Inhibition of DNMT1 methyltransferase activity via glucose-regulated O-GlcNAcylation alters the epigenome

  1. Heon Shin
  2. Amy Leung
  3. Kevin R Costello
  4. Parijat Senapati
  5. Hiroyuki Kato
  6. Roger E Moore
  7. Michael Lee
  8. Dimitri Lin
  9. Xiaofang Tang
  10. Patrick Pirrotte
  11. Zhen Bouman Chen
  12. Dustin E Schones  Is a corresponding author
  1. Department of Diabetes Complications and Metabolism, Beckman Research Institute, City of Hope, United States
  2. Irell and Manella Graduate School of Biological Sciences, City of Hope, United States
  3. Integrated Mass Spectrometry Shared Resource, City of Hope Comprehensive Cancer Center Duarte, United States
  4. Cancer & Cell Biology Division, Translational Genomics Research Institute, United States
5 figures, 1 table and 5 additional files

Figures

Figure 1 with 5 supplements
High glucose increases O-GlcNAcylation of DNMT1 in cell lines and primary cells.

(A) Hep3B cells were treated with glucose (5 mM or 25 mM) with or without Thiamet-G (TMG). Shown are immunoblots of collected lysates using antibody targeting O-GlcNAc and GAPDH (n = 3). (B) Lysates of Hep3B treated with glucose were immunoprecipitated with DNMT1 and immunoprecipitates were immunoblotted with antibody targeting O-GlcNAc (n = 3). (C) Peripheral blood mononuclear cells (PBMCs) were isolated from three individual donor blood samples and treated with increasing concentration of glucose for 24 hr. Collected cell lysates from PBMCs were immunoprecipitated with antibody targeting DNMT1 and immunoblotted for O-GlcNAc. Representative blot from one donor (n = 3). (D) Immunoblots for O-GlcNAc and GAPDH from liver samples of C57BL/6J mice given a high-fat/high-sucrose diet (HF/HS) or normal diet (chow) for 4 mo, and immunoprecipitated with Dnmt1. Lysates of mouse liver were immunoprecipitated with Dnmt1 and immunoprecipitates were immunoblotted with antibody targeting O-GlcNAc. *p<0.001; **p<0.0005; ***p<0.0001 by Student’s t-test (A-D); ns, not significant; data are represented as mean ± SD from three replicates of each sample.

Figure 1—figure supplement 1
DNMT1 can be O-GlcNAcylated in Hep3B cells.

Hep3B cells were treated with Thiamet-G (TMG) or OSMI-4 (OSMI). Shown are representative immunoblots of treated Hep3B lysates performed with antibodies targeting O-GlcNAc and GAPDH and bar graphs of relative expression between O-GlcNAc compared to control, GAPDH (n = 3, experimental replicates). Lysates from treated Hep3B with glucose were immunoprecipitated with DNMT1 and immunoprecipitates were immunoblotted with antibody targeting O-GlcNAc (n = 3). ***p<0.0001 by Student’s t-test; Data are represented as mean ± SD from three replicates of each sample.

Figure 1—figure supplement 2
DNMT1 can be O-GlcNAcylated in HepG2 cells and B-cells-derived lymphocytes.

(A) HepG2 cells were treated with Thiamet-G or OSMI. Shown are immunoblots of treated HepG2 lysates performed with immunoblots of immunoprecipitates performed with antibodies targeting O-GlcNAc (n = 3). (B) Shown are immunoblots of B cell and lymphocytes (LCL) lysates performed with immunoblots of immunoprecipitates performed with antibodies targeting O-GlcNAc (n = 3). **p<0.0005, ***p<0.0001 by Student’s t-test (A, B); data are represented as mean ± SD from three replicates of each sample.

Figure 1—figure supplement 3
Global protein O-GlcNAcylation was induced with high concentrations of sucrose.

