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Montalban E, Giralt A, Taing L, Nakamura Y, Pelosi A, Brown M, de Pins B, Valjent E, Martin M, Nairn AC, Greengard P, Flajolet M, Hervé D, Gambardella N, Roussarie JP, Girault JA. Operant Training for Highly Palatable Food Alters Translating Messenger RNA in Nucleus Accumbens D 2 Neurons and Reveals a Modulatory Role of Ncdn. Biol Psychiatry 2024; 95:926-937. [PMID: 37579933 PMCID: PMC11059129 DOI: 10.1016/j.biopsych.2023.08.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 08/04/2023] [Accepted: 08/04/2023] [Indexed: 08/16/2023]
Abstract
BACKGROUND Highly palatable food triggers behavioral responses including strong motivation. These effects involve the reward system and dopamine neurons, which modulate neurons in the nucleus accumbens (NAc). The molecular mechanisms underlying the long-lasting effects of highly palatable food on feeding behavior are poorly understood. METHODS We studied the effects of 2-week operant conditioning of mice with standard or isocaloric highly palatable food. We investigated the behavioral responses and dendritic spine modifications in the NAc. We compared the translating messenger RNA in NAc neurons identified by the type of dopamine receptors they express, depending on the kind of food and training. We tested the consequences of invalidation of an abundant downregulated gene, Ncdn. RESULTS Operant conditioning for highly palatable food increased motivation for food even in well-fed mice. In wild-type mice, free choice between regular and highly palatable food increased weight compared with access to regular food only. Highly palatable food increased spine density in the NAc. In animals trained for highly palatable food, translating messenger RNAs were modified in NAc neurons expressing dopamine D2 receptors, mostly corresponding to striatal projection neurons, but not in neurons expressing D1 receptors. Knockout of Ncdn, an abundant downregulated gene, opposed the conditioning-induced changes in satiety-sensitive feeding behavior and apparent motivation for highly palatable food, suggesting that downregulation may be a compensatory mechanism. CONCLUSIONS Our results emphasize the importance of messenger RNA alterations in D2 striatal projection neurons in the NAc in the behavioral consequences of highly palatable food conditioning and suggest a modulatory contribution of Ncdn downregulation.
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Affiliation(s)
- Enrica Montalban
- Institut National de la Santé et de la Recherche Médicale Unite Mixte de Recherche-S 1270, Paris, France; Faculty of Sciences and Engineering, Sorbonne Université, Paris, France; Institut du Fer à Moulin, Paris, France.
| | - Albert Giralt
- Institut National de la Santé et de la Recherche Médicale Unite Mixte de Recherche-S 1270, Paris, France; Faculty of Sciences and Engineering, Sorbonne Université, Paris, France; Institut du Fer à Moulin, Paris, France
| | - Lieng Taing
- Institut National de la Santé et de la Recherche Médicale Unite Mixte de Recherche-S 1270, Paris, France; Faculty of Sciences and Engineering, Sorbonne Université, Paris, France; Institut du Fer à Moulin, Paris, France
| | - Yuki Nakamura
- Institut National de la Santé et de la Recherche Médicale Unite Mixte de Recherche-S 1270, Paris, France; Faculty of Sciences and Engineering, Sorbonne Université, Paris, France; Institut du Fer à Moulin, Paris, France
| | - Assunta Pelosi
- Institut National de la Santé et de la Recherche Médicale Unite Mixte de Recherche-S 1270, Paris, France; Faculty of Sciences and Engineering, Sorbonne Université, Paris, France; Institut du Fer à Moulin, Paris, France
| | - Mallory Brown
- Laboratory of Molecular and Cellular Neuroscience, Rockefeller University, New York, New York
| | - Benoit de Pins
- Institut National de la Santé et de la Recherche Médicale Unite Mixte de Recherche-S 1270, Paris, France; Faculty of Sciences and Engineering, Sorbonne Université, Paris, France; Institut du Fer à Moulin, Paris, France
| | - Emmanuel Valjent
- Institut de Génomique Fonctionnelle, University of Montpellier, Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Montpellier, France
| | - Miquel Martin
- Eurecat, Centre Tecnològic de Catalunya, Unitat de Nutrició i Salut, Reus, Spain; Instituto de investigaciones médicas Hospital del Mar, Barcelona, Spain
| | - Angus C Nairn
- Department of Psychiatry, Yale School of Medicine, Connecticut Mental Health Center, New Haven, Connecticut
| | - Paul Greengard
- Laboratory of Molecular and Cellular Neuroscience, Rockefeller University, New York, New York
| | - Marc Flajolet
- Laboratory of Molecular and Cellular Neuroscience, Rockefeller University, New York, New York
| | - Denis Hervé
- Institut National de la Santé et de la Recherche Médicale Unite Mixte de Recherche-S 1270, Paris, France; Faculty of Sciences and Engineering, Sorbonne Université, Paris, France; Institut du Fer à Moulin, Paris, France
| | | | - Jean-Pierre Roussarie
- Laboratory of Molecular and Cellular Neuroscience, Rockefeller University, New York, New York
| | - Jean-Antoine Girault
- Institut National de la Santé et de la Recherche Médicale Unite Mixte de Recherche-S 1270, Paris, France; Faculty of Sciences and Engineering, Sorbonne Université, Paris, France; Institut du Fer à Moulin, Paris, France.
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Johansen VBI, Hampson E, Tsonou E, Pantarelli C, Chu JY, Crossland L, Okkenhaug H, Massey AJ, Hornigold DC, Welch HCE, Chetwynd SA. The GPCR adaptor protein Norbin regulates S1PR1 trafficking and the morphology, cell cycle and survival of PC12 cells. Sci Rep 2023; 13:18237. [PMID: 37880240 PMCID: PMC10600135 DOI: 10.1038/s41598-023-45148-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 10/16/2023] [Indexed: 10/27/2023] Open
Abstract
Norbin is an adaptor protein that binds numerous G protein-coupled receptors (GPCRs), is highly expressed in neurons, and is essential for a functioning nervous system in rodent models. Yet, beyond its control of neurite outgrowth and synaptic plasticity, few cellular roles of Norbin have been investigated to date. Furthermore, while Norbin is known to regulate the steady-state cell surface levels of several GPCRs, only in one case has the protein been shown to control the agonist-induced receptor internalisation which serves to attenuate GPCR signalling. Here, we generated a Norbin-deficient PC12 cell line which enabled us to study both the cellular functions of Norbin and its roles in GPCR trafficking and signalling. We show that Norbin limits cell size and spreading, and is required for the growth, viability and cell cycle progression of PC12 cells. We also found that Norbin regulates both the steady-state surface level and agonist-induced internalisation of the GPCR sphingosine-1-phosphate receptor 1 (S1PR1) in these cells, suggesting that its role in agonist-dependent GPCR trafficking is more widespread than previously appreciated. Finally, we show that Norbin limits the S1P-stimulated activation of Akt and p38 Mapk, and is required for the activation of Erk in PC12 cells. Together, our findings provide a better understanding of the cellular functions of Norbin and its control of GPCR trafficking.
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Affiliation(s)
- Valdemar B I Johansen
- Signalling Programme, The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, UK
- Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
- Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Elizabeth Hampson
- Signalling Programme, The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, UK
- Vernalis (R&D) Ltd., Cambridge, UK
| | - Elpida Tsonou
- Signalling Programme, The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, UK
- Bioscience Metabolism, Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | - Chiara Pantarelli
- Signalling Programme, The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, UK
| | - Julia Y Chu
- Signalling Programme, The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, UK
| | - Laraine Crossland
- Signalling Programme, The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, UK
| | | | | | - David C Hornigold
- Bioscience Metabolism, Research and Early Development, Cardiovascular, Renal and Metabolism (CVRM), BioPharmaceuticals R&D, AstraZeneca, Cambridge, UK
| | - Heidi C E Welch
- Signalling Programme, The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, UK.
| | - Stephen A Chetwynd
- Signalling Programme, The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, UK.
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Chetwynd SA, Andrews S, Inglesfield S, Delon C, Ktistakis NT, Welch HCE. Functions and mechanisms of the GPCR adaptor protein Norbin. Biochem Soc Trans 2023; 51:1545-1558. [PMID: 37503670 PMCID: PMC10586782 DOI: 10.1042/bst20221349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 06/27/2023] [Accepted: 07/07/2023] [Indexed: 07/29/2023]
Abstract
Norbin (Neurochondrin, NCDN) is a highly conserved 79 kDa adaptor protein that was first identified more than a quarter of a century ago as a gene up-regulated in rat hippocampus upon induction of long-term potentiation. Most research has focussed on the role of Norbin in the nervous system, where the protein is highly expressed. Norbin regulates neuronal morphology and synaptic plasticity, and is essential for normal brain development and homeostasis. Dysregulation of Norbin is linked to a variety of neurological conditions. Recently, Norbin was shown to be expressed in myeloid cells as well as neurons. Myeloid-cell specific deletion revealed an important role of Norbin as a suppressor of neutrophil-derived innate immunity. Norbin limits the ability of neutrophils to clear bacterial infections by curbing the responsiveness of these cells to inflammatory and infectious stimuli. Mechanistically, Norbin regulates cell responses through binding to its interactors, in particular to a wide range of G protein-coupled receptors (GPCRs). Norbin association with GPCRs controls GPCR trafficking and signalling. Other important Norbin interactors are the Rac guanine-nucleotide exchange factor P-Rex1 and protein kinase A. Downstream signalling pathways regulated by Norbin include ERK, Ca2+ and the small GTPase Rac. Here, we review the current understanding of Norbin structure, expression and its roles in health and disease. We also explore Norbin signalling through its interactors, with a particular focus on GPCR trafficking and signalling. Finally, we discuss avenues that could be pursued in the future to increase our understanding of Norbin biology.
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Affiliation(s)
| | - Simon Andrews
- Bioinformatics Facility, Babraham Institute, Cambridge, U.K
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CCCH-zinc finger antiviral protein relieves immunosuppression of T cell induced by avian leukosis virus subgroup J via NLP-PKC-δ-NFAT pathway. J Virol 2021; 96:e0134421. [PMID: 34705559 DOI: 10.1128/jvi.01344-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
CCCH-zinc finger antiviral protein (ZAP) can recognize and induce the degradation of mRNAs and proteins of certain viruses, as well as exert its antiviral activity by activating T cell. However, the mechanism of ZAP mediating T cell activation during virus infection remains unclear. Here, we found a potential function of ZAP that relieves immunosuppression of T cell induced by avian leukosis virus subgroup J (ALV-J) via a novel signaling pathway that involves norbin like protein (NLP), protein kinase C delta (PKC-δ) and nuclear factor of activated T cell (NFAT). Specifically, ZAP expression activated T cells by promoting the dephosphorylation and nuclear translocation of NFAT. Furthermore, knockdown of ZAP weakened the reactivity and antiviral response of T cells. Mechanistically, ZAP reduced PKC-δ activity by up-regulating and reactivating NLP through competitively binding with viral protein. Knockdown of NLP decreased the dephosphorylation of PKC-δ by ZAP expression. Moreover, we showed that knockdown of PKC-δ reduced the phosphorylation levels of NFAT and enhanced its nuclear translocation. Taken together, these data revealed that ZAP relieves immunosuppression caused by ALV-J and mediates T cell activation through NLP-PKC-δ-NFAT pathway. Importance The evolution of host defense system is driven synchronously in the process of resisting virus invasion. Accordingly, host innate defense factors exert effectively work in suppressing virus replication. However, it remains unclear that whether the host innate defense factors are involved in antiviral immune response against the invasion of immunosuppressive viruses. Here, we found that CCCH-type zinc finger antiviral protein (ZAP) effectively worked in resistance on immunosuppression caused by avian leukosis virus subgroup J (ALV-J), a classic immunosuppressive virus. Evidence showed that ZAP released the phosphatase activity of NLP inhibited by ALV-J and further activated NFAT by inactivating PKC-δ. This novel molecular mechanism that ZAP regulates antiviral immune response by mediating NLP-PKC-δ-NFAT pathway has greatly enriched the understanding of the functions of host innate defense factors and provided important scientific ideas and theoretical basis for the research of immunosuppressive virus and antiviral immunity.
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The GPCR adaptor protein norbin suppresses the neutrophil-mediated immunity of mice to pneumococcal infection. Blood Adv 2021; 5:3076-3091. [PMID: 34402884 DOI: 10.1182/bloodadvances.2020002782] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 04/27/2021] [Indexed: 12/25/2022] Open
Abstract
Streptococcal pneumonia is a worldwide health problem that kills ∼2 million people each year, particularly young children, the elderly, and immunosuppressed individuals. Alveolar macrophages and neutrophils provide the early innate immune response to clear pneumococcus from infected lungs. However, the level of neutrophil involvement is context dependent, both in humans and in mouse models of the disease, influenced by factors such as bacterial load, age, and coinfections. Here, we show that the G protein-coupled receptor (GPCR) adaptor protein norbin (neurochondrin, NCDN), which was hitherto known as a regulator of neuronal function, is a suppressor of neutrophil-mediated innate immunity. Myeloid norbin deficiency improved the immunity of mice to pneumococcal infection by increasing the involvement of neutrophils in clearing the bacteria, without affecting neutrophil recruitment or causing autoinflammation. It also improved immunity during Escherichia coli-induced septic peritonitis. It increased the responsiveness of neutrophils to a range of stimuli, promoting their ability to kill bacteria in a reactive oxygen species-dependent manner, enhancing degranulation, phagocytosis, and the production of reactive oxygen species and neutrophil extracellular traps, raising the cell surface levels of selected GPCRs, and increasing GPCR-dependent Rac and Erk signaling. The Rac guanine-nucleotide exchange factor Prex1, a known effector of norbin, was dispensable for most of these effects, which suggested that norbin controls additional downstream targets. We identified the Rac guanine-nucleotide exchange factor Vav as one of these effectors. In summary, our study presents the GPCR adaptor protein norbin as an immune suppressor that limits the ability of neutrophils to clear bacterial infections.
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Fatima A, Hoeber J, Schuster J, Koshimizu E, Maya-Gonzalez C, Keren B, Mignot C, Akram T, Ali Z, Miyatake S, Tanigawa J, Koike T, Kato M, Murakami Y, Abdullah U, Ali MA, Fadoul R, Laan L, Castillejo-López C, Liik M, Jin Z, Birnir B, Matsumoto N, Baig SM, Klar J, Dahl N. Monoallelic and bi-allelic variants in NCDN cause neurodevelopmental delay, intellectual disability, and epilepsy. Am J Hum Genet 2021; 108:739-748. [PMID: 33711248 PMCID: PMC8059333 DOI: 10.1016/j.ajhg.2021.02.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 02/21/2021] [Indexed: 12/14/2022] Open
Abstract
Neurochondrin (NCDN) is a cytoplasmatic neural protein of importance for neural growth, glutamate receptor (mGluR) signaling, and synaptic plasticity. Conditional loss of Ncdn in mice neural tissue causes depressive-like behaviors, impaired spatial learning, and epileptic seizures. We report on NCDN missense variants in six affected individuals with variable degrees of developmental delay, intellectual disability (ID), and seizures. Three siblings were found homozygous for a NCDN missense variant, whereas another three unrelated individuals carried different de novo missense variants in NCDN. We assayed the missense variants for their capability to rescue impaired neurite formation in human neuroblastoma (SH-SY5Y) cells depleted of NCDN. Overexpression of wild-type NCDN rescued the neurite-phenotype in contrast to expression of NCDN containing the variants of affected individuals. Two missense variants, associated with severe neurodevelopmental features and epilepsy, were unable to restore mGluR5-induced ERK phosphorylation. Electrophysiological analysis of SH-SY5Y cells depleted of NCDN exhibited altered membrane potential and impaired action potentials at repolarization, suggesting NCDN to be required for normal biophysical properties. Using available transcriptome data from human fetal cortex, we show that NCDN is highly expressed in maturing excitatory neurons. In combination, our data provide evidence that bi-allelic and de novo variants in NCDN cause a clinically variable form of neurodevelopmental delay and epilepsy, highlighting a critical role for NCDN in human brain development.
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Thompson LW, Morrison KD, Shirran SL, Groen EJN, Gillingwater TH, Botting CH, Sleeman JE. Neurochondrin interacts with the SMN protein suggesting a novel mechanism for spinal muscular atrophy pathology. J Cell Sci 2018; 131:jcs.211482. [PMID: 29507115 PMCID: PMC5963842 DOI: 10.1242/jcs.211482] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 02/16/2018] [Indexed: 12/15/2022] Open
Abstract
Spinal muscular atrophy (SMA) is an inherited neurodegenerative condition caused by a reduction in the amount of functional survival motor neuron (SMN) protein. SMN has been implicated in transport of mRNA in neural cells for local translation. We previously identified microtubule-dependent mobile vesicles rich in SMN and SNRPB, a member of the Sm family of small nuclear ribonucleoprotein (snRNP)-associated proteins, in neural cells. By comparing the interactomes of SNRPB and SNRPN, a neural-specific Sm protein, we now show that the essential neural protein neurochondrin (NCDN) interacts with Sm proteins and SMN in the context of mobile vesicles in neurites. NCDN has roles in protein localisation in neural cells and in maintenance of cell polarity. NCDN is required for the correct localisation of SMN, suggesting they may both be required for formation and transport of trafficking vesicles. NCDN may have potential as a therapeutic target for SMA together with, or in place of the targeting of SMN expression. This article has an associated First Person interview with the first author of the paper. Highlighted Article: The essential neural protein neurochondrin interacts with the spinal muscular atrophy (SMA) protein SMN in cell lines and in mice. This might be relevant to the molecular pathology of SMA.
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Affiliation(s)
- Luke W Thompson
- School of Biology, University of St Andrews, BSRC Complex, North Haugh St Andrews, KY16 9ST, UK
| | - Kim D Morrison
- School of Biology, University of St Andrews, BSRC Complex, North Haugh St Andrews, KY16 9ST, UK
| | - Sally L Shirran
- School of Biology, University of St Andrews, BSRC Complex, North Haugh St Andrews, KY16 9ST, UK
| | - Ewout J N Groen
- Edinburgh Medical School, Biomedical Sciences and Euan MacDonald Centre for Motor Neuron Disease Research, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK
| | - Thomas H Gillingwater
- Edinburgh Medical School, Biomedical Sciences and Euan MacDonald Centre for Motor Neuron Disease Research, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, UK
| | - Catherine H Botting
- School of Biology, University of St Andrews, BSRC Complex, North Haugh St Andrews, KY16 9ST, UK
| | - Judith E Sleeman
- School of Biology, University of St Andrews, BSRC Complex, North Haugh St Andrews, KY16 9ST, UK
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Pan D, Barber MA, Hornigold K, Baker MJ, Toth JM, Oxley D, Welch HCE. Norbin Stimulates the Catalytic Activity and Plasma Membrane Localization of the Guanine-Nucleotide Exchange Factor P-Rex1. J Biol Chem 2016; 291:6359-75. [PMID: 26792863 PMCID: PMC4813545 DOI: 10.1074/jbc.m115.686592] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Indexed: 12/15/2022] Open
Abstract
P-Rex1 is a guanine-nucleotide exchange factor (GEF) that activates the small G protein (GTPase) Rac1 to control Rac1-dependent cytoskeletal dynamics, and thus cell morphology. Three mechanisms of P-Rex1 regulation are currently known: (i) binding of the phosphoinositide second messenger PIP3, (ii) binding of the Gβγ subunits of heterotrimeric G proteins, and (iii) phosphorylation of various serine residues. Using recombinant P-Rex1 protein to search for new binding partners, we isolated the G-protein-coupled receptor (GPCR)-adaptor protein Norbin (Neurochondrin, NCDN) from mouse brain fractions. Coimmunoprecipitation confirmed the interaction between overexpressed P-Rex1 and Norbin in COS-7 cells, as well as between endogenous P-Rex1 and Norbin in HEK-293 cells. Binding assays with purified recombinant proteins showed that their interaction is direct, and mutational analysis revealed that the pleckstrin homology domain of P-Rex1 is required. Rac-GEF activity assays with purified recombinant proteins showed that direct interaction with Norbin increases the basal, PIP3- and Gβγ-stimulated Rac-GEF activity of P-Rex1. Pak-CRIB pulldown assays demonstrated that Norbin promotes the P-Rex1-mediated activation of endogenous Rac1 upon stimulation of HEK-293 cells with lysophosphatidic acid. Finally, immunofluorescence microscopy and subcellular fractionation showed that coexpression of P-Rex1 and Norbin induces a robust translocation of both proteins from the cytosol to the plasma membrane, as well as promoting cell spreading, lamellipodia formation, and membrane ruffling, cell morphologies generated by active Rac1. In summary, we have identified a novel mechanism of P-Rex1 regulation through the GPCR-adaptor protein Norbin, a direct P-Rex1 interacting protein that promotes the Rac-GEF activity and membrane localization of P-Rex1.
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Affiliation(s)
| | | | | | | | | | - David Oxley
- the Mass Spectrometry Facility, Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, United Kingdom
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Functional Analysis of Periplakin and Envoplakin, Cytoskeletal Linkers, and Cornified Envelope Precursor Proteins. Methods Enzymol 2015; 569:309-29. [PMID: 26778565 DOI: 10.1016/bs.mie.2015.06.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Envoplakin and periplakin are the two smallest plakin family cytoskeletal linker proteins that connect intermediate filaments to cellular junctions and other membrane locations. These two plakins have a structural role in the assembly of the cornified envelope (CE), the terminal stage of epidermal differentiation. Analysis of gene-targeted mice lacking both these plakins and the third initial CE scaffold protein, involucrin, demonstrate the importance of the structural integrity of CE for a proper epidermal barrier function. It has emerged that periplakin, which also has a wider tissue distribution than envoplakin, has additional, independent roles. Periplakin participates in the cytoskeletal organization also in other tissues and interacts with a wide range of membrane-associated proteins such as kazrin and butyrophilin BTN3A1. This review covers methods used to understand periplakin and envoplakin functions in cell culture models, including siRNA ablation of periplakin expression and the use of tagged protein domain constructs to study localization and interactions. In addition, assays that can be used to analyze CEs and epidermal barrier function in gene-targeted mice are described and discussed.
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Neurochondrin is an atypical RIIα-specific A-kinase anchoring protein. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:1667-75. [PMID: 25916936 DOI: 10.1016/j.bbapap.2015.04.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 04/13/2015] [Accepted: 04/15/2015] [Indexed: 12/25/2022]
Abstract
Protein kinase activity is regulated not only by direct strategies affecting activity but also by spatial and temporal regulatory mechanisms. Kinase signaling pathways are coordinated by scaffolding proteins that orchestrate the assembly of multi-protein complexes. One family of such scaffolding proteins are the A-kinase anchoring proteins (AKAPs). AKAPs share the commonality of binding cAMP-dependent protein kinase (PKA). In addition, they bind further signaling proteins and kinase substrates and tether such multi-protein complexes to subcellular locations. The A-kinase binding (AKB) domain of AKAPs typically contains a conserved helical motif that interacts directly with the dimerization/docking (D/D) domain of the regulatory subunits of PKA. Based on a pull-down proteomics approach, we identified neurochondrin (neurite-outgrowth promoting protein) as a previously unidentified AKAP. Here, we show that neurochondrin interacts directly with PKA through a novel mechanism that involves two distinct binding regions. In addition, we demonstrate that neurochondrin has strong isoform selectivity towards the RIIα subunit of PKA with nanomolar affinity. This article is part of a Special Issue entitled: Inhibitors of Protein Kinases.
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Saito Y, Hamamoto A, Kobayashi Y. Regulated Control of Melanin-Concentrating Hormone Receptor 1 through Posttranslational Modifications. Front Endocrinol (Lausanne) 2013; 4:154. [PMID: 24155742 PMCID: PMC3800845 DOI: 10.3389/fendo.2013.00154] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2013] [Accepted: 10/07/2013] [Indexed: 12/19/2022] Open
Abstract
Melanin-concentrating hormone (MCH) is a hypothalamic neuropeptide that plays an important role in feeding behavior. It activates two G-protein-coupled receptors, MCHR1 and MCHR2, of which MCHR1 is the primary regulator of food intake and energy homeostasis in rodents. In mammalian cells transfected with MCHR1, MCH is able to activate multiple signaling pathways including calcium mobilization, extracellular signal-regulated kinase activation, and inhibition of cyclic AMP generation through Gi/o- and Gq-coupled pathways. Further evidence suggests that MCHR1 is regulated through posttranslational modifications, which control its intracellular localization and provide appropriate cellular responses involving G-protein signaling. This review summarizes the current data on the control of MCHR1 function through glycosylation and phosphorylation, as related to cell function. Especially, a series of mutagenesis study highlights the importance of complete glycosylation of MCHR1 for efficient trafficking to the plasma membrane.
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Affiliation(s)
- Yumiko Saito
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan
- *Correspondence: Yumiko Saito, Graduate School of Integrated Arts and Sciences, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8521, Japan e-mail:
| | - Akie Hamamoto
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan
| | - Yuki Kobayashi
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan
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Xu S, Poidevin M, Han E, Bi J, Jin P. Circadian rhythm-dependent alterations of gene expression in Drosophila brain lacking fragile X mental retardation protein. PLoS One 2012; 7:e37937. [PMID: 22655085 PMCID: PMC3360013 DOI: 10.1371/journal.pone.0037937] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 04/26/2012] [Indexed: 11/18/2022] Open
Abstract
Fragile X syndrome is caused by the loss of the FMR1 gene product, fragile X mental retardation protein (FMRP). The loss of FMRP leads to altered circadian rhythm behaviors in both mouse and Drosophila; however, the molecular mechanism behind this phenomenon remains elusive. Here we performed a series of gene expression analyses, including of both mRNAs and microRNAs (miRNAs), and identified a number of mRNAs and miRNAs (miRNA-1 and miRNA-281) with circadian rhythm-dependent altered expression in dfmr1 mutant flies. Identification of these RNAs lays the foundation for future investigations of the molecular pathway(s) underlying the altered circadian rhythms associated with loss of dFmr1.
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Affiliation(s)
- Shunliang Xu
- Department of Neurology, 2nd Hospital of Shandong University, Jinan City, Shandong Province, People's Republic of China.
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Tonoike Y, Matsushita K, Tomonaga T, Katada K, Tanaka N, Shimada H, Nakatani Y, Okamoto Y, Nomura F. Adhesion molecule periplakin is involved in cellular movement and attachment in pharyngeal squamous cancer cells. BMC Cell Biol 2011; 12:41. [PMID: 21951621 PMCID: PMC3195110 DOI: 10.1186/1471-2121-12-41] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2011] [Accepted: 09/27/2011] [Indexed: 01/25/2023] Open
Abstract
Background We previously reported that periplakin (PPL) is downregulated in human esophageal cancer tissues compared to the adjacent non-cancer epithelium. Thus PPL could be a useful marker for detection of early esophageal cancer and evaluation of tumor progression, but largely remains unknown in this field. To investigate PPL involvement in carcinogenesis, tumor progression, cellular movement or attachment activity, siRNAs against PPL were transfected into pharyngeal squamous cancer cell lines and their effects on cellular behaviours were examined. Results PPL knockdown appeared to decrease tumor cell growth together with G2/M phase accumulation in cells attached to a culture dish. However, the extent of cell growth suppression, evaluated by the number of cells attached to the culture dish, was too distinctive to be explained only by cell cycle delay. Importantly, PPL knockdown suppressed cellular movement and attachment to the culture dish accompanied by decreased pAktSer473 phosphorylation. Additionally, LY294002, a PI3K inhibitor that dephosphorylates pAktSer473, significantly suppressed D562 cell migration. Thus PPL potentially engages in cellular movement al least partly via the PI3K/Akt axis. Conclusions PPL knockdown is related to reduced cellular movement and attachment activity in association with PI3K/Akt axis suppression, rather than malignant progression in pharyngeal cancer cells.
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Affiliation(s)
- Yurie Tonoike
- Department of Otorhinolaryngology, Chiba University Hospital, Chiba City, Japan
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15
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Maurice P, Guillaume JL, Benleulmi-Chaachoua A, Daulat AM, Kamal M, Jockers R. GPCR-Interacting Proteins, Major Players of GPCR Function. PHARMACOLOGY OF G PROTEIN COUPLED RECEPTORS 2011; 62:349-80. [DOI: 10.1016/b978-0-12-385952-5.00001-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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16
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Eberle AN, Mild G, Zumsteg U. Cellular models for the study of the pharmacology and signaling of melanin-concentrating hormone receptors. J Recept Signal Transduct Res 2010; 30:385-402. [PMID: 21083507 DOI: 10.3109/10799893.2010.524223] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cellular models for the study of the neuropeptide melanin-concentrating hormone (MCH) have become indispensable tools for pharmacological profiling and signaling analysis of MCH and its synthetic analogues. Although expression of MCH receptors is most abundant in the brain, MCH-R(1) is also found in different peripheral tissues. Therefore, not only cell lines derived from nervous tissue but also from peripheral tissues that naturally express MCH receptors have been used to study receptor signaling and regulation. For screening of novel compounds, however, heterologous expression of MCH-R(1) or MCH-R(2) genes in HEK293, Chinese hamster ovary, COS-7, or 3T3-L1 cells, or amplified MCH-R(1) expression/signaling in IRM23 cells transfected with the G(q) protein gene are the preferred tools because of more distinct pharmacological effects induced by MCH, which include inhibition of cAMP formation, stimulation of inositol triphosphate production, increase in intracellular free Ca(2+) and/or activation of mitogen-activated protein kinases. Most of the published data originate from this type of model system, whereas data based on studies with cell lines endogenously expressing MCH receptors are more limited. This review presents an update on the different cellular models currently used for the analysis of MCH receptor interaction and signaling.
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Affiliation(s)
- Alex N Eberle
- Laboratory of Endocrinology, Department of Biomedicine, University Hospital and University Children's Hospital, University of Basel, Basel, Switzerland
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17
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Wang H, Nong Y, Bazan F, Greengard P, Flajolet M. Norbin: A promising central nervous system regulator. Commun Integr Biol 2010; 3:487-90. [PMID: 21331221 DOI: 10.4161/cib.3.6.12844] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2010] [Accepted: 06/29/2010] [Indexed: 11/19/2022] Open
Abstract
Norbin, a neurite-outgrowth promoting protein, has been found to interact with and regulate several membrane proteins, including metabotropic glutamate receptor 5 (mGluR5). The disruption of both Norbin alleles leads to early embryonic death between 3.5 and 6.5 day post coitus.1 Forebrain specific Norbin knockout (KO) mice are defective in synaptic plasticity,2 an interesting feature considering that Norbin was initially discovered in the context of chemical-induced long term potentiation (LTP),3 a form of synaptic plasticity extensively studied in the context of learning and memory.4 The behavioral phenotypes associated with Norbin conditional KO suggest reduced mGluR5 function. Because of its fundamental functions, Norbin is emerging as a key neuronal regulator. The aim of the present review is to summarize current knowledge about Norbin while emphasizing its role in the nervous system.
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Affiliation(s)
- Hong Wang
- Laboratory of Molecular and Cellular Neuroscience; The Rockefeller University; New York, NY USA
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18
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Cook LB, Shum L, Portwood S. Melanin-concentrating hormone facilitates migration of preadipocytes. Mol Cell Endocrinol 2010; 320:45-50. [PMID: 20171260 DOI: 10.1016/j.mce.2010.02.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 12/21/2009] [Accepted: 02/04/2010] [Indexed: 10/19/2022]
Abstract
Adipose tissue develops from differentiating preadipocytes that expand and migrate. 3T3-L1 preadipocytes respond to melanin-concentrating hormone (MCH) by increasing leptin production. Here, we investigate whether MCH elicits remodeling of the actin cytoskeleton and whether this translates into altered migratory capacity of these cells. Incubation with MCH resulted in a loss of actin stress fibers accompanied by a change in morphology from a stretched-out fibroblast to a rounded cell. PMC-3881-PI, a MCH receptor 1 antagonist blocked the effect, confirming this receptor is solely responsible for MCH-mediated actin rearrangements. Both a pharmacological activator and inhibitor of phospholipase C were used to demonstrate this molecule's importance to the signaling pathway. Finally, MCH was shown to facilitate preadipocyte migration into a scratch wound, revealing a previously unknown role for MCH in the regulation of cellular migration. We conclude that MCH could influence the expansion of adipose tissue through its ability to enhance preadipocyte migration.
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Affiliation(s)
- Laurie B Cook
- Department of Biology, The College at Brockport, State University of New York, 350 New Campus Drive, Brockport, NY 14420, USA.
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19
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Ritter SL, Hall RA. Fine-tuning of GPCR activity by receptor-interacting proteins. Nat Rev Mol Cell Biol 2009; 10:819-30. [PMID: 19935667 DOI: 10.1038/nrm2803] [Citation(s) in RCA: 362] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
G protein-coupled receptors (GPCRs) mediate physiological responses to various ligands, such as hormones, neurotransmitters and sensory stimuli. The signalling and trafficking properties of GPCRs are often highly malleable depending on the cellular context. Such fine-tuning of GPCR function can be attributed in many cases to receptor-interacting proteins that are differentially expressed in distinct cell types. In some cases these GPCR-interacting partners directly mediate receptor signalling, whereas in other cases they act mainly as scaffolds to modulate G protein-mediated signalling. Furthermore, GPCR-interacting proteins can have a big impact on the regulation of GPCR trafficking, localization and/or pharmacological properties.
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Affiliation(s)
- Stefanie L Ritter
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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20
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Chung S, Saito Y, Civelli O. MCH receptors/gene structure-in vivo expression. Peptides 2009; 30:1985-9. [PMID: 19647772 PMCID: PMC2764003 DOI: 10.1016/j.peptides.2009.07.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2009] [Revised: 07/22/2009] [Accepted: 07/23/2009] [Indexed: 11/17/2022]
Abstract
Melanin-concentrating hormone (MCH) is a cyclic peptide which was originally discovered in fish to lighten skin color by affecting melanosomes aggregation. This peptide is highly conserved and also found in rodents whose gene is overexpressed upon fasting. However, the site of MCH action remained obscure until its receptor was discovered in 1999 as a G protein-coupled receptor. After this receptor structure was identified, the functional domains important for MCH-MCHR interaction were revealed. Moreover, the cloning of the MCH receptor led us to identify the in vivo sites of MCH action which suggested potential physiological functions of the MCH system. Furthermore, the MCH receptor identification allow for designing surrogate molecules which can block MCH activity. Studies using these molecules revealed various physiological functions of the MCH system not only in feeding but also in other physiological responses such as stress and emotion. This review will discuss how the MCH receptor was discovered and its impact on many studies investigating the MCH receptor's structure, signaling pathways, and expression pattern.
