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1.
Nucleic Acids Res ; 50(D1): D27-D38, 2022 01 07.
Article in English | MEDLINE | ID: covidwho-1758797

ABSTRACT

The National Genomics Data Center (NGDC), part of the China National Center for Bioinformation (CNCB), provides a family of database resources to support global research in both academia and industry. With the explosively accumulated multi-omics data at ever-faster rates, CNCB-NGDC is constantly scaling up and updating its core database resources through big data archive, curation, integration and analysis. In the past year, efforts have been made to synthesize the growing data and knowledge, particularly in single-cell omics and precision medicine research, and a series of resources have been newly developed, updated and enhanced. Moreover, CNCB-NGDC has continued to daily update SARS-CoV-2 genome sequences, variants, haplotypes and literature. Particularly, OpenLB, an open library of bioscience, has been established by providing easy and open access to a substantial number of abstract texts from PubMed, bioRxiv and medRxiv. In addition, Database Commons is significantly updated by cataloguing a full list of global databases, and BLAST tools are newly deployed to provide online sequence search services. All these resources along with their services are publicly accessible at https://ngdc.cncb.ac.cn.


Subject(s)
Databases, Factual , Animals , China , Computational Biology , Databases, Genetic , Databases, Pharmaceutical , Dogs , Epigenome , Genome, Human , Genome, Viral , Genomics , Humans , Methylation , Neoplasms/genetics , Neoplasms/pathology , Regeneration , SARS-CoV-2/genetics , Single-Cell Analysis , Software , Synthetic Biology
2.
J Immunol Res ; 2022: 1433323, 2022.
Article in English | MEDLINE | ID: covidwho-1697599

ABSTRACT

We performed a database mining on 102 transcriptomic datasets for the expressions of 29 m6A-RNA methylation (epitranscriptomic) regulators (m6A-RMRs) in 41 diseases and cancers and made significant findings: (1) a few m6A-RMRs were upregulated; and most m6A-RMRs were downregulated in sepsis, acute respiratory distress syndrome, shock, and trauma; (2) half of 29 m6A-RMRs were downregulated in atherosclerosis; (3) inflammatory bowel disease and rheumatoid arthritis modulated m6A-RMRs more than lupus and psoriasis; (4) some organ failures shared eight upregulated m6A-RMRs; end-stage renal failure (ESRF) downregulated 85% of m6A-RMRs; (5) Middle-East respiratory syndrome coronavirus infections modulated m6A-RMRs the most among viral infections; (6) proinflammatory oxPAPC modulated m6A-RMRs more than DAMP stimulation including LPS and oxLDL; (7) upregulated m6A-RMRs were more than downregulated m6A-RMRs in cancer types; five types of cancers upregulated ≥10 m6A-RMRs; (8) proinflammatory M1 macrophages upregulated seven m6A-RMRs; (9) 86% of m6A-RMRs were differentially expressed in the six clusters of CD4+Foxp3+ immunosuppressive Treg, and 8 out of 12 Treg signatures regulated m6A-RMRs; (10) immune checkpoint receptors TIM3, TIGIT, PD-L2, and CTLA4 modulated m6A-RMRs, and inhibition of CD40 upregulated m6A-RMRs; (11) cytokines and interferons modulated m6A-RMRs; (12) NF-κB and JAK/STAT pathways upregulated more than downregulated m6A-RMRs whereas TP53, PTEN, and APC did the opposite; (13) methionine-homocysteine-methyl cycle enzyme Mthfd1 downregulated more than upregulated m6A-RMRs; (14) m6A writer RBM15 and one m6A eraser FTO, H3K4 methyltransferase MLL1, and DNA methyltransferase, DNMT1, regulated m6A-RMRs; and (15) 40 out of 165 ROS regulators were modulated by m6A eraser FTO and two m6A writers METTL3 and WTAP. Our findings shed new light on the functions of upregulated m6A-RMRs in 41 diseases and cancers, nine cellular and molecular mechanisms, novel therapeutic targets for inflammatory disorders, metabolic cardiovascular diseases, autoimmune diseases, organ failures, and cancers.


Subject(s)
Atherosclerosis/genetics , Epigenesis, Genetic , Neoplasms/genetics , RNA, Messenger/metabolism , Reactive Oxygen Species/metabolism , Adenosine/analogs & derivatives , Adenosine/metabolism , Autoimmune Diseases/genetics , Datasets as Topic , Gene Expression Profiling , Humans , Inflammation/genetics , Metabolic Diseases/genetics , Methylation
3.
Nature ; 602(7896): 343-348, 2022 02.
Article in English | MEDLINE | ID: covidwho-1671588

