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Szulik M, Pallan PS, Nocek B, Voehler M, Banerjee S, Brooks S, Joachimiak A, Egli M, Eichman BF, Stone MP. Differential stabilities and sequence-dependent base pair opening dynamics of Watson-Crick base pairs with 5-hydroxymethylcytosine, 5-formylcytosine, or 5-carboxylcytosine. Biochemistry 2015; 54:1294-305. [PMID: 25632825 PMCID: PMC4325598 DOI: 10.1021/bi501534x] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
5-Hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC) form during active demethylation of 5-methylcytosine (5mC) and are implicated in epigenetic regulation of the genome. They are differentially processed by thymine DNA glycosylase (TDG), an enzyme involved in active demethylation of 5mC. Three modified Dickerson-Drew dodecamer (DDD) sequences, amenable to crystallographic and spectroscopic analyses and containing the 5'-CG-3' sequence associated with genomic cytosine methylation, containing 5hmC, 5fC, or 5caC placed site-specifically into the 5'-T(8)X(9)G(10)-3' sequence of the DDD, were compared. The presence of 5caC at the X(9) base increased the stability of the DDD, whereas 5hmC or 5fC did not. Both 5hmC and 5fC increased imino proton exchange rates and calculated rate constants for base pair opening at the neighboring base pair A(5):T(8), whereas 5caC did not. At the oxidized base pair G(4):X(9), 5fC exhibited an increase in the imino proton exchange rate and the calculated kop. In all cases, minimal effects to imino proton exchange rates occurred at the neighboring base pair C(3):G(10). No evidence was observed for imino tautomerization, accompanied by wobble base pairing, for 5hmC, 5fC, or 5caC when positioned at base pair G(4):X(9); each favored Watson-Crick base pairing. However, both 5fC and 5caC exhibited intranucleobase hydrogen bonding between their formyl or carboxyl oxygens, respectively, and the adjacent cytosine N(4) exocyclic amines. The lesion-specific differences observed in the DDD may be implicated in recognition of 5hmC, 5fC, or 5caC in DNA by TDG. However, they do not correlate with differential excision of 5hmC, 5fC, or 5caC by TDG, which may be mediated by differences in transition states of the enzyme-bound complexes.
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Affiliation(s)
- Marta
W. Szulik
- Department
of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt
Ingram Cancer Center, and Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Pradeep S. Pallan
- Department
of Biochemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt
Ingram Cancer Center, and Center for Structural Biology, School of
Medicine, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Boguslaw Nocek
- Bioscience
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Markus Voehler
- Department
of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt
Ingram Cancer Center, and Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Surajit Banerjee
- Northeastern
Collaborative Access Team and Department of Chemistry and Chemical
Biology, Cornell University, Argonne National
Laboratory, Argonne, Illinois 60439, United
States
| | - Sonja Brooks
- Department
of Biological Sciences, Vanderbilt Institute of Chemical Biology,
and Center for Structural Biology, Vanderbilt
University, Nashville, Tennessee 37235, United States
| | - Andrzej Joachimiak
- Bioscience
Division, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Martin Egli
- Department
of Biochemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt
Ingram Cancer Center, and Center for Structural Biology, School of
Medicine, Vanderbilt University, Nashville, Tennessee 37232, United States
| | - Brandt F. Eichman
- Department
of Biological Sciences, Vanderbilt Institute of Chemical Biology,
and Center for Structural Biology, Vanderbilt
University, Nashville, Tennessee 37235, United States
| | - Michael P. Stone
- Department
of Chemistry, Vanderbilt Institute of Chemical Biology, Vanderbilt
Ingram Cancer Center, and Center for Structural Biology, Vanderbilt University, Nashville, Tennessee 37235, United States,(M.P.S.) Tel.: 615-322-2589; E-mail:
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Rochette PJ, Lacoste S, Therrien JP, Bastien N, Brash DE, Drouin R. Influence of cytosine methylation on ultraviolet-induced cyclobutane pyrimidine dimer formation in genomic DNA. Mutat Res 2009; 665:7-13. [PMID: 19427505 DOI: 10.1016/j.mrfmmm.2009.02.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Revised: 01/25/2009] [Accepted: 02/17/2009] [Indexed: 10/21/2022]
