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Shi X, Walter NAR, Harkness JH, Neve KA, Williams RW, Lu L, Belknap JK, Eshleman AJ, Phillips TJ, Janowsky A. Genetic Polymorphisms Affect Mouse and Human Trace Amine-Associated Receptor 1 Function. PLoS One 2016; 11:e0152581. [PMID: 27031617 PMCID: PMC4816557 DOI: 10.1371/journal.pone.0152581] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 03/16/2016] [Indexed: 12/15/2022] Open
Abstract
Methamphetamine (MA) and neurotransmitter precursors and metabolites such as tyramine, octopamine, and β-phenethylamine stimulate the G protein-coupled trace amine-associated receptor 1 (TAAR1). TAAR1 has been implicated in human conditions including obesity, schizophrenia, depression, fibromyalgia, migraine, and addiction. Additionally TAAR1 is expressed on lymphocytes and astrocytes involved in inflammation and response to infection. In brain, TAAR1 stimulation reduces synaptic dopamine availability and alters glutamatergic function. TAAR1 is also expressed at low levels in heart, and may regulate cardiovascular tone. Taar1 knockout mice orally self-administer more MA than wild type and are insensitive to its aversive effects. DBA/2J (D2) mice express a non-synonymous single nucleotide polymorphism (SNP) in Taar1 that does not respond to MA, and D2 mice are predisposed to high MA intake, compared to C57BL/6 (B6) mice. Here we demonstrate that endogenous agonists stimulate the recombinant B6 mouse TAAR1, but do not activate the D2 mouse receptor. Progeny of the B6XD2 (BxD) family of recombinant inbred (RI) strains have been used to characterize the genetic etiology of diseases, but contrary to expectations, BXDs derived 30-40 years ago express only the functional B6 Taar1 allele whereas some more recently derived BXD RI strains express the D2 allele. Data indicate that the D2 mutation arose subsequent to derivation of the original RIs. Finally, we demonstrate that SNPs in human TAAR1 alter its function, resulting in expressed, but functional, sub-functional and non-functional receptors. Our findings are important for identifying a predisposition to human diseases, as well as for developing personalized treatment options.
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Affiliation(s)
- Xiao Shi
- Veterans Affairs Portland Health Care System, Portland, Oregon, United States of America
- The Methamphetamine Abuse Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Nicole A. R. Walter
- Veterans Affairs Portland Health Care System, Portland, Oregon, United States of America
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon, United States of America
| | - John H. Harkness
- Veterans Affairs Portland Health Care System, Portland, Oregon, United States of America
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Kim A. Neve
- Veterans Affairs Portland Health Care System, Portland, Oregon, United States of America
- The Methamphetamine Abuse Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Robert W. Williams
- Department of Genetics, Genomics and Informatics, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Lu Lu
- Department of Genetics, Genomics and Informatics, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
- Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong, Jiangsu, China
| | - John K. Belknap
- Veterans Affairs Portland Health Care System, Portland, Oregon, United States of America
- The Methamphetamine Abuse Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Amy J. Eshleman
- Veterans Affairs Portland Health Care System, Portland, Oregon, United States of America
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Tamara J. Phillips
- Veterans Affairs Portland Health Care System, Portland, Oregon, United States of America
- The Methamphetamine Abuse Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Aaron Janowsky
- Veterans Affairs Portland Health Care System, Portland, Oregon, United States of America
- The Methamphetamine Abuse Research Center, Oregon Health & Science University, Portland, Oregon, United States of America
- Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, Oregon, United States of America
- Department of Psychiatry, Oregon Health & Science University, Portland, Oregon, United States of America
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Suzuki K, Kaneko-Kawano T. Biological roles and therapeutic potential of G protein-coupled receptors for free fatty acids and metabolic intermediates. ACTA ACUST UNITED AC 2016. [DOI: 10.7600/jpfsm.5.213] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Kenji Suzuki
- College of Pharmaceutical Sciences, Ritsumeikan University
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Bolognini D, Tobin AB, Milligan G, Moss CE. The Pharmacology and Function of Receptors for Short-Chain Fatty Acids. Mol Pharmacol 2015; 89:388-98. [DOI: 10.1124/mol.115.102301] [Citation(s) in RCA: 163] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 12/29/2015] [Indexed: 12/11/2022] Open
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Edén D, Siegbahn A, Mokhtari D. Tissue factor/factor VIIa signalling promotes cytokine-induced beta cell death and impairs glucose-stimulated insulin secretion from human pancreatic islets. Diabetologia 2015; 58:2563-72. [PMID: 26271343 PMCID: PMC4589554 DOI: 10.1007/s00125-015-3729-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2015] [Accepted: 07/20/2015] [Indexed: 01/19/2023]
Abstract
AIMS/HYPOTHESIS Patients diagnosed with type 1 or type 2 diabetes have elevated levels of coagulation factor VIIa (FVIIa) and its receptor tissue factor (TF) in their bloodstream. This may affect the fate of the beta cells. We aimed to study the effects of TF/FVIIa signalling on cytokine-induced beta cell death and islet function in vitro. METHODS Human pancreatic islets and MIN-6 beta cells were used to study TF mRNA and protein expression using real-time PCR, immunoblotting and flow cytometry. The effects of TF/FVIIa on cytokine-induced beta cell death were studied in MIN-6 cells and human pancreatic islets using cell-death ELISA and propidium iodide and cleaved caspase-3 staining. Effects of TF/FVIIa on the phosphorylation of p38, extracellular signal-regulated kinase and c-Jun N-terminal kinase (JNK) were investigated by immunoblotting. Glucose-stimulated insulin secretion (GSIS) from human islets was measured with an insulin ELISA. RESULTS A combination of the cytokines IL-1β, TNF-α and IFN-γ induced TF expression in human pancreatic islets and in beta cells. TF/FVIIa did not affect basal beta cell death but, independently of downstream coagulation activity, augmented beta cell death in response to cytokines. The effect of TF/FVIIa on cytokine-induced beta cell death was found to be dependent on the stress kinase JNK, since FVIIa addition potentiated cytokine-induced JNK activation and JNK inhibition abolished the effect of TF/FVIIa on cytokine-induced beta cell death. Moreover, TF/FVIIa signalling resulted in inhibition of GSIS from human pancreatic islets. CONCLUSIONS/INTERPRETATION These results indicate that TF/FVIIa signalling has a negative effect on beta cell function and promotes beta cell death in response to cytokines.
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Affiliation(s)
- Desirée Edén
- Department of Medical Sciences, Clinical Chemistry, Science for Life Laboratory, University Hospital, Uppsala University, Entr. 61 3rd floor, S-751 85, Uppsala, Sweden
| | - Agneta Siegbahn
- Department of Medical Sciences, Clinical Chemistry, Science for Life Laboratory, University Hospital, Uppsala University, Entr. 61 3rd floor, S-751 85, Uppsala, Sweden
| | - Dariush Mokhtari
- Department of Medical Sciences, Clinical Chemistry, Science for Life Laboratory, University Hospital, Uppsala University, Entr. 61 3rd floor, S-751 85, Uppsala, Sweden.
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55
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Raab S, Wang H, Uhles S, Cole N, Alvarez-Sanchez R, Künnecke B, Ullmer C, Matile H, Bedoucha M, Norcross RD, Ottaway-Parker N, Perez-Tilve D, Conde Knape K, Tschöp MH, Hoener MC, Sewing S. Incretin-like effects of small molecule trace amine-associated receptor 1 agonists. Mol Metab 2015; 5:47-56. [PMID: 26844206 PMCID: PMC4703809 DOI: 10.1016/j.molmet.2015.09.015] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 09/21/2015] [Accepted: 09/22/2015] [Indexed: 12/05/2022] Open
Abstract
Objective Type 2 diabetes and obesity are emerging pandemics in the 21st century creating worldwide urgency for the development of novel and safe therapies. We investigated trace amine-associated receptor 1 (TAAR1) as a novel target contributing to the control of glucose homeostasis and body weight. Methods We investigated the peripheral human tissue distribution of TAAR1 by immunohistochemistry and tested the effect of a small molecule TAAR1 agonist on insulin secretion in vitro using INS1E cells and human islets and on glucose tolerance in C57Bl6, and db/db mice. Body weight effects were investigated in obese DIO mice. Results TAAR1 activation by a selective small molecule agonist increased glucose-dependent insulin secretion in INS1E cells and human islets and elevated plasma PYY and GLP-1 levels in mice. In diabetic db/db mice, the TAAR1 agonist normalized glucose excursion during an oral glucose tolerance test. Sub-chronic treatment of diet-induced obese (DIO) mice with the TAAR1 agonist resulted in reduced food intake and body weight. Furthermore insulin sensitivity was improved and plasma triglyceride levels and liver triglyceride content were lower than in controls. Conclusions We have identified TAAR1 as a novel integrator of metabolic control, which acts on gastrointestinal and pancreatic islet hormone secretion. Thus TAAR1 qualifies as a novel and promising target for the treatment of type 2 diabetes and obesity. TAAR1 is a novel key player in metabolic control. TAAR1 is expressed in β-cells and intestinal enteroendocrine cells in mice and humans. TAAR1 agonist improved glucose tolerance and reduced body weight in mouse disease models.
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Affiliation(s)
- Susanne Raab
- Roche Pharma Research & Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Haiyan Wang
- Roche Pharma Research & Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Sabine Uhles
- Roche Pharma Research & Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Nadine Cole
- Roche Pharma Research & Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Ruben Alvarez-Sanchez
- Roche Pharma Research & Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Basil Künnecke
- Roche Pharma Research & Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Christoph Ullmer
- Roche Pharma Research & Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Hugues Matile
- Roche Pharma Research & Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Marc Bedoucha
- Roche Pharma Research & Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Roger D Norcross
- Roche Pharma Research & Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Nickki Ottaway-Parker
- Department of Internal Medicine, Metabolic Disease Institute, University of Cincinnati, Cincinnati, OH 45237, USA
| | - Diego Perez-Tilve
- Department of Internal Medicine, Metabolic Disease Institute, University of Cincinnati, Cincinnati, OH 45237, USA
| | - Karin Conde Knape
- Roche Pharma Research & Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Matthias H Tschöp
- Helmholtz Diabetes Center, Helmholtz Zentrum München and Division of Metabolic Diseases, Technische Universität München, Germany
| | - Marius C Hoener
- Roche Pharma Research & Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
| | - Sabine Sewing
- Roche Pharma Research & Early Development (pRED), Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, CH-4070 Basel, Switzerland
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McNelis JC, Lee YS, Mayoral R, van der Kant R, Johnson AMF, Wollam J, Olefsky JM. GPR43 Potentiates β-Cell Function in Obesity. Diabetes 2015; 64:3203-17. [PMID: 26023106 PMCID: PMC4542437 DOI: 10.2337/db14-1938] [Citation(s) in RCA: 157] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 05/14/2015] [Indexed: 12/25/2022]
Abstract
The intestinal microbiome can regulate host energy homeostasis and the development of metabolic disease. Here we identify GPR43, a receptor for bacterially produced short-chain fatty acids (SCFAs), as a modulator of microbiota-host interaction. β-Cell expression of GPR43 and serum levels of acetate, an endogenous SCFA, are increased with a high-fat diet (HFD). HFD-fed GPR43 knockout (KO) mice develop glucose intolerance due to a defect in insulin secretion. In vitro treatment of isolated murine islets, human islets, and Min6 cells with (S)-2-(4-chlorophenyl)-3,3-dimethyl-N-(5-phenylthiazol-2-yl)butanamide (PA), a specific agonist of GPR43, increased intracellular inositol triphosphate and Ca(2+) levels, and potentiated insulin secretion in a GPR43-, Gαq-, and phospholipase C-dependent manner. In addition, KO mice fed an HFD displayed reduced β-cell mass and expression of differentiation genes, and the treatment of Min6 cells with PA increased β-cell proliferation and gene expression. Together these findings identify GPR43 as a potential target for therapeutic intervention.
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Affiliation(s)
- Joanne C McNelis
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Yun Sok Lee
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Rafael Mayoral
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Rik van der Kant
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA
| | - Andrew M F Johnson
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Joshua Wollam
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Jerrold M Olefsky
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, CA
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Führer D, Brix K, Biebermann H. Understanding the Healthy Thyroid State in 2015. Eur Thyroid J 2015; 4:1-8. [PMID: 26601068 PMCID: PMC4640297 DOI: 10.1159/000431318] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 05/12/2015] [Indexed: 12/22/2022] Open
Abstract
Thyroid hormones (TH) are of crucial importance for the physiological function of almost all organs. In cases of abnormal TH signaling, pathophysiological consequences may arise. The routine assessment of a healthy or diseased thyroid function state is currently based on the determination of serum concentrations of thyroid-stimulating hormone (TSH), and the TH T3 and T4. However, the definition of a 'normal' TSH range and similarly 'normal' T3 and T4 concentrations remains the subject of debate in different countries worldwide and has important implications on patient treatment in clinics. Not surprisingly, a significant number of patients whose thyroid function tests are biochemically determined to be within the normal range complain of impaired well-being. The reasons for this are so far not fully understood, but it has been recognized that thyroid function status needs to be 'individualized' and extended beyond simple TSH measurement. Thus, more precise and reliable parameters are required in order to optimally define the healthy thyroid status of an individual, and as a perspective to employ these in clinical routine. With the recent identification of new key players in TH action, a more accurate assessment of a patient's thyroid status may in the future become possible. Recently described distinct TH derivatives and metabolites, TH transporters, nongenomic TH effects (either through membrane-bound or cytosolic signaling), and classical nuclear TH action allow for insights into molecular and cellular preconditions of a healthy thyroid state. This will be a prerequisite to improve management of thyroid dysfunction, and additionally to prevent and target TH-related nonthyroid disease.
