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Membrane Glycoprotein (membrane + glycoprotein)
Kinds of Membrane Glycoprotein Selected AbstractsAltered membrane glycoprotein targeting in cholestatic hepatocytesEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 5 2010Giuseppa Esterina Liquori Eur J Clin Invest 2010; 40 (5): 393,400 Abstract Background, Hepatocytes are polarized epithelial cells with three morphologically and functionally distinct membrane surfaces: the sinusoidal, lateral and canalicular surface domains. These domains differ from each other in the expression of integral proteins, which concur to their polarized functions. We hypothesize that the cholestasis-induced alterations led to partial loss of hepatocyte polarity. An altered expression of membrane proteins may be indicative of functional disorders. Alkaline liver phosphatase (ALP), one of the most representative plasma membrane glycoproteins in hepatocytes, is expressed at the apical (canalicular) pole of the cell. Because the release of ALP protein in the bloodstream is significantly increased in cholestasis, the enzymatic levels of plasma ALP have major relevance in the diagnosis of cholestatic diseases. Here we assess the cholestasis-induced redistribution of membrane glycoproteins to investigate the ALP release. Materials and methods, We performed enzymatic histochemistry, immunohistochemistry, lectin histochemistry, immunogold and lectin-and immunoblotting studies. Experimental cholestasis was induced in rats by ligation of common bile duct (BDL). Results, The BDL led to altered membrane sialoglycoprotein targeting as well as to ultrastructural and functional disorders. Disarrangement of the microtubular system, thickening of the microfilamentous pericanalicular ectoplasm and disturbance of the vectorial trafficking of membrane glycoprotein containing vesicles were found. Conclusions, Altogether, results indicate that the cholestasis-induced partial loss of hepatocyte cell polarity leads to mistranslocation of ALP to the sinusoidal plasma membrane from where the enzyme is then massively released into the bloodstream. [source] Filopodial protrusions induced by glycoprotein M6a exhibit high motility and aids synapse formationEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 2 2010Marcela A. Brocco Abstract M6a is a neuronal membrane glycoprotein whose expression diminishes during chronic stress. M6a overexpression in rat primary hippocampal neurons induces the formation of filopodial protrusions that could be spine precursors. As the filopodium and spine motility has been associated with synaptogenesis, we analysed the motility of M6a-induced protrusions by time-lapse imaging. Our data demonstrate that the motile protrusions formed by the neurons overexpressing M6a were more abundant and moved faster than those formed in control cells. When different putative M6a phosphorylation sites were mutated, the neurons transfected with a mutant lacking intracellular phosphorylation sites bore filopodia, but these protrusions did not move as fast as those formed by cells overexpressing wild-type M6a. This suggests a role for M6a phosphorylation state in filopodium motility. Furthermore, we show that M6a-induced protrusions could be stabilized upon contact with presynaptic region. The motility of filopodia contacting or not neurites overexpressing synaptophysin was analysed. We show that the protrusions that apparently contacted synaptophysin-labeled cells exhibited less motility. The behavior of filopodia from M6a-overexpressing cells and control cells was alike. Thus, M6a-induced protrusions may be spine precursors that move to reach presynaptic membrane. We suggest that M6a is a key molecule for spine formation during development. [source] Structural requirements for the apical sorting of human multidrug resistance protein 2 (ABCC2)FEBS JOURNAL, Issue 7 2002Anne T. Nies The human multidrug resistance protein 2 (MRP2, symbol ABCC2) is a polytopic membrane glycoprotein of 1545 amino acids which exports anionic conjugates across the apical membrane of polarized cells. A chimeric protein composed of C-proximal MRP2 and N-proximal MRP1 localized to the apical membrane of polarized Madin,Darby canine kidney cells (MDCKII) indicating involvement of the carboxy-proximal part of human MRP2 in apical sorting. When compared to other MRP family members, MRP2 has a seven-amino-acid extension at its C-terminus with the last three amino acids (TKF) comprising a PDZ-interacting motif. In order to analyze whether this extension is required for apical sorting of MRP2, we generated MRP2 constructs mutated and stepwise truncated at their C-termini. These constructs were fused via their N-termini to green fluorescent protein (GFP) and were transiently transfected into polarized, liver-derived human HepG2 cells. Quantitative analysis showed that full-length GFP,MRP2 was localized to the apical membrane in 73% of transfected, polarized cells, whereas it remained on intracellular membranes in 27% of cells. Removal of the C-terminal TKF peptide and stepwise