To investigate the system used by insects to recognize invading microorganisms, we examined proteins from the larval hemolymph of Bombyx mori that bind to the cell surface of microorganisms. Two hemolymph proteins that bound to the cell surfaces of Micrococcus luteus and Saccharomyces cerevisiae were shown to be identical. This protein bound to all 11 microorganisms examined–5 Gram-negative bacteria, 3 Gram-positive bacteria, and 3 yeasts–and was consequently designated B. mori multibinding protein (BmMBP). The sequence of the cDNA encoding BmMBP revealed that it was a C-type lectin with two dissimilar carbohydrate-recognition domains (CRD1 and CRD2) distantly related to known insect C-type lectins. CRD1 and CRD2 were prepared as recombinant proteins and their binding properties were investigated using inhibition assays. Each domain had wide, dissimilar binding spectra to sugars. These properties enable BmMBP to bind to two sites on a microorganism, facilitating high-affinity binding to many types of microorganisms. The dissociation constants of BmMBP with M. luteus cells and S. cerevisiae were 1.23 × 10−8 and 1.00 × 10−11 M, respectively. rBmMBP triggered the aggregation of hemocytes from B. mori larvae in vitro and microorganisms recognized by BmMBP were surrounded by aggregated hemocytes in vivo, forming a nodule, which is the typical cellular reaction in insect immune responses. These observations suggest that BmMBP functions as a trigger for the nodule reaction and that the multirecognition characteristic of BmMBP plays an important role in the early stages of infection by a variety of microorganisms.

TLR3 and cytoplasmic RIG-I-like receptor (RLR) recognize virus-derived dsRNA and induce type I IFN production in a distinct manner. Human TLR3 localizes to the endosomal compartments in myeloid dendritic cells (mDCs), while it localizes to both the cell surface and interior in fibroblasts and epithelial cells. TLR3 signaling arises in the intracellular compartment in both cell types and requires endosomal maturation. The mechanisms by which extracellular dsRNA is delivered to the TLR3-containing organelle remain largely unknown. Among various synthetic dsRNAs, poly(I:C) is preferentially internalized and activates TLR3 in mDCs. In vitro transcribed dsRNAs hardly induce IFN-β production in mDCs. In this study, we demonstrate that the clathrin-dependent endocytic pathway mediates cell entry of poly(I:C) to induce IFN-β gene transcription. Furthermore, poly(I:C)-induced IFN-β production is inhibited by pretreatment of cells with B- and C-type oligodeoxynucleotides (ODNs) but not with TLR7/8 ligands. The binding and internalization of B-type ODNs by mDCs was reduced in the presence of poly(I:C), suggesting that poly(I:C) shares the uptake receptor with B- and C-type ODNs. Hence, foreign dsRNA is recognized by differently categorized receptors, cytoplasmic RIG-I-like receptor, membrane-bound TLR3 and cell-surface RNA capture. The endocytic pathway is critical for dsRNA-induced TLR3-mediated cell activation.

The double-stranded RNA analog, poly(I:C), extracellularly activates both the endosomal Toll-like receptor (TLR) 3 and the cytoplasmic RNA helicase, melanoma differentiation-associated gene 5, leading to the production of type I interferons (IFNs) and inflammatory cytokines. The mechanism by which extracellular poly(I:C) is delivered to TLR3-positive organelles and the cytoplasm remains to be elucidated. Here, we show that the cytoplasmic lipid raft protein, Raftlin, is essential for poly(I:C) cellular uptake in human myeloid dendritic cells and epithelial cells. When Raftlin was silenced, poly(I:C) failed to enter cells and induction of IFN-␤ production was inhibited. In addition, cellular uptake of B-type oligodeoxynucleotide that shares its uptake receptor with poly

The novel protein EHBP1L1 links Rab8 to Bin1and dynamin to regulate apical transport in epithelial cells.

