scholarly journals Prolonged inhibition of 5‐ HT 3 receptors by palonosetron results from surface receptor inhibition rather than inducing receptor internalization

2013 ◽  
Vol 169 (6) ◽  
pp. 1252-1262 ◽  
Author(s):  
J Daniel Hothersall ◽  
Christopher Moffat ◽  
Christopher N Connolly
Keyword(s):  
Receptor Internalization ◽  
Receptor Inhibition ◽  
Surface Receptor

Down-regulation of Drosophila Egf-r mRNA levels following hyperactivated receptor signaling

Development ◽  
1994 ◽  
Vol 120 (9) ◽  
pp. 2593-2600 ◽  
Author(s):  
M.A. Sturtevant ◽  
J.W. O'Neill ◽  
E. Bier
Keyword(s):  
Mrna Stability ◽  
Egf Receptor ◽  
Receptor Internalization ◽  
Ras Signaling ◽  
Mrna Levels ◽  
Down Regulation ◽  
Feedback Mechanisms ◽  
Receptor Complexes ◽  
Surface Receptor ◽  
Receptor Pool

Internalization of ligand-receptor complexes is a well-documented mechanism for limiting the duration and magnitude of a signaling event. In the case of the EGF-Receptor (EGF-R), exposure to EGF or TGF-alpha results in internalization of up to 95% of the surface receptor pool within 5 minutes of exposure to ligand. In this report, we show that levels of Drosophila Egf-r mRNA are strongly down-regulated in epidermal cells likely to have recently undergone high levels of EGF-R signaling. The cells in which Egf-r mRNA levels are down-regulated express the rhomboid gene, which is thought to locally amplify EGF-R signaling. Widespread Egf-r mRNA down-regulation can be induced by ubiquitous expression of rhomboid or by eliminating the Gap1 gene. These results suggest that cells engaged in intense EGF-R/RAS signaling limit the duration of the signal through a combination of short-acting negative feedback mechanisms such as receptor internalization followed by a longer lasting reduction in receptor transcript levels. Control of Egf-r mRNA levels by altering transcription or mRNA stability is a new tier of regulation to be considered in analysis of EGF-R signaling during development.

Calcium signaling in endothelia: cellular heterogeneity and receptor internalization

1992 ◽  
Vol 263 (5) ◽  
pp. C1029-C1039 ◽  
Author(s):  
W. H. Weintraub ◽  
P. A. Negulescu ◽  
T. E. Machen
Keyword(s):  
Endothelial Cells ◽  
Time Course ◽  
Second Messenger ◽  
Receptor Internalization ◽  
Cellular Heterogeneity ◽  
Vascular Perfusion ◽  
Vasoactive Factors ◽  
Ratio Imaging ◽  
Intracellular Ca ◽  
Surface Receptor

The vasoactive factors thrombin, bradykinin (BK), and ATP are released in response to tissue damage and inflammation and act on endothelium to modulate vascular perfusion. We have investigated the second messenger response of endothelium activated by these agonists and, in particular, the mechanism of desensitization to BK. Fura-2 fluorescence ratio imaging of calf pulmonary artery endothelial cells (CPAE) revealed 5- to 10-fold increases on intracellular Ca (Cai) in response to these agents. Maximal doses caused Cai to increase from 52 to 248 nM (thrombin), 556 nM (BK), and 643 nM (ATP). Agonists elicited a rapid (within 30 s) increase of Cai due to release of Ca from intracellular stores followed by a secondary elevation of Cai dependent on entry of external Ca. The temporal characteristics of the Cai responses to all agonists were heterogeneous from cell to cell, and, interestingly, repeated stimulation gave identical signature responses from individual cells, although the amplitude of the Cai response decreased to thrombin and especially bradykinin but not for ATP. This decrease was agonist specific because ATP elicited large increases of Cai after thrombin or BK desensitization. Maximal desensitization was obtained with BK applied for 5-10 min followed by a rest of < 10 min before restimulation. Although desensitization primarily reduced the elevation of Cai due to the release of the internal store, entry of extracellular Ca was also reduced. Cells responded heterogeneously to desensitization in that those with prominent extracellular Ca entry responded most strongly upon a second stimulation with BK. Because desensitized cells still responded to ATP with an increase of Cai, the desensitization was controlled at a step prior to the activation of phospholipase C. Desensitization occurred by a reduction of BK receptor number; a 10-min BK pretreatment reduced [3H]BK binding to receptors by 70% (from 14,600 receptors/cell, Km = 5 nM, to 5,300). As surface receptor numbers decreased, internalized receptors increased as assayed by an acetic acid wash. The time course of the receptor internalization was similar to the decrease in Cai response to BK. We conclude that the vasoactive agonists thrombin, BK, and ATP increase the second messenger Cai in endothelial cells and that a desensitized Cai response occurs with BK, but not with ATP, due to downregulation and endocytosis of the BK receptor.

scholarly journals Ligand-mediated internalization, recycling, and downregulation of the epidermal growth factor receptor in vivo.

