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Anandachar MS, Roy S, Sinha S, Boadi A, Katkar GD, Ghosh P. Diverse gut pathogens exploit the host engulfment pathway via a conserved mechanism. J Biol Chem 2023; 299:105390. [PMID: 37890785 PMCID: PMC10696401 DOI: 10.1016/j.jbc.2023.105390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 09/22/2023] [Accepted: 10/15/2023] [Indexed: 10/29/2023] Open
Abstract
Macrophages clear infections by engulfing and digesting pathogens within phagolysosomes. Pathogens escape this fate by engaging in a molecular arms race; they use WxxxE motif-containing "effector" proteins to subvert the host cells they invade and seek refuge within protective vacuoles. Here, we define the host component of the molecular arms race as an evolutionarily conserved polar "hot spot" on the PH domain of ELMO1 (Engulfment and Cell Motility protein 1), which is targeted by diverse WxxxE effectors. Using homology modeling and site-directed mutagenesis, we show that a lysine triad within the "patch" directly binds all WxxxE effectors tested: SifA (Salmonella), IpgB1 and IpgB2 (Shigella), and Map (enteropathogenic Escherichia coli). Using an integrated SifA-host protein-protein interaction network, in silico network perturbation, and functional studies, we show that the major consequences of preventing SifA-ELMO1 interaction are reduced Rac1 activity and microbial invasion. That multiple effectors of diverse structure, function, and sequence bind the same hot spot on ELMO1 suggests that the WxxxE effector(s)-ELMO1 interface is a convergence point of intrusion detection and/or host vulnerability. We conclude that the interface may represent the fault line in coevolved molecular adaptations between pathogens and the host, and its disruption may serve as a therapeutic strategy.
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Affiliation(s)
- Mahitha Shree Anandachar
- Department of Cellular and Molecular Medicine, University of California San Diego, San Diego, California, USA; Department of Pathology, University of California San Diego, San Diego, California, USA
| | - Suchismita Roy
- Department of Cellular and Molecular Medicine, University of California San Diego, San Diego, California, USA
| | - Saptarshi Sinha
- Department of Cellular and Molecular Medicine, University of California San Diego, San Diego, California, USA
| | - Agyekum Boadi
- Department of Cellular and Molecular Medicine, University of California San Diego, San Diego, California, USA
| | - Gajanan D Katkar
- Department of Cellular and Molecular Medicine, University of California San Diego, San Diego, California, USA.
| | - Pradipta Ghosh
- Department of Cellular and Molecular Medicine, University of California San Diego, San Diego, California, USA; Department of Medicine, University of California San Diego, San Diego, California, USA.
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2
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Anandachar MS, Roy S, Sinha S, Agyekum B, Ibeawuchi SR, Gementera H, Amamoto A, Katkar GD, Ghosh P. Diverse Gut Pathogens Exploit the Host Engulfment Pathway via a Conserved Mechanism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.09.536168. [PMID: 37066267 PMCID: PMC10104235 DOI: 10.1101/2023.04.09.536168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
Macrophages clear infections by engulfing and digesting pathogens within phagolysosomes. Pathogens escape this fate by engaging in a molecular arms race; they use WxxxE motif-containing effector proteins to subvert the host cells they invade and seek refuge within protective vacuoles. Here we define the host component of the molecular arms race as an evolutionarily conserved polar hotspot on the PH-domain of ELMO1 (Engulfment and Cell Motility1), which is targeted by diverse WxxxE-effectors. Using homology modeling and site-directed mutagenesis, we show that a lysine triad within the patch directly binds all WxxxE-effectors tested: SifA (Salmonella), IpgB1 and IpgB2 (Shigella), and Map (enteropathogenic E. coli). Using an integrated SifA-host protein-protein interaction (PPI) network, in-silico network perturbation, and functional studies we show that the major consequences of preventing SifA-ELMO1 interaction are reduced Rac1 activity and microbial invasion. That multiple effectors of diverse structure, function, and sequence bind the same hotpot on ELMO1 suggests that the WxxxE-effector(s)-ELMO1 interface is a convergence point of intrusion detection and/or host vulnerability. We conclude that the interface may represent the fault line in co-evolved molecular adaptations between pathogens and the host and its disruption may serve as a therapeutic strategy.
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3
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Bei J, Qiu Y, Cockrell D, Chang Q, Husseinzadeh S, Zhou C, Fang X, Bao X, Jin Y, Gaitas A, Khanipov K, Saito TB, Gong B. Identification of common sequence motifs shared exclusively among selectively packed exosomal pathogenic microRNAs during rickettsial infections. J Cell Physiol 2023; 238:1937-1948. [PMID: 37334929 DOI: 10.1002/jcp.31061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 05/12/2023] [Accepted: 05/22/2023] [Indexed: 06/21/2023]
Abstract
We previously reported that microRNA (miR)23a and miR30b are selectively sorted into exosomes derived from rickettsia-infected endothelial cells (R-ECExos). Yet, the mechanism remains unknown. Cases of spotted fever rickettsioses have been increasing, and infections with these bacteria cause life-threatening diseases by targeting brain and lung tissues. Therefore, the goal of the present study is to further dissect the molecular mechanism underlying R-ECExos-induced barrier dysfunction of normal recipient microvascular endothelial cells (MECs), depending on their exosomal RNA cargos. Infected ticks transmit the rickettsiae to human hosts following a bite and injections of the bacteria into the skin. In the present study, we demonstrate that treatment with R-ECExos, which were derived from spotted fever group R parkeri infected human dermal MECs, induced disruptions of the paracellular adherens junctional protein VE-cadherin, and breached the paracellular barrier function in recipient pulmonary MECs (PMECs) in an exosomal RNA-dependent manner. We did not detect different levels of miRs in parent dermal MECs following rickettsial infections. However, we demonstrated that the microvasculopathy-relevant miR23a-27a-24 cluster and miR30b are selectively enriched in R-ECExos. Bioinformatic analysis revealed that common sequence motifs are shared exclusively among the exosomal, selectively-enriched miR23a cluster and miR30b at different levels. Taken together, these data warrant further functional identification and characterization of a monopartition, bipartition, or tripartition among ACA, UCA, and CAG motifs that guide recognition of microvasculopathy-relevant miR23a-27a-24 and miR30b, and subsequently results in their selective enrichments in R-ECExos.
