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1.
Int J Mol Sci ; 23(21)2022 Oct 31.
Article in English | MEDLINE | ID: covidwho-2099576

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces immune-mediated type 1 interferon (IFN-1) production, the pathophysiology of which involves sterile alpha motif and histidine-aspartate domain-containing protein 1 (SAMHD1) tetramerization and the cytosolic DNA sensor cyclic-GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway. As a result, type I interferonopathies are exacerbated. Aspirin inhibits cGAS-mediated signaling through cGAS acetylation. Acetylation contributes to cGAS activity control and activates IFN-1 production and nuclear factor-κB (NF-κB) signaling via STING. Aspirin and dapsone inhibit the activation of both IFN-1 and NF-κB by targeting cGAS. We define these as anticatalytic mechanisms. It is necessary to alleviate the pathologic course and take the lag time of the odds of achieving viral clearance by day 7 to coordinate innate or adaptive immune cell reactions.


Subject(s)
COVID-19 , Interferon Type I , Humans , COVID-19/drug therapy , Acetylation , NF-kappa B/metabolism , Drug Repositioning , Membrane Proteins/metabolism , SARS-CoV-2 , Nucleotidyltransferases/metabolism , Interferon Type I/metabolism , Aspirin , Immunity, Innate/genetics
2.
Cells ; 11(21)2022 Nov 03.
Article in English | MEDLINE | ID: covidwho-2099367

ABSTRACT

The cGAS-STING pathway displays important functions in the regulation of innate and adaptive immunity following the detection of microbial and host-derived DNA. Here, we briefly summarize biological functions of STING and review recent literature highlighting its important contribution in the context of respiratory diseases. Over the last years, tremendous progress has been made in our understanding of STING activation, which has favored the development of STING agonists or antagonists with potential therapeutic benefits. Antagonists might alleviate STING-associated chronic inflammation and autoimmunity. Furthermore, pharmacological activation of STING displays strong antiviral properties, as recently shown in the context of SARS-CoV-2 infection. STING agonists also elicit potent stimulatory activities when used as an adjuvant promoting antitumor responses and vaccines efficacy.


Subject(s)
COVID-19 , Membrane Proteins , Humans , Membrane Proteins/metabolism , COVID-19/drug therapy , SARS-CoV-2 , Adaptive Immunity , Autoimmunity
3.
Vet Microbiol ; 275: 109597, 2022 Dec.
Article in English | MEDLINE | ID: covidwho-2086823

ABSTRACT

Interferon-induced transmembrane proteins (IFITMs) are broad-spectrum antiviral proteins that inhibit numerous virus infections by impeding viral entry into target cells. However, increasing evidence suggests diverse functions of IFITMs in virus infection, especially with the coronavirus. We analyzed the effect of chicken interferon-induced transmembrane proteins (chIFITMs) on coronavirus infectious bronchitis virus (IBV) infection in vitro. We demonstrated that the antiviral effects of IFITMs are dependent on cell and virus types. The overexpression of chIFITM1 dramatically promoted the replication of IBV Beaudette strain in the chicken hepatocellular carcinoma cell line, LMH. Mechanistically, chIFITMs share roughly the same subcellular localization in different host cells, and overexpressed of chIFITM1 have no effect of viral attachment and entry. Further studies revealed that mutations of amino acids at key positions (60KSRD63, 68KDFV71) in the intracellular loop domain (CIL) caused loss of the promoted function. Interaction with downstream proteins in co-response to viral infection could be the primary reason behind variable functions of chIFITM1 in different cells. In all, our study explored the functions of chIFITMs in viral infection from a new perspective.


