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1.
Viruses ; 14(5)2022 05 23.
Article in English | MEDLINE | ID: covidwho-1875812

ABSTRACT

This review is an accompaniment to a Special Issue on "Retroviral RNA Processing". It discusses post-transcriptional regulation of retroviruses, ranging from the ancient foamy viruses to more modern viruses, such as HIV-1, HTLV-1, Rous sarcoma virus, murine leukemia virus, mouse mammary tumor virus, and Mason-Pfizer monkey virus. This review is not comprehensive. However, it tries to address some of the major questions in the field with examples of how different retroviruses express their genes. It is amazing that a single primary RNA transcript can have so many possible fates: genomic RNA, unspliced mRNA, and up to 50 different alternatively spliced mRNAs. This review will discuss the sorting of RNAs for packaging or translation, RNA nuclear export mechanisms, splicing, translation, RNA modifications, and avoidance of nonsense-mediated RNA decay.


Subject(s)
RNA, Viral , Retroviridae , Active Transport, Cell Nucleus , Animals , Leukemia Virus, Murine/genetics , Mice , RNA Processing, Post-Transcriptional , RNA, Messenger/metabolism , RNA, Viral/genetics , RNA, Viral/metabolism , Retroviridae/genetics , Retroviridae/metabolism
2.
Am J Physiol Cell Physiol ; 322(4): C787-C793, 2022 04 01.
Article in English | MEDLINE | ID: covidwho-1807579

ABSTRACT

Similar to epigenetic DNA modification, RNA can be methylated and altered for stability and processing. RNA modifications, namely, epitranscriptomes, involve the following three functions: writing, erasing, and reading of marks. Methods for measurement and position detection are useful for the assessment of cellular function and human disease biomarkers. After pyrimidine 5-methylcytosine was reported for the first time a hundred years ago, numerous techniques have been developed for studying nucleotide modifications, including RNAs. Recent studies have focused on high-throughput and direct measurements for investigating the precise function of epitranscriptomes, including the characterization of severe acute respiratory syndrome coronavirus 2. The current study presents an overview of the development of detection techniques for epitranscriptomic marks and briefs about the recent progress in this field.


Subject(s)
COVID-19 , Transcriptome , Epigenesis, Genetic , Humans , RNA/genetics , RNA/metabolism , RNA Processing, Post-Transcriptional , Transcriptome/genetics
3.
PLoS One ; 17(2): e0264025, 2022.
Article in English | MEDLINE | ID: covidwho-1714775

ABSTRACT

Experimental breakthroughs have provided unprecedented insights into the genes involved in cancer. The identification of such cancer driver genes is a major step in gaining a fuller understanding of oncogenesis and provides novel lists of potential therapeutic targets. A key area that requires additional study is the posttranscriptional control mechanisms at work in cancer driver genes. This is important not only for basic insights into the biology of cancer, but also to advance new therapeutic modalities that target RNA-an emerging field with great promise toward the treatment of various cancers. In the current study we performed an in silico analysis on the transcripts associated with 800 cancer driver genes (10,390 unique transcripts) that identified 179,190 secondary structural motifs with evidence of evolutionarily ordered structures with unusual thermodynamic stability. Narrowing to one transcript per gene, 35,426 predicted structures were subjected to phylogenetic comparisons of sequence and structural conservation. This identified 7,001 RNA secondary structures embedded in transcripts with evidence of covariation between paired sites, supporting structure models and suggesting functional significance. A select set of seven structures were tested in vitro for their ability to regulate gene expression; all were found to have significant effects. These results indicate potentially widespread roles for RNA structure in posttranscriptional control of human cancer driver genes.


