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Mühlhaus J, Dinter J, Jyrch S, Teumer A, Jacobi SF, Homuth G, Kühnen P, Wiegand S, Grüters A, Völzke H, Raile K, Kleinau G, Krude H, Biebermann H. Investigation of Naturally Occurring Single-Nucleotide Variants in Human TAAR1. Front Pharmacol 2017; 8:807. [PMID: 29225575 PMCID: PMC5705543 DOI: 10.3389/fphar.2017.00807] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 10/25/2017] [Indexed: 11/21/2022] Open
Abstract
Activation of trace amine-associated receptor 1 (TAAR1) in endocrine pancreas is involved in weight regulation and glucose homeostasis. The purpose of this study was the identification and characterization of potential TAAR1 variants in patients with overweight/obesity and disturbed glucose homeostasis. Screening for TAAR1 variants was performed in 314 obese or overweight patients with impaired insulin secretion. The detected variants were functionally characterized concerning TAAR1 cell surface expression and signaling properties and their allele frequencies were determined in the population-based Study of Health in Pomerania (SHIP). Three heterozygous carriers of the single nucleotide missense variants p.Arg23Cys (R23C, rs8192618), p.Ser49Leu (S49L, rs140960896), and p.Ille171Leu (I171L, rs200795344) were detected in the patient cohort. While p.Ser49Leu and p.Ille171Leu were found in obese/overweight patients with slightly impaired glucose homeostasis, p.Arg23Cys was identified in a patient with a complete loss of insulin production. Functional in vitro characterization revealed a like wild-type function for I171L, partial loss of function for S49L and a complete loss of function for R23C. The frequency of the R23C variant in 2018 non-diabetic control individuals aged 60 years and older in the general population-based SHIP cohort was lower than in the analyzed patient sample. Both variants are rare in the general population indicating a recent origin in the general gene pool and/or the consequence of pronounced purifying selection, in line with the obvious detrimental effect of the mutations. In conclusion, our study provides hints for the existence of naturally occurring TAAR1 variants with potential relevance for weight regulation and glucose homeostasis.
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Affiliation(s)
- Jessica Mühlhaus
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universitt zu Berlin, Berlin, Germany
| | - Juliane Dinter
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universitt zu Berlin, Berlin, Germany
| | - Sabine Jyrch
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universitt zu Berlin, Berlin, Germany
| | - Alexander Teumer
- Institute for Community Medicine, University Medicine Greifswald, Greifswald, Germany
| | - Simon F Jacobi
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universitt zu Berlin, Berlin, Germany
| | - Georg Homuth
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, University of Greifswald, Greifswald, Germany
| | - Peter Kühnen
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universitt zu Berlin, Berlin, Germany
| | - Susanna Wiegand
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universitt zu Berlin, Berlin, Germany
| | - Annette Grüters
- Department for Pediatric Endocrinology and Diabetology, Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Henry Völzke
- Institute for Community Medicine, University Medicine Greifswald, Greifswald, Germany.,German Center for Diabetes Research (DZD), Greifswald, Germany
| | - Klemens Raile
- Department for Pediatric Endocrinology and Diabetology, Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany.,Experimental and Clinical Research Center (ECRC), Charité - Universitätsmedizin Berlin, Max Delbrück Center for Molecular Medicine (HZ), Berlin, Germany
| | - Gunnar Kleinau
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universitt zu Berlin, Berlin, Germany.,Institut für Medizinische Physik und Biophysik, Group Protein X-ray Crystallography and Signal Transduction, Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Heiko Krude
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universitt zu Berlin, Berlin, Germany
| | - Heike Biebermann
- Institute of Experimental Pediatric Endocrinology, Charité - Universitätsmedizin Berlin, Freie Universität Berlin, Humboldt-Universitt zu Berlin, Berlin, Germany