Abstract
The ultraviolet (UV) component of sunlight is the main cause of skin cancer. More than 50% of all non-melanoma skin cancers and >90% of squamous cell carcinomas in the US carry a sunlight-induced mutation in the p53 tumor suppressor gene. These mutations have a strong tendency to occur at methylated cytosines. Ligation-mediated PCR (LMPCR) was used to compare at nucleotide resolution DNA photoproduct formation at dipyrimidine sites either containing or lacking a methylated cytosine. For this purpose, we exploited the fact that the X chromosome is methylated in females only on the inactive X chromosome, and that the FMR1 (fragile-X mental retardation 1) gene is methylated only in fragile-X syndrome male patients. Purified genomic DNA was irradiated with UVC (254nm), UVB (290-320nm) or monochromatic UVB (302 and 313nm) to determine the effect of different wavelengths on cyclobutane pyrimidine dimer (CPD) formation along the X-linked PGK1 (phosphoglycerate kinase 1) and FMR1 genes. We show that constitutive methylation of cytosine increases the frequency of UVB-induced CPD formation by 1.7-fold, confirming that methylation per se is influencing the probability of damage formation. This was true for both UVB sources used, either broadband or monochromatic, but not for UVC. Our data prove unequivocally that following UVB exposure methylated cytosines are significantly more susceptible to CPD formation compared with unmethylated cytosines.
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Affiliation(s)
- Patrick J Rochette
- Division of Pathology, Department of Medical Biology, Université Laval, Québec, QC, Canada
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Abstract
Recent advances in human genome research have resulted in novel approaches for the identification of epigenetic modifications associated with cancer. Modulators of DNA methylation and chromatin structure have a dramatic effect on gene expression, cellular proliferation, differentiation, and apoptosis. Molecular pathways regulating epigenetic events that occur during tumorigenesis have been exploited as new targets for therapeutic intervention. Clinical studies exploring the effectiveness of therapeutic agents targeting DNA methylation and acetylation of histones have yielded promising results. Molecular profiles of epigenetic alterations in cancer cells could allow better stratification of patients who may show responsiveness to specific treatments.
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Affiliation(s)
- Thea Kalebic
- Lung and Upper Aerodigestive Cancer Research Group, Division of Cancer Prevention, National Cancer Institute, Bethesda, Maryland 20892, USA.
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Tsukamoto N, Karasawa M, Maehara T, Okamoto K, Sakai H, Naruse T, Morita K, Tsuchiya J, Omine M. The majority of T lymphocytes are polyclonal during the chronic phase of chronic myelogenous leukemia. Ann Hematol 1996; 72:61-5. [PMID: 8597608 DOI: 10.1007/bf00641309] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
To clarify the extent of cell lineage involvement in chronic myelogenous leukemia (CML), we investigated the bcr gene rearrangement and clonality using the X-chromosome-linked restriction fragment length polymorphism (RFLP) methylation method in T lymphocytes and granulocytes. We examined the granulocyte and T-cell fractions from the peripheral blood of seven female patients with CML during the chronic phase; patients were heterozygous for RFLPs at the phosphoglycerate kinase (PGK) or the hypoxanthine phosphoribosyltransferase (HPRT) gene. RFLP-methylation analysis of granulocytes demonstrated a monoclonal pattern in six of the seven patients and a rearranged bcr gene in all seven patients. In contrast, T lymphocytes exhibited a polyclonal pattern in six cases; in one case, a faint band was observed following methyl-sensitive enzyme cleavage. The bcr gene analysis in T lymphocytes showed the germline in every case. Our results indicate that the majority of T lymphocytes are polyclonal during the chronic phase of CML and confirm previous reports based on glucose-6-phosphate dehydrogenase, cytogenetic, and bcr rearrangement analyses.
