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Frontiers in Immunology 2022Limiting purine intake, inhibiting xanthine oxidoreductase (XOR) and inhibiting urate reabsorption in proximal tubule by uricosuric drugs, to reduce serum uric acid (UA)...
OBJECTIVE
Limiting purine intake, inhibiting xanthine oxidoreductase (XOR) and inhibiting urate reabsorption in proximal tubule by uricosuric drugs, to reduce serum uric acid (UA) levels, are recognized treatments for gout. However, the mechanism of increased how XOR expression and activity in hyperuricemia and gout remains unclear. This study aims to explore whether exogenous purines are responsible for increased XOR expression and activity.
METHODS
HepG2 and Bel-7402 human hepatoma cells were stimulated with exogenous purine, or were exposed to conditioned growth medium of purine-stimulated Jurkat cells, followed by measurement of XOR expression and UA production to determine the effect of lymphocyte-secreted cytokines on XOR expression in hepatocytes. The expression of STAT1, IRF1 and CBP and their binding on the promoter were detected by western blotting and ChIP-qPCR. The level of DNA methylation was determined by bisulfite sequencing PCR. Blood samples from 117 hyperuricemia patients and 119 healthy individuals were collected to analyze the correlation between purine, UA and IFN-γ concentrations.
RESULTS
Excess of purine was metabolized to UA in hepatocyte metabolism by XOR that was induced by IFN-γ secreted in the conditioned growth medium of Jurkat cells in response to exogenous purine, but it did not directly induce XOR expression. IFN-γ upregulated XOR expression due to the enhanced binding of STAT1 to IRF1 to further recruit CBP to the promoter. Clinical data showed positive correlation of serum IFN-γ with both purine and UA, and associated risk of hyperuricemia.
CONCLUSION
Purine not only acts as a metabolic substrate of XOR for UA production, but it induces inflammation through IFN-γ secretion that stimulates UA production through elevation of XOR expression.
Topics: Carcinoma, Hepatocellular; Cell Line, Tumor; Hepatocytes; Humans; Inflammation; Interferon-gamma; Jurkat Cells; Liver Neoplasms; Purines; Up-Regulation; Uric Acid; Xanthine Dehydrogenase
PubMed: 35154100
DOI: 10.3389/fimmu.2022.773001 -
Wiley Interdisciplinary Reviews. RNA 2012Molecular investigations of riboswitches bound to small-molecule effectors have produced a wealth of information on how these molecules achieve high affinity and... (Review)
Review
Molecular investigations of riboswitches bound to small-molecule effectors have produced a wealth of information on how these molecules achieve high affinity and specificity for a target ligand. X-ray crystal structures have been determined for the ligand-free state for representatives of the preQ₁-I, S-adenosylmethionine I, lysine, and glycine aptamer classes. These structures in conjunction with complimentary techniques, such as in-line probing, NMR spectroscopy, Förster resonance energy transfer, small-angle scattering, and computational simulations, have demonstrated that riboswitches adopt multiple conformations in the absence of ligand. Despite a number of investigations that support ligand-dependent folding, mounting evidence suggests that free-state riboswitches interact with their effectors in the sub-populations of largely prefolded states as embodied by the principle of conformational selection, which has been documented extensively for protein-mediated ligand interactions. Fundamental riboswitch investigations of the bound and free states have advanced our understanding of RNA folding, ligand recognition, and how these factors culminate in communication between an aptamer and its expression platform. An understanding of these topics is essential to comprehend riboswitch gene regulation at the molecular level, which has already provided a basis to understand the mechanism of action of natural antimicrobials.
Topics: Amino Acids; Binding Sites; Ligands; Nucleic Acid Conformation; Purines; Pyrimidinones; Pyrroles; RNA Folding; Riboswitch; S-Adenosylmethionine
PubMed: 21957061
DOI: 10.1002/wrna.114 -
Vascular Pharmacology Apr 2023Sildenafil, a well-known vasodilator known to interfere with purinergic signaling through effects on cGMP, is a mainstay in the treatment of pulmonary hypertension (PH)....
