Cellular Microbiology最新文献

{"title":"Galectin-3 regulates proinflammatory cytokine function and favours Brucella abortus chronic replication in macrophages and mice","authors":"Fernanda L. Tana,&nbsp;Erika S. Guimarães,&nbsp;Daiane M. Cerqueira,&nbsp;Priscila C. Campos,&nbsp;Marco Túlio R. Gomes,&nbsp;Fábio V. Marinho,&nbsp;Sergio C. Oliveira","doi":"10.1111/cmi.13375","DOIUrl":"10.1111/cmi.13375","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>In this study, we provide evidence that galectin-3 (Gal-3) plays an important role in <i>Brucella abortus</i> infection. Our results showed increased Gal-3 expression and secretion in <i>B. abortus</i> infected macrophages and mice. Additionally, our findings indicate that Gal-3 is dispensable for <i>Brucella</i>-containing vacuoles disruption, inflammasome activation and pyroptosis. On the other hand, we observed that <i>Brucella</i>-induced Gal-3 expression is crucial for induction of molecules associated to type I IFN signalling pathway, such as IFN-β: Interferon beta (IFN-β), C-X-C motif chemokine ligand 10 (CXCL10) and guanylate-binding proteins. Gal-3 KO macrophages showed reduced bacterial numbers compared to wild-type cells, suggesting that Gal-3 facilitates bacterial replication in vitro. Moreover, priming Gal-3 KO cells with IFN-β favoured <i>B. abortus</i> survival in macrophages. Additionally, we also observed that Gal-3 KO mice are more resistant to <i>B. abortus</i> infection and these animals showed elevated production of proinflammatory cytokines when compared to control mice. Finally, we observed an increased recruitment of macrophages, dendritic cells and neutrophils in spleens of Gal-3 KO mice compared to wild-type animals. In conclusion, this study demonstrated that <i>Brucella</i>-induced Gal-3 is detrimental to host and this molecule is implicated in inhibition of recruitment and activation of immune cells, which promotes <i>B. abortus</i> spread and aggravates the infection.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Take Aways</h3>\u0000 \u0000 <div>\u0000 <ul>\u0000 \u0000 <li><i>Brucella abortus</i> infection upregulates galectin-3 expression</li>\u0000 \u0000 <li>Galectin-3 regulates guanylate-binding proteins expression but is not required for <i>Brucella</i>-containing vacuole disruption</li>\u0000 \u0000 <li>Galectin-3 modulates proinflammatory cytokine production during bacterial infection</li>\u0000 \u0000 <li>Galectin-3 favours <i>Brucella</i> replication</li>\u0000 </ul>\u0000 </div>\u0000 </section>\u0000 </div>","PeriodicalId":9844,"journal":{"name":"Cellular Microbiology","volume":"23 10","pages":""},"PeriodicalIF":3.4,"publicationDate":"2021-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/cmi.13375","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39105786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Single-cell analyses reveal phosphate availability as critical factor for nutrition of Salmonella enterica within mammalian host cells","authors":"Jennifer Röder,&nbsp;Pascal Felgner,&nbsp;Michael Hensel","doi":"10.1111/cmi.13374","DOIUrl":"10.1111/cmi.13374","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;p&gt;&lt;i&gt;Salmonella enterica&lt;/i&gt; serovar Typhimurium (STM) is an invasive, facultative intracellular pathogen and acquisition of nutrients from host cells is essential for survival and proliferation of intracellular STM. The nutritional environment of intracellular STM is only partially understood. We deploy bacteria harbouring reporter plasmids to interrogate the environmental cues acting on intracellular STM, and flow cytometry allows analyses on level of single STM. Phosphorus is a macro-element for cellular life, and in STM inorganic phosphate (P&lt;sub&gt;i&lt;/sub&gt;), homeostasis is mediated by the two-component regulatory system PhoBR, resulting in expression of the high affinity