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Affiliation(s)
- Jiani Bei
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Yuan Qiu
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Diane Cockrell
- Laboratory of Bacteriology, Division of Intramural Research, NIAID-NIH, Hamilton, Montana, USA
| | - Qing Chang
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Sorosh Husseinzadeh
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Changcheng Zhou
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Xiang Fang
- Department of Neurology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Xiaoyong Bao
- Department of Pediatric, University of Texas Medical Branch, Galveston, Texas, USA
| | - Yang Jin
- Department of Medicine, Pulmonary and Critical Care Medicine Division, Boston University Medical Campus, Boston, Massachusetts, USA
| | - Angelo Gaitas
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Kamil Khanipov
- Department of Pharmacology, University of Texas Medical Branch, Galveston, Texas, USA
| | - Tais B Saito
- Laboratory of Bacteriology, Division of Intramural Research, NIAID-NIH, Hamilton, Montana, USA
| | - Bin Gong
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, USA
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4
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Achi SC, Karimilangi S, Lie D, Sayed IM, Das S. The WxxxE proteins in microbial pathogenesis. Crit Rev Microbiol 2023; 49:197-213. [PMID: 35287539 PMCID: PMC9737147 DOI: 10.1080/1040841x.2022.2046546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 02/10/2022] [Accepted: 02/19/2022] [Indexed: 12/14/2022]
Abstract
Effector proteins secreted by pathogens modulate various host cellular processes and help in bacterial pathogenesis. Some of these proteins, injected by enteric pathogens via Type Three Secretion System (T3SS) were grouped together based on a conserved signature motif (WxxxE) present in them. The presence of WxxxE motif is not limited to effectors released by enteric pathogens or the T3SS but has been detected in non-enteric pathogens, plant pathogens and in association with Type II and Type IV secretion systems. WxxxE effectors are involved in actin organization, inflammation regulation, vacuole or tubule formation, endolysosomal signalling regulation, tight junction disruption, and apoptosis. The WxxxE sequence has also been identified in TIR [Toll/interleukin-1 (IL-1) receptor] domains of bacteria and host. In the present review, we have focussed on the established and predicted functions of WxxxE effectors secreted by several pathogens, including enteric, non-enteric, and plant pathogens.
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Affiliation(s)
| | - Sareh Karimilangi
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Dominique Lie
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Ibrahim M. Sayed
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Soumita Das
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
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5
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Bei J, Qiu Y, Cockrell D, Chang Q, Husseinzadeh S, Zhou C, Gaitas A, Fang X, Jin Y, Khanipov K, Saito TB, Gong B. Identification of common sequence motifs shared exclusively among selectively packed exosomal pathogenic microRNAs during rickettsial infections. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.06.522907. [PMID: 36712112 PMCID: PMC9881928 DOI: 10.1101/2023.01.06.522907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
We previously reported that microRNA (miR)23a and miR30b are selectively sorted into rickettsia-infected, endothelial cell-derived exosomes ( R -ECExos). Yet, the mechanism remains unknown. The number of cases of spotted fever rickettsioses has been increasing in recent years, and infections with these bacteria cause life-threatening diseases by targeting brain and lung tissues. Therefore, the aim of the present study is to continue to dissect the molecular mechanism underlying R -ECExos-induced barrier dysfunction of normal recipient microvascular endothelial cells (MECs), depending on their exosomal RNA cargos. Rickettsiae are transmitted to human hosts by the bite of an infected tick into the skin. In the present study we demonstrate that treatment with R -ECExos, which were derived from spotted fever group R parkeri infected human dermal MECs, induced disruptions of the paracellular adherens junctional protein VE-cadherin and breached the paracellular barrier function in recipient pulmonary MECs (PMECs) in an exosomal RNA-dependent manner. Similarly, we did not detect different levels of miRs in parent dermal MECs following rickettsial infections. However, we demonstrated that the microvasculopathy-relevant miR23a-27a-24 cluster and miR30b are selectively enriched in R -ECExos. Bioinformatic analysis revealed that common sequence motifs are shared exclusively among the exosomal, selectively-enriched miR23a cluster and miR30b at different levels. Taken together, these data warrant further functional identification and characterization of a single, bipartition, or tripartition among ACA, UCA, and CAG motifs that guide recognition of microvasculopathy-relevant miR23a-27a-24 and miR30b, and subsequently results in their selective enrichments in R -ECExos.
