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Chatterjee R, Chowdhury AR, Mukherjee D, Chakravortty D. Lipid larceny: channelizing host lipids for establishing successful pathogenesis by bacteria. Virulence 2021; 12:195-216. [PMID: 33356849 PMCID: PMC7808437 DOI: 10.1080/21505594.2020.1869441] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 12/03/2020] [Accepted: 12/17/2020] [Indexed: 12/16/2022] Open
Abstract
Lipids are complex organic compounds made up of carbon, oxygen, and hydrogen. These play a diverse and intricate role in cellular processes like membrane trafficking, protein sorting, signal transduction, and bacterial infections. Both Gram-positive bacteria (Staphylococcus sp., Listeria monocytogenes, etc.) and Gram-negative bacteria (Chlamydia sp., Salmonella sp., E. coli, etc.) can hijack the various host-lipids and utilize them structurally as well as functionally to mount a successful infection. The pathogens can deploy with various arsenals to exploit host membrane lipids and lipid-associated receptors as an attachment for toxins' landing or facilitate their entry into the host cellular niche. Bacterial species like Mycobacterium sp. can also modulate the host lipid metabolism to fetch its carbon source from the host. The sequential conversion of host membrane lipids into arachidonic acid and prostaglandin E2 due to increased activity of cPLA-2 and COX-2 upon bacterial infection creates immunosuppressive conditions and facilitates the intracellular growth and proliferation of bacteria. However, lipids' more debatable role is that they can also be a blessing in disguise. Certain host-lipids, especially sphingolipids, have been shown to play a crucial antibacterial role and help the host in combating the infections. This review shed light on the detailed role of host lipids in bacterial infections and the current understanding of the lipid in therapeutics. We have also discussed potential prospects and the need of the hour to help us cope in this race against deadly pathogens and their rapidly evolving stealthy virulence strategies.
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Affiliation(s)
- Ritika Chatterjee
- Department of Microbiology and Cell Biology, Division of Biological Sciences, Indian Institute of Science, Bangalore, India
| | - Atish Roy Chowdhury
- Department of Microbiology and Cell Biology, Division of Biological Sciences, Indian Institute of Science, Bangalore, India
| | - Debapriya Mukherjee
- Department of Microbiology and Cell Biology, Division of Biological Sciences, Indian Institute of Science, Bangalore, India
| | - Dipshikha Chakravortty
- Department of Microbiology and Cell Biology, Division of Biological Sciences, Indian Institute of Science, Bangalore, India
- Centre for Biosystems Science and Engineering, Indian Institute of Science, Bangalore, India
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2
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Dadhich R, Kapoor S. Various Facets of Pathogenic Lipids in Infectious Diseases: Exploring Virulent Lipid-Host Interactome and Their Druggability. J Membr Biol 2020; 253:399-423. [PMID: 32833058 PMCID: PMC7443855 DOI: 10.1007/s00232-020-00135-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 08/12/2020] [Indexed: 02/07/2023]
Abstract
Lipids form an integral, structural, and functional part of all life forms. They play a significant role in various cellular processes such as membrane fusion, fission, endocytosis, protein trafficking, and protein functions. Interestingly, recent studies have revealed their more impactful and critical involvement in infectious diseases, starting with the manipulation of the host membrane to facilitate pathogenic entry. Thereafter, pathogens recruit specific host lipids for the maintenance of favorable intracellular niche to augment their survival and proliferation. In this review, we showcase the lipid-mediated host pathogen interplay in context of life-threatening viral and bacterial diseases including the recent SARS-CoV-2 infection. We evaluate the emergent lipid-centric approaches adopted by these pathogens, while delineating the alterations in the composition and organization of the cell membrane within the host, as well as the pathogen. Lastly, crucial nexus points in their interaction landscape for therapeutic interventions are identified. Lipids act as critical determinants of bacterial and viral pathogenesis by altering the host cell membrane structure and functions.
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Affiliation(s)
- Ruchika Dadhich
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, 400076, India.
| | - Shobhna Kapoor
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, 400076, India.
- Wadhwani Research Centre for Bioengineering, Indian Institute of Technology Bombay, Mumbai, 400076, India.
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3
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Li Y, Talotta-Altenburg LM, Silimperi KA, Ciabattoni GO, Lowe-Krentz LJ. Endothelial nitric oxide synthase activation is required for heparin receptor effects on vascular smooth muscle cells. Am J Physiol Cell Physiol 2019; 318:C463-C475. [PMID: 31891520 DOI: 10.1152/ajpcell.00284.2018] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Published studies indicate that TMEM184A is a heparin receptor that interacts with and transduces stimulation from heparin in vascular cells. Previous studies have indicated that heparin increases endothelial nitric oxide synthase (eNOS) activity in bovine endothelial cells. However, the precise mechanism remains unknown. In this study, we investigated the impact of heparin treatment and TMEM184A on eNOS's activation and the role of eNOS in heparin signaling in the cloned A7r5 rat vascular smooth muscle cell line and confirmed results in endothelial cells. We employed a combination of TMEM184A knockdown A7r5 cells along with transient eNOS knockdown and enzyme inhibitor strategies. The results indicate that heparin induces phosphorylation of eNOS. eNOS can be immunoprecipitated with TMEM184A and is internalized to the perinuclear region in a TMEM184A-dependent manner in response to heparin. We also examined how heparin treatment leads to phosphorylation of eNOS and confirmed that TMEM184A and Ca2+ were required to mediate heparin-elicited eNOS phosphorylation. Evidence supporting the involvement of transient receptor potential cation channel subfamily V member 4 with TMEM184A in this eNOS activation process is also presented.
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Affiliation(s)
- Yaqiu Li
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania
| | | | - Kayli A Silimperi
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania
| | - Grace O Ciabattoni
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania
| | - Linda J Lowe-Krentz
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania
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4
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Otopathogenic Staphylococcus aureus Invades Human Middle Ear Epithelial Cells Primarily through Cholesterol Dependent Pathway. Sci Rep 2019; 9:10777. [PMID: 31346200 PMCID: PMC6658548 DOI: 10.1038/s41598-019-47079-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 06/26/2019] [Indexed: 01/20/2023] Open
Abstract
Chronic suppurative otitis media (CSOM) is one of the most common infectious diseases of the middle ear especially affecting children, leading to delay in language development and communication. Although Staphylococcus aureus is the most common pathogen associated with CSOM, its interaction with middle ear epithelial cells is not well known. In the present study, we observed that otopathogenic S. aureus has the ability to invade human middle ear epithelial cells (HMEECs) in a dose and time dependent manner. Scanning electron microscopy demonstrated time dependent increase in the number of S. aureus on the surface of HMEECs. We observed that otopathogenic S. aureus primarily employs a cholesterol dependent pathway to colonize HMEECs. In agreement with these findings, confocal microscopy showed that S. aureus colocalized with lipid rafts in HMEECs. The results of the present study provide new insights into the pathogenesis of S. aureus induced CSOM. The availability of in vitro cell culture model will pave the way to develop novel effective treatment modalities for CSOM beyond antibiotic therapy.
