scholarly journals Antibodies to tubulin and actin bind to the surface of a human monocytic cell line, U937.

1991 ◽  
Vol 39 (7) ◽  
pp. 981-985 ◽  
Author(s):  
S B Por ◽  
M A Cooley ◽  
S N Breit ◽  
R Penny ◽  
P W French
Keyword(s):  
Flow Cytometry ◽  
Cell Surface ◽  
Cell Line ◽  
Laser Scanning ◽  
Confocal Laser ◽  
Staining Procedure ◽  
Intermediate Filament Protein ◽  
U937 Cells ◽  
Monocytic Cell ◽  
Monocytic Cell Line

Intermittent reports of cytoskeleton proteins (actin and tubulin) on the cell surface have appeared over the last 13 years. Whereas most have concentrated on lymphocytes, this study provides evidence for the presence of these proteins on the surface of a human cultured monocyte-like cell line, U937. Both actin and tubulin were detected on the surface of U937 cells by flow cytometry, using an indirect staining procedure based on biotin-streptavidin-phycoerythrin, chosen for greater sensitivity. By use of this procedure, the majority of viable unstimulated U937 cells stained positively for actin and tubulin, although the level of fluorescence intensity was low. With an antibody specific for tyrosine-tubulin, most of the surface tubulin was also found to be tyrosinylated. For vimentin, an intermediate filament protein abundantly present in the cytoplasm of U937 cells, no staining could be detected. Confirmation of the flow cytometry data for surface actin and tubulin on unstimulated U937 cells was achieved by direct vesualization using a confocal laser scanning microscope. When U937 cells were activated with PMA and LPS, a marked reduction in the level of cell surface actin and tubulin occurred. The role of cell surface actin and tubulin on unstimulated U937 cells, in terms of monocyte function, remains to be elucidated.

scholarly journals Screening of compounds toxicity against human Monocytic cell line-THP-1 by flow cytometry

10.1251/bpo92 ◽  
2004 ◽  
Vol 6 (1) ◽  
pp. 220-225 ◽  
Author(s):  
Neora Pick ◽  
Scott Cameron ◽  
Dorit Arad ◽  
Yossef Av-Gay
Keyword(s):  
Flow Cytometry ◽  
Cell Line ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Human Monocytic Cell Line ◽  
Human Monocytic Cell

scholarly journals Interleukin-8 Is Differentially Expressed by Human-Derived Monocytic Cell Line U937 Infected with Mycobacterium tuberculosis H37Rv and Mycobacterium marinum

2003 ◽  
Vol 71 (10) ◽  
pp. 5480-5487 ◽  
Author(s):  
Chang-Hwa Song ◽  
Ji-Sook Lee ◽  
Hwa-Jung Kim ◽  
Jeong-Kyu Park ◽  
Tae-Hyun Paik ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Cell Line ◽  
Mycobacterium Marinum ◽  
Interleukin 8 ◽  
Differentially Expressed ◽  
Northern Hybridization ◽  
U937 Cells ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Infected Cells

ABSTRACT Although Mycobacterium marinum is closely related to Mycobacterium tuberculosis H37Rv genomically, the clinical outcome in humans is quite different for M. marinum and M. tuberculosis infections. We investigated possible factors in the host macrophages for determining differential pathological responses to M. tuberculosis and M. marinum using an in vitro model of mycobacterial infection. Using suppression-subtractive hybridization, we identified 12 differentially expressed genes in the human monocytic cell line U937 infected with M. tuberculosis and M. marinum. Of those genes, the most frequently recovered transcript encoded interleukin-8 (IL-8). Northern hybridization revealed that IL-8 mRNA was highly upregulated in M. tuberculosis-infected U937 cells compared with M. marinum-infected cells. In addition, enzyme-linked immunosorbent assay showed that IL-8 protein secretion was significantly elevated in M. tuberculosis-infected U937 cells, human primary monocytes, and monocyte-derived macrophages compared with that in M. marinum-infected cells. The depressed IL-8 expression was unique in M. marinum-infected cells compared with cells infected with other strains of mycobacteria, including M. tuberculosis H37Ra, Mycobacterium bovis BCG, or Mycobacterium smegmatis. When the expression of NF-κB was assessed in mycobacterium-infected U937 cells, IκBα proteins were significantly degraded in M. tuberculosis-infected cells compared with M. marinum-infected cells. Collectively, these results suggest that differential IL-8 expression in human macrophages infected with M. tuberculosis and M. marinum may be critically associated with distinct host responses in tuberculosis. Additionally, our data indicate that differential signal transduction pathways may underlie the distinct patterns of IL-8 secretion in cells infected by the two mycobacteria.

scholarly journals Development of specific receptors for N-formylated chemotactic peptides in a human monocyte cell line stimulated with lymphokines

1980 ◽  
Vol 152 (1) ◽  
pp. 31-40 ◽  
Author(s):  
MC Pike ◽  
DG Fischer ◽  
HS Koren ◽  
R Snyderman
Keyword(s):  
Cell Line ◽  
Binding Sites ◽  
Dissociation Constants ◽  
Specific Binding ◽  
Human Monocyte ◽  
Lymphocyte Culture ◽  
U937 Cells ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Human Monocytic Cell Line

