Strong homeostatic TCR signals induce formation of self-tolerant virtual memory CD8 T cells
We describe two molecular mechanisms driving the formation of virtual memory T cells. First, virtual memory T cells originate exclusively from strongly self-reactive T cells. Second, the stoichiometry of the CD8 interaction with Lck regulates the size of the virtual memory T-cell compartment via modulating the self-reactivity of individual T cells. Although virtual memory T cells descend from the highly self-reactive clones and acquire a partial memory program, they are not more potent in inducing experimental autoimmune diabetes than naïve T cells. These data underline the importance of the variable level of self-...
Source: EMBO Journal - July 13, 2018 Category: Molecular Biology Authors: Drobek, A., Moudra, A., Mueller, D., Huranova, M., Horkova, V., Pribikova, M., Ivanek, R., Oberle, S., Zehn, D., McCoy, K. D., Draber, P., Stepanek, O. Tags: Immunology Articles Source Type: research
Transcriptional control and exploitation of an immune-responsive family of plant retrotransposons
In this study, we employed an ATCOPIA93 long-terminal repeat (LTR) promoter-GUS fusion to show that this retrotransposon behaves like an immune-responsive gene during pathogen defense in Arabidopsis. We also showed that the endogenous ATCOPIA93 copy "EVD", which is activated in the presence of bacterial stress, is negatively regulated by both DNA methylation and polycomb-mediated silencing, a mode of repression typically found at protein-coding and microRNA genes. Interestingly, an ATCOPIA93-derived soloLTR is located upstream of the disease resistance gene RPP4 and is devoid of DNA methylation and H3K27m3 marks. Through l...
Source: EMBO Journal - July 13, 2018 Category: Molecular Biology Authors: Zervudacki, J., Yu, A., Amesefe, D., Wang, J., Drouaud, J., Navarro, L., Deleris, A. Tags: Chromatin, Epigenetics, Genomics & Functional Genomics, Microbiology, Virology & Host Pathogen Interaction, Plant Biology Articles Source Type: research
Mechanism of membrane pore formation by human gasdermin-D
Gasdermin-D (GSDMD), a member of the gasdermin protein family, mediates pyroptosis in human and murine cells. Cleaved by inflammatory caspases, GSDMD inserts its N-terminal domain (GSDMDNterm) into cellular membranes and assembles large oligomeric complexes permeabilizing the membrane. So far, the mechanisms of GSDMDNterm insertion, oligomerization, and pore formation are poorly understood. Here, we apply high-resolution (≤ 2 nm) atomic force microscopy (AFM) to describe how GSDMDNterm inserts and assembles in membranes. We observe GSDMDNterm inserting into a variety of lipid compositions, among which phosphat...
Source: EMBO Journal - July 13, 2018 Category: Molecular Biology Authors: Mulvihill, E., Sborgi, L., Mari, S. A., Pfreundschuh, M., Hiller, S., Müller, D. J. Tags: Autophagy & Cell Death, Immunology Articles Source Type: research
Dimer-specific immunoprecipitation of active caspase-2 identifies TRAF proteins as novel activators
Caspase-2 has been shown to initiate apoptotic cell death in response to specific intracellular stressors such as DNA damage. However, the molecular mechanisms immediately upstream of its activation are still poorly understood. We combined a caspase-2 bimolecular fluorescence complementation (BiFC) system with fluorophore-specific immunoprecipitation to isolate and study the active caspase-2 dimer and its interactome. Using this technique, we found that tumor necrosis factor receptor-associated factor 2 (TRAF2), as well as TRAF1 and 3, directly binds to the active caspase-2 dimer. TRAF2 in particular is necessary for caspa...
