1
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Zhao H, Li J, You Z, Lindsay HD, Yan S. Distinct regulation of ATM signaling by DNA single-strand breaks and APE1. Nat Commun 2024; 15:6517. [PMID: 39112456 PMCID: PMC11306256 DOI: 10.1038/s41467-024-50836-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 07/21/2024] [Indexed: 08/10/2024] Open
Abstract
In response to DNA double-strand breaks or oxidative stress, ATM-dependent DNA damage response (DDR) is activated to maintain genome integrity. However, it remains elusive whether and how DNA single-strand breaks (SSBs) activate ATM. Here, we provide direct evidence in Xenopus egg extracts that ATM-mediated DDR is activated by a defined SSB structure. Our mechanistic studies reveal that APE1 promotes the SSB-induced ATM DDR through APE1 exonuclease activity and ATM recruitment to SSB sites. APE1 protein can form oligomers to activate the ATM DDR in Xenopus egg extracts in the absence of DNA and can directly stimulate ATM kinase activity in vitro. Our findings reveal distinct mechanisms of the ATM-dependent DDR activation by SSBs in eukaryotic systems and identify APE1 as a direct activator of ATM kinase.
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Affiliation(s)
- Haichao Zhao
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC, 28223, USA
| | - Jia Li
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC, 28223, USA
| | - Zhongsheng You
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Howard D Lindsay
- Lancaster Medical School, Faculty of Health and Medicine, Lancaster University, Lancaster, LA1 4YQ, UK
| | - Shan Yan
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC, 28223, USA.
- School of Data Science, University of North Carolina at Charlotte, Charlotte, NC, 28223, USA.
- Center for Biomedical Engineering and Science, University of North Carolina at Charlotte, Charlotte, USA.
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2
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Fleming AM, Tran R, Omaga CA, Manage SAH, Burrows CJ, Conboy JC. Second Harmonic Generation Interrogation of the Endonuclease APE1 Binding Interaction with G-Quadruplex DNA. Anal Chem 2022; 94:15027-15032. [PMID: 36269876 PMCID: PMC9945475 DOI: 10.1021/acs.analchem.2c02951] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The binding interaction between the DNA repair enzyme apurinic/apyrimidinic endonuclease-1 (APE1) with promoter G-quadruplex (G4) folds bearing an abasic site (AP) can serve as a gene regulatory switch during oxidative stress. Prior fluorescence-based analysis in solution suggested APE1 binds the VEGF promoter G4 but whether this interaction was specific or not remained an open question. Second harmonic generation (SHG) was used in this work to measure the noncanonical DNA-protein binding interaction in a label-free assay with high sensitivity to demonstrate the interaction is ordered and specific. The binding of APE1 to the VEGF promoter G4 with AP sites modeled by a tetrahydrofuran analogue produced dissociation constants of ∼100 nM that differed from duplex and single-stranded DNA control studies. The SHG measurements confirmed APE1 binds the VEGF G4 folds in a specific manner resolving a remaining question regarding how this endonuclease with gene regulatory features engages G4 folds. The studies demonstrate the power of SHG to interrogate noncanonical DNA-protein interactions providing a foundational example for the use of this analytical method in future biochemical analyses.
