
• DNA vazebné proteiny genetika   metabolismus   MeSH
• HeLa buňky MeSH
• intracelulární signální peptidy a proteiny genetika   metabolismus   MeSH
• lidé MeSH
• myši MeSH
• poškození DNA * MeSH
• proteinarginin-N-methyltransferasy antagonisté a inhibitory   genetika   metabolismus   MeSH
• represorové proteiny antagonisté a inhibitory   genetika   metabolismus   MeSH
• ultrafialové záření * MeSH
• záření gama * MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 53BP1 MeSH
• chromozomální proteiny, nehistonové MeSH
• DNA vazebné proteiny MeSH
• intracelulární signální peptidy a proteiny MeSH
• PRMT1 protein, human MeSH Prohlížeč
• Prmt1 protein, mouse MeSH Prohlížeč
• proteinarginin-N-methyltransferasy MeSH
• represorové proteiny MeSH
• TP53BP1 protein, human MeSH Prohlížeč
• Trp53bp1 protein, mouse MeSH Prohlížeč

Heterochromatin protein 1 (HP1), which binds to sites of histone H3 lysine 9 (H3K9) methylation, is primarily responsible for gene silencing and the formation of heterochromatin. We observed that HP1 beta is located in both the chromocenters and fibrillarin-positive nucleoli interiors. However, HP1 alpha and HP1 gamma occupied fibrillarin-positive compartments to a lesser extent, corresponding to the distinct levels of HP1 subtypes at the promoter of rDNA genes. Deficiency of histone methyltransferases SUV39h and/or inhibition of histone deacetylases (HDACi) decreased HP1 beta and H3K9 trimethylation at chromocenters, but not in fibrillarin-positive regions that co-localized with RNA polymerase I. Similarly, SUV39h- and HDACi-dependent nucleolar rearrangement and inhibition of rDNA transcription did not affect the association between HP1 beta and fibrillarin. Moreover, the presence of HP1 beta in nucleoli is likely connected with transcription of ribosomal genes and with the role of fibrillarin in nucleolar processes.

• MeSH
• buněčné jadérko metabolismus   MeSH
• chromozomální proteiny, nehistonové metabolismus   MeSH
• fibroblasty metabolismus   MeSH
• kultivované buňky MeSH
• methyltransferasy metabolismus   MeSH
• myši MeSH
• represorové proteiny metabolismus   MeSH
• vazba proteinů MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• Cbx1 protein, mouse MeSH Prohlížeč
• chromozomální proteiny, nehistonové MeSH
• fibrillarin MeSH Prohlížeč
• methyltransferasy MeSH
• represorové proteiny MeSH
• Suv39h1 protein, mouse MeSH Prohlížeč

The nucleolus is a nuclear compartment that plays an important role in ribosome biogenesis. Some structural features and epigenetic patterns are shared between nucleolar and non-nucleolar compartments. For example, the location of transcriptionally active mRNA on extended chromatin loop species is similar to that observed for transcriptionally active ribosomal DNA (rDNA) genes on so-called Christmas tree branches. Similarly, nucleolus organizer region-bearing chromosomes located a distance from the nucleolus extend chromatin fibers into the nucleolar compartment. Specific epigenetic events, such as histone acetylation and methylation and DNA methylation, also regulate transcription of both rRNA- and mRNA-encoding loci. Here, we review the epigenetic mechanisms and structural features that regulate transcription of ribosomal and mRNA genes. We focus on similarities in epigenetic and structural regulation of chromatin in nucleoli and the surrounding non-nucleolar region and discuss the role of proteins, such as heterochromatin protein 1, fibrillarin, nucleolin, and upstream binding factor, in rRNA synthesis and processing.

• MeSH
• buněčné jadérko genetika   metabolismus   ultrastruktura   MeSH
• chromatin genetika   ultrastruktura   MeSH
• epigeneze genetická * MeSH
• genetická transkripce MeSH
• geny rRNA MeSH
• histony metabolismus   MeSH
• lidé MeSH
• messenger RNA genetika   MeSH
• ribozomální DNA genetika   MeSH
• ribozomy genetika   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• srovnávací studie MeSH
• Názvy látek
• chromatin MeSH
• histony MeSH
• messenger RNA MeSH
• ribozomální DNA MeSH