scholarly journals Differential internalization and processing of atrial-natriuretic-factor B and C receptor in PC12 cells

1991 ◽  
Vol 276 (2) ◽  
pp. 493-497 ◽  
Author(s):  
A Rathinavelu ◽  
G E Isom
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Pc12 Cells ◽  
Atrial Natriuretic Factor ◽  
Receptor Subtype ◽  
Receptor Subtypes ◽  
Surface Binding ◽  
Down Regulation ◽  
Natriuretic Factor ◽  
Atrial Natriuretic

PC12 cells express two atrial-natriuretic-factor-(ANF)-receptor subtypes with molecular masses of 130,000 (B receptor) and 70,000 (C receptor). The B-receptor subtype constitutes 65% of the cell-surface receptor population, and the remaining 35% are C receptors as determined by saturation binding studies in the presence of C-ANF, a C-receptor-selective analogue. ANF-(99-126)-peptide [ANF(99-126)], which can bind to both B- and C-receptor subtypes, was rapidly internalized into the cells after incubation at 37 degrees C. Internalization of 125I-ANF(99-126) was used as an index of the receptor-mediated endocytosis and to quantify receptor internalization. In the presence of a saturating concentration of C-ANF, receptor-mediated internalization of 125I-ANF(99-126) was reduced by 24%, indicating B receptor mediate 76% of ligand internalization. Incubation of cells with 10 microM-ANF at 37 degrees C down-regulated both receptor subtypes as reflected by decreased surface binding. Time-dependent studies suggest that B- and C-receptor subtypes undergo differential down-regulation. Incubation of down-regulated cells for 120 min in ANF-free medium produced a recovery of 35% of the original cell-surface binding. Affinity cross-linking of 125I-ANF to the receptors on the plasma membrane in re-incubated (up-regulated) cells demonstrated expression of predominantly the B-receptor subtype. Monensin blocked 72% of receptor up-regulation, whereas cycloheximide inhibited 43%, suggesting an active recycling mechanism involved in mediating up-regulation of the B receptors. The present study demonstrates a rapid internalization and intracellular recycling mechanism for B receptors in PC12 cells. C receptors also undergo internalization and down-regulation, but recycling of this receptor subtype into the plasma membrane occurs at a lower rate and to a lesser extent than is the case for the B receptor.

scholarly journals Kinetic analysis of internalization, recycling and redistribution of atrial natriuretic factor-receptor complex in cultured vascular smooth-muscle cells. Ligand-dependent receptor down-regulation

1992 ◽  
Vol 288 (1) ◽  
pp. 55-61 ◽  
Author(s):  
K N Pandey
Keyword(s):  
Smooth Muscle ◽  
Cell Surface ◽  
Atrial Natriuretic Factor ◽  
Dependent Manner ◽  
Receptor Complex ◽  
Down Regulation ◽  
Surface Receptors ◽  
Natriuretic Factor ◽  
Metabolic Degradation ◽  
Atrial Natriuretic

The kinetics of internalization, sequestration and metabolic degradation of atrial natriuretic factor (ANF)-receptor complex were studied in rat thoracic aortic smooth-muscle (RTASM) cells. These parameters were directly determined by measuring 125I-ANF binding to total, intracellular and cell-surface receptors. Pretreatment of cells with the lysosomotropic agent chloroquine and the energy depleter dinitrophenol led to an increase in the intracellular 125I-ANF radioactivity. After 60 min incubation at 37 degrees C, cell-associated 125I-ANF radioactivity fell rapidly in chloroquine-treated cells (> 85%) compared with the controls (< 45%). 125I-ANF radioactivity increased to a peak of 65% of the initial level within 15 min in chloroquine-treated cells compared with only 22% in the control cells. During the initial incubation period at 37 degrees C, chloroquine inhibited the release of both intact and degraded 125I-ANF in a time-dependent manner. However, at later incubation times, the effect of chloroquine was diminished and release of both degraded and intact ligand was resumed. Extracellular unlabelled ANF did not affect the release of degraded 125I-ANF but it accelerated the release of intact ANF by a retroendocytotic mechanism. After the endocytosis, about 30-40% of ANF receptors were restored to the cell surface from the internalized pool of receptors. The restoration was blocked by chloroquine or dinitrophenol but not by cycloheximide. Exposure of RTASM cells to unlabelled ANF resulted in a time- and concentration-dependent loss of ANF receptors. Unlabelled ANF (10 nM) induced a loss of more than 52% of 125I-ANF binding, and a complete loss occurred at micromolar concentrations. It is inferred that ANF-induced down-regulation of its receptor resulted primarily from an increased rate in internalization and metabolic degradation of ligand-receptor complex by receptor-mediated endocytotic mechanisms.