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Affiliation(s)
- Aaron M. Fleming
- 315 S 1400 East, Dept. of Chemistry, University of Utah, Salt Lake City, UT United States, 84112-0850
| | - Renee Tran
- 315 S 1400 East, Dept. of Chemistry, University of Utah, Salt Lake City, UT United States, 84112-0850
| | - Carla A. Omaga
- 315 S 1400 East, Dept. of Chemistry, University of Utah, Salt Lake City, UT United States, 84112-0850
| | - Shereen A. Howpay Manage
- 315 S 1400 East, Dept. of Chemistry, University of Utah, Salt Lake City, UT United States, 84112-0850
| | - Cynthia J. Burrows
- 315 S 1400 East, Dept. of Chemistry, University of Utah, Salt Lake City, UT United States, 84112-0850
| | - John C. Conboy
- 315 S 1400 East, Dept. of Chemistry, University of Utah, Salt Lake City, UT United States, 84112-0850
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3
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Li J, Zhao H, McMahon A, Yan S. APE1 assembles biomolecular condensates to promote the ATR-Chk1 DNA damage response in nucleolus. Nucleic Acids Res 2022; 50:10503-10525. [PMID: 36200829 PMCID: PMC9561277 DOI: 10.1093/nar/gkac853] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 09/14/2022] [Accepted: 10/03/2022] [Indexed: 11/13/2022] Open
Abstract
Multifunctional protein APE1/APEX1/HAP1/Ref-1 (designated as APE1) plays important roles in nuclease-mediated DNA repair and redox regulation in transcription. However, it is unclear how APE1 regulates the DNA damage response (DDR) pathways. Here we show that siRNA-mediated APE1-knockdown or APE1 inhibitor treatment attenuates the ATR–Chk1 DDR under stress conditions in multiple immortalized cell lines. Congruently, APE1 overexpression (APE1-OE) activates the ATR DDR under unperturbed conditions, which is independent of APE1 nuclease and redox functions. Structural and functional analysis reveals a direct requirement of the extreme N-terminal motif within APE1 in the assembly of distinct biomolecular condensates in vitro and DNA/RNA-independent activation of the ATR DDR. Overexpressed APE1 co-localizes with nucleolar NPM1 and assembles biomolecular condensates in nucleoli in cancer but not non-malignant cells, which recruits ATR and activator molecules TopBP1 and ETAA1. APE1 protein can directly activate ATR to phosphorylate its substrate Chk1 in in vitro kinase assays. W119R mutant of APE1 is deficient in nucleolar condensation, and is incapable of activating nucleolar ATR DDR in cells and ATR kinase in vitro. APE1-OE-induced nucleolar ATR DDR activation leads to compromised ribosomal RNA transcription and reduced cell viability. Taken together, we propose distinct mechanisms by which APE1 regulates ATR DDR pathways.
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Affiliation(s)
- Jia Li
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
| | - Haichao Zhao
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
| | - Anne McMahon
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
| | - Shan Yan
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA.,School of Data Science, University of North Carolina at Charlotte, Charlotte, NC 28223, USA.,Center for Biomedical Engineering and Science, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
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4
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Manage SAH, Fleming AM, Chen HN, Burrows CJ. Cysteine Oxidation to Sulfenic Acid in APE1 Aids G-Quadruplex Binding While Compromising DNA Repair. ACS Chem Biol 2022; 17:2583-2594. [PMID: 36037088 PMCID: PMC9931449 DOI: 10.1021/acschembio.2c00511] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Apurinic/apyrimidinic endonuclease-1 (APE1) is a base excision repair (BER) enzyme that is also engaged in transcriptional regulation. Previous work demonstrated that the enzymatic stalling of APE1 on a promoter G-quadruplex (G4) recruits transcription factors during oxidative stress for gene regulation. Also, during oxidative stress, cysteine (Cys) oxidation is a post-translational modification (PTM) that can change a protein's function. The current study provides a quantitative survey of cysteine oxidation to sulfenic acid in APE1 and how this PTM at specific cysteine residues affects the function of APE1 toward the NEIL3 gene promoter G4 bearing an abasic site. Of the seven cysteine residues in APE1, five (C65, C93, C208, C296, and C310) were prone to carbonate radical anion oxidation to yield sulfenic acids that were identified and quantified by mass spectrometry. Accordingly, five Cys-to-serine (Ser) mutants of APE1 were prepared and found to have attenuated levels of endonuclease activity, depending on the position, while KD values generally decreased for G4 binding, indicating greater affinity. These data support the concept that cysteine oxidation to sulfenic acid can result in modified APE1 that enhances G4 binding at the expense of endonuclease activity during oxidative stress. Cysteine oxidation to sulfenic acid residues should be considered as one of the factors that may trigger a switch from base excision repair activity to transcriptional modulation by APE1.
