scholarly journals LSH Cooperates with DNA Methyltransferases To Repress Transcription

2007 ◽  
Vol 28 (1) ◽  
pp. 215-226 ◽  
Author(s):  
Kevin Myant ◽  
Irina Stancheva
Keyword(s):  
Dna Methylation ◽  
Chromatin Remodeling ◽  
Transcriptional Repression ◽  
Histone Deacetylases ◽  
Mammalian Cells ◽  
Dna Methyltransferase ◽  
Dna Methyltransferases ◽  
Large Protein ◽  
Large Protein Complex ◽  
Nuclear Extracts

ABSTRACT LSH, a protein related to the SNF2 family of chromatin-remodeling ATPases, is required for efficient DNA methylation in mammals. How LSH functions to support DNA methylation and whether it associates with a large protein complex containing DNA methyltransferase (DNMT) enzymes is currently unclear. Here we show that, unlike many other chromatin-remodeling ATPases, native LSH is present mostly as a monomeric protein in nuclear extracts of mammalian cells and cannot be detected in a large multisubunit complex. However, when targeted to a promoter of a reporter gene, LSH acts as an efficient transcriptional repressor. Using this as an assay to identify proteins that are required for LSH-mediated repression we found that LSH cooperates with the DNMTs DNMT1 and DNMT3B and with the histone deacetylases (HDACs) HDAC1 and HDAC2 to silence transcription. We show that transcriptional repression by LSH and interactions with HDACs are lost in DNMT1 and DNMT3B knockout cells but that the enzymatic activities of DNMTs are not required for LSH-mediated silencing. Our data suggest that LSH serves as a recruiting factor for DNMTs and HDACs to establish transcriptionally repressive chromatin which is perhaps further stabilized by DNA methylation at targeted loci.

scholarly journals Expanding the Structural Diversity of DNA Methyltransferase Inhibitors

2020 ◽  
Vol 14 (1) ◽  
pp. 17
Author(s):  
K. Eurídice Juárez-Mercado ◽  
Fernando D. Prieto-Martínez ◽  
Norberto Sánchez-Cruz ◽  
Andrea Peña-Castillo ◽  
Diego Prada-Gracia ◽  
...  
Keyword(s):  
Histone Deacetylases ◽  
Dna Methyltransferase ◽  
Structural Diversity ◽  
Dna Methyltransferases ◽  
Dna Methyltransferase Inhibitors ◽  
Epigenetic Drug ◽  
Ic50 Values ◽  
Dietary Component ◽  
Approved Drugs ◽  
Epigenetic Processes

Inhibitors of DNA methyltransferases (DNMTs) are attractive compounds for epigenetic drug discovery. They are also chemical tools to understand the biochemistry of epigenetic processes. Herein, we report five distinct inhibitors of DNMT1 characterized in enzymatic inhibition assays that did not show activity with DNMT3B. It was concluded that the dietary component theaflavin is an inhibitor of DNMT1. Two additional novel inhibitors of DNMT1 are the approved drugs glyburide and panobinostat. The DNMT1 enzymatic inhibitory activity of panobinostat, a known pan inhibitor of histone deacetylases, agrees with experimental reports of its ability to reduce DNMT1 activity in liver cancer cell lines. Molecular docking of the active compounds with DNMT1, and re-scoring with the recently developed extended connectivity interaction features approach, led to an excellent agreement between the experimental IC50 values and docking scores.

scholarly journals DNA Methyltransferase 3A Is Involved in the Sustained Effects of Chronic Stress on Synaptic Functions and Behaviors

2020 ◽  
Author(s):  
Jing Wei ◽  
Jia Cheng ◽  
Nicholas J Waddell ◽  
Zi-Jun Wang ◽  
Xiaodong Pang ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Dna Methyltransferase ◽  
Epigenetic Modification ◽  
Substantial Reduction ◽  
Dna Methyltransferases ◽  
Male Rats ◽  
Neural Pathways ◽  
Dnmt Inhibitors ◽  
Synaptic Functions

Abstract Emerging evidence suggests that epigenetic mechanisms regulate aberrant gene transcription in stress-associated mental disorders. However, it remains to be elucidated about the role of DNA methylation and its catalyzing enzymes, DNA methyltransferases (DNMTs), in this process. Here, we found that male rats exposed to chronic (2-week) unpredictable stress exhibited a substantial reduction of Dnmt3a after stress cessation in the prefrontal cortex (PFC), a key target region of stress. Treatment of unstressed control rats with DNMT inhibitors recapitulated the effect of chronic unpredictable stress on decreased AMPAR expression and function in PFC. In contrast, overexpression of Dnmt3a in PFC of stressed animals prevented the loss of glutamatergic responses. Moreover, the stress-induced behavioral abnormalities, including the impaired recognition memory, heightened aggression, and hyperlocomotion, were partially attenuated by Dnmt3a expression in PFC of stressed animals. Finally, we found that there were genome-wide DNA methylation changes and transcriptome alterations in PFC of stressed rats, both of which were enriched at several neural pathways, including glutamatergic synapse and microtubule-associated protein kinase signaling. These results have therefore recognized the potential role of DNA epigenetic modification in stress-induced disturbance of synaptic functions and cognitive and emotional processes.

