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IRE1α-driven inflammation promotes clearance of Citrobacter rodentium infection. Infect Immun 2021; 90:e0048121. [PMID: 34748367 PMCID: PMC8788755 DOI: 10.1128/iai.00481-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Endoplasmic reticulum (ER) stress is intimately linked with inflammation in response to pathogenic infections. ER stress occurs when cells experience a buildup of misfolded or unfolded protein during times of perturbation, such as infections, which facilitates the unfolded protein response (UPR). The UPR involves multiple host pathways in an attempt to re-establish homeostasis, which oftentimes leads to inflammation and cell death if unresolved. The UPR is activated to help resolve some bacterial infections, and the IRE1α pathway is especially critical in mediating inflammation. To understand the role of the IRE1α pathway of the UPR during enteric bacterial infection, we employed Citrobacter rodentium to study host-pathogen interactions in intestinal epithelial cells and the murine gastrointestinal (GI) tract. C. rodentium is an enteric mouse pathogen that is similar to the human pathogens enteropathogenic and enterohemorrhagic Escherichia coli (EPEC and EHEC, respectively), which have limited small animal models. Here, we demonstrate that both C. rodentium and EPEC induced the UPR in intestinal epithelial cells. UPR induction during C. rodentium infection correlated with the onset of inflammation in bone marrow-derived macrophages (BMDMs). Our previous work implicated IRE1α and NOD1/2 in ER stress-induced inflammation, which we observed were also required for pro-inflammatory gene induction during C. rodentium infection. C. rodentium induced IRE1α-dependent inflammation in mice, and inhibiting IRE1α led to a dysregulated inflammatory response and delayed clearance of C. rodentium. This study demonstrates that ER stress aids inflammation and clearance of C. rodentium through a mechanism involving the IRE1α-NOD1/2 axis.
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Hossain MM, Pérez-López E, Todd CD, Wei Y, Bonham-Smith PC. Endomembrane-Targeting Plasmodiophora brassicae Effectors Modulate PAMP Triggered Immune Responses in Plants. Front Microbiol 2021; 12:651279. [PMID: 34276588 PMCID: PMC8282356 DOI: 10.3389/fmicb.2021.651279] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 05/31/2021] [Indexed: 11/13/2022] Open
Abstract
Plasmodiophora brassicae is a devastating obligate, intracellular, biotrophic pathogen that causes clubroot disease in crucifer plants. Disease progression is regulated by effector proteins secreted by P. brassicae. Twelve P. brassicae putative effectors (PbPEs), expressed at various stages of disease development [0, 2, 5, 7, 14, 21, and 28 days post inoculation (DPI)] in Arabidopsis and localizing to the plant endomembrane system, were studied for their roles in pathogenesis. Of the 12 PbPEs, seven showed an inhibitory effect on programmed cell death (PCD) as triggered by the PCD inducers, PiINF1 (Phytophthora infestans Infestin 1) and PiNPP1 (P. infestans necrosis causing protein). Showing the strongest level of PCD suppression, PbPE15, a member of the 2-oxoglutarate (2OG) and Fe (II)-dependent oxygenase superfamily and with gene expression during later stages of infection, appears to have a role in tumorigenesis as well as defense signaling in plants. PbPE13 produced an enhanced PiINF1-induced PCD response. Transient expression, in Nicotiana benthamiana leaves of these PbPEs minus the signal peptide (SP) (Δsp PbPEGFPs), showed localization to the endomembrane system, targeting the endoplasmic reticulum (ER), Golgi bodies and nucleo-cytoplasm, suggesting roles in manipulating plant cell secretion and vesicle trafficking. Δsp PbPE13GFP localized to plasma membrane (PM) lipid rafts with an association to plasmodesmata, suggesting a role at the cell-to-cell communication junction. Membrane relocalization of Δsp PbPE13GFP, triggered by flagellin N-terminus of Pseudomonas aeruginosa (flg22 - known to elicit a PAMP triggered immune response in plants), supports its involvement in raft-mediated immune signaling. This study is an important step in deciphering P. brassicae effector roles in the disruption of plant immunity to clubroot disease.