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Affiliation(s)
- Shereen A. Howpay Manage
- Department of Chemistry, University of Utah, 315 S. 1400 E., Salt Lake City, UT 84112-0850, United States
| | - Aaron M. Fleming
- Department of Chemistry, University of Utah, 315 S. 1400 E., Salt Lake City, UT 84112-0850, United States
| | - Hsiao-Nung Chen
- Department of Chemistry, University of Utah, 315 S. 1400 E., Salt Lake City, UT 84112-0850, United States
| | - Cynthia J. Burrows
- Department of Chemistry, University of Utah, 315 S. 1400 E., Salt Lake City, UT 84112-0850, United States
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5
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Baljinnyam T, Sowers ML, Hsu CW, Conrad JW, Herring JL, Hackfeld LC, Sowers LC. Chemical and enzymatic modifications of 5-methylcytosine at the intersection of DNA damage, repair, and epigenetic reprogramming. PLoS One 2022; 17:e0273509. [PMID: 36037209 PMCID: PMC9423628 DOI: 10.1371/journal.pone.0273509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 08/09/2022] [Indexed: 11/19/2022] Open
Abstract
The DNA of all living organisms is persistently damaged by endogenous reactions including deamination and oxidation. Such damage, if not repaired correctly, can result in mutations that drive tumor development. In addition to chemical damage, recent studies have established that DNA bases can be enzymatically modified, generating many of the same modified bases. Irrespective of the mechanism of formation, modified bases can alter DNA-protein interactions and therefore modulate epigenetic control of gene transcription. The simultaneous presence of both chemically and enzymatically modified bases in DNA suggests a potential intersection, or collision, between DNA repair and epigenetic reprogramming. In this paper, we have prepared defined sequence oligonucleotides containing the complete set of oxidized and deaminated bases that could arise from 5-methylcytosine. We have probed these substrates with human glycosylases implicated in DNA repair and epigenetic reprogramming. New observations reported here include: SMUG1 excises 5-carboxyuracil (5caU) when paired with A or G. Both TDG and MBD4 cleave 5-formyluracil and 5caU when mispaired with G. Further, TDG not only removes 5-formylcytosine and 5-carboxycytosine when paired with G, but also when mispaired with A. Surprisingly, 5caU is one of the best substrates for human TDG, SMUG1 and MBD4, and a much better substrate than T. The data presented here introduces some unexpected findings that pose new questions on the interactions between endogenous DNA damage, repair, and epigenetic reprogramming pathways.
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Affiliation(s)
- Tuvshintugs Baljinnyam
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Mark L. Sowers
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas, United States of America
- MD-PhD Combined Degree Program, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Chia Wei Hsu
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas, United States of America
- MD-PhD Combined Degree Program, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - James W. Conrad
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Jason L. Herring
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Linda C. Hackfeld
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Lawrence C. Sowers
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas, United States of America
- * E-mail:
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6
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Sandoval JE, Ramabadran R, Stillson N, Sarah L, Fujimori DG, Goodell MA, Reich N. First-in-Class Allosteric Inhibitors of DNMT3A Disrupt Protein-Protein Interactions and Induce Acute Myeloid Leukemia Cell Differentiation. J Med Chem 2022; 65:10554-10566. [PMID: 35866897 DOI: 10.1021/acs.jmedchem.2c00725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We previously identified two structurally related pyrazolone (compound 1) and pyridazine (compound 2) allosteric inhibitors of DNMT3A through screening of a small chemical library. Here, we show that these compounds bind and disrupt protein-protein interactions (PPIs) at the DNMT3A tetramer interface. This disruption is observed with distinct partner proteins and occurs even when the complexes are acting on DNA, which better reflects the cellular context. Compound 2 induces differentiation of distinct myeloid leukemia cell lines including cells with mutated DNMT3A R882. To date, small molecules targeting DNMT3A are limited to competitive inhibitors of AdoMet or DNA and display extreme toxicity. Our work is the first to identify small molecules with a mechanism of inhibition involving the disruption of PPIs with DNMT3A. Ongoing optimization of compounds 1 and 2 provides a promising basis to induce myeloid differentiation and treatment of diseases that display aberrant PPIs with DNMT3A, such as acute myeloid leukemia.