(A) Hep3B cells were treated with sucrose (5 mM or 25 mM). Shown are immunoblots of collected lysates using antibody targeting O-GlcNAc and GAPDH (n = 3). Lysates of Hep3B treated with sucrose were immunoprecipitated with DNMT1 and immunoprecipitates were immunoblotted with antibody targeting O-GlcNAc (n = 3). (B) HepG2 cells were treated with 5 mM glucose or sucrose, or 25 mM glucose or sucrose. Lysates of HepG2 treated with glucose were immunoprecipitated with DNMT1 and immunoprecipitates were immunoblotted with antibody targeting O-GlcNAc (n = 3). **p<0.0005; ***p<0.0001 by Student’s t-test (A, B); data are represented as mean ± SD from three replicates of each sample.

Figure 1—figure supplement 4
The enzymatic activity of OGT or OGA was not significantly changed by glucose treatment.

(A) OGT activity was measured with low (5 mM, CTRL) or high glucose/Thiamet-G (TMG) (25 mM, O-GlcNAc) using the UDP-Glo Glycosyltransferase activity kit (Promega) (n = 3). (B) OGA activity was measured with low (5 mM, CTRL) or high glucose with TMG (25 mM, O-GlcNAc) using the O-GlcNAcase (OGA, NAG, or MGEA5) assay kit (Biomedical Research Service & Clinical Application) (n = 3). ns, not significant; data are represented as mean ± SD from three replicates of each sample.

Figure 1—figure supplement 5
DNMT1 can be O-GlcNAcylated in primary cells (peripheral blood mononuclear cells [PBMCs]).

Pooled PBMCs treated with low (5 mM, CTRL) or high glucose/Thiamet-G (TMG) (25 mM, O-GlcNAc) were immunoprecipitated with antibody targeting DNMT1 and immunoblotted for O-GlcNAc (n = 3). ***p<0.0001 by Student’s t-test; data are represented as mean ± SD from three replicates of each sample.

Figure 2 with 2 supplements
Identification of O-GlcNAcylated sites within DNMT1 by LC-MS/MS.

(A) Schematic drawing of the DNMT1 O-GlcNAc-modified region enriched from Hep3B cells based on mass spectrometry (MS) data and tandem MS (MS/MS) peaks. FTMS+ p NSI full MS (400.0000–1600.0000). DQDYARFESPPKTQPTEDNKF (S9 HexNAc) – S878. (B) Schematic diagram of identified novel O-GlcNAcylated and phosphorylated sites within DNMT1 as determined via LC-MS/MS. DMAP, DNA methyltransferase associated protein-binding domain; PCNA, proliferating cell nuclear antigen-binding domain; NLS, nuclear localization sequences; RFTS, replication foci targeting sequence domain; BAH, bromo-adjacent homology domain. (C) Sequence conservation of S878 in vertebrates. (D) Each immunoprecipitated Myc-DNMT1 wild type and substituted mutants was immunoblotted with an O-GlcNAc antibody (n = 3). **p<0.0005; ***p<0.0001 by Student’s t-test (D); N.D., not detected, ns, not significant; data are represented as mean ± SD from three replicates of each sample.

Figure 2—figure supplement 1
Myc-DNMT1-WT in Hep3B cells can be O-GlcNAcylated.

Myc-DNMT1-WT were transfected into Hep3B cells. Shown are immunoblots of treated DNMT1-WT lysates performed with antibodies targeting Myc, DNMT1, Tubulin, H3, and O-GlcNAc (n = 3). Lysates from treated DNMT1-WT were immunoprecipitated with Myc antibody. Shown are immunoblots of immunoprecipitates performed with antibodies targeting O-GlcNAc and CBB stained gel (Coomassie Brilliant Blue stain).

Figure 2—figure supplement 2
Tandem MS/MS peaks of O-GlcNAcylated DNMT1 peptides.
Figure 3 with 3 supplements
Site-specific O-GlcNAcylation inhibits DNMT1 methyltransferase function.

For (A–D), bar graphs are of relative activity of DNA methyltransferase activity measured as absorbance from a DNMT activity/Inhibition ELISA kit and representative immunoblots of immunoprecipitates performed with antibodies targeting DNMT1. (A) Hep3B cells were treated with low (5 mM, CTRL) or high glucose/Thiamet-G (TMG) (25 mM, O-GlcNAc) (n = 3). (B) Peripheral blood mononuclear cells (PBMCs) from donors were treated with increasing concentrations of glucose (range: 0–25 mM with TMG) (n = 3). (C) Liver samples from C57BL/6J mice given a high-fat/high-sucrose diet (HF/HS) or a normal diet (chow) for 4 mo. (D) Immunoprecipitated DNMT1 wild type and substituted mutants were treated with 5 mM or 25 mM glucose (n = 3). *p<0.001; **p<0.0005; ***p<0.0001 by Student’s t-test (A–D); ns, not significant; data are represented as mean ± SD from three replicates of each sample.

