Turnover of Plasma Membrane During Phagocytosis

1972 ◽  
Vol 11 (2) ◽  
pp. 569-579
Author(s):  
R. J. GOODALL ◽  
Y. F. LAI ◽  
J. E. THOMPSON
Keyword(s):  
Plasma Membrane ◽  
Cytoplasmic Membrane ◽  
De Novo ◽  
Surface Membrane ◽  
Acanthamoeba Castellanii ◽  
De Novo Synthesis ◽  
Cellular Membranes ◽  
Latex Beads ◽  
Specific Radio ◽  
Preferential Synthesis

Levels of radioactive glycine and glycerol incorporated into the plasma membrane of Acanthamoeba castellanii during phagocytosis were determined in order to elucidate how surface membrane expended during this process is replaced. The amoebae were allowed to ingest latex beads in the presence of the labelled membrane precursors and plasma membrane was then isolated and analysed for the presence of radioactivity. The isolated membrane fragments were found to be quite highly labelled. In order to ascertain whether this represented preferential synthesis of plasma membrane in response to phagocytosis, the specific radio-activities of the isolated membrane fractions were compared with those of corresponding particulate homogenates, which were composites of all cellular membranes. Enrichment values calculated in this manner proved to be essentially similar for both phagocytosing and non-phagocytosing amoebae. This indicates that de novo synthesis of plasma membrane is not essential for phagocytosis and in turn suggests that pre-existing cytoplasmic membrane is used to replace surface membrane consumed during ingestion. Presumably the incorporation of membrane precursors that was observed represents molecular turnover that occurs irrespective of phagocytosis.

scholarly journals Intracellular localization and de novo synthesis of FcRIII in human neutrophil granulocytes

Blood ◽  
1990 ◽  
Vol 75 (1) ◽  
pp. 144-151 ◽  
Author(s):  
CR Jost ◽  
TW Huizinga ◽  
R de Goede ◽  
JA Fransen ◽  
PA Tetteroo ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Golgi Complex ◽  
De Novo ◽  
Intracellular Localization ◽  
Human Neutrophils ◽  
Neutrophil Granulocytes ◽  
Metabolic Labeling ◽  
De Novo Synthesis ◽  
Double Labeling ◽  
Microscopic Studies

Abstract Immunoelectron microscopic studies in human neutrophils showed that FcRIII was present on the plasma membrane, in the Golgi complex, and in many small vesicles (120 to 180 nm). FcRIII was not found in specific or azurophilic granules as shown by immunogold double-labeling experiments, visualizing both FcRIII and either lactoferrin (a marker of specific granules) or myeloperoxidase (a marker for azurophilic granules). Because the occurrence of FcRIII in the Golgi complex suggested that biosynthesis of this receptor occurs in these cells, metabolic labeling experiments were performed. Immunoprecipitation of FcRIII from NP-40 lysates of cells labeled with 35S-methionine showed a diffuse 50- to 70-Kd band corresponding with the band noted after immunoprecipitation of FcRIII from surface iodinated cells. These findings show that de novo synthesis of FcRIII occurs in neutrophils and suggest that at least some of the small vesicles containing FcRIII derive from the Golgi complex and thus are involved in transport of newly synthesized FcRIII to the plasma membrane.

The Osmoregulatory System of the Amoeba, Acanthamoeba Castellanii

1972 ◽  
Vol 57 (1) ◽  
pp. 55-76
Author(s):  
R. A. PAL
Keyword(s):  
Plasma Membrane ◽  
Polyethylene Glycol ◽  
Ethylene Glycol ◽  
Surface Membrane ◽  
Acanthamoeba Castellanii ◽  
Sodium Sulphate ◽  
The Body ◽  
Contractile Vacuole ◽  
Body Volume ◽  
Food Vacuoles