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Dinter J, Khajavi N, Mühlhaus J, Wienchol CL, Cöster M, Hermsdorf T, Stäubert C, Köhrle J, Schöneberg T, Kleinau G, Mergler S, Biebermann H. The Multitarget Ligand 3-Iodothyronamine Modulates β-Adrenergic Receptor 2 Signaling. Eur Thyroid J 2015; 4:21-9. [PMID: 26601070 PMCID: PMC4640289 DOI: 10.1159/000381801] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 03/19/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND 3-Iodothyronamine (3-T1AM), a signaling molecule with structural similarities to thyroid hormones, induces numerous physiological responses including reversible body temperature decline. One target of 3-T1AM is the trace amine-associated receptor 1 (TAAR1), which is a member of the rhodopsin-like family of G protein-coupled receptors (GPCRs). Interestingly, the effects of 3-T1AM remain detectable in TAAR1 knockout mice, suggesting further targets for 3-T1AM such as adrenergic receptors. Therefore, we evaluated whether β-adrenergic receptor 1 (ADRB1) and 2 (ADRB2) signaling is affected by 3-T1AM in HEK293 cells and in human conjunctival epithelial cells (IOBA-NHC), where these receptors are highly expressed endogenously. METHODS A label-free EPIC system for prescreening the 3-T1AM-induced effects on ADRB1 and ADRB2 in transfected HEK293 cells was used. In addition, ADRB1 and ADRB2 activation was analyzed using a cyclic AMP assay and a MAPK reporter gene assay. Finally, fluorescence Ca(2+) imaging was utilized to delineate 3-T1AM-induced Ca(2+) signaling. RESULTS 3-T1AM (10(-5)-10(-10)M) enhanced isoprenaline-induced ADRB2-mediated Gs signaling but not that of ADRB1-mediated signaling. MAPK signaling remained unaffected for both receptors. In IOBA-NHC cells, norepinephrine-induced Ca(2+) influxes were blocked by the nonselective ADRB blocker timolol (10 µM), indicating that ADRBs are most likely linked with Ca(2+) channels. Notably, timolol was also found to block 3-T1AM (10(-5)M)-induced Ca(2+) influx. CONCLUSIONS The presented data support that 3-T1AM directly modulates β-adrenergic receptor signaling. The relationship between 3-T1AM and β-adrenergic signaling also reveals a potential therapeutic value for suppressing Ca(2+) channel-mediated inflammation processes, occurring in eye diseases such as conjunctivitis.
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Affiliation(s)
- Juliane Dinter
- Institut für Experimentelle Pädiatrische Endokrinologie, Berlin, Germany
| | - Noushafarin Khajavi
- Department of Ophthalmology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Jessica Mühlhaus
- Institut für Experimentelle Pädiatrische Endokrinologie, Berlin, Germany
| | | | - Maxi Cöster
- Institut für Biochemie, Molekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, Germany
| | - Thomas Hermsdorf
- Institut für Biochemie, Molekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, Germany
| | - Claudia Stäubert
- Institut für Biochemie, Molekulare Biochemie, Medizinische Fakultät, University of Leipzig, Leipzig, 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
| | - Gunnar Kleinau
- Institut für Experimentelle Pädiatrische Endokrinologie, Berlin, Germany
| | - Stefan Mergler
- Department of Ophthalmology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Heike Biebermann
- Institut für Experimentelle Pädiatrische Endokrinologie, Berlin, Germany
- *Heike Biebermann, Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, DE-13353 Berlin (Germany), E-Mail , Stefan Mergler, Department of Ophthalmology, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, DE-13353 Berlin (Germany), E-Mail
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Dinter J, Mühlhaus J, Jacobi S, Wienchol CL, Cöster M, Meister J, Höfig C, Müller A, Köhrle J, Grüters A, Krude H, Mittag J, Schöneberg T, Kleinau G, Biebermann H. New G protein coupled receptor targets for 3-iodotyronamine. Exp Clin Endocrinol Diabetes 2015. [DOI: 10.1055/s-0035-1547778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Mühlhaus J, Dinter J, Nürnberg D, Rehders M, Depke M, Golchert J, Homuth G, Yi CX, Morin S, Köhrle J, Brix K, Tschöp M, Kleinau G, Biebermann H. Analysis of human TAAR8 and murine Taar8b mediated signaling pathways and expression profile. Int J Mol Sci 2014; 15:20638-55. [PMID: 25391046 PMCID: PMC4264187 DOI: 10.3390/ijms151120638] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Revised: 10/25/2014] [Accepted: 11/04/2014] [Indexed: 12/04/2022] Open
Abstract
The thyroid hormone derivative 3-iodothyronamine (3-T1AM) exerts metabolic effects in vivo that contradict known effects of thyroid hormones. 3-T1AM acts as a trace amine-associated receptor 1 (TAAR1) agonist and activates Gs signaling in vitro. Interestingly, 3-T1AM-meditated in vivo effects persist in Taar1 knockout-mice indicating that further targets of 3-T1AM might exist. Here, we investigated another member of the TAAR family, the only scarcely studied mouse and human trace-amine-associated receptor 8 (Taar8b, TAAR8). By RT-qPCR and locked-nucleic-acid (LNA) in situ hybridization, Taar8b expression in different mouse tissues was analyzed. Functionally, we characterized TAAR8 and Taar8b with regard to cell surface expression and signaling via different G-protein-mediated pathways. Cell surface expression was verified by ELISA, and cAMP accumulation was quantified by AlphaScreen for detection of Gs and/or Gi/o signaling. Activation of G-proteins Gq/11 and G12/13 was analyzed by reporter gene assays. Expression analyses revealed at most marginal Taar8b expression and no gender differences for almost all analyzed tissues. In heart, LNA-in situ hybridization demonstrated the absence of Taar8b expression. We could not identify 3-T1AM as a ligand for TAAR8 and Taar8b, but both receptors were characterized by a basal Gi/o signaling activity, a so far unknown signaling pathway for TAARs.
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Affiliation(s)
- Jessica Mühlhaus
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany.
| | - Juliane Dinter
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany.
| | - Daniela Nürnberg
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany.
| | - Maren Rehders
- School of Engineering and Science, Research Center MOLIFE-Molecular Life Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany.
| | - Maren Depke
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine and Ernst-Moritz-Arndt-University Greifswald, Fr iedrich-Ludwig-Jahn-Str. 15a, 17487 Greifswald, Germany.
| | - Janine Golchert
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine and Ernst-Moritz-Arndt-University Greifswald, Fr iedrich-Ludwig-Jahn-Str. 15a, 17487 Greifswald, Germany.
| | - Georg Homuth
- Interfaculty Institute for Genetics and Functional Genomics, University Medicine and Ernst-Moritz-Arndt-University Greifswald, Fr iedrich-Ludwig-Jahn-Str. 15a, 17487 Greifswald, Germany.
| | - Chun-Xia Yi
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute for Diabetes and Obesity, Business Campus Garching, Parkring 13, 85748 Garching, Germany.
| | - Silke Morin
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute for Diabetes and Obesity, Business Campus Garching, Parkring 13, 85748 Garching, Germany.
| | - Josef Köhrle
- Institut für Experimentelle Endokrinologie, Charité-Universitätsmedizin Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany.
| | - Klaudia Brix
- School of Engineering and Science, Research Center MOLIFE-Molecular Life Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen, Germany.
| | - Matthias Tschöp
- Helmholtz Zentrum München, German Research Center for Environmental Health, Institute for Diabetes and Obesity, Business Campus Garching, Parkring 13, 85748 Garching, Germany.
| | - Gunnar Kleinau
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany.
| | - Heike Biebermann
- Institut für Experimentelle Pädiatrische Endokrinologie, Charité-Universitätsmedizin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany.
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Mühlhaus J, Dinter J, Piechowski CL, Müller A, Nürnberg D, Grüters A, Köhrle J, Yi CX, Tschöp M, Krude H, Kleinau G, Biebermann H. Aspects of 3-iodothyronamine (3T1AM) induced signaling by human and mouse trace amine-associated receptor 5 (TAAR5). Exp Clin Endocrinol Diabetes 2014. [DOI: 10.1055/s-0034-1372013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Mühlhaus J, Pütter C, Brumm H, Grallert H, Illig T, Scherag S, Reinehr T, Pott W, Albayrak Ö, Wang HJ, Bau AM, Wiegand S, Grüters A, Krude H, Hebebrand J, Hinney A, Biebermann H, Scherag A. Do common variants separate between obese melanocortin-4 receptor gene mutation carriers and non-carriers? The impact of cryptic relatedness. Horm Res Paediatr 2013; 77:358-68. [PMID: 22688572 DOI: 10.1159/000338999] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 04/23/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Genome-wide association studies revealed associations of single nucleotide polymorphisms (SNPs) flanking MC4R with body mass index variability and obesity. We genotyped 28 SNPs, covering MC4R, and searched for haplotypes discriminating between obese mutation carriers and non-carriers. METHODS We analyzed all three-marker haplotype combinations of the 28 SNPs to discriminate between obese mutation carriers and non-carriers - overall and in functional categories for 25 different MC4R mutations: (a) 'like wild type', (b) 'partial loss of function', and (c) 'complete loss of function'. We checked for the possible impact of 'cryptic relatedness' by sensitivity analyses including only 1 randomly selected patient per mutation. RESULTS Overall analyses revealed a haplotype of 3 SNPs downstream of the MC4R discriminating between obese mutation carriers and obese non-carriers. However, sensitivity analyses showed that the finding is most likely due to cryptic relatedness. CONCLUSION Given a mutation prevalence of 1-5%, the sample size of 62 obese mutation carriers with overall 25 different MC4R mutations represents a unique feature of our study. Taking MC4R as an example, we demonstrate the impact of cryptic relatedness when trying to link non-coding SNPs to functionally relevant mutations. Hence, a thorough mutation screen can currently not be guided by SNP genotyping.