1989 ◽  
Vol 109 (6) ◽  
pp. 2741-2749 ◽  
Author(s):  
W H Lai ◽  
P H Cameron ◽  
I Wada ◽  
J J Doherty ◽  
D G Kay ◽  
...  
Keyword(s):  
Body Weight ◽  
Western Blotting ◽  
Egf Receptor ◽  
Growth Factor Receptor ◽  
Receptor Occupancy ◽  
Liver Parenchyma ◽  
Receptor Internalization ◽  
Scatchard Analysis ◽  
Surface Receptor

EGF receptor internalization, recycling,a nd downregulation were evaluated in liver parenchyma as a function of increasing doses of injected EGF. The effect of ligand occupancy in vivo on the kinetics and extent of internalization was studied with changes in the receptor content of isolated plasmalemma and endosome fractions evaluated by direct binding, Scatchard analysis, and Western blotting. For all doses of injected EGF, receptor was lost from the plasmalemma and accumulated in endosomes in a time- and dose-dependent fashion. However, at doses of injected EGF equivalent to less than or equal to 50% surface receptor occupancy (i.e., less than or equal to 1 microgram/100 g body weight), receptor levels returned by 120 min to initial values. This return was resistant to cycloheximide and therefore did not represent newly synthesized receptor. Neither was the return due to replenishment by an intracellular pool of low-affinity receptors as such a pool could not be detected by Scatchard analysis or Western blotting. Therefore, receptor return was due to the recycling of previously internalized receptor. At doses of injected EGF greater than 50% receptor occupancy, net receptor loss-i.e., downregulation-was observed by evaluating the receptor content of total particulate fractions of liver homogenates. At the higher saturating doses of injected EGF (5 and 10 micrograms/100 g body weight), the majority of surface receptor content was lost by 15 min and remained low for at least an additional 105 min. As the kinetics of ligand clearance from the circulation and liver parenchyma were similar for all doses of EGF injected, then the ligand-mediated regulation of surface receptor content and downregulation were not a result of a prolonged temporal interaction of ligand with receptor. Rather, the phenomena must be a consequence of the absolute concentrations of EGF interacting with receptor at the cell surface and/or in endosomes.

scholarly journals The Glucagon-like Peptide-2 Receptor C Terminus Modulates β-Arrestin-2 Association but Is Dispensable for Ligand-induced Desensitization, Endocytosis, and G-protein-dependent Effector Activation

2005 ◽  
Vol 280 (23) ◽  
pp. 22124-22134 ◽  
Author(s):  
Jennifer L. Estall ◽  
Jacqueline A. Koehler ◽  
Bernardo Yusta ◽  
Daniel J. Drucker
Keyword(s):  
Cell Surface ◽  
G Protein ◽  
Receptor Expression ◽  
Receptor Internalization ◽  
Cell Surface Receptor ◽  
Receptor Desensitization ◽  
C Terminus ◽  
The Family ◽  
Surface Receptor ◽  
Glucagon Like Peptide

Classic models of receptor desensitization and internalization have been largely based on the behavior of Family A G-protein-coupled receptors (GPCRs). The glucagon-like peptide-2 receptor (GLP-2R) is a member of the Family B glucagon-secretin GPCR family, which exhibit significant sequence and structural differences from the Family A receptors in their intracellular and extracellular domains. To identify structural motifs that regulate GLP-2R signaling and cell surface receptor expression, we analyzed the functional properties of a series of mutant GLP-2Rs. The majority of the C-terminal receptor tail was dispensable for GLP-2-induced cAMP accumulation, ERK1/2 activation, and endocytosis in transfected cells. However, progressive truncation of the C terminus reduced cell surface receptor expression, altered agonist-induced GLP-2R trafficking, and abrogated protein kinase A-mediated heterologous receptor desensitization. Elimination of the distal 21 amino acids of the receptor was sufficient to promote constitutive receptor internalization and prevent agonist-induced recruitment of β-arrestin-2. Site-directed mutagenesis identified specific amino acid residues within the distal GLP-2R C terminus that mediate the stable association with β-arrestin-2. Surprisingly, although the truncated mutant receptors failed to interact with β-arrestin-2, they underwent homologous desensitization and subsequent resensitization with kinetics similar to that observed with the wild-type GLP-2R. Our data suggest that, although the GLP-2R C terminus is not required for coupling to cellular machinery regulating signaling or desensitization, it may serve as a sorting signal for intracellular trafficking. Taken together with the previously demonstrated clathrin and dynamin-independent, lipid-raft-dependent pathways for internalization, our data suggest that GLP-2 receptor signaling has evolved unique structural and functional mechanisms for control of receptor trafficking, desensitization, and resensitization.

scholarly journals Uncoupling between the insulin-receptor cycle and the cellular degradation of the hormone in cultured foetal hepatocytes. Effect of drugs and temperature that inhibit insulin degradation