1. It is estimated that Acanthamoeba castellanii eliminates a volume of water equal to its body volume in about 15-30 min. About 7% of the vacuolar discharge enters the body by means other than osmosis through the surface membrane. Food vacuoles fusing with the contractile vacuole do not significantly affect the rate of output. 2. Vacuolar output declines with the age of culture so that during the stationary phase of growth it is about half of that during early log phase of growth. 3. The rate of output of the contractile vacuole decreases with an increase of concentration of a non-penetrating solute in the external medium and shows a rectilinear relationship up to 0.07 M concentration. A low residual output after 0.07 M may be due to food vacuoles and pinocytic vacuoles. 4. On the basis of vacuolar output the excess internal osmotic pressure and permeability constant of water has been estimated as 0.07 M non-electrolyte and 0.04µm min-1 atm.-1 respectively. 5. On the basis of vacuolar behaviour it is concluded that the relative permeabilities of the plasma membrane to different solutes follows this order: methyl alcohol > ethylene glycol > urea > glycerol. On certain assumptions the permeability of the plasma membrane to ethylene glycol has been estimated provisionally as 0.107 x 10-16 mol/sec/µm2/mol/l. 6. Vacuolar behaviour suggests that sodium chloride, sodium nitrate, sodium sulphate and potassium chloride, but not magnesium chloride and calcium chloride, pass into the cell freely. 7. Growth of populations of A. castellanii is almost normal in polyethylene glycol 600 up to 0.07 M concentration but in higher concentrations it is low. There are some indications of an increase in volume of A . castellanii in cultures of polyethylene glycol 600 up to 0.07 M concentration, but not in higher concentrations. For amoebae cultured in media containing polyethylene glycol 600 the rate of output of the contractile vacuole declines sharply with an increase of polyethylene glycol 600 up to 0.07 M concentration and then more gradually.

scholarly journals Role of β-arrestin1/ERK MAP kinase pathway in regulating adenosine A1 receptor desensitization and recovery

2010 ◽  
Vol 298 (1) ◽  
pp. C56-C65 ◽  
Author(s):  
Sarvesh Jajoo ◽  
Debashree Mukherjea ◽  
Sunny Kumar ◽  
Sandeep Sheth ◽  
Tejbeer Kaur ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
De Novo ◽  
Fold Increase ◽  
Nuclear Factor Κb ◽  
Activator Protein 1 ◽  
De Novo Synthesis ◽  
Ductus Deferens ◽  
A1 Receptor ◽  
Interfering Rna

Exposure of cells to adenosine receptor (AR) agonists leads to receptor uncoupling from G proteins and downregulation of the A1AR. The receptor levels on the cell surface generally recover on withdrawal of the agonist, because of either translocation of the sequestered A1AR back to plasma membrane or de novo synthesis of A1AR. To examine the mechanism(s) underlying A1AR downregulation and recovery, we treated ductus deferens tumor (DDT1 MF-2) cells with the agonist R-phenylisopropyladenosine ( R-PIA) and showed a decrease in membrane A1AR levels by 24 h, which was associated with an unexpected 11-fold increase in A1AR mRNA. Acute exposure of these cells to R-PIA resulted in a rapid translocation of β-arrestin1 to the plasma membrane. Knockdown of β-arrestin1 by short interfering RNA (siRNA) blocked R-PIA-mediated downregulation of the A1AR, suppressed R-PIA-dependent ERK1/2 and activator protein-1 (AP-1) activity, and reduced the induction of A1AR mRNA. Withdrawal of the agonist after a 24-h exposure resulted in rapid recovery of plasma membrane A1AR. This was dependent on the de novo protein synthesis and on the activity of ERK1/2 but independent of β-arrestin1 and nuclear factor-κB. Together, these data suggest that exposure to A1AR agonist stimulates ERK1/2 activity via β-arrestin1, which subserves receptor uncoupling and downregulation, in addition to the induction of A1AR expression. We propose that such a pathway ensures both the termination of the agonist signal and recovery by priming the cell for rapid de novo synthesis of A1AR once the drug is terminated.

