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Zheng M, Zhang X, Min X, Sun N, Kim KM. Cytoplasmic recruitment of Mdm2 as a common characteristic of G protein-coupled receptors that undergo desensitization. Biochem Biophys Res Commun 2020; 530:181-188. [PMID: 32828283 DOI: 10.1016/j.bbrc.2020.06.091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 06/18/2020] [Indexed: 11/18/2022]
Abstract
Desensitization of G protein-coupled receptors (GPCRs) represents a gradual attenuation of receptor responsiveness by continuous or repeated exposure to agonists. The most widely accepted molecular mechanism responsible for desensitization is that of GRK2-mediated receptor phosphorylation followed by association with β-arrestins. However, in most cases, this mechanism cannot explain the desensitization of GPCRs. In this study, we investigated whether there exists a direct correlation between desensitization and certain cellular events that commonly observed with desensitizing receptors. Our study showed that constitutive ubiquitination of β-arrestin, accompanied by nuclear to cytoplasmic translocation of Mdm2, was observed in cells expressing desensitizing GPCRs (dopamine D3 receptor, K149C-dopamine D2 receptor, β2 adrenoceptor, and lysophosphatidic acid receptor 1). In contrast, Mdm2 was observed in the nucleus in cells expressing non-desensitizing GPCRs (dopamine D2 receptor, C147K-dopamine D3 receptor, and dopamine D4 receptor). Molecular manipulation to convert the characteristics of the dopamine D4 receptor from non-desensitizing to desensitizing changed the status of subcellular localization of Mdm2 from nuclear to cytoplasmic. With repeated agonist treatments of desensitizing receptors, Mdm2 translocated from cytoplasm to nucleus, resulting in the deubiquitination of β-arrestins. This study suggests that the property of a receptor that causes a change in subcellular localization of Mdm2, from the nuclear to cytoplasmic, could be used as a biomarker to predict the desensitization of a receptor.
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Affiliation(s)
- Mei Zheng
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, 61186, Republic of Korea
| | - Xiaohan Zhang
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, 61186, Republic of Korea
| | - Xiao Min
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, 61186, Republic of Korea
| | - Ningning Sun
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, 61186, Republic of Korea
| | - Kyeong-Man Kim
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, 61186, Republic of Korea.
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2
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Tshabalala TN, Tomescu MS, Prior A, Balakrishnan V, Sayed Y, Dirr HW, Achilonu I. Energetics of Glutathione Binding to Human Eukaryotic Elongation Factor 1 Gamma: Isothermal Titration Calorimetry and Molecular Dynamics Studies. Protein J 2016; 35:448-458. [PMID: 27844275 DOI: 10.1007/s10930-016-9688-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The energetics of ligand binding to human eukaryotic elongation factor 1 gamma (heEF1γ) was investigated using reduced glutathione (GSH), oxidised glutathione (GSSG), glutathione sulfonate and S-hexylglutathione as ligands. The experiments were conducted using isothermal titration calorimetry, and the findings were supported using computational studies. The data show that the binding of these ligands to heEF1γ is enthalpically favourable and entropically driven (except for the binding of GSSG). The full length heEF1γ binds GSSG with lower affinity (K d = 115 μM), with more hydrogen-bond contacts (ΔH = -73.8 kJ/mol) and unfavourable entropy (-TΔS = 51.7 kJ/mol) compared to the glutathione transferase-like N-terminus domain of heEF1γ, which did not show preference to any specific ligand. Computational free binding energy calculations from the 10 ligand poses show that GSSG and GSH consistently bind heEF1γ, and that both ligands bind at the same site with a folded bioactive conformation. This study reveals the possibility that heEF1γ is a glutathione-binding protein.
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Affiliation(s)
- Thabiso N Tshabalala
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, 2050, South Africa
| | - Mihai-Silviu Tomescu
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, 2050, South Africa
| | - Allan Prior
- School of Chemistry, University of the Witwatersrand, Johannesburg, 2050, South Africa
| | - Vijayakumar Balakrishnan
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, 2050, South Africa
| | - Yasien Sayed
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, 2050, South Africa
| | - Heini W Dirr
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, 2050, South Africa
| | - Ikechukwu Achilonu
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, 2050, South Africa.