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5
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Ares MA, Sansabas A, Rodríguez-Valverde D, Siqueiros-Cendón T, Rascón-Cruz Q, Rosales-Reyes R, Jarillo-Quijada MD, Alcántar-Curiel MD, Cedillo ML, Torres J, Girón JA, De la Cruz MA. The Interaction of Klebsiella pneumoniae With Lipid Rafts-Associated Cholesterol Increases Macrophage-Mediated Phagocytosis Due to Down Regulation of the Capsule Polysaccharide. Front Cell Infect Microbiol 2019; 9:255. [PMID: 31380298 PMCID: PMC6650577 DOI: 10.3389/fcimb.2019.00255] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 07/02/2019] [Indexed: 12/17/2022] Open
Abstract
Klebsiella pneumoniae successfully colonizes host tissues by recognizing and interacting with cholesterol present on membrane-associated lipid rafts. In this study, we evaluated the role of cholesterol in the expression of capsule polysaccharide genes of K. pneumoniae and its implication in resistance to phagocytosis. Our data revealed that exogenous cholesterol added to K. pneumoniae increases macrophage-mediated phagocytosis. To explain this event, the expression of capsular galF, wzi, and manC genes was determined in the presence of cholesterol. Down-regulation of these capsular genes occurred leading to increased susceptibility to phagocytosis by macrophages. In contrast, depletion of cholesterol from macrophage membranes led to enhanced expression of galF, wzi, and manC genes and to capsule production resulting in resistance to macrophage-mediated phagocytosis. Cholesterol-mediated repression of capsular genes was dependent on the RcsA and H-NS global regulators. Finally, cholesterol also down-regulated the expression of genes responsible for LPS core oligosaccharides production and OMPs. Our results suggest that cholesterol plays an important role for the host by reducing the anti-phagocytic properties of the K. pneumoniae capsule facilitating bacterial engulfment by macrophages during the bacteria-eukaryotic cell interaction mediated by lipid rafts.
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Affiliation(s)
- Miguel A Ares
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Centro Médico Nacional Siglo XXI, Hospital de Pediatría, Instituto Mexicano del Seguro Social, Mexico City, Mexico
| | - Alejandro Sansabas
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Centro Médico Nacional Siglo XXI, Hospital de Pediatría, Instituto Mexicano del Seguro Social, Mexico City, Mexico.,Facultad de Ciencias Químicas, Universidad Autónoma de Chihuahua, Chihuahua, Mexico
| | - Diana Rodríguez-Valverde
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Centro Médico Nacional Siglo XXI, Hospital de Pediatría, Instituto Mexicano del Seguro Social, Mexico City, Mexico.,Facultad de Ciencias Químicas, Universidad Autónoma de Chihuahua, Chihuahua, Mexico
| | | | - Quintín Rascón-Cruz
- Facultad de Ciencias Químicas, Universidad Autónoma de Chihuahua, Chihuahua, Mexico
| | - Roberto Rosales-Reyes
- Unidad de Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Ma Dolores Jarillo-Quijada
- Unidad de Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - María D Alcántar-Curiel
- Unidad de Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - María L Cedillo
- Centro de Detección Biomolecular, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Javier Torres
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Centro Médico Nacional Siglo XXI, Hospital de Pediatría, Instituto Mexicano del Seguro Social, Mexico City, Mexico
| | - Jorge A Girón
- Centro de Detección Biomolecular, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Miguel A De la Cruz
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Centro Médico Nacional Siglo XXI, Hospital de Pediatría, Instituto Mexicano del Seguro Social, Mexico City, Mexico
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6
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Thornbrough JM, Gopinath A, Hundley T, Worley MJ. Human Genome-Wide RNAi Screen for Host Factors That Facilitate Salmonella Invasion Reveals a Role for Potassium Secretion in Promoting Internalization. PLoS One 2016; 11:e0166916. [PMID: 27880807 PMCID: PMC5120809 DOI: 10.1371/journal.pone.0166916] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 11/07/2016] [Indexed: 02/06/2023] Open
Abstract
Salmonella enterica can actively invade the gastro-intestinal epithelium. This frequently leads to diarrheal disease, and also gives the pathogen access to phagocytes that can serve as vehicles for dissemination into deeper tissue. The ability to invade host cells is also important in maintaining the carrier state. While much is known about the bacterial factors that promote invasion, relatively little is known about the host factors involved. To gain insight into how Salmonella enterica serovar Typhimurium is able to invade normally non-phagocytic cells, we undertook a global RNAi screen with S. Typhimurium-infected human epithelial cells. In all, we identified 633 genes as contributing to bacterial internalization. These genes fall into a diverse group of functional categories revealing that cytoskeletal regulators are not the only factors that modulate invasion. In fact, potassium ion transport was the most enriched molecular function category in our screen, reinforcing a link between potassium and internalization. In addition to providing new insights into the molecular mechanisms underlying the ability of pathogens to invade host cells, all 633 host factors identified are candidates for new anti-microbial targets for treating Salmonella infections, and may be useful in curtailing infections with other pathogens as well.
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Affiliation(s)
- Joshua M. Thornbrough
- Department of Biology, University of Louisville, Louisville, KY, 40292, United States of America
| | - Adarsh Gopinath
- Department of Biology, University of Louisville, Louisville, KY, 40292, United States of America
| | - Tom Hundley
- Department of Biology, University of Louisville, Louisville, KY, 40292, United States of America
| | - Micah J. Worley
- Department of Biology, University of Louisville, Louisville, KY, 40292, United States of America
- Department of Microbiology and Immunology, University of Louisville, Louisville, KY, 40202, United States of America
- * E-mail:
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7
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Gaytán MO, Martínez-Santos VI, Soto E, González-Pedrajo B. Type Three Secretion System in Attaching and Effacing Pathogens. Front Cell Infect Microbiol 2016; 6:129. [PMID: 27818950 PMCID: PMC5073101 DOI: 10.3389/fcimb.2016.00129] [Citation(s) in RCA: 117] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 09/27/2016] [Indexed: 02/06/2023] Open
Abstract
Enteropathogenic Escherichia coli and enterohemorrhagic E. coli are diarrheagenic bacterial human pathogens that cause severe gastroenteritis. These enteric pathotypes, together with the mouse pathogen Citrobacter rodentium, belong to the family of attaching and effacing pathogens that form a distinctive histological lesion in the intestinal epithelium. The virulence of these bacteria depends on a type III secretion system (T3SS), which mediates the translocation of effector proteins from the bacterial cytosol into the infected cells. The core architecture of the T3SS consists of a multi-ring basal body embedded in the bacterial membranes, a periplasmic inner rod, a transmembrane export apparatus in the inner membrane, and cytosolic components including an ATPase complex and the C-ring. In addition, two distinct hollow appendages are assembled on the extracellular face of the basal body creating a channel for protein secretion: an approximately 23 nm needle, and a filament that extends up to 600 nm. This filamentous structure allows these pathogens to get through the host cells mucus barrier. Upon contact with the target cell, a translocation pore is assembled in the host membrane through which the effector proteins are injected. Assembly of the T3SS is strictly regulated to ensure proper timing of substrate secretion. The different type III substrates coexist in the bacterial cytoplasm, and their hierarchical secretion is determined by specialized chaperones in coordination with two molecular switches and the so-called sorting platform. In this review, we present recent advances in the understanding of the T3SS in attaching and effacing pathogens.
