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
Methylation of histones H4 at lysine 20 position (H4K20me), which is functional in DNA repair, represents a binding site for the 53BP1 protein. Here, we show a radiation-induced increase in the level of H4K20me3 while the levels of H4K20me1 and H4K20me2 remained intact. H4K20me3 was significantly pronounced at DNA lesions in only the G1 phase of the cycle, while this histone mark was reduced in very late S and G2 phases when PCNA was recruited to locally micro-irradiated chromatin. H4K20me3 was diminished in locally irradiated Suv39h1/h2 double knockout (dn) fibroblasts, and the same phenomenon was observed for H3K9me3 and its binding partner, the HP1β protein. Immunoprecipitation showed the existence of an interaction between H3K9me3-53BP1 and H4K20me3-53BP1; however, HP1β did not interact with 53BP1. Together, H3K9me3 and H4K20me3 represent epigenetic markers that are important for the function of the 53BP1 protein in non-homologous end joining (NHEJ) repair. The very late S phase represents the cell cycle breakpoint when a DDR function of the H4K20me3-53BP1 complex is abrogated due to recruitment of the PCNA protein and other DNA repair factors of homologous recombination to DNA lesions.
- Klíčová slova
- DNA damage, H3K9me3, H4K20me1/me2/me3, Suv39h1/h2, epigenetics,
- MeSH
- 53BP1 genetika metabolismus MeSH
- buněčné jádro genetika metabolismus účinky záření MeSH
- buněčné linie MeSH
- buněčný cyklus MeSH
- chromozomální proteiny, nehistonové metabolismus MeSH
- epigeneze genetická * účinky záření MeSH
- histony metabolismus MeSH
- homolog proteinu s chromoboxem 5 MeSH
- lidé MeSH
- metylace DNA * účinky záření MeSH
- metylace MeSH
- myši MeSH
- oprava DNA spojením konců * MeSH
- poškození DNA * MeSH
- proliferační antigen buněčného jádra metabolismus MeSH
- restrukturace chromatinu MeSH
- vazba proteinů MeSH
- vazebná místa MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- 53BP1 MeSH
- CBX1 protein, human MeSH Prohlížeč
- Cbx1 protein, mouse MeSH Prohlížeč
- chromozomální proteiny, nehistonové MeSH
- histony MeSH
- homolog proteinu s chromoboxem 5 MeSH
- PCNA protein, human MeSH Prohlížeč
- proliferační antigen buněčného jádra MeSH
- TP53BP1 protein, human MeSH Prohlížeč
- Trp53bp1 protein, mouse MeSH Prohlížeč
