Journal articles on the topic 'Interferon-induced transmembrane proteins'
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Siegrist, Fredy, Martin Ebeling, and Ulrich Certa. "The Small Interferon-Induced Transmembrane Genes and Proteins." Journal of Interferon & Cytokine Research 31, no. 1 (January 2011): 183–97. http://dx.doi.org/10.1089/jir.2010.0112.
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Guo, Xiangyang, Jan Steinkühler, Mariana Marin, Rumiana Dimova, and Gregory Melikian. "Inhibition of Viral Fusion by Interferon-Induced Transmembrane Proteins." Biophysical Journal 120, no. 3 (February 2021): 2a. http://dx.doi.org/10.1016/j.bpj.2020.11.093.
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Qian, Jin, Yann Le Duff, Yimeng Wang, Qinghua Pan, Shilei Ding, Yi-Min Zheng, Shan-Lu Liu, and Chen Liang. "Primate lentiviruses are differentially inhibited by interferon-induced transmembrane proteins." Virology 474 (January 2015): 10–18. http://dx.doi.org/10.1016/j.virol.2014.10.015.
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Zani, Ashley, Lizhi Zhang, Temet M. McMichael, Adam D. Kenney, Mahesh Chemudupati, Jesse J. Kwiek, Shan-Lu Liu, and Jacob S. Yount. "Interferon-induced transmembrane proteins inhibit cell fusion mediated by trophoblast syncytins." Journal of Biological Chemistry 294, no. 52 (November 17, 2019): 19844–51. http://dx.doi.org/10.1074/jbc.ac119.010611.
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Hornick, Andrew L., Ni Li, Mayumi Oakland, Paul B. McCray, and Patrick L. Sinn. "Human, Pig, and Mouse Interferon-Induced Transmembrane Proteins Partially Restrict Pseudotyped Lentiviral Vectors." Human Gene Therapy 27, no. 5 (May 2016): 354–62. http://dx.doi.org/10.1089/hum.2015.156.
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Buchrieser, Julian, and Olivier Schwartz. "Pregnancy complications and Interferon-induced transmembrane proteins (IFITM): balancing antiviral immunity and placental development." Comptes Rendus. Biologies 344, no. 2 (July 2, 2021): 145–56. http://dx.doi.org/10.5802/crbiol.54.
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Narayana, Sumudu K., Karla J. Helbig, Erin M. McCartney, Nicholas S. Eyre, Rowena A. Bull, Auda Eltahla, Andrew R. Lloyd, and Michael R. Beard. "The Interferon-induced Transmembrane Proteins, IFITM1, IFITM2, and IFITM3 Inhibit Hepatitis C Virus Entry." Journal of Biological Chemistry 290, no. 43 (September 9, 2015): 25946–59. http://dx.doi.org/10.1074/jbc.m115.657346.
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Sharma, Amit, Richard N. McLaughlin, Ryan S. Basom, Caroline Kikawa, Molly OhAinle, Jacob S. Yount, Michael Emerman, and Julie Overbaugh. "Macaque interferon-induced transmembrane proteins limit replication of SHIV strains in an Envelope-dependent manner." PLOS Pathogens 15, no. 7 (July 1, 2019): e1007925. http://dx.doi.org/10.1371/journal.ppat.1007925.
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Xie, Maorong, Baoqin Xuan, Jiaoyu Shan, Deng Pan, Yamei Sun, Zhao Shan, Jinping Zhang, Dong Yu, Bin Li, and Zhikang Qian. "Human Cytomegalovirus Exploits Interferon-Induced Transmembrane Proteins To Facilitate Morphogenesis of the Virion Assembly Compartment." Journal of Virology 89, no. 6 (December 31, 2014): 3049–61. http://dx.doi.org/10.1128/jvi.03416-14.
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ABSTRACTRecently, interferon-induced transmembrane proteins (IFITMs) have been identified to be key effector molecules in the host type I interferon defense system. The invasion of host cells by a large range of RNA viruses is inhibited by IFITMs during the entry step. However, the roles of IFITMs in DNA virus infections have not been studied in detail. In this study, we report that human cytomegalovirus (HCMV), a large human DNA virus, exploits IFITMs to facilitate the formation of the virion assembly compartment (vAC) during infection of human fibroblasts. We found that IFITMs were expressed constitutively in human embryonic lung fibroblasts (MRC5 cells). HCMV infection inhibited IFITM protein accumulation in the later stages of infection. Overexpression of an IFITM protein in MRC5 cells slightly enhanced HCMV production and knockdown of IFITMs by RNA interference reduced the virus titer by about 100-fold on day 8 postinfection, according to the findings of a virus yield assay at a low multiplicity of infection. Virus gene expression and DNA synthesis were not affected, but the typical round structure of the vAC was not formed after the suppression of IFITMs, thereby resulting in defective virion assembly and the production of less infectious virion particles. Interestingly, the replication of herpes simplex virus, a human herpesvirus that is closely related to HCMV, was not affected by the suppression of IFITMs in MRC5 cells. These results indicate that IFITMs are involved in a specific pathway required for HCMV replication.IMPORTANCEHCMV is known to repurpose the interferon-stimulated genes (ISGs) viperin and tetherin to facilitate its replication. Our results expand the range of ISGs that can be exploited by HCMV for its replication. This is also the first report of a proviral function of IFITMs in DNA virus replication. In addition, whereas previous studies showed that IFITMs modulate virus entry, which is a very early stage in the virus life cycle, we identified a new function of IFITMs during the very late stage of virus replication, i.e., virion assembly. Virus entry and assembly both involve vesicle transport and membrane fusion; thus, a common biochemical activity of IFITMs is likely to be involved. Therefore, our findings may provide a new platform for dissecting the molecular mechanism of action of IFITMs during the blocking or enhancement of virus infection, which are under intense investigation in this field.
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Wrensch, Florian, Gaëtan Ligat, Laura Heydmann, Catherine Schuster, Mirjam B. Zeisel, Patrick Pessaux, François Habersetzer, et al. "Interferon‐Induced Transmembrane Proteins Mediate Viral Evasion in Acute and Chronic Hepatitis C Virus Infection." Hepatology 70, no. 5 (June 21, 2019): 1506–20. http://dx.doi.org/10.1002/hep.30699.
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Rohaim, Mohammed A., Mohammad Q. Al-Natour, Mohammed A. Abdelsabour, Rania F. El Naggar, Yahia M. Madbouly, Kawkab A. Ahmed, and Muhammad Munir. "Transgenic Chicks Expressing Interferon-Inducible Transmembrane Protein 1 (IFITM1) Restrict Highly Pathogenic H5N1 Influenza Viruses." International Journal of Molecular Sciences 22, no. 16 (August 6, 2021): 8456. http://dx.doi.org/10.3390/ijms22168456.
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Mammalian cells utilize a wide spectrum of pathways to antagonize the viral replication. These pathways are typically regulated by antiviral proteins and can be constitutively expressed but also exacerbated by interferon induction. A myriad of interferon-stimulated genes (ISGs) have been identified in mounting broad-spectrum antiviral responses. Members of the interferon-induced transmembrane (IFITM) family of proteins are unique among these ISGs due to their ability to prevent virus entry through the lipid bilayer into the cell. In the current study, we generated transgenic chickens that constitutively and stably expressed chicken IFITM1 (chIFITM1) using the avian sarcoma-leukosis virus (RCAS)-based gene transfer system. The challenged transgenic chicks with clinical dose 104 egg infective dose 50 (EID50) of highly pathogenic avian influenza virus (HPAIV) subtype H5N1 (clade 2.2.1.2) showed 100% protection and significant infection tolerance. Although challenged transgenic chicks displayed 60% protection against challenge with the sub-lethal dose (EID50 105), the transgenic chicks showed delayed clinical symptoms, reduced virus shedding, and reduced histopathologic alterations compared to non-transgenic challenged control chickens. These finding indicate that the sterile defense against H5N1 HPAIV offered by the stable expression of chIFITM1 is inadequate; however, the clinical outcome can be substantially ameliorated. In conclusion, chIFITM proteins can inhibit influenza virus replication that can infect various host species and could be a crucial barrier against zoonotic infections.
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Fu, Bishi, Lingyan Wang, Shitao Li, and Martin E. Dorf. "ZMPSTE24 defends against influenza and other pathogenic viruses." Journal of Experimental Medicine 214, no. 4 (February 28, 2017): 919–29. http://dx.doi.org/10.1084/jem.20161270.
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Zinc metallopeptidase STE24 (ZMPSTE24) is a transmembrane metalloprotease whose catalytic activity is critical for processing lamin A on the inner nuclear membrane and clearing clogged translocons on the endoplasmic reticulum. We now report ZMPSTE24 is a virus-specific effector that restricts enveloped RNA and DNA viruses, including influenza A, Zika, Ebola, Sindbis, vesicular stomatitis, cowpox, and vaccinia, but not murine leukemia or adenovirus. ZMPSTE24-mediated antiviral action is independent of protease activity. Coimmunoprecipitation studies indicate ZMPSTE24 can complex with proteins of the interferon-induced transmembrane protein (IFITM) family. IFITM proteins impede viral entry, and ZMPSTE24 expression is necessary for IFITM antiviral activity. In vivo studies demonstrate ZMPSTE24-deficient mice display higher viral burdens, enhanced cytokine production, and increased mortality after influenza infection. Collectively, these findings identify ZMPSTE24 as an intrinsic broad-spectrum antiviral protein and provide insights into antiviral defense mechanisms.
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Li, Shitao, Lingyan Wang, Bishi Fu, and Martin E. Dorf. "ZMPSTE24 is a novel intrinsic immune protein that restricts a broad-spectrum of viruses." Journal of Immunology 196, no. 1_Supplement (May 1, 2016): 217.9. http://dx.doi.org/10.4049/jimmunol.196.supp.217.9.