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Affiliation(s)
- Dagmar Führer
- Department of Endocrinology and Metabolism, University Hospital Essen, University Duisburg-Essen, Essen, Germany
- *Dagmar Führer, Department of Endocrinology and Metabolism, University Hospital Essen, Hufelandstrasse 55, DE-45147 Essen (Germany), E-Mail , Klaudia Brix, Department of Life Sciences and Chemistry, Jacobs University Bremen, Campus Ring 1, DE-28759 Bremen (Germany), E-Mail , Heike Biebermann, Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, DE-13353 Berlin (Germany), E-Mail
| | - Klaudia Brix
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Heike Biebermann
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
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Dinter J, Mühlhaus J, Jacobi SF, Wienchol CL, Cöster M, Meister J, Hoefig CS, Müller A, Köhrle J, Grüters A, Krude H, Mittag J, Schöneberg T, Kleinau G, Biebermann H. 3-iodothyronamine differentially modulates α-2A-adrenergic receptor-mediated signaling. J Mol Endocrinol 2015; 54:205-16. [PMID: 25878061 DOI: 10.1530/jme-15-0003] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/10/2015] [Indexed: 11/08/2022]
Abstract
Most in vivo effects of 3-iodothyronamine (3-T1AM) have been thus far thought to be mediated by binding at the trace amine-associated receptor 1 (TAAR1). Inconsistently, the 3-T1AM-induced hypothermic effect still persists in Taar1 knockout mice, which suggests additional receptor targets. In support of this general assumption, it has previously been reported that 3-T1AM also binds to the α-2A-adrenergic receptor (ADRA2A), which modulates insulin secretion. However, the mechanism of this effect remains unclear. We tested two different scenarios that may explain the effect: the sole action of 3-T1AM at ADRA2A and a combined action of 3-T1AM at ADRA2A and TAAR1, which is also expressed in pancreatic islets. We first investigated a potential general signaling modification using the label-free EPIC technology and then specified changes in signaling by cAMP inhibition and MAPKs (ERK1/2) determination. We found that 3-T1AM induced Gi/o activation at ADRA2A and reduced the norepinephrine (NorEpi)-induced MAPK activation. Interestingly, in ADRA2A/TAAR1 hetero-oligomers, application of NorEpi resulted in uncoupling of the Gi/o signaling pathway, but it did not affect MAPK activation. However, 3-T1AM application in mice over a period of 6 days at a daily dose of 5 mg/kg had no significant effects on glucose homeostasis. In summary, we report an agonistic effect of 3-T1AM on the ADRA2A-mediated Gi/o pathway but an antagonistic effect on MAPK induced by NorEpi. Moreover, in ADRA2A/TAAR1 hetero-oligomers, the capacity of NorEpi to stimulate Gi/o signaling is reduced by co-stimulation with 3-T1AM. The present study therefore points to a complex spectrum of signaling modification mediated by 3-T1AM at different G protein-coupled receptors.
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Affiliation(s)
- Juliane Dinter
- Institut für Experimentelle Pädiatrische EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, GermanyDepartment of Cell and Molecular BiologyKarolinska Institutet, Stockholm, SwedenInstitut für BiochemieMolekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, GermanyInstitut für Experimentelle EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Jessica Mühlhaus
- Institut für Experimentelle Pädiatrische EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, GermanyDepartment of Cell and Molecular BiologyKarolinska Institutet, Stockholm, SwedenInstitut für BiochemieMolekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, GermanyInstitut für Experimentelle EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Simon Friedrich Jacobi
- Institut für Experimentelle Pädiatrische EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, GermanyDepartment of Cell and Molecular BiologyKarolinska Institutet, Stockholm, SwedenInstitut für BiochemieMolekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, GermanyInstitut für Experimentelle EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany Institut für Experimentelle Pädiatrische EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, GermanyDepartment of Cell and Molecular BiologyKarolinska Institutet, Stockholm, SwedenInstitut für BiochemieMolekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, GermanyInstitut für Experimentelle EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Carolin Leonie Wienchol
- Institut für Experimentelle Pädiatrische EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, GermanyDepartment of Cell and Molecular BiologyKarolinska Institutet, Stockholm, SwedenInstitut für BiochemieMolekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, GermanyInstitut für Experimentelle EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Maxi Cöster
- Institut für Experimentelle Pädiatrische EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, GermanyDepartment of Cell and Molecular BiologyKarolinska Institutet, Stockholm, SwedenInstitut für BiochemieMolekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, GermanyInstitut für Experimentelle EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Jaroslawna Meister
- Institut für Experimentelle Pädiatrische EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, GermanyDepartment of Cell and Molecular BiologyKarolinska Institutet, Stockholm, SwedenInstitut für BiochemieMolekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, GermanyInstitut für Experimentelle EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Carolin Stephanie Hoefig
- Institut für Experimentelle Pädiatrische EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, GermanyDepartment of Cell and Molecular BiologyKarolinska Institutet, Stockholm, SwedenInstitut für BiochemieMolekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, GermanyInstitut für Experimentelle EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Anne Müller
- Institut für Experimentelle Pädiatrische EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, GermanyDepartment of Cell and Molecular BiologyKarolinska Institutet, Stockholm, SwedenInstitut für BiochemieMolekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, GermanyInstitut für Experimentelle EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Josef Köhrle
- Institut für Experimentelle Pädiatrische EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, GermanyDepartment of Cell and Molecular BiologyKarolinska Institutet, Stockholm, SwedenInstitut für BiochemieMolekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, GermanyInstitut für Experimentelle EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Annette Grüters
- Institut für Experimentelle Pädiatrische EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, GermanyDepartment of Cell and Molecular BiologyKarolinska Institutet, Stockholm, SwedenInstitut für BiochemieMolekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, GermanyInstitut für Experimentelle EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Heiko Krude
- Institut für Experimentelle Pädiatrische EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, GermanyDepartment of Cell and Molecular BiologyKarolinska Institutet, Stockholm, SwedenInstitut für BiochemieMolekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, GermanyInstitut für Experimentelle EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Jens Mittag
- Institut für Experimentelle Pädiatrische EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, GermanyDepartment of Cell and Molecular BiologyKarolinska Institutet, Stockholm, SwedenInstitut für BiochemieMolekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, GermanyInstitut für Experimentelle EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Torsten Schöneberg
- Institut für Experimentelle Pädiatrische EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, GermanyDepartment of Cell and Molecular BiologyKarolinska Institutet, Stockholm, SwedenInstitut für BiochemieMolekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, GermanyInstitut für Experimentelle EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Gunnar Kleinau
- Institut für Experimentelle Pädiatrische EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, GermanyDepartment of Cell and Molecular BiologyKarolinska Institutet, Stockholm, SwedenInstitut für BiochemieMolekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, GermanyInstitut für Experimentelle EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Heike Biebermann
- Institut für Experimentelle Pädiatrische EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, GermanyDepartment of Cell and Molecular BiologyKarolinska Institutet, Stockholm, SwedenInstitut für BiochemieMolekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, GermanyInstitut für Experimentelle EndokrinologieCharité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
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Kaihara KA, Dickson LM, Ellenbroek JH, Orr CMD, Layden BT, Wicksteed B. PKA Enhances the Acute Insulin Response Leading to the Restoration of Glucose Control. Diabetes 2015; 64:1688-97. [PMID: 25475437 PMCID: PMC4407848 DOI: 10.2337/db14-1051] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 11/24/2014] [Indexed: 12/18/2022]
Abstract
Diabetes arises from insufficient insulin secretion and failure of the β-cell mass to persist and expand. These deficits can be treated with ligands to Gs-coupled G-protein-coupled receptors that raise β-cell cAMP. Here we studied the therapeutic potential of β-cell cAMP-dependent protein kinase (PKA) activity in restoring glucose control using β-caPKA mice. PKA activity enhanced the acute insulin response (AIR) to glucose, which is a primary determinant of the efficacy of glucose clearance. Enhanced AIR improved peripheral insulin action, leading to more rapid muscle glucose uptake. In the setting of pre-established glucose intolerance caused by diet-induced insulin resistance or streptozotocin-mediated β-cell mass depletion, PKA activation enhanced β-cell secretory function to restore glucose control, primarily through augmentation of the AIR. Enhanced AIR and improved glucose control were maintained through 16 weeks of a high-fat diet and aging to 1 year. Importantly, improved glucose tolerance did not increase the risk for hypoglycemia, nor did it rely upon hyperinsulinemia or β-cell hyperplasia, although PKA activity was protective for β-cell mass. These data highlight that improving β-cell function through the activation of PKA has a large and underappreciated capacity to restore glucose control with minimal risk for adverse side effects.
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Affiliation(s)
- Kelly A Kaihara
- Kovler Diabetes Center, The University of Chicago, Chicago, IL Committee for Molecular Metabolism and Nutrition, The University of Chicago, Chicago, IL Section of Adult and Pediatric Endocrinology, Diabetes, and Metabolism, Department of Medicine, The University of Chicago, Chicago, IL
| | - Lorna M Dickson
- Kovler Diabetes Center, The University of Chicago, Chicago, IL Section of Adult and Pediatric Endocrinology, Diabetes, and Metabolism, Department of Medicine, The University of Chicago, Chicago, IL
| | - Johanne H Ellenbroek
- Kovler Diabetes Center, The University of Chicago, Chicago, IL Section of Adult and Pediatric Endocrinology, Diabetes, and Metabolism, Department of Medicine, The University of Chicago, Chicago, IL
| | - Caitlin M D Orr
- Kovler Diabetes Center, The University of Chicago, Chicago, IL Committee for Molecular Metabolism and Nutrition, The University of Chicago, Chicago, IL Section of Adult and Pediatric Endocrinology, Diabetes, and Metabolism, Department of Medicine, The University of Chicago, Chicago, IL
| | - Brian T Layden
- Division of Endocrinology, Metabolism, and Molecular Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL Jesse Brown Veterans Affairs Medical Center, Chicago, IL
| | - Barton Wicksteed
- Kovler Diabetes Center, The University of Chicago, Chicago, IL Committee for Molecular Metabolism and Nutrition, The University of Chicago, Chicago, IL Section of Adult and Pediatric Endocrinology, Diabetes, and Metabolism, Department of Medicine, The University of Chicago, Chicago, IL
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60
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Dinter J, Mühlhaus J, Wienchol CL, Yi CX, Nürnberg D, Morin S, Grüters A, Köhrle J, Schöneberg T, Tschöp M, Krude H, Kleinau G, Biebermann H. Inverse agonistic action of 3-iodothyronamine at the human trace amine-associated receptor 5. PLoS One 2015; 10:e0117774. [PMID: 25706283 PMCID: PMC4382497 DOI: 10.1371/journal.pone.0117774] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 12/30/2014] [Indexed: 12/28/2022] Open
Abstract
OBJECTIVE Application of 3-iodothyronamine (3-T1AM) results in decreased body temperature and body weight in rodents. The trace amine-associated receptor (TAAR) 1, a family A G protein-coupled receptor, is a target of 3-T1AM. However, 3-T1AM effects still persist in mTaar1 knockout mice, which suggest so far unknown further receptor targets that are of physiological relevance. TAAR5 is a highly conserved TAAR subtype among mammals and we here tested TAAR5 as a potential 3-T1AM target. First, we investigated mouse Taar5 (mTaar5) expression in several brain regions of the mouse in comparison to mTaar1. Secondly, to unravel the full spectrum of signaling capacities, we examined the distinct Gs-, Gi/o-, G12/13-, Gq/11- and MAP kinase-mediated signaling pathways of mouse and human TAAR5 under ligand-independent conditions and after application of 3-T1AM. We found overlapping localization of mTaar1 and mTaar5 in the amygdala and ventromedial hypothalamus of the mouse brain. Second, the murine and human TAAR5 (hTAAR5) display significant basal activity in the Gq/11 pathway but show differences in the basal activity in Gs and MAP kinase signaling. In contrast to mTaar5, 3-T1AM application at hTAAR5 resulted in significant reduction in basal IP3 formation and MAP kinase signaling. In conclusion, our data suggest that the human TAAR5 is a target for 3-T1AM, exhibiting inhibitory effects on IP3 formation and MAP kinase signaling pathways, but does not mediate Gs signaling effects as observed for TAAR1. This study also indicates differences between TAAR5 orthologs with respect to their signaling profile. In consequence, 3-T1AM-mediated effects may differ between rodents and humans.
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Affiliation(s)
- Juliane Dinter
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Jessica Mühlhaus
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Carolin Leonie Wienchol
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Chun-Xia Yi
- Institute for Diabetes and Obesity, Helmholtz-Zentrum München, German Research Center for Environmental Health, München, Germany
| | - Daniela Nürnberg
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Silke Morin
- Institute for Diabetes and Obesity, Helmholtz-Zentrum München, German Research Center for Environmental Health, München, Germany
| | - Annette Grüters
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Josef Köhrle
- Institut für Experimentelle Endokrinologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Torsten Schöneberg
- Institut für Biochemie, Molekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, Germany
| | - Matthias Tschöp
- Institut für Experimentelle Endokrinologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Heiko Krude
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Gunnar Kleinau
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Heike Biebermann
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin Berlin, Berlin, Germany
- * E-mail:
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61
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Abstract
Gi-GPCRs, G protein-coupled receptors that signal via Gα proteins of the i/o class (Gαi/o), acutely regulate cellular behaviors widely in mammalian tissues, but their impact on the development and growth of these tissues is less clear. For example, Gi-GPCRs acutely regulate insulin release from pancreatic β cells, and variants in genes encoding several Gi-GPCRs--including the α-2a adrenergic receptor, ADRA2A--increase the risk of type 2 diabetes mellitus. However, type 2 diabetes also is associated with reduced total β-cell mass, and the role of Gi-GPCRs in establishing β-cell mass is unknown. Therefore, we asked whether Gi-GPCR signaling regulates β-cell mass. Here we show that Gi-GPCRs limit the proliferation of the insulin-producing pancreatic β cells and especially their expansion during the critical perinatal period. Increased Gi-GPCR activity in perinatal β cells decreased β-cell proliferation, reduced adult β-cell mass, and impaired glucose homeostasis. In contrast, Gi-GPCR inhibition enhanced perinatal β-cell proliferation, increased adult β-cell mass, and improved glucose homeostasis. Transcriptome analysis detected the expression of multiple Gi-GPCRs in developing and adult β cells, and gene-deletion experiments identified ADRA2A as a key Gi-GPCR regulator of β-cell replication. These studies link Gi-GPCR signaling to β-cell mass and diabetes risk and identify it as a potential target for therapies to protect and increase β-cell mass in patients with diabetes.
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Loss of FFA2 and FFA3 increases insulin secretion and improves glucose tolerance in type 2 diabetes. Nat Med 2015; 21:173-7. [PMID: 25581519 DOI: 10.1038/nm.3779] [Citation(s) in RCA: 238] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 11/25/2014] [Indexed: 12/14/2022]
Abstract
Type 2 diabetes is a major health problem worldwide, and one of its key features is the inability of elevated glucose to stimulate the release of sufficient amounts of insulin from pancreatic beta cells to maintain normal blood glucose levels. New therapeutic strategies to improve beta cell function are therefore believed to be beneficial. Here we demonstrate that the short-chain fatty acid receptors FFA2 (encoded by FFAR2) and FFA3 (encoded by FFAR3) are expressed in mouse and human pancreatic beta cells and mediate an inhibition of insulin secretion by coupling to Gi-type G proteins. We also provide evidence that mice with dietary-induced obesity and type 2 diabetes, as compared to non-obese control mice, have increased local formation by pancreatic islets of acetate, an endogenous agonist of FFA2 and FFA3, as well as increased systemic levels. This elevation may contribute to the insufficient capacity of beta cells to respond to hyperglycemia in obese states. Indeed, we found that genetic deletion of both receptors, either on the whole-body level or specifically in pancreatic beta cells, leads to greater insulin secretion and a profound improvement of glucose tolerance when mice are on a high-fat diet compared to controls. On the other hand, deletion of Ffar2 and Ffar3 in intestinal cells did not alter glucose tolerance in diabetic animals, suggesting these receptors act in a cell-autonomous manner in beta cells to regulate insulin secretion. In summary, under diabetic conditions elevated acetate acts on FFA2 and FFA3 to inhibit proper glucose-stimulated insulin secretion, and we expect antagonists of FFA2 and FFA3 to improve insulin secretion in type 2 diabetes.
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63
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Beck TC, Gomes AC, Cyster JG, Pereira JP. CXCR4 and a cell-extrinsic mechanism control immature B lymphocyte egress from bone marrow. ACTA ACUST UNITED AC 2014; 211:2567-81. [PMID: 25403444 PMCID: PMC4267240 DOI: 10.1084/jem.20140457] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Joao Pereira and colleagues at Yale University show that B cell egress from bone marrow is a passive process, similar to that of red blood cells. Immature B cells that approached bone marrow sinusoids decreased their expression of CXCR4 and rounded up, allowing them to be passively swept away. Leukocyte residence in lymphoid organs is controlled by a balance between retention and egress-promoting chemoattractants sensed by pertussis toxin (PTX)–sensitive Gαi protein–coupled receptors (GPCRs). Here, we use two-photon intravital microscopy to show that immature B cell retention within bone marrow (BM) was strictly dependent on amoeboid motility mediated by CXCR4 and CXCL12 and by α4β1 integrin–mediated adhesion to VCAM-1. However, B lineage cell egress from BM is independent of PTX-sensitive GPCR signaling. B lineage cells expressing PTX rapidly exited BM even though their motility within BM parenchyma was significantly reduced. Our experiments reveal that when immature B cells are near BM sinusoids their motility is reduced, their morphology is predominantly rounded, and cells reverse transmigrate across sinusoidal endothelium in a largely nonamoeboid manner. Immature B cell egress from BM was dependent on a twofold CXCR4 down-regulation that was antagonized by antigen-induced BCR signaling. This passive mode of cell egress from BM also contributes significantly to the export of other hematopoietic cells, including granulocytes, monocytes, and NK cells, and is reminiscent of erythrocyte egress.
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Affiliation(s)
- Thomas C Beck
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520
| | - Ana Cordeiro Gomes
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520
| | - Jason G Cyster
- Howard Hughes Medical Institute and Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94143 Howard Hughes Medical Institute and Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94143
| | - João P Pereira
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT 06520
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64
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Modulation of gene expression by 3-iodothyronamine: genetic evidence for a lipolytic pattern. PLoS One 2014; 9:e106923. [PMID: 25379707 PMCID: PMC4224367 DOI: 10.1371/journal.pone.0106923] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 08/04/2014] [Indexed: 01/11/2023] Open
Abstract
3-Iodothyronamine (T1AM) is an endogenous biogenic amine, structurally related to thyroid hormone, which is regarded as a novel chemical messenger. The molecular mechanisms underlying T1AM effects are not known, but it is possible to envisage changes in gene expression, since delayed and long-lasting phenotypic effects have been reported, particularly with regard to the modulation of lipid metabolism and body weight. To test this hypothesis we analysed gene expression profiles in adipose tissue and liver of eight rats chronically treated with T1AM (10 mg/Kg twice a day for five days) as compared with eight untreated rats. In vivo T1AM administration produced significant transcriptional effects, since 378 genes were differentially expressed in adipose tissue, and 114 in liver. The reported changes in gene expression are expected to stimulate lipolysis and beta-oxidation, while inhibiting adipogenesis. T1AM also influenced the expression of several genes linked to lipoprotein metabolism suggesting that it may play an important role in the regulation of cholesterol homeostasis. No effect on the expression of genes linked to toxicity was observed. The assay of tissue T1AM showed that in treated animals its endogenous concentration increased by about one order of magnitude, without significant changes in tissue thyroid hormone concentration. Therefore, the effects that we observed might have physiological or pathophysiological importance. Our results provide the basis for the reported effectiveness of T1AM as a lipolytic agent and gain importance in view of a possible clinical use of T1AM in obesity and/or dyslipidaemia.
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65
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Leiss V, Flockerzie K, Novakovic A, Rath M, Schönsiegel A, Birnbaumer L, Schürmann A, Harteneck C, Nürnberg B. Insulin secretion stimulated by L-arginine and its metabolite L-ornithine depends on Gα(i2). Am J Physiol Endocrinol Metab 2014; 307:E800-12. [PMID: 25205820 PMCID: PMC4216945 DOI: 10.1152/ajpendo.00337.2014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Bordetella pertussis toxin (PTx), also known as islet-activating protein, induces insulin secretion by ADP-ribosylation of inhibitory G proteins. PTx-induced insulin secretion may result either from inactivation of Gα(o) proteins or from combined inactivation of Gα(o), Gα(i1), Gα(i2), and Gα(i3) isoforms. However, the specific role of Gα(i2) in pancreatic β-cells still remains unknown. In global (Gα(i2)(-/-)) and β-cell-specific (Gα(i2)(βcko)) gene-targeted Gα(i2) mouse models, we studied glucose homeostasis and islet functions. Insulin secretion experiments and intracellular Ca²⁺ measurements were used to characterize Gα(i2) function in vitro. Gα(i2)(-/-) and Gα(i2)(βcko) mice showed an unexpected metabolic phenotype, i.e., significantly lower plasma insulin levels upon intraperitoneal glucose challenge in Gα(i2)(-/-) and Gα(i2)(βcko) mice, whereas plasma glucose concentrations were unchanged in Gα(i2)(-/-) but significantly increased in Gα(i2)(βcko) mice. These findings indicate a novel albeit unexpected role for Gα(i2) in the expression, turnover, and/or release of insulin from islets. Detection of insulin secretion in isolated islets did not show differences in response to high (16 mM) glucose concentrations between control and β-cell-specific Gα(i2)-deficient mice. In contrast, the two- to threefold increase in insulin secretion evoked by L-arginine or L-ornithine (in the presence of 16 mM glucose) was significantly reduced in islets lacking Gα(i2). In accord with a reduced level of insulin secretion, intracellular calcium concentrations induced by the agonistic amino acid L-arginine did not reach control levels in β-cells. The presented analysis of gene-targeted mice provides novel insights in the role of β-cell Gα(i2) showing that amino acid-induced insulin-release depends on Gα(i2).
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MESH Headings
- Animals
- Arginine/metabolism
- Blood Glucose/analysis
- Calcium Signaling
- Crosses, Genetic
- Down-Regulation
- Fluorescent Antibody Technique
- GTP-Binding Protein alpha Subunit, Gi2/agonists
- GTP-Binding Protein alpha Subunit, Gi2/genetics
- GTP-Binding Protein alpha Subunit, Gi2/metabolism
- GTP-Binding Protein alpha Subunits, Gi-Go/agonists
- GTP-Binding Protein alpha Subunits, Gi-Go/genetics
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- Hyperglycemia/blood
- Hyperglycemia/metabolism
- Hyperglycemia/prevention & control
- Hypoglycemia/blood
- Hypoglycemia/metabolism
- Hypoglycemia/prevention & control
- Insulin/blood
- Insulin/metabolism
- Insulin Secretion
- Islets of Langerhans/cytology
- Islets of Langerhans/metabolism
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Ornithine/blood
- Ornithine/metabolism
- Specific Pathogen-Free Organisms
- Tissue Culture Techniques
- Up-Regulation
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Affiliation(s)
- Veronika Leiss
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, University of Tübingen, Tübingen, Germany
| | - Katarina Flockerzie
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, University of Tübingen, Tübingen, Germany
| | - Ana Novakovic
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, University of Tübingen, Tübingen, Germany
| | - Michaela Rath
- Department of Experimental Diabetology, German Institute of Human Nutrition, Potsdam-Rehbrücke, Nuthetal, Germany
| | - Annika Schönsiegel
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, University of Tübingen, Tübingen, Germany
| | - Lutz Birnbaumer
- Laboratory of Neurobiology, National Institute of Environmental Health Sciences, National Institutes of Health/Department of Health and Human Services, Durham, North Carolina
| | - Annette Schürmann
- Department of Experimental Diabetology, German Institute of Human Nutrition, Potsdam-Rehbrücke, Nuthetal, Germany
| | - Christian Harteneck
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, University of Tübingen, Tübingen, Germany
| | - Bernd Nürnberg
- Department of Pharmacology and Experimental Therapy, Institute of Experimental and Clinical Pharmacology and Toxicology, Eberhard Karls University Hospitals and Clinics, and Interfaculty Center of Pharmacogenomics and Drug Research, University of Tübingen, Tübingen, Germany;
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66
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Clemmensen C, Smajilovic S, Wellendorph P, Bräuner-Osborne H. The GPCR, class C, group 6, subtype A (GPRC6A) receptor: from cloning to physiological function. Br J Pharmacol 2014; 171:1129-41. [PMID: 24032653 DOI: 10.1111/bph.12365] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 07/25/2013] [Accepted: 08/26/2013] [Indexed: 12/16/2022] Open
Abstract
GPRC6A (GPCR, class C, group 6, subtype A) is a class C GPCR that has been cloned from human, mouse and rat. Several groups have shown that the receptor is activated by a range of basic and small aliphatic L-α-amino acids of which L-arginine, L-lysine and L-ornithine are the most potent compounds with EC50 values in the mid-micromolar range. In addition, several groups have shown that the receptor is either directly activated or positively modulated by divalent cations such as Ca(2+) albeit in concentrations above 5 mM, which is above the physiological concentration in most tissues. More recently, the peptide osteocalcin and the steroid testosterone have also been suggested to be endogenous GPRC6A agonists. The receptor is widely expressed in all three species which, along with the omnipresence of the amino acids and divalent cation ligands, suggest that the receptor could be involved in a broad range of physiological functions. So far, this has mainly been addressed by analyses of genetically modified mice where the GPRC6A receptor has been ablated. Although there has been some discrepancies among results reported from different groups, there is increasing evidence that the receptor is involved in regulation of inflammation, metabolism and endocrine functions. GPRC6A could thus be an interesting target for new drugs in these therapeutic areas.
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Affiliation(s)
- C Clemmensen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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67
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Zucchi R, Accorroni A, Chiellini G. Update on 3-iodothyronamine and its neurological and metabolic actions. Front Physiol 2014; 5:402. [PMID: 25360120 PMCID: PMC4199266 DOI: 10.3389/fphys.2014.00402] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 09/28/2014] [Indexed: 11/23/2022] Open
Abstract
3-iodothyronamine (T1AM) is an endogenous amine, that has been detected in many rodent tissues, and in human blood. It has been hypothesized to derive from thyroid hormone metabolism, but this hypothesis still requires validation. T1AM is not a ligand for nuclear thyroid hormone receptors, but stimulates with nanomolar affinity trace amine-associated receptor 1 (TAAR1), a G protein-coupled membrane receptor. With a lower affinity it interacts with alpha2A adrenergic receptors. Additional targets are represented by apolipoprotein B100, mitochondrial ATP synthase, and membrane monoamine transporters, but the functional relevance of these interactions is still uncertain. Among the effects reported after administration of exogenous T1AM to experimental animals, metabolic and neurological responses deserve special attention, because they were obtained at low dosages, which increased endogenous tissue concentration by about one order of magnitude. Systemic T1AM administration favored fatty acid over glucose catabolism, increased ketogenesis and increased blood glucose. Similar responses were elicited by intracerebral infusion, which inhibited insulin secretion and stimulated glucagon secretion. However, T1AM administration increased ketogenesis and gluconeogenesis also in hepatic cell lines and in perfused liver preparations, providing evidence for a peripheral action, as well. In the central nervous system, T1AM behaved as a neuromodulator, affecting adrenergic and/or histaminergic neurons. Intracerebral T1AM administration favored learning and memory, modulated sleep and feeding, and decreased the pain threshold. In conclusion T1AM should be considered as a component of thyroid hormone signaling and might play a significant physiological and/or pathophysiological role. T1AM analogs have already been synthetized and their therapeutical potential is currently under investigation. 3-iodothyronamine (T1AM) is a biogenic amine whose structure is closely related to that of thyroid hormone (3,5,3′-triiodothyronine, or T3). The differences with T3 are the absence of the carboxylate group and the substitution of iodine with hydrogen in 5 and 3′ positions (Figure 1). In this paper we will review the evidence supporting the hypothesis that T1AM is a chemical messenger, namely that it is an endogenous substance able to interact with specific receptors producing significant functional effects. Special emphasis will be placed on neurological and metabolic effects, which are likely to have physiological and pathophysiological importance.
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Affiliation(s)
- Riccardo Zucchi
- Laboratory of Biochemistry, Department of Pathology, University of Pisa Pisa, Italy
| | - Alice Accorroni
- Laboratory of Biochemistry, Department of Pathology, University of Pisa Pisa, Italy
| | - Grazia Chiellini
- Laboratory of Biochemistry, Department of Pathology, University of Pisa Pisa, Italy
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68
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Evidence for the gut microbiota short-chain fatty acids as key pathophysiological molecules improving diabetes. Mediators Inflamm 2014; 2014:162021. [PMID: 25214711 PMCID: PMC4151858 DOI: 10.1155/2014/162021] [Citation(s) in RCA: 201] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 08/06/2014] [Indexed: 01/10/2023] Open
Abstract
In type 2 diabetes, hyperglycemia, insulin resistance, increased inflammation, and oxidative stress were shown to be associated with the progressive deterioration of beta-cell function and mass. Short-chain fatty acids (SCFAs) are organic fatty acids produced in the distal gut by bacterial fermentation of macrofibrous material that might improve type 2 diabetes features. Their main beneficial activities were identified in the decrease of serum levels of glucose, insulin resistance as well as inflammation, and increase in protective Glucagon-like peptide-1 (GLP-1) secretion. In this review, we updated evidence on the effects of SCFAs potentially improving metabolic control in type 2 diabetes.
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69
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Zhao Z, Low YS, Armstrong NA, Ryu JH, Sun SA, Arvanites AC, Hollister-Lock J, Shah NH, Weir GC, Annes JP. Repurposing cAMP-modulating medications to promote β-cell replication. Mol Endocrinol 2014; 28:1682-97. [PMID: 25083741 DOI: 10.1210/me.2014-1120] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Loss of β-cell mass is a cardinal feature of diabetes. Consequently, developing medications to promote β-cell regeneration is a priority. cAMP is an intracellular second messenger that modulates β-cell replication. We investigated whether medications that increase cAMP stability or synthesis selectively stimulate β-cell growth. To identify cAMP-stabilizing medications that promote β-cell replication, we performed high-content screening of a phosphodiesterase (PDE) inhibitor library. PDE3, -4, and -10 inhibitors, including dipyridamole, were found to promote β-cell replication in an adenosine receptor-dependent manner. Dipyridamole's action is specific for β-cells and not α-cells. Next we demonstrated that norepinephrine (NE), a physiologic suppressor of cAMP synthesis in β-cells, impairs β-cell replication via activation of α(2)-adrenergic receptors. Accordingly, mirtazapine, an α(2)-adrenergic receptor antagonist and antidepressant, prevents NE-dependent suppression of β-cell replication. Interestingly, NE's growth-suppressive effect is modulated by endogenously expressed catecholamine-inactivating enzymes (catechol-O-methyltransferase and l-monoamine oxidase) and is dominant over the growth-promoting effects of PDE inhibitors. Treatment with dipyridamole and/or mirtazapine promote β-cell replication in mice, and treatment with dipyridamole is associated with reduced glucose levels in humans. This work provides new mechanistic insights into cAMP-dependent growth regulation of β-cells and highlights the potential of commonly prescribed medications to influence β-cell growth.
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Affiliation(s)
- Zhenshan Zhao
- Department of Medicine and Division of Endocrinology, Gerontology, and Metabolism (Z.Z., N.A.A., S.A.S., J.P.A.) and Stanford Center for Biomedical Informatics Research (Y.S.L.), Stanford University School of Medicine, Stanford, California 94306; Department of Stem Cell and Regenerative Biology (J.H.R., A.C.A.), Harvard University, Cambridge, Massachusetts 02138; and Section of Islet Cell and Regenerative Biology (J.H.-L., G.C.W.), Joslin Diabetes Center, Department of Medicine, Harvard Medical School, Boston, Massachusetts 02115
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70
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Ghelardoni S, Chiellini G, Frascarelli S, Saba A, Zucchi R. Uptake and metabolic effects of 3-iodothyronamine in hepatocytes. J Endocrinol 2014; 221:101-10. [PMID: 24627446 DOI: 10.1530/joe-13-0311] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
3-Iodothyronamine (T1AM) is an endogenous relative of thyroid hormone with profound metabolic effects. In different experimental models, T1AM increased blood glucose, and it is not clear whether this effect is entirely accounted by changes in insulin and/or glucagone secretion. Thus, in the present work, we investigated the uptake of T1AM by hepatocytes, which was compared with the uptake of thyroid hormones, and the effects of T1AM on hepatic glucose and ketone body production. Two different experimental models were used: HepG2 cells and perfused rat liver. Thyronines and thyronamines (T0AMs) were significantly taken up by hepatocytes. In HepG2 cells exposed to 1 μM T1AM, at the steady state, the cellular concentration of T1AM exceeded the medium concentration by six- to eightfold. Similar accumulation occurred with 3,5,3'-triiodothyronine and thyroxine. Liver experiments confirmed significant T1AM uptake. T1AM was partly catabolized and the major catabolites were 3-iodothyroacetic acid (TA1) (in HepG2 cells) and T0AM (in liver). In both preparations, infusion with 1 μM T1AM produced a significant increase in glucose production, if adequate gluconeogenetic substrates were provided. This effect was dampened at higher concentration (10 μM) or in the presence of the amine oxidase inhibitor iproniazid, while TA1 was ineffective, suggesting that T1AM may have a direct gluconeogenetic effect. Ketone body release was significantly increased in liver, while variable results were obtained in HepG2 cells incubated with gluconeogenetic substrates. These findings are consistent with the stimulation of fatty acid catabolism, and a shift of pyruvate toward gluconeogenesis. Notably, these effects are independent from hormonal changes and might have physiological and pathophysiological importance.
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Affiliation(s)
- Sandra Ghelardoni
- Dipartimento di Patologia Chirurgica Medica Molecolare e dell'Area Critica, University of Pisa, Via Roma 55, 56126 Pisa, Italy
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71
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Willinger T, Ferguson SM, Pereira JP, De Camilli P, Flavell RA. Dynamin 2-dependent endocytosis is required for sustained S1PR1 signaling. ACTA ACUST UNITED AC 2014; 211:685-700. [PMID: 24638168 PMCID: PMC3978280 DOI: 10.1084/jem.20131343] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The endocytosis regulator dynamin 2 is required for the regulation of S1PR1 internalization and continued S1PR1 signaling in low S1P environments. Sphingosine-1-phosphate (S1P) receptor 1 (S1PR1) is critical for lymphocyte egress from lymphoid organs. Lymphocytes encounter low S1P concentrations near exit sites before transmigration, yet S1PR1 signaling is rapidly terminated after exposure to S1P. How lymphocytes maintain S1PR1 signaling in a low S1P environment near egress sites is unknown. Here we identify dynamin 2, an essential component of endocytosis, as a novel regulator of T cell egress. Mice with T cell–specific dynamin 2 deficiency had profound lymphopenia and impaired egress from lymphoid organs. Dynamin 2 deficiency caused impaired egress through regulation of S1PR1 signaling, and transgenic S1PR1 overexpression rescued egress in dynamin 2 knockout mice. In low S1P concentrations, dynamin 2 was essential for S1PR1 internalization, which enabled continuous S1PR1 signaling and promoted egress from both thymus and lymph nodes. In contrast, dynamin 2–deficient cells were only capable of a pulse of S1PR1 signaling, which was insufficient for egress. Our results suggest a possible mechanism by which T lymphocytes positioned at exit portals sense low S1P concentrations, promoting their egress into circulatory fluids.
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Affiliation(s)
- Tim Willinger
- Department of Immunobiology, 2 Department of Cell Biology, 3 Program in Cellular Neuroscience, Neurodegeneration, and Repair, and 4 Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, CT 06520
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72
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Vaessen SFC, Bruysters MWP, Vandebriel RJ, Verkoeijen S, Bos R, Krul CAM, Akkermans AM. Toward a mechanism-based in vitro safety test for pertussis toxin. Hum Vaccin Immunother 2014; 10:1391-5. [PMID: 24553455 DOI: 10.4161/hv.28001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Pertussis vaccines are routinely administered to infants to protect them from whooping cough. Still, an adequate safety test for pertussis toxin (PT), one of the main antigens in these vaccines, is not available. The histamine sensitization test is currently the only assay accepted by regulatory authorities to test for the absence of active PT in vaccines. This is however, a lethal animal test with poor reproducibility. In addition, it is not clear whether the assumed underlying mechanism, i.e., ADP-ribosylation of G proteins, is the only effect that should be considered in safety evaluation of PT. The in vitro safety test for PT that we developed is based on the clinical effects of PT in humans. For this, human cell lines were chosen based on the cell types involved in the clinical effects of PT. These cell lines were exposed to PT and analyzed by microarray. In this review, we discuss the clinical effects of PT and the mechanisms that underlie them. The approach taken may provide as an example for other situations in which an in vitro assay based on clinical effects in humans is required.
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Affiliation(s)
- Stefan F C Vaessen
- Research Centre Technology & Innovation; Innovative testing in Life sciences and Chemistry; University of Applied Sciences; Utrecht, the Netherlands
| | - Martijn W P Bruysters
- Center for Health Protection; National Institute for Public Health and the Environment; Bilthoven, the Netherlands
| | - Rob J Vandebriel
- Center for Health Protection; National Institute for Public Health and the Environment; Bilthoven, the Netherlands
| | - Saertje Verkoeijen
- Research Centre Technology & Innovation; Innovative testing in Life sciences and Chemistry; University of Applied Sciences; Utrecht, the Netherlands
| | - Rogier Bos
- Central Committee on Research Involving Human Subjects; Den Haag, the Netherlands
| | - Cyrille A M Krul
- Research Centre Technology & Innovation; Innovative testing in Life sciences and Chemistry; University of Applied Sciences; Utrecht, the Netherlands
| | - Arnoud M Akkermans
- Center for Health Protection; National Institute for Public Health and the Environment; Bilthoven, the Netherlands
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73
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Haviland JA, Reiland H, Butz DE, Tonelli M, Porter WP, Zucchi R, Scanlan TS, Chiellini G, Assadi-Porter FM. NMR-based metabolomics and breath studies show lipid and protein catabolism during low dose chronic T(1)AM treatment. Obesity (Silver Spring) 2013; 21:2538-44. [PMID: 23512955 PMCID: PMC3692609 DOI: 10.1002/oby.20391] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 01/08/2013] [Accepted: 01/09/2013] [Indexed: 11/06/2022]
Abstract
OBJECTIVE 3-Iodothyronamine (T1 AM), an analog of thyroid hormone, is a recently discovered fast-acting endogenous metabolite. Single high-dose treatments of T1 AM have produced rapid short-term effects, including a reduction of body temperature, bradycardia, and hyperglycemia in mice. DESIGN AND METHODS The effect of daily low doses of T1 AM (10 mg/kg) for 8 days on weight loss and metabolism in spontaneously overweight mice was monitored. The experiments were repeated twice (n = 4). Nuclear magnetic resonance (NMR) spectroscopy of plasma and real-time analysis of exhaled (13) CO2 in breath by cavity ring down spectroscopy (CRDS) were used to detect T1 AM-induced lipolysis. RESULTS CRDS detected increased lipolysis in breath shortly after T1 AM administration that was associated with a significant weight loss but independent of food consumption. NMR spectroscopy revealed alterations in key metabolites in serum: valine, glycine, and 3-hydroxybutyrate, suggesting that the subchronic effects of T1 AM include both lipolysis and protein breakdown. After discontinuation of T1 AM treatment, mice regained only 1.8% of the lost weight in the following 2 weeks, indicating lasting effects of T1 AM on weight maintenance. CONCLUSIONS CRDS in combination with NMR and (13) C-metabolic tracing constitute a powerful method of investigation in obesity studies for identifying in vivo biochemical pathway shifts and unanticipated debilitating side effects.
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Affiliation(s)
- J. A. Haviland
- Department of Zoology, University of Wisconsin-Madison, 250 N. Mills Street, Madison, WI 53706, USA
| | - H. Reiland
- Department of Biochemistry, 433 Babcock Drive, Madison, WI 53706, USA
| | - D. E. Butz
- Department of Zoology, University of Wisconsin-Madison, 250 N. Mills Street, Madison, WI 53706, USA
| | - M. Tonelli
- National Magnetic Resonance Facility at Madison, 433 Babcock Drive, Madison, WI 53706, USA
| | - W. P. Porter
- Department of Zoology, University of Wisconsin-Madison, 250 N. Mills Street, Madison, WI 53706, USA
| | - R. Zucchi
- Dipartimento di Scienze dell’Uomo e dell’Ambiente, Università di Pisa, Pisa 56126, Italy
| | - T. S. Scanlan
- Department of Physiology & Pharmacology and Cell & Developmental Biology, Oregon Health & Science University, Portland, OR 97239-3098, USA
| | - G. Chiellini
- Department of Biochemistry, 433 Babcock Drive, Madison, WI 53706, USA
- Dipartimento di Scienze dell’Uomo e dell’Ambiente, Università di Pisa, Pisa 56126, Italy
- Authors of correspondence: NMR and breath studies: Fariba Assadi-Porter, Department of Biochemistry, 433 Babcock Dr, Madison WI 53706. Phone: (608) 261-1167; Fax: (608) 262-3453; , Animal design: Grazia Chiellini, Department of Biochemistry, 433 Babcock Dr, Madison WI 53706. Phone: (608)-262-3268, ; Dipartimento di Scienze dell’Uomo e dell’Ambiente, Università di Pisa, via Roma, 55 Pisa 56126, Italy. Phone: +39 050 2218677,
| | - F. M. Assadi-Porter
- National Magnetic Resonance Facility at Madison, 433 Babcock Drive, Madison, WI 53706, USA
- Department of Biochemistry, 433 Babcock Drive, Madison, WI 53706, USA
- Authors of correspondence: NMR and breath studies: Fariba Assadi-Porter, Department of Biochemistry, 433 Babcock Dr, Madison WI 53706. Phone: (608) 261-1167; Fax: (608) 262-3453; , Animal design: Grazia Chiellini, Department of Biochemistry, 433 Babcock Dr, Madison WI 53706. Phone: (608)-262-3268, ; Dipartimento di Scienze dell’Uomo e dell’Ambiente, Università di Pisa, via Roma, 55 Pisa 56126, Italy. Phone: +39 050 2218677,
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Denton EV, Craig CJ, Pongratz RL, Appelbaum JS, Doerner AE, Narayanan A, Shulman GI, Cline GW, Schepartz A. A β-peptide agonist of the GLP-1 receptor, a class B GPCR. Org Lett 2013; 15:5318-21. [PMID: 24087900 DOI: 10.1021/ol402568j] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Previous work has shown that certain β(3)-peptides can effectively mimic the side chain display of an α-helix and inhibit interactions between proteins, both in vitro and in cultured cells. Here we describe a β(3)-peptide analog of GLP-1, CC-3(Act), that interacts with the GLP-1R extracellular domain (nGLP-1R) in vitro in a manner that competes with exendin-4 and induces GLP-1R-dependent cAMP signaling in cultured CHO-K1 cells expressing GLP-1R.
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Affiliation(s)
- Elizabeth V Denton
- Department of Chemistry, Yale University , New Haven, Connecticut 06511, United States, Department of Internal Medicine, Yale University School of Medicine , New Haven, Connecticut 06536, United States, Department of Cell Biology, Yale University School of Medicine , New Haven, Connecticut 06520, United States, Department of Cellular and Molecular Physiology, Yale University School of Medicine , New Haven, Connecticut 06520, United States, Howard Hughes Medical Institute, Yale University School of Medicine , New Haven, Connecticut 06520, United States, and Department of Molecular, Cellular and Developmental Biology, Yale University , New Haven, Connecticut 06520, United States
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75
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Activation of Hedgehog signaling by loss of GNAS causes heterotopic ossification. Nat Med 2013; 19:1505-12. [PMID: 24076664 PMCID: PMC3917515 DOI: 10.1038/nm.3314] [Citation(s) in RCA: 158] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Accepted: 07/19/2013] [Indexed: 12/17/2022]
Abstract
Bone formation is exquisitely controlled in space and time. Heterotopic ossification (HO), the pathologic formation of extra-skeletal bone, occurs as a common complication of trauma or in genetic disorders and can be disabling and lethal. However, the underlying molecular mechanisms are largely unknown. Here we demonstrate that Gαs restricts bone formation to the skeleton by inhibiting Hedgehog (Hh) signaling in mesenchymal progenitor cells. In progressive osseous heteroplasia (POH), a human disease caused by null mutations in GNAS that encodes Gαs, HH signaling is upregulated in ectopic osteoblasts and progenitor cells. Ectopic Hh signaling is sufficient to induce HO, while Hh signaling inhibition blocks HO in animal models. As our previous work has shown that GNAS gain of function mutations upregulate WNT/β-Catenin signaling in fibrous dysplasia (FD), our findings identify Gαs as a critical regulator of osteoblast differentiation by maintaining a balance between two key signaling pathways: Wnt/β-catenin and Hh. HH signaling inhibitors developed for cancer therapy may be repurposed to treat HO and other diseases caused by GNAS inactivation.
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76
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Engelstoft MS, Park WM, Sakata I, Kristensen LV, Husted AS, Osborne-Lawrence S, Piper PK, Walker AK, Pedersen MH, Nøhr MK, Pan J, Sinz CJ, Carrington PE, Akiyama TE, Jones RM, Tang C, Ahmed K, Offermanns S, Egerod KL, Zigman JM, Schwartz TW. Seven transmembrane G protein-coupled receptor repertoire of gastric ghrelin cells. Mol Metab 2013; 2:376-92. [PMID: 24327954 DOI: 10.1016/j.molmet.2013.08.006] [Citation(s) in RCA: 242] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Accepted: 08/26/2013] [Indexed: 12/18/2022] Open
Abstract
The molecular mechanisms regulating secretion of the orexigenic-glucoregulatory hormone ghrelin remain unclear. Based on qPCR analysis of FACS-purified gastric ghrelin cells, highly expressed and enriched 7TM receptors were comprehensively identified and functionally characterized using in vitro, ex vivo and in vivo methods. Five Gαs-coupled receptors efficiently stimulated ghrelin secretion: as expected the β1-adrenergic, the GIP and the secretin receptors but surprisingly also the composite receptor for the sensory neuropeptide CGRP and the melanocortin 4 receptor. A number of Gαi/o-coupled receptors inhibited ghrelin secretion including somatostatin receptors SSTR1, SSTR2 and SSTR3 and unexpectedly the highly enriched lactate receptor, GPR81. Three other metabolite receptors known to be both Gαi/o- and Gαq/11-coupled all inhibited ghrelin secretion through a pertussis toxin-sensitive Gαi/o pathway: FFAR2 (short chain fatty acid receptor; GPR43), FFAR4 (long chain fatty acid receptor; GPR120) and CasR (calcium sensing receptor). In addition to the common Gα subunits three non-common Gαi/o subunits were highly enriched in ghrelin cells: GαoA, GαoB and Gαz. Inhibition of Gαi/o signaling via ghrelin cell-selective pertussis toxin expression markedly enhanced circulating ghrelin. These 7TM receptors and associated Gα subunits constitute a major part of the molecular machinery directly mediating neuronal and endocrine stimulation versus metabolite and somatostatin inhibition of ghrelin secretion including a series of novel receptor targets not previously identified on the ghrelin cell.
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Key Words
- 7TM, seven transmembrane segment
- BAC, bacterial artificial chromosome
- CCK, cholecystokinin
- CFMB, (S)-2-(4-chlorophenyl)-3,3-dimethyl-N-(5-phenylthiazol-2-yl)butamide
- CGRP, calcitonin gene-related peptide
- CHBA, 3-chloro-5-hydroxybenzoic acid
- Enteroendocrine
- G protein signaling
- GIP, glucose-dependent insulinotropic polypeptide
- GLP-1, glucagon-like peptide 1
- GPCR
- Ghrelin
- Metabolites
- PTx, Bordetella pertussis toxin
- PYY, peptide YY
- Secretion
- hrGFP, humanized Renilla reniformis green fluorescent protein
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Affiliation(s)
- Maja S Engelstoft
- Novo Nordisk Foundation Center for Basic Metabolic Research, Section for Metabolic Receptology and Enteroendocrinology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark ; Laboratory for Molecular Pharmacology, Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark
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77
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Elimination of von Hippel-Lindau function perturbs pancreas endocrine homeostasis in mice. PLoS One 2013; 8:e72213. [PMID: 23977255 PMCID: PMC3748057 DOI: 10.1371/journal.pone.0072213] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 07/08/2013] [Indexed: 12/23/2022] Open
Abstract
Mutations in the human homolog of the Vhlh gene [encoding the von-Hippel Lindau (VHL) protein] lead to tumor development. In mice, depletion of Vhlh in pancreatic ß-cells causes perturbed glucose homeostasis, but the role of this gene in other pancreatic cells is poorly understood. To investigate the function of VHL/HIF pathway in pancreatic cells, we inactivated Vhlh in the pancreatic epithelium as well as in the endocrine and exocrine lineages. Our results show that embryonic depletion of Vhlh within the pancreatic epithelium causes postnatal lethality due to severe hypoglycemia. The hypoglycemia is recapitulated in mice with endocrine-specific removal of Vhlh, while animals with loss of Vhlh predominantly in the exocrine compartment survive to adulthood with no overt defects in glucose metabolism. Mice with hypoglycemia display diminished insulin release in response to elevated glucose. Significantly, the glucagon response is impaired both in vivo (circulating glucagon levels) as well as in an in vitro secretion assay in isolated islets. Hypoxia also impairs glucagon secretion in a glucagon-expressing cell line in culture. Our results reveal a novel role for the hypoxia/HIF pathway in islet hormone secretion and maintenance of the fine balance that allows for the establishment of normoglycemia.
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78
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Nakajima K, Jain S, Ruiz de Azua I, McMillin SM, Rossi M, Wess J. Minireview: Novel aspects of M3 muscarinic receptor signaling in pancreatic β-cells. Mol Endocrinol 2013; 27:1208-16. [PMID: 23820900 DOI: 10.1210/me.2013-1084] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The release of insulin from pancreatic β-cells is regulated by a considerable number of G protein-coupled receptors. During the past several years, we have focused on the physiological importance of β-cell M3 muscarinic acetylcholine receptors (M3Rs). At the molecular level, the M3R selectively activates G proteins of the G(q) family. Phenotypic analysis of several M3R mutant mouse models, including a mouse strain that lacks M3Rs only in pancreatic β-cells, indicated that β-cell M3Rs play a key role in maintaining blood glucose levels within a normal range. Additional studies with transgenic M3R mouse models strongly suggest that strategies aimed to enhance signaling through β-cell M3Rs may prove useful in the treatment of type 2 diabetes. More recently, we analyzed transgenic mice that expressed an M3R-based designer receptor in a β-cell-specific fashion, which enabled us to chronically activate a β-cell G(q)-coupled receptor by a drug that is otherwise pharmacologically inert. Drug-dependent activation of this designer receptor stimulated the sequential activation of G(q), phospholipase C, ERK1/2, and insulin receptor substrate 2 signaling, thus triggering a series of events that greatly improved β-cell function. Most importantly, chronic stimulation of this pathway protected mice against experimentally induced diabetes and glucose intolerance, induced either by streptozotocin or by the consumption of an energy-rich, high-fat diet. Because β-cells are endowed with numerous receptors that mediate their cellular effects via activation of G(q)-type G proteins, these findings provide a rational basis for the development of novel antidiabetic drugs targeting this class of receptors.
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Affiliation(s)
- Kenichiro Nakajima
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892, USA
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79
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Manni ME, De Siena G, Saba A, Marchini M, Landucci E, Gerace E, Zazzeri M, Musilli C, Pellegrini-Giampietro D, Matucci R, Zucchi R, Raimondi L. Pharmacological effects of 3-iodothyronamine (T1AM) in mice include facilitation of memory acquisition and retention and reduction of pain threshold. Br J Pharmacol 2013; 168:354-62. [PMID: 22889145 DOI: 10.1111/j.1476-5381.2012.02137.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Revised: 06/18/2012] [Accepted: 07/28/2012] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE 3-Iodothyronamine (T1AM), an endogenous derivative of thyroid hormones, is regarded as a rapid modulator of behaviour and metabolism. To determine whether brain thyroid hormone levels contribute to these effects, we investigated the effect of central administration of T1AM on learning and pain threshold of mice either untreated or pretreated with clorgyline (2.5 mg·kg(-1) , i.p.), an inhibitor of amine oxidative metabolism. EXPERIMENTAL APPROACH T1AM (0.13, 0.4, 1.32 and 4 μg·kg(-1) ) or vehicle was injected i.c.v. into male mice, and after 30 min their effects on memory acquisition capacity, pain threshold and curiosity were evaluated by the following tests: passive avoidance, licking latency on the hot plate and movements on the hole-board platform. Plasma glycaemia was measured using a glucorefractometer. Brain levels of triiodothyroxine (T3), thyroxine (T4) and T1AM were measured by HPLC coupled to tandem MS. ERK1/2 activation and c-fos expression in different brain regions were evaluated by Western blot analysis. RESULTS T1AM improved learning capacity, decreased pain threshold to hot stimuli, enhanced curiosity and raised plasma glycaemia in a dose-dependent way, without modifying T3 and T4 brain concentrations. T1AM effects on learning and pain were abolished or significantly affected by clorgyline, suggesting a role for some metabolite(s), or that T1AM interacts at the rapid desensitizing target(s). T1AM activated ERK in different brain areas at lower doses than those effective on behaviour. CONCLUSIONS AND IMPLICATIONS T1AM is a novel memory enhancer. This feature might have important implications for the treatment of endocrine and neurodegenerative-induced memory disorders.
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80
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James TD, Moffett SX, Scanlan TS, Martin JV. Effects of acute microinjections of the thyroid hormone derivative 3-iodothyronamine to the preoptic region of adult male rats on sleep, thermoregulation and motor activity. Horm Behav 2013; 64:81-8. [PMID: 23702093 PMCID: PMC4091812 DOI: 10.1016/j.yhbeh.2013.05.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 02/22/2013] [Accepted: 05/11/2013] [Indexed: 11/27/2022]
Abstract
The decarboxylated thyroid hormone derivative 3-iodothyronamine (T1AM) has been reported as having behavioral and physiological consequences distinct from those of thyroid hormones. Here, we investigate the effects of T1AM on EEG-defined sleep after acute administration to the preoptic region of adult male rats. Our laboratory recently demonstrated a decrease in EEG-defined sleep after administration of 3,3',5-triiodo-l-thyronine (T3) to the same brain region. After injection of T1AM or vehicle solution, EEG, EMG, activity, and core body temperature were recorded for 24h. Sleep parameters were determined from EEG and EMG data. Earlier investigations found contrasting systemic effects of T3 and T1AM, such as decreased heart rate and body temperature after intraperitoneal T1AM injection. However, nREM sleep was decreased in the present study after injections of 1 or 3 μg T1AM, but not after 0.3 or 10 μg, closely mimicking the previously reported effects of T3 administration to the preoptic region. The biphasic dose-response observed after either T1AM or T3 administration seems to indicate shared mechanisms and/or functions of sleep regulation in the preoptic region. Consistent with systemic administration of T1AM, however, microinjection of T1AM decreased body temperature. The current study is the first to show modulation of sleep by T1AM, and suggests that T1AM and T3 have both shared and independent effects in the adult mammalian brain.
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Affiliation(s)
- Thomas D. James
- Center for Computational and Integrative Biology, Rutgers University, 315 Penn Street, Camden, NJ 08102, USA
| | - Steven X. Moffett
- Center for Computational and Integrative Biology, Rutgers University, 315 Penn Street, Camden, NJ 08102, USA
| | - Thomas S. Scanlan
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97239, USA
| | - Joseph V. Martin
- Center for Computational and Integrative Biology, Rutgers University, 315 Penn Street, Camden, NJ 08102, USA
- Corresponding author. Fax: +1 856 225 6312., (J.V. Martin)
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81
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Cumero S, Fogolari F, Domenis R, Zucchi R, Mavelli I, Contessi S. Mitochondrial F(0) F(1) -ATP synthase is a molecular target of 3-iodothyronamine, an endogenous metabolite of thyroid hormone. Br J Pharmacol 2012; 166:2331-47. [PMID: 22452346 DOI: 10.1111/j.1476-5381.2012.01958.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND AND PURPOSE 3-iodothyronamine (T1AM) is a metabolite of thyroid hormone acting as a signalling molecule via non-genomic effectors and can reach intracellular targets. Because of the importance of mitochondrial F(0) F(1) -ATP synthase as a drug target, here we evaluated interactions of T1AM with this enzyme. EXPERIMENTAL APPROACH Kinetic analyses were performed on F(0) F(1) -ATP synthase in sub-mitochondrial particles and soluble F(1) -ATPase. Activity assays and immunodetection of the inhibitor protein IF(1) were used and combined with molecular docking analyses. Effects of T1AM on H9c2 cardiomyocytes were measured by in situ respirometric analysis. KEY RESULTS T1AM was a non-competitive inhibitor of F(0) F(1) -ATP synthase whose binding was mutually exclusive with that of the inhibitors IF(1) and aurovertin B. Both kinetic and docking analyses were consistent with two different binding sites for T1AM. At low nanomolar concentrations, T1AM bound to a high-affinity region most likely located within the IF(1) binding site, causing IF(1) release. At higher concentrations, T1AM bound to a low affinity-region probably located within the aurovertin binding cavity and inhibited enzyme activity. Low nanomolar concentrations of T1AM increased ADP-stimulated mitochondrial respiration in cardiomyocytes, indicating activation of F(0) F(1) -ATP synthase consistent with displacement of endogenous IF(1,) , reinforcing the in vitro results. CONCLUSIONS AND IMPLICATIONS Effects of T1AM on F(0) F(1) -ATP synthase were twofold: IF(1) displacement and enzyme inhibition. By targeting F(0) F(1) -ATP synthase within mitochondria, T1AM might affect cell bioenergetics with a positive effect on mitochondrial energy production at low, endogenous, concentrations. T1AM putative binding locations overlapping with IF(1) and aurovertin binding sites are described.
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Affiliation(s)
- S Cumero
- Department of Medical and Biological Sciences, MATI Centre of Excellence, University of Udine, Udine, Italy
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82
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Hackenmueller SA, Marchini M, Saba A, Zucchi R, Scanlan TS. Biosynthesis of 3-iodothyronamine (T1AM) is dependent on the sodium-iodide symporter and thyroperoxidase but does not involve extrathyroidal metabolism of T4. Endocrinology 2012; 153:5659-67. [PMID: 22948220 PMCID: PMC3473208 DOI: 10.1210/en.2012-1254] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
3-Iodothyronamine (T(1)AM) is an endogenous thyroid hormone derivative with unknown biosynthetic origins. Structural similarities have led to the hypothesis that T(1)AM is an extrathyroidal metabolite of T(4). This study uses an isotope-labeled T(4) [heavy-T(4) (H-T(4))] that can be distinguished from endogenous T(4) by mass spectrometry, which allows metabolites to be identified based on the presence of this unique isotope signature. Endogenous T(1)AM levels depend upon thyroid status and decrease upon induction of hypothyroidism. However, in hypothyroid mice replaced with H-T(4), the isotope-labeled H-T(3) metabolite is detected, but no isotope-labeled T(1)AM is detected. These data suggest that T(1)AM is not an extrathyroidal metabolite of T(4), yet is produced by a process that requires the same biosynthetic factors necessary for T(4) synthesis.
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Affiliation(s)
- Sarah A Hackenmueller
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, 97239, USA
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83
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Pi M, Wu Y, Lenchik NI, Gerling I, Quarles LD. GPRC6A mediates the effects of L-arginine on insulin secretion in mouse pancreatic islets. Endocrinology 2012; 153:4608-15. [PMID: 22872579 PMCID: PMC3512028 DOI: 10.1210/en.2012-1301] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Accepted: 07/12/2012] [Indexed: 12/11/2022]
Abstract
L-arginine (l-Arg) is an insulin secretagogue, but the molecular mechanism whereby it stimulates insulin secretion from β-cells is not known. The possibility that l-Arg regulates insulin secretion through a G protein-coupled receptor (GPCR)-mediated mechanism is suggested by the high expression of the nutrient receptor GPCR family C group 6 member A (GPRC6A) in the pancreas and TC-6 β-cells and the finding that Gprc6a(-/]minus]) mice have abnormalities in glucose homeostasis. To test the direct role of GPRC6A in regulating insulin secretion, we evaluated the response of pancreatic islets derived from Gprc6a(-/]minus]) mice to L-Arg. We found that the islet size and insulin content were decreased in pancreatic islets from Gprac6a(-/]minus]) mice. These alterations were selective for β-cells, because there were no abnormalities in serum glucagon levels or glucagon content of islets derived from Gprac6a(-/]minus]) mice. Significant reduction was observed in both the pancreatic ERK response to L-Arg administration to Gprc6a(-/]minus]) mice in vivo and L-Arg-induced insulin secretion and production ex vivo in islets isolated from Gprc6a(-/]minus]) mice. L-Arg stimulation of cAMP accumulation in isolated islets isolated from Gprc6a(-/]minus]) mice was also diminished. These findings suggest that l-Arg stimulation of insulin secretion in β-cells is mediated, at least in part, through GPRC6A activation of cAMP pathways.
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Affiliation(s)
- Min Pi
- Department of Medicine, University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA.
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84
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Manni ME, De Siena G, Saba A, Marchini M, Dicembrini I, Bigagli E, Cinci L, Lodovici M, Chiellini G, Zucchi R, Raimondi L. 3-Iodothyronamine: a modulator of the hypothalamus-pancreas-thyroid axes in mice. Br J Pharmacol 2012; 166:650-8. [PMID: 22225569 DOI: 10.1111/j.1476-5381.2011.01823.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Preclinical pharmacology of 3-iodothyronamine (T1AM), an endogenous derivative of thyroid hormones, indicates that it is a rapid modulator of rodent metabolism and behaviour. Since T1AM undergoes rapid enzymatic degradation, particularly by MAO, we hypothesized that the effects of T1AM might be altered by inhibition of MAO. EXPERIMENTAL APPROACH We investigated the effects of injecting T1AM (i.c.v.) on (i) feeding behaviour, hyperglycaemia and plasma levels of thyroid hormones and (ii) T1AM systemic bioavailability, in overnight fasted mice, under control conditions and after pretreatment with the MAO inhibitor clorgyline. T1AM (1.3, 6.6, 13, 20 and 26 µg·kg(-1) ) or vehicle were injected i.c.v. in fasted male mice not pretreated or pretreated i.p. with clorgyline (2.5 mg·kg(-1) ). Glycaemia was measured by a glucorefractometer, plasma triiodothyronine (fT3) by a chemiluminescent immunometric assay, c-fos activation immunohistochemically and plasma T1AM by HPLC coupled to tandem-MS. KEY RESULTS T1AM, 1.3 µg·kg(-1) , produced a hypophagic effect (-24% vs. control) and reduced c-fos activation. This dose showed systemic bioavailability (0.12% of injected dose), raised plasma glucose levels and reduced peripheral insulin sensitivity (-33% vs. control) and plasma fT3 levels. These effects were not linearly related to the dose injected. Clorgyline pretreatment strongly increased the systemic bioavailability of T1AM and prevented the hyperglycaemia and reduction in fT3 induced by T1AM. CONCLUSIONS AND IMPLICATIONS T1AM induces central and peripheral effects including hyperglycaemia and a reduction in plasma fT3 levels in fasted mice. These effects critically depend on the concentration of T1AM or its metabolites in target organs.
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Affiliation(s)
- Maria Elena Manni
- Department of Pharmacology, University of Florence, Florence, Italy Department of Biochemistry, University of Pisa, Pisa, Tuscany, Italy
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85
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Denis C, Saulière A, Galandrin S, Sénard JM, Galés C. Probing heterotrimeric G protein activation: applications to biased ligands. Curr Pharm Des 2012; 18:128-44. [PMID: 22229559 DOI: 10.2174/138161212799040466] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2011] [Accepted: 11/09/2011] [Indexed: 12/17/2022]
Abstract
Cell surface G protein-coupled receptors (GPCRs) drive numerous signaling pathways involved in the regulation of a broad range of physiologic processes. Today, they represent the largest target for modern drugs development with potential application in all clinical fields. Recently, the concept of "ligand-directed trafficking" has led to a conceptual revolution in pharmacological theory, thus opening new avenues for drug discovery. Accordingly, GPCRs do not function as simple on-off switch but rather as filters capable of selecting the activation of specific signals and thus generating texture responses to ligands, a phenomenon often referred to as ligand-biased signaling. Also, one challenging task today remains optimization of pharmacological assays with increased sensitivity so to better appreciate the inherent texture of ligands. However, considering that a single receptor has pleiotropic signaling properties and that each signal can crosstalk at different levels, biased activity remains thus difficult to evaluate. One strategy to overcome these limitations would be examining the initial steps following receptor activation. Even, if some G protein independent functions have been recently described, heterotrimeric G protein activation remains a general hallmark for all GPCRs families and the first cellular event subsequent to agonist binding to the receptor. Herein, we review the different methodologies classically used or recently developed to monitor G protein activation and discussed them in the context of G protein biased-ligands.
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Affiliation(s)
- Colette Denis
- Institut des Maladies Métaboliques et Cardiovasculaires, Université Toulouse III Paul Sabatier, Centre Hospitalier Universitaire de Toulouse, France.
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86
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Chiellini G, Erba P, Carnicelli V, Manfredi C, Frascarelli S, Ghelardoni S, Mariani G, Zucchi R. Distribution of exogenous [125I]-3-iodothyronamine in mouse in vivo: relationship with trace amine-associated receptors. J Endocrinol 2012; 213:223-30. [PMID: 22442117 DOI: 10.1530/joe-12-0055] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
3-Iodothyronamine (T1AM) is a novel chemical messenger, structurally related to thyroid hormone, able to interact with G protein-coupled receptors known as trace amine-associated receptors (TAARs). Little is known about the physiological role of T1AM. In this prospective, we synthesized [125I]-T1AM and explored its distribution in mouse after injecting in the tail vein at a physiological concentration (0.3 nM). The expression of the nine TAAR subtypes was evaluated by quantitative real-time PCR. [125I]-T1AM was taken up by each organ. A significant increase in tissue vs blood concentration occurred in gallbladder, stomach, intestine, liver, and kidney. Tissue radioactivity decreased exponentially over time, consistent with biliary and urinary excretion, and after 24 h, 75% of the residual radioactivity was detected in liver, muscle, and adipose tissue. TAARs were expressed only at trace amounts in most of the tissues, the exceptions being TAAR1 in stomach and testis and TAAR8 in intestine, spleen, and testis. Thus, while T1AM has a systemic distribution, TAARs are only expressed in certain tissues suggesting that other high-affinity molecular targets besides TAARs exist.
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Affiliation(s)
- Grazia Chiellini
- Dipartimento di Scienze dell'Uomo e dell'Ambiente, University of Pisa, Via Roma 55, 56126 Pisa, Italy.
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Ku GM, Pappalardo Z, Luo CC, German MS, McManus MT. An siRNA screen in pancreatic beta cells reveals a role for Gpr27 in insulin production. PLoS Genet 2012; 8:e1002449. [PMID: 22253604 PMCID: PMC3257298 DOI: 10.1371/journal.pgen.1002449] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Accepted: 11/18/2011] [Indexed: 11/18/2022] Open
Abstract
The prevalence of type 2 diabetes in the United States is projected to double or triple by 2050. We reasoned that the genes that modulate insulin production might be new targets for diabetes therapeutics. Therefore, we developed an siRNA screening system to identify genes important for the activity of the insulin promoter in beta cells. We created a subclone of the MIN6 mouse pancreatic beta cell line that expresses destabilized GFP under the control of a 362 base pair fragment of the human insulin promoter and the mCherry red fluorescent protein under the control of the constitutively active rous sarcoma virus promoter. The ratio of the GFP to mCherry fluorescence of a cell indicates its insulin promoter activity. As G protein coupled receptors (GPCRs) have emerged as novel targets for diabetes therapies, we used this cell line to screen an siRNA library targeting all known mouse GPCRs. We identified several known GPCR regulators of insulin secretion as regulators of the insulin promoter. One of the top positive regulators was Gpr27, an orphan GPCR with no known role in beta cell function. We show that knockdown of Gpr27 reduces endogenous mouse insulin promoter activity and glucose stimulated insulin secretion. Furthermore, we show that Pdx1 is important for Gpr27's effect on the insulin promoter and insulin secretion. Finally, the over-expression of Gpr27 in 293T cells increases inositol phosphate levels, while knockdown of Gpr27 in MIN6 cells reduces inositol phosphate levels, suggesting this orphan GPCR might couple to Gq/11. In summary, we demonstrate a MIN6-based siRNA screening system that allows rapid identification of novel positive and negative regulators of the insulin promoter. Using this system, we identify Gpr27 as a positive regulator of insulin production. Pancreatic beta cells are the only physiologic source of insulin. When these cells are destroyed in type 1 diabetics, there is uncontrolled hyperglycemia from complete insulin deficiency. In type 2 diabetes, these same cells fail to increase insulin secretion to compensate for peripheral insulin resistance leading to relative insulin deficiency. We constructed a novel screening system to find new regulators of insulin production in this critical cell type. Here, we describe a screen of the G protein coupled receptors (GPCRs) and show a role for orphan GPCR, Gpr27, in insulin promoter activity and insulin secretion. We propose that Gpr27 is a novel target for diabetes therapeutics.