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Affiliation(s)
- Meztlli O Gaytán
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Ciudad de México, Mexico
| | - Verónica I Martínez-Santos
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Ciudad de México, Mexico
| | - Eduardo Soto
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Ciudad de México, Mexico
| | - Bertha González-Pedrajo
- Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México Ciudad de México, Mexico
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8
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Toledo A, Benach JL. Hijacking and Use of Host Lipids by Intracellular Pathogens. Microbiol Spectr 2015; 3:10.1128/microbiolspec.VMBF-0001-2014. [PMID: 27337282 PMCID: PMC5790186 DOI: 10.1128/microbiolspec.vmbf-0001-2014] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Indexed: 12/14/2022] Open
Abstract
Intracellular bacteria use a number of strategies to survive, grow, multiply, and disseminate within the host. One of the most striking adaptations that intracellular pathogens have developed is the ability to utilize host lipids and their metabolism. Bacteria such as Anaplasma, Chlamydia, or Mycobacterium can use host lipids for different purposes, such as a means of entry through lipid rafts, building blocks for bacteria membrane formation, energy sources, camouflage to avoid the fusion of phagosomes and lysosomes, and dissemination. One of the most extreme examples of lipid exploitation is Mycobacterium, which not only utilizes the host lipid as a carbon and energy source but is also able to reprogram the host lipid metabolism. Likewise, Chlamydia spp. have also developed numerous mechanisms to reprogram lipids onto their intracellular inclusions. Finally, while the ability to exploit host lipids is important in intracellular bacteria, it is not an exclusive trait. Extracellular pathogens, including Helicobacter, Mycoplasma, and Borrelia, can recruit and metabolize host lipids that are important for their growth and survival.Throughout this chapter we will review how intracellular and extracellular bacterial pathogens utilize host lipids to enter, survive, multiply, and disseminate in the host.
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Affiliation(s)
- Alvaro Toledo
- Department of Molecular Genetics and Microbiology, Stony Brook University, Center for Infectious Diseases at the Center for Molecular Medicine, Stony Brook, NY 11794
| | - Jorge L Benach
- Department of Molecular Genetics and Microbiology, Stony Brook University, Center for Infectious Diseases at the Center for Molecular Medicine, Stony Brook, NY 11794
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Chatterjee A, Caballero-Franco C, Bakker D, Totten S, Jardim A. Pore-forming Activity of the Escherichia coli Type III Secretion System Protein EspD. J Biol Chem 2015; 290:25579-94. [PMID: 26324713 DOI: 10.1074/jbc.m115.648204] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Indexed: 12/20/2022] Open
Abstract
Enterohemorrhagic Escherichia coli is a causative agent of gastrointestinal and diarrheal diseases. Pathogenesis associated with enterohemorrhagic E. coli involves direct delivery of virulence factors from the bacteria into epithelial cell cytosol via a syringe-like organelle known as the type III secretion system. The type III secretion system protein EspD is a critical factor required for formation of a translocation pore on the host cell membrane. Here, we show that recombinant EspD spontaneously integrates into large unilamellar vesicle (LUV) lipid bilayers; however, pore formation required incorporation of anionic phospholipids such as phosphatidylserine and an acidic pH. Leakage assays performed with fluorescent dextrans confirmed that EspD formed a structure with an inner diameter of ∼2.5 nm. Protease mapping indicated that the two transmembrane helical hairpin of EspD penetrated the lipid layer positioning the N- and C-terminal domains on the extralumenal surface of LUVs. Finally, a combination of glutaraldehyde cross-linking and rate zonal centrifugation suggested that EspD in LUV membranes forms an ∼280-320-kDa oligomeric structure consisting of ∼6-7 subunits.
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Affiliation(s)
- Abhishek Chatterjee
- From the Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, Ste-Anne-de-Bellevue, Québec H9X 3V9, Canada
| | - Celia Caballero-Franco
- From the Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, Ste-Anne-de-Bellevue, Québec H9X 3V9, Canada
| | - Dannika Bakker
- From the Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, Ste-Anne-de-Bellevue, Québec H9X 3V9, Canada
| | - Stephanie Totten
- From the Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, Ste-Anne-de-Bellevue, Québec H9X 3V9, Canada
| | - Armando Jardim
- From the Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, Ste-Anne-de-Bellevue, Québec H9X 3V9, Canada
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10
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Disruption of Lipid Rafts Enhances the Effect of Lactobacilli on the Production of Tumor Necrosis Factor-Alpha in Mononuclear Blood Cells. Biosci Biotechnol Biochem 2014; 72:3293-6. [DOI: 10.1271/bbb.80445] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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11
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Helicobacter pylori's cholesterol uptake impacts resistance to docosahexaenoic acid. Int J Med Microbiol 2014; 304:314-20. [DOI: 10.1016/j.ijmm.2013.11.018] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 11/06/2013] [Accepted: 11/25/2013] [Indexed: 12/14/2022] Open
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12
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Protein kinase C mediates enterohemorrhagic Escherichia coli O157:H7-induced attaching and effacing lesions. Infect Immun 2014; 82:1648-56. [PMID: 24491575 DOI: 10.1128/iai.00534-13] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enterohemorrhagic Escherichia coli serotype O157:H7 causes outbreaks of diarrhea, hemorrhagic colitis, and the hemolytic-uremic syndrome. E. coli O157:H7 intimately attaches to epithelial cells, effaces microvilli, and recruits F-actin into pedestals to form attaching and effacing lesions. Lipid rafts serve as signal transduction platforms that mediate microbe-host interactions. The aims of this study were to determine if protein kinase C (PKC) is recruited to lipid rafts in response to E. coli O157:H7 infection and what role it plays in attaching and effacing lesion formation. HEp-2 and intestine 407 tissue culture epithelial cells were challenged with E. coli O157:H7, and cell protein extracts were then separated by buoyant density ultracentrifugation to isolate lipid rafts. Immunoblotting for PKC was performed, and localization in lipid rafts was confirmed with an anti-caveolin-1 antibody. Isoform-specific PKC small interfering RNA (siRNA) was used to determine the role of PKC in E. coli O157:H7-induced attaching and effacing lesions. In contrast to uninfected cells, PKC was recruited to lipid rafts in response to E. coli O157:H7. Metabolically active bacteria and cells with intact lipid rafts were necessary for the recruitment of PKC. PKC recruitment was independent of the intimin gene, type III secretion system, and the production of Shiga toxins. Inhibition studies, using myristoylated PKCζ pseudosubstrate, revealed that atypical PKC isoforms were activated in response to the pathogen. Pretreating cells with isoform-specific PKC siRNA showed that PKCζ plays a role in E. coli O157:H7-induced attaching and effacing lesions. We concluded that lipid rafts mediate atypical PKC signal transduction responses to E. coli O157:H7. These findings contribute further to the understanding of the complex array of microbe-eukaryotic cell interactions that occur in response to infection.
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Ha B, Lv Z, Bian Z, Zhang X, Mishra A, Liu Y. 'Clustering' SIRPα into the plasma membrane lipid microdomains is required for activated monocytes and macrophages to mediate effective cell surface interactions with CD47. PLoS One 2013; 8:e77615. [PMID: 24143245 PMCID: PMC3797048 DOI: 10.1371/journal.pone.0077615] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Accepted: 09/09/2013] [Indexed: 02/04/2023] Open
Abstract
SIRPα, an ITIMs-containing signaling receptor, negatively regulates leukocyte responses through extracellular interactions with CD47. However, the dynamics of SIRPα-CD47 interactions on the cell surface and the governing mechanisms remain unclear. Here we report that while the purified SIRPα binds to CD47 and that SIRPα is expressed on monocytes and monocytic THP-1 or U937, these SIRPα are ineffective to mediate cell binding to immobilized CD47. However, cell binding to CD47 is significantly enhanced when monocytes transmigrating across endothelia, or being differentiated into macrophages. Cell surface labeling reveals SIRPα to be diffused on naïve monocytes but highly clustered on transmigrated monocytes and macrophages. Protein crosslink and equilibrium centrifugation confirm that SIRPα in the latter cells forms oligomerized complexes resulting in increased avidity for CD47 binding. Furthermore, formation of SIRPα complexes/clusters requires the plasma membrane ‘lipid rafts’ and the activity of Src family kinase during macrophage differentiation. These results together suggest that ‘clustering’ SIRPα into plasma membrane microdomains is essential for activated monocytes and macrophages to effectively interact with CD47 and initiate intracellular signaling.
