scholarly journals Characterization of a complement-fragment-C5a-stimulated calcium-influx mechanism in U937 monocytic cells

1993 ◽  
Vol 295 (3) ◽  
pp. 679-684 ◽  
Author(s):  
P N Monk ◽  
L J Partridge
Keyword(s):  
Cell Line ◽  
Pertussis Toxin ◽  
Inositol Phosphates ◽  
Calcium Influx ◽  
Cell Types ◽  
U937 Cells ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Monocytic Cells

The mechanism by which complement fragment C5a elevates intracellular Ca2+ ([Ca2+]i) levels in two cell types, a monocytic cell line, U937, and neutrophils, has been investigated by the use of fluorometric and radiometric techniques. In U937 cells the influx of extracellular Ca2+ can be distinguished from the release of intracellular Ca2+ stores in terms of dose-responsiveness to C5a and sensitivity to pertussis-toxin poisoning. This suggests that the mechanism of Ca2+ influx in these cells is at least partially independent of both the production of inositol phosphates and elevation of internal Ca2+ concentration. The C5a-stimulated influx of 45Ca2+ into U937 cells is inhibited by a series of metal ions (Zn2+ > Co2+ > Mn2+ > Sr2+ approximately equal to Ni2+ > La3+). The stimulated influx of Ca2+ into neutrophils is inhibited differently (Ni2 >> Co2+ > Zn2+ approximately equal to La3+ > Mn2+ approximately equal to Sr2+), is less sensitive to C5a and both the influx of extracellular Ca2+ and the release of intracellular stores are equally sensitive to pertussis toxin treatment. Taken together these results indicate that [Ca2+]i is controlled in U937 monocytes by mechanisms distinct from those which appear to operate in other myeloid cells, such as neutrophils, stimulated with C5a and formylpeptide.

Increased calcium influx in a monocytic cell line on exposure to ultrafine carbon black

2000 ◽  
Vol 15 (2) ◽  
pp. 297 ◽  
Author(s):  
V. Stone ◽  
M. Tuinman ◽  
J.E. Vamvakopoulos ◽  
J. Shaw ◽  
D. Brown ◽  
...  
Keyword(s):  
Carbon Black ◽  
Cell Line ◽  
Calcium Influx ◽  
Monocytic Cell ◽  
Monocytic Cell Line

scholarly journals Chemical and hydrodynamic characterization of the human leucocyte receptor for complement subcomponent C1q

1989 ◽  
Vol 262 (2) ◽  
pp. 625-631 ◽  
Author(s):  
R Malhotra ◽  
R B Sim
Keyword(s):  
Amino Acid ◽  
Polypeptide Chain ◽  
Solid Phase ◽  
U937 Cells ◽  
Amino Acid Residues ◽  
Human Tonsil ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Complement Component C3

A procedure for preparation of the receptor for complement subcomponent Clq from human tonsil lymphocytes and the monocytic cell line U937 was developed. The procedure is suitable for isolation of several hundred micrograms of the receptor, Clq-R, and has yielded sufficient material for chemical and hydrodynamic characterization. Clq-R from tonsil lymphocytes behaves identically with that from U937 cells. Clq-R has a monomer Mr of 56,000, and is an acidic glycoprotein containing about 17% carbohydrate. The polypeptide chain length is estimated to be 416-448 amino acid residues, with two or three sites for N-linked glycosylation. Detergent-solubilized Clq-R exists as an elongated dimer (f/fo = 1.8), and does not bind a significant weight of detergent. The radioiodinated isolated receptor binds specifically and saturably to solid-phase Clq, but not to collagen, IgG, bovine serum albumin or complement component C3.