Source: EMBO Journal - July 13, 2018 Category: Molecular Biology Authors: Robeson, A. C., Lindblom, K. R., Wojton, J., Kornbluth, S., Matsuura, K. Tags: Autophagy & Cell Death Articles Source Type: research
A protein that controls the onset of a Salmonella virulence program
The mechanism of action and contribution to pathogenesis of many virulence genes are understood. By contrast, little is known about anti-virulence genes, which contribute to the start, progression, and outcome of an infection. We now report how an anti-virulence factor in Salmonella enterica serovar Typhimurium dictates the onset of a genetic program that governs metabolic adaptations and pathogen survival in host tissues. Specifically, we establish that the anti-virulence protein CigR directly restrains the virulence protein MgtC, thereby hindering intramacrophage survival, inhibition of ATP synthesis, stabilization ...
Source: EMBO Journal - July 13, 2018 Category: Molecular Biology Authors: Yeom, J., Pontes, M. H., Choi, J., Groisman, E. A. Tags: Microbiology, Virology & Host Pathogen Interaction, Transcription Articles Source Type: research
hDNA2 nuclease/helicase promotes centromeric DNA replication and genome stability
DNA2 is a nuclease/helicase that is involved in Okazaki fragment maturation, replication fork processing, and end resection of DNA double-strand breaks. Similar such helicase activity for resolving secondary structures and structure-specific nuclease activity are needed during DNA replication to process the chromosome-specific higher order repeat units present in the centromeres of human chromosomes. Here, we show that DNA2 binds preferentially to centromeric DNA. The nuclease and helicase activities of DNA2 are both essential for resolution of DNA structural obstacles to facilitate DNA replication fork movement. Loss of D...
Source: EMBO Journal - July 13, 2018 Category: Molecular Biology Authors: Li, Z., Liu, B., Jin, W., Wu, X., Zhou, M., Liu, V. Z., Goel, A., Shen, Z., Zheng, L., Shen, B. Tags: Cell Cycle, DNA Replication, Repair & Recombination Articles Source Type: research
Nuclear lncRNA stabilization in the host response to bacterial infection
Long non-coding RNAs (lncRNAs) play important roles in many cellular pathways, but their contribution to the defense of eukaryotic cells against pathogens remains poorly understood. A new study from Imamura et al in The EMBO Journal reports that Salmonella infection in human cells impacts nuclear RNA decay, which in turn drives the accumulation of otherwise unstable nuclear lncRNAs, some of which may have protective effects against this common bacterial pathogen. These unexpected findings demand more efforts to fully decrypt the molecular functions of lncRNAs in innate and adaptive immunity. (Source: EMBO Journal)
Source: EMBO Journal - July 2, 2018 Category: Molecular Biology Authors: Munschauer, M., Vogel, J. Tags: Microbiology, Virology & Host Pathogen Interaction, RNA Biology News [amp ] Views Source Type: research
miR-200/375 control epithelial plasticity-associated alternative splicing by repressing the RNA-binding protein Quaking
Members of the miR-200 family are critical gatekeepers of the epithelial state, restraining expression of pro-mesenchymal genes that drive epithelial–mesenchymal transition (EMT) and contribute to metastatic cancer progression. Here, we show that miR-200c and another epithelial-enriched miRNA, miR-375, exert widespread control of alternative splicing in cancer cells by suppressing the RNA-binding protein Quaking (QKI). During EMT, QKI-5 directly binds to and regulates hundreds of alternative splicing targets and exerts pleiotropic effects, such as increasing cell migration and invasion and restraining tumour growth, ...
