• Molecules and Cells
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• v.23 no.1
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• pp.1-10
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• 2007

Invading pathogens are recognized by diverse germline-encoded pattern-recognition receptors (PRRs) which are distributed in three different cellular compartments: extracellular, membrane, and cytoplasmic. In mammals, the major extracellular PRRs such as complements may first encounter the invading pathogens and opsonize them for clearance by phagocytosis which is mediated by membrane-associated phagocytic receptors including complement receptors. The major membrane-associated PRRs, Toll-like receptors, recognize diverse pathogens and generate inflammatory signals to coordinate innate immune responses and shape adaptive immune responses. Furthemore, certain membrane-associated PRRs such as Dectin-1 can mediate phagocytosis and also induce inflammatory response. When these more forefront detection systems are avoided by the pathogens, cytoplasmic PRRs may play major roles. Cytoplasmic caspase-recruiting domain (CARD) helicases such as retinoic acid-inducible protein I (RIG-I)/melanoma differentiation-associated gene 5 (MDA5), mediate antiviral immunity by inducing the production of type I interferons. Certain members of nucleotide-binding oligomerization domain (NOD)-like receptors such as NALP3 present in the cytosol form inflammasomes to induce inflammatory responses upon ligand recognition. Thus, diverse families of PRRs coordinately mediate immune responses against diverse types of pathogens.

• Animal cells and systems
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• v.13 no.1
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• pp.1-8
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• 2009

Toll-like receptor (TLR) family proteins, type I transmembrane proteins, play a central role in human innate immune response by recognizing common structural patterns in diverse molecules from bacteria, viruses and fungi. Recently four structures of the TLR and ligand complexes have been determined by high resolution x-ray crystallographic technique. In this review we summarize reported structures of TLRs and their proposed activation mechanisms. The structures demonstrate that binding of agonistic ligands to the extracellular domains of TLRs induces homo- or heterodimerization of the receptors. Dimerization of the TLR extracellular domains brings their two C-termini into close proximity. This suggests a plausible mechanism of TLR activation: ligand induces dimerization of the extracellular domains, which enforces juxtaposition of intracellular signaling domains for recruitment of intracellular adaptor proteins for signal initiation.

• BMB Reports
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• v.47 no.4
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• pp.184-191
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• 2014

Respiratory syncytial virus (RSV) is the leading cause of respiratory infection in infants and young children. Severe clinical manifestation of RSV infection is a bronchiolitis, which is common in infants under six months of age. Recently, RSV has been recognized as an important cause of respiratory infection in older populations with cardiovascular morbidity or immunocompromised patients. However, neither a vaccine nor an effective antiviral therapy is currently available. Moreover, the interaction between the host immune system and the RSV pathogen during an infection is not well understood. The innate immune system recognizes RSV through multiple mechanisms. The first innate immune RSV detectors are the pattern recognition receptors (PRRs), including toll-like receptors (TLRs), retinoic acid-inducible gene-I (RIG-I)-like receptors (RLRs), and nucleotide-biding oligomerization domain (NOD)-like receptors (NLRs). The following is a review of studies associated with various PRRs that are responsible for RSV virion recognition and subsequent induction of the antiviral immune response during RSV infection.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2006.11a
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• pp.103-115
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• 2006

$\beta$-Glucan is a glucose polymer that has linkage of $\beta$-(1,3), -(1,4) and -(1,6). As exclusively found in fungal and bacterial cell wall, not in animal, $\beta$-glucans are recognized by innate immune system. Dendritic cells (DC) or macrophages possesses pattern recognition molecule (PRM) for binding $\beta$-glucan as pathogen-associated molecular pattern (PAMP). Recently $\beta$-glucan receptor was cloned from DC and named as dectin-l which belongs to type II C-type lectin family. Human dectin-1 is consisted of 7 exons and 6 introns. The polypeptide of dectin-1 has 247 amino acids and has cytoplasmic, transmembrane, stalk and carbohydrate recognition domains. Dectin-1 could recognize variety of beta-1,3 and/or beta-1,6 glucan linkages, but not alpha-glucans. In our macrophage cell line culture system, dectin-1 mRNA was detected in RA W264.7 cells by reverse transcription-polymerase chain reaction (RT-PCR). Dectin-1 was also detected in the murine organs of spleen, thymus, lung and intestines. Treatment of RA W264.7 cells with $\beta$-glucans of Ganoderma lucidum (GLG) resulted in increased expression of IL-6 and TNF-$\alpha$ in the presence of LPS. However, GLG alone did not increase IL-6 nor TNF-$\alpha$. These results suggest that receptor dectin-1 cooperate with CD14 to activate signal transduction that is very critical in immunoresponse.

