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T1AM Attenuates the Hypoxia/Reoxygenation-Induced Necroptosis of H9C2 Cardiomyocytes via RIPK1/RIPK3 Pathway. BIOMED RESEARCH INTERNATIONAL 2022; 2022:4833791. [PMID: 35265713 PMCID: PMC8901330 DOI: 10.1155/2022/4833791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 01/26/2022] [Indexed: 11/19/2022]
Abstract
Purpose To investigate the detailed mechanism of 3-iodothyronamine (T1AM) in cell apoptosis and programmed necrosis of hypoxia/reoxygenation- (H/R-) induced H9C2 injury. Materials and Methods Cardiomyocyte H9C2 cells were cultured in vitro for the establishment of cardiomyocyte H/R models. Cells were randomly divided into four groups: the control group, H/R group, T1AM pretreatment group, T1AM pretreatment and H/R (6 μm T1AM+H/R) group. The degree of myocardial injury was determined by the detection of the cardiomyocyte inhibition rate by CCK8 and the detection of lactic dehydrogenase (LDH) activity. Cell apoptosis was assessed through TUNEL assay and flow cytometry analysis. The protein level and mRNA level of RIPK1, RIPK3, and CAMKII were detected by western blotting and qRT-PCR. Results Compared with the control group, the cell inhibition rate was dramatically elevated in the H/R group. LDH release of cardiomyocytes was significantly increased. Protein and mRNA expressions of RIPK1, RIPK3, and CAMKII were significantly enhanced. Compared with the H/R group, the cell inhibition rate, LDH release, cardiomyocyte necroptosis rate, and protein and mRNA levels of RIPK1, RIPK3, and CAMKII of the T1AM+H/R group were significantly decreased. Conclusion Pretreatment with T1AM could alleviate cardiomyocytes' H/R injury and inhibit necroptosis of cardiomyocytes, which might exert a protective function upon activation of the RIPK1/RIPK3 pathway.
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Biebermann H, Kleinau G. 3-Iodothyronamine Induces Diverse Signaling Effects at Different Aminergic and Non-Aminergic G-Protein Coupled Receptors. Exp Clin Endocrinol Diabetes 2019; 128:395-400. [PMID: 31698479 DOI: 10.1055/a-1022-1554] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The thyroid hormone metabolite 3-iodothyronamine (3-T1AM) exerts diverse physiological reactions such as a decrease of body temperature, and negative inotropic and chronotropic effects. This observed pleomorphic effect in physiology can be barely explained by interaction with only one target protein such as the trace-amine receptor 1 (TAAR1), a class A G-protein coupled receptor (GPCR). Moreover, Taar1 knock-out mice still react to 3-T1AM through physiological responses with a rapid decrease in body temperature. These facts propelled our group and others to search for further targets for this molecule.The group of TAARs evolved early in evolution and, according to sequence similarities, they are closely related to adrenoceptors and other aminergic receptors. Therefore, several of these receptors were characterized by their potential to interplay with 3-T1AM. Indeed, 3-T1AM acts as a positive allosteric modulator on the beta2-adrenoceptor (ADRB2) and as a biased agonist on the serotonin receptor 1B (5HT1b) and the alpha2-adrenoceptor (ADRA2A). In addition, 3-T1AM was reported to be a weak antagonist at a non-aminergic muscarinic receptor (M3).These findings impressively reflect that such trace amines can unselectively and simultaneously function at different receptors expressed by one cell or at different tissues. In conclusion, the role of 3-T1AM is hypothesized to concert the fine-tuning of specific cell reactions by the accentuation of certain pathways dependent on distinct receptors. 3-T1AM acts as a regulator of signals by blocking, modulating, or inducing simultaneously distinct intracellular signaling cascades via different GPCRs.
