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Puthenveedu MA, von Zastrow M. Cargo Regulates Clathrin-Coated Pit Dynamics. Cell 2006; 127:113-24. [PMID: 17018281 DOI: 10.1016/j.cell.2006.08.035] [Citation(s) in RCA: 207] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2006] [Revised: 06/02/2006] [Accepted: 08/01/2006] [Indexed: 11/15/2022]
Abstract
Clathrin-coated pits (CCPs) are generally considered a uniform population of endocytic machines containing mixed constitutive and regulated membrane cargo. Contrary to this view, we show that regulated endocytosis of G protein-coupled receptors (GPCRs) occurs preferentially through a subset of CCPs. Significantly, GPCR-containing CCPs are also functionally distinct, as their surface residence time is regulated locally by GPCR cargo via PDZ-dependent linkage to the actin cytoskeleton. Such cargo-regulated CCPs show delayed recruitment of dynamin and can undergo an abortive event in which clathrin coats separate from the plasma membrane without concomitant receptor endocytosis. Segregation of cargo into CCP subsets, combined with cargo-dependent control of CCP dynamics, suggests a simple kinetic mechanism to generate functional specialization early in the endocytic pathway and reduce competition between diverse endocytic cargo.
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Affiliation(s)
- Manojkumar A Puthenveedu
- Department of Psychiatry, University of California at San Francisco, 600 16th Street, San Francisco, CA 94158, USA
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Day P, Kobilka B. PDZ-domain arrays for identifying components of GPCR signaling complexes. Trends Pharmacol Sci 2006; 27:509-11. [PMID: 16904197 DOI: 10.1016/j.tips.2006.08.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Revised: 07/10/2006] [Accepted: 08/02/2006] [Indexed: 11/22/2022]
Abstract
Many G-protein-coupled receptors (GPCRs) modulate the activity of multiple effectors. Yet, despite this apparent promiscuity, signaling in the context of differentiated cells is often highly specific. This specificity is attributable to the formation of cell-type-specific signaling complexes that are held together by scaffolding proteins, many of which contain one or more PDZ domains. Identifying the set of potential interactions among GPCRs, other signaling molecules and these scaffolding proteins is essential for understanding physiological signaling processes. A recent article describes an elegantly simple PDZ-domain array that can identify potential interacting partners of GPCRs and other signaling molecules.
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Affiliation(s)
- Peter Day
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA
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53
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Gardner LA, Tavalin SJ, Goehring AS, Scott JD, Bahouth SW. AKAP79-mediated targeting of the cyclic AMP-dependent protein kinase to the beta1-adrenergic receptor promotes recycling and functional resensitization of the receptor. J Biol Chem 2006; 281:33537-53. [PMID: 16940053 DOI: 10.1074/jbc.m601809200] [Citation(s) in RCA: 63] [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
Resensitization of G protein-coupled receptors (GPCR) following prolonged agonist exposure is critical for restoring the responsiveness of the receptor to subsequent challenges by agonist. The 3'-5' cyclic AMP-dependent protein kinase (PKA) and serine 312 in the third intracellular loop of the human beta(1)-adrenergic receptor (beta(1)-AR) were both necessary for efficient recycling and resensitization of the agonist-internalized beta(1)-AR (Gardner, L. A., Delos Santos, N. M., Matta, S. G., Whitt, M. A., and Bahouth, S. W. (2004) J. Biol. Chem. 279, 21135-21143). Because PKA is compartmentalized near target substrates by interacting with protein kinase A anchoring proteins (AKAPs), the present study was undertaken to identify the AKAP involved in PKA-mediated phosphorylation of the beta(1)-AR and in its recycling and resensitization. Here, we report that Ht-31 peptide-mediated disruption of PKA/AKAP interactions prevented the recycling and functional resensitization of heterologously expressed beta(1)-AR in HEK-293 cells and endogenously expressed beta(1)-AR in SK-N-MC cells and neonatal rat cortical neurons. Whereas several endogenous AKAPs were identified in HEK-293 cells, small interfering RNA-mediated down-regulation of AKAP79 prevented the recycling of the beta(1)-AR in this cell line. Co-immunoprecipitations and fluorescence resonance energy transfer (FRET) microscopy experiments in HEK-293 cells revealed that the beta(1)-AR, AKAP79, and PKA form a ternary complex at the carboxyl terminus of the beta(1)-AR. This complex was involved in PKA-mediated phosphorylation of the third intracellular loop of the beta(1)-AR because disruption of PKA/AKAP interactions or small interfering RNA-mediated down-regulation of AKAP79 both inhibited this response. Thus, AKAP79 provides PKA to phosphorylate the beta(1)-AR and thereby dictate the recycling and resensitization itineraries of the beta(1)-AR.
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Affiliation(s)
- Lidia A Gardner
- Department of Pharmacology, University of Tennessee Health Sciences Center, Memphis, Tennessee 38163, USA
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54
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Gavarini S, Bécamel C, Altier C, Lory P, Poncet J, Wijnholds J, Bockaert J, Marin P. Opposite effects of PSD-95 and MPP3 PDZ proteins on serotonin 5-hydroxytryptamine2C receptor desensitization and membrane stability. Mol Biol Cell 2006; 17:4619-31. [PMID: 16914526 PMCID: PMC1635381 DOI: 10.1091/mbc.e06-03-0218] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
PSD-95/Disc large/Zonula occludens 1 (PDZ) domain-containing proteins (PDZ proteins) play an important role in the targeting and the trafficking of transmembrane proteins. Our previous studies identified a set of PDZ proteins that interact with the C terminus of the serotonin 5-hydroxytryptamine (5-HT)(2C) receptor. Here, we show that the prototypic scaffolding protein postsynaptic density-95 (PSD-95) and another membrane-associated guanylate kinase, MAGUK p55 subfamily member 3 (MPP3), oppositely regulate desensitization of the receptor response in both heterologous cells and mice cortical neurons in primary culture. PSD-95 increased desensitization of the 5-HT(2C) receptor-mediated Ca(2+) response, whereas MPP3 prevented desensitization of the Ca(2+) response. The effects of the PDZ proteins on the desensitization of the Ca(2+) response were correlated with a differential regulation of cell surface expression of the receptor. Additional experiments were performed to assess how PDZ proteins globally modulate desensitization of the 5-HT(2C) receptor response in neurons, by using a peptidyl mimetic of the 5-HT(2C) receptor C terminus fused to the human immunodeficiency virus type-1 Tat protein transduction domain, which disrupts interaction between the 5-HT(2C) receptor and PDZ proteins. Transduction of this peptide inhibitor into cultured cortical neurons increased the desensitization of the 5-HT(2C) receptor-mediated Ca(2+) response. This indicates that, overall, interaction of 5-HT(2C) receptors with PDZ proteins inhibits receptor desensitization in cortical neurons.
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Affiliation(s)
- Sophie Gavarini
- *Centre National de la Recherche Scientifique Unité Mixte de Recherche 5203, Institut National de la Santé et de la Recherche Médicale, U661, Université Montpellier I, Université Montpellier II, and Département de Neurobiologie, Institut de Génomique Fonctionnelle, F-34094 Montpellier Cedex 5, France
| | - Carine Bécamel
- *Centre National de la Recherche Scientifique Unité Mixte de Recherche 5203, Institut National de la Santé et de la Recherche Médicale, U661, Université Montpellier I, Université Montpellier II, and Département de Neurobiologie, Institut de Génomique Fonctionnelle, F-34094 Montpellier Cedex 5, France
| | - Christophe Altier
- Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada T2N 1N4; and
| | - Philippe Lory
- *Centre National de la Recherche Scientifique Unité Mixte de Recherche 5203, Institut National de la Santé et de la Recherche Médicale, U661, Université Montpellier I, Université Montpellier II, and Département de Neurobiologie, Institut de Génomique Fonctionnelle, F-34094 Montpellier Cedex 5, France
| | - Joël Poncet
- *Centre National de la Recherche Scientifique Unité Mixte de Recherche 5203, Institut National de la Santé et de la Recherche Médicale, U661, Université Montpellier I, Université Montpellier II, and Département de Neurobiologie, Institut de Génomique Fonctionnelle, F-34094 Montpellier Cedex 5, France
| | - Jan Wijnholds
- Department of Neuromedical Genetics, The Netherlands Institute for Neurosciences, Royal Netherlands Academy of Arts and Sciences, 1105 BA Amsterdam, The Netherlands
| | - Joël Bockaert
- *Centre National de la Recherche Scientifique Unité Mixte de Recherche 5203, Institut National de la Santé et de la Recherche Médicale, U661, Université Montpellier I, Université Montpellier II, and Département de Neurobiologie, Institut de Génomique Fonctionnelle, F-34094 Montpellier Cedex 5, France
| | - Philippe Marin
- *Centre National de la Recherche Scientifique Unité Mixte de Recherche 5203, Institut National de la Santé et de la Recherche Médicale, U661, Université Montpellier I, Université Montpellier II, and Département de Neurobiologie, Institut de Génomique Fonctionnelle, F-34094 Montpellier Cedex 5, France
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55
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Deng F, Price MG, Davis CF, Mori M, Burgess DL. Stargazin and other transmembrane AMPA receptor regulating proteins interact with synaptic scaffolding protein MAGI-2 in brain. J Neurosci 2006; 26:7875-84. [PMID: 16870733 PMCID: PMC6674230 DOI: 10.1523/jneurosci.1851-06.2006] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The spatial coordination of neurotransmitter receptors with other postsynaptic signaling and structural molecules is regulated by a diverse array of cell-specific scaffolding proteins. The synaptic trafficking of AMPA receptors by the stargazin protein in some neurons, for example, depends on specific interactions between the C terminus of stargazin and the PDZ [postsynaptic density-95 (PSD-95)/Discs large/zona occludens-1] domains of membrane-associated guanylate kinase scaffolding proteins PSD-93 or PSD-95. Stargazin [Cacng2 (Ca2+ channel gamma2 subunit)] is one of four closely related proteins recently categorized as transmembrane AMPA receptor regulating proteins (TARPs) that appear to share similar functions but exhibit distinct expression patterns in the CNS. We used yeast two-hybrid screening to identify MAGI-2 (membrane associated guanylate kinase, WW and PDZ domain containing 2) as a novel candidate interactor with the cytoplasmic C termini of the TARPs. MAGI-2 [also known as S-SCAM (synaptic scaffolding molecule)] is a multi-PDZ domain scaffolding protein that interacts with several different ligands in brain, including PTEN (phosphatase and tensin homolog), dasm1 (dendrite arborization and synapse maturation 1), dendrin, axin, beta- and delta-catenin, neuroligin, hyperpolarization-activated cation channels, beta1-adrenergic receptors, and NMDA receptors. We confirmed that MAGI-2 coimmunoprecipitated with stargazin in vivo from mouse cerebral cortex and used in vitro assays to localize the interaction to the C-terminal -TTPV amino acid motif of stargazin and the PDZ1, PDZ3, and PDZ5 domains of MAGI-2. Expression of stargazin recruited MAGI-2 to cell membranes and cell-cell contact sites in transfected HEK-293T cells dependent on the presence of the stargazin -TTPV motif. These experiments identify MAGI-2 as a strong candidate for linking TARP/AMPA receptor complexes to a wide range of other postsynaptic molecules and pathways and advance our knowledge of protein interactions at mammalian CNS synapses.