1987 ◽  
Vol 246 (3) ◽  
pp. 567-573 ◽  
Author(s):  
P Soubigou ◽  
M Ali ◽  
C Plas
Keyword(s):  
Cell Surface ◽  
Insulin Receptor ◽  
Rat Hepatocytes ◽  
Receptor Internalization ◽  
Cell Surface Receptor ◽  
Insulin Degradation ◽  
Receptor Recycling ◽  
Partial Restoration ◽  
Receptor Sites ◽  
Surface Receptor

Sequential changes in the numbers of cell-surface receptors induced by a transitory exposure to insulin in cultured 18-day foetal-rat hepatocytes were investigated in the presence of drugs and at a temperature of 22 degrees C, which inhibit cellular insulin degradation. Chloroquine (70 microM) and monensin (3 microM) did not greatly change the initial rate of internalization of cell-surface receptor sites after exposure to 10 nM-insulin, but led to a steady state after 20 min, which represented 40% of the initial binding, compared with 5 min and 60% in the absence of the drug. Moreover, these drugs strongly decreased the proportion of receptor sites recovered at the cell surface after subsequent removal of the hormone. They were ineffective when insulin was not present. The removal of monensin together with the hormone allowed partial restoration of cell-surface receptor sites and degradation of cell-associated insulin to start again at the initial speed, indicating a reversible effect of the drug. During this phase, the drug concentration-dependence for the two effects showed that receptor recycling was restored with concentrations of monensin not as low as for insulin degradation. The effect of vinblastine (50-100 microM) was similar to that of chloroquine and monensin, whereas no modification in the internalization and recovery processes was observed in the presence of bacitracin concentrations (1-3 mM) that inhibit insulin degradation by 70%. A temperature of 22 degrees C did not prevent the receptor internalization, but had a slowing effect on the recycling process, which appeared to vary in experiments where insulin degradation remained inhibited. The present study shows that the process of insulin degradation mediated by receptor endocytosis is not a prerequisite for insulin-receptor recycling in cultured foetal hepatocytes.

scholarly journals Subcellular Trafficking of the TRH Receptor: Effect of Phosphorylation

2009 ◽  
Vol 23 (9) ◽  
pp. 1466-1478 ◽  
Author(s):  
Brian W. Jones ◽  
Patricia M. Hinkle
Keyword(s):  
Plasma Membrane ◽  
Receptor Trafficking ◽  
Dominant Negative ◽  
Receptor Internalization ◽  
Cell Surface Receptor ◽  
Epitope Tag ◽  
Surface Receptors ◽  
Surface Receptor ◽  
G Protein Coupled ◽  
Trh Receptor

Abstract Activation of the G protein-coupled TRH receptor leads to its phosphorylation and internalization. These studies addressed the fundamental question of whether phosphorylation regulates receptor trafficking or endosomal localization regulates the phosphorylation state of the receptor. Trafficking of phosphorylated and dephosphorylated TRH receptors was characterized using phosphosite-specific antibody after labeling surface receptors with antibody to an extracellular epitope tag. Rab5 and phosphoreceptor did not colocalize at the plasma membrane immediately after TRH addition but overlapped extensively by 15 min. Dominant-negative Rab5-S34N inhibited receptor internalization. Later, phosphoreceptor was in endosomes containing Rab5 and Rab4. Dephosphorylated receptor colocalized with Rab4 but not with Rab5. Dominant-negative Rab4, -5, or -11 did not affect receptor phosphorylation or dephosphorylation, showing that phosphorylation determines localization in Rab4+/Rab5− vesicles and not vice versa. No receptor colocalized with Rab7; a small amount of phosphoreceptor colocalized with Rab11. To characterize recycling, surface receptors were tagged with antibody, or surface receptors containing an N-terminal biotin ligase acceptor sequence were labeled with biotin. Most recycling receptors did not return to the plasma membrane for more than 2 h after TRH was removed, whereas the total cell surface receptor density was largely restored in less than 1 h, indicating that recruited receptors contribute heavily to early repopulation of the plasma membrane.

Expression, function, and localization of the REG cell surface receptor

2001 ◽  
Vol 120 (5) ◽  
pp. A18-A19
Author(s):  
B DIECKGRAEFE ◽  
C HOUCHEN ◽  
H ZHANG
Keyword(s):  
Cell Surface ◽  
Cell Surface Receptor ◽  
Surface Receptor

Defects in insulin-receptor internalization and processing in monocytes of obese subjects and obese NIDDM patients

Diabetes ◽  
1989 ◽  
Vol 38 (12) ◽  
pp. 1579-1584 ◽  
Author(s):  
V. Trischitta ◽  
A. Brunetti ◽  
A. Chiavetta ◽  
L. Benzi ◽  
V. Papa ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Receptor Internalization ◽  
Obese Subjects ◽  
Niddm Patients
Sign in / Sign up

Export Citation Format

Share Document