73 results found
Lobato-Marquez D, Mostowy S, Salmonella ubiquitination: ARIH1 enters the fray, EMBO Reports, ISSN: 1469-221X
Ubiquitination is a post-translational modification in which ubiquitin, a 76 amino acid polypeptide, is covalently bound to one or more lysines of a target protein. Ubiquitination is mediated by the coordinated activity of ubiquitin activating (E1), conjugating (E2), and ligating (E3) enzymes. Ubiquitin is widely investigated for its ability to regulate key biological processes in the cell, including protein degradation and host-bacteria interactions. The determinants underlying bacterial ubiquitination, and their precise roles in host defense, have not been fully resolved. In this issue of EMBO reports, Polajnar et al discover that Ring-between-Ring (RBR) E3 ligase ARIH1 (also known as HHARI) is involved in formation of the ubiquitin coat surrounding cytosolic Salmonella . Evidence suggests that ARIH1, in cooperation with E3 ligases LRSAM1 and HOIP, modulates the recognition of intracellular bacteria for cellautonomous immunity.
Mostowy S, Chytrid fungus infection in zebrafish demonstrates that the pathogen can parasitise non-amphibian vertebrate hosts, Nature Communications
Liew N, Moya MJM, Wierzbicki CJ, et al., 2017, Chytrid fungus infection in zebrafish demonstrates that the pathogen can parasitize non-amphibian vertebrate hosts, NATURE COMMUNICATIONS, Vol: 8, Pages: 15048-15048, ISSN: 2041-1723
Aquatic chytrid fungi threaten amphibian biodiversity worldwide owing to their ability to rapidly expand their geographical distributions and to infect a wide range of hosts. Combating this risk requires an understanding of chytrid host range to identify potential reservoirs of infection and to safeguard uninfected regions through enhanced biosecurity. Here we extend our knowledge on the host range of the chytrid Batrachochytrium dendrobatidis by demonstrating infection of a non-amphibian vertebrate host, the zebrafish. We observe dose-dependent mortality and show that chytrid can infect and proliferate on zebrafish tissue. We also show that infection phenotypes (fin erosion, cell apoptosis and muscle degeneration) are direct symptoms of infection. Successful infection is dependent on disrupting the zebrafish microbiome, highlighting that, as is widely found in amphibians, commensal bacteria confer protection against this pathogen. Collectively, our findings greatly expand the limited tool kit available to study pathogenesis and host response to chytrid infection.
Mazon-Moya MJ, Willis AR, Torraca V, et al., 2017, Septins restrict inflammation and protect zebrafish larvae from Shigella infection, PLOS PATHOGENS, Vol: 13, Pages: e1006467-e1006467, ISSN: 1553-7366
Shigella flexneri, a Gram-negative enteroinvasive pathogen, causes inflammatory destruction of the human intestinal epithelium. Infection by S. flexneri has been well-studied in vitro and is a paradigm for bacterial interactions with the host immune system. Recent work has revealed that components of the cytoskeleton have important functions in innate immunity and inflammation control. Septins, highly conserved cytoskeletal proteins, have emerged as key players in innate immunity to bacterial infection, yet septin function in vivo is poorly understood. Here, we use S. flexneri infection of zebrafish (Danio rerio) larvae to study in vivo the role of septins in inflammation and infection control. We found that depletion of Sept15 or Sept7b, zebrafish orthologs of human SEPT7, significantly increased host susceptibility to bacterial infection. Live-cell imaging of Sept15-depleted larvae revealed increasing bacterial burdens and a failure of neutrophils to control infection. Strikingly, Sept15-depleted larvae present significantly increased activity of Caspase-1 and more cell death upon S. flexneri infection. Dampening of the inflammatory response with anakinra, an antagonist of interleukin-1 receptor (IL-1R), counteracts Sept15 deficiency in vivo by protecting zebrafish from hyper-inflammation and S. flexneri infection. These findings highlight a new role for septins in host defence against bacterial infection, and suggest that septin dysfunction may be an underlying factor in cases of hyper-inflammation.