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Yu H, He J, Su G, Wang Y, Fang F, Yang W, Gu K, Fu N, Wang Y, Shen Y, Liu X. Fluid shear stress activates YAP to promote epithelial-mesenchymal transition in hepatocellular carcinoma. Mol Oncol 2021; 15:3164-3183. [PMID: 34260811 PMCID: PMC8564657 DOI: 10.1002/1878-0261.13061] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 06/22/2021] [Accepted: 07/13/2021] [Indexed: 02/05/2023] Open
Abstract
Epithelial-mesenchymal transition (EMT) mediated by fluid shear stress (FSS) in the tumor microenvironment plays an important role in driving metastasis of the malignant tumor. As a mechanotransducer, Yes-associated protein (YAP) is known to translocate into the nucleus to initiate transcription of genes involved in cell proliferation upon extracellular biophysical stimuli. Here, we showed that FSS facilitated cytoskeleton rearrangement in hepatocellular carcinoma cells, which led to the release of YAP from its binding partner, integrin β subunit, in the cytomembrane. Moreover, we found that upregulation of guanine nucleotide exchange factor (GEF)-H1, a microtubule-associated Rho GEF, is a critical step in the FSS-induced translocation of YAP. Nuclear YAP activated the expression of the EMT-regulating transcription factor SNAI1, but suppressed the expression of N6-methyladenosine (m6 A) modulators; together, this promoted the expression of EMT-related genes. We also observed that FSS-treated HepG2 cells showed markedly increased tumorigenesis and metastasis in vivo. Collectively, our findings unravel the underlying molecular processes by which FSS induces translocation of YAP from the cytomembrane to the nucleus, contributes to EMT and enhances metastasis in hepatocellular carcinoma.
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Affiliation(s)
- Hongchi Yu
- Institute of Biomedical EngineeringWest China School of Basic Medical Sciences & Forensic MedicineSichuan UniversityChengduChina
- National Engineering Research Center for BiomaterialsChengduChina
| | - Jia He
- Institute of Biomedical EngineeringWest China School of Basic Medical Sciences & Forensic MedicineSichuan UniversityChengduChina
| | - Guanyue Su
- Institute of Biomedical EngineeringWest China School of Basic Medical Sciences & Forensic MedicineSichuan UniversityChengduChina
| | - Yuelong Wang
- West China HospitalSichuan UniversityChengduChina
| | - Fei Fang
- Institute of Biomedical EngineeringWest China School of Basic Medical Sciences & Forensic MedicineSichuan UniversityChengduChina
| | - Wenxing Yang
- Department of PhysiologyWest China School of Basic Medical Sciences & Forensic MedicineSichuan UniversityChengduChina
| | - Kaiyun Gu
- National Clinical Research Center for Child HealthZhejiang UniversityHangzhouChina
| | - Naiyang Fu
- Cancer and Stem Cell Biology ProgramDuke‐NUS Medical SchoolSingapore
| | - Yunbing Wang
- National Engineering Research Center for BiomaterialsChengduChina
| | - Yang Shen
- Institute of Biomedical EngineeringWest China School of Basic Medical Sciences & Forensic MedicineSichuan UniversityChengduChina
| | - Xiaoheng Liu
- Institute of Biomedical EngineeringWest China School of Basic Medical Sciences & Forensic MedicineSichuan UniversityChengduChina
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7
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Abstract
Spotted fever group rickettsioses (SFRs) are devastating human infections. Vascular endothelial cells (ECs) are the primary targets of rickettsial infection. Edema resulting from EC barrier dysfunction occurs in the brain and lungs in most cases of lethal SFR, but the underlying mechanisms remain unclear. The aim of the study was to explore the potential role of Rickettsia-infected, EC-derived exosomes (Exos) during infection. Using size exclusion chromatography (SEC), we purified Exos from conditioned, filtered, bacterium-free media collected from Rickettsia parkeri-infected human umbilical vein ECs (HUVECs) (R-ECExos) and plasma of Rickettsia australis- or R. parkeri-infected mice (R-plsExos). We observed that rickettsial infection increased the release of heterogeneous plsExos, but endothelial exosomal size, morphology, and production were not significantly altered following infection. Compared to normal plsExos and ECExos, both R-plsExos and R-ECExos induced dysfunction of recipient normal brain microvascular ECs (BMECs). The effect of R-plsExos on mouse recipient BMEC barrier function is dose dependent. The effect of R-ECExos on human recipient BMEC barrier function is dependent on the exosomal RNA cargo. Next-generation sequencing analysis and stem-loop quantitative reverse transcription-PCR (RT-qPCR) validation revealed that rickettsial infection triggered the selective enrichment of endothelial exosomal mir-23a and mir-30b, which potentially target the endothelial barrier. To our knowledge, this is the first report on the functional role of extracellular vesicles following infection by obligately intracellular bacteria.