scholarly journals EXOCYTOSIS OF LATEX BEADS DURING THE ENCYSTMENT OF ACANTHAMOEBA

1972 ◽  
Vol 52 (1) ◽  
pp. 117-130 ◽  
Author(s):  
James R. Stewart ◽  
Robert A. Weisman
Keyword(s):  
Cell Wall ◽  
Plasma Membrane ◽  
Cyst Wall ◽  
Actinomycin D ◽  
Acanthamoeba Castellanii ◽  
Ultrastructural Analysis ◽  
Synthetase Activity ◽  
Wall Formation ◽  
Latex Beads ◽  
In Cells

Cells of Acanthamoeba castellanii (Neff) are known to form mature cysts characterized by a cellulose-containing cell wall when transferred to a nonnutrient medium. Amebas which engulfed latex beads before encystment formed mature cysts essentially devoid of bead material. The encystment of bead-containing cells appeared to be similar to that of control cells since no important differences between the two were observed with respect to cellular levels of glycogen or protein, cellulose synthetase activity, the amount of cyst wall polysaccharide formed, or the percentage of cysts formed. Actinomycin D and cycloheximide inhibited encystment as well as bead expulsion. Ultrastructural analysis revealed that the beads, which initially were contained in phagocytic vesicles, were released from the cell by fusion of vesicular membranes with the plasma membrane. Exocytosis was observed in cells after 3 hr of encystment, with most of the beads being lost before cyst wall formation. Each bead-containing vesicle involved in expulsion was conspicuously demarcated by an area of concentrated cytoplasm, which was more homogeneously granular than the surrounding cytoplasm. Beads were not observed in the cytoplasm of mature cysts but were occasionally found in the cyst wall.

scholarly journals Intracellular localization and de novo synthesis of FcRIII in human neutrophil granulocytes

Blood ◽  
1990 ◽  
Vol 75 (1) ◽  
pp. 144-151
Author(s):  
CR Jost ◽  
TW Huizinga ◽  
R de Goede ◽  
JA Fransen ◽  
PA Tetteroo ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Golgi Complex ◽  
De Novo ◽  
Intracellular Localization ◽  
Human Neutrophils ◽  
Neutrophil Granulocytes ◽  
Metabolic Labeling ◽  
De Novo Synthesis ◽  
Double Labeling ◽  
Microscopic Studies

Immunoelectron microscopic studies in human neutrophils showed that FcRIII was present on the plasma membrane, in the Golgi complex, and in many small vesicles (120 to 180 nm). FcRIII was not found in specific or azurophilic granules as shown by immunogold double-labeling experiments, visualizing both FcRIII and either lactoferrin (a marker of specific granules) or myeloperoxidase (a marker for azurophilic granules). Because the occurrence of FcRIII in the Golgi complex suggested that biosynthesis of this receptor occurs in these cells, metabolic labeling experiments were performed. Immunoprecipitation of FcRIII from NP-40 lysates of cells labeled with 35S-methionine showed a diffuse 50- to 70-Kd band corresponding with the band noted after immunoprecipitation of FcRIII from surface iodinated cells. These findings show that de novo synthesis of FcRIII occurs in neutrophils and suggest that at least some of the small vesicles containing FcRIII derive from the Golgi complex and thus are involved in transport of newly synthesized FcRIII to the plasma membrane.

scholarly journals De Novo Synthesis of Plasma Membrane and Tonoplast Polypeptides of Barley Roots during Short-Term K+ Deprivation

1992 ◽  
Vol 100 (3) ◽  
pp. 1269-1276 ◽  
Author(s):  
Mala Fernando ◽  
Jarnail Mehroke ◽  
Anthony D. M. Glass
Keyword(s):  
Plasma Membrane ◽  
De Novo ◽  
De Novo Synthesis ◽  
Short Term