Glomerular and vascular atrial natriuretic factor receptors in adrenalectomized rats

1989 ◽  
Vol 256 (6) ◽  
pp. R1250-R1257
Author(s):  
V. Cachofeiro ◽  
E. L. Schiffrin ◽  
M. Cantin ◽  
R. Garcia
Keyword(s):  
Atrial Natriuretic Factor ◽  
Biological Response ◽  
Plasma Renin ◽  
Receptor Subtype ◽  
Receptor Subtypes ◽  
Receptor Density ◽  
Apparent Lack ◽  
Natriuretic Factor ◽  
Vascular Receptor ◽  
Atrial Natriuretic

The renal and vascular responses to atrial natriuretic factor (ANF) and glomerular and vascular ANF receptors were studied in adrenalectomized (ADR) rats with or without deoxycorticosterone (DOC) or dexamethasone (Dexa) replacement therapy. As expected, adrenalectomy elicited hypotension, hemoconcentration, and increased plasma renin activity, but no changes in plasma levels of either ANF-(1-98) or ANF-(99-126) were detected. Dexa treatment decreased both ANF-(1-98) and ANF-(99-126), whereas DOC treatment increased only ANF-(1-98). The acute renal response to ANF and furosemide was reduced in ADR rats and partially restored either by steroid replacement or by raising blood pressure. The blunted natriuretic response to ANF in ADR rats was associated with an increased density of glomerular receptors. Norepinephrine-precontracted vascular strips from ADR rats were more sensitive to ANF (ED50: 1.7 x 10(-8) M) than those from sham-operated animals (ED50: 1.5 x 10(-7) M). However, vascular ANF receptor density in mesenteric vessels from ADR animals was decreased. Dexa treatment restored vascular response to that observed in sham-operated animals without a concomitant change in vascular receptor density. Because the presence of guanylate cyclase-coupled and noncoupled ANF receptor subtypes have been described in different tissues, we conclude that the apparent lack of correlation between the biological response to ANF and total binding of ANF to glomeruli or mesenteric artery membranes in ADR rats may be in part caused by a differential regulation of both receptor subtype populations.

scholarly journals Atrial natriuretic factor and C-type natriuretic peptide induce retraction of human thyrocytes in monolayer culture via guanylyl cyclase receptors

2002 ◽  
Vol 173 (1) ◽  
pp. 169-176 ◽  
Author(s):  
DF Sellitti ◽  
C Lagranha ◽  
G Perrella ◽  
F Curcio ◽  
SQ Doi
Keyword(s):  
Natriuretic Peptide ◽  
Natriuretic Peptides ◽  
Atrial Natriuretic Factor ◽  
Kinase Inhibitor ◽  
Human Thyroid ◽  
Thyroid Cell ◽  
Receptor Subtypes ◽  
Natriuretic Factor ◽  
Human Thyroid Cell ◽  
Atrial Natriuretic

The natriuretic peptides signal through three receptor subtypes, of which two (NPR-A and NPR-B) are membrane-bound guanylyl cyclases for which the principal ligands are respectively atrial natriuretic factor (ANF) and C-type natriuretic peptide (CNP). In the human thyroid cell, a third receptor, NPR-C, has been implicated in the regulation of thyroglobulin, but functional roles for NPR-A and NPR-B have not yet been defined. In the present study we used RT-PCR to identify transcripts of all three receptor subtypes, both in human thyroid and in HTU-5 cells, a long-term culture of thyroid-derived cells. Both ANF and CNP induced a twofold increase in intracellular cGMP content in HTU-5 cells. Morphologic changes (a significant increase in cells of the retracted phenotype) were observed in ANF- and CNP-treated cells within 3 and 5 h of treatment respectively. Significant increases in retracted cell number were induced by ANF and CNP, but not the NPR-C-specific ring-deleted ANF analog, C-ANF(4-23), during a 15-day treatment. All three natriuretic peptides, however, induced a small (15-20%) but significant (P<0 small middle dot001) increase in DNA content per well. The stable analog of cGMP, 8-bromo-cGMP (8-BrcGMP; 1 mM), also increased the number of retracted HTU-5 cells, and was equipotent with the cAMP analog, 8-BrcAMP, in this effect. The cGMP-dependent protein kinase inhibitor, KT5823, however, had no significant effect on the ANF-induced increase in numbers of retracted cells. These results suggest that the actions of NPR-A and NPR-B, functional receptors in the human thyroid cell, may in part be mediated by cGMP-induced alterations in the cytoskeleton.

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