-
Cell Metabolism Apr 2019Mice deficient for SIRT6 exhibit a severely shortened lifespan, growth retardation, and highly elevated LINE1 (L1) activity. Here we report that SIRT6-deficient cells...
Mice deficient for SIRT6 exhibit a severely shortened lifespan, growth retardation, and highly elevated LINE1 (L1) activity. Here we report that SIRT6-deficient cells and tissues accumulate abundant cytoplasmic L1 cDNA, which triggers strong type I interferon response via activation of cGAS. Remarkably, nucleoside reverse-transcriptase inhibitors (NRTIs), which inhibit L1 retrotransposition, significantly improved health and lifespan of SIRT6 knockout mice and completely rescued type I interferon response. In tissue culture, inhibition of L1 with siRNA or NRTIs abrogated type I interferon response, in addition to a significant reduction of DNA damage markers. These results indicate that L1 activation contributes to the pathologies of SIRT6 knockout mice. Similarly, L1 transcription, cytoplasmic cDNA copy number, and type I interferons were elevated in the wild-type aged mice. As sterile inflammation is a hallmark of aging, we propose that modulating L1 activity may be an important strategy for attenuating age-related pathologies.
Topics: Age Factors; Animals; Dideoxynucleotides; Female; Inflammation; Male; Mice; Mice, Inbred Strains; Mice, Knockout; RNA-Binding Proteins; Sirtuins; Stavudine; Thymine Nucleotides; Zidovudine
PubMed: 30853213
DOI: 10.1016/j.cmet.2019.02.014 -
Annual Review of Nutrition Aug 2018Despite unequivocal evidence that folate deficiency increases risk for human pathologies, and that folic acid intake among women of childbearing age markedly decreases... (Review)
Review
Despite unequivocal evidence that folate deficiency increases risk for human pathologies, and that folic acid intake among women of childbearing age markedly decreases risk for birth defects, definitive evidence for a causal biochemical pathway linking folate to disease and birth defect etiology remains elusive. The de novo and salvage pathways for thymidylate synthesis translocate to the nucleus of mammalian cells during S- and G2/M-phases of the cell cycle and associate with the DNA replication and repair machinery, which limits uracil misincorporation into DNA and genome instability. There is increasing evidence that impairments in nuclear de novo thymidylate synthesis occur in many pathologies resulting from impairments in one-carbon metabolism. Understanding the roles and regulation of nuclear de novo thymidylate synthesis and its relationship to genome stability will increase our understanding of the fundamental mechanisms underlying folate- and vitamin B-associated pathologies.
Topics: Animals; Cell Cycle; Cell Nucleus; Folic Acid; Gene Expression Regulation; Humans; Thymidine Monophosphate
PubMed: 30130467
DOI: 10.1146/annurev-nutr-071714-034441 -
Science (New York, N.Y.) Apr 2021Mutations in the or tumor suppressor genes predispose individuals to breast and ovarian cancer. In the clinic, these cancers are treated with inhibitors that target...
Mutations in the or tumor suppressor genes predispose individuals to breast and ovarian cancer. In the clinic, these cancers are treated with inhibitors that target poly(ADP-ribose) polymerase (PARP). We show that inhibition of DNPH1, a protein that eliminates cytotoxic nucleotide 5-hydroxymethyl-deoxyuridine (hmdU) monophosphate, potentiates the sensitivity of -deficient cells to PARP inhibitors (PARPi). Synthetic lethality was mediated by the action of SMUG1 glycosylase on genomic hmdU, leading to PARP trapping, replication fork collapse, DNA break formation, and apoptosis. -deficient cells that acquired resistance to PARPi were resensitized by treatment with hmdU and DNPH1 inhibition. Because genomic hmdU is a key determinant of PARPi sensitivity, targeting DNPH1 provides a promising strategy for the hypersensitization of -deficient cancers to PARPi therapy.
Topics: Antineoplastic Agents; Apoptosis; CRISPR-Cas Systems; Cell Line, Tumor; DNA Breaks, Double-Stranded; DNA Replication; DNA, Neoplasm; Deoxycytidine Monophosphate; Deoxyuracil Nucleotides; Drug Resistance, Neoplasm; Genes, BRCA1; Humans; Hydrolysis; N-Glycosyl Hydrolases; Phthalazines; Piperazines; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Proto-Oncogene Proteins; Synthetic Lethal Mutations; Thymidine; Uracil-DNA Glycosidase
PubMed: 33833118
DOI: 10.1126/science.abb4542 -
Journal of Molecular Histology Jun 2018Measuring the mean duration of synthesis-phase (T) and of the total cell-cycle (T) within progenitor cell populations can provide important insights into the biology...
