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Biomolecules Dec 2023Cells maintain a fine-tuned balance of deoxyribonucleoside 5'-triphosphates (dNTPs), a crucial factor in preserving genomic integrity. Any alterations in the nucleotide...
Cells maintain a fine-tuned balance of deoxyribonucleoside 5'-triphosphates (dNTPs), a crucial factor in preserving genomic integrity. Any alterations in the nucleotide pool's composition or chemical modifications to nucleotides before their incorporation into DNA can lead to increased mutation frequency and DNA damage. In addition to the chemical modification of canonical dNTPs, the cellular de novo dNTP metabolism pathways also produce noncanonical dNTPs. To keep their levels low and prevent them from incorporating into the DNA, these noncanonical dNTPs are removed from the dNTP pool by sanitizing enzymes. In this study, we introduce innovative protocols for the high-throughput fluorescence-based quantification of dUTP, 5-methyl-dCTP, and 5-hydroxymethyl-dCTP. To distinguish between noncanonical dNTPs and their canonical counterparts, specific enzymes capable of hydrolyzing either the canonical or noncanonical dNTP analogs are employed. This approach provides a more precise understanding of the composition and noncanonical constituents of dNTP pools, facilitating a deeper comprehension of DNA metabolism and repair. It is also crucial for accurately interpreting mutational patterns generated through the next-generation sequencing of biological samples.
Topics: Deoxyribonucleotides; Deoxycytosine Nucleotides; DNA
PubMed: 38136671
DOI: 10.3390/biom13121801 -
Molecular Biology and Evolution Dec 2023The de novo synthesis of deoxythymidine triphosphate uses several pathways: gram-negative bacteria use deoxycytidine triphosphate deaminase to convert deoxycytidine...
Functional Prokaryotic-Like Deoxycytidine Triphosphate Deaminases and Thymidylate Synthase in Eukaryotic Social Amoebae: Vertical, Endosymbiotic, or Horizontal Gene Transfer?
The de novo synthesis of deoxythymidine triphosphate uses several pathways: gram-negative bacteria use deoxycytidine triphosphate deaminase to convert deoxycytidine triphosphate into deoxyuridine triphosphate, whereas eukaryotes and gram-positive bacteria instead use deoxycytidine monophosphate deaminase to transform deoxycytidine monophosphate to deoxyuridine monophosphate. It is then unusual that in addition to deoxycytidine monophosphate deaminases, the eukaryote Dictyostelium discoideum has 2 deoxycytidine triphosphate deaminases (Dcd1Dicty and Dcd2Dicty). Expression of either DcdDicty can fully rescue the slow growth of an Escherichia coli dcd knockout. Both DcdDicty mitigate the hydroxyurea sensitivity of a Schizosaccharomyces pombe deoxycytidine monophosphate deaminase knockout. Phylogenies show that Dcd1Dicty homologs may have entered the common ancestor of the eukaryotic groups of Amoebozoa, Obazoa, Metamonada, and Discoba through an ancient horizontal gene transfer from a prokaryote or an ancient endosymbiotic gene transfer from a mitochondrion, followed by horizontal gene transfer from Amoebozoa to several other unrelated groups of eukaryotes. In contrast, the Dcd2Dicty homologs were a separate horizontal gene transfer from a prokaryote or a virus into either Amoebozoa or Rhizaria, followed by a horizontal gene transfer between them. ThyXDicty, the D. discoideum thymidylate synthase, another enzyme of the deoxythymidine triphosphate biosynthesis pathway, was suggested previously to be acquired from the ancestral mitochondria or by horizontal gene transfer from alpha-proteobacteria. ThyXDicty can fully rescue the E. coli thymidylate synthase knockout, and we establish that it was obtained by the common ancestor of social amoebae not from mitochondria but from a bacterium. We propose horizontal gene transfer and endosymbiotic gene transfer contributed to the enzyme diversity of the deoxythymidine triphosphate synthesis pathway in most social amoebae, many Amoebozoa, and other eukaryotes.
Topics: DCMP Deaminase; Gene Transfer, Horizontal; Escherichia coli; Amoeba; Thymidylate Synthase; Dictyostelium; Deoxycytidine Monophosphate
PubMed: 38064674
DOI: 10.1093/molbev/msad268 -
Biochemical Pharmacology Dec 2023Ribonucleotide reductase (RR) is a rate-limiting enzyme that facilitates DNA replication and repair by reducing nucleotide diphosphates (NDPs) to deoxyribonucleotide...
