DNA damage response (DDR) in ribosomal genes and mechanisms of DNA repair in embryonic stem cells (ESCs) are less explored nuclear events. DDR in ESCs should be unique due to their high proliferation rate, expression of pluripotency factors, and specific chromatin signature. Given short population doubling time and fast progress through G1 phase, ESCs require a sustained production of rRNA, which leads to the formation of large and prominent nucleoli. Although transcription of rRNA in the nucleolus is relatively well understood, little is known about DDR in this nuclear compartment. Here, we directed formation of double-strand breaks in rRNA genes with I- PpoI endonuclease, and we studied nucleolar morphology, DDR, and chromatin modifications. We observed a pronounced formation of I- PpoI-induced nucleolar caps, positive on BRCA1, NBS1, MDC1, γH2AX, and UBF1 proteins. We showed interaction of nucleolar protein TCOF1 with HDAC1 and TCOF1 with CARM1 after DNA injury. Moreover, H3R17me2a modification mediated by CARM1 was found in I- PpoI-induced nucleolar caps. Finally, we report that heterochromatin protein 1 is not involved in DNA repair of nucleolar caps.

• Keywords
• CARM1, DNA repair, HDAC1, NBS1, PpoI, chromatin, nucleolus,
• MeSH
• Acetylation MeSH
• Arginine metabolism   MeSH
• Cell Nucleolus genetics   ultrastructure   MeSH
• Cell Line MeSH
• DNA Breaks, Double-Stranded * MeSH
• Embryonic Stem Cells metabolism   ultrastructure   MeSH
• Phosphoproteins metabolism   MeSH
• Genes, rRNA MeSH
• Histone Deacetylase 1 metabolism   MeSH
• Histones metabolism   MeSH
• Intracellular Signaling Peptides and Proteins MeSH
• Nuclear Proteins metabolism   MeSH
• Methylation MeSH
• Mice MeSH
• DNA Repair MeSH
• Protein-Arginine N-Methyltransferases metabolism   MeSH
• RNA, Ribosomal genetics   metabolism   MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Arginine MeSH
• coactivator-associated arginine methyltransferase 1 MeSH Browser
• Phosphoproteins MeSH
• Hdac1 protein, mouse MeSH Browser
• Histone Deacetylase 1 MeSH
• Histones MeSH
• Intracellular Signaling Peptides and Proteins MeSH
• Nuclear Proteins MeSH
• Protein-Arginine N-Methyltransferases MeSH
• RNA, Ribosomal MeSH
• Tcof1 protein, mouse MeSH Browser