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Affiliation(s)
- Jonathan E Sandoval
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106-9510, United States
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106-9510, United States
| | - Raghav Ramabadran
- Stem Cells and Regenerative Medicine Center, Baylor College of Medicine, Houston, Texas 77030, United States
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, United States
- Interdepartmental Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, Texas 77030, United States
| | - Nathaniel Stillson
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106-9510, United States
| | - Letitia Sarah
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, California 94158, United States
| | - Danica Galonić Fujimori
- Department of Cellular and Molecular Pharmacology, University of California San Francisco, San Francisco, California 94158, United States
| | - Margaret A Goodell
- Stem Cells and Regenerative Medicine Center, Baylor College of Medicine, Houston, Texas 77030, United States
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, United States
| | - Norbert Reich
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106-9510, United States
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7
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Hsu CW, Conrad JW, Sowers ML, Baljinnyam T, Herring JL, Hackfeld LC, Hatch SS, Sowers LC. A combinatorial system to examine the enzymatic repair of multiply damaged DNA substrates. Nucleic Acids Res 2022; 50:7406-7419. [PMID: 35776119 PMCID: PMC9303388 DOI: 10.1093/nar/gkac530] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 05/18/2022] [Accepted: 06/07/2022] [Indexed: 12/03/2022] Open
Abstract
DNA damage drives genetic mutations that underlie the development of cancer in humans. Multiple pathways have been described in mammalian cells which can repair this damage. However, most work to date has focused upon single lesions in DNA. We present here a combinatorial system which allows assembly of duplexes containing single or multiple types of damage by ligating together six oligonucleotides containing damaged or modified bases. The combinatorial system has dual fluorescent labels allowing examination of both strands simultaneously, in order to study interactions or competition between different DNA repair pathways. Using this system, we demonstrate how repair of oxidative damage in one DNA strand can convert a mispaired T:G deamination intermediate into a T:A mutation. We also demonstrate that slow repair of a T:G mispair, relative to a U:G mispair, by the human methyl-binding domain 4 DNA glycosylase provides a competitive advantage to competing repair pathways, and could explain why CpG dinucleotides are hotspots for C to T mutations in human tumors. Data is also presented that suggests repair of closely spaced lesions in opposing strands can be repaired by a combination of short and long-patch base excision repair and simultaneous repair of multiply damage sites can potentially lead to lethal double strand breaks.
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Affiliation(s)
- Chia Wei Hsu
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA.,MD-PhD Combined Degree Program, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA
| | - James W Conrad
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA
| | - Mark L Sowers
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA.,MD-PhD Combined Degree Program, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA
| | - Tuvshintugs Baljinnyam
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA
| | - Jason L Herring
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA
| | - Linda C Hackfeld
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA
| | - Sandra S Hatch
- Department of Radiation Oncology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA.,Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Lawrence C Sowers
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA.,Department of Internal Medicine, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA
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8
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Hsu CW, Sowers ML, Baljinnyam T, Herring JL, Hackfeld LC, Tang H, Zhang K, Sowers LC. Measurement of deaminated cytosine adducts in DNA using a novel hybrid thymine DNA glycosylase. J Biol Chem 2022; 298:101638. [PMID: 35085553 PMCID: PMC8861164 DOI: 10.1016/j.jbc.2022.101638] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 01/13/2022] [Accepted: 01/17/2022] [Indexed: 01/16/2023] Open
Abstract
The hydrolytic deamination of cytosine and 5-methylcytosine drives many of the transition mutations observed in human cancer. The deamination-induced mutagenic intermediates include either uracil or thymine adducts mispaired with guanine. While a substantial array of methods exist to measure other types of DNA adducts, the cytosine deamination adducts pose unusual analytical problems, and adequate methods to measure them have not yet been developed. We describe here a novel hybrid thymine DNA glycosylase (TDG) that is comprised of a 29-amino acid sequence from human TDG linked to the catalytic domain of a thymine glycosylase found in an archaeal thermophilic bacterium. Using defined-sequence oligonucleotides, we show that hybrid TDG has robust mispair-selective activity against deaminated U:G and T:G mispairs. We have further developed a method for separating glycosylase-released free bases from oligonucleotides and DNA followed by GC-MS/MS quantification. Using this approach, we have measured for the first time the levels of total uracil, U:G, and T:G pairs in calf thymus DNA. The method presented here will allow the measurement of the formation, persistence, and repair of a biologically important class of deaminated cytosine adducts.