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Affiliation(s)
| | - Edel Pérez-López
- Department of Plant Sciences, Laval University, CRIV, Quebec City, QC, Canada
| | - Christopher D Todd
- Department of Biology, University of Saskatchewan, Saskatoon, SK, Canada
| | - Yangdou Wei
- Department of Biology, University of Saskatchewan, Saskatoon, SK, Canada
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Almeida C. A potential third-order role of the host endoplasmic reticulum as a contact site in interkingdom microbial endosymbiosis and viral infection. ENVIRONMENTAL MICROBIOLOGY REPORTS 2021; 13:255-271. [PMID: 33559322 DOI: 10.1111/1758-2229.12938] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Revised: 02/04/2021] [Accepted: 02/05/2021] [Indexed: 06/12/2023]
Abstract
The normal functioning of eukaryotic cells depends on the compartmentalization of metabolic processes within specific organelles. Interactions among organelles, such as those between the endoplasmic reticulum (ER) - considered the largest single structure in eukaryotic cells - and other organelles at membrane contact sites (MCSs) have also been suggested to trigger synergisms, including intracellular immune responses against pathogens. In addition to the ER-endogenous functions and ER-organelle MCSs, we present the perspective of a third-order role of the ER as a host contact site for endosymbiotic microbial non-pathogens and pathogens, from endosymbiont bacteria to parasitic protists and viruses. Although understudied, ER-endosymbiont interactions have been observed in a range of eukaryotic hosts, including protists, plants, algae, and metazoans. Host ER interactions with endosymbionts could be an ER function built from ancient, conserved mechanisms selected for communicating with mutualistic endosymbionts in specific life cycle stages, and they may be exploited by pathogens and parasites. The host ER-'guest' interactome and traits in endosymbiotic biology are briefly discussed. The acknowledgment and understanding of these possible mechanisms might reveal novel evolutionary perspectives, uncover the causes of unexplained cellular disorders and suggest new pharmacological targets.
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Affiliation(s)
- Celso Almeida
- ENDOBIOS Biotech®, Praceta Progresso Clube n° 6, 2725-110 Mem-Martins, Portugal
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Abstract
Intracellular proliferation of Legionella pneumophila within a vacuole in human alveolar macrophages is essential for manifestation of Legionnaires’ pneumonia. Intravacuolar growth of the pathogen is totally dependent on remodeling the L. pneumophila-containing vacuole (LCV) by the ER and on its evasion of the endosomal-lysosomal degradation pathway. Diversion of the Legionella pneumophila-containing vacuole (LCV) from the host endosomal-lysosomal degradation pathway is one of the main virulence features essential for manifestation of Legionnaires’ pneumonia. Many of the ∼350 Dot/Icm-injected effectors identified in L. pneumophila have been shown to interfere with various host pathways and processes, but no L. pneumophila effector has ever been identified to be indispensable for lysosomal evasion. While most single effector mutants of L. pneumophila do not exhibit a defective phenotype within macrophages, we show that the MavE effector is essential for intracellular growth of L. pneumophila in human monocyte-derived macrophages (hMDMs) and amoebae and for intrapulmonary proliferation in mice. The mavE null mutant fails to remodel the LCV with endoplasmic reticulum (ER)-derived vesicles and is trafficked to the lysosomes where it is degraded, similar to formalin-killed bacteria. During infection of hMDMs, the MavE effector localizes to the poles of the LCV membrane. The crystal structure of MavE, resolved to 1.8 Å, reveals a C-terminal transmembrane helix, three copies of tyrosine-based sorting motifs, and an NPxY eukaryotic motif, which binds phosphotyrosine-binding domains present on signaling and adaptor eukaryotic proteins. Two point mutations within the NPxY motif result in attenuation of L. pneumophila in both hMDMs and amoeba. The substitution defects of P78 and D64 are associated with failure of vacuoles harboring the mutant to be remodeled by the ER and results in fusion of the vacuole to the lysosomes leading to bacterial degradation. Therefore, the MavE effector of L. pneumophila is indispensable for phagosome biogenesis and lysosomal evasion.
