H3R8me2
From Wikipedia, the free encyclopedia
H3R8me2 is an epigenetic modification to the DNA packaging protein histone H3. It is a mark that indicates the di-methylation at the 8th arginine residue of the histone H3 protein. In epigenetics, arginine methylation of histones H3 and H4 is associated with a more accessible chromatin structure and thus higher levels of transcription. The existence of arginine demethylases that could reverse arginine methylation is controversial.[1]
H3R8me2 is associated with transcriptional repression, and modified by PRMT5, but not CARM1.
As of March 2021, there are no disease associations known for H3R8me2.[2]
The name of this modification indicates dimethylation of arginine 8 on histone H3 protein subunit: [3]
| Abbr. | Meaning |
| H3 | H3 family of histones |
| R | standard abbreviation for arginine |
| 8 | position of amino acid residue
(counting from N-terminus) |
| me | methyl group |
| 2 | number of methyl groups added |
Arginine
Arginine can be methylated once (monomethylated arginine) or twice (dimethylated arginine). Methylation of arginine residues is catalyzed by three different classes of protein arginine methyltransferases.[1]
Arginine methylation affects the interactions between proteins and has been implicated in a variety of cellular processes, including protein trafficking, signal transduction, and transcriptional regulation.[4]
Arginine methylation plays a major role in gene regulation because of the ability of the PRMTs to deposit key activating (histone H4R3me2, H3R2me2, H3R17me2, H3R26me2) or repressive (H3R2me2, H3R8me2, H4R3me2) histone marks.
Histone modifications
Mechanism and function of modification
Epigenetic implications
The post-translational modification of histone tails by either histone-modifying complexes or chromatin remodeling complexes is interpreted by the cell and leads to complex, combinatorial transcriptional output. It is thought that a histone code dictates the expression of genes by a complex interaction between the histones in a particular region.[6] The current understanding and interpretation of histones comes from two large scale projects: ENCODE and the Epigenomic roadmap.[7] The purpose of the epigenomic study was to investigate epigenetic changes across the entire genome. This led to chromatin states, which define genomic regions by grouping different proteins and/or histone modifications together. Chromatin states were investigated in Drosophila cells by looking at the binding location of proteins in the genome. Use of ChIP-sequencing revealed regions in the genome characterized by different banding.[8] Different developmental stages were profiled in Drosophila as well, an emphasis was placed on histone modification relevance.[9] A look in to the data obtained led to the definition of chromatin states based on histone modifications.[10] Certain modifications were mapped and enrichment was seen to localize in certain genomic regions.
The human genome is annotated with chromatin states. These annotated states can be used as new ways to annotate a genome independently of the underlying genome sequence. This independence from the DNA sequence enforces the epigenetic nature of histone modifications. Chromatin states are also useful in identifying regulatory elements that have no defined sequence, such as enhancers. This additional level of annotation allows for a deeper understanding of cell specific gene regulation.[11]
Clinical significance
PRMT2 was shown to mediate the dorsal developmental program through methylation of H3R8me2a.[12]