scholarly journals Human Metapneumovirus Induces IRF1 via TANK-Binding Kinase 1 and Type I IFN

2021 ◽  
Vol 12 ◽  
Author(s):  
Simon Loevenich ◽  
Alix S. Spahn ◽  
Kristin Rian ◽  
Victor Boyartchuk ◽  
Marit Walbye Anthonsen
Keyword(s):  
Fungal Pathogens ◽  
Molecular Mechanisms ◽  
Viral Infections ◽  
Human Monocyte ◽  
Cell Types ◽  
Human Metapneumovirus ◽  
Type I ◽  
Protein Levels ◽  
Antiviral Responses ◽  
Mucosal Surfaces

The innate immune and host-protective responses to viruses, such as the airway pathogen human metapneumovirus (HMPV), depend on interferons (IFNs) that is induced through TANK-binding kinase 1 (TBK1) and IFN regulatory factors (IRFs). The transcription factor IRF1 is important for host resistance against several viruses and has a key role in induction of IFN-λ at mucosal surfaces. In most cell types IRF1 is expressed at very low levels, but its mRNA is rapidly induced when the demand for IRF1 activity arises. Despite general recognition of the importance of IRF1 to antiviral responses, the molecular mechanisms by which IRF1 is regulated during viral infections are not well understood. Here we identify the serine/threonine kinase TBK1 and IFN-β as critical regulators of IRF1 mRNA and protein levels in human monocyte-derived macrophages. We find that inhibition of TBK1 activity either by the semi-selective TBK1/IKKε inhibitor BX795 or by siRNA-mediated knockdown abrogates HMPV-induced expression of IRF1. Moreover, we show that canonical NF-κB signaling is involved in IRF1 induction and that the TBK1/IKKε inhibitor BX795, but not siTBK1 treatment, impairs HMPV-induced phosphorylation of the NF-κB subunit p65. At later time-points of the infection, IRF1 expression depended heavily on IFN-β-mediated signaling via the IFNAR-STAT1 pathway. Hence, our results suggest that TBK1 activation and TBK1/IKKε-mediated phosphorylation of the NF-κB subunit p65 control transcription of IRF1. Our study identifies a novel mechanism for IRF1 induction in response to viral infection of human macrophages that could be relevant not only to defense against HMPV, but also to other viral, bacterial and fungal pathogens.

scholarly journals An alternative model for type I interferon induction downstream of human TLR2

2020 ◽  
Vol 295 (42) ◽  
pp. 14325-14342
Author(s):  
Timo Oosenbrug ◽  
Michel J. van de Graaff ◽  
Mariëlle C. Haks ◽  
Sander van Kasteren ◽  
Maaike E. Ressing
Keyword(s):  
Molecular Mechanisms ◽  
Human Monocyte ◽  
Cell Types ◽  
Type I Interferons ◽  
Type I ◽  
Downstream Signaling ◽  
Interferon Stimulated Genes ◽  
Cytokines And Chemokines ◽  
A Cell ◽  
Extracellular Environment

Surface-exposed Toll-like receptors (TLRs) such as TLR2 and TLR4 survey the extracellular environment for pathogens. TLR activation initiates the production of various cytokines and chemokines, including type I interferons (IFN-I). Downstream of TLR4, IFNβ secretion is only vigorously triggered in macrophages when the receptor undergoes endocytosis and switches signaling adaptor; surface TLR4 engagement predominantly induces proinflammatory cytokines via the signaling adaptor MyD88. It is unclear whether this dichotomy is generally applicable to other TLRs, cell types, or differentiation states. Here, we report that diverse TLR2 ligands induce an IFN-I response in human monocyte-like cells, but not in differentiated macrophages. This TLR2-dependent IFN-I signaling originates from the cell surface and depends on MyD88; it involves combined activation of the transcription factors IRF3 and NF-κB, driven by the kinases TBK1 and TAK1-IKKβ, respectively. TLR2-stimulated monocytes produced modest IFNβ levels that caused productive downstream signaling, reflected by STAT1 phosphorylation and expression of numerous interferon-stimulated genes. Our findings reveal that the outcome of TLR2 signaling includes an IFN-I response in human monocytes, which is lost upon macrophage differentiation, and differs mechanistically from IFN-I-induction through TLR4. These findings point to molecular mechanisms tailored to the differentiation state of a cell and the nature of receptors activated to control and limit TLR-triggered IFN-I responses.