deletion of up to 11 amino acids did not change this predominant apical distribution. However, apical localization was largely impaired when GFP,MRP2 was C-terminally truncated by 15 or more amino acids. Thus, neither the PDZ-interacting TKF motif nor the full seven-amino-acid extension were necessary for apical sorting of MRP2. Instead, our data indicate that a deletion of at least 15 C-terminal amino acids impairs the localization of MRP2 to the apical membrane of polarized cells. [source] Bernard Soulier syndrome in pregnancy: a systematic reviewHAEMOPHILIA, Issue 4 2010P. PEITSIDIS Summary., Bernard Soulier syndrome (BSS) is a rare disorder of platelets, inherited mainly as an autosomal recessive trait. It is characterised by qualitative and quantitative defects of the platelet membrane glycoprotein (GP) Ib-IX-V complex. The main clinical characteristics are thrombocytopenia, prolonged bleeding time and the presence of giant platelets. Data on the clinical course and outcome of pregnancy in women with Bernard Soulier syndrome is scattered in individual case reports. In this paper, we performed a systematic review of literature and identified 16 relevant articles; all case reports that included 30 pregnancies among 18 women. Primary postpartum haemorrhage was reported in 10 (33%) and secondary in 12 (40%) of pregnancies, requiring blood transfusion in 15 pregnancies. Two women had an emergency obstetric hysterectomy. Alloimmune thrombocytopenia was reported in 6 neonates, with one intrauterine death and one neonatal death. Bernard Soulier syndrome in pregnancy is associated with a high risk of serious bleeding for the mother and the neonate. A multidisciplinary team approach and individualised management plan for such women are required to minimise these risks. An international registry is recommended to obtain further knowledge in managing women with this rare disorder. [source] The Flavobacterium psychrophilum OmpA, an outer membrane glycoprotein, induces a humoral response in rainbow troutJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2007F. Dumetz Abstract Aims:, The purpose of this study was to characterize OmpA, a major glycoprotein isolated from the membrane fraction of Flavobacterium psychrophilum, and to evaluate its potential as antigenic unit in a possible vaccine. Methods and Results:, The expression product of ompA is a 465-amino-acid protein precursor that contains a 21-amino acid signal peptide and has overall homology (up to 60% identity) with similarly sized proteins of some bacteria belonging to the Flavobacteriaceae family. The carboxy-terminal region contains the ,OmpA/MotB' domain/signature and five putative ,Thrombospondin type 3 repeats' domains have been identified in the central region. OmpA was clearly detected in the outer membrane fraction and its surface exposure was demonstrated. OmpA is one of the immunodominant antigens and binding of specific anti-OmpA antibodies lead to cell lysis in the presence of complement. Fish immunized with OmpA emulsified with Freund's adjuvant developed a high antibody titter. Conclusions:, Collectively, the data obtained here indicate that OmpA may be involved in Fl. psychrophilum/host cell interactions and appears to be a potential immunogen for a vaccine. Significance and Impact of the Study:, This study is one step in the direction of understanding pathogenesis of Fl. psychrophilum and development of future vaccine. [source] Endoglin: An accessory component of the TGF-,-binding receptor-complex with diagnostic, prognostic, and bioimmunotherapeutic potential in human malignanciesJOURNAL OF CELLULAR PHYSIOLOGY, Issue 1 2001Ester Fonsatti Endoglin (CD105) is a cell membrane glycoprotein over-expressed on highly proliferating endothelial cells in culture, and on endothelial cells of angiogenetic blood vessels within benign and malignant tissues. CD105 binds several factors of the Transforming Growth Factor (TGF)-, superfamily, and its over-expression modulates cellular responses to TGF-,1. The complex of experimental findings accumulated in the last few years strongly indicate that CD105 is a powerful marker of angiogenesis, and that it might play a critical role in the pathogenesis of vascular diseases and in tumor progression. In this paper, we will review the structural, biological and functional features of CD105, as well as its distribution within normal and neoplastic tissues, emphasizing its foreseeable role as a molecular target for new diagnostic and bioimmunotherapeutic approaches in human malignancies. © 2001 Wiley-Liss, Inc. [source] Variable number of tandem repeats polymorphism of platelet glycoprotein Ib , in Chinese people and CC genotype with aspirin sensitivity in patients with cerebral infarctionJOURNAL OF CLINICAL PHARMACY & THERAPEUTICS, Issue 2 2009Y.