Histone-lysine N-methyltransferase SUV39H1 is an enzyme that in humans is encoded by the SUV39H1 gene. [5]
Histone-lysine N-methyltransferase SUV39H1 is an enzyme that in humans is encoded by the SUV39H1 gene. [5]
This gene is a member of the suppressor of variegation 3-9 homolog family and encodes a protein with a chromodomain and a C-terminal SET domain. This nuclear protein moves to the centromeres during mitosis and functions as a histone methyltransferase, methylating lysine-9 of histone H3. Overall, it plays a vital role in heterochromatin organization, chromosome segregation, and mitotic progression. [6] In mouse embryonic stem cells, Suv39h1 expression is repressed by OCT4 protein through the induction of an antisense long non-coding RNA. [7]
SUV39H1 has been shown to interact with:
In biology, histones are highly basic proteins abundant in lysine and arginine residues that are found in eukaryotic cell nuclei and in most Archaeal phyla. They act as spools around which DNA winds to create structural units called nucleosomes. Nucleosomes in turn are wrapped into 30-nanometer fibers that form tightly packed chromatin. Histones prevent DNA from becoming tangled and protect it from DNA damage. In addition, histones play important roles in gene regulation and DNA replication. Without histones, unwound DNA in chromosomes would be very long. For example, each human cell has about 1.8 meters of DNA if completely stretched out; however, when wound about histones, this length is reduced to about 90 micrometers (0.09 mm) of 30 nm diameter chromatin fibers.
Histone H3 is one of the five main histones involved in the structure of chromatin in eukaryotic cells. Featuring a main globular domain and a long N-terminal tail, H3 is involved with the structure of the nucleosomes of the 'beads on a string' structure. Histone proteins are highly post-translationally modified however Histone H3 is the most extensively modified of the five histones. The term "Histone H3" alone is purposely ambiguous in that it does not distinguish between sequence variants or modification state. Histone H3 is an important protein in the emerging field of epigenetics, where its sequence variants and variable modification states are thought to play a role in the dynamic and long term regulation of genes.
Methyl-CpG-binding domain protein 1 is a protein that in humans is encoded by the MBD1 gene. The protein encoded by MBD1 binds to methylated sequences in DNA, and thereby influences transcription. It binds to a variety of methylated sequences, and appears to mediate repression of gene expression. It has been shown to play a role in chromatin modification through interaction with the histone H3K9 methyltransferase SETDB1. H3K9me3 is a repressive modification.
The family of heterochromatin protein 1 (HP1) consists of highly conserved proteins, which have important functions in the cell nucleus. These functions include gene repression by heterochromatin formation, transcriptional activation, regulation of binding of cohesion complexes to centromeres, sequestration of genes to the nuclear periphery, transcriptional arrest, maintenance of heterochromatin integrity, gene repression at the single nucleosome level, gene repression by heterochromatization of euchromatin, and DNA repair. HP1 proteins are fundamental units of heterochromatin packaging that are enriched at the centromeres and telomeres of nearly all eukaryotic chromosomes with the notable exception of budding yeast, in which a yeast-specific silencing complex of SIR proteins serve a similar function. Members of the HP1 family are characterized by an N-terminal chromodomain and a C-terminal chromoshadow domain, separated by a hinge region. HP1 is also found at some euchromatic sites, where its binding can correlate with either gene repression or gene activation. HP1 was originally discovered by Tharappel C James and Sarah Elgin in 1986 as a factor in the phenomenon known as position effect variegation in Drosophila melanogaster.
RNA-induced transcriptional silencing (RITS) is a form of RNA interference by which short RNA molecules – such as small interfering RNA (siRNA) – trigger the downregulation of transcription of a particular gene or genomic region. This is usually accomplished by posttranslational modification of histone tails which target the genomic region for heterochromatin formation. The protein complex that binds to siRNAs and interacts with the methylated lysine 9 residue of histones H3 (H3K9me2) is the RITS complex.
Chromobox protein homolog 3 is a protein that is encoded by the CBX3 gene in humans.
Chromatin remodeling is the dynamic modification of chromatin architecture to allow access of condensed genomic DNA to the regulatory transcription machinery proteins, and thereby control gene expression. Such remodeling is principally carried out by 1) covalent histone modifications by specific enzymes, e.g., histone acetyltransferases (HATs), deacetylases, methyltransferases, and kinases, and 2) ATP-dependent chromatin remodeling complexes which either move, eject or restructure nucleosomes. Besides actively regulating gene expression, dynamic remodeling of chromatin imparts an epigenetic regulatory role in several key biological processes, egg cells DNA replication and repair; apoptosis; chromosome segregation as well as development and pluripotency. Aberrations in chromatin remodeling proteins are found to be associated with human diseases, including cancer. Targeting chromatin remodeling pathways is currently evolving as a major therapeutic strategy in the treatment of several cancers.
Histone deacetylase 3 is an enzyme encoded by the HDAC3 gene in both humans and mice.
Tripartite motif-containing 28 (TRIM28), also known as transcriptional intermediary factor 1β (TIF1β) and KAP1, is a protein that in humans is encoded by the TRIM28 gene.
DNA (cytosine-5)-methyltransferase 3A (DNMT3A) is an enzyme that catalyzes the transfer of methyl groups to specific CpG structures in DNA, a process called DNA methylation. The enzyme is encoded in humans by the DNMT3A gene.
Histone-binding protein RBBP7 is a protein that in humans is encoded by the RBBP7 gene.
Histone H3.2 is a protein that in humans is encoded by the HIST2H3C gene.
Chromatin assembly factor 1 subunit A is a protein that in humans is encoded by the CHAF1A gene.
Histone-lysine N-methyltransferase SETDB1 is an enzyme that in humans is encoded by the SETDB1 gene. SETDB1 is also known as KMT1E or H3K9 methyltransferase ESET.
Histone H3.1 is a protein in humans that is encoded by the H3C1 gene.
Histone H3.1 is a protein that in humans is encoded by the HIST1H3F gene.
Histone-lysine N-methyltransferase SETD7 is an enzyme that in humans is encoded by the SETD7 gene.
Chromobox protein homolog 5 is a protein that in humans is encoded by the CBX5 gene. It is a highly conserved, non-histone protein part of the heterochromatin family. The protein itself is more commonly called HP1α. Heterochromatin protein-1 (HP1) has an N-terminal domain that acts on methylated lysines residues leading to epigenetic repression. The C-terminal of this protein has a chromo shadow-domain (CSD) that is responsible for homodimerizing, as well as interacting with a variety of chromatin-associated, non-histone proteins.
Protein methylation is a type of post-translational modification featuring the addition of methyl groups to proteins. It can occur on the nitrogen-containing side-chains of arginine and lysine, but also at the amino- and carboxy-termini of a number of different proteins. In biology, methyltransferases catalyze the methylation process, activated primarily by S-adenosylmethionine. Protein methylation has been most studied in histones, where the transfer of methyl groups from S-adenosyl methionine is catalyzed by histone methyltransferases. Histones that are methylated on certain residues can act epigenetically to repress or activate gene expression.
Thomas Jenuwein is a German scientist working in the fields of epigenetics, chromatin biology, gene regulation and genome function.