Measuring the mean duration of synthesis-phase (T) and of the total cell-cycle (T) within progenitor cell populations can provide important insights into the biology governing these cells. Rather than a passive process that shows little variability across cellular contexts, the cell-cycle is instead highly regulated. For example, in the rodent forebrain, T is selectively lengthened in radial glial progenitor cells undergoing symmetric versus asymmetric division. This lengthening is thought to minimize the potential for copying errors that can occur during DNA replication. Manipulating cell-cycle duration can also affect cell fate, demonstrating that in certain circumstances cell-cycle duration is an instructive process. Currently, cell-cycle length is typically measured using either cumulative labeling with a single thymidine analogue, or via dual thymidine analogue labeling approaches. However, these methods are often time-consuming and inefficient. Here, using the embryonic mouse cerebral cortex as a model system, we describe a simplified dual thymidine analogue protocol using BrdU and EdU that can be used to measure T and T. The advantage of this protocol over cumulative labeling approaches is that only a single time-point is required for measurement. An additional benefit of this protocol over existing dual-analog approaches (CldU/IdU) is the antibody-free detection of EdU and the acid-free detection of BrdU, processes allowing for the parallel use of specific antibodies so as to measure the cell-cycle in immunologically defined cellular subpopulations.
Topics: Animals; Antibodies; Bromodeoxyuridine; Cell Cycle; Cerebral Cortex; Deoxyuracil Nucleotides; Mice; Staining and Labeling; Stem Cells; Time Factors
PubMed: 29445897
DOI: 10.1007/s10735-018-9761-8 -
FASEB Journal : Official Publication of... Jan 2017
Review
Topics: Animals; DNA Damage; DNA Repair Enzymes; Deoxyribonucleotides; Escherichia coli; Escherichia coli Proteins; Humans; Mutagenesis; Neoplasms; Oxidation-Reduction; Phosphoric Monoester Hydrolases; Pyrophosphatases
PubMed: 27729413
DOI: 10.1096/fj.201601100 -
Molecules (Basel, Switzerland) Aug 2022Rhamnose-associated molecules are attracting attention because they are present in bacteria but not mammals, making them potentially useful as antibacterial agents.... (Review)
Review
Rhamnose-associated molecules are attracting attention because they are present in bacteria but not mammals, making them potentially useful as antibacterial agents. Additionally, they are also valuable for tumor immunotherapy. Thus, studies on the functions and biosynthetic pathways of rhamnose-containing compounds are in progress. In this paper, studies on the biosynthetic pathways of three rhamnose donors, i.e., deoxythymidinediphosphate-L-rhamnose (dTDP-Rha), uridine diphosphate-rhamnose (UDP-Rha), and guanosine diphosphate rhamnose (GDP-Rha), are firstly reviewed, together with the functions and crystal structures of those associated enzymes. Among them, dTDP-Rha is the most common rhamnose donor, and four enzymes, including glucose-1-phosphate thymidylyltransferase RmlA, dTDP-Glc-4,6-dehydratase RmlB, dTDP-4-keto-6-deoxy-Glc-3,5-epimerase RmlC, and dTDP-4-keto-Rha reductase RmlD, are involved in its biosynthesis. Secondly, several known rhamnosyltransferases from , , , , and are discussed. In these studies, however, the functions of rhamnosyltransferases were verified by employing gene knockout and radiolabeled substrates, which were almost impossible to obtain and characterize the products of enzymatic reactions. Finally, the application of rhamnose-containing compounds in disease treatments is briefly described.
Topics: Biosynthetic Pathways; Racemases and Epimerases; Rhamnose; Thymine Nucleotides; Uridine Diphosphate
PubMed: 36014553
DOI: 10.3390/molecules27165315 -
Viruses Mar 2020Deoxynucleoside triphosphate (dNTP) molecules are essential for the replication and maintenance of genomic information in both cells and a variety of viral pathogens.... (Review)
Review
Deoxynucleoside triphosphate (dNTP) molecules are essential for the replication and maintenance of genomic information in both cells and a variety of viral pathogens. While the process of dNTP biosynthesis by cellular enzymes, such as ribonucleotide reductase (RNR) and thymidine kinase (TK), has been extensively investigated, a negative regulatory mechanism of dNTP pools was recently found to involve sterile alpha motif (SAM) domain and histidine-aspartate (HD) domain-containing protein 1, SAMHD1. When active, dNTP triphosphohydrolase activity of SAMHD1 degrades dNTPs into their 2'-deoxynucleoside (dN) and triphosphate subparts, steadily depleting intercellular dNTP pools. The differential expression levels and activation states of SAMHD1 in various cell types contributes to unique dNTP pools that either aid (i.e., dividing T cells) or restrict (i.e., nondividing macrophages) viral replication that consumes cellular dNTPs. Genetic mutations in SAMHD1 induce a rare inflammatory encephalopathy called Aicardi-Goutières syndrome (AGS), which phenotypically resembles viral infection. Recent publications have identified diverse roles for SAMHD1 in double-stranded break repair, genome stability, and the replication stress response through interferon signaling. Finally, a series of SAMHD1 mutations were also reported in various cancer cell types while why SAMHD1 is mutated in these cancer cells remains to investigated. Here, we reviewed a series of studies that have begun illuminating the highly diverse roles of SAMHD1 in virology, immunology, and cancer biology.