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Abstract Virus entry begins with attachment to cell-surface receptors and ends with delivery of the viral genome into the cytoplasm. Many enveloped viruses are ferried deep into the cytoplasm through endocytic vesicles and utilize the low pH endosomal environment to activate the fusion process between viral and cellular membranes. Higher vertebrates evolved interferon-induced transmembrane proteins (IFITM) to impede endocytic penetration by a broad spectrum of RNA viruses. However, the molecular mechanism by which IFITM proteins hinder viral entry is not well elucidated. To address the antiviral mechanism of IFITM, we hypothesize that type I interferon (IFN) induces recruitment of co-factors to the IFITM3 protein complex. Proteomic analysis of IFITM3-FLAG protein complex in HEK293 cells revealed that IFN induced IFITM3 to recruit ZMPSTE24, the 7-pass transmembrane zinc metalloprotease whose function in cytoplasmic organelles is not defined. Contrary to IFITM, ZMPSTE24 mRNA and protein expression are not regulated by IFN. But consistent with IFITM, ZMPSTE24 restricts both RNA and DNA viruses using endocytic entry, including influenza A, vesicular stomatitis, sindbis, Ebola, cowpox and vaccinia viruses. Antiviral activity requires ZMPSTE24 endosomal localization and is independent of its protease activity. Furthermore, ZMPSTE24 is recruited to endosomes by IFITM and block viral endocytic entry. These findings identify a new role for ZMPSTE24 as a broad-spectrum intrinsic antiviral protein and the downstream antiviral effector of IFITM.
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Weidner, Jessica M., Dong Jiang, Xiao-Ben Pan, Jinhong Chang, Timothy M. Block, and Ju-Tao Guo. "Interferon-Induced Cell Membrane Proteins, IFITM3 and Tetherin, Inhibit Vesicular Stomatitis Virus Infection via Distinct Mechanisms." Journal of Virology 84, no. 24 (October 13, 2010): 12646–57. http://dx.doi.org/10.1128/jvi.01328-10.
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ABSTRACT Tetherin and IFITM3 are recently identified interferon-induced cellular proteins that restrict infections by retroviruses and filoviruses and of influenza virus and flaviviruses, respectively. In our efforts to further explore their antiviral activities against other viruses and determine their antiviral mechanisms, we found that the two antiviral proteins potently inhibit the infection of vesicular stomatitis virus (VSV), a prototype member of the Rhabdoviridae family. Taking advantage of this well-studied virus infection system, we show that although both tetherin and IFITM3 are plasma membrane proteins, tetherin inhibits virion particle release from infected cells, while IFITM3 disrupts an early event after endocytosis of virion particles but before primary transcription of incoming viral genomes. Furthermore, we demonstrate that both the N-terminal 21 amino acid residues and C-terminal transmembrane region of IFITM3 are required for its antiviral activity. Collectively, our work sheds light on the mechanisms by which tetherin and IFITM3 restrict infection with rhabdoviruses and possibly other pathogenic viruses.
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Lou, Kevin, Douglas R. Wassarman, Tangpo Yang, YiTing Paung, Ziyang Zhang, Thomas A. O’Loughlin, Megan K. Moore, et al. "IFITM proteins assist cellular uptake of diverse linked chemotypes." Science 378, no. 6624 (December 9, 2022): 1097–104. http://dx.doi.org/10.1126/science.abl5829.
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The search for cell-permeable drugs has conventionally focused on low-molecular weight (MW), nonpolar, rigid chemical structures. However, emerging therapeutic strategies break traditional drug design rules by employing flexibly linked chemical entities composed of more than one ligand. Using complementary genome-scale chemical-genetic approaches we identified an endogenous chemical uptake pathway involving interferon-induced transmembrane proteins (IFITMs) that modulates the cell permeability of a prototypical biopic inhibitor of MTOR (RapaLink-1, MW: 1784 g/mol). We devised additional linked inhibitors targeting BCR-ABL1 (DasatiLink-1, MW: 1518 g/mol) and EIF4A1 (BisRoc-1, MW: 1466 g/mol), uptake of which was facilitated by IFITMs. We also found that IFITMs moderately assisted some proteolysis-targeting chimeras and examined the physicochemical requirements for involvement of this uptake pathway.
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Motani, Kou, and Hidetaka Kosako. "BioID screening of biotinylation sites using the avidin-like protein Tamavidin 2-REV identifies global interactors of stimulator of interferon genes (STING)." Journal of Biological Chemistry 295, no. 32 (June 17, 2020): 11174–83. http://dx.doi.org/10.1074/jbc.ra120.014323.
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Stimulator of interferon genes (STING) mediates cytosolic DNA-induced innate immune signaling via membrane trafficking. The global identification of proteins that spatiotemporally interact with STING will provide a better understanding of its trafficking mechanisms and of STING signaling pathways. Proximity-dependent biotin identification (BioID) is a powerful technology to identify physiologically relevant protein-protein interactions in living cells. However, biotinylated peptides are rarely detected in the conventional BioID method, which uses streptavidin beads to pull down biotinylated proteins, because the biotin-streptavidin interaction is too strong. As a result, only nonbiotinylated peptides are identified, which cannot be distinguished from peptides of nonspecifically pull-downed proteins. Here, we developed a simple method to efficiently and specifically enrich biotinylated peptides using Tamavidin 2-REV, an engineered avidin-like protein with reversible biotin-binding capability. Using RAW264.7 macrophages stably expressing TurboID-fused STING, we identified and quantified >4,000 biotinylated peptides of STING-proximal proteins. Various endoplasmic reticulum-associated proteins were biotinylated in unstimulated cells, and STING activation caused biotinylation of many proteins located in the Golgi and endosomes. These proteins included those known to interact with activated STING, such as TANK-binding kinase 1 (TBK1), several palmitoyl transferases, and p62/sequestosome 1 (SQSTM1). Furthermore, interferon-induced transmembrane protein 3 (IFITM3), an endolysosome-localized antiviral protein, bound to STING at the late activation stage. These dynamic interaction profiles will provide detailed insights into STING signaling; we propose that our approach using Tamavidin 2-REV would be useful for BioID-based and other biotinylation-based peptide identification methods.
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Löchte, Sara, Sharon Waichman, Oliver Beutel, Changjiang You, and Jacob Piehler. "Live cell micropatterning reveals the dynamics of signaling complexes at the plasma membrane." Journal of Cell Biology 207, no. 3 (November 10, 2014): 407–18. http://dx.doi.org/10.1083/jcb.201406032.
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Interactions of proteins in the plasma membrane are notoriously challenging to study under physiological conditions. We report in this paper a generic approach for spatial organization of plasma membrane proteins into micropatterns as a tool for visualizing and quantifying interactions with extracellular, intracellular, and transmembrane proteins in live cells. Based on a protein-repellent poly(ethylene glycol) polymer brush, micropatterned surface functionalization with the HaloTag ligand for capturing HaloTag fusion proteins and RGD peptides promoting cell adhesion was devised. Efficient micropatterning of the type I interferon (IFN) receptor subunit IFNAR2 fused to the HaloTag was achieved, and highly specific IFN binding to the receptor was detected. The dynamics of this interaction could be quantified on the single molecule level, and IFN-induced receptor dimerization in micropatterns could be monitored. Assembly of active signaling complexes was confirmed by immunostaining of phosphorylated Janus family kinases, and the interaction dynamics of cytosolic effector proteins recruited to the receptor complex were unambiguously quantified by fluorescence recovery after photobleaching.
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Wan, Wang, Chen, Zhu, Shang, Xiao, and Zhang. "A Subcellular Quantitative Proteomic Analysis of Herpes Simplex Virus Type 1-Infected HEK 293T Cells." Molecules 24, no. 23 (November 20, 2019): 4215. http://dx.doi.org/10.3390/molecules24234215.
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Herpes simplex virus type 1 (HSV-1) is widespread double-stranded DNA (dsDNA) virus that establishes life-long latency and causes diverse severe symptoms. The mechanisms of HSV-1 infection and HSV-1’s interactions with various host cells have been studied and reviewed extensively. Type I interferons were secreted by host cells upon HSV infection and play a vital role in controlling virus proliferation. A few studies, however, have focused on HSV-1 infection without the presence of interferon (IFN) signaling. In this study, HEK 293T cells with low toll-like receptor (TLR) and stimulator of interferon genes protein (STING) expression were infected with HSV-1 and subjected to a quantitative proteomic analysis. By using a subcellular fractionation strategy and high-performance mass spectrometry, a total of 6607 host proteins were quantified, of which 498 proteins were differentially regulated. A bioinformatics analysis indicated that multiple signaling pathways might be involved in HSV-1 infection. A further functional study indicated the role of Interferon-induced transmembrane protein 3 (IFITM3), Coiled-coil-helix-coiled-coil-helix domain-containing protein 2 (CHCHD2), and Tripartite motif-containing protein 27 (TRIM27) in inhibiting viral DNA replication and proliferation. Our data provide a global view of host responses to HSV-1 infection in HEK 293T cells and identify the proteins involved in the HSV-1 infection process.
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Hsin, Fu, Yu-Chen Hsu, Yu-Fei Tsai, Shu-Wha Lin, and Helene Minyi Liu. "The transmembrane serine protease hepsin suppresses type I interferon induction by cleaving STING." Science Signaling 14, no. 687 (June 15, 2021): eabb4752. http://dx.doi.org/10.1126/scisignal.abb4752.
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Many viral proteases mediate the evasion of antiviral innate immunity by cleaving adapter proteins in the interferon (IFN) induction pathway. Host proteases are also involved in innate immunity and inflammation. Here, we report that the transmembrane protease hepsin (also known as TMPRSS1), which is predominantly present in hepatocytes, inhibited the induction of type I IFN during viral infections. Knocking out hepsin in mouse embryonic fibroblasts (MEFs) increased the viral infection–induced expression of Ifnb1, an Ifnb1 promoter reporter, and an IFN-sensitive response element promoter reporter. Ectopic expression of hepsin in cultured human hepatocytes and HEK293T cells suppressed the induction of IFNβ during viral infections by reducing the abundance of STING. These effects depended on the protease activity of hepsin. We identified a putative hepsin target site in STING and showed that mutating this site protected STING from hepsin-mediated cleavage. In addition to hepatocytes, several hepsin-producing prostate cancer cell lines showed reduced STING-mediated type I IFN induction and responses. These results reveal a role for hepsin in suppressing STING-mediated type I IFN induction, which may contribute to the vulnerability of hepatocytes to chronic viral infections.
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Minakshi, Rinki. "Interferon-Induced Transmembrane Protein: A Moonlighting Protein Against SARS-CoV-2 Infection or in Support of Invasive Ductal Breast Carcinoma?" Asian Pacific Journal of Cancer Care 5, S1 (September 15, 2020): 241–42. http://dx.doi.org/10.31557/apjcc.2020.5.s1.241-242.