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8
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Kassa EG, Zlotkin-Rivkin E, Friedman G, Ramachandran RP, Melamed-Book N, Weiss AM, Belenky M, Reichmann D, Breuer W, Pal RR, Rosenshine I, Lapierre LA, Goldenring JR, Aroeti B. Enteropathogenic Escherichia coli remodels host endosomes to promote endocytic turnover and breakdown of surface polarity. PLoS Pathog 2019; 15:e1007851. [PMID: 31242273 PMCID: PMC6615643 DOI: 10.1371/journal.ppat.1007851] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Revised: 07/09/2019] [Accepted: 05/20/2019] [Indexed: 12/11/2022] Open
Abstract
Enteropathogenic E. coli (EPEC) is an extracellular diarrheagenic human pathogen which infects the apical plasma membrane of the small intestinal enterocytes. EPEC utilizes a type III secretion system to translocate bacterial effector proteins into its epithelial hosts. This activity, which subverts numerous signaling and membrane trafficking pathways in the infected cells, is thought to contribute to pathogen virulence. The molecular and cellular mechanisms underlying these events are not well understood. We investigated the mode by which EPEC effectors hijack endosomes to modulate endocytosis, recycling and transcytosis in epithelial host cells. To this end, we developed a flow cytometry-based assay and imaging techniques to track endosomal dynamics and membrane cargo trafficking in the infected cells. We show that type-III secreted components prompt the recruitment of clathrin (clathrin and AP2), early (Rab5a and EEA1) and recycling (Rab4a, Rab11a, Rab11b, FIP2, Myo5b) endocytic machineries to peripheral plasma membrane infection sites. Protein cargoes, e.g. transferrin receptors, β1 integrins and aquaporins, which exploit the endocytic pathways mediated by these machineries, were also found to be recruited to these sites. Moreover, the endosomes and cargo recruitment to infection sites correlated with an increase in cargo endocytic turnover (i.e. endocytosis and recycling) and transcytosis to the infected plasma membrane. The hijacking of endosomes and associated endocytic activities depended on the translocated EspF and Map effectors in non-polarized epithelial cells, and mostly on EspF in polarized epithelial cells. These data suggest a model whereby EPEC effectors hijack endosomal recycling mechanisms to mislocalize and concentrate host plasma membrane proteins in endosomes and in the apically infected plasma membrane. We hypothesize that these activities contribute to bacterial colonization and virulence. Enteropathogenic Escherichia coli (EPEC) are pathogenic bacteria that cause infantile diarrhea. Upon ingestion, EPEC reaches the small intestine, where an injection device termed the type III secretion system is utilized to inject a set of effector proteins from the bacteria into the host cell. These proteins manipulate the localization and functions of host proteins, lipids and organelles and contribute to the emergence of the EPEC disease. The molecular mechanisms underlying the functions of the EPEC effector proteins are not completely understood. Here we show that early upon infection, two such effector proteins, EspF and Map, hijack host endosomes at bacterial adherence sites to facilitate endocytosis and recycling of plasma membrane proteins at these sites. The consequence of this event is the enrichment and mislocalization of host plasma membrane proteins at infection sites. One such protein is the transferrin receptor, which is a carrier for transferrin, whose function is to mediate cellular uptake of iron. Iron is a critical nutrient for bacterial growth and survival. We postulate that the unique manipulation of transferrin receptor endocytic membrane trafficking by EPEC plays an important role in its survival on the luminal surface of the intestinal epithelium.
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Affiliation(s)
- Ephrem G. Kassa
- Department of Cell and Developmental Biology, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Efrat Zlotkin-Rivkin
- Department of Cell and Developmental Biology, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Gil Friedman
- Department of Cell and Developmental Biology, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Rachana P. Ramachandran
- Department of Cell and Developmental Biology, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Naomi Melamed-Book
- Bio-imaging Unit, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Aryeh M. Weiss
- Bio-imaging Unit, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
- Faculty of Engineering, Bar Ilan University, Ramat Gan, Israel
| | - Michael Belenky
- Department of Cell and Developmental Biology, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Dana Reichmann
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
- Proteomics and Mass Spectrometry Unit, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - William Breuer
- Proteomics and Mass Spectrometry Unit, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ritesh Ranjan Pal
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ilan Rosenshine
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Lynne A. Lapierre
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - James R. Goldenring
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Benjamin Aroeti
- Department of Cell and Developmental Biology, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
- * E-mail:
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Vardi N, Chaturvedi S, Weinberger LS. Feedback-mediated signal conversion promotes viral fitness. Proc Natl Acad Sci U S A 2018; 115:E8803-E8810. [PMID: 30150412 PMCID: PMC6140503 DOI: 10.1073/pnas.1802905115] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A fundamental signal-processing problem is how biological systems maintain phenotypic states (i.e., canalization) long after degradation of initial catalyst signals. For example, to efficiently replicate, herpesviruses (e.g., human cytomegalovirus, HCMV) rapidly counteract cell-mediated silencing using transactivators packaged in the tegument of the infecting virion particle. However, the activity of these tegument transactivators is inherently transient-they undergo immediate proteolysis but delayed synthesis-and how transient activation sustains lytic viral gene expression despite cell-mediated silencing is unclear. By constructing a two-color, conditional-feedback HCMV mutant, we find that positive feedback in HCMV's immediate-early 1 (IE1) protein is of sufficient strength to sustain HCMV lytic expression. Single-cell time-lapse imaging and mathematical modeling show that IE1 positive feedback converts transient transactivation signals from tegument pp71 proteins into sustained lytic expression, which is obligate for efficient viral replication, whereas attenuating feedback decreases fitness by promoting a reversible silenced state. Together, these results identify a regulatory mechanism enabling herpesviruses to sustain expression despite transient activation signals-akin to early electronic transistors-and expose a potential target for therapeutic intervention.
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Affiliation(s)
- Noam Vardi
- Gladstone-University of California, San Francisco (UCSF) Center for Cell Circuitry, Gladstone Institutes, San Francisco, CA 94158
| | - Sonali Chaturvedi
- Gladstone-University of California, San Francisco (UCSF) Center for Cell Circuitry, Gladstone Institutes, San Francisco, CA 94158
| | - Leor S Weinberger
- Gladstone-University of California, San Francisco (UCSF) Center for Cell Circuitry, Gladstone Institutes, San Francisco, CA 94158;
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94158
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94158
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10
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Affiliation(s)
- Joseph E. Aslan
- Knight Cardiovascular Institute, School of Medicine, Oregon Health & Science University, Portland, Oregon, USA
- Department of Biochemistry and Molecular Biology, School of Medicine, Oregon Health & Science University, Portland, Oregon, USA
- Department of Biomedical Engineering, School of Medicine, Oregon Health & Science University, Portland, Oregon, USA
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11
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Singh AP, Sharma S, Pagarware K, Siraji RA, Ansari I, Mandal A, Walling P, Aijaz S. Enteropathogenic E. coli effectors EspF and Map independently disrupt tight junctions through distinct mechanisms involving transcriptional and post-transcriptional regulation. Sci Rep 2018; 8:3719. [PMID: 29487356 PMCID: PMC5829253 DOI: 10.1038/s41598-018-22017-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 02/14/2018] [Indexed: 01/05/2023] Open
Abstract
Enteropathogenic E. coli infection is characterized by rapid onset of diarrhea but the underlying mechanisms are not well defined. EPEC targets the tight junctions which selectively regulate the permeability of charged and uncharged molecules. Cooperative actions of the EPEC effectors EspF and Map have been reported to mediate tight junction disruption. To analyze the individual contributions of EspF and Map, we generated in vitro models where EspF and Map, derived from the EPEC strain E2348/69, were constitutively expressed in epithelial cells. Here we report that tight junction disruption by EspF and Map is caused by the inhibition of the junctional recruitment of proteins during tight junction assembly. Constitutive expression of EspF and Map depleted the levels of tight junction proteins. EspF down-regulated the transcript levels of claudin-1, occludin and ZO-1, while Map down-regulated only claudin-1 transcripts. Both effectors also caused lysosomal degradation of existing tight junction proteins. We also identified a novel interaction of Map with non-muscle myosin II. Consistent with earlier studies, EspF was found to interact with ZO-1 while actin was the common interacting partner for both effectors. Our data provides evidence for the distinct roles of Map and EspF in tight junction disruption through non-synergistic functions.
