Biomedical subjects

Tony Kouzarides

Publications and source records attributed to Tony Kouzarides.

44 records · Page 3Linked to original sources

PubMed2002

Structure of the HP1 chromodomain bound to histone H3 methylated at lysine 9.

Specific modifications to histones are essential epigenetic markers---heritable changes in gene expression that do not affect the DNA sequence. Methylation of lysine 9 in histone H3 is recognized by heterochromatin protein 1 (HP1), which directs the binding of other proteins to control chromatin structure and gene expression. Here we show that HP1 uses an induced-fit mechanism for recognition of this modification, as revealed by the structure of its chromodomain bound to a histone H3 peptide dimethylated at Nzeta of lysine 9. The binding pocket for the N-methyl groups is provided by three aromatic side chains, Tyr21, Trp42 and Phe45, which reside in two regions that become ordered on binding of the peptide. The side chain of Lys9 is almost fully extended and surrounded by residues that are conserved in many other chromodomains. The QTAR peptide sequence preceding Lys9 makes most of the additional interactions with the chromodomain, with HP1 residues Val23, Leu40, Trp42, Leu58 and Cys60 appearing to be a major determinant of specificity by binding the key buried Ala7. These findings predict which other chromodomains will bind methylated proteins and suggest a motif that they recognize.

Amino Acid Sequence↗

PubMed2002

Histone H3 lysine 4 methylation disrupts binding of nucleosome remodeling and deacetylase (NuRD) repressor complex.

Histone N-terminal tails are post-translationally modified in many ways. At lysine residues, histones can be either acetylated or methylated. Both modifications lead to the binding of specific proteins; bromodomain proteins, such as GCN5, bind acetyl lysines and the chromodomain protein, HP1, binds methyl lysine 9 of histone H3. Here we show that the previously characterized transcriptional repressor complex NuRD (nucleosome remodeling and deacetylase) binds to the histone H3 N-terminal tail and that methylation at lysine 4, but not lysine 9, prevents binding. Given that lysine 4 methylation is found at sites of active transcription, these results suggest that a function of lysine 4 methylation is to disrupt the association of histones with a repressor complex.

Acetylation↗

PubMed2002

Methyltransferase recruitment and DNA hypermethylation of target promoters by an oncogenic transcription factor.

DNA methylation of tumor suppressor genes is a frequent mechanism of transcriptional silencing in cancer. The molecular mechanisms underlying the specificity of methylation are unknown. We report here that the leukemia-promoting PML-RAR fusion protein induces gene hypermethylation and silencing by recruiting DNA methyltransferases to target promoters and that hypermethylation contributes to its leukemogenic potential. Retinoic acid treatment induces promoter demethylation, gene reexpression, and reversion of the transformed phenotype. These results establish a mechanistic link between genetic and epigenetic changes during transformation and suggest that hypermethylation contributes to the early steps of carcinogenesis.

Azacitidine↗

PubMed2002

DNA methyltransferases get connected to chromatin.

The DNA methyltransferases (Dnmts) are responsible for the generation of genomic methylation patterns, which lead to transcriptional silencing. Recent studies have identified new protein partners for the Dnmts revealing novel mechanisms by which they can be targeted to specific genomic regions to silence genes. In particular, the links identified with histone deacetylases, histone methyltransferases and SNF-2-like ATPases are defining new requirements for the functioning of Dnmts. A picture is emerging whereby the Dnmts are intimately connected to the chromatin environment in which they are working.

Animals↗

PubMed2002

Histone methylation in transcriptional control.

Over the past year or so, methylation of histones has come to be recognised as a major player in the regulation of gene activity. This notion follows the discovery of lysine and arginine methyltransferases and proteins that recognise the methyl-lysine 'mark' on histones. Methylated histones have been implicated in heterochromatic repression, promoter regulation and the propagation of a repressed state via DNA methylation.

Amino Acid Sequence↗

PubMed2002

Unsafe SETs: histone lysine methyltransferases and cancer.

Enzymes that covalently modify histones control many cellular processes by affecting gene expression. A new class of these enzymes is the histone lysine methyltransferase family, whose catalytic activity lies within a conserved domain, the SET domain. This article surveys the evidence for a connection between SET-domain-containing proteins and cancer. It proposes that deregulation of SET-domain function has an important role in carcinogenesis.

Amino Acid Sequence↗

PubMed2002

Histone methylation defines epigenetic asymmetry in the mouse zygote.

The oocyte cytoplasm regulates and enhances the epigenetic asymmetry between parental genomes and, consequently, functional differences observed between them during development in mammals. Here we demonstrate a preferential interaction of HP1beta with the maternal genome immediately after fertilisation in the mouse zygote, which also shows a high level of lysine 9-methylated histone H3. In contrast, the paternal genome has neither HP1beta binding nor methylated histone H3 at these early stages. Paternal binding of HP1beta is only detected at the pronuclear stage, prior to the appearance of lysine 9-methylated histone H3. The early recruitment of heterochromatic factors specifically to the maternal genome could explain the preferential DNA demethylation of the paternal genome in the zygote.

Animals↗

PubMed2001

Methylation at arginine 17 of histone H3 is linked to gene activation.

The nuclear hormone receptor co-activator CARM1 has the potential to methylate histone H3 at arginine residues in vitro. The methyltransferase activity of CARM1 is necessary for its co-activator functions in transient transfection assays. However, the role of this methyltransferase in vivo is unclear, given that methylation of arginines is not easily detectable on histones. We have raised an antibody that specifically recognizes methylated arginine 17 (R17) of histone H3, the major site of methylation by CARM1. Using this antibody we show that methylated R17 exists in vivo. Chromatin immunoprecipitation analysis shows that R17 methylation on histone H3 is dramatically upregulated when the estrogen receptor-regulated pS2 gene is activated. Coincident with the appearance of methylated R17, CARM1 is found associated with the histones on the pS2 gene. Together these results demonstrate that CARM1 is recruited to an active promoter and that CARM1-mediated R17 methylation on histone H3 takes place in vivo during this active state.

Animals↗