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Nature Communications Mar 2023By lacking de novo purine biosynthesis enzymes, Plasmodium falciparum requires purine nucleoside uptake from host cells. The indispensable nucleoside transporter ENT1 of...
By lacking de novo purine biosynthesis enzymes, Plasmodium falciparum requires purine nucleoside uptake from host cells. The indispensable nucleoside transporter ENT1 of P. falciparum facilitates nucleoside uptake in the asexual blood stage. Specific inhibitors of PfENT1 prevent the proliferation of P. falciparum at submicromolar concentrations. However, the substrate recognition and inhibitory mechanism of PfENT1 are still elusive. Here, we report cryo-EM structures of PfENT1 in apo, inosine-bound, and inhibitor-bound states. Together with in vitro binding and uptake assays, we identify that inosine is the primary substrate of PfENT1 and that the inosine-binding site is located in the central cavity of PfENT1. The endofacial inhibitor GSK4 occupies the orthosteric site of PfENT1 and explores the allosteric site to block the conformational change of PfENT1. Furthermore, we propose a general "rocker switch" alternating access cycle for ENT transporters. Understanding the substrate recognition and inhibitory mechanisms of PfENT1 will greatly facilitate future efforts in the rational design of antimalarial drugs.
Topics: Humans; Plasmodium falciparum; Nucleoside Transport Proteins; Nucleobase, Nucleoside, Nucleotide, and Nucleic Acid Transport Proteins; Malaria, Falciparum; Purine Nucleosides; Inosine
PubMed: 36977719
DOI: 10.1038/s41467-023-37411-1 -
Immunity, Inflammation and Disease Apr 2023Adenosine receptors are P1 class of purinergic receptors that belong to G protein-coupled receptors. There are 4 subtypes of adenosine receptors, namely A1, A2A, A2B,... (Review)
Review
Adenosine receptors are P1 class of purinergic receptors that belong to G protein-coupled receptors. There are 4 subtypes of adenosine receptors, namely A1, A2A, A2B, and A3. A2AR has a high affinity for the ligand adenosine. Under pathological conditions or external stimuli, ATP is sequentially hydrolyzed to adenosine by CD39 and CD73. The combination of adenosine and A2AR can increase the concentration of cAMP and activate a series of downstream signaling pathways, and further playing the role of immunosuppression and promotion of tumor invasion. A2AR is expressed to some extent on various immune cells, where it is abnormally expressed on immune cells in cancers and autoimmune diseases. A2AR expression also correlates with disease progression. Inhibitors and agonists of A2AR may be potential new strategies for treatment of cancers and autoimmune diseases. We herein briefly reviewed the expression and distribution of A2AR, adenosine/A2AR signaling pathway, expression, and potential as a therapeutic target.
Topics: Humans; Receptor, Adenosine A2A; Adenosine; Autoimmune Diseases; Signal Transduction; Neoplasms
PubMed: 37102661
DOI: 10.1002/iid3.826 -
Reproduction in Domestic Animals =... Jan 2021Natural modifications of cellular RNA include various chemical modifications, such as N6-methyladenosine (m A), which enable the orderly metabolism and function of RNA... (Review)
Review
Natural modifications of cellular RNA include various chemical modifications, such as N6-methyladenosine (m A), which enable the orderly metabolism and function of RNA structural diversity, thereby affecting gene expression. Spermatogenesis is a complex differentiating developmental process, which includes the proliferation of spermatogonial stem cells, spermatocyte meiosis and sperm maturation. Emerging evidence has shown that RNA methylation can influence RNA splicing, exportation and translation, which are controlled in the male germline in order to ensure coordinated gene expression. In this review, we summarize the typical characteristics of different types of RNA methylation during the process of spermatogenesis. In particular, we emphasize the functions of the RNA methylation effectors during the male germ cell development.
Topics: Adenosine; Animals; Male; Methylation; RNA Processing, Post-Transcriptional; Spermatogenesis
PubMed: 33174242
DOI: 10.1111/rda.13856 -
Nucleic Acids Research May 2021Deazapurine nucleosides such as 3-deazaadenosine (c3A) are crucial for atomic mutagenesis studies of functional RNAs. They were the key for our current mechanistic...
Deazapurine nucleosides such as 3-deazaadenosine (c3A) are crucial for atomic mutagenesis studies of functional RNAs. They were the key for our current mechanistic understanding of ribosomal peptide bond formation and of phosphodiester cleavage in recently discovered small ribozymes, such as twister and pistol RNAs. Here, we present a comprehensive study on the impact of c3A and the thus far underinvestigated 3-deazaguanosine (c3G) on RNA properties. We found that these nucleosides can decrease thermodynamic stability of base pairing to a significant extent. The effects are much more pronounced for 3-deazapurine nucleosides compared to their constitutional isomers of 7-deazapurine nucleosides (c7G, c7A). We furthermore investigated base pair opening dynamics by solution NMR spectroscopy and revealed significantly enhanced imino proton exchange rates. Additionally, we solved the X-ray structure of a c3A-modified RNA and visualized the hydration pattern of the minor groove. Importantly, the characteristic water molecule that is hydrogen-bonded to the purine N3 atom and always observed in a natural double helix is lacking in the 3-deazapurine-modified counterpart. Both, the findings by NMR and X-ray crystallographic methods hence provide a rationale for the reduced pairing strength. Taken together, our comparative study is a first major step towards a comprehensive understanding of this important class of nucleoside modifications.
