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Csaba Z, Dournaud P. Internalization of somatostatin receptors in brain and periphery. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2023; 196:43-57. [PMID: 36813365 DOI: 10.1016/bs.pmbts.2022.09.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Somatostatin (SRIF) is a neuropeptide that acts as an important regulator of both endocrine and exocrine secretion and modulates neurotransmission in the central nervous system (CNS). SRIF also regulates cell proliferation in normal tissues and tumors. The physiological actions of SRIF are mediated by a family of five G protein-coupled receptors, called somatostatin receptor (SST) SST1, SST2, SST3, SST4, SST5. These five receptors share similar molecular structure and signaling pathways but they display marked differences in their anatomical distribution, subcellular localization and intracellular trafficking. The SST subtypes are widely distributed in the CNS and peripheral nervous system, in many endocrine glands and tumors, particularly of neuroendocrine origin. In this review, we focus on the agonist-dependent internalization and recycling of the different SST subtypes in vivo in the CNS, peripheral organs and tumors. We also discuss the physiological, pathophysiological and potential therapeutic effects of the intracellular trafficking of SST subtypes.
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Affiliation(s)
- Zsolt Csaba
- Université Paris Cité, NeuroDiderot, Inserm UMR, Paris, France
| | - Pascal Dournaud
- Université Paris Cité, NeuroDiderot, Inserm UMR, Paris, France.
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2
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Nagarajan SK, Babu S, Kulkarni SA, Vadivelu A, Devaraju P, Sohn H, Madhavan T. Understanding the influence of lipid bilayers and ligand molecules in determining the conformational dynamics of somatostatin receptor 2. Sci Rep 2021. [PMID: 33828200 DOI: 10.1038/s41598‐021‐87422‐5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Somatostatin receptor 2 (SSTR2) is a G-protein coupled receptor (GPCR) that controls numerous cellular processes including cell-to-cell signaling. In this study, we report how the lipid and ligand molecules influence the conformational dynamics of the membrane-bound SSTR2. Molecular simulations of different holo and apoenzyme complexes of SSTR2 in the presence and absence of a lipid bilayer were performed, observed, and correlated with previously reported studies. We identified the important SSTR2 residues that take part in the formation of the SSTR2-ligand complex. On analyzing the molecular simulation trajectories, we identified that the residue D3.32 is crucial in determining the bioactive conformation of SSTR2 ligands in the binding site. Based on the results, we suggest that designing a novel SSTR2 ligand with an H-bond donor group at the R1 position, and hydrophobic groups at R2 and R3 might have higher activity and SSTR2-selectivity. We analyzed the simulated systems to identify other important structural features involved in SSTR2-ligand binding and to observe the different conformational changes that occur in the protein after the ligand binding. Additionally, we studied the conformational dynamics of N- and C-terminal regions of SSTR2 in the presence and absence of the lipid bilayer. Both the systems were compared to understand the influence of lipid molecules in the formation of secondary structural domains by these extracellular regions. The comparative study revealed that the secondary structural elements formed by C-terminal residues in presence of lipid molecules is crucial for the functioning of SSTR2. Our study results highlight the structural complexities involved in the functioning of SSTR upon binding with the ligands in the presence and absence of lipid bilayer, which is essential for designing novel drug targets.
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Affiliation(s)
- Santhosh Kumar Nagarajan
- Computational Biology Lab, Department of Genetic Engineering, School of Bioengineering, SRM Institute of Science and Technology, SRM Nagar, Kattankulathur, Chennai, 603203, India
| | - Sathya Babu
- Computational Biology Lab, Department of Genetic Engineering, School of Bioengineering, SRM Institute of Science and Technology, SRM Nagar, Kattankulathur, Chennai, 603203, India
| | - Seema A Kulkarni
- Department of Food and Process Engineering, School of Bioengineering, SRM Institute of Science and Technology, SRM Nagar, Kattankulathur, Chennai, 603203, India
| | - Aanand Vadivelu
- Computational Biology Lab, Department of Genetic Engineering, School of Bioengineering, SRM Institute of Science and Technology, SRM Nagar, Kattankulathur, Chennai, 603203, India
| | - Panneer Devaraju
- Unit of Vector Biology and Control, ICMR-Vector Control Research Centre, Indian Council of Medical Research (ICMR), Puducherry, India
| | - Honglae Sohn
- Department of Chemistry and Department of Carbon Materials, Chosun University, Gwangju, South Korea.
| | - Thirumurthy Madhavan
- Computational Biology Lab, Department of Genetic Engineering, School of Bioengineering, SRM Institute of Science and Technology, SRM Nagar, Kattankulathur, Chennai, 603203, India.