scholarly journals Structural insights into CpG-specific DNA methylation by human DNA methyltransferase 3B

2020 ◽  
Vol 48 (7) ◽  
pp. 3949-3961 ◽  
Author(s):  
Chien-Chu Lin ◽  
Yi-Ping Chen ◽  
Wei-Zen Yang ◽  
James C K Shen ◽  
Hanna S Yuan
Keyword(s):  
Dna Methylation ◽  
Dna Methyltransferase ◽  
Cytosine Methylation ◽  
Catalytic Domain ◽  
De Novo ◽  
Water Channel ◽  
Dna Methyltransferases ◽  
Structural Basis ◽  
Cpg Sites ◽  
Methylation Patterns

Abstract DNA methyltransferases are primary enzymes for cytosine methylation at CpG sites of epigenetic gene regulation in mammals. De novo methyltransferases DNMT3A and DNMT3B create DNA methylation patterns during development, but how they differentially implement genomic DNA methylation patterns is poorly understood. Here, we report crystal structures of the catalytic domain of human DNMT3B–3L complex, noncovalently bound with and without DNA of different sequences. Human DNMT3B uses two flexible loops to enclose DNA and employs its catalytic loop to flip out the cytosine base. As opposed to DNMT3A, DNMT3B specifically recognizes DNA with CpGpG sites via residues Asn779 and Lys777 in its more stable and well-ordered target recognition domain loop to facilitate processive methylation of tandemly repeated CpG sites. We also identify a proton wire water channel for the final deprotonation step, revealing the complete working mechanism for cytosine methylation by DNMT3B and providing the structural basis for DNMT3B mutation-induced hypomethylation in immunodeficiency, centromere instability and facial anomalies syndrome.

P.2.e.017 DNA methylation is selectively altered in bipolar disorder and linked to DNA methyltransferases and histone deacetylases mRNAs levels

2012 ◽  
Vol 22 ◽  
pp. S285-S286
Author(s):  
C. D'Addario ◽  
B. Dell'Osso ◽  
A. Di Francesco ◽  
M.C. Palazzo ◽  
B. Benatti ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Bipolar Disorder ◽  
Histone Deacetylases ◽  
Dna Methyltransferases

scholarly journals Control of the DNA Methylation System Component MBD2 by Protein Arginine Methylation

2006 ◽  
Vol 26 (19) ◽  
pp. 7224-7235 ◽  
Author(s):  
Choon Ping Tan ◽  
Sara Nakielny
Keyword(s):  
Dna Methylation ◽  
Complex Formation ◽  
Histone Deacetylases ◽  
Mammalian Cells ◽  
Genome Stability ◽  
Epigenetic Modification ◽  
Arginine Methylation ◽  
System Component ◽  
Transcription Repression ◽  
Mbd Proteins

ABSTRACT DNA methylation is vital for proper chromatin structure and function in mammalian cells. Genetic removal of the enzymes that catalyze DNA methylation results in defective imprinting, transposon silencing, X chromosome dosage compensation, and genome stability. This epigenetic modification is interpreted by methyl-DNA binding domain (MBD) proteins. MBD proteins respond to methylated DNA by recruiting histone deacetylases (HDAC) and other transcription repression factors to the chromatin. The MBD2 protein is dispensable for animal viability, but it is implicated in the genesis of colon tumors. Here we report that the MBD2 protein is controlled by arginine methylation. We identify the protein arginine methyltransferase enzymes that catalyze this modification and show that arginine methylation inhibits the function of MBD2. Arginine methylation of MBD2 reduces MBD2-methyl-DNA complex formation, reduces MBD2-HDAC repression complex formation, and impairs the transcription repression function of MBD2 in cells. Our report provides a molecular description of a potential regulatory mechanism for an MBD protein family member. It is the first to demonstrate that protein arginine methyltransferases participate in the DNA methylation system of chromatin control.

scholarly journals Complex DNA sequence readout mechanisms of the DNMT3B DNA methyltransferase

2020 ◽  
Vol 48 (20) ◽  
pp. 11495-11509
Author(s):  
Michael Dukatz ◽  
Sabrina Adam ◽  
Mahamaya Biswal ◽  
Jikui Song ◽  
Pavel Bashtrykov ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Dna Methyltransferase ◽  
Catalytic Mechanism ◽  
Catalytic Domain ◽  
Dna Methyltransferases ◽  
Flanking Sequence ◽  
Cpg Sites ◽  
Binding Interface ◽  
Target Sites ◽  
Flanking Sequences

