Biomedical subjects

Yuichi Endo

Publications and source records attributed to Yuichi Endo.

14 recordsLinked to original sources

PubMed2005

Human M-ficolin is a secretory protein that activates the lectin complement pathway.

Three types of ficolins have been identified in humans: L-ficolin, M-ficolin, and H-ficolin. Similar to mannose-binding lectin, L-ficolin and H-ficolin are the recognition molecules in the lectin complement pathway. Another human ficolin, M-ficolin, is a nonserum ficolin that is expressed in leukocytes and lung; however, little is known about its physiologic roles. In this study, we report the characterization of M-ficolin in terms of its protein localization and lectin activity. M-ficolin was localized in secretory granules in the cytoplasm of neutrophils, monocytes, and type II alveolar epithelial cells in lung. M-ficolin precipitated with mannose-binding lectin-associated serine proteases (MASP)-1 and MASP-2 in a co-immunoprecipitation assay, indicating that M-ficolin forms complexes with MASP-1 and MASP-2. M-ficolin-MASP complexes activated complement on N-acetylglucosamine (GlcNAc)-coated microplates in a C4 deposition assay. M-ficolin bound to several neoglycoproteins bearing GlcNAc, N-acetylgalactosamine, and sialyl-N-acetyllactosamine, suggesting that M-ficolin can recognize the common carbohydrate residues found in microbes. Indeed, M-ficolin bound to Staphylococcus aureus through GlcNAc. These results indicate that M-ficolin, like its family members, functions as a recognition molecule of the lectin complement pathway and plays an important role in innate immunity.

Complement Activation↗

PubMed2005

Ficolin A and ficolin B are expressed in distinct ontogenic patterns and cell types in the mouse.

Ficolins are a group of proteins characterized by the presence of collagen-like and fibrinogen-like domains. Two of three human ficolins, L-ficolin and H-ficolin, are serum lectins that form complexes with mannose-binding lectin-associated serine proteases (MASPs) and play important roles in the lectin complement pathway. The other human ficolin, M-ficolin, is a non-serum-type ficolin that is expressed in monocytes. Little is known about the physiological roles of ficolins. In this study, we delineated the ontogeny and cell types that express ficolins in mice. RT-PCR analysis showed that the expression pattern of ficolin A expression was closely similar to that of Masps, suggesting that these molecules may function in coordination as components of the lectin complement pathway. The cell types that express ficolin A mRNA in both adult liver and spleen were identified as macrophages by in situ hybridization. Ficolin B exhibited a distinct ontogeny pattern that switched from embryonic liver to postnatal bone marrow and spleen. The cells that express ficolin B mRNA were identified as belonging to the myeloid cell lineage by magnetic sorting and by subsequent RT-PCR in bone marrow cells. Thus, the different spatial-temporal expression patterns of ficolins A and B suggest that these molecules play distinct roles in the prenatal and postnatal stages.

Animals↗

PubMed2004

Origin of the classical complement pathway: Lamprey orthologue of mammalian C1q acts as a lectin.

The lectin complement pathway in innate immunity is closely related to the classical complement pathway in adaptive immunity, with respect to the structures and functions of their components. Both pathways are initiated by complexes consisting of collagenous proteins and serine proteases of the mannose-binding lectin (MBL)-associated serine protease (MASP)/C1r/C1s family. It has been speculated that the classical pathway emerged after the lectin pathway, and that the activation mechanism of the latter was partially conserved. The classical and lectin pathways can be traced back to at least cartilaginous fish and ascidian (urochordata), respectively. To elucidate the evolution of the complement system, we isolated and characterized a GlcNAc-binding lectin from sera of lamprey (agnathans), the most primitive vertebrate that lacks the classical pathway. Lamprey GlcNAc-binding lectin was an oligomer consisting of 24-kDa subunits. cDNA and phylogenetic analyses revealed that the lamprey GlcNAc-binding lectin is an orthologue of mammalian C1q, a collagenous subcomponent of the first component involved in binding to immunoglobulins in the classical pathway. Lamprey C1q copurified with MASP-A, a serine protease of the MASP/C1r/C1s family, which exhibited proteolytic activity against lamprey C3. Surface plasmon resonance analysis showed that lamprey C1q specifically bound to GlcNAc, but not various other carbohydrates tested. These results suggest that C1q may have emerged as a lectin and may have functioned as an initial recognition molecule of the complement system in innate immunity before the establishment of adaptive immunity such as immunoglobulins in the cartilaginous fish.