phosphate transporter &lt;i&gt;pstSCAB-phoU&lt;/i&gt;. Using fluorescent protein reporters, we investigated P&lt;sub&gt;i&lt;/sub&gt; availability for intracellular STM at single-cell level over time. We observed that P&lt;sub&gt;i&lt;/sub&gt; concentration in the &lt;i&gt;Salmonella&lt;/i&gt;-containing vacuole (SCV) is limiting and activates the promoter of &lt;i&gt;pstSCAB-phoU&lt;/i&gt; encoding a high affinity phosphate uptake system. Correlation between reporter activation by STM in defined media and in host cells indicates P&lt;sub&gt;i&lt;/sub&gt; concentration less 10 μM within the SCV. STM proliferating within the SCV experience increasing P&lt;sub&gt;i&lt;/sub&gt; limitations. Activity of the &lt;i&gt;Salmonella&lt;/i&gt; pathogenicity island 2 (SPI2)-encoded type III secretion system (T3SS) is crucial for efficient intracellular proliferation, and SPI2-T3SS-mediated endosomal remodelling also reliefs P&lt;sub&gt;i&lt;/sub&gt; limitation. STM that are released from SCV to enter the cytosol of epithelial cells did not indicate P&lt;sub&gt;i&lt;/sub&gt; limitations. Addition of P&lt;sub&gt;i&lt;/sub&gt; to culture media of infected cells partially relieved P&lt;sub&gt;i&lt;/sub&gt; limitations in the SCV, as did inhibition of intracellular proliferation. We conclude that availability of P&lt;sub&gt;i&lt;/sub&gt; is critical for intracellular lifestyle of STM, and P&lt;sub&gt;i&lt;/sub&gt; acquisition is maintained by multiple mechanisms. Our work demonstrates the use of bacterial pathogens as sensitive single-cell reporters for their environment in host cell or host organisms.&lt;/p&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Take Away&lt;/h3&gt;\u0000 \u0000 &lt;div&gt;\u0000 &lt;ul&gt;\u0000 \u0000 &lt;li&gt;&lt;i&gt;Salmonella&lt;/i&gt; strains were engineered to report their intracellular niche and the availability of inorganic phosphate (P&lt;sub&gt;i&lt;/sub&gt;) on level of single intracellular bacteria&lt;/li&gt;\u0000 \u0000 &lt;li&gt;Within the &lt;i&gt;Salmonella&lt;/i&gt;-containing vacuole (SCV), P&lt;sub&gt;i&lt;/sub&gt; is limited and limitation increases with bacterial proliferation&lt;/li&gt;\u0000 \u0000 &lt;li&gt;&lt;i&gt;Salmonella&lt;/i&gt; located in host cell cytosol are not limited in P&lt;sub&gt;i&lt;/sub&gt; availability&lt;/li&gt;\u0000 \u0000 &lt;li&gt;R","PeriodicalId":9844,"journal":{"name":"Cellular Microbiology","volume":"23 10","pages":""},"PeriodicalIF":3.4,"publicationDate":"2021-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/cmi.13374","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39098982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Emerging methods in cellular microbiology","authors":"Elizabeth L. Hartland","doi":"10.1111/cmi.13369","DOIUrl":"10.1111/cmi.13369","url":null,"abstract":"&lt;p&gt;In an era where new viruses can emerge suddenly and anti-microbial resistance is now widespread, a full understanding of the pathogen and host factors that contribute to disease pathology and spread remains a critically important goal. Methods and technologies to study the cell biology of infection are changing rapidly. The interdisciplinary requirements to interrogate host-pathogen interactions are ever more complex and indispensable to identify the cellular and immune factors that lead to the resolution of infection. The ability of a pathogen to replicate in the host likewise needs a thorough knowledge of the pathogen determinants required to cause disease. In this special issue, &lt;i&gt;Cellular Microbiology&lt;/i&gt; highlights some of the most cutting-edge approaches and techniques to study pathogen biology and infection.