ABSTRACT

Carbapenems are antibiotics of last resort in the clinic. Owing to their potency and broad-spectrum activity, they are an important part of the antibiotic arsenal. The vital role of carbapenems is exemplified by the approval acquired by Merck from the US Food and Drug Administration (FDA) for the use of an imipenem combination therapy to treat the increased levels of hospital-acquired and ventilator-associated bacterial pneumonia that have occurred during the COVID-19 pandemic1. The C6 hydroxyethyl side chain distinguishes the clinically used carbapenems from the other classes of ß-lactam antibiotics and is responsible for their low susceptibility to inactivation by occluding water from the ß-lactamase active site2. The construction of the C6 hydroxyethyl side chain is mediated by cobalamin- or B12-dependent radical S-adenosylmethionine (SAM) enzymes3. These radical SAM methylases (RSMTs) assemble the alkyl backbone by sequential methylation reactions, and thereby underlie the therapeutic usefulness of clinically used carbapenems. Here we present X-ray crystal structures of TokK, a B12-dependent RSMT that catalyses three-sequential methylations during the biosynthesis of asparenomycin A. These structures, which contain the two metallocofactors of the enzyme and were determined in the presence and absence of a carbapenam substrate, provide a visualization of a B12-dependent RSMT that uses the radical mechanism that is shared by most of these enzymes. The structures provide insight into the stereochemistry of initial C6 methylation and suggest that substrate positioning governs the rate of each methylation event.


Subject(s)
Carbapenems/biosynthesis , Methyltransferases/chemistry , Methyltransferases/metabolism , S-Adenosylmethionine/metabolism , Streptomyces/enzymology , Thienamycins/biosynthesis , Vitamin B 12/metabolism , Binding Sites , Biocatalysis , Coenzymes/metabolism , Crystallography, X-Ray , Kinetics , Methylation , Models, Molecular , Protein Binding , Protein Domains , Streptomyces/metabolism , beta-Lactamase Inhibitors/metabolism , beta-Lactamases/chemistry , beta-Lactamases/metabolism
4.
Nucleic Acids Res ; 50(2): 635-650, 2022 01 25.
Article in English | MEDLINE | ID: covidwho-1621653

ABSTRACT

Coronaviral methyltransferases (MTases), nsp10/16 and nsp14, catalyze the last two steps of viral RNA-cap creation that takes place in cytoplasm. This cap is essential for the stability of viral RNA and, most importantly, for the evasion of innate immune system. Non-capped RNA is recognized by innate immunity which leads to its degradation and the activation of antiviral immunity. As a result, both coronaviral MTases are in the center of scientific scrutiny. Recently, X-ray and cryo-EM structures of both enzymes were solved even in complex with other parts of the viral replication complex. High-throughput screening as well as structure-guided inhibitor design have led to the discovery of their potent inhibitors. Here, we critically summarize the tremendous advancement of the coronaviral MTase field since the beginning of COVID pandemic.


Subject(s)
Antiviral Agents/chemistry , Antiviral Agents/pharmacology , Coronavirus/drug effects , Coronavirus/enzymology , Methyltransferases/antagonists & inhibitors , Methyltransferases/chemistry , Methyltransferases/metabolism , Amino Acid Sequence , Amino Acids/chemistry , Binding Sites , Coronavirus/genetics , Drug Discovery , Humans , Methylation , Models, Molecular , Molecular Conformation , Molecular Structure , Protein Binding , RNA, Viral/chemistry , RNA, Viral/genetics , RNA, Viral/metabolism , Structure-Activity Relationship
5.
Epigenomics ; 14(3): 153-162, 2022 02.
Article in English | MEDLINE | ID: covidwho-1622527

ABSTRACT

Smoking could predispose individuals to a more severe COVID-19 by upregulating a particular gene known as mdig, which is mediated through a number of well-known histone modifications. Smoking might regulate the transcription-activating H3K4me3 mark, along with the transcription-repressing H3K9me3 and H3K27me3 marks, in a way to favor SARS-CoV-2 entry by enhancing the expression of ACE2, NRP1 and NRP2, AT1R, CTSD and CTSL, PGE2 receptors 2-4, SLC6A20 and IL-6, all of which interact either directly or indirectly with important receptors, facilitating viral entry in COVID-19.


Lay abstract The role of smoking in development of several respiratory diseases has been clearly established. A significant proportion of these deleterious effects is mediated through epigenetic mechanisms, particularly histone modifications. Recent evidence indicates that smoking induces the expression of a mediator known as mdig, which in turn alters the transcription of several key proteins that have been implicated in development of COVID-19.