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56
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Zhang H, Wang D, Sun H, Hall RA, Chris Yun C. MAGI-3 regulates LPA-induced activation of Erk and RhoA. Cell Signal 2006; 19:261-8. [PMID: 16904289 PMCID: PMC1995035 DOI: 10.1016/j.cellsig.2006.06.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2006] [Accepted: 06/29/2006] [Indexed: 12/25/2022]
Abstract
Lysophosphatidic acids (LPA) exert multiple biological effects through specific G protein-coupled receptors. The LPA-activated receptor subtype LPA(2) contains a carboxyl-terminal motif that allows interaction with PDZ domain-containing proteins, such as NHERF2 and PDZ-RhoGEF. To identify additional interacting partners of LPA(2), the LPA(2) carboxyl-terminus was used to screen a proteomic array of PDZ domains. In addition to the previously identified NHERF2, several additional LPA(2)-interacting PDZ domains were found. These included MAGI-2, MAGI-3 and neurabin. In the present work, we demonstrate the specific interaction between LPA(2) and MAGI-3, and the effects of MAGI-3 in colon cancer cells using SW480 as a cell model. MAGI-3 specifically bound to LPA(2), but not to LPA(1) and LPA(3). This interaction was mediated via the fifth PDZ domain of MAGI-3 interacting with the carboxyl-terminal 4 amino acids of LPA(2), and mutational alteration of the carboxyl-terminal sequences of LPA(2) severely attenuated its ability to bind MAGI-3. LPA(2) also associated with MAGI-3 in cells as determined by co-affinity purification. Overexpression of MAGI-3 in SW480 cells showed no apparent effect on LPA-induced activation of Erk and Akt. In contrast, silencing of MAGI-3 expression by siRNA drastically inhibited LPA-induced Erk activation, suggesting that the lack of an effect by overexpression was due to the high endogenous MAGI-3 level in these cells. Previous studies have shown that the cellular signaling elicited by LPA results in activation of the small GTPase RhoA by Galpha(12/13) - as well as Galpha(q)-dependent pathways. Overexpression of MAGI-3 stimulated LPA-induced RhoA activation, whereas silencing of MAGI-3 by siRNA resulted in a small but statistically significant decrease in RhoA activation. These results demonstrate that MAGI-3 interacts directly with LPA(2) and regulates the ability of LPA(2) to activate Erk and RhoA.
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Affiliation(s)
- Huanchun Zhang
- Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Dongsheng Wang
- Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Hong Sun
- Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Randy A. Hall
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - C. Chris Yun
- Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA
- Department of Physiology, Emory University School of Medicine, Atlanta, GA 30322, USA
- * Corresponding author. Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA. Tel.: +1 404 712 2865; fax: +1 404 727 5767. E-mail address: (C.C. Yun)
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57
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Chen Z, Hague C, Hall RA, Minneman KP. Syntrophins regulate alpha1D-adrenergic receptors through a PDZ domain-mediated interaction. J Biol Chem 2006; 281:12414-20. [PMID: 16533813 DOI: 10.1074/jbc.m508651200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
To find novel cytoplasmic binding partners of the alpha1D-adrenergic receptor (AR), a yeast two-hybrid screen using the alpha1D-AR C terminus as bait was performed on a human brain cDNA library. Alpha-syntrophin, a protein containing one PDZ domain and two pleckstrin homology domains, was isolated in this screen as an alpha1D-AR-interacting protein. Alpha-syntrophin specifically recognized the C terminus of alpha1D- but not alpha1A- or alpha1B-ARs. In blot overlay assays, the PDZ domains of syntrophin isoforms alpha, beta1, and beta2 but not gamma1 or gamma2 showed strong selective interactions with the alpha1D-AR C-tail fusion protein. In transfected human embryonic kidney 293 cells, full-length alpha1D- but not alpha1A- or alpha1B-ARs co-immunoprecipitated with syntrophins, and the importance of the receptor C terminus for the alpha1D-AR/syntrophin interaction was confirmed using chimeric receptors. Mutation of the PDZ-interacting motif at the alpha1D-AR C terminus markedly decreased inositol phosphate formation stimulated by norepinephrine but not carbachol in transfected HEK293 cells. This mutation also dramatically decreased alpha1D-AR binding and protein expression. In addition, stable overexpression of alpha-syntrophin significantly increased alpha1D-AR protein expression and binding but did not affect those with a mutated PDZ-interacting motif, suggesting that syntrophin plays an important role in maintaining receptor stability by directly interacting with the receptor PDZ-interacting motif. This direct interaction may provide new information about the regulation of alpha1D-AR signaling and the role of syntrophins in modulating G protein-coupled receptor function.
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Affiliation(s)
- Zhongjian Chen
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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58
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He J, Bellini M, Inuzuka H, Xu J, Xiong Y, Yang X, Castleberry AM, Hall RA. Proteomic analysis of beta1-adrenergic receptor interactions with PDZ scaffold proteins. J Biol Chem 2005; 281:2820-7. [PMID: 16316992 DOI: 10.1074/jbc.m509503200] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Many G protein-coupled receptors possess carboxyl-terminal motifs ideal for interaction with PDZ scaffold proteins, which can control receptor trafficking and signaling in a cell-specific manner. To gain a panoramic view of beta1-adrenergic receptor (beta AR) interactions with PDZ scaffolds, the beta1AR carboxyl terminus was screened against a newly developed proteomic array of PDZ domains. These screens confirmed beta1AR associations with several previously identified PDZ partners, such as PSD-95, MAGI-2, GIPC, and CAL. Moreover, two novel beta1AR-interacting proteins, SAP97 and MAGI-3, were also identified. The beta1AR carboxyl terminus was found to bind specifically to the first PDZ domain of MAGI-3, with the last four amino acids (E-S-K-V) of beta1AR being the key determinants of the interaction. Full-length beta1AR robustly associated with full-length MAGI-3 in cells, and this association was abolished by mutation of the beta1AR terminal valine residue to alanine (V477A), as determined by co-immunoprecipitation experiments and immunofluorescence co-localization studies. MAGI-3 co-expression with beta1AR profoundly impaired beta1AR-mediated ERK1/2 activation but had no apparent effect on beta1AR-mediated cyclic AMP generation or agonist-promoted beta1AR internalization. These findings revealed that the interaction of MAGI-3 with beta1AR can selectively regulate specific aspects of receptor signaling. Moreover, the screens of the PDZ domain proteomic array provide a comprehensive view of beta1AR interactions with PDZ scaffolds, thereby shedding light on the molecular mechanisms by which beta1 AR signaling and trafficking can be regulated in a cell-specific manner.
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Affiliation(s)
- Junqi He
- Department of Biochemistry and Molecular Biology, Capital University of Medical Sciences, Beijing 100054, China
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59
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Lehtonen S, Ryan JJ, Kudlicka K, Iino N, Zhou H, Farquhar MG. Cell junction-associated proteins IQGAP1, MAGI-2, CASK, spectrins, and alpha-actinin are components of the nephrin multiprotein complex. Proc Natl Acad Sci U S A 2005; 102:9814-9. [PMID: 15994232 PMCID: PMC1175008 DOI: 10.1073/pnas.0504166102] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nephrin is a cell surface receptor of the Ig superfamily that localizes to slit diaphragms, the specialized junctions between the interdigitating foot processes of the glomerular epithelium (podocytes) in the kidney. Mutations in the NPHS1 gene encoding nephrin lead to proteinuria and congenital nephrotic syndrome, indicating that nephrin is essential for normal glomerular development and function. To identify nephrin-binding proteins, we performed mass spectrometry on proteins obtained from pull-down assays with GST-nephrin cytoplasmic domain. Nephrin specifically pulled down six proteins from glomerular lysates, MAGI-2/S-SCAM (membrane-associated guanylate kinase inverted 2/synaptic scaffolding molecule), IQGAP1 (IQ motif-containingGTPase-activatingprotein1),CASK(calcium/calmodulin-dependent serine protein kinase), alpha-actinin, alphaII spectrin, and betaII spectrin. All of these scaffolding proteins are often associated with cell junctions. By immunofluorescence these proteins are expressed in glomerular epithelial cells, where they colocalize with nephrin in the foot processes. During glomerular development, IQGAP1 is expressed in the junctional complexes between the earliest identifiable podocytes, MAGI-2/S-SCAM is first detected in junctional complexes in podocytes after their migration to the base of the cells. Thus, the nephrin-slit diaphragm protein complex contains a group of scaffolding proteins that function to connect junctional membrane proteins to the actin cytoskeleton and signaling cascades. Despite their special morphology and function, there is considerable compositional similarity between the podocyte slit diaphragm and typical junctional complexes of other epithelial cells.
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Affiliation(s)
- Sanna Lehtonen
- Departments of Cellular and Molecular Medicine and Pathology, and Ludwig Institute for Cancer Research, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
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60
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Calloe K, Elmedyb P, Olesen SP, Jorgensen NK, Grunnet M. Hypoosmotic cell swelling as a novel mechanism for modulation of cloned HCN2 channels. Biophys J 2005; 89:2159-69. [PMID: 15980171 PMCID: PMC1366717 DOI: 10.1529/biophysj.105.063792] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
This work demonstrates cell swelling as a new regulatory mechanism for the cloned hyperpolarization-activated, cyclic nucleotide-gated channel 2 (HCN2). HCN2 channels were coexpressed with aquaporin1 in Xenopus laevis oocytes and currents were monitored using a two-electrode voltage-clamp. HCN2 channels were activated by hyperpolarization to -100 mV and the currents were measured before and during hypoosmotic cell swelling. Cell swelling increased HCN2 currents by 30% without changing the kinetics of the currents. Injection of 50 nl intracellular solution resulted in a current increase of 20%, indicating that an increase in cell volume also under isoosmotic conditions may lead to activation of HCN2. In the absence of aquaporin1 only negligible changes in oocyte cell volume occur during exposure to hypoosmotic media and no significant change in HCN2 channel activity was observed during perfusion with hypoosmotic media. This indicates that cell swelling and not a change in ionic strength of the media, caused the observed swelling-induced increase in current. The increase in HCN2 current induced by cell swelling could be abolished by cytochalasin D treatment, indicating that an intact F-actin cytoskeleton is a prerequisite for the swelling-induced current.
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Affiliation(s)
- Kirstine Calloe
- Copenhagen Heart Arrhythmia Research Centre and Department of Medical Physiology, The Panum Institute, University of Copenhagen, Copenhagen, Denmark.
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61
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Franklin JL, Yoshiura K, Dempsey PJ, Bogatcheva G, Jeyakumar L, Meise KS, Pearsall RS, Threadgill D, Coffey RJ. Identification of MAGI-3 as a transforming growth factor-alpha tail binding protein. Exp Cell Res 2005; 303:457-70. [PMID: 15652357 DOI: 10.1016/j.yexcr.2004.10.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2004] [Revised: 10/14/2004] [Indexed: 01/02/2023]
Abstract
The cytoplasmic domain of the transforming growth factor-alpha precursor (proTGFalpha) contains a C-terminal PSD-95/SAP90, Discs Large, and Zona Occludens-1 (PDZ) recognition motif (TVV). By yeast two-hybrid screening of a mouse embryo library, we have found that a third member of a family of PDZ-containing proteins, membrane associated guanylate kinase inverted-3 (MAGI-3), binds to TGFalpha's TVV. MAGI-3 is widely expressed in multiple mouse tissues, including brain. Immunolocalization showed that MAGI-3 and TGFalpha were colocalized in neurons in the cortex and dentate gyrus, as well as in ependymal cells and some astrocytes. In vitro, proTGFalpha bound the PDZ-1 domain of MAGI-3 and MAGI-2, but not MAGI-1. MAGI-3 and the 17-kDa cell surface form of proTGFalpha interact transiently in MDCK cells stably transfected with both MAGI-3 and human proTGFalpha cDNAs. MAGI-3 and wild-type proTGFalpha colocalize at the cell surface. In contrast, MAGI-3 forms a stable complex with membrane-fixed TGFalpha early in the secretory pathway and interacts with immature and cell surface forms of membrane-fixed TGFalpha. Overexpression of MAGI-3 resulted in increased levels of TGFalpha in the basolateral medium of polarized MDCK cells, suggesting that MAGI-3 has a role in efficient trafficking of TGFalpha to the cell surface in polarized epithelial cells.