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The interferon-induced transmembrane proteins (IFITMs), widely acting against invading viruses are ubiquitously expressed on the cellular membranes, were previously known for their prominent role in tumorigenesis. Studies productively showed that the entry restriction on SARS-CoV spike glycoprotein agreeably involved the action of frontier IFITM1, 2 and 3. On the contrary, overexpression of IFITM3 has been reported in Invasive ductal breast carcinoma (IDC) tissue specimens where lentivirus-delivered shRNA resulted in targeted silencing of IFITM3 mRNA expression. Despite acting protective against virus infection, expression of IFITM favors cancer migration as seen in IDC. The existence of such a phenomenon wherein a choice is made by the selection pressure on IFITM allele frequency in human population between opposing roles of the protein, needs to be untangled.
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Seyfried, Nicholas T., Leanne C. Huysentruyt, James A. Atwood, Qiangwei Xia, Thomas N. Seyfried, and Ron Orlando. "Up-regulation of NG2 proteoglycan and interferon-induced transmembrane proteins 1 and 3 in mouse astrocytoma: A membrane proteomics approach." Cancer Letters 263, no. 2 (May 2008): 243–52. http://dx.doi.org/10.1016/j.canlet.2008.01.007.
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Wang, Anqi, Lipei Sun, Mingshu Wang, Renyong Jia, Dekang Zhu, Mafeng Liu, Kunfeng Sun, et al. "Identification of IFITM1 and IFITM3 in Goose: Gene Structure, Expression Patterns, and Immune Reponses against Tembusu Virus Infection." BioMed Research International 2017 (2017): 1–13. http://dx.doi.org/10.1155/2017/5149062.
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As interferon-stimulated genes (ISGs), interferon-inducible transmembrane proteins 1 and 3 (IFITM1 and IFITM3) can effectively inhibit the replication of multiple viruses. Here, goose IFITM1 and IFITM3 were cloned and identified for the first time. The two proteins share the same topological structure and several important sites critical for the antiviral functions in other species are conserved in the goose. Goose IFITM1 and IFITM3 are most closely related to their respective orthologs in ducks; these proteins exhibited high mRNA transcript levels in immune-related tissues, including the thymus, bursa of Fabricius, and Harderian gland, compared to other tissues. Moreover, goose IFITM1 was highly constitutively expressed in gastrointestinal tract tissues, while goose IFITM3 was expressed in respiratory organs. Furthermore, goose IFITM3 was activated in goose peripheral blood mononuclear cells (PBMCs) infected with Tembusu virus (TMUV) or treated with Toll-like receptors (TLRs) agonists, while only the R848 and Poly (I:C) agonists induced significant upregulation of goose IFITM1. Furthermore, goose IFITM1 and IFITM3 were upregulated in the sampled tissues, to some extent, after TMUV infection. Notably, significant upregulation of goose IFITM1 and IFITM3 was detected in the cecum and cecal tonsil, where TMUV was primarily distributed. These data provide new insights into the immune effectors in geese and promote our understanding of the role of IFITM1 and IFITM3 in the defense against TMUV.
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Gorman, Matthew J., Subhajit Poddar, Michael Farzan, and Michael S. Diamond. "The Interferon-Stimulated GeneIfitm3Restricts West Nile Virus Infection and Pathogenesis." Journal of Virology 90, no. 18 (July 6, 2016): 8212–25. http://dx.doi.org/10.1128/jvi.00581-16.
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ABSTRACTThe interferon-induced transmembrane protein (IFITM) family of proteins inhibit infection of several different enveloped viruses in cell culture by virtue of their ability to restrict entry and fusion from late endosomes. As few studies have evaluated the importance ofIfitm3 in vivoin restricting viral pathogenesis, we investigated its significance as an antiviral gene against West Nile virus (WNV), an encephalitic flavivirus, in cells and mice.Ifitm3−/−mice were more vulnerable to lethal WNV infection, and this was associated with greater virus accumulation in peripheral organs and central nervous system tissues. As no difference in viral burden in the brain or spinal cord was observed after direct intracranial inoculation, Ifitm3 likely functions as an antiviral protein in nonneuronal cells. Consistent with this,Ifitm3−/−fibroblasts but not dendritic cells resulted in higher yields of WNV in multistep growth analyses. Moreover, transcomplementation experiments showed that Ifitm3 inhibited WNV infection independently of Ifitm1, Ifitm2, Ifitm5, and Ifitm6. Beyond a direct effect on viral infection in cells, analysis of the immune response in WNV-infectedIfitm3−/−mice showed decreases in the total number of B cells, CD4+T cells, and antigen-specific CD8+T cells. Finally, bone marrow chimera experiments demonstrated that Ifitm3 functioned in both radioresistant and radiosensitive cells, as higher levels of WNV were observed in the brain only when Ifitm3 was absent from both compartments. Our analyses suggest that Ifitm3 restricts WNV pathogenesis likely through multiple mechanisms, including the direct control of infection in subsets of cells.IMPORTANCEAs part of the mammalian host response to viral infections, hundreds of interferon-stimulated genes (ISGs) are induced. The inhibitory activity of individual ISGs varies depending on the specific cell type and viral pathogen. Among ISGs, the genes encoding interferon-induced transmembrane protein (IFITM) have been reported to inhibit multiple families of viruses in cell culture. However, few reports have evaluated the impact ofIFITMgenes on viral pathogenesisin vivo. In this study, we characterized the antiviral activity of Ifitm3 against West Nile virus (WNV), an encephalitic flavivirus, using mice with a targeted gene deletion ofIfitm3. Based on extensive virological and immunological analyses, we determined that Ifitm3 protects mice from WNV-induced mortality by restricting virus accumulation in peripheral organs and, subsequently, in central nervous system tissues. Our data suggest that Ifitm3 restricts WNV pathogenesis by multiple mechanisms and functions in part by controlling infection in different cell types.
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Зарипова, А. Р., Л. Р. Нургалиева, А. В. Тюрин, И. Р. Минниахметов, and Р. И. Хусаинова. "Search for mutations of the interferon-induced transmembrane protein 5 (IFITM5) gene in patients with osteogenesis imperfecta." Nauchno-prakticheskii zhurnal «Medicinskaia genetika», no. 10() (October 30, 2019): 21–29. http://dx.doi.org/10.25557/2073-7998.2019.10.21-29.
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Проведено исследование гена интерферон индуцированного трансмембранного белка 5 (IFITM5) у 99 пациентов с несовершенным остеогенезом (НО) из 86 неродственных семей. НО - клинически и генетически гетерогенное наследственное заболевание соединительной ткани, основное клиническое проявление которого - множественные переломы, начиная с неонатального периода жизни, зачастую приводящие к инвалидизации с детского возраста. К основным клиническим признакам НО относятся голубые склеры, потеря слуха, аномалия дентина, повышенная ломкость костей, нарушения роста и осанки с развитием характерных инвалидизирующих деформаций костей и сопутствующих проблем, включающих дыхательные, неврологические, сердечные, почечные нарушения. НО встречается как у мужчин, так и у женщин. До сих пор не определена степень генетической гетерогенности заболевания. На сегодняшний день известно 20 генов, вовлеченных в патогенез НО, и исследователи разных стран продолжают искать новые гены. В последнее десятилетие стало известно, что аутосомно-рецессивные, аутосомно-доминантные и Х-сцепленные мутации в широком спектре генов, кодирующих белки, которые участвуют в синтезе коллагена I типа, его процессинге, секреции и посттрансляционной модификации, а также в белках, которые регулируют дифференцировку и активность костеобразующих клеток, вызывают НО. Мутации в гене IFITM5, также называемом BRIL (bone-restricted IFITM-like protein), участвующем в формировании остеобластов, приводят к развитию НО типа V. До 5% пациентов имеют НО типа V, который характеризуется образованием гиперпластического каллуса после переломов, кальцификацией межкостной мембраны предплечья и сетчатым рисунком ламелирования, наблюдаемого при гистологическом исследовании кости. В 2012 г. гетерозиготная мутация (c.-14C> T) в 5’-нетранслируемой области (UTR) гена IFITM5 была идентифицирована как основная причина НО V типа. В представленной работе проведен анализ гена IFITM5 и идентифицирована мутация c.-14C>T, возникшая de novo, у одного пациента с НО, которому впоследствии был установлен V тип заболевания. Также выявлены три известных полиморфных варианта: rs57285449; c.80G>C (p.Gly27Ala) и rs2293745; c.187-45C>T и rs755971385 c.279G>A (p.Thr93=) и один ранее не описанный вариант: c.128G>A (p.Ser43Asn) AGC>AAC (S/D), которые не являются патогенными. В статье уделяется внимание особенностям клинических проявлений НО V типа и рекомендуется определение мутации c.-14C>T в гене IFITM5 при подозрении на данную форму заболевания. A study was made of interferon-induced transmembrane protein 5 gene (IFITM5) in 99 patients with osteogenesis imperfecta (OI) from 86 unrelated families and a search for pathogenic gene variants involved in the formation of the disease phenotype. OI is a clinically and genetically heterogeneous hereditary disease of the connective tissue, the main clinical manifestation of which is multiple fractures, starting from the natal period of life, often leading to disability from childhood. The main clinical signs of OI include blue sclera, hearing loss, anomaly of dentin, increased fragility of bones, impaired growth and posture, with the development of characteristic disabling bone deformities and associated problems, including respiratory, neurological, cardiac, and renal disorders. OI occurs in both men and women. The degree of genetic heterogeneity of the disease has not yet been determined. To date, 20 genes are known to be involved in the pathogenesis of OI, and researchers from different countries continue to search for new genes. In the last decade, it has become known that autosomal recessive, autosomal dominant and X-linked mutations in a wide range of genes encoding proteins that are involved in the synthesis of type I collagen, its processing, secretion and post-translational modification, as well as in proteins that regulate the differentiation and activity of bone-forming cells cause OI. Mutations in the IFITM5 gene, also called BRIL (bone-restricted IFITM-like protein), involved in the formation of osteoblasts, lead to the development of OI type V. Up to 5% of patients have OI type V, which is characterized by the formation of a hyperplastic callus after fractures, calcification of the interosseous membrane of the forearm, and a mesh lamellar pattern observed during histological examination of the bone. In 2012, a heterozygous mutation (c.-14C> T) in the 5’-untranslated region (UTR) of the IFITM5 gene was identified as the main cause of OI type V. In the present work, the IFITM5 gene was analyzed and the de novo c.-14C> T mutation was identified in one patient with OI who was subsequently diagnosed with type V of the disease. Three known polymorphic variants were also identified: rs57285449; c.80G> C (p.Gly27Ala) and rs2293745; c.187-45C> T and rs755971385 c.279G> A (p.Thr93 =) and one previously undescribed variant: c.128G> A (p.Ser43Asn) AGC> AAC (S / D), which were not pathogenic. The article focuses on the features of the clinical manifestations of OI type V, and it is recommended to determine the c.-14C> T mutation in the IFITM5 gene if this form of the disease is suspected.