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3
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Understanding the influence of lipid bilayers and ligand molecules in determining the conformational dynamics of somatostatin receptor 2. Sci Rep 2021; 11:7677. [PMID: 33828200 PMCID: PMC8027056 DOI: 10.1038/s41598-021-87422-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 03/26/2021] [Indexed: 11/11/2022] Open
Abstract
Somatostatin receptor 2 (SSTR2) is a G-protein coupled receptor (GPCR) that controls numerous cellular processes including cell-to-cell signaling. In this study, we report how the lipid and ligand molecules influence the conformational dynamics of the membrane-bound SSTR2. Molecular simulations of different holo and apoenzyme complexes of SSTR2 in the presence and absence of a lipid bilayer were performed, observed, and correlated with previously reported studies. We identified the important SSTR2 residues that take part in the formation of the SSTR2-ligand complex. On analyzing the molecular simulation trajectories, we identified that the residue D3.32 is crucial in determining the bioactive conformation of SSTR2 ligands in the binding site. Based on the results, we suggest that designing a novel SSTR2 ligand with an H-bond donor group at the R1 position, and hydrophobic groups at R2 and R3 might have higher activity and SSTR2-selectivity. We analyzed the simulated systems to identify other important structural features involved in SSTR2-ligand binding and to observe the different conformational changes that occur in the protein after the ligand binding. Additionally, we studied the conformational dynamics of N- and C-terminal regions of SSTR2 in the presence and absence of the lipid bilayer. Both the systems were compared to understand the influence of lipid molecules in the formation of secondary structural domains by these extracellular regions. The comparative study revealed that the secondary structural elements formed by C-terminal residues in presence of lipid molecules is crucial for the functioning of SSTR2. Our study results highlight the structural complexities involved in the functioning of SSTR upon binding with the ligands in the presence and absence of lipid bilayer, which is essential for designing novel drug targets.
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4
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Carr HS, Chang JT, Frost JA. The PDZ Domain Protein SYNJ2BP Regulates GRK-Dependent Sst2A Phosphorylation and Downstream MAPK Signaling. Endocrinology 2021; 162:6031468. [PMID: 33313679 PMCID: PMC7799432 DOI: 10.1210/endocr/bqaa229] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Indexed: 11/19/2022]
Abstract
The somatostatin receptor 2A (SST2) is a G-protein-coupled receptor (GPCR) that is expressed in neuroendocrine tissues within the gastrointestinal tract and brain, and is commonly overexpressed in many neuroendocrine tumors. Moreover, SST2 agonists are used clinically as the primary pharmacological treatment to suppress excess hormone secretion in a variety of neuroendocrine tumors. Despite its wide clinical use, mechanisms controlling the trafficking and signaling of SST2 are not fully understood. SST2 contains a C-terminal post-synaptic density 95, Drosophila discs large, zona-occludens 1 (PDZ) domain-binding motif that has been shown to interact with 3 different PDZ domain-containing proteins. However, the consequences of these interactions are not well understood, nor is it known whether additional PDZ domain proteins interact with SST2. Through unbiased screening we have identified 10 additional PDZ domain proteins that interact with SST2. We chose one of these, SYNJ2BP, for further study. We observed that SYNJ2BP interacted with SST2 in an agonist-dependent manner, and that this required the PDZ binding site of SST2. Importantly, overexpression of SYNJ2BP enhanced ligand-stimulated receptor internalization. Mechanistically, SYNJ2BP interacted with G-protein-coupled receptor kinase 2 (GRK2) and promoted GRK-dependent phosphorylation of the receptor after somatostatin stimulation. Interaction with GRK2 required the C-terminus of SYNJ2BP. Binding to SYNJ2BP did not affect the ability of SST2 to suppress 3',5'-cyclic adenosine 5'-monophosphate production, but was required for optimal agonist-stimulated extracellularly regulated kinase 1/2 activation. These data indicated that SYNJ2BP is an SST2-interacting protein that modulates agonist-stimulated receptor regulation and downstream signaling.
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Affiliation(s)
- Heather S Carr
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Jeffrey T Chang
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas, USA
| | - Jeffrey A Frost
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas, USA
- Correspondence: Jeffrey A. Frost, PhD, Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, 6431 Fannin St, Houston, TX 77030, USA.