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Affiliation(s)
- Gregory M. Ku
- Diabetes Center, University of California San Francisco, San Francisco, California, United States of America
- Division of Endocrinology, Metabolism, and Diabetes, Department of Medicine, University of California San Francisco, San Francisco, California, United States of America
| | - Zachary Pappalardo
- Diabetes Center, University of California San Francisco, San Francisco, California, United States of America
| | - Chun Chieh Luo
- Diabetes Center, University of California San Francisco, San Francisco, California, United States of America
| | - Michael S. German
- Diabetes Center, University of California San Francisco, San Francisco, California, United States of America
- Division of Endocrinology, Metabolism, and Diabetes, Department of Medicine, University of California San Francisco, San Francisco, California, United States of America
| | - Michael T. McManus
- Diabetes Center, University of California San Francisco, San Francisco, California, United States of America
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America
- * E-mail:
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88
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Layden BT, Yalamanchi SK, Wolever TMS, Dunaif A, Lowe WL. Negative association of acetate with visceral adipose tissue and insulin levels. Diabetes Metab Syndr Obes 2012; 5:49-55. [PMID: 22419881 PMCID: PMC3299553 DOI: 10.2147/dmso.s29244] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND The composition of gut flora has been proposed as a cause of obesity, a major risk factor for type 2 diabetes. The objective of this study was to assess whether serum short chain fatty acids, a major by-product of fermentation in gut flora, are associated with obesity and/or diabetes-related traits (insulin sensitivity and secretion). METHODS The association of serum short chain fatty acids levels with measures of obesity was assessed using body mass index, computerized tomography scan, and dual photon X-ray absorptiometry scan. Insulin sensitivity and insulin secretion were both determined from an oral glucose tolerance test and insulin sensitivity was also determined from a hyperinsulinemic euglycemic clamp. RESULTS In this population of young, obese women, acetate was negatively associated with visceral adipose tissue determined by computerized tomography scan and dual photon X-ray absorptiometry scan, but not body mass index. The level of the short chain fatty acids acetate, but not propionate or butyrate, was also negatively associated with fasting serum insulin and 2 hour insulin levels in the oral glucose tolerance test. CONCLUSIONS In this population, serum acetate was negatively associated with visceral adipose tissue and insulin levels. Future studies need to verify these findings and expand on these observations in larger cohorts of subjects.
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Affiliation(s)
- Brian T Layden
- Division of Endocrinology, Metabolism and Molecular Medicine (BTL, SKY, AD, WLL), Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
- Correspondence: BT Layden, Division of Endocrinology, Metabolism and Molecular Medicine, Northwestern University Feinberg School of Medicine, Tarry Building 15-760, 303 East Chicago, Avenue, Chicago, Illinois, 60611-3008, USA, Tel +1 312 503 1610, Fax +1 312 908 9032, Email
| | - Sudha K Yalamanchi
- Division of Endocrinology, Metabolism and Molecular Medicine (BTL, SKY, AD, WLL), Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Thomas MS Wolever
- Department of Nutritional Sciences (TMSW), University of Toronto, Toronto, Canada
| | - Andrea Dunaif
- Division of Endocrinology, Metabolism and Molecular Medicine (BTL, SKY, AD, WLL), Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - William L Lowe
- Division of Endocrinology, Metabolism and Molecular Medicine (BTL, SKY, AD, WLL), Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
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89
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Roy G, Placzek E, Scanlan TS. ApoB-100-containing lipoproteins are major carriers of 3-iodothyronamine in circulation. J Biol Chem 2011; 287:1790-800. [PMID: 22128163 DOI: 10.1074/jbc.m111.275552] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
3-Iodothyronamine (T(1)AM) is a biogenic amine derivative of thyroid hormone present in tissue and blood of vertebrates. Approximately 99% of the circulating thyroid hormones are bound to plasma proteins, including three major thyroid hormone-binding proteins, and the question arises as to whether circulating T(1)AM is also bound to serum factors. We report here that T(1)AM is largely bound to a single protein component of human serum. Using T(1)AM-affinity chromatography, we isolated this protein, and sequence analysis identified it as apolipoprotein B-100 (apoB-100), the protein component of several low density lipoprotein particles. Consistent with this finding, we demonstrate that >90% of specifically bound T(1)AM in human serum resides in the apoB-100-containing low density lipoprotein fraction. T(1)AM reversibly binds to apoB-100-containing lipoprotein particles with an equilibrium dissociation constant (K(D)) of 17 nm and a T(1)AM/apoB-100 stoichiometry of 1:1. Competition binding assays demonstrate that this binding site is highly selective for T(1)AM. Intracellular T(1)AM uptake is significantly enhanced by apoB-100-containing lipoprotein particles. Modest enhancements to apoB-100 cellular uptake and secretion by T(1)AM were observed; however, multidose T(1)AM treatment did not affect lipid or lipoprotein inventory in vivo. Thus, it appears that apoB-100 serves as a carrier of circulating T(1)AM and affords a novel mechanism by which T(1)AM gains entry to cells.
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Affiliation(s)
- Gouriprassana Roy
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon 97239-3098, USA
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90
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G protein-coupled receptor signaling and sphingosine-1-phosphate play a phylogenetically conserved role in endocrine pancreas morphogenesis. Mol Cell Biol 2011; 31:4442-53. [PMID: 21911471 DOI: 10.1128/mcb.05702-11] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
During development pancreatic endocrine cells migrate in a coordinated fashion. This migration is necessary to form fully functional islets, but the mechanisms involved remain unknown. Therapeutic strategies to restore β-cell mass and islet functionality by reprogramming endogenous exocrine cells would be strengthened from simultaneous treatments that enhance endocrine cell clustering. We found that endocrine progenitors respond to and regulate G protein-coupled receptor (GPCR) signaling in order to cluster in islets. Rgs4, a dedicated regulator of GPCR signaling, was specifically expressed in early epithelial endocrine progenitors of both zebrafish and mouse, and its expression in the mouse endocrine progenitors was strictly dependent upon Ngn3, the key specification gene of the endocrine lineage. Rgs4 loss of function resulted in defects in islet cell aggregation. By genetically inactivating Gα(i)-mediated GPCR signaling in endocrine progenitors, we established its role in islet cell aggregation in both mouse and zebrafish. Finally, we identified sphingosine-1-phosphate (S1P) as a ligand mediating islet cell aggregation in both species acting through distinct but closely related receptors.
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91
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Muppidi JR, Arnon TI, Bronevetsky Y, Veerapen N, Tanaka M, Besra GS, Cyster JG. Cannabinoid receptor 2 positions and retains marginal zone B cells within the splenic marginal zone. ACTA ACUST UNITED AC 2011; 208:1941-8. [PMID: 21875957 PMCID: PMC3182059 DOI: 10.1084/jem.20111083] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In addition to other receptors, including sphingosine-1-phosphate receptor 1, cannabinoid receptor 2 positions mouse marginal zone B cells within the marginal zone and also prevents their loss to the blood. Specialized B cells residing in the splenic marginal zone (MZ) continuously survey the blood for antigens and are important for immunity to systemic infections. However, the cues that uniquely attract cells to the MZ have not been defined. Previous work demonstrated that mice deficient in cannabinoid receptor 2 (CB2) have decreased numbers of MZ B cells but it has been unclear whether CB2 regulates MZ B cell development or positioning. We show that MZ B cells are highly responsive to the CB2 ligand 2-arachidonylglycerol (2-AG) and that CB2 antagonism rapidly displaces small numbers of MZ B cells to the blood. Antagonism for longer durations depletes MZ B cells from the spleen. In mice deficient in sphingosine-1-phosphate receptor function, CB2 antagonism causes MZ B cell displacement into follicles. Moreover, CB2 overexpression is sufficient to position B cells to the splenic MZ. These findings establish a role for CB2 in guiding B cells to the MZ and in preventing their loss to the blood. As a consequence of their MZ B cell deficiency, CB2-deficient mice have reduced numbers of CD1d-high B cells. We show that CB2 deficiency results in diminished humoral responses to a CD1d-restricted systemic antigen.
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Affiliation(s)
- Jagan R Muppidi
- Howard Hughes Medical Institute, Department of Microbiology and Immunology, and Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
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92
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Kim W, Doyle ME, Liu Z, Lao Q, Shin YK, Carlson OD, Kim HS, Thomas S, Napora JK, Lee EK, Moaddel R, Wang Y, Maudsley S, Martin B, Kulkarni RN, Egan JM. Cannabinoids inhibit insulin receptor signaling in pancreatic β-cells. Diabetes 2011; 60:1198-209. [PMID: 21346174 PMCID: PMC3064093 DOI: 10.2337/db10-1550] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVE Optimal glucose homeostasis requires exquisitely precise adaptation of the number of insulin-secreting β-cells in the islets of Langerhans. Insulin itself positively regulates β-cell proliferation in an autocrine manner through the insulin receptor (IR) signaling pathway. It is now coming to light that cannabinoid 1 receptor (CB1R) agonism/antagonism influences insulin action in insulin-sensitive tissues. However, the cells on which the CB1Rs are expressed and their function in islets have not been firmly established. We undertook the current study to investigate if intraislet endogenous cannabinoids (ECs) regulate β-cell proliferation and if they influence insulin action. RESEARCH DESIGN AND METHODS We measured EC production in isolated human and mouse islets and β-cell line in response to glucose and KCl. We evaluated human and mouse islets, several β-cell lines, and CB1R-null (CB1R(-/-)) mice for the presence of a fully functioning EC system. We investigated if ECs influence β-cell physiology through regulating insulin action and demonstrated the therapeutic potential of manipulation of the EC system in diabetic (db/db) mice. RESULTS ECs are generated within β-cells, which also express CB1Rs that are fully functioning when activated by ligands. Genetic and pharmacologic blockade of CB1R results in enhanced IR signaling through the insulin receptor substrate 2-AKT pathway in β-cells and leads to increased β-cell proliferation and mass. CB1R antagonism in db/db mice results in reduced blood glucose and increased β-cell proliferation and mass, coupled with enhanced IR signaling in β-cells. Furthermore, CB1R activation impedes insulin-stimulated IR autophosphorylation on β-cells in a Gα(i)-dependent manner. CONCLUSIONS These findings provide direct evidence for a functional interaction between CB1R and IR signaling involved in the regulation of β-cell proliferation and will serve as a basis for developing new therapeutic interventions to enhance β-cell function and proliferation in diabetes.
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MESH Headings
- Animals
- Blotting, Western
- Cell Proliferation/drug effects
- Cells, Cultured
- Female
- GTP-Binding Protein alpha Subunit, Gi2/genetics
- GTP-Binding Protein alpha Subunit, Gi2/metabolism
- Glucose/pharmacology
- Humans
- Immunoprecipitation
- In Vitro Techniques
- Indoles/pharmacology
- Insulin-Secreting Cells/drug effects
- Insulin-Secreting Cells/metabolism
- Male
- Mice
- Mice, Mutant Strains
- Mice, Obese
- Piperidines/pharmacology
- Potassium Chloride/pharmacology
- Protein Binding
- Pyrazoles/pharmacology
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptor, Cannabinoid, CB1/metabolism
- Receptor, Insulin/metabolism
- Signal Transduction/drug effects
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Affiliation(s)
- Wook Kim
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Máire E. Doyle
- Division of Endocrinology, Johns Hopkins Medical Institutes, Baltimore, Maryland
| | - Zhuo Liu
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Qizong Lao
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Yu-Kyong Shin
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Olga D. Carlson
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Hee Seung Kim
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Sam Thomas
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Joshua K. Napora
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Eun Kyung Lee
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Ruin Moaddel
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Yan Wang
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Stuart Maudsley
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Bronwen Martin
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland
| | - Rohit N. Kulkarni
- Department of Islet Cell Biology and Regenerative Medicine, Joslin Diabetes Center, and Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Josephine M. Egan
- National Institute on Aging, National Institutes of Health, Baltimore, Maryland
- Corresponding author: Josephine M. Egan,
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93
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Millard SM, Louie AM, Wattanachanya L, Wronski TJ, Conklin BR, Nissenson RA. Blockade of receptor-activated G(i) signaling in osteoblasts in vivo leads to site-specific increases in cortical and cancellous bone formation. J Bone Miner Res 2011; 26:822-32. [PMID: 20939063 PMCID: PMC3179326 DOI: 10.1002/jbmr.273] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Osteoblasts play a critical role in the maintenance of bone mass through bone formation and regulation of bone resorption. Targeted expression of a constitutively active engineered G(i)-coupled G protein-coupled receptor (GPCR) to osteoblasts in vivo leads to severe osteopenia. However, little is known about the role of endogenous receptor-mediated G(i) signaling in regulating osteoblast function. In this study, we investigated the skeletal effects of blocking G(i)-coupled signaling in osteoblasts in vivo. This was accomplished by transgenic expression of the catalytic subunit of pertussis toxin (PTX) under control of the collagen Iα 2.3-kb promoter. These mice, designated Col1(2.3)(+)/PTX(+), showed increased cortical thickness at the femoral midshaft at 12 weeks of age. This correlated with increased periosteal bone formation associated with expanded mineralizing surface observed in 8-week-old mice of both genders. The cancellous bone phenotype of the Col1(2.3)(+)/PTX(+) mice was sexually dimorphic, with increases in fractional bone volume at the distal femur seen only in females. Similarly, while cancellous bone-formation rates were unchanged in males, they could not be quantified for female Col1(2.3)(+)/PTX(+) mice owing to the disorganized nature of the labeling pattern, which was consistent with rapid formation of woven bone. Alterations in osteoclast activity did not appear to participate in the phenotype. These data demonstrate that G(i)-coupled signaling by GPCRs endogenous to osteoblasts plays a complex role in the regulation of bone formation in a manner that is dependent on both gender and the anatomic site within bone.