Amino Acid Sequence↗

PubMed2004

Survival of mitomycin C-treated pancreatic islet xenografts is mediated by increased expression of transforming growth factor-beta.

BACKGROUND: Mitomycin C (MMC) can trigger various intracellular signals. The authors previously showed that pretreatment of highly immunogenic crude pancreatic islets with MMC improved their survival in a rat-to-mouse transplantation model. The aim of this study was to investigate the role of transforming growth factor (TGF)-beta in mediating MMC-induced survival of islet xenografts. METHODS: : Collagenase-digested islets obtained from WS rats (RT1k) were incubated for 30 min with 10 microg/mL MMC and then transplanted into streptozotocin-induced diabetic C57BL/6 (H-2b) mice after 20 hr of culture at 37 degrees C. RESULTS: Survival of xenografts was enhanced by pretreatment of islets with MMC. MMC-treated xenografts showed a mild inflammatory cell response and significantly minimal infiltration of macrophages, CD4 T cells, and CD8 T cells compared with untreated grafts. TGF-beta mRNA was increased at 20 hr after MMC treatment, and TGF-beta protein expression was also increased compared with untreated islet xenografts. TGF-beta concentration in blebs formed around the xenografts (but not in the serum) was higher in animals that underwent transplantation with MMC-treated islets than with untreated islets. Simultaneous transplantation of MMC-treated and untreated islets separately in each kidney of recipient mice showed that protection was only found in MMC-treated islets. Treatment of islets before transplantation by neutralizing anti-TGF-beta antibody suppressed the MMC-protective effects on graft survival, whereas no such effect was noted with isotype-matched immunoglobulin. CONCLUSIONS: : The authors' results indicate that MMC treatment effectively reduces local inflammatory response and that such effects are mediated by increase of TGF-beta during the early period of islet transplantation.

Animals↗

PubMed2004

Primitive complement system--recognition and activation.

The complement system, composed of more than 30 serum and cell surface components, is collaborating in recognition and elimination of pathogens as a part of both the innate and acquired immune systems. The two collagenous lectins, mannose-binding lectin (MBL) and ficolins, are one of the pattern recognition molecules acting in innate immunity and upon recognition of the pathogens, they trigger the activation of the lectin complement pathway through attached serine proteases (MASPs). A similar lectin-base complement system, consisting of the lectin-protease complex and C3, is present in ascidians, our closest invertebrate relatives and functions in an opsonic manner. On the other hand, ongoing genome projects in both vertebrates and invertebrates revealed that most domains used by mammalian complement components are found in both protostomes and deuterostomes. However, the unique combinations of them as found in mammalian complement components are present only in deuterostomes, indicating the deuterostome origin of the complement system. Unexpectedly, the complement system of an invertebrate deuterostome, ascidian, shows a similar level of complexity as that of mammals, suggesting that expansion of complement genes by gene duplications occurred independently both in the ascidian and vertebrate lineages. Although most characteristic domain structures of the mammalian complement components are found in ascidians, detailed evolutionary analysis casts doubt on their mutual reactivity in several points. Thus, another integrative step seems to have been required to establish the modern complement system of higher vertebrates.

Animals↗

PubMed2004

Identification of the mouse H-ficolin gene as a pseudogene and orthology between mouse ficolins A/B and human L-/M-ficolins.