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Affiliation(s)
- Jeffrey L Franklin
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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62
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Kimura K, Kitano J, Nakajima Y, Nakanishi S. Hyperpolarization-activated, cyclic nucleotide-gated HCN2 cation channel forms a protein assembly with multiple neuronal scaffold proteins in distinct modes of protein-protein interaction. Genes Cells 2005; 9:631-40. [PMID: 15265006 DOI: 10.1111/j.1356-9597.2004.00752.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Hyperpolarization-activated cation currents, termed Ih, are non-uniformly distributed along dendritic arbors with current density increasing with increasing distance from the soma. The non-uniform distribution of Ih currents contributes to normalization of location-dependent variability in temporal integration of synaptic input, but the molecular basis for the graded HCN distribution remains to be investigated. The hyperpolarization-activated, cyclic nucleotide-gated cation channels (HCNs) underlie Ih currents and consist of four members (HCN1-HCN4) of the gene family in mammals. In this investigation, we report that HCN2 forms a protein assembly with tamalin, S-SCAM and Mint2 scaffold proteins, using several different approaches including immunoprecipitation of rat brain and heterologously expressing cell extracts and glutathione S-transferase pull-down assays. The PDZ domain of tamalin interacts with HCN2 at both the PDZ-binding motif and the internal carboxy-terminal tail of HCN2, whereas binding of the PDZ domain of S-SCAM occurs at the cyclic nucleotide-binding domain (CNBD) and the CNBD-downstream sequence of the carboxy-terminal tail of HCN2. A protein assembly between HCN2 and Mint2 is formed by the interaction of the munc18-interacting domain of Mint2 with the CNBD-downstream sequence of HCN2. The results demonstrate that HCN2 forms a protein complex with multiple neuronal scaffold proteins in distinct modes of protein-protein interaction.
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Affiliation(s)
- Kouji Kimura
- Department of Biological Sciences, Faculty of Medicine, and Department of Molecular and System Biology, Graduate School of Biostudies, Kyoto University, Yoshida Konoe-cho, Sakyo-ku, Kyoto, 606-8501, Japan
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63
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Subauste MC, Nalbant P, Adamson ED, Hahn KM. Vinculin Controls PTEN Protein Level by Maintaining the Interaction of the Adherens Junction Protein β-Catenin with the Scaffolding Protein MAGI-2. J Biol Chem 2005; 280:5676-81. [PMID: 15579911 DOI: 10.1074/jbc.m405561200] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PTEN is a frequently mutated tumor suppressor in malignancies. Interestingly, some malignancies exhibit undetectable PTEN protein without mutations or loss of PTEN mRNA. The cause(s) for this reduction in PTEN is unknown. Cancer cells frequently exhibit loss of cadherin, beta-catenin, alpha-catenin and/or vinculin, key elements of adherens junctions. Here we show that F9 vinculin-null (vin(-/-)) cells lack PTEN protein despite normal PTEN mRNA levels. Their PTEN protein expression was restored by transfection with vinculin or by inhibition of PTEN degradation. F9 vin(-/-) cells express PTEN protein upon transfection with a vinculin fragment (amino acids 243-1066) that is capable of interacting with alpha-catenin but unable to target into focal adhesions. On the other hand, disruption of adherens junctions with an E-cadherin blocking antibody reduced PTEN protein to undetectable levels in wild-type F9 cells. PTEN protein levels were restored in F9 vin(-/-) cells upon transfection with an E-cadherin-alpha-catenin fusion protein, which targets into adherens junctions and interacts with beta-catenin in F9 vin(-/-) cells. beta-Catenin is known to interact with MAGI-2. MAGI-2 interaction with PTEN in the cell membrane is known to prevent PTEN protein degradation. Thus, MAGI-2 overexpression in F9 vin(-/-) cells restored PTEN protein levels. Moreover, expression of vinculin mutants that reinstated the disrupted interactions of beta-catenin with MAGI-2 in F9 vin(-/-) cells also restored PTEN protein levels. These studies indicate that PTEN protein levels are dependent on the maintenance of beta-catenin-MAGI-2 interaction, in which vinculin plays a critical role.
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Affiliation(s)
- M Cecilia Subauste
- Department of Cell Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037, USA.
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64
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Abstract
G protein-coupled receptors (GPCR) interact not only with heterotrimeric G proteins but also with accessory proteins called GPCR interacting proteins (GIP). These proteins have important functions. They are implicated in GPCR targeting to specific cellular compartments, in their assembling into large functional complexes called "receptosomes," in their trafficking to and from the plasma membrane, and in the fine-tuning of their signaling properties. There are several types of GIPs. Some are transmembrane proteins such as another GPCR (homodimerization and heterodimerization), ionic channels, ionotropic receptors, and single transmembrane proteins. The latter is implicated in the fine-tuning of receptor pharmacology or signaling. Other GIPs are soluble proteins interacting mainly with the "magic" C-terminal tail. Among them, PDZ domain-containing proteins are the most abundant. They generally, but not always, interact with the extreme C-terminal domain of GPCRs. Some GIPs interact with specific sequences of the C-terminal such as the Homer binding sequence (-PPxxFR-), the dopamine receptor interacting protein (DRIP) binding sequence (-FxxxFxxxF-), etc. Finally, only few GIPs have been found thus far to interact with the third intracellular loop of GPCRs. The future will tell us if this situation is only due to technical reasons.
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Affiliation(s)
- Joël Bockaert
- UPR CNRS 2580, CCIPE, 141 Rue de la Cardonille, 34094 Montpellier Cedex 5, France.
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65
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Scott DB, Michailidis I, Mu Y, Logothetis D, Ehlers MD. Endocytosis and degradative sorting of NMDA receptors by conserved membrane-proximal signals. J Neurosci 2005; 24:7096-109. [PMID: 15306643 PMCID: PMC6729175 DOI: 10.1523/jneurosci.0780-04.2004] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Regulation of the abundance of NMDA receptors (NMDARs) at excitatory synapses is critical during changes in synaptic efficacy underlying learning and memory as well as during synapse formation throughout neural development. However, the molecular signals that govern NMDAR delivery, maintenance, and internalization remain unclear. In this study, we identify a conserved family of membrane-proximal endocytic signals, two within the NMDAR type 1 (NR1) subunit and one within the NR2A and NR2B subunits, necessary and sufficient to drive the internalization of NMDARs. These endocytic motifs reside in the region of NMDAR subunits immediately after the fourth membrane segment, a region implicated in use-dependent rundown and NMDA channel inactivation. Although endocytosis driven by the distal C-terminal domain of NR2B is followed by rapid recycling, internalization mediated by membrane-proximal motifs selectively targets receptors to late endosomes and accelerates degradation. These results define a novel conserved signature of NMDARs regulating internalization and postendocytic trafficking.
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Affiliation(s)
- Derek B Scott
- Program in Cell and Molecular Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
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66
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Meyer G, Varoqueaux F, Neeb A, Oschlies M, Brose N. The complexity of PDZ domain-mediated interactions at glutamatergic synapses: a case study on neuroligin. Neuropharmacology 2005; 47:724-33. [PMID: 15458844 DOI: 10.1016/j.neuropharm.2004.06.023] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2004] [Revised: 06/26/2004] [Accepted: 06/30/2004] [Indexed: 11/30/2022]
Abstract
The postsynaptic specialisation at glutamatergic synapses is composed of a network of proteins located within the membrane and the underlying postsynaptic density. The strong interconnectivity between the protein components is mediated by a limited number of interaction modes. Particularly abundant are PDZ domain-mediated interactions. An obstacle in understanding the fidelity of postsynaptic processes involving PDZ domains is the high degree of overlap with respect to their binding specificities. Focussing on transsynaptic adhesion molecules, we used the yeast two-hybrid system to obtain an overview of the binding specificities of selected C-terminal PDZ binding motifs. Neuroligin, a postsynaptic cell surface protein that spans the synaptic cleft and interacts with beta-neurexin, served as a starting point. Neuroligin binds to the PDZ domain-containing proteins PSD95, SAP102, Chapsyn110, S-SCAM, Magi1 and 3, Shank1 and 3, Pick1, GOPC, SPAR, Semcap3 and PDZ-RGS3. Next, we examined the relationship between neuroligin and synaptic cell adhesion molecules or glutamate receptor subunits with respect to PDZ-mediated interactions. We found a limited overlap in the PDZ-domain binding specificities of neuroligin with those of Sidekick2 and Ephrin-B2. In contrast, Syndecan2 and IgSF4 show no overlap with the PDZ-domain specificity of neuroligin, instead, they bind to GRIP and syntenin. The AMPA receptor subunit GluR2 interacts with Semcap3 and PDZ-RGS3, whereas the kainate receptor subunits GluR5 and GluR6 show weak interactions with PSD95. In summary, we can sketch a complex pattern of overlap in the binding specificities of synaptic cell surface proteins towards PDZ-domain proteins.
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Affiliation(s)
- Guido Meyer
- Max-Planck-Institute for Experimental Medicine, Department of Molecular Neurobiology, Deutsche Forschungsgemeinschaft Centre for Molecular Physiology of the Brain, Hermann-Rein-Strasse 3, D-37075 Göttingen, Germany.
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67
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Abstract
The three subtypes of beta-adrenergic receptor (beta AR) all interact with G proteins as a central aspect of their signaling. The various beta AR subtypes also associate differentially with a variety of other cytoplasmic and transmembrane proteins. These beta AR-interacting proteins play distinct roles in the regulation of receptor signaling and trafficking. The specificity of beta AR associations with various binding partners can help to explain key physiological differences between beta AR subtypes. Moreover, the differential tissue expression patterns of many of the beta AR-interacting proteins may contribute to tissue-specific regulation of beta AR function.
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Affiliation(s)
- Randy A Hall
- Department of Pharmacology, Rollins Research Center, Emory University School of Medicine, 5113 Rollins Research Center, 1510 Clifton Rd., Atlanta, GA 30322, USA.