Ribonucleotide reductase (RR) is a rate-limiting enzyme that facilitates DNA replication and repair by reducing nucleotide diphosphates (NDPs) to deoxyribonucleotide diphosphates (dNDPs) and is thereby crucial for cell proliferation and cancer development. The E2F family of transcription factors includes key regulators of gene expression involved in cell cycle control. In this study, E2F8 expression was significantly increased in most cancer tissues of lung adenocarcinoma (LUAD) patients and was correlated with the expression of RRM2 through database and clinical samples analysis. The protein expression of E2F8 and RRM2 were positively correlated with tumor-node-metastasis (TNM) pathological stage, and high expression of E2F8 and RRM2 predicted a low 5-year overall survival rate in LUAD patients. Overexpression and knockdown experiments showed that E2F8 was essential for LUAD cell proliferation, DNA synthesis, and cell cycle progression, which were RRM2-dependent. Reporter gene, ChIP-qPCR, and DNA pulldown-Western blot assays indicated that E2F8 activated the transcription of the RRM2 gene by directly binding with the RRM2 promoter in LUAD cells. Previous studies indicated that inhibition of WEE1 kinase can suppress the phosphorylation of CDK1/2 and promote the degradation of RRM2. We further showed here that the combination of E2F8 knockdown with MK-1775, an inhibitor of WEE1 being evaluated in clinical trials, synergistically suppressed proliferation and promoted apoptosis of LUAD cells in vitro and in vivo. Thus, this study reveals a novel role of E2F8 as a proto-oncogenic transcription activator by activating RRM2 expression in LUAD, and targeting both the transcription and degradation mechanisms of RRM2 could produce a synergistic inhibitory effect for LUAD treatment in addition to conventional inhibition of RR enzyme activity.
Topics: Humans; Adenocarcinoma of Lung; Cell Cycle Proteins; Cell Line, Tumor; Cell Proliferation; DNA; DNA Replication; Gene Expression Regulation, Neoplastic; Lung Neoplasms; Protein-Tyrosine Kinases; Repressor Proteins
PubMed: 37863324
DOI: 10.1016/j.bcp.2023.115854 -
Journal of Bacteriology Oct 2023Ribonucleotides frequently contaminate DNA and, if not removed, cause genomic instability. Consequently, all organisms are equipped with RNase H enzymes to remove...
Ribonucleotides frequently contaminate DNA and, if not removed, cause genomic instability. Consequently, all organisms are equipped with RNase H enzymes to remove RNA-DNA hybrids (RDHs). lacking RNase HI () and RNase HII () enzymes, the ∆ ∆ double mutant, accumulates RDHs in its DNA. These RDHs can convert into RNA-containing DNA lesions (R-lesions) of unclear nature that compromise genomic stability. The ∆ double mutant has severe phenotypes, like growth inhibition, replication stress, sensitivity to ultraviolet radiation, SOS induction, increased chromosomal fragmentation, and defects in nucleoid organization. In this study, we found that RNase HI deficiency also alters wild-type levels of DNA supercoiling. Despite these severe chromosomal complications, ∆ double mutant survives, suggesting that dedicated pathways operate to avoid or repair R-lesions. To identify these pathways, we systematically searched for mutants synthetic lethal (colethal) with the defect using an unbiased color screen and a candidate gene approach. We identified both novel and previously reported -colethal and -coinhibited mutants, characterized them, and sorted them into avoidance or repair pathways. These mutants operate in various parts of nucleic acid metabolism, including replication fork progression, R-loop prevention and removal, nucleoid organization, tRNA modification, recombinational repair, and chromosome-dimer resolution, demonstrating the pleiotropic nature of RNase H deficiency. IMPORTANCE Ribonucleotides (rNs) are structurally very similar to deoxyribonucleotides. Consequently, rN contamination of DNA is common and pervasive across all domains of life. Failure to remove rNs from DNA has severe consequences, and all organisms are equipped with RNase H enzymes to remove RNA-DNA hybrids. RNase H deficiency leads to complications in bacteria, yeast, and mouse, and diseases like progressive external ophthalmoplegia (mitochondrial defects in RNASEH1) and Aicardi-Goutières syndrome (defects in RNASEH2) in humans. mutant, deficient in RNases H, has severe chromosomal complications. Despite substantial problems, nearly half of the mutant population survives. We have identified novel and previously confirmed pathways in various parts of nucleic acid metabolism that ensure survival with RNase H deficiency.