Ficolin is a collagenous lectin which plays a crucial role in innate immunity. Three and two ficolins have been identified in human and mice, respectively. To identify the mouse homologue of human H-ficolin and to elucidate the orthology between mouse ficolins A/B and human L-/M-ficolins, the gene structures were explored. The mouse homologue of the H-ficolin gene was identified as a pseudogene on chromosome 4. The mouse ficolin A gene was located far from the ficolin B gene on chromosome 2, whereas the human L-ficolin and M-ficolin genes were close in the region homologous to the ficolin B locus. Together with the exon-intron structures and the phylogenetic tree, these results suggest that ficolin B is the mouse orthologue of M-ficolin and that the genes encoding serum-type ficolins, ficolin A and L-ficolin, were generated independently from the ficolin B/M-ficolin lineage each in mice and primates.

Amino Acid Sequence↗

PubMed2004

The lectin-complement pathway--its role in innate immunity and evolution.

Innate immunity was formerly thought to be a non-specific immune response characterized by phagocytosis. However, innate immunity has considerable specificity and is capable of discriminating between pathogens and self. Recognition of pathogens is mediated by a set of pattern recognition receptors, which recognize conserved pathogen-associated molecular patterns (PAMPs) shared by broad classes of microorganisms, thereby successfully defending invertebrates and vertebrates against infection. Lectins, carbohydrate-binding proteins, play an important role in innate immunity by recognizing a wide range of pathogens. Mannose-binding lectin (MBL) and ficolin are lectins composed of a lectin domain attached to collagenous region. However, they use a different lectin domain: a carbohydrate recognition domain (CRD) is responsible for MBL and a fibrinogen-like domain for ficolin. These two collagenous lectins are pattern recognition receptors, and upon recognition of the infectious agent, they trigger the activation of the lectin-complement pathway through attached serine proteases, MBL-associated serine proteases (MASPs). A similar lectin-based complement system, consisting of the lectin-protease complex and C3, is present in ascidians, our closest invertebrate relatives, and functions in an opsonic manner. We isolated several lectins homologous to MBLs and ficolins and several MASPs in invertebrates and lower vertebrates, and herein we discuss the molecular evolution of these molecules. Based on these findings, it seems likely that the complement system played a pivotal role in innate immunity before the evolution of an acquired immune system in jawed vertebrates.

Animals↗

PubMed2003

Origin of mannose-binding lectin-associated serine protease (MASP)-1 and MASP-3 involved in the lectin complement pathway traced back to the invertebrate, amphioxus.

Mannose-binding lectin-associated serine proteases (MASPs) are involved in complement activation through the lectin pathway. To elucidate the phylogenetic origin of MASP and a primordial complement system, we cloned two MASP cDNAs from amphioxus (Branchiostoma belcheri) of the cephalochordates, considered to be the closest relative of vertebrates. The two sequences, orthologues of mammalian MASP-1 and MASP-3, were produced by alternative processing of RNA from a single gene consisting of a common H chain-encoding region and two L chain-encoding regions, a structure which is similar to that of the human MASP1/3 gene. We also isolated two MASP genes from the ascidian Halocynthia roretzi (urochordates) and found that each of them consists simply of an H chain-encoding region and a single L chain-encoding region. The difference in structure between the ascidian MASP genes and the amphioxus/mammalian MASP genes suggests that a prototype gene was converted to the MASP1/3-type gene possessing two L chain-encoding regions at an early stage of evolution before the divergence of amphioxus. This conclusion is supported by the presence of MASP-1 and MASP-3 homologues in almost all vertebrates, as demonstrated by the cloning of novel cDNA sequences representing lamprey (cyclostomes) MASP-1 and Xenopus MASP-3. The ancient origin of MASP-1 and MASP-3 suggests that they have crucial functions common to all species which emerged after cephalochordates.

Amino Acid Sequence↗

PubMed2003

Molecular cloning and characterization of novel ficolins from Xenopus laevis.

