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1.
ACS Chem Biol ; 16(5): 844-856, 2021 05 21.
Article in English | MEDLINE | ID: covidwho-1457790

ABSTRACT

Interferon-induced transmembrane proteins (IFITMs) are S-palmitoylated proteins in vertebrates that restrict a diverse range of viruses. S-palmitoylated IFITM3 in particular engages incoming virus particles, prevents their cytoplasmic entry, and accelerates their lysosomal clearance by host cells. However, how S-palmitoylation modulates the structure and biophysical characteristics of IFITM3 to promote its antiviral activity remains unclear. To investigate how site-specific S-palmitoylation controls IFITM3 antiviral activity, we employed computational, chemical, and biophysical approaches to demonstrate that site-specific lipidation of cysteine 72 enhances the antiviral activity of IFITM3 by modulating its conformation and interaction with lipid membranes. Collectively, our results demonstrate that site-specific S-palmitoylation of IFITM3 directly alters its biophysical properties and activity in cells to prevent virus infection.


Subject(s)
Antiviral Agents/chemistry , Cell Membrane/metabolism , Interferons/chemistry , Lipids/chemistry , Membrane Proteins/metabolism , RNA-Binding Proteins/metabolism , Amino Acid Sequence , Antiviral Agents/pharmacology , Binding Sites , Cell Membrane/ultrastructure , Computational Biology , Drug Design , Humans , Interferons/pharmacology , Lipoylation , Lysosomes/metabolism , Molecular Dynamics Simulation , Protein Binding , Protein Conformation , Signal Transduction
2.
EMBO J ; 40(3): e106501, 2021 02 01.
Article in English | MEDLINE | ID: covidwho-1389834

ABSTRACT

Interferon-induced transmembrane proteins (IFITMs) restrict infections by many viruses, but a subset of IFITMs enhance infections by specific coronaviruses through currently unknown mechanisms. We show that SARS-CoV-2 Spike-pseudotyped virus and genuine SARS-CoV-2 infections are generally restricted by human and mouse IFITM1, IFITM2, and IFITM3, using gain- and loss-of-function approaches. Mechanistically, SARS-CoV-2 restriction occurred independently of IFITM3 S-palmitoylation, indicating a restrictive capacity distinct from reported inhibition of other viruses. In contrast, the IFITM3 amphipathic helix and its amphipathic properties were required for virus restriction. Mutation of residues within the IFITM3 endocytosis-promoting YxxФ motif converted human IFITM3 into an enhancer of SARS-CoV-2 infection, and cell-to-cell fusion assays confirmed the ability of endocytic mutants to enhance Spike-mediated fusion with the plasma membrane. Overexpression of TMPRSS2, which increases plasma membrane fusion versus endosome fusion of SARS-CoV-2, attenuated IFITM3 restriction and converted amphipathic helix mutants into infection enhancers. In sum, we uncover new pro- and anti-viral mechanisms of IFITM3, with clear distinctions drawn between enhancement of viral infection at the plasma membrane and amphipathicity-based mechanisms used for endosomal SARS-CoV-2 restriction.


Subject(s)
Antigens, Differentiation/genetics , COVID-19/genetics , Membrane Proteins/genetics , RNA-Binding Proteins/genetics , SARS-CoV-2 , Angiotensin-Converting Enzyme 2/genetics , Animals , Cell Line , Chlorocebus aethiops , Humans , Mice , Mutation , SARS-CoV-2/physiology , Serine Endopeptidases , Virus Internalization
3.
J Biol Chem ; 297(1): 100847, 2021 07.
Article in English | MEDLINE | ID: covidwho-1246014