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Friedrich A, Beare PA, Schulze-Luehrmann J, Cordsmeier A, Pazen T, Sonnewald S, Lührmann A. The Coxiella burnetii effector protein CaeB modulates endoplasmatic reticulum (ER) stress signalling and is required for efficient replication in Galleria mellonella. Cell Microbiol 2021; 23:e13305. [PMID: 33355405 DOI: 10.1111/cmi.13305] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 12/15/2020] [Accepted: 12/20/2020] [Indexed: 01/02/2023]
Abstract
The obligate intracellular pathogen Coxiella burnetii is the causative agent of the zoonosis Q fever. C. burnetii infection can have severe outcomes due to the development of chronic infection. To establish and maintain an infection, C. burnetii depends on a functional type IVB secretion system (T4BSS) and, thus, on the translocation of effector proteins into the host cell. Here, we showed that the C. burnetii T4BSS effector protein CaeB targets the conserved endoplasmatic reticulum (ER) stress sensor IRE1 during ER stress in mammalian and plant cells. CaeB-induced upregulation of IRE1 RNase activity was essential for CaeB-mediated inhibition of ER stress-induced cell death. Our data reveal a novel role for CaeB in ER stress signalling modulation and demonstrate that CaeB is involved in pathogenicity in vivo. Furthermore, we provide evidence that C. burnetii infection leads to modulation of the ER stress sensors IRE1 and PERK, but not ATF6 during ER stress. While the upregulation of the RNase activity of IRE1 during ER stress depends on CaeB, modulation of PERK is CaeB independent, suggesting that C. burnetii encodes several factors influencing ER stress during infection.
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Affiliation(s)
- Anja Friedrich
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany.,Lehrstuhl für Biochemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Paul A Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Jan Schulze-Luehrmann
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Arne Cordsmeier
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Tobias Pazen
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Sophia Sonnewald
- Lehrstuhl für Biochemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Anja Lührmann
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
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Long RKM, Moriarty KP, Cardoen B, Gao G, Vogl AW, Jean F, Hamarneh G, Nabi IR. Super resolution microscopy and deep learning identify Zika virus reorganization of the endoplasmic reticulum. Sci Rep 2020; 10:20937. [PMID: 33262363 PMCID: PMC7708840 DOI: 10.1038/s41598-020-77170-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 10/28/2020] [Indexed: 01/08/2023] Open
Abstract
The endoplasmic reticulum (ER) is a complex subcellular organelle composed of diverse structures such as tubules, sheets and tubular matrices. Flaviviruses such as Zika virus (ZIKV) induce reorganization of ER membranes to facilitate viral replication. Here, using 3D super resolution microscopy, ZIKV infection is shown to induce the formation of dense tubular matrices associated with viral replication in the central ER. Viral non-structural proteins NS4B and NS2B associate with replication complexes within the ZIKV-induced tubular matrix and exhibit distinct ER distributions outside this central ER region. Deep neural networks trained to distinguish ZIKV-infected versus mock-infected cells successfully identified ZIKV-induced central ER tubular matrices as a determinant of viral infection. Super resolution microscopy and deep learning are therefore able to identify and localize morphological features of the ER and allow for better understanding of how ER morphology changes due to viral infection.
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Affiliation(s)
- Rory K M Long
- Life Sciences Institute, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.,Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.,Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada
| | - Kathleen P Moriarty
- School of Computing Science, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - Ben Cardoen
- School of Computing Science, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada
| | - Guang Gao
- Life Sciences Institute, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.,Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada
| | - A Wayne Vogl
- Life Sciences Institute, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.,Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada
| | - François Jean
- Life Sciences Institute, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada. .,Department of Microbiology and Immunology, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
| | - Ghassan Hamarneh
- School of Computing Science, Simon Fraser University, Burnaby, BC, V5A 1S6, Canada.