&lt;/p&gt;&lt;p&gt;Light based and electron microscopic imaging has long played an important role in defining the intracellular mechanisms of infection. Such methods can now be quickly adapted through the design of fluorescent reporters and utilised for high throughout applications. Cortese and Laketa &lt;span&gt;(2021)&lt;/span&gt; describe recent advances in high-throughput microscopy and electron microscopy and explain how these were applied during the SARS-CoV-2 outbreak (Cortese &amp; Laketa, &lt;span&gt;2021&lt;/span&gt;). For example, the development of a mNeonGreen reporter microscopy-based virus neutralisation assay outperformed standard plaque assays in sensitivity and time in the critical early stages of the COVID-19 pandemic (Muruato et al., &lt;span&gt;2020&lt;/span&gt;). Cryo-electron microscopy was instrumental in rapidly defining the structure of the SARS-CoV-2 spike protein in complex with its cellular receptor, angiotensin convertase enzyme 2 (ACE2), directly informing an understanding of neutralising antibodies (Cortese &amp; Laketa, &lt;span&gt;2021&lt;/span&gt;). In bacterial pathogens, Dufrêne, Viljoen, Mignolet, and Mathelié-Guinlet (&lt;span&gt;2021&lt;/span&gt;) report on the utility of atomic force microscopy (AFM) to provide super-resolution imaging and nanomechanical measurements of bacterial cell surfaces and receptor-ligand interactions. This is providing new insight into the fine structure and biophysical function of adhesins and also informing vaccine and drug development (Dufrêne et al., &lt;span&gt;2021&lt;/span&gt;).&lt;/p&gt;&lt;p&gt;The subcellular host cell compartment occupied by intracellular pathogens is highly specialised to support pathogen replication. Given their role in sampling of extracellular fluid, macropinosomes are hijacked by diverse pathogens to establish entry into the intracellular environment. However, macropinosomes are also highly dynamic organelles with a range of cellular functions. Chang, Enninga, and Stévenin &lt;span&gt;(2021)&lt;/span&gt; describe imaging-based and proteomic methods for the tracking and characterisation of these important organelles as they are modified as a niche for invasion and/or replication by bacteria such as &lt;i&gt;Shigella&lt;/i&gt;, &lt;i&gt;Salmonella&lt;/i&gt;, &lt;i&gt;Bruc","PeriodicalId":9844,"journal":{"name":"Cellular Microbiology","volume":"23 7","pages":""},"PeriodicalIF":3.4,"publicationDate":"2021-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/cmi.13369","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39099817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Syncollin is an antibacterial polypeptide","authors":"Rosie A. Waters,&nbsp;James Robinson,&nbsp;J. Michael Edwardson","doi":"10.1111/cmi.13372","DOIUrl":"10.1111/cmi.13372","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>Syncollin is a 16-kDa protein found predominantly in the zymogen granules of pancreatic acinar cells, with expression at lower levels in intestinal epithelial cells and neutrophils. Here, we used Strep-tagged syncollin isolated from the supernatant of transiently transfected mammalian cells to test the hypothesis that syncollin has antibacterial properties, which might enable it to play a role in host defence in the gut and possibly elsewhere. We show that syncollin is an exceptionally thermostable protein with a circular dichroism spectrum consistent with a predominantly beta-sheet structure. Syncollin binds to bacterial peptidoglycan and restricts the growth of representative Gram-positive (<i>Lactococcus lactis</i>) and Gram-negative (<i>Escherichia coli</i>) bacteria. Syncollin induces propidium iodide uptake into <i>E. coli</i> (but not <i>L. lactis</i>), indicating permeabilisation of the bacterial membrane. It also causes surface structural damage in both <i>L. lactis</i> and <i>E. coli</i>, as visualised by scanning electron microscopy. We propose that syncollin is a previously unidentified member of a large group of antimicrobial polypeptides that control the gut microbiome.