Subject(s)
Coronavirus Infections , Infectious bronchitis virus , Animals , Infectious bronchitis virus/genetics , Chickens , Coronavirus Infections/veterinary , Antiviral Agents/pharmacology , Interferons/pharmacology , Membrane Proteins/genetics , Membrane Proteins/metabolism , Virus Replication
4.
Clin Nucl Med ; 47(12): 1026-1029, 2022 Dec 01.
Article in English | MEDLINE | ID: covidwho-2078007

ABSTRACT

PATIENTS AND METHODS: Six post COVID-19 patients suspected for pulmonary fibrosis were scheduled for dual-tracer PET/CT with 18 F-FDG and 68 Ga-fibroblast activation protein inhibitor (FAPI)-46. The uptake of 68 Ga-FAPI-46 in the involved lung was compared with a control group of 9 non-COVID-19 patients. Clinical data and PET/CT imaging were collected and analyzed. RESULTS: PET/CT revealed in all 6 pulmonary impaired patients the reduced glucose avidity on 18 F-FDG and clear positivity on 68 Ga-FAPI-46 PET/CT in comparison to the control group. CONCLUSIONS: Enhancing fibrotic repair mechanisms, 68 Ga-FAPI PET/CT may improve noninvasive clinical diagnostic performance in patients with long-term CT abnormalities after severe COVID-19. Although this study shows promising results, additional studies in larger populations are required to establish a general diagnostic guideline.


Subject(s)
COVID-19 , Positron Emission Tomography Computed Tomography , Humans , Positron Emission Tomography Computed Tomography/methods , Fluorodeoxyglucose F18 , Membrane Proteins/metabolism , COVID-19/complications , COVID-19/diagnostic imaging , Gallium Radioisotopes
5.
Cells ; 11(18)2022 09 08.
Article in English | MEDLINE | ID: covidwho-2065725

ABSTRACT

Cyclic GMP-AMP synthase (cGAS) is a predominant and ubiquitously expressed cytosolic onfirmedDNA sensor that activates innate immune responses by producing a second messenger, cyclic GMP-AMP (cGAMP), and the stimulator of interferon genes (STING). cGAS contains a highly disordered N-terminus, which can sense genomic/chromatin DNA, while the C terminal of cGAS binds dsDNA liberated from various sources, including mitochondria, pathogens, and dead cells. Furthermore, cGAS cellular localization dictates its response to foreign versus self-DNA. Recent evidence has also highlighted the importance of dsDNA-induced post-translational modifications of cGAS in modulating inflammatory responses. This review summarizes and analyzes cGAS activity regulation based on structure, sub-cellular localization, post-translational mechanisms, and Ca2+ signaling. We also discussed the role of cGAS activation in different diseases and clinical outcomes.


Subject(s)
Membrane Proteins , Nucleotidyltransferases , Chromatin , DNA/metabolism , Interferons/genetics , Membrane Proteins/metabolism , Nucleotidyltransferases/metabolism
6.
PLoS Biol ; 20(10): e3001805, 2022 10.
Article in English | MEDLINE | ID: covidwho-2065095

ABSTRACT

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection is mediated by the entry receptor angiotensin-converting enzyme 2 (ACE2). Although attachment factors and coreceptors facilitating entry are extensively studied, cellular entry factors inhibiting viral entry are largely unknown. Using a surfaceome CRISPR activation screen, we identified human LRRC15 as an inhibitory attachment factor for SARS-CoV-2 entry. LRRC15 directly binds to the receptor-binding domain (RBD) of spike protein with a moderate affinity and inhibits spike-mediated entry. Analysis of human lung single-cell RNA sequencing dataset reveals that expression of LRRC15 is primarily detected in fibroblasts and particularly enriched in pathological fibroblasts in COVID-19 patients. ACE2 and LRRC15 are not coexpressed in the same cell types in the lung. Strikingly, expression of LRRC15 in ACE2-negative cells blocks spike-mediated viral entry in ACE2+ cell in trans, suggesting a protective role of LRRC15 in a physiological context. Therefore, LRRC15 represents an inhibitory attachment factor for SARS-CoV-2 that regulates viral entry in trans.


Subject(s)
Angiotensin-Converting Enzyme 2 , COVID-19 , Humans , Angiotensin-Converting Enzyme 2/genetics , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/metabolism , COVID-19/genetics , Protein Binding , Membrane Proteins/genetics , Membrane Proteins/metabolism
7.
J Mol Biol ; 434(6): 167277, 2022 03 30.
Article in English | MEDLINE | ID: covidwho-2061566

