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Kenakin T. Bias translation: The final frontier? Br J Pharmacol 2024; 181:1345-1360. [PMID: 38424747 DOI: 10.1111/bph.16335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Revised: 10/24/2023] [Accepted: 10/31/2023] [Indexed: 03/02/2024] Open
Abstract
Biased signalling is a natural result of GPCR allosteric function and should be expected from any and all synthetic and natural agonists. Therefore, it may be encountered in all agonist discovery projects and must be considered as a beneficial (or possible detrimental) feature of new candidate molecules. While bias is detected easily, the synoptic nature of GPCR signalling makes translation of simple in vitro bias to complex in vivo systems problematic. The practical outcome of this is a difficulty in predicting the therapeutic value of biased signalling due to the failure of translation of identified biased signalling to in vivo agonism. This is discussed in this review as well as some new ways forward to improve this translation process and better exploit this powerful pharmacologic mechanism.
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Affiliation(s)
- Terry Kenakin
- Department of Pharmacology, University of North Carolina, School of Medicine, Chapel Hill, North Carolina, USA
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2
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Surve S, Watkins SC, Sorkin A. EGFR-RAS-MAPK signaling is confined to the plasma membrane and associated endorecycling protrusions. J Cell Biol 2021; 220:212639. [PMID: 34515735 PMCID: PMC8563293 DOI: 10.1083/jcb.202107103] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 08/21/2021] [Accepted: 08/24/2021] [Indexed: 12/16/2022] Open
Abstract
The subcellular localization of RAS GTPases defines the operational compartment of the EGFR-ERK1/2 signaling pathway within cells. Hence, we used live-cell imaging to demonstrate that endogenous KRAS and NRAS tagged with mNeonGreen are predominantly localized to the plasma membrane. NRAS was also present in the Golgi apparatus and a tubular, plasma-membrane derived endorecycling compartment, enriched in recycling endosome markers (TERC). In EGF-stimulated cells, there was essentially no colocalization of either mNeonGreen-KRAS or mNeonGreen-NRAS with endosomal EGFR, which, by contrast, remained associated with endogenous Grb2-mNeonGreen, a receptor adaptor upstream of RAS. ERK1/2 activity was diminished by blocking cell surface EGFR with cetuximab, even after most ligand-bound, Grb2-associated EGFRs were internalized. Endogenous mCherry-tagged RAF1, an effector of RAS, was recruited to the plasma membrane, with subsequent accumulation in mNG-NRAS–containing TERCs. We propose that a small pool of surface EGFRs sustain signaling within the RAS-ERK1/2 pathway and that RAS activation persists in TERCs, whereas endosomal EGFR does not significantly contribute to ERK1/2 activity.
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Affiliation(s)
- Sachin Surve
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Simon C Watkins
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Alexander Sorkin
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA
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3
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MicroRNA-dependent inhibition of PFN2 orchestrates ERK activation and pluripotent state transitions by regulating endocytosis. Proc Natl Acad Sci U S A 2020; 117:20625-20635. [PMID: 32788350 DOI: 10.1073/pnas.2002750117] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Profilin2 (PFN2) is a target of the embryonic stem cell (ESC)-enriched miR-290 family of microRNAs (miRNAs) and an actin/dynamin-binding protein implicated in endocytosis. Here we show that the miR-290-PFN2 pathway regulates many aspects of ESC biology. In the absence of miRNAs, PFN2 is up-regulated in ESCs, with a resulting decrease in endocytosis. Reintroduction of miR-290, knockout of Pfn2, or disruption of the PFN2-dynamin interaction domain in miRNA-deficient cells reverses the endocytosis defect. The reduced endocytosis is associated with impaired extracellular signal-regulated kinase (ERK) signaling, delayed ESC cell cycle progression, and repressed ESC differentiation. Mutagenesis of the single canonical conserved 3' UTR miR-290-binding site of Pfn2 or overexpression of the Pfn2 open reading frame alone in otherwise wild-type cells largely recapitulates these phenotypes. Taken together, these findings define an axis of posttranscriptional control, endocytosis, and signal transduction that is important for ESC proliferation and differentiation.
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4
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Ghosh E, Srivastava A, Baidya M, Kumari P, Dwivedi H, Nidhi K, Ranjan R, Dogra S, Koide A, Yadav PN, Sidhu SS, Koide S, Shukla AK. A synthetic intrabody-based selective and generic inhibitor of GPCR endocytosis. NATURE NANOTECHNOLOGY 2017; 12:1190-1198. [PMID: 28967893 PMCID: PMC5722207 DOI: 10.1038/nnano.2017.188] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 08/13/2017] [Indexed: 05/06/2023]
Abstract
Beta-arrestins (βarrs) critically mediate desensitization, endocytosis and signalling of G protein-coupled receptors (GPCRs), and they scaffold a large number of interaction partners. However, allosteric modulation of their scaffolding abilities and direct targeting of their interaction interfaces to modulate GPCR functions selectively have not been fully explored yet. Here we identified a series of synthetic antibody fragments (Fabs) against different conformations of βarrs from phage display libraries. Several of these Fabs allosterically and selectively modulated the interaction of βarrs with clathrin and ERK MAP kinase. Interestingly, one of these Fabs selectively disrupted βarr-clathrin interaction, and when expressed as an intrabody, it robustly inhibited agonist-induced endocytosis of a broad set of GPCRs without affecting ERK MAP kinase activation. Our data therefore demonstrate the feasibility of selectively targeting βarr interactions using intrabodies and provide a novel framework for fine-tuning GPCR functions with potential therapeutic implications.
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Affiliation(s)
- Eshan Ghosh
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Ashish Srivastava
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Mithu Baidya
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Punita Kumari
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Hemlata Dwivedi
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Kumari Nidhi
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Ravi Ranjan
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Shalini Dogra
- CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Akiko Koide
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York 10016, USA
- Department of Medicine, New York University School of Medicine, New York 10016, USA
| | - Prem N Yadav
- CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Sachdev S Sidhu
- Department of Molecular Genetics, University of Toronto, Ontario MSS1A8, Canada
| | - Shohei Koide
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York 10016, USA
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York 10016, USA
| | - Arun K Shukla
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
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5
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Kenakin T. A Scale of Agonism and Allosteric Modulation for Assessment of Selectivity, Bias, and Receptor Mutation. Mol Pharmacol 2017; 92:414-424. [PMID: 28679508 DOI: 10.1124/mol.117.108787] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2017] [Accepted: 06/12/2017] [Indexed: 11/22/2022] Open
Abstract
An index of agonism is described that can be used to quantify agonist receptor selectivity, bias, cell-based agonism, and the effects of receptor mutation on signaling. The parameter is derived from agonist concentration-response curves and comprises the maximal response to the agonist (max) and the EC50 in the form of Δlog(max/EC50). This parameter is derived from equations describing agonists as positive allosteric facilitators of receptor-signaling protein interaction. A similar index is also derived to quantify the potentiating effects of positive allosteric modulators, which can be used to quantify in situ positive allosteric modulator activity in vivo. These indices lend themselves to statistical analysis and are system-independent in that the effects of the system processing of agonist response and differences in assay sensitivity and receptor expression are cancelled. The various applications of the Δlog(max/EC50) scale are described for each pharmacologic application.
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Affiliation(s)
- Terry Kenakin
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina
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Abstract
INTRODUCTION The availability of different functional pharmacological assays has revealed that agonists for receptors that are pleiotropically coupled to multiple signaling pathways in the cell can emphasize signals to some pathways over others, i.e. can be biased toward certain signals. This, in turn, opens the possibility that molecules can be made to emphasize favorable signals, de-emphasize harmful signals or selectively block the ability of the natural agonist to produce unfavorable signals. Areas covered: This paper discusses the mechanism of biased signaling, the possible therapeutic implications of this effect, methods to quantify and measure bias and the current literature describing the translation of biased measure in vitro to in vivo systems. In addition, the challenges of exploiting this mechanism for therapy are outlined. Expert opinion: While this mechanism is well established and ubiquitous in pharmacology and easily measured in vitro, there are theoretical and practical hurdles to overcome to the fruitful utilization of signaling bias in therapeutic systems. There will be failures in the translation of biased molecules in vivo because of these challenges but hopefully also success and these latter translations hopefully will provide guidance in exploiting this effect further for therapy.
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Affiliation(s)
- Terry Kenakin
- a Department of Pharmacology , University of North Carolina School of Medicine , Chapel Hill , NC , USA
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Irannejad R, Tsvetanova NG, Lobingier BT, von Zastrow M. Effects of endocytosis on receptor-mediated signaling. Curr Opin Cell Biol 2015; 35:137-43. [PMID: 26057614 PMCID: PMC4529812 DOI: 10.1016/j.ceb.2015.05.005] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 05/18/2015] [Accepted: 05/20/2015] [Indexed: 01/31/2023]
Abstract
Cellular mechanisms of membrane traffic and signal transduction are deeply interconnected. The present review discusses how membrane trafficking in the endocytic pathway impacts receptor-mediated signaling. Examples of recent progress are highlighted, focusing on the endocytosis-signaling nexus in mammals.
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Affiliation(s)
- Roshanak Irannejad
- Departments of Psychiatry and of Cellular & Molecular Pharmacology, University of California, San Francisco School of Medicine, 600 16th Street, San Francisco CA 94158-2140 USA
| | - Nikoleta G. Tsvetanova
- Departments of Psychiatry and of Cellular & Molecular Pharmacology, University of California, San Francisco School of Medicine, 600 16th Street, San Francisco CA 94158-2140 USA
| | - Braden T. Lobingier
- Departments of Psychiatry and of Cellular & Molecular Pharmacology, University of California, San Francisco School of Medicine, 600 16th Street, San Francisco CA 94158-2140 USA
| | - Mark von Zastrow
- Departments of Psychiatry and of Cellular & Molecular Pharmacology, University of California, San Francisco School of Medicine, 600 16th Street, San Francisco CA 94158-2140 USA
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Kenakin T. The Effective Application of Biased Signaling to New Drug Discovery. Mol Pharmacol 2015; 88:1055-61. [PMID: 26138073 DOI: 10.1124/mol.115.099770] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Accepted: 07/02/2015] [Indexed: 01/14/2023] Open
Abstract
The ability of agonists to selectively activate some but not all signaling pathways linked to pleiotropically signaling receptors has opened the possibility of obtaining molecules that emphasize beneficial signals, de-emphasize harmful signals, and concomitantly deemphasize harmful signals while blocking the harmful signals produced by endogenous agonists. The detection and quantification of biased effects is straightforward, but two important factors should be considered in the evaluation of biased effects in drug discovery. The first is that efficacy, and not bias, determines whether a given agonist signal will be observed; bias only dictates the relative concentrations at which agonist signals will appear when they do appear. Therefore, a Cartesian coordinate system plotting relative efficacy (on a scale of Log relative Intrinsic Activities) as the ordinates and Log(bias) as the abscissae is proposed as a useful tool in evaluating possible biased molecules for progression in discovery programs. Second, it should be considered that the current scales quantifying bias limit this property to the allosteric vector (ligand/receptor/coupling protein complex) and that whole-cell processing of this signal can completely change measured bias from in vitro predictions.
