scholarly journals Regulation of plasminogen activator in 3T3 cells: effect of phorbol myristate acetate on subcellular distribution and molecular weight.

1981 ◽  
Vol 90 (3) ◽  
pp. 727-731 ◽  
Author(s):  
S Jaken ◽  
P H Black
Keyword(s):  
Molecular Weight ◽  
Plasma Membrane ◽  
Plasminogen Activator ◽  
Phorbol Myristate Acetate ◽  
Subcellular Distribution ◽  
Tumor Promoter ◽  
3T3 Cells ◽  
Myristate Acetate ◽  
Extracellular Release ◽  
Swiss 3T3

The tumor promoter, phorbol myristate acetate (PMA), stimulates plasminogen activator production and extracellular release in confluent Swiss 3T3 cells. Coordinated with the increased extracellular release is a redistribution of the activity into plasma membrane-enriched fractions and a shift in the predominant molecular weight species from 75,000 to 49,000 daltons. The evidence suggests that PMA induces the formation of the 49,000 dalton species which is preferentially located in plasma membrane-enriched fractions.

scholarly journals Correlation between a specific molecular weight form of plasminogen activator and metabolic activity of 3T3 cells.

1981 ◽  
Vol 90 (3) ◽  
pp. 721-726 ◽  
Author(s):  
S Jaken ◽  
P H Black
Keyword(s):  
Molecular Weight ◽  
Plasminogen Activator ◽  
Growth Stimulation ◽  
Transformed Cells ◽  
3T3 Cells ◽  
Myristate Acetate ◽  
Quiescent Cells ◽  
Predominant Form ◽  
Molecular Weight Form ◽  
Stimulation Of

In quiescent cultures of 3T3 cells, plasminogen activator (PA) is found predominantly as a 75,000 dalton species. When quiescent cells are exposed to mitogenic agents such as phorbol myristate acetate, Ca++, or 25% serum, the absolute levels of PA in cell lysates may either increase or decrease. However, a consistent observation is that in the stimulated cultures PA is found predominantly as a 49,000 dalton species. This also is the predominant form of PA in growing and transformed cells. Concomitant with the mitogen-induced stimulation of the 49,000 dalton PA in quiescent cultures is a change in morphology to one that is characteristic of growing and transformed cells. The data suggest that PA is not operative in causing the morphological change that occurs with activation; however, the 49,000 dalton PA in particular is closely related to the pleiotypic response accompanying growth stimulation and transformation.

Factors which affect DNA strand breakage in human leukocytes exposed to a tumor promoter, phorbol myristate acetate

1982 ◽  
Vol 60 (11) ◽  
pp. 1359-1366 ◽  
Author(s):  
H. C. Birnboim
Keyword(s):  
Hydrogen Peroxide ◽  
Dna Damage ◽  
Phorbol Myristate Acetate ◽  
Respiratory Burst ◽  
Superoxide Anion ◽  
Tumor Promoter ◽  
Myristate Acetate ◽  
Strand Breakage ◽  
Dna Strand ◽  
Dna Strand Breakage

We have recently reported that phorbol myristate acetate (PMA) induces extensive DNA strand break damage in human peripheral blood leukocytes. The mechanism of action involves superoxide anion and hydrogen peroxide which are generated by phagocytes during the "respiratory burst." In this report, we describe the effect of various inhibitors and scavengers on PMA-induced DNA damage. Azide and cyanide greatly increased the level of damage; sulfhydryl compounds (glutathione, cysteine, and cysteamine) and ascorbate markedly decreased the level of damage. Hydroxyl radical scavengers such as dimethyl sulfoxide (DMSO) and glycerol also decreased the level of damage but apparently did so by inhibiting the respiratory burst. Diethyldithiocarbamate (DDC) increased the level of DNA damage at low concentrations (<1 mM), but decreased DNA damage at ≥1 mM. The results are consistent with a mechanism involving superoxide anion and hydrogen peroxide, but the precise reaction (free radical or enzymatic) responsible for DNA strand breakage has not been determined. The PMA-stimulated phagocyte is an interesting model system for looking at "active oxygen" mediated DNA damage and factors which influence it.

scholarly journals A high-affinity receptor for urokinase plasminogen activator on human keratinocytes: characterization and potential modulation during migration.

1990 ◽  
Vol 1 (11) ◽  
pp. 843-852 ◽  
Author(s):  
H McNeill ◽  
P J Jensen
Keyword(s):  
Molecular Weight ◽  
Plasma Membrane ◽  
Plasminogen Activator ◽  
Binding Sites ◽  
Human Keratinocytes ◽  
Urokinase Plasminogen Activator ◽  
Receptor Expression ◽  
Epithelial Migration ◽  
High Affinity ◽  
Upa Receptor