McCarthy RR, Mazon-Moya MJ, Moscoso JA, et al., 2017, Cyclic-di-GMP regulates lipopolysaccharide modification and contributes to Pseudomonas aeruginosa immune evasion, NATURE MICROBIOLOGY, Vol: 2, Pages: 17027-17027, ISSN: 2058-5276
Pseudomonas aeruginosa is a Gram-negative bacterial pathogen associated with acute and chronic infections. The universal cyclic-di-GMP second messenger is instrumental in the switch from a motile lifestyle to resilient biofilm as in the cystic fibrosis lung. The SadC diguanylate cyclase is associated with this patho-adaptive transition. Here, we identify an unrecognized SadC partner, WarA, which we show is a methyltransferase in complex with a putative kinase, WarB. We established that WarA binds to cyclic-di-GMP, which potentiates its methyltransferase activity. Together, WarA and WarB have structural similarities with the bifunctional Escherichia coli lipopolysaccharide (LPS) O antigen regulator WbdD. Strikingly, WarA influences P. aeruginosa O antigen modal distribution and interacts with the LPS biogenesis machinery. LPS is known to modulate the immune response in the host, and by using a zebrafish infection model, we implicate WarA in the ability of P. aeruginosa to evade detection by the host.
Mesquita FS, Brito C, Mazon Moya MJ, et al., 2017, Endoplasmic reticulum chaperone Gp96 controls actomyosin dynamics and protects against pore-forming toxins, EMBO REPORTS, Vol: 18, Pages: 303-318, ISSN: 1469-221X
During infection, plasma membrane (PM) blebs protect host cells against bacterial pore-forming toxins (PFTs), but were also proposed to promote pathogen dissemination. However, the details and impact of blebbing regulation during infection remained unclear. Here, we identify the endoplasmic reticulum chaperone Gp96 as a novel regulator of PFT-induced blebbing. Gp96 interacts with non-muscle myosin heavy chain IIA (NMHCIIA) and controls its activity and remodelling, which is required for appropriate coordination of bleb formation and retraction. This mechanism involves NMHCIIA-Gp96 interaction and their recruitment to PM blebs and strongly resembles retraction of uropod-like structures from polarized migrating cells, a process that also promotes NMHCIIA-Gp96 association. Consistently, Gp96 and NMHCIIA not only protect the PM integrity from listeriolysin O (LLO) during infection by Listeria monocytogenes but also affect cytoskeletal organization and cell migration. Finally, we validate the association between Gp96 and NMHCIIA in vivo and show that Gp96 is required to protect hosts from LLO-dependent killing.
Klionsky DJ, Abdelmohsen K, Abe A, et al., 2016, Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition), AUTOPHAGY, Vol: 12, Pages: 1-222, ISSN: 1554-8627
Krokowski S, Lobato-Márquez D, Mostowy S, et al., 2016, Mitochondria promote septin assembly into cages that entrap Shigella for autophagy., Autophagy, Pages: 0-00, ISSN: 1554-8627
Septins are cytoskeletal proteins implicated in cytokinesis and host-pathogen interactions. During macroautophagy/autophagy of Shigella flexneri, septins assemble into cage-like structures to entrap actin-polymerizing bacteria and restrict their dissemination. How septins assemble to entrap bacteria is not fully known. We discovered that mitochondria support septin cage assembly to promote autophagy of Shigella. Consistent with roles for the cytoskeleton in mitochondrial dynamics, we showed that DNM1L/DRP1 (dynamin 1 like) can interact with septins to enhance mitochondrial fission. Remarkably, Shigella fragment mitochondria and escape from septin cage entrapment in order to avoid autophagy. These results uncover a close relationship between mitochondria and septin assembly, and identify a new role for mitochondria in bacterial autophagy.
Krokowski S, Mostowy S, Krokowski S, et al., 2016, Investigation of septins using infection by bacterial pathogens, SEPTINS, Vol: 136, Pages: 117-134, ISSN: 0091-679X
Investigation of the host cytoskeleton during infection by bacterial pathogens has significantly contributed to our understanding of cell biology and host defense. Work has shown that septins are recruited to the phagocytic cup as collarlike structures and enable bacterial entry into host cells. In the cytosol, septins can entrap actin-polymerizing bacteria in cage-like structures for targeting to autophagy, a highly conserved intracellular degradation process. In this chapter, we describe methods to investigate septin assembly and function during infection by bacterial pathogens. Use of these methods can lead to in-depth understanding of septin biology and suggest therapeutic approaches to combat infectious disease.
Krokowski S, Mostowy S, Krokowski S, et al., 2016, Interactions between Shigella flexneri and the Autophagy Machinery, FRONTIERS IN CELLULAR AND INFECTION MICROBIOLOGY, Vol: 6, ISSN: 2235-2988
Autophagy, an intracellular degradation process, is increasingly recognized as having important roles in host defense. Interactions between Shigella flexneri and the autophagy machinery were first discovered in 2005. Since then, work has shown that multiple autophagy pathways are triggered by S. flexneri, and autophagic responses can have different roles during Shigella infection. Here, we review the interactions between S. flexneri and the autophagy machinery, highlighting that studies using Shigella can reveal the breadth of autophagic responses available to the host.