Subject(s)
COVID-19/genetics , Dioxygenases/genetics , Epigenesis, Genetic , Histone Demethylases/genetics , Histones/genetics , Nuclear Proteins/genetics , Protein Processing, Post-Translational , Smoking/genetics , Angiotensin-Converting Enzyme 2/genetics , Angiotensin-Converting Enzyme 2/metabolism , COVID-19/diagnosis , COVID-19/metabolism , COVID-19/virology , Cathepsin D/genetics , Cathepsin D/metabolism , Cathepsin L/genetics , Cathepsin L/metabolism , Dioxygenases/metabolism , Histone Demethylases/metabolism , Histones/metabolism , Humans , Interleukin-6/genetics , Interleukin-6/metabolism , Membrane Transport Proteins/genetics , Membrane Transport Proteins/metabolism , Methylation , Neuropilin-1/genetics , Neuropilin-1/metabolism , Neuropilin-2/genetics , Neuropilin-2/metabolism , Nuclear Proteins/metabolism , Protein Isoforms/genetics , Protein Isoforms/metabolism , Receptor, Angiotensin, Type 1/genetics , Receptor, Angiotensin, Type 1/metabolism , Receptors, Prostaglandin E/genetics , Receptors, Prostaglandin E/metabolism , Risk Factors , SARS-CoV-2/genetics , SARS-CoV-2/growth & development , SARS-CoV-2/metabolism , Smoking/metabolism , Smoking/pathology , Virus Internalization
6.
STAR Protoc ; 3(1): 101067, 2022 03 18.
Article in English | MEDLINE | ID: covidwho-1595326

ABSTRACT

N 6 -methylation of adenosine (m6A) is the most abundant internal mRNA modification and is an important post-transcriptional regulator of gene expression. Here, we describe a protocol for methylated RNA immunoprecipitation sequencing (MeRIP-Seq) to detect and quantify m6A modifications in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA. The protocol is optimized for low viral RNA levels and is readily adaptable for other applications. For complete details on the use and execution of this protocol, please refer to Li et al. (2021).


Subject(s)
Adenosine/analogs & derivatives , Immunoprecipitation/methods , Sequence Analysis, RNA/methods , Adenosine/analysis , Adenosine/genetics , Animals , COVID-19/genetics , Caco-2 Cells , Chlorocebus aethiops , Gene Expression/genetics , Gene Expression Regulation/genetics , Genetic Techniques , HEK293 Cells , Humans , Methylation , RNA/chemistry , RNA/genetics , RNA Processing, Post-Transcriptional , RNA, Viral/metabolism , SARS-CoV-2/genetics , SARS-CoV-2/pathogenicity , Vero Cells
7.
Dis Markers ; 2021: 7686374, 2021.
Article in English | MEDLINE | ID: covidwho-1595046

ABSTRACT

Objective: S-Adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) are indicators of global transmethylation and may play an important role as markers of severity of COVID-19. Methods: The levels of plasma SAM and SAH were determined in patients admitted with COVID-19 (n = 56, mean age = 61). Lung injury was identified by computed tomography (CT) in accordance with the CT0-4 classification. Results: SAM was found to be a potential marker of lung damage risk in COVID-19 patients (SAM > 80 nM; CT3,4 vs. CT 0-2: relative ratio (RR) was 3.0; p = 0.0029). SAM/SAH > 6.0 was also found to be a marker of lung injury (CT2-4 vs. CT0,1: RR = 3.47, p = 0.0004). There was a negative association between SAM and glutathione level (ρ = -0.343, p = 0.011). Interleukin-6 (IL-6) levels were associated with SAM (ρ = 0.44, p = 0.01) and SAH (ρ = 0.534, p = 0.001) levels. Conclusions: A high SAM level and high methylation index are associated with the risk of lung injury in patients with COVID-19. The association of SAM with IL-6 and glutathione indicates an important role of transmethylation in the development of cytokine imbalance and oxidative stress in patients with COVID-19.


Subject(s)
COVID-19/complications , Lung Injury/blood , S-Adenosylhomocysteine/blood , S-Adenosylmethionine/blood , SARS-CoV-2 , Adult , Aged , Aged, 80 and over , Atherosclerosis/epidemiology , Biomarkers , COVID-19/epidemiology , Comorbidity , Diabetes Mellitus/epidemiology , Female , Glutathione/blood , Humans , Hypertension/epidemiology , Interleukin-6/blood , Lung Injury/diagnostic imaging , Lung Injury/etiology , Male , Methylation , Middle Aged , Military Personnel , Risk , Tomography, X-Ray Computed , Young Adult
8.
Int J Mol Sci ; 23(1)2021 Dec 28.
Article in English | MEDLINE | ID: covidwho-1580696

ABSTRACT

The inhibition of key enzymes that may contain the viral replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have assumed central importance in drug discovery projects. Nonstructural proteins (nsps) are essential for RNA capping and coronavirus replication since it protects the virus from host innate immune restriction. In particular, nonstructural protein 16 (nsp16) in complex with nsp10 is a Cap-0 binding enzyme. The heterodimer formed by nsp16-nsp10 methylates the 5'-end of virally encoded mRNAs to mimic cellular mRNAs and thus it is one of the enzymes that is a potential target for antiviral therapy. In this study, we have evaluated the mechanism of the 2'-O methylation of the viral mRNA cap using hybrid quantum mechanics/molecular mechanics (QM/MM) approach. It was found that the calculated free energy barriers obtained at M062X/6-31+G(d,p) is in agreement with experimental observations. Overall, we provide a detailed molecular analysis of the catalytic mechanism involving the 2'-O methylation of the viral mRNA cap and, as expected, the results demonstrate that the TS stabilization is critical for the catalysis.