Subject(s)
Evolution, Molecular , Neoplasms , Nucleic Acid Conformation , Phylogeny , RNA Processing, Post-Transcriptional , RNA Stability , RNA, Neoplasm , Humans , Neoplasms/genetics , Neoplasms/metabolism , RNA, Neoplasm/genetics , RNA, Neoplasm/metabolism
4.
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
5.
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
6.
Viruses ; 14(1)2021 12 30.
Article in English | MEDLINE | ID: covidwho-1580401

ABSTRACT

Medicinal chemistry optimization of a previously described stilbene inhibitor of HIV-1, 5350150 (2-(2-(5-nitro-2-thienyl)vinyl)quinoline), led to the identification of the thiazole-5-carboxamide derivative (GPS491), which retained potent anti-HIV-1 activity with reduced toxicity. In this report, we demonstrate that the block of HIV-1 replication by GPS491 is accompanied by a drastic inhibition of viral gene expression (IC50 ~ 0.25 µM), and alterations in the production of unspliced, singly spliced, and multiply spliced HIV-1 RNAs. GPS491 also inhibited the replication of adenovirus and multiple coronaviruses. Low µM doses of GPS491 reduced adenovirus infectious yield ~1000 fold, altered virus early gene expression/viral E1A RNA processing, blocked viral DNA amplification, and inhibited late (hexon) gene expression. Loss of replication of multiple coronaviruses (229E, OC43, SARS-CoV2) upon GPS491 addition was associated with the inhibition of viral structural protein expression and the formation of virus particles. Consistent with the observed changes in viral RNA processing, GPS491 treatment induced selective alterations in the accumulation/phosphorylation/function of splicing regulatory SR proteins. Our study establishes that a compound that impacts the activity of cellular factors involved in RNA processing can prevent the replication of several viruses with minimal effect on cell viability.


Subject(s)
Adenoviridae/drug effects , Antiviral Agents/pharmacology , Coronavirus/drug effects , HIV-1/drug effects , RNA Processing, Post-Transcriptional/drug effects , Thiazoles/pharmacology , Virus Replication/drug effects , Adenoviridae/physiology , Antiviral Agents/chemistry , Cell Line , Coronavirus/classification , Coronavirus/physiology , Gene Expression/drug effects , HIV-1/physiology , Humans , RNA Splicing Factors/metabolism , RNA, Viral/metabolism , Thiazoles/chemistry
7.
Eur J Immunol ; 51(7): 1641-1651, 2021 07.
Article in English | MEDLINE | ID: covidwho-1473829

ABSTRACT

Emerging life-threatening viruses have posed great challenges to public health. It is now increasingly clear that epigenetics plays a role in shaping host-virus interactions and there is a great need for a more thorough understanding of these intricate interactions through the epigenetic lens, which may represent potential therapeutic opportunities in the clinic. In this review, we highlight the current understanding of the roles of key epigenetic regulators - chromatin remodeling and histone modification - in modulating chromatin openness during host defense against virus. We also discuss how the RNA modification m6A (N6-methyladenosine) affects fundamental aspects of host-virus interactions. We conclude with future directions for uncovering more detailed functions that epigenetic regulation exerts on both host cells and viruses during infection.


Subject(s)
Antiviral Agents/immunology , Epigenesis, Genetic/genetics , Epigenesis, Genetic/immunology , Immunity, Innate/genetics , Immunity, Innate/immunology , Animals , Chromatin/genetics , Chromatin/immunology , Histones/genetics , Histones/immunology , Host Microbial Interactions/genetics , Host Microbial Interactions/immunology , Humans , RNA Processing, Post-Transcriptional/genetics , RNA Processing, Post-Transcriptional/immunology
8.
Front Immunol ; 12: 727861, 2021.
Article in English | MEDLINE | ID: covidwho-1477822

ABSTRACT

Inflammatory response is a host-protective mechanism against tissue injury or infections, but also has the potential to cause extensive immunopathology and tissue damage, as seen in many diseases, such as cardiovascular diseases, neurodegenerative diseases, metabolic syndrome and many other infectious diseases with public health concerns, such as Coronavirus Disease 2019 (COVID-19), if failure to resolve in a timely manner. Recent studies have uncovered a superfamily of endogenous chemical molecules that tend to resolve inflammatory responses and re-establish homeostasis without causing excessive damage to healthy cells and tissues. Among these, the monocyte chemoattractant protein-induced protein (MCPIP) family consisting of four members (MCPIP-1, -2, -3, and -4) has emerged as a group of evolutionarily conserved molecules participating in the resolution of inflammation. The focus of this review highlights the biological functions of MCPIP-1 (also known as Regnase-1), the best-studied member of this family, in the resolution of inflammatory response. As outlined in this review, MCPIP-1 acts on specific signaling pathways, in particular NFκB, to blunt production of inflammatory mediators, while also acts as an endonuclease controlling the stability of mRNA and microRNA (miRNA), leading to the resolution of inflammation, clearance of virus and dead cells, and promotion of tissue regeneration via its pleiotropic effects. Evidence from transgenic and knock-out mouse models revealed an involvement of MCPIP-1 expression in immune functions and in the physiology of the cardiovascular system, indicating that MCPIP-1 is a key endogenous molecule that governs normal resolution of acute inflammation and infection. In this review, we also discuss the current evidence underlying the roles of other members of the MCPIP family in the regulation of inflammatory processes. Further understanding of the proteins from this family will provide new insights into the identification of novel targets for both host effectors and microbial factors and will lead to new therapeutic treatments for infections and other inflammatory diseases.