scholarly journals Identification of Feline Interferon Regulatory Factor 1 as an Efficient Antiviral Factor against the Replication of Feline Calicivirus and Other Feline Viruses

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Yongxiang Liu ◽  
Xiaoxiao Liu ◽  
Hongtao Kang ◽  
Xiaoliang Hu ◽  
Jiasen Liu ◽  
...  
Keyword(s):  
Antiviral Activity ◽  
Viral Infections ◽  
Interferon Regulatory Factor ◽  
Feline Calicivirus ◽  
Type I ◽  
Norwalk Virus ◽  
Regulatory Factor ◽  
Feline Panleukopenia Virus ◽  
Protein Levels ◽  
Interferon Regulatory Factor 1

Interferons (IFNs) can inhibit most, if not all, viral infections by eliciting the transcription of hundreds of interferon-stimulated genes (ISGs). Feline calicivirus (FCV) is a highly contagious pathogen of cats and a surrogate for Norwalk virus. Interferon efficiently inhibits the replication of FCV, but the mechanism of the antiviral activity is poorly understood. Here, we evaluated the anti-FCV activity of ten ISGs, whose antiviral activities were previously reported. The results showed that interferon regulatory factor 1 (IRF1) can significantly inhibit the replication of FCV, whereas the other ISGs tested in this study failed. Further, we found that IRF1 was localized in the nucleus and efficiently activated IFN-β and the ISRE promoter. IRF1 can trigger the production of endogenous interferon and the expression of ISGs, suggesting that IRF1 can positively regulate IFN signalling. Importantly, the mRNA and protein levels of IRF1 were reduced upon FCV infection, which may be a new strategy for FCV to evade the innate immune system. Finally, the antiviral activity of IRF1 against feline panleukopenia virus, feline herpesvirus, and feline infectious peritonitis virus was demonstrated. These data indicate that feline IRF1 plays an important role in regulating the host type I IFN response and inhibiting feline viral infections.

scholarly journals Differential cell autonomous responses determine the outcome of coxsackievirus infections in murine pancreatic α and β cells

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Laura Marroqui ◽  
Miguel Lopes ◽  
Reinaldo S dos Santos ◽  
Fabio A Grieco ◽  
Merja Roivainen ◽  
...  
Keyword(s):  
Gene Networks ◽  
Viral Infections ◽  
Islet Cells ◽  
Global Gene Expression ◽  
Cell Types ◽  
Autoimmune Response ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Antiviral Responses ◽  
Different Cell Types

Type 1 diabetes (T1D) is an autoimmune disease caused by loss of pancreatic β cells via apoptosis while neighboring α cells are preserved. Viral infections by coxsackieviruses (CVB) may contribute to trigger autoimmunity in T1D. Cellular permissiveness to viral infection is modulated by innate antiviral responses, which vary among different cell types. We presently describe that global gene expression is similar in cytokine-treated and virus-infected human islet cells, with up-regulation of gene networks involved in cell autonomous immune responses. Comparison between the responses of rat pancreatic α and β cells to infection by CVB5 and 4 indicate that α cells trigger a more efficient antiviral response than β cells, including higher basal and induced expression of STAT1-regulated genes, and are thus better able to clear viral infections than β cells. These differences may explain why pancreatic β cells, but not α cells, are targeted by an autoimmune response during T1D.

scholarly journals A role for IRF3-dependent RXRα repression in hepatotoxicity associated with viral infections