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Take Aways</h3>\u0000 \u0000 <div>\u0000 <ul>\u0000 \u0000 <li>Syncollin is a 16-kDa protein found in pancreatic zymogen granules.</li>\u0000 \u0000 <li>Syncollin is highly thermostable and has a predominantly beta-sheet structure.</li>\u0000 \u0000 <li>Syncollin binds peptidoglycan and restricts the growth of <i>L. lactis</i> and <i>E. coli</i>.</li>\u0000 \u0000 <li>Syncollin causes propidium iodide uptake into <i>E. coli</i> (but not <i>L. lactis</i>).</li>\u0000 \u0000 <li>Syncollin causes surface structural damage in both <i>L. lactis</i> and <i>E. coli</i>.</li>\u0000 </ul>\u0000 </div>\u0000 </section>\u0000 </div>","PeriodicalId":9844,"journal":{"name":"Cellular Microbiology","volume":"23 10","pages":""},"PeriodicalIF":3.4,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/cmi.13372","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39258157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inflammasome activation and IL-1β signalling in group A Streptococcus disease","authors":"Johanna Richter,&nbsp;Stephan Brouwer,&nbsp;Kate Schroder,&nbsp;Mark J. Walker","doi":"10.1111/cmi.13373","DOIUrl":"10.1111/cmi.13373","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>Group A <i>Streptococcus</i> (GAS) is a Gram-positive bacterial pathogen that causes significant morbidity and mortality worldwide. Recent clinical evidence suggests that the inflammatory marker interleukin-1β (IL-1β) plays an important role in GAS disease progression, and presents a potential target for therapeutic intervention. Interaction with GAS activates the host inflammasome pathway to stimulate production and secretion of IL-1β, but GAS can also stimulate IL-1β production in an inflammasome-independent manner. This review highlights progress that has been made in understanding the importance of host cell inflammasomes and IL-1 signalling in GAS disease, and explores challenges and unsolved problems in this host-pathogen interaction.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Take Away</h3>\u0000 \u0000 <div>\u0000 <ul>\u0000 \u0000 <li>Inflammasome signalling during GAS infection is an emerging field of research.</li>\u0000 \u0000 <li>GAS modulates the NLRP3 inflammasome pathway through multiple mechanisms.</li>\u0000 \u0000 <li>SpeB contributes to IL-1β production independently of the inflammasome pathway.</li>\u0000 \u0000 <li>IL-1β signalling can be host-protective, but also drive severe GAS disease.</li>\u0000 </ul>\u0000 </div>\u0000 </section>\u0000 </div>","PeriodicalId":9844,"journal":{"name":"Cellular Microbiology","volume":"23 9","pages":""},"PeriodicalIF":3.4,"publicationDate":"2021-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/cmi.13373","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39095839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A putative PKA phosphorylation site S227 in MoSom1 is essential for infection-related morphogenesis and pathogenicity in Magnaporthe oryzae","authors":"Shuzhen Deng,&nbsp;Lin Xu,&nbsp;Zhe Xu,&nbsp;Wuyun Lv,&nbsp;Zhengxian Chen,&nbsp;Nan Yang,&nbsp;Nicholas J. Talbot,&nbsp;Zhengyi Wang","doi":"10.1111/cmi.13370","DOIUrl":"10.1111/cmi.13370","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>In the rice blast fungus <i>Magnaporthe oryzae</i>, the cAMP signalling pathway plays a critical role in regulating leaf surface recognition and the initiation of appressorium development. Direct downstream targets of the cAMP signalling pathway are, however, not well-characterised. The MoSom1 protein functions downstream of the cAMP dependent protein kinase A (cAMP-PKA) and is essential for infection-related morphogenesis and pathogenicity. In this study, we show that mutation of a putative PKA phosphorylation site in MoSom1 is essential for its role in appressorium differentiation and pathogenicity in <i>M. oryzae</i>. Mutation of serine 227 in MoSom1 by deletion or serine (S) substitution to alanine (A), valine (V) or tyrosine (Y), resulted in defects of conidiation, appressorium-like structure formation and fungal pathogenicity. Western blot analysis confirmed that S227 in MoSom1 is a putative PKA phosphorylation site. Furthermore, a <i>ΔMosom1</i> mutant showed reduced expression of <i>PMK1</i> and was defective in Pmk1 phosphorylation, indicating that the Pmk1 mitogen-activated protein kinase (MAPK) acts downstream of MoSom1 in <i>M. oryzae</i>. We conclude that the cAMP-PKA pathway may regulate the Pmk1 MAPK pathway through MoSom1 during rice infection by the blast fungus.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Take Aways</h3>\u0000 \u0000 <div>\u0000 <ul>\u0000 \u0000 <li>S227 is crucial for MoSom1 function in <i>M. oryzae</i>.</li>\u0000 \u0000 <li>S227 in MoSom1 was identified as a putative PKA phosphorylation site in <i>M. oryzae</i>.</li>\u0000 \u0000 <li>S227 is essential for infection-related morphogenesis and pathogenicity in <i>M. oryzae</i>.</li>\u0000 </ul>\u0000 </div>\u0000 </section>\u0000 </div>","PeriodicalId":9844,"journal":{"name":"Cellular Microbiology","volume":"23 10","pages":""},"PeriodicalIF":3.4,"publicationDate":"2021-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/cmi.13370","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39064388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Candidalysin triggers epithelial cellular stresses that induce necrotic death","authors":"Mariana Blagojevic,&nbsp;Giorgio Camilli,&nbsp;Michelle Maxson,&nbsp;Bernhard Hube,&nbsp;David L. Moyes,&nbsp;Jonathan P. Richardson,&nbsp;Julian R. Naglik","doi":"10.1111/cmi.13371","DOIUrl":"10.1111/cmi.13371","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p><i>Candida albicans</i> is a common opportunistic fungal pathogen that causes a wide range of infections from superficial mucosal to hematogenously disseminated candidiasis. The hyphal form plays an important role in the pathogenic process by invading epithelial cells and causing tissue damage. Notably, the secretion of the hyphal toxin candidalysin is essential for both epithelial cell damage and activation of mucosal immune responses. However, the mechanism of candidalysin-induced cell death remains unclear. Here, we examined the induction of cell death by candidalysin in oral epithelial cells. Fluorescent imaging using healthy/apoptotic/necrotic cell markers revealed that candidalysin causes a rapid and marked increase in the population of necrotic rather than apoptotic cells in a concentration dependent manner. Activation of a necrosis-like pathway was confirmed since <i>C. albicans</i> and candidalysin failed to activate caspase-8 and -3, or the cleavage of poly (ADP-ribose) polymerase. Furthermore, oral epithelial cells treated with candidalysin showed rapid production of reactive oxygen species, disruption of mitochondria activity and mitochondrial membrane potential, ATP depletion and cytochrome c release. Collectively, these data demonstrate that oral epithelial cells respond to the secreted fungal toxin candidalysin by triggering numerous cellular stress responses that induce necrotic death.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Take aways</h3>\u0000 \u0000 <div>\u0000 <ul>\u0000 \u0000 <li>Candidalysin secreted from <i>Candida albicans</i> causes epithelial cell stress.</li>\u0000 \u0000 <li>Candidalysin induces calcium influx and oxidative stress in host cells.</li>\u0000 \u0000 <li>Candidalysin induces mitochondrial dysfunction, ATP depletion and epithelial necrosis.</li>\u0000 \u0000 <li>The toxicity of candidalysin is mediated from the epithelial cell surface.