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68
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Gage RM, Matveeva EA, Whiteheart SW, von Zastrow M. Type I PDZ ligands are sufficient to promote rapid recycling of G Protein-coupled receptors independent of binding to N-ethylmaleimide-sensitive factor. J Biol Chem 2004; 280:3305-13. [PMID: 15548537 DOI: 10.1074/jbc.m406934200] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Molecular sorting of G protein-coupled receptors (GPCRs) between divergent recycling and lysosomal pathways determines the functional consequences of agonist-induced endocytosis. The carboxyl-terminal cytoplasmic domain of the beta2 adrenergic receptor (beta2AR) mediates both PDZ binding to Na+/H+ exchanger regulatory factor/ezrin/radixin/moesin-binding phosphoprotein of 50 kDa (NHERF/EBP50) family proteins and non-PDZ binding to the N-ethylmaleimide-sensitive factor (NSF). We have investigated whether PDZ interaction(s) are actually sufficient to promote rapid recycling of endocytosed receptors and, if so, whether PDZ-mediated sorting is restricted to the beta2AR tail or to sequences that bind NHERF/EBP50. The trafficking effects of short (10 residue) sequences differing in PDZ and NSF binding properties were examined using chimeric mutant receptors. The recycling activity of the beta2AR-derived tail sequence was not blocked by a point mutation that selectively disrupts binding to NSF, and naturally occurring PDZ ligand sequences were identified that do not bind detectably to NSF yet function as strong recycling signals. The carboxyl-terminal cytoplasmic domain of the beta1-adrenergic receptor, which does not bind either to NSF or NHERF/EBP50 and interacts selectively with a distinct group of PDZ proteins, promoted rapid recycling of chimeric mutant receptors with efficiency similarly high as that of the beta2AR tail. These results indicate that PDZ domain-mediated protein interactions are sufficient to promote rapid recycling of GPCRs, independent of binding to NSF. They also suggest that PDZ-directed recycling is a rather general mechanism of GPCR regulation, which is not restricted to a single GPCR, and may involve additional PDZ domain-containing protein(s) besides NHERF/EBP50.
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Affiliation(s)
- Robert M Gage
- Department of Pharmaceutical Chemistry, University of California at San Francisco, San Francisco California 94143, USA
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69
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He J, Bellini M, Xu J, Castleberry AM, Hall RA. Interaction with Cystic Fibrosis Transmembrane Conductance Regulator-associated Ligand (CAL) Inhibits β1-Adrenergic Receptor Surface Expression. J Biol Chem 2004; 279:50190-6. [PMID: 15358775 DOI: 10.1074/jbc.m404876200] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
G protein-coupled receptors such as the beta1-adrenergic receptor (beta1AR) must be trafficked to the plasma membrane in order to bind with their extracellular ligands and regulate cellular physiology. By using glutathione S-transferase pull-down techniques, we found that the beta1AR carboxyl terminus directly interacts with the cystic fibrosis transmembrane conductance regulator-associated ligand (CAL; also known as PIST, GOPC, and FIG), a protein known to be primarily localized to the Golgi apparatus. CAL contains two predicted coiled-coil domains and one PSD-95/Discs-large/ZO-1 homology (PDZ) domain. The beta1AR carboxyl terminus (CT) binds to the PDZ domain of CAL, with the last few amino acids (ESKV) of the beta1AR-CT being the key determinants for the interaction. Mutation of the terminal valine residue resulted in markedly reduced association of the beta1AR-CT with CAL. Numerous other mutations to the ESKV motif also impaired the beta1AR-CT/CAL interaction, suggesting that this motif is close to optimal for association with the CAL PDZ domain. In cells, full-length beta1AR robustly associates with CAL, and this interaction is abolished by mutation of the terminal valine to alanine of the receptor (V477A), as determined by co-immunoprecipitation experiments and immunofluorescence co-localization studies. Consistent with observations that CAL is a Golgi-associated protein, overexpression of CAL reduces surface expression of beta1AR. Interaction with CAL promotes retention of beta1AR within the cell, whereas PSD-95, another beta1AR-associated PDZ domain-containing protein, competitively blocks beta1AR association with CAL and promotes receptor trafficking to the cell surface. These data reveal that CAL, a novel beta1AR-binding partner, modulates beta1AR intracellular trafficking, thereby revealing a new mechanism of regulation for beta1AR anterograde trafficking through the endoplasmic reticulum-Golgi complex to the plasma membrane.
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Affiliation(s)
- Junqi He
- Department of Pharmacology, Rollins Research Center, Emory University, School of Medicine, Atlanta, GA 30322, USA.
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70
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Joubert L, Hanson B, Barthet G, Sebben M, Claeysen S, Hong W, Marin P, Dumuis A, Bockaert J. New sorting nexin (SNX27) and NHERF specifically interact with the 5-HT4a receptor splice variant: roles in receptor targeting. J Cell Sci 2004; 117:5367-79. [PMID: 15466885 DOI: 10.1242/jcs.01379] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The 5-hydroxytryptamine type 4 receptor (5-HT4R) is involved in learning, feeding, respiratory control and gastrointestinal transit. This receptor is one of the G-protein-coupled receptors for which alternative mRNA splicing generates the most variants that differ in their C-terminal extremities. Some 5-HT4R variants (a, e and f) express canonical PDZ ligands at their C-termini. Here, we have examined whether some mouse 5-HT4R variants associate with specific sets of proteins, using a proteomic approach based on peptide-affinity chromatography, two-dimensional electrophoresis and mass spectrometry. We have identified ten proteins that interact specifically with the 5-HT4(a)R and three that only associate with the 5-HT4(e)R. Most of them are PDZ proteins. Among the proteins that associated specifically with the 5-HT4(a)R variant, NHERF greatly modified its subcellular localization. Moreover, NHERF recruited the 5-HT4(a)R to microvilli, where it localized with activated ezrin, consistent with the role of 5-HT4(a)R in cytoskeleton remodelling. The 5-HT4(a)R also interacted with both the constitutive and inducible (upon methamphetamine treatment) forms of the recently cloned sorting nexin 27 (SNX27a and b, respectively). We found that SNX27a redirected part of 5-HT4(a)R to early endosomes. The interaction of the 5-HT4R splice variants with distinct sets of PDZ proteins might specify their cellular localization as well as their signal transduction properties.
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MESH Headings
- Alternative Splicing
- Amino Acid Sequence
- Animals
- Brain/metabolism
- Carrier Proteins/metabolism
- Carrier Proteins/physiology
- Cell Line, Tumor
- Chromatography
- Cytoskeletal Proteins
- Cytoskeleton/metabolism
- Electrophoresis, Gel, Two-Dimensional
- Humans
- Immunoprecipitation
- Mass Spectrometry
- Methamphetamine/pharmacology
- Mice
- Microscopy, Confocal
- Molecular Sequence Data
- NIH 3T3 Cells
- Neurons/metabolism
- Peptides/chemistry
- Phosphoproteins/chemistry
- Phosphoproteins/metabolism
- Phosphoproteins/physiology
- Plasmids/metabolism
- Protein Binding
- Protein Structure, Tertiary
- Proteomics
- Receptors, Serotonin, 5-HT4/metabolism
- Receptors, Serotonin, 5-HT4/physiology
- Signal Transduction
- Sodium-Hydrogen Exchangers
- Sorting Nexins
- Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
- Transfection
- Vesicular Transport Proteins
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Affiliation(s)
- Lara Joubert
- Laboratoire de Génomique Fonctionnelle, CNRS UPR2580, CCIPE, 141 rue de la Cardonille, 34094 Montpellier CEDEX 05, France
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71
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Yamada A, Irie K, Deguchi-Tawarada M, Ohtsuka T, Takai Y. Nectin-dependent localization of synaptic scaffolding molecule (S-SCAM) at the puncta adherentia junctions formed between the mossy fibre terminals and the dendrites of pyramidal cells in the CA3 area of the mouse hippocampus. Genes Cells 2004; 8:985-94. [PMID: 14750953 DOI: 10.1046/j.1356-9597.2003.00690.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Two types of intercellular junctions, synaptic junctions (SJs) and puncta adherentia junctions (PAs), are observed at the synapses between the mossy fibre terminals and the dendrites of pyramidal cells in the CA3 area of the hippocampus. SJs are associated with active zones and postsynaptic densities (PSDs) where neurotransmission occurs, whereas PAs are not associated with either of them. We have found that the nectin-afadin unit as well as the N-cadherin-catenin unit localizes at the PAs and that both the units cooperatively organize the PAs. Nectins are Ca2+-independent Ig-like cell-cell adhesion molecules and afadin is a nectin- and actin filament-binding protein that connects nectins to the actin cytoskeleton. Synaptic scaffolding molecule (S-SCAM) is a neural scaffolding protein which interacts with many proteins including neuroligin, NMDA receptors, neural plakophilin-related armadillo-repeat protein/delta-catenin, a GDP/GTP exchange protein for Rap1 small G protein (PDZ-Rap-GEP), and beta-catenin. S-SCAM has been suggested to be a component of PSDs, but its precise localization at the synapses remains unknown. RESULTS S-SCAM was not concentrated at the PSDs but highly concentrated and co-localized with nectins at both the sides of the PAs formed between the mossy fibre terminals and the dendrites of pyramidal cells in the CA3 area of the adult mouse hippocampus. S-SCAM co-localized with nectin-1 at the primitive synapses where the SJs and the PAs were not morphologically differentiated, and they co-localized during the maturation of the SJs and the PAs. Nectin-1 had a potency to recruit S-SCAM to the nectin-1-based cell-cell adhesion sites formed in cadherin-deficient L cells as a model system. This recruitment was dependent on the C-terminal PDZ domain-binding motif of nectin-1 which is necessary for the binding of afadin, suggesting that nectins recruit S-SCAM through afadin. Consistently, S-SCAM was co-immunoprecipitated with afadin by the anti-S-SCAM antibody from the mouse brain, but S-SCAM did not directly bind afadin. CONCLUSION These results indicate that S-SCAM localizes at the PAs in the CA3 area of the hippocampus in a nectin-dependent manner and suggest that S-SCAM serves as a scaffolding molecule at the PAs after maturation of the synapses and at the SJs during the maturation.
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Affiliation(s)
- Akio Yamada
- Department of Molecular Biology and Biochemistry, Osaka University Graduate School of Medicine/Faculty of Medicine, Suita 565-0871, Japan
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72
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Heydorn A, Søndergaard BP, Ersbøll B, Holst B, Nielsen FC, Haft CR, Whistler J, Schwartz TW. A library of 7TM receptor C-terminal tails. Interactions with the proposed post-endocytic sorting proteins ERM-binding phosphoprotein 50 (EBP50), N-ethylmaleimide-sensitive factor (NSF), sorting nexin 1 (SNX1), and G protein-coupled receptor-associated sorting protein (GASP). J Biol Chem 2004; 279:54291-303. [PMID: 15452121 DOI: 10.1074/jbc.m406169200] [Citation(s) in RCA: 139] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Adaptor and scaffolding proteins determine the cellular targeting, the spatial, and thereby the functional association of G protein-coupled seven-transmembrane receptors with co-receptors, transducers, and downstream effectors and the adaptors determine post-signaling events such as receptor sequestration through interactions, mainly with the C-terminal intracellular tails of the receptors. A library of tails from 59 representative members of the super family of seven-transmembrane receptors was probed as glutathione S-transferase fusion proteins for interactions with four different adaptor proteins previously proposed to be involved in post-endocytotic sorting of receptors. Of the two proteins suggested to target receptors for recycling to the cell membrane, which is the route believed to be taken by a majority of receptors, ERM (ezrin-radixin-moesin)-binding phosphoprotein 50 (EBP50) bound only a single receptor tail, i.e. the beta(2)-adrenergic receptor, whereas N-ethylmaleimide-sensitive factor bound 11 of the tail-fusion proteins. Of the two proteins proposed to target receptors for lysosomal degradation, sorting nexin 1 (SNX1) bound 10 and the C-terminal domain of G protein-coupled receptor-associated sorting protein bound 23 of the 59 tail proteins. Surface plasmon resonance analysis of the binding kinetics of selected hits from the glutathione S-transferase pull-down experiments, i.e. the tails of the virally encoded receptor US28 and the delta-opioid receptor, confirmed the expected nanomolar affinities for interaction with SNX1. Truncations of the NK(1) receptor revealed that an extended binding epitope is responsible for the interaction with both SNX1 and G protein-coupled receptor-associated sorting protein as well as with N-ethylmaleimide-sensitive factor. It is concluded that the tail library provides useful information on the general importance of certain adaptor proteins, for example, in this case, ruling out EBP50 as being a broad spectrum-recycling adaptor.