Topics: Humans; Animals; Mice; Escherichia coli; Ultraviolet Rays; DNA; Genomic Instability; Ribonuclease H; RNA; Ribonucleotides
PubMed: 37819120
DOI: 10.1128/jb.00280-23 -
Nucleic Acids Research Nov 2023The cellular imbalance between high concentrations of ribonucleotides (NTPs) and low concentrations of deoxyribonucleotides (dNTPs), is challenging for DNA polymerases...
The cellular imbalance between high concentrations of ribonucleotides (NTPs) and low concentrations of deoxyribonucleotides (dNTPs), is challenging for DNA polymerases when building DNA from dNTPs. It is currently believed that DNA polymerases discriminate against NTPs through a steric gate model involving a clash between a tyrosine and the 2'-hydroxyl of the ribonucleotide in the polymerase active site in B-family DNA polymerases. With the help of crystal structures of a B-family polymerase with a UTP or CTP in the active site, molecular dynamics simulations, biochemical assays and yeast genetics, we have identified a mechanism by which the finger domain of the polymerase sense NTPs in the polymerase active site. In contrast to the previously proposed polar filter, our experiments suggest that the amino acid residue in the finger domain senses ribonucleotides by steric hindrance. Furthermore, our results demonstrate that the steric gate in the palm domain and the sensor in the finger domain are both important when discriminating NTPs. Structural comparisons reveal that the sensor residue is conserved among B-family polymerases and we hypothesize that a sensor in the finger domain should be considered in all types of DNA polymerases.
Topics: Catalytic Domain; Crystallography, X-Ray; Deoxyribonucleotides; DNA; DNA Polymerase II; Ribonucleotides; Saccharomyces cerevisiae
PubMed: 37819038
DOI: 10.1093/nar/gkad817 -
Journal of Animal Science Jan 2023Feeding a Saccharomyces cerevisiae fermentation product (SCFP; NutriTek, Diamond V, Cedar Rapids, IA) during periods of metabolic stress is beneficial to the health of...
Impact of a Saccharomyces cerevisiae fermentation product during an intestinal barrier challenge in lactating Holstein cows on ileal microbiota and markers of tissue structure and immunity.
Feeding a Saccharomyces cerevisiae fermentation product (SCFP; NutriTek, Diamond V, Cedar Rapids, IA) during periods of metabolic stress is beneficial to the health of dairy cows partially through its effect on the gut microbiota. Whether SCFP alters the ileal microbiota in lactating cows during intestinal challenges induced by feed restriction (FR) is not known. We used 16S rRNA sequencing to assess if feeding SCFP during FR to induce gut barrier dysfunction alters microbiota profiles in the ileum. The mRNA abundance of key genes associated with tissue structures and immunity was also detected. Multiparous cows (97.1 ± 7.6 days in milk (DIM); n = 7 per treatment) fed a control diet or the control plus 19 g/d NutriTek for 9 wk were subjected to an FR challenge for 5 d, during which they were fed 40% of their ad libitum intake from the 7 d before FR. All cows were slaughtered at the end of FR. DNA extracted from ileal digesta was subjected to PacBio Full-Length 16S rRNA gene sequencing. High-quality amplicon sequence analyses were performed with Targeted Amplicon Diversity Analysis and MicrobiomeAnalyst. Functional analysis was performed and analyzed using PICRUSt and STAMP. Feeding SCFP did not (P > 0.05) alter dry matter intake, milk yield, or milk components during FR. In addition, SCFP supplementation tended (P = 0.07) to increase the relative abundance of Proteobacteria and Bifidobacterium animalis. Compared with controls, feeding SCFP increased the relative abundance of Lactobacillales (P = 0.03). Gluconokinase, oligosaccharide reducing-end xylanase, and 3-hydroxy acid dehydrogenase were among the enzymes overrepresented (P < 0.05) in response to feeding SCFP. Cows fed SCFP had a lower representation of adenosylcobalamin biosynthesis I (early cobalt insertion) and pyrimidine deoxyribonucleotides de novo biosynthesis III (P < 0.05). Subsets of the Firmicutes genus, Bacteroidota phylum, and Treponema genus were correlated with the mRNA abundance of genes associated with ileal integrity (GCNT3, GALNT5, B3GNT3, FN1, ITGA2, LAMB2) and inflammation (AOX1, GPX8, CXCL12, CXCL14, CCL4, SAA3). Our data indicated that the moderate FR induced dysfunction of the ileal microbiome, but feeding SCFP increased the abundance of some beneficial gut probiotic bacteria and other species related to tissue structures and immunity.