. 519:215-220, 2002), by using monoclonal antibodies (MAbs) that block binding between the binding site and the receptor. First, we produced a series of MAbs against Cry1Aa and obtained two MAbs, MAbs 2C2 and 1B10, that were capable of blocking the binding between Cry1Aa and BmAPN1 (blocking MAbs). The epitope of the Fab fragments of MAb 2C2 overlapped the BmAPN1 binding site, whereas the epitope of the Fab fragments of MAb 1B10 did not overlap but was located close to the binding site. Using three approaches for epitope mapping, we identified two candidate epitopes for the blocking MAbs on Cry1Aa. We constructed two Cry1Aa toxin mutants by substituting a cysteine on the toxin surface at each of the two candidate epitopes, and the small blocking molecule N-(9-acridinyl)maleimide (NAM) was introduced at each cysteine substitution to determine the true epitope. The Cry1Aa mutant with NAM bound to Cys582 did not bind either of the two blocking MAbs, suggesting that the true epitope for each of the blocking MAbs was located at the site containing Val582, which also consisted of 508 STLRVN 513 and 582 VFTLSAHV 589 . These results indicated that the BmAPN1 binding site overlapped part of the region blocked by MAb 2C2 that was close to but excluded the actual epitope of MAb 2C2 on domain III of Cry1Aa toxin. We also discuss another area on Cry1Aa toxin as a new candidate site for BmAPN1 binding.Bacillus thuringiensis, a gram-positive bacterium, produces various insecticidal proteins called Cry toxins which kill only target insects. This bacterium is used as a microbial insecticide and for the genetic development of insect-resistant plants.Cry toxins are expressed in inclusion bodies as protoxins (70 to 140 kDa) during sporulation. When a protoxin is ingested by target insects, it is solubilized in the insect midgut and digested by proteolytic enzymes in the insect (2). After enzymatic activation, the toxic protease-resistant fragment, which is the 60-to 65-kDa activated toxin, binds to specific receptors located in the columnar cells of the midgut apical brush border membrane (28). The binding of the toxin to receptor molecules leads to a conformational change in the toxin. This allows the toxin to insert into the plasma membrane and subsequently generate pores or ion channels which lead to cellular swelling and lysis (27,35,65,68). Finally, the intoxicated insects die. The binding of the activated toxin to a specific gut receptor is considered to be one of the key factors for insect toxicity. The insecticidal specificity of Cry toxins seems to be largely dependent on this receptor recognition.The three-dimensional structures of Cry1Aa trypsin-activated toxin, Cry2A protoxin, Cry3A, and Cry3B have been analyzed by X-ray diffraction crystallography (14,25,43,51). These proteins are comprised of three domains. The Cry1Aa and Cry3A structures have many similar features. The N-terminal domain I is composed of a seven-alpha-helix bundle in which the alpha-5 helix is encircled by the other helices. Domain II consists of thre...

serovar Typhimurium ( Typhimurium) and its monophasic variant ( 4,[5],12:i:-) are the major causes of gastroenteritis in both humans and animals. Pulsed-field gel electrophoresis and multilocus variable-number tandem-repeat analysis have been used widely as subtyping methods for these pathogens in molecular epidemiological analyses, but the results do not precisely reflect phylogenetic information. In this study, we performed a phylogenetic analysis of these serovars using whole-genome sequencing data and identified nine distinct genotypic clades. Then, we established an allele-specific PCR-based genotyping method detecting a clade-specific single nucleotide polymorphism to rapidly identify the clade of each isolate. Among a total of 815 isolates obtained from cattle in Japan between 1977 and 2017, clades 1, 7, and 9 contained 77% of isolates. Obvious replacement of the dominant clone was observed five times in this period, and clade 9, which mostly contains 4,[5],12:i:-, is currently dominant. Among 140 isolates obtained from swine in Japan between 1976 and 2017, clades 3 and 9 contained 64% of isolates. Clade 9 is the latest clone as is the case in cattle isolates. Clade 9 is similar to an epidemic clone from Europe, which is characterized by sequence type 34 (ST34), chromosomal genomic island 3, and a composite transposon containing antimicrobial resistance genes. The increased prevalence of clade 9 among food animals in Japan might be a part of the pandemic of the European 4,[5],12:i:- clone.

