Mycobacterium tuberculosis Mce3C promotes mycobacteria entry into macrophages through activation of β2 integrin‐mediated signalling pathway
Abstract
Establishment of infection by facultative intracellular pathogen Mycobacterium tuberculosis (Mtb) requires adherence to and internalisation by macrophages. However, the effector molecules exploited by Mtb for entry into macrophages remain to be fully understood. The mammalian cell entry (Mce) proteins play an essential role in facilitating the internalisation of mycobacteria into mammalian cells. Here, we characterized Mtb Mce3C as a new mycobacterial surface protein that could promote mycobacterial adhesion to and invasion of macrophages in an RGD motif‐dependent manner. We then further demonstrated that β2 in...
Source: Cellular Microbiology - November 24, 2017 Category: Microbiology Authors: Yong Zhang, Jie Li, Bingxi Li, Jing Wang, Cui Hua Liu Tags: RESEARCH ARTICLE Source Type: research
Lipocalin 2 (Lcn2) interferes with iron uptake by Brucella abortus and dampens immunoregulation during infection of RAW 264.7 macrophages
In this study, we report that Lcn2 is induced by Brucella (B.) abortus infection and significantly contributes to the restriction of intracellular survival of Brucella in macrophages. We found that Lcn2 prevented iron uptake by B. abortus through two distinct mechanisms. First, Lcn2 is secreted to capture bacterial siderophore(s) and abrogate iron import by Brucella. Second, Lcn2 decreases the intracellular iron levels during Brucella infection, which probably deprives the invading Brucella of the iron source needed for growth. Suppression of Lcn2 signaling resulted in a marked induction of anti‐inflammatory cytokine, in...
Source: Cellular Microbiology - November 23, 2017 Category: Microbiology Authors: Huynh Tan Hop, Lauren Togonon Arayan, Tran Xuan Ngoc Huy, Alisha Wehdnesday Bernardo Reyes, Eun Jin Baek, WonGi Min, Hu Jang Lee, Man Hee Rhee, Kenta Watanabe, Hong Hee Chang, Suk Kim Tags: RESEARCH ARTICLE Source Type: research
An Adherent Mucus Layer Attenuates the Genotoxic Effect of Colibactin
In this study, we used a variety of cell culture models, among them a 3D cell culture approach based on decellularized small intestinal submucosa, to investigate whether the intestinal mucus layer has the potential to interfere with colibactin activity. We demonstrate that the expression of mucins and the formation of an adherent mucus layer significantly increased with increasing complexity of cell culture. Moreover, we show that the presence of an adherent mucus layer on epithelial cells attenuates the genotoxic activity of colibactin, by preventing the induction of DNA‐DSBs. Removal of the adherent mucus layer restore...
Source: Cellular Microbiology - November 21, 2017 Category: Microbiology Authors: Christian Reuter, Mona Alzheimer, Heike Walles, Tobias A. Oelschlaeger Tags: RESEARCH ARTICLE Source Type: research
Modeling Persistent Mycoplasma pneumoniae Infection of Human Airway Epithelium
SUMMARY
Mycoplasma pneumoniae is a human respiratory tract pathogen causing acute and chronic airway disease states that can include long‐term carriage and extra‐pulmonary spread. The mechanisms of persistence and migration beyond the conducting airways, however, remain poorly understood. We previously described an acute exposure model using normal human bronchial epithelium (NHBE) in air‐liquid interface culture, showing that M. pneumoniae gliding motility is essential for initial colonization and subsequent spread, including localization to epithelial cell junctions. We extended those observations here, characteriz...
Source: Cellular Microbiology - November 20, 2017 Category: Microbiology Authors: Oliver A. Prince, Thomas M. Krunkosky, Edward S. Sheppard, Duncan C. Krause Tags: RESEARCH ARTICLE Source Type: research
Activation of lpxR gene through enterohaemorrhagic Escherichia coli virulence regulators mediates lipid A modification to attenuate innate immune response
Abstract
During the course of infection, pathogens must overcome a variety of host defence systems. Modulation of lipid A, which is a strong stimulant for host immune systems, is one of the strategies used by microorganisms to evade the host response. The lpxR gene, which encodes a lipid A 3′‐O‐deacylase, is commonly found in several pathogens and has been shown to reduce the inflammatory response. Here, we demonstrated that the lpxR gene of enterohaemorrhagic Escherichia coli (EHEC) was positively regulated by two virulence regulators, Pch and Ler, and that this regulation was coordinated with the locus of enterocyt...
