scholarly journals DDI2 protease activity controls embryonic development and inflammation via TCF11/NRF1

2020 ◽  
Author(s):  
Monika Siva ◽  
Stefanie Haberecht-Müller ◽  
Michaela Prochazkova ◽  
Jan Prochazka ◽  
Frantisek Sedlak ◽  
...  
Keyword(s):  
Stress Responses ◽  
Mammalian Cells ◽  
Type I ◽  
Interferon Signature ◽  
Knock Out ◽  
Unfolded Protein ◽  
Proteotoxic Stress ◽  
Proteasome Subunits

DDI2 is an aspartic protease that cleaves polyubiquitinated substrates. Upon proteotoxic stress, DDI2 activates the ER-bound transcription factor TCF11/NRF1 (NFE2L1), a master regulator of proteostasis maintenance in mammalian cells, and ensures the expression of rescue factors including proteasome subunits. Here we describe the consequences of DDI2 ablation both in vivo and in cells. Knock-out of DDI2 in mice resulted in embryonic lethality at E12.5 with severe developmental failure. Molecular characterization of the embryos and surrogate DDI2 knock-out cell lines showed insufficient proteasome expression with proteotoxic stress, accumulation of high molecular weight ubiquitin conjugates, and induction of the unfolded protein and integrated stress responses. We also show that DDI2 KO-induced proteotoxic stress causes the cell-autonomous innate immune system to induce a type I interferon signature. These results indicate an important role for DDI2 in the proteostasis network of cells and tissues and in the maintenance of a balanced immune response.

scholarly journals In Vitro Effects of Sulforaphane on Interferon-Driven Inflammation and Exploratory Evaluation in Two Healthy Volunteers

Molecules ◽  
2021 ◽  
Vol 26 (12) ◽  
pp. 3602
Author(s):  
Elena Genova ◽  
Maura Apollonio ◽  
Giuliana Decorti ◽  
Alessandra Tesser ◽  
Alberto Tommasini ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Supportive Therapy ◽  
P Value ◽  
Type I ◽  
Interferon Signature ◽  
Interferon Stimulated Genes ◽  
Immune System Activation ◽  
In Vitro Effects

Interferonopathies are rare genetic conditions defined by systemic inflammatory episodes caused by innate immune system activation in the absence of pathogens. Currently, no targeted drugs are authorized for clinical use in these diseases. In this work, we studied the contribution of sulforaphane (SFN), a cruciferous-derived bioactive molecule, in the modulation of interferon-driven inflammation in an immortalized human hepatocytes (IHH) line and in two healthy volunteers, focusing on STING, a key-component player in interferon pathway, interferon signature modulation, and GSTM1 expression and genotype, which contributes to SFN metabolism and excretion. In vitro, SFN exposure reduced STING expression as well as interferon signature in the presence of the pro-inflammatory stimulus cGAMP (cGAMP 3 h vs. SFN+cGAMP 3 h p value < 0.0001; cGAMP 6 h vs. SFN+cGAMP 6 h p < 0.001, one way ANOVA), restoring STING expression to the level of unstimulated cells. In preliminary experiments on healthy volunteers, no appreciable variations in interferon signature were identified after SFN assumption, while only in one of them, presenting the GSTM1 wild type genotype related to reduced SFN excretion, could a downregulation of STING be recorded. This study confirmed that SFN inhibits STING-mediated inflammation and interferon-stimulated genes expression in vitro. However, only a trend towards the downregulation of STING could be reproduced in vivo. Results obtained have to be confirmed in a larger group of healthy individuals and in patients with type I interferonopathies to define if the assumption of SFN could be useful as supportive therapy.

scholarly journals B-1 cell: the precursor of a novel mononuclear phagocyte with immuno-regulatory properties

2009 ◽  
Vol 81 (3) ◽  
pp. 489-496 ◽  
Author(s):  
José Daniel Lopes ◽  
Mario Mariano
Keyword(s):  
Mammalian Cells ◽  
Giant Cells ◽  
Mononuclear Phagocyte ◽  
Different Types ◽  
Series Of Experiments ◽  
B1 Cells ◽  
Regulatory Properties