ABSTRACT

Establishment of the interferon (IFN)-mediated antiviral state provides a crucial initial line of defense against viral infection. Numerous genes that contribute to this antiviral state remain to be identified. Using a loss-of-function strategy, we screened an original library of 1156 siRNAs targeting 386 individual curated human genes in stimulated microglial cells infected with Zika virus (ZIKV), an emerging RNA virus that belongs to the flavivirus genus. The screen recovered twenty-one potential host proteins that modulate ZIKV replication in an IFN-dependent manner, including the previously known IFITM3 and LY6E. Further characterization contributed to delineate the spectrum of action of these genes towards other pathogenic RNA viruses, including Hepatitis C virus and SARS-CoV-2. Our data revealed that APOL3 acts as a proviral factor for ZIKV and several other related and unrelated RNA viruses. In addition, we showed that MTA2, a chromatin remodeling factor, possesses potent flavivirus-specific antiviral functions induced by IFN. Our work identified previously unrecognized genes that modulate the replication of RNA viruses in an IFN-dependent manner, opening new perspectives to target weakness points in the life cycle of these viruses.


Subject(s)
Flavivirus , Interferons , Virus Replication , Apolipoproteins L/genetics , Apolipoproteins L/metabolism , Flavivirus/physiology , Histone Deacetylases/genetics , Histone Deacetylases/metabolism , Humans , Interferons/genetics , Membrane Proteins/genetics , Membrane Proteins/metabolism , RNA-Binding Proteins/genetics , RNA-Binding Proteins/metabolism , Repressor Proteins/genetics , Repressor Proteins/metabolism , SARS-CoV-2/physiology , Zika Virus/physiology
8.
mBio ; 13(5): e0254322, 2022 10 26.
Article in English | MEDLINE | ID: covidwho-2053129

ABSTRACT

COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has had a devastating impact on global public health, emphasizing the importance of understanding innate immune mechanisms and cellular restriction factors that cells can harness to fight viral infections. The multimembrane-spanning zinc metalloprotease ZMPSTE24 is one such restriction factor. ZMPSTE24 has a well-characterized proteolytic role in the maturation of prelamin A, precursor of the nuclear scaffold protein lamin A. An apparently unrelated role for ZMPSTE24 in viral defense involves its interaction with the interferon-inducible membrane proteins (IFITMs), which block virus-host cell fusion by rigidifying cellular membranes and thereby prevent viral infection. ZMPSTE24, like the IFITMs, defends cells against a broad spectrum of enveloped viruses. However, its ability to protect against coronaviruses has never been examined. Here, we show that overexpression of ZMPSTE24 reduces the efficiency of cellular infection by SARS-CoV-2 Spike-pseudotyped lentivirus and that genetic knockout or small interfering RNA-mediated knockdown of endogenous ZMPSTE24 enhances infectivity. We further demonstrate a protective role for ZMPSTE24 in a Spike-ACE2-dependent cell-cell fusion assay. In both assays, a catalytic dead version of ZMPSTE24 is equally as protective as the wild-type protein, indicating that ZMPSTE24's proteolytic activity is not required for defense against SARS-CoV-2. Finally, we demonstrate by plaque assays that Zmpste24-/- mouse cells show enhanced infection by a genuine coronavirus, mouse hepatitis virus (MHV). This study extends the range of viral protection afforded by ZMPSTE24 to include coronaviruses and suggests that targeting ZMPSTE24's mechanism of viral defense could have therapeutic benefit. IMPORTANCE The COVID-19 pandemic caused by the coronavirus SARS-CoV-2 has underscored the importance of understanding intrinsic cellular components that can be harnessed as the cell's first line of defense to fight against viral infection. Our paper focuses on one such protein, the integral membrane protease ZMPSTE24, which interacts with interferon-inducible transmembrane proteins (IFITMs). IFITMs interfere with virus entry by inhibiting fusion between viral and host cell membranes, and ZMPSTE24 appears to contribute to this inhibitory activity. ZMPSTE24 has been shown to defend cells against several, but not all, enveloped viruses. In this study, we extend ZMPSTE24's reach to include coronaviruses, by showing that ZMPSTE24 protects cells from SARS-CoV-2 pseudovirus infection, Spike protein-mediated cell-cell fusion, and infection by the mouse coronavirus MHV. This work lays the groundwork for further studies to decipher the mechanistic role of ZMPSTE24 in blocking the entry of SARS-CoV-2 and other viruses into cells.


