http://hdl.handle.net/10033/128109 Wed, 22 May 2013 14:20:33 GMT 2013-05-22T14:20:33Z http://hdl.handle.net/10033/292559 Title: Identification of the N-terminal domain of the influenza virus PA responsible for the suppression of host protein synthesis. Authors: Desmet, Emily A; Bussey, Kendra A; Stone, Raychel; Takimoto, Toru Abstract: Cellular protein synthesis is suppressed during influenza virus infection, allowing for preferential production of viral proteins. To explore the impact of polymerase subunits on protein synthesis, we coexpressed enhanced green fluorescent protein (eGFP) or luciferase together with each polymerase component or NS1 of A/California/04/2009 (Cal) and found that PA has a significant impact on the expression of eGFP and luciferase. Comparison of the suppressive activity on coexpressed proteins between various strains revealed that avian virus or avian-origin PAs have much stronger activity than human-origin PAs, such as the one from A/WSN/33 (WSN). Protein synthesis data suggested that reduced expression of coexpressed proteins is not due to PA's reported proteolytic activity. A recombinant WSN containing Cal PA showed enhanced host protein synthesis shutoff and induction of apoptosis. Further characterization of the PA fragment indicated that the N-terminal domain (PANt), which includes the endonuclease active site, is sufficient to suppress cotransfected gene expression. By characterizing various chimeric PANts, we found that multiple regions of PA, mainly the helix α4 and the flexible loop of amino acids 51 to 74, affect the activity. The suppressive effect of PANt cDNA was mainly due to PA-X, which was expressed by ribosomal frameshifting. In both Cal and WSN viruses, PA-X showed a stronger effect than the corresponding PANt, suggesting that the unique C-terminal sequences of PA-X also play a role in suppressing cotransfected gene expression. Our data indicate strain variations in PA gene products, which play a major role in suppression of host protein synthesis. Fri, 01 Mar 2013 00:00:00 GMT http://hdl.handle.net/10033/292559 2013-03-01T00:00:00Z http://hdl.handle.net/10033/281033 Title: Noncanonical autophagy is required for type I interferon secretion in response to DNA-immune complexes. Authors: Henault, Jill; Martinez, Jennifer; Riggs, Jeffrey M; Tian, Jane; Mehta, Payal; Clarke, Lorraine; Sasai, Miwa; Latz, Eicke; Brinkmann, Melanie M; Iwasaki, Akiko; Coyle, Anthony J; Kolbeck, Roland; Green, Douglas R; Sanjuan, Miguel A Abstract: Toll-like receptor-9 (TLR9) is largely responsible for discriminating self from pathogenic DNA. However, association of host DNA with autoantibodies activates TLR9, inducing the pathogenic secretion of type I interferons (IFNs) from plasmacytoid dendritic cells (pDCs). Here, we found that in response to DNA-containing immune complexes (DNA-IC), but not to soluble ligands, IFN-α production depended upon the convergence of the phagocytic and autophagic pathways, a process called microtubule-associated protein 1A/1B-light chain 3 (LC3)-associated phagocytosis (LAP). LAP was required for TLR9 trafficking into a specialized interferon signaling compartment by a mechanism that involved autophagy-related proteins, but not the conventional autophagic preinitiation complex, or adaptor protein-3 (AP-3). Our findings unveil a new role for nonconventional autophagy in inflammation and provide one mechanism by which anti-DNA autoantibodies, such as those found in several autoimmune disorders, bypass the controls that normally restrict the apportionment of pathogenic DNA and TLR9 to the interferon signaling compartment. Fri, 14 Dec 2012 00:00:00 GMT http://hdl.handle.net/10033/281033 2012-12-14T00:00:00Z http://hdl.handle.net/10033/269392 Title: ChIP-on-chip analysis identifies IL-22 as direct target gene of ectopically expressed FOXP3 transcription factor in human T cells. Authors: Jeron, Andreas; Hansen, Wiebke; Ewert, Franziska; Buer, Jan; Geffers, Robert; Bruder, Dunja Abstract: ABSTRACT: Sun, 01 Jan 2012 00:00:00 GMT http://hdl.handle.net/10033/269392 2012-01-01T00:00:00Z http://hdl.handle.net/10033/251560 Title: IL-4 Attenuates Pulmonary Epithelial Cell-Mediated Suppression of T Cell Priming. Authors: Albrecht, Melanie; Arnhold, Markus; Lingner, Sandra; Mahapatra, Subhashree; Bruder, Dunja; Hansen, Gesine; Dittrich, Anna-Maria Abstract: We have previously shown that Th2-polarized airway inflammation facilitates sensitization towards new, protein antigens. In this context, we could demonstrate that IL-4 needs to act on cells of the hematopoetic and the structural compartment in order to facilitate sensitization towards new antigens. We thus aimed to elucidate possible mechanisms of action of IL-4 on structural cells choosing to analyze pulmonary epithelial cells as an important part of the lung's structural system. We used a co-culture system of DC- or APC-dependent in vitro priming of T cells, co-cultivated on a layer of cells of a murine pulmonary epithelial cell line (LA-4) pretreated with or without IL-4. Effects on T cell priming were analyzed via CFSE-dilution and flow cytometric assessment of activation status. Pulmonary epithelial cells suppressed T cell proliferation in vitro but this effect was attenuated by pre-treatment of the epithelial cells with IL-4. Transwell experiments suggest that epithelial-mediated suppression of T cell activation is mostly cell-contact dependent and leads to attenuation in an early naive T cell phenotype. Secretion of soluble factors like TARC, TSLP, GM-CSF and CCL20 by epithelial cells did not change after IL-4 treatment. However, analysis of co-stimulatory expression on pulmonary epithelial cells revealed that pre-treatment of epithelial cells with IL-4 changed expression GITR-L, suggesting a possible mechanism for the effects observed. Our studies provide new insight into the role of IL-4 during the early phases of pulmonary sensitization: The inhibitory activity of pulmonary epithelial cells in homeostasis is reversed in the presence of IL-4, which is secreted in the context of Th2-dominated allergic airway inflammation. This mechanism might serve to explain facilitated sensitization in the clinical context of polysensitization where due to a pre-existing sensitization increased levels of IL-4 in the airways might facilitate T cell priming towards new antigens. Sun, 01 Jan 2012 00:00:00 GMT http://hdl.handle.net/10033/251560 2012-01-01T00:00:00Z