Subject(s)
Methyltransferases/metabolism , RNA Caps/chemistry , RNA Caps/metabolism , SARS-CoV-2/enzymology , SARS-CoV-2/genetics , Viral Nonstructural Proteins/metabolism , Viral Regulatory and Accessory Proteins/metabolism , Biocatalysis , Biomechanical Phenomena , Methylation , Methyltransferases/chemistry , Molecular Dynamics Simulation , Quantum Theory , RNA Processing, Post-Transcriptional , Viral Nonstructural Proteins/chemistry , Viral Regulatory and Accessory Proteins/chemistry
9.
Biochem J ; 478(14): 2789-2791, 2021 07 30.
Article in English | MEDLINE | ID: covidwho-1526112

ABSTRACT

Post-translational modifications (PTMs) on histone proteins are known as epigenetic marks that demarcate the status of chromatin. These modifications are 'read' by specific reader proteins, which in turn recruit additional factors to modulate chromatin accessibility and the activity of the underlying DNA. Accumulating evidence suggests that these modifications are not restricted solely to histones, many non-histone proteins may function in a similar way through mimicking the histones. In this commentary, we briefly discuss a systematic study of the discovery of histone H3 N-terminal mimicry proteins (H3TMs), and their implications in chromatin regulation and drug discoveries.


Subject(s)
Chromatin/metabolism , DNA/metabolism , Histones/metabolism , Protein Processing, Post-Translational , Animals , Chromatin/genetics , Chromatin Assembly and Disassembly , DNA/genetics , Humans , Lysine/metabolism , Methylation , Models, Biological
10.
Nucleic Acids Res ; 50(D1): D27-D38, 2022 01 07.
Article in English | MEDLINE | ID: covidwho-1493883

ABSTRACT

The National Genomics Data Center (NGDC), part of the China National Center for Bioinformation (CNCB), provides a family of database resources to support global research in both academia and industry. With the explosively accumulated multi-omics data at ever-faster rates, CNCB-NGDC is constantly scaling up and updating its core database resources through big data archive, curation, integration and analysis. In the past year, efforts have been made to synthesize the growing data and knowledge, particularly in single-cell omics and precision medicine research, and a series of resources have been newly developed, updated and enhanced. Moreover, CNCB-NGDC has continued to daily update SARS-CoV-2 genome sequences, variants, haplotypes and literature. Particularly, OpenLB, an open library of bioscience, has been established by providing easy and open access to a substantial number of abstract texts from PubMed, bioRxiv and medRxiv. In addition, Database Commons is significantly updated by cataloguing a full list of global databases, and BLAST tools are newly deployed to provide online sequence search services. All these resources along with their services are publicly accessible at https://ngdc.cncb.ac.cn.


Subject(s)
Databases, Factual , Animals , China , Computational Biology , Databases, Genetic , Databases, Pharmaceutical , Dogs , Epigenome , Genome, Human , Genome, Viral , Genomics , Humans , Methylation , Neoplasms/genetics , Neoplasms/pathology , Regeneration , SARS-CoV-2/genetics , Single-Cell Analysis , Software , Synthetic Biology
11.
Viruses ; 13(11)2021 10 20.
Article in English | MEDLINE | ID: covidwho-1481015

ABSTRACT

The causative agent of COVID-19 pandemic, SARS-CoV-2, has a 29,903 bases positive-sense single-stranded RNA genome. RNAs exhibit about 150 modified bases that are essential for proper function. Among internal modified bases, the N6-methyladenosine, or m6A, is the most frequent, and is implicated in SARS-CoV-2 immune response evasion. Although the SARS-CoV-2 genome is RNA, almost all genomes sequenced thus far are, in fact, reverse transcribed complementary DNAs. This process reduces the true complexity of these viral genomes because the incorporation of dNTPs hides RNA base modifications. Here, we present an initial exploration of Nanopore direct RNA sequencing to assess the m6A residues in the SARS-CoV-2 sequences of ORF3a, E, M, ORF6, ORF7a, ORF7b, ORF8, N, ORF10 and the 3'-untranslated region. We identified fifteen m6A methylated positions, of which, six are in ORF N. Additionally, because m6A is associated with the DRACH motif, we compared its distribution in major SARS-CoV-2 variants. Although DRACH is highly conserved among variants, we show that variants Beta and Eta have a fourth position C > U change in DRACH at 28,884b that could affect methylation. This is the first report of direct RNA sequencing of a Brazilian SARS-CoV-2 sample coupled with the identification of modified bases.


