scholarly journals Phosphorylation and internalization of gp130 occur after IL-6 activation of Jak2 kinase in hepatocytes.

1994 ◽  
Vol 5 (7) ◽  
pp. 819-828 ◽  
Author(s):  
Y Wang ◽  
G M Fuller
Keyword(s):  
Protein Synthesis ◽  
Cell Surface ◽  
De Novo ◽  
Cell Types ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Protein Synthesis Inhibitors ◽  
Different Cell Types ◽  
Kinetics Of

Recent evidence has shown that members of the Jak kinase family are activated after IL-6 binds to its receptor complex, leading to a tyrosine phosphorylation of gp130, the IL-6 signal-transducing subunit. The different members of the IL-6 cytokine subfamily induce distinct patterns of Jak-Tyk phosphorylation in different cell types. Using monospecific antibodies to gp130, Jak2 kinase, and phosphotyrosine, we investigated the kinetics of IL-6 stimulation of members of this pathway in primary hepatocytes. Our findings show that Jak 2 is maximally activated within 2 min of exposure to IL-6, followed by gp130 phosphorylation that reaches its peak in another 2 min then declines to basal level by 60 min. In vitro phosphorylation experiments show that activated Jak 2 is able to phosphorylate both native gp130 and a fusion peptide containing its cytoplasmic domain, demonstrating gp130 is a direct substrate of Jak 2 kinase. Experiments designed to explore the cell surface expression of gp130 show that > or = 2 h are required to get a second round of phosphorylation after the addition of more cytokines. This finding suggests that activated gp130 is internalized from the cell surface after IL-6 stimulation. Additional experiments using protein synthesis inhibitors reveal that new protein synthesis is required to get a second cycle of gp130 phosphorylation indicating gp130 must be synthesized de novo and inserted into the membrane. These findings provide strong evidence that down regulation of the IL-6 signal in hepatocytes involves the internalization and cytosol degradation of gp130.

scholarly journals Pseudorabies virus US3- and UL49.5-dependent and -independent downregulation of MHC I cell surface expression in different cell types

Virology ◽  
2009 ◽  
Vol 395 (2) ◽  
pp. 172-181 ◽  
Author(s):  
Matthias J. Deruelle ◽  
Céline Van den Broeke ◽  
Hans J. Nauwynck ◽  
Thomas C. Mettenleiter ◽  
Herman W. Favoreel
Keyword(s):  
Cell Surface ◽  
Pseudorabies Virus ◽  
Cell Types ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Mhc I ◽  
Different Cell Types

Aggregation of mononucleated precursors triggers cell surface expression of alphavbeta3 integrin, essential to formation of osteoclast-like multinucleated cells

1998 ◽  
Vol 111 (17) ◽  
pp. 2563-2574 ◽  
Author(s):  
P. Boissy ◽  
I. Machuca ◽  
M. Pfaff ◽  
D. Ficheux ◽  
P. Jurdic
Keyword(s):  
Cell Surface ◽  
De Novo ◽  
Osteoclast Differentiation ◽  
Cell Aggregation ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Dihydroxyvitamin D3 ◽  
Osteoclast Precursors ◽  
Integrin Alphavbeta3

Alphavbeta3 is a key integrin mediating adhesion of multinucleated osteoclasts during bone resorption. 1, 25-dihydroxyvitamin D3 upregulates alphavbeta3 integrin expression in mononucleated osteoclast precursors and concomitantly stimulates their differentiation into osteoclasts. This suggests that this integrin could play a major role during osteoclast differentiation.We have developed an in vitro model, in which 1, 25-dihydroxyvitamin D3 sequentially modifies the behavior of macrophages: It first induces rounding up of these cells, then their subsequent aggregation and spreading, which finally leads to cell fusion and the formation of osteoclast-like multinucleated giant cells. We show that, while 1,25-dihydroxyvitamin D3 stimulates the de novo synthesis of alphavbeta3 in macrophages early in this process, its accumulation on the surface is triggered by cell aggregation. A high level of integrin alphavbeta3 cell surface expression correlates with macrophage spreading preceding fusion. This was confirmed by means of novel cell permeable peptides containing the C-terminal sequence of the integrin beta3 tail to specifically block (alphavbeta3 function. Although this peptide has no effect on the aggregation step, it disrupts the spreading of osteoclast precursors and consequently inhibits their fusion. These findings suggest a novel role of the integrin alphavbeta3 in a discrete step of osteoclast differentiation.

scholarly journals Analysis of functional domains of the v-fms-encoded protein of Susan McDonough strain feline sarcoma virus by linker insertion mutagenesis.