RATIONALE
Sildenafil, a well-known vasodilator known to interfere with purinergic signaling through effects on cGMP, is a mainstay in the treatment of pulmonary hypertension (PH). However, little is known regarding its effects on the metabolic reprogramming of vascular cells, which is a hallmark of PH. Purine metabolism, especially intracellular de novo purine biosynthesis is essential for vascular cell proliferation. Since adventitial fibroblasts are critical contributors to proliferative vascular remodeling in PH, in this study we aimed to investigate if sildenafil, beyond its well-known vasodilator role in smooth muscle cells, impacts intracellular purine metabolism and proliferation of fibroblasts derived from human PH patients.
METHODS
Integrated omics approaches (plasma and cell metabolomics) and pharmacological inhibitor approaches were employed in plasma samples and cultured pulmonary artery fibroblasts from PH patients.
MEASUREMENTS AND MAIN RESULTS
Plasma metabolome analysis of 27 PH patients before and after treatment with sildenafil, demonstrated a partial, but specific effect of sildenafil on purine metabolites, especially adenosine, adenine, and xanthine. However, circulating markers of cell stress, including lactate, succinate, and hypoxanthine were only decreased in a small subset of sildenafil-treated patients. To better understand potential effects of sildenafil on pathological changes in purine metabolism (especially purine synthesis) in PH, we performed studies on pulmonary fibroblasts from PAH patients (PH-Fibs) and corresponding controls (CO-Fibs), since these cells have previously been shown to demonstrate stable and marked PH associated phenotypic and metabolic changes. We found that PH-Fibs exhibited significantly increased purine synthesis. Treatment of PH-Fibs with sildenafil was insufficient to normalize cellular metabolic phenotype and only modestly attenuated the proliferation. However, we observed that treatments which have been shown to normalize glycolysis and mitochondrial abnormalities including a PKM2 activator (TEPP-46), and the histone deacetylase inhibitors (HDACi), SAHA and Apicidin, had significant inhibitory effects on purine synthesis. Importantly, combined treatment with HDACi and sildenafil exhibited synergistic inhibitory effects on proliferation and metabolic reprogramming in PH-Fibs.
CONCLUSIONS
While sildenafil alone partially rescues metabolic alterations associated with PH, treatment with HDACi, in combination with sildenafil, represent a promising and potentially more effective strategy for targeting vasoconstriction, metabolic derangement and pathological vascular remodeling in PH.
Topics: Humans; Sildenafil Citrate; Hypertension, Pulmonary; Histone Deacetylase Inhibitors; Vascular Remodeling; Vasodilator Agents; Pulmonary Artery; Purines; Cell Proliferation
PubMed: 36849042
DOI: 10.1016/j.vph.2023.107157 -
Molecular BioSystems Mar 2014Some metabolic pathway enzymes are known to organize into multi-enzyme complexes for reasons of catalytic efficiency, metabolite channeling, and other advantages of... (Review)
Review
Some metabolic pathway enzymes are known to organize into multi-enzyme complexes for reasons of catalytic efficiency, metabolite channeling, and other advantages of compartmentalization. It has long been an appealing prospect that de novo purine biosynthesis enzymes form such a complex, termed the "purinosome." Early work characterizing these enzymes garnered scarce but encouraging evidence for its existence. Recent investigations led to the discovery in human cell lines of purinosome bodies-cytoplasmic puncta containing transfected purine biosynthesis enzymes, which were argued to correspond to purinosomes. New discoveries challenge both the functional and physiological relevance of these bodies in favor of protein aggregation.
Topics: Cytoplasmic Granules; Humans; Multienzyme Complexes; Protein Binding; Protein Transport; Proteins; Purines
PubMed: 24413256
DOI: 10.1039/c3mb70397e -
Journal of Biological Inorganic... Dec 2022New mono- and di-nuclear thio-purine and thio-purine nucleoside gold(I) complexes were synthesized, characterized, and evaluated in vitro for biological activities in...