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Affiliation(s)
- Terry Kenakin
- Department of Pharmacology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina
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TNF-α augmented Porphyromonas gingivalis invasion in human gingival epithelial cells through Rab5 and ICAM-1. BMC Microbiol 2014; 14:229. [PMID: 25179218 PMCID: PMC4159534 DOI: 10.1186/s12866-014-0229-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 08/19/2014] [Indexed: 01/12/2023] Open
Abstract
Background Tumor necrosis factor alpha (TNF-α) plays a central role in the initiation and maintenance of immune responses to periodontopathic bacteria. However, excess TNF-α leads to dysregulated immune responses and progression of periodontitis. Porphyromonas gingivalis (P. gingivalis) invades gingival epithelial cells and then multiplies and survives for a long period. Additionally, increment of TNF-α in periodontal sites is associated with a high prevalence of gram-negative anaerobes such as P. gingivalis. However, it has not been determined whether TNF-α affects invasion of P. gingivalis in periodontal tissues. Results We examined the effect of TNF-α on invasion of P. gingivalis in gingival epithelial cells and clarified the mechanism by which TNF-α augments invasion of P. gingivalis. Invasion of P. gingivalis into Ca9-22 cells was augmented by stimulation with TNF-α and it was inhibited by treatment with an antibody to TNF receptor-1. TNF-α increased production of ICAM-1, and P. gingivalis invasion was inhibited by an antibody to ICAM-1 in Ca9-22 cells. Silencing of Rab5 mRNA inhibited P. gingivalis invasion. Furthermore, the JNK inhibitor SP600125 inhibited invasion of P. gingivalis and also decreased the active form of Rab5 in Ca9-22 cells. Conclusion TNF-α augments invasion of P. gingivalis in human gingival epithelial cells through increment of ICAM-1 and activation of Rab5. These phenomena may contribute to persistent infection of P. ginigvalis and prolongation of immune responses in periodontal tissues. Electronic supplementary material The online version of this article (doi:10.1186/s12866-014-0229-z) contains supplementary material, which is available to authorized users.
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Macey TA, Bobeck EN, Suchland KL, Morgan MM, Ingram SL. Change in functional selectivity of morphine with the development of antinociceptive tolerance. Br J Pharmacol 2014; 172:549-61. [PMID: 24666417 DOI: 10.1111/bph.12703] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 03/14/2014] [Accepted: 03/18/2014] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND AND PURPOSE Opioids, such as morphine, are the most effective treatment for pain but their efficacy is diminished with the development of tolerance following repeated administration. Recently, we found that morphine activated ERK in opioid-tolerant but not in naïve rats, suggesting that morphine activation of μ-opioid receptors is altered following repeated morphine administration. Here, we have tested the hypothesis that μ-opioid receptor activation of ERK in the ventrolateral periaqueductal gray (vlPAG) is dependent on dynamin, a protein implicated in receptor endocytosis. EXPERIMENTAL APPROACH Rats were made tolerant to repeated microinjections of morphine into the vlPAG. The effects of dynamin on ERK activation and antinociception were assessed by microinjecting myristoylated dominant-negative dynamin peptide (Dyn-DN) or a scrambled control peptide into the vlPAG. Microinjection of a fluorescent dermorphin analogue (DERM-A594) into the vlPAG was used to monitor μ-opioid receptor internalization. KEY RESULTS Morphine did not activate ERK and Dyn-DN administration had no effect on morphine-induced antinociception in saline-pretreated rats. In contrast, morphine-induced ERK activation in morphine-pretreated rats that was blocked by Dyn-DN administration. Dyn-DN also inhibited morphine antinociception. Finally, morphine reduced DERM-A594 internalization only in morphine-tolerant rats indicating that μ-opioid receptors were internalized and unavailable to bind DERM-A594. CONCLUSIONS AND IMPLICATIONS Repeated morphine administration increased μ-opioid receptor activation of ERK signalling via a dynamin-dependent mechanism. These results demonstrate that the balance of agonist signalling to G-protein and dynamin-dependent pathways is altered, effectively changing the functional selectivity of the agonist-receptor complex. LINKED ARTICLES This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2.
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Affiliation(s)
- T A Macey
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR, USA
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Bourassa P, Tudashki HB, Pineyro G, Grandbois M, Gendron L. Label-free monitoring of μ-opioid receptor-mediated signaling. Mol Pharmacol 2014; 86:138-49. [PMID: 24874699 DOI: 10.1124/mol.114.093450] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
In this study, we used a combination of traditional signaling investigation approaches, bioluminescence resonance energy transfer (BRET) biosensors, and the label-free approach surface plasmon resonance (SPR) spectroscopy to monitor the signaling cascades of the μ-opioid receptor (MOP). In human embryonic kidney cells stably expressing a Flag-tagged version of human MOP, we compared the signals triggered by the noninternalizing and internalizing MOP agonists morphine and DAMGO (Tyr-D-Ala-Gly-N-methyl-Phe-Gly-ol), respectively. We studied three major and well described components of MOP signaling: receptor internalization, G protein coupling, and activation of extracellular signal-regulated kinase ERK1/ERK2. Our results show that morphine and DAMGO display different profiles of receptor internalization and a similar ability to trigger the phosphorylation of ERK1/ERK2. Our SPR analyses revealed that morphine and DAMGO evoke similar SPR signatures and that Gαi, cAMP-dependent pathways, and ERK1/ERK2 have key roles in morphine- and DAMGO-mediated signaling. Most interestingly, we found that the so-called MOP neutral antagonists CTOP (D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH(2)), naloxone, and naltrexone behave like partial agonists. Even more intriguing, BRET experiments indicate that CTAP (D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH(2)) induces similar conformational changes as naltrexone at the Gαi-βγ interface, whereas it appears as an inverse agonist based on its SPR response thus indicating distinct signaling mechanisms for the two ligands. Taken together, our results support the usefulness of label-free methods such as SPR to study whole-cell responses and signaling cascades triggered by G protein-coupled receptors and complement the conventional approaches by revealing cellular responses that would have been otherwise undetectable.
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Affiliation(s)
- Philippe Bourassa
- Départements de Physiologie et Biophysique (P.B., L.G.), Pharmacologie (H.B.T., M.G.), and Psychiatrie (G.P.), Centre de Recherche du CHU Ste-Justine (H.B.T, G.P.), Université de Montréal, Montreal, Quebec, Canada; Institut de Pharmacologie de Sherbrooke (M.G., L.G.), Centre de Recherche du CHU Sherbrooke (P.B., M.G., L.G.), Université de Sherbrooke (P.B., M.G., L.G.), Sherbrooke, Quebec, Canada; and Quebec Pain Research Network, Quebec City, Quebec, Canada (L.G.)
| | - Hanieh Bagheri Tudashki
- Départements de Physiologie et Biophysique (P.B., L.G.), Pharmacologie (H.B.T., M.G.), and Psychiatrie (G.P.), Centre de Recherche du CHU Ste-Justine (H.B.T, G.P.), Université de Montréal, Montreal, Quebec, Canada; Institut de Pharmacologie de Sherbrooke (M.G., L.G.), Centre de Recherche du CHU Sherbrooke (P.B., M.G., L.G.), Université de Sherbrooke (P.B., M.G., L.G.), Sherbrooke, Quebec, Canada; and Quebec Pain Research Network, Quebec City, Quebec, Canada (L.G.)
| | - Graciela Pineyro
- Départements de Physiologie et Biophysique (P.B., L.G.), Pharmacologie (H.B.T., M.G.), and Psychiatrie (G.P.), Centre de Recherche du CHU Ste-Justine (H.B.T, G.P.), Université de Montréal, Montreal, Quebec, Canada; Institut de Pharmacologie de Sherbrooke (M.G., L.G.), Centre de Recherche du CHU Sherbrooke (P.B., M.G., L.G.), Université de Sherbrooke (P.B., M.G., L.G.), Sherbrooke, Quebec, Canada; and Quebec Pain Research Network, Quebec City, Quebec, Canada (L.G.)
| | - Michel Grandbois
- Départements de Physiologie et Biophysique (P.B., L.G.), Pharmacologie (H.B.T., M.G.), and Psychiatrie (G.P.), Centre de Recherche du CHU Ste-Justine (H.B.T, G.P.), Université de Montréal, Montreal, Quebec, Canada; Institut de Pharmacologie de Sherbrooke (M.G., L.G.), Centre de Recherche du CHU Sherbrooke (P.B., M.G., L.G.), Université de Sherbrooke (P.B., M.G., L.G.), Sherbrooke, Quebec, Canada; and Quebec Pain Research Network, Quebec City, Quebec, Canada (L.G.)
| | - Louis Gendron
- Départements de Physiologie et Biophysique (P.B., L.G.), Pharmacologie (H.B.T., M.G.), and Psychiatrie (G.P.), Centre de Recherche du CHU Ste-Justine (H.B.T, G.P.), Université de Montréal, Montreal, Quebec, Canada; Institut de Pharmacologie de Sherbrooke (M.G., L.G.), Centre de Recherche du CHU Sherbrooke (P.B., M.G., L.G.), Université de Sherbrooke (P.B., M.G., L.G.), Sherbrooke, Quebec, Canada; and Quebec Pain Research Network, Quebec City, Quebec, Canada (L.G.)
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Jaremko KM, Thompson NL, Reyes BAS, Jin J, Ebersole B, Jenney CB, Grigson PS, Levenson R, Berrettini WH, Van Bockstaele EJ. Morphine-induced trafficking of a mu-opioid receptor interacting protein in rat locus coeruleus neurons. Prog Neuropsychopharmacol Biol Psychiatry 2014; 50:53-65. [PMID: 24333843 PMCID: PMC3928604 DOI: 10.1016/j.pnpbp.2013.12.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 11/26/2013] [Accepted: 12/05/2013] [Indexed: 12/14/2022]
Abstract
Opiate addiction is a devastating health problem, with approximately 2million people currently addicted to heroin or non-medical prescription opiates in the United States alone. In neurons, adaptations in cell signaling cascades develop following opioid actions at the mu opioid receptor (MOR). A novel putative target for intervention involves interacting proteins that may regulate trafficking of MOR. Morphine has been shown to induce a re-distribution of a MOR-interacting protein Wntless (WLS, a transport molecule necessary for secretion of neurotrophic Wnt proteins), from cytoplasmic to membrane compartments in rat striatal neurons. Given its opiate-sensitivity and its well-characterized molecular and cellular adaptations to morphine exposure, we investigated the anatomical distribution of WLS and MOR in the rat locus coeruleus (LC)-norepinephrine (NE) system. Dual immunofluorescence microscopy was used to test the hypothesis that WLS is localized to noradrenergic neurons of the LC and that WLS and MOR co-exist in common LC somatodendritic processes, providing an anatomical substrate for their putative interactions. We also hypothesized that morphine would influence WLS distribution in the LC. Rats received saline, morphine or the opiate agonist [d-Ala2, N-Me-Phe4, Gly-ol5]-enkephalin (DAMGO), and tissue sections through the LC were processed for immunogold-silver detection of WLS and MOR. Statistical analysis showed a significant re-distribution of WLS to the plasma membrane following morphine treatment in addition to an increase in the proximity of gold-silver labels for MOR and WLS. Following DAMGO treatment, MOR and WLS were predominantly localized within the cytoplasmic compartment when compared to morphine and control. In a separate cohort of rats, brains were obtained from saline-treated or heroin self-administering male rats for pulldown co-immunoprecipitation studies. Results showed an increased association of WLS and MOR following heroin exposure. As the LC-NE system is important for cognition as well as decisions underlying substance abuse, adaptations in WLS trafficking and expression may play a role in modulating MOR function in the LC and contribute to the negative sequelae of opiate exposure on executive function.