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 Secretion of interleukin-8 by human-derived cell lines infected withMycobacterium bovis

2004 ◽  
Vol 13 (1) ◽  
pp. 45-49 ◽  
Author(s):  
Patricia Méndez-Samperio ◽  
Janet Palma-Barrios ◽  
Abraham Vázquez-Hernández ◽  
Elizabeth García-Martínez
Keyword(s):  
Infected Cell ◽  
Cell Line ◽  
Cell Lines ◽  
Immunosorbent Assay ◽  
Calcium Influx ◽  
Enzyme Linked Immunosorbent Assay ◽  
U937 Cells ◽  
Tetraacetic Acid ◽  
Acetoxymethyl Ester ◽  
Monocytic Cell

Background: The variable efficacy of bacillus Calmette-Guérin (Mycobacterium bovisBCG) in protecting humans against tuberculosis has prompted a search for the mechanisms through which BCG induces chemokines. In this study, our experiments were designed to determine the role of the transcription factor nuclear factor-κB (NF-κB) and intracellular calcium in the production of interleukin (IL)-8, a main chemotactic factor, by human-derived monocytic cell line U937 and by a human epithelial HEp-2 cell line infected withM.bovisBCG.Methods: The concentrations of IL-8 in culture supernatants of U937 cells or HEp-2 cells infected withM. bovisBCG were determined by enzyme-linked immunosorbent assay. We used sulfasalazine and curcumin, which are well-described inhibitors of NF-κB activity, and we used ethylenediamine tetraacetic acid to deplete extracellular Ca2+or used the cell-permeable agent 1,2-bis (2-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid tetra (acetoxymethyl) ester to chelate releasable intracellular stores of Ca2+in order to investigate the mechanisms through whichM.bovisBCG induces IL-8 secretion in our system.Results: The enzyme-linked immunosorbent assay showed that IL-8 protein secretion was elevated inM.bovis-infected cell lines. This effect was statistically significant(p<0.01). When calcium influx was suppressed inM.bovis-infected cell lines, IL-8 secretion was inhibited. Notably, specific inhibitors of NF-κB (sulfasalazine and curcumin) inhibitedM.bovis-induced IL-8 secretion from U937 cells or HEp-2 cells.Conclusions: Collectively, these results indicate that activation of NF-κB is an important signal transduction pathway inM.bovis-induced IL-8 secretion in monocytic or epithelial cells. Furthermore, the results showed that calcium influx had a direct effect on IL-8 secretion in U937 cells or HEp-2 cells infected withM.bovis.

scholarly journals Fish Monocytes as a Model for Mycobacterial Host-Pathogen Interactions

2001 ◽  
Vol 69 (12) ◽  
pp. 7310-7317 ◽  
Author(s):  
Sahar H. El-Etr ◽  
Ling Yan ◽  
Jeffrey D. Cirillo
Keyword(s):  
Mycobacterium Smegmatis ◽  
Virulence Determinants ◽  
Monocytic Cell ◽  
Monocytic Cell Line ◽  
Monocytic Cells ◽  
Vitro Model ◽  
Mycobacterial Pathogenesis ◽  
Identification And Characterization

ABSTRACT Mycobacterium marinum, a relatively rapid-growing fish and human pathogen, has become an important model for the investigation of mycobacterial pathogenesis. M. marinumis closely related to the Mycobacterium tuberculosiscomplex and causes a disease in fish and amphibians with pathology similar to tuberculosis. We have developed an in vitro model for the study of M. marinum virulence mechanisms using the carp monocytic cell line CLC (carp leukocyte culture). We found that fish monocytes can differentiate between pathogenic and nonpathogenic mycobacterial species. Interestingly, M. marinum enters fish monocytes at a 40- to 60-fold-higher rate thanMycobacterium smegmatis. In addition, M. marinum survives and replicates in fish monocytes whileM. smegmatis is killed. We also found that M. marinum inhibits lysosomal fusion in fish monocytes, indicating that these cells may be used to dissect the mechanisms of intracellular trafficking in mycobacteria. We conclude from these observations that monocytic cells from fish, a natural host for M. marinum, provide an extremely valuable model for the identification and characterization of mycobacterial virulence determinants in the laboratory.

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.

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