-Y. Jin MM Summary Background and objective:, To study the prevalence of variable number of tandem repeats (VNTR) polymorphism in platelet membrane glycoprotein (GP) Ib , in a Chinese Han population and to determine the relationship between VNTR polymorphisms and aspirin resistance. Methods:, Three hundred healthy individuals and 110 patients with cerebral infarction volunteered to participate in this study. The genotype status of all participants was determined by polymerase chain reaction-restriction fragment length polymorphism analysis. Platelet aggregation in patients with cerebral infarction receiving aspirin (100 mg/day) for at least 7 days, was measured by optical transmission aggregometry. Results and discussion:, Only three alleles of GP Ib ,, namely, B, C and D, were found. Type A was not found in the Chinese Han participants. Aspirin-sensitive patients were significantly more often of CC genotype than aspirin-semi-responders. Conclusions:, Only three types of alleles B, C and D were detected in the north-eastern region of China. The CC genotype of the VTNR polymorphism in GPIb appears to be more sensitive to the inhibitory action of low-dose aspirin. [source] Conjugation of isometamidium chloride to antibodies and the use of the conjugate against the haemoflagellate, Cryptobia salmositica Katz, 1951: an immuno-chemotherapeutic strategyJOURNAL OF FISH DISEASES, Issue 8 2001B F Ardelli The trypanocidal drug isometamidium chloride (Samorin) was conjugated to polyclonal and monoclonal antibodies produced against the pathogenic haemoflagellate Cryptobia salmositica. Under in vitro conditions the unconjugated drug normally accumulates rapidly in the kinetoplast in the parasite; however, once it was conjugated to antibodies (either polyclonal or monoclonal) it was found throughout the parasite. Isometamidium conjugated to polyclonal antibodies lysed C. salmositica under in vitro conditions, but parasites were not agglutinated. In contrast, isometamidium conjugated to monoclonal antibodies (against a 200 kDa surface membrane glycoprotein) did not lyse C. salmositica, but parasites were agglutinated. Because of the low efficacy of the monoclonal conjugate against the parasite in vitro, its cryptobiocidal effect was not evaluated further. The infectivity of C. salmositica (incubated either in culture medium or whole blood) was reduced in fish after in vitro exposure to isometamidium conjugated to polyclonal antibodies. Parasitaemias were reduced in infected chinook salmon, Oncorhynchus tshawytscha, after treatment with isometamidium conjugated to polyclonal antibodies. [source] Genotypic analysis of two hypervariable human cytomegalovirus genesJOURNAL OF MEDICAL VIROLOGY, Issue 9 2008Amanda J. Bradley Abstract Most human cytomegalovirus (HCMV) genes are highly conserved in sequence among strains, but some exhibit a substantial degree of variation. Two of these genes are UL146, which encodes a CXC chemokine, and UL139, which is predicted to encode a membrane glycoprotein. The sequences of these genes were determined from a collection of 184 HCMV samples obtained from Africa, Australia, Asia, Europe, and North America. UL146 is hypervariable throughout, whereas variation in UL139 is concentrated in a sequence encoding a potentially highly glycosylated region. The UL146 sequences fell into 14 genotypes, as did all previously reported sequences. The UL139 sequences grouped into 8 genotypes, and all previously reported sequences fell into a subset of these. There were minor differences among continents in genotypic frequencies for UL146 and UL139, but no clear geographical separation, and identical nucleotide sequences were represented among communities distant from each other. The frequent detection of multiple genotypes indicated that mixed infections are common. For both genes, the degree of divergence was sufficient to preclude reliable sequence alignments between genotypes in the most variable regions, and the mode of evolution involved in generating the genotypes could not be discerned. Within genotypes, constraint appears to have been the predominant mode, and positive selection was detected marginally at best. No evidence was found for linkage disequilibrium. The emerging scenario is that the HCMV genotypes developed in early human populations (or even earlier), becoming established via founder or bottleneck effects, and have spread, recombined and mixed worldwide in more recent times. J. Med. Virol. 80:1615,1623, 2008. © 2008 Wiley-Liss, Inc. [source] The lectin-like domain of thrombomodulin interferes with complement activation and protects against arthritisJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 8 2006M. VAN DE WOUWER Summary.,Background: Thrombomodulin (TM) is predominantly a vascular endothelial cell plasma membrane glycoprotein that, via distinct structural domains, interacts with multiple ligands, thereby modulating coagulation, fibrinolysis, complement activation, inflammation and cell proliferation. We previously reported that by mediating signals that interfere with mitogen-activated protein kinase and nuclear factor ,B pathways, the amino-terminal C-type lectin-like domain of TM has direct anti-inflammatory properties. Methods: In the current study, we use murine models of acute inflammatory arthritis and biochemical approaches to assess the mechanism by which the