Figure 3—figure supplement 1
Site-specific O-GlcNAcylation at DNMT1 sites abrogate the function of methyltransferase and DNA loss of methylation at CpG island under high glucose/Thiamet-G (TMG) conditions.

(A) HepG2 cells were treated with low (5 mM, CTRL) or high glucose/TMG (25 mM, O-GlcNAc). Shown are absorbance of DNA methyltransferase activity performed with DNA methyltransferase activity kit (n = 3, technical replicates from three biological replicates for each strain). (B) Hep3B cells were treated with 25 mM glucose with or without Thiamet-G by time dependent. Shown are absorbance of DNA methyltransferase activity performed with DNA methyltransferase activity kit (n = 3, technical replicates from three biological replicates for each strain). **p<0.0005, ***p<0.0001 by Student’s t-test (A, B); data are represented as mean ± SD from three replicates of each sample.

Figure 3—figure supplement 2
The methylation loss by high glucose/Thiamet-G (TMG) conditions was not apparent in the DNMT1-S878A mutant.

(A) Each Hep3B and Myc-DNMT1-overexpressed mutant (DNMT1-WT or DNMT1-S878A) was treated with low (5 mM, CTRL) or high glucose/TMG (25 mM, O-GlcNAc), 5-aza or GSK-3484862 (negative control). Shown are absorbance of global DNA methylation of LINE-1 performed with global DNA methylation LINE-1 kit (n = 3). (B) Each HepG2 and Myc-DNMT1-overexpressed mutants (DNMT1-WT or DNMT1-S878A) were treated with low (5 mM, CTRL) or high glucose/TMG (25 mM, O-GlcNAc). Shown are absorbance of global DNA methylation of LINE-1 performed with global DNA methylation LINE-1 kit (n = 3, technical replicates from three biological replicates for each strain). (C) DNA was extracted from Hep3B and Myc-DNMT1-overexpressed mutants (DNMT1-WT or DNMT1-S878A) were treated with low (5 mM, CTRL) or high glucose/TMG (25 mM, O-GlcNAc) or 5-aza (negative control) with MspI (negative control) or HpaII. Shown are extracted genomic DNA samples and analyze on the 4200 TapeStation System with the Genomic DNA Screen Tape assay with methylation-sensitive enzyme using MspI or HpaII (n = 3, technical replicates from three biological replicates for each strain). **p<0.0005; ***p<0.0001 by Student’s t-test (A, B); ns, not significant; data are represented as mean ± SD from three replicates of each sample.

Figure 3—figure supplement 3
High glucose/Thiamet-G (TMG) conditions do not impact localization of DNMT1-WT or DNMT1-S878A.

(A) Hep3B cells expressed with DNMT1-WT and DNMT1-S878 cells were treated with low (5 mM, CTRL) or high glucose/TMG (25 mM, O-GlcNAc). (B) HepG2 cells expressed with DNMT1-WT and DNMT1-S878 cells were treated with low (5 mM, CTRL) or high glucose/TMG (25 mM, O-GlcNAc). DNMT1 localization was determined by immunofluorescence using confocal microscopy.

Figure 4 with 8 supplements
High glucose leads to loss of DNA methylation at cancer-specific partially methylated domains (PMDs).

(A) Density plot of DNA methylation for DNMT1-WT and DNMT1-S878A cells with either low (5 mM, CTRL) or high glucose/Thiamet-G (TMG) (25 mM, O-GlcNAc). (B) Genome browser screenshot of DNA methylation for DNMT1-WT and DNMT1-S878A cells and low or high glucose along with liver tumor PMDs from Li et al., 2016. (C) Boxplots of DNA methylation at PMDs or general genomic background (BG) for each DNMT1-WT and DNMT1-S878A treated with low (5 mM, CTRL) or high glucose/TMG (25 mM, O-GlcNAc). (D) Heatmap representation of global DNA methylation for DNMT1-WT and DNMT1-S878A cells under low (5 mM, CTRL) or high glucose/TMG (25 mM, O-GlcNAc) at gene-poor and gene-rich regions. (E) Methylation changes from O-GlcNAcylation of DNMT1 by wave score for replication timing (Hansen et al., 2010; Thurman et al., 2007). ***p<0.0001 by Wilcoxon signed-rank test (C).