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Affiliation(s)
- Heike Biebermann
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Gunnar Kleinau
- Institute of Medical Physics and Biophysics, Group Protein X-ray Crystallography and Signal Transduction, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
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Minimal Age-Related Alterations in Behavioral and Hematological Parameters in Trace Amine-Associated Receptor 1 (TAAR1) Knockout Mice. Cell Mol Neurobiol 2019; 40:273-282. [PMID: 31399838 DOI: 10.1007/s10571-019-00721-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 08/04/2019] [Indexed: 10/26/2022]
Abstract
Since the discovery in 2001, the G protein-coupled trace amine-associated receptor 1 (TAAR1) has become an important focus of research targeted on evaluation of its role in the central nervous system (CNS). Meanwhile, impact of TAAR1 in the peripheral organs is less investigated. Expression of TAAR1 was demonstrated in different peripheral tissues: pancreatic β-cells, stomach, intestines, white blood cells (WBC), and thyroid. However, the role of TAAR1 in regulation of hematological parameters has not been investigated yet. In this study, we performed analysis of anxiety-related behaviors, a complete blood count (CBC), erythrocyte fragility, as well as FT3/FT4 thyroid hormones levels in adult and middle-aged TAAR1 knockout mice. Complete blood count analysis was performed on a Siemens Advia 2120i hematology analyzer and included more than 35 measured and calculated parameters. Erythrocyte fragility test evaluated spherocytosis pathologies of red blood cells (RBC). No significant alterations in essentially all these parameters were found in mice without TAAR1. However, comparative aging analysis has revealed a decreased neutrophils level in the middle-aged TAAR1 knockout mouse group. Minimal alterations in these parameters observed in TAAR1 knockout mice suggest that future TAAR1-based therapies should exert little hematological effect and thus will likely have a good safety profile.
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Abstract
Trace amines are endogenous compounds classically regarded as comprising β-phenylethyalmine, p-tyramine, tryptamine, p-octopamine, and some of their metabolites. They are also abundant in common foodstuffs and can be produced and degraded by the constitutive microbiota. The ability to use trace amines has arisen at least twice during evolution, with distinct receptor families present in invertebrates and vertebrates. The term "trace amine" was coined to reflect the low tissue levels in mammals; however, invertebrates have relatively high levels where they function like mammalian adrenergic systems, involved in "fight-or-flight" responses. Vertebrates express a family of receptors termed trace amine-associated receptors (TAARs). Humans possess six functional isoforms (TAAR1, TAAR2, TAAR5, TAAR6, TAAR8, and TAAR9), whereas some fish species express over 100. With the exception of TAAR1, TAARs are expressed in olfactory epithelium neurons, where they detect diverse ethological signals including predators, spoiled food, migratory cues, and pheromones. Outside the olfactory system, TAAR1 is the most thoroughly studied and has both central and peripheral roles. In the brain, TAAR1 acts as a rheostat of dopaminergic, glutamatergic, and serotonergic neurotransmission and has been identified as a novel therapeutic target for schizophrenia, depression, and addiction. In the periphery, TAAR1 regulates nutrient-induced hormone secretion, suggesting its potential as a novel therapeutic target for diabetes and obesity. TAAR1 may also regulate immune responses by regulating leukocyte differentiation and activation. This article provides a comprehensive review of the current state of knowledge of the evolution, physiologic functions, pharmacology, molecular mechanisms, and therapeutic potential of trace amines and their receptors in vertebrates and invertebrates.
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Affiliation(s)
- Raul R Gainetdinov
- Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia (R.R.G.); Skolkovo Institute of Science and Technology (Skoltech), Moscow, Russia (R.R.G.); Neuroscience, Ophthalmology, and Rare Diseases Discovery and Translational Area, pRED, Roche Innovation Centre Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland (M.C.H.); and Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada (M.D.B.)
| | - Marius C Hoener
- Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia (R.R.G.); Skolkovo Institute of Science and Technology (Skoltech), Moscow, Russia (R.R.G.); Neuroscience, Ophthalmology, and Rare Diseases Discovery and Translational Area, pRED, Roche Innovation Centre Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland (M.C.H.); and Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada (M.D.B.)
| | - Mark D Berry
- Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia (R.R.G.); Skolkovo Institute of Science and Technology (Skoltech), Moscow, Russia (R.R.G.); Neuroscience, Ophthalmology, and Rare Diseases Discovery and Translational Area, pRED, Roche Innovation Centre Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland (M.C.H.); and Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada (M.D.B.)