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Achilonu I, Siganunu TP, Dirr HW. Purification and characterisation of recombinant human eukaryotic elongation factor 1 gamma. Protein Expr Purif 2014; 99:70-7. [DOI: 10.1016/j.pep.2014.04.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 04/02/2014] [Accepted: 04/03/2014] [Indexed: 11/17/2022]
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4
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Martínez-Royo A, Lahoz B, Alabart JL, Folch J, Calvo JH. Characterisation of the Melatonin Receptor 1A (MTNR1A) gene in the Rasa Aragonesa sheep breed: association with reproductive seasonality. Anim Reprod Sci 2012; 133:169-75. [PMID: 22809454 DOI: 10.1016/j.anireprosci.2012.06.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Revised: 06/21/2012] [Accepted: 06/22/2012] [Indexed: 10/28/2022]
Abstract
The ovine Melatonin Receptor 1A (MTNR1A) gene was structurally characterised and association between its variants and the reproductive seasonality was examined in a daughter design comprising three families of Rasa Aragonesa sheep breed. Sequencing of six Rasa Aragonesa ewes with extreme values for seasonality trait revealed 28 polymorphisms: 11 SNPs in the coding region (all in Exon 2), and 17 SNPs in the promoter region MTNR1A. All the substitutions in the coding region were found most likely lacking any phenotypic effect, because they are conservative mutations or were not part of the transmembrane domain. The silent mutations, which had shown association with reproductive seasonality in other breeds, were also found and genotyped in Rasa Aragonesa. The T allele of SNP606/RsaI of MNTR1A gene was associated with a greater percentage of oestrous cyclic ewes in the Rasa Aragonesa breed, indicating that this SNP may be in linkage disequilibrium with a mutation responsible for this trait close to MTNR1A, or in regulatory sequences of the gene. In this sense, several SNPs affecting a binding element for some transcription factors have been identified in the promoter region. The SNPs at 422 and 527 positions could constitute a binding element for some transcription factors (TFs), located in an EF2 and SRY consensus sites in the promoter region, respectively. Haplotype h(5) showed significant differences with the h(2) haplotype (66% compared to 49.2%) on oestrous cyclicity, thus these results are consistent with genotypic associations for each SNP. Haplotype with T, A and T alleles for SNPs 422, 677 (promoter region) and 612 (Exon 2) showed an increase of the percentage of oestrous cyclic ewes. Although some of these mutations have been associated with seasonal reproduction, further studies with a more appropriate animal design as well as functional studies of TF binding activity are needed.
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Affiliation(s)
- A Martínez-Royo
- Unidad de Tecnología en Producción Animal, CITA, Zaragoza, Spain
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Wu J, Xiao H, Sun H, Zou L, Zhu LQ. Role of dopamine receptors in ADHD: a systematic meta-analysis. Mol Neurobiol 2012; 45:605-20. [PMID: 22610946 DOI: 10.1007/s12035-012-8278-5] [Citation(s) in RCA: 178] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2012] [Accepted: 05/07/2012] [Indexed: 01/11/2023]
Abstract
The dopaminergic system plays a pivotal role in the central nervous system via its five diverse receptors (D1-D5). Dysfunction of dopaminergic system is implicated in many neuropsychological diseases, including attention deficit hyperactivity disorder (ADHD), a common mental disorder that prevalent in childhood. Understanding the relationship of five different dopamine (DA) receptors with ADHD will help us to elucidate different roles of these receptors and to develop therapeutic approaches of ADHD. This review summarized the ongoing research of DA receptor genes in ADHD pathogenesis and gathered the past published data with meta-analysis and revealed the high risk of DRD5, DRD2, and DRD4 polymorphisms in ADHD.