A human monocyte-like cell line, U937, when grown in continuous culture, does not secrete lysosomal enzymes or migrate towards chemotactic factors. When the cells are stimulated by lymphokines, however, they develop the ability both to migrate directionally and to secrete enzymes in response to several types of chemoattractants. The development, by stimulated cells, of chemotactic and secretory responses to one class of chemoattractants, the N- formylated peptides, is accompanied by the appearance on the cells of specific binding sites for these substances. Using tritiated N-formyl- methionyl-leueyl-phenylalanine (fMet-Leu-[(3)H]Phe) as a ligand, it was determined that unstimulated U937 cells possess no detectable binding sites. However, after stimulation with lymphocyte culture supernates for 24, 48, and 72 h, they developed 4,505 (+/-) 1,138, 22,150(+/-) 4,030, and 37,200 (+/-) 8,000 sites/cell, respectively. The dissociation constants for the interaction of fMet-Leu-[SH]Phe with the binding sites were approximately the same regardless of stimulation time and ranged between 15 and 30 nM. The binding of fMet-Leu-[(3)H]Phe by stimulated U937 cells was rapid and readily reversed by the addition of a large excess of unlabeled peptide. The affinity of a series of N-formylated peptides for binding to U937 cells exactly reflected the potency of the peptides in inducing lysosomal enzyme secretion and chemotaxis. The availability of a continuous human monocytic cell line that can be induced to express receptors for N-formylated peptides will provide a useful tool not only for the characterization of such receptors but also for the delineation of regulatory mechanisms involved in cellular differentiation and the chemotactic response.

scholarly journals Acetylation of p-aminobenzoylglutamate, a folic acid catabolite, by recombinant human arylamine N-acetyltransferase and U937 cells

1995 ◽  
Vol 307 (1) ◽  
pp. 1-3 ◽  
Author(s):  
R F Minchin
Keyword(s):  
Folic Acid ◽  
Cell Line ◽  
U937 Cell ◽  
U937 Cells ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Major Urinary Metabolite ◽  
Endogenous Substrate

N-acetyl-p-aminobenzoylglutamate is a major urinary metabolite of folic acid. It is formed by acetylation of p-aminobenzoylglutamate following cleavage of the C9-N10 bond of folic acid. Using recombinant human type 1 (NAT1) and type 2 (NAT2) arylamine N-acetyltransferase, we have shown that p-aminobenzoylglutamate is a specific NAT1 substrate. At an acetyl-CoA concentration of 50 microM, the Km for p-aminobenzoylglutamate (pABG) acetylation by recombinant NAT1 was 130 +/- 13 microM. For the human pro-monocytic cell-line U937, the apparent Km was slightly higher (333 +/- 17 microM). Inhibitor studies supported NAT1-dependent acetylation of pABG by U937 cell cytosols. These studies are the first to identify a potential endogenous substrate for human NAT1 and suggest that this enzyme may be important in the cellular clearance of pABG.

scholarly journals A Defect in Influenza A Virus Particle Assembly Specific to Primary Human Macrophages

2017 ◽  
Author(s):  
Sukhmani Bedi ◽  
Takeshi Noda ◽  
Yoshihiro Kawaoka ◽  
Akira Ono
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Cell Line ◽  
Influenza A Virus ◽  
Influenza A ◽  
Actin Polymerization ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Particle Assembly ◽  
Human Macrophages

AbstractThe primary target of Influenza A virus (IAV) is epithelial cells in the respiratory tract. In contrast to epithelial cells, productive infection of most IAV strains is either blocked or highly inefficient in macrophages. The exact nature of the defect in IAV replication in human macrophages remains unknown. In this study, we showed that primary human monocyte-derived macrophages (MDM) are inefficient in IAV release even when compared to a monocytic cell line differentiated to macrophage-like cells, despite comparable levels of expression of viral glycoproteins at the plasma membrane. Correlative fluorescence scanning electron microscopy revealed that formation of budding structures at the cell surface is inefficient in MDM even though clustering of a viral glycoprotein, hemagglutinin (HA), is observed, suggesting that IAV particle assembly is blocked in human MDM. Using anin situproximity ligation assay, we further determined that association between HA and the viral ion channel protein M2 is defective at the plasma membrane of MDM. In contrast, HA and another glycoprotein neuraminidase (NA) associate with each other on the MDM surface efficiently. Notably, the defect in association between HA and M2 in MDM was reversed upon inhibition of actin polymerization by cytochalasin D. Altogether, these results suggest that HA-M2 association on the plasma membrane is a discrete step in the IAV assembly process, which is separable from the association between HA and NA and susceptible to suppression by actin cytoskeleton. Overall, our study revealed the presence of a cell-type-specific mechanism negatively regulating IAV assembly at the plasma membrane.ImportanceIdentification of host cell determinants promoting or suppressing replication of many viruses has been aided by analyses of host cells that impose inherent blocks on viral replication. In this study, we show that primary human MDM are not permissive to IAV replication due to a defect at the virus particle formation step. This defect is specific to primary human macrophages, since a human monocytic cell line differentiated to macrophage-like cells supports IAV particle formation. We further identified association between two viral transmembrane proteins, HA and M2, on the cell surface as a discrete assembly step, which is defective in MDM. Defective HA-M2 association in MDM is rescued by disruption of the actin cytoskeleton, revealing a previously unknown, negative role for actin polymerization, which is generally thought to play positive roles in IAV assembly. Overall, our study uncovered a host-mediated restriction of association between viral transmembrane components during IAV assembly.

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