Abstract DNA methyltransferases interact with their CpG target sites in the context of variable flanking sequences. We investigated DNA methylation by the human DNMT3B catalytic domain using substrate pools containing CpX target sites in randomized flanking context and identified combined effects of CpG recognition and flanking sequence interaction together with complex contact networks involved in balancing the interaction with different flanking sites. DNA methylation rates were more affected by flanking sequences at non-CpG than at CpG sites. We show that T775 has an essential dynamic role in the catalytic mechanism of DNMT3B. Moreover, we identify six amino acid residues in the DNA-binding interface of DNMT3B (N652, N656, N658, K777, N779, and R823), which are involved in the equalization of methylation rates of CpG sites in favored and disfavored sequence contexts by forming compensatory interactions to the flanking residues including a CpG specific contact to an A at the +1 flanking site. Non-CpG flanking preferences of DNMT3B are highly correlated with non-CpG methylation patterns in human cells. Comparison of the flanking sequence preferences of human and mouse DNMT3B revealed subtle differences suggesting a co-evolution of flanking sequence preferences and cellular DNMT targets.

scholarly journals Developmental remodelling of non-CG methylation at satellite DNA repeats

2020 ◽  
Vol 48 (22) ◽  
pp. 12675-12688 ◽  
Author(s):  
Samuel E Ross ◽  
Allegra Angeloni ◽  
Fan-Suo Geng ◽  
Alex de Mendoza ◽  
Ozren Bogdanovic
Keyword(s):  
Stem Cells ◽  
Embryonic Stem Cells ◽  
Transcriptional Repression ◽  
Dna Methyltransferase ◽  
Embryonic Stem ◽  
Dna Methyltransferases ◽  
Dna Repeats ◽  
Satellite Repeats ◽  
Cg Dinucleotides ◽  
The Brain

Abstract In vertebrates, DNA methylation predominantly occurs at CG dinucleotides however, widespread non-CG methylation (mCH) has been reported in mammalian embryonic stem cells and in the brain. In mammals, mCH is found at CAC trinucleotides in the nervous system, where it is associated with transcriptional repression, and at CAG trinucleotides in embryonic stem cells, where it positively correlates with transcription. Moreover, CAC methylation appears to be a conserved feature of adult vertebrate brains. Unlike any of those methylation signatures, here we describe a novel form of mCH that occurs in the TGCT context within zebrafish mosaic satellite repeats. TGCT methylation is inherited from both male and female gametes, remodelled during mid-blastula transition, and re-established during gastrulation in all embryonic layers. Moreover, we identify DNA methyltransferase 3ba (Dnmt3ba) as the primary enzyme responsible for the deposition of this mCH mark. Finally, we observe that TGCT-methylated repeats are specifically associated with H3K9me3-marked heterochromatin suggestive of a functional interplay between these two gene-regulatory marks. Altogether, this work provides insight into a novel form of vertebrate mCH and highlights the substrate diversity of vertebrate DNA methyltransferases.

DNA methylation and regulation of DNA methyltransferases in a freeze-tolerant vertebrate

2020 ◽  
Vol 98 (2) ◽  
pp. 145-153 ◽  
Author(s):  
Jing Zhang ◽  
Liam J. Hawkins ◽  
Kenneth B. Storey
Keyword(s):  
Dna Methylation ◽  
Transcriptional Repression ◽  
Freeze Tolerance ◽  
Dna Methyltransferases ◽  
Wood Frog ◽  
Activity Levels ◽  
Wood Frogs ◽  
Metabolic Role ◽  
Freeze Tolerant

The wood frog is one of the few freeze-tolerance vertebrates. This is accomplished in part by the accumulation of cryoprotectant glucose, metabolic rate depression, and stress response activation. These may be achieved by mechanisms such as DNA methylation, which is typically associated with transcriptional repression. Hyperglycemia is also associated with modifications to epigenetic profiles, indicating an additional role that the high levels of glucose play in freeze tolerance. We sought to determine whether DNA methylation is affected during freezing exposure, and whether this is due to the wood frog’s response to hyperglycemia. We examined global DNA methylation and DNA methyltransferases (DNMTs) in the liver and muscle of frozen and glucose-loaded wood frogs. The results showed that levels of 5-methylcytosine (5mC) increased in the muscle, suggesting elevated DNA methylation during freezing. DNMT activities also decreased in muscle during thawing, glucose loading, and in vitro glucose experiments. Liver DNMT activities were similar to muscle; however, a varied response to DNMT levels and a decrease in 5mC highlight the metabolic role the liver plays during freezing. Glucose was also shown to decrease DNMT activity levels in the wood frog, in vitro, elucidating a potentially novel regulatory mechanism. Together these results suggest an interplay between freeze tolerance and hyperglycemic regulation of DNA methylation.