</li>\u0000 </ul>\u0000 </div>\u0000 </section>\u0000 </div>","PeriodicalId":9844,"journal":{"name":"Cellular Microbiology","volume":"23 10","pages":""},"PeriodicalIF":3.4,"publicationDate":"2021-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/cmi.13371","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39076404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genome-wide genetic screen identifies host ubiquitination as important for Legionella pneumophila Dot/Icm effector translocation","authors":"Sze Ying Ong,&nbsp;Ralf Schuelein,&nbsp;Rachelia R. Wibawa,&nbsp;Daniel W. Thomas,&nbsp;Yanny Handoko,&nbsp;Saskia Freytag,&nbsp;Melanie Bahlo,&nbsp;Kaylene J. Simpson,&nbsp;Elizabeth L. Hartland","doi":"10.1111/cmi.13368","DOIUrl":"10.1111/cmi.13368","url":null,"abstract":"<p>The Dot/Icm system of <i>Legionella pneumophila</i> is essential for virulence and delivers a large repertoire of effectors into infected host cells to create the <i>Legionella</i> containing vacuole. Since the secretion of effectors via the Dot/Icm system does not occur in the absence of host cells, we hypothesised that host factors actively participate in Dot/Icm effector translocation. Here we employed a high-throughput, genome-wide siRNA screen to systematically test the effect of silencing 18,120 human genes on translocation of the Dot/Icm effector, RalF, into HeLa cells. For the primary screen, we found that silencing of 119 genes led to increased translocation of RalF, while silencing of 321 genes resulted in decreased translocation. Following secondary screening, 70 genes were successfully validated as ‘high confidence’ targets. Gene set enrichment analysis of siRNAs leading to decreased RalF translocation, showed that ubiquitination was the most highly overrepresented category in the pathway analysis. We further showed that two host factors, the E2 ubiquitin-conjugating enzyme, UBE2E1, and the E3 ubiquitin ligase, CUL7, were important for supporting Dot/Icm translocation and <i>L. pneumophila</i> intracellular replication. In summary, we identified host ubiquitin pathways as important for the efficiency of Dot/Icm effector translocation by <i>L. pneumophila</i>, suggesting that host-derived ubiquitin-conjugating enzymes and ubiquitin ligases participate in the translocation of <i>Legionella</i> effector proteins and influence intracellular persistence and survival.</p>","PeriodicalId":9844,"journal":{"name":"Cellular Microbiology","volume":"23 10","pages":""},"PeriodicalIF":3.4,"publicationDate":"2021-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/cmi.13368","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39023821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Recombinant IL-22 promotes protection in a murine model of Aspergillus flavus keratitis and mediates host immune responses in human corneal epithelial cells","authors":"Lakshmi Sruthi Mallela,&nbsp;Prerana Sharma,&nbsp;Tata Santosh RamaBhadra Rao,&nbsp;Sanhita Roy","doi":"10.1111/cmi.13367","DOIUrl":"10.1111/cmi.13367","url":null,"abstract":"<p><i>Aspergillus flavus</i> is a leading cause of corneal infections in India and worldwide, resulting in severe visual impairment. We studied the host immune response towards <i>A. flavus</i> in immortalised human corneal epithelial cells (HCEC) and found increased expression of Toll-like receptors, antimicrobial peptides and proinflammatory cytokines like IL-6 and IL-8. Differential expressions of antimicrobial peptides were determined in corneal scrapings from <i>A. flavus</i> keratitis patients with significantly increased expression of LL-37, S100A12 and RNase 7. Increased levels of IL-22 expression were observed both in patients with <i>A. flavus</i> keratitis and in experimental mice model of corneal infections along with IL-17, IL-23 and IL-18. IL-22 is an important mediator of inflammation during microbial infections, and acts primarily on fibroblasts and epithelial cells. We observed constitutive expression of IL-22 receptors in HCEC, and IL-22 mediated activation of NF-κB, MAPK pathways and STAT3, along with increased expression of antimicrobial peptides in these cells. IL-22 also efficiently lessened cell deaths in corneal epithelial cells during <i>A. flavus</i> infection in vitro. Furthermore, recombinant IL-22 reduced fungal burden and corneal opacity in an experimental murine model of <i>A. flavus</i> keratitis.