| | - Ivan R Nabi
- Life Sciences Institute, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada. .,Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada. .,School of Biomedical Engineering, University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
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Yoshikawa Y, Sugimoto K, Ochiai Y, Ohashi N. Intracellular proliferation of Anaplasma phagocytophilum is promoted via modulation of endoplasmic reticulum stress signaling in host cells. Microbiol Immunol 2020; 64:270-279. [PMID: 31909489 DOI: 10.1111/1348-0421.12770] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 12/17/2019] [Accepted: 01/05/2020] [Indexed: 02/06/2023]
Abstract
Anaplasma phagocytophilum, an obligate intracellular bacterium that propagates within host granulocytes, is considered to modify the host intracellular environment for pathogenesis. However, the mechanism(s) underlying such host modifications remain unclear. Here, we aimed to investigate the relation between A. phagocytophilum and endoplasmic reticulum (ER) stress in THP-1 cells. A. phagocytophilum activated the three ER stress sensors: inositol-requiring enzyme-1 (IRE1), protein kinase RNA-like endoplasmic reticulum kinase (PERK), and activating transcription factor-6 (ATF6). IRE1 activation occurred immediately after host cell invasion by A. phagocytophilum; however, the activated IRE1-induced splicing of X-box-binding protein 1 was not promoted during A. phagocytophilum infection. This suppression was sustained even after the doxycycline-mediated elimination of intracellular A. phagocytophilum. IRE1 knockdown accelerated A. phagocytophilum-induced apoptosis and decreased intracellular A. phagocytophilum. These data suggest that A. phagocytophilum utilizes IRE1 activation to promote its own intracellular proliferation. Moreover, PERK and ATF6 partially mediated A. phagocytophilum-induced apoptosis by promoting the expression of CCAAT/enhancer-binding protein homologous protein, which induces the transcription of several proapoptotic genes. Thus, A. phagocytophilum possibly manipulates the host ER stress signals to facilitate intracellular proliferation and infection of surrounding cells before/after host cell apoptosis.
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Affiliation(s)
- Yuko Yoshikawa
- Laboratory of Microbiology, Department of Food and Nutritional Sciences, Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, Shizuoka, Japan.,Laboratory of Veterinary Public Health, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, Tokyo, Japan
| | - Kei Sugimoto
- Laboratory of Microbiology, Department of Food and Nutritional Sciences, Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, Shizuoka, Japan
| | - Yoshitsugu Ochiai
- Laboratory of Veterinary Public Health, School of Veterinary Medicine, Faculty of Veterinary Science, Nippon Veterinary and Life Science University, Tokyo, Japan
| | - Norio Ohashi
- Laboratory of Microbiology, Department of Food and Nutritional Sciences, Graduate School of Integrated Pharmaceutical and Nutritional Sciences, University of Shizuoka, Shizuoka, Japan
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Bleves S, Galán JE, Llosa M. Bacterial injection machines: Evolutionary diverse but functionally convergent. Cell Microbiol 2020; 22:e13157. [PMID: 31891220 DOI: 10.1111/cmi.13157] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 12/19/2019] [Indexed: 12/23/2022]
Abstract
Many human pathogens use Type III, Type IV, and Type VI secretion systems to deliver effectors into their target cells. The contribution of these secretion systems to microbial virulence was the main focus of a workshop organised by the International University of Andalusia in Spain. The meeting addressed structure-function, substrate recruitment, and translocation processes, which differ widely on the different secretion machineries, as well as the nature of the translocated effectors and their roles in subverting the host cell. An excellent panel of worldwide speakers presented the state of the art of the field, highlighting the involvement of bacterial secretion in human disease and discussing mechanistic aspects of bacterial pathogenicity, which can provide the bases for the development of novel antivirulence strategies.
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Affiliation(s)
- Sophie Bleves
- LISM (Laboratoire d'Ingénierie des Systèmes Macromoléculaires-UMR7255), IMM (Institut de Microbiologie de la Méditerranée), Aix-Marseille Univ and CNRS, Marseille, France
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut
| | - Matxalen Llosa
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-CSIC-SODERCAN, Santander, Spain
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