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Cellular Microbiology

Flavie Courjol, Mathieu Gissot
Toxoplasma gondii is a unicellular eukaryotic pathogen that belongs to the Apicomplexa phylum, which encompasses some of the deadliest pathogens of medical and veterinary importance. The centrosome is key to the organization and coordination of the cell cycle and division of apicomplexan parasites. The T. gondii centrosome possesses a particular bipartite structure (outer and inner core). One of the main roles of the centrosome is to ensure proper coordination of karyokinesis. However, how these two events are coordinated is still unknown in T...
February 15, 2018: Cellular Microbiology
Dongfang Wang, Xiuling Gu, Xiaoman Liu, Songtao Wei, Bin Wang, Min Fang
Tuberculosis remains a threat to public health. The major problem for curing this disease is latent infection, of which the underlying mechanisms are still not fully understood. Previous studies indicate that NK cells do not play a role in inhibiting the growth of Mycobacterium tuberculosis in the lung, and recent studies have revealed that NK cells regulate the adaptive immunity during mycobacterial infection. By using a mouse model of direct lung infection with M.bovis BCG, we found that the presence of NK cells postponed the priming and activation of T cells after BCG infection...
February 15, 2018: Cellular Microbiology
Anoop Kumar, Ishita Chatterjee, Arivarasu N Anbazhagan, Dulari Jayawardena, Shubha Priyamvada, Waddah A Alrefai, Jun Sun, Alip Borthakur, Pradeep K Dudeja
Infection with the protozoan parasite Cryptosporidium parvum (CP) causes cryptosporidiosis, a widespread diarrheal disease. Impaired intestinal epithelial barrier function and increased permeability are most commonly associated with diarrheal diseases caused by enteric infections. However, studies on barrier disruption and underlying mechanisms in cryptosporidiosis are extremely limited. Epithelial tight junctions (TJ) and adherens junctions (AJ) are important in maintaining barrier integrity. Therefore, we examined the effects of CP infection on paracellular permeability and on the expression of the major TJ and AJ proteins utilizing in vitro, ex vivo, and in vivo models...
February 14, 2018: Cellular Microbiology
Arpita Mukherjee, Upayan Patra, Rahul Bhowmick, Mamta Chawla-Sarkar
Dynamic equilibrium between mitochondrial fission and mitochondrial fusion serves as an important quality control system within cells ensuring cellular vitality and homeostasis. Viruses often target mitochondrial dynamics as a part of their obligatory cellular reprogramming. The present study was undertaken to assess the status and regulation of mitochondrial dynamics during rotavirus (RV) infection. Distinct fragmentation of mitochondrial syncytia was observed during late hours of RV (SA11, Wa, A5-13) infection...
February 14, 2018: Cellular Microbiology
Le Son Tran, Darren Tran, Amanda De Paoli, Kimberley D'Costa, Sarah J Creed, Garrett Z Ng, Lena Le, Philip Sutton, J Silke, U Nachbur, Richard L Ferrero
Helicobacter pylori causes chronic inflammation which is a key precursor to gastric carcinogenesis. It has been suggested that H. pylori may limit this immunopathology by inducing the production of IL-33 in gastric epithelial cells, thus promoting T helper 2 immune responses. The molecular mechanism underlying IL-33 production in response to H. pylori infection, however, remains unknown. In the current study, we demonstrate that H. pylori activates signalling via the pathogen recognition molecule NOD1 and its adaptor protein RIPK2, to promote production of both full-length and processed IL-33 in gastric epithelial cells...
February 2, 2018: Cellular Microbiology
Lian Xu, Zhi-Zhen Pan, Jing Zhang, Li-Yang Niu, Jie Li, Zheng Chen, Bo Liu, Yu-Jing Zhu, Qing-Xi Chen
Cry2Ab, a pore-forming toxin (PFT) derived from Bacillus thuringiensis (Bt), is widely used as a bio-insecticides to control lepidopteran pests around the world. A previous study revealed that proteolytic activation of Cry2Ab by Plutella xylostella midgut juice (PxMJ) was essential for its insecticidal activity against P. xylostella, although the exact molecular mechanism remained unknown. Here we demonstrated for the first time that proteolysis of Cry2Ab uncovered an active region (the helices α4-α5 in Domain I), which was required for the mode of action of Cry2Ab...
January 30, 2018: Cellular Microbiology
Jacob S Edmisson, Shifu Tian, Cortney L Armstrong, Aruna Vashishta, Christopher K Klaes, Irina Miralda, Emeri Jimenez-Flores, Junyi Le, Qian Wang, Richard J Lamont, Silvia M Uriarte
Filifactor alocis is a newly appreciated pathogen in periodontal diseases. Neutrophils are the predominant innate immune cell in the gingival crevice. In this study we examined modulation of human neutrophil antimicrobial functions by F. alocis. Both non-opsonized and serum opsonized F. alocis were engulfed by neutrophils, but were not efficiently eliminated. Challenge of neutrophils with either non-opsonized or serum opsonized F. alocis induced a minimal intracellular as well as extracellular respiratory burst response compared to opsonized Staphylococcus aureus and fMLF, respectively...
