Internalization of the rat AT<sub>1a</sub> and AT<sub>1b</sub> receptors: pharmacological and functional requirements

Conchon, Sophie; Monnot, Catherine; Teutsch, B; Corvol, Pierre; Clauser, Éric

doi:10.1016/0014-5793(94)00703-9

Cited by 91 publications

(69 citation statements)

References 41 publications

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“…Receptor Internalization Assays-Radioligand binding measurements of AT 1A R internalization were assessed as described previously (20). Briefly, HEK 293 cells transiently transfected to overexpress FLAG-AT 1A R in the absence and presence of Rab5a constructs were washed with serum-free MEM with 10 mM Hepes, pH 7.4, and then were incubated at 37°C in the same medium containing 100 nM Ang II for 1 h. The cells were then washed in cold MEM containing 10 mM Hepes and were incubated in acid wash solution (90 mM NaCl, 50 mM sodium citrate, pH 5.0) for 20 min to dissociate bound ligand.…”

Section: Methodsmentioning

confidence: 99%

Rab5 Association with the Angiotensin II Type 1A Receptor Promotes Rab5 GTP Binding and Vesicular Fusion

Seachrist¹,

Laporte²,

Dale³

et al. 2002

Journal of Biological Chemistry

129

123

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Section: Methodsmentioning

confidence: 99%

Rab5 Association with the Angiotensin II Type 1A Receptor Promotes Rab5 GTP Binding and Vesicular Fusion

Seachrist¹,

Laporte²,

Dale³

et al. 2002

Journal of Biological Chemistry

129

123

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“…42,68), but for other receptors a clear separation between the two processes is evident (69). In extreme cases, the phosphorylation and internalization of angiotensin AT1 or choleocystokinin A receptors can be stimulated by ligands that do not activate signaling through the receptor (19,20). Mutant GPCRs have also been constructed in which agonist-induced G protein signaling is abolished while processes leading to receptor internalization are preserved (e.g.…”

Section: Table II Relative Efficacy For Opioid Agonist Inhibition Of mentioning

confidence: 99%

“…However, there is no evidence that phosphorylation by either PKC or calmodulin-dependent kinase II contributes to MOP internalization. GPCR internalization is not simply a secondary consequence of receptor activation by agonists but can be affected differentially by different ligands independently of their efficacy of coupling to G proteins, and for some receptors even apparent antagonists can induce receptor internalization (19,20). MOP agonists appear to have differential capacities to promote receptor internalization.…”

mentioning

confidence: 99%

Opioid Agonists Have Different Efficacy Profiles for G Protein Activation, Rapid Desensitization, and Endocytosis of Mu-opioid Receptors

Borgland

Connor

Osborne

et al. 2003

Journal of Biological Chemistry

144

179

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The differential ability of various -opioid receptor (MOP) agonists to induce rapid receptor desensitization and endocytosis of MOP could arise simply from differences in their efficacy to activate G proteins or, alternatively, be due to differential capacity for activation of other signaling processes. We used AtT20 cells stably expressing a low density of FLAG-tagged MOP to compare the efficacies of a range of agonists to 1) activate G proteins using inhibition of calcium channel currents (I Ca ) as a reporter before and after inactivation of a fraction of receptors by ␤-chlornaltrexamine, 2) produce rapid, homologous desensitization of I Ca inhibition, and 3) internalize receptors. Relative efficacies determined for G protein coupling were [Tyr-D-Ala-Gly-MePhe-Glyol]enkephalin (DAMGO) (1) > methadone (0.98) > morphine (0.58) > pentazocine (0.15). The same rank order of efficacies for rapid desensitization of MOP was observed, but greater concentrations of agonist were required than for G protein activation. By contrast, relative efficacies for promoting endocytosis of MOP were DAMGO (1) > methadone (0.59) > > morphine (0.07) > pentazocine (0.03). These results indicate that the efficacy of opioids to produce activation of G proteins and rapid desensitization is distinct from their capacity to internalize -opioid receptors but that, contrary to some previous reports, morphine can produce rapid, homologous desensitization of MOP.Tolerance to the analgesic and other effects of opioid drugs, such as morphine, undermines their use in long term treatment (1). Although analgesic tolerance is likely to be a complex phenomenon, an understanding of how -opioid (MOP) 1 receptors are regulated by opioid agonists will lead to important insights into this phenomenon. MOPs are similar to many other G protein-coupled receptors (GPCR) in that they undergo desensitization within several minutes of stimulation by agonists (2-4), and continued agonist exposure results in removal of receptors from the cell surface (5-7). MOP phosphorylation is increased as a consequence of agonist exposure, leading to a commonly held assumption that receptor phosphorylation is essential for MOP desensitization and internalization (5, 8 -10). The mechanism that may be responsible for uncoupling MOP from G protein activation and then promoting receptor sequestration is as follows: phosphorylation of the agonist occupied MOP by a G protein receptor kinase (GRK), subsequent binding of ␤-arrestins to the phosphorylated receptor, and removal of MOP from the cell surface via a clathrin-dependent process (11-15). The enhanced analgesic potency of morphine and diminished analgesic tolerance in ␤-arrestin2 knockout mice suggest that the capacity of opioid agonists to cause receptor desensitization and endocytosis is one of the key cellular mechanisms underlying tolerance (16). Phosphorylation of MOP by protein kinase C (PKC) or calmodulin-dependent kinase II can also reduce the capacity of MOP to activate G proteins (8,17), also contributing to opioid tole...

