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The ISME Journal Jan 2024Viruses are a major control on populations of microbes. Often, their virulence is examined in controlled laboratory conditions. Yet, in nature, environmental conditions...
Viruses are a major control on populations of microbes. Often, their virulence is examined in controlled laboratory conditions. Yet, in nature, environmental conditions lead to changes in host physiology and fitness that may impart both costs and benefits on viral success. Phosphorus (P) is a major abiotic control on the marine cyanobacterium Synechococcus. Some viruses infecting Synechococcus have acquired, from their host, a gene encoding a P substrate binding protein (PstS), thought to improve virus replication under phosphate starvation. Yet, pstS is uncommon among cyanobacterial viruses. Thus, we asked how infections with viruses lacking PstS are affected by P scarcity. We show that the production of infectious virus particles of such viruses is reduced in low P conditions. However, this reduction in progeny is not caused by impaired phage genome replication, thought to be a major sink for cellular phosphate. Instead, transcriptomic analysis showed that under low P conditions, a PstS-lacking cyanophage increased the expression of a specific gene set that included mazG, hli2, and gp43 encoding a pyrophosphatase, a high-light inducible protein and DNA polymerase, respectively. Moreover, several of the upregulated genes were controlled by the host's phoBR two-component system. We hypothesize that recycling and polymerization of nucleotides liberates free phosphate and thus allows viral morphogenesis, albeit at lower rates than when phosphate is replete or when phages encode pstS. Altogether, our data show how phage genomes, lacking obvious P-stress-related genes, have evolved to exploit their host's environmental sensing mechanisms to coordinate their own gene expression in response to resource limitation.
Topics: Synechococcus; Bacteriophages; Phosphates; Phosphorus; Carrier Proteins
PubMed: 38431846
DOI: 10.1093/ismejo/wrae032 -
Journal of Evolutionary Biology Mar 2024Mutator alleles, which confer increased mutation rates, are known to spontaneously emerge and "hitchhike" to fixation in evolving asexual populations. Theory predicts...
Mutator alleles, which confer increased mutation rates, are known to spontaneously emerge and "hitchhike" to fixation in evolving asexual populations. Theory predicts that in an evolving asexual mutator population, a second mutator allele may spontaneously arise and hitchhike to fixation. Here, we describe an empirical test of the hypothesis of repeated hitchhiking. The starting population was a clonal strain of mutL-Escherichia coli whose mutation rate was 100-fold higher than wild type. We exposed the mutL- strain to a series of three antibiotics in increasing order of selective strength: fosfomycin, rifampicin, and streptomycin. Two independent replicates of the experiment were performed. As predicted, elevated mutation rates and enrichment for multilocus mutators (which bear more than one mutator allele) were observed in the end point populations of both experiments. DNA sequencing revealed an identical spontaneous 1-bp insertion in the mutator gene mutT in both end point populations. In the multilocus mutators, the causal relationship between the mutT- mutations and the increase in mutation rate was supported with mutT+ plasmid complementation tests. Surprisingly, when the experiment was repeated with the antibiotics deployed in decreasing order of selective strength, enrichment for multilocus mutators was not observed. Our data support the likelihood that the mutT- mutations rose to fixation in both populations, consistent with the hypothesis of repeated mutator hitchhiking. The escalation of mutation rates in asexual populations is relevant to multiple biological scenarios, including antibiotic resistance, host-pathogen interactions, and carcinogenesis.
Topics: Genotype; Anti-Bacterial Agents; Mutation; Mutation Rate; Escherichia coli; Pyrophosphatases; Escherichia coli Proteins
PubMed: 38367184
DOI: 10.1093/jeb/voae007 -
Nucleic Acids Research Apr 2024CtIP initiates DNA end resection and mediates homologous recombination (HR) repair. However, the underlying mechanisms of CtIP regulation and how the control of its...
CtIP initiates DNA end resection and mediates homologous recombination (HR) repair. However, the underlying mechanisms of CtIP regulation and how the control of its regulation affects DNA repair remain incompletely characterized. In this study, NUDT16 loss decreases CtIP protein levels and impairs CtIP recruitment to double-strand breaks (DSBs). Furthermore, overexpression of a catalytically inactive NUDT16 mutant is unable to rescue decreased CtIP protein and impaired CtIP recruitment to DSBs. In addition, we identified a novel posttranslational modification of CtIP by ADP-ribosylation that is targeted by a PAR-binding E3 ubiquitin ligase, RNF146, leading to CtIP ubiquitination and degradation. These data suggest that the hydrolase activity of NUDT16 plays a major role in controlling CtIP protein levels. Notably, ADP-ribosylation of CtIP is required for its interaction with NUDT16, its localization at DSBs, and for HR repair. Interestingly, NUDT16 can also be ADP-ribosylated. The ADP-ribosylated NUDT16 is critical for CtIP protein stability, CtIP recruitment to DSBs, and HR repair in response to DNA damage. In summary, we demonstrate that NUDT16 and its PARylation regulate CtIP stability and CtIP recruitment to DSBs, providing new insights into our understanding of the regulation of CtIP-mediated DNA end resection in the HR repair pathway.