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MESH Headings
- Amino Acid Sequence
- Carrier Proteins/metabolism
- Cell Membrane/chemistry
- Cell Membrane/metabolism
- Endocytosis
- Gene Deletion
- Glutathione Transferase/genetics
- Humans
- Lysosomes/metabolism
- Molecular Sequence Data
- Mutagenesis
- Peptide Fragments/chemistry
- Peptide Fragments/genetics
- Peptide Fragments/metabolism
- Peptide Library
- Phosphoproteins
- Receptors, Adrenergic, beta-2/chemistry
- Receptors, Adrenergic, beta-2/genetics
- Receptors, Adrenergic, beta-2/metabolism
- Receptors, Cell Surface/chemistry
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Receptors, Opioid, delta/chemistry
- Receptors, Opioid, delta/genetics
- Receptors, Opioid, delta/metabolism
- Receptors, Tachykinin/chemistry
- Receptors, Tachykinin/genetics
- Receptors, Tachykinin/metabolism
- Recombinant Fusion Proteins/metabolism
- Sodium-Hydrogen Exchangers/metabolism
- Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins
- Surface Plasmon Resonance
- Vesicular Transport Proteins/metabolism
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Affiliation(s)
- Arne Heydorn
- Laboratory for Molecular Pharmacology, Department of Pharmacology, Panum Institute, University of Copenhagen, DK-2200 Copenhagen, Denmark
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73
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Nagayama S, Iiizumi M, Katagiri T, Toguchida J, Nakamura Y. Identification of PDZK4, a novel human gene with PDZ domains, that is upregulated in synovial sarcomas. Oncogene 2004; 23:5551-7. [PMID: 15077175 DOI: 10.1038/sj.onc.1207710] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In an earlier study designed to investigate molecular mechanisms of carcinogenesis in synovial sarcomas (SSs), we applied a cDNA microarray to detect human genes with significantly increased expression in SS cells. Among the genes selected in this way, we identified a novel transcript, subsequently designated PDZK4 (PDZ domain-containing 4), that was specifically upregulated in all of the 13 SS cases we examined. On Northern blots of normal human tissues, the PDZK4 transcript was expressed only in fetal brain. Immunocytochemical staining of transfected COS7 cells showed that the PDZK4 gene product localized mainly under the plasma membrane. Treatment of human SS cells with small interfering RNA (siRNA) inhibited the expression of PDZK4 and resulted in the suppression of tumor-cell growth. Induction of exogenous PDZK4 expression promoted growth of T98G and COS7 cells in which no endogenous expression of PDZK4 was observed. Taken together, these findings strongly suggest that inappropriate expression of PDZK4 might play an important role in the proliferation of SS cells and that the gene might be a suitable molecular target for designing of novel drugs to treat SS patients.
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Affiliation(s)
- Satoshi Nagayama
- Laboratory of Molecular Medicine, Human Genome Center, Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
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74
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Rebois R, Allen BG, Hébert TE. The targetable G protein proteome: where is the next generation of drug targets? ACTA ACUST UNITED AC 2004. [DOI: 10.1016/s1741-8372(04)02429-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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75
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Patterson AJ, Zhu W, Chow A, Agrawal R, Kosek J, Xiao RP, Kobilka B. Protecting the myocardium: a role for the beta2 adrenergic receptor in the heart. Crit Care Med 2004; 32:1041-8. [PMID: 15071399 DOI: 10.1097/01.ccm.0000120049.43113.90] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVE The sympathetic nervous system enhances cardiac muscle function by activating beta adrenergic receptors (betaARs). Recent studies suggest that chronic betaAR stimulation is detrimental, however, and that it may play a role in the clinical deterioration of patients with congestive heart failure. To examine the impact of chronic beta1AR and beta2AR subtype stimulation individually, we studied the cardiovascular effects of catecholamine infusions in betaAR subtype knockout mice (beta1KO, beta2KO). DESIGN Prospective, randomized, experimental study. SETTING Animal research laboratory. SUBJECTS beta1KO and beta2KO mice and wild-type controls. INTERVENTIONS The animals were subjected to 2 wks of continuous infusion of the betaAR agonist isoproterenol. Analyses of cardiac function and structure were performed during and 3 days after completion of the infusions. Functional studies included graded exercise treadmill testing, in vivo assessments of left ventricular function using Mikro-Tip catheter transducers, right ventricular pressure measurements, and analyses of organ weight to body weight ratios. Structural studies included heart weight measurements, assessments of myocyte ultrastructure using electron microscopy, and in situ terminal deoxynucleotidyl transferase-mediated biotin-dUTP nick-end labeling staining to quantitate myocyte apoptosis. MEASUREMENTS AND MAIN RESULTS We found that isoproterenol-treated beta2KO mice experienced greater mortality rates (p =.001, chi-square test using Fisher's exact method) and increased myocyte apoptosis at 3- and 7-day time points (p =.04 and p =.0007, respectively, two-way analysis of variance). CONCLUSION The results of this study suggest that in vivo beta2AR activation is antiapoptotic and contributes to myocardial protection.
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MESH Headings
- Adrenergic beta-Agonists/pharmacology
- Animals
- Apoptosis/drug effects
- Exercise Test/drug effects
- Heart/innervation
- Infusions, Intravenous
- Isoproterenol/pharmacology
- Male
- Mice
- Mice, Knockout
- Microscopy, Electron
- Myocardial Contraction/drug effects
- Myocardium/pathology
- Receptors, Adrenergic, beta-1/drug effects
- Receptors, Adrenergic, beta-1/genetics
- Receptors, Adrenergic, beta-2/drug effects
- Receptors, Adrenergic, beta-2/genetics
- Survival Rate
- Sympathetic Nervous System/drug effects
- Ventricular Function, Left/drug effects
- Ventricular Function, Right/drug effects
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76
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Gardner LA, Delos Santos NM, Matta SG, Whitt MA, Bahouth SW. Role of the Cyclic AMP-dependent Protein Kinase in Homologous Resensitization of the β1-Adrenergic Receptor. J Biol Chem 2004; 279:21135-43. [PMID: 14990580 DOI: 10.1074/jbc.m313652200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A fundamental question in biology is how the various motifs in G protein-coupled receptors participate in the divergent functions orchestrated by these molecules. Here we describe a fundamental role for a serine residue at position 312 in the third intracellular loop of the human beta(1)-adrenergic receptor (beta(1)-AR) in endocytic recycling of the agonist-internalized receptor. In receptor recycling experiments that were monitored by confocal microscopy, the agonist-internalized wild-type (WT) beta(1)-AR recycled with a t(0.5) of 14 +/- 3 min. Mutagenesis of Ser(312) to alanine (Ser(312) --> Ala beta(1)-AR) or to the phosphoserine mimic aspartic acid (Ser(312) --> Asp beta(1)-AR) resulted in beta(1)-AR constructs that were pharmacologically indistinguishable from the WT beta(1)-AR. The internalized Ser(312) --> Asp beta(1)-AR recycled efficiently with a t(0.5) of 11 +/- 3 min, whereas the internalized Ser(312) --> Ala beta(1)-AR was not recycled or functionally resensitized through the endosomal pathway. Because this serine is a putative residue for phosphorylation by the cyclic AMP-dependent protein kinase (PKA), we examined the role of this kinase in recycling of the internalized beta(1)-AR. Inhibition of PKA biochemically or genetically using a dominant negative PKA construct blocked the recycling of the internalized WT beta(1)-AR. Phosphorylation studies revealed that the beta(1)-AR is partially phosphorylated by PKA and that phosphorylation of the beta(1)-AR by the catalytic subunit of PKA occurs exclusively at Ser(312). Our results identify a new signaling paradigm in which homologous activation of a kinase provides a reversible modification that shifts the itinerary of the internalized receptor toward recycling and resensitization. Therefore, PKA-mediated phosphorylation of G protein-coupled receptors might result in motif-dependent desensitization or resensitization.
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Affiliation(s)
- Lidia A Gardner
- Pharmacology and Molecular Sciences, University of Tennessee Health Sciences Center, 874 Union Avenue, Memphis, TN 38163, USA
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77
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Liang W, Curran PK, Hoang Q, Moreland RT, Fishman PH. Differences in endosomal targeting of human (beta)1- and (beta)2-adrenergic receptors following clathrin-mediated endocytosis. J Cell Sci 2004; 117:723-34. [PMID: 14734649 DOI: 10.1242/jcs.00878] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The beta(2)-adrenergic receptor (beta(2)AR) undergoes agonist-mediated endocytosis via clathrin-coated pits by a process dependent on both arrestins and dynamin. Internalization of some G protein-coupled receptors, however, is independent of arrestins and/or dynamin and through other membrane microdomains such as caveolae or lipid rafts. The human beta(1)AR is less susceptible to agonist-mediated internalization than the beta(2)-subtype, and its endocytic route, which is unknown, may be different. We have found that (i) co-expression of arrestin-2 or -3 enhanced the internalization of both subtypes whereas co-expression of dominant-negative mutants of arrestin-2 or dynamin impaired their internalization, as did inhibitors of clathrin-mediated endocytosis. (ii) Agonist stimulation increased the phosphorylation of beta(2)AR but not beta(1)AR. (iii) In response to agonist, each subtype redistributed from the cell surface to a distinct population of cytoplasmic vesicles; those containing beta(1)AR were smaller and closer to the plasma membrane whereas those containing beta(2)AR were larger and more perinuclear. (iv) When subcellular fractions from agonist-treated cells were separated by sucrose density gradient centrifugation, all of the internalized beta(2)AR appeared in the lighter endosomal-containing fractions whereas some of the internalized beta(1)AR remained in the denser plasma membrane-containing fractions. (v) Both subtypes recycled with similar kinetics back to the cell surface upon removal of agonist; however, recycling of beta(2)AR but not beta(1)AR was inhibited by monensin. Based on these results, we propose that the internalization of beta(1)AR is both arrestin- and dynamin-dependent and follows the same clathrin-mediated endocytic pathway as beta(2)AR. But during or after endocytosis, beta(1)AR and beta(2)AR are sorted into different endosomal compartments.