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“…[ 3 H]-angiotensin II bound initially to the cell surface receptors, followed by rapid internalization of the angiotensin II-receptor complexes. Surface-bound and internalized radioligand could be separated from each other: the former was readily released by mild acid treatment (see Methods) of the cells and the latter, acidresistant binding, could be solubilized using 0.1 M NaOH (Crozat et al, 1986;Conchon et al, 1994;Hein et al, 1997). Table 1, addition of 0.1% BSA in the incubation medium decreased the IC 50 values of candesartan (2.7 fold), EXP3174 (4.7 fold) and losartan (3.0 fold) but not of irbesartan and angiotensin II.…”

Section: E Ect Of Selective At 1 Receptor Antagonists On Ip Accumulationmentioning

confidence: 99%

Distinction between surmountable and insurmountable selective AT₁ receptor antagonists by use of CHO‐K1 cells expressing human angiotensin II AT₁ receptors

Vanderheyden¹,

Fierens²,

Backer³

et al. 1999

British J Pharmacology

147

106

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1 CHO-K1 cells that were stably transfected with the gene for the human AT 1 receptor (CHO-AT 1 cells) were used for pharmacological studies of non-peptide AT 1 receptor antagonists. 2 In the presence of 10 mM LiCl, angiotensin II caused a concentration-dependent and long-lasting increase of inositol phosphates accumulation with an EC 50 of 3.4 nM. No angiotensin II responses are seen in wild-type CHO-K1 cells. 5 Preincubation with the insurmountable antagonist candesartan decreased the maximal angiotensin II induced inositol phosphate accumulation up to 94% and, concomitantly, decreased the maximal binding capacity of the cell surface receptors. These inhibitory e ects were halfmaximal for 0.6 nM candesartan and were attenuated by simultaneous preincubation with 1 mM losartan indicating a syntopic action of both antagonists. 6 Losartan caused a parallel rightward shift of the angiotensin II concentration-response curves and did not a ect the maximal binding capacity. EXP3174 (the active metabolite of losartan) and irbesartan showed a mixed-type behavior in both functional and binding studies. 7 Reversal of the inhibitory e ect was slower for candesartan as compared with EXP3174 and irbesartan and it was almost instantaneous for losartan, suggesting that the insurmountable nature of selective AT 1 receptor antagonists in functional studies was related to their long-lasting inhibition.

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Internalization of the rat AT_1a and AT_1b receptors: pharmacological and functional requirements

Cited by 91 publications

References 41 publications

Rab5 Association with the Angiotensin II Type 1A Receptor Promotes Rab5 GTP Binding and Vesicular Fusion

Rab5 Association with the Angiotensin II Type 1A Receptor Promotes Rab5 GTP Binding and Vesicular Fusion

Opioid Agonists Have Different Efficacy Profiles for G Protein Activation, Rapid Desensitization, and Endocytosis of Mu-opioid Receptors

Distinction between surmountable and insurmountable selective AT₁ receptor antagonists by use of CHO‐K1 cells expressing human angiotensin II AT₁ receptors

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Internalization of the rat AT1a and AT1b receptors: pharmacological and functional requirements

Cited by 91 publications

References 41 publications

Rab5 Association with the Angiotensin II Type 1A Receptor Promotes Rab5 GTP Binding and Vesicular Fusion

Rab5 Association with the Angiotensin II Type 1A Receptor Promotes Rab5 GTP Binding and Vesicular Fusion

Opioid Agonists Have Different Efficacy Profiles for G Protein Activation, Rapid Desensitization, and Endocytosis of Mu-opioid Receptors

Distinction between surmountable and insurmountable selective AT1 receptor antagonists by use of CHO‐K1 cells expressing human angiotensin II AT1 receptors

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Internalization of the rat AT_1a and AT_1b receptors: pharmacological and functional requirements

Distinction between surmountable and insurmountable selective AT₁ receptor antagonists by use of CHO‐K1 cells expressing human angiotensin II AT₁ receptors