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Affiliation(s)
- Chia Wei Hsu
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas, USA,MD-PhD Combined Degree Program, University of Texas Medical Branch, Galveston, Texas, USA
| | - Mark L. Sowers
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas, USA,MD-PhD Combined Degree Program, University of Texas Medical Branch, Galveston, Texas, USA
| | - Tuvshintugs Baljinnyam
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Jason L. Herring
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Linda C. Hackfeld
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Hui Tang
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Kangling Zhang
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Lawrence C. Sowers
- Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas, USA,Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas, USA,For correspondence: Lawrence C. Sowers
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9
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Fleming AM, Manage SAH, Burrows CJ. Binding of AP endonuclease-1 to G-quadruplex DNA depends on the N-terminal domain, Mg 2+ and ionic strength. ACS BIO & MED CHEM AU 2021; 1:44-56. [PMID: 35005714 DOI: 10.1021/acsbiomedchemau.1c00031] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The base excision repair enzyme apurinic/apyrimidinic endonuclease-1 (APE1) is also engaged in transcriptional regulation. APE1 can function in both pathways when the protein binds to a promoter G-quadruplex (G4) bearing an abasic site (modeled with tetrahydrofuran, F) that leads to enzymatic stalling on the non-canonical fold to recruit activating transcription factors. Biochemical and biophysical studies to address APE1's binding and catalytic activity with the vascular endothelial growth factor (VEGF) promoter G4 are lacking, and the present work provides insight on this topic. Herein, the native APE1 was used for cleavage assays, and the catalytically inactive mutant D210A was used for binding assays with double-stranded DNA (dsDNA) versus the native G4 or the G4 with F at various positions, revealing dependencies of the interaction on the cation concentrations K+ and Mg2+ and the N-terminal domain of the protein. Assays in 0, 1, or 10 mM Mg2+ found that dsDNA and G4 substrates required the cation for both binding and catalysis, in which G4 binding increased with [Mg2+]. Studies with 50 versus physiological 140 mM K+ ions showed that F-containing dsDNA was bound and cleaved by APE1; whereas, the G4s with F were poorly cleaved in low salt and not cleaved at all at higher salt while the binding remained robust. Using Δ33 or Δ61 N-terminal truncated APE1 proteins, the binding and cleavage of dsDNA with F was minimally impacted; in contrast, the G4s required the N-terminus for binding and catalysis is nearly abolished without the N-terminus. With this knowledge, we found APE1 could remodel the F-containing VEGF promoter dsDNA→G4 folds in solution. Lastly, the addition of the G4 ligand pyridostatin inhibited APE1 binding and cleavage of F-containing G4s but not dsDNA. The biological and medicinal chemistry implications of the results are discussed.
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Affiliation(s)
- Aaron M Fleming
- Department of Chemistry, University of Utah, 315 S. 1400 E., Salt Lake City, UT 84112-0850, United States
| | - Shereen A Howpay Manage
- Department of Chemistry, University of Utah, 315 S. 1400 E., Salt Lake City, UT 84112-0850, United States
| | - Cynthia J Burrows
- Department of Chemistry, University of Utah, 315 S. 1400 E., Salt Lake City, UT 84112-0850, United States
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10
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Feng B, Niu H, Zhai H, Shen C, Zhang H. In-situ hydrophobic environment triggering reactive fluorescence probe to real-time monitor mitochondrial DNA damage. Front Chem Sci Eng 2021. [DOI: 10.1007/s11705-021-2063-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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11
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Sandoval JE, Reich NO. p53 and TDG are dominant in regulating the activity of the human de novo DNA methyltransferase DNMT3A on nucleosomes. J Biol Chem 2020; 296:100058. [PMID: 33172892 PMCID: PMC7948466 DOI: 10.1074/jbc.ra120.016125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 11/03/2020] [Accepted: 11/10/2020] [Indexed: 11/07/2022] Open
Abstract
DNA methylation and histone tail modifications are interrelated mechanisms involved in a wide range of biological processes, and disruption of this crosstalk is linked to diseases such as acute myeloid leukemia. In addition, DNA methyltransferase 3A (DNMT3A) activity is modulated by several regulatory proteins, including p53 and thymine DNA glycosylase (TDG). However, the relative role of histone tails and regulatory proteins in the simultaneous coordination of DNMT3A activity remains obscure. We observed that DNMT3A binds H3 tails and p53 or TDG at distinct allosteric sites to form DNMT3A–H3 tail-p53 or –TDG multiprotein complexes. Functional characterization of DNMT3A–H3 tail-p53 or –TDG complexes on human-derived synthetic histone H3 tails, mononucleosomes, or polynucleosomes shows p53 and TDG play dominant roles in the modulation of DNMT3A activity. Intriguingly, this dominance occurs even when DNMT3A is actively methylating nucleosome substrates. The activity of histone modifiers is influenced by their ability to sense modifications on histone tails within the same nucleosome or histone tails on neighboring nucleosomes. In contrast, we show here that DNMT3A acts on DNA within a single nucleosome, on nucleosomal DNA within adjacent nucleosomes, and DNA not associated with the DNMT3A–nucleosome complex. Our findings have direct bearing on how the histone code drives changes in DNA methylation and highlight the complex interplay between histone tails, epigenetic enzymes, and modulators of enzymatic activity.