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Confort, Marie-Pierre, Maëva Duboeuf, Adrien Thiesson, Léa Pons, Federico Marziali, Sophie Desloire, Maxime Ratinier, Andrea Cimarelli, and Frédérick Arnaud. "IFITMs from Naturally Infected Animal Species Exhibit Distinct Restriction Capacities against Toscana and Rift Valley Fever Viruses." Viruses 15, no. 2 (January 22, 2023): 306. http://dx.doi.org/10.3390/v15020306.
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Rift Valley Fever virus (RVFV) and Toscana virus (TOSV) are two pathogenic arthropod-borne viruses responsible for zoonotic infections in both humans and animals; as such, they represent a growing threat to public and veterinary health. Interferon-induced transmembrane (IFITM) proteins are broad inhibitors of a large panel of viruses belonging to various families and genera. However, little is known on the interplay between RVFV, TOSV, and the IFITM proteins derived from their naturally infected host species. In this study, we investigated the ability of human, bovine, and camel IFITMs to restrict RVFV and TOSV infection. Our results indicated that TOSV was extremely sensitive to inhibition by all the animal IFITMs tested, while RVFV was inhibited by human IFITM-2 and IFITM-3, but not IFITM-1,and exhibited a more heterogeneous resistance phenotype towards the individual bovine and camel IFITMs tested. Overall, our findings shed some light on the complex and differential interplay between two zoonotic viruses and IFITMs from their naturally infected animal species.
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Nie, Ying, Bangkun Yang, Junfeng Hu, Lingling Zhang, and Zhimin Ma. "Bruceine D ameliorates the balance of Th1/Th2 in a mouse model of ovalbumin-induced allergic asthma via inhibiting the NOTCH pathway." Allergologia et Immunopathologia 49, no. 6 (November 4, 2021): 73–79. http://dx.doi.org/10.15586/aei.v49i6.499.
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Allergic asthma is a heterogeneous inflammatory disorder triggered by inhaled allergens, leading to airflow obstruction, bronchial inflammation, and airway hyperresponsiveness (AHR). T helper (Th) 2 cell-mediated immune response and airway inflammation are the key features of allergic asthma. Bruceine D (BD) is a bioactive compound extracted from the seeds of Brucea javanica. The present study aimed to investigate the effects of increased doses of BD on AHR, secretion of Th1-/Th2-associated cytokines, and inflammatory cell infiltration in ovalbumin (OVA)-induced allergic asthma mice. The results showed that BD reduced OVA-induced inflammatory cell infiltration and bronchial hyperresponsiveness into the peribronchial tissues and perivascular areas. Mice treated with BD also showed significantly decreased expressions of Th2-associated cytokines (i.e., interleukin (IL)-4, IL-5, and IL-13) and elevated production of Th1-associated cytokines (i.e., interferon gamma and IL-2) following OVA stimulation. BD treatment dose-dependently inhibited OVA-induced accumulation of inflammatory cells in asthmatic mice. Further analysis revealed that OVA exposure upregulated pulmonary expressions of NOTCH signaling receptors, a group of transmembrane proteins that communicate signals upon binding to transmembrane ligands expressed on adjacent cells, while BD treatment significantly abolished OVA-induced activation of the NOTCH pathway. In conclusion, BD protected mice against OVA-induced allergic asthma by reducing AHR and restoring the Th1/Th2 balance through the NOTCH signaling pathway. Our findings highlighted the potential of BD as a therapeutic agent for allergic asthma.
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Foldi, Julia, Xiaoyu Hu, Allen Y. Chung, and Lionel B. Ivashkiv. "Regulation of Notch ligands by the TLR and IFN-γ pathways in macrophages (135.63)." Journal of Immunology 182, no. 1_Supplement (April 1, 2009): 135.63. http://dx.doi.org/10.4049/jimmunol.182.supp.135.63.
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Abstract Jagged and Delta proteins are transmembrane ligands for the Notch family of receptors. The role for Notch and its ligands in innate immunity remains largely unknown. Our lab recently identified a subset of Toll like receptor (TLR)-inducible genes that were activated synergistically, by TLR-ligands and the Notch pathway. Some of these genes were also regulated by interferon (IFN)-γ, a potent macrophage activator. To further elucidate the role of the Notch pathway in innate immunity, we would like to know how Notch ligands are regulated in macrophages. We found that Jagged-1 and Delta-like (Dll)-1 were induced by TLR ligation and were regulated by IFN-γ in CD14+ primary human monocytes and in mouse bone-marrow-derived macrophages. TLR-induced upregulation of Jagged-1 was independent of de novo protein synthesis and the mitogen activated protein kinase (MAPK) pathway, while the nuclear factor (NF)-κB and Notch pathways played a role in this process. IFN-γ pre-treatment of cells super-induced TLR-stimulated Jagged-1, while it inhibited Dll-1 upregulation. In conclusion, Jagged and Delta proteins are synergistically regulated by the TLR, Notch and IFN-γ pathways in macrophages. This work is supported by the Cancer Research Institute (CRI) Predoctoral Fellowship.
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Fricke, Thomas, Sarah Schlagowski, Shanchuan Liu, Xiaoliang Yang, Uwe Fiebig, Artur Kaul, Armin Ensser, and Alexander S. Hahn. "Comparison of a Genotype 1 and a Genotype 2 Macaque Foamy Virus env Gene Indicates Distinct Infectivity and Cell-Cell Fusion but Similar Tropism and Restriction of Cell Entry by Interferon-Induced Transmembrane Proteins." Viruses 15, no. 2 (January 17, 2023): 262. http://dx.doi.org/10.3390/v15020262.
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Foamy viruses (FVs) are naturally found in many different animals and also in primates with the notable exception of humans, but zoonotic infections are common. In several species, two different envelope (env) gene sequence clades or genotypes exist. We constructed a simian FV (SFV) clone containing a reporter gene cassette. In this background, we compared the env genes of the SFVmmu-DPZ9524 (genotype 1) and of the SFVmmu_R289hybAGM (genotype 2) isolates. SFVmmu_R289hybAGM env-driven infection was largely resistant to neutralization by SFVmmu-DPZ9524-neutralizing sera. While SFVmmu_R289hybAGM env consistently effected higher infectivity and cell-cell fusion, we found no differences in the cell tropism conferred by either env across a range of different cells. Infection by both viruses was weakly and non-significantly enhanced by simultaneous knockout of interferon-induced transmembrane proteins (IFITMs) 1, 2, and 3 in A549 cells, irrespective of prior interferon stimulation. Infection was modestly reduced by recombinant overexpression of IFITM3, suggesting that the SFV entry step might be weakly restricted by IFITM3 under some conditions. Overall, our results suggest that the different env gene clades in macaque foamy viruses induce genotype-specific neutralizing antibodies without exhibiting overt differences in cell tropism, but individual env genes may differ significantly with regard to fitness.
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Franz, Sergej, Fabian Pott, Thomas Zillinger, Christiane Schüler, Sandra Dapa, Carlo Fischer, Vânia Passos, et al. "Human IFITM3 restricts chikungunya virus and Mayaro virus infection and is susceptible to virus-mediated counteraction." Life Science Alliance 4, no. 7 (June 2, 2021): e202000909. http://dx.doi.org/10.26508/lsa.202000909.
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Interferon-induced transmembrane (IFITM) proteins restrict membrane fusion and virion internalization of several enveloped viruses. The role of IFITM proteins during alphaviral infection of human cells and viral counteraction strategies are insufficiently understood. Here, we characterized the impact of human IFITMs on the entry and spread of chikungunya virus and Mayaro virus and provide first evidence for a CHIKV-mediated antagonism of IFITMs. IFITM1, 2, and 3 restricted infection at the level of alphavirus glycoprotein-mediated entry, both in the context of direct infection and cell-to-cell transmission. Relocalization of normally endosomal IFITM3 to the plasma membrane resulted in loss of antiviral activity. rs12252-C, a naturally occurring variant of IFITM3 that may associate with severe influenza in humans, restricted CHIKV, MAYV, and influenza A virus infection as efficiently as wild-type IFITM3. Antivirally active IFITM variants displayed reduced cell surface levels in CHIKV-infected cells involving a posttranscriptional process mediated by one or several nonstructural protein(s) of CHIKV. Finally, IFITM3-imposed reduction of specific infectivity of nascent particles provides a rationale for the necessity of a virus-encoded counteraction strategy against this restriction factor.
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Zhong, Li, Yuxin Song, Federico Marziali, Rustem Uzbekov, Xuan-Nhi Nguyen, Chloé Journo, Philippe Roingeard, and Andrea Cimarelli. "A novel domain within the CIL regulates egress of IFITM3 from the Golgi and reveals a regulatory role of IFITM3 on the secretory pathway." Life Science Alliance 5, no. 7 (April 8, 2022): e202101174. http://dx.doi.org/10.26508/lsa.202101174.
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The InterFeron-Induced TransMembrane proteins (IFITMs) are members of the dispanin/CD225 family that act as broad viral inhibitors by preventing viral-to-cellular membrane fusion. In this study, we uncover egress from the Golgi as an important step in the biology of IFITM3 by identifying the domain that regulates this process and that similarly controls the egress of the dispanins IFITM1 and PRRT2, protein linked to paroxysmal kinesigenic dyskinesia. In the case of IFITM3, high levels of expression of wild-type, or mutations in the Golgi egress domain, lead to accumulation of IFITM3 in the Golgi and drive generalized glycoprotein trafficking defects. These defects can be relieved upon incubation with Amphotericin B, compound known to relieve IFITM-driven membrane fusion defects, as well as by v-SNARE overexpression, suggesting that IFITM3 interferes with membrane fusion processes important for Golgi functionalities. The comparison of glycoprotein trafficking in WT versus IFITMs-KO cells indicates that the modulation of the secretory pathway is a novel feature of IFITM proteins. Overall, our study defines a novel domain that regulates the egress of several dispanin/CD225 members from the Golgi and identifies a novel modulatory function for IFITM3.