2006 ◽  
Vol 203 (12) ◽  
pp. 2589-2602 ◽  
Author(s):  
Edward K. Chow ◽  
Antonio Castrillo ◽  
Arash Shahangian ◽  
Liming Pei ◽  
Ryan M. O'Connell ◽  
...  
Keyword(s):  
Viral Infection ◽  
Target Genes ◽  
Metabolic Diseases ◽  
Viral Infections ◽  
Type I ◽  
Reye's Syndrome ◽  
Downstream Target ◽  
Antiviral Responses ◽  
Host Metabolism

Viral infections and antiviral responses have been linked to several metabolic diseases, including Reye's syndrome, which is aspirin-induced hepatotoxicity in the context of a viral infection. We identify an interferon regulatory factor 3 (IRF3)–dependent but type I interferon–independent pathway that strongly inhibits the expression of retinoid X receptor α (RXRα) and suppresses the induction of its downstream target genes, including those involved in hepatic detoxification. Activation of IRF3 by viral infection in vivo greatly enhances bile acid– and aspirin-induced hepatotoxicity. Our results provide a critical link between the innate immune response and host metabolism, identifying IRF3-mediated down-regulation of RXRα as a molecular mechanism for pathogen-associated metabolic diseases.

scholarly journals How fragile we are. Influence of STimulator of INterferon Genes, STING, variants on pathogen recognition and immune response efficiency

2021 ◽  
Author(s):  
Jeremy Morere ◽  
Cecilia Hognon ◽  
Tom Miclot ◽  
Tao Jiang ◽  
Elise Dumont ◽  
...  
Keyword(s):  
Immune Response ◽  
Molecular Mechanisms ◽  
Viral Infections ◽  
Inflammatory Diseases ◽  
Dynamical Behavior ◽  
Structural Features ◽  
Type I Interferons ◽  
Machine Learning Techniques ◽  
Type I ◽  
Interaction Patterns

The STimulator of INterferon Genes (STING) protein is a cornerstone of the human immune response. Its activation by cGAMP upon the presence of cytosolic DNA stimulates the production of type I interferons and inflammatory cytokines which are crucial for protecting cells from infections. STING signaling pathway can also influence both tumor-suppressive and tumor-promoting mechanisms, rendering it an appealing target for drug design. In the human population, several STING variants exist and exhibit dramatic differences in their activity, impacting the efficiency of the host defense against infections. Understanding the differential molecular mechanisms exhibited by these variants is of utmost importance notably towards personalized medicine treatments against diseases such as viral infections (COVID-19, Dengue...), cancers, or auto-inflammatory diseases. Owing to micro-seconds scale molecular modeling simulations and post-processing by contacts analysis and Machine Learning techniques, we reveal the dynamical behavior of four STING variants (wild type, G230A, R293Q, and G230A-R293Q) and we rationalize the variability of efficiency observed experimentally. Our results show that the decrease of STING activity is linked to a stiffening of key-structural features of the binding cavity, together with changes of the interaction patterns within the protein.

scholarly journals Primary cilia and the reciprocal activation of AKT and SMAD2/3 regulate stretch-induced autophagy in trabecular meshwork cells

2021 ◽  
Vol 118 (13) ◽  
pp. e2021942118
Author(s):  
Myoung Sup Shim ◽  
April Nettesheim ◽  
Angela Dixon ◽  
Paloma B. Liton
Keyword(s):  
Trabecular Meshwork ◽  
Primary Cilia ◽  
Molecular Mechanisms ◽  
Ex Vivo ◽  
Mechanical Stretch ◽  
Cell Types ◽  
Elevated Pressure ◽  
Compensatory Response ◽  
Protein Levels ◽  
Trabecular Meshwork Cells