Larrouy-Maumus G, Clements A, Filloux A, et al., 2016, Direct detection of lipid A on intact Gram-negative bacteria by MALDI-TOF mass spectrometry, JOURNAL OF MICROBIOLOGICAL METHODS, Vol: 120, Pages: 68-71, ISSN: 0167-7012
The purification and characterization of Gram-negative bacterial lipid A is tedious and time-consuming. Herein we report a rapid and sensitive method to identify lipid A directly on intact bacteria without any chemical treatment or purification, using an atypical solvent system to solubilize the matrix combined with MALDI-TOF mass spectrometry.
How cells recognize membrane curvature is not fully understood. In this issue, Bridges et al. (2016.J. Cell Biol.http://dx.doi.org/10.1083/jcb.201512029) discover that septins, a component of the cytoskeleton, recognize membrane curvature at the micron scale, a common morphological hallmark of eukaryotic cellular processes.
Pfanzelter J, Way M, Mostowy S, 2016, Septins suppress the release of vaccinia virus from infected cells., Annual Meeting of the American-Society-for-Cell-Biology (ASCB), Publisher: AMER SOC CELL BIOLOGY, ISSN: 1059-1524
Shah A, Kannambath S, Herbst S, et al., 2016, Calcineurin Orchestrates Lateral Transfer of Aspergillus fumigatus during Macrophage Cell Death, AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE, Vol: 194, Pages: 1127-1139, ISSN: 1073-449X
RATIONALE: Pulmonary aspergillosis is a lethal mold infection in the immunocompromised host. Understanding initial control of infection and how this is altered in the immunocompromised host are key goals for comprehension of the pathogenesis of pulmonary aspergillosis. OBJECTIVES: To characterize the outcome of human macrophage infection with Aspergillus fumigatus and how this is altered in transplant recipients on calcineurin inhibitor immunosuppressants. METHODS: We defined the outcome of human macrophage infection with A. fumigatus, as well as the impact of calcineurin inhibitors, through a combination of single-cell fluorescence imaging, transcriptomics, proteomics, and in vivo studies. MEASUREMENTS AND MAIN RESULTS: Macrophage phagocytosis of A. fumigatus enabled control of 90% of fungal germination. However, fungal germination in the late phagosome led to macrophage necrosis. During programmed necroptosis, we observed frequent cell-cell transfer of A. fumigatus between macrophages, which assists subsequent control of germination in recipient macrophages. Lateral transfer occurred through actin-dependent exocytosis of the late endosome in a vasodilator-stimulated phosphoprotein envelope. Its relevance to the control of fungal germination was also shown by direct visualization in our zebrafish aspergillosis model in vivo. The calcineurin inhibitor FK506 (tacrolimus) reduced cell death and lateral transfer in vitro by 50%. This resulted in uncontrolled fungal germination in macrophages and also resulted in hyphal escape. CONCLUSIONS: These observations identify programmed, necrosis-dependent lateral transfer of A. fumigatus between macrophages as an important host strategy for controlling fungal germination. This process is critically dependent on calcineurin. Our studies provide fundamental insights into the pathogenesis of pulmonary aspergillosis in the immunocompromised host.
Sirianni A, Krokowski S, Lobato-Marquez D, et al., 2016, Mitochondria mediate septin cage assembly to promote autophagy of Shigella, EMBO REPORTS, Vol: 17, Pages: 1029-1043, ISSN: 1469-221X
Septins, cytoskeletal proteins with well-characterised roles in cytokinesis, form cage-like structures around cytosolic Shigella flexneri and promote their targeting to autophagosomes. However, the processes underlying septin cage assembly, and whether they influence S. flexneri proliferation, remain to be established. Using single-cell analysis, we show that the septin cages inhibit S. flexneri proliferation. To study mechanisms of septin cage assembly, we used proteomics and found mitochondrial proteins associate with septins in S. flexneri-infected cells. Strikingly, mitochondria associated with S. flexneri promote septin assembly into cages that entrap bacteria for autophagy. We demonstrate that the cytosolic GTPase dynamin-related protein 1 (Drp1) interacts with septins to enhance mitochondrial fission. To avoid autophagy, actin-polymerising Shigella fragment mitochondria to escape from septin caging. Our results demonstrate a role for mitochondria in anti-Shigella autophagy and uncover a fundamental link between septin assembly and mitochondria.