Subject(s)
Adenosine/analogs & derivatives , COVID-19/virology , Immune Evasion/genetics , RNA, Viral/metabolism , SARS-CoV-2/genetics , 3' Untranslated Regions , Adenosine/metabolism , Animals , Chlorocebus aethiops , Genome, Viral , Humans , Methylation , Nanopore Sequencing/methods , Open Reading Frames , Sequence Analysis, RNA/methods , Vero Cells
12.
Int J Mol Sci ; 22(20)2021 Oct 12.
Article in English | MEDLINE | ID: covidwho-1480792

ABSTRACT

The infection of mammalian cells by enveloped viruses is triggered by the interaction of viral envelope glycoproteins with the glycosaminoglycan, heparan sulfate. By mimicking this carbohydrate, some anionic polysaccharides can block this interaction and inhibit viral entry and infection. As heparan sulfate carries both carboxyl and sulfate groups, this work focused on the derivatization of a (1→3)(1→6)-ß-D-glucan, botryosphaeran, with these negatively-charged groups in an attempt to improve its antiviral activity. Carboxyl and sulfonate groups were introduced by carboxymethylation and sulfonylation reactions, respectively. Three derivatives with the same degree of carboxymethylation (0.9) and different degrees of sulfonation (0.1; 0.2; 0.4) were obtained. All derivatives were chemically characterized and evaluated for their antiviral activity against herpes (HSV-1, strains KOS and AR) and dengue (DENV-2) viruses. Carboxymethylated botryosphaeran did not inhibit the viruses, while all sulfonated-carboxymethylated derivatives were able to inhibit HSV-1. DENV-2 was inhibited only by one of these derivatives with an intermediate degree of sulfonation (0.2), demonstrating that the dengue virus is more resistant to anionic ß-D-glucans than the Herpes simplex virus. By comparison with a previous study on the antiviral activity of sulfonated botryosphaerans, we conclude that the presence of carboxymethyl groups might have a detrimental effect on antiviral activity.


Subject(s)
Antiviral Agents/pharmacology , Dengue Virus/drug effects , Herpesviridae/drug effects , Sulfonic Acids/chemistry , beta-Glucans/chemistry , Animals , Antiviral Agents/chemistry , Cell Survival/drug effects , Chlorocebus aethiops , Dengue Virus/physiology , Glucans/chemistry , Glucans/pharmacology , Herpesviridae/physiology , Methylation , Vero Cells , Virus Internalization/drug effects , beta-Glucans/pharmacology
13.
Int J Mol Sci ; 22(19)2021 Oct 01.
Article in English | MEDLINE | ID: covidwho-1463708

ABSTRACT

Social behavioral changes, including social isolation or loneliness, increase the risk for stress-related disorders, such as major depressive disorder, posttraumatic stress disorder (PTSD), and suicide, which share a strong neuroinflammatory etiopathogenetic component. The peroxisome-proliferator activated receptor (PPAR)-α, a newly discovered target involved in emotional behavior regulation, is a ligand-activated nuclear receptor and a transcription factor that, following stimulation by endogenous or synthetic ligands, may induce neuroprotective effects by modulating neuroinflammation, and improve anxiety and depression-like behaviors by enhancing neurosteroid biosynthesis. How stress affects epigenetic mechanisms with downstream effects on inflammation and emotional behavior remains poorly understood. We studied the effects of 4-week social isolation, using a mouse model of PTSD/suicide-like behavior, on hippocampal PPAR-α epigenetic modification. Decreased PPAR-α expression in the hippocampus of socially isolated mice was associated with increased levels of methylated cytosines of PPAR-α gene CpG-rich fragments and deficient neurosteroid biosynthesis. This effect was associated with increased histone deacetylases (HDAC)1, methyl-cytosine binding protein (MeCP)2 and decreased ten-eleven translocator (TET)2 expression, which favor hypermethylation. These alterations were associated with increased TLR-4 and pro-inflammatory markers (e.g., TNF-α,), mediated by NF-κB signaling in the hippocampus of aggressive mice. This study contributes the first evidence of stress-induced brain PPAR-α epigenetic regulation. Social isolation stress may constitute a risk factor for inflammatory-based psychiatric disorders associated with neurosteroid deficits, and targeting epigenetic marks linked to PPAR-α downregulation may offer a valid therapeutic approach.