Characterization of the origin, properties, functions and fate of cells is a fundamental task for the understanding of physiological and pathological phenomena. Despite the bulk of knowledge concerning the diverse characteristics of mammalian cells, some of them, such as B-1 cells, are still poorly understood. Here we report the results obtained in our laboratory on these cells in the last 10 years. After showing that B-1 cells could be cultured and amplified in vitro, a series of experiments were performed with these cells. They showed that B1 cells reside mostly in the peritoneal and pleural cavities, migrate to distant inflammatory foci, coalesce to form giant cells and participate in granuloma formation, both in vitro and in vivo. They are also able to present antigens to immunologically responsive cells and are endowed with regulatory properties. Further, we have also shown that these cells facilitate different types of infection as well as tumor growth and spreading. These data are presently reviewed pointing to a pivotal role that these cells may play in innate and acquired immunity.

Alterations in an IRE1-RNA complex in the mammalian unfolded protein response

2001 ◽  
Vol 114 (17) ◽  
pp. 3207-3212
Author(s):  
Anne Bertolotti ◽  
David Ron
Keyword(s):  
Unfolded Protein Response ◽  
Mammalian Cells ◽  
Dynamic Change ◽  
Rna Molecules ◽  
Unfolded Protein ◽  
Rna Fragments ◽  
Stressed Cells ◽  
Rna Complex ◽  
Protein Response

IRE1 proteins mediate cellular responses to accumulation of malfolded proteins in the endoplasmic reticulum in the yeast and mammalian unfolded protein responses. A sensitive in vivo u.v. crosslinking assay showed that IRE1 proteins are intimately associated with RNA in mammalian cells. The IRE1-associated RNA fragments recovered by this assay were different in stressed and unstressed cells. The amount of RNA associated with IRE1 that could be revealed by end-labeling with T4 kinase was greater in IRE1-containing complexes isolated from stressed cells. Furthermore, the RNA fragments recovered from complexes found in stressed cells were shorter than those from unstressed cells, revealing a dynamic change in the IRE1-RNA complex during the UPR. Formation of the complex between IRE1 and RNA was dependent on both the kinase and endonuclease domains of IRE1, and involved pre-existing RNA species. When viewed in the context of the known importance of Ire1p-HAC1 mRNA interactions to the yeast unfolded protein response, these findings suggest that full-length mammalian IRE1s also engage RNA molecules as downstream effectors.

scholarly journals Interaction between a 54-Kilodalton Mammalian Cell Surface Protein and Cowpea Mosaic Virus

2006 ◽  
Vol 81 (4) ◽  
pp. 1632-1640 ◽  
Author(s):  
Kristopher J. Koudelka ◽  
Chris S. Rae ◽  
Maria J. Gonzalez ◽  
Marianne Manchester
Keyword(s):  
Mosaic Virus ◽  
Mammalian Cells ◽  
Plasma Membranes ◽  
Vaccine Development ◽  
Surface Protein ◽  
Cowpea Mosaic Virus ◽  
Murine Fibroblasts ◽  
Mammalian System

ABSTRACT Cowpea mosaic virus (CPMV), a plant virus that is a member of the picornavirus superfamily, is increasingly being used for nanotechnology applications, including material science, vascular imaging, vaccine development, and targeted drug delivery. For these applications, it is critical to understand the in vivo interactions of CPMV within the mammalian system. Although the bioavailability of CPMV in the mouse has been demonstrated, the specific interactions between CPMV and mammalian cells need to be characterized further. Here we demonstrate that although the host range for replication of CPMV is confined to plants, mammalian cells nevertheless bind and internalize CPMV in significant amounts. This binding is mediated by a conserved 54-kDa protein found on the plasma membranes of both human and murine cell lines. Studies using a deficient cell line, deglycosidases, and glycosylation inhibitors showed that the CPMV binding protein (CPMV-BP) is not glycosylated. A possible 47-kDa isoform of the CPMV-BP was also detected in the organelle and nuclear subcellular fraction prepared from murine fibroblasts. Further characterization of CPMV-BP is important to understand how CPMV is trafficked through the mammalian system and may shed light on how picornaviruses may have evolved between plant and animal hosts.