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Olsen C, Memarzadeh K, Ulu A, Carr HS, Bean AJ, Frost JA. Regulation of Somatostatin Receptor 2 Trafficking by C-Tail Motifs and the Retromer. Endocrinology 2019; 160:1031-1043. [PMID: 30822353 PMCID: PMC6462214 DOI: 10.1210/en.2018-00865] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 02/25/2019] [Indexed: 12/15/2022]
Abstract
The Gi-coupled somatostatin receptor 2 (SST2) is a G protein-coupled receptor (GPCR) that mediates many of somatostatin's neuroendocrine actions. Upon stimulation, SST2 is rapidly internalized and transported to early endosomes before being recycled to the plasma membrane. However, little is known about the intracellular itinerary of SST2 after it moves to the early endosomal compartment or the cytoplasmic proteins that regulate its trafficking. As postsynaptic density protein/discs large 1/zonula occludens-1 (PDZ) domain interactions often regulate the trafficking and signaling potential of GPCRs, we examined the role of the SST2 PDZ ligand and additional C-terminal residues in controlling its intracellular trafficking. We determined that SST2 can recycle to the plasma membrane via multiple pathways, including a LAMP1/Rab7-positive late endosome to the trans-Golgi network (TGN) pathway. Trafficking from the late endosome to the TGN is often regulated by the retromer complex of endosomal coat proteins, and disrupting the retromer components sorting nexins 1/2 inhibits the budding of SST2 from late endosomes. Moreover, trafficking through the late endosomal/TGN pathway is dependent on an intact PDZ ligand and C-terminal tail, as truncating either the 3 or 10 C-terminal amino acids of SST2 alters the pathway through which it recycles to the plasma membrane. Moreover, addition of these amino acids to a heterologous receptor is sufficient to redirect it from a degradation pathway to a recycling itinerary. Our results demonstrate that endosomal trafficking of SST2 is dependent on numerous regulatory mechanisms controlled by its C terminus and the retromer machinery.
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Affiliation(s)
- Courtney Olsen
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas
- MD Anderson UTHealth Graduate School of Biomedical Sciences, Houston, Texas
| | - Kimiya Memarzadeh
- MD Anderson UTHealth Graduate School of Biomedical Sciences, Houston, Texas
- Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, Houston, Texas
| | - Arzu Ulu
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas
| | - Heather S Carr
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas
| | - Andrew J Bean
- MD Anderson UTHealth Graduate School of Biomedical Sciences, Houston, Texas
- Department of Neurobiology and Anatomy, University of Texas Health Science Center at Houston, Houston, Texas
- Department of Pediatrics, University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Jeffrey A Frost
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, Texas
- MD Anderson UTHealth Graduate School of Biomedical Sciences, Houston, Texas
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6
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Riedemann T, Sutor B. Long-lasting actions of somatostatin on pyramidal cell excitability in the mouse cingulate cortex. Neurosci Lett 2019; 698:217-223. [PMID: 30668961 DOI: 10.1016/j.neulet.2019.01.034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 01/10/2019] [Accepted: 01/18/2019] [Indexed: 02/07/2023]
Abstract
Many neurological diseases are related to disturbances of somatostatin- (SOM-) expressing interneurons in the cingulate cortex. Therefore, their role within the circuitry of the cingulate cortex needs to be investigated. We describe here the physiological time course of SOM effects onto pyramidal cell excitability and action potential discharge pattern. Furthermore, we show that the GRK2 inhibitor Gallein had no effect on the reduced SOM-induced response following repetitive SOM applications.
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Affiliation(s)
- Therese Riedemann
- Biomedical Center, Ludwig-Maximilians-Universität, Physiological Genomics, Großhaderner Str. 9, 82152 Planegg-Martinsried, Germany.