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Affiliation(s)
- Anand Prakash Singh
- Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Swati Sharma
- Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Kirti Pagarware
- Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Rafay Anwar Siraji
- Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Imran Ansari
- Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Anupam Mandal
- Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Pangertoshi Walling
- Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Saima Aijaz
- Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, 110067, India.
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12
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A systematic exploration of the interactions between bacterial effector proteins and host cell membranes. Nat Commun 2017; 8:532. [PMID: 28912547 PMCID: PMC5599653 DOI: 10.1038/s41467-017-00700-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 07/20/2017] [Indexed: 01/08/2023] Open
Abstract
Membrane-bound organelles serve as platforms for the assembly of multi-protein complexes that function as hubs of signal transduction in eukaryotic cells. Microbial pathogens have evolved virulence factors that reprogram these host signaling responses, but the underlying molecular mechanisms are poorly understood. Here we test the ability of ~200 type III and type IV effector proteins from six Gram-negative bacterial species to interact with the eukaryotic plasma membrane and intracellular organelles. We show that over 30% of the effectors localize to yeast and mammalian cell membranes, including a subset of previously uncharacterized Legionella effectors that appear to be able to regulate yeast vacuolar fusion. A combined genetic, cellular, and biochemical approach supports that some of the tested bacterial effectors can bind to membrane phospholipids and may regulate membrane trafficking. Finally, we show that the type III effector IpgB1 from Shigella flexneri may bind to acidic phospholipids and regulate actin filament dynamics.Microbial pathogens secrete effector proteins into host cells to affect cellular functions. Here, the authors use a yeast-based screen to study around 200 effectors from six bacterial species, showing that over 30% of them interact with the eukaryotic plasma membrane or intracellular organelles.
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Ugalde-Silva P, Gonzalez-Lugo O, Navarro-Garcia F. Tight Junction Disruption Induced by Type 3 Secretion System Effectors Injected by Enteropathogenic and Enterohemorrhagic Escherichia coli. Front Cell Infect Microbiol 2016; 6:87. [PMID: 27606286 PMCID: PMC4995211 DOI: 10.3389/fcimb.2016.00087] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 08/10/2016] [Indexed: 12/18/2022] Open
Abstract
The intestinal epithelium consists of a single cell layer, which is a critical selectively permeable barrier to both absorb nutrients and avoid the entry of potentially harmful entities, including microorganisms. Epithelial cells are held together by the apical junctional complexes, consisting of adherens junctions, and tight junctions (TJs), and by underlying desmosomes. TJs lay in the apical domain of epithelial cells and are mainly composed by transmembrane proteins such as occludin, claudins, JAMs, and tricellulin, that are associated with the cytoplasmic plaque formed by proteins from the MAGUK family, such as ZO-1/2/3, connecting TJ to the actin cytoskeleton, and cingulin and paracingulin connecting TJ to the microtubule network. Extracellular bacteria such as EPEC and EHEC living in the intestinal lumen inject effectors proteins directly from the bacterial cytoplasm to the host cell cytoplasm, where they play a relevant role in the manipulation of the eukaryotic cell functions by modifying or blocking cell signaling pathways. TJ integrity depends on various cell functions such as actin cytoskeleton, microtubule network for vesicular trafficking, membrane integrity, inflammation, and cell survival. EPEC and EHEC effectors target most of these functions. Effectors encoded inside or outside of locus of enterocyte effacement (LEE) disrupt the TJ strands. EPEC and EHEC exploit the TJ dynamics to open this structure, for causing diarrhea. EPEC and EHEC secrete effectors that mimic host proteins to manipulate the signaling pathways, including those related to TJ dynamics. In this review, we focus on the known mechanisms exploited by EPEC and EHEC effectors for causing TJ disruption.
