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141.
Jesper Melchjorsen Johanna Rintahaka Stine S?by Kristy A. Horan Alina Poltajainen Lars ?stergaard S?ren R. Paludan Sampsa Matikainen 《Journal of virology》2010,84(21):11350-11358
Innate recognition of viruses is mediated by pattern recognition receptors (PRRs) triggering expression of antiviral interferons (IFNs) and proinflammatory cytokines. In mice, Toll-like receptor 2 (TLR2) and TLR9 as well as intracellular nucleotide-sensing pathways have been shown to recognize herpes simplex virus (HSV). Here, we describe how human primary macrophages recognize early HSV infection via intracellular pathways. A number of inflammatory cytokines, IFNs, and IFN-stimulated genes were upregulated after HSV infection. We show that early recognition of HSV and induction of IFNs and inflammatory cytokines are independent of TLR2 and TLR9, since inhibition of TLR2 using TLR2 neutralizing antibodies did not affect virus-induced responses and the macrophages were unresponsive to TLR9 stimulation. Instead, HSV recognition involves intracellular recognition systems, since induction of tumor necrosis factor alpha (TNF-α) and IFNs was dependent on virus entry and replication. Importantly, expression of IFNs was strongly inhibited by small interfering RNA (siRNA) knockdown of MAVS, but this MAVS-dependent IFN induction occurred independently of the recently discovered polymerase III (Pol III)/RIG-I DNA sensing system. In contrast, induction of TNF-α was largely independent of MAVS, suggesting that induction of inflammatory cytokines during HSV infection proceeds via a novel pathway. Transfection with ODN2006, a broad inhibitor of intracellular nucleotide recognition, revealed that nucleotide-sensing systems are employed to induce both IFNs and TNF-α. Finally, using siRNA knockdown, we found that MDA5, but not RIG-I, was the primary mediator of HSV recognition. Thus, innate recognition of HSV by human primary macrophages occurs via two distinct intracellular nucleotide-sensing pathways responsible for induction of IFNs and inflammatory cytokine expression, respectively.Virus recognition is essential for activation of innate antiviral immune defense and the subsequent induction of acquired immunity. Conserved pathogen motifs, termed pathogen-associated molecular patterns (PAMPs), are recognized by pattern recognition receptors (PRRs). Virus-recognizing PRRs include Toll-like receptors (TLRs), RIG-I-like receptors (RLRs), and a number of intracellular DNA receptors. Several TLRs have been attributed roles in the recognition of virus. TLR2 and TLR4 recognize viral surface structures (3, 6, 18, 31), TLR3 recognizes double-stranded RNA (dsRNA) (2), and TLR7/8 and TLR9 function as signaling receptors for viral single-stranded RNA (ssRNA) (8, 11, 21) and CpG DNA (12, 20), respectively.Within the cell, cytoplasmic RLRs RIG-I and MDA5 both recognize accumulation of virus-derived dsRNA; in addition, RIG-I recognizes 5′-triphosphated RNA (14, 27, 39, 40). In addition to the RLRs, a number of receptors recognize foreign DNA. Presently, three DNA receptors have been identified: Z-DNA binding protein 1 (ZBP-1, or DAI) (36) and RNA polymerase III (Pol III) (1, 4) both mediate interferon (IFN) and cytokine production, whereas the AIM2 inflammasome is involved in caspase 1 activation in response to cytoplasmic dsDNA (13).Herpes simplex virus type 1 (HSV-1) and HSV-2 are two closely related human DNA viruses associated with a number of serious diseases, including orofacial infections, encephalitis, and genital infections (34). Macrophages play an important role in the first line of defense against viral infection via production of IFNs, cytokines, and chemokines that regulate the progress of the virus infection and activate and support appropriate defense mechanisms (9, 10, 24).TLR2, TLR3, and TLR9 have been identified as mediators of proinflammatory cytokine production during HSV infections. TLR2 mediates an overzealous inflammatory cytokine response following HSV-1 infection in mice, promoting mononuclear cell infiltration of the brain and development of encephalitis (18). TLR3 mediates type I and III IFN production in human fibroblasts (41). TLR9 recognizes genomic DNA from HSV-1 and HSV-2 in murine plasmacytoid dendritic cells (DCs) (17, 20) and mediates tumor necrosis factor alpha (TNF-α) and CCL5 production in murine macrophages (22). Both TLR2 and TLR9 mediate recognition of HSV and cytokine production in murine conventional DCs (35). HSV is recognized by an RLR/MAVS-dependent mechanism in murine macrophages and mouse embryonic fibroblasts (MEFs) (5, 29, 30). Recent data suggest that RNA Pol III mediates IFN production following HSV-1 infection and transfection with HSV-1 DNA in macrophage-like RAW 264.7 cells (4). Finally, murine L929 fibroblast-like cells are moderately inhibited in their ability to produce IFN after HSV-1 infection when ZBP-1 is knocked down (19, 36). Thus, several PRRs have been reported to recognize HSV-1 in murine cells and different cell lines, but the pathways responsible for sensing this virus in human primary macrophages and their impact on cytokine expression have not previously been described.In this work, we investigate the recognition pathways underlying HSV-induced cytokine and chemokine expression in human primary macrophages. We demonstrate that HSV-1-induced IFN and cytokine expression is independent of TLR2 and TLR9 but highly dependent on virus replication and intracellular nucleotide recognition systems. Specifically, induction of IFNs is dependent on MAVS and MDA5, whereas TNF-α is induced by a novel intracellular nucleotide-sensing system. 相似文献
142.