scholarly journals Mammalian Casein Kinase 1α and Its Leishmanial Ortholog Regulate Stability of IFNAR1 and Type I Interferon Signaling

2009 ◽  
Vol 29 (24) ◽  
pp. 6401-6412 ◽  
Author(s):  
Jianghuai Liu ◽  
Lucas P. Carvalho ◽  
Sabyasachi Bhattacharya ◽  
Christopher J. Carbone ◽  
K. G. Suresh Kumar ◽  
...  
Keyword(s):  
Er Stress ◽  
Mammalian Cells ◽  
Leishmania Major ◽  
Type I Interferon ◽  
Casein Kinase ◽  
Type I ◽  
Bona Fide ◽  
Activity Dependent

ABSTRACT Phosphorylation of the degron of the IFNAR1 chain of the type I interferon (IFN) receptor triggers ubiquitination and degradation of this receptor and, therefore, plays a crucial role in negative regulation of IFN-α/β signaling. Besides the IFN-stimulated and Jak activity-dependent pathways, a basal ligand-independent phosphorylation of IFNAR1 has been described and implicated in downregulating IFNAR1 in response to virus-induced endoplasmic reticulum (ER) stress. Here we report purification and characterization of casein kinase 1α (CK1α) as a bona fide major IFNAR1 kinase that confers basal turnover of IFNAR1 and cooperates with ER stress stimuli to mediate phosphorylation-dependent degradation of IFNAR1. Activity of CK1α was required for phosphorylation and downregulation of IFNAR1 in response to ER stress and viral infection. While many forms of CK1 were capable of phosphorylating IFNAR1 in vitro, human CK1α and L-CK1 produced by the protozoan Leishmania major were also capable of increasing IFNAR1 degron phosphorylation in cells. Expression of leishmania CK1 in mammalian cells stimulated the phosphorylation-dependent downregulation of IFNAR1 and attenuated its signaling. Infection of mammalian cells with L. major modestly decreased IFNAR1 levels and attenuated cellular responses to IFN-α in vitro. We propose a role for mammalian and parasite CK1 enzymes in regulating IFNAR1 stability and type I IFN signaling.

scholarly journals Baculovirus-inducing fast-acting innate immunity kills Plasmodium liver stages

2018 ◽  
Author(s):  
Talha Bin Emran ◽  
Mitsuhiro Iyori ◽  
Yuki Ono ◽  
Fitri Amelia ◽  
Yenni Yusuf ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Type I ◽  
Innate Immune Responses ◽  
Independent Manner ◽  
Liver Stage ◽  
Interferon Stimulated Genes ◽  
Rna Transcripts ◽  
Double Stranded Dna ◽  
Further Development

ABSTRACTBaculovirus (BV), an enveloped insect virus with a circular double-stranded DNA genome, possesses unique characteristics that induce strong innate immune responses in mammalian cells. Here, we show that BV administration not only sterilely protects BALB/c mice for at least 7 days from subsequent Plasmodium berghei sporozoite infection but also eliminates existing liver-stage parasites completely, effects superior to those of primaquine, and does so in a TLR9-independent manner. Six hours post-BV administration, IFN-α and IFN-γ were robustly produced in serum, and RNA transcripts of interferon-stimulated genes were drastically upregulated in the liver. The in vivo passive transfer of post-BV administration serum effectively eliminated liver-stage parasites, and IFN-α neutralization abolished this effect, indicating that the BV liver-stage parasite killing mechanism is downstream of the type I IFN signaling pathway. Our results demonstrate that BV is a potent IFN-inducing prophylactic and therapeutic agent with great potential for further development as a new malaria vaccine and/or anti-hypnozoite drug.