Figure 4—figure supplement 1
DNA loss of methylation by increased global O-GlcNAcylation decreases.

Density plot of DNA methylation for DNMT1-WT and DNMT1-S878A cells with either low (5 mM, CTRL) or high glucose/Thiamet-G (TMG) (25 mM, O-GlcNAc). (A) Partially methylated domain (PMD) regions, (B) non-PMD regions. (C–G) Bar graphs represent percentage of global DNA methylation of wild type and DNMT1 mutants (DNMT1-WT or DNMT1-S878A) that treated low (5 mM, CTRL) or high glucose/TMG (25 mM, O-GlcNAc). (C) 5’UTR, (D) promoter, (E) gene body, (F) 3’UTR, and (G) intergenic regions. (H) Genome browser screenshot of DNA methylation data at a differentially methylated region by glucose concentration.

Figure 4—figure supplement 2
Global DNA methylation of wild type and DNMT1 mutants between low Fragments Per Kilobase of transcript per Million mapped reads (FPKM) regions and high FPKM regions (DNMT1-WT or DNMT1-S878A) that treated low (5 mM, CTRL) or high glucose/Thiamet-G (TMG) (25 mM, O-GlcNAc) were determined by Nanopolish call methylation.

These are defined 'low FPKM' as containing <25% of FPKM regions per Mb window and 'high FPKM' as containing >75% of FPKM regions per Mb window.

Figure 4—figure supplement 3
Methylation changes from O-GlcNAcylation of DNMT1 in DNMT1-S878A mutant.

The loss of methylation was not observed in S878A mutant cells. (A, B) The distribution of each DNA methylation was divided by DNA replication timing.

Figure 4—figure supplement 4
DNA loss of methylation by increased global O-GlcNAcylation decreases around the transposable element (TE) regions.

(A) Boxplot represents the levels of DNA methylation on the TE regions or non-TE regions of each Myc-DNMT1-overexpressed mutants (DNMT1-WT or DNMT1-S878A) were treated with low (5 mM, CTRL) or high glucose/Thiamet-G (TMG) (25 mM, O-GlcNAc). (B–D) Bar graphs represent percentage of global DNA methylation of wild type and DNMT1 mutants (DNMT1-WT or DNMT1-S878A) that treated low (5 mM, CTRL) or high glucose/TMG (25 mM, O-GlcNAc). (B) SINE, (C) LINE, and (D) LTR regions. **p<0.0005; ***p<0.0001 by Wilcoxon signed-rank test (A–D); ns, not significant.

Figure 4—figure supplement 5
Loss of DNA methylation by increased global O-GlcNAcylation decreases.

Evolutionarily recent TEs are more likely to lose methylation than older elements in a variety of systems. Methylation percentages are shown around (A) LTR12C and (B) HERVH-int regions. The Myc-DNMT1 overexpressed mutants (DNMT1-WT or DNMT1-S878A) were treated low (5mM, CTRL) or high glucose/TMG (25mM, O-GlcNAc).

Figure 4—figure supplement 6
ZFP57 and ZNF605 demonstrate binding to a significant number of LTR12C elements present in liver cancer partially methylated domains (PMDs).

Genome browser screenshot of DNA methylation data LTR12C elements (blue) that demonstrate binding with ZFP57 and ZNF605 by glucose concentration.

Figure 4—figure supplement 7
Evolutionarily recent elements are less likely to lose methylation induced by O-GlcNAcylation of DNMT1.

The evolutionary distance between each group is from Perelman et al., 2011. Boxplot represents the DNA methylation by clades of the human genome (Homo sapiens to Haplorhini). CTRL, control; O-Glc, O-GlcNAc.

Figure 4—figure supplement 8
Only loci with >5× coverage were retained for analysis, comprising 90% of CpGs in the genome.

