Chromosomal histone modification patterns – from conservation to diversity

Impact of nucleosome dynamics and histone modifications on cell proliferation during Arabidopsis development

“…However, future studies should aim at characterizing functionally the Arabidopsis homologs of chromatin-modifying enzymes, with particular emphasis in the target genes affected and the developmental stages involved. Furthermore, the consequences of certain histone modifications are opposite in animals and plants, suggesting that different mechanisms have evolved to read epigenetic modifications (Fuchs et al, 2006;Sanchez and Gutierrez, 2009a, b). Therefore, the identification and functional study of effector proteins is of primary relevance to advance our understanding of epigenetic changes occurring in different chromatin domains and of the plant histone code.…”

“…In mammalian cells, H3K9me3 is a silencing mark when found in the promoter, but is activating when is located within the transcribed regions (Berger, 2007). On the contrary, in Arabidopsis H3K9me3 is found in Arabidopsis euchromatin (Fuchs et al, 2006) and active promoters , whereas H3K9me2 is associated with repressed promoters Ramirez-Parra and Gutierrez, 2007a). Genomic analysis has extended these observations and confirmed that the H3K9me3 distribution colocalizes with euchromatin, with a slight bias towards the promoter regions (Turck et al, 2007), whereas H3K9me2 is highly enriched in transposons, pseudogenes and repressed genes.…”

“…In Arabidopsis, H3K18ac and H4K16ac increase during S-phase, although the HATs involved have not been identified. Different modifications occur in other plant species (Fuchs et al, 2006;Sanchez et al, 2008) indicating that, although increase acetylation is a common feature, the nature of these modifications is plant species-specific.…”

“…Histone modifications can alter chromatin conformation to the so-called 'open' or 'closed' states that facilitate or preclude the recruitment of factors required for various processes. Although there are common aspects of the histone code in all organisms, recent evidence show exceptions, as discussed below, which in the case of Arabidopsis contribute to define key differences between the plant and the animal histone code (Fuchs et al, 2006;Sanchez and Gutierrez, 2009b). In any case, we are still very far from fully understanding the histone code and its output in terms of transcriptional control.…”

Epigenetic Mechanisms in Inflammation

“…The covalent modification of histones is an essential epigenetic mechanism of gene regulation. These post-translational modifications (methylation of lysines and arginines, acetylation, phosphorylation, ubiquitination, SUMOylation, and ADP-ribosylation) occur most frequently at the N-terminal tails of the core histones (Fuchs et al, 2006). Acetylation of histones is associated with an "open" chromatin conformation that facilitates transcription (Campos and Reinberg, 2009;Cheng and Blumenthal, 2010).…”