Topics: Humans; ADP-Ribosylation; Carrier Proteins; DNA Breaks, Double-Stranded; Endodeoxyribonucleases; HEK293 Cells; Nuclear Proteins; Protein Processing, Post-Translational; Pyrophosphatases; Recombinational DNA Repair; Ubiquitin-Protein Ligases; Ubiquitination
PubMed: 38324469
DOI: 10.1093/nar/gkae064 -
Breast Cancer Research : BCR Feb 2024The most aggressive form of breast cancer is triple-negative breast cancer (TNBC), which lacks expression of the estrogen receptor (ER) and progesterone receptor (PR),...
BACKGROUND
The most aggressive form of breast cancer is triple-negative breast cancer (TNBC), which lacks expression of the estrogen receptor (ER) and progesterone receptor (PR), and does not have overexpression of the human epidermal growth factor receptor 2 (HER2). Treatment options for women with TNBC tumors are limited, unlike those with ER-positive tumors that can be treated with hormone therapy, or those with HER2-positive tumors that can be treated with anti-HER2 therapy. Therefore, we have sought to identify novel targeted therapies for TNBC. In this study, we investigated the potential of a novel phosphatase, NUDT5, as a potential therapeutic target for TNBC.
METHODS
The mRNA expression levels of NUDT5 in breast cancers were investigated using TCGA and METABRIC (Curtis) datasets. NUDT5 ablation was achieved through siRNA targeting and NUDT5 inhibition with the small molecule inhibitor TH5427. Xenograft TNBC animal models were employed to assess the effect of NUDT5 inhibition on in vivo tumor growth. Proliferation, death, and DNA replication assays were conducted to investigate the cellular biological effects of NUDT5 loss or inhibition. The accumulation of 8-oxo-guanine (8-oxoG) and the induction of γHAX after NUDT5 loss was determined by immunofluorescence staining. The impact of NUDT5 loss on replication fork was assessed by measuring DNA fiber length.
RESULTS
In this study, we demonstrated the significant role of an overexpressed phosphatase, NUDT5, in regulating oxidative DNA damage in TNBCs. Our findings indicate that loss of NUDT5 results in suppressed growth of TNBC both in vitro and in vivo. This growth inhibition is not attributed to cell death, but rather to the suppression of proliferation. The loss or inhibition of NUDT5 led to an increase in the oxidative DNA lesion 8-oxoG, and triggered the DNA damage response in the nucleus. The interference with DNA replication ultimately inhibited proliferation.
CONCLUSIONS
NUDT5 plays a crucial role in preventing oxidative DNA damage in TNBC cells. The loss or inhibition of NUDT5 significantly suppresses the growth of TNBCs. These biological and mechanistic studies provide the groundwork for future research and the potential development of NUDT5 inhibitors as a promising therapeutic approach for TNBC patients.
Topics: Animals; Female; Humans; Cell Line, Tumor; Cell Proliferation; Pyrophosphatases; Receptors, Estrogen; Triple Negative Breast Neoplasms
PubMed: 38317231
DOI: 10.1186/s13058-024-01778-w -
Heliyon Jan 2024The need for naturally occurring constituents is driven by the rise in the cancer prevalence and the unpleasant side effects associated with chemotherapeutics.... (Review)
Review
The need for naturally occurring constituents is driven by the rise in the cancer prevalence and the unpleasant side effects associated with chemotherapeutics. Triptolide, the primary active component of "Tripterygium Wilfordii", has exploited for biological mechanisms and therapeutic potential against various tumors. Based on the recent pre-clinical investigations, triptolide is linked to the induction of death of cancerous cells by triggering cellular apoptosis via inhibiting heat shock protein expression (HSP70), and cyclin dependent kinase (CDKs) by up regulating expression of P21. MKP1, histone methyl transferases and RNA polymerases have all recently identified as potential targets of triptolide in cells. Autophagy, AKT signaling pathway and various pathways involving targeted proteins such as A-disintegrin & metalloprotease-10 (ADAM10), Polycystin-2 (PC-2), dCTP pyro-phosphatase 1 (DCTP1), peroxiredoxin-I (Prx-I), TAK1 binding protein (TAB1), kinase subunit (DNA-PKcs) and the xeroderma-pigmentosum B (XPB or ERCC3) have been exploited. Besides that, triptolide is responsible for enhancing the effectiveness of various chemotherapeutics. In addition, several triptolide moieties, including minnelide and LLDT8, have progressed in investigations on humans for the treatment of cancer. Targeted strategies, such as triptolide conjugation with ligands or triptolide loaded nano-carriers, are efficient techniques to confront toxicities associated with triptolide. We expect and anticipate that advances in near future, regarding combination therapies of triptolide, might be beneficial against cancerous cells.