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Affiliation(s)
- Binh Ha
- Program of Cellular Biology and Immunology, Center of Inflammation, Immunity and Infection, Georgia State University, Atlanta, Georgia, United States of America
| | - Zhiyuan Lv
- Program of Cellular Biology and Immunology, Center of Inflammation, Immunity and Infection, Georgia State University, Atlanta, Georgia, United States of America
- School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Zhen Bian
- Program of Cellular Biology and Immunology, Center of Inflammation, Immunity and Infection, Georgia State University, Atlanta, Georgia, United States of America
- School of Life Sciences, Nanjing University, Nanjing, Jiangsu, China
| | - Xiugen Zhang
- Program of Cellular Biology and Immunology, Center of Inflammation, Immunity and Infection, Georgia State University, Atlanta, Georgia, United States of America
| | - Aarti Mishra
- Program of Cellular Biology and Immunology, Center of Inflammation, Immunity and Infection, Georgia State University, Atlanta, Georgia, United States of America
| | - Yuan Liu
- Program of Cellular Biology and Immunology, Center of Inflammation, Immunity and Infection, Georgia State University, Atlanta, Georgia, United States of America
- * E-mail:
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14
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Hong Z, Staiculescu MC, Hampel P, Levitan I, Forgacs G. How cholesterol regulates endothelial biomechanics. Front Physiol 2012; 3:426. [PMID: 23162471 PMCID: PMC3498650 DOI: 10.3389/fphys.2012.00426] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Accepted: 10/19/2012] [Indexed: 11/13/2022] Open
Abstract
As endothelial cells form the barrier between blood flow and surrounding tissue, many of their functions depend on mechanical integrity, in particular those of the plasma membrane. As component and organizer of the plasma membrane, cholesterol is a regulator of cellular mechanical properties. Disruption of cholesterol balance leads to impairment of endothelial functions and eventually to disease. The mechanical properties of the membrane are strongly affected by the cytoskeleton. As Phosphatidylinositol-4,5-bisphosphate (PIP2) is a key mediator between the membrane and cytoskeleton, it also affects cellular biomechanical properties. Typically, PIP2 is concentrated in cholesterol-rich microdomains, such as caveolae and lipid rafts, which are particularly abundant in the endothelial plasma membrane. We investigated the connection between cholesterol and PIP2 by extracting membrane tethers from bovine aortic endothelial cells (BAEC) at different cholesterol levels and PIP2 conditions. Our results suggest that in BAEC the role of PIP2, as a mediator of membrane-cytoskeleton adhesion, is regulated by cholesterol. Our findings confirm the specific role of cholesterol in endothelial cells and may have implications for cholesterol-dependent vascular pathologies.
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Affiliation(s)
- Zhongkui Hong
- Department of Physics and Astronomy, University of Missouri-Columbia Columbia, MO, USA
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Enterohemorrhagic Escherichia coli O157:H7 Shiga toxins inhibit gamma interferon-mediated cellular activation. Infect Immun 2012; 80:2307-15. [PMID: 22526675 DOI: 10.1128/iai.00255-12] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) serotype O157:H7 is a food-borne pathogen that causes significant morbidity and mortality in developing and industrialized nations. EHEC infection of host epithelial cells is capable of inhibiting the gamma interferon (IFN-γ) proinflammatory pathway through the inhibition of Stat-1 phosphorylation, which is important for host defense against microbial pathogens. The aim of this study was to determine the bacterial factors involved in the inhibition of Stat-1 tyrosine phosphorylation. Human HEp-2 and Caco-2 epithelial cells were challenged directly with either EHEC or bacterial culture supernatants and stimulated with IFN-γ, and then the protein extracts were analyzed by immunoblotting. The data showed that IFN-γ-mediated Stat-1 tyrosine phosphorylation was inhibited by EHEC secreted proteins. Using two-dimensional difference gel electrophoresis, EHEC Shiga toxins were identified as candidate inhibitory factors. EHEC Shiga toxin mutants were then generated and complemented in trans, and mutant culture supernatant was supplemented with purified Stx to confirm their ability to subvert IFN-γ-mediated cell activation. We conclude that while other factors are likely involved in the suppression of IFN-γ-mediated Stat-1 tyrosine phosphorylation, E. coli-derived Shiga toxins represent a novel mechanism by which EHEC evades the host immune system.
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RNAi screen of Salmonella invasion shows role of COPI in membrane targeting of cholesterol and Cdc42. Mol Syst Biol 2011; 7:474. [PMID: 21407211 PMCID: PMC3094068 DOI: 10.1038/msb.2011.7] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Accepted: 02/03/2011] [Indexed: 01/08/2023] Open
Abstract
A genome wide RNAi screen identifies 72 host cell genes affecting S. Typhimurium entry, including actin regulators and COPI. This study implicates COPI-dependent cholesterol and sphingolipid localization as a common mechanism of infection by bacterial and viral pathogens. Genome-scale RNAi screen identifies 72 host genes affecting S. Typhimurium host cell invasion. Step-specific follow-up assays assign the phenotypes to specific steps of the invasion process. COPI effects on host cell binding, ruffling and invasion were traced to a key role of COPI in membrane targeting of cholesterol, sphingolipids, Rac1 and Cdc42. This new role of COPI explains why COPI is required for host cell infection by numerous bacterial and viral pathogens.