Source: EMBO Journal - July 2, 2018 Category: Molecular Biology Authors: Pillman, K. A., Phillips, C. A., Roslan, S., Toubia, J., Dredge, B. K., Bert, A. G., Lumb, R., Neumann, D. P., Li, X., Conn, S. J., Liu, D., Bracken, C. P., Lawrence, D. M., Stylianou, N., Schreiber, A. W., Tilley, W. D., Hollier, B. G., Khew-Goodall, Y., Tags: Cancer, Cell Adhesion, Polarity & Cytoskeleton, RNA Biology Articles Source Type: research
Helicobacter pylori adhesin HopQ disrupts trans dimerization in human CEACAMs
The human gastric pathogen Helicobacter pylori is a major causative agent of gastritis, peptic ulcer disease, and gastric cancer. As part of its adhesive lifestyle, the bacterium targets members of the carcinoembryonic antigen-related cell adhesion molecule (CEACAM) family by the conserved outer membrane adhesin HopQ. The HopQ–CEACAM1 interaction is associated with inflammatory responses and enables the intracellular delivery and phosphorylation of the CagA oncoprotein via a yet unknown mechanism. Here, we generated crystal structures of HopQ isotypes I and II bound to the N-terminal domain of human CEACAM1...
Source: EMBO Journal - July 2, 2018 Category: Molecular Biology Authors: Moonens, K., Hamway, Y., Neddermann, M., Reschke, M., Tegtmeyer, N., Kruse, T., Kammerer, R., Mejias-Luque, R., Singer, B. B., Backert, S., Gerhard, M., Remaut, H. Tags: Cell Adhesion, Polarity & Cytoskeleton, Microbiology, Virology & Host Pathogen Interaction, Structural Biology Articles Source Type: research
The Helicobacter pylori adhesin protein HopQ exploits the dimer interface of human CEACAMs to facilitate translocation of the oncoprotein CagA
Helicobacter pylori infects half of the world's population, and strains that encode the cag type IV secretion system for injection of the oncoprotein CagA into host gastric epithelial cells are associated with elevated levels of cancer. CagA translocation into host cells is dependent on interactions between the H. pylori adhesin protein HopQ and human CEACAMs. Here, we present high-resolution structures of several HopQ-CEACAM complexes and CEACAMs in their monomeric and dimeric forms establishing that HopQ uses a coupled folding and binding mechanism to engage the canonical CEACAM dimerization interface for CEACAM rec...
Source: EMBO Journal - July 2, 2018 Category: Molecular Biology Authors: Bonsor, D. A., Zhao, Q., Schmidinger, B., Weiss, E., Wang, J., Deredge, D., Beadenkopf, R., Dow, B., Fischer, W., Beckett, D., Wintrode, P. L., Haas, R., Sundberg, E. J. Tags: Cell Adhesion, Polarity & Cytoskeleton, Microbiology, Virology & Host Pathogen Interaction, Structural Biology Articles Source Type: research
Photodynamic therapy with redaporfin targets the endoplasmic reticulum and Golgi apparatus
Preclinical evidence depicts the capacity of redaporfin (Redp) to act as potent photosensitizer, causing direct antineoplastic effects as well as indirect immune-dependent destruction of malignant lesions. Here, we investigated the mechanisms through which photodynamic therapy (PDT) with redaporfin kills cancer cells. Subcellular localization and fractionation studies based on the physicochemical properties of redaporfin revealed its selective tropism for the endoplasmic reticulum (ER) and the Golgi apparatus (GA). When activated, redaporfin caused rapid reactive oxygen species-dependent perturbation of ER/GA compartments,...
Source: EMBO Journal - July 2, 2018 Category: Molecular Biology Authors: Gomes-da-Silva, L. C., Zhao, L., Bezu, L., Zhou, H., Sauvat, A., Liu, P., Durand, S., Leduc, M., Souquere, S., Loos, F., Mondragon, L., Sveinbjornsson, B., Rekdal, O., Boncompain, G., Perez, F., Arnaut, L. G., Kepp, O., Kroemer, G. Tags: Cancer, Autophagy & Cell Death Articles Source Type: research
In vivo expansion of functionally integrated GABAergic interneurons by targeted increase in neural progenitors
A central hypothesis for brain evolution is that it might occur via expansion of progenitor cells and subsequent lineage-dependent formation of neural circuits. Here, we report in vivo amplification and functional integration of lineage-specific circuitry in Drosophila. Levels of the cell fate determinant Prospero were attenuated in specific brain lineages within a range that expanded not only progenitors but also neuronal progeny, without tumor formation. Resulting supernumerary neural stem cells underwent normal functional transitions, progressed through the temporal patterning cascade, and generated progeny with mo...