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Percher, Avital, Srinivasan Ramakrishnan, Emmanuelle Thinon, Xiaoqiu Yuan, Jacob S. Yount, and Howard C. Hang. "Mass-tag labeling reveals site-specific and endogenous levels of protein S-fatty acylation." Proceedings of the National Academy of Sciences 113, no. 16 (April 4, 2016): 4302–7. http://dx.doi.org/10.1073/pnas.1602244113.
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Fatty acylation of cysteine residues provides spatial and temporal control of protein function in cells and regulates important biological pathways in eukaryotes. Although recent methods have improved the detection and proteomic analysis of cysteine fatty (S-fatty) acylated proteins, understanding how specific sites and quantitative levels of this posttranslational modification modulate cellular pathways are still challenging. To analyze the endogenous levels of protein S-fatty acylation in cells, we developed a mass-tag labeling method based on hydroxylamine-sensitivity of thioesters and selective maleimide-modification of cysteines, termed acyl-PEG exchange (APE). We demonstrate that APE enables sensitive detection of protein S-acylation levels and is broadly applicable to different classes of S-palmitoylated membrane proteins. Using APE, we show that endogenous interferon-induced transmembrane protein 3 is S-fatty acylated on three cysteine residues and site-specific modification of highly conserved cysteines are crucial for the antiviral activity of this IFN-stimulated immune effector. APE therefore provides a general and sensitive method for analyzing the endogenous levels of protein S-fatty acylation and should facilitate quantitative studies of this regulated and dynamic lipid modification in biological systems.
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Brown, Christopher W., Kyle B. Stephenson, Stephen Hanson, Michael Kucharczyk, Roy Duncan, John C. Bell, and Brian D. Lichty. "The p14 FAST Protein of Reptilian Reovirus Increases Vesicular Stomatitis Virus Neuropathogenesis." Journal of Virology 83, no. 2 (October 29, 2008): 552–61. http://dx.doi.org/10.1128/jvi.01921-08.
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ABSTRACT The fusogenic orthoreoviruses express nonstructural fusion-associated small transmembrane (FAST) proteins that induce cell-cell fusion and syncytium formation. It has been speculated that the FAST proteins may serve as virulence factors by promoting virus dissemination and increased or altered cytopathology. To directly test this hypothesis, the gene encoding the p14 FAST protein of reptilian reovirus was inserted into the genome of a heterologous virus that does not naturally form syncytia, vesicular stomatitis virus (VSV). Expression of the p14 FAST protein by the VSV/FAST recombinant gave the virus a highly fusogenic phenotype in cell culture. The growth of this recombinant fusogenic VSV strain was unaltered in vitro but was significantly enhanced in vivo. The VSV/FAST recombinant consistently generated higher titers of virus in the brains of BALB/c mice after intranasal or intravenous infection compared to the parental VSV/green fluorescent protein (GFP) strain that expresses GFP in place of p14. The VSV/FAST recombinant also resulted in an increased incidence of hind-limb paralysis, it infected a larger volume of brain tissue, and it induced more extensive neuropathology, thus leading to a lower maximum tolerable dose than that for the VSV/GFP parental virus. In contrast, an interferon-inducing mutant of VSV expressing p14 was still attenuated, indicating that this interferon-inducing phenotype is dominant to the fusogenic properties conveyed by the FAST protein. Based on this evidence, we conclude that the reovirus p14 FAST protein can function as a bona fide virulence factor.
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Lallas, G. C., N. Courtis, and M. Havredaki. "K562 Cell Sensitization to 5-Fluorouracil- or Interferon-Alpha-Induced Apoptosis Via Cordycepin (3′-Deoxyadenosine): Fine Control of Cell Apoptosis Via Poly(A) Polymerase Upregulation." International Journal of Biological Markers 19, no. 1 (January 2004): 58–66. http://dx.doi.org/10.1177/172460080401900108.
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K562 cells represent a classical model for the study of drug resistance. Induction of apoptosis is accompanied by concomitant distinct modulations of poly(A) polymerase (PAP) and other proteins involved in mRNA maturation. Recent data suggest the involvement of mRNA stability in the induction of specific apoptosis pathways. In this study we used a specific polyadenylation inhibitor, cordycepin (3-deoxyadenosine), to investigate the involvement of polyadenylation in K562 cell apoptosis and drug resistance. The combination of cordycepin with either 5-fluorouracil or interferon-alpha sensitized chemoresistant K562 cells to apoptosis. This sensitization was followed by distinct PAP modulations before and after the appearance of characteristic apoptosis pointers (DNA laddering, DAPI staining, mitochondrial transmembrane potential). PAP modulations appeared essential for K562 sensitization. mRNA polyadenylation therefore seemed to be involved not only in apoptosis but also in drug resistance. Polyadenylation inhibition by cordycepin under certain conditions sensitized chemoresistant K562 cells to apoptosis and thus polyadenylation could prove to be a fine target for overcoming drug resistance.
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Schandené, Liliane, Florence Roufosse, Aurore de Lavareille, Patrick Stordeur, André Efira, Bernard Kennès, Elie Cogan, and Michel Goldman. "Interferon α prevents spontaneous apoptosis of clonal Th2 cells associated with chronic hypereosinophilia." Blood 96, no. 13 (December 15, 2000): 4285–92. http://dx.doi.org/10.1182/blood.v96.13.4285.
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Abstract A recent study identified a clonal expansion of CD3−CD4+cells secreting Th2-type cytokines in 4 patients with chronic hypereosinophilia. Because interferon α (IFN-α) is used in the therapy of the idiopathic hypereosinophilic syndrome, the effects of this cytokine on the survival of clonal Th2 cells isolated from the blood of 2 patients were determined. First, these cells displayed a high rate of spontaneous apoptosis on culture in cytokine-free medium and were also sensitive to Fas-mediated apoptosis induced by soluble Fas ligand. Addition of IFN-α or interleukin-2 (IL-2) to culture medium resulted in significant protection against spontaneous but not Fas-induced apoptosis. Although spontaneous apoptosis of the clonal Th2 cells was clearly associated with down-regulation of both bcl-2 and bcl-xL levels, IFN-α had no significant effect on the expression of these antiapoptotic proteins, whereas addition of IL-2 resulted in higher levels of bcl-2. On the other hand, IFN-α decreased the numbers of cells with disrupted mitochondrial transmembrane potential both during spontaneous apoptosis and after exposure to protoporphyrin IX. Thus, IFN-α might promote the survival of clonal Th2 cells, an effect that could be relevant to the therapeutic approach for patients with chronic hypereosinophilia caused by clonal expansion of Th2-type cells.
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Schandené, Liliane, Florence Roufosse, Aurore de Lavareille, Patrick Stordeur, André Efira, Bernard Kennès, Elie Cogan, and Michel Goldman. "Interferon α prevents spontaneous apoptosis of clonal Th2 cells associated with chronic hypereosinophilia." Blood 96, no. 13 (December 15, 2000): 4285–92. http://dx.doi.org/10.1182/blood.v96.13.4285.h8004285_4285_4292.
Full textAbstract:
A recent study identified a clonal expansion of CD3−CD4+cells secreting Th2-type cytokines in 4 patients with chronic hypereosinophilia. Because interferon α (IFN-α) is used in the therapy of the idiopathic hypereosinophilic syndrome, the effects of this cytokine on the survival of clonal Th2 cells isolated from the blood of 2 patients were determined. First, these cells displayed a high rate of spontaneous apoptosis on culture in cytokine-free medium and were also sensitive to Fas-mediated apoptosis induced by soluble Fas ligand. Addition of IFN-α or interleukin-2 (IL-2) to culture medium resulted in significant protection against spontaneous but not Fas-induced apoptosis. Although spontaneous apoptosis of the clonal Th2 cells was clearly associated with down-regulation of both bcl-2 and bcl-xL levels, IFN-α had no significant effect on the expression of these antiapoptotic proteins, whereas addition of IL-2 resulted in higher levels of bcl-2. On the other hand, IFN-α decreased the numbers of cells with disrupted mitochondrial transmembrane potential both during spontaneous apoptosis and after exposure to protoporphyrin IX. Thus, IFN-α might promote the survival of clonal Th2 cells, an effect that could be relevant to the therapeutic approach for patients with chronic hypereosinophilia caused by clonal expansion of Th2-type cells.
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Li, Juan, Zhan Qi, Yuan-Ping Hu, and Yu-Xiang Wang. "Possible biomarkers for predicting lymph node metastasis of esophageal squamous cell carcinoma: a review." Journal of International Medical Research 47, no. 2 (January 7, 2019): 544–56. http://dx.doi.org/10.1177/0300060518819606.
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Esophageal cancer is the eighth most common form of cancer worldwide, and esophageal squamous cell carcinoma (ESCC) is a major type of esophageal cancer that arises from epithelial cells of the esophagus. Local lymph node metastasis (LNM) is a typical sign of failure for ESCC clinical treatments, and a link has been established between LNM and the aberrant expression of specific biomarkers. In this review, we summarize what is known about nine factors significantly associated with LNM in ESCC patients: phosphatase and tensin homolog (PTEN), mucin 1, vascular endothelial growth factor-C, tumor necrosis factor alpha-induced protein 8 (TNFAIP8), Raf-1 kinase inhibitory protein, stathmin (STMN1), metastasis-associated protein 1, caveolin-1, and interferon-induced transmembrane protein 3. The function of these nine proteins involves four major mechanisms: tumor cell proliferation, tumor cell migration and invasion, epithelium–mesenchymal transition, and chemosensitivity. The roles of PTEN, STMN1, and TNFAIP8 involve at least two of these mechanisms, and we suggest that they are possible biomarkers for predicting LNM in ESCC. However, further retrospective research into PTEN, STMN1, and TNFAIP8 is needed to test their possibilities as indicators.
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Kummer, Susann, Ori Avinoam, and Hans-Georg Kräusslich. "IFITM3 Clusters on Virus Containing Endosomes and Lysosomes Early in the Influenza A Infection of Human Airway Epithelial Cells." Viruses 11, no. 6 (June 12, 2019): 548. http://dx.doi.org/10.3390/v11060548.