Septins, a unique cytoskeletal component associated with cellular membranes, are increasingly recognized as having important roles in host defense against bacterial infection. A role for septins during invasion of Listeria monocytogenes into host cells was first proposed in 2002. Since then, work has shown that septins assemble in response to a wide variety of invasive bacterial pathogens, and septin assemblies can have different roles during the bacterial infection process. Here we review the interplay between septins and bacterial pathogens, highlighting septins as a structural determinant of host defense. We also discuss how investigation of septin assembly in response to bacterial infection can yield insight into basic cellular processes including phagocytosis, autophagy, and mitochondrial dynamics.
Willis A, Mazon-Moya M, Mostowy S, et al., 2016, Investigation of septin biology in vivo using zebrafish, SEPTINS, Vol: 136, Pages: 221-241, ISSN: 0091-679X
The zebrafish (Danio rerio) is an important animal model to study cell biology in vivo. Benefits of the zebrafish include a fully annotated reference genome, an easily manipulable genome (for example, by morpholino oligonucleotide or CRISPR-Cas9), and transparent embryos for noninvasive, real-time microscopy using fluorescent transgenic lines. Zebrafish have orthologues of most human septins, and studies using larvae were used to investigate the role of septins in vertebrate development. The zebrafish larva is also an established model to study the cell biology of infection and has recently been used to visualize septin assembly during bacterial infection in vivo. Here, we describe protocols for the study of septins in zebrafish, with emphasis on techniques used to investigate the role of septins in host defense against bacterial infection.
Willis AR, Moore C, Mazon-Moya M, et al., 2016, Injections of Predatory Bacteria Work Alongside Host Immune Cells to Treat Shigella Infection in Zebrafish Larvae, CURRENT BIOLOGY, Vol: 26, Pages: 3343-3351, ISSN: 0960-9822
Bdellovibrio bacteriovorus are predatory bacteria that invade and kill a range of Gram-negative bacterial pathogens in natural environments and in vitro [1, 2]. In this study, we investigated Bdellovibrio as an injected, antibacterial treatment in vivo, using zebrafish (Danio rerio) larvae infected with an antibiotic-resistant strain of the human pathogen Shigella flexneri. When injected alone, Bdellovibrio can persist for more than 24 hr in vivo yet exert no pathogenic effects on zebrafish larvae. Bdellovibrio injection of zebrafish containing a lethal dose of Shigella promotes pathogen killing, leading to increased zebrafish survival. Live-cell imaging of infected zebrafish reveals that Shigella undergo rounding induced by the invasive predation from Bdellovibrio in vivo. Furthermore, Shigella-dependent replication of Bdellovibrio was captured inside the zebrafish larvae, indicating active predation in vivo. Bdellovibrio can be engulfed and ultimately eliminated by host neutrophils and macrophages, yet have a sufficient dwell time to prey on pathogens. Experiments in immune-compromised zebrafish reveal that maximal therapeutic benefits of Bdellovibrio result from the synergy of both bacterial predation and host immunity, but that in vivo predation contributes significantly to the survival outcome. Our results demonstrate that successful antibacterial therapy can be achieved via the host immune system working together with bacterial predation by Bdellovibrio. Such cooperation may be important to consider in the fight against antibiotic-resistant infections in vivo.
Gibbings D, Mostowy S, Jay F, et al., 2015, Corrigendum: Selective autophagy degrades DICER and AGO2 and regulates miRNA activity., Nat Cell Biol, Vol: 17, Pages: 1088-1088, ISSN: 1465-7392
Herbst S, Shah A, Moya MM, et al., 2015, Phagocytosis-dependent activation of a TLR9-BTK-calcineurin-NFAT pathway co-ordinates innate immunity to Aspergillus fumigatus, EMBO MOLECULAR MEDICINE, Vol: 7, Pages: 240-258, ISSN: 1757-4676
Transplant recipients on calcineurin inhibitors are at high risk of invasive fungal infection. Understanding how calcineurin inhibitors impair fungal immunity is a key priority for defining risk of infection. Here, we show that the calcineurin inhibitor tacrolimus impairs clearance of the major mould pathogen Aspergillus fumigatus from the airway, by inhibiting macrophage inflammatory responses. This leads to defective early neutrophil recruitment and fungal clearance. We confirm these findings in zebrafish, showing an evolutionarily conserved role for calcineurin signalling in neutrophil recruitment during inflammation. We find that calcineurin-NFAT activation is phagocytosis dependent and collaborates with NF-κB for TNF-α production. For yeast zymosan particles, activation of macrophage calcineurin-NFAT occurs via the phagocytic Dectin-1-spleen tyrosine kinase pathway, but for A. fumigatus, activation occurs via a phagosomal TLR9-dependent and Bruton's tyrosine kinase-dependent signalling pathway that is independent of MyD88. We confirm the collaboration between NFAT and NF-κB for TNF-α production in primary alveolar macrophages. These observations identify inhibition of a newly discovered macrophage TLR9-BTK-calcineurin-NFAT signalling pathway as a key immune defect that leads to organ transplant-related invasive aspergillosis.