lectin-like domain of TM modifies disease progression. Results: Mice lacking the lectin-like domain of TM (TMLeD/LeDmice) develop inflammatory arthritis that is more rapid in onset and more severe than that developed in their wildtype counterparts. In two models of arthritis, treatment of mice with recombinant soluble lectin-like domain of TM significantly suppresses clinical evidence of disease and diminishes monocyte/macrophage infiltration into the synovium, with weaker expression of the pro-inflammatory high mobility group box chromosomal protein 1. While thrombin-TM mediated activation of thrombin activatable fibrinolysis inhibitor inactivates complement factors C3a and C5a, we show that TM has a second independent mechanism to regulate complement: the lectin-like domain of TM directly interferes with complement activation via the classical and lectin pathways. Conclusions: These data extend previous insights into the mechanisms by which TM modulates innate immunity, and highlight its potential as a therapeutic target for inflammatory diseases. [source] Tissue factor: a mini-reviewJOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, Issue 3 2007Valéry Daubie Abstract Tissue factor (TF) is historically known as the trigger of the coagulation cascade. This integral membrane glycoprotein forms a ternary complex with factor VIIa (FVIIa) and zymogen factor (FX), which is then activated to factor Xa (FXa). The latter cleaves prothrombin into thrombin (FIIa), which in turn activates fibrinogen in fibrin monomers. What is less known is its additional non-haemostatic roles in inflammation, tumour growth and angiogenesis. This aspect will be developed here. TF, as a transmembrane protein, has a signalling effect requiring FVIIa. TF,FVIIa complex activates G protein-coupled receptor protease-activated receptor 2 (PAR-2) and therefore modulates various cellular processes, such as cell proliferation and survival, gene transcription and protein translation. In this review we will first highlight, using recent structural data, the ,potentially' active domain able to modulate the triggered intracellular response. We also will focus on the still emerging and promising results deciphering the diverse locations in which TF appears. We conclude with a description of an emerging and atypical use of tissue factor in platelet gel surgery for sinus augmentation. Copyright © 2007 John Wiley & Sons, Ltd. [source] Recent advances in the discovery of flavonoids and analogs with high-affinity binding to P-glycoprotein responsible for cancer cell multidrug resistanceMEDICINAL RESEARCH REVIEWS, Issue 5 2002Ahcène Boumendjel Abstract P-glycoprotein (P-gp) is a plasma membrane glycoprotein that confers multidrug resistance on cells by virtue of its ability to exclude cytotoxic drugs in an ATP-dependent manner. The most commonly considered hypothesis is that P-gp acts as an ATP-driven drug-export pump, the mechanism of which is not understood in detail. Therefore, a tremendous effort is being made to find out modulator molecules to inhibit P-gp. We have been developing flavonoid derivatives as a new class of promising modulators using a new in vitro rational-screening assay based on measurements of the binding-affinity toward the C-terminal nucleotide-binding domain (NBD2) of P-gp. This review is focused on our results obtained with a variety of flavonoids. Structure,activity relationships of flavonoids as potential MDR modulators are reported. © 2002 Wiley Periodicals, Inc. Med Res Rev, 22, No. 5, 512,529, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/med.10015 [source] Generation of cell hybrids via a fusogenic cell lineTHE JOURNAL OF GENE MEDICINE, Issue 7 2006Siew Chiat Cheong Abstract Background Hybrids obtained by fusion between tumour cells (TC) and dendritic cells (DC) have been proposed as anti-tumour vaccines because of their potential to combine the expression of tumour-associated antigens with efficient antigen presentation. The classical methods used for fusion, polyethylene glycol (PEG) and electrofusion, are cytotoxic and generate cell debris that can be taken up by DC rendering the identification of true hybrids difficult. Methods We have established a stable cell line expressing a viral fusogenic membrane glycoprotein (FMG) that is not itself susceptible to fusion. This cell line has been used to generate hybrids and to evaluate the relevance of tools used for hybrid detection. Results This FMG-expressing cell line promotes fusion between autologous or allogeneic TC and DC in any combination, generating ,tri-parental hybrids'. At least 20% of TC are found to be integrated into hybrids. Conclusions It is speculated that this tri-parental hybrid approach offers new possibilities to further modulate the anti-tumour effect of the DC/TC hybrids since it allows the expression of relevant immunostimulatory molecules by appropriate engineering of the fusogenic cell line. Copyright © 2006 John Wiley & Sons, Ltd. [source] Expression, crystallization and preliminary crystallographic study of mouse hepatitis virus (MHV) nucleocapsid