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Affiliation(s)
- Jonathan E Sandoval
- Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California, USA
| | - Norbert O Reich
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California, USA.
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12
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Healing E, Charlier CF, Meira LB, Elliott RM. A panel of colorimetric assays to measure enzymatic activity in the base excision DNA repair pathway. Nucleic Acids Res 2019; 47:e61. [PMID: 30869144 PMCID: PMC6582407 DOI: 10.1093/nar/gkz171] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 02/13/2019] [Accepted: 03/07/2019] [Indexed: 12/12/2022] Open
Abstract
DNA repair is essential for the maintenance of genomic integrity, and evidence suggest that inter-individual variation in DNA repair efficiency may contribute to disease risk. However, robust assays suitable for quantitative determination of DNA repair capacity in large cohort and clinical trials are needed to evaluate these apparent associations fully. We describe here a set of microplate-based oligonucleotide assays for high-throughput, non-radioactive and quantitative determination of repair enzyme activity at individual steps and over multiple steps of the DNA base excision repair pathway. The assays are highly sensitive: using HepG2 nuclear extract, enzyme activities were quantifiable at concentrations of 0.0002 to 0.181 μg per reaction, depending on the enzyme being measured. Assay coefficients of variation are comparable with other microplate-based assays. The assay format requires no specialist equipment and has the potential to be extended for analysis of a wide range of DNA repair enzyme activities. As such, these assays hold considerable promise for gaining new mechanistic insights into how DNA repair is related to individual genetics, disease status or progression and other environmental factors and investigating whether DNA repair activities can be used a biomarker of disease risk.
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Affiliation(s)
- Eleanor Healing
- Department of Nutritional Sciences, University of Surrey, Guildford, Surrey GU2 7XH, UK
| | - Clara F Charlier
- Department of Clinical and Experimental Medicine, University of Surrey, Guildford, Surrey GU2 7XH, UK
| | - Lisiane B Meira
- Department of Clinical and Experimental Medicine, University of Surrey, Guildford, Surrey GU2 7XH, UK
| | - Ruan M Elliott
- Department of Nutritional Sciences, University of Surrey, Guildford, Surrey GU2 7XH, UK
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Feng B, Wang K, Yang Y, Wang G, Zhang H, Liu Y, Jiang K. Ultrasensitive recognition of AP sites in DNA at the single-cell level: one molecular rotor sequentially self-regulated to form multiple different stable conformations. Chem Sci 2019; 10:10373-10380. [PMID: 32110326 PMCID: PMC6988597 DOI: 10.1039/c9sc04140k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 09/20/2019] [Indexed: 01/22/2023] Open
Abstract
Molecular rotors self-regulate their conformations to emit different ultrasensitive recognition signals for AP sites in DNA at the single-cell level.
The AP site is a primary form of DNA damage. Its presence alters the genetic structure and eventually causes malignant diseases. AP sites generally present a high-speed dynamic change in the DNA sequence. Thus, precisely recognizing AP sites is difficult, especially at the single-cell level. To address this issue, we provide a broad-spectrum strategy to design a group of molecular rotors, that is, a series of nonfluorescent 2-(4-vinylbenzylidene)malononitrile derivatives (BMN-Fluors), which constantly display molecular rotation in a free state. Interestingly, after activating the relevant specific-recognition reaction (i.e., hydrolysis reaction of benzylidenemalononitrile) only in the AP-site cavity within a short time (approximately 300 s), each of these molecules can be fixed into this cavity and can sequentially self-regulate to form different stable conformations in accordance with the cavity size. The different stable conformations possess various HOMO–LUMO energy gaps in their excited state. This condition enables the AP site to emit different fluorescence signals at various wavelengths. Given the different self-regulation abilities of the conformations, the series of molecules, BMN-Fluors, can emit different types of signals, including an “OFF–ON” single-channel signal, a “ratio” double-channel signal, and even a precise multichannel signal. Among the BMN-Fluors derivatives, d1-BMN can sequentially self-regulate to form five stable conformations, thereby resulting in the emission of a five-channel signal for different AP sites in situ. Thus, d1-BMN can be used as a probe to ultrasensitively recognize the AP site with precise fluorescent signals at the single-cell level. This design strategy can be generalized to develop additional single-channel to multichannel signal probes to recognize other specific sites in DNA sequences in living organisms.