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Chiellini G, Bellusci L, Sabatini M, Zucchi R. Thyronamines and Analogues - The Route from Rediscovery to Translational Research on Thyronergic Amines. Mol Cell Endocrinol 2017; 458:149-155. [PMID: 28069535 DOI: 10.1016/j.mce.2017.01.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Revised: 12/07/2016] [Accepted: 01/02/2017] [Indexed: 11/18/2022]
Abstract
Thyronamines are a novel class of endogenous signaling compounds, structurally related to thyroid hormones (THs). Specific thyronamines, particularly 3-iodothyronamine (T1AM), stimulate with nanomolar affinity trace amine-associated receptor 1 (TAAR1), a G protein-coupled membrane receptor, and may also interact with other TAAR subtypes (particularly TAAR5), adrenergic receptors (particularly α2 receptors), amine transporters, and mitochondrial proteins. In addition to its structural similarities with THs, T1AM also contains the arylethylamine scaffold as in monoamine neurotransmitters, implicating an intriguing role for T1AM as both a neuromodulator and a hormone-like molecule constituting a part of thyroid hormone signaling. A large number of T1AM derivatives have already been synthesized. We discuss the different chemical strategies followed to obtain thyronamine analogues, their potency at TAAR1, and their structure-activity relationship. Preliminary characterization of the functional effects of these synthetic compounds is also provided.
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Duntas LH. Predictions on the Role of Thyronamines in the Setting of The Oracle of Delphi. Thyroid 2016; 26:1653-1655. [PMID: 27852155 DOI: 10.1089/thy.2016.0560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Leonidas H Duntas
- Unit of Endocrinology, Diabetes and Metabolism, Evgenideion Hospital, University of Athens , Athens, Greece
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7
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Hoefig CS, Zucchi R, Köhrle J. Thyronamines and Derivatives: Physiological Relevance, Pharmacological Actions, and Future Research Directions. Thyroid 2016; 26:1656-1673. [PMID: 27650974 DOI: 10.1089/thy.2016.0178] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Thyronamines (3-T1AM, T0AM) are endogenous compounds probably derived from L-thyroxine or its intermediate metabolites. Combined activities of intestinal deiodinases and ornithine decarboxylase generate 3-T1AM in vitro. Alternatively, 3-T1AM might be formed by the thyroid gland and secreted into the blood. 3-T1AM and T0AM concentrations have been determined by liquid chromatography-tandem mass spectrometry analysis (LC-MS/MS) in tissues, serum, and cell lines. However, large variations of 3-T1AM concentrations in human serum were reported by LC-MS/MS compared with a monoclonal antibody-based immunoassay. These differences might be caused by strong binding of the highly hydrophobic 3-T1AM to apolipoprotein B100. Pharmacological administration of 3-T1AM results in dose-dependent reversible effects on body temperature, cardiac function, energy metabolism, and neurological functions. The physiological relevance of these actions is unclear, but may occur at tissue concentrations close to the estimated endogenous concentrations of 3-T1AM or its metabolites T0AM or thyroacetic acid (TA1). A number of putative receptors, binding sites, and cellular target molecules mediating actions of the multi-target ligand 3-T1AM have been proposed. Among those are members of the trace amine associated receptor family, the adrenergic receptor ADRα2a, and the thermosensitive transient receptor potential melastatin 8 channel. Preclinical studies employing various animal experimental models are in progress, and more stable receptor-selective agonistic and antagonistic analogues of 3-T1AM are now available for testing. The potent endogenous thyroid hormone-derived biogenic amine 3-T1AM exerts marked cryogenic, metabolic, cardiac and central actions and represents a valuable lead compound linking endocrine, metabolic, and neuroscience research to advance development of new drugs.
