scholarly journals Phenylarsine oxide-induced increase in alveolar macrophage surface receptors: evidence for fusion of internal receptor pools with the cell surface.

1985 ◽  
Vol 101 (1) ◽  
pp. 121-129 ◽  
Author(s):  
J Kaplan ◽  
D M Ward ◽  
H S Wiley
Keyword(s):  
Cell Surface ◽  
Ligand Binding ◽  
Gradient Centrifugation ◽  
Buoyant Density ◽  
Receptor Activity ◽  
Enzyme Release ◽  
Cell Integrity ◽  
Phenylarsine Oxide ◽  
Surface Receptor ◽  
Receptor Number

Rabbit alveolar macrophages which were treated at 0 degrees C with phenylarsine oxide and then incubated at 37 degrees C for 10 min exhibited a two- to threefold increase in surface receptor activity for macroglobulin.protease complexes, diferric transferrin, and mannose-terminal glycoproteins. Analysis of the concentration-dependence of ligand binding indicated that changes in ligand-binding activity were due to changes in receptor number rather than alterations in ligand-receptor affinity. Surface receptor number could also be increased by treatment of cells with three other sulfhydryl reagents, N-ethylmaleimide, p-chloromercurobenzoate, and iodoacetic acid. The increase in receptor activity was maximal after 10 min and decreased over the next hour. This decrease in cell-associated receptor activity was due to the release of large membrane vesicles which demonstrated a uniform buoyant density by isopycnic sucrose gradient centrifugation. Treatment of cells with phenylarsine oxide did not decrease the cellular content of lactate dehydrogenase or beta-galactosidase, indicating that cell integrity was maintained and lysosomal enzyme release did not occur. Our studies indicate that phenylarsine oxide treatment in the presence of extracellular Ca2+ results in the fusion of receptor-containing vesicles with the cell surface.

scholarly journals Mitogenic agents induce redistribution of transferrin receptors from internal pools to the cell surface

1986 ◽  
Vol 238 (3) ◽  
pp. 721-728 ◽  
Author(s):  
D McV Ward ◽  
J Kaplan
Keyword(s):  
Growth Factor ◽  
Cell Surface ◽  
Transferrin Receptor ◽  
Transferrin Receptors ◽  
Serum Free Medium ◽  
Free Medium ◽  
Serum Free ◽  
Surface Receptor ◽  
Receptor Number ◽  
Receptor Distribution

Incubation of serum-growth HeLa cells in serum-free medium causes a rapid (t1/2 3 min) 30-60% decrease in the binding of 125I-diferric transferrin to the cell surface. Addition of fetal bovine serum to cells in serum-free medium results in a rapid (t1/2 3 min) and concentration-dependent increase in binding activity. The loss or gain in ligand binding is a result of changes in surface receptor number rather than an alteration in ligand-receptor affinity. A variety of hormones (insulin, insulin-like growth factor, interleukin 1 and platelet-derived factor) were found to mimic the effect of serum on receptor number. The alteration in surface receptor number was found to be calcium-dependent. Changes in surface receptor number were independent of either receptor biosynthetic rate or the absolute cellular content of receptors. The effect of insulin or serum on Hela cell transferrin receptor distribution was unaffected by the presence of transferrin, demonstrating that receptor distribution in this cell type is ligand-independent. The ability of serum or insulin to modify surface transferrin receptor number was also observed in mouse L-cells, human skin fibroblasts, and J774 macrophage tumour cells. However, transferrin receptors on K562 and Epstein-Barr virus-transformed human lymphoblasts were unaltered by these agents. The quantities of receptors whose distribution is predominantly on the surface (i.e. epidermal growth factor or low density lipoprotein receptor) were unaltered by addition of the mitogenic agents. These results extend our previous studies [H.S. Wiley & J. Kaplan (1984) Proc. Natl. Acad. Sci. U.S.A. 81, 7456-7460] demonstrating that mitogenic agents can induce redistribution of receptor pools in selected cell types.