Mostowy S, Shenoy AR, Mostowy S, et al., 2015, The cytoskeleton in cell-autonomous immunity: structural determinants of host defence, NATURE REVIEWS IMMUNOLOGY, Vol: 15, Pages: 559-573, ISSN: 1474-1733
Host cells use antimicrobial proteins, pathogen-restrictive compartmentalization and cell death in their defence against intracellular pathogens. Recent work has revealed that four components of the cytoskeleton--actin, microtubules, intermediate filaments and septins, which are well known for their roles in cell division, shape and movement--have important functions in innate immunity and cellular self-defence. Investigations using cellular and animal models have shown that these cytoskeletal proteins are crucial for sensing bacteria and for mobilizing effector mechanisms to eliminate them. In this Review, we highlight the emerging roles of the cytoskeleton as a structural determinant of cell-autonomous host defence.
Shah A, Kannambath S, Herbst S, et al., 2015, 'THE KISS OF DEATH' - CALCINEURIN INHIBITORS PREVENT ACTIN-DEPENDENT LATERAL TRANSFER OF ASPERGILLUS FUMIGATUS IN NECROPTOTIC HUMAN MACROPHAGES, Winter Meeting of the British-Thoracic-Society, Publisher: BMJ PUBLISHING GROUP, Pages: A48-A48, ISSN: 0040-6376
Sirianni A, Mostowy S, 2015, Autophagy in the Infected Cell: Insights from Pathogenic Bacteria, Autophagy, Infection, and the Immune Response, Pages: 143-157, ISBN: 9781118677551
© 2015 by John Wiley & Sons, Inc. All rights reserved. Autophagy is an important defence mechanism to clear intracellular microbes. A wide variety of bacterial pathogens are targeted to autophagy; however, some have evolved mechanisms to avoid or manipulate the autophagy machinery for intracellular survival. An in-depth understanding of autophagy-bacteria interactions will therefore be critical to appreciate fully how the autophagy machinery can function in immunity and microbial clearance in vivo.
Mostowy S, Bi E, Fuchtbauer E-M, et al., 2014, Highlight: The 5th International Workshop on Septin Biology, BIOLOGICAL CHEMISTRY, Vol: 395, Pages: 119-121, ISSN: 1431-6730
Mostowy S, Mostowy S, Mostowy S, et al., 2014, Multiple Roles of the Cytoskeleton in Bacterial Autophagy, PLOS PATHOGENS, Vol: 10, Pages: e1004409-e1004409, ISSN: 1553-7366
Moya MJM, Colucci-Guyon E, Mostowy S, et al., 2014, Use of Shigella flexneri to Study Autophagy-Cytoskeleton Interactions, JOVE-JOURNAL OF VISUALIZED EXPERIMENTS, ISSN: 1940-087X
Shigella flexneri is an intracellular pathogen that can escape from phagosomes to reach the cytosol, and polymerize the host actin cytoskeleton to promote its motility and dissemination. New work has shown that proteins involved in actin-based motility are also linked to autophagy, an intracellular degradation process crucial for cell autonomous immunity. Strikingly, host cells may prevent actin-based motility of S. flexneri by compartmentalizing bacteria inside 'septin cages' and targeting them to autophagy. These observations indicate that a more complete understanding of septins, a family of filamentous GTP-binding proteins, will provide new insights into the process of autophagy. This report describes protocols to monitor autophagy-cytoskeleton interactions caused by S. flexneri in vitro using tissue culture cells and in vivo using zebrafish larvae. These protocols enable investigation of intracellular mechanisms that control bacterial dissemination at the molecular, cellular, and whole organism level.