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Affiliation(s)
- Jing Wu
- Department of Epidemiology and Biostatistics and Ministry of Education Key Lab of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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β-arrestin2 plays permissive roles in the inhibitory activities of RGS9-2 on G protein-coupled receptors by maintaining RGS9-2 in the open conformation. Mol Cell Biol 2011; 31:4887-901. [PMID: 22006018 DOI: 10.1128/mcb.05690-11] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Together with G protein-coupled receptor (GPCR) kinases (GRKs) and β-arrestins, RGS proteins are the major family of molecules that control the signaling of GPCRs. The expression pattern of one of these RGS family members, RGS9-2, coincides with that of the dopamine D(3) receptor (D(3)R) in the brain, and in vivo studies have shown that RGS9-2 regulates the signaling of D2-like receptors. In this study, β-arrestin2 was found to be required for scaffolding of the intricate interactions among the dishevelled-EGL10-pleckstrin (DEP) domain of RGS9-2, Gβ5, R7-binding protein (R7BP), and D(3)R. The DEP domain of RGS9-2, under the permission of β-arrestin2, inhibited the signaling of D(3)R in collaboration with Gβ5. β-Arrestin2 competed with R7BP and Gβ5 so that RGS9-2 is placed in the cytosolic region in an open conformation which is able to inhibit the signaling of GPCRs. The affinity of the receptor protein for β-arrestin2 was a critical factor that determined the selectivity of RGS9-2 for the receptor it regulates. These results show that β-arrestins function not only as mediators of receptor-G protein uncoupling and initiators of receptor endocytosis but also as scaffolding proteins that control and coordinate the inhibitory effects of RGS proteins on the signaling of certain GPCRs.
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Min C, Cheong SY, Cheong SJ, Kim M, Cho DI, Kim KM. RGS4 exerts inhibitory activities on the signaling of dopamine D2 receptor and D3 receptor through the N-terminal region. Pharmacol Res 2011; 65:213-20. [PMID: 21896332 DOI: 10.1016/j.phrs.2011.08.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2011] [Accepted: 08/22/2011] [Indexed: 11/28/2022]
Abstract
Dopamine D(2) receptor and D(3) receptor (D(2)R and D(3)R) are the major targets for current antipsychotic drugs, and their proper regulation has pathological and pharmacological significance. This study was conducted to understand the functional roles and molecular mechanisms of RGS proteins (RGS2, RGS4, and RGS9-2) on the signaling of D(2)R and D(3)R. RGS proteins were co-expressed with D(2)R and D(3)R in HEK-293 cells. The protein interactions between RGS proteins and D(2)R/D(3)R, and effects of RGS proteins on the internalization, signaling, and desensitization of D(2)R/D(3)R were determined. In addition, the RGS4 proteins were subdivided into N-terminal region, RGS domain, and the C-terminal region, and the specific subdomain of RGS4 protein involved in the regulation of the signaling of D(2)R/D(3)R was determined. All of RGS proteins we tested interacted with D(2)R/D(3)R. RGS4 exerted potent inhibitory activities on the signaling of D(2)R/D(3)R. RGS9-2 exerted selective but moderate inhibitory activity on D(3)R and the internalization of D(2)R. RGS2 had no effect. The N-terminal domain of RGS4 was involved in its interaction with D(2)R and D(3)R and was required for the inhibitory activity of the RGS domain. The study for the first time showed that RGS4 is the major RGS protein which interacts through the N-terminal region and exerts potent inhibitory activities on the signaling of D(2)R and D(3)R.
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Affiliation(s)
- Chengchun Min
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, Republic of Korea
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8
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Min C, Cho DI, Kwon KJ, Kim KS, Shin CY, Kim KM. Novel regulatory mechanism of canonical Wnt signaling by dopamine D2 receptor through direct interaction with beta-catenin. Mol Pharmacol 2011; 80:68-78. [PMID: 21493728 DOI: 10.1124/mol.111.071340] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Classical G protein-coupled receptors (GPCRs) and canonical Wnt pathways were believed to use distinct signaling pathways. However, recent studies have shown that these two pathways interact each other by sharing several intermediate signaling components. Recent in vivo studies showed that antipsychotic drugs, which block dopamine D2-like receptors, increase the cellular levels of downstream signaling components of canonical Wnt pathways, such as dishevelled (Dvl), glycogen synthase kinase 3β (GSK3β), and β-catenin. These results suggest that some functional interactions might exist between Wnt pathway and D2-like receptors. In this study, we show that among five different dopamine receptor subtypes, D(2) receptor (D(2)R) selectively inhibited the Wnt signaling, which was measured by lymphoid enhancing factor-1 (LEF-1)-dependent transcriptional activities. D(2)R-mediated inhibition of Wnt signaling was agonist- and G protein-independent and did not require receptor phosphorylation or endocytosis. D(2)R inhibited the LEF-1-dependent transcriptional activities, and this inhibitory activity was not affected by the inhibition of GSK-3β, suggesting that D(2)R inhibited the Wnt signaling by acting on the downstream of GSK3β. D(2)R directly interacted with β-catenin through the second and third loops, leading to a reduction of β-catenin distribution in the nucleus, resulting in an inhibition of LEF-1-dependent transcription. This is a novel mechanism for the regulation of canonical Wnt signaling by GPCRs, in which receptor proteins recruit β-catenin from cytosol to the plasma membrane, resulting in the decrement of the β-catenin/LEF-1-dependent transcription in the nucleus.
