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Cellular Microbiology

Xiaoye Liu, Shuangyang Ding, Peijie Shi, Richard Dietrich, Erwin Märtlbauer, Kui Zhu
Bacillus cereus is an opportunistic pathogen that often causes foodborne infectious diseases and food poisoning. Non-haemolytic enterotoxin (Nhe) is the major toxin found in almost all enteropathogenic B. cereus and B. thuringiensis isolates. However, little is known about the cellular response after Nhe triggered pore formation on cell membrane. Here we demonstrate that Nhe induced cell cycle arrest at G0 /G1 phase and provoked apoptosis in Vero cells, most likely associated with mitogen-activated protein kinase (MAPK) and death receptor pathways...
October 20, 2016: Cellular Microbiology
Julien Karim Malet, Pascale Cossart, David Ribet
Bacterial pathogens can interfere during infection with host cell organelles, such as mitochondria, the endoplasmic reticulum-Golgi system or nuclei. As important cellular functions are often compartmentalized in these organelles, their targeting allows pathogens to manipulate key host functions during infection. Here, we identify lysosomes as a new class of organelles targeted by the pathogenic bacterium Listeria monocytogenes. We demonstrate that extracellular Listeria, via secretion of the pore-forming toxin Listeriolysin O (LLO), alter lysosomal integrity in epithelial cells, but not in macrophages...
October 14, 2016: Cellular Microbiology
Meghan Zuck, Tisha Ellis, Anthony Venida, Kevin Hybiske
The precise strategies that intracellular pathogens use to exit host cells have a direct impact on their ability to disseminate within a host, transmit to new hosts, and engage or avoid immune responses. The obligate intracellular bacterium Chlamydia trachomatis exits the host cell by two distinct exit strategies, lysis and extrusion. The defining characteristics of extrusions, and advantages gained by Chlamydia within this unique double-membrane structure are not well understood. Here, we define extrusions as being largely devoid of host organelles, comprised mostly of Chlamydia elementary bodies, and containing phosphatidylserine on the outer surface of the extrusion membrane...
October 14, 2016: Cellular Microbiology
Lilian Pereira Silva, Patrícia Alves de Castro, Thaila Fernanda Dos Reis, Mario Henrique Paziani, Márcia Regina Von Zeska Kress, Diego M Riaño-Pachón, Daisuke Hagiwara, Laure N A Ries, Neil Andrew Brown, Gustavo H Goldman
Invasive aspergillosis is predominantly caused by Aspergillus fumigatus and adaptations to stresses experienced within the human host are a prerequisite for the survival and virulence strategies of the pathogen. The central signal transduction pathway operating during hyperosmotic stress is the High Osmolarity Glycerol mitogen-activated protein kinase (MAPK) cascade. A. fumigatus MpkC and SakA, orthologues of the Saccharomyces cerevisiae Hog1p, constitute the primary regulator of the hyperosmotic stress response...
October 5, 2016: Cellular Microbiology
Alexandra Vergnes, Julie P M Viala, Rabah Ouadah-Tsabet, Bérengère Pocachard, Laurent Loiseau, Stéphane Méresse, Frédéric Barras, Laurent Aussel
Iron-sulfur (Fe-S)-containing proteins contribute to various biological processes, including redox reactions or regulation of gene expression. Living organisms have evolved by developing distinct biosynthetic pathways to assemble these clusters, including ISC (Iron Sulfur Cluster) and SUF (Sulfur mobilization). Salmonella enterica serovar Typhimurium is an intracellular pathogen responsible for a wide range of infections, from gastroenteritis to severe systemic diseases. Salmonella possesses all known prokaryotic systems to assemble Fe-S clusters, including ISC and SUF...
October 5, 2016: Cellular Microbiology
Chris T Höfer, Fabian Jolmes, Ivan Haralampiev, Michael Veit, Andreas Herrmann
The Influenza A virus nucleoprotein (NP) is the major protein component of the genomic viral ribonucleoprotein (vRNP) complexes, which are the replication- and transcription-competent units of Influenza viruses. Early during infection, NP mediates import of vRNPs into the host cell nucleus where viral replication and transcription take place; also newly synthesized NP molecules are targeted into the nucleus, enabling coreplicational assembly of progeny vRNPs. NP reportedly acts as regulatory factor during infection, and it is known to be involved in numerous interactions with host cell proteins...
October 3, 2016: Cellular Microbiology
Allan L Chen, Andy S Moon, Hannah N Bell, Amy S Huang, Ajay A Vashisht, Justin Y Toh, Andrew H Lin, Santhosh M Nadipuram, Elliot W Kim, Charles P Choi, James A Wohlschlegel, Peter J Bradley
The Toxoplasma inner membrane complex (IMC) is a specialized organelle underlying the parasite's plasma membrane that consists of flattened rectangular membrane sacs that are sutured together and positioned atop a supportive cytoskeleton. We have previously identified a novel class of proteins localizing to the transverse and longitudinal sutures of the IMC, which we named ISCs. Here we have used proximity-dependent biotin identification (BioID) at the sutures to better define the composition of this IMC subcompartment...