New mono- and di-nuclear thio-purine and thio-purine nucleoside gold(I) complexes were synthesized, characterized, and evaluated in vitro for biological activities in comparison to related known purine complexes. By combining known anti-tumoral thio-purines with RPAu moieties as present in auranofin, complexes with enhanced effects and selectivities were obtained, which not only act as cytostatics, but also disrupt tumor-specific processes. Their IC values in cytotoxicity test with tumor cell lines ranged from three-digit nanomolar to single-digit micromolar, revealing a tentative structure-activity relationship (SAR). Both the residues R of the phosphane ligand and R at C2 of the pyrimidine ring had a significant impact on the cytotoxicity. In most cases, the introduction of a ribo-furanosyl group at N9 of the purine led to a distinctly more cytotoxic complex. Most complexes were more active against multi-drug-resistant tumor cells or such lacking functional p53 when compared to the respective untreated wild type cell lines. Some nucleoside complexes displayed an interesting dose-dependent dual mode of action regarding cell cycle arrest and DNA repair mechanism. Some phosphane(purine-6-thiolato)gold (I) complexes had a stronger inhibitory effect on the thioredoxin reductase (TrxR) and on the reactive oxygen species (ROS) generation in cancer cells than is typical of other gold complexes. They also led to DNA fragmentation and showed anti-angiogenic effects. Their stability under test conditions was demonstrated by Se NMR monitoring of an exemplary selenopurine complex.
Topics: Gold; Phosphines; Thioredoxin-Disulfide Reductase; Purines; Cell Line, Tumor; Antineoplastic Agents; Coordination Complexes
PubMed: 36244017
DOI: 10.1007/s00775-022-01968-x -
The ISME Journal Sep 2022Despite the widespread occurrence of intracellular crystalline inclusions in unicellular eukaryotes, scant attention has been paid to their composition, functions, and...
Despite the widespread occurrence of intracellular crystalline inclusions in unicellular eukaryotes, scant attention has been paid to their composition, functions, and evolutionary origins. Using Raman microscopy, we examined >200 species from all major eukaryotic supergroups. We detected cellular crystalline inclusions in 77% species out of which 80% is composed of purines, such as anhydrous guanine (62%), guanine monohydrate (2%), uric acid (12%) and xanthine (4%). Our findings shifts the paradigm assuming predominance of calcite and oxalates. Purine crystals emerge in microorganisms in all habitats, e.g., in freshwater algae, endosymbionts of reef-building corals, deadly parasites, anaerobes in termite guts, or slime molds. Hence, purine biocrystallization is a general and ancestral eukaryotic process likely present in the last eukaryotic common ancestor (LECA) and here we propose two proteins omnipresent in eukaryotes that are likely in charge of their metabolism: hypoxanthine-guanine phosphoribosyl transferase and equilibrative nucleoside transporter. Purine crystalline inclusions are multifunctional structures representing high-capacity and rapid-turnover reserves of nitrogen and optically active elements, e.g., used in light sensing. Thus, we anticipate our work to be a starting point for further studies spanning from cell biology to global ecology, with potential applications in biotechnologies, bio-optics, or in human medicine.
Topics: Biomineralization; Eukaryota; Guanine; Humans; Purines
PubMed: 35672454
DOI: 10.1038/s41396-022-01264-1 -
Chemical & Pharmaceutical Bulletin 2018In this review, we have summarized the research effort into the development of unnatural base pairs beyond standard Watson-Crick (WC) base pairs for synthetic biology.... (Review)
Review
In this review, we have summarized the research effort into the development of unnatural base pairs beyond standard Watson-Crick (WC) base pairs for synthetic biology. Prior to introducing our research results, we present investigations by four outstanding groups in the field. Their research results demonstrate the importance of shape complementarity and stacking ability as well as hydrogen-bonding (H-bonding) patterns for unnatural base pairs. On the basis of this research background, we developed unnatural base pairs consisting of imidazo[5',4':4.5]pyrido[2,3-d]pyrimidines and 1,8-naphthyridines, i.e., Im : Na pairs. Since Im bases are recognized as ring-expanded purines and Na bases are recognized as ring-expanded pyrimidines, Im : Na pairs are expected to satisfy the criteria of shape complementarity and enhanced stacking ability. In addition, these pairs have four non-canonical H-bonds. Because of these preferable properties, ImN : NaO, one of the Im : Na pairs, is recognized as a complementary base pair in not only single nucleotide insertion, but also the PCR.
