The incorporation of histone H3 with an acetylated lysine 56 (H3K56ac) into the nucleosome is important for chromatin remodeling and serves as a marker of new nucleosomes during DNA replication and repair in yeast. However, in human cells, the level of H3K56ac is greatly reduced, and its role during the cell cycle is controversial. Our aim was to determine the potential of H3K56ac to regulate cell cycle progression in different human cell lines. A significant increase in the number of H3K56ac foci, but not in H3K56ac protein levels, was observed during the S and G2 phases in cancer cell lines, but was not observed in embryonic stem cell lines. Despite this increase, the H3K56ac signal was not present in late replication chromatin, and H3K56ac protein levels did not decrease after the inhibition of DNA replication. H3K56ac was not tightly associated with the chromatin and was primarily localized to active chromatin regions. Our results support the role of H3K56ac in transcriptionally active chromatin areas but do not confirm H3K56ac as a marker of newly synthetized nucleosomes in DNA replication.

• MeSH
• Cell Cycle genetics   physiology   MeSH
• Chromatin metabolism   MeSH
• G2 Phase genetics   MeSH
• Histones metabolism   MeSH
• HL-60 Cells MeSH
• Mass Spectrometry MeSH
• Humans MeSH
• Nucleosomes metabolism   MeSH
• DNA Replication genetics   physiology   MeSH
• S Phase genetics   MeSH
• Saccharomyces cerevisiae Proteins genetics   metabolism   MeSH
• Saccharomyces cerevisiae genetics   metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Cajal bodies are important nuclear structures containing proteins that preferentially regulate RNA-related metabolism. We investigated the cell-type specific nuclear distribution of Cajal bodies and the level of coilin, a protein of Cajal bodies, in non-irradiated and irradiated human tumor cell lines and embryonic stem (ES) cells. Cajal bodies were localized in different nuclear compartments, including DAPI-poor regions, in the proximity of chromocenters, and adjacent to nucleoli. The number of Cajal bodies per nucleus was cell cycle-dependent, with higher numbers occurring during G2 phase. Human ES cells contained a high coilin level in the nucleoplasm, but coilin-positive Cajal bodies were also identified in nuclei of mouse and human ES cells. Coilin, but not SMN, recognized UVA-induced DNA lesions, which was cell cycle-independent. Treatment with γ-radiation reduced the localized movement of Cajal bodies in many cell types and GFP-coilin fluorescence recovery after photobleaching was very fast in nucleoplasm in comparison with GFP-coilin recovery in DNA lesions. By contrast, nucleolus-localized coilin displayed very slow fluorescence recovery after photobleaching, which indicates very slow rates of protein diffusion, especially in nucleoli of mouse ES cells.

• MeSH
• Cell Nucleus genetics   metabolism   radiation effects   MeSH
• Cell Line MeSH
• K562 Cells MeSH
• Coiled Bodies genetics   metabolism   radiation effects   MeSH
• DNA genetics   radiation effects   MeSH
• G2 Phase genetics   MeSH
• HeLa Cells MeSH
• Nuclear Proteins genetics   metabolism   MeSH
• Humans MeSH
• Mice MeSH
• Cell Line, Tumor MeSH
• Recombinant Fusion Proteins genetics   metabolism   MeSH
• Ultraviolet Rays adverse effects   MeSH
• Gamma Rays adverse effects   MeSH
• Green Fluorescent Proteins genetics   metabolism   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH