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Ma S, Yin X, Pin JP, Rondard P, Yi P, Liu J. Absence of calcium-sensing receptor basal activity due to inter-subunit disulfide bridges. Commun Biol 2024; 7:501. [PMID: 38664468 PMCID: PMC11045811 DOI: 10.1038/s42003-024-06189-3] [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: 08/21/2023] [Accepted: 04/12/2024] [Indexed: 04/28/2024] Open
Abstract
G protein-coupled receptors naturally oscillate between inactive and active states, often resulting in receptor constitutive activity with important physiological consequences. Among the class C G protein-coupled receptors that typically sense amino-acids and their derivatives, the calcium sensing receptor (CaSR) tightly controls blood calcium levels. Its constitutive activity has not yet been studied. Here, we demonstrate the importance of the inter-subunit disulfide bridges in maintaining the inactive state of CaSR, resulting in undetectable constitutive activity, unlike the other class C receptors. Deletion of these disulfide bridges results in strong constitutive activity that is abolished by mutations preventing amino acid binding. It shows that this inter-subunit disulfide link is necessary to limit the agonist effect of amino acids on CaSR. Furthermore, human genetic mutations deleting these bridges and associated with hypocalcemia result in elevated CaSR constitutive activity. These results highlight the physiological importance of fine tuning the constitutive activity of G protein-coupled receptors.
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Affiliation(s)
- Shumin Ma
- Cellular Signaling Laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Xueliang Yin
- Cellular Signaling Laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Jean-Philippe Pin
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, Montpellier, Cedex 5, France
| | - Philippe Rondard
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, Montpellier, Cedex 5, France.
| | - Ping Yi
- Cellular Signaling Laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China.
| | - Jianfeng Liu
- Cellular Signaling Laboratory, International Research Center for Sensory Biology and Technology of MOST, Key Laboratory of Molecular Biophysics of MOE, and College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China.
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2
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Yang Z, Wang JY, Yang F, Zhu KK, Wang GP, Guan Y, Ning SL, Lu Y, Li Y, Zhang C, Zheng Y, Zhou SH, Wang XW, Wang MW, Xiao P, Yi F, Zhang C, Zhang PJ, Xu F, Liu BH, Zhang H, Yu X, Gao N, Sun JP. Structure of GPR101-Gs enables identification of ligands with rejuvenating potential. Nat Chem Biol 2024; 20:484-492. [PMID: 37945893 DOI: 10.1038/s41589-023-01456-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 09/21/2023] [Indexed: 11/12/2023]
Abstract
GPR101 is an orphan G protein-coupled receptor actively participating in energy homeostasis. Here we report the cryo-electron microscopy structure of GPR101 constitutively coupled to Gs heterotrimer, which reveals unique features of GPR101, including the interaction of extracellular loop 2 within the 7TM bundle, a hydrophobic chain packing-mediated activation mechanism and the structural basis of disease-related mutants. Importantly, a side pocket is identified in GPR101 that facilitates in silico screening to identify four small-molecule agonists, including AA-14. The structure of AA-14-GPR101-Gs provides direct evidence of the AA-14 binding at the side pocket. Functionally, AA-14 partially restores the functions of GH/IGF-1 axis and exhibits several rejuvenating effects in wild-type mice, which are abrogated in Gpr101-deficient mice. In summary, we provide a structural basis for the constitutive activity of GPR101. The structure-facilitated identification of GPR101 agonists and functional analysis suggest that targeting this orphan receptor has rejuvenating potential.
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Affiliation(s)
- Zhao Yang
- NHC Key Laboratory of Otorhinolaryngology, Qilu Hospital of Shandong University, and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Jun-Yan Wang
- NHC Key Laboratory of Otorhinolaryngology, Qilu Hospital of Shandong University, and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
- Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, China
| | - Fan Yang
- NHC Key Laboratory of Otorhinolaryngology, Qilu Hospital of Shandong University, and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
- Advanced Medical Research Institute, Meili Lake Translational Research Park, Cheeloo College of Medicine, Shandong University, Jinan, China
- Key Laboratory Experimental Teratology of the Ministry of Education, Department of Physiology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Kong-Kai Zhu
- Advanced Medical Research Institute, Meili Lake Translational Research Park, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Guo-Peng Wang
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Ying Guan
- NHC Key Laboratory of Otorhinolaryngology, Qilu Hospital of Shandong University, and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
- Advanced Medical Research Institute, Meili Lake Translational Research Park, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Shang-Lei Ning
- Department of General Surgery, Qilu Hospital of Shandong University, Jinan, China
| | - Yan Lu
- NHC Key Laboratory of Otorhinolaryngology, Qilu Hospital of Shandong University, and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Yu Li
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China
| | - Chao Zhang
- NHC Key Laboratory of Otorhinolaryngology, Qilu Hospital of Shandong University, and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Yuan Zheng
- Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, China
- Key Laboratory of Molecular Cardiovascular Science, Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Ministry of Education, Beijing, China
| | - Shu-Hua Zhou
- Key Laboratory Experimental Teratology of the Ministry of Education, Department of Physiology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Xin-Wen Wang
- NHC Key Laboratory of Otorhinolaryngology, Qilu Hospital of Shandong University, and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Ming-Wei Wang
- NHC Key Laboratory of Otorhinolaryngology, Qilu Hospital of Shandong University, and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Peng Xiao
- NHC Key Laboratory of Otorhinolaryngology, Qilu Hospital of Shandong University, and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Fan Yi
- Key Laboratory of Infection and Immunity of Shandong Province, Department of Pharmacology, School of Basic Medical Sciences, Shandong University, Jinan, China
| | - Cheng Zhang
- National Key Laboratory for Innovation and Transformation of Luobing Theory, Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese National Health Commission and Chinese Academy of Medical Sciences, Department of Cardiology, Qilu Hospital of Shandong University, Jinan, China
| | - Peng-Ju Zhang
- NHC Key Laboratory of Otorhinolaryngology, Qilu Hospital of Shandong University, and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Fei Xu
- iHuman Institute, ShanghaiTech University, Shanghai, China
| | - Bao-Hua Liu
- Shenzhen Key Laboratory for Systemic Aging and Intervention (SKL-SAI), School of Basic Medical Sciences, Shenzhen University, Shenzhen, China
| | - Hua Zhang
- School of Biological Science and Technology, University of Jinan, Jinan, China
| | - Xiao Yu
- Key Laboratory Experimental Teratology of the Ministry of Education, Department of Physiology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China.
| | - Ning Gao
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China.
| | - Jin-Peng Sun
- NHC Key Laboratory of Otorhinolaryngology, Qilu Hospital of Shandong University, and Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, China.
- Beijing Key Laboratory of Cardiovascular Receptors Research, Beijing, China.
- Advanced Medical Research Institute, Meili Lake Translational Research Park, Cheeloo College of Medicine, Shandong University, Jinan, China.
- Key Laboratory of Molecular Cardiovascular Science, Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University, Ministry of Education, Beijing, China.
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3
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Wang Y, Ngo VA, Wang X. Stereoselective recognition of morphine enantiomers by μ-opioid receptor. Natl Sci Rev 2024; 11:nwae029. [PMID: 38410825 PMCID: PMC10896590 DOI: 10.1093/nsr/nwae029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 12/11/2023] [Accepted: 12/14/2023] [Indexed: 02/28/2024] Open
Abstract
Stereospecific recognition of chiral molecules plays a crucial role in biological systems. The μ-opioid receptor (MOR) exhibits binding affinity towards (-)-morphine, a well-established gold standard in pain management, while it shows minimal binding affinity for the (+)-morphine enantiomer, resulting in a lack of analgesic activity. Understanding how MOR stereoselectively recognizes morphine enantiomers has remained a puzzle in neuroscience and pharmacology for over half-a-century due to the lack of direct observation techniques. To unravel this mystery, we constructed the binding and unbinding processes of morphine enantiomers with MOR via molecular dynamics simulations to investigate the thermodynamics and kinetics governing MOR's stereoselective recognition of morphine enantiomers. Our findings reveal that the binding of (-)-morphine stabilizes MOR in its activated state, exhibiting a deep energy well and a prolonged residence time. In contrast, (+)-morphine fails to sustain the activation state of MOR. Furthermore, the results suggest that specific residues, namely D1142.50 and D1473.32, are deprotonated in the active state of MOR bound to (-)-morphine. This work highlights that the selectivity in molecular recognition goes beyond binding affinities, extending into the realm of residence time.
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Affiliation(s)
- Yibo Wang
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Van A Ngo
- Advanced Computing for Life Sciences and Engineering Group, Science Engagement Section, National Center for Computational Sciences, Oak Ridge National Lab, Oak Ridge 37831, USA
| | - Xiaohui Wang
- Laboratory of Chemical Biology, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
- School of Applied Chemistry and Engineering, University of Science and Technology of China, Hefei 230026, China
- Beijing National Laboratory for Molecular Sciences, Beijing 100190, China
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4
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Sridhar PS, Vasquez V, Monteil-Rivera F, Allingham JS, Loewen MC. A peroxidase-derived ligand that induces Fusarium graminearum Ste2 receptor-dependent chemotropism. Front Cell Infect Microbiol 2024; 13:1287418. [PMID: 38239502 PMCID: PMC10794396 DOI: 10.3389/fcimb.2023.1287418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 12/06/2023] [Indexed: 01/22/2024] Open
Abstract
Introduction The fungal G protein-coupled receptors Ste2 and Ste3 are vital in mediating directional hyphal growth of the agricultural pathogen Fusarium graminearum towards wheat plants. This chemotropism is induced by a catalytic product of peroxidases secreted by the wheat. Currently, the identity of this product, and the substrate it is generated from, are not known. Methods and results We provide evidence that a peroxidase substrate is derived from F. graminearum conidia and report a simple method to extract and purify the FgSte2-activating ligand for analyses by mass spectrometry. The mass spectra arising from t he ligand extract are characteristic of a 400 Da carbohydrate moiety. Consistent with this type of molecule, glycosidase treatment of F. graminearum conidia prior to peroxidase treatment significantly reduced the amount of ligand extracted. Interestingly, availability of the peroxidase substrate appears to depend on the presence of both FgSte2 and FgSte3, as knockout of one or the other reduces the chemotropism-inducing effect of the extracts. Conclusions While further characterization is necessary, identification of the F. graminearum-derived peroxidase substrate and the FgSte2-activating ligand will unearth deeper insights into the intricate mechanisms that underlie fungal pathogenesis in cereal crops, unveiling novel avenues for inhibitory interventions.
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Affiliation(s)
- Pooja S. Sridhar
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, ON, Canada
| | - Vinicio Vasquez
- National Research Council of Canada, Aquatic and Crop Resources Development, Montreal, QC, Canada
| | - Fanny Monteil-Rivera
- National Research Council of Canada, Aquatic and Crop Resources Development, Montreal, QC, Canada
| | - John S. Allingham
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, ON, Canada
| | - Michele C. Loewen
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, ON, Canada
- National Research Council of Canada, Aquatic and Crop Resources Development, Ottawa, ON, Canada
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5
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Impact of 5-HT 6 Receptor Subcellular Localization on Its Signaling and Its Pathophysiological Roles. Cells 2023; 12:cells12030426. [PMID: 36766768 PMCID: PMC9913600 DOI: 10.3390/cells12030426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/20/2023] [Accepted: 01/24/2023] [Indexed: 02/03/2023] Open
Abstract
The serotonin (5-HT)6 receptor still raises particular interest given its unique spatio-temporal pattern of expression among the serotonin receptor subtypes. It is the only serotonin receptor specifically expressed in the central nervous system, where it is detected very early in embryonic life and modulates key neurodevelopmental processes, from neuronal migration to brain circuit refinement. Its predominant localization in the primary cilium of neurons and astrocytes is also unique among the serotonin receptor subtypes. Consistent with the high expression levels of the 5-HT6 receptor in brain regions involved in the control of cognitive processes, it is now well-established that the pharmacological inhibition of the receptor induces pro-cognitive effects in several paradigms of cognitive impairment in rodents, including models of neurodevelopmental psychiatric disorders and neurodegenerative diseases. The 5-HT6 receptor can engage several signaling pathways in addition to the canonical Gs signaling, but there is still uncertainty surrounding the signaling pathways that underly its modulation of cognition, as well as how the receptor's coupling is dependent on its cellular compartmentation. Here, we describe recent findings showing how the proper subcellular localization of the receptor is achieved, how this peculiar localization determines signaling pathways engaged by the receptor, and their pathophysiological influence.
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6
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Linders LE, Supiot LF, Du W, D’Angelo R, Adan RAH, Riga D, Meye FJ. Studying Synaptic Connectivity and Strength with Optogenetics and Patch-Clamp Electrophysiology. Int J Mol Sci 2022; 23:ijms231911612. [PMID: 36232917 PMCID: PMC9570045 DOI: 10.3390/ijms231911612] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 09/20/2022] [Accepted: 09/21/2022] [Indexed: 02/07/2023] Open
Abstract
Over the last two decades the combination of brain slice patch clamp electrophysiology with optogenetic stimulation has proven to be a powerful approach to analyze the architecture of neural circuits and (experience-dependent) synaptic plasticity in such networks. Using this combination of methods, originally termed channelrhodopsin-assisted circuit mapping (CRACM), a multitude of measures of synaptic functioning can be taken. The current review discusses their rationale, current applications in the field, and their associated caveats. Specifically, the review addresses: (1) How to assess the presence of synaptic connections, both in terms of ionotropic versus metabotropic receptor signaling, and in terms of mono- versus polysynaptic connectivity. (2) How to acquire and interpret measures for synaptic strength and function, like AMPAR/NMDAR, AMPAR rectification, paired-pulse ratio (PPR), coefficient of variance and input-specific quantal sizes. We also address how synaptic modulation by G protein-coupled receptors can be studied with pharmacological approaches and advanced technology. (3) Finally, we elaborate on advances on the use of dual color optogenetics in concurrent investigation of multiple synaptic pathways. Overall, with this review we seek to provide practical insights into the methods used to study neural circuits and synapses, by combining optogenetics and patch-clamp electrophysiology.
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7
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Watts SW, Flood ED, Thompson JM. Is the 5-hydroxytryptamine 7 Receptor Constitutively Active in the Vasculature? A Study in Veins/Vein. J Cardiovasc Pharmacol 2022; 80:314-322. [PMID: 35939654 PMCID: PMC9373064 DOI: 10.1097/fjc.0000000000001296] [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: 02/18/2022] [Accepted: 04/17/2022] [Indexed: 11/26/2022]
Abstract
ABSTRACT The 5-hydroxytryptamine 7 (5-HT 7 ) receptor is reported to have considerable constitutive activity when transfected into cells. Constitutive activity-receptor activity in the absence of known agonist-is important for understanding the contributions of a receptor to (patho)physiology. We test the hypothesis that the 5-HT 7 receptor possesses constitutive activity in a physiological situation. Isolated veins from male and female Sprague Dawley rats were used as models for measuring isometric force; the abdominal vena cava possesses a functional 5-HT 7 receptor that mediates relaxation, whereas the small mesenteric vein does not. Compounds reported to act as inverse agonists were investigated for their ability to cause contraction (moving a constitutively active relaxant receptor to an inactive state, removing relaxation). Compared with a vehicle control, clozapine, risperidone, ketanserin, and SB269970 caused no contraction in the isolated male abdominal vena cava. By contrast, methiothepin caused a concentration-dependent contraction of the male but not female abdominal vena cava, although with low potency (-log EC 50 [M] = 5.50 ± 0.45) and efficacy (∼12% of contraction to endothelin-1). Methiothepin-induced contraction was not reduced by the 5-HT 7 receptor antagonist (SB269970, 1 μM, not active in the vena cava). These same compounds showed little to no effect in the isolated mesenteric vein. We conclude that the 5-HT 7 receptor in the isolated veins of the Sprague Dawley rat does not possess constitutive activity. We raise the question of the physiological relevance of constitutive activity of this receptor important to such diverse physiological functions as sleep, circadian rhythm, temperature, and blood pressure regulation.
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Affiliation(s)
- Stephanie W Watts
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI
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8
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Chaudhary A, Mani A. Aβ peptides stabilize GPCRs in inactive form and trigger inverse agonism in Alzheimer's disease. Biochimie 2022; 201:75-78. [PMID: 35839919 DOI: 10.1016/j.biochi.2022.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Revised: 06/28/2022] [Accepted: 07/08/2022] [Indexed: 11/25/2022]
Abstract
Several G-protein coupled receptors (GPCR) are upregulated in Alzheimer's Disease (AD), which ought to facilitate neurotransmission, and improve cognition. Yet, despite this upregulation, associated physiological effects are not observed in AD patients. This paradox solicits urgent attention to find a suitable justification for disturbed neurotransmission in AD. This article focuses on the role of Aβ granules and their possible interaction with GPCRs that modulate neurotransmission and AD progression.
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Affiliation(s)
- Amit Chaudhary
- Department of Biotechnology, Motilal Nehru National Institute of Technology, Allahabad, 211004, India
| | - Ashutosh Mani
- Department of Biotechnology, Motilal Nehru National Institute of Technology, Allahabad, 211004, India.
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9
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Serrano NE, Saputra SG, Íbias J, Company M, Nazarian A. Pain-induced impulsivity is sexually dimorphic and mu-opioid receptor sensitive in rats. Psychopharmacology (Berl) 2021; 238:3447-3462. [PMID: 34427720 DOI: 10.1007/s00213-021-05963-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 08/10/2021] [Indexed: 12/13/2022]
Abstract
RATIONALE AND OBJECTIVES Pain sensation can negatively impact cognitive function, including impulsivity. Pain-induced changes in impulsivity can contribute to development of psychiatric comorbidities found in those with chronic pain conditions. The goal of this study was to determine whether complete Freund's adjuvant (CFA)-induced pain manipulation enhances impulsivity in rats. Whether the pain-induced impulsivity is sexually dimorphic, and if mu-opioid receptors play a role in these processes. METHODS Male and female rats were screened for trait impulsivity and designated as high or low impulsive using a delay discounting task. Rats then received a hind paw injection of CFA, and their impulsivity was assessed for 16 days. The effects of morphine on impulsivity were also examined. In a separate experiment, rats were pretreated with beta-funaltrexamine (β-FNA) to determine the role of mu-opioid receptors on impulsivity. RESULTS CFA treatment increased impulsivity in males and females. The onset of CFA-induced impulsivity was faster in high impulsive females than males. Morphine blocked CFA-induced impulsivity in both sexes in a dose- and time-dependent manner. β-FNA prevented the actions of morphine on CFA-induced impulsivity in high impulsive males, but not high impulsive females. Moreover, β-FNA increased CFA-induced impulsivity in morphine naïve males, but not females. CONCLUSION These findings demonstrate unique sex differences in CFA-induced impulsivity, response to morphine, and the impact of mu-opioid receptors. A better understanding of cognitive deficits and their mechanisms can provide insight into the development of substance abuse and psychiatric comorbidities that occur in people with chronic pain.
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Affiliation(s)
- Nidia Espinoza Serrano
- Department of Pharmaceutical Sciences, Western University of Health Sciences, 309 E. Second Street, Pomona, CA, 91766, USA
| | - Samuel G Saputra
- Department of Pharmaceutical Sciences, Western University of Health Sciences, 309 E. Second Street, Pomona, CA, 91766, USA
| | - Javier Íbias
- Departamento de Metodologίa de Las Ciencias del Comportamiento, Facultad de Psicologίa, Universidad Nacional de Educacίon a Distancia (UNED), 28040, Madrid, Spain
| | - Matthew Company
- Department of Pharmaceutical Sciences, Western University of Health Sciences, 309 E. Second Street, Pomona, CA, 91766, USA
| | - Arbi Nazarian
- Department of Pharmaceutical Sciences, Western University of Health Sciences, 309 E. Second Street, Pomona, CA, 91766, USA.
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10
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Schihada H, Shekhani R, Schulte G. Quantitative assessment of constitutive G protein-coupled receptor activity with BRET-based G protein biosensors. Sci Signal 2021; 14:eabf1653. [PMID: 34516756 DOI: 10.1126/scisignal.abf1653] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
[Figure: see text].
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Affiliation(s)
- Hannes Schihada
- Section for Receptor Biology and Signaling, Department of Physiology and Pharmacology, Karolinska Institutet, Biomedicum, Solnavägen 9, SE-17165 Stockholm, Sweden
| | - Rawan Shekhani
- Section for Receptor Biology and Signaling, Department of Physiology and Pharmacology, Karolinska Institutet, Biomedicum, Solnavägen 9, SE-17165 Stockholm, Sweden
| | - Gunnar Schulte
- Section for Receptor Biology and Signaling, Department of Physiology and Pharmacology, Karolinska Institutet, Biomedicum, Solnavägen 9, SE-17165 Stockholm, Sweden
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11
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Karapinar R, Schwitalla JC, Eickelbeck D, Pakusch J, Mücher B, Grömmke M, Surdin T, Knöpfel T, Mark MD, Siveke I, Herlitze S. Reverse optogenetics of G protein signaling by zebrafish non-visual opsin Opn7b for synchronization of neuronal networks. Nat Commun 2021; 12:4488. [PMID: 34301944 PMCID: PMC8302595 DOI: 10.1038/s41467-021-24718-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 06/24/2021] [Indexed: 01/15/2023] Open
Abstract
Opn7b is a non-visual G protein-coupled receptor expressed in zebrafish. Here we find that Opn7b expressed in HEK cells constitutively activates the Gi/o pathway and illumination with blue/green light inactivates G protein-coupled inwardly rectifying potassium channels. This suggests that light acts as an inverse agonist for Opn7b and can be used as an optogenetic tool to inhibit neuronal networks in the dark and interrupt constitutive inhibition in the light. Consistent with this prediction, illumination of recombinant expressed Opn7b in cortical pyramidal cells results in increased neuronal activity. In awake mice, light stimulation of Opn7b expressed in pyramidal cells of somatosensory cortex reliably induces generalized epileptiform activity within a short (<10 s) delay after onset of stimulation. Our study demonstrates a reversed mechanism for G protein-coupled receptor control and Opn7b as a tool for controlling neural circuit properties.
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Affiliation(s)
- Raziye Karapinar
- Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany
- Laboratory of Optogenetics and Circuit Neuroscience, Imperial College London, London, UK
- The Francis Crick Institute, London, UK
| | | | - Dennis Eickelbeck
- Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany
- Laboratory of Optogenetics and Circuit Neuroscience, Imperial College London, London, UK
- The Francis Crick Institute, London, UK
| | - Johanna Pakusch
- Behavioral Neuroscience, Ruhr-University Bochum, Bochum, Germany
| | - Brix Mücher
- Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany
| | - Michelle Grömmke
- Behavioral Neuroscience, Ruhr-University Bochum, Bochum, Germany
| | - Tatjana Surdin
- Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany
| | - Thomas Knöpfel
- Laboratory of Optogenetics and Circuit Neuroscience, Imperial College London, London, UK
| | - Melanie D Mark
- Behavioral Neuroscience, Ruhr-University Bochum, Bochum, Germany.
| | - Ida Siveke
- Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany
- German Cancer Consortium (DKTK/DKFZ), West German Cancer Center, University Hospital Essen, Essen, Germany
| | - Stefan Herlitze
- Department of Zoology and Neurobiology, Ruhr-University Bochum, Bochum, Germany.
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Olaniru OE, Cheng J, Ast J, Arvaniti A, Atanes P, Huang GC, King AJF, Jones PM, Broichhagen J, Hodson DJ, Persaud SJ. SNAP-tag-enabled super-resolution imaging reveals constitutive and agonist-dependent trafficking of GPR56 in pancreatic β-cells. Mol Metab 2021; 53:101285. [PMID: 34224919 PMCID: PMC8326393 DOI: 10.1016/j.molmet.2021.101285] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 06/19/2021] [Accepted: 06/28/2021] [Indexed: 12/25/2022] Open
Abstract
Objective Members of the adhesion G protein-coupled receptor (aGPCR) subfamily are important actors in metabolic processes, with GPR56 (ADGRG1) emerging as a possible target for type 2 diabetes therapy. GPR56 can be activated by collagen III, its endogenous ligand, and by a synthetic seven amino-acid peptide (TYFAVLM; P7) contained within the GPR56 Stachel sequence. However, the mechanisms regulating GPR56 trafficking dynamics and agonist activities are not yet clear. Methods Here, we introduced SNAPf-tag into the N-terminal segment of GPR56 to monitor GPR56 cellular activity in situ. Confocal and super-resolution microscopy were used to investigate the trafficking pattern of GPR56 in native MIN6 β-cells and in MIN6 β-cells where GPR56 had been deleted by CRISPR-Cas9 gene editing. Insulin secretion, changes in intracellular calcium, and β-cell apoptosis were determined by radioimmunoassay, single-cell calcium microfluorimetry, and measuring caspase 3/7 activities, respectively, in MIN6 β-cells and human islets. Results SNAP-tag labelling indicated that GPR56 predominantly underwent constitutive internalisation in the absence of an exogenous agonist, unlike GLP-1R. Collagen III further stimulated GPR56 internalisation, whereas P7 was without significant effect. The overexpression of GPR56 in MIN6 β-cells did not affect insulin secretion. However, it was associated with reduced β-cell apoptosis, while the deletion of GPR56 made MIN6 β-cells more susceptible to cytokine-induced apoptosis. P7 induced a rapid increase in the intracellular calcium in MIN6 β-cells (in a GPR56-dependent manner) and human islets, and it also caused a sustained and reversible increase in insulin secretion from human islets. Collagen III protected human islets from cytokine-induced apoptosis, while P7 was without significant effect. Conclusions These data indicate that GPR56 exhibits both agonist-dependent and -independent trafficking in β-cells and suggest that while GPR56 undergoes constitutive signalling, it can also respond to its ligands when required. We have also identified that constitutive and agonist-dependent GPR56 activation is coupled to protect β-cells against apoptosis, offering a potential therapeutic target to maintain β-cell mass in type 2 diabetes. GPR56 predominantly underwent constitutive internalisation in β-cells in the absence of exogenous agonist. The GPR56 agonists, collagen III and P7, showed differential effects on GPR56 trafficking and islet functions. Constitutive and agonist-dependent GPR56 activation is coupled to protection of β-cells against apoptosis.
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Affiliation(s)
- Oladapo E Olaniru
- Department of Diabetes, School of Life Course Sciences, King's College London, Guy's Campus, London SE1 1UL, UK.
| | - Jordan Cheng
- Department of Imaging Chemistry and Biology, School of Biomedical Engineering & Imaging Sciences, 4th floor Lambeth Wing, St Thomas' Hospital, London, SE1 7EH, UK
| | - Julia Ast
- Institute of Metabolism and Systems Research (IMSR), Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK; Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Anastasia Arvaniti
- Institute of Metabolism and Systems Research (IMSR), Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK; Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Patricio Atanes
- Department of Diabetes, School of Life Course Sciences, King's College London, Guy's Campus, London SE1 1UL, UK
| | - Guo C Huang
- Department of Diabetes, School of Life Course Sciences, King's College London, Guy's Campus, London SE1 1UL, UK
| | - Aileen J F King
- Department of Diabetes, School of Life Course Sciences, King's College London, Guy's Campus, London SE1 1UL, UK
| | - Peter M Jones
- Department of Diabetes, School of Life Course Sciences, King's College London, Guy's Campus, London SE1 1UL, UK
| | - Johannes Broichhagen
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125, Berlin, Germany
| | - David J Hodson
- Institute of Metabolism and Systems Research (IMSR), Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham, Birmingham, UK; Centre for Endocrinology, Diabetes and Metabolism, Birmingham Health Partners, Birmingham, UK
| | - Shanta J Persaud
- Department of Diabetes, School of Life Course Sciences, King's College London, Guy's Campus, London SE1 1UL, UK.
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McCarthy CI, Chou-Freed C, Rodríguez SS, Yaneff A, Davio C, Raingo J. Constitutive activity of dopamine receptor type 1 (D1R) increases CaV2.2 currents in PFC neurons. J Gen Physiol 2021; 152:151624. [PMID: 32259196 PMCID: PMC7201881 DOI: 10.1085/jgp.201912492] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 02/14/2020] [Accepted: 03/12/2020] [Indexed: 01/19/2023] Open
Abstract
Alterations in dopamine receptor type 1 (D1R) density are associated with cognitive deficits of aging and schizophrenia. In the prefrontal cortex (PFC), D1R plays a critical role in the regulation of working memory, which is impaired in these cognitive deficit states, but the cellular events triggered by changes in D1R expression remain unknown. A previous report demonstrated that interaction between voltage-gated calcium channel type 2.2 (CaV2.2) and D1R stimulates CaV2.2 postsynaptic surface location in medial PFC pyramidal neurons. Here, we show that in addition to the occurrence of the physical receptor-channel interaction, constitutive D1R activity mediates up-regulation of functional CaV2.2 surface density. We performed patch-clamp experiments on transfected HEK293T cells and wild-type C57BL/6 mouse brain slices, as well as imaging experiments and cAMP measurements. We found that D1R coexpression led to ∼60% increase in CaV2.2 currents in HEK293T cells. This effect was occluded by preincubation with a D1/D5R inverse agonist, chlorpromazine, and by replacing D1R with a D1R mutant lacking constitutive activity. Moreover, D1R-induced increase in CaV2.2 currents required basally active Gs protein, as well as D1R-CaV2.2 interaction. In mice, intraperitoneal administration of chlorpromazine reduced native CaV currents’ sensitivity to ω-conotoxin-GVIA and their size by ∼49% in layer V/VI pyramidal neurons from medial PFC, indicating a selective effect on CaV2.2. Additionally, we found that reducing D1/D5R constitutive activity correlates with a decrease in the agonist-induced D1/D5R inhibitory effect on native CaV currents. Our results could be interpreted as a stimulatory effect of D1R constitutive activity on the number of CaV2.2 channels available for dopamine-mediated modulation. Our results contribute to the understanding of the physiological role of D1R constitutive activity and may explain the noncanonical postsynaptic distribution of functional CaV2.2 in PFC neurons.
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Affiliation(s)
- Clara Inés McCarthy
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology, Universidad Nacional de La Plata, Consejo de Investigaciones Científicas y Técnicas, Comisión de Investigaciones de la Provincia de Buenos Aires, Buenos Aires, Argentina
| | - Cambria Chou-Freed
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology, Universidad Nacional de La Plata, Consejo de Investigaciones Científicas y Técnicas, Comisión de Investigaciones de la Provincia de Buenos Aires, Buenos Aires, Argentina
| | - Silvia Susana Rodríguez
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology, Universidad Nacional de La Plata, Consejo de Investigaciones Científicas y Técnicas, Comisión de Investigaciones de la Provincia de Buenos Aires, Buenos Aires, Argentina
| | - Agustín Yaneff
- Instituto de Investigaciones Farmacológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Carlos Davio
- Instituto de Investigaciones Farmacológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Jesica Raingo
- Electrophysiology Laboratory, Multidisciplinary Institute of Cell Biology, Universidad Nacional de La Plata, Consejo de Investigaciones Científicas y Técnicas, Comisión de Investigaciones de la Provincia de Buenos Aires, Buenos Aires, Argentina
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Abstract
To understand human taste requires not only physiological studies ranging from receptor mechanisms to brain circuitry, but also psychophysical studies that quantitatively describe the perceptual output of the system. As obvious as this requirement is, differences in research approaches, methodologies, and objectives complicate the ability to meet it. Discussed here is an example of how the discovery two decades ago of a perceptual taste illusion (thermal taste) has led to physiological and psychophysical research on both peripheral and central mechanisms of taste, including most recently a psychophysical study of the heat sensitivity of the human sweet taste receptor TAS1R2/T1R3, and an fMRI study of a possible central gain mechanism that may underlie, in part, differences in human taste sensitivity. In addition to the new data and hypotheses these studies have generated, they illustrate instances of research on taste motivated by evidence derived from different approaches and levels of analysis.
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Affiliation(s)
- Barry G Green
- The John B. Pierce Laboratory, 290 Congress Avenue, New Haven, CT, USA 06519
- Department of Surgery (Otolaryngology), Yale School of Medicine, 333 Cedar Street, New Haven, CT, USA 06511
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15
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Desai NV, Varela C. Distinct burst properties contribute to the functional diversity of thalamic nuclei. J Comp Neurol 2021; 529:3726-3750. [PMID: 33723858 PMCID: PMC8440663 DOI: 10.1002/cne.25141] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 03/10/2021] [Accepted: 03/12/2021] [Indexed: 12/21/2022]
Abstract
Thalamic neurons fire spikes in two modes, burst and tonic. The function of burst firing is unclear, but the evidence suggests that bursts are more effective at activating cortical cells, and that postinhibition rebound bursting contributes to thalamocortical oscillations during sleep. Bursts are considered stereotyped signals; however, there is limited evidence regarding how burst properties compare across thalamic nuclei of different functional or anatomical organization. Here, we used whole-cell patch clamp recordings and compartmental modeling to investigate the properties of bursts in six sensory thalamic nuclei, to study the mechanisms that can lead to different burst properties, and to assess the implications of different burst properties for thalamocortical transmission and oscillatory functions. We found that bursts in higher-order cells on average had higher number of spikes and longer latency to the first spike. Additionally, burst features in first-order neurons were determined by sensory modality. Shifting the voltage-dependence and density of the T-channel conductance in a compartmental model replicates the burst properties from the intracellular recordings, pointing to molecular mechanisms that can generate burst diversity. Furthermore, the model predicts that bursts with higher number of spikes will drastically reduce the effectiveness of thalamocortical transmission. In addition, the latency to burst limited the rebound oscillatory frequency in modeled cells. These results demonstrate that burst properties vary according to the thalamocortical hierarchy and with sensory modality. The findings imply that, while in burst mode, thalamocortical transmission and firing frequency will be determined by the number of spikes and latency to burst.
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Affiliation(s)
- Nidhi Vasant Desai
- Psychology Department, Jupiter Life Sciences Initiative, Florida Atlantic University, Boca Raton, Florida, USA
| | - Carmen Varela
- Psychology Department, Jupiter Life Sciences Initiative, Florida Atlantic University, Boca Raton, Florida, USA
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16
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Haspula D, Clark MA. Cannabinoid Receptors: An Update on Cell Signaling, Pathophysiological Roles and Therapeutic Opportunities in Neurological, Cardiovascular, and Inflammatory Diseases. Int J Mol Sci 2020; 21:E7693. [PMID: 33080916 PMCID: PMC7590033 DOI: 10.3390/ijms21207693] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 10/14/2020] [Accepted: 10/15/2020] [Indexed: 12/16/2022] Open
Abstract
The identification of the human cannabinoid receptors and their roles in health and disease, has been one of the most significant biochemical and pharmacological advancements to have occurred in the past few decades. In spite of the major strides made in furthering endocannabinoid research, therapeutic exploitation of the endocannabinoid system has often been a challenging task. An impaired endocannabinoid tone often manifests as changes in expression and/or functions of type 1 and/or type 2 cannabinoid receptors. It becomes important to understand how alterations in cannabinoid receptor cellular signaling can lead to disruptions in major physiological and biological functions, as they are often associated with the pathogenesis of several neurological, cardiovascular, metabolic, and inflammatory diseases. This review focusses mostly on the pathophysiological roles of type 1 and type 2 cannabinoid receptors, and it attempts to integrate both cellular and physiological functions of the cannabinoid receptors. Apart from an updated review of pre-clinical and clinical studies, the adequacy/inadequacy of cannabinoid-based therapeutics in various pathological conditions is also highlighted. Finally, alternative strategies to modulate endocannabinoid tone, and future directions are also emphasized.
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Affiliation(s)
- Dhanush Haspula
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD 20892, USA;
| | - Michelle A. Clark
- Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, FL 33314, USA
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17
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Sciacca FL, Ciaccio C, Fontana F, Strano C, Gilardoni F, Pantaleoni C, D'Arrigo S. Severe Phenotype in a Patient With Homozygous 15q21.2 Microdeletion Involving BCL2L10, GNB5, and MYO5C Genes, Resembling Infantile Developmental Disorder With Cardiac Arrhythmias (IDDCA). Front Genet 2020; 11:399. [PMID: 32477400 PMCID: PMC7237723 DOI: 10.3389/fgene.2020.00399] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 03/30/2020] [Indexed: 11/29/2022] Open
Abstract
Homozygous and compound heterozygous mutations in GNB5 gene have been associated with a wide spectrum of clinical presentations, ranging from neurodevelopmental issues with or without cardiac arrhythmia (LADCI) to severe developmental delay with epileptic encephalopathy, retinal dystrophy, and heart rhythm abnormalities (IDDCA). While missense or missense/non-sense mutations usually lead to milder form, the biallelic loss of function of GNB5 gene causes the severe multisystemic IDDCA phenotype. So far, only 27 patients have been described with GNB5-associated disease. We report the first case of a patient carrying a homozygous 15q21.2 microdeletion, encompassing GNB5 and the two contiguous genes BCL2L10 and MYO5C. The clinical features of the child are consistent with the severe IDDCA phenotype, thus confirming the GNB5 loss-of-function mechanism in determining such presentation of the disease.
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Affiliation(s)
- Francesca L Sciacca
- Neurological Biochemistry and Neuropharmacology Unit, Laboratory of Cytogenetic, Department of Diagnostic and Technology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Claudia Ciaccio
- Developmental Neurology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Federica Fontana
- Neurological Biochemistry and Neuropharmacology Unit, Laboratory of Cytogenetic, Department of Diagnostic and Technology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Camilla Strano
- Developmental Neurology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Francesca Gilardoni
- Neurological Biochemistry and Neuropharmacology Unit, Laboratory of Cytogenetic, Department of Diagnostic and Technology, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Chiara Pantaleoni
- Developmental Neurology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
| | - Stefano D'Arrigo
- Developmental Neurology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan, Italy
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Nachtigal D, Green BG. Sweet Thermal Taste: Perceptual Characteristics in Water and Dependence on TAS1R2/TAS1R3. Chem Senses 2020; 45:219-230. [PMID: 32072157 PMCID: PMC7320217 DOI: 10.1093/chemse/bjaa009] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
The initial objective of this study was to determine if activation of the sweet taste receptor TAS1R2/TAS1R3 is necessary for perception of sweet thermal taste (swTT). Our approach was to inhibit the receptor with the inverse agonist lactisole using a temperature-controlled flow gustometer. Because all prior studies of thermal taste (TT) used metal thermodes to heat the tongue tip, we first investigated whether it could be generated in heated water. Experiment 1 showed that sweetness could be evoked when deionized water was heated from 20 to 35 °C, and testing with static temperatures between 20 and 35 °C demonstrated the importance of heating from a cool temperature. As in previous studies, thermal sweetness was reported by only a subset of participants, and replicate measurements found variability in reports of sweetness across trials and between sessions. Experiment 2 then showed that exposure to 8 mM lactisole blocked perception of swTT. Confirmation of the involvement of TAS1R2/TAS1R3 led to an investigation of possible sensory and cognitive interactions between thermal and chemical sweetness. Using sucrose as a sweet stimulus and quinine as a nonsweet control, we found that dynamic heating capable of producing thermal sweetness did not increase the sweetness of sucrose compared with static heating at 35 °C. However, swTT was disrupted if trials containing sucrose (but not quinine) were interspersed among heating-only trials. These findings provide new information relevant to understanding the perceptual processes and receptor mechanisms of swTT, as well as the heat sensitivity of sweet taste in general.
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Affiliation(s)
| | - Barry G Green
- The John B. Pierce Laboratory, New Haven, CT, USA
- Yale School of Medicine, Department of Surgery (Otolaryngology), New Haven, CT, USA
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19
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Wang Q, Dong X, Lu J, Hu T, Pei G. Constitutive activity of a G protein-coupled receptor, DRD1, contributes to human cerebral organoid formation. Stem Cells 2020; 38:653-665. [PMID: 32052915 PMCID: PMC7384186 DOI: 10.1002/stem.3156] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Revised: 01/12/2020] [Accepted: 01/22/2020] [Indexed: 12/22/2022]
Abstract
The intricate balance of neural stem cell (NSC) amplification and neurogenesis is central to nervous system development. Dopamine D1 receptor (DRD1) is a typical G protein‐coupled receptor (GPCR) mainly expressed in neurogenic area, with high constitutive activity. The receptor appears in the embryonic period before the formation of mature synaptic contacts, which indicates that dopamine receptor and its constitutive activity play crucial roles in the embryonic brain development. Here, we found that DRD1 was enriched in human NSCs. Inhibition of the receptor activity by its inverse agonists promoted human NSCs proliferation and impeded its differentiation. These results were also mimicked by genetic knockdown of DRD1, which also blocked the effects of inverse agonists, suggesting a receptor‐dependent manner. More interestingly, knock‐in A229T mutant with reduced DRD1 constitutive activity by CRISPR‐Cas9 genome editing technology resulted into increased endogenous human NSCs proliferation. These results were well reproduced in human cerebral organoids, and inhibition of the DRD1 constitutive activity by its inverse agonists induced the expansion and folding of human cerebral organoids. The anatomic analysis uncovered that decreasing the constitutive activity of DRD1 by its inverse agonists promoted the NSCs proliferation and maintenance that led to hindered cortical neurogenesis. Further mechanistic studies revealed that the PKC‐CBP pathway was involved in the regulation by DRD1. Thus, our findings indicate that the constitutive activity of DRD1 and possibly other GPCRs plays an important role in the development of human nervous system.
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Affiliation(s)
- Qinying Wang
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell ScienceInstitute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of SciencesShanghaiChina
| | - Xiaoxu Dong
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell ScienceInstitute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of SciencesShanghaiChina
- School of Life Science and Technology, Shanghai Tech UniversityShanghaiChina
| | - Jing Lu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell ScienceInstitute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of SciencesShanghaiChina
| | - Tingting Hu
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell ScienceInstitute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of SciencesShanghaiChina
| | - Gang Pei
- State Key Laboratory of Cell Biology, CAS Center for Excellence in Molecular Cell ScienceInstitute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of SciencesShanghaiChina
- Shanghai Key Laboratory of Signaling and Disease ResearchCollaborative Innovation Center for Brain Science, School of Life Sciences and Technology, Tongji UniversityShanghaiChina
- Institute for Stem Cell and Regeneration, Chinese Academy of SciencesBeijingChina
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20
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Cordisco Gonzalez S, Mustafá ER, Rodriguez SS, Perello M, Raingo J. Dopamine Receptor Type 2 and Ghrelin Receptor Coexpression Alters Ca V2.2 Modulation by G Protein Signaling Cascades. ACS Chem Neurosci 2020; 11:3-13. [PMID: 31808667 DOI: 10.1021/acschemneuro.9b00426] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Voltage-gated calcium channels type 2.2 (CaV2.2) are activated by action potentials at presynaptic terminals, and their calcium current induces neurotransmitter release. In this context, regulating CaV2.2 is critical, and one of the most important mechanisms for doing so is through its G protein-coupled receptor (GPCR) activity. Two such GPCRs are the ghrelin (GHSR) and the dopamine type 2 (D2R) receptors. We previously demonstrated that constitutive GHSR activity reduces CaV2.2 forward trafficking and that ghrelin-induced GHSR activity inhibits CaV2.2 currents. On the other hand, dopamine-induced D2R activity also inhibits CaV2.2 currents. It has been recently shown that D2R and GHSR form heteromers in hypothalamic neurons. This interaction profoundly changes the signaling cascades activated by dopamine and is necessary for dopamine-dependent anorexia. Here we explored how D2R-GHSR coexpression in HEK293T cells modulates the effect that each GPCR has on CaV2.2. We found that D2R-GHSR coexpression reduces the inhibition of CaV2.2 currents by agonist-induced D2R activation and added a new source of basal CaV2.2 current inhibition to the one produced by GHSR solely expression. We investigated the signaling cascades implicated and found that constitutive GHSR activity, Gq protein, and Gβγ subunit play a critical role in these altered effects. Moreover, we found that the effect of D2R agonist on native calcium currents in hypothalamic neurons is reduced when both D2R and GHSR are overexpressed. In summary, our results allow us to propose a novel mechanism for controlling CaV2.2 currents involving the coexpression of two physiologically relevant GPCRs.
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Estaras M, Ameur FZ, Roncero V, Fernandez-Bermejo M, Blanco G, Lopez D, Mateos JM, Salido GM, Gonzalez A. The melatonin receptor antagonist luzindole induces Ca 2+ mobilization, reactive oxygen species generation and impairs trypsin secretion in mouse pancreatic acinar cells. Biochim Biophys Acta Gen Subj 2019; 1863:129407. [PMID: 31381958 DOI: 10.1016/j.bbagen.2019.07.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 07/23/2019] [Accepted: 07/31/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND In this work we studied the effects of the melatonin receptor-antagonist luzindole (1 μM-50 μM) on isolated mouse pancreatic acinar cells. METHODS Changes in intracellular free-Ca2+ concentration, reactive oxygen species production and trypsin secretion were analyzed. RESULTS Luzindole induced increases in [Ca2+]i that diminished CCK-8 induced Ca2+ mobilization, compared with that observed when CCK-8 was applied alone. Treatment of cells with thapsigargin (1 μM), in the absence of Ca2+ in the extracellular medium, evoked a transient increase in [Ca2+]i. The additional incubation of cells with luzindole (10 μM) failed to induce further mobilization of Ca2+. In the presence of luzindole a concentration-dependent increase in ROS generation was observed that decreased in the absence of Ca2+ or by pretreatment of cells with melatonin (100 μM). Incubation of pancreatic acinar cells with luzindole (10 μM) impaired CCK-8-induced trypsin secretion. Melatonin was unable to revert the effect of luzindole on CCK-8-induced trypsin secretion. CONCLUSION The melatonin receptor-inhibitor luzindole induces Ca2+-mediated pro-oxidative conditions and impairment of enzyme secretion, which creates a situation in pancreatic acinar cells that might compromise their function. GENERAL SIGNIFICANCE The effects of luzindole that we have observed, might be unspecific and could mislead the observations when it is used to study the actions of melatonin on the gland. Another possibility is that melatonin receptors exhibit a basal or agonist-independent activity in pancreatic acinar cells, which might be modulated by melatonin or luzindole.
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Affiliation(s)
- Matias Estaras
- Institute of Molecular Pathology Biomarkers, University of Extremadura, Caceres, Spain
| | - Fatma Z Ameur
- Laboratoire de Physiologie de la Nutrition et de Sécurité Alimentaire, Université d'Oran1, Ahmed BenBella, Algeria
| | - Vicente Roncero
- Unit of Histology and Pathological Anatomy, Veterinary Faculty, University of Extremadura, Caceres, Spain
| | | | - Gerardo Blanco
- Hepatobiliary-Pancreatic Surgery and Liver Transplant Unit, Infanta Cristina Hospital, Badajoz, Spain
| | - Diego Lopez
- Hepatobiliary-Pancreatic Surgery and Liver Transplant Unit, Infanta Cristina Hospital, Badajoz, Spain
| | - Jose M Mateos
- Department of Gastroenterology, San Pedro de Alcantara Hospital, Caceres, Spain
| | - Gines M Salido
- Institute of Molecular Pathology Biomarkers, University of Extremadura, Caceres, Spain
| | - Antonio Gonzalez
- Institute of Molecular Pathology Biomarkers, University of Extremadura, Caceres, Spain.
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Golovko AI, Ivanov MB, Golovko ES, Dolgo-Saburov VB, Zatsepin EP. The Neurochemical Mechanisms of the Pharmacological Activities of Inverse Agonists of the Benzodiazepine Binding Site. NEUROCHEM J+ 2018. [DOI: 10.1134/s1819712418030042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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23
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Chemogenetic Manipulations of Ventral Tegmental Area Dopamine Neurons Reveal Multifaceted Roles in Cocaine Abuse. J Neurosci 2018; 39:503-518. [PMID: 30446532 DOI: 10.1523/jneurosci.0537-18.2018] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Revised: 10/04/2018] [Accepted: 10/19/2018] [Indexed: 01/13/2023] Open
Abstract
Ventral tegmental area (VTA) dopamine (DA) neurons perform diverse functions in motivation and cognition, but their precise roles in addiction-related behaviors are still debated. Here, we targeted VTA DA neurons for bidirectional chemogenetic modulation during specific tests of cocaine reinforcement, demand, and relapse-related behaviors in male rats, querying the roles of DA neuron inhibitory and excitatory G-protein signaling in these processes. Designer receptor stimulation of Gq signaling, but not Gs signaling, in DA neurons enhanced cocaine seeking via functionally distinct projections to forebrain limbic regions. In contrast, engaging inhibitory Gi/o signaling in DA neurons blunted the reinforcing and priming effects of cocaine, reduced stress-potentiated reinstatement, and altered behavioral strategies for cocaine seeking and taking. Results demonstrate that DA neurons play several distinct roles in cocaine seeking, depending on behavioral context, G-protein-signaling cascades, and DA neuron efferent targets, highlighting their multifaceted roles in addiction.SIGNIFICANCE STATEMENT G-protein-coupled receptors are crucial modulators of ventral tegmental area (VTA) dopamine neuron activity, but how this metabotropic signaling impacts the complex roles of dopamine in reward and addiction is poorly understood. Here, we bidirectionally modulate dopamine neuron G-protein signaling with DREADDs (designer receptors exclusively activated by designer drugs) during a variety of cocaine-seeking behaviors, revealing nuanced, pathway-specific roles in cocaine reward, effortful seeking, and relapse-like behaviors. Gq and Gs stimulation activated dopamine neurons, but only Gq stimulation robustly enhanced cocaine seeking. Gi/o inhibitory signaling reduced some, but not all, types of cocaine seeking. Results show that VTA dopamine neurons modulate numerous distinct aspects of cocaine addiction- and relapse-related behaviors, and point to potential new approaches for intervening in these processes to treat addiction.
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Karamitri A, Plouffe B, Bonnefond A, Chen M, Gallion J, Guillaume JL, Hegron A, Boissel M, Canouil M, Langenberg C, Wareham NJ, Le Gouill C, Lukasheva V, Lichtarge O, Froguel P, Bouvier M, Jockers R. Type 2 diabetes-associated variants of the MT 2 melatonin receptor affect distinct modes of signaling. Sci Signal 2018; 11:11/545/eaan6622. [PMID: 30154102 DOI: 10.1126/scisignal.aan6622] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Melatonin is produced during the night and regulates sleep and circadian rhythms. Loss-of-function variants in MTNR1B, which encodes the melatonin receptor MT2, a G protein-coupled receptor (GPCR), are associated with an increased risk of type 2 diabetes (T2D). To identify specific T2D-associated signaling pathway(s), we profiled the signaling output of 40 MT2 variants by monitoring spontaneous (ligand-independent) and melatonin-induced activation of multiple signaling effectors. Genetic association analysis showed that defects in the melatonin-induced activation of Gαi1 and Gαz proteins and in spontaneous β-arrestin2 recruitment to MT2 were the most statistically significantly associated with an increased T2D risk. Computational variant impact prediction by in silico evolutionary lineage analysis strongly correlated with the measured phenotypic effect of each variant, providing a predictive tool for future studies on GPCR variants. Together, this large-scale functional study provides an operational framework for the postgenomic analysis of the multiple GPCR variants present in the human population. The association of T2D risk with signaling pathway-specific defects opens avenues for pathway-specific personalized therapeutic intervention and reveals the potential relevance of MT2 function during the day, when melatonin is undetectable, but spontaneous activity of the receptor occurs.
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Affiliation(s)
- Angeliki Karamitri
- Inserm, U1016, Institut Cochin, Paris, France.,CNRS UMR 8104, Paris, France.,Université Paris Descartes, Paris, France
| | - Bianca Plouffe
- Institute for Research in Immunology and Cancer and Department of Biochemistry and Molecular Medicine, Université de Montréal, Montreal, Québec H3C 3J7, Canada
| | - Amélie Bonnefond
- Université Lille, CNRS UMR 8199-EGID, Institut Pasteur de Lille, Lille, France
| | - Min Chen
- Inserm, U1016, Institut Cochin, Paris, France.,CNRS UMR 8104, Paris, France.,Université Paris Descartes, Paris, France
| | - Jonathan Gallion
- Structural Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jean-Luc Guillaume
- Inserm, U1016, Institut Cochin, Paris, France.,CNRS UMR 8104, Paris, France.,Université Paris Descartes, Paris, France
| | - Alan Hegron
- Inserm, U1016, Institut Cochin, Paris, France.,CNRS UMR 8104, Paris, France.,Université Paris Descartes, Paris, France
| | - Mathilde Boissel
- Université Lille, CNRS UMR 8199-EGID, Institut Pasteur de Lille, Lille, France
| | - Mickaël Canouil
- Université Lille, CNRS UMR 8199-EGID, Institut Pasteur de Lille, Lille, France
| | - Claudia Langenberg
- Medical Research Council (MRC) Epidemiology Unit, University of Cambridge School of Clinical Medicine, Cambridge CB2 0QQ, UK
| | - Nicholas J Wareham
- Medical Research Council (MRC) Epidemiology Unit, University of Cambridge School of Clinical Medicine, Cambridge CB2 0QQ, UK
| | - Christian Le Gouill
- Institute for Research in Immunology and Cancer and Department of Biochemistry and Molecular Medicine, Université de Montréal, Montreal, Québec H3C 3J7, Canada
| | - Viktoria Lukasheva
- Institute for Research in Immunology and Cancer and Department of Biochemistry and Molecular Medicine, Université de Montréal, Montreal, Québec H3C 3J7, Canada
| | - Olivier Lichtarge
- Structural Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Philippe Froguel
- Université Lille, CNRS UMR 8199-EGID, Institut Pasteur de Lille, Lille, France. .,Department of Genomics of Common Disease, School of Public Health, Imperial College London, Hammersmith Hospital, W12 0NN London, UK
| | - Michel Bouvier
- Institute for Research in Immunology and Cancer and Department of Biochemistry and Molecular Medicine, Université de Montréal, Montreal, Québec H3C 3J7, Canada.
| | - Ralf Jockers
- Inserm, U1016, Institut Cochin, Paris, France. .,CNRS UMR 8104, Paris, France.,Université Paris Descartes, Paris, France
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25
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Prado C, Gaiazzi M, González H, Ugalde V, Figueroa A, Osorio-Barrios FJ, López E, Lladser A, Rasini E, Marino F, Zaffaroni M, Cosentino M, Pacheco R. Dopaminergic Stimulation of Myeloid Antigen-Presenting Cells Attenuates Signal Transducer and Activator of Transcription 3-Activation Favouring the Development of Experimental Autoimmune Encephalomyelitis. Front Immunol 2018; 9:571. [PMID: 29619030 PMCID: PMC5871671 DOI: 10.3389/fimmu.2018.00571] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 03/06/2018] [Indexed: 12/19/2022] Open
Abstract
The dual potential to promote tolerance or inflammation to self-antigens makes dendritic cells (DCs) fundamental players in autoimmunity. Previous results have shown that stimulation of dopamine receptor D5 (DRD5) in DCs potentiates their inflammatory behaviour, favouring the development of experimental autoimmune encephalomyelitis (EAE). Here, we aimed to decipher the underlying mechanism and to test its relevance in multiple sclerosis (MS) patients. Our data shows that DRD5-deficiency confined to DCs in EAE mice resulted in reduced frequencies of CD4+ T-cell subsets with inflammatory potential in the central nervous system, including not only Th1 and Th17 cells but also granulocyte-macrophage colony-stimulating factor producers. Importantly, ex vivo depletion of dopamine from DCs resulted in a dramatic reduction of EAE severity, highlighting the relevance of an autocrine loop promoting inflammation in vivo. Mechanistic analyses indicated that DRD5-signalling in both mouse DCs and human monocytes involves the attenuation of signal transducer and activator of transcription 3-activation, a transcription factor that limits the production of the inflammatory cytokines interleukin (IL)-12 and IL-23. Furthermore, we found an exacerbated expression of all dopamine receptors in peripheral blood pro-inflammatory monocytes obtained from MS patients. These findings illustrate a novel mechanism by which myeloid antigen-presenting cells may trigger the onset of their inflammatory behaviour promoting the development of autoimmunity.
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Affiliation(s)
- Carolina Prado
- Laboratorio de Neuroinmunología, Fundación Ciencia and Vida, Santiago, Chile
| | - Michela Gaiazzi
- Center for Research in Medical Pharmacology, University of Insubria, Varese, Italy
| | - Hugo González
- Laboratorio de Neuroinmunología, Fundación Ciencia and Vida, Santiago, Chile
| | - Valentina Ugalde
- Laboratorio de Neuroinmunología, Fundación Ciencia and Vida, Santiago, Chile
| | - Alicia Figueroa
- Laboratorio de Neuroinmunología, Fundación Ciencia and Vida, Santiago, Chile
| | | | - Ernesto López
- Laboratorio de Inmunoterapia Génica, Fundación Ciencia and Vida, Santiago, Chile
| | - Alvaro Lladser
- Laboratorio de Inmunoterapia Génica, Fundación Ciencia and Vida, Santiago, Chile
| | - Emanuela Rasini
- Center for Research in Medical Pharmacology, University of Insubria, Varese, Italy
| | - Franca Marino
- Center for Research in Medical Pharmacology, University of Insubria, Varese, Italy
| | - Mauro Zaffaroni
- Multiple Sclerosis Centre, ASST della Valle Olona, Hospital of Gallarate, Gallarate, Italy
| | - Marco Cosentino
- Center for Research in Medical Pharmacology, University of Insubria, Varese, Italy
| | - Rodrigo Pacheco
- Laboratorio de Neuroinmunología, Fundación Ciencia and Vida, Santiago, Chile.,Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andres Bello, Santiago, Chile
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26
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Panlilio LV, Justinova Z. Preclinical Studies of Cannabinoid Reward, Treatments for Cannabis Use Disorder, and Addiction-Related Effects of Cannabinoid Exposure. Neuropsychopharmacology 2018; 43:116-141. [PMID: 28845848 PMCID: PMC5719102 DOI: 10.1038/npp.2017.193] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 08/17/2017] [Accepted: 08/22/2017] [Indexed: 12/21/2022]
Abstract
Cannabis use has become increasingly accepted socially and legally, for both recreational and medicinal purposes. Without reliable information about the effects of cannabis, people cannot make informed decisions regarding its use. Like alcohol and tobacco, cannabis can have serious adverse effects on health, and some people have difficulty discontinuing their use of the drug. Many cannabis users progress to using and becoming addicted to other drugs, but the reasons for this progression are unclear. The natural cannabinoid system of the brain is complex and involved in many functions, including brain development, reward, emotion, and cognition. Animal research provides an objective and controlled means of obtaining information about: (1) how cannabis affects the brain and behavior, (2) whether medications can be developed to treat cannabis use disorder, and (3) whether cannabis might produce lasting changes in the brain that increase the likelihood of becoming addicted to other drugs. This review explains the tactics used to address these issues, evaluates the progress that has been made, and offers some directions for future research.
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Affiliation(s)
- Leigh V Panlilio
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, NIH, DHHS, Baltimore, MD, USA
| | - Zuzana Justinova
- Preclinical Pharmacology Section, Behavioral Neuroscience Research Branch, Intramural Research Program, National Institute on Drug Abuse, NIH, DHHS, Baltimore, MD, USA
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27
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Sustained Activity of Metabotropic Glutamate Receptor: Homer, Arrestin, and Beyond. Neural Plast 2017; 2017:5125624. [PMID: 29359050 PMCID: PMC5735635 DOI: 10.1155/2017/5125624] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 10/10/2017] [Accepted: 10/31/2017] [Indexed: 01/08/2023] Open
Abstract
When activated, metabotropic glutamate receptors (mGlus) exert long-lasting changes within the glutamatergic synapses. One mechanism is a tonic effect of downstream signal transduction pathways via sustained activation of mGlu itself. Like many other G protein-coupled receptors (GPCRs), mGlu can exist in a constitutively active state, which persists agonist independently. In this paper, we review the current knowledge of the mechanisms underlying the constitutive activity of group I mGlus. The issues concerning Homer1a mechanism in the constitutive activity of group I mGlus and recent findings regarding the significant role of β-arrestin in sustained GPCR activity are also discussed. We propose that once in a state of sustained activation, the mGlu persistently activates downstream signaling pathways, including various adaptor proteins and kinases, such as β-arrestin and mitogen-activated protein kinases. In turn, these effector molecules bind to or phosphorylate the mGlu C-terminal binding domains and consequently regulate the activation state of the mGlu.
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28
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Mach RH. Small Molecule Receptor Ligands for PET Studies of the Central Nervous System-Focus on G Protein Coupled Receptors. Semin Nucl Med 2017; 47:524-535. [PMID: 28826524 DOI: 10.1053/j.semnuclmed.2017.05.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
G protein-coupled receptors (GPRCs) are a class of proteins that are expressed in high abundance and are responsible for numerous signal transduction pathways in the central nervous system. Consequently, alterations in GPRC function have been associated with a wide variety of neurologic and neuropsychiatric disorders. The development of PET probes for imaging GPRCs has served as a major emphasis of PET radiotracer development and PET imaging studies over the past 30 years. In this review, a basic description of the biology of G proteins and GPRCs is provided. This includes recent evidence of the existence of dimeric and multimeric species of GPRCs that have been termed "receptor mosaics," with an emphasis on the different GPRCs that form complexes with the dopamine D2 receptor. An overview of the different PET radiotracers for imaging the component GPRC within these different multimeric complexes of the D2 receptor is also provided.
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Affiliation(s)
- Robert H Mach
- Department of Radiology, Perelman School Medicine, University of Pennsylvania, Philadelphia, PA.
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29
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Polter AM, Barcomb K, Chen RW, Dingess PM, Graziane NM, Brown TE, Kauer JA. Constitutive activation of kappa opioid receptors at ventral tegmental area inhibitory synapses following acute stress. eLife 2017; 6. [PMID: 28402252 PMCID: PMC5389861 DOI: 10.7554/elife.23785] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 03/13/2017] [Indexed: 12/14/2022] Open
Abstract
Stressful experiences potently activate kappa opioid receptors (κORs). κORs in the ventral tegmental area regulate multiple aspects of dopaminergic and non-dopaminergic cell function. Here we show that at GABAergic synapses on rat VTA dopamine neurons, a single exposure to a brief cold-water swim stress induces prolonged activation of κORs. This is mediated by activation of the receptor during the stressor followed by a persistent, ligand-independent constitutive activation of the κOR itself. This lasting change in function is not seen at κORs at neighboring excitatory synapses, suggesting distinct time courses and mechanisms of regulation of different subsets of κORs. We also provide evidence that constitutive activity of κORs governs the prolonged reinstatement to cocaine-seeking observed after cold water swim stress. Together, our studies indicate that stress-induced constitutive activation is a novel mechanism of κOR regulation that plays a critical role in reinstatement of drug seeking. DOI:http://dx.doi.org/10.7554/eLife.23785.001 People who are recovering from drug addiction are more vulnerable to cravings and relapse when under stress. This ability of stress to boost drug relapse can also be shown in animals previously exposed to addictive drugs. Rats can learn to press a lever to administer themselves a dose of cocaine and, during withdrawal, rats previously exposed to the drug will press the lever more often if they are stressed. Indeed, just a few minutes of stress is enough to increase lever pressing for several days. Stress and addictive drugs both act on a region of the brain called the ventral tegmental area, or VTA, which is part of the brain’s reward system. Stress indirectly increases the activity of the VTA. It does so by activating a protein on the surface of VTA neurons called the kappa opioid receptor (κOR for short). Previous studies revealed that five minutes of stress increases the activity of κORs in the VTA of rats for five days. Conversely, blocking κORs stopped stressed rats from pressing the lever more often for cocaine. Together, these findings suggested that activating κORs in the VTA contributes to stress-induced drug relapse. Polter et al. have now discovered how stress activates κORs. It turns out that stressful or unpleasant experiences cause the brain to produce a protein called dynorphin, which binds to and activates the κORs. After a stressful event, the receptors are said to have become constitutively active, and blocking this constitutive activity prevents stress from inducing drug-seeking behavior. Polter et al. show that binding of dynorphin is needed to change the shape of the receptors so that they remain active even after dynorphin has detached, but it is likely that other molecules are also involved. This is the first study to show a link between stress, constitutive activation of κORs, and drug relapse. The next step is to work out why this process occurs on only some and not all occasions when the brain releases dynorphin, and why only certain κORs in the VTA respond in this way. Whether constitutive kOR activity drives stress-related craving in people with a history of drug abuse and how to halt these cravings also remain to be determined. DOI:http://dx.doi.org/10.7554/eLife.23785.002
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Affiliation(s)
- Abigail M Polter
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, United States
| | - Kelsey Barcomb
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, United States
| | - Rudy W Chen
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, United States
| | - Paige M Dingess
- Neuroscience Program, University of Wyoming, Laramie, United States.,University of Wyoming, School of Pharmacy, Laramie, United States
| | - Nicholas M Graziane
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, United States
| | - Travis E Brown
- Neuroscience Program, University of Wyoming, Laramie, United States.,University of Wyoming, School of Pharmacy, Laramie, United States
| | - Julie A Kauer
- Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, United States
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30
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Mallipeddi S, Janero DR, Zvonok N, Makriyannis A. Functional selectivity at G-protein coupled receptors: Advancing cannabinoid receptors as drug targets. Biochem Pharmacol 2017; 128:1-11. [PMID: 27890725 PMCID: PMC5470118 DOI: 10.1016/j.bcp.2016.11.014] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 11/14/2016] [Indexed: 12/11/2022]
Abstract
The phenomenon of functional selectivity, whereby a ligand preferentially directs the information output of a G-protein coupled receptor (GPCR) along (a) particular effector pathway(s) and away from others, has redefined traditional GPCR signaling paradigms to provide a new approach to structure-based drug design. The two principal cannabinoid receptors (CBRs) 1 and 2 belong to the class-A GPCR subfamily and are considered tenable therapeutic targets for several indications. Yet conventional orthosteric ligands (agonists, antagonists/inverse agonists) for these receptors have had very limited clinical utility due to their propensity to incite on-target adverse events. Chemically distinct classes of cannabinergic ligands exhibit signaling bias at CBRs towards individual subsets of signal transduction pathways. In this review, we discuss the known signaling pathways regulated by CBRs and examine the current evidence for functional selectivity at CBRs in response to endogenous and exogenous cannabinergic ligands as biased agonists. We further discuss the receptor and ligand structural features allowing for selective activation of CBR-dependent functional responses. The design and development of biased ligands may offer a pathway to therapeutic success for novel CBR-targeted drugs.
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Affiliation(s)
- Srikrishnan Mallipeddi
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, United States; Center for Drug Discovery, Northeastern University, Boston, MA 02115, United States
| | - David R Janero
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, United States; Center for Drug Discovery, Northeastern University, Boston, MA 02115, United States
| | - Nikolai Zvonok
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, United States; Center for Drug Discovery, Northeastern University, Boston, MA 02115, United States
| | - Alexandros Makriyannis
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA 02115, United States; Center for Drug Discovery, Northeastern University, Boston, MA 02115, United States; Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, United States.
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31
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Salort G, Álvaro-Bartolomé M, García-Sevilla JA. Regulation of cannabinoid CB 2 receptor constitutive activity in vivo: repeated treatments with inverse agonists reverse the acute activation of JNK and associated apoptotic signaling in mouse brain. Psychopharmacology (Berl) 2017; 234:925-941. [PMID: 28127623 DOI: 10.1007/s00213-017-4537-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 01/07/2017] [Indexed: 01/29/2023]
Abstract
RATIONALE CB2 receptors express constitutive activity and inverse agonists regulate receptor basal activity, which might be involved in death mechanisms. This study assessed the effects of a selective CB2 agonist (JWH133) and different CB2 inverse agonists (AM630, JTE907, raloxifene) on death pathways in brain. OBJECTIVES The acute (JWH13) and the acute/chronic effects (AM630, JTE907, raloxifene) of CB2 ligands regulating pro-apoptotic c-Jun NH2-terminal kinase (p-JNK/JNK ratio) and associated signaling of extrinsic (Fas receptor, Fas-Associated death domain protein, FADD) and intrinsic (Bax, cytochrome c) death pathways (nuclear poly (ADP-ribose) polymerase PARP) were investigated in mouse brain. METHODS Mice were treated with CB2 drugs and target protein contents were assessed by western blot analysis. RESULTS JWH133 reduced cortical JNK (-27-45%) whereas AM630 acutely increased JNK in cortex (+61-148%), cerebellum (+34-40%), and striatum (+33-42%). JTE907 and raloxifene also increased cortical JNK (+31%-57%). Acute AM630, but not JWH133, increased cortical FADD, Bax, cytochrome c, and PARP cleavage. Repeated treatments with the three CB2 inverse agonists were associated with a reversal of the acute effects resulting in decreases in cortical JNK (AM630: -36%; JTE907: -25%; raloxifene: -11%). Chronic treatments also induced a reversal with down-regulation (AM630) or only tolerance (JTE907 and raloxifene) on other apoptotic markers (FADD, Bax, cytochrome c, PARP). CONCLUSIONS AM630 and JTE907 are CB2 protean ligands. Thus, chronic inverse agonists abolished CB2 constitutive activity and then the ligands behaved as agonists reducing (like JWH133) JNK activity. Acute and chronic treatments with CB2 inverse agonists regulate in opposite directions brain death markers.
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Affiliation(s)
- Glòria Salort
- Laboratori de Neurofarmacologia, Institut Universitari d'Investigació en Ciències de la Salut (IUNICS/IdisPa), Universitat de les Illes Balears, Cra. Valldemossa km 7.5, E-07122, Palma de Mallorca, Spain.,Redes Temáticas de Investigación Cooperativa en Salud-Red de Trastornos Adictivos (RETICS-RTA), ISCIII, Madrid, Spain
| | - María Álvaro-Bartolomé
- Laboratori de Neurofarmacologia, Institut Universitari d'Investigació en Ciències de la Salut (IUNICS/IdisPa), Universitat de les Illes Balears, Cra. Valldemossa km 7.5, E-07122, Palma de Mallorca, Spain.,Redes Temáticas de Investigación Cooperativa en Salud-Red de Trastornos Adictivos (RETICS-RTA), ISCIII, Madrid, Spain
| | - Jesús A García-Sevilla
- Laboratori de Neurofarmacologia, Institut Universitari d'Investigació en Ciències de la Salut (IUNICS/IdisPa), Universitat de les Illes Balears, Cra. Valldemossa km 7.5, E-07122, Palma de Mallorca, Spain. .,Redes Temáticas de Investigación Cooperativa en Salud-Red de Trastornos Adictivos (RETICS-RTA), ISCIII, Madrid, Spain.
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32
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Janero DR, Thakur GA. Leveraging allostery to improve G protein-coupled receptor (GPCR)-directed therapeutics: cannabinoid receptor 1 as discovery target. Expert Opin Drug Discov 2016; 11:1223-1237. [PMID: 27712124 DOI: 10.1080/17460441.2016.1245289] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
INTRODUCTION Allosteric modulators of G-protein coupled receptors (GPCRs) hold the promise of improved pharmacology and safety over typical orthosteric GPCR ligands. These features are particularly relevant to the cannabinoid receptor 1 (CB1R) GPCR, since typical orthosteric CB1R ligands are associated with adverse events that limit their translational potential. Areas covered: The contextual basis for applying allostery to CB1R is considered from pharmacological, drug-discovery, and medicinal standpoints. Rational design of small-molecule CB1R allosteric modulators as potential pharmacotherapeutics would be greatly facilitated by direct experimental characterization of structure-function correlates underlying the biological activity of chemically-diverse CB1R allosteric modulators, CB1R allosteric ligand-binding binding pockets, and amino acid contact residues critical to allosteric ligand engagement and activity. In these regards, designer covalent probes exhibiting well-characterized molecular pharmacology as CB1R allosteric modulators are emerging as valuable molecular reporters enabling experimental interrogation of CB1R allosteric site(s) and informing the design of new CB1R agents as drugs. Expert opinion: Synthesis and pharmacological profiling of CB1R allosteric ligands will continue to provide valuable insights into CB1R structure-function correlates. The resulting data should expand the repertoire of novel agents capable of exerting therapeutic benefit by modulating CB1R-dependent signaling.
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Affiliation(s)
- David R Janero
- a Center for Drug Discovery; Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences; Department of Chemistry and Chemical Biology, College of Science; and Health Sciences Entrepreneurs , Northeastern University , Boston , MA , USA
| | - Ganesh A Thakur
- b Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences , Northeastern University , Boston , MA , USA
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Shamseldin HE, Masuho I, Alenizi A, Alyamani S, Patil DN, Ibrahim N, Martemyanov KA, Alkuraya FS. GNB5 mutation causes a novel neuropsychiatric disorder featuring attention deficit hyperactivity disorder, severely impaired language development and normal cognition. Genome Biol 2016; 17:195. [PMID: 27677260 PMCID: PMC5037613 DOI: 10.1186/s13059-016-1061-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 09/12/2016] [Indexed: 11/23/2022] Open
Abstract
Background Neuropsychiatric disorders are common forms of disability in humans. Despite recent progress in deciphering the genetics of these disorders, their phenotypic complexity continues to be a major challenge. Mendelian neuropsychiatric disorders are rare but their study has the potential to unravel novel mechanisms that are relevant to their complex counterparts. Results In an extended consanguineous family, we identified a novel neuropsychiatric phenotype characterized by severe speech impairment, variable expressivity of attention deficit hyperactivity disorder (ADHD), and motor delay. We identified the disease locus through linkage analysis on 15q21.2, and exome sequencing revealed a novel missense variant in GNB5. GNB5 encodes an atypical β subunit of the heterotrimeric GTP-binding proteins (Gβ5). Gβ5 is enriched in the central nervous system where it forms constitutive complexes with members of the regulator of G protein signaling family of proteins to modulate neurotransmitter signaling that affects a number of neurobehavioral outcomes. Here, we show that the S81L mutant form of Gβ5 has significantly impaired activity in terminating responses that are elicited by dopamine. Conclusions We demonstrate that these deficits originate from the impaired expression of the mutant Gβ5 protein, resulting in the decreased ability to stabilize regulator of G protein signaling complexes. Our data suggest that this novel neuropsychiatric phenotype is the human equivalent of Gnb5 deficiency in mice, which manifest motor deficits and hyperactivity, and highlight a critical role of Gβ5 in normal behavior as well as language and motor development in humans. Electronic supplementary material The online version of this article (doi:10.1186/s13059-016-1061-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Hanan E Shamseldin
- Department of Genetics, King Faisal Specialist Hospital and Research Center, MBC-03, PO Box 3354, Riyadh, 11211, Saudi Arabia
| | - Ikuo Masuho
- Department of Neuroscience, The Scripps Research Institute, 130 Scripps Way, #3C2, Jupiter, FL, 33458, USA
| | - Ahmed Alenizi
- Department of Pediatrics, King Saud Medical City, Riyadh, Saudi Arabia
| | - Suad Alyamani
- Department of Neurosciences, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | - Dipak N Patil
- Department of Neuroscience, The Scripps Research Institute, 130 Scripps Way, #3C2, Jupiter, FL, 33458, USA
| | - Niema Ibrahim
- Department of Genetics, King Faisal Specialist Hospital and Research Center, MBC-03, PO Box 3354, Riyadh, 11211, Saudi Arabia
| | - Kirill A Martemyanov
- Department of Neuroscience, The Scripps Research Institute, 130 Scripps Way, #3C2, Jupiter, FL, 33458, USA.
| | - Fowzan S Alkuraya
- Department of Genetics, King Faisal Specialist Hospital and Research Center, MBC-03, PO Box 3354, Riyadh, 11211, Saudi Arabia. .,Department of Anatomy and Cell Biology, College of Medicine, Alfaisal University, Riyadh, Saudi Arabia.
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Trivellin G, Bjelobaba I, Daly AF, Larco DO, Palmeira L, Faucz FR, Thiry A, Leal LF, Rostomyan L, Quezado M, Schernthaner-Reiter MH, Janjic MM, Villa C, Wu TJ, Stojilkovic SS, Beckers A, Feldman B, Stratakis CA. Characterization of GPR101 transcript structure and expression patterns. J Mol Endocrinol 2016; 57:97-111. [PMID: 27282544 PMCID: PMC4959428 DOI: 10.1530/jme-16-0045] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 06/09/2016] [Indexed: 12/25/2022]
Abstract
We recently showed that Xq26.3 microduplications cause X-linked acrogigantism (X-LAG). X-LAG patients mainly present with growth hormone and prolactin-secreting adenomas and share a minimal duplicated region containing at least four genes. GPR101 was the only gene highly expressed in their pituitary lesions, but little is known about its expression patterns. In this work, GPR101 transcripts were characterized in human tissues by 5'-Rapid Amplification of cDNA Ends (RACE) and RNAseq, while the putative promoter was bioinformatically predicted. We investigated GPR101 mRNA and protein expression by RT-quantitative PCR (qPCR), whole-mount in situ hybridization, and immunostaining, in human, rhesus monkey, rat and zebrafish. We identified four GPR101 isoforms characterized by different 5'-untranslated regions (UTRs) and a common 6.1kb long 3'UTR. GPR101 expression was very low or absent in almost all adult human tissues examined, except for specific brain regions. Strong GPR101 staining was observed in human fetal pituitary and during adolescence, whereas very weak/absent expression was detected during childhood and adult life. In contrast to humans, adult monkey and rat pituitaries expressed GPR101, but in different cell types. Gpr101 is expressed in the brain and pituitary during rat and zebrafish development; in rat pituitary, Gpr101 is expressed only after birth and shows sexual dimorphism. This study shows that different GPR101 transcripts exist and that the brain is the major site of GPR101 expression across different species, although divergent species- and temporal-specific expression patterns are evident. These findings suggest an important role for GPR101 in brain and pituitary development and likely reflect the very different growth, development and maturation patterns among species.
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Affiliation(s)
- Giampaolo Trivellin
- Section on Endocrinology and GeneticsEunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, Maryland, USA
| | - Ivana Bjelobaba
- Section on Cellular SignalingEunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, Maryland, USA
| | - Adrian F Daly
- Department of EndocrinologyUniversity of Liège, Domaine Universitaire du Sart-Tilman, Liège, Belgium
| | - Darwin O Larco
- Department of Obstetrics and GynecologyUniformed Services University of the Health Sciences, Bethesda, Maryland, USA
| | - Leonor Palmeira
- Department of EndocrinologyUniversity of Liège, Domaine Universitaire du Sart-Tilman, Liège, Belgium
| | - Fabio R Faucz
- Section on Endocrinology and GeneticsEunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, Maryland, USA
| | - Albert Thiry
- Department of PathologyUniversity of Liège, Domaine Universitaire du Sart-Tilman, Liège, Belgium
| | - Letícia F Leal
- Section on Endocrinology and GeneticsEunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, Maryland, USA Department of PediatricsUniversity of Sao Paulo, Ribeirao Preto, São Paulo, Brazil
| | - Liliya Rostomyan
- Department of EndocrinologyUniversity of Liège, Domaine Universitaire du Sart-Tilman, Liège, Belgium
| | - Martha Quezado
- Laboratory of PathologyNational Cancer Institute (NCI), National Institutes of Health (NIH), Bethesda, Maryland, USA
| | - Marie Helene Schernthaner-Reiter
- Section on Endocrinology and GeneticsEunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, Maryland, USA
| | - Marija M Janjic
- Section on Cellular SignalingEunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, Maryland, USA
| | - Chiara Villa
- Department of EndocrinologyUniversity of Liège, Domaine Universitaire du Sart-Tilman, Liège, Belgium Hopital FochService d'Anatomie et Cytologie Pathologiques, Suresnes Cedex, France
| | - T John Wu
- Department of Obstetrics and GynecologyUniformed Services University of the Health Sciences, Bethesda, Maryland, USA
| | - Stanko S Stojilkovic
- Section on Cellular SignalingEunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, Maryland, USA
| | - Albert Beckers
- Department of EndocrinologyUniversity of Liège, Domaine Universitaire du Sart-Tilman, Liège, Belgium
| | - Benjamin Feldman
- Division of Developmental BiologyEunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, Maryland, USA
| | - Constantine A Stratakis
- Section on Endocrinology and GeneticsEunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, Maryland, USA
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Agnati LF, Marcoli M, Maura G, Fuxe K, Guidolin D. The multi-facet aspects of cell sentience and their relevance for the integrative brain actions: role of membrane protein energy landscape. Rev Neurosci 2016; 27:347-63. [DOI: 10.1515/revneuro-2015-0049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 11/11/2015] [Indexed: 12/14/2022]
Abstract
AbstractSeveral ion channels can be randomly and spontaneously in an open state, allowing the exchange of ion fluxes between extracellular and intracellular environments. We propose that the random changes in the state of ion channels could be also due to proteins exploring their energy landscapes. Indeed, proteins can modify their steric conformation under the effects of the physicochemical parameters of the environments with which they are in contact, namely, the extracellular, intramembrane and intracellular environments. In particular, it is proposed that the random walk of proteins in their energy landscape is towards attractors that can favor the open or close condition of the ion channels and/or intrinsic activity of G-protein-coupled receptors. The main aspect of the present proposal is that some relevant physicochemical parameters of the environments (e.g. molecular composition, temperature, electrical fields) with which some signaling-involved plasma membrane proteins are in contact alter their conformations. In turn, these changes can modify their information handling via a modulatory action on their random walk towards suitable attractors of their energy landscape. Thus, spontaneous and/or signal-triggered electrical activities of neurons occur that can have emergent properties capable of influencing the integrative actions of brain networks. Against this background, Cook’s hypothesis on ‘cell sentience’ is developed by proposing that physicochemical parameters of the environments with which the plasma-membrane proteins of complex cellular networks are in contact fulfill a fundamental role in their spontaneous and/or signal-triggered activity. Furthermore, it is proposed that a specialized organelle, the primary cilium, which is present in most cells (also neurons and astrocytes), could be of peculiar importance to pick up chemical signals such as ions and transmitters and to detect physical signals such as pressure waves, thermal gradients, and local field potentials.
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Affiliation(s)
| | - Manuela Marcoli
- 3University of Genova, Department of Pharmacy and Center of Excellence for Biomedical Research, Viale Cembrano 4, I-16148 Genova, Italy
| | - Guido Maura
- 3University of Genova, Department of Pharmacy and Center of Excellence for Biomedical Research, Viale Cembrano 4, I-16148 Genova, Italy
| | - Kjell Fuxe
- 2Karolinska Institutet, Department of Neuroscience, S-17177 Stockholm, Sweden
| | - Diego Guidolin
- 4University of Padova, Department of Molecular Medicine, I-35122 Padova, Italy
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Sustained Suppression of Hyperalgesia during Latent Sensitization by μ-, δ-, and κ-opioid receptors and α2A Adrenergic Receptors: Role of Constitutive Activity. J Neurosci 2016; 36:204-21. [PMID: 26740662 DOI: 10.1523/jneurosci.1751-15.2016] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Many chronic pain disorders alternate between bouts of pain and periods of remission. The latent sensitization model reproduces this in rodents by showing that the apparent recovery ("remission") from inflammatory or neuropathic pain can be reversed by opioid antagonists. Therefore, this remission represents an opioid receptor-mediated suppression of a sustained hyperalgesic state. To identify the receptors involved, we induced latent sensitization in mice and rats by injecting complete Freund's adjuvant (CFA) in the hindpaw. In WT mice, responses to mechanical stimulation returned to baseline 3 weeks after CFA. In μ-opioid receptor (MOR) knock-out (KO) mice, responses did not return to baseline but partially recovered from peak hyperalgesia. Antagonists of α2A-adrenergic and δ-opioid receptors reinstated hyperalgesia in WT mice and abolished the partial recovery from hyperalgesia in MOR KO mice. In rats, antagonists of α2A adrenergic and μ-, δ-, and κ-opioid receptors reinstated hyperalgesia during remission from CFA-induced hyperalgesia. Therefore, these four receptors suppress hyperalgesia in latent sensitization. We further demonstrated that suppression of hyperalgesia by MORs was due to their constitutive activity because of the following: (1) CFA-induced hyperalgesia was reinstated by the MOR inverse agonist naltrexone (NTX), but not by its neutral antagonist 6β-naltrexol; (2) pro-enkephalin, pro-opiomelanocortin, and pro-dynorphin KO mice showed recovery from hyperalgesia and reinstatement by NTX; (3) there was no MOR internalization during remission; (4) MORs immunoprecipitated from the spinal cord during remission had increased Ser(375) phosphorylation; and (5) electrophysiology recordings from dorsal root ganglion neurons collected during remission showed constitutive MOR inhibition of calcium channels. SIGNIFICANCE STATEMENT Chronic pain causes extreme suffering to millions of people, but its mechanisms remain to be unraveled. Latent sensitization is a phenomenon studied in rodents that has many key features of chronic pain: it is initiated by a variety of noxious stimuli, has indefinite duration, and pain appears in episodes that can be triggered by stress. Here, we show that, during latent sensitization, there is a sustained state of pain hypersensitivity that is continuously suppressed by the activation of μ-, δ-, and κ-opioid receptors and by adrenergic α2A receptors in the spinal cord. Furthermore, we show that the activation of μ-opioid receptors is not due to the release of endogenous opioids, but rather to its ligand-independent constitutive activity.
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Tassin V, Girard B, Chotte A, Fontanaud P, Rigault D, Kalinichev M, Perroy J, Acher F, Fagni L, Bertaso F. Phasic and Tonic mGlu7 Receptor Activity Modulates the Thalamocortical Network. Front Neural Circuits 2016; 10:31. [PMID: 27199672 PMCID: PMC4842779 DOI: 10.3389/fncir.2016.00031] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 04/05/2016] [Indexed: 11/13/2022] Open
Abstract
Mutation of the metabotropic glutamate receptor type 7 (mGlu7) induces absence-like epileptic seizures, but its precise role in the somatosensory thalamocortical network remains unknown. By combining electrophysiological recordings, optogenetics, and pharmacology, we dissected the contribution of the mGlu7 receptor at mouse thalamic synapses. We found that mGlu7 is functionally expressed at both glutamatergic and GABAergic synapses, where it can inhibit neurotransmission and regulate short-term plasticity. These effects depend on the PDZ-ligand of the receptor, as they are lost in mutant mice. Interestingly, the very low affinity of mGlu7 receptors for glutamate raises the question of how it can be activated, namely at GABAergic synapses and in basal conditions. Inactivation of the receptor activity with the mGlu7 negative allosteric modulator (NAM), ADX71743, enhances thalamic synaptic transmission. In vivo administration of the NAM induces a lethargic state with spindle and/or spike-and-wave discharges accompanied by a behavioral arrest typical of absence epileptic seizures. This provides evidence for mGlu7 receptor-mediated tonic modulation of a physiological function in vivo preventing synchronous and potentially pathological oscillations.
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Affiliation(s)
- Valériane Tassin
- CNRS, Institut de Génomique Fonctionnelle, UMR-5203Montpellier, France; INSERM, U1191Montpellier, France; UMR-5203, Université de MontpellierMontpellier, France
| | - Benoît Girard
- CNRS, Institut de Génomique Fonctionnelle, UMR-5203Montpellier, France; INSERM, U1191Montpellier, France; UMR-5203, Université de MontpellierMontpellier, France
| | - Apolline Chotte
- CNRS, Institut de Génomique Fonctionnelle, UMR-5203Montpellier, France; INSERM, U1191Montpellier, France; UMR-5203, Université de MontpellierMontpellier, France
| | - Pierre Fontanaud
- CNRS, Institut de Génomique Fonctionnelle, UMR-5203Montpellier, France; INSERM, U1191Montpellier, France; UMR-5203, Université de MontpellierMontpellier, France
| | | | | | - Julie Perroy
- CNRS, Institut de Génomique Fonctionnelle, UMR-5203Montpellier, France; INSERM, U1191Montpellier, France; UMR-5203, Université de MontpellierMontpellier, France
| | - Francine Acher
- CNRS, UMR-8601, Université Paris Descartes Paris, France
| | - Laurent Fagni
- CNRS, Institut de Génomique Fonctionnelle, UMR-5203Montpellier, France; INSERM, U1191Montpellier, France; UMR-5203, Université de MontpellierMontpellier, France
| | - Federica Bertaso
- CNRS, Institut de Génomique Fonctionnelle, UMR-5203Montpellier, France; INSERM, U1191Montpellier, France; UMR-5203, Université de MontpellierMontpellier, France
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Weiss N, Zamponi GW. All roads lead to presynaptic calcium channel inhibition by the ghrelin receptor: Separate agonist-dependent and -independent signaling pathways. ACTA ACUST UNITED AC 2015; 146:201-4. [PMID: 26283201 PMCID: PMC4555476 DOI: 10.1085/jgp.201511462] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Norbert Weiss
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., 199 00 Prague 9, Czech Republic
| | - Gerald W Zamponi
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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MacDonald K, Kimber MJ, Day TA, Ribeiro P. A constitutively active G protein-coupled acetylcholine receptor regulates motility of larval Schistosoma mansoni. Mol Biochem Parasitol 2015; 202:29-37. [PMID: 26365538 PMCID: PMC4607267 DOI: 10.1016/j.molbiopara.2015.09.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 09/05/2015] [Accepted: 09/07/2015] [Indexed: 12/20/2022]
Abstract
The neuromuscular system of helminths controls a variety of essential biological processes and therefore represents a good source of novel drug targets. The neuroactive substance, acetylcholine controls movement of Schistosoma mansoni but the mode of action is poorly understood. Here, we present first evidence of a functional G protein-coupled acetylcholine receptor in S. mansoni, which we have named SmGAR. A bioinformatics analysis indicated that SmGAR belongs to a clade of invertebrate GAR-like receptors and is related to vertebrate muscarinic acetylcholine receptors. Functional expression studies in yeast showed that SmGAR is constitutively active but can be further activated by acetylcholine and, to a lesser extent, the cholinergic agonist, carbachol. Anti-cholinergic drugs, atropine and promethazine, were found to have inverse agonist activity towards SmGAR, causing a significant decrease in the receptor's basal activity. An RNAi phenotypic assay revealed that suppression of SmGAR activity in early-stage larval schistosomulae leads to a drastic reduction in larval motility. In sum, our results provide the first molecular evidence that cholinergic GAR-like receptors are present in schistosomes and are required for proper motor control in the larvae. The results further identify SmGAR as a possible candidate for antiparasitic drug targeting.
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Affiliation(s)
- Kevin MacDonald
- Institute of Parasitology, McGill University, Macdonald Campus, 21,111 Lakeshore Road, Ste. Anne de Bellevue Quebec, H9X 3V9, Canada
| | - Michael J Kimber
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Tim A Day
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011, USA
| | - Paula Ribeiro
- Institute of Parasitology, McGill University, Macdonald Campus, 21,111 Lakeshore Road, Ste. Anne de Bellevue Quebec, H9X 3V9, Canada.
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On the modularity of the intrinsic flexibility of the µ opioid receptor: a computational study. PLoS One 2014; 9:e115856. [PMID: 25549261 PMCID: PMC4280117 DOI: 10.1371/journal.pone.0115856] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 12/01/2014] [Indexed: 11/19/2022] Open
Abstract
The µ opioid receptor (µOR), the principal target to control pain, belongs to the G protein-coupled receptors (GPCRs) family, one of the most highlighted protein families due to their importance as therapeutic targets. The conformational flexibility of GPCRs is one of their essential characteristics as they take part in ligand recognition and subsequent activation or inactivation mechanisms. It is assessed that the intrinsic mechanical properties of the µOR, more specifically its particular flexibility behavior, would facilitate the accomplishment of specific biological functions, at least in their first steps, even in the absence of a ligand or any chemical species usually present in its biological environment. The study of the mechanical properties of the µOR would thus bring some indications regarding the highly efficient ability of the µOR to transduce cellular message. We therefore investigate the intrinsic flexibility of the µOR in its apo-form using all-atom Molecular Dynamics simulations at the sub-microsecond time scale. We particularly consider the µOR embedded in a simplified membrane model without specific ions, particular lipids, such as cholesterol moieties, or any other chemical species that could affect the flexibility of the µOR. Our analyses highlighted an important local effect due to the various bendability of the helices resulting in a diversity of shape and volume sizes adopted by the µOR binding site. Such property explains why the µOR can interact with ligands presenting highly diverse structural geometry. By investigating the topology of the µOR binding site, a conformational global effect is depicted: the correlation between the motional modes of the extra- and intracellular parts of µOR on one hand, along with a clear rigidity of the central µOR domain on the other hand. Our results show how the modularity of the µOR flexibility is related to its pre-ability to activate and to present a basal activity.
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Zhang B, Albaker A, Plouffe B, Lefebvre C, Tiberi M. Constitutive activities and inverse agonism in dopamine receptors. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2014; 70:175-214. [PMID: 24931197 DOI: 10.1016/b978-0-12-417197-8.00007-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The concept of activation in the absence of agonists has been demonstrated for many GPCRs and is now solidified as one of the principal aspects of GPCR signaling. In this chapter, we review how dopamine receptors demonstrate this ability. Although difficult to prove in vivo due to the presence of endogenous dopamine and lack of subtype-selective inverse agonists and "pure" antagonists (neutral ligands), in vitro assays such as measuring intracellular cAMP, [(35)S]GTPγS binding, and [(3)H]thymidine incorporation have uncovered the constitutive activation of D1- and D2-class receptors. Nevertheless, because of limited and inconsistent findings, the existence of constitutive activity for D2-class receptors is currently not well established. Mutagenesis studies have shown that basal signaling, notably by D1-class receptors, is governed by the collective contributions of transmembrane domains and extracellular/intracellular loops, such as the third extracellular loop, the third intracellular loop, and C-terminal tail. Furthermore, constitutive activities of D1-class receptors are subjected to regulation by kinases. Among the dopamine receptor family, the D5 receptor subtype exhibits a higher basal signaling and bears resemblance to constitutively active mutant forms of GPCRs. The presence of its constitutive activity in vivo and its pathophysiological relevance, with a brief mention of other subtypes, are also discussed.
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Affiliation(s)
- Boyang Zhang
- Ottawa Hospital Research Institute (Neuroscience Program), Ottawa, Ontario, Canada; Departments of Medicine, Cellular & Molecular Medicine, Psychiatry, University of Ottawa, Ottawa, Ontario, Canada
| | - Awatif Albaker
- Ottawa Hospital Research Institute (Neuroscience Program), Ottawa, Ontario, Canada; Departments of Medicine, Cellular & Molecular Medicine, Psychiatry, University of Ottawa, Ottawa, Ontario, Canada
| | - Bianca Plouffe
- Department of Biochemistry, Université de Montréal, Montréal, Québec, Canada; Institut de recherche en immunologie, cancer, Montréal, Québec, Canada
| | - Caroline Lefebvre
- Ottawa Hospital Research Institute (Neuroscience Program), Ottawa, Ontario, Canada; Departments of Medicine, Cellular & Molecular Medicine, Psychiatry, University of Ottawa, Ottawa, Ontario, Canada
| | - Mario Tiberi
- Ottawa Hospital Research Institute (Neuroscience Program), Ottawa, Ontario, Canada; Departments of Medicine, Cellular & Molecular Medicine, Psychiatry, University of Ottawa, Ottawa, Ontario, Canada.
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