Pathogens are not only a menace to public health, but they also provide excellent tools for probing host cell function. Thus, studying infection mechanisms has fueled progress in cell biology (Ridley et al, 1992; Welch et al, 1997). In the presented study, we have performed an RNAi screen to identify host cell genes required for Salmonella host cell invasion. This screen identified proteins known to contribute to Salmonella-induced actin rearrangements (e.g., Cdc42 and the Arp2/3 complex; reviewed in Schlumberger and Hardt, 2006) and vesicular traffic (e.g., Rab7) as well as unexpected hits, such as the COPI complex. COPI is a known organizer of Golgi-to-ER vesicle transport (Bethune et al, 2006; Beck et al, 2009). Here, we show that COPI is also involved in plasma membrane targeting of cholesterol, sphingolipids and the Rho GTPases Cdc42 and Rac1, essential host cell factors required for Salmonella invasion. This explains why COPI depletion inhibits infection by S. Typhimurium and illustrates how combining bacterial pathogenesis and systems approaches can promote cell biology. Salmonella Typhimurium is a common food-borne pathogen and worldwide a major public health problem causing severe diarrhea. The pathogen uses the host's gut mucosa as a portal of entry and gut tissue invasion is a key event leading to the disease. This explains the intense interest from medicine and basic biology in the mechanism of Salmonella host cell invasion. Tissue culture infection models have delineated a sequence of events leading host cell invasion (Figure 1;Schlumberger and Hardt, 2006): (i) pathogen binding to the host cell surface; (ii) activation of a syringe-like apparatus (‘Type III secretion system 1', T1) of the bacterium and injection of a bacterial toxin cocktail into the host cell. These toxins include SopE, a key virulence factor triggering invasion (Hardt et al, 1998), which was analyzed in our study; (iii) toxin-triggered membrane ruffling. To a significant extent, this is facilitated by SopE-triggered activation of Cdc42 and Rac1 and subsequent actin polymerization at the site of infection; (iv) engulfment of the pathogen within a vesicular compartment (SCV) and (v) maturation of the SCV, a process driven by a second Type III secretion system (T2), which is expressed by the pathogen upon bacterial entry (Figure 1). This sequence of events mediates Salmonella invasion into the gut epithelium and illustrates that this pathogen can be used for probing mechanisms of host cell actin control, membrane biogenesis, vesicle formation and vesicular trafficking. SopE is a key virulence factor of invasion and triggers the activation of Cdc42 and Rac1 and subsequent actin polymerization at the site of infection. We have employed a SopE-expressing S. Typhimurium strain and RNAi screening technology to identify host cell factors affecting invasion. First, we developed an automated fluorescence microscopy assay to quantify S. Typhimurium entry in a high-throughput format (Figure 1C). This assay was based on a GFP reporter expressed by the pathogen after invasion and maturation of the SCV. Using this assay, we screened a ‘druggable genome' siRNA library (6978 genes, 3 oligos each, 1 oligo per well) and identified 72 invasion hits. These included established regulators of the actin cytoskeleton (Cdc42, Arp2/3, Nap1; Schlumberger and Hardt, 2006), some of which have not been implicated so far in Salmonella entry (Pfn1, Cap1), as well as proteins not previously thought to influence infection (Atp1a1, Rbx1, COPI complex). Potentially, these hits could affect any step of the invasion process (Figure 1A). In the second stage of the study, we have assigned each ‘invasion hit' to particular steps of the invasion process. For this purpose, we developed step-specific assays for Salmonella binding, injection, ruffling and membrane engulfment and re-screened the genes found as hits in the first screen (four siRNAs per gene). As expected, a significant number of ‘hits' affected binding to the host cell, others affected binding and ruffling (e.g., Pfn1, Itgβ5, Cap1), a few were specific for the ruffling step (e.g., Cdc42) and some affected SCV maturation, namely Rab7a, the trafficking protein Vps39 and the vacuolar proton pump Atp6ap2. Thus, our experimental strategy allowed mechanistic interpretation and linked novel hits to particular phenotypes, thus providing a basis for further studies (Figure 1). COPI depletion impaired effector injection and ruffling. This was surprising, as the COPI complex was known to regulate retrogade Golgi-to-ER transport, but was not expected to affect pathogen interactions at the plasma membrane. Therefore, we have investigated the underlying mechanism. We have observed that COPI depletion entailed dramatic changes in the plasma membrane composition (Figure 6). Cholesterol and sphingolipids, which form domains (‘lipid rafts') in the plasma membrane, were depleted from the cell surface and redirected into a large vesicular compartment. The same was true for the Rho GTPases Rac1 and Cdc42. This strong decrease in the amount of cholesterol-enriched microdomains and Rho GTPases in the plasma membrane explained the observed defects in S. Typhimurium host cell invasion and assigned a novel role for COPI in controlling mammalian plasma membrane composition. It should be noted that other viral and bacterial pathogens do show a similar dependency on host cellular COPI and plasma membrane lipids. This includes notorious pathogens such as Staphylococcus aureus (Ramet et al, 2002; Potrich et al, 2009), Listeria monocytogenes (Seveau et al, 2004; Agaisse et al, 2005; Cheng et al, 2005; Gekara et al, 2005), Mycobacterium tuberculosis (Munoz et al, 2009), Chlamydia trachomatis (Elwell et al, 2008), influenza virus (Hao et al, 2008; Konig et al, 2010), hepatitis C virus (Tai et al, 2009; Popescu and Dubuisson, 2010) and the vesicular stomatitis virus (presented study) and suggests that COPI-mediated control of host cell plasma membrane composition might be of broad importance for pathogenesis. Future work will have to address whether this might offer starting points for developing anti-infective therapeutics with a very broad spectrum of activity. The pathogen Salmonella Typhimurium is a common cause of diarrhea and invades the gut tissue by injecting a cocktail of virulence factors into epithelial cells, triggering actin rearrangements, membrane ruffling and pathogen entry. One of these factors is SopE, a G-nucleotide exchange factor for the host cellular Rho GTPases Rac1 and Cdc42. How SopE mediates cellular invasion is incompletely understood. Using genome-scale RNAi screening we identified 72 known and novel host cell proteins affecting SopE-mediated entry. Follow-up assays assigned these ‘hits' to particular steps of the invasion process; i.e., binding, effector injection, membrane ruffling, membrane closure and maturation of the Salmonella-containing vacuole. Depletion of the COPI complex revealed a unique effect on virulence factor injection and membrane ruffling. Both effects are attributable to mislocalization of cholesterol, sphingolipids, Rac1 and Cdc42 away from the plasma membrane into a large intracellular compartment. Equivalent results were obtained with the vesicular stomatitis virus. Therefore, COPI-facilitated maintenance of lipids may represent a novel, unifying mechanism essential for a wide range of pathogens, offering opportunities for designing new drugs.
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Dasanayake D, Richaud M, Cyr N, Caballero-Franco C, Pittroff S, Finn RM, Ausió J, Luo W, Donnenberg MS, Jardim A. The N-terminal amphipathic region of the Escherichia coli type III secretion system protein EspD is required for membrane insertion and function. Mol Microbiol 2011; 81:734-50. [PMID: 21651628 DOI: 10.1111/j.1365-2958.2011.07727.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Enterohemorrhagic Escherichia coli is a causative agent of gastrointestinal and diarrheal diseases. These pathogenic E. coli express a syringe-like protein machine, known as the type III secretion system (T3SS), used for the injection of virulence factors into the cytosol of the host epithelial cell. Breaching the epithelial plasma membrane requires formation of a translocation pore that contains the secreted protein EspD. Here we demonstrate that the N-terminal segment of EspD, encompassing residues 1-171, contains two amphipathic domains spanning residues 24-41 and 66-83, with the latter of these helices being critical for EspD function. Fluorescence and circular dichroism analysis revealed that, in solution, His₆-EspD₁₋₁₇₁ adopts a native disordered structure; however, on binding anionic small unilamellar vesicles composed of phosphatidylserine, His₆-EspD₁₋₁₇₁ undergoes a pH depended conformational change that increases the α-helix content of this protein approximately sevenfold. This change coincides with insertion of the region circumscribing Trp₄₇ into the hydrophobic core of the lipid bilayer. On the HeLa cell plasma membrane, His₆-EspD₁₋₁₇₁ forms a homodimer that is postulated to promote EspD-EspD oligomerization and pore formation. Complementation of ΔespD null mutant bacteria with an espDΔ66-83 gene showed that this protein was secreted but non-functional.