Ficolins are proteins characterized by the presence of collagen- and fibrinogen-like domains. Two of three human ficolins, L-ficolin and H-ficolin, are serum lectins and are thought to play crucial roles in host defense through opsonization and complement activation. To elucidate the evolution of ficolins and the primordial complement lectin pathway, we cloned four ficolin cDNAs from Xenopus laevis, termed Xenopus ficolin (XeFCN) 1, 2, 3 and 4. The deduced amino acid sequences of the four ficolins revealed the conserved collagen- and fibrinogen-like domains. The full sequences of the four ficolins showed a 42-56% identity to human ficolins, and 60-83% between one another. Northern blots showed that XeFCN1 was expressed mainly in liver, spleen and heart, and XeFCN2 and XeFCN4 mainly in peripheral blood leukocytes, lung and spleen. We isolated ficolin proteins from Xenopus serum by affinity chromatography on N-acetylglucosamine-agarose, followed by ion-exchange chromatography. The final eluate showed polymeric bands composed of two components of 37 and 40 kDa. The N-terminal amino acid sequences and treatment with endoglycosidase F showed that the two bands are the same XeFCN1 protein with different masses of N-linked sugar. The polymeric form of the two types of XeFCN1 specifically recognized GlcNAc and GalNAc residues. These results suggest that like human L-ficolin, XeFCN1 functions in the circulation through its lectin activity.

Amino Acid Sequence↗

PubMed2003

Inhibitory effects of triterpenes isolated from Hoelen on free radical-induced lysis of red blood cells.

Hoelen, sclederma of Poria cocos Wolf, has long been used as a sedative and diuretic in traditional medicine. Formerly, we demonstrated that Hoelen in vitro protects red blood cells from AAPH-induced hemolysis. In this study, tests were carried out to identify the main ingredient of Hoelen that has the scavenging effect on free-radicals. Triterpene carboxylic acids isolated from the methanol extract of Hoelen, i.e. pachymic acid, polyporenic acid, 3-epidehydrotumulosic acid, 3beta-hydroxylanosta-7,9(11), 24-trien-21-oic acid and 3-o-acetyl-16 alpha -hydroxytrametenolic acid, were found to have inhibitory activities against AAPH-induced lysis of red blood cells.

Amidines↗

PubMed2003

A truncated isoform of the protein phosphatase 2A B56gamma regulatory subunit may promote genetic instability and cause tumor progression.

F10, a subline of the B16 mouse melanoma cell line, is itself the parent of the more metastatic BL6 line. BL6 cells differ from F10 cells by an alteration of the gene encoding the B56gamma regulatory subunit of protein phosphatase 2A (PP2A), which results in the expression of a truncated variant of the subunit (Deltagamma1). PP2A is involved in regulating the cell-cycle checkpoint and we found that the checkpoint in BL6 cells is aberrant when the Deltagamma1 protein is expressed. That is, although Deltagamma1 protein levels in cultured BL6 cells are low and these cells do not show an altered checkpoint on gamma-irradiation, irradiated footpad BL6 tumor cells show both a marked increase in Deltagamma1 levels and more extensive polyploidy and less apoptosis than F10 cells. These observations were reproduced with Deltagamma1 gene-transfected F10 cells (F10(Deltagamma1)). Deltagamma1 expression and an aberrant checkpoint are also associated with a higher metastatic ability because irradiated F10(Deltagamma1) tumors metastasized much more frequently than F10 tumors, which rarely metastasized whether irradiated or not. Nonirradiated F10(Deltagamma1) tumors, which do not express Deltagamma1 protein, had similarly low rates of metastasis. The greater metastatic ability of irradiated F10(Deltagamma1) tumors also correlated with the acquisition of many more genomic alterations. Thus, it seems that Deltagamma1 expression may damage the checkpoint, which may then allow the acquisition of genetic alterations that promote metastasis. These observations support the notion that mechanisms promoting the genetic instability of tumors could also aid tumor progression from the nonmetastatic to the metastatic state.