protein C-terminal domainACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 6 2010Xiaohang Tong Mouse hepatitis virus (MHV) belongs to the group II coronaviruses. The virus produces nine genes encoding 11 proteins that could be recognized as structural proteins and nonstructural proteins and are crucial for viral RNA synthesis. The nucleocapsid (N) protein, one of the structural proteins, interacts with the 30.4,kb virus genomic RNA to form the helical nucleocapsid and associates with the membrane glycoprotein via its C-terminus to stabilize virion assembly. Here, the expression and crystallization of the MHV nucleocapsid protein C-terminal domain are reported. The crystals diffracted to 2.20,Å resolution and belonged to space group P422, with unit-cell parameters a = 66.6, c = 50.8,Å. Assuming the presence of two molecules in the asymmetric unit, the solvent content is 43.0% (VM = 2.16,Å3,Da,1). [source] Clinicopathologic significance of dysadherin expression in cutaneous malignant melanomaCANCER, Issue 8 2005Immunohistochemical analysis of 115 patients Abstract BACKGROUND The E-cadherin,mediated cell adhesion system is frequently inactivated by multiple mechanisms and is involved in tumor progression in many types of cancer. Recently, the authors reported a novel cell membrane glycoprotein, dysadherin, which has an anti,cell-cell adhesion function and down-regulates E-cadherin. METHODS Expression of both dysadherin and E-cadherin was investigated immunohistochemically in 115 patients with cutaneous malignant melanoma to determine the correlation between the 2 molecules and their associations with both patient survival and the clinicopathologic features of the tumors. RESULTS Dysadherin and E-cadherin were expressed at the cell membranes of melanoma cells. Fifty-two percent of the tumors showed dysadherin immunopositivity, and 91% of the tumors showed reduced E-cadherin immunopositivity. There was no significant inverse correlation between dysadherin expression and E-cadherin expression. Increased dysadherin expression was significantly correlated with nodular subtype (P = 0.042), Clark level (P < 0.001), tumor thickness (P < 0.001), ulceration (P = 0.008), lymph node metastasis (P < 0.001), high TNM classification (P < 0.001), and poor patient survival (P < 0.001). Multivariate analysis of patient survival revealed that increased dysadherin expression was a significant predictor of poor survival (P < 0.001). CONCLUSIONS Thus, increased expression of dysadherin was a significant indicator of poor prognosis in patients with cutaneous malignant melanoma. Cancer 2005. © 2005 American Cancer Society. [source] Cell adhesion system and human cancer morphogenesisCANCER SCIENCE, Issue 7 2003Setsuo Hirohashi Cell-cell adhesion determines the polarity of cells and participates in the maintenance of the cell societies called tissues. Cell-cell adhesiveness is generally reduced in human cancers. Reduced intercellular adhesiveness allows cancer cells to disobey the social order, resulting in destruction of histological structure, which is the morphological hallmark of malignant tumors. Reduced intercellular adhesiveness is also indispensable for cancer invasion and metastasis. A tumor-suppressor gene product, E-cadherin, and its undercoat proteins, catenins, which connect cadherins to actin filaments, are located at lateral borders, concentrating on adherens junctions, of epithelial cells and establish firm cell-cell adhesion. The E-cadherin cell adhesion system in cancer cells is inactivated by various mechanisms that reflect the morphological and biological characteristics of the tumor. Silencing of the E-cadherin gene by DNA hypermethylation around the promoter region occurs frequently, even in precancerous conditions. In diffuse infiltrating cancers, mutations are found in the genes for E-cadherin and ,-and ,-catenins. At the invading front of cancers, the E-cadherin cell adhesion system is inactivated by tyrosine phosphorylation of ,-catenin; an oncogene product, c- erb B-2 protein, is found to associate directly with ,-catenin. The E-cadherin cell adhesion system cross-talks with the Wingless/Wnt signaling pathway through ,-catenin, and expression of genes, which participate in cancer morphogenesis, may be regulated in conjunction with the Wingless/Wnt signaling pathway. Dysadherin, a newly identified cancer-associated cell membrane glycoprotein, down-regulates E-cadherin and promotes cancer metastasis. In conclusion, inactivation of the E-cadherin cell adhesion system by both genetic and epigenetic mechanisms plays a significant role during multistage human carcinogenesis. [source] Vinculin is proteolyzed by calpain during platelet aggregation: 95 kDa cleavage fragment associates with the platelet cytoskeletonCYTOSKELETON, Issue 4 2004Katherine Serrano Abstract The focal adhesion protein vinculin contributes to cell attachment and spreading through strengthening of mechanical interactions between cell cytoskeletal proteins and surface membrane glycoproteins. To investigate whether vinculin proteolysis plays a role in the