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Affiliation(s)
- Dayal Dasanayake
- Institute of Parasitology and Centre for Host-Parasite Interactions, Macdonald Campus of McGill University, Ste-Anne-de-Bellevue, Québec H9X3V9, Canada
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Reis RSD, Horn F. Enteropathogenic Escherichia coli, Samonella, Shigella and Yersinia: cellular aspects of host-bacteria interactions in enteric diseases. Gut Pathog 2010; 2:8. [PMID: 20649986 PMCID: PMC2921366 DOI: 10.1186/1757-4749-2-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Accepted: 07/22/2010] [Indexed: 12/18/2022] Open
Abstract
A successful infection of the human intestine by enteropathogenic bacteria depends on the ability of bacteria to attach and colonize the intestinal epithelium and, in some cases, to invade the host cell, survive intracellularly and disseminate from cell to cell. To accomplish these processes bacteria have evolved an arsenal of molecules that are mostly secreted by dedicated type III secretion systems, and that interact with the host, subverting normal cellular functions. Here we overview the most important molecular strategies developed by enteropathogenic Escherichia coli, Salmonella enterica, Shigella flexneri, and Yersinia enterocolitica to cause enteric infections. Despite having evolved different effectors, these four microorganisms share common host cellular targets.
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Affiliation(s)
- Roberta Souza Dos Reis
- Departamento de Biofísica, Universidade Federal do Rio Grande do Sul, P,O, Box 15005, 91501-970, Porto Alegre, Brazil.
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Shen-Tu G, Schauer DB, Jones NL, Sherman PM. Detergent-resistant microdomains mediate activation of host cell signaling in response to attaching-effacing bacteria. J Transl Med 2010; 90:266-81. [PMID: 19997063 DOI: 10.1038/labinvest.2009.131] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) O157:H7 causes outbreaks of bloody diarrhea and the hemolytic-uremic syndrome. EHEC intimately adheres to epithelial cells, effaces microvilli and induces attaching-effacing (AE) lesions. Detergent-resistant microdomains (lipid rafts) serve as membrane platforms for the recruitment of signaling complexes to mediate host responses to infection. The aim of this study was to define the role of lipid rafts in activating signal transduction pathways in response to AE bacterial pathogens. Epithelial cell monolayers were infected with EHEC (MOI 100:1, 3 h, 37 degrees C) and lipid rafts isolated by buoyant density ultracentrifugation. Phosphoinositide 3-kinase (PI3K) localization to lipid rafts was confirmed using PI3K and anti-caveolin-1 antibodies. Mice with cholesterol storage disease Niemann-Pick, type C were used as in vivo models to confirm the role of lipid rafts in mediating signaling response to AE organisms. In contrast to uninfected cells, PI3K was recruited to lipid rafts in response to EHEC infection. Metabolically active bacteria and cells with intact cholesterol-rich microdomains were necessary for the recruitment of second messengers to lipid rafts. Recruitment of PI3K to lipid rafts was independent of the intimin (eaeA) gene, type III secretion system, and production of Shiga-like toxins. Colonization of NPC(-/-) colonic mucosa by Citrobacter rodentium and AE lesion formation were both delayed, compared with wild-type mice infected with the murine-specific AE bacterial pathogen. C. rodentium-infected NPC(-/-) mice had reduced colonic epithelial hyperplasia (64+/-8.251 vs 112+/-2.958 microm; P<0.05) and decreased secretion of IFN-gamma (17.6+/-17.6 vs 71+/-26.3 pg/ml, P<0.001). Lipid rafts mediate host cell signal transduction responses to AE bacterial infections both in vitro and in vivo. These findings advance the current understanding of microbial-eukaryotic cell interactions in response to enteric pathogens that hijack signaling responses mediated through lipid rafts.
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Affiliation(s)
- Grace Shen-Tu
- Research Institute, Hospital for Sick Children, University of Toronto, Toronto, ON, Canada
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20
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Bridge DR, Novotny MJ, Moore ER, Olson JC. Role of host cell polarity and leading edge properties in Pseudomonas type III secretion. MICROBIOLOGY-SGM 2009; 156:356-373. [PMID: 19910414 DOI: 10.1099/mic.0.033241-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Type III secretion (T3S) functions in establishing infections in a large number of Gram-negative bacteria, yet little is known about how host cell properties might function in this process. We used the opportunistic pathogen Pseudomonas aeruginosa and the ability to alter host cell sensitivity to Pseudomonas T3S to explore this problem. HT-29 epithelial cells were used to study cellular changes associated with loss of T3S sensitivity, which could be induced by treatment with methyl-beta-cyclodextrin or perfringolysin O. HL-60 promyelocytic cells are innately resistant to Pseudomonas T3S and were used to study cellular changes occurring in response to induction of T3S sensitivity, which occurred following treatment with phorbol esters. Using both cell models, a positive correlation was observed between eukaryotic cell adherence to tissue culture wells and T3S sensitivity. In examining the type of adhesion process linked to T3S sensitivity in HT-29 cells, a hierarchical order of protein involvement was identified that paralleled the architecture of leading edge (LE) focal complexes. Conversely, in HL-60 cells, induction of T3S sensitivity coincided with the onset of LE properties and the development of actin-rich projections associated with polarized cell migration. When LE architecture was examined by immunofluorescent staining for actin, Rac1, IQ-motif-containing GTPase-activating protein 1 (IQGAP1) and phosphatidylinositol 3 kinase (PI3 kinase), intact LE structure was found to closely correlate with host cell sensitivity to P. aeruginosa T3S. Our model for host cell involvement in Pseudomonas T3S proposes that cortical actin polymerization at the LE alters membrane properties to favour T3S translocon function and the establishment of infections, which is consistent with Pseudomonas infections targeting wounded epithelial barriers undergoing cell migration.
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Affiliation(s)
- Dacie R Bridge
- Department of Microbiology, Immunology, and Cell Biology, West Virginia University Health Sciences Center, Morgantown, WV 26506-9177, USA
| | - Matthew J Novotny
- Department of Microbiology, Immunology, and Cell Biology, West Virginia University Health Sciences Center, Morgantown, WV 26506-9177, USA
| | - Elizabeth R Moore
- Laboratory of Intracellular Parasites, NIAID, Rocky Mountain Laboratories, Hamilton, MT 59840, USA
| | - Joan C Olson
- Department of Microbiology, Immunology, and Cell Biology, West Virginia University Health Sciences Center, Morgantown, WV 26506-9177, USA
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French CT, Panina EM, Yeh SH, Griffith N, Arambula DG, Miller JF. The Bordetella type III secretion system effector BteA contains a conserved N-terminal motif that guides bacterial virulence factors to lipid rafts. Cell Microbiol 2009; 11:1735-49. [PMID: 19650828 PMCID: PMC2788067 DOI: 10.1111/j.1462-5822.2009.01361.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Bordetella type III secretion system (T3SS) effector protein BteA is necessary and sufficient for rapid cytotoxicity in a wide range of mammalian cells. We show that BteA is highly conserved and functionally interchangeable between Bordetella bronchiseptica, Bordetella pertussis and Bordetella parapertussis. The identification of BteA sequences required for cytotoxicity allowed the construction of non-cytotoxic mutants for localization studies. BteA derivatives were targeted to lipid rafts and showed clear colocalization with cortical actin, ezrin and the lipid raft marker GM1. We hypothesized that BteA associates with the cytoplasmic face of lipid rafts to locally modulate host cell responses to Bordetella attachment. B. bronchiseptica adhered to host cells almost exclusively to GM1-enriched lipid raft microdomains and BteA colocalized to these same sites following T3SS-mediated translocation. Disruption of lipid rafts with methyl-beta-cyclodextrin protected cells from T3SS-induced cytotoxicity. Localization to lipid rafts was mediated by a 130-amino-acid lipid raft targeting domain at the N-terminus of BteA, and homologous domains were identified in virulence factors from other bacterial species. Lipid raft targeting sequences from a T3SS effector (Plu4750) and an RTX-type toxin (Plu3217) from Photorhabdus luminescens directed fusion proteins to lipid rafts in a manner identical to the N-terminus of BteA.