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Affiliation(s)
- Wei Liang
- Membrane Biochemistry Section, Laboratory of Molecular and Cellular Neurobiology, National Institute of Neurological Disorders and Stroke, The National Institutes of Health, Bethesda, MD 20892, USA
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78
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Liang W, Austin S, Hoang Q, Fishman PH. Resistance of the human beta 1-adrenergic receptor to agonist-mediated down-regulation. Role of the C terminus in determining beta-subtype degradation. J Biol Chem 2003; 278:39773-81. [PMID: 12888573 DOI: 10.1074/jbc.m304482200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Prolonged agonist stimulation results in down-regulation of most G protein-coupled receptors. When we exposed baby hamster kidney cells stably expressing the human beta1-adrenergic receptor (beta 1AR) to agonist over a 24-h period, we instead observed an increase of approximately 30% in both beta 1AR binding activity and immune-detected receptors. In contrast, beta 2AR expressed in these cells exhibited a decrease of > or =50%. We determined that the basal turnover rates of the two subtypes were similar (t(1/2) approximately 7 h) and that agonist stimulation increased beta 2AR but not beta 1AR turnover. Blocking receptor trafficking to lysosomes with bafilomycin A1 had no effect on basal turnover of either subtype but blocked agonist-stimulated beta 2AR turnover. As beta 1AR mRNA levels increased in agonist-stimulated cells, beta 1AR up-regulation appeared to result from increased synthesis with no change in degradation. To explore the basis for the subtype differences, we expressed chimeras in which the C termini had been exchanged. Each chimera responded to persistent agonist stimulation based on the source of its C-tail; beta 1AR with a beta 2AR C-tail underwent down-regulation, and beta 2AR with a beta 1AR C-tail underwent up-regulation. The C-tails had a corresponding effect on agonist-stimulated receptor phosphorylation and internalization with the order being beta 2AR > beta 1AR with beta 2AR C-tail > beta 2AR with a beta 1AR C-tail > beta 1AR. As internalization may be a prerequisite for down-regulation, we addressed this possibility by co-expressing each subtype with arrestin-2. Although beta 1AR internalization was increased to that of beta 2AR, down-regulation still did not occur. Instead, beta 1AR accumulated inside the cells. We conclude that in unstimulated cells, both subtypes appear to be turned over by the same mechanism. Upon agonist stimulation, both subtypes are internalized, and beta 2AR but not beta 1AR undergoes lysosomal degradation, the fate of each subtype being regulated by determinants in its C-tail.
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MESH Headings
- Adrenergic beta-Agonists/pharmacology
- Amino Acid Sequence
- Animals
- Base Sequence
- Cell Line
- Cricetinae
- DNA, Complementary/genetics
- Down-Regulation/drug effects
- Humans
- Kinetics
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptors, Adrenergic, beta-1/chemistry
- Receptors, Adrenergic, beta-1/drug effects
- Receptors, Adrenergic, beta-1/genetics
- Receptors, Adrenergic, beta-1/metabolism
- Receptors, Adrenergic, beta-2/chemistry
- Receptors, Adrenergic, beta-2/drug effects
- Receptors, Adrenergic, beta-2/genetics
- Receptors, Adrenergic, beta-2/metabolism
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Recombinant Proteins/chemistry
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
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Affiliation(s)
- Wei Liang
- Membrane Biochemistry Section, Laboratory of Molecular and Cellular Neurobiology, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
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79
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Xiang Y, Kobilka B. The PDZ-binding motif of the beta2-adrenoceptor is essential for physiologic signaling and trafficking in cardiac myocytes. Proc Natl Acad Sci U S A 2003; 100:10776-81. [PMID: 12954981 PMCID: PMC196879 DOI: 10.1073/pnas.1831718100] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
beta1- and beta2-adrenergic receptors (AR) regulate cardiac myocyte function through distinct signaling pathways. In addition to regulating cardiac rate and contractility, beta1AR and beta2AR may play different roles in the pathogenesis of heart failure. Studies on neonatal cardiac myocytes from beta1AR and beta2AR knockout mice suggest that subtype-specific signaling is determined by subtype-specific membrane targeting and trafficking. Stimulation of beta2ARs has a biphasic effect on contraction rate, with an initial increase followed by a sustained Gi-dependent decrease. Recent studies show that a PDZ domain-binding motif at the carboxyl terminus of human beta2AR interacts with ezrin-binding protein 50/sodium-hydrogen exchanger regulatory factor, a PDZ-domain-containing protein. The human beta2AR carboxyl terminus also binds to N-ethylmaleimide-sensitive factor, which does not contain a PDZ domain. We found that mutation of the three carboxyl-terminal amino acids in the mouse beta2AR (beta2AR-AAA) disrupts recycling of the receptor after agonist-induced internalization in cardiac myocytes. Nevertheless, stimulation of the beta2AR-AAA produced a greater contraction rate increase than that of the wild-type beta2AR. This enhanced stimulation of contraction rate can be attributed in part to the failure of the beta2AR-AAA to couple to Gi. We also observed that coupling of endogenous, wild-type beta2AR to Gi in beta1AR knockout myocytes is inhibited by treatment with a membrane-permeable peptide representing the beta2AR carboxyl terminus. These studies demonstrate that association of the carboxyl terminus of the beta2AR with ezrin-binding protein 50/sodium-hydrogen exchanger regulatory factor, N-ethylmaleimide-sensitive factor, or some related proteins dictates physiologic signaling specificity and trafficking in cardiac myocytes.
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MESH Headings
- Amino Acid Motifs
- Amino Acid Sequence
- Animals
- Binding Sites
- Cells, Cultured
- Endocytosis
- Enzyme-Linked Immunosorbent Assay
- Mice
- Mice, Knockout
- Microscopy, Fluorescence
- Molecular Sequence Data
- Mutagenesis
- Myocardium/cytology
- Myocardium/metabolism
- Protein Transport
- Receptors, Adrenergic, beta-2/chemistry
- Receptors, Adrenergic, beta-2/genetics
- Receptors, Adrenergic, beta-2/metabolism
- Receptors, Adrenergic, beta-2/physiology
- Signal Transduction
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Affiliation(s)
- Yang Xiang
- Department of Molecular and Cellular Physiology, Stanford University, Palo Alto, CA 94305, USA
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80
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Hu LA, Chen W, Martin NP, Whalen EJ, Premont RT, Lefkowitz RJ. GIPC interacts with the beta1-adrenergic receptor and regulates beta1-adrenergic receptor-mediated ERK activation. J Biol Chem 2003; 278:26295-301. [PMID: 12724327 DOI: 10.1074/jbc.m212352200] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Beta1-adrenergic receptors, expressed at high levels in the human heart, have a carboxyl-terminal ESKV motif that can directly interact with PDZ domain-containing proteins. Using the beta1-adrenergic receptor carboxyl terminus as bait, we identified the novel beta1-adrenergic receptor-binding partner GIPC in a yeast two-hybrid screen of a human heart cDNA library. Here we demonstrate that the PDZ domain-containing protein, GIPC, co-immunoprecipitates with the beta1-adrenergic receptor in COS-7 cells. Essential for this interaction is the Ser residue of the beta1-adrenergic receptor carboxyl-terminal ESKV motif. Our data also demonstrate that beta1-adrenergic receptor stimulation activates the mitogen-activated protein kinase, ERK1/2. beta1-adrenergic receptor-mediated ERK1/2 activation was inhibited by pertussis toxin, implicating Gi, and was substantially decreased by the expression of GIPC. Expression of GIPC had no observable effect on beta1-adrenergic receptor sequestration or receptor-mediated cAMP accumulation. This GIPC effect was specific for the beta1-adrenergic receptor and was dependent on an intact PDZ binding motif. These data suggest that GIPC can regulate beta1-adrenergic receptor-stimulated, Gi-mediated, ERK activation while having no effect on receptor internalization or Gs-mediated cAMP signaling.
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Affiliation(s)
- Liaoyuan A Hu
- Howard Hughes Medical Institute, Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA
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81
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Bockaert J, Marin P, Dumuis A, Fagni L. The 'magic tail' of G protein-coupled receptors: an anchorage for functional protein networks. FEBS Lett 2003; 546:65-72. [PMID: 12829238 DOI: 10.1016/s0014-5793(03)00453-8] [Citation(s) in RCA: 174] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
All cell types express a great variety of G protein-coupled receptors (GPCRs) that are coupled to only a limited set of G proteins. This disposition favors cross-talk between transduction pathways. However, GPCRs are organized into functional units. They promote specificity and thus avoid unsuitable cross-talk. New methodologies (mostly yeast two-hybrid screens and proteomics) have been used to discover more than 50 GPCR-associated proteins that are involved in building these units. In addition, these protein networks participate in the trafficking, targeting, signaling, fine-tuning and allosteric regulation of GPCRs. To date, proteins that interact with the GPCR C-terminus are the most abundant and are the focus of this review.
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Affiliation(s)
- Joël Bockaert
- Laboratoire de Génomique Fonctionnelle, UPR CNRS 2580, 141 rue de la Cardonille, 34094 Montpellier Cedex 5, France.
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82
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Abstract
Adrenoceptors (ARs), members of the G protein-coupled receptor superfamily, form the interface between the sympathetic nervous system and the cardiovascular system, with integral roles in the rapid regulation of myocardial function. However, in heart failure, chronic catecholamine stimulation of adrenoceptors has been linked to pathologic cardiac remodeling, including myocyte apoptosis and hypertrophy. In cardiac myocytes, activation of AR subtypes results in coupling to different G proteins and induction of specific signaling pathways, which is partly regulated by the subtype-specific distribution of receptors in plasma membrane compartments containing distinct complexes of signaling molecules. The Connections Maps of the Adrenergic and Myocyte Adrenergic Signaling Pathways bring into focus the specific signaling pathways of individual AR subtypes and their relevant functions in vivo.
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Affiliation(s)
- Yang Xiang
- Department of Molecular and Cellular Physiology, Stanford Medical Center, Palo Alto, CA 94305, USA
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83
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Abstract
PDZ domains are small globular building blocks that are amongst the most abundant protein interaction domains in organisms. Over the past several years an avalanche of data has implicated these modules in the clustering, targeting and routing of associating proteins. An overview is given of the types of interactions displayed by PDZ domains and how this relates to the current knowledge on their spatial structure. Furthermore, the different levels on which PDZ--ligand binding can be regulated and the consequences of PDZ domain-mediated clustering for activity, routing and targeting of interacting proteins will be addressed. Finally, some cell and animal models that illustrate the impact of PDZ domain-containing proteins on (multi-) cellular processes will be discussed.
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Affiliation(s)
- Marco van Ham
- Department of Cell Biology, Institute of Cellular Signalling, Nijmegen Center for Molecular Life Sciences, University of Nijmegen, Geert Grooteplein 28, 6525 GA Nijmegen, The Netherlands
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84
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Lee-Kwon W, Kawano K, Choi JW, Kim JH, Donowitz M. Lysophosphatidic acid stimulates brush border Na+/H+ exchanger 3 (NHE3) activity by increasing its exocytosis by an NHE3 kinase A regulatory protein-dependent mechanism. J Biol Chem 2003; 278:16494-501. [PMID: 12595524 DOI: 10.1074/jbc.m300580200] [Citation(s) in RCA: 77] [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
Na(+)/H(+) exchanger 3 (NHE3) kinase A regulatory protein (E3KARP) has been implicated in cAMP- and Ca(2+)-dependent inhibition of NHE3. In the current study, a new role of E3KARP is demonstrated in the stimulation of NHE3 activity. Lysophosphatidic acid (LPA) is a mediator of the restitution phase of inflammation but has not been studied for effects on sodium absorption. LPA has no effect on NHE3 activity in opossum kidney (OK) proximal tubule cells, which lack expression of endogenous E3KARP. However, in OK cells exogenously expressing E3KARP, LPA stimulated NHE3 activity. Consistent with the stimulatory effect on NHE3 activity, LPA treatment increased the surface NHE3 amount, which occurred by accelerating exocytic trafficking (endocytic recycling) to the apical plasma membrane. These LPA effects only occurred in OK cells transfected with E3KARP. The LPA-induced increases of NHE3 activity, surface NHE3 amounts, and exocytosis were completely inhibited by pretreatment with the PI 3-kinase inhibitor, LY294002. LPA stimulation of the phosphorylation of Akt was used as an assay for PI 3-kinase activity. LY294002 completely prevented the LPA-induced increase in Akt phosphorylation, which is consistent with the inhibitory effect of LY294002 on the LPA stimulation of NHE3 activity. The LPA-induced phosphorylation of Akt was the same in OK cells with and without E3KARP. These results show that LPA stimulates NHE3 in the apical surface of OK cells by a mechanism that is dependent on both E3KARP and PI 3-kinase. This is the first demonstration that rapid stimulation of NHE3 activity is dependent on an apical membrane PDZ domain protein.