Activation of autophagy is one of the responses elicited by high intraocular pressure (IOP) and mechanical stretch in trabecular meshwork (TM) cells. However, the mechanosensor and the molecular mechanisms by which autophagy is induced by mechanical stretch in these or other cell types is largely unknown. Here, we have investigated the mechanosensor and downstream signaling pathway that regulate cyclic mechanical stretch (CMS)-induced autophagy in TM cells. We report that primary cilia act as a mechanosensor for CMS-induced autophagy and identified a cross-regulatory talk between AKT1 and noncanonical SMAD2/3 signaling as critical components of primary cilia-mediated activation of autophagy by mechanical stretch. Furthermore, we demonstrated the physiological significance of our findings in ex vivo perfused eyes. Removal of primary cilia disrupted the homeostatic IOP compensatory response and prevented the increase in LC3-II protein levels in response to elevated pressure challenge, strongly supporting a role of primary cilia-mediated autophagy in regulating IOP homeostasis.

scholarly journals PI3K is critical for the nuclear translocation of IRF-7 and type I IFN production by human plasmacytoid predendritic cells in response to TLR activation

2008 ◽  
Vol 205 (2) ◽  
pp. 315-322 ◽  
Author(s):  
Cristiana Guiducci ◽  
Cristina Ghirelli ◽  
Marie-Annick Marloie-Provost ◽  
Tracy Matray ◽  
Robert L. Coffman ◽  
...  
Keyword(s):  
Nuclear Translocation ◽  
Cell Types ◽  
Nuclear Factor Κb ◽  
Type I ◽  
Endosomal Trafficking ◽  
Type I Ifn ◽  
Protein Levels ◽  
Proinflammatory Responses ◽  
Novel Target ◽  
Factor Α

Plasmacytoid predendritic cells (pDCs) are the main producers of type I interferon (IFN) in response to Toll-like receptor (TLR) stimulation. Phosphatidylinositol-3 kinase (PI3K) has been shown to be activated by TLR triggering in multiple cell types; however, its role in pDC function is not known. We show that PI3K is activated by TLR stimulation in primary human pDCs and demonstrate, using specific inhibitors, that PI3K is required for type I IFN production by pDCs, both at the transcriptional and protein levels. Importantly, PI3K was not involved in other proinflammatory responses of pDCs, including tumor necrosis factor α and interleukin 6 production and DC differentiation. pDCs preferentially expressed the PI3K δ subunit, which was specifically involved in the control of type I IFN production. Although uptake and endosomal trafficking of TLR ligands were not affected in the presence of PI3K inhibitors, there was a dramatic defect in the nuclear translocation of IFN regulatory factor (IRF) 7, whereas nuclear factor κB activation was preserved. Thus, PI3K selectively controls type I IFN production by regulating IRF-7 nuclear translocation in human pDCs and could serve as a novel target to inhibit pathogenic type I IFN in autoimmune diseases.

scholarly journals Human Type I Interferon Antiviral Effects in Respiratory and Reemerging Viral Infections

2020 ◽  
Vol 2020 ◽  
pp. 1-27 ◽  
Author(s):  
Patricio L. Acosta ◽  
Alana B. Byrne ◽  
Diego R. Hijano ◽  
Laura B. Talarico
Keyword(s):  
Immune System ◽  
Host Defense ◽  
Immune Modulation ◽  
Molecular Mechanisms ◽  
Viral Infections ◽  
Current Knowledge ◽  
Type I Interferons ◽  
Type I ◽  
Antiviral Effects ◽  
Wide Range

Type I interferons (IFN-I) are a group of related proteins that help regulate the activity of the immune system and play a key role in host defense against viral infections. Upon infection, the IFN-I are rapidly secreted and induce a wide range of effects that not only act upon innate immune cells but also modulate the adaptive immune system. While IFN-I and many IFN stimulated genes are well-known for their protective antiviral role, recent studies have associated them with potential pathogenic functions. In this review, we summarize the current knowledge regarding the complex effects of human IFN-I responses in respiratory as well as reemerging flavivirus infections of public health significance and the molecular mechanisms by which viral proteins antagonize the establishment of an antiviral host defense. Antiviral effects and immune modulation of IFN-stimulated genes is discussed in resisting and controlling pathogens. Understanding the mechanisms of these processes will be crucial in determining how viral replication can be effectively controlled and in developing safe and effective vaccines and novel therapeutic strategies.