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Affiliation(s)
- Kellie M Jaremko
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States
| | - Nicholas L Thompson
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States
| | - Beverly A S Reyes
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States.
| | - Jay Jin
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033, United States
| | - Brittany Ebersole
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033, United States
| | - Christopher B Jenney
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA 17033, United States
| | - Patricia S Grigson
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA 17033, United States
| | - Robert Levenson
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033, United States
| | - Wade H Berrettini
- Department of Psychiatry, Center for Neurobiology and Behavior, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, United States
| | - Elisabeth J Van Bockstaele
- Department of Pharmacology and Physiology, Drexel University College of Medicine, Philadelphia, PA 19102, United States
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Narita M, Imai S, Nakamura A, Ozeki A, Asato M, Rahmadi M, Sudo Y, Hojo M, Uezono Y, Devi LA, Kuzumaki N, Suzuki T. Possible involvement of prolonging spinal µ-opioid receptor desensitization in the development of antihyperalgesic tolerance to µ-opioids under a neuropathic pain-like state. Addict Biol 2013; 18:614-22. [PMID: 21812868 DOI: 10.1111/j.1369-1600.2011.00354.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In the present study, we investigated the possible development of tolerance to the antihyperalgesic effect of µ-opioid receptor (MOR) agonists under a neuropathic pain-like state. Repeated treatment with fentanyl, but not morphine or oxycodone, produced a rapid development of tolerance to its antihyperalgesic effect in mice with sciatic nerve ligation. Like the behavioral study, G-protein activation induced by fentanyl was significantly reduced in membranes obtained from the spinal cord of nerve-ligated mice with in vivo repeated injection of fentanyl. In β-endorphin-knockout mice with nerve ligation, developed tolerance to the antihyperalgesic effect of fentanyl was abolished, and reduced G-protein activation by fentanyl after nerve ligation with fentanyl was reversed to the normal level. The present findings indicate that released β-endorphin within the spinal cord may be implicated in the rapid development of tolerance to fentanyl under a neuropathic pain-like state.
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Affiliation(s)
- Minoru Narita
- Department of Toxicology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, Japan.
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14
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Anselmi L, Jaramillo I, Palacios M, Huynh J, Sternini C. Ligand-induced μ opioid receptor internalization in enteric neurons following chronic treatment with the opiate fentanyl. J Neurosci Res 2013; 91:854-60. [PMID: 23553842 DOI: 10.1002/jnr.23214] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 01/11/2013] [Accepted: 01/14/2013] [Indexed: 12/19/2022]
Abstract
Morphine differs from most opiates its poor ability to internalize μ opioid receptors (μORs). However, chronic treatment with morphine produces adaptational changes at the dynamin level, which enhance the efficiency of acute morphine stimulation to promote μOR internalization in enteric neurons. This study tested the effect of chronic treatment with fentanyl, a μOR-internalizing agonist, on ligand-induced endocytosis and the expression of the intracellular trafficking proteins, dynamin and β-arrestin, in enteric neurons using organotypic cultures of the guinea pig ileum. In enteric neurons from guinea pigs chronically treated with fentanyl, μOR immunoreactivity was predominantly at the cell surface after acute exposure to morphine with a low level of μOR translocation, slightly higher than in neurons from naïve animals. This internalization was not due to morphine's direct effect, because it was also observed in neurons exposed to medium alone. By contrast, D-Ala2-N-Me-Phe4-Gly-ol5-enkephalin (DAMGO), a potent μOR-internalizing agonist, induced pronounced and rapid μOR endocytosis in enteric neurons from animals chronically treated with fentanyl or from naïve animals. Chronic fentanyl treatment did not alter dynamin or β-arrestin expression. These findings indicate that prolonged activation of μORs with an internalizing agonist such as fentanyl does not enhance the ability of acute morphine to trigger μOR endocytosis or induce changes in intracellular trafficking proteins, as observed with prolonged activation of μORs with a poorly internalizing agonist such as morphine. Cellular adaptations induced by chronic opiate treatment might be ligand dependent and vary with the agonist efficiency to induce receptor internalization.
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Affiliation(s)
- Laura Anselmi
- CURE Digestive Diseases Research Center, Digestive Diseases Division, Los Angeles, CA 90073, USA
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15
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Saleki M, Colgin N, Kirby JA, Cobb SL, Ali S. Evaluation of two cyclic di-peptides as inhibitors of CCL2 induced chemotaxis. MEDCHEMCOMM 2013. [DOI: 10.1039/c3md00043e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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16
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Dang VC, Chieng BC, Christie MJ. Prolonged Stimulation of μ-Opioid Receptors Produces β-Arrestin-2-Mediated Heterologous Desensitization of α2-Adrenoceptor Function in Locus Ceruleus Neurons. Mol Pharmacol 2012; 82:473-80. [DOI: 10.1124/mol.112.079350] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
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17
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Whistler JL. Examining the role of mu opioid receptor endocytosis in the beneficial and side-effects of prolonged opioid use: from a symposium on new concepts in mu-opioid pharmacology. Drug Alcohol Depend 2012; 121:189-204. [PMID: 22226706 PMCID: PMC4224378 DOI: 10.1016/j.drugalcdep.2011.10.031] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 10/20/2011] [Accepted: 10/22/2011] [Indexed: 12/31/2022]
Abstract
Opioid drugs remain the gold standard for the treatment of severe pain, both acute/post-surgical and chronic. However, the utility of opioid drugs for the treatment of chronic pain is compromised by the development of analgesic tolerance which, in turn, leads to dose-escalation and increased likelihood of dangerous side effects, including dependence. Consequently, there remains resistance among clinicians and the general population to using opiates for pain management because of risk of "addiction." These fears are not unwarranted. More than 2.5 million people begin abusing opioid painkillers each year, and prescription opioid abuse is now the second most common type of illegal drug use after marijuana. Some abusers become dependent due to recreational use of prescription painkillers. However, many abusers are among the 40 million people suffering from chronic pain, and developed dependence while using the drugs for legitimate purposes. Both of these trends highlight the need to develop opioid therapeutics with a reduced liability to cause tolerance, dependence and addiction. Identifying the ideal properties of opioid drugs that would retain analgesia but reduce these side-effects has been a goal of my laboratory for more than a decade. During this time, we have proposed the novel hypothesis that opioid drugs that promote desensitization, endocytosis and recycling of the mu-opioid-receptor (MOR) will retain analgesic efficacy, but will have a reduced liability to cause tolerance, dependence and addiction. We have generated substantial data, both pharmacological and genetic to suggest that our hypothesis is a valid one. These data are summarized in this review.
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Affiliation(s)
- Jennifer L. Whistler
- Department of Neurology, Ernest Gallo Clinic and Research Center, University of California, San Francisco, 5858 Horton St. Suite 200, Emeryville, CA 94608, tel: 510 985-3127, fax: 510 985-3101,
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18
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Wang J, Yuan W, Li MD. Genes and pathways co-associated with the exposure to multiple drugs of abuse, including alcohol, amphetamine/methamphetamine, cocaine, marijuana, morphine, and/or nicotine: a review of proteomics analyses. Mol Neurobiol 2011; 44:269-86. [PMID: 21922273 DOI: 10.1007/s12035-011-8202-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2011] [Accepted: 08/31/2011] [Indexed: 10/17/2022]
Abstract
Drug addiction is a chronic neuronal disease. In recent years, proteomics technology has been widely used to assess the protein expression in the brain tissues of both animals and humans exposed to addictive drugs. Through this approach, a large number of proteins potentially involved in the etiology of drug addictions have been identified, which provide a valuable resource to study protein function, biochemical pathways, and networks related to the molecular mechanisms underlying drug dependence. In this article, we summarize the recent application of proteomics to profiling protein expression patterns in animal or human brain tissues after the administration of alcohol, amphetamine/methamphetamine, cocaine, marijuana, morphine/heroin/butorphanol, or nicotine. From available reports, we compiled a list of 497 proteins associated with exposure to one or more addictive drugs, with 160 being related to exposure to at least two abused drugs. A number of biochemical pathways and biological processes appear to be enriched among these proteins, including synaptic transmission and signaling pathways related to neuronal functions. The data included in this work provide a summary and extension of the proteomics studies on drug addiction. Furthermore, the proteins and biological processes highlighted here may provide valuable insight into the cellular activities and biological processes in neurons in the development of drug addiction.
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Affiliation(s)
- Ju Wang
- Department of Psychiatry and Neurobehavioral Sciences, University of Virginia, Charlottesville, VA 22911, USA
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19
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Codd EE, Mabus JR, Murray BS, Zhang SP, Flores CM. Dynamic Mass Redistribution as a Means to Measure and Differentiate Signaling via Opioid and Cannabinoid Receptors. Assay Drug Dev Technol 2011; 9:362-72. [DOI: 10.1089/adt.2010.0347] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Ellen E. Codd
- Johnson & Johnson Pharmaceutical Research & Development, Spring House, Pennsylvania
| | - John R. Mabus
- Johnson & Johnson Pharmaceutical Research & Development, Spring House, Pennsylvania
| | - Brian S. Murray
- Johnson & Johnson Pharmaceutical Research & Development, Spring House, Pennsylvania
| | - Sui-Po Zhang
- Johnson & Johnson Pharmaceutical Research & Development, Spring House, Pennsylvania
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20
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Kenakin T, Miller LJ. Seven transmembrane receptors as shapeshifting proteins: the impact of allosteric modulation and functional selectivity on new drug discovery. Pharmacol Rev 2010; 62:265-304. [PMID: 20392808 DOI: 10.1124/pr.108.000992] [Citation(s) in RCA: 458] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
It is useful to consider seven transmembrane receptors (7TMRs) as disordered proteins able to allosterically respond to a number of binding partners. Considering 7TMRs as allosteric systems, affinity and efficacy can be thought of in terms of energy flow between a modulator, conduit (the receptor protein), and a number of guests. These guests can be other molecules, receptors, membrane-bound proteins, or signaling proteins in the cytosol. These vectorial flows of energy can yield standard canonical guest allostery (allosteric modification of drug effect), effects along the plane of the cell membrane (receptor oligomerization), or effects directed into the cytosol (differential signaling as functional selectivity). This review discusses these apparently diverse pharmacological effects in terms of molecular dynamics and protein ensemble theory, which tends to unify 7TMR behavior toward cells. Special consideration will be given to functional selectivity (biased agonism and biased antagonism) in terms of mechanism of action and potential therapeutic application. The explosion of technology that has enabled observation of diverse 7TMR behavior has also shown how drugs can have multiple (pluridimensional) efficacies and how this can cause paradoxical drug classification and nomenclatures.
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Affiliation(s)
- Terry Kenakin
- GlaxoSmithKline, 5 Moore Drive, Mailtstop V-287, Research Triangle Park, NC 27709, USA.