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Affiliation(s)
- Paul Ugalde-Silva
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional México City, Mexico
| | - Octavio Gonzalez-Lugo
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional México City, Mexico
| | - Fernando Navarro-Garcia
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional México City, Mexico
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14
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Rauch L, Hennings K, Trasak C, Röder A, Schröder B, Koch-Nolte F, Rivera-Molina F, Toomre D, Aepfelbacher M. Staphylococcus aureus recruits Cdc42GAP through recycling endosomes and the exocyst to invade human endothelial cells. J Cell Sci 2016; 129:2937-49. [PMID: 27311480 DOI: 10.1242/jcs.186213] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 06/13/2016] [Indexed: 01/01/2023] Open
Abstract
Activation and invasion of the vascular endothelium by Staphylococcus aureus is a major cause of sepsis and endocarditis. For endothelial cell invasion, S. aureus triggers actin polymerization through Cdc42, N-WASp (also known as WASL) and the Arp2/3 complex to assemble a phagocytic cup-like structure. Here, we show that after stimulating actin polymerization staphylococci recruit Cdc42GAP (also known as ARHGAP1) which deactivates Cdc42 and terminates actin polymerization in the phagocytic cups. Cdc42GAP is delivered to the invading bacteria on recycling endocytic vesicles in concert with the exocyst complex. When Cdc42GAP recruitment by staphylococci was prevented by blocking recycling endocytic vesicles or the exocyst complex, or when Cdc42 was constitutively activated, phagocytic cup closure was impaired and endothelial cell invasion was inhibited. Thus, to complete invasion of the endothelium, staphylococci reorient recycling endocytic vesicles to recruit Cdc42GAP, which terminates Cdc42-induced actin polymerization in phagocytic cups. Analogous mechanisms might govern other Cdc42-dependent cell functions.
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Affiliation(s)
- Liane Rauch
- Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, Hamburg 20246, Germany
| | - Kirsten Hennings
- Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, Hamburg 20246, Germany
| | - Claudia Trasak
- Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, Hamburg 20246, Germany
| | - Anja Röder
- Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, Hamburg 20246, Germany
| | - Barbara Schröder
- Institute of Biological and Medical Imaging (IBMI), Helmholtz Zentrum München, Ingolstädter Landstraße 1, Neuherberg 85764, Germany Institute for Biological Imaging, Technical University of Munich, Arcisstrasse 21, Munich 80333, Germany
| | - Friedrich Koch-Nolte
- Institute of Immunology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, Hamburg 20246, Germany
| | - Felix Rivera-Molina
- Department of Cell Biology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510, USA
| | - Derek Toomre
- Department of Cell Biology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510, USA
| | - Martin Aepfelbacher
- Institute of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, Hamburg 20246, Germany
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15
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Sharma R, Roberts E. Gradient sensing by a bistable regulatory motif enhances signal amplification but decreases accuracy in individual cells. Phys Biol 2016; 13:036003. [DOI: 10.1088/1478-3975/13/3/036003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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16
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Abstract
Bacterial pathogens encode a wide variety of effectors and toxins that hijack host cell structure and function. Of particular importance are virulence factors that target actin cytoskeleton dynamics critical for cell shape, stability, motility, phagocytosis, and division. In addition, many bacteria target organelles of the general secretory pathway (e.g., the endoplasmic reticulum and the Golgi complex) and recycling pathways (e.g., the endolysosomal system) to establish and maintain an intracellular replicative niche. Recent research on the biochemistry and structural biology of bacterial effector proteins and toxins has begun to shed light on the molecular underpinnings of these host-pathogen interactions. This exciting work is revealing how pathogens gain control of the complex and dynamic host cellular environments, which impacts our understanding of microbial infectious disease, immunology, and human cell biology.
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Affiliation(s)
- Alyssa Jimenez
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390;
| | - Didi Chen
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390;
| | - Neal M Alto
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390;
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17
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Stradal TEB, Costa SCP. Type III Secreted Virulence Factors Manipulating Signaling to Actin Dynamics. Curr Top Microbiol Immunol 2016; 399:175-199. [PMID: 27744505 DOI: 10.1007/82_2016_35] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A key aspect of bacterial pathogenesis is the colonization and persistence within the host and, later on, its dissemination to new niches. During evolution, bacteria developed a myriad of virulence mechanisms to usurp the host's sophisticated defense mechanisms in order to establish their colonization niche. Elucidation of the highly dynamic and complex interactions between host and pathogens remains an important field of study. Here, we highlight the conserved manipulation of the actin cytoskeleton by some Gram-negative gastrointestinal pathogens, addressing the role of type III secreted bacterial GEFs at the different steps of pathogenesis. As a final topic, we review cytoskeleton dynamics induced by EPEC/EHEC strains for pedestal formation.
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Affiliation(s)
- Theresia E B Stradal
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Baunschweig, Germany.
| | - Sonia C P Costa
- Department of Cell Biology, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Baunschweig, Germany
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18
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Deligianni DD. MWCNTs enhance hBMSCs spreading but delay their proliferation in the direction of differentiation acceleration. Cell Adh Migr 2015; 8:404-17. [PMID: 25482637 DOI: 10.4161/19336918.2014.969993] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Investigating the ability of films of pristine multiwalled nanotubes (MWCNTs) to influence human mesenchymal stem cells' proliferation, morphology, and differentiation into osteoblasts, we concluded to the following: A. MWCNTs delay the proliferation of hBMS cells but increase their differentiation. The enhancement of the differentiation markers could be a result of decreased proliferation and maturation of the extracellular matrix B. Cell spread on MWCNTs toward a polygonal shape with many thin filopodia to attach to the surfaces. Spreading may be critical in supporting osteogenic differentiation in pre-osteoblastic progenitors, being related with cytoskeletal tension. C. hBMS cells prefer MWCNTs than tissue plastic to attach and grow, being non-toxic to these cells. MWCNTs can be regarded as osteoinductive biomaterial topographies for bone regenerative engineering.