1987 ◽  
Vol 7 (9) ◽  
pp. 3287-3296 ◽  
Author(s):  
S D Lyman ◽  
L R Rohrschneider
Keyword(s):  
Cell Surface ◽  
Biological Effects ◽  
Intracellular Localization ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Insertion Mutagenesis ◽  
Focus Formation ◽  
External Domain ◽  
Sarcoma Virus

The Susan McDonough strain of feline sarcoma virus contains an oncogene, v-fms, which is capable of transforming fibroblasts in vitro. The mature protein product of the v-fms gene (gp140fms) is found on the surface of transformed cells; this glycoprotein has external, transmembrane, and cytoplasmic domains. To assess the functional role of these domains in transformation, we constructed a series of nine linker insertion mutations throughout the v-fms gene by using a dodecameric BamHI linker. The biological effects of these mutations on the function and intracellular localization of v-fms-encoded proteins were determined by transfecting the mutated DNA into Rat-2 cells. Most of the mutations within the external domain of the v-fms-encoded protein eliminated focus formation on Rat-2 cells; three of these mutations interfered with the glycosylation of the v-fms protein and interfered with formation of the mature gp140fms. One mutation in the external domain led to cell surface expression of v-fms protein even in the absence of complete glycosylational processing. Cell surface expression of mutated v-fms protein is probably necessary, but is not sufficient, for cell transformation since mutant v-fms protein was found on the surface of several nontransformed cell lines. Mutations that were introduced within the external domain had little effect on in vitro kinase activity, whereas mutations within the cytoplasmic domain all had strong inhibitory effects on this activity.

scholarly journals Carbohydrate-dependent B cell activation by fucose-binding bacterial lectins

2019 ◽  
Vol 12 (571) ◽  
pp. eaao7194 ◽  
Author(s):  
Isabel Wilhelm ◽  
Ella Levit-Zerdoun ◽  
Johanna Jakob ◽  
Sarah Villringer ◽  
Marco Frensch ◽  
...  
Keyword(s):  
B Cells ◽  
Cell Surface ◽  
B Cell ◽  
Cell Activation ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
B Cell Activation ◽  
Intracellular Ca ◽  
Bacterial Lectins

Bacterial lectins are typically multivalent and bind noncovalently to specific carbohydrates on host tissues to facilitate bacterial adhesion. Here, we analyzed the effects of two fucose-binding lectins, BambL fromBurkholderia ambifariaand LecB fromPseudomonas aeruginosa, on specific signaling pathways in B cells. We found that these bacterial lectins induced B cell activation, which, in vitro, was dependent on the cell surface expression of the B cell antigen receptor (BCR) and its co-receptor CD19, as well as on spleen tyrosine kinase (Syk) activity. The resulting release of intracellular Ca2+was followed by an increase in the cell surface abundance of the activation marker CD86, augmented cytokine secretion, and subsequent cell death, replicating all of the events that are observed in vitro upon canonical and antigen-mediated B cell activation. Moreover, injection of BambL in mice resulted in a substantial, BCR-independent loss of B cells in the bone marrow with simultaneous, transient enlargement of the spleen (splenomegaly), as well as an increase in the numbers of splenic B cells and myeloid cells. Together, these data suggest that bacterial lectins can initiate polyclonal activation of B cells through their sole capacity to bind to fucose.

scholarly journals Both Freshly Prepared and Frozen-Stored Amniotic Membrane Cells Express the Complement Inhibitor CD59