Subject(s)
Gene Expression Regulation/genetics , Inflammation Mediators/metabolism , Inflammation/immunology , Ribonucleases/immunology , SARS-CoV-2/immunology , Transcription Factors/immunology , Animals , Apoptosis/genetics , COVID-19/immunology , Humans , Inflammation/pathology , Mice , NF-kappa B/metabolism , RNA Processing, Post-Transcriptional/genetics , Transcriptional Activation/immunology , Ubiquitination
9.
Genes Dev ; 35(13-14): 1005-1019, 2021 07 01.
Article in English | MEDLINE | ID: covidwho-1334329

ABSTRACT

N6-methyladenosine (m6A) is an abundant internal RNA modification, influencing transcript fate and function in uninfected and virus-infected cells. Installation of m6A by the nuclear RNA methyltransferase METTL3 occurs cotranscriptionally; however, the genomes of some cytoplasmic RNA viruses are also m6A-modified. How the cellular m6A modification machinery impacts coronavirus replication, which occurs exclusively in the cytoplasm, is unknown. Here we show that replication of SARS-CoV-2, the agent responsible for the COVID-19 pandemic, and a seasonal human ß-coronavirus HCoV-OC43, can be suppressed by depletion of METTL3 or cytoplasmic m6A reader proteins YTHDF1 and YTHDF3 and by a highly specific small molecule METTL3 inhibitor. Reduction of infectious titer correlates with decreased synthesis of viral RNAs and the essential nucleocapsid (N) protein. Sites of m6A modification on genomic and subgenomic RNAs of both viruses were mapped by methylated RNA immunoprecipitation sequencing (meRIP-seq). Levels of host factors involved in m6A installation, removal, and recognition were unchanged by HCoV-OC43 infection; however, nuclear localization of METTL3 and cytoplasmic m6A readers YTHDF1 and YTHDF2 increased. This establishes that coronavirus RNAs are m6A-modified and host m6A pathway components control ß-coronavirus replication. Moreover, it illustrates the therapeutic potential of targeting the m6A pathway to restrict coronavirus reproduction.


Subject(s)
Coronavirus OC43, Human/physiology , RNA Processing, Post-Transcriptional/genetics , SARS-CoV-2/physiology , Virus Replication/genetics , Adenosine/analogs & derivatives , Adenosine/genetics , Adenosine/metabolism , Cell Line , Coronavirus Infections/metabolism , Coronavirus Infections/virology , Gene Expression Regulation/drug effects , Host-Pathogen Interactions/drug effects , Humans , Methyltransferases/antagonists & inhibitors , Methyltransferases/metabolism , Nucleocapsid Proteins , RNA, Viral/metabolism , RNA-Binding Proteins/metabolism , Virus Replication/drug effects
10.
Cell Death Dis ; 12(8): 732, 2021 07 23.
Article in English | MEDLINE | ID: covidwho-1322464

ABSTRACT

Severe coronavirus disease 2019 (COVID-19) is characterized by symptoms of lymphopenia and multiorgan damage, but the underlying mechanisms remain unclear. To explore the function of N6-methyladenosine (m6A) modifications in COVID-19, we performed microarray analyses to comprehensively characterize the m6A epitranscriptome. The results revealed distinct global m6A profiles in severe and mild COVID-19 patients. Programmed cell death and inflammatory response were the major biological processes modulated by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Further, RBM15, a major m6A methyltransferase, was significantly elevated and positively correlated with disease severity. Silencing RBM15 drastically reduced lymphocyte death in vitro. Knockdown of RBM15 remarkably suppressed the expression levels of multitarget genes related to programmed cell death and inflammatory response. This study shows that SARS-CoV-2 infection alters the m6A epitranscriptome of lymphocytes, particularly in the case of severe patients. RBM15 regulated host immune response to SARS-CoV-2 by elevating m6A modifications of multitarget genes. These findings indicate that RBM15 can serve as a target for the treatment of COVID-19.