Subject(s)
Aggression , Hippocampus/metabolism , Inflammation/etiology , PPAR alpha/genetics , Social Isolation , Stress, Psychological , Aggression/psychology , Animals , Behavior, Animal , Chromatin Assembly and Disassembly , CpG Islands , Disease Models, Animal , Disease Susceptibility , Epigenesis, Genetic , Gene Expression , Inflammation/metabolism , Inflammation Mediators/metabolism , Male , Methylation , Mice , PPAR alpha/metabolism , Promoter Regions, Genetic , Signal Transduction
14.
Sci Rep ; 11(1): 20012, 2021 10 08.
Article in English | MEDLINE | ID: covidwho-1462029

ABSTRACT

There are currently no cures for coronavirus infections, making the prevention of infections the only course open at the present time. The COVID-19 pandemic has been difficult to prevent, as the infection is spread by respiratory droplets and thus effective, scalable and safe preventive interventions are urgently needed. We hypothesise that preventing viral entry into mammalian nasal epithelial cells may be one way to limit the spread of COVID-19. Here we show that N-palmitoyl-N-monomethyl-N,N-dimethyl-N,N,N-trimethyl-6-O-glycolchitosan (GCPQ), a positively charged polymer that has been through an extensive Good Laboratory Practice toxicology screen, is able to reduce the infectivity of SARS-COV-2 in A549ACE2+ and Vero E6 cells with a log removal value of - 3 to - 4 at a concentration of 10-100 µg/ mL (p < 0.05 compared to untreated controls) and to limit infectivity in human airway epithelial cells at a concentration of 500 µg/ mL (p < 0.05 compared to untreated controls). In vivo studies using transgenic mice expressing the ACE-2 receptor, dosed nasally with SARS-COV-2 (426,000 TCID50/mL) showed a trend for nasal GCPQ (20 mg/kg) to inhibit viral load in the respiratory tract and brain, although the study was not powered to detect statistical significance. GCPQ's electrostatic binding to the virus, preventing viral entry into the host cells, is the most likely mechanism of viral inhibition. Radiolabelled GCPQ studies in mice show that at a dose of 10 mg/kg, GCPQ has a long residence time in mouse nares, with 13.1% of the injected dose identified from SPECT/CT in the nares, 24 h after nasal dosing. With a no observed adverse effect level of 18 mg/kg in rats, following a 28-day repeat dose study, clinical testing of this polymer, as a COVID-19 prophylactic is warranted.


Subject(s)
Antiviral Agents/therapeutic use , COVID-19/drug therapy , Nasal Sprays , SARS-CoV-2/drug effects , A549 Cells , Animals , Antiviral Agents/administration & dosage , Chlorocebus aethiops , Humans , Male , Methylation , Mice, Inbred BALB C , Mice, Transgenic , SARS-CoV-2/physiology , Surface-Active Agents/administration & dosage , Surface-Active Agents/therapeutic use , Vero Cells , Viral Load/drug effects
15.
Sci Signal ; 14(689)2021 06 29.
Article in English | MEDLINE | ID: covidwho-1406596

ABSTRACT

Capping of viral messenger RNAs is essential for efficient translation, for virus replication, and for preventing detection by the host cell innate response system. The SARS-CoV-2 genome encodes the 2'-O-methyltransferase nsp16, which, when bound to the coactivator nsp10, uses S-adenosylmethionine (SAM) as a donor to transfer a methyl group to the first ribonucleotide of the mRNA in the final step of viral mRNA capping. Here, we provide biochemical and structural evidence that this reaction requires divalent cations, preferably Mn2+, and a coronavirus-specific four-residue insert. We determined the x-ray structures of the SARS-CoV-2 2'-O-methyltransferase (the nsp16-nsp10 heterodimer) in complex with its reaction substrates, products, and divalent metal cations. These structural snapshots revealed that metal ions and the insert stabilize interactions between the capped RNA and nsp16, resulting in the precise alignment of the ribonucleotides in the active site. Comparison of available structures of 2'-O-methyltransferases with capped RNAs from different organisms revealed that the four-residue insert unique to coronavirus nsp16 alters the backbone conformation of the capped RNA in the binding groove, thereby promoting catalysis. This insert is highly conserved across coronaviruses, and its absence in mammalian methyltransferases makes this region a promising site for structure-guided drug design of selective coronavirus inhibitors.


Subject(s)
COVID-19/virology , RNA Caps/metabolism , RNA, Viral/metabolism , SARS-CoV-2/metabolism , Viral Nonstructural Proteins/metabolism , Amino Acid Sequence , Catalytic Domain , Crystallography, X-Ray , Humans , Manganese/metabolism , Methylation , Methyltransferases/chemistry , Methyltransferases/genetics , Methyltransferases/metabolism , Models, Molecular , Nucleic Acid Conformation , RNA Caps/chemistry , RNA Caps/genetics , RNA Stability , RNA, Messenger/chemistry , RNA, Messenger/genetics , RNA, Messenger/metabolism , RNA, Viral/chemistry , RNA, Viral/genetics , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , S-Adenosylmethionine/chemistry , S-Adenosylmethionine/metabolism , SARS-CoV-2/genetics , Signal Transduction , Substrate Specificity , Viral Nonstructural Proteins/chemistry , Viral Nonstructural Proteins/genetics
16.
Viruses ; 13(9)2021 08 30.
Article in English | MEDLINE | ID: covidwho-1390783