October 1, 2016: Cellular Microbiology
Dalila Mil-Homens, Sandra N Pinto, Rute G Matos, Cecília Arraiano, Arsenio M Fialho
Chronic lung disease caused by persistent bacterial infections is a major cause of morbidity and mortality in patients with cystic fibrosis (CF). CF pathogens acquire antibiotic resistance, overcame host defenses and impose uncontrolled inflammation that ultimately may cause permanent damage of lungs' airways. Among the multiple CF-associated pathogens, Burkholderia cenocepacia and other B. cepacia complex (Bcc) bacteria have become prominent contributors of disease progression. Here, we demonstrate that BcaA, a trimeric autotransporter adhesin (TAA) from the epidemic strain B...
September 29, 2016: Cellular Microbiology
Nichole Orench-Rivera, Meta Kuehn
Over the past two decades, researchers studying both microbial and host cell communities have gained an appreciation for the ability of bacteria to produce, regulate, and functionally utilize outer membrane vesicles (OMVs) as a means to survive and interact with their cellular and acellular environments. Common ground has emerged, as it appears that vesicle production is an environmentally-controlled and specific secretion process, however it has been challenging to discover the principles that govern fundamentals of vesicle-mediated transport...
September 27, 2016: Cellular Microbiology
Sanjiveeni Dhamgaye, Yue Qu, Anton Y Peleg
Interactions between fungi and bacteria and their relevance to human health and disease have recently attracted increased attention in biomedical fields. Emerging evidence shows that bacteria and fungi can have synergistic or antagonistic interactions, each with important implications for human colonization and disease. It is now appreciated that some of these interactions may be strategic, and help promote the survival of one or both microorganisms within the host. This review will shed light on clinically relevant interactions between fungi and Gram-negative bacteria...
September 25, 2016: Cellular Microbiology
Hung-Yu Sun, Chun-Chieh Lin, Pei-Ju Tsai, Wei-Jen Tsai, Jin-Ching Lee, Chiung-Wen Tsao, Pin-Nan Cheng, I-Chin Wu, Yen-Cheng Chiu, Ting-Tsung Chang, Kung-Chia Young
Lipoprotein lipase (LPL) has been identified as an anti-HCV host factor, but the cellular mechanism remains elusive. Here, we investigated the cellular mechanism of LPL involving in anti-HCV. The functional activation of peroxisome proliferator-activated receptor (PPAR) α signal by LPL transducing into hepatocytes were investigated in HCV-infected cells, primary human heaptocytes (PHHs), and in HCV-core transgenic mice. The result showed that the levels of transcriptional transactivity and nuclear translocation of PPARα in Huh7 cells and PHHs were elevated by physiologically ranged LPL treatment of either very-low-density lipoprotein or HCV particles...
September 25, 2016: Cellular Microbiology
M I Ramirez, P Deolindo, I J de Messias-Reason, Emma A Arigi, H Choi, I C Almeida, I Evans-Osses
Extracellular vesicles (EVs) released from pathogens may alter host-cell functions. We previously demonstrated the involvement of host cell-derived microvesicles (MVs) during early interaction between Trypanosoma cruzi metacyclic trypomastigote (META) stage and THP-1 cells. Here, we aim to understand the contribution of different parasite stages and their EVs in the interaction with host cells. First, we observed that infective host cell-derived trypomastigote (TCT), META, and noninfective epimastigote (EPI) stages were able to induce different levels of MV release from THP-1 cells; however, only META and TCT could increase host-cell invasion...
September 25, 2016: Cellular Microbiology
Moona Huttunen, Paula Turkki, Anita Mäki, Lassi Paavolainen, Pekka Ruusuvuori, Varpu Marjomäki
We have demonstrated previously that the human picornavirus Echovirus 1 (EV1) triggers an infectious internalization pathway that follows closely, but seems to stay separate from the EGFR pathway triggered by EGF. Here we confirmed by using live and confocal microscopy that EGFR and EV1 vesicles are following intimately each other but are distinct entities with different degradation kinetics. We show here that despite being sorted to different pathways and located in distinct endosomes, EV1 inhibits EGFR down-regulation...
September 24, 2016: Cellular Microbiology
Shiladitya Chattopadhyay, Arpita Mukherjee, Upayan Patra, Rahul Bhowmick, Trayambak Basak, Shantanu Sengupta, Mamta Chawla-Sarkar
Phosphoproteomics-based platforms have been widely used to identify post translational dynamics of cellular proteins in response to viral infection. The present study was undertaken to assess differential tyrosine phosphorylation during early hours of rotavirus (RV) SA11 infection. Heat shock proteins (Hsp60) were found to be enriched in the data set of RV-SA11 induced differentially tyrosine-phosphorylated proteins at 2 hr post infection (hpi). Hsp60 was further found to be phosphorylated by an activated form of Src kinase on 227th tyrosine residue, and tyrosine phosphorylation of mitochondrial chaperonin Hsp60 correlated with its proteasomal degradation at 2-2...