Subject(s)
Adenosine/analogs & derivatives , COVID-19/genetics , RNA Processing, Post-Transcriptional , RNA-Binding Proteins/metabolism , Transcriptome , Adenosine/metabolism , COVID-19/pathology , Cell Line, Tumor , Epigenesis, Genetic , Female , Humans , Lymphocytes/metabolism , Male , Middle Aged , RNA-Binding Proteins/genetics , THP-1 Cells
11.
J Biol Chem ; 297(2): 100973, 2021 08.
Article in English | MEDLINE | ID: covidwho-1312455

ABSTRACT

N6-methyladenosine (m6A) is the most frequent chemical modification in eukaryotic mRNA and is known to participate in a variety of physiological processes, including cancer progression and viral infection. The reversible and dynamic m6A modification is installed by m6A methyltransferase (writer) enzymes and erased by m6A demethylase (eraser) enzymes. m6A modification recognized by m6A binding proteins (readers) regulates RNA processing and metabolism, leading to downstream biological effects such as promotion of stability and translation or increased degradation. The m6A writers and erasers determine the abundance of m6A modifications and play decisive roles in its distribution and function. In this review, we focused on m6A writers and erasers and present an overview on their known functions and enzymatic molecular mechanisms, showing how they recognize substrates and install or remove m6A modifications. We also summarize the current applications of m6A writers and erasers for m6A detection and highlight the merits and drawbacks of these available methods. Lastly, we describe the biological functions of m6A in cancers and viral infection based on research of m6A writers and erasers and introduce new assays for m6A functionality via programmable m6A editing tools.


Subject(s)
Adenosine/analogs & derivatives , Eukaryotic Cells/metabolism , Methyltransferases/metabolism , Neoplasms/pathology , RNA Processing, Post-Transcriptional/genetics , RNA, Messenger/genetics , Adenosine/chemistry , Adenosine/genetics , Adenosine/metabolism , Humans , Neoplasms/genetics , Neoplasms/metabolism
12.
Cells ; 10(5)2021 05 07.
Article in English | MEDLINE | ID: covidwho-1273392

ABSTRACT

The field of mRNA modifications has been steadily growing in recent years as technologies have improved and the importance of these residues became clear. However, a subfield has also arisen, specifically focused on how these modifications affect viral RNA, with the possibility that viruses can also be used as a model to best determine the role that these modifications play on cellular mRNAs. First, virologists focused on the most abundant internal mRNA modification, m6A, mapping this modification and elucidating its effects on the RNA of a wide range of RNA and DNA viruses. Next, less common RNA modifications including m5C, Nm and ac4C were investigated and also found to be present on viral RNA. It now appears that viral RNA is littered with a multitude of RNA modifications. In biological systems that are under constant evolutionary pressure to out compete both the host as well as newly arising viral mutants, it poses an interesting question about what evolutionary benefit these modifications provide as it seems evident, at least to this author, that these modifications have been selected for. In this review, I discuss how RNA modifications are identified on viral RNA and the roles that have now been uncovered for these modifications in regard to viral replication. Finally, I propose some interesting avenues of research that may shed further light on the exact role that these modifications play in viral replication.


Subject(s)
Epigenesis, Genetic , Gene Expression Regulation , RNA Processing, Post-Transcriptional , RNA, Viral/chemistry , RNA, Viral/genetics , Animals , Humans
13.
J Med Virol ; 93(7): 4258-4264, 2021 Jul.
Article in English | MEDLINE | ID: covidwho-1173823

ABSTRACT

The recent coronavirus disease 2019 (COVID-19), causing a global pandemic with devastating effects on healthcare and social-economic systems, has no special antiviral therapies available for human coronaviruses (CoVs). The severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) possesses a nonstructural protein (nsp14), with amino-terminal domain coding for proofreading exoribonuclease (ExoN) that is required for high-fidelity replication. The ability of CoVs during genome replication and transcription to proofread and exclude mismatched nucleotides has long hindered the development of anti-CoV drugs. The resistance of SARS-CoV-2 to antivirals, especially nucleoside analogs (NAs), shows the need to identify new CoV inhibition targets. Therefore, this review highlights the importance of nsp14-ExoN as a target for inhibition. Also, nucleoside analogs could be used in combination with existing anti-CoV therapeutics to target the proofreading mechanism.