</p>","PeriodicalId":9844,"journal":{"name":"Cellular Microbiology","volume":"23 9","pages":""},"PeriodicalIF":3.4,"publicationDate":"2021-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/cmi.13367","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39013774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The type III secretion system effector EspO of enterohaemorrhagic Escherichia coli inhibits apoptosis through an interaction with HAX-1","authors":"Sharanya Chatterjee,&nbsp;Sujinna Lekmeechai,&nbsp;Nicolas Constantinou,&nbsp;Ewa A. Grzybowska,&nbsp;Zuzanna Kozik,&nbsp;Jyoti S. Choudhary,&nbsp;Cedric N. Berger,&nbsp;Gad Frankel,&nbsp;Abigail Clements","doi":"10.1111/cmi.13366","DOIUrl":"10.1111/cmi.13366","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <p>Many enteric pathogens employ a type III secretion system (T3SS) to translocate effector proteins directly into the host cell cytoplasm, where they subvert signalling pathways of the intestinal epithelium. Here, we report that the anti-apoptotic regulator HS1-associated protein X1 (HAX-1) is an interaction partner of the T3SS effectors EspO of enterohaemorrhagic <i>Escherichia coli</i> (EHEC) and <i>Citrobacter rodentium</i>, OspE of <i>Shigella flexneri</i> and Osp1_STYM of <i>Salmonella enterica</i> serovar Typhimurium. EspO, OspE and Osp1_STYM have previously been reported to interact with the focal adhesions protein integrin linked kinase (ILK). We found that EspO localizes both to the focal adhesions (ILK localisation) and mitochondria (HAX-1 localisation), and that increased expression of HAX-1 leads to enhanced mitochondrial localisation of EspO. Ectopic expression of EspO, OspE and Osp1_STYM protects cells from apoptosis induced by staurosporine and tunicamycin. Depleting cells of HAX-1 indicates that the anti-apoptotic activity of EspO is HAX-1 dependent. Both HAX-1 and ILK were further confirmed as EspO1-interacting proteins during infection using T3SS-delivered EspO1. Using cell detachment as a proxy for cell death we confirmed that T3SS-delivered EspO1 could inhibit cell death induced during EPEC infection, to a similar extent as the anti-apoptotic effector NleH, or treatment with the pan caspase inhibitor z-VAD. In contrast, in cells lacking HAX-1, EspO1 was no longer able to protect against cell detachment, while NleH1 and z-VAD maintained their protective activity. Therefore, during both infection and ectopic expression EspO protects cells from cell death by interacting with HAX-1. These results suggest that despite the differences between EHEC, <i>C</i>. <i>rodentium</i>, <i>Shigella</i> and <i>S</i>. <i>typhimurium</i> infections, hijacking HAX-1 anti-apoptotic signalling is a common strategy to maintain the viability of infected cells.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Take Away</h3>\u0000 \u0000 <div>\u0000 <ul>\u0000 \u0000 <li>EspO homologues are found in EHEC, <i>Shigella</i>, <i>S</i>. <i>typhimurium</i> and some EPEC.</li>\u0000 \u0000 <li>EspO homologues interact with HAX-1.</li>\u0000 \u0000 <li>EspO protects infected cells from apoptosis.</li>\u0000 \u0000 <li>EspO joins a growing list of T3SS effectors that manipulate cell death pathways.</li>\u0000 </ul>\u0000 </div>\u0000 </section>\u0000 </div>","PeriodicalId":9844,"journal":{"name":"Cellular Microbiology","volume":"23 9","pages":""},"PeriodicalIF":3.4,"publicationDate":"2021-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/cmi.13366","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"39007994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}