January 28, 2018: Cellular Microbiology
Elnaz S Rasti, Megan L Schappert, Angela C Brown
The primary virulence factor of Vibrio cholerae, cholera toxin (CT), initiates a pathway in epithelial cells that leads to the severe diarrhea characteristic of cholera. Secreted CT binds to GM1 on the surface of host cells to facilitate internalization. Many bacterial toxins, including CT, have been shown to be additionally delivered via outer membrane vesicles (OMVs). A fraction of the closely related heat labile toxin (LT) produced by enterotoxigenic Escherichia coli (ETEC) has been demonstrated to reside on the surface of OMVs, where it binds GM1 to facilitate OMV internalization by host cells...
January 27, 2018: Cellular Microbiology
Jungnam Lee, JoAnn S Roberts, Kalina R Atanasova, Nityananda Chowdhury, Özlem Yilmaz
We have previously shown that a homolog of a conserved Nucleoside-diphosphate-kinase (Ndk) family of multifunctional enzymes and secreted molecule in Porphyromonas gingivalis can modulate selective host molecular pathways including downregulation of reactive-oxygen-species generation to promote bacterial survival in human gingival-epithelial-cells (GECs). In this study, we describe a novel kinase function for bacterial effector, P. gingivalis-Ndk, in abrogating epithelial cell death by phosphorylating Heat-shock-protein-27 (HSP27) in GECs...
January 22, 2018: Cellular Microbiology
Victoria E B Hipolito, Erika Ospina-Escobar, Roberto J Botelho
Lysosomes are acidic and hydrolytic organelles responsible for receiving and digesting cargo acquired during endocytosis, phagocytosis, and autophagy. For macrophages and dendritic cells, the lysosome is kingpin, playing a direct role in microbe killing and antigen processing for presentation. Strikingly, the historic view that lysosomes are homogeneous and static organelles is being replaced with a more elegant paradigm, in which lysosomes are heterogeneous, dynamic and respond to cellular needs. For example, lysosomes are signaling platforms that integrate stress detection and molecular decision hubs like mTORC1 and AMPK to modulate cellular activity...
January 19, 2018: Cellular Microbiology
Natália G Sampaio, Samantha Emery, Alexandra Garnham, Qiao Y Tan, Xavier Sisquella, Matthew A Pimentel, Neta Regev-Rudzki, Louis Schofield, Emily M Eriksson
Pathogens can release extracellular vesicles (EVs) for cell-cell communication and host modulation. EVs from Plasmodium falciparum, the deadliest malaria parasite species, can transfer drug resistance genes between parasites. EVs from late-stage parasite-infected RBC (iRBC-EVs) are immunostimulatory and affect endothelial cell permeability, but little is known about EVs from early-stage iRBC. We detected the parasite virulence factor PfEMP1, which is responsible for iRBC adherence and a major contributor to disease severity, in EVs only up to 12 hours-post RBC invasion...
January 18, 2018: Cellular Microbiology
Julianne Mendi Muthinja, Johanna Ripp, Timothy Krüger, Andrea Imle, Tamás Haraszti, Oliver T Fackler, Joachim P Spatz, Markus Engstler, Friedrich Frischknecht
Motile cells and pathogens migrate in complex environments and yet are mostly studied on simple 2D substrates. In order to mimic the diverse environments of motile cells a set of assays including substrates of defined elasticity, microfluidics, micropatterns, organotypic cultures and 3D gels have been developed. We briefly introduce these and then focus on the use of micro-patterned pillar arrays, which help to bridge the gap between 2D and 3D. These structures are made from polydimethylsiloxane, a moldable plastic and their use has revealed new insights into mechanoperception in Caenorhabditis elegans, gliding motility of Plasmodium, swimming of trypanosomes and nuclear stability in cancer cells...
January 7, 2018: Cellular Microbiology
Mayumi Tachibana, Tomoko Ishino, Eizo Takashima, Takafumi Tsuboi, Motomi Torii
Anopheles mosquitoes transmit Plasmodium parasites of mammals, including the species that cause malaria in humans. Malaria pathology is caused by rapid multiplication of parasites in asexual intraerythrocytic cycles. Sexual stage parasites are also produced during the intraerythrocytic cycle, and are ingested by the mosquito, initiating gametogenesis and subsequent sporogonic stage development. Here, we present a Plasmodium protein, termed microgamete surface protein (MiGS), which has an important role in male gametocyte osmiophilic body (MOB) formation and microgamete function...
January 5, 2018: Cellular Microbiology
Sin Yee Gun, Carla Claser, Teck Hui Teo, Shanshan W Howland, Chek Meng Poh, Rebecca Ren Ying Chye, Lisa F P Ng, Laurent Rénia
Host immune response has a key role in controlling the progression of malaria infection. In the well-established murine model of experimental cerebral malaria (ECM) with P. berghei ANKA infection, pro-inflammatory Th1 and CD8+ T cells response are essential for disease development. Interferon regulatory factor 1 (IRF1) is a transcription factor which promotes Th1 responses and its absence was previously shown to protect from ECM death. Yet, the exact mechanism of protection remains unknown. Here we demonstrated that IRF1-deficient mice (IRF1KO) were protected from ECM death despite displaying early neurological signs...