Subject(s)
Antiviral Agents/pharmacology , COVID-19/drug therapy , Exoribonucleases/genetics , SARS-CoV-2/genetics , Viral Nonstructural Proteins/genetics , Virus Replication/drug effects , Exoribonucleases/drug effects , Exoribonucleases/metabolism , Genome, Viral/genetics , Humans , Methyltransferases/genetics , RNA Processing, Post-Transcriptional/physiology , RNA, Viral/genetics , SARS-CoV-2/drug effects , Viral Nonstructural Proteins/drug effects , Viral Nonstructural Proteins/metabolism , Virus Replication/physiology
14.
Int J Mol Sci ; 22(7)2021 Mar 25.
Article in English | MEDLINE | ID: covidwho-1154425

ABSTRACT

The global COVID-19 pandemic caused by SARS-CoV-2 has resulted in over 2.2 million deaths. Disease outcomes range from asymptomatic to severe with, so far, minimal genotypic change to the virus so understanding the host response is paramount. Transcriptomics has become incredibly important in understanding host-pathogen interactions; however, post-transcriptional regulation plays an important role in infection and immunity through translation and mRNA stability, allowing tight control over potent host responses by both the host and the invading virus. Here, we apply ribosome profiling to assess post-transcriptional regulation of host genes during SARS-CoV-2 infection of a human lung epithelial cell line (Calu-3). We have identified numerous transcription factors (JUN, ZBTB20, ATF3, HIVEP2 and EGR1) as well as select antiviral cytokine genes, namely IFNB1, IFNL1,2 and 3, IL-6 and CCL5, that are restricted at the post-transcriptional level by SARS-CoV-2 infection and discuss the impact this would have on the host response to infection. This early phase restriction of antiviral transcripts in the lungs may allow high viral load and consequent immune dysregulation typically seen in SARS-CoV-2 infection.


Subject(s)
Cytokines/genetics , RNA Processing, Post-Transcriptional , Ribosomes/metabolism , Ribosomes/virology , SARS-CoV-2/immunology , Transcription Factors/genetics , Animals , Antiviral Agents/antagonists & inhibitors , Cell Line, Tumor , Chlorocebus aethiops , Computational Biology , Cytokines/metabolism , Epithelial Cells/immunology , Epithelial Cells/virology , Gene Expression Profiling , Host Microbial Interactions , Humans , Immunity, Innate/genetics , Lung/immunology , Lung/virology , RNA, Messenger/metabolism , RNA-Seq , Ribosomes/genetics , SARS-CoV-2/metabolism , Transcription Factors/metabolism , Transcriptome , Vero Cells
15.
Viruses ; 12(5)2020 05 10.
Article in English | MEDLINE | ID: covidwho-1121808

ABSTRACT

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) causing the COVID-19 respiratory disease pandemic utilizes unique 2'-O-methyltransferase (2'-O-MTase) capping machinery to camouflage its RNA from innate immune recognition. The nsp16 catalytic subunit of the 2'-O-MTase is unusual in its requirement for a stimulatory subunit (nsp10) to catalyze the ribose 2'-O-methylation of the viral RNA cap. Here we provide a computational basis for drug repositioning or de novo drug development based on three differential traits of the intermolecular interactions of the SARS-CoV-2-specific nsp16/nsp10 heterodimer, namely: (1) the S-adenosyl-l-methionine-binding pocket of nsp16, (2) the unique "activating surface" between nsp16 and nsp10, and (3) the RNA-binding groove of nsp16. We employed ≈9000 U.S. Food and Drug Administration (FDA)-approved investigational and experimental drugs from the DrugBank repository for docking virtual screening. After molecular dynamics calculations of the stability of the binding modes of high-scoring nsp16/nsp10-drug complexes, we considered their pharmacological overlapping with functional modules of the virus-host interactome that is relevant to the viral lifecycle, and to the clinical features of COVID-19. Some of the predicted drugs (e.g., tegobuvir, sonidegib, siramesine, antrafenine, bemcentinib, itacitinib, or phthalocyanine) might be suitable for repurposing to pharmacologically reactivate innate immune restriction and antagonism of SARS-CoV-2 RNAs lacking 2'-O-methylation.