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Ágnes Füst ◽  
Éva Pállinger ◽  
Adrienn Stündl ◽  
Eszter Kovács ◽  
László Imre ◽  
...  
Keyword(s):  
Cell Surface ◽  
Amniotic Membrane ◽  
Ocular Surface ◽  
Cell Types ◽  
Surface Expression ◽  
Mesenchymal Cells ◽  
Cell Surface Expression ◽  
Complement Inhibitor ◽  
Becton Dickinson ◽  
Intracellular Expression

Amniotic membrane proved to be very effective tool in the treatment of a number of ocular surface diseases. The amniotic membrane, however, has to be stored before its transplantation onto the ocular surface followed by mandatory serologic control in order to exclude the transmission of certain viruses. Therefore it is most important to study if cryopreservation of the membrane affects cell surface expression of the molecules. We measured cell surface expression of CD59, a membrane-bound complement inhibitor on the cells of freshly prepared and cryopreserved amniotic membrane. Cells of amniotic membrane were separated mechanically. Epithelial and mesenchymal cells were identified by the intracellular expression of nanog and the cell surface ICAM1 positivity, respectively. Multicolor flow cytometric immunophenotyping was used for determination of the CD59 expression. CellQuest-Pro software program (Becton Dickinson) was used both for measurements and analysis. CD59-positive cells could be detected in all investigated samples and in all investigated cell types, although the expression level of CD59 differed. CD59 was expressed both on freshly prepared and frozen-stored samples. Higher level of CD59 was detected on ICAM1+ mesenchymal cells than on nanog+ epithelial cells. Our findings indicate that amniotic membranes maintain their complement inhibiting capacity after cryopreservation.

scholarly journals Mammalian PIG-L and its yeast homologue Gpi12p are N-acetylglucosaminylphosphatidylinositol de-N-acetylases essential in glycosylphosphatidylinositol biosynthesis

1999 ◽  
Vol 339 (1) ◽  
pp. 185-192 ◽  
Author(s):  
Reika WATANABE ◽  
Kazuhito OHISHI ◽  
Yusuke MAEDA ◽  
Nobuo NAKAMURA ◽  
Taroh KINOSHITA
Keyword(s):  
Cell Surface ◽  
Chinese Hamster ◽  
Surface Expression ◽  
Amino Acid Identity ◽  
Eukaryotic Cell ◽  
Surface Proteins ◽  
Ovary Cell ◽  
Cell Surface Expression ◽  
Expression Cloning

Glycosylphosphatidylinositol (GPI) is used as a membrane anchor by many eukaryotic cell-surface proteins. The second step of GPI biosynthesis is de-N-acetylation of N-acetylglucosaminylphosphatidylinositol (GlcNAc-PI). We have previously cloned the rat PIG-L gene by expression cloning that complemented a mutant Chinese hamster ovary cell line defective in this step. Here we show that recombinant rat PIG-L protein purified from Escherichia coli as a complex with GroEL has GlcNAc-PI de-N-acetylase activity in vitro. The activity was not enhanced by GTP, which is known to enhance the de-N-acetylase activity of mammalian cell microsomes. As with other de-N-acetylases that act on the GlcNAc moiety, metal ions, in particular Mn2+ and Ni2+, enhanced the enzyme activity of PIG-L. The Saccharomyces cerevisiae YMR281W open reading frame encodes a protein (termed Gpi12p) with 24% amino acid identity with rat PIG-L. On transfection into mammalian PIG-L-deficient cells, this gene, GPI12, restored the cell-surface expression of GPI-anchored proteins and GlcNAc-PI de-N-acetylase activity. The disruption of the gene caused lethality in S. cerevisiae. These results indicate that GlcNAc-PI de-N-acetylase is conserved between mammals and yeasts and that the de-N-acetylation step is also indispensable in yeasts.