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Affiliation(s)
- Whaseon Lee-Kwon
- Department of Physiology, Gastrointestinal Division, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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85
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Xu J, He J, Castleberry AM, Balasubramanian S, Lau AG, Hall RA. Heterodimerization of alpha 2A- and beta 1-adrenergic receptors. J Biol Chem 2003; 278:10770-7. [PMID: 12529373 DOI: 10.1074/jbc.m207968200] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
beta- and alpha(2)-adrenergic receptors are known to exhibit substantial cross-talk and mutual regulation in tissues where they are expressed together. We have found that the beta(1)-adrenergic receptor (beta(1)AR) and alpha(2A)-adrenergic receptor (alpha(2A)AR) heterodimerize when coexpressed in cells. Immunoprecipitation studies with differentially tagged beta(1)AR and alpha(2A)AR expressed in HEK-293 cells revealed robust co-immunoprecipitation of the two receptors. Moreover, agonist stimulation of alpha(2A)AR was found to induce substantial internalization of coexpressed beta(1)AR, providing further evidence for a physical association between the two receptors in a cellular environment. Ligand binding assays examining displacement of [(3)H]dihydroalprenolol binding to the beta(1)AR by various ligands revealed that beta(1)AR pharmacological properties were significantly altered when the receptor was coexpressed with alpha(2A)AR. Finally, beta(1)AR/alpha(2A)AR heterodimerization was found to be markedly enhanced by a beta(1)AR point mutation (N15A) that blocks N-linked glycosylation of the beta(1)AR as well as by point mutations (N10A/N14A) that block N-linked glycosylation of the alpha(2A)AR. These data reveal an interaction between beta(1)AR and alpha(2A)AR that is regulated by glycosylation and that may play a key role in cross-talk and mutual regulation between these receptors.
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Affiliation(s)
- Jianguo Xu
- Department of Pharmacology, Rollins Research Center, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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86
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Bowie D, Garcia EP, Marshall J, Traynelis SF, Lange GD. Allosteric regulation and spatial distribution of kainate receptors bound to ancillary proteins. J Physiol 2003; 547:373-85. [PMID: 12562952 PMCID: PMC2342651 DOI: 10.1113/jphysiol.2002.033076] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2002] [Accepted: 12/05/2002] [Indexed: 11/08/2022] Open
Abstract
A diverse range of accessory proteins regulates the behaviour of most ligand- and voltage-gated ion channels. For glutamate receptor 6 (GluR6) kainate receptors, two unrelated proteins, concanavalin-A (Con-A) and postsynaptic density protein 95 (PSD-95), bind to extra- and intracellular domains, respectively, but are reported to exert similar effects on GluR6 desensitization behaviour. We have tested the hypothesis that distinct allosteric binding sites control GluR6 receptors via a common transduction pathway. Rapid agonist application to excised patches revealed that neither Con-A nor PSD-95 affect the onset of desensitization. The rate of desensitization elicited by 10 mM L-glutamate was similar in control (taufast = 5.5 +/- 0.4 ms), Con-A-treated patches (taufast = 6.1 +/- 0.5 ms) and patches containing PSD-95 and GluR6 receptors (taufast = 4.7 +/- 0.6 ms). Likewise, the time course of recovery from GluR6 desensitization was similar in both control and Con-A conditions, whereas PSD-95 accelerated recovery almost twofold. Peak and steady-state (SS) dose-response relationships to glutamate were unchanged by lectin treatment (e.g. control, EC50(SS) = 31 +/- 28 microM vs Con-A, EC50(SS) = 45 +/- 9 microM, n = 6), suggesting that Con-A does not convert non-conducting channels with high agonist affinity into an open conformation. Instead, we demonstrate that the effects of Con-A on macroscopic responses reflect a shift in the relative contribution of different open states of the channel. In contrast, the effect of PSD-95 on recovery behaviour suggests that the association between kainate receptors and cytoskeletal proteins regulates signalling at glutamatergic synapses. Our results show that Con-A and PSD-95 regulate kainate receptors via distinct allosteric mechanisms targeting selective molecular steps in the transduction pathway.
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Affiliation(s)
- Derek Bowie
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
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87
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Yap CC, Muto Y, Kishida H, Hashikawa T, Yano R. PKC regulates the delta2 glutamate receptor interaction with S-SCAM/MAGI-2 protein. Biochem Biophys Res Commun 2003; 301:1122-8. [PMID: 12589829 DOI: 10.1016/s0006-291x(03)00070-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Inside cells, membrane proteins are localized at particular surface domains to perform their precise functions. Various kinds of PDZ domain proteins have been shown to play important roles in the intracellular trafficking and anchoring of membrane proteins. In this study, we show that delta2 glutamate receptor is interacting with S-SCAM/MAGI-2, a PDZ domain protein localized in the perinuclear region and postsynaptic sites of cerebellar Purkinje cells. The binding is regulated by PKC (protein kinase-C) mediated phosphorylation of the receptor with a unique repetitive structure in S-SCAM/MAGI-2. Co-expression of both proteins resulted in drastic changes of the receptor localization in COS7 cells. These results show a novel regulatory mechanism for the binding of PDZ domain proteins and suggest that the interaction between delta2 receptor and S-SCAM/MAGI-2 may be important for intracellular trafficking of the receptor.
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Affiliation(s)
- Chan Choo Yap
- Laboratory for Cellular Information Processing, Brain Science Institute, RIKEN, Wako, 351-0198, Saitama, Japan
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88
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Kremerskothen J, Plaas C, Büther K, Finger I, Veltel S, Matanis T, Liedtke T, Barnekow A. Characterization of KIBRA, a novel WW domain-containing protein. Biochem Biophys Res Commun 2003; 300:862-7. [PMID: 12559952 DOI: 10.1016/s0006-291x(02)02945-5] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In a yeast two hybrid screen with the human isoform of Dendrin (KIAA0749), a putative modulator of the postsynaptic cytoskeleton, we isolated a cDNA coding for a novel protein, KIBRA, possessing two amino-terminal WW domains, an internal C2-like domain and a carboxy-terminal glutamic acid-rich stretch. Northern blot analysis revealed that the expression of KIBRA mRNA was predominately found in kidney and brain. In vitro interaction studies revealed that the first KIBRA WW domain binds specifically to PPxY motifs. Transient transfection of monkey kidney cells with constructs encoding Myc-tagged KIBRA displayed a cytoplasmic localization and a perinuclear enrichment of the protein.
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Affiliation(s)
- Joachim Kremerskothen
- Department for Experimental Tumorbiology, University Muenster, Badestrasse 9, D-48149 Muenster, Germany.
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89
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González-Mariscal L, Betanzos A, Nava P, Jaramillo BE. Tight junction proteins. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2003; 81:1-44. [PMID: 12475568 DOI: 10.1016/s0079-6107(02)00037-8] [Citation(s) in RCA: 810] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A fundamental function of epithelia and endothelia is to separate different compartments within the organism and to regulate the exchange of substances between them. The tight junction (TJ) constitutes the barrier both to the passage of ions and molecules through the paracellular pathway and to the movement of proteins and lipids between the apical and the basolateral domains of the plasma membrane. In recent years more than 40 different proteins have been discovered to be located at the TJs of epithelia, endothelia and myelinated cells. This unprecedented expansion of information has changed our view of TJs from merely a paracellular barrier to a complex structure involved in signaling cascades that control cell growth and differentiation. Both cortical and transmembrane proteins integrate TJs. Among the former are scaffolding proteins containing PDZ domains, tumor suppressors, transcription factors and proteins involved in vesicle transport. To date two components of the TJ filaments have been identified: occludin and claudin. The latter is a protein family with more than 20 members. Both occludin and claudins are integral proteins capable of interacting adhesively with complementary molecules on adjacent cells and of co-polymerizing laterally. These advancements in the knowledge of the molecular structure of TJ support previous physiological models that exhibited TJ as dynamic structures that present distinct permeability and morphological characteristics in different tissues and in response to changing natural, pathological or experimental conditions.
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Affiliation(s)
- L González-Mariscal
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (CINVESTAV), Ave. Politécnico Nacional 2508, México DF, 07000, Mexico.
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90
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He J, Xu J, Castleberry AM, Lau AG, Hall RA. Glycosylation of beta(1)-adrenergic receptors regulates receptor surface expression and dimerization. Biochem Biophys Res Commun 2002; 297:565-72. [PMID: 12270132 DOI: 10.1016/s0006-291x(02)02259-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The beta(1)-adrenergic receptor (beta(1)AR) has one predicted site of N-linked glycosylation on its extracellular amino-terminus, but the glycosylation and potential functional importance of this site have not yet been examined. We show here that the beta(1)AR is glycosylated in various cell types and that mutation of the single predicted site of N-linked glycosylation (N15A) results in the formation of receptors that are not N-glycosylated. The beta(1)AR N15A mutant exhibited significantly decreased basal surface expression relative to the wild-type receptor but had no detectable deficits in ligand binding or agonist-promoted internalization. Co-immunoprecipitation experiments using Flag-tagged and HA-tagged receptors demonstrated that the beta(1)AR-N15A mutant receptor exhibits a markedly reduced capacity for dimerization relative to wild-type beta(1)AR. These data reveal that the beta(1)AR is glycosylated on Asn15 and that this glycosylation plays a role in regulating beta(1)AR surface expression and dimerization.