ABSTRACT

The ongoing COVID-19 pandemic exemplifies the general need to better understand viral infections. The positive single-strand RNA genome of its causative agent, the SARS coronavirus 2 (SARS-CoV-2), encodes all viral enzymes. In this work, we focused on one particular methyltransferase (MTase), nsp16, which, in complex with nsp10, is capable of methylating the first nucleotide of a capped RNA strand at the 2'-O position. This process is part of a viral capping system and is crucial for viral evasion of the innate immune reaction. In light of recently discovered non-canonical RNA caps, we tested various dinucleoside polyphosphate-capped RNAs as substrates for nsp10-nsp16 MTase. We developed an LC-MS-based method and discovered four types of capped RNA (m7Gp3A(G)- and Gp3A(G)-RNA) that are substrates of the nsp10-nsp16 MTase. Our technique is an alternative to the classical isotope labelling approach for the measurement of 2'-O-MTase activity. Further, we determined the IC50 value of sinefungin to illustrate the use of our approach for inhibitor screening. In the future, this approach may be an alternative technique to the radioactive labelling method for screening inhibitors of any type of 2'-O-MTase.


Subject(s)
COVID-19/virology , Methyltransferases/metabolism , SARS-CoV-2/enzymology , Viral Nonstructural Proteins/metabolism , Viral Regulatory and Accessory Proteins/metabolism , Chromatography, Liquid , Gene Expression Regulation, Viral , Humans , Mass Spectrometry , Methylation , Methyltransferases/genetics , RNA Caps , RNA, Viral/genetics , SARS-CoV-2/genetics , Substrate Specificity , Viral Nonstructural Proteins/genetics , Viral Regulatory and Accessory Proteins/genetics
17.
Angew Chem Int Ed Engl ; 60(24): 13280-13286, 2021 06 07.
Article in English | MEDLINE | ID: covidwho-1384109

ABSTRACT

Eukaryotic mRNAs are emerging modalities for protein replacement therapy and vaccination. Their 5' cap is important for mRNA translation and immune response and can be naturally methylated at different positions by S-adenosyl-l-methionine (AdoMet)-dependent methyltransferases (MTases). We report on the cosubstrate scope of the MTase CAPAM responsible for methylation at the N6 -position of adenosine start nucleotides using synthetic AdoMet analogs. The chemo-enzymatic propargylation enabled production of site-specifically modified reporter-mRNAs. These cap-propargylated mRNAs were efficiently translated and showed ≈3-fold increased immune response in human cells. The same effects were observed when the receptor binding domain (RBD) of SARS-CoV-2-a currently tested epitope for mRNA vaccination-was used. Site-specific chemo-enzymatic modification of eukaryotic mRNA may thus be a suitable strategy to modulate translation and immune response of mRNAs for future therapeutic applications.


Subject(s)
RNA Caps/immunology , RNA, Messenger/immunology , COVID-19/pathology , COVID-19/virology , Chromatography, High Pressure Liquid , Genes, Reporter , HEK293 Cells , Humans , Mass Spectrometry , Methylation , Methyltransferases/metabolism , Protein Biosynthesis , Protein Domains/genetics , Protein Domains/immunology , RNA Caps/analysis , RNA Caps/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , S-Adenosylmethionine/chemistry , S-Adenosylmethionine/immunology , S-Adenosylmethionine/metabolism , SARS-CoV-2/genetics , SARS-CoV-2/isolation & purification , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology
18.
Genes Dev ; 35(15-16): 1123-1141, 2021 08 01.
Article in English | MEDLINE | ID: covidwho-1322683

ABSTRACT

Spliceosomal small nuclear RNAs (snRNAs) are modified by small Cajal body (CB)-specific ribonucleoproteins (scaRNPs) to ensure snRNP biogenesis and pre-mRNA splicing. However, the function and subcellular site of snRNA modification are largely unknown. We show that CB localization of the protein Nopp140 is essential for concentration of scaRNPs in that nuclear condensate; and that phosphorylation by casein kinase 2 (CK2) at ∼80 serines targets Nopp140 to CBs. Transiting through CBs, snRNAs are apparently modified by scaRNPs. Indeed, Nopp140 knockdown-mediated release of scaRNPs from CBs severely compromises 2'-O-methylation of spliceosomal snRNAs, identifying CBs as the site of scaRNP catalysis. Additionally, alternative splicing patterns change indicating that these modifications in U1, U2, U5, and U12 snRNAs safeguard splicing fidelity. Given the importance of CK2 in this pathway, compromised splicing could underlie the mode of action of small molecule CK2 inhibitors currently considered for therapy in cholangiocarcinoma, hematological malignancies, and COVID-19.