Subject(s)
COVID-19 , Murine hepatitis virus , Humans , Mice , Animals , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/metabolism , Angiotensin-Converting Enzyme 2 , Pandemics , Lamin Type A , Membrane Proteins/genetics , Membrane Proteins/metabolism , RNA, Small Interfering , Virus Internalization , Murine hepatitis virus/genetics , Antiviral Agents/pharmacology , Giant Cells , Metalloproteases , Interferons , Zinc
9.
J Biol Chem ; 298(11): 102500, 2022 Nov.
Article in English | MEDLINE | ID: covidwho-2041895

ABSTRACT

Coronavirus disease represents a real threat to the global population, and understanding the biological features of the causative virus, that is, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is imperative for mitigating this threat. Analyses of proteins such as primary receptors and coreceptors (cofactors), which are involved in the entry of SARS-CoV-2 into host cells, will provide important clues to help control the virus. Here, we identified host cell membrane protein candidates present in proximity to the attachment sites of SARS-CoV-2 spike proteins, using proximity labeling and proteomic analysis. The identified proteins represent key candidate factors that may be required for viral entry. We found SARS-CoV-2 host protein DPP4, cell adhesion protein Cadherin 17, and glycoprotein CD133 colocalized with cell membrane-bound SARS-CoV-2 spike proteins in Caco-2 cells and thus showed potential as candidate factors. Additionally, our analysis of the experimental infection of HEK293T cells with a SARS-CoV-2 pseudovirus indicated a 2-fold enhanced infectivity in the CD133-ACE2-coexpressing HEK293T cells compared to that in HEK293T cells expressing ACE-2 alone. The information and resources regarding these coreceptor labeling and analysis techniques could be utilized for the development of antiviral agents against SARS-CoV-2 and other emerging viruses.


Subject(s)
COVID-19 , Membrane Proteins , Spike Glycoprotein, Coronavirus , Virus Attachment , Humans , Angiotensin-Converting Enzyme 2 , Caco-2 Cells , HEK293 Cells , Membrane Proteins/metabolism , Protein Binding , Proteomics , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/metabolism , Virus Internalization , Receptors, Virus/metabolism
10.
Front Immunol ; 13: 982839, 2022.
Article in English | MEDLINE | ID: covidwho-2039678

ABSTRACT

The secreted enzyme interleukin four-induced gene 1 (IL4I1) is involved in the negative control of the adaptive immune response. IL4I1 expression in human cancer is frequent and correlates with poor survival and resistance to immunotherapy. Nevertheless, its mechanism of action remains partially unknown. Here, we identified transmembrane serine protease 13 (TMPRSS13) as an immune cell-expressed surface protein that binds IL4I1. TMPRSS13 is a paralog of TMPRSS2, of which the protease activity participates in the cleavage of SARS-CoV-2 spike protein and facilitates virus induced-membrane fusion. We show that TMPRSS13 is expressed by human lymphocytes, monocytes and monocyte-derived macrophages, can cleave the spike protein and allow SARS-CoV-2 spike pseudotyped virus entry into cells. We identify regions of homology between IL4I1 and spike and demonstrate competition between the two proteins for TMPRSS13 binding. These findings may be relevant for both interfering with SARS-CoV-2 infection and limiting IL4I1-dependent immunosuppressive activity in cancer.


Subject(s)
COVID-19 , Neoplasms , Humans , Interleukins , L-Amino Acid Oxidase , Membrane Proteins/genetics , Membrane Proteins/metabolism , SARS-CoV-2 , Serine Endopeptidases/genetics , Spike Glycoprotein, Coronavirus/metabolism
12.
Biol Chem ; 403(10): 969-982, 2022 09 27.
Article in English | MEDLINE | ID: covidwho-2029808