scholarly journals TLT-1 Regulates Thrombus Growth Under Non-Inflammatory Conditions

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 1050-1050
Author(s):  
Angela Doerr ◽  
Denise Pedrosa ◽  
Maria Schander ◽  
Yotis A. Senis ◽  
Alexandra Mazharian ◽  
...  
Keyword(s):  
Platelet Activation ◽  
Type I Collagen ◽  
Platelet Rich Plasma ◽  
Thrombus Formation ◽  
Type I ◽  
Wild Type ◽  
Platelet Surface ◽  
Knock Out ◽  
Integrin Αiibβ3

Abstract Background Thrombus formation is a complex, dynamic and multistep process, based on two crucial steps: platelet adhesion and platelet aggregation that both involve the large multimeric plasma glycoprotein Von Willebrand Factor (VWF). VWF binding to the GPIb/X/V complex initiates platelet adhesion to the vessel wall at high shear stress and triggers platelet activation resulting in the generation of thrombin and activation of integrin αIIbβ3 on the platelet surface. This activation of αIIbβ3 in turn leads to outside-in signalling and promotes binding of αIIbβ3 to fibrinogen and VWF, mediating thrombus growth. Trigging receptor expressed on myeloid cells like transcript-1 (TLT-1) is a transmembrane receptor, which is targeted to α-granules of platelets and megakaryocytes. Thrombin-induced platelet activation rapidly presents TLT-1 on the platelet surface and releases a soluble form (sTLT-1) into the circulation. To date the only known ligand for TLT-1 is fibrinogen and TLT-1 has been implicated in the regulation of inflammation-associated thrombosis. Interestingly, a putative interaction of VWF with TLT-1 was indicated by a screen with known platelet receptors. Aim We aimed to evaluate the effect of TLT-1/VWF interaction on platelet aggregation and thrombus formation. Methods Recombinant TLT-1 and VWF were purified and the interaction between TLT-1 and VWF was analyzed by surface plasmon resonance. Static interaction was confirmed by an ELISA based binding assay. Flow assays assessed TLT-1 dependent thrombus formation in vitro. The effects of TLT-1 knockout on thrombus formation in vivo were examined via intravital microscopy of the flow restricted inferior vena cava (IVC) and imaging of platelet attachment and fibrin formation over 6 hours. Furthermore, thrombus formation and resolution was followed by high resolution ultrasound imaging after stenosis induction for 28 days. Integrin aIIbb3 activation was analysed by flow cytometry using the JonA antibody in murine platelet rich plasma. Results VWF bound to soluble TLT-1 with high affinity in a calcium dependent manner (K D = 1.9 nM). The binding site on VWF was mapped to the A3D4 domains and high molecular weight VWF multimers had the greatest affinity for TLT-1. Moreover, HEK293 cells transfected with TLT-1 bound to VWF and VWF strings formed specifically on TLT-1 expressing cells, confirming the interaction between the two proteins. VWF inhibited the binding of fibrinogen to TLT-1, suggesting that VWF is a preferred binding partner of TLT-1. Human platelets exhibited increased TLT-1 surface expression after TRAP-6 induced platelet activation and TLT-1 was detected throughout thrombi formed under flow. Furthermore, a TLT-1 blocking antibody inhibited the interaction of TLT-1 with VWF and reduced platelet capture to type I collagen under shear stress. Ex vivo perfusion of blood from TLT-1 knock out mice over type I collagen also resulted in reduced thrombus formation compared to blood from wild-type mice. TLT-1 knock-out platelets were activated by thrombin similar to wild-type controls, based on P-selectin expression in platelet rich plasma. However, activation of integrin αIIbβ3 determined by JonA staining was reduced in the absence of TLT-1. This phenotype of reduced integrin αIIbβ3 activation on P-selectin positive platelets was phenocopied by the thrombin platelet response in platelet rich plasma from VWF -/- mice, but not GPIbα-deficient mice, indicating that the TLT-1-VWF interaction on platelets directly influences integrin αIIbβ3 activation. Significantly, thrombus formation was markedly reduced in TLT-1 knockout mice in the IVC model in vivo in comparison to wild-type mice. Conclusions This study demonstrates that TLT-1 is a novel platelet ligand for VWF, and that TLT-1 may preferentially bind VWF over fibrinogen. We propose a TLT-1/VWF dependent integrin αIIbβ3 activation mechanism which plays a pivotal role in thrombus formation under non-inflammatory and potentially inflammatory conditions. Disclosures Ruf: ICONIC Therapeutics: Consultancy; MeruVasimmune: Current holder of individual stocks in a privately-held company; ARCA bioscience: Consultancy, Patents & Royalties.