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Interferon-induced transmembrane proteins (IFITMs) have been shown to strongly affect influenza A virus (IAV) infectivity in tissue culture. Moreover, polymorphisms in IFITM3 have been associated with the severity of the disease in humans. IFITM3 appears to act early in the infection, but its mechanism of action and potential interactions with incoming IAV structures are not yet defined. Here, we visualized endogenous IFITM3 interactions with IAV in the human lung epithelial cell line A549 and in primary human airway epithelial cells employing stimulated emission depletion super-resolution microscopy. By applying an iterative approach for the cluster definition and computational cluster analysis, we found that IFITM3 reorganizes into clusters as IAV infection progresses. IFITM3 cluster formation started at 2-3 h post infection and increased over time to finally coat IAV-containing endosomal vesicles. This IAV-induced phenotype was due to the endosomal recruitment of IFITM3 rather than to an overall increase in the IFITM3 abundance. While the IAV-induced IFITM3 clustering and localization to endosomal vesicles was comparable in primary human airway epithelial cells and the human lung epithelial cell line A549, the endogenous IFITM3 signal was higher in primary cells. Moreover, we observed IFITM3 signals adjacent to IAV-containing recycling endosomes.
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Winkler, Michael, Florian Wrensch, Pascale Bosch, Maike Knoth, Michael Schindler, Sabine Gärtner, and Stefan Pöhlmann. "Analysis of IFITM-IFITM Interactions by a Flow Cytometry-Based FRET Assay." International Journal of Molecular Sciences 20, no. 16 (August 8, 2019): 3859. http://dx.doi.org/10.3390/ijms20163859.
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The interferon-induced transmembrane proteins 1–3 (IFITM1–3) inhibit host cell entry of several viruses. However, it is incompletely understood how IFITM1–3 exert antiviral activity. Two phenylalanine residues, F75 and F78, within the intramembrane domain 1 (IM1) were previously shown to be required for IFITM3/IFITM3 interactions and for inhibition of viral entry, suggesting that IFITM/IFITM interactions might be pivotal to antiviral activity. Here, we employed a fluorescence resonance energy transfer (FRET) assay to analyze IFITM/IFITM interactions. For assay calibration, we equipped two cytosolic, non-interacting proteins, super yellow fluorescent protein (SYFP) and super cyan fluorescent protein (SCFP), with signals that target proteins to membrane rafts and also analyzed a SCFP-SYFP fusion protein. This strategy allowed us to discriminate background signals resulting from colocalization of proteins at membrane subdomains from signals elicited by protein–protein interactions. Coexpression of IFITM1–3 and IFITM5 fused to fluorescent proteins elicited strong FRET signals, and mutation of F75 and F78 in IFITM3 (mutant IFITM3-FF) abrogated antiviral activity, as expected, but did not alter cellular localization and FRET signals. Moreover, IFITM3-FF co-immunoprecipitated efficiently with wild type (wt) IFITM3, lending further support to the finding that lack of antiviral activity of IFITM3-FF was not due to altered membrane targeting or abrogated IFITM3-IFITM3 interactions. Collectively, we report an assay that allows quantifying IFITM/IFITM interactions. Moreover, we confirm residues F75 and F78 as critical for antiviral activity but also show that these residues are dispensable for IFITM3 membrane localization and IFITM3/IFITM3 interactions.
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Chen, Yi-Hao, Ching-Long Chen, Chang-Min Liang, Jy-Been Liang, Ming-Cheng Tai, Yun-Hsiang Chang, Da-Wen Lu, and Jiann-Torng Chen. "Silibinin Inhibits ICAM-1 Expression via Regulation of N-Linked and O-Linked Glycosylation in ARPE-19 Cells." BioMed Research International 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/701395.
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To evaluate the effects of silibinin on intercellular adhesion molecule-1 (ICAM-1) expression, we used ARPE-19 cells as a model in which tumor necrosis factor (TNF-α) and interferon (IFN-γ) enhanced ICAM-1 expression. This upregulation was inhibited by silibinin. In an adherence assay using ARPE-19 and THP-1 cells, silibinin inhibited the cell adhesion function of ICAM-1. The inhibitory effects of silibinin on ICAM-1 expression were mediated via the blockage of nuclear translocation of p65 proteins in TNF-αand phosphorylation of STAT1 in IFN-γ-stimulated cells. In addition, silibinin altered the degree of N-linked glycosylation posttranslationally in ARPE-19 cells by significantly enhancingMGAT3gene expression. Silibinin can increase the O-GlcNAc levels of glycoproteins in ARPE-19 cells. In a reporter gene assay, PUGNAc, which can also increase O-GlcNAc levels, inhibited NF-κB reporter activity in TNF-α-induced ARPE-19 cells and this process was augmented by silibinin treatment. Overexpression ofOGTgene was associated with reduced TNF-α-induced ICAM-1 levels, which is consistent with that induced by silibinin treatment. Taken together, silibinin inhibits ICAM-1 expression and its function through altered O-linked glycosylation in NF-κB and STAT1 signaling pathways and decreases the N-linked glycosylation of ICAM-1 transmembrane protein in proinflammatory cytokine-stimulated ARPE-19 cells.
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Röck, Jürgen, Jürgen Schmitz, and Gregor Winkels. "CD303 (BDCA-2) mediated inhibition of interferon type I production in plasmacytoid dendritic cells is linked to SYK, BLNK and PKC delta signaling (89.25)." Journal of Immunology 178, no. 1_Supplement (April 1, 2007): S153. http://dx.doi.org/10.4049/jimmunol.178.supp.89.25.
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Abstract CD303 is a calcium dependent type II lectin also known as Blood-Dendritic-Cell-Antigen-2 (BDCA-2) specifically expressed by human plasmacytoid dendritic cells (PDC). We have previously shown that monoclonal antibody (mAb) ligation of CD303 induces mAb endocytosis, calcium mobilization, protein tyrosine phosphorylation and inhibition of type I interferon (IFN I) production in stimulated PDC. Here we show that CD303 signaling and internalization in many aspects resembles B cell receptor (BCR) signaling and internalization. Instead of CD79a and CD79b, CD303 appears to use the Fc-receptor-common-gamma-chain as transmembrane adaptor protein. Like BCR signaling, CD303 triggering leads to SYK and BLNK phosphorylation. Signal transduction most likely involves activation of the phospholipase C-gamma 2, the phosphoinositide-3 kinase and the protein kinase C delta. Therefore, inhibition of IFN I production in stimulated PDC can be mimicked by PMA. Western blotting and peptide mass fingerprinting show that tyrosine phosphorylation occurs at cytoskeletal proteins (actin, alpha/beta-tubulin, profilin, alpha-actinin), proteasome activator subunit and the clathrin heavy chain, indicating clathrin-mediated endocytosis and vesicle trafficking. Finally, CD303 triggering inhibits TNF-alpha and CpG ODN-induced NF-kappa B activation in PDC.
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Benfield, Camilla TO, Farrell MacKenzie, Markus Ritzefeld, Michela Mazzon, Stuart Weston, Edward Tate, Boon Han Teo, et al. "Bat IFITM3 restriction depends on S-palmitoylation and a polymorphic site within the CD225 domain." Life Science Alliance 3, no. 1 (December 11, 2019): e201900542. http://dx.doi.org/10.26508/lsa.201900542.
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Host interferon-induced transmembrane proteins (IFITMs) are broad-spectrum antiviral restriction factors. Of these, IFITM3 potently inhibits viruses that enter cells through acidic endosomes, many of which are zoonotic and emerging viruses with bats (order Chiroptera) as their natural hosts. We previously demonstrated that microbat IFITM3 is antiviral. Here, we show that bat IFITMs are characterized by strong adaptive evolution and identify a highly variable and functionally important site—codon 70—within the conserved CD225 domain of IFITMs. Mutation of this residue in microbat IFITM3 impairs restriction of representatives of four different virus families that enter cells via endosomes. This mutant shows altered subcellular localization and reduced S-palmitoylation, a phenotype copied by mutation of conserved cysteine residues in microbat IFITM3. Furthermore, we show that microbat IFITM3 is S-palmitoylated on cysteine residues C71, C72, and C105, mutation of each cysteine individually impairs virus restriction, and a triple C71A-C72A-C105A mutant loses all restriction activity, concomitant with subcellular re-localization of microbat IFITM3 to Golgi-associated sites. Thus, we propose that S-palmitoylation is critical for Chiropteran IFITM3 function and identify a key molecular determinant of IFITM3 S-palmitoylation.
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Leung, Jason Y., Gorben P. Pijlman, Natasha Kondratieva, Jennifer Hyde, Jason M. Mackenzie, and Alexander A. Khromykh. "Role of Nonstructural Protein NS2A in Flavivirus Assembly." Journal of Virology 82, no. 10 (March 12, 2008): 4731–41. http://dx.doi.org/10.1128/jvi.00002-08.
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ABSTRACT Flavivirus nonstructural (NS) proteins are involved in RNA replication and modulation of the host antiviral response; however, evidence is mounting that some NS proteins also have essential roles in virus assembly. Kunjin virus (KUN) NS2A is a small, hydrophobic, transmembrane protein that is part of the replication complex and inhibits interferon induction. Previously, we have shown that an isoleucine (I)-to-asparagine (N) substitution at position 59 of the NS2A protein blocked the production of secreted virus particles in cells electroporated with viral RNA carrying this mutation. We now show that prolonged incubation of mutant KUN NS2A-I59N replicon RNA, in an inducible BHK-derived packaging cell line (expressing KUN structural proteins C, prM, and E), generated escape mutants that rescued the secretion of infectious virus-like particles. Sequencing identified three groups of revertants that included (i) reversions to wild-type, hydrophobic Ile, (ii) pseudorevertants to more hydrophobic residues (Ser, Thr, and Tyr) at codon 59, and (iii) pseudorevertants retaining Asn at NS2A codon 59 but containing a compensatory mutation (Thr-to-Pro) at NS2A codon 149. Engineering hydrophobic residues at NS2A position 59 or the compensatory T149P mutation into NS2A-I59N replicon RNA restored the assembly of secreted virus-like particles in packaging cells. T149P mutation also rescued virus production when introduced into the full-length KUN RNA containing an NS2A-I59N mutation. Immunofluorescence and electron microscopy analyses of NS2A-I59N replicon-expressing cells showed a distinct lack of virus-induced membranes normally present in cells expressing wild-type replicon RNA. The compensatory mutation NS2A-T149P restored the induction of membrane structures to a level similar to those observed during wild-type replication. The results further confirm the role of NS2A in virus assembly, demonstrate the importance of hydrophobic residues at codon 59 in this process, implicate the involvement of NS2A in the biogenesis of virus-induced membranes, and suggest a vital role for the virus-induced membranes in virus assembly.
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Li, Tongya, Zunlong Ke, Weiyong Liu, Ying Xiong, Ying Zhu, and Yingle Liu. "Human Hepatitis B Virus Core Protein Inhibits IFNα-Induced IFITM1 Expression by Interacting with BAF200." Viruses 11, no. 5 (May 9, 2019): 427. http://dx.doi.org/10.3390/v11050427.