Delphine Cardi Alexandre Pozza Bertrand Arnou Estelle Marchal Johannes D. Clausen Jens Peter Andersen Sanjeev Krishna Jesper V. M?ller Marc le Maire Christine Jaxel 《The Journal of biological chemistry》2010,285(34):26406-26416
The antimalarial drugs artemisinins have been described as inhibiting Ca2+-ATPase activity of PfATP6 (Plasmodium falciparum ATP6) after expression in Xenopus oocytes. Mutation of an amino acid residue in mammalian SERCA1 (Glu255) to the equivalent one predicted in PfATP6 (Leu) was reported to induce sensitivity to artemisinin in the oocyte system. However, in the present experiments, we found that artemisinin did not inhibit mammalian SERCA1a E255L either when expressed in COS cells or after purification of the mutant expressed in Saccharomyces cerevisiae. Moreover, we found that PfATP6 after expression and purification from S. cerevisiae was insensitive to artemisinin and significantly less sensitive to thapsigargin and 2,5-di(tert-butyl)-1,4-benzohydroquinone than rabbit SERCA1 but retained higher sensitivity to cyclopiazonic acid, another type of SERCA1 inhibitor. Although mammalian SERCA and purified PfATP6 appear to have different pharmacological profiles, their insensitivity to artemisinins suggests that the mechanism of action of this class of drugs on the calcium metabolism in the intact cell is complex and cannot be ascribed to direct inhibition of PfATP6. Furthermore, the successful purification of PfATP6 affords the opportunity to develop new antimalarials by screening for inhibitors against PfATP6. 相似文献
143.
144.
Schröder O Yudina Y Sabirsh A Zahn N Haeggström JZ Stein J 《Journal of lipid research》2006,47(5):1071-1080
Prostaglandin (PG) E(2) (PGE(2)) plays a predominant role in promoting colorectal carcinogenesis. The biosynthesis of PGE(2) is accomplished by conversion of the cyclooxygenase (COX) product PGH(2) by several terminal prostaglandin E synthases (PGES). Among the known PGES isoforms, microsomal PGES type 1 (mPGES-1) and type 2 (mPGES-2) were found to be overexpressed in colorectal cancer (CRC); however, the role and regulation of these enzymes in this malignancy are not yet fully understood. Here, we report that the cyclopentenone prostaglandins (CyPGs) 15-deoxy-Delta(12,14)-PGJ(2) and PGA(2) downregulate mPGES-2 expression in the colorectal carcinoma cell lines Caco-2 and HCT 116 without affecting the expression of any other PGES or COX. Inhibition of mPGES-2 was subsequently followed by decreased microsomal PGES activity. These effects were mediated via modulation of the cellular thiol-disulfide redox status but did not involve activation of the peroxisome proliferator-activated receptor gamma or PGD(2) receptors. CyPGs had antiproliferative properties in vitro; however, this biological activity could not be directly attributed to decreased PGES activity because it could not be reversed by adding PGE(2). Our data suggest that there is a feedback mechanism between PGE(2) and CyPGs that implicates mPGES-2 as a new potential target for pharmacological intervention in CRC. 相似文献
145.