ABSTRACT

The zoonotic transmission of highly pathogenic coronaviruses into the human population is a pressing concern highlighted by the ongoing SARS-CoV-2 pandemic. Recent work has helped to illuminate much about the mechanisms of SARS-CoV-2 entry into the cell, which determines host- and tissue-specific tropism, pathogenicity, and zoonotic transmission. Here we discuss current findings on the factors governing SARS-CoV-2 entry. We first reviewed key features of the viral spike protein (S) mediating fusion of the viral envelope and host cell membrane through binding to the SARS-CoV-2 receptor, angiotensin-converting enzyme 2. We then examined the roles of host proteases including transmembrane protease serine 2 and cathepsins in processing S for virus entry and the impact of this processing on endosomal and plasma membrane virus entry routes. We further discussed recent work on several host cofactors that enhance SARS-CoV-2 entry including Neuropilin-1, CD147, phosphatidylserine receptors, heparan sulfate proteoglycans, sialic acids, and C-type lectins. Finally, we discussed two key host restriction factors, i.e., interferon-induced transmembrane proteins and lymphocyte antigen 6 complex locus E, which can disrupt SARS-CoV-2 entry. The features of SARS-CoV-2 are presented in the context of other human coronaviruses, highlighting unique aspects. In addition, we identify the gaps in understanding of SARS-CoV-2 entry that will need to be addressed by future studies.


Subject(s)
COVID-19/metabolism , SARS-CoV-2/physiology , Virus Internalization , Animals , Basigin/genetics , Basigin/metabolism , COVID-19/genetics , COVID-19/virology , Host-Pathogen Interactions , Humans , Lectins, C-Type/genetics , Lectins, C-Type/metabolism , Neuropilin-1/genetics , Neuropilin-1/metabolism , Receptors, Virus/genetics , Receptors, Virus/metabolism , SARS-CoV-2/genetics
4.
Genomics ; 113(4): 1733-1741, 2021 07.
Article in English | MEDLINE | ID: covidwho-1171554

ABSTRACT

Interferon-induced membrane proteins (IFITM) 3 gene variants are known risk factor for severe viral diseases. We examined whether IFITM3 variant may underlie the heterogeneous clinical outcomes of SARS-CoV-2 infection-induced COVID-19 in large Arab population. We genotyped 880 Saudi patients; 93.8% were PCR-confirmed SARS-CoV-2 infection, encompassing most COVID-19 phenotypes. Mortality at 90 days was 9.1%. IFITM3-SNP, rs12252-G allele was associated with hospital admission (OR = 1.65 [95% CI; 1.01-2.70], P = 0.04]) and mortality (OR = 2.2 [95% CI; 1.16-4.20], P = 0.01). Patients less than 60 years old had a lower survival probability if they harbor this allele (log-rank test P = 0.002). Plasma levels of IFNγ were significantly lower in a subset of patients with AG/GG genotypes than patients with AA genotype (P = 0.00016). Early identification of these individuals at higher risk of death may inform precision public health response.


Subject(s)
COVID-19/genetics , Genetic Predisposition to Disease , Membrane Proteins/genetics , RNA-Binding Proteins/genetics , SARS-CoV-2/genetics , Adult , Aged , Aged, 80 and over , COVID-19/mortality , COVID-19/virology , Female , Genetic Association Studies , Genotype , Humans , Interferons/genetics , Male , Middle Aged , Polymorphism, Single Nucleotide/genetics , SARS-CoV-2/pathogenicity
5.
Cytokine ; 137: 155354, 2021 01.
Article in English | MEDLINE | ID: covidwho-893718

ABSTRACT

BACKGROUND AND AIMS: The interferon-induced transmembrane proteins play an important antiviral role by preventing viruses from traversing the cellular lipid bilayer. IFITM3 gene variants have been associated with the clinical response to influenza and other viruses. Our aim was to determine whether the IFITM3 rs12252 polymorphism was associated with the risk of developing severe symptoms of COVID-19 in our population. METHODS: A total of 288 COVID-19 patients who required hospitalization (81 in the intensive care unit) and 440 age matched controls were genotyped with a Taqman assay. Linear regression models were used to compare allele and genotype frequencies between the groups, correcting for age and sex. RESULTS: Carriers of the minor allele frequency (rs12252 C) were significantly more frequent in the patients compared to controls after correcting by age and sex (p = 0.01, OR = 2.02, 95%CI = 1.19-3.42). This genotype was non-significantly more common among patients who required ICU. CONCLUSIONS: The IFITM3 rs12252 C allele was a risk factor for COVID-19 hospitalization in our Caucasian population. The extent of the association was lower than the reported among Chinese, a population with a much higher frequency of the risk allele.