PubMed: 38293343
DOI: 10.1016/j.heliyon.2024.e24335 -
The Journal of Biological Chemistry Mar 2024Poly(ADP-ribosyl)ation (PARylation) is a critical posttranslational modification that plays a vital role in maintaining genomic stability via a variety of molecular...
Poly(ADP-ribosyl)ation (PARylation) is a critical posttranslational modification that plays a vital role in maintaining genomic stability via a variety of molecular mechanisms, including activation of replication stress and the DNA damage response. The nudix hydrolase NUDT16 was recently identified as a phosphodiesterase that is responsible for removing ADP-ribose units and that plays an important role in DNA repair. However, the roles of NUDT16 in coordinating replication stress and cell cycle progression remain elusive. Here, we report that SETD3, which is a member of the SET-domain containing protein (SETD) family, is a novel substrate for NUDT16, that its protein levels fluctuate during cell cycle progression, and that its stability is strictly regulated by NUDT16-mediated dePARylation. Moreover, our data indicated that the E3 ligase CHFR is responsible for the recognition and degradation of endogenous SETD3 in a PARP1-mediated PARylation-dependent manner. Mechanistically, we revealed that SETD3 associates with BRCA2 and promotes its recruitment to stalled replication fork and DNA damage sites upon replication stress or DNA double-strand breaks, respectively. Importantly, depletion of SETD3 in NUDT16-deficient cells did not further exacerbate DNA breaks or enhance the sensitivity of cancer cells to IR exposure, suggesting that the NUDT16-SETD3 pathway may play critical roles in the induction of tolerance to radiotherapy. Collectively, these data showed that NUDT16 functions as a key upstream regulator of SETD3 protein stability by reversing the ADP-ribosylation of SETD3, and NUDT16 participates in the resolution of replication stress and facilitates HR repair.
Topics: ADP-Ribosylation; DNA Breaks, Double-Stranded; DNA Damage; DNA Repair; Neoplasms; Poly (ADP-Ribose) Polymerase-1; Protein Processing, Post-Translational; Humans; Cell Line; Pyrophosphatases; Histone Methyltransferases
PubMed: 38272222
DOI: 10.1016/j.jbc.2024.105671 -
Scientific Reports Jan 2024The excision and replication, thus the life cycle of pathogenicity islands in staphylococci are regulated by Stl master repressors that form strong dimers. It has been...
Antirepressor specificity is shaped by highly efficient dimerization of the staphylococcal pathogenicity island regulating repressors: Stl repressor dimerization perturbed by dUTPases.
The excision and replication, thus the life cycle of pathogenicity islands in staphylococci are regulated by Stl master repressors that form strong dimers. It has been recently shown that SaPIbov1-Stl dimers are separated during the activation of the Staphylococcus aureus pathogenicity island (SaPI) transcription via helper phage proteins. To understand the mechanism of this regulation, a quantitative analysis of the dimerization characteristics is required. Due to the highly efficient dimerization process, such an analysis has to involve specific solutions that permit relevant experiments to be performed. In the present work, we focused on two staphylococcal Stls associated with high biomedical interest, namely Stl proteins of Staphylococcus aureus bov1 and Staphylococcus hominis ShoCI794_SEPI pathogenicity islands. Exploiting the interactions of these two Stl proteins with their antirepressor-mimicking interaction partners allowed precise determination of the Stl dimerization constant in the subnanomolar range.
Topics: Humans; Genomic Islands; Dimerization; Staphylococcus; Pyrophosphatases; Staphylococcus aureus; Staphylococcal Infections; Polymers
PubMed: 38263343
DOI: 10.1038/s41598-024-51260-y -
International Journal of Molecular... Jan 2024The main function of dUTPases is to regulate the cellular levels of dUTP and dTTP, thereby playing a crucial role in DNA repair mechanisms. Despite the fact that mutant...