Phototransduction genes are up-regulated in a global gene expression study of Drosophila melanogaster selected for heat resistance 下载免费PDF全文
Nielsen MM Sørensen JG Kruhøffer M Justesen J Loeschcke V 《Cell stress & chaperones》2006,11(4):325-333
The genetic architecture underlying heat resistance remains partly unclear despite the well-documented involvement of heat shock proteins (Hsps). It was previously shown that factors besides Hsps are likely to play an important role for heat resistance. In this study, gene expression arrays were used to make replicate measurements of gene expression before and up to 64 hours after a mild heat stress treatment, in flies selected for heat resistance and unselected control flies, to identify genes differentially expressed in heat resistance-selected flies. We found 108 genes up-regulated and 10 down-regulated using the Affymetrix gene expression platform. Among the up-regulated genes, a substantial number are involved in the phototransduction process. Another group of genes up-regulated in selected flies is characterized by also responding to heat shock treatment several hours after peak induction of known Hsps revert to nonstress levels. These findings suggest phototransduction genes to be critically involved in heat resistance, and support a role for components of the phototransduction process in stress-sensing mechanisms. In addition, the results suggest yet-uncharacterized genes responding to heat stress several hours after treatment to be involved in heat stress resistance. These findings mark an important increase in the understanding of heat resistance. 相似文献
146.
147.
Crystals of sarcoplasmic reticulum Ca(2+)-ATPase 总被引:1,自引:0,他引:1
High-resolution structures of the Ca(2+)-ATPase have over the last 5 years added a structural dimension to our understanding of the function of this integral membrane protein. The Ca(2+)-ATPase is now by far the membrane protein where the most functionally different conformations have been described in precise structural detail. Here, we review our experience from solving Ca(2+)-ATPase structures: a purification scheme involving minimum handling of the protein to preserve natural and essential lipids, a rational approach to screening for crystals based on a limited number of polyethyleneglycols and many different salts, improving crystal quality using additives, collecting the data and finally solving the structures. We argue that certain of the lessons learned in the present study are very likely to be useful for crystallisation of eukaryotic membrane proteins in general. 相似文献
148.
Chan HL Jansson J Lam TW Yiu SM 《Journal of bioinformatics and computational biology》2006,4(4):807-832
Given a distance matrix M that specifies the pairwise evolutionary distances between n species, the phylogenetic tree reconstruction problem asks for an edge-weighted phylogenetic tree that satisfies M, if one exists. We study some extensions of this problem to rooted phylogenetic networks. Our main result is an O(n(2) log n)-time algorithm for determining whether there is an ultrametric galled network that satisfies M, and if so, constructing one. In fact, if such an ultrametric galled network exists, our algorithm is guaranteed to construct one containing the minimum possible number of nodes with more than one parent (hybrid nodes). We also prove that finding a largest possible submatrix M' of M such that there exists an ultrametric galled network that satisfies M' is NP-hard. Furthermore, we show that given an incomplete distance matrix (i.e. where some matrix entries are missing), it is also NP-hard to determine whether there exists an ultrametric galled network which satisfies it. 相似文献
149.
He YJ Huynh TN Jansson J Sung WK 《Journal of bioinformatics and computational biology》2006,4(1):59-74
To construct a phylogenetic tree or phylogenetic network for describing the evolutionary history of a set of species is a well-studied problem in computational biology. One previously proposed method to infer a phylogenetic tree/network for a large set of species is by merging a collection of known smaller phylogenetic trees on overlapping sets of species so that no (or as little as possible) branching information is lost. However, little work has been done so far on inferring a phylogenetic tree/network from a specified set of trees when in addition, certain evolutionary relationships among the species are known to be highly unlikely. In this paper, we consider the problem of constructing a phylogenetic tree/network which is consistent with all of the rooted triplets in a given set C and none of the rooted triplets in another given set F. Although NP-hard in the general case, we provide some efficient exact and approximation algorithms for a number of biologically meaningful variants of the problem. 相似文献
150.
Recent work suggests that protein fibrillation mechanisms and the structure of the resulting protein fibrils are very sensitive to environmental conditions such as temperature and ionic strength. Here we report the effect of several inorganic salts on the fibrillation of glucagon. At acidic pH, fibrillation is much less influenced by cations than anions, for which the effects follow the electroselectivity series; e.g., the effect of sulfate is approximately 65-fold higher than that of chloride per mole. Increased salt concentrations generally accelerate fibrillation, but result in formation of an alternate type of fibrils. Stability of these fibrils is highly affected by changes in anion concentration; the apparent melting temperature is increased by approximately 22 degrees C for any 10-fold concentration increase, indicating that the fibrils cannot exist without anions. In contrast, fibrillation under alkaline conditions is more affected by cations than anions. We conclude that ions interact directly as structural ligands with glucagon fibrils where they coordinate charges and assist in formation of new fibrils. As ex vivo amyloid plaques often contain large amounts of highly sulfated organic molecules, the specific effects of sulfate ions on glucagon may have general relevance in the study of amyloidosis and other protein deposition diseases. 相似文献