scholarly journals Telomere associated gene expression as well as TERT protein level and telomerase activity are altered in the ovarian follicles of aged mice

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Esra Gozde Kosebent ◽  
Saffet Ozturk
Keyword(s):  
Gene Expression ◽  
Molecular Mechanisms ◽  
Structural Integrity ◽  
Cell Types ◽  
Telomerase Activity ◽  
Ovarian Follicles ◽  
Biological Aging ◽  
Aged Mice ◽  
Protein Levels ◽  
Ovarian Aging

AbstractTelomeres cap the ends of eukaryotic chromosomes to maintain genomic stability and integrity during an organism’s lifespan. The length of telomeres inevitably shortens due to DNA replication, genotoxic agents, and biological aging. A limited number of cell types, e.g., stem cells, germline cells, and early embryos can elongate shortened telomeres via the enzymatic action of telomerase, which is composed of telomerase reverse transcriptase (TERT) and telomerase RNA component (Terc). Additionally, telomere-associated proteins including telomeric repeat binding factor 1 (TRF1) and 2 (TRF2), as well as protection of telomeres 1a (POT1a), bind to telomeres to maintain their structural integrity and length. During ovarian aging in mammals, telomeres progressively shorten, accompanied by fertility loss; however, the molecular mechanism underlying this attrition during follicle development remains unclear. In this study, the primary, secondary, preantral, and antral follicles were obtained either from 6-week-old adult (n = 19) or 52-week-old aged (n = 12) mice. We revealed that the Tert, Terc, Trf1, Trf2, and Pot1a gene expression (P < 0.001) and TERT protein (P < 0.01) levels significantly decreased in certain ovarian follicles of the aged group when compared to those of the adult group. Also, telomerase activity exhibited remarkable changes in the follicles of both groups. Consequently, altered telomere-associated gene expression and reduced TERT protein levels in the follicles of aged mice may be a determinant of telomere shortening during ovarian aging, and infertility appearing in the later decades of reproductive lifespan. Further investigations are required to determine the molecular mechanisms underlying these alterations in the follicles during ovarian aging.

scholarly journals When human guanylate-binding proteins meet viral infections

2021 ◽  
Vol 28 (1) ◽  
Author(s):  
Rongzhao Zhang ◽  
Zhixin Li ◽  
Yan-Dong Tang ◽  
Chenhe Su ◽  
Chunfu Zheng
Keyword(s):  
Innate Immunity ◽  
Viral Infection ◽  
Binding Proteins ◽  
Molecular Mechanisms ◽  
Viral Infections ◽  
Innate Immune ◽  
Type I Interferons ◽  
Type I ◽  
Downstream Signaling ◽  
Antiviral Innate Immunity

AbstractInnate immunity is the first line of host defense against viral infection. After invading into the cells, pathogen-associated-molecular-patterns derived from viruses are recognized by pattern recognition receptors to activate the downstream signaling pathways to induce the production of type I interferons (IFN-I) and inflammatory cytokines, which play critical functions in the host antiviral innate immune responses. Guanylate-binding proteins (GBPs) are IFN-inducible antiviral effectors belonging to the guanosine triphosphatases family. In addition to exerting direct antiviral functions against certain viruses, a few GBPs also exhibit regulatory roles on the host antiviral innate immunity. However, our understanding of the underlying molecular mechanisms of GBPs' roles in viral infection and host antiviral innate immune signaling is still very limited. Therefore, here we present an updated overview of the functions of GBPs during viral infection and in antiviral innate immunity, and highlight discrepancies in reported findings and current challenges for future studies, which will advance our understanding of the functions of GBPs and provide a scientific and theoretical basis for the regulation of antiviral innate immunity.

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