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Affiliation(s)
- Carolin Stephanie Hoefig
- 1 Institut für Experimentelle Endokrinologie Charité, Universitätsmedizin Berlin , Berlin, Germany
| | - Riccardo Zucchi
- 2 Laboratory of Biochemistry, Department of Pathology, University of Pisa , Pisa, Italy
| | - Josef Köhrle
- 1 Institut für Experimentelle Endokrinologie Charité, Universitätsmedizin Berlin , Berlin, Germany
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Hoefig CS, Jacobi SF, Warner A, Harder L, Schanze N, Vennström B, Mittag J. 3-Iodothyroacetic acid lacks thermoregulatory and cardiovascular effects in vivo. Br J Pharmacol 2015; 172:3426-33. [PMID: 25765843 DOI: 10.1111/bph.13131] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Revised: 01/20/2015] [Accepted: 03/10/2015] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND AND PURPOSE 3-Iodothyronamine (3-T1 AM) is an endogenous thyroid hormone derivative reported to induce strong hypothermia and bradycardia within minutes upon injection in rodents. Although 3-T1 AM is rapidly converted to several other metabolites in vivo, these strong pharmacological responses were solely attributed to 3-T1 AM, leaving potential contributions of downstream products untested. We therefore examined the cardiometabolic effects of 3-iodothyroacetic acid (TA1 ), the main degradation product of 3-T1 AM. EXPERIMENTAL APPROACH We used a sensitive implantable radiotelemetry system in C57/Bl6J mice to study the effects of TA1 on body temperature and heart rate, as well as other metabolic parameters. KEY RESULTS Interestingly, despite using pharmacological TA1 doses, we observed no effects on heart rate or body temperature after a single TA1 injection (50 mg·kg(-1) , i.p.) compared to sham-injected controls. Repeated administration of TA1 (5 mg·kg(-1) , i.p. for 7 days) likewise did not alter body weight, food and water intake, heart rate, blood pressure, brown adipose tissue (BAT) thermogenesis or body temperature. Moreover, mRNA expression of tissue specific genes in heart, kidney, liver, BAT and lung was also not altered by TA1 compared to sham-injected controls. CONCLUSIONS AND IMPLICATIONS Our data therefore conclusively demonstrate that TA1 does not contribute to the cardiovascular or thermoregulatory effects observed after 3-T1 AM administration in mice, suggesting that the oxidative deamination constitutes an important deactivation mechanism for 3-T1 AM with possible implications for cardiovascular and thermoregulatory functions.
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Affiliation(s)
- Carolin S Hoefig
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Simon F Jacobi
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Amy Warner
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Lisbeth Harder
- Center of Brain Behavior and Metabolism CBBM/Medizinische Klinik I, University of Lübeck, Lübeck, Germany
| | - Nancy Schanze
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Björn Vennström
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Jens Mittag
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden.,Center of Brain Behavior and Metabolism CBBM/Medizinische Klinik I, University of Lübeck, Lübeck, Germany
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TAAR1 transforms thinking about a plant alkaloid that transformed the practice of medicine. Int J Neuropsychopharmacol 2014; 17:1545-7. [PMID: 24901712 DOI: 10.1017/s1461145714000911] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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10
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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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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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Differential modulation of Beta-adrenergic receptor signaling by trace amine-associated receptor 1 agonists. PLoS One 2011; 6:e27073. [PMID: 22073124 PMCID: PMC3205048 DOI: 10.1371/journal.pone.0027073] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Accepted: 10/09/2011] [Indexed: 11/19/2022] Open
Abstract
Trace amine-associated receptors (TAAR) are rhodopsin-like G-protein-coupled receptors (GPCR). TAAR are involved in modulation of neuronal, cardiac and vascular functions and they are potentially linked with neurological disorders like schizophrenia and Parkinson's disease. Subtype TAAR1, the best characterized TAAR so far, is promiscuous for a wide set of ligands and is activated by trace amines tyramine (TYR), phenylethylamine (PEA), octopamine (OA), but also by thyronamines, dopamine, and psycho-active drugs. Unfortunately, effects of trace amines on signaling of the two homologous β-adrenergic receptors 1 (ADRB1) and 2 (ADRB2) have not been clarified yet in detail. We, therefore, tested TAAR1 agonists TYR, PEA and OA regarding their effects on ADRB1/2 signaling by co-stimulation studies. Surprisingly, trace amines TYR and PEA are partial allosteric antagonists at ADRB1/2, whereas OA is a partial orthosteric ADRB2-antagonist and ADRB1-agonist. To specify molecular reasons for TAAR1 ligand promiscuity and for observed differences in signaling effects on particular aminergic receptors we compared TAAR, tyramine (TAR) octopamine (OAR), ADRB1/2 and dopamine receptors at the structural level. We found especially for TAAR1 that the remarkable ligand promiscuity is likely based on high amino acid similarity in the ligand-binding region compared with further aminergic receptors. On the other hand few TAAR specific properties in the ligand-binding site might determine differences in ligand-induced effects compared to ADRB1/2. Taken together, this study points to molecular details of TAAR1-ligand promiscuity and identified specific trace amines as allosteric or orthosteric ligands of particular β-adrenergic receptor subtypes.