Topics: Base Pairing; Crystallography, X-Ray; Mutagenesis; Purines; RNA; RNA Stability; Thermodynamics; Tubercidin
PubMed: 33856457
DOI: 10.1093/nar/gkab256 -
Clinical Biochemistry Jun 2021Recently, the enzyme nudix hydrolase 15 (NUDT15) has been identified as an additional component of the thiopurine metabolism pathway. NUDT15 (also known as MTH2)... (Review)
Review
Recently, the enzyme nudix hydrolase 15 (NUDT15) has been identified as an additional component of the thiopurine metabolism pathway. NUDT15 (also known as MTH2) catalyzes the dephosphorylation of 6-thioguanosine triphosphate (6-TGTP) and 6-thio-deoxyguanosine triphosphate (6-TdGTP), which is the active metabolite of thiopurine medications. Thiopurine compounds, which were first synthesized in the 1950s, are widely used in the treatment of childhood leukemia, inflammatory bowel disease, and autoimmune disorders. For many years, TPMT has been recognized as an enzyme that is involved in thiopurine metabolism, and interindividual variation in TPMT activity has been known to contribute to differences in risk of thiopurine toxicity. Genetic variation that leads to decreased NUDT15 activity has been recognized as an additional contributor, beyond TPMT, to thiopurine toxicity. In some populations, including Asian and Latino populations, NUDT15 genetic variants are more common than TPMT variants, making this a significant biomarker of toxicity. Clinical genetic testing is now available for a subset of NUDT15 variants, representing a remarkably fast translation from bench to bedside. This review will focus on NUDT15 - from discovery to clinical implementation.
Topics: Asian People; Hispanic or Latino; Humans; Inflammatory Bowel Diseases; Methyltransferases; Mutation; Pharmacogenomic Variants; Purine Nucleosides; Pyrophosphatases; Thionucleosides
PubMed: 33675810
DOI: 10.1016/j.clinbiochem.2021.02.007 -
Nature Jun 2020The nature of the first genetic polymer is the subject of major debate. Although the 'RNA world' theory suggests that RNA was the first replicable information carrier of...
The nature of the first genetic polymer is the subject of major debate. Although the 'RNA world' theory suggests that RNA was the first replicable information carrier of the prebiotic era-that is, prior to the dawn of life-other evidence implies that life may have started with a heterogeneous nucleic acid genetic system that included both RNA and DNA. Such a theory streamlines the eventual 'genetic takeover' of homogeneous DNA from RNA as the principal information-storage molecule, but requires a selective abiotic synthesis of both RNA and DNA building blocks in the same local primordial geochemical scenario. Here we demonstrate a high-yielding, completely stereo-, regio- and furanosyl-selective prebiotic synthesis of the purine deoxyribonucleosides: deoxyadenosine and deoxyinosine. Our synthesis uses key intermediates in the prebiotic synthesis of the canonical pyrimidine ribonucleosides (cytidine and uridine), and we show that, once generated, the pyrimidines persist throughout the synthesis of the purine deoxyribonucleosides, leading to a mixture of deoxyadenosine, deoxyinosine, cytidine and uridine. These results support the notion that purine deoxyribonucleosides and pyrimidine ribonucleosides may have coexisted before the emergence of life.
Topics: Adenosine; Cytidine; DNA; Evolution, Chemical; Origin of Life; Oxidation-Reduction; Purine Nucleosides; Pyrimidine Nucleosides; RNA; Uridine
PubMed: 32494078
DOI: 10.1038/s41586-020-2330-9 -
Journal of Cellular Physiology Jul 2022N6-methyladenosine (m6A) is an extremely common and conservative posttranscriptional modification, that can specifically target and regulate the expression or stability... (Review)
Review
N6-methyladenosine (m6A) is an extremely common and conservative posttranscriptional modification, that can specifically target and regulate the expression or stability of a series of tumor-related genes, thus playing critical roles in the occurrence and development of tumors. c-Myc is an important tumorigenic transcription factor that promotes tumorigenesis and development by mainly regulating the expression of downstream target genes. Increasing evidence shows that m6A modification, as well as abnormal expression and regulation of c-Myc, is critical molecular mechanisms driving tumorigenesis and development. Although more evidence has been uncovered about the individual roles of m6A modification or c-Myc in tumors, the interaction between m6A modification and c-Myc in tumorigenesis and development has not been systematically summarized. Therefore, this review is focused on the mutual regulation between m6A modification and c-Myc expression and stability as well as its roles in tumorigenesis and development. We also summarized the potential value of the interaction between m6A modification and m6A expression and stability in tumor diagnosis and treatment, which provides a specific reference for revealing the mechanism of tumor occurrence and development as well as clinical diagnosis and treatment.