December 27, 2017: Cellular Microbiology
Jie Tong, Yuguang Fu, Nai-Huei Wu, Manfred Rohde, Fandan Meng, Peter Valentin-Weigand, Georg Herrler
Group B streptococci (GBS) contain a capsular polysaccharide with side chains terminating in α2,3-linked sialic acids. Because of this linkage type, the sialic acids of GBS are recognized by lectins of immune cells. This interaction results in a dampening of the host immune response and thus promotes immune evasion. As several influenza A viruses (IAV) use α2,3-linked sialic acid as a receptor determinant for binding to host cells, we analyzed whether GBS and influenza viruses can interact with each other and how this interaction affects viral replication and bacterial adherence to and invasion of host cells...
December 22, 2017: Cellular Microbiology
Ryan W J Steel, Ying Pei, Nelly Camargo, Alexis Kaushansky, Dorender A Dankwa, Thomas Martinson, Thao Nguyen, Will Betz, Hayley Cardamone, Vladimir Vigdorovich, Nicholas Dambrauskas, Sara Carbonetti, Ashley M Vaughan, Noah D Sather, Stefan H I Kappe
Gliding motility and cell traversal by the Plasmodium ookinete and sporozoite invasive stages allow penetration of cellular barriers to establish infection of the mosquito vector and mammalian host, respectively. Motility and traversal are not observed in red cell infectious merozoites, and we have previously classified genes that are expressed in sporozoites but not merozoites (S genes) in order to identify proteins involved in these processes. The S4 gene has been described as critical for Cell Traversal of Ookinetes and Sporozoites (CelTOS), yet knockout parasites (s4/celtos¯) do not generate robust salivary gland sporozoite numbers, precluding a thorough analysis of S4/CelTOS function during host infection...
December 18, 2017: Cellular Microbiology
Jennifer Fredlund, José Carlos Santos, Virginie Stévenin, Allon Weiner, Patricia Latour-Lambert, Katya Rechav, Adeline Mallet, Jacomine Krijnse-Locker, Michael Elbaum, Jost Enninga
Salmonella enterica induces membrane ruffling and genesis of macropinosomes during its interactions with epithelial cells. This is achieved through the type three secretion system-1 (T3SS-1), which first mediates bacterial attachment to host cells and then injects bacterial effector proteins to alter host behavior. Next, Salmonella enters into the targeted cell within an early membrane-bound compartment that matures into a slow growing, replicative niche called the Salmonella Containing Vacuole (SCV). Alternatively, the pathogen disrupts the membrane of the early compartment and replicate at high rate in the cytosol...
December 18, 2017: Cellular Microbiology
Islam M Ateia, Pimchanok Sutthiboonyapan, Pachiyappan Kamarajan, Taocong Jin, Valentina Godovikova, Yvonne L Kapila, J Christopher Fenno
Host-derived matrix metalloproteinases (MMPs) and bacterial proteases mediate destruction of extracellular matrices and supporting alveolar bone in periodontitis. The Treponema denticola dentilisin protease induces MMP-2 expression and activation in periodontal ligament (PDL) cells, and dentilisin-mediated activation of pro-MMP-2 is required for cellular fibronectin degradation. Here we report that T. denticola regulates MMP-2 expression through epigenetic modifications in the periodontium. PDL cells were treated with epigenetic enzyme inhibitors before or after T...
December 4, 2017: Cellular Microbiology
Abdi Elmi, Amber Dorey, Eleanor Watson, Heena Jagatia, Neil F Inglis, Ozan Gundogdu, Mona Bajaj-Elliott, Brendan W Wren, David G E Smith, Nick Dorrell
Campylobacter jejuni, the leading cause of bacterial acute gastroenteritis worldwide, secretes an arsenal of virulence-associated proteins within outer membrane vesicles (OMVs). C. jejuni OMVs contain three serine proteases (HtrA, Cj0511 and Cj1365c) which cleave the intestinal epithelial cell (IEC) tight and adherens junction proteins occludin and E-cadherin, promoting enhanced C. jejuni adhesion to and invasion of IECs. C. jejuni OMVs also induce IECs innate immune responses. The bile salt sodium taurocholate (ST) is sensed as a host signal to co-ordinate the activation of virulence-associated genes in the enteric pathogen Vibrio cholerae...
December 4, 2017: Cellular Microbiology
Phylicia A Aaron, Mantana Jamklang, John P Uhrig, Angie Gelli
Cryptococcus neoformans is an opportunistic fungal pathogen that causes life-threatening meningitis most commonly in populations with impaired immunity. Here we resolved the transcriptome of the human brain endothelium challenged with C. neoformans to establish whether C. neoformans invades the CNS by co-opting particular signaling pathways as a means to promote its own entry. Among the 5 major pathways targeted by C. neoformans, the EPH-EphrinA1 (EphA2) tyrosine kinase receptor-signaling pathway was examined further...
December 2, 2017: Cellular Microbiology
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