The main function of dUTPases is to regulate the cellular levels of dUTP and dTTP, thereby playing a crucial role in DNA repair mechanisms. Despite the fact that mutant organisms with obliterated dUTPase enzymatic activity remain viable, it is not possible to completely knock out the gene due to the lethal consequences of such a mutation for the organism. As a result, it is considered that this class of enzymes performs an additional function that is essential for the organism's survival. In this study, we provide evidence that the dUTPase of bacteriophage T5 fulfills a supplemental function, in addition to its canonical role. We determined the crystal structure of bacteriophage T5 dUTPase with a resolution of 2.0 Å, and we discovered a distinct short loop consisting of six amino acid residues, representing a unique structural feature specific to the T5-like phages dUTPases. The removal of this element did not affect the overall structure of the homotrimer, but it had significant effects on the development of the phage. Furthermore, it was shown that the enzymatic function and the novel function of the bacteriophage T5 dUTPase are unrelated and independent from each other.
Topics: Amino Acids; Bacteriophages; DNA Repair; Mutation; Pyrophosphatases
PubMed: 38255966
DOI: 10.3390/ijms25020892 -
BMC Pediatrics Jan 2024NUDT2 is an enzyme important for maintaining the intracellular level of the diadenosine tetraphosphate (Ap4A). Bi-allelic loss of function variants in NUDT2 has recently...
NUDT2 is an enzyme important for maintaining the intracellular level of the diadenosine tetraphosphate (Ap4A). Bi-allelic loss of function variants in NUDT2 has recently been reported as a rare cause of intellectual disability (ID). Herein, we describe a Chinese girl with ID, attention deficit hyperactivity disorder (ADHD), and motor delays with abnormal walking posture and difficulty climbing stairs, who bears compound heterozygous variants c.34 C > T (p.R12*) and c.194T > G (p.I65R) in NUDT2. Homozygous variants c.34 C > T (p.R12*) or c.186del (p.A63Qfs*3) in NUDT2 were previously reported to cause ID. This is the first patient with ID due to compound heterozygous variants in NUDT2 and p.I65R is a novel missense variant. This study enriched the genotype and phenotype of NUDT2-related ID and supported the critical developmental involvement of NUDT2.
Topics: Female; Humans; Intellectual Disability; Genotype; Phenotype; Mutation, Missense; Homozygote; Nudix Hydrolases; Phosphoric Monoester Hydrolases
PubMed: 38243213
DOI: 10.1186/s12887-024-04542-3 -
American Journal of Physiology. Cell... Mar 2024The phosphodiesterase enzymes mediate calcium-phosphate deposition in various tissues, although which enzymes are active in bone mineralization is unclear. Using gene...
The phosphodiesterase enzymes mediate calcium-phosphate deposition in various tissues, although which enzymes are active in bone mineralization is unclear. Using gene array analysis, we found that a member of ecto-nucleotide pyrophosphatase/phosphodiesterase family, ENPP2, was strongly down-regulated with age in stromal stem cells that produce osteoblasts and make bone. This is in keeping with reduced bone formation in older animals. Thus, we hypothesized that ENPP2 is, at least in part, an early mediator of bone formation and thus may reflect reduced bone formation with age. Since ENPP2 has not previously been shown to have a role in osteoblast differentiation, we studied its effect on bone differentiation from stromal stem cells, verified by flow cytometry for stem cell antigens. In these remarkably uniform osteoblast precursors, we did transfection with ENPP2 DsiRNA, scrambled DsiRNA, or no transfection to make cells with normal or greatly reduced ENPP2 and analyzed osteoblast differentiation and mineralization. Osteoblast differentiation down-regulation was shown by alizarin red binding, silver staining, and alkaline phosphatase activity. Differences were confirmed by real-time PCR for alkaline phosphatase (ALPL), osteocalcin (BGLAP), and ENPP2 and by Western Blot for Enpp2. These were decreased, ∼50%, in osteoblasts transfected with ENPP2 DsiRNA compared with cells transfected with a scrambled DsiRNA or not transfected (control) cells. This finding is the first evidence for the role of ENPP2 in osteoblast differentiation and mineralization. We report the discovery that the ecto-nucleotide pyrophosphatase/phosphodiesterase, ENPP2, is an important regulator of early differentiation of bone-forming osteoblasts.
Topics: Animals; Osteogenesis; Alkaline Phosphatase; Cell Differentiation; Phosphoric Diester Hydrolases; Calcinosis; Pyrophosphatases
PubMed: 38223929
DOI: 10.1152/ajpcell.00692.2023