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Affiliation(s)
- Chengchun Min
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju 500-757, Korea
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9
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Current perspectives on the selective regulation of dopamine D2 and D3 receptors. Arch Pharm Res 2010; 33:1521-38. [DOI: 10.1007/s12272-010-1005-8] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Revised: 08/20/2010] [Accepted: 08/20/2010] [Indexed: 01/07/2023]
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10
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Gage MC, Keen JN, Buxton AT, Bedi MK, Findlay JBC. Proteomic Analysis of IgE-Mediated Secretion by LAD2 Mast Cells. J Proteome Res 2009; 8:4116-25. [DOI: 10.1021/pr900108w] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Matthew C. Gage
- Institute of Membrane and Systems Biology, Faculty of Biological Sciences, LIGHT Laboratories, University of Leeds, Leeds LS2 9JT, United Kingdom, and Division of Cardiovascular and Diabetes Research, Faculty of Medicine and Health, LIGHT Laboratories, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Jeffrey N. Keen
- Institute of Membrane and Systems Biology, Faculty of Biological Sciences, LIGHT Laboratories, University of Leeds, Leeds LS2 9JT, United Kingdom, and Division of Cardiovascular and Diabetes Research, Faculty of Medicine and Health, LIGHT Laboratories, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Anthony T. Buxton
- Institute of Membrane and Systems Biology, Faculty of Biological Sciences, LIGHT Laboratories, University of Leeds, Leeds LS2 9JT, United Kingdom, and Division of Cardiovascular and Diabetes Research, Faculty of Medicine and Health, LIGHT Laboratories, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Maninder K. Bedi
- Institute of Membrane and Systems Biology, Faculty of Biological Sciences, LIGHT Laboratories, University of Leeds, Leeds LS2 9JT, United Kingdom, and Division of Cardiovascular and Diabetes Research, Faculty of Medicine and Health, LIGHT Laboratories, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - John B. C. Findlay
- Institute of Membrane and Systems Biology, Faculty of Biological Sciences, LIGHT Laboratories, University of Leeds, Leeds LS2 9JT, United Kingdom, and Division of Cardiovascular and Diabetes Research, Faculty of Medicine and Health, LIGHT Laboratories, University of Leeds, Leeds LS2 9JT, United Kingdom
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11
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Debily MA, Marhomy SE, Boulanger V, Eveno E, Mariage-Samson R, Camarca A, Auffray C, Piatier-Tonneau D, Imbeaud S. A functional and regulatory network associated with PIP expression in human breast cancer. PLoS One 2009; 4:e4696. [PMID: 19262752 PMCID: PMC2650800 DOI: 10.1371/journal.pone.0004696] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2008] [Accepted: 01/11/2009] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND The PIP (prolactin-inducible protein) gene has been shown to be expressed in breast cancers, with contradictory results concerning its implication. As both the physiological role and the molecular pathways in which PIP is involved are poorly understood, we conducted combined gene expression profiling and network analysis studies on selected breast cancer cell lines presenting distinct PIP expression levels and hormonal receptor status, to explore the functional and regulatory network of PIP co-modulated genes. PRINCIPAL FINDINGS Microarray analysis allowed identification of genes co-modulated with PIP independently of modulations resulting from hormonal treatment or cell line heterogeneity. Relevant clusters of genes that can discriminate between [PIP+] and [PIP-] cells were identified. Functional and regulatory network analyses based on a knowledge database revealed a master network of PIP co-modulated genes, including many interconnecting oncogenes and tumor suppressor genes, half of which were detected as differentially expressed through high-precision measurements. The network identified appears associated with an inhibition of proliferation coupled with an increase of apoptosis and an enhancement of cell adhesion in breast cancer cell lines, and contains many genes with a STAT5 regulatory motif in their promoters. CONCLUSIONS Our global exploratory approach identified biological pathways modulated along with PIP expression, providing further support for its good prognostic value of disease-free survival in breast cancer. Moreover, our data pointed to the importance of a regulatory subnetwork associated with PIP expression in which STAT5 appears as a potential transcriptional regulator.