Low passage cultures of normal human keratinocytes produce several components of the plasminogen activator/plasmin proteolytic cascade, including urokinase plasminogen activator (uPA), tissue plasminogen activator (tPA), and two specific inhibitors. Studies here presented demonstrate that these cells also contain a high-affinity (Kd = 3 x 10(-10) M) plasma membrane-binding site for uPA. High molecular weight uPA, either as the single-chain precursor or two-chain activated form, bound to the receptor; however, low molecular weight (33 kD) uPA, tPA, or epidermal growth factor did not compete for binding, demonstrating specificity. Acid treatment, which removed endogenous uPA from the receptor, was required to detect maximal binding (45,000 sites per cell). To investigate the possibility that the uPA receptor on keratinocytes may be involved in epithelial migration during wound repair, cultures were wounded and allowed to migrate into the wounded site. Binding sites for uPA were localized by autoradiographic analysis of 125I-uPA binding as well as by immunocytochemical studies using anti-uPA IgG. With both techniques uPA binding sites were detected selectively on the plasma membrane of cells at the leading edge of the migrating epithelial sheet. This localization pattern suggests that uPA receptor expression on keratinocytes may be coupled to cell migration during cutaneous wounding.

Suppressive action of cobalt on exocytosis and respiratory burst in neutrophils

1989 ◽  
Vol 257 (5) ◽  
pp. C859-C864 ◽  
Author(s):  
J. G. Elferink ◽  
M. Deierkauf
Keyword(s):  
Plasma Membrane ◽  
Phorbol Myristate Acetate ◽  
Respiratory Burst ◽  
Cytochalasin B ◽  
Superoxide Production ◽  
Co2 Activation ◽  
Chemotactic Peptide ◽  
Myristate Acetate ◽  
Intracellular Target ◽  
Suppressive Action

Activation of exocytosis and respiratory burst in rabbit neutrophils by the chemotactic peptide fMet-Leu-Phe is inhibited by Co2+. Inhibition is antagonized by extracellular Ca2+ and is dependent on the time of preincubation of cells with Co2+ before addition of activator. Co2+ inhibits the enhancement of 45Ca association that occurs during activation with fMet-Leu-Phe. Interference with Ca2+ translocation across the plasma membrane by Co2+ is probably not the cause of inhibition of neutrophil activation, because activation in the absence of extracellular Ca2+ is inhibited by Co2+. Activation of neutrophils by phorbol myristate acetate is inhibited at higher Co2+ concentrations than activation by fMet-Leu-Phe. Inhibition of the superoxide production by Co2+ occurs both in the presence or in the absence of cytochalasin B. Fluorescence of neutrophils loaded with quin2 is diminished by Co2+, indicating that Co2+ had entered into the cytoplasm. The results are compatible with the view that Co2+ inhibits exocytosis and respiratory burst in neutrophils by an interaction with a Ca2+-dependent intracellular target.

Trypsin-uncoupled synthesis and secretion of yeast invertase: implications for the mechanism of secretion

1979 ◽  
Vol 25 (4) ◽  
pp. 528-534 ◽  
Author(s):  
Bruce E. Holbein ◽  
Denis K. Kidby
Keyword(s):  
Molecular Weight ◽  
Plasma Membrane ◽  
Subcellular Distribution ◽  
Plasma Membranes ◽  
External Surface ◽  
Internal Surface ◽  
Low Molecular Weight ◽  
Synthetase Activity ◽  
Trypsin Treatment ◽  
Yeast Invertase

The subcellular distribution of invertase was examined after synthesis and secretion by sphaeroplasts had been uncoupled by the addition of 30 μg mL−1 trypsin. Sphaeroplasts secreted only the high molecular weight invertase during uncoupling by trypsin. The level of low molecular weight, 'small' invertase in the soluble internal pool was found to be elevated by over fivefold, and the membrane-associated pool was found to contain low molecular weight invertase in addition to intermediate molecular weight invertase, after 1.5 h of trypsin treatment. Purified plasma membranes from trypsin-treated sphaeroplasts had no detectable mannan synthetase activity. On the basis of these and previous findings, a working hypothesis wherein invertase is synthesized on the internal surface of the plasma membrane and glycosylated during its transit to the external surface is presented.

scholarly journals Production of plasminogen activator by established cell lines of mouse origin.

1977 ◽  
Vol 73 (1) ◽  
pp. 47-55 ◽  
Author(s):  
D B Rifkin ◽  
R Pollack
Keyword(s):  
Plasminogen Activator ◽  
Cell Lines ◽  
3T3 Cells ◽  
Established Cell Lines ◽  
Embryo Cultures ◽  
Established Cell ◽  
Swiss 3T3 ◽  
Swiss 3T3 Cell ◽  
Transformed Cell Lines ◽  
3T3 Cell Lines

The correlation between malignant transformation and increased plasminogen activator synthesis has been studied in a variety of established cell lines. In contrast to the behavior of secondary mouse embryo cultures, which always show increased fibrinolytic activity when transformed, no such correlation was found within the BALB/c 3T3 line and its transformed derivatives. Cell lines were established from tumors initiated in BALB/c mice by several transformed cell lines. These lines were generally found to contain no more plasminogen activator than the cells used for inoculation. A correlation was found between transformation and plasminogen activator synthesis within Swiss 3T3 cell lines. However, the correlation was not maintained by serum revertants of transformed Swiss 3T3 cells.

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