Search results for "Glycoprotein"
showing 10 items of 852 documents
Effects of cytokines on synthesis and function of the hepatic asialoglycoprotein receptor
1994
In this study we have investigated whether cytokines, critical mediators of the immune response, might have a direct effect on the expression and/or function of the human hepatic asialoglycoprotein receptor (ASGPR). Binding and uptake of asialoglycoproteins by the human hepatoma cell line, HepG2, and by freshly isolated rat hepatocytes were inhibited by 50% after 3-6 hours and completely abolished following a 24 hour exposure to tumor necrosis factor (TNF) alpha, interferon (INF) alpha or gamma, or interleukin-2 (IL-2). The loss of ASGPR binding activity mediated by IL-2 was reversible up to 4 hours of exposure and accompanied by the selective phosphorylation of the cell-surface receptor. S…
Beta-2-glycoprotein I is growth regulated and plays a role as survival factor for hepatocytes
2004
Beta-2-glycoprotein I (beta(2)GPI) is mainly produced by the liver and is found in plasma partially associated to lipoproteins. Although various properties have been attributed to this protein, its physiological role remains still unclear. We investigated its expression in cultured liver cells and in regenerating liver. Expression studies in HepG2 cells demonstrate that beta(2)GPI mRNA is regulated in a cell cycle-dependent manner, with very low expression in low cycling conditions and increasing levels in proliferating cells. p21 WAF-dependent growth arrest, induced by butyrate treatment, down-regulate beta(2)GPI mRNA levels. Immunolocalization in normal rat liver shows a non-homogeneous p…
Comparison of antiplatelet effects of aspirin, ticlopidine, or their combination after stent implantation.
1998
Background —This study was performed to analyze the influence of either aspirin, ticlopidine, or their combination on platelet activation and aggregation parameters after stent implantation. Methods and Results —Sixty-one patients with successful implantation of a single Palmaz-Schatz stent in a native coronary artery were randomly assigned to either group A (aspirin 300 mg/d+ticlopidine 2×250 mg/d), group B (ticlopidine 2×250 mg/d), or group C (aspirin 300 mg/d). Platelet activation was evaluated on days 1, 7, and 14 by flow cytometry measurement of expression of CD62p (p-selectin) and the binding of fibrinogen to the platelet surface glycoprotein IIb/IIIa receptor. Platelet aggregation w…
Acute exercise induced changes in rat skeletal muscle mRNAs and proteins regulating type IV collagen content
2001
This experiment tested the hypothesis that running-induced damage to rat skeletal muscle causes changes in synthesis and degradation of basement membrane type IV collagen and to proteins regulating its degradation. Samples from soleus muscle and red and white parts of quadriceps femoris muscle (MQF) were collected 6 h or 1, 2, 4, or 7 days after downhill running. Increased muscle β-glucuronidase activity indicated greater muscle damage in the red part of MQF than in the white part of MQF or soleus. In the red part of MQF, type IV collagen expression was upregulated at the pretranslational level and the protein concentration decreased, whereas matrix metalloproteinase-2 (MMP-2), a protein th…
Developmental expression of human cartilage matrix protein.
1994
Cartilage matrix protein (CMP) is a non-collagenous component of cartilage with a yet unknown function. In this study we used in situ hybridization to investigate the temporal and sptial distribution of CMP transcripts during human embryonic and early fetal development, and compared it to the pattern of expression observed for collagen types I, II, X, and decorin. The distribution of CMP and collagen type II transcripts followed a similar pattern in the embryonic bone anlage, the fetal growth plate, and the developing vertebral column. Expression was highest in the upper hypertrophic and lower proliferative zone, whereas calcified cartilage was negative throughout the different stages of bo…
Glucose-induced loss of glycosyl-phosphatidylinositol-anchored membrane regulators of complement activation (CD59, CD55) by in vitro cultured human u…
2000
Aims/hypothesis. This study examines whether increased glucose concentrations are responsible for a decreased expression of membrane regulators of complement activation molecules. The effect of high glucose in determining an increase in membrane attack complex deposition on endothelial cells was also investigated. Methods. Endothelial cells were isolated from umbilical cord tissue, cultured in the presence of increased concentrations of glucose, and the expression of CD46, CD55, and CD59 was detected by ELISA (enzyme-linked immunosorbent assay) and by flow cytometry. Glucose-treated endothelial cells were also incubated with antiendothelial cell antibodies and fresh complement to assess the…
Receptor Recognition Sites of Cytokines Are Organized as Exchangeable Modules
1999
Interleukin-6 (IL-6) and ciliary neurotrophic factor (CNTF) are "4-helical bundle" cytokines of the IL-6 type family of neuropoietic and hematopoietic cytokines. IL-6 signals by induction of a gp130 homodimer (e.g. IL-6), whereas CNTF and leukemia inhibitory factor (LIF) signal via a heterodimer of gp130 and LIF receptor (LIFR). Despite binding to the same receptor component (gp130) and a similar protein structure, IL-6 and CNTF share only 6% sequence identity. Using molecular modeling we defined a putative LIFR binding epitope on CNTF that consists of three distinct regions (C-terminal A-helix/N-terminal AB loop, BC loop, C-terminal CD-loop/N-terminal D-helix). A corresponding gp130-bindin…
Oncostatin M, leukaemia-inhibitory factor and interleukin 6 trigger different effects on alpha1-proteinase inhibitor synthesis in human lung-derived …
1998
Interleukin 6 (IL-6), oncostatin M (OSM) and leukaemia-inhibitory factor (LIF) share a common signal-transducing subunit in each of their receptors and thus mediate an overlapping spectrum of biological activities. Although all of these cytokines stimulate the production of α1-proteinase inhibitor (α1-PI) in hepatocyte-derived cells, only OSM is able to up-regulate levels of this inhibitor in epithelial cells originating from the lung. In this study we characterized human lung-derived epithelial-like HTB58 cells for their ability to synthesize α1-PI after treatment with IL-6, OSM and LIF. The results demonstrate that the resistance of HTB58 cells to the effects of IL-6 and LIF was not becau…
Human herpes virus 8 interleukin-6 homologue triggers gp130 on neuronal and hematopoietic cells
2000
Human herpes virus-8 (HHV8) encodes a cytokine named viral interleukin-6 (vIL-6) that shares 25% amino-acid identity with its human homologue. Human IL-6 is known to be a growth and differentiation factor of lymphatic cells and plays a potential role in the pathophysiology of various lymphoproliferative diseases. vIL-6 is expressed in HHV8-associated-diseases including Kaposi's sarcoma, Body-cavity-based-lymphoma and Castleman's disease, suggesting a pathogenetic involvement in the malignant growth of B-cell associated diseases and other malignant tumours. We expressed vIL-6 in Escherichia coli as a fusion protein with recombinant periplasmic maltose binding protein. After cleavage from the…
Recombinant Human Single Chain Fv Antibodies Recognizing Human Interleukin-6
1998
A human antibody library was displayed on the surface of filamentous bacteriophage and screened for binding to human interleukin-6 (IL-6). Two antibody-bearing phages were selected that bound IL-6. The complementary-determining region 3 loops of the variable heavy chains of these two antibodies differed in length and sequence and recognized two distinct epitopes. One of the single chain Fv fragments isolated (H1) was found to bind human (but not murine) IL-6 with an affinity comparable to that of the human IL-6 receptor. H1 also recognized newly synthesized human IL-6 intracellularly, as shown by indirect immunofluorescence. H1 did not neutralize human IL-6, and the H1 epitope was mapped to…