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Affiliation(s)
- Marie-Anne Debily
- Array s/IMAGE, Genexpress, Functional Genomics and Systems Biology for Health, LGN-UMR 7091-CNRS and Pierre & Marie Curie University, Paris VI, Villejuif, France.
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Dörfler M, Tschammer N, Hamperl K, Hübner H, Gmeiner P. Novel D3 selective dopaminergics incorporating enyne units as nonaromatic catechol bioisosteres: synthesis, bioactivity, and mutagenesis studies. J Med Chem 2008; 51:6829-38. [PMID: 18834111 DOI: 10.1021/jm800895v] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Enynes of type 4 and 5 as long chain derivatives of the nonaromatic dopamine D 3 receptor agonist 3 (FAUC 73) were prepared by exploiting chemoselective functionalization of the azido-substituted vinyl triflate 9. Radioligand binding studies indicated excellent D 3 affinity and selectivity over related GPCRs for the terminal alkynes 4c (FAUC 460) and 5c. Biphasic displacement curves gave picomolar K i values for the high affinity binding site of D 3. According to mitogenesis experiments and bioluminescence based cAMP assays, the biphenylcarboxamide 4c and its click chemistry derived triazole analogue 5c behaved as strong partial agonists but relative ligand efficacy significantly depended on the type of functional assay. Site directed mutagenesis involving the mutants D 3 D3.32E, and D 3 F6.51W implied that ligand interactions with D3.32 and F6.51 are highly crucial, giving rise to analogous binding modes for dopamine, classical and enyne type agonists.
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Affiliation(s)
- Miriam Dörfler
- Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich Alexander University, Schuhstrasse 19, 91052 Erlangen, Germany
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13
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Melatonin receptors, heterodimerization, signal transduction and binding sites: what's new? Br J Pharmacol 2008; 154:1182-95. [PMID: 18493248 DOI: 10.1038/bjp.2008.184] [Citation(s) in RCA: 219] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Melatonin is a neurohormone that has been claimed to be involved in a wide range of physiological functions. Nevertheless, for most of its effects, the mechanism of action is not really known. In mammals, two melatonin receptors, MT1 and MT2, have been cloned. They belong to the G-protein-coupled receptor (GPCR) superfamily. They share some specific short amino-acid sequences, which suggest that they represent a specific subfamily. Another receptor from the same subfamily, the melatonin-related receptor has been cloned in different species including humans. This orphan receptor also named GPR50 does not bind melatonin and its endogenous ligand is still unknown. Nevertheless, this receptor has been shown to behave as an antagonist of the MT1 receptor, which opens new pharmacological perspectives for GPR50 despite the lack of endogenous or synthetic ligands. Moreover, MT1 and MT2 interact together through the formation of heterodimers at least in cells transfected with the cDNA of these two receptors. Lastly, signalling complexes associated with MT1 and MT2 receptors are starting to be deciphered. A third melatonin-binding site has been purified and characterized as the enzyme quinone reductase 2 (QR2). Inhibition of QR2 by melatonin may explain melatonin's protective effect that has been reported in different animal models and that is generally associated with its well-documented antioxidant properties.