• 한국약용작물학회:학술대회논문집
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• 2006.11a
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• pp.103-115
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• 2006

[ ${\beta}-Glucan$ ] is a glucose polymer that has linkage of ${\beta}-(1,3)$, -(1,4) and -(1,6). As exclusively found in fungal and bacterial cell wall, not in animal, ${\beta}-glucans$ are recognized by innate immune system. Dendritic cells (DC) or macrophages possesses pattern recognition molecule (PRM) for binding ${\beta}-glucans$ as pathogen-associated molecular pattern (PAMP). Recently ${\beta}-glucans$ receptor was cloned from DC and named as dectin-l which belongs to type II C-type lectin family. Human dectin-l is consisted of 7 exons and 6 introns. The polypeptide of dectin-l has 247 amino acids and has cytoplasmic, transmembrane, stalk and carbohydrate recognition domains. Dectin-l could recognize variety of beta-l,3 and/or beta-l,6 glucan linkages, but not alpha-glucans. In our macrophage cell line culture system, dectin-l mRNA was detected in RA W264.7 cells by reverse transcription-polymerase chain reaction (RT-PCR). Dectin-l was also detected in the murine organs of spleen, thymus, lung and intestines. Treatment of RA W264.7 cells with ${\beta}-glucans$ of Ganoderma lucidum (GLG) resulted in increased expression of IL-6 and $TNF-{\alpha}$ in the presence of LPS. However, GLG alone did not increase IL-6 nor $TNF-{\alpha}$ These results suggest that receptor dectin-l cooperate with CD14 to activate signal transduction that is very critical in immunoresponse.

• The Korean Journal of Malacology
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• v.31 no.3
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• pp.233-241
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• 2015

Toll-like receptors (TLRs) are a major pattern recognition receptor that recognize the structure of invading pathogen and play key roles by triggering immune response. In this study, we identified a sequence of TLR homolog and characterized at molecular level from the abalone (Haliotis discus hannai). Multiple alignments and phylogenetic analysis of abalone TLR protein belongs to the TLR 2/6. Expression level of abalone TLR 2/6 in the tissue was comparatively high in the mantle, gill, digestive duct, and hemocytes, but lowest in the muscle. Expression level of abalone TLR 2/6 mRNA in the mantle, gill, digestive duct, and hemocytes was 20-fold, 60-fold, 115-fold, 112-fold higher than in the muscle, respectively. Expression level of abalone TLR 2/6 mRNA in the mantle was steadily increased until 12 h and decreased post-infection with Vibrio parahemolyticus. While the expression level of abalone TLR 2/6 mRNA in the gill and hemocytes was drastically increased at 6 and 9 h post-infection with Vibrio parahemolyticus, respectively. These results suggest that abalone TLR 2/6 is conserved through evolution and may play roles similar to its mammalian counterparts.

• International Journal of Oral Biology
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• v.33 no.3
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• pp.77-82
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• 2008

Innate immune response is initiated by the recognition of unique microbial molecular patterns through pattern recognition receptors (PRRs). The purpose of this study is to dissect the expression of various PRRs in gingival epithelial cells of differentiated versus undifferentiated states. Differentiation of immortalized human gingival epithelial HOK-16B cells was induced by culture in the presence of high $Ca^{2+}$ at increased cell density. The expression levels of various PRRs in HOK-16B cells were examined by realtime reverse transcription polymerase chain reaction (RTPCR) and flow cytometry. In addition, the expression of human beta defensins (HBDs) was examined by real time RT-PCR and the amounts of secreted cytokines were measured by enzyme linked immunosorbent assay. In undifferentiated HOK-16B cells, NACHT-LRR-PYDcontaining protein (NALP) 2 was expressed most abundantly, and toll like receptor (TLR) 2, TLR4, nucleotide-binding oligomerization domain (NOD) 1, and NOD2 were expressed in substantial levels. However, TLR3, TLR7, TLR8, TLR9, ICE protease-activating factor (IPAF), and NALP6 were hardly expressed. In differentiated cells, the levels of NOD2, NALP2, and TLR4 were different from those in undifferentiated cells at RNA but not at protein levels. Interestingly, differentiated cells expressed the increased levels of HBD-1 and -3 but secreted reduced amount of IL-8. In conclusion, the repertoire of PRRs expressed by gingival epithelial cells is limited, and undifferentiated and differentiated cells express similar levels of PRRs.