Ghossoub R, Hu Q, Failler M, et al., 2013, Septins 2, 7 and 9 and MAP4 colocalize along the axoneme in the primary cilium and control ciliary length, JOURNAL OF CELL SCIENCE, Vol: 126, Pages: 2583-2594, ISSN: 0021-9533
Septins are a large, evolutionarily conserved family of GTPases that form hetero-oligomers and interact with the actin-based cytoskeleton and microtubules. They are involved in scaffolding functions, and form diffusion barriers in budding yeast, the sperm flagellum and the base of primary cilia of kidney epithelial cells. We investigated the role of septins in the primary cilium of retinal pigmented epithelial (RPE) cells, and found that SEPT2 forms a 1:1:1 complex with SEPT7 and SEPT9 and that the three members of this complex colocalize along the length of the axoneme. Similar to observations in kidney epithelial cells, depletion of cilium-localized septins by siRNA-based approaches inhibited ciliogenesis. MAP4, which is a binding partner of SEPT2 and controls the accessibility of septins to microtubules, was also localized to the axoneme where it appeared to negatively regulate ciliary length. Taken together, our data provide new insights into the functions and regulation of septins and MAP4 in the organization of the primary cilium and microtubule-based activities in cells.
MicroRNAs (miRNAs) form a class of ~21 nucleotide (nt) RNAs that post-transcriptionally repress partially complementary messenger RNAs. miRNA-mediated silencing is critical for control of many key biological processes such as tumorigenesis, neuronal synaptic plasticity and defense against bacteria and viruses. Thus, unsurprisingly, miRNA biogenesis, abundance and action are under refined feedback control that is only beginning to be experimentally uncovered. We recently discovered that DICER1 and EIF2C/AGO are targeted for degradation by autophagy as miRNA-free entities by the selective autophagy receptor CALCOCO2/NDP52 (calcium binding and coiled-coil domain 2/nuclear dot protein, 52 kDa). Strikingly, autophagy establishes a checkpoint for continued loading of miRNA, and this checkpoint is required for maintenance of miRNA abundance and proper miRNA activity. This newfound role for autophagy in miRNA biology suggests that human diseases exhibiting misregulated autophagy may be interdependent with defects in miRNA-mediated regulation of gene networks.
Guenin-Mace L, Veyron-Churlet R, Thoulouze M-I, et al., 2013, Mycolactone activation of Wiskott-Aldrich syndrome proteins underpins Buruli ulcer formation, JOURNAL OF CLINICAL INVESTIGATION, Vol: 123, Pages: 1501-1512, ISSN: 0021-9738
Mycolactone is a diffusible lipid secreted by the human pathogen Mycobacterium ulcerans, which induces the formation of open skin lesions referred to as Buruli ulcers. Here, we show that mycolactone operates by hijacking the Wiskott-Aldrich syndrome protein (WASP) family of actin-nucleating factors. By disrupting WASP autoinhibition, mycolactone leads to uncontrolled activation of ARP2/3-mediated assembly of actin in the cytoplasm. In epithelial cells, mycolactone-induced stimulation of ARP2/3 concentrated in the perinuclear region, resulting in defective cell adhesion and directional migration. In vivo injection of mycolactone into mouse ears consistently altered the junctional organization and stratification of keratinocytes, leading to epidermal thinning, followed by rupture. This degradation process was efficiently suppressed by coadministration of the N-WASP inhibitor wiskostatin. These results elucidate the molecular basis of mycolactone activity and provide a mechanism for Buruli ulcer pathogenesis. Our findings should allow for the rationale design of competitive inhibitors of mycolactone binding to N-WASP, with anti-Buruli ulcer therapeutic potential.
Judith D, Mostowy S, Bourai M, et al., 2013, Species-specific impact of the autophagy machinery on Chikungunya virus infection, EMBO REPORTS, Vol: 14, Pages: 534-544, ISSN: 1469-221X
Chikungunya virus (CHIKV) is a recently re-emerged arbovirus that triggers autophagy. Here, we show that CHIKV interacts with components of the autophagy machinery during its replication cycle, inducing a cytoprotective effect. The autophagy receptor p62 protects cells from death by binding ubiquitinated capsid and targeting it to autophagolysosomes. By contrast, the human autophagy receptor NDP52--but not its mouse orthologue--interacts with the non-structural protein nsP2, thereby promoting viral replication. These results highlight the distinct roles of p62 and NDP52 in viral infection, and identify NDP52 as a cellular factor that accounts for CHIKV species specificity.
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