Subject(s)
Interstitial Cells of Cajal/metabolism , Methylation , Nuclear Proteins/metabolism , Phosphoproteins/metabolism , RNA Splicing , RNA, Small Nuclear/metabolism , COVID-19/drug therapy , Casein Kinase II/antagonists & inhibitors , Casein Kinase II/metabolism , Cholangiocarcinoma/drug therapy , Hematologic Neoplasms/drug therapy , Humans , Phosphorylation , RNA, Small Nuclear/chemistry , Ribonucleoproteins/metabolism , Spliceosomes/genetics
19.
mBio ; 12(4): e0106721, 2021 08 31.
Article in English | MEDLINE | ID: covidwho-1297962

ABSTRACT

The coronavirus disease 2019 pandemic caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is an ongoing global public crisis. Although viral RNA modification has been reported based on the transcriptome architecture, the types and functions of RNA modification are still unknown. In this study, we evaluated the roles of RNA N6-methyladenosine (m6A) modification in SARS-CoV-2. Our methylated RNA immunoprecipitation sequencing (MeRIP-Seq) and Nanopore direct RNA sequencing (DRS) analysis showed that SARS-CoV-2 RNA contained m6A modification. Moreover, SARS-CoV-2 infection not only increased the expression of methyltransferase-like 3 (METTL3) but also altered its distribution. Modification of METTL3 expression by short hairpin RNA or plasmid transfection for knockdown or overexpression, respectively, affected viral replication. Furthermore, the viral key protein RdRp interacted with METTL3, and METTL3 was distributed in both the nucleus and cytoplasm in the presence of RdRp. RdRp appeared to modulate the sumoylation and ubiquitination of METTL3 via an unknown mechanism. Taken together, our findings demonstrated that the host m6A modification complex interacted with viral proteins to modulate SARS-CoV-2 replication. IMPORTANCE Internal chemical modifications of viral RNA play key roles in the regulation of viral replication and gene expression. Although potential internal modifications have been reported in SARS-CoV-2 RNA, the function of the SARS-CoV-2 N6-methyladenosine (m6A) modification in the viral life cycle is unclear. In the current study, we demonstrated that SARS-CoV-2 RNA underwent m6A modification by host m6A machinery. SARS-CoV-2 infection altered the expression pattern of methyltransferases and demethylases, while the expression level of methyltransferase-like 3 (METTL3) and fat mass and obesity-associated protein (FTO) was linked to the viral replication. Further study showed that METTL3 interacted with viral RNA polymerase RNA-dependent RNA polymerase (RdRp), which influenced not only the distribution but also the posttranslational modification of METTL3. Our study provided evidence that host m6A components interacted with viral proteins to modulate viral replication.


Subject(s)
Adenosine/analogs & derivatives , Methyltransferases/genetics , Methyltransferases/metabolism , SARS-CoV-2/growth & development , Virus Replication/genetics , Adenosine/chemistry , Adenosine/genetics , Alpha-Ketoglutarate-Dependent Dioxygenase FTO/metabolism , COVID-19/pathology , Gene Expression Regulation/genetics , Humans , Methylation , Protein Processing, Post-Translational/physiology , RNA, Viral/chemistry , RNA, Viral/genetics , RNA-Dependent RNA Polymerase/genetics , SARS-CoV-2/genetics
20.
SLAS Discov ; 26(9): 1200-1211, 2021 10.
Article in English | MEDLINE | ID: covidwho-1290310

ABSTRACT

The COVID-19 pandemic has clearly brought the healthcare systems worldwide to a breaking point, along with devastating socioeconomic consequences. The SARS-CoV-2 virus, which causes the disease, uses RNA capping to evade the human immune system. Nonstructural protein (nsp) 14 is one of the 16 nsps in SARS-CoV-2 and catalyzes the methylation of the viral RNA at N7-guanosine in the cap formation process. To discover small-molecule inhibitors of nsp14 methyltransferase (MTase) activity, we developed and employed a radiometric MTase assay to screen a library of 161 in-house synthesized S-adenosylmethionine (SAM) competitive MTase inhibitors and SAM analogs. Among six identified screening hits, SS148 inhibited nsp14 MTase activity with an IC50 value of 70 ± 6 nM and was selective against 20 human protein lysine MTases, indicating significant differences in SAM binding sites. Interestingly, DS0464 with an IC50 value of 1.1 ± 0.2 µM showed a bisubstrate competitive inhibitor mechanism of action. DS0464 was also selective against 28 out of 33 RNA, DNA, and protein MTases. The structure-activity relationship provided by these compounds should guide the optimization of selective bisubstrate nsp14 inhibitors and may provide a path toward a novel class of antivirals against COVID-19, and possibly other coronaviruses.


Subject(s)
COVID-19/genetics , Exoribonucleases/genetics , Protein Binding/genetics , SARS-CoV-2/genetics , Viral Nonstructural Proteins/genetics , Antiviral Agents/pharmacology , Binding Sites/genetics , COVID-19/virology , Humans , Methylation , Pandemics , RNA, Viral/genetics , SARS-CoV-2/pathogenicity , Virus Replication/genetics
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