Characterization of Monocyte-Associated Factor V

1993 ◽  
Vol 70 (02) ◽  
pp. 273-280 ◽  
Author(s):  
Janos Kappelmayer ◽  
Satya P Kunapuli ◽  
Edward G Wyshock ◽  
Robert W Colman
Keyword(s):  
Monoclonal Antibody ◽  
Light Chain ◽  
Peripheral Blood ◽  
De Novo ◽  
Factor V ◽  
Blood Monocytes ◽  
De Novo Synthesis ◽  
Hep G2 ◽  
Hep G2 Cells ◽  
Peripheral Blood Monocytes

SummaryWe demonstrate that in addition to possessing binding sites for intact factor V (FV), unstimulated peripheral blood monocytes also express activated factor V (FVa) on their surfaces. FVa was identified on the monocyte surface by monoclonal antibody B38 recognizing FVa light chain and by human oligoclonal antibodies H1 (to FVa light chain) and H2 (to FVa heavy chain) using immunofluorescence microscopy and flow cytometry. On Western blots, partially cleaved FV could be identified as a 220 kDa band in lysates of monocytes. In addition to surface expression of FVa, monocytes also contain intracellular FV as detected only after permeabilization by Triton X-100 by monoclonal antibody B10 directed specifically to the Cl domain not present in FVa. We sought to determine whether the presence of FV in peripheral blood monocytes is a result of de novo synthesis.Using in situ hybridization, no FV mRNA could be detected in monocytes, while in parallel control studies, factor V mRNA was detectable in Hep G2 cells and CD18 mRNA in monocytes. In addition, using reverse transcriptase and the polymerase chain reaction, no FV mRNA was detected in mononuclear cells or in U937 cells, but mRNA for factor V was present in Hep G2 cells using the same techniques. These data suggest that FV is present in human monocytes, presumably acquired by binding of plasma FV, and that the presence of this critical coagulation factor is not due to de novo synthesis.

Platelets Stimulate Thromboplastin Synthesis in Human Endothelial Cells

1983 ◽  
Vol 49 (02) ◽  
pp. 069-072 ◽  
Author(s):  
U L H Johnsen ◽  
T Lyberg ◽  
K S Galdal ◽  
H Prydz
Keyword(s):  
Endothelial Cells ◽  
De Novo ◽  
Umbilical Vein ◽  
Time Dependent ◽  
De Novo Synthesis ◽  
Human Endothelial Cells ◽  
Tumor Promotor ◽  
Coagulation Assay ◽  
Platelet Aggregates ◽  
Umbilical Vein Endothelial Cells

SummaryHuman umbilical vein endothelial cells in culture synthesize thromboplastin upon stimulation with phytohaemagglutinin (PHA) or the tumor promotor 12-O-tetradecanoyl-phorbol-13-acetate (TPA). The thromboplastin activity is further strongly enhanced in a time dependent reaction by the presence of gel-filtered platelets or platelet aggregates. This effect was demonstrable at platelet concentrations lower than those normally found in plasma, it may thus be of pathophysiological relevance. The thromboplastin activity increased with increasing number of platelets added. Cycloheximide inhibited the increase, suggesting that de novo synthesis of the protein component of thromboplastin, apoprotein III, is necessary.When care was taken to remove monocytes no thromboplastin activity and no apoprotein HI antigen could be demonstrated in suspensions of gel-filtered platelets, platelets aggregated with thrombin or homogenized platelets when studied with a coagulation assay and an antibody neutralization technique.

DE NOVO SYNTHESIS OF STEROIDS BY THE TESTES OF THE HUMAN FOETUS AT MIDGESTATION

1971 ◽  
Vol 68 (1_Supplb) ◽  
pp. S135 ◽  
Author(s):  
R. S. Mathur ◽  
N. Wiqvist ◽  
E. Diczfalusy
Keyword(s):  
De Novo ◽  
De Novo Synthesis ◽  
Human Foetus
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