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MESH Headings
- Adult
- Biomarkers, Tumor/analysis
- Biomarkers, Tumor/genetics
- Clone Cells/pathology
- Female
- Fusion Proteins, bcr-abl/analysis
- Fusion Proteins, bcr-abl/genetics
- Heterozygote
- Humans
- Hypoxanthine Phosphoribosyltransferase/analysis
- Hypoxanthine Phosphoribosyltransferase/genetics
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/immunology
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology
- Middle Aged
- Neoplasm Proteins/analysis
- Neoplasm Proteins/genetics
- Phosphoglycerate Kinase/analysis
- Phosphoglycerate Kinase/genetics
- Polymorphism, Restriction Fragment Length
- T-Lymphocyte Subsets/pathology
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Affiliation(s)
- N Tsukamoto
- Third Department of Internal Medicine, Gunma University School of Medicine, Maebashi, Gunma, Japan
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Palitti F, Carotti D, Busiello V, Bendicenti A, Strom R, Di Girolamo M. DNA hypomethylation and differentiation in Friend leukemia cell variants. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1216:50-4. [PMID: 8218415 DOI: 10.1016/0167-4781(93)90036-d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The occurrence, upon differentiation, of a transient DNA hypomethylation has been observed in Friend erythroleukemia cells. Treatment with hexamethylenebisacetamide (HMBA) induces within 24 h a 20% hypomethylation of newly synthesized DNA, that is followed by re-methylation before completion of the differentiative process, as measured by the appearance of benzidine-positive cells. We examined a series of mutant clones which continue to grow in the presence of an inducer. Methylcytosine content of DNA was measured by HPLC, after cell labeling with [3H]uridine. We found that one of these continuously growing clones, which was still capable of hemoglobin synthesis, showed the same degree of hypomethylation as the parental one. The re-methylation process did not occur, however, unless erythroid differentiation was reverted by the removal of the inducer. In another clone which had lost the capacity to synthesize hemoglobin, no DNA hypomethylation was detectable. These experiments show that DNA hypomethylation is an early event strictly related to cell differentiation but not to cell growth arrest.
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Affiliation(s)
- F Palitti
- Department of Biochemical Sciences A. Rossi Fanelli, University La Sapienza, Rome, Italy
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Pascale R, Simile MM, Ruggiu ME, Seddaiu MA, Satta G, Sequenza MJ, Daino L, Vannini MG, Lai P, Feo F. Reversal by 5-azacytidine of the S-adenosyl-L-methionine-induced inhibition of the development of putative preneoplastic foci in rat liver carcinogenesis. Cancer Lett 1991; 56:259-65. [PMID: 1708694 DOI: 10.1016/0304-3835(91)90011-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The development of gamma-glutamyltranspeptidase (GGT)-positive foci, in Wistar rats, initiated with diethylnitrosamine and subjected to selection according to 'resistant hepatocyte' protocol, was coupled, 7 weeks after initiation, with liver DNA hypomethylation and with a fall in S-adenosylmethionine/S-adenosylhomocysteine (SAM/SAH) ratio, and in 5-methylthio-adenosine (MTA) content. A 15-day treatment with SAM, started 1 week after selection, caused a dose-dependent decrease in the development of GGT-positive foci, recovery of liver SAM/SAH ratio and MTA level, and liver DNA methylation. A 12-day treatment with 20 mumol/kg per day of 5-azacytidine (AzaC), starting 1 week after selection, enhanced growth of GGT-positive foci, caused strong DNA hypomethylation, and partially counteracted the inhibition of GGT-positive foci growth, without affecting recovery of SAM/SAH ratio and MTA level, induced by SAM. These results suggest a role of DNA methylation in the antipromoting effect of SAM.
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Affiliation(s)
- R Pascale
- Institute of General Pathology, University of Sassari, Italy
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