Prognostic significance of leukopenia at the time of diagnosis in acute myeloid leukemia (AML)

2009 ◽  
Vol 27 (15_suppl) ◽  
pp. 7070-7070
Author(s):  
M. L. Arellano ◽  
E. Winton ◽  
L. Pan ◽  
L. Souza ◽  
S. Sunay ◽  
...  
Keyword(s):  
Cell Surface ◽  
Adhesion Molecules ◽  
De Novo ◽  
Risk Group ◽  
Statistical Significance ◽  
Univariate Analysis ◽  
Prognostic Significance ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Surface Adhesion

7070 Background: In contrast to the poor prognosis associated with hyperleukocytosis, the prognostic significance of leukopenia at the time of diagnosis of AML is unknown. Methods: Single institution retrospective analysis of 225 consecutive, newly diagnosed AML patients (pts), homogeneously treated between July 1996 and February 2005; and divided into 2 groups based on presenting WBC: < 2,000/uL (30) and > 2,000/uL (195). Simultaneously obtained peripheral blood and marrow blasts were analyzed for cell surface expression of CD34, cKit, CXCR4, PCAM, VLA-2, VLA-3, VLA-4, VLA-5, and FLT3 using flow cytometry. Results: Patients’ characteristics (gender, secondary vs. de novo, and cytogenetic [CTG] risk) were comparable between the 2 groups. Leukopenic AML pts were older (median 56 vs. 53 years, p = 0.02), and had lower induction complete remission [CR] rates: 63% vs. 81% (p = 0.03) by univariate analysis. Induction mortality was 0% for leukopenic and 5% for non-leukopenic pts. In primary refractory pts, median survival was longer for leukopenic (11) vs. non-leukopenic (34) pts: 137 vs. 81 d (p = 0.026). Median follow-up was 22 mos. Event-free (EFS), disease-free (DFS), and overall survivals (OS) were lower in the leukopenic group: 12 vs. 14; 14 vs. 17; and 17 vs. 19 mos, respectively; but did not reach statistical significance. By multivariate analysis, age (p < 0.0001) and CTG risk group (p < 0.0001) were independent predictors of OS, while CTG risk group predicted RFS (p < 0.0001). The level of expression of cell surface adhesion molecules on blood and marrow blasts was comparable for the 2 groups. Conclusions: AML pts presenting with leukopenia have comparable outcomes to those presenting with normal or high WBC despite a lower likelihood of achieving remission. Leukopenic AML did not have over-expression of cell surface adhesion molecules. No significant financial relationships to disclose.

Assessing factors for predictive response to ADC targets in clinical tissue for companion diagnostic development.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. e22187-e22187
Author(s):  
Steven James Potts ◽  
Joseph Krueger ◽  
Holger Lange ◽  
David Eberhard ◽  
George David Young
Keyword(s):  
Tumor Microenvironment ◽  
Cell Surface ◽  
Surface Expression ◽  
Receptor Internalization ◽  
Critical Parameters ◽  
Cell Surface Expression ◽  
Cell Surface Antigens ◽  
Drug Conjugates ◽  
Coefficients Of Variation

e22187 Background: One premise of antibody-drug conjugates (ADC) is that the bound mAb-antigen complex on the cell surface will internalize and be metabolized by lysosomal proteases to release the free drug. Thus, the efficacy of an ADC is dependent not only on the presence of cell surface antigens, but also intact delivery of the conjugated drug. In most cases, the biological mechanisms behind these processes have not been elucidated. Furthermore, the extracellular stability of the ADC may be affected by the activity of the target proteases in the tumor microenvironment outside of the lysozome. These concepts are especially important for CDx approaches, which would ideally account not only for the degree of cell surface expression of the target, but also receptor internalization and potential effects of tumor microenvironment. Although in vitro approaches exist to measure these attributes, there are no clinically amenable approaches to measure these critical parameters. Methods: Flagship Biosciences has invented several proprietary approaches for measuring critical properties of the therapeutic target on the cell surface or inside the cell, as well as properties of the TME which could be used to predict efficacy to an ADC using FFPE biopsies. These image analysis approaches have been designed specifically in context of ADC CDx programs to: 1) Accurately define cell surface target expression independent of cytoplasmic expression; 2) Assess critical factors in the TME which may affect delivery of the drug to the intracellular target; and 3) Multiplex these evaluations for an integrative answer to be derived from a typical clinical biopsy. Results: The measurement of cytoplasm/membrane localization was evaluated on several hundred tissue sections, and the methodology was found to be highly reproducible, with coefficients of variation lower than that observed by manual pathologist accessment. Conclusions: Our approach discretely measures endpoints of cell surface biomarker prevalence, biomarker membrane/cytoplasmic ratio, heterogeneity, stromal contribution, inflammatory environment, and other important cell-by-cell outputs from a single FFPE slide in the context of typical drug discovery.