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Human hepatitis B virus core protein (HBc) is a structural protein of the hepatitis B virus (HBV) and contributes to HBV regulation of host-cell transcription. However, the mechanisms of transcriptional regulation remain poorly characterized. To dissect the function of HBc, a yeast two-hybrid was performed to identify HBc-binding proteins, and the C-terminal of BRG1/hBRM-associated factors 200 (BAF200C) was identified. Then, the existence of HBc interactions with BAF200C and full-length BAF200 was confirmed via co-immunoprecipitation assays in 293T, HepG2 and HepG2-NTCP cells. Furthermore, we show that the binding between HBc and BAF200 was of vital importance to HBc mediated downregulation of interferon-induced transmembrane protein 1 (IFITM1) expression, and the mechanisms for the downregulation were disclosed as follows. Basal level of IFITM1 expression depends on BAF200, rather than the JAK–STAT1 pathway. The interaction of HBc with BAF200 disturbs the stability of the polybromo-associated BAF (PBAF) complex and results in the suppression of IFTM1 transcription. Finally, the antiviral effects of IFITM1 on cell proliferation and HBV replication were found to be partially restored when HBc was co-transfected with BAF200. Collectively, our findings indicate that HBc plays a role in HBV resistance against the antiviral activities of IFNα, providing details about HBV evasion of host innate immunity.
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Palatini, Massimo, Simon Franz Müller, Michael Kirstgen, Silke Leiting, Felix Lehmann, Lena Soppa, Nora Goldmann, et al. "IFITM3 Interacts with the HBV/HDV Receptor NTCP and Modulates Virus Entry and Infection." Viruses 14, no. 4 (March 30, 2022): 727. http://dx.doi.org/10.3390/v14040727.
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The Na+/taurocholate co-transporting polypeptide (NTCP, gene symbol SLC10A1) is both a physiological bile acid transporter and the high-affinity hepatic receptor for the hepatitis B and D viruses (HBV/HDV). Virus entry via endocytosis of the virus/NTCP complex involves co-factors, but this process is not fully understood. As part of the innate immunity, interferon-induced transmembrane proteins (IFITM) 1–3 have been characterized as virus entry-restricting factors for many viruses. The present study identified IFITM3 as a novel protein–protein interaction (PPI) partner of NTCP based on membrane yeast-two hybrid and co-immunoprecipitation experiments. Surprisingly, IFITM3 knockdown significantly reduced in vitro HBV infection rates of NTCP-expressing HuH7 cells and primary human hepatocytes (PHHs). In addition, HuH7-NTCP cells showed significantly lower HDV infection rates, whereas infection with influenza A virus was increased. HBV-derived myr-preS1 peptide binding to HuH7-NTCP cells was intact even under IFITM3 knockdown, suggesting that IFITM3-mediated HBV/HDV infection enhancement occurs in a step subsequent to the viral attachment to NTCP. In conclusion, IFITM3 was identified as a novel NTCP co-factor that significantly affects in vitro infection with HBV and HDV in NTCP-expressing hepatoma cells and PHHs. While there is clear evidence for a direct PPI between IFITM3 and NTCP, the specific mechanism by which this PPI facilitates the infection process remains to be identified in future studies.
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Huang, Kai, Monica L. Bailey, and Dwayne L. Barber. "Stress Erythropoiesis Elicits a Program of Gene Regulation That Overlaps with Interferon-γ." Blood 104, no. 11 (November 16, 2004): 2161. http://dx.doi.org/10.1182/blood.v104.11.2161.2161.
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Abstract Erythropoietin (EPO), the primary cytokine regulator of red blood cell production, acts through binding to its cognate receptor (EPO-R), which is primarily expressed on erythroid precursors. Knockout studies have illustrated a critical role for EPO, EPO-R and the downstream tyrosine kinase JAK2 in embryogenesis as mice lacking any of these components die from a fatal anemia at E13.5. These data suggest that EPO-R and/or JAK2 are required to promote erythropoiesis in vivo. EPO provides mitogenic, differentiative and cell survival signals to erythroid progenitors. We have performed microarray studies to identify target genes regulated by EPO in cell lines and primary cells. We utilized an erythroid cell line (HCD-57), a myeloid cell line stably expressing the EPO-R (Ba/F3-EPO-R), fetal liver cells isolated from E13.5 mice as well as splenocytes isolated from Phenylhydrazine (PHZ)-primed adult mice. Fetal liver cells permit the study of normal erythropoiesis in a fetal setting whereas the PHZ-primed erythroblasts permit analysis of stress erythropoiesis in adult mice. We harvested cells at 1, 8, 12 and 24 hr after EPO stimulation which correspond to immediate early gene induction (1 hr), S phase entry (8 hr) and G2/M (24 hr) time points. RNA was prepared and hybridized to the Affymetrix U74A mouse chip. Data was analyzed and only those genes with statistical significance (p < 0.05) were considered for further characterization. Analysis of the 1 hr time points has revealed that six genes are co-regulated by EPO in all four cellular environments. Included within this co-hort are the Suppressor of Cytokine Signaling genes (Cis, SOCS-1 and SOCS-3) and Myc, as well as two novel genes. We compared our datasets with other published analyses. The Williams laboratory has identified an Interferon-Stimulated Gene “ISG” data set corresponding to genes induced by Type I or Type II Interferon’s. We queried our PHZ-primed erythroblast data set against the Williams ISG database. Of the 305 human genes in the ISG database, 218 are expressed on the Affymetrix chip. We searched our dataset for genes that are induced 1.5-fold or greater at 2 of 4, 3 of 4 or 4 of 4 time points. Thirty-four genes are also stimulated by EPO in PHZ-primed erythroblasts including classical IFN-regulated genes such as Interferon-regulator factor-1 (IRF-1), Interferon-stimulated gene-15 (ISG-15), Interferon-induced transmembrane protein 3-like (IFITM-3l), Protein Kinase R (PKR) and Signal Transducer and Activator of Transcription-1 (STAT1). We have previously demonstrated that STAT1 is a negative regulator of murine erythropoiesis utilizing STAT1-deficient mice. We also analyzed immediate early gene regulation in fetal liver cells and PHZ-primed erythroblasts isolated from STAT1-deficient mice stimulated with EPO for 1 hr. These data were compared with the relevant wild type data sets. EPO stimulates the induction of the ubiquitin-like protein, ISG-15 in both wild type and STAT1−/− erythroblasts. Several signaling proteins have been shown to be covalently modified by ISG-15 including STAT1. ISG-15 is removed from ISGylated products by the deubiquitinating enzyme, Ubp43. EPO stimulates a rapid accumulation of Ubp43 in wild type cells, however, EPO fails to induce Ubp43 mRNA in STAT1-deficient fetal liver and PHZ-primed erythroblasts. Experiments are underway to confirm that the mechanism by which STAT1 exerts negative regulation of erythropoiesis is via upregulation of the deubiquitinating enzyme, Ubp43.
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Sun, Xiangjie, Hui Zeng, Amrita Kumar, Jessica A. Belser, Taronna R. Maines, and Terrence M. Tumpey. "Constitutively Expressed IFITM3 Protein in Human Endothelial Cells Poses an Early Infection Block to Human Influenza Viruses." Journal of Virology 90, no. 24 (October 5, 2016): 11157–67. http://dx.doi.org/10.1128/jvi.01254-16.
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ABSTRACTA role for pulmonary endothelial cells in the orchestration of cytokine production and leukocyte recruitment during influenza virus infection, leading to severe lung damage, has been recently identified. As the mechanistic pathway for this ability is not fully known, we extended previous studies on influenza virus tropism in cultured human pulmonary endothelial cells. We found that a subset of avian influenza viruses, including potentially pandemic H5N1, H7N9, and H9N2 viruses, could infect human pulmonary endothelial cells (HULEC) with high efficiency compared to human H1N1 or H3N2 viruses. In HULEC, human influenza viruses were capable of binding to host cellular receptors, becoming internalized and initiating hemifusion but failing to uncoat the viral nucleocapsid and to replicate in host nuclei. Unlike numerous cell types, including epithelial cells, we found that pulmonary endothelial cells constitutively express a high level of the restriction protein IFITM3 in endosomal compartments. IFITM3 knockdown by small interfering RNA (siRNA) could partially rescue H1N1 virus infection in HULEC, suggesting IFITM3 proteins were involved in blocking human influenza virus infection in endothelial cells. In contrast, selected avian influenza viruses were able to escape IFITM3 restriction in endothelial cells, possibly by fusing in early endosomes at higher pH or by other, unknown mechanisms. Collectively, our study demonstrates that the human pulmonary endothelium possesses intrinsic immunity to human influenza viruses, in part due to the constitutive expression of IFITM3 proteins. Notably, certain avian influenza viruses have evolved to escape this restriction, possibly contributing to virus-induced pneumonia and severe lung disease in humans.IMPORTANCEAvian influenza viruses, including H5N1 and H7N9, have been associated with severe respiratory disease and fatal outcomes in humans. Although acute respiratory distress syndrome (ARDS) and progressive pulmonary endothelial damage are known to be present during severe human infections, the role of pulmonary endothelial cells in the pathogenesis of avian influenza virus infections is largely unknown. By comparing human seasonal influenza strains to avian influenza viruses, we provide greater insight into the interaction of influenza virus with human pulmonary endothelial cells. We show that human influenza virus infection is blocked during the early stages of virus entry, which is likely due to the relatively high expression of the host antiviral factors IFITMs (interferon-induced transmembrane proteins) located in membrane-bound compartments inside cells. Overall, this study provides a mechanism by which human endothelial cells limit replication of human influenza virus strains, whereas avian influenza viruses overcome these restriction factors in this cell type.
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Pichurin, Pavel N., Gregorio D. Chazenbalk, Holly Aliesky, Oxana Pichurina, Basil Rapoport, and Sandra M. McLachlan. "“Hijacking” the Thyrotropin Receptor: A Chimeric Receptor-Lysosome Associated Membrane Protein Enhances Deoxyribonucleic Acid Vaccination and Induces Graves’ Hyperthyroidism." Endocrinology 145, no. 12 (December 1, 2004): 5504–14. http://dx.doi.org/10.1210/en.2004-0530.