Shown are overall CpGs sites that detected with >5× coverage DNA methylation analysis using Nanopore technology PromethION sequencer. Each condition is biologically replicated.

Figure 5 with 4 supplements
High glucose-induced reactive oxygen species (ROS) and DNA damage cause apoptotic cell death in DNMT1-WT cells.

(A) Quantitative fluorescence image of ROS in DNMT1-WT and DNMT1-S878A cells with either low (5 mM, CTRL) or high glucose/Thiamet-G (TMG) (25 mM, O-GlcNAc). (B) Quantitative fluorescence image of γ-H2A.X in DNMT1-WT and DNMT1-S878A cells treated with low (5 mM, CTRL) or high glucose/TMG (25 mM, O-GlcNAc). (C) Quantitative fluorescence image of cell death in propidium iodide staining of DNMT1-WT and DNMT1-S878A cells under low (5 mM, CTRL) or high glucose/TMG (25 mM, O-GlcNAc). *p<0.001; **p<0.0005; ***p<0.0001 by Student’s t-test (A–C); data are represented as mean ± SD from three replicates of each sample.

Figure 5—figure supplement 1
Heatmap representation of promoter DNA methylation for DNMT1-WT and DNMT1-S878A cells under low (5 mM, CTRL) or high glucose/Thiamet-G (TMG) (25 mM, O-GlcNAc) at gene-poor and gene-rich regions.

(A) Whole promoters and (B) differentially methylated promoters.

Figure 5—figure supplement 2
DNA loss of methylation within promoter region by increased global O-GlcNAcylation impact different gene pathways.

(A) Gene Ontology of the top 11 pathways of hypomethylated promoter DNA by high glucose treatment. (B) Gene interaction map of hypomethylated promoter DNA of DNMT1-WT by high glucose treatment.

Figure 5—figure supplement 3
Quantitative analysis of human apoptosis related proteins in DNMT1-WT and DNMT1-S878A with either low (5 mM, CTRL) or high glucose/Thiamet-G (TMG) (25 mM, O-GlcNAc) using Proteome profiler (n = 3).

PC, positive control; NC, negative control; 1. cleaved-caspase3; 2, cIAP1; 3, claspin; 4, phospho-p53(S15); 5, survivin. ***p<0.0001 by Student’s t-test; Data are represented as mean ± SD from three replicates of each sample.

Figure 5—figure supplement 4
Each Hep3B (Mock) and Myc-DNMT1-overexpressed mutant (DNMT1-WT or DNMT1-S878A) was treated with low (5 mM, CTRL) or high glucose/Thiamet-G (TMG) (25 mM, O-GlcNAc), 5-aza, or GSK-3484862 (negative control).

Shown are absorbance of 8-OHdG performed with DNA damage quantification kit (n = 3). **p<0.0005; ***p<0.0001 by Student’s t-test; ns, not significant; data are represented as mean ± SD from three replicates of each sample.