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21
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Miller FJ, Chu X, Stanic B, Tian X, Sharma RV, Davisson RL, Lamb FS. A differential role for endocytosis in receptor-mediated activation of Nox1. Antioxid Redox Signal 2010; 12:583-93. [PMID: 19737091 PMCID: PMC2861543 DOI: 10.1089/ars.2009.2857] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Internalization of activated receptors to a compartment enriched with NAPDH oxidase and associated signaling molecules is expected to facilitate regulation of redox-mediated signal transduction. The aim of this study was to test the hypothesis that endocytosis is necessary for generation of reactive oxygen species (ROS) by Nox1 and for redox-dependent signaling in smooth muscle cells (SMCs). Within minutes of treatment with tumor necrosis factor (TNF)-alpha or thrombin, SMCs increased cellular levels of ROS that was inhibited by shRNA to Nox1. Treatment of SMC with TNF-alpha induced a dynamin-dependent endosomal generation of ROS, whereas thrombin-mediated ROS production did not occur within endosomes and was not prevented by dominant-negative dynamin (dn-dynamin), but instead required transactivation of the epidermal growth factor receptor (EGFR). Activation of the phosphatidylinositol 3-kinase (PI3K)-Akt-activating transcription factor-1 (ATF-1) pathway by TNF-alpha and thrombin were both Nox1- and dynamin-dependent. In conclusion, we show that formation of specific ligand-receptor complexes results in spatially distinct mechanisms of Nox1 activation and generation of ROS. These findings provide novel insights into the role of compartmentalization for integrating redox-dependent cell signaling.
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22
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Inhibition of dynamin prevents CCL2-mediated endocytosis of CCR2 and activation of ERK1/2. Cell Signal 2009; 21:1748-57. [PMID: 19643177 DOI: 10.1016/j.cellsig.2009.07.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Revised: 07/16/2009] [Accepted: 07/21/2009] [Indexed: 11/20/2022]
Abstract
The magnitude and duration of G protein-coupled receptor (GPCR) signals are regulated through desensitization mechanisms. In leukocytes, ligand binding to chemokine receptors leads to Ca2+ mobilization and ERK activation through pertussis toxin-sensitive G proteins, as well as to phosphorylation of the GPCR. After interaction with the endocytic machinery (clathrin, adaptin), the adaptor beta-arrestin recognizes the phosphorylated GPCR tail and quenches signaling to receptors. The molecular mechanisms that lead to receptor endocytosis are not universal amongst the GPCR, however, and the precise spatial and temporal events in the internalization of the CCR2 chemokine receptor remain unknown. Here we show that after ligand binding, CCR2 internalizes rapidly and reaches early endosomes, and later, lysosomes. Knockdown of clathrin by RNA interference impairs CCR2 internalization, as does treatment with the dynamin inhibitor, dynasore. Our results show that CCR2 internalization uses a combination of clathrin-dependent and -independent pathways, as observed for other chemokine receptors. Moreover, the use of dynasore allowed us to confirm the existence of a dynamin-sensitive element that regulates ERK1/2 activation. Our results indicate additional complexity in the link between receptor internalization and cell signaling.
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23
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Guo Y, Wang HL, Xiang XH, Zhao Y. The role of glutamate and its receptors in mesocorticolimbic dopaminergic regions in opioid addiction. Neurosci Biobehav Rev 2009; 33:864-73. [DOI: 10.1016/j.neubiorev.2009.02.005] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2008] [Revised: 02/10/2009] [Accepted: 02/19/2009] [Indexed: 11/28/2022]
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24
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Ryu SD, Lee HS, Suk HY, Park CS, Choi OH. Cross-linking of FcepsilonRI causes Ca2+ mobilization via a sphingosine kinase pathway in a clathrin-dependent manner. Cell Calcium 2009; 45:99-108. [PMID: 18675457 DOI: 10.1016/j.ceca.2008.07.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2007] [Revised: 07/03/2008] [Accepted: 07/04/2008] [Indexed: 10/21/2022]
Abstract
Clathrin-coated pits are now recognized to be involved in cell signaling in addition to receptor down-regulation. Here we tried to identify signaling pathways that might be dependent on clathrin. Our initial data with pharmacological inhibitors of formation of clathrin-coated pits or lipid-rafts indicated that Ca(2+) response evoked by cross-linking of the high affinity receptors for IgE (FcepsilonRI) was dependent on clathrin. To confirm this finding, we created clathrin-knockdown cells by transfecting the mast cell line RBL-2H3 with a shRNA-clathrin heavy chain construct. In these cells, the FcepsilonRI-mediated Ca(2+) response was almost completely abolished, which was accompanied by the inhibition of sphingosine 1-phosphate (S1P) production with no changes in inositol 1,4,5-trisphosphate (IP(3)) production. This suggests that the Ca(2+) signaling pathway via a sphingosine kinase (SK) is dependent on clathrin. Furthermore, antigen-induced tyrosine phosphorylation of p85 and p110 subunits of PI3K was almost completely inhibited in clathrin-knockdown cells. In contrast, antigen-induced tyrosine phosphorylation of phospholipase Cgamma was not affected by clathrin-knockdown and tyrosine phosphorylation of Syk and degranulation were partially inhibited in clathrin-knockdown cells. The present study identifies the SK/Ca(2+) pathway to be dependent on clathrin.
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Affiliation(s)
- Seung-Duk Ryu
- Department of Medicine, Division of Allergy and Clinical Immunology, The Johns Hopkins University School of Medicine, Johns Hopkins Asthma and Allergy Center, 5501 Hopkins Bayview Circle, Baltimore, MD 21224, USA
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25
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Xu AJ, Kuramasu A, Maeda K, Kinoshita K, Takayanagi S, Fukushima Y, Watanabe T, Yanagisawa T, Sukegawa J, Yanai K. Agonist-induced internalization of histamine H2 receptor and activation of extracellular signal-regulated kinases are dynamin-dependent. J Neurochem 2008; 107:208-17. [PMID: 18691388 DOI: 10.1111/j.1471-4159.2008.05608.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Histamine H2 receptor (H2R) is a member of G protein-coupled receptor family. Agonist stimulation of H2R results in several cellular events including activation of adenylate cyclase and phospholipase C, desensitization of the receptor, activation of extracellular signal-regulated kinases ERK1/2, and receptor endocytosis. In this study, we identified a GTPase dynamin as a binding partner of H2R. Dynamin could associate with H2R both in vitro and in vivo. Functional analyses using dominant-negative form of dynamin (K44E-dynamin) revealed that cAMP production and the following H2R desensitization are independent of dynamin. However, the agonist-induced H2R internalization was inhibited by co-expression of K44E-dynamin. Furthermore, activation of extracellular-signal regulated kinases ERK1/2 in response to dimaprit, an H2R agonist, was attenuated by K44E-dynamin. Although H2R with truncation of 51 amino acids at its carboxy-terminus did not internalize after agonist stimulation, it still activated ERK1/2, but the degree of this activation was less than that of the wild-type receptor. Finally, K44E dynamin did not affect ERK1/2 activation induced by internalization-deficient H2R. These results suggest that the agonist-induced H2R internalization and ERK1/2 activation are partially dynamin-dependent. Furthermore, ERK1/2 activation via H2R is likely dependent of the endocytotic process rather than dynamin itself.
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Affiliation(s)
- A-Jing Xu
- Departments of Pharmacology, Tohoku University School of Medicine, Seiryo-machi, Aoba-ku, Sendai, Japan
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26
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Ouedraogo M, Lecat S, Rochdi MD, Hachet-Haas M, Matthes H, Gicquiaux H, Verrier S, Gaire M, Glasser N, Mély Y, Takeda K, Bouvier M, Galzi JL, Bucher B. Distinct motifs of neuropeptide Y receptors differentially regulate trafficking and desensitization. Traffic 2007; 9:305-24. [PMID: 18088318 DOI: 10.1111/j.1600-0854.2007.00691.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Activated human neuropeptide Y Y(1) receptors rapidly desensitize and internalize through clathrin-coated pits and recycle from early and recycling endosomes, unlike Y(2) receptors that neither internalize nor desensitize. To identify motifs implicated in Y(1) receptor desensitization and trafficking, mutants with varying C-terminal truncations or a substituted Y(2) C-terminus were constructed. Point mutations of key putative residues were made in a C-terminal conserved motif [phi-H-(S/T)-(E/D)-V-(S/T)-X-T] that we have identified and in the second intracellular i2 loop. Receptors were analyzed by functional assays, spectrofluorimetric measurements on living cells, flow cytometry, confocal imaging and bioluminescence resonance energy transfer assays for beta-arrestin activation and adaptor protein (AP-2) complex recruitment. Inhibitory GTP-binding protein-dependent signaling of Y(1) receptors to adenylyl cyclase and desensitization was unaffected by C-terminal truncations or mutations, while C-terminal deletion mutants of 42 and 61 amino acids no longer internalized. Substitutions of Thr357, Asp358, Ser360 and Thr362 by Ala in the C-terminus abolished both internalization and beta-arrestin activation but not desensitization. A Pro145 substitution by His in an i2 consensus motif reported to mediate phosphorylation-independent recruitment of beta-arrestins affected neither desensitization, internalization or recycling kinetics of activated Y(1) receptors nor beta-arrestin activation. Interestingly, combining Pro145 substitution by His and C-terminal substitutions significantly attenuates Y(1) desensitization. In the Y(2) receptor, replacement of His155 with Pro at this position in the i2 loop motif promotes agonist-mediated desensitization, beta-arrestin activation, internalization and recycling. Overall, our results indicate that beta-arrestin-mediated desensitization and internalization of Y(1) and Y(2) receptors are differentially regulated by the C-terminal motif and the i2 loop consensus motif.
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Affiliation(s)
- Moussa Ouedraogo
- Institut Gilbert-Laustriat, UMR 7175, CNRS/Université Louis Pasteur, Strasbourg I, France
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27
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Role of receptor internalization in opioid tolerance and dependence. Pharmacol Ther 2007; 117:199-206. [PMID: 18076994 DOI: 10.1016/j.pharmthera.2007.10.003] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2007] [Accepted: 10/25/2007] [Indexed: 12/01/2022]
Abstract
Agonist-induced mu-opioid receptor (MOPr) internalization has long been suggested to contribute directly to functional receptor desensitization and opioid tolerance. In contrast, recent evidence suggests that opioid receptor internalization could in fact reduce opioid tolerance in vivo, but the mechanisms that are responsible for the internalization-mediated protection against opioid tolerance are controversely discussed. One prevailing hypothesis is, that receptor internalization leads to decreased receptor signaling and therefore to reduced associated compensatory changes in downstream signaling systems that are involved in the development of opioid tolerance. However, numerous studies have demonstrated that desensitized and internalized mu-opioid receptors are rapidly recycled to the cell surface in a reactivated state, thus counteracting receptor desensitization and opioid tolerance. Further studies revealed agonist-selective differences in the ability to induce opioid receptor internalization. Recently it has been demonstrated that the endocytotic efficacies of opioids are negatively correlated to the induced opioid tolerance. Thus, clearer understanding of the role of opioid receptor trafficking in the regulation of opioid tolerance and dependence will help in the treatment of patients suffering from chronic pain or drug dependence.