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Affiliation(s)
- Junqi He
- Department of Pharmacology, 5113 Rollins Research Center, Emory University School of Medicine, 1510 Clifton Rd., Atlanta, GA 30322, USA
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91
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Pak Y, Pham N, Rotin D. Direct binding of the beta1 adrenergic receptor to the cyclic AMP-dependent guanine nucleotide exchange factor CNrasGEF leads to Ras activation. Mol Cell Biol 2002; 22:7942-52. [PMID: 12391161 PMCID: PMC134719 DOI: 10.1128/mcb.22.22.7942-7952.2002] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
G-protein-coupled receptors (GPCRs) can indirectly activate Ras primarily through the betagamma subunits of G proteins, which recruit c-Src, phosphatidylinositol 3-kinase, and Grb2-SOS. However, a direct interaction between a Ras activator (guanine nucleotide exchange factor [GEF]) and GPCRs that leads to Ras activation has never been demonstrated. We report here a novel mechanism for a direct GPCR-mediated Ras activation. The beta1 adrenergic receptor (beta1-AR) binds to the PDZ domain of the cyclic AMP (cAMP)-dependent Ras exchange factor, CNrasGEF, via its C-terminal SkV motif. In cells heterologously expressing beta1-AR and CNrasGEF, Ras is activated by the beta1-AR agonist isoproterenol, and this activation is abolished in beta1-AR mutants that cannot bind CNrasGEF or in CNrasGEF mutants lacking the catalytic CDC25 domain or cAMP-binding domain. Moreover, the activation is transduced via Gsalpha and not via Gbetagamma. In contrast to beta1-AR, the beta2-AR neither binds CNrasGEF nor activates Ras via CNrasGEF after agonist stimulation. These results suggest a model whereby the physical interaction between the beta1-AR and CNrasGEF facilitates the transduction of Gsalpha-induced cAMP signal into the activation of Ras. The present study provides the first demonstration of direct physical association between a Ras activator and a GPCR, leading to agonist-induced Ras activation
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MESH Headings
- Animals
- Cell Line
- Cyclic AMP/metabolism
- GTP-Binding Protein alpha Subunits, Gs/metabolism
- Green Fluorescent Proteins
- Guanine Nucleotide Exchange Factors/metabolism
- Humans
- Ligands
- Luminescent Proteins/metabolism
- Models, Biological
- Nerve Tissue Proteins
- Protein Binding
- Protein Structure, Tertiary
- Protein Subunits
- Rats
- Receptors, Adrenergic, beta-1/genetics
- Receptors, Adrenergic, beta-1/metabolism
- Receptors, Adrenergic, beta-2/genetics
- Receptors, Adrenergic, beta-2/metabolism
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Swine
- ras Proteins/metabolism
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Affiliation(s)
- Youngshil Pak
- Program in Cell Biology, The Hospital for Sick Children, and Biochemistry Department, University of Toronto, Toronto, M5G 1X8 Ontario, Canada
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92
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Mercier JF, Salahpour A, Angers S, Breit A, Bouvier M. Quantitative Assessment of β1- and β2-Adrenergic Receptor Homo- and Heterodimerization by Bioluminescence Resonance Energy Transfer. J Biol Chem 2002; 277:44925-31. [PMID: 12244098 DOI: 10.1074/jbc.m205767200] [Citation(s) in RCA: 407] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Quantitative bioluminescence resonance energy transfer (BRET) analysis was applied to the study of beta(1)- and beta(2)-adrenergic receptor homo- and heterodimerization. To assess the relative affinity between each of the protomers, BRET saturation experiments were carried out in HEK-293T cells. beta(1)- and beta(2)-adrenergic receptors were found to have similar propensity to engage in homo- and heterotropic interactions suggesting that, at equivalent expression levels of the two receptor subtypes, an equal proportion of homo- and heterodimers would form. Analysis of the data also revealed that, at equimolar expression levels of energy donor and acceptor, more than 80% of the receptor molecules exist as dimers and that this high incidence of receptor dimerization is insensitive to receptor density for expression levels varying between 1.4 and 26.9 pmol of receptor/mg of membrane protein. Taken together, these results indicate that most of the receptors expressed in cells exist as constitutive dimers and that, at least in undifferentiated fibroblasts, the proportion of homo- and heterodimers between the closely related beta(1)- and beta(2)-adrenergic receptors is determined by their relative levels of expression.
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MESH Headings
- Cell Line
- Dimerization
- Fluorescence Resonance Energy Transfer/methods
- Humans
- Luminescent Measurements
- Protein Structure, Quaternary
- Radioligand Assay
- Receptors, Adrenergic, beta-1/chemistry
- Receptors, Adrenergic, beta-1/genetics
- Receptors, Adrenergic, beta-1/metabolism
- Receptors, Adrenergic, beta-2/chemistry
- Receptors, Adrenergic, beta-2/genetics
- Receptors, Adrenergic, beta-2/metabolism
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
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Affiliation(s)
- Jean-François Mercier
- Département de Biochimie and Groupe de Recherche sur le Système Nerveux Autonome, Université de Montréal, Montréal, Quebec H3C 3J7, Canada
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93
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Abstract
The actions of many hormones and neurotransmitters are mediated through stimulation of G protein-coupled receptors. A primary mechanism by which these receptors exert effects inside the cell is by association with heterotrimeric G proteins, which can activate a wide variety of cellular enzymes and ion channels. G protein-coupled receptors can also interact with a number of cytoplasmic scaffold proteins, which can link the receptors to various signaling intermediates and intracellular effectors. The multicomponent nature of G protein-coupled receptor signaling pathways makes them ideally suited for regulation by scaffold proteins. This review focuses on several specific examples of G protein-coupled receptor-associated scaffolds and the roles they may play in organizing receptor-initiated signaling pathways in the cardiovascular system and other tissues.
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Affiliation(s)
- Randy A Hall
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Ga, USA
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94
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Lavoie C, Mercier JF, Salahpour A, Umapathy D, Breit A, Villeneuve LR, Zhu WZ, Xiao RP, Lakatta EG, Bouvier M, Hébert TE. Beta 1/beta 2-adrenergic receptor heterodimerization regulates beta 2-adrenergic receptor internalization and ERK signaling efficacy. J Biol Chem 2002; 277:35402-10. [PMID: 12140284 DOI: 10.1074/jbc.m204163200] [Citation(s) in RCA: 177] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Beta(1)- and beta(2)-adrenergic receptors (beta(1)AR and beta(2)AR) are co-expressed in numerous tissues where they play a central role in the responses of various organs to sympathetic stimulation. Although the two receptor subtypes share some signaling pathways, each has been shown to have specific signaling and regulatory properties. Given the recent recognition that many G protein-coupled receptors can form homo- and heterodimers, the present study was undertaken to determine whether the beta(1)AR and beta(2)AR can form dimers in cells and, if so, to investigate the potential functional consequences of such heterodimerization. Using co-immunoprecipitation and bioluminescence resonance energy transfer, we show that beta(1)AR and beta(2)AR can form heterodimers in HEK 293 cells co-expressing the two receptors. Functionally, beta-adrenergic stimulated adenylyl cyclase activity was found to be identical in cells expressing beta(1)AR, beta(2)AR, or both receptors at similar levels, indicating that heterodimerization did not affect this signaling pathway. When considering ERK1/2 MAPK activity, a significant agonist-promoted activation was detected in beta(2)AR- but not beta(1)AR-expressing cells. Similarly to what was observed in cells expressing the beta(1)AR alone, no beta-adrenergic stimulated ERK1/2 phosphorylation was observed in cells co-expressing the two receptors. A similar inhibition of agonist-promoted internalization of the beta(2)AR was observed upon co-expression of the beta(1)AR, which by itself internalized to a lesser extent. Taken together, our data suggest that heterodimerization between beta(1)AR and beta(2)AR inhibits the agonist-promoted internalization of the beta(2)AR and its ability to activate the ERK1/2 MAPK signaling pathway.
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MESH Headings
- Cell Line
- Dimerization
- Endocytosis
- Enzyme-Linked Immunosorbent Assay
- Humans
- Immunohistochemistry
- Mitogen-Activated Protein Kinase 1/metabolism
- Mitogen-Activated Protein Kinase 3
- Mitogen-Activated Protein Kinases/metabolism
- Phosphorylation
- Precipitin Tests
- Receptors, Adrenergic, beta-1/chemistry
- Receptors, Adrenergic, beta-1/genetics
- Receptors, Adrenergic, beta-1/metabolism
- Receptors, Adrenergic, beta-2/chemistry
- Receptors, Adrenergic, beta-2/genetics
- Receptors, Adrenergic, beta-2/metabolism
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Signal Transduction
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Affiliation(s)
- Catherine Lavoie
- Centre de Recherche, Institut de Cardiologie de Montréal, Montréal, Québec, H1T 1C8, Canada
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95
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Xiang Y, Devic E, Kobilka B. The PDZ binding motif of the beta 1 adrenergic receptor modulates receptor trafficking and signaling in cardiac myocytes. J Biol Chem 2002; 277:33783-90. [PMID: 12097326 DOI: 10.1074/jbc.m204136200] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Beta(1) and beta(2) adrenergic receptors (AR) regulate the intrinsic contraction rate in neonatal mouse cardiac myocytes through distinct signaling pathways. It has been shown that stimulation of beta(1)ARs leads to a protein kinase A-dependent increase in contraction rate. In contrast, stimulation of beta(2)ARs has a biphasic effect on contraction rate, with an initial protein kinase A-independent increase followed by a sustained decrease that is blocked by pertussis toxin. The beta(2)AR undergoes agonist-induced endocytosis in cardiac myocytes while the beta(1)AR remains on the cell surface. It has been shown that a PDZ domain binding motif at the carboxyl terminus of beta(1)AR interacts with the postsynaptic density protein PSD-95 when both are expressed in HEK293 cells. We found that mutation of this PDZ binding motif in the beta(1)AR (beta(1)AR-PDZ) enabled agonist-induced internalization in cardiac myocytes. Moreover, stimulation of beta(1)AR-PDZ had a biphasic effect on the myocyte contraction rate similar to that observed following stimulation of the beta(2)AR. The secondary decrease in the contraction rate was mediated by G(i) and could be blocked by pertussis toxin. Furthermore, a non-selective endocytosis inhibitor, concanavalin A, inhibited the internalization of wild type beta(2)AR and the mutated beta(1)AR-PDZ, and blocked the coupling of both receptors to G(i). Finally, treating myocytes with a membrane-permeable peptide representing beta(1)AR PDZ motif caused the endogenous beta(1)AR to behave like beta(1)AR-PDZ. These studies suggest that association of the beta(1)AR with PSD-95 or a related protein dictates signaling specificity by retaining the receptor at the cell surface and preventing interaction with G(i).
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Amino Acid Motifs
- Animals
- Animals, Newborn
- Binding Sites
- Biological Transport
- Cells, Cultured
- Cyclic AMP/metabolism
- Discs Large Homolog 1 Protein
- GTP-Binding Proteins/physiology
- Guanylate Kinases
- Heart/physiology
- Membrane Proteins
- Mice
- Mice, Knockout
- Nerve Tissue Proteins/physiology
- Receptors, Adrenergic, beta-1/chemistry
- Receptors, Adrenergic, beta-1/physiology
- Receptors, Adrenergic, beta-2/physiology
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Affiliation(s)
- Yang Xiang
- Department of Molecular and Cellular Physiology, Howard Hughes Medical Institution, B157 Beckman Center, Stanford Medical Center, Palo Alto, CA 94043, USA
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96
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Cheng J, Moyer BD, Milewski M, Loffing J, Ikeda M, Mickle JE, Cutting GR, Li M, Stanton BA, Guggino WB. A Golgi-associated PDZ domain protein modulates cystic fibrosis transmembrane regulator plasma membrane expression. J Biol Chem 2002; 277:3520-9. [PMID: 11707463 DOI: 10.1074/jbc.m110177200] [Citation(s) in RCA: 186] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We identified a novel cystic fibrosis transmembrane conductance regulator (CFTR)-associating, PDZ domain-containing protein, CAL (CFTR associated ligand) containing two predicted coiled-coiled domains and one PDZ domain. The PDZ domain of CAL binds to the C terminus of CFTR. Although CAL does not have any predicted transmembrane domains, CAL is associated with membranes mediated by a region containing the coiled-coil domains. CAL is located primarily at the Golgi apparatus, co-localizing with trans-Golgi markers and is sensitive to Brefeldin A treatment. Immunoprecipitation experiments suggest that CAL exists as a multimer. Overexpression of CAL reduces CFTR chloride currents in mammalian cells and decreases expression, rate of insertion and half-life of CFTR in the plasma membrane. The Na(+)/H(+) exchanger regulatory factor, NHE-RF, a subplasma membrane PDZ domain protein, restores cell surface expression of CFTR and chloride currents. In addition, NHE-RF inhibits the binding of CAL to CFTR. CAL modulates the surface expression of CFTR. CAL favors retention of CFTR within the cell, whereas NHE-RF favors surface expression by competing with CAL for the binding of CFTR. Thus, the regulation of CFTR in the plasma membrane involves the dynamic interaction between at least two PDZ domain proteins.
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Affiliation(s)
- Jie Cheng
- Department of Physiology and Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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