influence vinculin exerts on the cytoskeleton, we studied the fate of vinculin in activated and aggregating platelets by Western blot analysis of the platelet lysate and the cytoskeletal fractions of differentially activated platelets. Vinculin was proteolyzed into at least three fragments (the major one being ,95 kDa) within 5 min of platelet activation with thrombin or calcium ionophore. The 95 kDa vinculin fragment shifted cellular compartments from the membrane skeletal fraction to the cortical cytoskeletal fraction of lysed platelets in a platelet aggregation-dependent manner. Vinculin cleavage was inhibited by calpeptin and E64d, indicating that the enzyme responsible for vinculin proteolysis is calpain. These calpain inhibitors also inhibited the translocation of full-length vinculin to the cytoskeleton. We conclude that cleavage of vinculin and association of vinculin cleavage fragment(s) with the platelet cytoskeleton is an activation response that may be important in the cytoskeletal remodeling of aggregating platelets. Cell Motil. Cytoskeleton 58:242,252, 2004. © 2004 Wiley-Liss, Inc. [source] Altered membrane glycoprotein targeting in cholestatic hepatocytesEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 5 2010Giuseppa Esterina Liquori Eur J Clin Invest 2010; 40 (5): 393,400 Abstract Background, Hepatocytes are polarized epithelial cells with three morphologically and functionally distinct membrane surfaces: the sinusoidal, lateral and canalicular surface domains. These domains differ from each other in the expression of integral proteins, which concur to their polarized functions. We hypothesize that the cholestasis-induced alterations led to partial loss of hepatocyte polarity. An altered expression of membrane proteins may be indicative of functional disorders. Alkaline liver phosphatase (ALP), one of the most representative plasma membrane glycoproteins in hepatocytes, is expressed at the apical (canalicular) pole of the cell. Because the release of ALP protein in the bloodstream is significantly increased in cholestasis, the enzymatic levels of plasma ALP have major relevance in the diagnosis of cholestatic diseases. Here we assess the cholestasis-induced redistribution of membrane glycoproteins to investigate the ALP release. Materials and methods, We performed enzymatic histochemistry, immunohistochemistry, lectin histochemistry, immunogold and lectin-and immunoblotting studies. Experimental cholestasis was induced in rats by ligation of common bile duct (BDL). Results, The BDL led to altered membrane sialoglycoprotein targeting as well as to ultrastructural and functional disorders. Disarrangement of the microtubular system, thickening of the microfilamentous pericanalicular ectoplasm and disturbance of the vectorial trafficking of membrane glycoprotein containing vesicles were found. Conclusions, Altogether, results indicate that the cholestasis-induced partial loss of hepatocyte cell polarity leads to mistranslocation of ALP to the sinusoidal plasma membrane from where the enzyme is then massively released into the bloodstream. [source] Roles of oxidized low-density lipoprotein and its receptors in the pathogenesis of atherosclerotic diseasesGERIATRICS & GERONTOLOGY INTERNATIONAL, Issue 4 2002Noriaki Kume In elderly populations, atherosclerotic diseases, including ischemic heart disease and stroke, frequently impair quality of life and affect mortality. Hypercholesterolemia, especially increased plasma low-density lipoprotein (LDL), is one of the strongest risk factors for atheroscletorotic diseases. Oxidative modification of LDL appears to convert LDL particles to more atherogenic forms. Scavenger receptor class A (SR-A) and CD36 have been identified and well-characerized as receptors for Ox-LDL in macrophages. In addition to these molecules, lectin-like oxidized LDL receptor (LOX)-1 and scavenger receptor for phosphatidylserine and oxidized lipoprotein (SR-PSOX) are type II and I membrane glycoproteins, respectively, both of which can act as cell-surface endocytosis receptors for atherogenic oxidized LDL (Ox-LDL). LOX-1 expression can dynamically be induced by pro-inflammatory stimuli, and is detectable in cultured macrophages and activated vascular smooth muscle cells (VSMC), in addition to endothelial cells. LOX-1-dependent uptake of Ox-LDL induces apoptosis of cultured VSMC. In vivo, endothelial cells that cover early atherosclerotic lesions, and intimal macrophages and VSMC in advanced atherosclerotic plaques dominantly express LOX-1. LOX-1 expressed on the cell-surface can be cleaved in part and released as soluble molecules, suggesting the diagnostic value of soluble LOX-1. SR-PSOX is a newly identified receptor for Ox-LDL, which appears to be identical to CXCL16, a novel membrane-anchored chemokine directed to CXCR6-positive lymphocytes. In contrast to LOX-1, which is expressed by a variety of cell types, SR-PSOX expression appeared relatively confined to macrophages in atherogenesis. Taken together, oxidized LDL receptors, including LOX-1 and SR-PSOX, may play important roles in