Topics: Adenosine; Carcinogenesis; Gene Expression Regulation; Humans; Neoplasms; Proto-Oncogene Proteins c-myc
PubMed: 35388487
DOI: 10.1002/jcp.30733 -
Medical Science Monitor : International... Apr 2020According to the World Health Organization cardiovascular disease risk charts, the mortality rate of cardiovascular diseases in people is still high. The medical... (Review)
Review
According to the World Health Organization cardiovascular disease risk charts, the mortality rate of cardiovascular diseases in people is still high. The medical expenses caused by cardiovascular diseases are increasing daily, and the medical burden is becoming heavier; as such, it is imperative to prevent and cure cardiovascular diseases. A large number of scholars are analyzing the pathogenesis of cardiovascular diseases from various perspectives. Recent findings suggest that N6-methyladenosine (m6A) plays a multifaceted role in the cardiovascular system. m6A is a methylated modification product on RNA molecules and exists on various RNA molecules. It is one of the most common epigenetic modifications discovered to date. It regulates the expression of genes and subsequent responses. The amount of m6A is determined by methylases (writers) and demethylases (erasers). The third type of proteins, readers, selectively bind to m6A to regulate RNA stability and gene expression. In this paper, the relationship between m6A and related enzymes and cardiovascular structure and function was reviewed based on recent research results regarding the cardiovascular system.
Topics: Adenosine; Cardiovascular Diseases; Cardiovascular System; Epigenesis, Genetic; Gene Expression; Humans; Lipid Metabolism; Lipids; Methylation; Methyltransferases
PubMed: 32350237
DOI: 10.12659/MSM.921742 -
Frontiers in Bioscience (Landmark... Oct 2023Metazoan adenosine-to-inosine (A-to-I) RNA editing is a highly conserved mechanism that diversifies the transcriptome by post-transcriptionally converting adenosine to... (Review)
Review
Metazoan adenosine-to-inosine (A-to-I) RNA editing is a highly conserved mechanism that diversifies the transcriptome by post-transcriptionally converting adenosine to inosine. Millions of editing sites have been identified in different species and, based on abnormal editing observed in various disorders, it is intuitive to conclude that RNA editing is both functional and adaptive. In this review, we propose the following major points: (1) "Function/functional" only represents a molecular/phenotypic consequence and is not necessarily connected to "adaptation/adaptive"; (2) Adaptive editing should be judged in the light of evolution and emphasize advantages of temporal-spatial flexibility; (3) Adaptive editing could, in theory, be extended from nonsynonymous sites to all potentially functional sites. This review seeks to conceptually bridge the gap between molecular biology and evolutionary biology and provide a more objective understanding on the biological functions and evolutionary significance of RNA editing.
Topics: Animals; RNA; RNA Editing; Adenosine; Inosine; Transcriptome
PubMed: 37919076
DOI: 10.31083/j.fbl2810256 -
ChemMedChem Feb 2024The synthesis and antiproliferative evaluation of novel d-glucopyranuronamide-containing nucleosides is described. Based on our previously reported anticancer...
The synthesis and antiproliferative evaluation of novel d-glucopyranuronamide-containing nucleosides is described. Based on our previously reported anticancer d-glucuronamide-based nucleosides, new analogues comprising N/O-dodecyl or N-propargyl substituents at the glucuronamide unit and anomerically-N-linked 2-acetamido-6-chloropurine, 6-chloropurine or 4-(6-chloropurinyl)methyl triazole motifs were synthesized in 4-6 steps starting from acetonide-protected glucofuranurono-6,3-lactone. The methodologies were based on the access to N-substituted glycopyranuronamide precursors, namely 1,2-O-acetyl derivatives or glucuronoamidyl azides for further nucleobase N-glycosylation or 1,3-dipolar cycloaddition with N - and N -propargyl-6-chloropurines, respectively. N-Propargyl glucuronamide-based N -purine nucleosides were converted into (triazolyl)methyl amide-6,6-linked pseudodisaccharide nucleosides via cycloaddition with methyl 6-azido-glucopyranoside. A CuI/Amberlyst A-21 catalytic system employed in the cycloaddition reactions also effected conversion into 6-dimethylaminopurine nucleosides. Antiproliferative evaluation in chronic myeloid leukemia (K562) and breast cancer (MCF-7) cells revealed significant effects exhibited by the synthesized monododecylated purine-containing nucleosides. A N-propargyl 3-O-dodecyl glucuronamide derivative comprising a N -β-linked 6-chloropurine moiety was the most active compound against MCF-7 cells (GI =11.9 μM) while a related α-(purinyl)methyltriazole nucleoside comprising a N -linked 6-chloropurine moiety exhibited the highest activity against K562 cells (GI =8.0 μM). Flow cytometry and immunoblotting analysis of apoptosis-related proteins in K562 cells treated with the N-propargyl 3-O-dodecyl glucuronamide-based N -linked 6-chloropurine nucleoside indicated that it acts via apoptosis induction.
Topics: Humans; Nucleosides; Amides; Purine Nucleosides; Glucuronates
PubMed: 38095428
DOI: 10.1002/cmdc.202300608