Topics: Autoimmune Diseases of the Nervous System; DNA Repair; Deoxyribonucleotides; Humans; Immunity, Innate; Mutation; Neoplasms; Nervous System Malformations; Protein Domains; Protein Processing, Post-Translational; SAM Domain and HD Domain-Containing Protein 1; Virus Diseases; Virus Replication
PubMed: 32244340
DOI: 10.3390/v12040382 -
Molecules (Basel, Switzerland) Nov 2019Dinucleoside 5',5'-polyphosphates (DNPs) are endogenous substances that play important intra- and extracellular roles in various biological processes, such as cell... (Review)
Review
Dinucleoside 5',5'-polyphosphates (DNPs) are endogenous substances that play important intra- and extracellular roles in various biological processes, such as cell proliferation, regulation of enzymes, neurotransmission, platelet disaggregation and modulation of vascular tone. Various methodologies have been developed over the past fifty years to access these compounds, involving enzymatic processes or chemical procedures based either on P(III) or P(V) chemistry. Both solution-phase and solid-support strategies have been developed and are reported here. Recently, green chemistry approaches have emerged, offering attracting alternatives. This review outlines the main synthetic pathways for the preparation of dinucleoside 5',5'-polyphosphates, focusing on pharmacologically relevant compounds, and highlighting recent advances.
Topics: Deoxycytosine Nucleotides; Dinucleoside Phosphates; Dry Eye Syndromes; Green Chemistry Technology; Humans; Ophthalmic Solutions; Phosphorylation; Polyphosphates; Purinergic P2Y Receptor Agonists; Receptors, Purinergic; Uracil Nucleotides; Uridine
PubMed: 31783537
DOI: 10.3390/molecules24234334 -
Molecular Aspects of Medicine Feb 2017Thymidylate (dTMP) biosynthesis plays an essential and exclusive function in DNA synthesis and proper cell division, and therefore has been an attractive therapeutic... (Review)
Review
Thymidylate (dTMP) biosynthesis plays an essential and exclusive function in DNA synthesis and proper cell division, and therefore has been an attractive therapeutic target. Folate analogs, known as antifolates, and nucleotide analogs that inhibit the enzymatic action of the de novo thymidylate biosynthesis pathway and are commonly used in cancer treatment. In this review, we examine the mechanisms by which the antifolate 5-fluorouracil, as well as other dTMP synthesis inhibitors, function in cancer treatment in light of emerging evidence that dTMP synthesis occurs in the nucleus. Nuclear localization of the de novo dTMP synthesis pathway requires modification of the pathway enzymes by the small ubiquitin-like modifier (SUMO) protein. SUMOylation is required for nuclear localization of the de novo dTMP biosynthesis pathway, and disruption in the SUMO pathway inhibits cell proliferation in several cancer models. We summarize evidence that the nuclear localization of the dTMP biosynthesis pathway is a critical factor in the efficacy of antifolate-based therapies that target dTMP synthesis.
Topics: Animals; Cell Nucleus; Drug Resistance, Neoplasm; Fluorouracil; Humans; Neoplasms; Sumoylation; Thymidine Monophosphate
PubMed: 27876557
DOI: 10.1016/j.mam.2016.11.005 -
FASEB Journal : Official Publication of... Sep 2014For >35 yr, we have known that the accuracy of DNA replication is controlled in large part by the relative concentrations of the 4 canonical deoxyribonucleoside... (Review)
Review
For >35 yr, we have known that the accuracy of DNA replication is controlled in large part by the relative concentrations of the 4 canonical deoxyribonucleoside 5'-triphosphates (dNTPs) at the replisome. Since this field was last reviewed, ∼8 yr ago, there has been increased understanding of the mutagenic pathways as they occur in living cells. At the same time, aspects of deoxyribonucleotide metabolism have been shown to be critically involved in processes as diverse as cell cycle control, protooncogene expression, cellular defense against HIV infection, replication rate control, telomere length control, and mitochondrial function. Evidence supports a relationship between dNTP pools and microsatellite repeat instability. Relationships between dNTP synthesis and breakdown in controlling steady-state pools have become better defined. In addition, new experimental approaches have allowed definitive analysis of mutational pathways induced by dNTP pool abnormalities, both in Escherichia coli and in yeast. Finally, ribonucleoside triphosphate (rNTP) pools have been shown to be critical determinants of DNA replication fidelity. These developments are discussed in this review article.
Topics: Animals; DNA Replication; Deoxyribonucleotides; Gene Expression Regulation; Humans; Metabolic Networks and Pathways; Mutagenesis
PubMed: 24928192
DOI: 10.1096/fj.14-251249