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Affiliation(s)
- Shinjae Chung
- Department of Pharmacology, University of California, Irvine, Irvine, CA, USA
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA, USA
| | - Yumiko Saito
- Laboratory for Behavioral Neuroscience, Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan
| | - Olivier Civelli
- Department of Pharmacology, University of California, Irvine, Irvine, CA, USA
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA, USA
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21
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Gao XB. Electrophysiological effects of MCH on neurons in the hypothalamus. Peptides 2009; 30:2025-30. [PMID: 19463877 PMCID: PMC2782585 DOI: 10.1016/j.peptides.2009.05.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Revised: 05/06/2009] [Accepted: 05/07/2009] [Indexed: 11/21/2022]
Abstract
Melanin concentrating hormone (MCH) has been implicated in many brain functions and behaviors essential to the survival of animals. The hypothalamus is one of the primary targets where MCH-containing nerve fibers and MCH receptors are extensively expressed and its actions in the brain are exerted. Since the identification of MCH receptors as orphan G protein coupled receptors, the cellular effects of MCH have been revealed in many non-neuronal expression systems (including Xenopus oocytes and cell lines), however, the mechanism by which MCH modulates the activity in the neuronal circuitry of the brain is still under investigation. This review summarizes our current knowledge of electrophysiological effects of MCH on neurons in the hypothalamus, particularly in the lateral hypothalamus. Generally, MCH exerts inhibitory effects on neurons in this structure and may serve as a homeostatic regulator in the lateral hypothalamic area. Given the contrast between the limited data on cellular functions of MCH in the hypothalamus versus a fast growing body of evidence on the vital role of MCH in animal behavior, further investigations of the former are warranted.
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Affiliation(s)
- Xiao-Bing Gao
- Department of OB/GYN and Reproductive Science, Yale University School of Medicine, New Haven, CT 06520, USA.
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22
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Localization of the succinate receptor in the distal nephron and its signaling in polarized MDCK cells. Kidney Int 2009; 76:1258-67. [PMID: 19776718 DOI: 10.1038/ki.2009.360] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
When the succinate receptor (SUCNR1) is activated in the afferent arterioles of the glomerulus it increases renin release and induces hypertension. To study its location in other nephron segments and its role in kidney function, we performed immunohistochemical analysis and found that SUCNR1 is located in the luminal membrane of macula densa cells of the juxtaglomerular apparatus in close proximity to renin-producing granular cells, the cortical thick ascending limb, and cortical and inner medullary collecting duct cells. In order to study its signaling, SUCNR1 was stably expressed in Madin-Darby Canine Kidney (MDCK) cells, where it localized to the apical membrane. Activation of the cells by succinate caused Gq and Gi-mediated intracellular calcium mobilization, transient phosphorylation of extracellular regulated kinase (ERK)1/2 and the release of arachidonic acid along with prostaglandins E2 and I2. Signaling was desensitized without receptor internalization but rapidly resensitized upon succinate removal. Immunohistochemical evidence of phosphorylated ERK1/2 was found in cortical collecting duct cells of wild type but not SUCNR1 knockout streptozotocin-induced diabetic mice, indicating in vivo relevance. Since urinary succinate concentrations in health and disease are in the activation range of the SUCNR1, this receptor can sense succinate in the luminal fluid. Our study suggests that changes in the luminal succinate concentration may regulate several aspects of renal function.
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Wang L, Martin B, Brenneman R, Luttrell LM, Maudsley S. Allosteric modulators of g protein-coupled receptors: future therapeutics for complex physiological disorders. J Pharmacol Exp Ther 2009; 331:340-8. [PMID: 19667132 DOI: 10.1124/jpet.109.156380] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are one of the most important classes of proteins in the genome, not only because of their tremendous molecular diversity but because they are the targets of nearly 50% of current pharmacotherapeutics. The majority of these drugs affect GPCR activity by binding to a similar molecular site as the endogenous cognate ligand for the receptor. These "orthosterically" targeted drugs currently dominate the existing pharmacopeia. Over the past two decades, novel opportunities for drug discovery have risen from a greater understanding of the complexity of GPCR signaling. A striking example of this is the appreciation that many GPCRs possess functional allosteric binding sites. Allosteric modulator ligands bind receptor domains topographically distinct from the orthosteric site, altering the biological activity of the orthosteric ligand by changing its binding affinity, functional efficacy, or both. This additional receptor signaling complexity can be embraced and exploited for the next generation of GPCR-targeted therapies. Despite the challenges associated with detecting and quantifying the myriad of possible allosteric effects on GPCR activity, allosteric ligands offer the prospect of engendering a facile stimulus-bias in orthosteric ligand signaling, paving the way for not only receptor-selective but also signaling pathway-selective therapies. Allosteric modulators possess specific advantages when considering the treatment of multifactorial syndromes, such as metabolic diseases or age-related cognitive impairment, because they may not greatly affect neurotransmitter or hormone release patterns, thus maintaining the integrity of complex signaling networks that underlie perception, memory patterns, or neuroendocrinological axes while introducing therapeutically beneficial signal bias.