scholarly journals Significance of Nano- and Microtopography for Cell-Surface Interactions in Orthopaedic Implants

2007 ◽  
Vol 2007 ◽  
pp. 1-19 ◽  
Author(s):  
M. Jäger ◽  
C. Zilkens ◽  
K. Zanger ◽  
R. Krauspe
Keyword(s):  
Cell Surface ◽  
Cell Types ◽  
Surface Interactions ◽  
Orthopaedic Implants ◽  
Nanostructured Surfaces ◽  
Major Interest ◽  
Cell Surface Interactions ◽  
Biomaterial Application ◽  
Different Cell Types

Cell-surface interactions play a crucial role for biomaterial application in orthopaedics. It is evident that not only the chemical composition of solid substances influence cellular adherence, migration, proliferation and differentiation but also the surface topography of a biomaterial. The progressive application of nanostructured surfaces in medicine has gained increasing interest to improve the cytocompatibility and osteointegration of orthopaedic implants. Therefore, the understanding of cell-surface interactions is of major interest for these substances. In this review, we elucidate the principle mechanisms of nano- and microscale cell-surface interactions in vitro for different cell types onto typical orthopaedic biomaterials such as titanium (Ti), cobalt-chrome-molybdenum (CoCrMo) alloys, stainless steel (SS), as well as synthetic polymers (UHMWPE, XLPE, PEEK, PLLA). In addition, effects of nano- and microscaled particles and their significance in orthopaedics were reviewed. The significance for the cytocompatibility of nanobiomaterials is discussed critically.

scholarly journals Cholangiocyte expression of α2β1-integrin confers susceptibility to rotavirus-induced experimental biliary atresia

2008 ◽  
Vol 295 (1) ◽  
pp. G16-G26 ◽  
Author(s):  
Mubeen Jafri ◽  
Bryan Donnelly ◽  
Steven Allen ◽  
Alex Bondoc ◽  
Monica McNeal ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Cell Surface ◽  
Biliary Atresia ◽  
Cell Lines ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Newborn Mice ◽  
A Cell

Inoculation of BALB/c mice with rhesus rotavirus (RRV) in the newborn period results in biliary epithelial cell (cholangiocyte) infection and the murine model of biliary atresia. Rotavirus infection of a cell requires attachment, which is governed in part by cell-surface expression of integrins such as α2β1. We hypothesized that cholangiocytes were susceptible to RRV infection because they express α2β1. RRV attachment and replication was measured in cell lines derived from cholangiocytes and hepatocytes. Flow cytometry was performed on these cell lines to determine whether α2β1 was present. Cholangiocytes were blocked with natural ligands, a monoclonal antibody, or small interfering RNA against the α2-subunit and were infected with RRV. The extrahepatic biliary tract of newborn mice was screened for the expression of the α2β1-integrin. Newborn mice were pretreated with a monoclonal antibody against the α2-subunit and were inoculated with RRV. RRV attached and replicated significantly better in cholangiocytes than in hepatocytes. Cholangiocytes, but not hepatocytes, expressed α2β1 in vitro and in vivo. Blocking assays led to a significant reduction in attachment and yield of virus in RRV-infected cholangiocytes. Pretreatment of newborn pups with an anti-α2 monoclonal antibody reduced the ability of RRV to cause biliary atresia in mice. Cell-surface expression of the α2β1-integrin plays a role in the mechanism that confers cholangiocyte susceptibility to RRV infection.

Sign in / Sign up

Export Citation Format

Share Document