Topics: Female; Cattle; Animals; Dietary Supplements; Lactation; Saccharomyces cerevisiae; Fermentation; RNA, Ribosomal, 16S; Diet; Milk; Gastrointestinal Microbiome; RNA, Messenger; Animal Feed; Rumen
PubMed: 37721866
DOI: 10.1093/jas/skad309 -
Frontiers in Cellular and Infection... 2023Maintenance of dNTPs pools in is dependent on both biosynthetic and degradation pathways that together ensure correct cellular homeostasis throughout the cell cycle...
Maintenance of dNTPs pools in is dependent on both biosynthetic and degradation pathways that together ensure correct cellular homeostasis throughout the cell cycle which is essential for the preservation of genomic stability. Both the salvage and pathways participate in the provision of pyrimidine dNTPs while purine dNTPs are made available solely through salvage. In order to identify enzymes involved in degradation here we have characterized the role of a trypanosomal SAMHD1 orthologue denominated TbHD82. Our results show that TbHD82 is a nuclear enzyme in both procyclic and bloodstream forms of . Knockout forms exhibit a hypermutator phenotype, cell cycle perturbations and an activation of the DNA repair response. Furthermore, dNTP quantification of null mutant cells revealed perturbations in nucleotide metabolism with a substantial accumulation of dATP, dCTP and dTTP. We propose that this HD domain-containing protein present in kinetoplastids plays an essential role acting as a sentinel of genomic fidelity by modulating the unnecessary and detrimental accumulation of dNTPs.
Topics: Deoxyribonucleotides; Trypanosoma brucei brucei; SAM Domain and HD Domain-Containing Protein 1; Genomic Instability; Genome, Protozoan; DNA Damage; Cell Cycle
PubMed: 37674581
DOI: 10.3389/fcimb.2023.1241305 -
Drug Design, Development and Therapy 2023To explore the pharmacological effects and mechanisms of Qinghao Biejia decoction (QBD) against non-small-cell lung cancer (NSCLC) based on network pharmacology and to...
Integrating Network Pharmacology and Experimental Validation to Explore the Effects and Mechanisms of Qinghao Biejia Decoction and Its Active Compound Artemisinin B Against Non-Small-Cell Lung Cancer.
PURPOSE
To explore the pharmacological effects and mechanisms of Qinghao Biejia decoction (QBD) against non-small-cell lung cancer (NSCLC) based on network pharmacology and to verify the anticancer effect of artemisinin B (ART B), the active ingredient of QBD, on H1299 cells.
METHODS
Ultra-performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UPLC-QTOF-MS/MS) was applied to explore the chemoprofile of QBD. A zebrafish xenograft model was used to determine the anti-cancer efficacy of QBD. Cell counting kit-8 assay, terminal deoxyribonucleotide transferase-mediated-dUTP nick-end labeling assay; immunofluorescence, and flow cytometry were used to evaluate the in vitro anti-proliferative and pro-apoptotic effects of QBD and ART B on H1299 cells. Subsequently, the related targets and action mechanisms of both QBD and ART B predicted by network pharmacological analyses were experimentally validated by real-time PCR and Western blot assays on H1299 cells.
RESULTS
UPLC-QTOF-MS/MS identified a total of 69 compounds (such as ART B, mangiferin, and artemisinic acid) in QBD. The in vivo data showed that QBD significantly inhibited the growth of H1299 cells in xenograft larval zebrafish from 125 to 500 μg/mL. The in vitro data showed that QBD induced apoptosis of H1299 cells, accompanied by down-regulating the expression of BCL-2 and up-regulating the expression of BIM, PUMA, BAX, c-PARP, γ-H2A.X, c-CASP3, and c-CASP8. Alike QBD, ART B exerted similar anti-proliferative and pro-apoptotic effects on H1299 cells. Moreover, ART B inhibited expressions of , and , and up-regulated expression. Mechanistically, ART B promoted apoptosis of H1299 cells by inhibiting PI3K/Akt signaling pathway.
CONCLUSION
This study revealed the anti-NSCLC efficacy of QBD. ART B, the effective component of QBD, plays an anti-NSCLC role by down-regulating the PI3K-Akt signaling pathway. It suggests that QBD and ART B are promising drug candidates for NSCLC treatment.