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28
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Bhattacharya M, Ojha N, Solanki S, Mukhopadhyay CK, Madan R, Patel N, Krishnamurthy G, Kumar S, Basu SK, Mukhopadhyay A. IL-6 and IL-12 specifically regulate the expression of Rab5 and Rab7 via distinct signaling pathways. EMBO J 2006; 25:2878-88. [PMID: 16763563 PMCID: PMC1500850 DOI: 10.1038/sj.emboj.7601170] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2005] [Accepted: 05/05/2006] [Indexed: 01/10/2023] Open
Abstract
Recent studies have shown that phagosome maturation depends on the balance between pro-inflammatory and anti-inflammatory cytokines, indicating that cytokine modulates phagosome maturation. However, the mechanism of cytokine-mediated modulation of intracellular trafficking remains to be elucidated. Here, we have shown that treatment of macrophages with IL-6 specifically induce the expression of Rab5 through the activation of extracellular signal-regulated kinase, whereas IL-12 exclusively upregulate the expression of Rab7 through the activation of p38 MAPK. We have cloned the 5'-flanking regions of the rab5c or rab7 into the promoterless reporter vector. Our results have shown that cells transfected with rab5c chimera are transactivated by IL-6, and IL-12 specifically transactivates cells containing rab7 chimera. Moreover, our results also show that IL-12 induces lysosomal transport, whereas IL-6 stimulates the fusion between early compartments in macrophages and accordingly modulates Salmonella trafficking and survival in macrophages. This is the first demonstration showing that cytokine differentially regulates endocytic trafficking by controlling the expression of appropriate Rab GTPase, and provides insight into the mechanism of cytokine-mediated regulation of intracellular trafficking.
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Affiliation(s)
| | - Namrata Ojha
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
| | - Sunil Solanki
- Center for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
| | | | - Richa Madan
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
| | - Nitin Patel
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
| | | | - Senthil Kumar
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
| | - Sandip K Basu
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
| | - Amitabha Mukhopadhyay
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
- Cell Biology Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India. Tel.: +91 11 26703536, +91 11 26703596; Fax: +91 11 26717104; E-mail:
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29
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Abstract
A series of nociceptin receptor ligands has been investigated in relationship to their capability to promote receptor endocytosis, desensitization (evaluated as inhibition of forskolin-stimulated cAMP production) and compensatory upregulation of adenylyl cyclase activity in CHO-K1 cells expressing the cloned human nociceptin receptor. Nociceptin (NC), [Arg14, Lys15]NC-NH2 and NNC 63-0532 (0.01 nM-10 microM) induce a concentration-dependent endocytosis and recycling of the nociceptin receptor. This mechanism contributes to maintain receptor signaling as it counteracts desensitization development and enhances a compensatory upregulation of adenyl cyclase activity. In contrast, the partial agonists [Phe1,Psi(CH2NH)Gly2]NC(1-13)-NH2, Ac-RYYRIK-NH2 and Ac-RYYRWK-NH2 (up to 100 microM) fail to induce receptor endocytosis and cause a pronounced receptor desensitization that is not influenced by monensin, a blocker of recycling of the internalized receptors.
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Affiliation(s)
- Santi Spampinato
- Department of Pharmacology, University of Bologna, Bologna, Italy.
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30
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Narita M, Suzuki M, Narita M, Niikura K, Nakamura A, Miyatake M, Yajima Y, Suzuki T. mu-Opioid receptor internalization-dependent and -independent mechanisms of the development of tolerance to mu-opioid receptor agonists: Comparison between etorphine and morphine. Neuroscience 2006; 138:609-19. [PMID: 16417975 DOI: 10.1016/j.neuroscience.2005.11.046] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2005] [Revised: 11/10/2005] [Accepted: 11/19/2005] [Indexed: 12/30/2022]
Abstract
A growing body of evidences suggests that receptor desensitization is implicated in the development of tolerance to opioids, which is generally regulated by protein kinases and receptor trafficking proteins. In the present study, we demonstrated that repeated s.c. treatment with etorphine, but not morphine, produced a significant increase in protein levels of G protein-coupled receptor kinase 2, dynamin II, beta-arrestin 2 and phosphorylated-conventional protein kinase C in membranes of the mouse spinal cord, suggesting that the etorphine-induced mu-opioid receptor desensitization may result from G protein-coupled receptor kinase 2/dynaminII/beta-arrestin2-dependent phosphorylation of mu-opioid receptors. Unlike etorphine, morphine failed to change the levels of these trafficking proteins. Furthermore, we found that the level of glial fibrillary acidic protein in the mouse spinal cord was clearly increased by chronic in vivo and in vitro treatment with morphine, whereas no such effect was noted by etorphine. In the behavioral study, intraperitoneal pretreatment with the glial-modulating agent propentofylline suppressed the development of tolerance to morphine-induced antinociception. In addition, intrathecal injection of astrocytes and astrocyte-conditioned medium mixture, which were obtained from cultured astrocytes of the newborn mouse spinal cord, aggravated the development of tolerance to morphine. In contrast, these agents failed to affect the development of tolerance induced by etorphine. These findings provide direct evidence for the distinct mechanisms between etorphine and morphine on the development of tolerance to spinal antinociception. These findings raise the possibility that the increased astroglia response produced by chronic morphine could be associated with the lack of mu-opioid receptor internalization.
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Affiliation(s)
- M Narita
- Department of Toxicology, Hoshi University School of Pharmacy and Pharmaceutical Sciences, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan.
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31
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Zhao H, Loh HH, Law PY. Adenylyl cyclase superactivation induced by long-term treatment with opioid agonist is dependent on receptor localized within lipid rafts and is independent of receptor internalization. Mol Pharmacol 2006; 69:1421-32. [PMID: 16415176 DOI: 10.1124/mol.105.020024] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Long-term opioid agonist treatment results in adenylyl cyclase superactivation. A recent "RAVE" theory implicates a direct correlation between the ability of agonist to induce receptor internalization and the magnitude of adenylyl cyclase superactivation. We decided to test such a theory by examining the adenylyl cyclase superactivation after long-term activation of mu-opioid receptor (MOR) in an EcR293 cell model. We examined the magnitudes of adenylyl cyclase superactivation in the presence of naloxone after long-term treatment with morphine, etorphine, and methadone, three agonists reported to have differential activities in promoting MOR internalization. It can be shown that the magnitudes of adenylyl cyclase superactivation after treating with these three agonists, although different, were dependent on MOR density. Blunting MOR internalization with the dominant-negative mutant of dynamin, K44E, did not alter the magnitude of either morphine- or etorphine-induced adenylyl cyclase superactivation. In the presence of diprenorphine, the magnitude of adenylyl cyclase superactivation after etorphine treatment was identical to that observed with morphine. It could be demonstrated further that adenylyl cyclase superactivation is dependent on the cell surface-located MOR. Sucrose gradient fractionation demonstrated the colocalization of MOR and adenylyl cyclase V/VI with caveolin-1, a marker for lipid rafts. After long-term agonist treatment, the majority of MOR remained at the lipid rafts. Methyl-beta-cyclodextrin (MbetaCD) completely blunted the adenylyl cyclase superactivation and agonist-induced receptor internalization. These MbetaCD actions were reversed by incubating the cells with cholesterol. Thus, the adenylyl cyclase superactivation is not dependent on agonist-induced receptor internalization. Rather, the location of MOR at lipid rafts is an absolute requirement for the observed adenylyl cyclase superactivation.
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Affiliation(s)
- Hui Zhao
- Department of Pharmacology, 6-120 Jackson Hall, Medical School, University of Minnesota, 321 Church St. S.E., Minneapolis, MN 55455-0217, USA
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32
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Zanner R, Gratzl M, Prinz C. Expression of the endocytic proteins dynamin and amphiphysin in rat gastric enterochromaffin-like cells. J Cell Sci 2005; 117:2369-76. [PMID: 15126636 DOI: 10.1242/jcs.01091] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dynamin and amphiphysin play crucial roles in a variety of endocytic processes. Previous investigations of expression and functions of these proteins were performed mostly on neurons. The aim of this study was to investigate the presence and interaction of dyn and amph in gastric enterochromaffin-like cells. These endocrine cells of the gastric mucosa play a pivotal role in the regulation of acid secretion. Exocytosis of histamine-containing secretory vesicles has been described in detail. However, the mechanisms of endocytosis are unknown in this neuroendocrine cell type. Using RT-PCR and western blotting, we detected dynamin-1, -2 and -3 in highly enriched isolated enterochromaffin-like cells. Dynamin-1 and -2 were expressed at similar high levels, whereas dynamin-3 was of low abundance. Immunofluorescence microscopy located dynamin-1 and -2 to the cytoplasm and cell surface, whereas dynamin-3 was distributed differently in the perinuclear area. The presence of amphiphysin-1 and -2 RNAs was revealed by RT-PCR and a new splice variant of amphiphysin-2 was detected. Amphiphysin-1 and -2 were also detected in enterochromaffin-like cells by immunohistochemistry in the same locations as dynamin-1 and -2. Amphiphysin-1 and dynamin-1 co-immunoprecipitated with amphiphysin-2. In addition, dynamin-1 and amphiphysin-2 partially colocalized at the plasma membrane. Our results confirm the interaction of dynamin and amphiphysin and imply a role in endocytosis in enterochromaffin-like cells. To our knowledge, this is the first demonstration of the co-expression of all three dynamin isoforms in a non-tumor cell.
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Affiliation(s)
- Robert Zanner
- II Medizinische Klinik und Poliklinik, Technische Universität München, 81675 München, Germany
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Sorkina T, Hoover BR, Zahniser NR, Sorkin A. Constitutive and Protein Kinase C-Induced Internalization of the Dopamine Transporter is Mediated by a Clathrin-Dependent Mechanism. Traffic 2004; 6:157-70. [PMID: 15634215 DOI: 10.1111/j.1600-0854.2005.00259.x] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The amount of dopamine transporter (DAT) present at the cell surface is rapidly regulated by the rates of DAT internalization to endosomes and DAT recycling back to the plasma membrane. The re-distribution of the transporter from the cell surface to endosomes was induced by phorbol ester activation of protein kinase C in porcine aortic endothelial cells stably expressing the human DAT. Inhibition of DAT recycling with the carboxylic ionophore monensin also caused significant accumulation of DAT in early endosomes and a concomitant loss of DAT from the cell surface, due to protein kinase C-independent constitutive internalization of DAT in the absence of recycling. Such monensin-induced relocation of DAT to endosomes was therefore utilized as a measure of the constitutive internalization of DAT. Knock-down of clathrin heavy chain or dynamin II by small interfering RNAs dramatically inhibited both constitutive and protein kinase C-mediated internalization of DAT. In contrast, neither monensin-dependent nor phorbol ester-induced re-distribution of DAT were affected by inhibitors of endocytosis through cholesterol-rich membrane microdomains. Mutational analysis revealed the potential importance of amino acid residues 587-597 in DAT internalization. Altogether, the data suggest that both constitutive and protein kinase C-mediated internalization of DAT utilize the clathrin-dependent endocytic pathway, but likely involve unconventional mechanisms.
