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PLoS Pathogens Apr 2021Intestinal epithelial cells are subject to attack by a diverse array of microbes, including intracellular as well as extracellular pathogens. While defense in epithelial...
Intestinal epithelial cells are subject to attack by a diverse array of microbes, including intracellular as well as extracellular pathogens. While defense in epithelial cells can be triggered by pattern recognition receptor-mediated detection of microbe-associated molecular patterns, there is much to be learned about how they sense infection via perturbations of host physiology, which often occur during infection. A recently described host defense response in the nematode C. elegans called the Intracellular Pathogen Response (IPR) can be triggered by infection with diverse natural intracellular pathogens, as well as by perturbations to protein homeostasis. From a forward genetic screen, we identified the C. elegans ortholog of purine nucleoside phosphorylase pnp-1 as a negative regulator of IPR gene expression, as well as a negative regulator of genes induced by extracellular pathogens. Accordingly, pnp-1 mutants have resistance to both intracellular and extracellular pathogens. Metabolomics analysis indicates that C. elegans pnp-1 likely has enzymatic activity similar to its human ortholog, serving to convert purine nucleosides into free bases. Classic genetic studies have shown how mutations in human purine nucleoside phosphorylase cause immunodeficiency due to T-cell dysfunction. Here we show that C. elegans pnp-1 acts in intestinal epithelial cells to regulate defense. Altogether, these results indicate that perturbations in purine metabolism are likely monitored as a cue to promote defense against epithelial infection in the nematode C. elegans.
Topics: Animals; Bacterial Infections; Caenorhabditis elegans; Cell Count; Epithelial Cells; Purine Nucleosides; Purine-Nucleoside Phosphorylase; Receptors, Pattern Recognition
PubMed: 33878133
DOI: 10.1371/journal.ppat.1009350 -
Journal of Molecular Biology May 2008Deoxycytidine kinase (dCK) is an essential nucleoside kinase critical for the production of nucleotide precursors for DNA synthesis. This enzyme catalyzes the initial... (Comparative Study)
Comparative Study
Deoxycytidine kinase (dCK) is an essential nucleoside kinase critical for the production of nucleotide precursors for DNA synthesis. This enzyme catalyzes the initial conversion of the nucleosides deoxyadenosine (dA), deoxyguanosine (dG), and deoxycytidine (dC) into their monophosphate forms, with subsequent phosphorylation to the triphosphate forms performed by additional enzymes. Several nucleoside analog prodrugs are dependent on dCK for their pharmacological activation, and even nucleosides of the non-physiological L-chirality are phosphorylated by dCK. In addition to accepting dC and purine nucleosides (and their analogs) as phosphoryl acceptors, dCK can utilize either ATP or UTP as phosphoryl donors. To unravel the structural basis for substrate promiscuity of dCK at both the nucleoside acceptor and nucleotide donor sites, we solved the crystal structures of the enzyme as ternary complexes with the two enantiomeric forms of dA (D-dA, or L-dA), with either UDP or ADP bound to the donor site. The complexes with UDP revealed an open state of dCK in which the nucleoside, either D-dA or L-dA, is surprisingly bound in a manner not consistent with catalysis. In contrast, the complexes with ADP, with either D-dA or L-dA, adopted a closed and catalytically competent conformation. The differential states adopted by dCK in response to the nature of the nucleotide were also detected by tryptophan fluorescence experiments. Thus, we are in the unique position to observe differential effects at the acceptor site due to the nature of the nucleotide at the donor site, allowing us to rationalize the different kinetic properties observed with UTP to those with ATP.