Subject(s)
Betacoronavirus/immunology , Coronavirus Infections/virology , Immune Evasion/drug effects , Pneumonia, Viral/virology , RNA Processing, Post-Transcriptional , RNA, Viral/metabolism , COVID-19 , Coronavirus Infections/drug therapy , Coronavirus Infections/immunology , Drug Repositioning , Humans , Immunity, Innate , Methylation , Models, Molecular , Pandemics , Pneumonia, Viral/immunology , SARS-CoV-2
16.
Nucleic Acids Res ; 49(7): e40, 2021 04 19.
Article in English | MEDLINE | ID: covidwho-1050155

ABSTRACT

Generation of conditional knockout (cKO) and various gene-modified cells is laborious and time-consuming. Here, we established an all-in-one cKO system, which enables highly efficient generation of cKO cells and simultaneous gene modifications, including epitope tagging and reporter gene knock-in. We applied this system to mouse embryonic stem cells (ESCs) and generated RNA helicase Ddx1 cKO ESCs. The targeted cells displayed endogenous promoter-driven EGFP and FLAG-tagged DDX1 expression, and they were converted to Ddx1 KO via FLP recombinase. We further established TetFE ESCs, which carried a reverse tetracycline transactivator (rtTA) expression cassette and a tetracycline response element (TRE)-regulated FLPERT2 cassette in the Gt(ROSA26)Sor locus for instant and tightly regulated induction of gene KO. By utilizing TetFE Ddx1F/F ESCs, we isolated highly pure Ddx1F/F and Ddx1-/- ESCs and found that loss of Ddx1 caused rRNA processing defects, thereby activating the ribosome stress-p53 pathway. We also demonstrated cKO of various genes in ESCs and homologous recombination-non-proficient human HT1080 cells. The frequency of cKO clones was remarkably high for both cell types and reached up to 96% when EGFP-positive clones were analyzed. This all-in-one cKO system will be a powerful tool for rapid and precise analyses of gene functions.


Subject(s)
DEAD-box RNA Helicases/metabolism , Gene Knockout Techniques/methods , RNA, Ribosomal/metabolism , Animals , Cell Line , Embryonic Stem Cells , Fibroblasts , Gene Expression , Gene Knock-In Techniques , Humans , Mice , Mice, Inbred C57BL , RNA Processing, Post-Transcriptional , Ribosomes/metabolism
17.
Biomolecules ; 10(7)2020 07 17.
Article in English | MEDLINE | ID: covidwho-951579

ABSTRACT

Studies have shown that epigenetic abnormalities are involved in various diseases, including cancer. In particular, in order to realize precision medicine, the integrated analysis of genetics and epigenetics is considered to be important; detailed epigenetic analysis in the medical field has been becoming increasingly important. In the epigenetics analysis, DNA methylation and histone modification analyses have been actively studied for a long time, and many important findings were accumulated. On the other hand, recently, attention has also been focused on RNA modification in the field of epigenetics; now it is known that RNA modification is associated with various biological functions, such as regulation of gene expression. Among RNA modifications, functional analysis of N6-methyladenosine (m6A), the most abundant RNA modification found from humans to plants is actively progressing, and it has also been known that m6A abnormality is involved in cancer and other diseases. Importantly, recent studies have shown that m6A is related to viral infections. Considering the current world situation under threat of viral infections, it is important to deepen knowledge of RNA modification from the viewpoint of viral diseases. Hence, in this review, we have summarized the recent findings regarding the roles of RNA modifications in biological functions, cancer biology, and virus infection, particularly focusing on m6A in mRNA.