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Affiliation(s)
- Tatiana Sorkina
- Department of Pharmacology, University of Colorado Health Sciences Center, Aurora, Colorado 80045, USA
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Koch T, Widera A, Bartzsch K, Schulz S, Brandenburg LO, Wundrack N, Beyer A, Grecksch G, Höllt V. Receptor endocytosis counteracts the development of opioid tolerance. Mol Pharmacol 2004; 67:280-7. [PMID: 15475572 DOI: 10.1124/mol.104.004994] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In contrast to endogenous opioids, the highly addictive drug morphine activates the mu-opioid receptor without causing its rapid endocytosis. It has recently been reported that coapplication of low concentrations of [d-Ala(2),N-Me-Phe(4),Gly(5)-ol]-enkephalin (DAMGO) facilitates the ability of morphine to stimulate mu-opioid receptor endocytosis and prevents the development of morphine tolerance in rats. To investigate the clinical relevance of this finding for analgesic therapy, the endocytotic efficacies of a series of clinically used opioids were determined, and the effect of a combination of these drugs with morphine on the mu-opioid receptor endocytosis in receptor-expressing human embryonic kidney (HEK) 293 cells was quantified. The combination of morphine and opioid drugs with high endocytotic efficacies (e.g., DAMGO, etonitazene, sufentanil, beta-endorphin, piritramide, or methadone) did not result in a facilitation of morphine-mediated endocytosis but rather in a decrease of the receptor endocytosis mediated by the tested opioid drugs. These findings demonstrate a partial agonistic effect of morphine on the agonist-induced receptor endocytosis. Moreover, we demonstrated that the endocytotic potencies of opioid drugs are negatively correlated with their ability to cause receptor desensitization and opioid tolerance in HEK 293 cells. These results strongly support the hypothesis that mu-opioid receptor endocytosis counteracts receptor desensitization and opioid tolerance by inducing fast receptor reactivation and recycling. In addition, it is shown that agonist-induced receptor endocytosis facilitates the compensatory up-regulation of the cAMP pathway, a cellular hallmark of opioid withdrawal. Our findings suggest that opioids with high endocytotic efficacies might cause reduced opioid tolerance but can facilitate compensatory mechanisms, resulting in an enhanced opioid dependence.
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Affiliation(s)
- Thomas Koch
- Department of Pharmacology and Toxicology, Otto-von-Guericke University, 39120 Magdeburg, Leipziger Strasse 44, Germany.
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Mishra RK, Jatiani SS, Kumar A, Simhadri VR, Hosur RV, Mittal R. Dynamin interacts with members of the sumoylation machinery. J Biol Chem 2004; 279:31445-54. [PMID: 15123615 DOI: 10.1074/jbc.m402911200] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dynamin is a GTP-binding protein whose oligomerization-dependent assembly around the necks of lipid vesicles mediates their scission from parent membranes. Dynamin is thus directly involved in the regulation of endocytosis. Sumoylation is a post-translational protein modification whereby the ubiquitin-like modifier Sumo is covalently attached to lysine residues on target proteins by a process requiring the concerted action of an activating enzyme (ubiquitin-activating enzyme), a conjugating enzyme (ubiquitin carrier protein), and a ligating enzyme (ubiquitin-protein isopeptide ligase). Here, we show that dynamin interacts with Sumo-1, Ubc9, and PIAS-1, all of which are members of the sumoylation machinery. Ubc9 and PIAS-1 are known ubiquitin carrier protein and ubiquitin-protein isopeptide ligase enzymes, respectively, for the process of sumoylation. We have identified the coiled-coil GTPase effector domain (GED) of dynamin as the site on dynamin that interacts with Sumo-1, Ubc9, and PIAS-1. Although we saw no evidence of covalent Sumo-1 attachment to dynamin, Sumo-1 and Ubc9 are shown here to inhibit the lipid-dependent oligomerization of dynamin. Expression of Sumo-1 and Ubc9 in mammalian cells down-regulated the dynamin-mediated endocytosis of transferrin, whereas dynamin-independent fluid-phase uptake was not affected. Furthermore, using high resolution NMR spectroscopy, we have identified amino acid residues on Sumo-1 that directly interact with the GED of dynamin. The results suggest that the GED of dynamin may serve as a scaffold that concentrates the sumoylation machinery in the vicinity of potential acceptor proteins.
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Affiliation(s)
- Ram Kumar Mishra
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai 400 005, India
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36
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Holstein DM, Berg KA, Leeb-Lundberg LMF, Olson MS, Saunders C. Calcium-sensing Receptor-mediated ERK1/2 Activation Requires Gαi2 Coupling and Dynamin-independent Receptor Internalization. J Biol Chem 2004; 279:10060-9. [PMID: 14701866 DOI: 10.1074/jbc.m312039200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The calcium-sensing receptor (CaR) recently has been shown to activate MAP kinase (ERK1/2) in various cell types as well as in heterologous expression systems. In this study we show that the CaR agonist NPS R-467 (1 microm), which does not activate the CaR by itself, robustly activates ERK1/2 in the presence of a low concentration of Ca(2+) (0.5 mm CaCl(2)) in human embryonic kidney (HEK) cells permanently expressing the human CaR (HEK-hCaR). Ca(2+) (4 mm) also activates ERK1/2 but with differing kinetics. CaR-dependent ERK1/2 activation begins to desensitize to 4 mm Ca(2+) after 10 min, whereas there is no desensitization to NPS R-467/CaCl(2) as late as 4 h. Moreover, recovery from desensitization occurs as rapidly as 30 min with 4 mm CaCl(2). Pretreatment of HEK-hCaR cells with concanavalin A (250 microg/ml) to block CaR internalization completely eliminated the NPS R-467/CaCl(2)-mediated ERK1/2 activation but did not block the 2-min time point of 4 mm Ca(2+)-mediated ERK1/2 activation. Neither dominant-negative dynamin (K44A) nor dominant-negative beta-arrestin inhibited ERK1/2 activation by either CaR agonist treatment, suggesting that CaR-elicited ERK1/2 signaling occurs via a dynamin-independent pathway. Pertussis toxin pretreatment partially attenuated the 4 mm Ca(2+)-ERK1/2 activation; this attenuated activity was completely restored by co-expression of the Galpha(i2) (C351I) but not Galpha(i1) (C351I) or Galpha(i3) (C351I) G proteins, PTX-insensitive G protein mutants. Taken together, these data suggest that both 4 mm Ca(2+) and NPS R-467/CaCl(2) activate ERK1/2 via distinguishable pathways in HEK-hCaR cells and may represent a nexus to differentially regulate differentiation versus proliferation via CaR activation.
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Affiliation(s)
- Deborah M Holstein
- Department of Biochemistry, University of Texas Health Science Center at San Antonio, 78229-3900, USA
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37
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Huang J, Sun Y, Huang XY. Distinct roles for Src tyrosine kinase in beta2-adrenergic receptor signaling to MAPK and in receptor internalization. J Biol Chem 2004; 279:21637-42. [PMID: 14990578 DOI: 10.1074/jbc.m400956200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
G protein-coupled receptors form the largest family of membrane receptors and transmit diverse ligand signals to modulate various cellular responses. After activation by their ligands, some of these G protein-coupled receptors are desensitized, internalized (endocytosed), and down-regulated (degraded). In HEK 293 cells, the G(s)-coupled beta2-adrenergic receptor was postulated to initiate a second wave of signaling, such as the activation of the mitogen-activated protein kinase (MAPK) pathway after the receptor is internalized. The tyrosine kinase c-Src plays a critical role in these events. Here we used mouse embryonic fibroblast (MEF) cells deficient in Src family tyrosine kinases to examine the role of Src in beta2-adrenergic receptor signaling to the MAPK pathway and in receptor internalization. We found that in Src-deficient cells the beta2-adrenergic receptor could activate the MAPK pathway. However, the internalization of beta2-adrenergic receptors was blocked in Src-deficient MEF cells. Furthermore, we observed that in MEF cells deficient in beta-arrestin 2 the internalization of the beta2-adrenergic receptor was impaired, whereas the activation of the MAPK pathway by the beta2-adrenergic receptor was normal. Our data demonstrate that although Src and beta-arrestin 2 play essential roles in beta2-adrenergic receptor internalization, they are not required for the activation of the MAPK pathway by the beta2-adrenergic receptor. In other words, our finding suggests that receptor internalization is not required for beta2-adrenergic receptor signaling to the MAPK pathway in MEF cells.
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Affiliation(s)
- Jianyun Huang
- Department of Physiology, Cornell University Weill Medical College, New York, NY 10021, USA
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38
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Kahlig KM, Javitch JA, Galli A. Amphetamine regulation of dopamine transport. Combined measurements of transporter currents and transporter imaging support the endocytosis of an active carrier. J Biol Chem 2003; 279:8966-75. [PMID: 14699142 DOI: 10.1074/jbc.m303976200] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dopaminergic neurotransmission is fine-tuned by the rate of removal of dopamine (DA) from the extracellular space via the Na(+)/Cl(-)-dependent DA transporter (DAT). DAT is a target of psychostimulants such as amphetamine (AMPH) and cocaine. Previously, we reported that AMPH redistributes the human DAT away from the cell surface. This process was associated with a reduction in transport capacity. This loss of transport capacity may result either from a modification of the function of DAT that is independent of its cell surface redistribution and/or from a reduction in the number of active transporters at the plasma membrane that results from DAT trafficking. To discriminate between these possibilities, we stably transfected HEK-293 cells with a yellow fluorescent protein (YFP)-tagged human DAT (hDAT cells). In hDAT cells, acute exposure to AMPH induced a time-dependent loss of hDAT activity. By coupling confocal imaging with patch-clamp whole-cell recordings, we have demonstrated for the first time that the loss of AMPH-induced hDAT activity temporally parallels the accumulation of intracellular hDAT. In addition, presteady-state current analysis revealed a cocaine-sensitive, voltage-dependent capacitance current that correlated with the level of transporter membrane expression and in turn served to monitor the AMPH-induced trafficking of hDAT. We found that the decrease in hDAT cell surface expression induced by AMPH was not paralleled by changes in the ability of the single transporter to carry charges. Quasi-stationary noise analysis of the AMPH-induced hDAT currents revealed that the unitary transporter current remained unaltered during the loss of hDAT membrane expression. Taken together, these data strongly suggest that the AMPH-induced reduction of hDAT transport capacity results from the removal of active hDAT from the plasma membrane.
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Affiliation(s)
- Kristopher M Kahlig
- Department of Molecular Physiology and Biophysics, Center for Molecular Neuroscience, Vanderbilt University, Nashville, Tennessee 37232-8548, USA
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39
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Charest PG, Bouvier M. Palmitoylation of the V2 vasopressin receptor carboxyl tail enhances beta-arrestin recruitment leading to efficient receptor endocytosis and ERK1/2 activation. J Biol Chem 2003; 278:41541-51. [PMID: 12900404 DOI: 10.1074/jbc.m306589200] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A large number of G protein-coupled receptors are palmitoylated on cysteine residues located in their carboxyl tail, but the general role of this post-translational modification remains poorly understood. Here we show that preventing palmitoylation of the V2 vasopressin receptor, by site-directed mutagenesis of cysteines 341 and 342, significantly delayed and decreased both agonist-promoted receptor endocytosis and mitogen-activated protein kinase activation. Pharmacological blockade of receptor endocytosis is without effect on the vasopressin-stimulated mitogen-activated protein kinase activity, excluding the possibility that the reduced kinase activation mediated by the palmitoylation-less mutant could result from altered receptor endocytosis. In contrast, two dominant negative mutants of beta-arrestin which inhibit receptor endocytosis also attenuated vasopressin-stimulated mitogen-activated protein kinase activity, suggesting that the scaffolding protein, beta-arrestin, represents the common link among receptor palmitoylation, endocytosis, and kinase activation. Coimmunoprecipitation and bioluminescence resonance energy transfer experiments confirmed that inhibiting receptor palmitoylation considerably reduced the vasopressin-stimulated recruitment of beta-arrestin to the receptor. Interestingly, the changes in beta-arrestin recruitment kinetics were similar to those observed for vasopressin-stimulated receptor endocytosis and mitogen-activated protein kinase activation. Taken together the results indicate that palmitoylation enhances the recruitment of beta-arrestin to the activated V2 vasopressin receptor thus facilitating processes requiring the scaffolding action of beta-arrestin.