Topics: Binding Sites; Catalysis; Crystallography, X-Ray; Deoxyadenosines; Deoxycytidine; Deoxycytidine Kinase; Deoxyguanosine; Kinetics; Mutagenesis, Site-Directed; Structure-Activity Relationship; Substrate Specificity
PubMed: 18377927
DOI: 10.1016/j.jmb.2008.02.061 -
Acta Poloniae Pharmaceutica 2004Cytotoxic nucleoside analogs have a broad clinical use. They were among the first chemotherapeutic agents used in the treatment of malignant diseases. The anticancer... (Review)
Review
Cytotoxic nucleoside analogs have a broad clinical use. They were among the first chemotherapeutic agents used in the treatment of malignant diseases. The anticancer nucleosides include analogs of physiologic pyrimidine and purine nucleosides. They are used in oncology in the treatment of both, solid tumors and hematological malignancies. These agents have many intracellular targets, e.g. they act as antimetabolites, competing with natural nucleosides during DNA or RNA synthesis and as inhibitors of key cell enzymes. Understanding of the mechanisms of action of these compounds and synthesis of new analogs provides the possibility to further expand the spectrum of their clinical use and enhance their antitumor activity. In this paper we describe mechanisms of action and possible clinical use in the treatment of hematological malignancies of these nucleoside analogs, which are now in different stages of clinical trials, namely tezacitabine, troxacitabine, clofarabine, nelarabine, decitabine, CNDAC and ECyD.
Topics: Adenine Nucleotides; Animals; Antineoplastic Agents; Arabinonucleosides; Clinical Trials as Topic; Clofarabine; Cytarabine; Cytosine; Deoxycytidine; Dioxolanes; Half-Life; Hematologic Neoplasms; Humans; Purine Nucleosides; Pyrimidine Nucleosides; Stereoisomerism
PubMed: 15481249
DOI: No ID Found -
Synthesis of novel purine nucleosides towards a selective inhibition of human butyrylcholinesterase.Bioorganic & Medicinal Chemistry Jul 2009The search for new and potent cholinesterase inhibitors is an ongoing quest mobilizing many organic chemistry groups around the world as these molecules have been shown...
The search for new and potent cholinesterase inhibitors is an ongoing quest mobilizing many organic chemistry groups around the world as these molecules have been shown to treat the late symptoms of Alzheimer's disease as well as to act as neuroprotecting agents. In this work, we disclose the synthesis of novel 2-acetamidopurine nucleosides and, for the first time, regioselective N(7)-glycosylation with 2-acetamido-6-chloropurine, promoted by trimethylsilyl triflate, was accomplished by tuning the reaction conditions (acetonitrile as solvent, 65 degrees C, 5h) starting from 1-acetoxy bicyclic glycosyl donors, or by direct coupling of a methyl glucopyranoside with the nucleobase to obtain only N(7) nucleosides in reasonable yield (55-60%). The nucleosides as well as their sugar precursors were screened for acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition. While none of the compounds tested inhibited AChE, remarkably, some of the N(7) nucleosides and sugar bicyclic derivatives showed potent inhibition towards BChE. Nanomolar inhibition was obtained for one compound competing well with rivastigmine, a drug currently in use for the treatment of Alzheimer's disease. Experimental results showed that the presence of benzyl groups on the carbohydrate scaffold and the N(7)-linked purine nucleobase were necessary for strong BChE inactivation. A preliminary evaluation of the acute cytotoxicity of the elongated bicyclic sugar precursors and nucleosides was performed indicating low values, in the same order of magnitude as those of rivastigmine.
Topics: Alzheimer Disease; Butyrylcholinesterase; Cell Line; Cell Survival; Cholinesterase Inhibitors; Fibroblasts; Glycosylation; Humans; Purine Nucleosides; Stereoisomerism
PubMed: 19520578
DOI: 10.1016/j.bmc.2009.05.057 -
Nucleic Acids Symposium Series (2004) 2008Several thieno-expanded purine nucleoside analogues were synthesized for use as tools in ongoing investigations into nucleic acid structure and function in our...
Several thieno-expanded purine nucleoside analogues were synthesized for use as tools in ongoing investigations into nucleic acid structure and function in our laboratories. The inclusion of the thiophene ring system in the nucleoside endows the purine scaffold with advantages not previously available in other reported expanded purines. The synthesis and preliminary biological studies are reported herein.