Tables

Key resources table
Reagent type (species) or resourceDesignationSource or referenceIdentifiersAdditional information
Gene
(Homo sapiens)
DNMT1HUGO Gene Nomenclature CommitteeHGNC:2976-
Cell line
(H. sapiens)
Hep 3B2.1–7ATCCHB-8064-
Cell line
(H. sapiens)
Hep G2ATCCHB-8065-
Transfected construct
(H. sapiens)
pcDNA3/Myc-DNMT1AddgenePlasmid #36939
AntibodyAnti-beta-actin (D6A8)
(rabbit monoclonal)
Cell Signaling TechnologyCat# 8457WB (1:1000)
AntibodyAnti-alpha-tubulin (11H10)
(rabbit monoclonal)
Cell Signaling TechnologyCat# 2125WB (1:1000)
AntibodyAnti-DNMT1 (60B1220.1)
(mouse monoclonal)
Novus BiologicalsCat# NB100-56519IP (1:250)
WB (1:1000)
AntibodyAnti-DNMT1 (H-12)
(mouse monoclonal)
Santa Cruz BiotechnologyCat# sc-271729WB (1:1000)
AntibodyAnti-gamma H2A.X
(rabbit polyclonal)
AbcamCat# ab11174IF (1:1000)
AntibodyAnti-GAPDH
(rabbit monoclonal)
AbcamCat# ab181602WB (1:1000)
AntibodyAnti-H3
(rabbit polyclonal)
AbcamCat# ab1791WB (1:1000)
AntibodyAnti-Myc [Myc.A7]
(mouse monoclonal)
AbcamCat# ab18185IP (1:250)
WB (1:1000)
AntibodyAnti-O-GlcNAc (RL2)
(mouse monoclonal)
AbcamCat# ab2739WB (1:1000)
AntibodyAoat anti-rabbit IgG H&L (HRP)
(goat polyclonal)
AbcamCat# ab6721WB (1:5000)
AntibodyGoat anti-mouse IgG H&L (HRP)
(goat polyclonal)
AbcamCat# ab6789WB (1:5000)
AntibodyGoat anti-mouse IgG (H+L), Alexa 488
(goat polyclonal)
InvitrogenCat# A32723WB (1:1000)
Sequence-based reagentDNMT1-T158AThis paperPCR primersagccccaggatt CGA aggaaaagcacc
Sequence-based reagentDNMT1-T158AThis paperPCR primersggtgcttttcct TCG aatcctggggct
Sequence-based reagentDNMT1-T616AThis paperPCR primersgacaggggaccc GCG aaagccaccacc
Sequence-based reagentDNMT1-T616AThis paperPCR primersggtggtggcttt CGC gggtcccctgtc
Sequence-based reagentDNMT1-S878AThis paperPCR primersgcgagattcgag GAG cctccaaaaacc
Sequence-based reagentDNMT1-S878AThis paperPCR primersggtttttggagg CTC ctcgaatctcgc
Sequence-based reagentDNMT1-S878DThis paperPCR primersgcgagattcgag GAC cctccaaaaacc
Sequence-based reagentDNMT1-S878DThis paperPCR primersggtttttggagg GTC ctcgaatctcgc
Sequence-based reagentDNMT1-T882AThis paperPCR primerstcccctccaaaa GCC cagccaacagag
Sequence-based reagentDNMT1-T882AThis paperPCR primersctctgttggctg GGC ttttggagggga
Commercial assay or kitQ5 Site-Directed Mutagenesis kitNEBCat# E0554S-
Commercial assay or kitEpiQuik DNMT Activity/Inhibition ELISA Easy KitEpiGentekCat# P-3139-
Commercial assay or kitGlobal DNA methylation LINE-1Active MotifCat# 55017-
Commercial assay or kitEpiQuik 8-OHdG DNA Damage Quantification Direct kitEpiGentekCat# P-6003-
Chemical compound, drugOSMI-4Selleck ChemCat# S8910-
Chemical compound, drugThiamet-G (TMG)Cayman ChemicalCat# 13237-
Software, algorithmbedGraphToBigWigKent et al., 2010--
Software, algorithmClustal OmegaSievers et al., 2011-Version 1.2.4
Software, algorithmGraphPad Prism 9GraphPad-Version: 9.3.1
Software, algorithmMinimap2Li and Birol, 2018RRID:SCR_018550Version: 2.17
Software, algorithmNanopolishLoman et al., 2015RRID:SCR_016157Version: 0.11.1
Software, algorithmPythonPython Core TeamVersion: 3.8.2
Software, algorithmRR Core Team-Version: 3.4.3
Software, algorithmSamtoolsLister et al., 2009RRID:SCR_002105Version: 1.10
OtherUniProtThe UniProt Consortium-Database of protein information (https://www.uniprot.org/)
OtherDAPI stainInvitrogenD13061 µg/ml; marker for nuclear DNA

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  1. Heon Shin
  2. Amy Leung
  3. Kevin R Costello
  4. Parijat Senapati
  5. Hiroyuki Kato
  6. Roger E Moore
  7. Michael Lee
  8. Dimitri Lin
  9. Xiaofang Tang
  10. Patrick Pirrotte
  11. Zhen Bouman Chen
  12. Dustin E Schones
(2023)
Inhibition of DNMT1 methyltransferase activity via glucose-regulated O-GlcNAcylation alters the epigenome
eLife 12:e85595.
https://doi.org/10.7554/eLife.85595