Source: Cellular Microbiology - November 17, 2017 Category: Microbiology Authors: Rikako Ogawa, Hilo Yen, Kiyoshi Kawasaki, Toru Tobe Tags: RESEARCH ARTICLE Source Type: research
M. tuberculosis Mce3C promotes mycobacteria entry into macrophages through activation of β2 integrin‐mediated signaling pathway
Abstract
Establishment of infection by facultative intracellular pathogen Mycobacterium tuberculosis (Mtb) requires adherence to and internalization by macrophages. However, the effector molecules exploited by Mtb for entry into macrophages remain to be fully understood. The mammalian cell entry (Mce) proteins play an essential role in facilitating the internalization of mycobacteria into mammalian cells. Here we characterized Mtb Mce3C as a new mycobacterial surface protein that could promote mycobacterial adhesion to and invasion of macrophages in an RGD motif‐dependent manner. We then further demonstrated that β2 int...
Source: Cellular Microbiology - November 10, 2017 Category: Microbiology Authors: Yong Zhang, Jie Li, Bingxi Li, Jing Wang, Cui Hua Liu Tags: RESEARCH ARTICLE Source Type: research
Issue Information
No abstract is available for this article. (Source: Cellular Microbiology)
Source: Cellular Microbiology - November 9, 2017 Category: Microbiology Tags: ISSUE INFORMATION Source Type: research
Chlamydia trachomatis regulates growth and development in response to host cell fatty acid availability in the absence of lipid droplets
Abstract
Chlamydia trachomatis (Ct) is a Gram‐negative obligate intracellular pathogen of humans that causes significant morbidity from sexually transmitted and ocular diseases globally. Ct acquires host fatty acids (FA) to meet the metabolic and growth requirements of the organism. Lipid droplets (LDs) are storehouses of FAs in host cells and have been proposed to be a source of FAs for the parasitophorous vacuole, termed inclusion, in which Ct replicates. Previously, cells devoid of LDs were shown to produce reduced infectious progeny at 24 hours post‐infection (hpi). Here, while we also found reduced progeny at 24 h...
Source: Cellular Microbiology - November 8, 2017 Category: Microbiology Authors: Manu Sharma, Maria A. Recuero ‐Checa, Francis Yue Fan, Deborah Dean Tags: RESEARCH ARTICLE Source Type: research
Targeting host mitochondria: a role for the Trypanosoma cruzi amastigote flagellum
Abstract
Trypanosoma cruzi is the kinetoplastid protozoan parasite that causes human Chagas disease, a chronic disease with complex outcomes including severe cardiomyopathy and sudden death. In mammalian hosts, T. cruzi colonizes a wide range of tissues and cell types where it replicates within the host cell cytoplasm. Like all intracellular pathogens, T. cruzi amastigotes must interact with its immediate host cell environment in a manner that facilitates access to nutrients and promotes a suitable niche for replication and survival. Although potentially exploitable to devise strategies for pathogen control, fundamental kn...
Source: Cellular Microbiology - November 8, 2017 Category: Microbiology Authors: Gaelle Lentini, Nicolas Dos Santos Pacheco, Barbara A. Burleigh Tags: BREAKING REPORT Source Type: research
Identification of GBF1 as a cellular factor required for Hepatitis E virus RNA replication
Abstract
The hepatitis E virus (HEV) genome is a single‐stranded, positive‐sense RNA that encodes three proteins including the ORF1 replicase. Mechanisms of HEV replication in host cells are unclear and only a few cellular factors involved in this step have been identified so far. Here, we used brefeldin A (BFA) that blocks the activity of the cellular Arf guanine nucleotide exchange factors GBF1, BIG1 and BIG2, which play a major role in reshuffling of cellular membranes. We showed that BFA inhibits HEV replication in a dose‐dependent manner. The use of siRNA and Golgicide A identified GBF1 as a host factor critical...
Source: Cellular Microbiology - November 7, 2017 Category: Microbiology Authors: Rayan Farhat, Maliki Ankavay, Nadjet Lebsir, J érôme Gouttenoire, Catherine L. Jackson, Czeslaw Wychowski, Darius Moradpour, Jean Dubuisson, Yves Rouille, Laurence Cocquerel Tags: RESEARCH ARTICLE Source Type: research
Live Faecalibacterium prausnitzii induces greater TLR2 and TLR2/6 activation than the dead bacterium in an apical anaerobic co ‐culture system
Abstract
Inappropriate activation of intestinal innate immune receptors, such as Toll‐like receptors (TLRs), by pathogenic bacteria is linked to chronic inflammation. In contrast, a ‘tonic’ level of TLR activation by commensal bacteria is required for intestinal homeostasis. A technical challenge when studying this activation in vitro is the co‐culturing of oxygen‐requiring mammalian cells with obligate anaerobic commensal bacteria. To overcome this, we used a novel apical anaerobic co‐culture system to successfully adapt a TLR activation assay to be conducted in conditions optimised for both cell types. Live F...
