Search results for "glycoproteins"
showing 10 items of 496 documents
Screening for inhibitors of HIV gp120-CD4 binding using an enzyme-linked immunoabsorbent assay.
1993
Binding of the HIV-1 major viral surface glycoprotein, gp120, to the major cell receptor, CD4, is essential for HIV infection of the target cell and syncytium formation. An enzyme-linked immunoassay using solid phase CD4 was used to quantitate the binding of HIV-1 gp120 to CD4, and to assess the activity and mechanism of action of putative inhibitors of that reaction. Monoclonal antibodies to the gp120 binding site on CD4 (e.g., Leu3a) blocked gp120 binding, while monoclonal antibodies to other portions of CD4 (e.g. OKT4) did not. Both aurintricarboxylic acid and sulfonated polysaccharides (e.g., dextran sulfate) blocked CD4-gp120 interactions by binding to the CD4 component. Human polyclon…
Decidual endothelial cells express surface-bound C1q as a molecular bridge between endovascular trophoblast and decidual endothelium.
2008
This study was prompted by the observation that decidual endothelial cells (DECs), unlike endothelial cells (ECs) of blood vessels in normal skin, kidney glomeruli and brain, express surface-bound C1q in physiologic pregnancy. This finding was unexpected, because deposits of C1q are usually observed in pathologic conditions and are associated with complement activation. In the case of DECs, we failed to detect immunoglobulins and C4 co-localized with C1q on the cell surface. Surprisingly, DECs expressed mRNA for the three chains of C1q and secreted detectable level of this component in serum-free medium. The ability to synthesize C1q is acquired by DECs during pregnancy and is not shared by…
Aromatase and amphiregulin are correspondingly expressed in human liver cancer cells
2009
Human hepatocellular carcinoma (HCC) is associated with high mortality rates, being the third most common cause of cancer death worldwide. Although estrogens have been implicated in HCC, their potential role in development and/or progression of this malignancy remains unclear. In this study we investigated mRNA and protein expression of aromatase (Aro) and amphiregulin (AREG) in relation to estrogen receptors (ERs), in HepG2, Huh7, and HA22T human malignant liver cell lines, using RT-PCR and Western blot analyses. Aro expression was significantly higher (approximately 13-fold, P= 0.003) in HepG2 cells than in Huh7 cells, while no Aro expression could be detected in HA22T cells. Interestingl…
Potential involvement of fas and its ligand in the pathogenesis of Hashimoto's thyroiditis
1997
The mechanisms responsible for thyrocyte destruction in Hashimoto's thyroiditis (HT) are poorly understood. Thyrocytes from HT glands, but not from nonautoimmune thyroids, expressed Fas. Interleukin-1β (IL-1β), abundantly produced in HT glands, induced Fas expression in normal thyrocytes, and cross-linking of Fas resulted in massive thyrocyte apoptosis. The ligand for Fas (FasL) was shown to be constitutively expressed both in normal and HT thyrocytes and was able to kill Fas-sensitive targets. Exposure to IL-1β induced thyrocyte apoptosis, which was prevented by antibodies that block Fas, suggesting that IL-1β-induced Fas expression serves as a limiting factor for thyrocyte destruction. Th…
Placenta-derived CD95 ligand causes liver damage in hemolysis, elevated liver enzymes, and low platelet count syndrome.
2004
Background & Aims: The HELLP (hemolysis, elevated liver enzymes, low platelets) syndrome is a life-threatening complication during pregnancy. The associated liver disease may be severe, and maternal hepatic complications may progress to the point that transplantation becomes necessary. CD95 (APO-1, Fas)-mediated apoptosis of liver cells is one of the major pathogenic mechanisms during liver disease. The interaction of CD95 with its ligand, CD95L(FasL), induces apoptosis and thus the source of the death-inducing ligand is critical for understanding the pathomechanism of liver damage involving the CD95-system. Methods: Sera from HELLP patients were analyzed and used in cell culture experiment…
Lysosomal trafficking in rat cardiac myocytes.
1990
By immunolabeling of cryosections, we have characterized in rat cardiac myocytes the cation-independent mannose-6-phosphate receptor (MPR), a lysosomal membrane glycoprotein, lgp120, and a lysosomal enzyme, MEP (homologous to cathepsin L). Most of the MPR label was located in large membrane-filled structures (MPR structures) in large clusters of mitochondria adjacent to but distinct from the Golgi complex. Lpg120 and MEP showed typical lysosomal localization throughout the cell, often associated with regions that appeared to contain autophagosome-like structures. In addition, MEP and lgp120 co-localized within MPR structures. MEP and MPR were localized inside the lumen of MPR structures. M…
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…
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…