Deacetylation and Methylation at Histone H3 Lysine 9 (H3K9) Coordinate Chromosome Condensation during Cell Cycle Progression

Abstract

Interphasic chromatin condenses into the chromosomes in order to facilitate the correct segregation of genetic information. It has been previously reported that the phosphorylation and methylation of the N-terminal tail of histone H3 are responsible for chromosome condensation. In this study, we demonstrate that the deacetylation and methylation of histone H3 lysine 9 (H3K9) are required for proper chromosome condensation. We confirmed that H3K9ac levels were reduced, whereas H3K9me3 levels were increased in mitotic cells, via immunofluorescence and Western blot analysis. Nocodazole treatment induced G2/M arrest but co-treatment with TSA, an HDAC inhibitor, delayed cell cycle progression. However, the HMTase inhibitor, AdoX, had no effect on nocodazole-induced G2/M arrest, thereby indicating that sequential modifications of H3K9 are required for proper chromosome condensation. The expression of SUV39H1 and SETDB1, H3K9me3-responsible HMTases, are specifically increased along with H3K9me3 in nocodazole-arrested buoyant cells, which suggests that the increased expression of those proteins is an important step in chromosome condensation. H3K9me3 was highly concentrated in the vertical chromosomal axis during prophase and prometaphase. Collectively, the results of this study indicate that sequential modifications at H3K9 are associated with correct chromosome condensation, and that H3K9me3 may be relevant to the condensation of chromosome length.

The multi zinc-finger protein Trps1 acts as a regulator of histone deacetylation during mitosis

“…As outlined above, histones have to be hypoacetylated during prometaphase to facilitate chromatin condensation 5 . We thus tested if histone H3 could be a physiological target of the Trps1-Hdac complex.…”

“…During recent years, many lines of evidence, mostly based on synthetic Hdac inhibitors and knockdown experiments, have demonstrated the importance of Hdac function in regulating mitosis 5 , 35 . Chromatin hyperacetylation interferes with its compaction, leading to the activation of the spindle attachment checkpoint and an arrest of mitosis in prometaphase 9 , 26 , 27 .…”

“…As cells enter mitosis, the chromatin needs to be condensed into structures of higher order. Several recent studies using either synthetic inhibitors or genetic inactivation of Hdacs demonstrated that DNA condensation requires histone deacetylases 4 , 5 . Consequently, cells with impaired Hdac function activate the mitotic checkpoint and stay arrested in prometaphase 6 , 7 .…”

The role of epigenetic regulation in stem cell and cancer biology

“…A well-characterized example of this is the H3K9 site, where acetylation and methylation regulates a switch between activation and repression of genes [97]. As these marks regulate opposing events, it is postulated that acetylation at this site prohibits methylation.…”

Comparative analyses of histone H3K9 trimethylations in the heart and spleen of normal humans

“…Among the various histone lysine methylation patterns, this study focused on H3K9 owing to its association with condensed and repressed chromatin (Park et al, 2011). H3K9me3 is a posttranslational modification that is commonly linked with both facultative and constitutive heterochromatin formation and transcriptional repression (Shinkai and Tachibana, 2011).…”