ABSTRACT

TMPRSS13 is a member of the type II transmembrane serine protease (TTSP) family. Here we characterize a novel post-translational mechanism important for TMPRSS13 function: proteolytic cleavage within the extracellular TMPRSS13 stem region located between the transmembrane domain and the first site of N-linked glycosylation at asparagine (N)-250 in the scavenger receptor cysteine rich (SRCR) domain. Importantly, the catalytic competence of TMPRSS13 is essential for stem region cleavage, suggesting an autonomous mechanism of action. Site-directed mutagenesis of the 10 basic amino acids (four arginine and six lysine residues) in this region abrogated zymogen activation and catalytic activity of TMPRSS13, as well as phosphorylation, cell surface expression, and shedding. Mutation analysis of individual arginine residues identified R223, a residue located between the low-density lipoprotein receptor class A domain and the SRCR domain, as important for stem region cleavage. Mutation of R223 causes a reduction in the aforementioned functional processing steps of TMPRSS13. These data provide further insight into the roles of different post-translational modifications as regulators of the function and localization of TMPRSS13. Additionally, the data suggest the presence of complex interconnected regulatory mechanisms that may serve to ensure the proper levels of cell-surface and pericellular TMPRSS13-mediated proteolysis under homeostatic conditions.


Subject(s)
Membrane Proteins , Protein Processing, Post-Translational , Arginine/metabolism , Enzyme Precursors/metabolism , Membrane Proteins/metabolism , Proteolysis
13.
Nat Commun ; 13(1): 5294, 2022 09 08.
Article in English | MEDLINE | ID: covidwho-2016700

ABSTRACT

Interferon-induced transmembrane protein 3 (IFITM3) is a restriction factor that limits viral pathogenesis and exerts poorly understood immunoregulatory functions. Here, using human and mouse models, we demonstrate that IFITM3 promotes MyD88-dependent, TLR-mediated IL-6 production following exposure to cytomegalovirus (CMV). IFITM3 also restricts IL-6 production in response to influenza and SARS-CoV-2. In dendritic cells, IFITM3 binds to the reticulon 4 isoform Nogo-B and promotes its proteasomal degradation. We reveal that Nogo-B mediates TLR-dependent pro-inflammatory cytokine production and promotes viral pathogenesis in vivo, and in the case of TLR2 responses, this process involves alteration of TLR2 cellular localization. Nogo-B deletion abrogates inflammatory cytokine responses and associated disease in virus-infected IFITM3-deficient mice. Thus, we uncover Nogo-B as a driver of viral pathogenesis and highlight an immunoregulatory pathway in which IFITM3 fine-tunes the responsiveness of myeloid cells to viral stimulation.


Subject(s)
COVID-19 , Interleukin-6 , Nogo Proteins/metabolism , Animals , Cytokines/metabolism , Humans , Interleukin-6/metabolism , Membrane Proteins/genetics , Membrane Proteins/metabolism , Mice , RNA-Binding Proteins/genetics , RNA-Binding Proteins/metabolism , SARS-CoV-2 , Toll-Like Receptor 2/metabolism
14.
Vet Microbiol ; 274: 109551, 2022 Nov.
Article in English | MEDLINE | ID: covidwho-1996617

ABSTRACT

Viroporins are virus-encoded proteins that mediate ion channel (IC) activity, playing critical roles in virus entry, replication, pathogenesis, and immune evasion. Previous studies have shown that some coronavirus accessory proteins have viroporin-like activity. Porcine deltacoronavirus (PDCoV) is an emerging enteropathogenic coronavirus that encodes three accessory proteins, NS6, NS7, and NS7a. However, whether any of the PDCoV accessory proteins possess viroporin-like activity, and if so which, remains unknown. In this study, we analyzed the biochemical properties of the three PDCoV-encoded accessory proteins and found that NS7a could enhance the membrane permeability of both mammalian cells and Escherichia coli cells. Indirect immunofluorescence assay and co-immunoprecipitation assay results further indicated that NS7a is an integral membrane protein and can form homo-oligomers. A bioinformation analysis revealed that a putative viroporin domain (VPD) is located within amino acids 69-88 (aa69-88) of NS7a. Experiments with truncated mutants and alanine scanning mutagenesis additionally demonstrated that the amino acid residues 69FLR71 of NS7a are essential for its viroporin-like activity. Together, our findings are the first to demonstrate that PDCoV NS7a possesses viroporin-like activity and identify its key amino acid residues associated with viroporin-like activity.