Topics: Base Pairing; Hydrogen Bonding; Naphthyridines; Physical Phenomena; Purines; Pyrimidines; Synthetic Biology
PubMed: 29386463
DOI: 10.1248/cpb.c17-00685 -
Nature Chemistry Nov 2017Understanding the diversity of dynamic structures and functions of DNA and RNA in biology requires tools that can selectively and intimately probe these biomolecules.... (Review)
Review
Understanding the diversity of dynamic structures and functions of DNA and RNA in biology requires tools that can selectively and intimately probe these biomolecules. Synthetic fluorescent nucleobases that can be incorporated into nucleic acids alongside their natural counterparts have emerged as a powerful class of molecular reporters of location and environment. They are enabling new basic insights into DNA and RNA, and are facilitating a broad range of new technologies with chemical, biological and biomedical applications. In this Review, we will present a brief history of the development of fluorescent nucleobases and explore their utility as tools for addressing questions in biophysics, biochemistry and biology of nucleic acids. We provide chemical insights into the two main classes of these compounds: canonical and non-canonical nucleobases. A point-by-point discussion of the advantages and disadvantages of both types of fluorescent nucleobases is made, along with a perspective into the future challenges and outlook for this burgeoning field.
Topics: DNA; Fluorescent Dyes; Purines; Pyrimidines; RNA
PubMed: 29064490
DOI: 10.1038/nchem.2859 -
Current Opinion in Structural Biology Feb 2014There are a growing number of studies reporting the observation of purine-pyrimidine base-pairs that are seldom observed in unmodified nucleic acids because they entail... (Review)
Review
There are a growing number of studies reporting the observation of purine-pyrimidine base-pairs that are seldom observed in unmodified nucleic acids because they entail the loss of energetically favorable interactions or require energetically costly base ionization or tautomerization. These high energy purine-pyrimidine base-pairs include G•C(+) and A•T Hoogsteen base-pairs, which entail ∼180° rotation of the purine base in a Watson-Crick base-pair, protonation of cytosine N3, and constriction of the C1'-C1' distance by ∼2.5Å. Other high energy pure-pyrimidine base-pairs include G•T, G•U, and A•C mispairs that adopt Watson-Crick like geometry through either base ionization or tautomerization. Although difficult to detect and characterize using biophysical methods, high energy purine-pyrimidine base-pairs appear to be more common than once thought. They further expand the structural and functional diversity of canonical and non-canonical nucleic acid base-pairs.
Topics: Animals; Base Pairing; DNA; Humans; Isomerism; Models, Molecular; Nucleic Acid Conformation; Purines; Pyrimidines
PubMed: 24721455
DOI: 10.1016/j.sbi.2013.12.003 -
Cells Sep 2023Purines are required for fundamental biological processes and alterations in their metabolism lead to severe genetic diseases associated with developmental defects whose...
Purines are required for fundamental biological processes and alterations in their metabolism lead to severe genetic diseases associated with developmental defects whose etiology remains unclear. Here, we studied the developmental requirements for purine metabolism using the amphibian as a vertebrate model. We provide the first functional characterization of purine pathway genes and show that these genes are mainly expressed in nervous and muscular embryonic tissues. Morphants were generated to decipher the functions of these genes, with a focus on the adenylosuccinate lyase (), which is an enzyme required for both salvage and de novo purine pathways. knockdown led to a severe reduction in the expression of the myogenic regulatory factors (MRFs: Myod1, Myf5 and Myogenin), thus resulting in defects in somite formation and, at later stages, the development and/or migration of both craniofacial and hypaxial muscle progenitors. The reduced expressions of and , which are two genes specific to the salvage and de novo pathways, respectively, resulted in similar alterations. In conclusion, our data show for the first time that de novo and recycling purine pathways are essential for myogenesis and highlight new mechanisms in the regulation of MRF gene expression.
Topics: Animals; Xenopus laevis; Muscle, Skeletal; Purines; Muscle Development
PubMed: 37830593
DOI: 10.3390/cells12192379