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Affiliation(s)
- Susan M Millard
- Endocrine Research Unit, Veterans Administration Medical Center, University of California San Francisco, San Francisco, CA 94121, USA
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94
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CXCR4 and CXCR7 have distinct functions in regulating interneuron migration. Neuron 2011; 69:61-76. [PMID: 21220099 DOI: 10.1016/j.neuron.2010.12.005] [Citation(s) in RCA: 219] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2010] [Indexed: 11/24/2022]
Abstract
CXCL12/CXCR4 signaling is critical for cortical interneuron migration and their final laminar distribution. No information is yet available on CXCR7, a newly defined CXCL12 receptor. Here we demonstrated that CXCR7 regulated interneuron migration autonomously, as well as nonautonomously through its expression in immature projection neurons. Migrating cortical interneurons coexpressed Cxcr4 and Cxcr7, and Cxcr7(-/-) and Cxcr4(-/-) mutants had similar defects in interneuron positioning. Ectopic CXCL12 expression and pharmacological blockade of CXCR4 in Cxcr7(-/-) mutants showed that both receptors were essential for responding to CXCL12 during interneuron migration. Furthermore, live imaging revealed that Cxcr4(-/-) and Cxcr7(-/-) mutants had opposite defects in interneuron motility and leading process morphology. In vivo inhibition of Gα(i/o) signaling in migrating interneurons phenocopied the interneuron lamination defects of Cxcr4(-/-) mutants. On the other hand, CXCL12 stimulation of CXCR7, but not CXCR4, promoted MAP kinase signaling. Thus, we suggest that CXCR4 and CXCR7 have distinct roles and signal transduction in regulating interneuron movement and laminar positioning.
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95
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Roger B, Papin J, Vacher P, Raoux M, Mulot A, Dubois M, Kerr-Conte J, Voy BH, Pattou F, Charpentier G, Jonas JC, Moustaïd-Moussa N, Lang J. Adenylyl cyclase 8 is central to glucagon-like peptide 1 signalling and effects of chronically elevated glucose in rat and human pancreatic beta cells. Diabetologia 2011; 54:390-402. [PMID: 21046358 DOI: 10.1007/s00125-010-1955-x] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Accepted: 09/08/2010] [Indexed: 01/19/2023]
Abstract
AIMS/HYPOTHESIS Glucose and incretins regulate beta cell function, gene expression and insulin exocytosis via calcium and cAMP. Prolonged exposure to elevated glucose (also termed glucotoxicity) disturbs calcium homeostasis, but little is known about cAMP signalling. We therefore investigated long-term effects of glucose on this pathway with special regard to the incretin glucagon-like peptide 1 (GLP-1). METHODS We exposed INS-1E cells and rat or human islets to different levels of glucose for 3 days and determined functional responses in terms of second messengers (cAMP, Ca(2+)), transcription profiles, activation of cAMP-responsive element (CRE) and secretion by measuring membrane capacitance. Moreover, we modulated directly the abundance of a calcium-sensitive adenylyl cyclase (ADCY8) and GLP-1 receptor (GLP1R). RESULTS GLP-1- or forskolin-mediated increases in cytosolic calcium, cAMP-levels or insulin secretion were largely reduced in INS-1E cells cultured at elevated glucose (>5.5 mmol/l). Statistical analysis of transcription profiles identified cAMP pathways as major targets regulated by glucose. Quantitative PCR confirmed these findings and unravelled marked downregulation of the calcium-sensitive adenylyl cyclase ADCY8 also in rat and in human islets. Re-expression of ADCY8, but not of the GLP1R, recovered GLP-1 signalling in glucotoxicity in INS-1E cells and in rat islets. Moreover, knockdown of this adenylyl cyclase showed that GLP-1-induced cAMP generation, calcium signalling, activation of the downstream target CRE and direct amplification of exocytosis by cAMP-raising agents (evaluated by capacitance measurement) proceeds via ADCY8. CONCLUSIONS/INTERPRETATION cAMP-mediated pathways are modelled by glucose, and downregulation of the calcium-sensitive ADCY8 plays a central role herein, including signalling via the GLP1R.
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Affiliation(s)
- B Roger
- Université de Bordeaux 1, Institut Européen de Chimie et Biologie, UMR CNRS 5248, 2 Av Robert Escarpit, 33607 Pessac, France
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96
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Ruiz de Azua I, Gautam D, Guettier JM, Wess J. Novel insights into the function of β-cell M3 muscarinic acetylcholine receptors: therapeutic implications. Trends Endocrinol Metab 2011; 22:74-80. [PMID: 21106385 PMCID: PMC3053051 DOI: 10.1016/j.tem.2010.10.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 10/20/2010] [Accepted: 10/20/2010] [Indexed: 12/25/2022]
Abstract
Impaired function of pancreatic β-cells is one of the hallmarks of type 2 diabetes. β-cell function is regulated by the activity of many hormones and neurotransmitters, which bind to specific cell surface receptors. The M(3) muscarinic acetylcholine receptor (M3R) belongs to the superfamily of G protein-coupled receptors and, following ligand dependent activation, selectively activates G proteins of the G(q/11) family. Recent studies with M3R mutant mice strongly suggest that β-cell M3Rs play a central role in promoting insulin release and maintaining correct glucose homeostasis. In this review, we highlight recent studies indicating that β-cell M3Rs and components of downstream signaling pathways might represent promising new targets for the treatment of type 2 diabetes.
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Affiliation(s)
- Inigo Ruiz de Azua
- Molecular Signaling Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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97
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Augmented glucose-induced insulin release in mice lacking G(o2), but not G(o1) or G(i) proteins. Proc Natl Acad Sci U S A 2011; 108:1693-8. [PMID: 21220323 DOI: 10.1073/pnas.1018903108] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Insulin secretion by pancreatic β cells is a complex and highly regulated process. Disruption of this process can lead to diabetes mellitus. One of the various pathways involved in the regulation of insulin secretion is the activation of heterotrimeric G proteins. Bordetella pertussis toxin (PTX) promotes insulin secretion, suggesting the involvement of one or more of three G(i) and/or two G(o) proteins as suppressors of insulin secretion from β cells. However, neither the mechanism of this inhibitory modulation of insulin secretion nor the identity of the G(i/o) proteins involved has been elucidated. Here we show that one of the two splice variants of G(o), G(o2), is a key player in the control of glucose-induced insulin secretion by β cells. Mice lacking G(o2)α, but not those lacking α subunits of either G(o1) or any G(i) proteins, handle glucose loads more efficiently than wild-type (WT) mice, and do so by increased glucose-induced insulin secretion. We thus provide unique genetic evidence that the G(o2) protein is a transducer in an inhibitory pathway that prevents damaging oversecretion of insulin.
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98
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Kobayashi NR, Hawes SM, Crook JM, Pébay A. G-protein coupled receptors in stem cell self-renewal and differentiation. Stem Cell Rev Rep 2010; 6:351-66. [PMID: 20625855 DOI: 10.1007/s12015-010-9167-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Stem cells have great potential for understanding early development, treating human disease, tissue trauma and early phase drug discovery. The factors that control the regulation of stem cell survival, proliferation, migration and differentiation are still emerging. Some evidence now exists demonstrating the potent effects of various G-protein coupled receptor (GPCR) ligands on the biology of stem cells. This review aims to give an overview of the current knowledge of the regulation of embryonic and somatic stem cell maintenance and differentiation by GPCR ligands.
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99
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Zhao A, Ohara-Imaizumi M, Brissova M, Benninger RK, Xu Y, Hao Y, Abramowitz J, Boulay G, Powers AC, Piston D, Jiang M, Nagamatsu S, Birnbaumer L, Gu G. Gαo represses insulin secretion by reducing vesicular docking in pancreatic beta-cells. Diabetes 2010; 59:2522-9. [PMID: 20622165 PMCID: PMC3279551 DOI: 10.2337/db09-1719] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Pertussis toxin uncoupling-based studies have shown that Gαi and Gαo can inhibit insulin secretion in pancreatic β-cells. Yet it is unclear whether Gαi and Gαo operate through identical mechanisms and how these G-protein-mediated signals inhibit insulin secretion in vivo. Our objective is to examine whether/how Gαo regulates islet development and insulin secretion in β-cells. RESEARCH DESIGN AND METHODS Immunoassays were used to analyze the Gαo expression in mouse pancreatic cells. Gαo was specifically inactivated in pancreatic progenitor cells by pancreatic cell-specific gene deletion. Hormone expression and insulin secretion in response to different stimuli were assayed in vivo and in vitro. Electron microscope and total internal reflection fluorescence-based assays were used to evaluate how Gαo regulates insulin vesicle docking and secretion in response to glucose stimulation. RESULTS Islet cells differentiate properly in Gαo(-/-) mutant mice. Gαo inactivation significantly enhances insulin secretion both in vivo and in isolation. Gαo nullizygous β-cells contain an increased number of insulin granules docked on the cell plasma membrane, although the total number of vesicles per β-cell remains unchanged. CONCLUSIONS Gαo is not required for endocrine islet cell differentiation, but it regulates the number of insulin vesicles docked on the β-cell membrane.
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Affiliation(s)
- Aizhen Zhao
- Program in Developmental Biology and Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Mica Ohara-Imaizumi
- Department of Biochemistry, Kyorin University School of Medicine Mitaka, Tokyo, Japan
| | - Marcella Brissova
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
- VA Tennessee Valley Healthcare System, Nashville, Tennessee
| | - Richard K.P. Benninger
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Yanwen Xu
- Program in Developmental Biology and Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Yuhan Hao
- Program in Developmental Biology and Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Joel Abramowitz
- Transmembrane Signaling Group, Laboratory of Neurobiology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina
| | - Guylain Boulay
- Department of Pharmacology, School of Medicine, Sherbrooke University, Sherbrooke, Québec, Canada
| | - Alvin C. Powers
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee
- Division of Diabetes, Endocrinology, and Metabolism, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee
- VA Tennessee Valley Healthcare System, Nashville, Tennessee
| | - David Piston
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Meisheng Jiang
- Department of Molecular and Medical Pharmacology, University of California, Los Angeles, Los Angeles, California
| | - Shinya Nagamatsu
- Department of Biochemistry, Kyorin University School of Medicine Mitaka, Tokyo, Japan
| | - Lutz Birnbaumer
- Transmembrane Signaling Group, Laboratory of Neurobiology, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina
| | - Guoqiang Gu
- Program in Developmental Biology and Department of Cell and Developmental Biology, Vanderbilt University Medical Center, Nashville, Tennessee
- Corresponding author: Guoqiang Gu,
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Panas HN, Lynch LJ, Vallender EJ, Xie Z, Chen GL, Lynn SK, Scanlan TS, Miller GM. Normal thermoregulatory responses to 3-iodothyronamine, trace amines and amphetamine-like psychostimulants in trace amine associated receptor 1 knockout mice. J Neurosci Res 2010; 88:1962-9. [PMID: 20155805 DOI: 10.1002/jnr.22367] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
3-Iodothyronamine (T1AM) is a metabolite of thyroid hormone. It is an agonist at trace amine-associated receptor 1 (TAAR1), a recently identified receptor involved in monoaminergic regulation and a potential novel therapeutic target. Here, T1AM was studied using rhesus monkey TAAR1 and/or human dopamine transporter (DAT) co-transfected cells, and wild-type (WT) and TAAR1 knock-out (KO) mice. The IC(50) of T1AM competition for binding of the DAT-specific radio-ligand [(3)H]CFT was highly similar in DAT cells, WT striatal synaptosomes and KO striatal synaptosomes (0.72-0.81 microM). T1AM inhibition of 10 nM [(3)H]dopamine uptake (IC(50): WT, 1.4 + or - 0.5 microM; KO, 1.2 + or - 0.4 microM) or 50 nM [(3)H]serotonin uptake (IC(50): WT, 4.5 + or - 0.6 microM; KO, 4.7 + or - 1.1 microM) in WT and KO synaptosomes was also highly similar. Unlike other TAAR1 agonists that are DAT substrates, TAAR1 signaling in response to T1AM was not enhanced in the presence of DAT as determined by CRE-luciferase assay. In vivo, T1AM induced robust hypothermia in WT and KO mice equivalently and dose dependently (maximum change degrees Celsius: 50 mg/kg at 60 min: WT -6.0 + or - 0.4, KO -5.6 + or - 1.0; and 25 mg/kg at 30 min: WT -2.7 + or - 0.4, KO -3.0 + or - 0.2). Other TAAR1 agonists including beta-phenylethylamine (beta-PEA), MDMA (3,4-methylenedioxymethamphetamine) and methamphetamine also induced significant, time-dependent thermoregulatory responses that were alike in WT and KO mice. Therefore, TAAR1 co-expression does not alter T1AM binding to DAT in vitro nor T1AM inhibition of [(3)H]monoamine uptake ex vivo, and TAAR1 agonist-induced thermoregulatory responses are TAAR1-independent. Accordingly, TAAR1-directed compounds will likely not affect thermoregulation nor are they likely to be cryogens.
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Affiliation(s)
- Helen N Panas
- Division of Neuroscience, Harvard Medical School/NEPRC, Southborough, MA, USA
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