Topics: Humans; Animals; Carcinoma, Non-Small-Cell Lung; Artemisia annua; Zebrafish; Network Pharmacology; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Tandem Mass Spectrometry; Lung Neoplasms
PubMed: 37637262
DOI: 10.2147/DDDT.S414098 -
Cells Aug 2023Infectious diseases, particularly Tuberculosis (TB) caused by , pose a significant global health challenge, with 1.6 million reported deaths in 2021, making it the most... (Review)
Review
Infectious diseases, particularly Tuberculosis (TB) caused by , pose a significant global health challenge, with 1.6 million reported deaths in 2021, making it the most fatal disease caused by a single infectious agent. The rise of drug-resistant infectious diseases adds to the urgency of finding effective and safe intervention therapies. Antisense therapy uses antisense oligonucleotides (ASOs) that are short, chemically modified, single-stranded deoxyribonucleotide molecules complementary to their mRNA target. Due to their designed target specificity and inhibition of a disease-causing gene at the mRNA level, antisense therapy has gained interest as a potential therapeutic approach. This type of therapy is currently utilized in numerous diseases, such as cancer and genetic disorders. Currently, there are limited but steadily increasing studies available that report on the use of ASOs as treatment for infectious diseases. This review explores the sustainability of FDA-approved and preclinically tested ASOs as a treatment for infectious diseases and the adaptability of ASOs for chemical modifications resulting in reduced side effects with improved drug delivery; thus, highlighting the potential therapeutic uses of ASOs for treating infectious diseases.
Topics: Humans; Communicable Diseases; Biological Therapy; Mycobacterium tuberculosis; Drug Delivery Systems; Oligonucleotides, Antisense; RNA, Messenger
PubMed: 37626929
DOI: 10.3390/cells12162119 -
Cancer Research Communications Aug 2023Ribonucleotide reductase (RNR) catalyzes the rate-limiting step in the synthesis of deoxyribonucleosides and is required for DNA replication. Multiple types of cancer,...
UNLABELLED
Ribonucleotide reductase (RNR) catalyzes the rate-limiting step in the synthesis of deoxyribonucleosides and is required for DNA replication. Multiple types of cancer, including Ewing sarcoma tumors, are sensitive to RNR inhibitors or a reduction in the levels of either the RRM1 or RRM2 subunits of RNR. However, the polypharmacology and off-target effects of RNR inhibitors have complicated the identification of the mechanisms that regulate sensitivity and resistance to this class of drugs. Consequently, we used a conditional knockout (CRISPR/Cas9) and rescue approach to target RRM1 in Ewing sarcoma cells and identified that loss of the RRM1 protein results in the upregulation of the expression of multiple members of the activator protein-1 (AP-1) transcription factor complex, including c-Jun and c-Fos, and downregulation of c-Myc. Notably, overexpression of c-Jun and c-Fos in Ewing sarcoma cells is sufficient to inhibit cell growth and downregulate the expression of the c-Myc oncogene. We also identified that the upregulation of AP-1 is mediated, in part, by SLFN11, which is a replication stress response protein that is expressed at high levels in Ewing sarcoma. In addition, small-molecule inhibitors of RNR, including gemcitabine, and histone deacetylase inhibitors, which reduce the level of the RRM1 protein, also activate AP-1 signaling and downregulate the level of c-Myc in Ewing sarcoma. Overall, these results provide novel insight into the critical pathways activated by loss of RNR activity and the mechanisms of action of inhibitors of RNR.
SIGNIFICANCE
RNR is the rate-limiting enzyme in the synthesis of deoxyribonucleotides. Although RNR is the target of multiple chemotherapy drugs, polypharmacology and off-target effects have complicated the identification of the precise mechanism of action of these drugs. In this work, using a knockout-rescue approach, we identified that inhibition of RNR upregulates AP-1 signaling and downregulates the level of c-Myc in Ewing sarcoma tumors.
Topics: Humans; Sarcoma, Ewing; Transcription Factor AP-1; Neuroectodermal Tumors, Primitive, Peripheral; Signal Transduction; Proto-Oncogene Proteins c-fos; Ribonucleotide Reductases; Craniocerebral Trauma; DNA Replication; Nuclear Proteins
PubMed: 37599787
DOI: 10.1158/2767-9764.CRC-23-0268