atherogenesis and atherosclerotic plaque rupture. [source] Variation and infectivity neutralization in influenzaIMMUNOLOGY, Issue 1 2006Marcel Knossow Summary Worldwide epidemics of influenza are caused by viruses that normally infect other species, particularly waterfowl, and that contain haemagglutinin membrane glycoproteins (HAs) to which the human population has no immunity. Anti-HA immunoglobulins neutralize influenza virus infectivity. In this review we outline structural differences that distinguish the HAs of the 16 antigenic subtypes (H1,16) found in viruses from avian species. We also describe structural changes in HA required for the effective transfer to humans of viruses containing three of them, H1, H2 and H3, in the 1918 (Spanish), the 1957 (Asian) and the 1968 (Hong Kong) pandemics, respectively. In addition, we consider changes that may be required before the current avian H5 viruses could pass from human to human. [source] A carbohydrate neoepitope that is up-regulated on human mononuclear leucocytes by neuraminidase treatment or by cellular activationIMMUNOLOGY, Issue 2 2001Mark T. Quinn Summary The expression of cell-surface antigens can delineate specific leucocyte developmental or functional stages. For example, certain membrane glycoproteins are expressed selectively on leucocyte subsets only after activation. Leucocyte activation can also induce changes in carbohydrate epitopes expressed on surface antigens. In the present studies, we report on a novel monoclonal immunoglobulin M antibody (mAb 13.22) that recognizes a unique carbohydrate epitope expressed on human leucocyte membrane proteins. Characterization of mAb 13.22 specificity by immunoblotting showed that it recognized proteins of MW ,95 000 and 150 000, including both CD18 and CD11b. The mAb 13.22 epitope was removed by N -glycosidase F but not by endoglycosidase H or fucosidase, demonstrating that it is an N-linked carbohydrate antigen. Interestingly, immunoblot staining was enhanced after neuraminidase treatment, suggesting that the antibody epitope might also be partially masked by sialic acid. In resting leucocytes, the mAb 13.22 antigen was expressed strongly on neutrophils, while dull staining was present on monocytes, and no lymphocyte staining was observed. In marked contrast, treatment of leucocytes with neuraminidase resulted in exposure of a mAb 13.22 neoepitope on a subset of lymphocytes (primarily T lymphocytes and natural killer cells) as well as up-regulated staining more than 18-fold on monocytes. Activation of lymphocytes in culture with phytohaemagglutinin or concanavalin A also unmasked the mAb 13.22 neoepitope on ,37% of the CD45RO+ lymphocytes. Furthermore, analysis of leucocytes collected from the synovial fluid of patients with rheumatoid arthritis showed that ,18% of the lymphocytes present expressed the mAb 13.22 neoepitope. Taken together, our results suggest that the mAb 13.22 carbohydrate neoepitope could represent a physiologically relevant marker that is up-regulated on leucocyte subsets during the inflammatory response. [source] Glycoproteomics and glycomics investigation of membrane N -glycosylproteins from human colon carcinoma cellsPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 16 2008Anne-Sophie Vercoutter-Edouart Dr. Abstract Aberrant glycosylation of proteins is known to profoundly affect cellular adhesion or motility of tumoral cells. In this study, we used HT-29 human colon epithelial cancer cells as a cellular model of cancer progression, as they can either proliferate or differentiate into enterocyte phenotype. A glycoproteomic approach based on Con A lectin-affinity chromatography, SDS-PAGE and MS analysis, allowed the identification of membrane N -glycoproteins from Triton X-100-solubilized proteins from membrane preparation. Among them, 65% were membrane proteins, and 45% were known to be N -glycosylated, such as , chains integrin and dipeptidyl isomerase IV. By lectin-blot analysis, significant changes of ,-2,3- and ,-2,6-sialylation of membrane glycoproteins were observed between proliferating and differentiated HT-29 cells. From these results, nano-LC-MS/MS analysis of the tryptic digests of the corresponding bands was performed and led to the identification of several transmembrane glycoproteins, like members of the solute carrier family and adhesion proteins. Finally, we compared N -glycans profiles and monosaccharide composition of proliferating and enterocyte-like HT-29 cells using MALDI-MS and GC-MS analyses of permethylated derivatives. This glycomic approach allowed to underscore significant changes in N -glycans structure, in particular the expression of atypical N -acetylglucosamine (GlcNAc)-ended N -glycans in enterocyte-like HT-29 cells. [source] Structural analysis of ,-Gal and new non-Gal carbohydrate epitopes from specific pathogen-free miniature pig kidneyPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 13 2008Yun-Gon Kim Abstract The major barrier in transplantation of pig organs into humans is the presence of surface carbohydrate antigens (e.g., the Gal,1-3Gal,1-4GlcNAc-R (,-Gal) epitope) expressed on pig endothelial cells. In this study, total N -glycans from membrane glycoproteins derived from specific pathogen-free miniature pig kidney are identified by MALDI-TOF, negative ion ESI MS/MS and normal-phase HPLC (NP-HPLC) combined with exoglycosidase digestion. Over 100 N -glycans, including sialylated and neutral types, were identified. As well as the known ,-Gal antigens, some of these glycans contained novel non-Gal carbohydrate antigens such as (Neu5Gc-Gal-GlcNAc) and Gal,1-3Lewisx (Gal-Gal-(Fuc)GlcNAc) which have not been reported before in N -glycans from pig organs. The ability of MALDI, ESI, and HPLC to measure the relative proportions of the glycans was evaluated. The HPLC resolution was insufficient for accurate work and some minor differences were noted in the ionization efficiencies of different glycan groups when measured by the two mass spectrometric techniques. However, the results indicated that the relative quantity of ,-Gal epitope was in the region of 50% of the complex glycans. High-mannose type glycans were also abundant (35,43%) but appeared to be ionized more efficiently than the complex glycans by ESI than by MALDI. [source] Immediate Posttransplantation Cotrimoxazole-Induced Immune ThrombocytopeniaAMERICAN JOURNAL OF TRANSPLANTATION, Issue 4 2010R. Caluwé Drug-induced immune thrombocytopenia (DITP) can be caused by numerous drugs. When this condition develops, platelet destruction results from binding of antibodies to normal platelets only in the presence of a sensitizing drug. A recently proposed model suggests that these drug-dependent antibodies are derived from a pool of naturally occurring antibodies with weak affinity for specific epitopes on certain platelet membrane glycoproteins. We describe here a case of DITP secondary to cotrimoxazole exposure in the immediate posttransplantation phase in a renal transplant recipient. Apart from heparin-induced thrombocytopenia, DITP posttransplantation has to the best of our knowledge never been described, perhaps because of its immune-mediated origin. Our case demonstrates that DITP can occur posttransplantation, that cotrimoxazole due to its intensive use in the transplanted population is one of the most likely causative agents and that a timely recognition and treatment might have important consequences for both graft and patient. [source] Single nucleotide polymorphisms of the inflammatory cytokine genes in adults with chronic immune thrombocytopenic purpuraBRITISH JOURNAL OF HAEMATOLOGY, Issue 6 2004Takashi Satoh Summary Single nucleotide polymorphisms (SNPs) of inflammatory cytokine genes were examined in 84 adult Japanese patients with chronic immune thrombocytopenic purpura (ITP) and 56 race-matched healthy controls. The SNPs examined were within the genes encoding tumour necrosis factor (TNF)- , (,238 G/A and ,308 G/A), TNF- , (+252 G/A), and interleukin (IL)-1, (,511 C/T and +3953 T/C). Of these SNPs, the frequency of the TNF- , (+252) G/G phenotype was significantly higher in ITP patients than in healthy controls (21% vs. 7%, P = 0·04, odds ratio = 3·6, 95% confidence interval 1·1,11·1), while no significant association was detected for the other SNPs. The distribution of the TNF- , (+252) phenotype was not associated with human leucocyte antigen class II alleles or the therapeutic response in ITP patients. The frequency of circulating anti-glycoprotein IIb/IIIa antibody-producing B cells was significantly higher in ITP patients with the TNF- , (+252) G/G phenotype than in those with the G/A or A/A phenotype (11·9 ± 4·9 vs. 6·8 ± 4·9 and 3·7 ± 2·8 per 105 peripheral blood mononuclear cells; P = 0·02 and P < 0·001, respectively). These findings suggest that the SNP located at TNF- , (+252) contributes to susceptibility to chronic ITP by controlling the autoreactive B-cell responses to platelet membrane glycoproteins. [source] The Identification of an Adenovirus Receptor by Using Affinity Capture and Mass SpectrometryCHEMBIOCHEM, Issue 8 2004Sunia A. Trauger Dr. Abstract A tandem mass spectrometry-based approach is demonstrated for detecting a receptor for Ad37, one of the causative agents for epidemic keratoconjunctivitis. Partial purification of membrane glycoproteins was performed by using lectin-affinity chromatography and SDS-PAGE. Gel bands that were shown to bind Ad37 by using Viral Overlay Protein Blot Assay (VOPBA) were excised, proteolyzed and analyzed by using nanoLC-MS/MS to identify putative receptors contained in a mixture of proteins. Four candidate receptors were identified among approximately 50 proteins based on a search against a protein database. Inhibition of gene delivery mediated by an Ad37 vector, with antibodies against the glycoproteins identified by tandem mass spectrometry, strongly indicated that Membrane Cofactor Protein (MCP), a member of the complement regulatory family of proteins, is the receptor. This rapid and sensitive MS/MS-based strategy is perceived to have wide potential applications for the detection of viral receptors. [source] | |||||||||||||||||||||||||