Source: EMBO Journal - July 2, 2018 Category: Molecular Biology Authors: Shaw, R. E., Kottler, B., Ludlow, Z. N., Buhl, E., Kim, D., Morais da Silva, S., Miedzik, A., Coum, A., Hodge, J. J., Hirth, F., Sousa-Nunes, R. Tags: Development & Differentiation, Neuroscience Articles Source Type: research
Live imaging of wound angiogenesis reveals macrophage orchestrated vessel sprouting and regression
Wound angiogenesis is an integral part of tissue repair and is impaired in many pathologies of healing. Here, we investigate the cellular interactions between innate immune cells and endothelial cells at wounds that drive neoangiogenic sprouting in real time and in vivo. Our studies in mouse and zebrafish wounds indicate that macrophages are drawn to wound blood vessels soon after injury and are intimately associated throughout the repair process and that macrophage ablation results in impaired neoangiogenesis. Macrophages also positively influence wound angiogenesis by driving resolution of anti-angiogenic wound...
Source: EMBO Journal - July 2, 2018 Category: Molecular Biology Authors: Gurevich, D. B., Severn, C. E., Twomey, C., Greenhough, A., Cash, J., Toye, A. M., Mellor, H., Martin, P. Tags: Development & Differentiation, Vascular Biology & Angiogenesis Articles Source Type: research
Centrosomal ALIX regulates mitotic spindle orientation by modulating astral microtubule dynamics
The orientation of the mitotic spindle (MS) is tightly regulated, but the molecular mechanisms are incompletely understood. Here we report a novel role for the multifunctional adaptor protein ALG-2-interacting protein X (ALIX) in regulating MS orientation in addition to its well-established role in cytokinesis. We show that ALIX is recruited to the pericentriolar material (PCM) of the centrosomes and promotes correct orientation of the MS in asymmetrically dividing Drosophila stem cells and epithelial cells, and symmetrically dividing Drosophila and human epithelial cells. ALIX-deprived cells display defective formation of...
Source: EMBO Journal - July 2, 2018 Category: Molecular Biology Authors: Malerod, L., Le Borgne, R., Lie-Jensen, A., Eikenes, A. H., Brech, A., Liestol, K., Stenmark, H., Haglund, K. Tags: Cell Adhesion, Polarity & Cytoskeleton, Cell Cycle Articles Source Type: research
Diminished nuclear RNA decay upon Salmonella infection upregulates antibacterial noncoding RNAs
Cytoplasmic mRNA degradation controls gene expression to help eliminate pathogens during infection. However, it has remained unclear whether such regulation also extends to nuclear RNA decay. Here, we show that 145 unstable nuclear RNAs, including enhancer RNAs (eRNAs) and long noncoding RNAs (lncRNAs) such as NEAT1v2, are stabilized upon Salmonella infection in HeLa cells. In uninfected cells, the RNA exosome, aided by the Nuclear EXosome Targeting (NEXT) complex, degrades these labile transcripts. Upon infection, the levels of the exosome/NEXT components, RRP6 and MTR4, dramatically decrease, resulting in transcript stab...
Source: EMBO Journal - July 2, 2018 Category: Molecular Biology Authors: Imamura, K., Takaya, A., Ishida, Y.-i., Fukuoka, Y., Taya, T., Nakaki, R., Kakeda, M., Imamachi, N., Sato, A., Yamada, T., Onoguchi-Mizutani, R., Akizuki, G., Tanu, T., Tao, K., Miyao, S., Suzuki, Y., Nagahama, M., Yamamoto, T., Jensen, T. H., Akimitsu, N Tags: Microbiology, Virology & Host Pathogen Interaction, RNA Biology Articles Source Type: research