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Affiliation(s)
- Christopher T French
- Department of Microbiology, Immunology and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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Sason H, Milgrom M, Weiss AM, Melamed-Book N, Balla T, Grinstein S, Backert S, Rosenshine I, Aroeti B. Enteropathogenic Escherichia coli subverts phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate upon epithelial cell infection. Mol Biol Cell 2008; 20:544-55. [PMID: 18987340 DOI: 10.1091/mbc.e08-05-0516] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Phosphatidylinositol 4,5-bisphosphate [PI(4,5)P(2)] and phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P(3)] are phosphoinositides (PIs) present in small amounts in the inner leaflet of the plasma membrane (PM) lipid bilayer of host target cells. They are thought to modulate the activity of proteins involved in enteropathogenic Escherichia coli (EPEC) infection. However, the role of PI(4,5)P(2) and PI(3,4,5)P(3) in EPEC pathogenesis remains obscure. Here we show that EPEC induces a transient PI(4,5)P(2) accumulation at bacterial infection sites. Simultaneous actin accumulation, likely involved in the construction of the actin-rich pedestal, is also observed at these sites. Acute PI(4,5)P(2) depletion partially diminishes EPEC adherence to the cell surface and actin pedestal formation. These findings are consistent with a bimodal role, whereby PI(4,5)P(2) contributes to EPEC association with the cell surface and to the maximal induction of actin pedestals. Finally, we show that EPEC induces PI(3,4,5)P(3) clustering at bacterial infection sites, in a translocated intimin receptor (Tir)-dependent manner. Tir phosphorylated on tyrosine 454, but not on tyrosine 474, forms complexes with an active phosphatidylinositol 3-kinase (PI3K), suggesting that PI3K recruited by Tir prompts the production of PI(3,4,5)P(3) beneath EPEC attachment sites. The functional significance of this event may be related to the ability of EPEC to modulate cell death and innate immunity.
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Affiliation(s)
- Hagit Sason
- Department of Cell and Animal Biology, Confocal Unit, Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
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Wang M, Hajishengallis G. Lipid raft-dependent uptake, signalling and intracellular fate of Porphyromonas gingivalis in mouse macrophages. Cell Microbiol 2008; 10:2029-42. [PMID: 18547335 DOI: 10.1111/j.1462-5822.2008.01185.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Lipid rafts are cholesterol-enriched microdomains involved in cellular trafficking and implicated as portals for certain pathogens. We sought to determine whether the oral pathogen Porphyromonas gingivalis enters macrophages via lipid rafts, and if so, to examine the impact of raft entry on its intracellular fate. Using J774A.1 mouse macrophages, we found that P. gingivalis colocalizes with lipid rafts in a cholesterol-dependent way. Depletion of cellular cholesterol using methyl-beta-cyclodextrin resulted in about 50% inhibition of P. gingivalis uptake, although this effect was reversed by cholesterol reconstitution. The intracellular survival of P. gingivalis was dramatically inhibited in cholesterol-depleted cells relative to untreated or cholesterol-reconstituted cells, even when infections were adjusted to allow equilibration of the initial intracellular bacterial load. P. gingivalis thus appeared to exploit raft-mediated uptake for promoting its survival. Consistent with this, lipid raft disruption enhanced the colocalization of internalized P. gingivalis with lysosomes. In contrast, raft disruption did not affect the expression of host receptors interacting with P. gingivalis, although it significantly inhibited signal transduction. In summary, P. gingivalis uses macrophage lipid rafts as signalling and entry platforms, which determine its intracellular fate to the pathogen's own advantage.
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Affiliation(s)
- Min Wang
- Department of Periodontics/Oral Health and Systemic Disease, University of Louisville Health Sciences Center, Louisville, KY 40292, USA
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Hugo A, Kakisu E, De Antoni G, Pérez P. Lactobacilli antagonize biological effects of enterohaemorrhagic Escherichia coli in vitro. Lett Appl Microbiol 2008; 46:613-9. [DOI: 10.1111/j.1472-765x.2008.02363.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Schmitt HP. Profiling the culprit in Alzheimer's disease (AD): bacterial toxic proteins - Will they be significant for the aetio-pathogenesis of AD and the transmissible spongiform encephalopathies? Med Hypotheses 2007; 69:596-609. [PMID: 17337124 DOI: 10.1016/j.mehy.2007.01.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2006] [Accepted: 01/02/2007] [Indexed: 11/25/2022]
Abstract
The aetiology of Alzheimer's disease (AD) and the transmissible spongiform encephalopathies (tSEs) is still elusive. The concept that prion protein (PrP(Sc)) is the aetiological agent (infectious protein) in the tSEs has recently been questioned. In AD, the cause of the aberrant cleavage of the beta-amyloid precursor protein (APP), resulting in the production of amyloidogenic Abeta fragments, has yet remained obscure. Moreover, the amyloid hypothesis of AD has been seriously challenged. In both AD and the tSEs, pathogens of various nature, including bacteria, have been discussed as possible causal factors. However, aetiological considerations have completely neglected microbial products such as the bacterial toxic proteins (BTPs). The present paper is aimed at drawing a "culprit profile" of these toxic molecules that can exert, at low-dosage, neuro-degeneration through various effects. Clearly, BTPs may affect cell-surface receptors including modulatory amine transmitter receptor expression, block neuro-transmitter release, increase intra-cellular Ca(2+) levels, affect intra-cellular signal transduction, change cyto-skeletal processing, alter synaptic transmission, influence APP proteolysis, interact with cell surface proteins like PrP(C) or their GPI anchors, act as chaperones inducing conformational change in proteins (e.g., PrP(C) to PrP(Sc)), alter lipid membrane integrity by affecting phospholipases or forming pores and channels, induce vacuolar (spongiform) change and elicit inflammatory reactions with cytokine production including cytokines that were demonstrated in the AD brain. Like PrP(Sc), BTPs can be heat-stable and acid-resistant. BTPs can meet the key-proteins of AD and tSEs in the lipid-rich domains of the plasma membrane called rafts. Basically, this might enable them to initiate a large variety of unfavourable molecular events, eventually resulting in pathogenetic cascades as in AD and the tSEs. All in all, their profile lends support to the hypothesis that BTPs might represent relevant culprits capable to cue and/or promote neuro-degeneration in both AD and the tSEs.
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Affiliation(s)
- H Peter Schmitt
- Institute of Pathology, Department for Neuropathology, University of Heidelberg, Germany.