September 24, 2016: Cellular Microbiology
Jane H Kinnaird, Meetali Singh, Victoria Gillan, William Weir, Ewen Dd Calder, Isabel Hostettler, Utpal Tatu, Eileen Devaney, Brian R Shiels
HSP90 chaperones are essential regulators of cellular function, as they ensure the appropriate conformation of multiple key client proteins. Four HSP90 isoforms were identified in the protozoan parasite Theileria annulata. Partial characterisation was undertaken for three and localisation confirmed for cytoplasmic (TA12105); endoplasmic reticulum (TA06470) and apicoplast (TA10720) forms. ATPase activity and binding to the HSP90 inhibitor geldanamycin, were demonstrated for recombinant TA12105 and all three native forms could be isolated to varying extents by binding to geldanamycin beads...
September 20, 2016: Cellular Microbiology
Juliana Perrone Bezerra de Menezes, Amrita Koushik, Satarupa Das, Can Guven, Ariel Siegel, Maria Fernanda Laranjeira-Silva, Wolfgang Losert, Norma W Andrews
Leishmania is an intracellular protozoan parasite that causes a broad spectrum of clinical manifestations, ranging from self-healing skin lesions to fatal visceralizing disease. As the host cells of choice for all species of Leishmania, macrophages are critical for the establishment of infections. How macrophages contribute to parasite homing to specific tissues and how parasites modulate macrophage function are still poorly understood. In this study, we show that Leishmania amazonensis infection inhibits macrophage roaming motility...
September 18, 2016: Cellular Microbiology
Jennifer A Haworth, Howard F Jenkinson, Helen J Petersen, Catherine R Back, Jane L Brittan, Steve W Kerrigan, Angela H Nobbs
A range of Streptococcus bacteria are able to interact with blood platelets to form a thrombus (clot). Streptococcus gordonii is ubiquitous within the human oral cavity and amongst the common pathogens isolated from subjects with infective endocarditis. Two cell surface proteins, Hsa and Platelet adherence protein A (PadA), in S. gordonii mediate adherence and activation of platelets. In this study, we demonstrate that PadA binds activated platelets and that an NGR (Asparagine-Glycine-Arginine) motif within a 657 amino acid residue N-terminal fragment of PadA is responsible for this, together with two other integrin-like recognition motifs RGT and AGD...
September 11, 2016: Cellular Microbiology
Takeshi Yamamoto, Yutaka Kida, Yuichi Sakamoto, Koichi Kuwano
Neutrophils play an important role in antimicrobial defense as the first line of innate immune system. Recently, the release of neutrophil extracellular traps (NETs) has been identified as a killing mechanism of neutrophils against invading microbes. Mycoplasma pneumoniae, a causative agent of respiratory infection, has been shown to be resistant to in vitro killing by neutrophils, suggesting that the bacterium might circumvent bactericidal activity of NETs. In this study, we investigated whether M. pneumoniae possesses resistance mechanisms against the NETs-mediated killing of neutrophils and found that the bacterium degrades the NETs induced upon M...
September 7, 2016: Cellular Microbiology
Christine Henry, Thierry Fontaine, Christoph Heddergott, Pauline Robinet, Vishukumar Aimanianda, Remi Beau, Anne Beauvais, Isabelle Mouyna, Marie-Christine Prevost, Arnaud Fekkar, Yanan Zhao, David Perlin, Jean-Paul Latgé
The galactomannan is a major cell wall molecule of Aspergillus fumigatus. This molecule is composed of a linear mannan with a repeating unit composed of four α1,6 and α1,2 linked mannose with side chains of galactofuran. To obtain a better understanding of the mannan biosynthesis in A. fumigatus, it was decided to undertake the successive deletion of the 11 genes which are putative orthologs of the mannosyltransferases responsible for establishing α1,6 and α1,2 mannose linkages in yeast. These deletions did not lead to a reduction of the mannan content of the cell wall of the mycelium of A...
September 7, 2016: Cellular Microbiology
Ayumi Saeki, Toshihiko Suzuki, Akira Hasebe, Ryousuke Kamezaki, Mari Fujita, Futoshi Nakazawa, Ken-Ichiro Shibata
Streptococcus sanguinis is frequently isolated from the blood of patients with infective endocarditis and contributes to the pathology of this disease through induction of interleukin (IL)-1β responsible for the development of the disease. However, the mechanism of IL-1β induction remains unknown. In this study, S. sanguinis activated a murine dendritic cell (DC) to induce IL-1β and this activity was attenuated by silencing the mRNAs of nucleotide-binding domain-like receptor containing protein 3 (NLRP3) and caspase-1...
September 7, 2016: Cellular Microbiology
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