• Fisheries and Aquatic Sciences
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• v.25 no.11
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• pp.559-571
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• 2022

Galectins, a family of ß-galactoside-binding lectins, have emerged as soluble mediators in infected cells and pattern recognition receptors (PRRs) responsible for evoking and regulating innate immunity. The present study aimed to evaluate the role of galectin-1 in the host immune response of redlip mullet (Liza haematocheilia). We established a cDNA database for redlip mullet, and the cDNA sequence of galectin-1 (LhGal-1) was characterized. In silico analysis was performed, and the spatial and temporal expression patterns in gills and blood in response to lipopolysaccharide polyinosinic:polycytidylic acid, and Lactococcus garvieae were estimated via quantitative real-time PCR. Functional assays were conducted using recombinant protein to investigate carbohydrate binding, bacterial binding, and bacterial agglutination activity. LhGal-1 was composed of 135 amino acids. Conserved motifs (H-NPR, -N- and -W-E-R) within the carbohydrate recognition domain were found in LhGal-1. The tissue distribution revealed that the healthy stomach expressed high levels of LhGal-1. The temporal monitoring of LhGal-1 mRNA expression in the gill and blood showed its significant upregulation in response to immune challenges with different stimulants. rLhGal-1 exhibited binding activity in response to carbohydrates and bacteria. Moreover, the agglutination of rLhGal-1 against Escherichia coli was observed. Collectively, our findings suggest that LhGal-1 may function as a PRR in redlip mullet. Furthermore, LhGal-1 can be considered a significant gene to play a protective role in redlip mullet immune system.

• IMMUNE NETWORK
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• v.21 no.6
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• pp.42.1-42.20
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• 2021

Eosinophils play critical roles in the maintenance of homeostasis in innate and adaptive immunity. Although primarily known for their roles in parasitic infections and the development of Th2 cell responses, eosinophils also play complex roles in other immune responses ranging from anti-inflammation to defense against viral and bacterial infections. However, the contributions of pattern recognition receptors in general, and NOD-like receptors (NLRs) in particular, to eosinophil involvement in these immune responses remain relatively underappreciated. Our in vivo studies demonstrated that NLRC4 deficient mice had a decreased number of eosinophils and impaired Th2 responses after induction of an allergic airway disease model. Our in vitro data, utilizing human eosinophilic EoL-1 cells, suggested that TLR2 induction markedly induced pro-inflammatory responses and inflammasome forming NLRC4 and NLRP3. Moreover, activation by their specific ligands resulted in caspase-1 cleavage and mature IL-1β secretion. Interestingly, Th2 responses such as secretion of IL-5 and IL-13 decreased after transfection of EoL-1 cells with short interfering RNAs targeting human NLRC4. Specific induction of NLRC4 with PAM3CSK4 and flagellin upregulated the expression of IL-5 receptor and expression of Fc epsilon receptors (FcεR1α, FcεR2). Strikingly, activation of the NLRC4 inflammasome also promoted expression of the costimulatory receptor CD80 as well as expression of immunoregulatory receptors PD-L1 and Siglec-8. Concomitant with NLRC4 upregulation, we found an increase in expression and activation of matrix metalloproteinase (MMP)-9, but not MMP-2. Collectively, our results present new potential roles of NLRC4 in mediating a variety of eosinopilic functions.

• Korean Journal of Environmental Agriculture
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• v.40 no.1
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• pp.1-12
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• 2021

BACKGROUND: G protein-coupled receptors (GPCRs) are widely distributed in various organisms. Insect GPCRs shown as in vertebrate GPCRs are membrane receptors that coordinate or involve in various physiological processes such as learning/memory, development, locomotion, circadian rhythm, reproduction, etc. This study aimed to identify GPCRs expressed in fat body and compare the expression pattern of GPCRs in different temperature conditions. METHODS AND RESULTS: To identify GPCRs genes and compare their expression in different temperature conditions, total RNAs of fat body in Plutella xylostella larva were extracted and the transcriptomes have been analyzed via next generation sequencing method. From the fat body transcriptomes, genes that belong to GPCR Family A, B, and F were identified such as opsin, gonadotropin-releasing hormone receptor, neuropeptide F (NPF) receptor, muthuselah (Mth), diuretic hormone receptor, frizzled, etc. Under low temperature, expressions of GPCRs such as C-C chemokine receptor (CCR), opsin, prolactin-releasing peptide receptor, substance K receptor, Mth-like receptor, diuretic hormone receptor, frizzled and stan were higher than those at 25℃. They are involved in immunity, feeding, movement, odorant recognition, diuresis, and development. In contrast to the control (25℃), at high temperature GPCRs including CCR, gonadotropin-releasing hormone receptor, moody, NPF receptor, neuropeptide B1 receptor, frizzled and stan revealed higher expression whose biological functions are related to immunity, blood-brain barrier formation, feeding, learning, and reproduction. CONCLUSION: Transcriptome of fat body can provide understanding the pools of GPCRs. Identifications of fat body GPCRs may contribute to develop new targets for the control of insect pests.