We have previously reported increased expression of ma-matrix proteins and are involved in tissue remodeling during fibrotic and/or inflammatory processes. In addition, a num-trix metalloproteinase-2 (MMP-2) using a rat model of liver fibrosis. However we did not clarify how the precursor of ber of studies have provided evidence for the involvement of MMPs and their inhibitors in various processes including MMP-2 (proMMP-2) was activated. Therefore, we used human liver specimens with chronic hepatitis (CH) and liver cirrhosis ovulation, 3 embryogenic growth, and differentiation, 4,5 or tumor invasion and metastasis. 6-8 (LC) to examine expression of membrane-type-1-MMP (MT1-MMP), which has recently been determined to activateWe have previously reported increased expression of MMP-2 (72 kd type IV collagenase, gelatinase A) in a rat proMMP-2. Northern hybridization studies showed a 5.4-and 1.4-fold increase in MMP-2 expression in CH and LC, respec-experimental model of liver fibrosis induced by CCl 4 intoxication. 9 In paticular, the active form of MMP-2 increased tively, as compared with normal liver. MT1-MMP gene expression simultaneously increased 4.0-and 1.4-fold in CH and during the fibrosing process and may act to remodel the space of Disse. However, the activation of proMMP-2 during LC, respectively. In situ hybridization using 35 S-cRNA probes of MMP-2 and MT1-MMP showed prominent silver granules this fibrotic process has not been studied.Activity of MMPs may be regulated at the level of gene in elongated cells found in the lobules, periportal areas, and fibrous septa of CH and LC samples. These elongated cells transcription, during proenzyme activation, or during binding of the proenzyme or active enzyme to specific inhibitors expressed a-smooth muscle actin by immunohistochemistry. Immunoelectron microscopic examination localized MMP-2 like the tissue inhibitor of metalloproteinases (TIMPs). 10,11 The mechanism of MMP-2 proenzyme activation differs from and MT1-MMP to the rough endoplasmic reticulum of stellate cells located in the lobules and periportal areas, or to fibro-that of other MMPs in that serine proteases such as plasmin, neutrophil elastase, and trypsin can activate several blasts in the fibrous septa, suggesting that MMP-2 and MT1-MMP were produced by these cells. In addition, cytoplasmic proMMPs, but fail to activate proMMP-2. 12 Recently, a unique activator of proMMP-2 was found on various cell and membranous immunodeposits of both MMPs were found in endothelial cells, Kupffer cells, capillary endothelial cells, surfaces and identified as membrane-type MMPs (MT-MMPs). [13][14][15][16] Because MMP-2 is an important enzyme in the and lymphocytes, indicating that activation of proMMP-2 occurs locally. Increased expression of MMP-2 and MT1-MMP degradation of type IV collagen found in basement membranes, MT-MMPs present on tumor cell surfaces is thought was detected in CH and LC, while dual over-expression was found in stellate cells and fibroblasts, possibly resulting in to play a crucial ...

The DEAD box helicase DDX3 assembles IPS-1 (also called Cardif, MAVS, or VISA) in non-infected human cells where minimal amounts of the RIG-I-like receptor (RLR) protein are expressed. DDX3 C-terminal regions directly bind the IPS-1 CARD-like domain as well as the N-terminal hepatitis C virus (HCV) core protein. DDX3 physically binds viral RNA to form IPS-1-containing spots, that are visible by confocal microscopy. HCV polyU/UC induced IPS-1-mediated interferon (IFN)-beta promoter activation, which was augmented by co-transfected DDX3. DDX3 spots localized near the lipid droplets (LDs) where HCV particles were generated. Here, we report that HCV core protein interferes with DDX3-enhanced IPS-1 signaling in HEK293 cells and in hepatocyte Oc cells. Unlike the DEAD box helicases RIG-I and MDA5, DDX3 was constitutively expressed and colocalized with IPS-1 around mitochondria. In hepatocytes (O cells) with the HCV replicon, however, DDX3/IPS-1-enhanced IFN-beta-induction was largely abrogated even when DDX3 was co-expressed. DDX3 spots barely merged with IPS-1, and partly assembled in the HCV core protein located near the LD in O cells, though in some O cells IPS-1 was diminished or disseminated apart from mitochondria. Expression of DDX3 in replicon-negative or core-less replicon-positive cells failed to cause complex formation or LD association. HCV core protein and DDX3 partially colocalized only in replicon-expressing cells. Since the HCV core protein has been reported to promote HCV replication through binding to DDX3, the core protein appears to switch DDX3 from an IFN-inducing mode to an HCV-replication mode. The results enable us to conclude that HCV infection is promoted by modulating the dual function of DDX3.