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Abstract
Thyronamines (TAMs) are a newly identified class of endogenous signaling compounds. Their structure is identical to that of thyroid hormone and deiodinated thyroid hormone derivatives, except that TAMs do not possess a carboxylate group. Despite some initial publications dating back to the 1950s, TAMs did not develop into an independent area of research until 2004, when they were rediscovered as potential ligands to a class of G protein-coupled receptors called trace-amine associated receptors. Since this discovery, two representatives of TAMs, namely 3-iodothyronamine (3-T(1)AM) and thyronamine (T(0)AM), have been detected in vivo. Intraperitoneal or central injection of 3-T(1)AM or T(0)AM into mice, rats, or Djungarian hamsters caused various prompt effects, such as metabolic depression, hypothermia, negative chronotropy, negative inotropy, hyperglycemia, reduction of the respiratory quotient, ketonuria, and reduction of fat mass. Although their physiological function remains elusive, 3-T(1)AM and T(0)AM have already revealed promising therapeutic potential because they represent the only endogenous compounds inducing hypothermia as a prophylactic or acute treatment of stroke and might thus be expected to cause fewer side effects than synthetic compounds. This review article summarizes the still somewhat scattered data on TAMs obtained both recently and more than 20 yr ago to yield a complete and updated picture of the current state of TAM research.
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Affiliation(s)
- S Piehl
- Institut für Experimentelle Endokrinologie, Charité-Universitätsmedizin Berlin, Charité Campus Virchow-Klinikum (Südring 10), Augustenburger Platz 1, 13353 Berlin, Germany
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Tan ES, Naylor JC, Groban ES, Bunzow JR, Jacobson MP, Grandy DK, Scanlan TS. The molecular basis of species-specific ligand activation of trace amine-associated receptor 1 (TAAR(1)). ACS Chem Biol 2009; 4:209-20. [PMID: 19256523 PMCID: PMC2677188 DOI: 10.1021/cb800304d] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The trace amine-associated receptor 1 (TAAR(1)) is an aminergic G protein-coupled receptor (GPCR) potently activated by 3-iodothyronamine (1), an endogenous derivative of thyroid hormone. Structure-activity relationship studies on 1 and related agonists showed that the rat and mouse species of TAAR(1) accommodated structural modifications and functional groups on the ethylamine portion and the biaryl ether moiety of the molecule. However, the two receptors clearly exhibited distinct, species-specific ligand preferences despite being remarkably similar with 93% sequence similarity. In this study, we generated single and double mutants of rat and mouse TAAR(1) to probe the molecular recognition of agonists and the underlying basis for the ligand selectivity of rat and mouse TAAR(1). Key, nonconserved specificity determinant residues in transmembranes helices 4 and 7 within the ligand binding site appear to be the primary source of a number of the observed ligand preferences. Residue 7.39 in transmembrane 7 dictated the preference for a beta-phenyl ring, while residue 4.56 in transmembrane 4 was partially responsible for the lower potency of 1 and tyramine for the mouse receptor. Additionally, 1 and tyramine were found to have the same binding mode in rat TAAR(1) despite structure-activity relationship data suggesting the possibility of each molecule having different binding orientations. These findings provide valuable insights into the critical binding site residues involved in the ligand-receptor interaction that can influence compound selectivity and functional activity of aminergic GPCRs.
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Affiliation(s)
- Edwin S Tan
- Chemistry and Chemical Biology Graduate Program, University of California, San Francisco, San Francisco, California 94158, USA.
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