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Abstract Naked DNA vaccination with the TSH receptor (TSHR) does not, in most studies, induce TSHR antibodies and never induces hyperthyroidism in BALB/c mice. Proteins expressed endogenously by vaccination are preferentially presented by major histocompatibility complex class I, but optimal T cell help for antibody production requires lysosomal processing and major histocompatibility complex class II presentation. To divert protein expression to lysosomes, we constructed a plasmid with the TSHR ectodomain spliced between the signal peptide and transmembrane-intracellular region of lysosome-associated membrane protein (LAMP)-1, a lysosome-associated membrane protein. BALB/c mice pretreated with cardiotoxin were primed intramuscularly using this LAMP-TSHR chimera and boosted twice with DNA encoding wild-type TSHR, TSHR A-subunit, or LAMP-TSHR. With each protocol, spleen cells responded to TSHR antigen by secreting interferon-γ, and 60% or more mice had TSHR antibodies detectable by ELISA. TSH binding inhibitory activity was present in seven, four, and two of 10 mice boosted with TSHR A-subunit, LAMP-TSHR, or wild-type TSHR, respectively. Importantly, six of 30 mice had elevated T4 levels and goiter (5 of 6 with detectable thyroid-stimulating antibodies). Injecting LAMP-TSHR intradermally without cardiotoxin pretreatment induced TSHR antibodies detectable by ELISA but not by TSH binding inhibitory activity, and none became hyperthyroid. These findings are consistent with a role for cardiotoxin-recruited macrophages in which (unlike in fibroblasts) LAMP-TSHR can be expressed intracellularly and on the cell surface. In conclusion, hijacking the TSHR to lysosomes enhances T cell responses and TSHR antibody generation and induces Graves’-like hyperthyroidism in BALB/c mice by intramuscular naked DNA vaccination.
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Sneha, Patil, Urmi Shah, and Seetharaman Balaji. "In Silico Insights into HIV-1 Vpu-Tetherin Interactions and Its Mutational Counterparts." Medical Sciences 7, no. 6 (June 22, 2019): 74. http://dx.doi.org/10.3390/medsci7060074.
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Tetherin, an interferon-induced host protein encoded by the bone marrow stromal antigen 2 (BST2/CD317/HM1.24) gene, is involved in obstructing the release of many retroviruses and other enveloped viruses by cross-linking the budding virus particles to the cell surface. This activity is antagonized in the case of human immunodeficiency virus (HIV)-1 wherein its accessory protein Viral Protein U (Vpu) interacts with tetherin, causing its downregulation from the cell surface. Vpu and tetherin connect through their transmembrane (TM) domains, culminating into events leading to tetherin degradation by recruitment of β-TrCP2. However, mutations in the TM domains of both proteins are reported to act as a resistance mechanism to Vpu countermeasure impacting tetherin’s sensitivity towards Vpu but retaining its antiviral activity. Our study illustrates the binding aspects of blood-derived, brain-derived, and consensus HIV-1 Vpu with tetherin through protein–protein docking. The analysis of the bound complexes confirms the blood-derived Vpu–tetherin complex to have the best binding affinity as compared to other two. The mutations in tetherin and Vpu are devised computationally and are subjected to protein–protein interactions. The complexes are tested for their binding affinities, residue connections, hydrophobic forces, and, finally, the effect of mutation on their interactions. The single point mutations in tetherin at positions L23Y, L24T, and P40T, and triple mutations at {L22S, F44Y, L37I} and {L23T, L37T, T45I}, while single point mutations in Vpu at positions A19H and W23Y and triplet of mutations at {V10K, A11L, A19T}, {V14T, I18T, I26S}, and {A11T, V14L, A15T} have revealed no polar contacts with minimal hydrophobic interactions between Vpu and tetherin, resulting in reduced binding affinity. Additionally, we have explored the aggregation potential of tetherin and its association with the brain-derived Vpu protein. This work is a possible step toward an understanding of Vpu–tetherin interactions.
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Huang, Wei-Wei, Eduardo A. Garcia-Zepeda, Alain Sauty, Hans C. Oettgen, Marc E. Rothenberg, and Andrew D. Luster. "Molecular and Biological Characterization of the Murine Leukotriene B4 Receptor Expressed on Eosinophils." Journal of Experimental Medicine 188, no. 6 (September 21, 1998): 1063–74. http://dx.doi.org/10.1084/jem.188.6.1063.
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The movement of leukocytes into tissues is regulated by the local production of chemical mediators collectively referred to as chemoattractants. Although chemoattractants constitute a diverse array of molecules, including proteins, peptides, and lipids, they all appear to signal leukocytes through a related family of seven transmembrane–spanning G protein–coupled receptors. The eosinophil is a potent proinflammatory cell that is attracted into tissues during allergic inflammation, parasitic infection, and certain malignancies. Since the molecular mechanisms controlling eosinophil recruitment are incompletely understood, we performed a degenerate polymerase chain reaction on cDNA isolated from murine eosinophils to identify novel chemoattractant receptors. We report the isolation of a cDNA that encodes a 351–amino acid glycoprotein that is 78% identical to a human gene that has been reported to be a purinoceptor (P2Y7) and a leukotriene B4 (LTB4) receptor (BLTR). Chinese hamster ovary (CHO) cells transfected with this cDNA specifically bound [3H]LTB4 with a dissociation constant of 0.6 ± 0.1 nM. Furthermore, LTB4 induced a dose-dependent intracellular calcium flux in transfected CHO cells. In contrast, [35S]dATP did not specifically bind to these transfectants. This mRNA was expressed at high levels in interleukin 5–exposed eosinophils, elicited peritoneal macrophages and neutrophils, and to a lesser extent interferon γ stimulated macrophages. Low levels of expression were detected in the lung, lymph node, and spleen of unchallenged mice. Western blot analysis detected the mBLTR protein in murine eosinophils and alveolar macrophages as well as human eosinophils. In addition, elevated levels of mBLTR mRNA were found in the lungs of mice in a murine model of allergic pulmonary inflammation in a time course consistent with the influx of eosinophils. Our findings indicate that this murine receptor is an LTB4 receptor that is highly expressed on activated leukocytes, including eosinophils, and may play an important role in mediating eosinophil recruitment into inflammatory foci.
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Lee, Jaewoong, Mark E. Robinson, Ning Ma, Teresa Sadras, Kadriye Nehir Cosgun, Lai N. Chan, Kohei Kume, et al. "Identification of a Conserved Intracellular Loop (CIL) Structure That Scaffolds PIP3 to Amplify Oncogenic Signaling during Malignant B-Cell Transformation." Blood 138, Supplement 1 (November 5, 2021): 868. http://dx.doi.org/10.1182/blood-2021-149646.
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Abstract Background: Within seconds of antigen-encounter, B-cell receptor (BCR) signaling induces dramatic changes of cell membrane lipid composition, including >40-fold increases of local PIP3-concentrations within lipid rafts. While several structural elements, including pleckstrin homology (PH) domains have been identified as PIP3-binding proteins, the underlying mechanisms that amplify BCR-signaling to assemble large signaling complexes within lipid rafts within 15 to 30 seconds, remained elusive. To understand the mechanistic and biophysical requirements for PIP3 accumulation during normal B-cell activation and acute oncogenic transformation, we identified PIP3-interacting proteins by cell-surface proteomic analyses. Results: In addition to proteins known to bind PIP3 with their PH-domains, we identified the short 133 aa protein IFITM3 (interferon-inducible transmembrane protein 3) as a top-ranking PIP3 scaffold. This was unexpected because IFITM3 was previously identified as endosomal protein that blocks viral infection by stiffening endosomal membranes to firmly contain viral cargo. Previous studies revealed that polymorphisms that lead to the expression of truncated IFITM3 are associated with increased susceptibility to viral infections, including SARS-CoV2. Among known cell membrane lipids, PIP3 has the highest negative charge. Instead of a PH-domain, IFITM3 laterally sequestered PIP3 through electrostatic interactions with two basic lysine residues (K83 and K104) located at the membrane-solution interface. Together with three other basic lysine and arginine residues K83 and K104 form a conserved intracellular loop (CIL), which enable IFITM3 to efficiently capture two PIP3 molecules. Bivalent PIP3-binding of the IFITM3-CIL enables a crosslinking mechanism that results in dramatic amplification of B-cell activation signals and clustering of large signaling complexes within lipid rafts. In normal resting B-cells, Ifitm3 was minimally expressed and mainly localized in endosomes. However, B-cell activation and oncogenic kinases induced phosphorylation at IFITM3-Y20, resulting in translocation of IFITM3 from endosomes and massive accumulation at the cell surface. Ifitm3ˉ /ˉ naïve B-cells developed at normal numbers, however, activation by antigen encounter was compromised. In Ifitm3ˉ /ˉ B-cells, lipid rafts were depleted of PIP3, resulting in defective expression of >60 lipid raft-associated surface receptors and impaired PI3K-signaling. Ifitm3ˉ /ˉ B-cells were unable to undergo affinity maturation and di not contribute to germinal center formation upon immunization. Analyses of gene expression and clinical outcome data from patients in six clinical cohorts for pediatric and adult B-ALL, mantle cell lymphoma, CLL and DLBCL, we consistently identified IFITM3 as a top-ranking predictor of poor clinical outcome. Inducible activation of BCR-ABL1 and NRAS G12D rapidly induced development of B-ALL but failed to transform and initiate B-ALL from Ifitm3ˉ /ˉ B-cell precursors. Conversely, the phospho-mimetic IFITM3-Y20E mutation, mimicking phosphorylation of the IFITM3 N-terminus at Y20 induced constitutive membrane localization of IFITM3, spontaneous aggregation of large oncogenic signaling complexes and readily initiated transformation in a genetic model of pre-malignant B-cells. Conclusions: We conclude that phosphorylation of IFITM3 upon B-cell activation induces a dynamic switch from antiviral effector functions in endosomes to oncogenic signal-amplification at the cell-surface. IFITM3-dependent amplification of PI3K-signaling is critical to enable rapid expansion of activated B-cells. In addition, multiple oncogenes depend on IFITM3 to assemble PIP3-dependent signaling complexes and amplify PI3K-signaling for malignant transformation and initiation of B-lymphoid leukemia and lymphoma. Figure 1 Figure 1. Disclosures Weinstock: SecuraBio: Consultancy; ASELL: Consultancy; Bantam: Consultancy; Abcuro: Research Funding; Verastem: Research Funding; Daiichi Sankyo: Consultancy, Research Funding; AstraZeneca: Consultancy; Travera: Other: Founder/Equity; Ajax: Other: Founder/Equity.