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Affiliation(s)
- Jessica Mühlhaus
- Institute of Experimental Pediatric Endocrinology, Charité Campus Virchow-Klinikum, Berlin, Germany
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Piechowski CL, Rediger A, Lagemann C, Mühlhaus J, Müller A, Pratzka J, Tarnow P, Grüters A, Krude H, Kleinau G, Biebermann H. Inhibition of melanocortin-4 receptor dimerization by substitutions in intracellular loop 2. J Mol Endocrinol 2013; 51:109-18. [PMID: 23674133 DOI: 10.1530/jme-13-0061] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Obesity is one of the most challenging global health problems. One key player in energy homeostasis is the melanocortin-4 receptor (MC4R), which is a family A G-protein-coupled receptor (GPCR). It has recently been shown that MC4R has the capacity to form homo- or heterodimers. Dimerization of GPCRs is of great importance for signaling regulation, with major pharmacological implications. Unfortunately, not enough is yet known about the detailed structural properties of MC4R dimers or the functional consequences of receptor dimerization. Our goal, therefore, was to explore specific properties related to MC4R dimerization. First, we aimed to induce the dissociation of dimers to monomers and to compare the functional parameters of wild-type and MC4R variants. To inhibit homodimerization, we designed MC4R chimeras with the cannabinoid-1 receptor, a receptor that does not interact with MC4R. Indeed, we identified several substitutions in the intracellular loop 2 (ICL2) and adjacent regions of transmembrane helix 3 (TMH3) and TMH4 that lead to partial dimer dissociation. Interestingly, the capacity for signaling activity was generally increased in these MC4R variants, although receptor expression remained unchanged. This increase in activity for dissociated receptors might indicate a link between receptor dimerization and signaling capacity. Moreover, dimer dissociation was also observed in a naturally occurring activating MC4R mutation in ICL2. Taken together, this study provides new information on the structural prerequisites for MC4R dimerization and identifies an approach to induce the dissociation of MC4R dimers. This might be useful for further investigation of pharmacological properties.
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Affiliation(s)
- Carolin L Piechowski
- Institute of Experimental Pediatric Endocrinology, Charité-Universitätsmedizin Berlin, Humboldt-Universität zu Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
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Brumm H, Mühlhaus J, Bolze F, Scherag S, Hinney A, Hebebrand J, Wiegand S, Klingenspor M, Grüters A, Krude H, Biebermann H. Rescue of melanocortin 4 receptor (MC4R) nonsense mutations by aminoglycoside-mediated read-through. Obesity (Silver Spring) 2012; 20:1074-81. [PMID: 21738238 DOI: 10.1038/oby.2011.202] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Aminoglycoside-mediated read-through of stop codons was recently demonstrated for a variety of diseases in vitro and in vivo. About 30 percent of human genetic diseases are the consequence of nonsense mutations. Nonsense mutations in obesity-associated genes like the melanocortin 4 receptor (MC4R), expressed in the hypothalamus, show the impact of premature stop codons on energy homeostasis. Therefore, the MC4R could be a potential pharmaceutical target for obesity treatment and targeting MC4R stop mutations could serve as proof of principle for nonsense mutations in genes expressed in the brain. We investigated four naturally occurring nonsense mutations in the MC4R (W16X, Y35X, E61X, Q307X) located at different positions in the receptor for aminoglycoside-mediated functional rescue in vitro. We determined localization and amount of full-length protein before and after aminoglycoside treatment by fluorescence microscopy, cell surface and total enzyme linked immunosorbent assay (ELISA). Signal transduction properties were analyzed by cyclic adenosine monophosphate (cAMP) assays after transient transfection of MC4R wild type and mutant receptors into COS-7 cells. Functional rescue of stop mutations in the MC4R is dependent on: (i) triplet sequence of the stop codon, (ii) surrounding sequence, (iii) location within the receptor, (iv) applied aminoglycoside and ligand. Functional rescue was possible for W16X, Y35X (N-terminus), less successful for Q307X (C-terminus) and barely feasible for E61X (first transmembrane domain). Restoration of full-length proteins by PTC124 could not be confirmed. Future pharmaceutical applications must consider the potency of aminoglycosides to restore receptor function as well as the ability to pass the blood-brain barrier.
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MESH Headings
- Aminoglycosides/pharmacology
- Blood-Brain Barrier
- Codon, Nonsense/drug effects
- Codon, Nonsense/genetics
- Codon, Terminator/drug effects
- Codon, Terminator/genetics
- Energy Metabolism/drug effects
- Energy Metabolism/genetics
- Female
- Humans
- Male
- Obesity/blood
- Obesity/drug therapy
- Obesity/genetics
- Oxadiazoles/pharmacology
- Receptor, Melanocortin, Type 4/drug effects
- Receptor, Melanocortin, Type 4/genetics
- Receptor, Melanocortin, Type 4/metabolism
- Signal Transduction/drug effects
- Signal Transduction/genetics
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Affiliation(s)
- Harald Brumm
- Institute of Experimental Pediatric Endocrinology, Charité Universitätsmedizin Berlin, Berlin, Germany
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