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Chen ML, Ge Z, Fox JG, Schauer DB. Disruption of tight junctions and induction of proinflammatory cytokine responses in colonic epithelial cells by Campylobacter jejuni. Infect Immun 2006; 74:6581-9. [PMID: 17015453 PMCID: PMC1698078 DOI: 10.1128/iai.00958-06] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Campylobacter jejuni is a leading cause of human enterocolitis and is associated with postinfectious complications, including irritable bowel syndrome and Guillain-Barré syndrome. However, the pathogenesis of C. jejuni infection remains poorly understood. Paracellular pathways in intestinal epithelial cells are gated by intercellular junctions (tight junctions and adherens junctions), providing a functional barrier between luminal microbes and host immune cells in the lamina propria. Here we describe alterations in tight junctions in intestinal epithelial monolayers following C. jejuni infection. Apical infection of polarized T84 monolayers caused a time-dependent decrease in transepithelial electrical resistance (TER). Immunofluorescence microscopy revealed a redistribution of the tight junctional transmembrane protein occludin from an intercellular to an intracellular location. Subcellular fractionation using equilibrium sucrose density gradients demonstrated decreased hyperphosphorylated occludin in lipid rafts, Triton X-100-soluble fractions, and the Triton X-100-insoluble pellet following apical infection. Apical infection with C. jejuni also caused rapid activation of NF-kappaB and AP-1, phosphorylation of extracellular signal-regulated kinase, Jun N-terminal protein kinase, and p38 mitogen-activated protein kinases, and basolateral secretion of the CXC chemokine interleukin-8 (IL-8). Basolateral infection with C. jejuni caused a more rapid decrease in TER, comparable redistribution of tight-junction proteins, and secretion of more IL-8 than that seen with apical infection. These results suggest that compromised barrier function and increased chemokine expression contribute to the pathogenesis of C. jejuni-induced enterocolitis.
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Affiliation(s)
- Ming L Chen
- Division of Comparative Medicine, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Bldg. 56-787, Cambridge, MA 02139, USA.
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Allen-Vercoe E, Waddell B, Toh MCW, DeVinney R. Amino acid residues within enterohemorrhagic Escherichia coli O157:H7 Tir involved in phosphorylation, alpha-actinin recruitment, and Nck-independent pedestal formation. Infect Immun 2006; 74:6196-205. [PMID: 16954405 PMCID: PMC1695534 DOI: 10.1128/iai.00753-06] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) O157:H7 and enteropathogenic E. coli (EPEC) adherence to epithelial cells results in the formation of actin pedestals. Pedestal formation requires the bacterial protein Tir, which is inserted into the epithelial cell plasma membrane by the type III secretion system. EPEC and EHEC use different Tir-based mechanisms for pedestal formation, and the EPEC Tir residues required have been well described. In contrast, little is known about the regions of EHEC O157:H7 Tir that are essential for pedestal formation. Additionally, EHEC O157:H7 Tir is serine/threonine phosphorylated, although the residues involved and their role in pedestal formation are not known. In this study, we describe two regions within the carboxy terminus of EHEC O157:H7 Tir that are required for phosphorylation and pedestal formation. Serines 436 and 437 are substrates for protein kinase A phosphorylation, although this is not required to form pedestals. Using a series of internal deletion mutants, we found that amino acids 454 to 463 are required for efficient pedestal formation. Deleting this region resulted in a significant decrease in the recruitment of both filamentous actin and the actin binding protein alpha-actinin. As alpha-actinin binds directly to the EHEC O157:H7 amino terminus, these data suggest that its recruitment is dependent on pedestal formation.
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Affiliation(s)
- Emma Allen-Vercoe
- Department of Microbiology and Infectious Diseases, University of Calgary Health Sciences Centre, 3330 Hospital Dr. NW, Calgary, AB T2N 4N1, Canada
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Johnson-Henry KC, Hagen KE, Gordonpour M, Tompkins TA, Sherman PM. Surface-layer protein extracts from Lactobacillus helveticus inhibit enterohaemorrhagic Escherichia coli O157:H7 adhesion to epithelial cells. Cell Microbiol 2006; 9:356-67. [PMID: 16925785 DOI: 10.1111/j.1462-5822.2006.00791.x] [Citation(s) in RCA: 173] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Adherence of intestinal pathogens, including Escherichia coli O157:H7, to human intestinal epithelial cells is a key step in pathogenesis. Probiotic bacteria, including Lactobacillus helveticus R0052 inhibit the adhesion of E. coli O157:H7 to epithelial cells, a process which may be related to specific components of the bacterial surface. Surface-layer proteins (Slps) are located in a paracrystalline layer outside the bacterial cell wall and are thought to play a role in tissue adherence. However, the ability of S-layer protein extract derived from probiotic bacteria to block adherence of enteric pathogens has not been investigated. Human epithelial (HEp-2 and T84) cells were treated with S-layer protein extract alone, infected with E. coli O157:H7, or pretreated with S-layer protein extract prior to infection to determine their importance in the inhibition of pathogen adherence. The effects of S-layer protein extracts were characterized by phase-contrast and immunofluorescence microscopy and measurement of the transepithelial electrical resistance of polarized monolayers. Pre-treatment of host epithelial cells with S-layer protein extracts prior to E. coli O157:H7 infection decreased pathogen adherence and attaching-effacing lesions in addition to preserving the barrier function of monolayers. These in vitro studies indicate that a non-viable constituent derived from a probiotic strain may prove effective in interrupting the infectious process of an intestinal pathogen.
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Jandu N, Ceponis PJM, Kato S, Riff JD, McKay DM, Sherman PM. Conditioned medium from enterohemorrhagic Escherichia coli-infected T84 cells inhibits signal transducer and activator of transcription 1 activation by gamma interferon. Infect Immun 2006; 74:1809-18. [PMID: 16495555 PMCID: PMC1418659 DOI: 10.1128/iai.74.3.1809-1818.2006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gamma interferon (IFN-gamma) is a cytokine important to host defense which can signal through signal transducer and activator of transcription 1 (Stat1). Enterohemorrhagic Escherichia coli (EHEC) modulates host cell signal transduction to establish infection, and EHEC serotypes O113:H21 and O157:H7 both inhibit IFN-gamma-induced Stat1 tyrosine phosphorylation in vitro. The aim of this study was to delineate both bacterial and host cell factors involved in the inhibition of Stat1 tyrosine phosphorylation. Human T84 colonic epithelial cells were challenged with direct infection, viable EHEC separated from T84 cells by a filter, sodium orthovanadate, isolated flagellin, bacterial culture supernatants, and conditioned medium treated with proteinase K, trypsin, or heat inactivation. Epithelial cells were then stimulated with IFN-gamma and protein extracts were analyzed by immunoblotting. The data showed that IFN-gamma-inducible Stat1 tyrosine phosphorylation was inhibited when EHEC adhered to T84 cells, but not by bacterial culture supernatants or bacteria separated from the epithelial monolayer. Conditioned medium from T84 cells infected with EHEC O157:H7 suppressed Stat1 activation, and this was not reversed by treatment with proteinases or heat inactivation. Use of pharmacological inhibitors showed that time-dependent bacterial, but not epithelial, protein synthesis was involved. Stat1 inhibition was also independent of bacterial flagellin, host proteasome activity, and protein tyrosine phosphatases. Infection led to altered IFN-gamma receptor domain 1 subcellular distribution and decreased expression in cholesterol-enriched membrane microdomains. Thus, suppression of host cell IFN-gamma signaling by production of a contact-dependent, soluble EHEC factor may represent a novel mechanism for this pathogen to evade the host immune system.
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Affiliation(s)
- Narveen Jandu
- Research Institute, Gastroenterology and Nutrition Room 8409, Hospital for Sick Children, 555 University Ave., Toronto, Ontario, Canada M5G 1X8
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