| | - Bernd Sutor
- Biomedical Center, Ludwig-Maximilians-Universität, Physiological Genomics, Großhaderner Str. 9, 82152 Planegg-Martinsried, Germany
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7
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Günther T, Tulipano G, Dournaud P, Bousquet C, Csaba Z, Kreienkamp HJ, Lupp A, Korbonits M, Castaño JP, Wester HJ, Culler M, Melmed S, Schulz S. International Union of Basic and Clinical Pharmacology. CV. Somatostatin Receptors: Structure, Function, Ligands, and New Nomenclature. Pharmacol Rev 2019; 70:763-835. [PMID: 30232095 PMCID: PMC6148080 DOI: 10.1124/pr.117.015388] [Citation(s) in RCA: 132] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Somatostatin, also known as somatotropin-release inhibitory factor, is a cyclopeptide that exerts potent inhibitory actions on hormone secretion and neuronal excitability. Its physiologic functions are mediated by five G protein-coupled receptors (GPCRs) called somatostatin receptor (SST)1-5. These five receptors share common structural features and signaling mechanisms but differ in their cellular and subcellular localization and mode of regulation. SST2 and SST5 receptors have evolved as primary targets for pharmacological treatment of pituitary adenomas and neuroendocrine tumors. In addition, SST2 is a prototypical GPCR for the development of peptide-based radiopharmaceuticals for diagnostic and therapeutic interventions. This review article summarizes findings published in the last 25 years on the physiology, pharmacology, and clinical applications related to SSTs. We also discuss potential future developments and propose a new nomenclature.
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Affiliation(s)
- Thomas Günther
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany (T.G., A.L., S.S.); Unit of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy (G.T.); PROTECT, INSERM, Université Paris Diderot, Sorbonne Paris Cité, Paris, France (P.D., Z.C.); Cancer Research Center of Toulouse, INSERM UMR 1037-University Toulouse III Paul Sabatier, Toulouse, France (C.B.); Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (H.-J.K.); Centre for Endocrinology, William Harvey Research Institute, Barts and London School of Medicine, Queen Mary University of London, London, United Kingdom (M.K.); Maimonides Institute for Biomedical Research of Cordoba, Córdoba, Spain (J.P.C.); Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain (J.P.C.); Reina Sofia University Hospital, Córdoba, Spain (J.P.C.); CIBER Fisiopatología de la Obesidad y Nutrición, Córdoba, Spain (J.P.C.); Pharmaceutical Radiochemistry, Technische Universität München, Munich, Germany (H.-J.W.); Culler Consulting LLC, Hopkinton, Massachusetts (M.C.); and Pituitary Center, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California (S.M.)
| | - Giovanni Tulipano
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany (T.G., A.L., S.S.); Unit of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy (G.T.); PROTECT, INSERM, Université Paris Diderot, Sorbonne Paris Cité, Paris, France (P.D., Z.C.); Cancer Research Center of Toulouse, INSERM UMR 1037-University Toulouse III Paul Sabatier, Toulouse, France (C.B.); Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (H.-J.K.); Centre for Endocrinology, William Harvey Research Institute, Barts and London School of Medicine, Queen Mary University of London, London, United Kingdom (M.K.); Maimonides Institute for Biomedical Research of Cordoba, Córdoba, Spain (J.P.C.); Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain (J.P.C.); Reina Sofia University Hospital, Córdoba, Spain (J.P.C.); CIBER Fisiopatología de la Obesidad y Nutrición, Córdoba, Spain (J.P.C.); Pharmaceutical Radiochemistry, Technische Universität München, Munich, Germany (H.-J.W.); Culler Consulting LLC, Hopkinton, Massachusetts (M.C.); and Pituitary Center, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California (S.M.)
| | - Pascal Dournaud
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany (T.G., A.L., S.S.); Unit of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy (G.T.); PROTECT, INSERM, Université Paris Diderot, Sorbonne Paris Cité, Paris, France (P.D., Z.C.); Cancer Research Center of Toulouse, INSERM UMR 1037-University Toulouse III Paul Sabatier, Toulouse, France (C.B.); Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (H.-J.K.); Centre for Endocrinology, William Harvey Research Institute, Barts and London School of Medicine, Queen Mary University of London, London, United Kingdom (M.K.); Maimonides Institute for Biomedical Research of Cordoba, Córdoba, Spain (J.P.C.); Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain (J.P.C.); Reina Sofia University Hospital, Córdoba, Spain (J.P.C.); CIBER Fisiopatología de la Obesidad y Nutrición, Córdoba, Spain (J.P.C.); Pharmaceutical Radiochemistry, Technische Universität München, Munich, Germany (H.-J.W.); Culler Consulting LLC, Hopkinton, Massachusetts (M.C.); and Pituitary Center, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California (S.M.)