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Affiliation(s)
- Despina D Deligianni
- a Department of Mechanical Engineering & Aeronautics ; University of Patras ; Rion , Greece
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19
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Analysis of the activity and regulon of the two-component regulatory system composed by Cjj81176_1484 and Cjj81176_1483 of Campylobacter jejuni. J Bacteriol 2015; 197:1592-605. [PMID: 25691530 DOI: 10.1128/jb.02564-14] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 02/11/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Campylobacter jejuni is a leading cause of bacterial diarrheal disease and a frequent commensal of the intestinal tract in poultry and other animals. For optimal growth and colonization of hosts, C. jejuni employs two-component regulatory systems (TCSs) to monitor environmental conditions and promote proper expression of specific genes. We analyzed the potential of C. jejuni Cjj81176_1484 (Cjj1484) and Cjj81176_1483 (Cjj1483) to encode proteins of a cognate TCS that influences expression of genes possibly important for C. jejuni growth and colonization. Transcriptome analysis revealed that the regulons of the Cjj81176_1484 (Cjj1484) histidine kinase and the Cjj81176_1483 (Cjj1483) response regulator contain many common genes, suggesting that these proteins likely form a cognate TCS. We found that this TCS generally functions to repress expression of specific proteins with roles in metabolism, iron/heme acquisition, and respiration. Furthermore, the TCS repressed expression of Cjj81176_0438 and Cjj81176_0439, which had previously been found to encode a gluconate dehydrogenase complex required for commensal colonization of the chick intestinal tract. However, the TCS and other specific genes whose expression is repressed by the TCS were not required for colonization of chicks. We observed that the Cjj1483 response regulator binds target promoters in both unphosphorylated and phosphorylated forms and influences expression of some specific genes independently of the Cjj1484 histidine kinase. This work further expands the signaling mechanisms of C. jejuni and provides additional insights regarding the complex and multifactorial regulation of many genes involved in basic metabolism, respiration, and nutrient acquisition that the bacterium requires for optimal growth in different environments. IMPORTANCE Bacterial two-component regulatory systems (TCSs) link environmental cues to expression of specific genes that enable optimal bacterial growth or colonization of hosts. We found that the Campylobacter jejuni Cjj1484 histidine kinase and Cjj1483 response regulator function as a cognate TCS to largely repress expression of target genes encoding a gluconate dehydrogenase complex required for commensal colonization of the chick intestinal tract, as well as other genes encoding proteins for heme or iron acquisition, metabolism, and respiration. We also discovered different modes by which Cjj1483 may mediate repression with and without Cjj1484. This work provides insight into the signal transduction mechanisms of a leading cause of bacterial diarrheal disease and emphasizes the multifactorial and complex regulation of specific biological processes in C. jejuni.
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20
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Wang MJ, Artemenko Y, Cai WJ, Iglesias PA, Devreotes PN. The directional response of chemotactic cells depends on a balance between cytoskeletal architecture and the external gradient. Cell Rep 2014; 9:1110-21. [PMID: 25437564 DOI: 10.1016/j.celrep.2014.09.047] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 08/29/2014] [Accepted: 09/25/2014] [Indexed: 11/19/2022] Open
Abstract
Polarized migrating cells display signal transduction events, such as activation of phosphatidylinositol 3-kinase (PI3K) and Scar/Wave, and respond more readily to chemotactic stimuli at the leading edge. We sought to determine the basis of this polarized sensitivity. Inhibiting actin polymerization leads to uniform sensitivity. However, when human neutrophils were "stalled" by simultaneously blocking actin and myosin dynamics, they maintained the gradient of responsiveness to chemoattractant and also displayed noise-driven PIP3 flashes on the basal membrane, localized toward the front. Thus, polarized sensitivity does not require migration or cytoskeletal dynamics. The threshold for response is correlated with the static F-actin distribution, but not cell shape or volume changes, membrane fluidity, or the preexisting distribution of PI3K. The kinetics of responses to temporal and spatial stimuli were consistent with the local excitation global inhibition model, but the overall direction of the response was biased by the internal axis of polarity.
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Affiliation(s)
- Ming-Jie Wang
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Physiology and Pathophysiology, Fudan University Shanghai Medical College, Shanghai 200032, China
| | - Yulia Artemenko
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Wen-Jie Cai
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Basic Medicine, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Pablo A Iglesias
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Peter N Devreotes
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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21
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Bement WM, von Dassow G. Single cell pattern formation and transient cytoskeletal arrays. Curr Opin Cell Biol 2013; 26:51-9. [PMID: 24529246 DOI: 10.1016/j.ceb.2013.09.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2013] [Revised: 09/25/2013] [Accepted: 09/26/2013] [Indexed: 12/28/2022]
Abstract
A major goal of developmental biology is to explain the emergence of pattern in cell layers, tissues and organs. Developmental biologists now accept that reaction diffusion-based mechanisms are broadly employed in developing organisms to direct pattern formation. Here we briefly consider these mechanisms and then apply some of the concepts derived from them to several processes that occur in single cells: wound repair, yeast budding, and cytokinesis. Two conclusions emerge from this analysis: first, there is considerable overlap at the level of general mechanisms between developmental and single cell pattern formation; second, dynamic structures based on the actin cytoskeleton may be far more ordered than is generally recognized.
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Affiliation(s)
- William M Bement
- Laboratory of Cell and Molecular Biology and Department of Zoology, University of Wisconsin-Madison, 1525 Linden Drive, Madison, Wisconsin 53706, USA; Oregon Institute of Marine Biology, University of Oregon, P.O. Box 5389, Charleston, OR 97420, USA.
| | - George von Dassow
- Laboratory of Cell and Molecular Biology and Department of Zoology, University of Wisconsin-Madison, 1525 Linden Drive, Madison, Wisconsin 53706, USA.