Ligand Binding to the Cell-Surface Receptor for Reovirus Type 3 Alters Schwann Cell Growth and Function

1990 ◽  
Vol 605 (1 Myelination a) ◽  
pp. 412-415
Author(s):  
JEFFREY A. COHEN ◽  
WILLIAM V. WILLIAMS ◽  
KENNETH F. MORE ◽  
HARISH SEHDEV ◽  
JAMES G. DAVIES ◽  
...  
Keyword(s):  
Cell Growth ◽  
Schwann Cell ◽  
Cell Surface ◽  
Ligand Binding ◽  
Cell Surface Receptor ◽  
Reovirus Type ◽  
Surface Receptor ◽  
And Function ◽  
Type 3

scholarly journals Fates of endocytosed somatostatin sst2 receptors and associated agonists

1998 ◽  
Vol 336 (2) ◽  
pp. 291-298 ◽  
Author(s):  
Jennifer A. KOENIG ◽  
Rejbinder KAUR ◽  
Iain DODGEON ◽  
J. Michael EDWARDSON ◽  
Patrick P. A. HUMPHREY
Keyword(s):  
Cell Surface ◽  
Somatostatin Receptor ◽  
Somatostatin Receptors ◽  
Receptor Recycling ◽  
Extracellular Medium ◽  
Main Pathway ◽  
Surface Receptor ◽  
Receptor Number ◽  
Agonist Ligands ◽  
Somatostatin 14

Somatostatin agonists are rapidly and efficiently internalized with the somatostatin sst2 receptor. The fate of internalized agonists and receptors is of critical importance because the rate of ligand recycling back to the cell surface can limit the amount of radioligand accumulated inside the cells, whereas receptor recycling might be of vital importance in providing the cell surface with dephosphorylated, resensitized receptors. Furthermore the accumulation of radioisotope-conjugated somatostatin agonists inside cancer cells resulting from receptor-mediated internalization has been used as a treatment for cancers that overexpress somatostatin receptors. In the present study, radio-iodinated agonists at the sst2 somatostatin receptor were employed to allow quantitative analysis of the fate of endocytosed agonist. After endocytosis, recycling back to the cell surface was the main pathway for both 125I-labelled somatostatin-14 (SRIF-14) and the more stable agonist 125I-labelled cyclo(N-Me-Ala-Tyr-d-Trp-Lys-Abu-Phe) (BIM-23027; Abu stands for aminobutyric acid), accounting for 75–85% of internalized ligand when re-endocytosis of radioligand was prevented. We have shown that there is a dynamic cycling of both somatostatin agonist ligands and receptors between the cell surface and internal compartments both during agonist treatment and after surface-bound agonist has been removed, unless steps are taken to prevent the re-activation of receptors by recycled agonist. Internalization leads to increased degradation of 125I-labelled SRIF-14 but not 125I-labelled BIM-23027. The concentration of recycled agonist accumulating in the extracellular medium was sufficient to re-activate the receptor, as measured both by the inhibition of forskolin-stimulated adenylate cyclase and the recovery of surface receptor number after internalization.

scholarly journals Effects of Food Mastication on Rat Parotid Gland Adrenergic and Cholinergic Cell Surface Receptors

1993 ◽  
Vol 4 (3) ◽  
pp. 591-597 ◽  
Author(s):  
Dorthea A. Johnson ◽  
H. Lee Cardenas
Keyword(s):  
Cell Surface ◽  
Parotid Gland ◽  
Ligand Binding ◽  
Cell Surface Receptor ◽  
Receptor Density ◽  
Gland Weight ◽  
Surface Receptor ◽  
Muscarinic Cholinergic ◽  
Cholinergic Cell ◽  
Pelleted Diet

Adult male rats were fed diets of differing texture (liquid, powder, standard pelleted, or bulk pelleted) to alter food mastication. After 2 weeks, the parotid glands were removed and adrenergic and muscarinic-cholinergic cell surface receptor density (fM bound/mg protein) and ligand binding dissociation constants (Kd in nM) were determined by radioligand binding techniques on a crude membrane fraction. For all diets, gland weight increased as the requirement for food mastication increased (i.e., liquid < powder < standard pelleted < bulk pelleted). Among the diets, neither beta-two nor alpha-two receptor density was altered. Beta-one receptor density was directly related to dietary mastication. Compared with the standard pelleted diet, beta-one receptor density was reduced 21% for the liquid diet and 7% for the powdered diet; for the bulk-pelleted diet, beta-one receptor density was increased 11%. With respect to alpha-one receptor density, it was not affected by the liquid or powdered diet when compared with the standard pelleted diet, but alpha-one receptors were increased 14% with the bulk-pelleted diet. Muscarinic-cholinergic receptor density for the liquid diet fed rats was 27% less than for the standard-pelleted diet; powdered diet did not differ from standard pelleted, while that for the bulk-pelleted diet was increased 6%. With but minor exceptions, ligand binding affinity was unaffected by the changes in diet texture. These studies demonstrate that dietary mastication as well as affecting parotid gland weight, cell size, and saliva production also influences autonomic cell surface receptor density.

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