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Gillen CM, Gao Y, Niehaus-Sauter MM, Wylde MR, Wheatly MG. Elongation factor 1Bgamma (eEF1Bgamma) expression during the molting cycle and cold acclimation in the crayfish Procambarus clarkii. Comp Biochem Physiol B Biochem Mol Biol 2008; 150:170-6. [PMID: 18407536 DOI: 10.1016/j.cbpb.2008.02.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Revised: 02/26/2008] [Accepted: 02/26/2008] [Indexed: 02/04/2023]
Abstract
Eukaryotic elongation factor 1Bgamma (eEF1Bgamma) is a subunit of elongation factor 1 (EF1), which regulates the recruitment of amino acyl-tRNAs to the ribosome during protein synthesis in eukaryotes. In addition to structural roles within eEF1, eEF1Bgamma has properties which suggest sensory or regulatory activities. We have cloned eEF1Bgamma from axial abdominal muscle of freshwater crayfish, Procambarus clarkii. The predicted amino acid sequence has 66% identity to Locusta migratoria eEF1Bgamma and 65% identity to Artemia salina eEF1Bgamma. We measured eEF1Bgamma expression by real-time PCR, using the relative quantification method with 18s ribosomal RNA as an internal calibrator. eEF1Bgamma expression was lowest in gill, axial abdominal muscle, and hepatopancreas, and was highest in the antennal gland (5.7-fold above hepatopancreas) and cardiac muscle (7.8-fold above hepatopancreas). In axial abdominal muscle, eEF1Bgamma expression was 4.4-fold higher in premolt and 11.9 higher in postmolt compared to intermolt. In contrast, eEF1Bgamma was decreased or unchanged in epithelial tissues during pre- and postmolt. eEF1Bgamma expression in the hepatopancreas was 3.5-fold higher during intermolt compared to premolt and was unchanged in gill and antennal gland. No significant differences in eEF1Bgamma were found after 1 week of acclimation to 4 degrees C. These results show that eEF1Bgamma is regulated at the mRNA level with tissue-specific differences in expression patterns.
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Intracellular complexes of the beta2 subunit of the nicotinic acetylcholine receptor in brain identified by proteomics. Proc Natl Acad Sci U S A 2007; 104:20570-5. [PMID: 18077321 DOI: 10.1073/pnas.0710314104] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Nicotine acetylcholine receptors (nAChRs) comprise a family of ligand-gated channels widely expressed in the mammalian brain. The beta2 subunit is an abundant protein subunit critically involved in the cognitive and behavioral properties of nicotine as well as in the mechanisms of nicotine addiction. In this work, we used matrix-assisted laser desorption ionization time-of-flight tandem mass spectrometry (MALDI-TOF-TOF MS/MS) to uncover protein interactions of the intracellular loop of the beta2 subunit and components of immunoprecipitated beta2-nAChR complexes from mouse brain. Using the beta2-knockout mouse to exclude nonspecific binding to the beta2 antibody, we identify 21 nAChR-interacting proteins (NIPs) expressed in brain. Western blot analysis confirmed the association between the beta2 subunit and candidate NIPs. Based on their functional profiles, the hypothesis is suggested that the identified NIPs can regulate the trafficking and signaling of the beta2-nAChR. Interactions of the beta2 subunit with NIPs such as G protein alpha, G protein-regulated inducer of neurite outgrowth 1, and G protein-activated K(+) channel 1 suggest a link between nAChRs and cellular G protein pathways. These findings reveal intracellular interactions of the beta2 subunit and may contribute to the understanding of the mechanisms of nAChR signaling and trafficking in neurons.