Subject(s)
Adenosine/analogs & derivatives , Epigenesis, Genetic , Neoplasms/genetics , RNA Processing, Post-Transcriptional , RNA/genetics , Virus Diseases/genetics , Adenosine/genetics , Adenosine/metabolism , Animals , Humans , Neoplasms/metabolism , RNA/metabolism , RNA Folding , RNA Stability , RNA Transport , Virus Diseases/metabolism
18.
Clin Epigenetics ; 12(1): 156, 2020 10 21.
Article in English | MEDLINE | ID: covidwho-883596

ABSTRACT

Epigenetics is a relatively new field of science that studies the genetic and non-genetic aspects related to heritable phenotypic changes, frequently caused by environmental and metabolic factors. In the host, the epigenetic machinery can regulate gene expression through a series of reversible epigenetic modifications, such as histone methylation and acetylation, DNA/RNA methylation, chromatin remodeling, and non-coding RNAs. The coronavirus disease 19 (COVID-19) is a highly transmittable and pathogenic viral infection. The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), which emerged in Wuhan, China, and spread worldwide, causes it. COVID-19 severity and consequences largely depend on patient age and health status. In this review, we will summarize and comparatively analyze how viruses regulate the host epigenome. Mainly, we will be focusing on highly pathogenic respiratory RNA virus infections such as coronaviruses. In this context, epigenetic alterations might play an essential role in the onset of coronavirus disease complications. Although many therapeutic approaches are under study, more research is urgently needed to identify effective vaccine or safer chemotherapeutic drugs, including epigenetic drugs, to cope with this viral outbreak and to develop pre- and post-exposure prophylaxis against COVID-19.


Subject(s)
Antiviral Agents/pharmacology , Betacoronavirus/physiology , Coronavirus Infections/drug therapy , Coronavirus Infections/genetics , Epigenesis, Genetic , Gene Expression Regulation, Viral , Pneumonia, Viral/drug therapy , Pneumonia, Viral/genetics , COVID-19 , Coronavirus Infections/immunology , Cytokines/genetics , Cytokines/immunology , Gene Expression Regulation, Viral/drug effects , Host-Pathogen Interactions , Humans , Inflammation/immunology , Pandemics , Pneumonia, Viral/immunology , RNA Processing, Post-Transcriptional , SARS-CoV-2
20.
Sci Signal ; 13(651)2020 09 29.
Article in English | MEDLINE | ID: covidwho-808027

ABSTRACT

There are currently no antiviral therapies specific for SARS-CoV-2, the virus responsible for the global pandemic disease COVID-19. To facilitate structure-based drug design, we conducted an x-ray crystallographic study of the SARS-CoV-2 nsp16-nsp10 2'-O-methyltransferase complex, which methylates Cap-0 viral mRNAs to improve viral protein translation and to avoid host immune detection. We determined the structures for nsp16-nsp10 heterodimers bound to the methyl donor S-adenosylmethionine (SAM), the reaction product S-adenosylhomocysteine (SAH), or the SAH analog sinefungin (SFG). We also solved structures for nsp16-nsp10 in complex with the methylated Cap-0 analog m7GpppA and either SAM or SAH. Comparative analyses between these structures and published structures for nsp16 from other betacoronaviruses revealed flexible loops in open and closed conformations at the m7GpppA-binding pocket. Bound sulfates in several of the structures suggested the location of the ribonucleic acid backbone phosphates in the ribonucleotide-binding groove. Additional nucleotide-binding sites were found on the face of the protein opposite the active site. These various sites and the conserved dimer interface could be exploited for the development of antiviral inhibitors.


Subject(s)
Betacoronavirus/enzymology , Coronavirus Infections/drug therapy , Methyltransferases/chemistry , Pneumonia, Viral/drug therapy , Viral Nonstructural Proteins/chemistry , Adenosine/analogs & derivatives , Adenosine/metabolism , Adenosine/pharmacology , Betacoronavirus/drug effects , Binding Sites , COVID-19 , Catalytic Domain , Crystallography, X-Ray , Dimerization , Genes, Viral/genetics , Humans , Methylation , Methyltransferases/antagonists & inhibitors , Models, Molecular , Open Reading Frames/genetics , Pandemics , Protein Binding , Protein Conformation , RNA Cap Analogs/metabolism , RNA Processing, Post-Transcriptional , RNA, Viral/metabolism , S-Adenosylhomocysteine/metabolism , S-Adenosylmethionine/metabolism , SARS-CoV-2 , Structure-Activity Relationship , Viral Nonstructural Proteins/antagonists & inhibitors , Viral Nonstructural Proteins/metabolism
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