Topics: Drug Design; Enzyme Inhibitors; Purine Nucleosides; RNA-Dependent RNA Polymerase
PubMed: 18776540
DOI: 10.1093/nass/nrn321 -
Organic Letters Dec 2017Photochemical precursors that produce dA and dG(N-H) are needed to investigate their reactivity. The synthesis of two 1,1-diphenylhydrazines (1, 2) and their use as...
Photochemical precursors that produce dA and dG(N-H) are needed to investigate their reactivity. The synthesis of two 1,1-diphenylhydrazines (1, 2) and their use as photochemical sources of dA and dG(N-H) is presented. Trapping studies indicate production of these radicals with good fidelity, and 1 was incorporated into an oligonucleotide via solid-phase synthesis. Cyclic voltammetric studies show that reduction potentials of 1 and 2 are lower than those of widely used "hole sinks", e.g., 8-oxodGuo and 7-deazadGuo, to investigate DNA-hole transfer processes. These molecules could be useful (a) as sources of dA and dG(N-H) at specific sites in oligonucleotides and (b) as "hole sinks" for the study of DNA-hole transfer processes.
Topics: 8-Hydroxy-2'-Deoxyguanosine; DNA; Deoxyguanosine; Electrochemical Techniques; Free Radicals; Hydrazines; Molecular Structure; Nitrogen; Oligonucleotides; Photochemical Processes; Purine Nucleosides; Solid-Phase Synthesis Techniques
PubMed: 29125775
DOI: 10.1021/acs.orglett.7b03368 -
Molecules (Basel, Switzerland) Mar 2022Depression is the most common mental illness, affecting approximately 4.4% of the global population. Despite many available treatments, some patients exhibit...
Depression is the most common mental illness, affecting approximately 4.4% of the global population. Despite many available treatments, some patients exhibit treatment-resistant depression. Thus, the need to develop new and alternative treatments cannot be overstated. Adenosine receptor antagonists have emerged as a promising new class of antidepressants. The current study investigates a novel dual A/A adenosine receptor antagonist, namely 2-(3,4-dihydroxybenzylidene)-4-methoxy-2,3-dihydro-1H-inden-1-one (), for antidepressant capabilities by determining its metabolic profiles and comparing them to those of two reference compounds (imipramine and KW-6002). The metabolic profiles were obtained by treating male Sprague-Dawley rats with and the reference compounds and subjecting them to the forced swim test. Serum and brain material was consequently collected from the animals following euthanasia, after which the metabolites were extracted and analyzed through untargeted metabolomics using both H-NMR and GC-TOFMS. The current study provides insight into compound 's metabolic profile. The metabolic profile of was similar to those of the reference compounds. They potentially exhibit their antidepressive capabilities via downstream effects on amino acid and lipid metabolism.
Topics: Adenosine A2 Receptor Antagonists; Animals; Antidepressive Agents; Depression; Humans; Male; Metabolomics; Purine Nucleosides; Purinergic P1 Receptor Antagonists; Rats; Rats, Sprague-Dawley
PubMed: 35408500
DOI: 10.3390/molecules27072094 -
The Journal of Biological Chemistry Nov 1998Although purinergic compounds are widely involved in the intra- and intercellular communication of the nervous system, little is known of their involvement in the growth...
Although purinergic compounds are widely involved in the intra- and intercellular communication of the nervous system, little is known of their involvement in the growth and regeneration of neuronal connections. In dissociated cultures, the addition of adenosine or guanosine in the low micromolar range induced goldfish retinal ganglion cells to extend lengthy neurites and express the growth-associated protein GAP-43. These effects were highly specific and did not reflect conversion of the nucleosides to their nucleotide derivatives; pyrimidines, purine nucleotides, and membrane-permeable, nonhydrolyzable cyclic nucleotide analogs were all inactive. The activity of adenosine required its conversion to inosine, because inhibitors of adenosine deaminase rendered adenosine inactive. Exogenously applied inosine and guanosine act directly upon an intracellular target, which may coincide with a kinase described in PC12 cells. In support of this, the effects of the purine nucleosides were blocked with purine transport inhibitors and were inhibited competitively with the purine analog 6-thioguanine (6-TG). In PC12 cells, others have shown that 6-TG blocks nerve growth factor-induced neurite outgrowth and selectively inhibits the activity of protein kinase N, a partially characterized, nerve growth factor-inducible serine-threonine kinase. In both goldfish and rat retinal ganglion cells, 6-TG completely blocked outgrowth induced by other growth factors, and this inhibition was reversed with inosine. These results suggest that axon outgrowth in central nervous system neurons critically involves an intracellular purine-sensitive mechanism.