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Affiliation(s)
- Beidou Feng
- Henan Key Laboratory of Green Chemical Media and Reactions , Ministry of Education , Key Laboratory of Green Chemical Media and Reactions; Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals , Henan Key Laboratory of Organic Functional Molecules and Drug Innovation , School of Chemistry and Chemical Engineering , School of Environment , College of Physics and Materials Science , Henan Normal University , Xinxiang 453007 , China .
| | - Kui Wang
- Henan Key Laboratory of Green Chemical Media and Reactions , Ministry of Education , Key Laboratory of Green Chemical Media and Reactions; Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals , Henan Key Laboratory of Organic Functional Molecules and Drug Innovation , School of Chemistry and Chemical Engineering , School of Environment , College of Physics and Materials Science , Henan Normal University , Xinxiang 453007 , China .
| | - Yonggang Yang
- Henan Key Laboratory of Green Chemical Media and Reactions , Ministry of Education , Key Laboratory of Green Chemical Media and Reactions; Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals , Henan Key Laboratory of Organic Functional Molecules and Drug Innovation , School of Chemistry and Chemical Engineering , School of Environment , College of Physics and Materials Science , Henan Normal University , Xinxiang 453007 , China .
| | - Ge Wang
- Xinxiang Medical University , Xinxiang 453000 , P. R. China
| | - Hua Zhang
- Henan Key Laboratory of Green Chemical Media and Reactions , Ministry of Education , Key Laboratory of Green Chemical Media and Reactions; Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals , Henan Key Laboratory of Organic Functional Molecules and Drug Innovation , School of Chemistry and Chemical Engineering , School of Environment , College of Physics and Materials Science , Henan Normal University , Xinxiang 453007 , China .
| | - Yufang Liu
- Henan Key Laboratory of Green Chemical Media and Reactions , Ministry of Education , Key Laboratory of Green Chemical Media and Reactions; Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals , Henan Key Laboratory of Organic Functional Molecules and Drug Innovation , School of Chemistry and Chemical Engineering , School of Environment , College of Physics and Materials Science , Henan Normal University , Xinxiang 453007 , China .
| | - Kai Jiang
- Henan Key Laboratory of Green Chemical Media and Reactions , Ministry of Education , Key Laboratory of Green Chemical Media and Reactions; Collaborative Innovation Center of Henan Province for Green Manufacturing of Fine Chemicals , Henan Key Laboratory of Organic Functional Molecules and Drug Innovation , School of Chemistry and Chemical Engineering , School of Environment , College of Physics and Materials Science , Henan Normal University , Xinxiang 453007 , China .