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22
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Dean P, Young L, Quitard S, Kenny B. Insights into the pathogenesis of enteropathogenic E. coli using an improved intestinal enterocyte model. PLoS One 2013; 8:e55284. [PMID: 23383137 PMCID: PMC3557262 DOI: 10.1371/journal.pone.0055284] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Accepted: 12/21/2012] [Indexed: 11/28/2022] Open
Abstract
Enteropathogenic E. coli (EPEC) is a human pathogen that targets the small intestine, causing severe and often fatal diarrhoea in infants. A defining feature of EPEC disease is the loss (effacement) of absorptive microvilli (MV) from the surface of small intestinal enterocytes. Much of our understanding of EPEC pathogenesis is derived from studies using cell lines such as Caco-2 – the most extensively used small intestinal model. However, previous work has revealed fundamental differences between Caco-2 cells and in vivo differentiated enterocytes in relation to MV effacement. This, and the high heterogeneity and low transfection efficiency of the Caco-2 cell line prompted the isolation of several sub-clones (NCL-1–12) to identify a more tractable and improved in vivo-like cell model. Along with established Caco-2 clones (TC-7, BBE1), sub-clones were assessed for growth rate, apical surface morphology, epithelial barrier function and transfection efficiency. TC-7 cells provided the best all-round clone and exhibited highest levels of ectopic gene expression following cell polarisation. Novel alterations in EGFP-labelled mitochondria, that were not previously documented in non-polarised cell types, highlighted the potential of the TC-7 model for defining dynamic enterocyte-specific changes during infection. Crucially, the TC-7 cell line also mimicked ex vivo derived enterocytes with regard to MV effacement, enabling a better dissection of the process. Effacement activity caused by the EPEC protein Map in the Caco-2 but not ex vivo model, was linked to a defect in suppressing its Cdc42-dependent functionality. MV effacement activity of the EPEC protein EspF in the TC-7 model was dependent on its N-WASP binding motif, which is also shown to play an essential role in epithelial barrier dysfunction. Together, this study highlights the many advantages of using TC-7 cells as a small intestinal model to study host-pathogen interactions.
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Affiliation(s)
- Paul Dean
- Institute of Cell and Molecular Biosciences, Medical School, University of Newcastle, Newcastle-Upon-Tyne, United Kingdom
- * E-mail: (PD) (PD); (BK) (BK)
| | - Lorna Young
- Institute of Cell and Molecular Biosciences, Medical School, University of Newcastle, Newcastle-Upon-Tyne, United Kingdom
| | - Sabine Quitard
- Institute of Cell and Molecular Biosciences, Medical School, University of Newcastle, Newcastle-Upon-Tyne, United Kingdom
| | - Brendan Kenny
- Institute of Cell and Molecular Biosciences, Medical School, University of Newcastle, Newcastle-Upon-Tyne, United Kingdom
- * E-mail: (PD) (PD); (BK) (BK)
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23
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Actin cytoskeleton manipulation by effector proteins secreted by diarrheagenic Escherichia coli pathotypes. BIOMED RESEARCH INTERNATIONAL 2012; 2013:374395. [PMID: 23509714 PMCID: PMC3591105 DOI: 10.1155/2013/374395] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 10/22/2012] [Indexed: 11/18/2022]
Abstract
The actin cytoskeleton is a dynamic structure necessary for cell and tissue organization, including the maintenance of epithelial barriers. Disruption of the epithelial barrier coincides with alterations of the actin cytoskeleton in several disease states. These disruptions primarily affect the paracellular space, which is normally regulated by tight junctions. Thereby, the actin cytoskeleton is a common and recurring target of bacterial virulence factors. In order to manipulate the actin cytoskeleton, bacteria secrete and inject toxins and effectors to hijack the host cell machinery, which interferes with host-cell pathways and with a number of actin binding proteins. An interesting model to study actin manipulation by bacterial effectors is Escherichia coli since due to its genome plasticity it has acquired diverse genetic mobile elements, which allow having different E. coli varieties in one bacterial species. These E. coli pathotypes, including intracellular and extracellular bacteria, interact with epithelial cells, and their interactions depend on a specific combination of virulence factors. In this paper we focus on E. coli effectors that mimic host cell proteins to manipulate the actin cytoskeleton. The study of bacterial effector-cytoskeleton interaction will contribute not only to the comprehension of the molecular causes of infectious diseases but also to increase our knowledge of cell biology.
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24
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Simon CM, Vaughan EM, Bement WM, Edelstein-Keshet L. Pattern formation of Rho GTPases in single cell wound healing. Mol Biol Cell 2012; 24:421-32. [PMID: 23264464 PMCID: PMC3564532 DOI: 10.1091/mbc.e12-08-0634] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
A mathematical model is developed to explain segregation and maintenance of Rho and Cdc42 activity zones during wound healing. The model replicates basic features of zone segregation and dynamics, reveals that Rho and Cdc42 activities represent spatially modulated bistability, and makes nonintuitive predictions confirmed by experiment. The Rho GTPases—Rho, Rac, and Cdc42—control an enormous variety of processes, many of which reflect activation of these GTPases in spatially confined and mutually exclusive zones. By using mathematical models and experimental results to establish model parameters, we analyze the formation and segregation of Rho and Cdc42 zones during Xenopus oocyte wound repair and the role played by Abr, a dual guanine nucleotide exchange factor–GTPase-activating protein, in this process. The Rho and Cdc42 zones are found to be best represented as manifestations of spatially modulated bistability, and local positive feedback between Abr and Rho can account for the maintenance and dynamic properties of the Rho zone. In contrast, the invocation of an Abr-independent positive feedback loop is required to account for Cdc42 spatial bistability. In addition, the model replicates the results of previous in vivo experiments in which Abr activity is manipulated. Further, simulating the model with two closely spaced wounds made nonintuitive predictions about the Rho and Cdc42 patterns; these predictions were confirmed by experiment. We conclude that the model is a useful tool for analysis of Rho GTPase signaling and that the Rho GTPases can be fruitfully considered as components of intracellular pattern formation systems.
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Affiliation(s)
- Cory M Simon
- Department of Mathematics, University of British Columbia, Vancouver, BC, Canada.
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