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Daulat AM, Maurice P, Froment C, Guillaume JL, Broussard C, Monsarrat B, Delagrange P, Jockers R. Purification and Identification of G Protein-coupled Receptor Protein Complexes under Native Conditions. Mol Cell Proteomics 2007; 6:835-44. [PMID: 17215244 DOI: 10.1074/mcp.m600298-mcp200] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
G protein-coupled receptors (GPCRs) constitute the largest family of membrane receptors and are of major therapeutic importance. The identification of GPCR-associated proteins is an important step toward a better understanding of these receptors. However, current methods are not satisfying as only isolated receptor domains (intracellular loops or carboxyl-terminal tails) can be used as "bait." We report here a method based on tandem affinity purification coupled to mass spectrometry that overcomes these limitations as the entire receptor is used to identify protein complexes formed in living mammalian cells. The human MT(1) and MT(2) melatonin receptors were chosen as model GPCRs. Both receptors were tagged with the tandem affinity purification tag at their carboxyl-terminal tails and expressed in human embryonic kidney 293 cells. Receptor solubilization and purification conditions were optimized. The method was validated by the co-purification of G(i) proteins, which are well known GPCR interaction partners but which are difficult to identify with current protein-protein interaction assays. Several new and functionally relevant MT(1)- and MT(2)-associated proteins were identified; some of them were common to both receptors, and others were specific for each subtype. Taken together, our protocol allowed for the first time the purification of GPCR-associated proteins under native conditions in quantities suitable for mass spectrometry analysis.
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MESH Headings
- Cell Line
- Chromatography, Affinity
- Chromatography, Liquid
- Humans
- Mass Spectrometry
- Multiprotein Complexes/isolation & purification
- Proteins/isolation & purification
- Receptor, Melatonin, MT1/chemistry
- Receptor, Melatonin, MT1/metabolism
- Receptor, Melatonin, MT2/chemistry
- Receptor, Melatonin, MT2/metabolism
- Recombinant Fusion Proteins/chemistry
- Recombinant Fusion Proteins/metabolism
- Spectrometry, Mass, Electrospray Ionization
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Affiliation(s)
- Avais M Daulat
- Department of Cell Biology, Institut Cochin, INSERM U567, CNRS UMR 8104, Université Paris Descartes, France
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Cho DI, Quan W, Oak MH, Choi HJ, Lee KY, Kim KM. Functional interaction between dopamine receptor subtypes for the regulation of c-fos expression. Biochem Biophys Res Commun 2007; 357:1113-8. [PMID: 17462594 DOI: 10.1016/j.bbrc.2007.04.066] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2007] [Accepted: 04/11/2007] [Indexed: 11/25/2022]
Abstract
Dopaminergic drugs increase the expression of the proto-oncogene, c-fos, in the brain, which is involved in the coordination of neurobiological changes caused by repeated cocaine or amphetamine use. This study examined the roles of five dopamine receptor subtypes on the c-fos promoter activity. D(1)R or D(5)R significantly increased the expression of c-fos promoter by activating protein kinase A. However, D(2)R, D(3)R, or D(4)R did not show any noticeable effects. The co-expression of D(1)R/D(3)R or D(1)R/D(2)R synergistically activated the basal and agonist-induced expression of the c-fos promoter, respectively. The Ral guanine-nucleotide-dissociation-stimulator-like, which was found to interact with the 3rd cytoplasmic loop of D(3)R, mediated the inhibitory activity of D(3)R in c-fos expression. In summary, the expression of the c-fos promoter was increased by the D1-like receptors and enhanced synergistically by the D2-like receptors via the modulation of cellular cAMP. D(3)R inhibited the expression of the c-fos promoter through an interaction with RGL.
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Affiliation(s)
- Dong-Im Cho
- Research Institute of Drug Development, College of Pharmacy, Chonnam National University, Kwang-Ju 500-757, Republic of Korea
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Ahlgren-Beckendorf JA, Levant B. Signaling Mechanisms of the D3Dopamine Receptor. J Recept Signal Transduct Res 2004; 24:117-30. [PMID: 15521358 DOI: 10.1081/rrs-200029953] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
A substantial body of evidence shows the capacity of the dopamine D3 receptor to couple functionally to G proteins when expressed in an appropriate milieu in heterologous expression systems. In these systems, activation of D3 receptors inhibits adenylate cyclase, modulates ion flow through potassium and calcium channels, and activates kinases, most notably mitogen-activated protein kinase. Coupling to Gi/Go is implicated in many of these effects, but other G proteins may contribute. Studies with chimeric receptors implicate the third intracellular loop in the mediation of agonist-induced signal transduction. Finally, D3-preferring drugs modulate expression of c-fos in neuronal cultures and brain. Signaling mechanisms of the D3 receptor in brain, however, remain to be definitively determined.
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