Topics: Adenosine; Animals; Axons; Calcium-Calmodulin-Dependent Protein Kinases; Goldfish; Hydrolysis; Inosine; Phosphatidylinositol 3-Kinases; Purine Nucleosides; Purine Nucleotides; Purinergic P1 Receptor Antagonists; Rats; Rats, Sprague-Dawley; Retinal Ganglion Cells; Thioguanine
PubMed: 9792672
DOI: 10.1074/jbc.273.45.29626 -
Science (New York, N.Y.) Apr 2015Most approved antiviral therapeutics selectively inhibit proteins encoded by a single virus, thereby providing a “one drug-one bug” solution. As a result of this...
Most approved antiviral therapeutics selectively inhibit proteins encoded by a single virus, thereby providing a “one drug-one bug” solution. As a result of this narrow spectrum of coverage and the high cost of drug development, therapies are currently approved for fewer than ten viruses out of the hundreds known to cause human disease. This perspective summarizes progress and challenges in the development of broad-spectrum antiviral therapies. These strategies include targeting enzymatic functions shared by multiple viruses and host cell machinery by newly discovered compounds or by repurposing approved drugs. These approaches offer new practical means for developing therapeutics against existing and emerging viral threats.
Topics: Adenine; Adenosine; Antiviral Agents; Benzamides; Chloroquine; Communicable Diseases, Emerging; Cyclosporins; Cytosine; Dengue; Drug Approval; Drug Design; Erlotinib Hydrochloride; Hemorrhagic Fever, Ebola; Humans; Imatinib Mesylate; Indoles; Organophosphonates; Piperazines; Purine Nucleosides; Pyrimidines; Pyrroles; Pyrrolidines; Quinazolines; Sunitinib; Viruses
PubMed: 25883340
DOI: 10.1126/science.aaa3778 -
Chemistry & Biology Sep 2009Purine nucleoside phosphorylase (PNP) catalyzes the phosphorolysis of 6-oxy-purine nucleosides to the corresponding purine base and alpha-D-ribose 1-phosphate. Its...
Purine nucleoside phosphorylase (PNP) catalyzes the phosphorolysis of 6-oxy-purine nucleosides to the corresponding purine base and alpha-D-ribose 1-phosphate. Its genetic loss causes a lethal T cell deficiency. The highly reactive ribocation transition state of human PNP is protected from solvent by hydrophobic residues that sequester the catalytic site. The catalytic site was enlarged by replacing individual catalytic site amino acids with glycine. Reactivity of the ribocation transition state was tested for capture by water and other nucleophiles. In the absence of phosphate, inosine is hydrolyzed by native, Y88G, F159G, H257G, and F200G enzymes. Phosphorolysis but not hydrolysis is detected when phosphate is bound. An unprecedented N9-to-N3 isomerization of inosine is catalyzed by H257G and F200G in the presence of phosphate and by all PNPs in the absence of phosphate. These results establish a ribocation lifetime too short to permit capture by water. An enlarged catalytic site permits ribocation formation with relaxed geometric constraints, permitting nucleophilic rebound and N3-inosine isomerization.
Topics: Biocatalysis; Catalytic Domain; Humans; Hydrolysis; Inosine; Isomerism; Kinetics; Magnetic Resonance Spectroscopy; Purine Nucleosides; Purine-Nucleoside Phosphorylase; Ribosemonophosphates
PubMed: 19778725
DOI: 10.1016/j.chembiol.2009.07.012