scholarly journals DNA methyltransferase 1 and DNA methylation patterning contribute to germinal center B-cell differentiation

Blood ◽  
2011 ◽  
Vol 118 (13) ◽  
pp. 3559-3569 ◽  
Author(s):  
Rita Shaknovich ◽  
Leandro Cerchietti ◽  
Lucas Tsikitas ◽  
Matthias Kormaksson ◽  
Subhajyoti De ◽  
...  
Keyword(s):  
Dna Methylation ◽  
B Cells ◽  
Germinal Center ◽  
Dna Methyltransferase ◽  
Cytosine Deaminase ◽  
Dna Methyltransferases ◽  
B Cell Differentiation ◽  
Dual Roles ◽  
Germinal Center B Cell ◽  
Cellular Phenotypes

Abstract The phenotype of germinal center (GC) B cells includes the unique ability to tolerate rapid proliferation and the mutagenic actions of activation induced cytosine deaminase (AICDA). Given the importance of epigenetic patterning in determining cellular phenotypes, we examined DNA methylation and the role of DNA methyltransferases in the formation of GCs. DNA methylation profiling revealed a marked shift in DNA methylation patterning in GC B cells versus resting/naive B cells. This shift included significant differential methylation of 235 genes, with concordant inverse changes in gene expression affecting most notably genes of the NFkB and MAP kinase signaling pathways. GC B cells were predominantly hypomethylated compared with naive B cells and AICDA binding sites were highly overrepresented among hypomethylated loci. GC B cells also exhibited greater DNA methylation heterogeneity than naive B cells. Among DNA methyltransferases (DNMTs), only DNMT1 was significantly up-regulated in GC B cells. Dnmt1 hypomorphic mice displayed deficient GC formation and treatment of mice with the DNA methyltransferase inhibitor decitabine resulted in failure to form GCs after immune stimulation. Notably, the GC B cells of Dnmt1 hypomorphic animals showed evidence of increased DNA damage, suggesting dual roles for DNMT1 in DNA methylation and double strand DNA break repair.

scholarly journals Methylation-Mediated Transcriptional Silencing in Euchromatin by Methyl-CpG Binding Protein MBD1 Isoforms

1999 ◽  
Vol 19 (9) ◽  
pp. 6415-6426 ◽  
Author(s):  
Naoyuki Fujita ◽  
Shin-ichiro Takebayashi ◽  
Katsuzumi Okumura ◽  
Shinichi Kudo ◽  
Tsutomu Chiba ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Transcriptional Repression ◽  
Mammalian Cells ◽  
Fluorescent Protein ◽  
Cpg Islands ◽  
Transcriptional Silencing ◽  
Pericentromeric Region ◽  
Chromosome 1 ◽  
Reverse Transcription Pcr ◽  
Genome Methylation

ABSTRACT DNA methylation of promoter-associated CpG islands is involved in the transcriptional repression of vertebrate genes. To investigate the mechanisms underlying gene inactivation by DNA methylation, we characterized a human MBD1 protein, one of the components of MeCP1, which possesses a methyl-CpG binding domain (MBD) and cysteine-rich (CXXC) domains. Four novel MBD1 isoforms (MBD1v1, MBD1v2, MBD1v3, and MBD1v4) were identified by the reverse transcription-PCR method. We found that these transcripts were alternatively spliced in the region of CXXC domains and the C terminus. Green fluorescent protein-fused MBD1 was localized to multiple foci on the human genome, mostly in the euchromatin regions, and particularly concentrated in the pericentromeric region of chromosome 1. Both the MBD sequence and genome methylation were required for proper localization of the MBD1 protein. We further investigated whether MBD1 isoforms are responsible for transcriptional repression of human genes. A bacterially expressed MBD1 protein bound preferentially to methylated DNA fragments containing CpG islands from the tumor suppressor genes p16,VHL, and E-cadherin and from an imprintedSNRPN gene. All MBD1 isoforms inhibited promoter activities of these genes via methylation. Interestingly, MBD1 isoforms v1 and v2 containing three CXXC domains also suppressed unmethylated promoter activities in mammalian cells. These effects were further manifested inDrosophila melanogaster cells, which lack genome methylation. Sp1-activated transcription of methylated p16and SNRPN promoters was inhibited by all of the MBD1 isoforms, whereas the isoforms v1 and v2 reduced Sp1-activated transcription from unmethylated promoters as well. These findings suggested that the MBD1 isoforms have different roles in methylation-mediated transcriptional silencing in euchromatin.

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