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Affiliation(s)
- Pascale G Charest
- Department of Biochemistry and Groupe de Recherche sur le Système Nerveux Autonome, Université de Montréal, Montréal, Québec H3C 3J7, Canada
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García-Fuster MJ, Ferrer-Alcón M, Miralles A, García-Sevilla JA. Modulation of Fas receptor proteins and dynamin during opiate addiction and induction of opiate withdrawal in rat brain. Naunyn Schmiedebergs Arch Pharmacol 2003; 368:421-31. [PMID: 14530904 DOI: 10.1007/s00210-003-0801-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2003] [Accepted: 08/19/2003] [Indexed: 10/26/2022]
Abstract
The Fas receptor is involved in the regulation of apoptosis but also can function as a non-apoptotic signal transducer. This study was mainly designed to quantitate Fas proteins in rat brain during heroin addiction and opiate withdrawal. In rat, mouse and human brains, and in SH-SY5Y cells, similar forms of Fas were immunodetected with different antibodies (i.e., 35 kDa native Fas and 48- and 51-kDa glycosylated Fas). Acute (2 h) treatments with the micro-opioid receptor agonists heroin (10 mg/kg) and morphine (30 mg/kg) increased the immunodensity of native Fas (124% and 36%) but not that of glycosylated Fas in the cerebral cortex. Chronic (5 days) heroin (5-30 mg/kg) and morphine (10-100 mg/kg) were also associated with increased native Fas (76% and 45%) and with different expressions of glycosylated Fas. In heroin-dependent rats, opiate withdrawal (48 h) resulted in a sustained increase in native Fas (107%) and in up-regulation of 51 kDa glycosylated Fas (51%). Acute treatments with selective delta-receptor (SNC-80, 10 mg/kg) or kappa-receptor (U 50488-H, 10 mg/kg) agonists did not alter the content of native or glycosylated Fas. Chronic pentazocine (10-80 mg/kg, 5 days), a mixed opiate drug and sigma(1) receptor agonist, decreased native (48%) and glycosylated (38-82%) Fas proteins. Similarly, the selective sigma(1) agonist (+)-SKF 10047 also decreased native Fas (37%) and the effect was blocked by the sigma(1) antagonist BD 1063. Brain dynamin was up-regulated by acute and/or chronic heroin (30-39%), morphine (47-85%), pentazocine (51%) and heroin withdrawal (74%). The main results indicate that chronic heroin/morphine treatment and heroin withdrawal are associated with up-regulation of 35 kDa native Fas (and with different expressions of glycosylated Fas), and also with concomitant increases of dynamin in rat brain.
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Affiliation(s)
- M Julia García-Fuster
- Laboratory of Neuropharmacology, Associate Unit of the Institute of Neurobiology "Ramón y Cajal" (CSIC), Department of Biology, University of the Balearic Islands, Cra. Valldemossa Km 7.5, 07122, Palma de Mallorca, Spain
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Jiménez-Sainz MC, Fast B, Mayor F, Aragay AM. Signaling pathways for monocyte chemoattractant protein 1-mediated extracellular signal-regulated kinase activation. Mol Pharmacol 2003; 64:773-82. [PMID: 12920215 DOI: 10.1124/mol.64.3.773] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
G protein-coupled receptors (GPCRs) initiate diverse down-stream signaling events in response to ligand stimulation, as rapid activation of the extracellular signal-regulated kinase ERK1 and ERK2. The chemokine monocyte chemoattractant protein-1 (MCP-1) is the agonist for several chemokine receptors that belong to the GPCR superfamily, CCR2 being the most important. Stimulation of mitogen-activated protein kinases (MAPKs) by MCP-1 has been implicated in integrin activation and chemotaxis, but the molecular pathways down-stream of the receptors remain unclear. To dissect the cascade of events leading to MAPK activation upon CCR2 receptor stimulation, several specific inhibitors and mutants of signal transduction proteins were used in monocytic cells endogenously expressing CCR2 and/or in human embryonic kidney-293 cells transfected with CCR2B receptors and epitope-tagged ERK1. We show that ERK activation by MCP-1 involves heterotrimeric Gi protein subunits, protein kinase C, phosphoinositide-3-kinase, and Ras. On the other hand, the activity of cytosolic tyrosine kinases, epidermal growth factor receptor transactivation, or variations in intracellular calcium levels are not required for the mitogenic activation elicited by MCP-1. In addition, we find that internalization of CCR2B itself is not necessary for efficient MCP-1-induced activation of ERK, although a dynamin mutant partially inhibits ERK stimulation. These results suggest that different parallel pathways are being activated that lead to the full activation of the mitogen-activated protein kinase cascade and that internalization of other signaling proteins but not of the receptor is required for complete ERK activation.
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Affiliation(s)
- M Carmen Jiménez-Sainz
- Department of Anatomy and Cell Biology, Faculty of Medicine, University of Bergen, N-5009 Bergen, Norway.
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42
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Chen Z, Rola-Pleszczynski M, Stankova J. Activation of ERK1/2 by platelet-activating factor receptor is independent of receptor internalisation and G-protein activation. Cell Signal 2003; 15:843-50. [PMID: 12834809 DOI: 10.1016/s0898-6568(03)00056-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Platelet-activating factor (PAF) is a potent pro-inflammatory phospholipid mediator involved in a broad range of physiological and pathophysiological processes. The receptor of PAF (PAFR) is a heptahelical G-protein-coupled receptor. We have shown previously that upon agonist stimulation, PAFR internalised through clathrin-coated vesicles in an arrestin-dependent, but G-protein-coupling-independent manner. In the current report, we demonstrate that PAF stimulates Erk1/2 phosphorylation and: (1). dominant negative mutants of arrestins and dynamin do not influence Erk1/2 activation, (2). hypertonic conditions do not decrease the extent of Erk1/2 phosphorylation, (3). internalisation-deficient and/or G-protein-coupling-deficient mutants of PAFR activate Erk1/2 as efficiently as the wild-type PAFR, and (4). inhibition of epidermal growth factor receptor (EGFR) does not block Erk1/2 activation. Taken together, our results suggest that PAFR-mediated activation of mitogen-activated protein kinases Erk1/2 does not require receptor endocytosis, receptor tyrosine kinase transactivation or G-protein activation. In addition, our studies reveal that PAFR-mediated signals of G-protein activation, receptor internalisation and MAPK activation are differentially regulated by receptor structure and/or conformation.
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Affiliation(s)
- Zhangguo Chen
- Department of Pediatrics, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Quebec, Canada J1H 5N4
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Arnold AM, Anderson GW, McIver B, Eberhardt NL. A novel dynamin III isoform is up-regulated in the central nervous system in hypothyroidism. Int J Dev Neurosci 2003; 21:267-75. [PMID: 12850060 DOI: 10.1016/s0736-5748(03)00053-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Hypothyroidism in early postnatal development leads to abnormal CNS development that may be controlled in part at the level of gene transcription. Comparing the expression of euthyroid (EuT) and hypothyroid (HypoT) rat brain mRNAs by differential display PCR (ddPCR), we identified a novel dynamin III mRNA that was up-regulated in the hypothyroid state. Northern analysis of brain mRNA using a probe from the dynamin III open reading frame (ORF) revealed two transcripts of 3.0 and 7.2kb size. The 3.0 kb transcript was observed in testis and brain, but not liver or lung RNA. In the brain the 3.0 kb transcript increased from 25 to 57% of adult (Ad) levels from postnatal day (p) p2-p15, but was not significantly regulated by thyroid hormone status. In contrast, the more abundant 7.2 kb transcript increased from 16.8 to 48.0% of adult levels from p2 to p15 in euthyroid rat pups but from 54.0% of adult levels at p2 to 97.9% of adult levels by p15 in hypothyroid pups. Overlapping cDNA clones from a rat brain cDNA library defined the 7.2kb mRNA, which consisted of the complete ORF, containing a four amino acid insert at the end of the pleckstrin homology domain (PHD), and two unique 3'-flanking regions, that are likely derived from alternative processing. Thus, the 7.2 kb dynamin III transcript is brain-specific and selectively regulated by thyroid hormone status. The data suggest that the regulation of dynamin III by altered thyroid hormone status may affect synaptogenesis in the CNS through dynamin's essential roles in synaptic vesicle and receptor recycling, neurotransmitter reuptake, and growth factor receptor signaling.
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Affiliation(s)
- Andrew M Arnold
- Department of Medicine, Mayo Clinic, Rochester, MN 55905, USA
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Elorza A, Penela P, Sarnago S, Mayor F. MAPK-dependent degradation of G protein-coupled receptor kinase 2. J Biol Chem 2003; 278:29164-73. [PMID: 12738776 DOI: 10.1074/jbc.m304314200] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
G protein-coupled receptor kinase 2 (GRK2) is a key modulator of G protein-coupled receptors (GPCR). Altered expression of GRK2 has been described to occur during pathological conditions characterized by impaired GPCR signaling. We have reported recently that GRK2 is rapidly degraded by the proteasome pathway and that beta-arrestin function and Src-mediated phosphorylation are involved in targeting GRK2 for proteolysis. In this report, we show that phosphorylation of GRK2 by MAPK also triggers GRK2 turnover by the proteasome pathway. Modulation of MAPK activation alters the degradation of transfected or endogenous GRK2, and a GRK2 mutant that mimics phosphorylation by MAPK shows an enhanced degradation rate, thus indicating a direct effect of MAPK on GRK2 turnover. Interestingly, MAPK-mediated modulation of wild-type GRK2 stability requires beta-arrestin function and is facilitated by previous phosphorylation of GRK2 on tyrosine residues by c-Src. Consistent with an important physiological role, interfering with this GRK2 degradation process results in altered GPCR responsiveness. Our data suggest that both c-Src and MAPK-mediated phosphorylation would contribute to modulate GRK2 degradation, and put forward the existence of new feedback mechanisms connecting MAPK cascades and GPCR signaling.