Source: Cellular Microbiology - November 7, 2017 Category: Microbiology Authors: Eva Maier, Rachel C. Anderson, Eric Altermann, Nicole C. Roy Tags: RESEARCH ARTICLE Source Type: research
Activation of lpxR gene through enterohemorrhagic Escherichia coli virulence regulators mediates lipid A modification to attenuate innate immune response
Abstract
During the course of infection, pathogens must overcome a variety of host defense systems. Modulation of lipid A, which is a strong stimulant for host immune systems, is one of the strategies used by microorganisms to evade the host response. The lpxR gene, which encodes a lipid A 3'‐O‐deacylase, is commonly found in several pathogens and has been shown to reduce the inflammatory response. Here, we demonstrated that the lpxR gene of enterohemorrhagic E. coli (EHEC) was positively regulated by two virulence regulators, Pch and Ler, and that this regulation was coordinated with the LEE genes, which encode major ...
Source: Cellular Microbiology - November 7, 2017 Category: Microbiology Authors: Rikako Ogawa, Hilo Yen, Kiyoshi Kawasaki, Toru Tobe Tags: RESEARCH ARTICLE Source Type: research
Cryptococcal dissemination to the central nervous system requires the vacuolar calcium transporter Pmc1
Abstract
Cryptococcus neoformans is a basidiomycetous yeast and the cause of cryptococcosis in immunocompromised individuals. The most severe form of the disease is meningoencephalitis, which is one of the leading cause of death in HIV/AIDS patients. In order to access the central nervous system (CNS), C. neoformans relies on the activity of certain virulence factors such as urease, which allows transmigration through the blood–brain barrier (BBB). In the present study, we demonstrate that the calcium transporter Pmc1 enables C. neoformans to penetrate the CNS, since the pmc1 null mutant failed to infect and to survive w...
Source: Cellular Microbiology - November 7, 2017 Category: Microbiology Authors: Eamim D. Squizani, Nat ália K. Oliveira, Júlia C.V. Reuwsaat, Bárbara M. Marques, William Lopes, Alexandra L. Gerber, Ana Tereza R. Vasconcelos, Sophie Lev, Julianne T. Djordjevic, Augusto Schrank, Marilene H. Vainstein, Charley C. Staats, Lívia Kmetz Tags: RESEARCH ARTICLE Source Type: research
Toxoplasma gondii infection shifts dendritic cells into an amoeboid rapid migration mode encompassing podosome dissolution, secretion of TIMP ‐1 and reduced proteolysis of extracellular matrix
We report that increased TIMP‐1 secretion and cytoskeletal rearrangements encompassing podosome dissolution are features of Toxoplasma‐induced hypermigration of DCs with an impact on matrix degradation. Jointly, the data highlight how an obligate intracellular parasite orchestrates key regulatory cellular processes consistent with non‐proteolytic amoeboid migration of the vehicle cells that facilitate its dissemination. (Source: Cellular Microbiology)
Source: Cellular Microbiology - November 1, 2017 Category: Microbiology Authors: Einar B. Ólafsson, Manuel Varas‐Godoy, Antonio Barragan Tags: RESEARCH ARTICLE Source Type: research
PtaB, a lim ‐domain binding protein in Aspergillus fumigatus regulates biofilm formation and conidiation through distinct pathways
Abstract
The exopolysaccharide galactosaminogalactan (GAG) plays an important role in mediating adhesion, biofilm formation and virulence in the pathogenic fungus Aspergillus fumigatus. The developmental modifiers MedA, StuA and SomA regulate GAG biosynthesis, but the mechanisms underlying this regulation are poorly understood. PtaB is a lim‐domain binding protein that interacts with the transcription factor SomA and is required for normal conidiation and biofilm formation. Disruption of ptaB resulted in impaired GAG production and conidiation in association with a markedly reduced expression of GAG biosynthetic genes (u...
Source: Cellular Microbiology - November 1, 2017 Category: Microbiology Authors: Shizhu Zhang, Yuan Chen, Zhihua Ma, Qiuyi Chen, Hanna Ostapska, Fabrice N. Gravelat, Ling Lu, Donald C. Sheppard Tags: RESEARCH ARTICLE Source Type: research