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Affiliation(s)
- Liyun Wang
- Receptor Pharmacology Unit, and Metabolism Unit, the National Institutes of Health, National Institute on Aging, Baltimore, Maryland 21224, USA
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24
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Ward RJ, Jenkins L, Milligan G. Selectivity and functional consequences of interactions of family A G protein-coupled receptors with neurochondrin and periplakin. J Neurochem 2009; 109:182-92. [PMID: 19166508 DOI: 10.1111/j.1471-4159.2009.05918.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A wide range of intracellular proteins have been demonstrated to interact with individual G protein-coupled receptors (GPCRs) and, in certain cases, to modulate their function or trafficking. However, in only a few cases have the GPCR selectivity of such interactions been investigated. Interactions between the intracellular C-terminal tails of 44 GPCRs and both neurochondrin and periplakin were assessed in pull-down studies. 23 of these interacted with neurochondrin and periplakin, 10 interacted with neither whilst nine interacted with only neurochondrin and two with only periplakin. When appropriate GIP-interacting G(q)/G(11)-coupled GPCRs were expressed in cells inducibly expressing neurochondrin or periplakin this resulted in a reduction in the increase in intracellular [Ca(2+)] in response to agonist. However, induction of neurochondrin or periplakin was without functional consequences for GPCRs with which they did not interact. Unlike intracellular [Ca(2+)] signals, induction of expression of either interacting protein did not inhibit agonist-mediated ERK1/2 MAPK phosphorylation. These data indicate that both periplakin and neurochondrin can interact with a wide range of GPCRs and modulate function selectively. Details of the structure of the intracellular C-terminal tail of individual receptors will be required to fully understand the basis of such selectivity.
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Affiliation(s)
- Richard J Ward
- Molecular Pharmacology Group, Neuroscience and Molecular Pharmacology, Faculty of Biomedical and Life Sciences, University of Glasgow, Glasgow, UK
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25
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Miyamoto-Matsubara M, Saitoh O, Maruyama K, Aizaki Y, Saito Y. Regulation of melanin-concentrating hormone receptor 1 signaling by RGS8 with the receptor third intracellular loop. Cell Signal 2008; 20:2084-94. [PMID: 18760349 DOI: 10.1016/j.cellsig.2008.07.019] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Revised: 07/27/2008] [Accepted: 07/31/2008] [Indexed: 11/26/2022]
Abstract
Melanin-concentrating hormone (MCH) receptor 1 (MCH1R) belongs to the class A G protein-coupled receptors (GPCRs). The MCH-MCH1R system plays a central role in energy metabolism, and thus the regulation of signaling pathways activated by this receptor is of particular interest. Regulator of G protein signaling (RGS) proteins work by increasing the GTPase activity of G protein alpha subunits and attenuate cellular responses coupled with G proteins. Recent evidence has shown that RGS proteins are not simple G protein regulators but equally inhibit the signaling from various GPCRs. Here, we demonstrate that RGS8, which is highly expressed in the brain, functions as a negative modulator of MCH1R signaling. By using biochemical approaches, RGS8 was found to selectively and directly bind to the third intracellular (i3) loop of MCH1R in vitro. When expressed in HEK293T cells, RGS8 and MCH1R colocalized to the plasma membrane and RGS8 potently inhibited the calcium mobilization induced by MCH. The N-terminal 9 amino acids of RGS8 were required for the optimal capacity to downregulate the receptor signaling. Furthermore, Arg(253) and Arg(256) at the distal end of the i3 loop were found to comprise a structurally important site for the functional interaction with RGS8, since coexpression of RGS8 with R253Q/R256Q mutant receptors resulted in a loss of induction of MCH-stimulated calcium mobilization. This functional association suggests that RGS8 may represent a new therapeutic target for the development of novel pharmaceutical agents.
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Affiliation(s)
- Mayumi Miyamoto-Matsubara
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Kagamiyama, Hiroshima 739-8521, Japan
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26
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Saito Y, Nagasaki H. The melanin-concentrating hormone system and its physiological functions. Results Probl Cell Differ 2008; 46:159-179. [PMID: 18227983 DOI: 10.1007/400_2007_052] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Melanin-concentrating hormone (MCH) is a neuropeptide that was originally isolated from salmon pituitary where it causes pigment aggregation. MCH is also abundantly present in mammalian neurons and expressed in the lateral hypothalamus and zona incerta, brain regions that are known to be at the center of feeding behavior. MCH binds to and activates two G protein-coupled receptors, MCH1R and MCH2R. Although MCH2R is non-functional in rodents, genetic and pharmacological studies have demonstrated that rodent MCH1R is involved in the regulation of feeding behavior and energy balance. Unexpectedly, some antagonists have provided evidence that MCH signaling participates in the regulation of other processes, such as emotion and stress. The discovery of MCH receptors has extensively promoted the progress of MCH studies and may represent an ideal example of how deorphanized receptors can open new directions toward more detailed physiological studies.
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Affiliation(s)
- Yumiko Saito
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Hiroshima, Japan.
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27
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Leach K, Sexton PM, Christopoulos A. Allosteric GPCR modulators: taking advantage of permissive receptor pharmacology. Trends Pharmacol Sci 2007; 28:382-9. [PMID: 17629965 DOI: 10.1016/j.tips.2007.06.004] [Citation(s) in RCA: 281] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 05/29/2007] [Accepted: 06/27/2007] [Indexed: 10/23/2022]
Abstract
The past decade has witnessed a dramatic increase in the identification of allosteric modulators of G-protein-coupled receptor (GPCR) activity. Concomitantly, several new perspectives and hypotheses regarding the way ligands regulate GPCR signalling have also emerged. Here, we briefly discuss how the concepts of collateral efficacy and permissive agonism-antagonism intersect the field of allosteric GPCR modulation. Despite the challenges associated with detecting and quantifying the myriad of possible allosteric effects on GPCR activity, it is proposed that allosteric ligands offer the exciting prospect of engendering stimulus-bias in orthosteric ligand signalling, thus paving the way for not only receptor-selective but also signalling-pathway-selective therapies.
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Affiliation(s)
- Katie Leach
- Drug Discovery Biology Laboratory, Department of Pharmacology, Monash University, Clayton, Victoria 3800, Australia
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