Subject(s)
/genetics , COVID-19/genetics , Membrane Proteins/genetics , RNA-Binding Proteins/genetics , /genetics , Aged , COVID-19/blood , COVID-19/epidemiology , Female , Gene Frequency , Genetic Predisposition to Disease , Genotype , Humans , Linear Models , Male , Membrane Proteins/blood , Middle Aged , Polymorphism, Genetic , RNA-Binding Proteins/blood , Risk Factors
6.
Emerg Microbes Infect ; 9(1): 1567-1579, 2020 Dec.
Article in English | MEDLINE | ID: covidwho-707709

ABSTRACT

Diverse SARS-like coronaviruses (SL-CoVs) have been identified from bats and other animal species. Like SARS-CoV, some bat SL-CoVs, such as WIV1, also use angiotensin converting enzyme 2 (ACE2) from human and bat as entry receptor. However, whether these viruses can also use the ACE2 of other animal species as their receptor remains to be determined. We report herein that WIV1 has a broader tropism to ACE2 orthologs than SARS-CoV isolate Tor2. Among the 9 ACE2 orthologs examined, human ACE2 exhibited the highest efficiency to mediate the infection of WIV1 pseudotyped virus. Our findings thus imply that WIV1 has the potential to infect a wide range of wild animals and may directly jump to humans. We also showed that cell entry of WIV1 could be restricted by interferon-induced transmembrane proteins (IFITMs). However, WIV1 could exploit the airway protease TMPRSS2 to partially evade the IFITM3 restriction. Interestingly, we also found that amphotericin B could enhance the infectious entry of SARS-CoVs and SL-CoVs by evading IFITM3-mediated restriction. Collectively, our findings further underscore the risk of exposure to animal SL-CoVs and highlight the vulnerability of patients who take amphotericin B to infection by SL-CoVs, including the most recently emerging (SARS-CoV-2).


Subject(s)
Betacoronavirus/physiology , Chiroptera/virology , Membrane Proteins/metabolism , Peptidyl-Dipeptidase A/metabolism , RNA-Binding Proteins/metabolism , Receptors, Virus/metabolism , Serine Endopeptidases/metabolism , Virus Internalization , Angiotensin-Converting Enzyme 2 , Animals , Betacoronavirus/classification , HEK293 Cells , Humans , Rats , Receptors, Coronavirus , SARS Virus/physiology , Viverridae
7.
Front Immunol ; 11: 1372, 2020.
Article in English | MEDLINE | ID: covidwho-619471

ABSTRACT

Current guidelines for COVID-19 management recommend the utilization of various repurposed drugs. Despite ongoing research toward the development of a vaccine against SARS-CoV-2, such a vaccine will not be available in time to contribute to the containment of the ongoing pandemic. Therefore, there is an urgent need to develop a framework for the rapid identification of novel targets for diagnostic and therapeutic interventions. We analyzed publicly available transcriptomic datasets of SARS-CoV infected humans and mammals to identify consistent differentially expressed genes then validated in SARS-CoV-2 infected epithelial cells transcriptomic datasets. Comprehensive toxicogenomic analysis of the identified genes to identify possible interactions with clinically proven drugs was carried out. We identified IFITM3 as an early upregulated gene, and valproic acid was found to enhance its mRNA expression as well as induce its antiviral action. These findings indicate that analysis of publicly available transcriptomic and toxicogenomic data represents a rapid approach for the identification of novel targets and molecules that can modify the action of such targets during the early phases of emerging infections like COVID-19.


Subject(s)
Coronavirus Infections/genetics , Coronavirus Infections/immunology , Gene Expression Profiling , Membrane Proteins/genetics , Pneumonia, Viral/genetics , Pneumonia, Viral/immunology , RNA-Binding Proteins/genetics , 2',5'-Oligoadenylate Synthetase/genetics , Animals , Antiviral Agents/pharmacology , Betacoronavirus/physiology , COVID-19 , Disease Models, Animal , Ferrets , Gene Expression Regulation/drug effects , Humans , Immunity, Innate , Lung , Macaca fascicularis , Mice , Myxovirus Resistance Proteins/genetics , Pandemics , SARS-CoV-2 , Species Specificity , Up-Regulation/drug effects , Valproic Acid/pharmacology
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