3T3 Cells↗

PubMed2003

Expression of H-ficolin/Hakata antigen, mannose-binding lectin-associated serine protease (MASP)-1 and MASP-3 by human glioma cell line T98G.

Mannose-binding lectin (MBL) is a C-type lectin involved in the first line of host defense and it requires MBL-associated serine proteases (MASP) for activation of the lectin complement pathway (LCP). Recently we reported that human ficolins, L-ficolin/P35 and H-ficolin/Hakata antigen, as well as MBL activate the LCP in association with MASP. We investigated in vitro expression of complements of the lectin complement pathway in several cell lines. Out of 17 cell lines tested using RT-PCR, a human glioma cell line, T98G, expressed high levels of H-ficolin/Hakata antigen, MASP1 and MASP3 mRNAs. Similar results were obtained in four other glioma lines. In addition, mRNAs for C1r, C1s, C2, C3, C4, C5 and C6 were also detected in T98G cells, but very low amount of mRNAs for C1q and MBL. MBL mRNA was seen in two of the other glioma cell lines. An ELISA of culture supernatants showed that T98G cells secreted a considerable amount of MASP-1 and MASP-3 proteins. SDS-PAGE and immunoblotting analyses showed the secreted H-ficolin/Hakata antigen, MASP-1 and MASP-3 to be 34, 81 and 105 kDa in size respectively, similar to their serum counterparts. Since the glioma cells used are derived from astrocytes, this suggests that human astrocytes may be a source of some components of the LCP in the brain.

Cell Line↗

PubMed2002

Functional characterization of human mannose-binding lectin-associated serine protease (MASP)-1/3 and MASP-2 promoters, and comparison with the C1s promoter.

The 5'-flanking regions of the genes encoding human mannose-binding lectin-associated serine protease (MASP)-1/3 and MASP-2, key enzymes in the lectin complement pathway, were isolated and characterized. The features of their promoters were compared with those of the human gene for C1s, the effector component of the classical pathway. The sequences upstream from the transcription start sites of the three genes contained the elements essential for transcription and liver-specific expression. Transient expression of constructs of these genes fused to the luciferase reporter gene confirmed their liver-specific expression and showed that the MASP promoters were slightly up-regulated by the presence of IL-1beta. The stimulatory effects of IL-1beta on MASP1/3 and MASP2 gene expression were abolished by the simultaneous presence of IL-6. MASP-1/3 promoter activity was also down-regulated by IFN-gamma. In contrast, C1s promoter activity was strongly up-regulated by IL-6, IL-1beta and IFN-gamma. These results indicate that IL-6 and IFN-gamma affect the expression of the MASP genes in a different fashion from that of the C1s gene, implying differential regulatory effects of these cytokines on the biosynthesis of lectin pathway-specific serine proteases and classical pathway-specific serine proteases.

5' Flanking Region↗

PubMedDate not supplied

Novel mutations of the cartilage oligomeric matrix protein (COMP) gene in two Japanese patients with pseudoachondroplasia.

Mutations in the cartilage oligomeric matrix protein (COMP) gene cause two skeletal dysplasias, pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia (MED), which are autosomal dominant disorders characterized by short-limb dwarfism. We report novel mutations of the COMP gene identified in two sporadic Japanese cases of PSACH. One had a novel single base substitution in exon 9, resulting in a missense mutation of Gly309Arg in the second type 3 repeat of COMP protein. The other patient had no mutations in any of the exonic sequences of the gene, but she did have a novel base substitution in intron 13. Although this mutation was not located in the conserved sequences for splicing donor and acceptor sites, it might disturb the precise splicing of the COMP transcripts, resulting in the production of abnormal protein with defective last type 3 repeat and/or C-terminal domain.

Achondroplasia↗