Subject(s)
Coronavirus Infections , Coronavirus , Swine Diseases , Swine , Animals , Viroporin Proteins , Coronavirus Infections/veterinary , Amino Acids/metabolism , Alanine/metabolism , Membrane Proteins/metabolism , Ion Channels/metabolism , Mammals
15.
J Interferon Cytokine Res ; 42(8): 430-443, 2022 08.
Article in English | MEDLINE | ID: covidwho-1992069

ABSTRACT

Interferon-induced transmembrane (IFITM) proteins mediate protection against enveloped viruses by blocking membrane fusion at endosomes. IFITM1 and IFITM3 are crucial for protection against influenza, and various single nucleotide polymorphisms altering their function have been linked to disease susceptibility. However, bulk IFITM1 and IFITM3 mRNA expression dynamics and their correlation with clinical outcomes have not been extensively addressed in patients with respiratory infections. In this study, we evaluated the expression of IFITM1 and IFITM3 in peripheral leukocytes from healthy controls and individuals with severe pandemic influenza A(H1N1) or coronavirus disease 2019 (COVID-19). Comparisons between participants grouped according to their clinical characteristics, underlying disease, and outcomes showed that the downregulation of IFITM1 was a distinctive characteristic of severe pandemic influenza A(H1N1) that correlated with outcomes, including mortality. Conversely, increased IFITM3 expression was a common feature of severe pandemic influenza A(H1N1) and COVID-19. Using a high-dose murine model of infection, we confirmed not only the downregulation of IFITM1 but also of IFITM3 in the lungs of mice with severe influenza, as opposed to humans. Analyses in the comparative cohort also indicate the possible participation of IFITM3 in COVID-19. Our results add to the evidence supporting a protective function of IFITM proteins against viral respiratory infections in humans.


Subject(s)
Antigens, Differentiation , COVID-19 , Influenza, Human , Membrane Proteins , RNA-Binding Proteins , Animals , Antigens, Differentiation/genetics , Antigens, Differentiation/metabolism , COVID-19/genetics , Humans , Influenza A Virus, H1N1 Subtype , Influenza, Human/genetics , Leukocytes/metabolism , Membrane Proteins/genetics , Membrane Proteins/metabolism , Mice , RNA-Binding Proteins/genetics , RNA-Binding Proteins/metabolism
16.
Pharmacol Res Perspect ; 10(4): e00997, 2022 08.
Article in English | MEDLINE | ID: covidwho-1990536

ABSTRACT

In the process of pharmacology education, practical teaching is an important complement to theoretical teaching. These activities include the use of experimental animals to obtain certain pharmacological parameters or to help students understand certain classical concepts. However, the growing interest in laboratory animal welfare, the rapid development of pharmacology research and the challenges of cultivating innovative pharmacy talent create a need for innovative and flexible in vitro experiments for teaching purposes. Here, we report the application of positron emission tomography (PET) imaging of 18 F-labeled fibroblast activation protein inhibitor (18 F-FAPi) to practical pharmacology teaching, enabling dynamic visualization of the distribution and excretion process of FAPi in mice. Students can quantitatively analyze the distribution of FAPi in various tissues and organs without sacrificing the mice. Furthermore, the newly implemented method resulted in highly reproducible results and was generally appreciated by the students. Additionally, the application of PET imaging in pharmacokinetic teaching can not only greatly reduce the use of experimental animals but also need not sacrificing animals. Of note is that dynamic scanning data from this project can be used for online practical teaching during COVID-19 pandemic.


Subject(s)
COVID-19 , Pandemics , Animals , Fibroblasts/metabolism , Humans , Membrane Proteins/metabolism , Mice , Positron-Emission Tomography , Tissue Distribution
17.
Cell Death Dis ; 13(8): 684, 2022 Aug 06.
Article in English | MEDLINE | ID: covidwho-1977989