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Affiliation(s)
- Ana Elorza
- Departamento de Biología Molecular and Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Científicas-Universidad Autónoma de Madrid, E-28049 Madrid, Spain
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45
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Cao S, Yao J, Shah V. The proline-rich domain of dynamin-2 is responsible for dynamin-dependent in vitro potentiation of endothelial nitric-oxide synthase activity via selective effects on reductase domain function. J Biol Chem 2003; 278:5894-901. [PMID: 12488320 DOI: 10.1074/jbc.m212546200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The GTPase dynamin-2 (dyn-2) binds and positively regulates the nitric oxide-generating enzyme, endothelial nitric-oxide synthase (eNOS) (Cao, S., Yao, Y., McCabe, T., Yao, Q., Katusic, Z., Sessa, W., and Shah, V. (2001) J. Biol. Chem. 276, 14249-14256). Here we demonstrate, using purified proteins, that this occurs through a selective influence of the dyn-2 proline-rich domain (dyn-2 PRD) on the eNOS reductase domain. In vitro studies demonstrate that dyn-2 PRD fused with glutathione S-transferase (GST) binds recombinant eNOS protein specifically and with binding kinetics comparable with that observed between dyn-2 full-length and eNOS. Additionally, GST-dyn-2 PRD binds the in vitro transcribed (35)S-eNOS reductase domain but not the (35)S-eNOS oxygenase domain. Furthermore GST-dyn-2 PRD binds a (35)S-labeled eNOS reductase domain fragment (amino acids 645-850) that partially overlaps with the FAD binding domain of eNOS. A recombinant form of the SH3-containing protein Fyn competes the binding of recombinant eNOS protein with dyn-2 PRD, thereby implicating the SH3-like region contained within this reductase domain fragment as the dyn-2 binding region. Mammalian two-hybrid screen corroborates these interactions in cells as well. Functional studies demonstrate that dyn-2 PRD selectively potentiates eNOS activity in a concentration-dependent manner in an order of magnitude similar to that observed with dyn-2 full-length and in a manner that requires calmodulin. Although dyn-2 PRD does not influence eNOS oxygenase domain function or ferricyanide reduction, it does potentiate the ability of recombinant eNOS to reduce cytochrome c, supporting an influence of dyn-2 PRD on electron transfer between FAD and FMN. (These data indicate that the binding domains of dyn-2 and eNOS reside within the dyn-2 PRD domain and the FAD binding region of the eNOS reductase domains, respectively, and that dyn-2 PRD is sufficient to mediate dyn-2-dependent potentiation of eNOS activity, at least in part, by potentiating electron transfer.)
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Affiliation(s)
- Sheng Cao
- Gastrointestinal Research Unit and Department of Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA
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46
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Okura T, Varga EV, Hosohata Y, Navratilova E, Cowell SM, Rice K, Nagase H, Hruby VJ, Roeske WR, Yamamura HI. Agonist-specific down-regulation of the human delta-opioid receptor. Eur J Pharmacol 2003; 459:9-16. [PMID: 12505529 DOI: 10.1016/s0014-2999(02)02823-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Down-regulation of the delta-opioid receptor contributes to the development of tolerance to delta-opioid receptor agonists. The involvement of the carboxy terminus of the mouse delta-opioid receptor in peptide agonist-mediated down-regulation has been established. In the present study, we examined the down-regulation of the truncated human delta-opioid receptor by structurally distinct delta-opioid receptor agonists. Chinese hamster ovary (CHO) cells, expressing the full-length or truncated epitope-tagged human delta-opioid receptors were incubated with various delta-opioid receptor agonists (100 nM, 24 h), and membrane receptor levels were determined by [(3)H]naltrindole saturation binding. Each delta-opioid receptor agonist tested down-regulated the full-length receptor. Truncation of the carboxy terminus abolished down-regulation by all delta-opioid receptor agonists, except SNC80 ((+)-4-[(alphaR)-alpha-((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]N,N-diethylbenzamide). In addition, truncation of the C-terminus completely attenuated [D-Pen(2)-D-Pen(5)]enkephalin (DPDPE), but not SNC80-mediated [32P] incorporation into the protein immunoreactive with an anti-epitope-tagged antibody. These findings suggest that SNC80-mediated phosphorylation and down-regulation of the human delta-opioid receptor involves other receptor domains in addition to the carboxy terminus. Pertussis toxin treatment did not block SNC80-mediated down-regulation of the truncated Et-hDOR, indicating that the down-regulation is independent of G(i/o) protein activation and subsequent downstream signaling.
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MESH Headings
- Amino Acid Sequence
- Analgesics, Opioid/pharmacology
- Animals
- Benzamides/pharmacology
- Binding, Competitive/drug effects
- CHO Cells
- Cricetinae
- Dose-Response Relationship, Drug
- Down-Regulation
- Enkephalin, D-Penicillamine (2,5)-/pharmacology
- Humans
- Molecular Sequence Data
- Naltrexone/analogs & derivatives
- Naltrexone/metabolism
- Pertussis Toxin/pharmacology
- Phosphorylation/drug effects
- Piperazines/pharmacology
- Radioligand Assay
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/genetics
- Receptors, Opioid, delta/metabolism
- Recombinant Fusion Proteins/agonists
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Sequence Deletion
- Tritium
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Affiliation(s)
- Takashi Okura
- Department of Pharmacology, The University of Arizona Health Sciences Center, Tucson, AZ 85724, USA
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47
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Dell EJ, Connor J, Chen S, Stebbins EG, Skiba NP, Mochly-Rosen D, Hamm HE. The betagamma subunit of heterotrimeric G proteins interacts with RACK1 and two other WD repeat proteins. J Biol Chem 2002; 277:49888-95. [PMID: 12359736 DOI: 10.1074/jbc.m202755200] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A yeast two-hybrid approach was used to discern possible new effectors for the betagamma subunit of heterotrimeric G proteins. Three of the clones isolated are structurally similar to Gbeta, each exhibiting the WD40 repeat motif. Two of these proteins, the receptor for activated C kinase 1 (RACK1) and the dynein intermediate chain, co-immunoprecipitate with Gbetagamma using an anti-Gbeta antibody. The third protein, AAH20044, has no known function; however, sequence analysis indicates that it is a WD40 repeat protein. Further investigation with RACK1 shows that it not only interacts with Gbeta(1)gamma(1) but also unexpectedly with the transducin heterotrimer Galpha(t)beta(1)gamma(1). Galpha(t) alone does not interact, but it must contribute to the interaction because the apparent EC(50) value of RACK1 for Galpha(t)beta(1)gamma(1) is 3-fold greater than that for Gbeta(1)gamma(1) (0.1 versus 0.3 microm). RACK1 is a scaffold that interacts with several proteins, among which are activated betaIIPKC and dynamin-1 (1). betaIIPKC and dynamin-1 compete with Gbeta(1)gamma(1) and Galpha(t)beta(1)gamma(1) for interaction with RACK1. These findings have several implications: 1) that WD40 repeat proteins may interact with each other; 2) that Gbetagamma interacts differently with RACK1 than with its other known effectors; and/or 3) that the G protein-RACK1 complex may constitute a signaling scaffold important for intracellular responses.
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Affiliation(s)
- Edward J Dell
- Institute for Neuroscience and Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, Chicago, Illinois 60613, USA
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48
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Lu Z, Murray JT, Luo W, Li H, Wu X, Xu H, Backer JM, Chen YG. Transforming growth factor beta activates Smad2 in the absence of receptor endocytosis. J Biol Chem 2002; 277:29363-8. [PMID: 12034739 DOI: 10.1074/jbc.m203495200] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Like many other cell surface receptors, transforming growth factor beta (TGF-beta) receptors are internalized upon ligand stimulation. Given that the signaling-facilitating molecules Smad anchor for receptor activation (SARA) and Hrs are mainly localized in early endosomes, it was unclear whether receptor internalization is required for Smad2 activation. Using reversible biotin labeling, we directly monitored internalization of the TGF-beta type I receptor. Our data indicate that TGF-beta type I receptor is endocytosed via a clathrin-dependent mechanism and is effectively blocked by depletion of intracellular potassium or by expression of a mutant dynamin (K44A). However, blockage of receptor endocytosis by these two means has no effect on TGF-beta-mediated Smad2 activation. Furthermore, TGF-beta-induced Smad2 activation was unaffected by inhibition of hVPS34 activity with wortmannin or inhibitory anti-hVPS34 antibodies. Finally, we demonstrated that Smad2 interacted with cell surface receptors and that a SARA binding-deficient Smad2 mutant was phosphorylated by the receptors. Thus, our findings suggest that receptor endocytosis is dispersible for TGF-beta-mediated activation of Smad2 and that this activation can be mediated by both SARA-dependent and -independent mechanisms.
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Affiliation(s)
- Zhongxian Lu
- Division of Biomedical Sciences, University of California, Riverside, California 92521, USA
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49
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Sorkin A, Von Zastrow M. Signal transduction and endocytosis: close encounters of many kinds. Nat Rev Mol Cell Biol 2002; 3:600-14. [PMID: 12154371 DOI: 10.1038/nrm883] [Citation(s) in RCA: 647] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Binding of hormones, growth factors and other cell modulators to cell-surface receptors triggers a complex array of signal-transduction events. The activation of many receptors also accelerates their endocytosis. Endocytic transport is important in regulating signal transduction and in mediating the formation of specialized signalling complexes. Conversely, signal-transduction events modulate specific components of the endocytic machinery. Recent studies of protein tyrosine kinases and G-protein-coupled receptors have shed new light on the mechanisms and functional consequences of this bidirectional interplay between signalling and membrane-transport networks.
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Affiliation(s)
- Alexander Sorkin
- Department of Pharmacology, University of Colorado Health Sciences Center, Denver, Colorado 80111, USA.
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50
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Szaszák M, Gáborik Z, Turu G, McPherson PS, Clark AJL, Catt KJ, Hunyady L. Role of the proline-rich domain of dynamin-2 and its interactions with Src homology 3 domains during endocytosis of the AT1 angiotensin receptor. J Biol Chem 2002; 277:21650-6. [PMID: 11925437 DOI: 10.1074/jbc.m200778200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In nonneural tissues, the dynamin-2 isoform participates in the formation of clathrin-coated vesicles during receptor endocytosis. In this study, the mechanism of dynamin-2 action was explored during endocytosis of the G protein-coupled AT1A angiotensin receptor expressed in Chinese hamster ovary cells. Dynamin-2 molecules with mutant pleckstrin homology domains or deleted proline-rich domains (PRD) exerted dominant negative inhibition on the endocytosis of radiolabeled angiotensin II. However, only the PRD mutation interfered with the localization of the dynamin-2 molecule to clathrin-coated pits and reduced the inhibitory effect of the GTPase-deficient K44A mutant dynamin-2. Green fluorescent protein-tagged Src homology 3 (SH3) domains of endophilin I and amphiphysin II, two major binding partners of dynamins, also inhibited AT1A receptor-mediated endocytosis of angiotensin II. These effects were partially or fully, respectively, restored by the overexpression of dynamin-2. Transient overexpression of these SH3 domains also reduced the localization of dynamin-2 to clathrin-coated pits. These data indicate that, similar to the recruitment of dynamin-1 during the recycling of synaptic vesicles, interaction of the dynamin-2 PRD with SH3 domains of proteins such as the amphiphysins and endophilins is essential for AT1A receptor endocytosis. This mechanism could be of general importance in dynamin-dependent endocytosis of other G protein-coupled receptors in nonneural tissues.
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MESH Headings
- Animals
- Blotting, Western
- CHO Cells
- Cells, Cultured
- Cricetinae
- DNA, Complementary/metabolism
- Dynamin I
- Dynamins
- Endocytosis
- GTP Phosphohydrolases/chemistry
- GTP Phosphohydrolases/physiology
- Gene Deletion
- Genes, Dominant
- Green Fluorescent Proteins
- Luminescent Proteins/metabolism
- Microscopy, Confocal
- Microscopy, Fluorescence
- Mutagenesis, Site-Directed
- Mutation
- Plasmids/metabolism
- Proline/chemistry
- Protein Binding
- Protein Isoforms
- Protein Structure, Tertiary
- Rats
- Receptor, Angiotensin, Type 1
- Receptors, Angiotensin/chemistry
- Receptors, Angiotensin/metabolism
- Time Factors
- Transfection
- src Homology Domains
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Affiliation(s)
- Márta Szaszák
- Department of Physiology, Semmelweis University, Faculty of Medicine, H-1088 Budapest, Hungary
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