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14
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Sandoval JE, Huang YH, Muise A, Goodell MA, Reich NO. Mutations in the DNMT3A DNA methyltransferase in acute myeloid leukemia patients cause both loss and gain of function and differential regulation by protein partners. J Biol Chem 2019; 294:4898-4910. [PMID: 30705090 DOI: 10.1074/jbc.ra118.006795] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 01/24/2019] [Indexed: 01/08/2023] Open
Abstract
Eukaryotic DNA methylation prevents genomic instability by regulating the expression of oncogenes and tumor-suppressor genes. The negative effects of dysregulated DNA methylation are highlighted by a strong correlation between mutations in the de novo DNA methyltransferase gene DNA methyltransferase 3α (DNMT3A) and poor prognoses among acute myeloid leukemia (AML) patients. We show here that clinically observed DNMT3A mutations dramatically alter enzymatic activity, including mutations that lead to 6-fold hypermethylation and 3-fold hypomethylation of the human cyclin-dependent kinase inhibitor 2B (CDKN2B or p15) gene promoter. Our results provide insights into the clinically observed heterogeneity of p15 methylation in AML. Cytogenetically normal AML (CN-AML) constitutes 40-50% of all AML cases and is the most epigenetically diverse AML subtype with pronounced changes in non-CpG DNA methylation. We identified a subset of DNMT3A mutations that enhance the enzyme's ability to perform non-CpG methylation by 2-8-fold. Many of these mutations mapped to DNMT3A regions known to interact with proteins that themselves contribute to AML, such as thymine DNA glycosylase (TDG). Using functional mapping of TDG-DNMT3A interactions, we provide evidence that TDG and DNMT3-like (DNMT3L) bind distinct regions of DNMT3A. Furthermore, DNMT3A mutations caused diverse changes in the ability of TDG and DNMT3L to affect DNMT3A function. Cell-based studies of one of these DNMT3A mutations (S714C) replicated the enzymatic studies and revealed that it causes dramatic losses of genome-wide methylation. In summary, mutations in DNMT3A lead to diverse levels of activity, interactions with epigenetic machinery components and cellular changes.
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Affiliation(s)
- Jonathan E Sandoval
- From the Departments of Chemistry and Biochemistry and.,Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106-9510 and
| | - Yung-Hsin Huang
- the Program in Developmental Biology.,Stem Cells and Regenerative Medicine Center.,Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, Texas 77030
| | - Abigail Muise
- Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106-9510 and
| | - Margaret A Goodell
- the Program in Developmental Biology.,Stem Cells and Regenerative Medicine Center.,Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, Texas 77030
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15
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Barbado C, Córdoba-Cañero D, Ariza RR, Roldán-Arjona T. Nonenzymatic release of N7-methylguanine channels repair of abasic sites into an AP endonuclease-independent pathway in Arabidopsis. Proc Natl Acad Sci U S A 2018; 115:E916-E924. [PMID: 29339505 PMCID: PMC5798382 DOI: 10.1073/pnas.1719497115] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Abasic (apurinic/apyrimidinic, AP) sites in DNA arise from spontaneous base loss or by enzymatic removal during base excision repair. It is commonly accepted that both classes of AP site have analogous biochemical properties and are equivalent substrates for AP endonucleases and AP lyases, although the relative roles of these two types of enzymes are not well understood. We provide here genetic and biochemical evidence that, in Arabidopsis, AP sites generated by spontaneous loss of N7-methylguanine (N7-meG) are exclusively repaired through an AP endonuclease-independent pathway initiated by FPG, a bifunctional DNA glycosylase with AP lyase activity. Abasic site incision catalyzed by FPG generates a single-nucleotide gap with a 3'-phosphate terminus that is processed by the DNA 3'-phosphatase ZDP before repair is completed. We further show that the major AP endonuclease in Arabidopsis (ARP) incises AP sites generated by enzymatic N7-meG excision but, unexpectedly, not those resulting from spontaneous N7-meG loss. These findings, which reveal previously undetected differences between products of enzymatic and nonenzymatic base release, may shed light on the evolution and biological roles of AP endonucleases and AP lyases.
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Affiliation(s)
- Casimiro Barbado
- Maimónides Biomedical Research Institute of Córdoba, 14004 Córdoba, Spain
- Department of Genetics, University of Córdoba, 14071 Córdoba, Spain
- Reina Sofia University Hospital, 14004 Córdoba, Spain
| | - Dolores Córdoba-Cañero
- Maimónides Biomedical Research Institute of Córdoba, 14004 Córdoba, Spain
- Department of Genetics, University of Córdoba, 14071 Córdoba, Spain
- Reina Sofia University Hospital, 14004 Córdoba, Spain
| | - Rafael R Ariza
- Maimónides Biomedical Research Institute of Córdoba, 14004 Córdoba, Spain;
- Department of Genetics, University of Córdoba, 14071 Córdoba, Spain
- Reina Sofia University Hospital, 14004 Córdoba, Spain
| | - Teresa Roldán-Arjona
- Maimónides Biomedical Research Institute of Córdoba, 14004 Córdoba, Spain;
- Department of Genetics, University of Córdoba, 14071 Córdoba, Spain
- Reina Sofia University Hospital, 14004 Córdoba, Spain
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