ABSTRACT

Pattern recognition receptors (PRRs) and interferons (IFNs) serve as essential antiviral defense against SARS-CoV-2, the causative agent of the COVID-19 pandemic. Type III IFNs (IFN-λ) exhibit cell-type specific and long-lasting functions in auto-inflammation, tumorigenesis, and antiviral defense. Here, we identify the deubiquitinating enzyme USP22 as central regulator of basal IFN-λ secretion and SARS-CoV-2 infections in human intestinal epithelial cells (hIECs). USP22-deficient hIECs strongly upregulate genes involved in IFN signaling and viral defense, including numerous IFN-stimulated genes (ISGs), with increased secretion of IFN-λ and enhanced STAT1 signaling, even in the absence of exogenous IFNs or viral infection. Interestingly, USP22 controls basal and 2'3'-cGAMP-induced STING activation and loss of STING reversed STAT activation and ISG and IFN-λ expression. Intriguingly, USP22-deficient hIECs are protected against SARS-CoV-2 infection, viral replication, and the formation of de novo infectious particles, in a STING-dependent manner. These findings reveal USP22 as central host regulator of STING and type III IFN signaling, with important implications for SARS-CoV-2 infection and antiviral defense.


Subject(s)
COVID-19 , Interferon Type I , Membrane Proteins/metabolism , Ubiquitin Thiolesterase , Antiviral Agents/pharmacology , Humans , Interferon Type I/genetics , Interferons/metabolism , Pandemics , SARS-CoV-2 , Ubiquitin Thiolesterase/metabolism
18.
J Cell Biol ; 221(6)2022 06 06.
Article in English | MEDLINE | ID: covidwho-1960887

ABSTRACT

ß-coronaviruses reshape host cell endomembranes to form double-membrane vesicles (DMVs) for genome replication and transcription. Ectopically expressed viral nonstructural proteins nsp3 and nsp4 interact to zipper and bend the ER for DMV biogenesis. Genome-wide screens revealed the autophagy proteins VMP1 and TMEM41B as important host factors for SARS-CoV-2 infection. Here, we demonstrated that DMV biogenesis, induced by virus infection or expression of nsp3/4, is impaired in the VMP1 KO or TMEM41B KO cells. In VMP1 KO cells, the nsp3/4 complex forms normally, but the zippered ER fails to close into DMVs. In TMEM41B KO cells, the nsp3-nsp4 interaction is reduced and DMV formation is suppressed. Thus, VMP1 and TMEM41B function at different steps during DMV formation. VMP1 was shown to regulate cross-membrane phosphatidylserine (PS) distribution. Inhibiting PS synthesis partially rescues the DMV defects in VMP1 KO cells, suggesting that PS participates in DMV formation. We provide molecular insights into the collaboration of host factors with viral proteins to remodel host organelles.


Subject(s)
COVID-19 , Membrane Proteins , SARS-CoV-2 , Viral Replication Compartments , Autophagy/genetics , Humans , Membrane Proteins/genetics , Membrane Proteins/metabolism , Organelles/metabolism , Phosphatidylserines , SARS-CoV-2/physiology , Viral Nonstructural Proteins/genetics , Virus Replication
20.
ACS Chem Biol ; 17(8): 2109-2120, 2022 Aug 19.
Article in English | MEDLINE | ID: covidwho-1947197

ABSTRACT

Interferon-induced transmembrane proteins (IFITM1, 2, and 3) are important antiviral proteins that are active against many viruses, including influenza A virus (IAV), dengue virus (DENV), Ebola virus (EBOV), Zika virus (ZIKV), and severe acute respiratory syndrome coronavirus (SARS-CoV). IFITM proteins exhibit specificity in activity, but their distinct mechanisms of action and regulation are unclear. Since S-palmitoylation and cholesterol homeostasis are crucial for viral infections, we investigated IFITM interactions with cholesterol by photoaffinity cross-linking in mammalian cells along with molecular dynamic simulations and nuclear magnetic resonance analysis in vitro. These studies suggest that cholesterol can directly interact with S-palmitoylated IFITMs in cells and alter the conformation of IFITMs in membrane bilayers. Notably, we discovered that the S-palmitoylation levels regulate differential IFITM protein interactions with cholesterol in mammalian cells and specificity of antiviral activity toward IAV, SARS-CoV-2, and EBOV. Our studies suggest that modulation of IFITM S-palmitoylation levels and cholesterol interaction influence host susceptibility to different viruses.


Subject(s)
Antiviral Agents , Lipoylation , Membrane Proteins , Sterols , Animals , Antiviral Agents/pharmacology , Cholesterol/metabolism , Influenza A virus , Membrane Proteins/metabolism , Membrane Proteins/pharmacology , SARS-CoV-2 , Sterols/metabolism , Zika Virus
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