scholarly journals HIVEP1 Is a Negative Regulator of NF-κB That Inhibits Systemic Inflammation in Sepsis

2021 ◽  
Vol 12 ◽  
Author(s):  
Hisatake Matsumoto ◽  
Brendon P. Scicluna ◽  
Kin Ki Jim ◽  
Fahimeh Falahi ◽  
Wanhai Qin ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Negative Regulator ◽  
Type I ◽  
Promoter Regions ◽  
Monocytic Cells ◽  
Site Analysis ◽  
Enhancer Binding Protein ◽  
Transcriptomic Changes

Our previous work identified human immunodeficiency virus type I enhancer binding protein 1 (HIVEP1) as a putative driver of LPS-induced NF-κB signaling in humans in vivo. While HIVEP1 is known to interact with NF-ĸB binding DNA motifs, its function in mammalian cells is unknown. We report increased HIVEP1 mRNA expression in monocytes from patients with sepsis and monocytes stimulated by Toll-like receptor agonists and bacteria. In complementary overexpression and gene deletion experiments HIVEP1 was shown to inhibit NF-ĸB activity and induction of NF-ĸB responsive genes. RNA sequencing demonstrated profound transcriptomic changes in HIVEP1 deficient monocytic cells and transcription factor binding site analysis showed enrichment for κB site regions. HIVEP1 bound to the promoter regions of NF-ĸB responsive genes. Inhibition of cytokine production by HIVEP1 was confirmed in LPS-stimulated murine Hivep1-/- macrophages and HIVEP1 knockdown zebrafish exposed to the common sepsis pathogen Streptococcus pneumoniae. These results identify HIVEP1 as a negative regulator of NF-κB in monocytes/macrophages that inhibits proinflammatory reactions in response to bacterial agonists in vitro and in vivo.

scholarly journals AMPylation matches BiP activity to client protein load in the endoplasmic reticulum

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Steffen Preissler ◽  
Cláudia Rato ◽  
Ruming Chen ◽  
Robin Antrobus ◽  
Shujing Ding ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Mammalian Cells ◽  
Atp Hydrolysis ◽  
Covalent Modification ◽  
Dependent Manner ◽  
Gene Encoding ◽  
Unfolded Protein ◽  
Peptide Dissociation

The endoplasmic reticulum (ER)-localized Hsp70 chaperone BiP affects protein folding homeostasis and the response to ER stress. Reversible inactivating covalent modification of BiP is believed to contribute to the balance between chaperones and unfolded ER proteins, but the nature of this modification has so far been hinted at indirectly. We report that deletion of FICD, a gene encoding an ER-localized AMPylating enzyme, abolished detectable modification of endogenous BiP enhancing ER buffering of unfolded protein stress in mammalian cells, whilst deregulated FICD activity had the opposite effect. In vitro, FICD AMPylated BiP to completion on a single residue, Thr518. AMPylation increased, in a strictly FICD-dependent manner, as the flux of proteins entering the ER was attenuated in vivo. In vitro, Thr518 AMPylation enhanced peptide dissociation from BiP 6-fold and abolished stimulation of ATP hydrolysis by J-domain cofactor. These findings expose the molecular basis for covalent inactivation of BiP.

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