| | - Corinne Bousquet
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany (T.G., A.L., S.S.); Unit of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy (G.T.); PROTECT, INSERM, Université Paris Diderot, Sorbonne Paris Cité, Paris, France (P.D., Z.C.); Cancer Research Center of Toulouse, INSERM UMR 1037-University Toulouse III Paul Sabatier, Toulouse, France (C.B.); Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (H.-J.K.); Centre for Endocrinology, William Harvey Research Institute, Barts and London School of Medicine, Queen Mary University of London, London, United Kingdom (M.K.); Maimonides Institute for Biomedical Research of Cordoba, Córdoba, Spain (J.P.C.); Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain (J.P.C.); Reina Sofia University Hospital, Córdoba, Spain (J.P.C.); CIBER Fisiopatología de la Obesidad y Nutrición, Córdoba, Spain (J.P.C.); Pharmaceutical Radiochemistry, Technische Universität München, Munich, Germany (H.-J.W.); Culler Consulting LLC, Hopkinton, Massachusetts (M.C.); and Pituitary Center, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California (S.M.)
| | - Zsolt Csaba
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany (T.G., A.L., S.S.); Unit of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy (G.T.); PROTECT, INSERM, Université Paris Diderot, Sorbonne Paris Cité, Paris, France (P.D., Z.C.); Cancer Research Center of Toulouse, INSERM UMR 1037-University Toulouse III Paul Sabatier, Toulouse, France (C.B.); Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (H.-J.K.); Centre for Endocrinology, William Harvey Research Institute, Barts and London School of Medicine, Queen Mary University of London, London, United Kingdom (M.K.); Maimonides Institute for Biomedical Research of Cordoba, Córdoba, Spain (J.P.C.); Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain (J.P.C.); Reina Sofia University Hospital, Córdoba, Spain (J.P.C.); CIBER Fisiopatología de la Obesidad y Nutrición, Córdoba, Spain (J.P.C.); Pharmaceutical Radiochemistry, Technische Universität München, Munich, Germany (H.-J.W.); Culler Consulting LLC, Hopkinton, Massachusetts (M.C.); and Pituitary Center, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California (S.M.)
| | - Hans-Jürgen Kreienkamp
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany (T.G., A.L., S.S.); Unit of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy (G.T.); PROTECT, INSERM, Université Paris Diderot, Sorbonne Paris Cité, Paris, France (P.D., Z.C.); Cancer Research Center of Toulouse, INSERM UMR 1037-University Toulouse III Paul Sabatier, Toulouse, France (C.B.); Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (H.-J.K.); Centre for Endocrinology, William Harvey Research Institute, Barts and London School of Medicine, Queen Mary University of London, London, United Kingdom (M.K.); Maimonides Institute for Biomedical Research of Cordoba, Córdoba, Spain (J.P.C.); Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain (J.P.C.); Reina Sofia University Hospital, Córdoba, Spain (J.P.C.); CIBER Fisiopatología de la Obesidad y Nutrición, Córdoba, Spain (J.P.C.); Pharmaceutical Radiochemistry, Technische Universität München, Munich, Germany (H.-J.W.); Culler Consulting LLC, Hopkinton, Massachusetts (M.C.); and Pituitary Center, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California (S.M.)
| | - Amelie Lupp
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany (T.G., A.L., S.S.); Unit of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy (G.T.); PROTECT, INSERM, Université Paris Diderot, Sorbonne Paris Cité, Paris, France (P.D., Z.C.); Cancer Research Center of Toulouse, INSERM UMR 1037-University Toulouse III Paul Sabatier, Toulouse, France (C.B.); Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (H.-J.K.); Centre for Endocrinology, William Harvey Research Institute, Barts and London School of Medicine, Queen Mary University of London, London, United Kingdom (M.K.); Maimonides Institute for Biomedical Research of Cordoba, Córdoba, Spain (J.P.C.); Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain (J.P.C.); Reina Sofia University Hospital, Córdoba, Spain (J.P.C.); CIBER Fisiopatología de la Obesidad y Nutrición, Córdoba, Spain (J.P.C.); Pharmaceutical Radiochemistry, Technische Universität München, Munich, Germany (H.-J.W.); Culler Consulting LLC, Hopkinton, Massachusetts (M.C.); and Pituitary Center, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California (S.M.)
| | - Márta Korbonits
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany (T.G., A.L., S.S.); Unit of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy (G.T.); PROTECT, INSERM, Université Paris Diderot, Sorbonne Paris Cité, Paris, France (P.D., Z.C.); Cancer Research Center of Toulouse, INSERM UMR 1037-University Toulouse III Paul Sabatier, Toulouse, France (C.B.); Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (H.-J.K.); Centre for Endocrinology, William Harvey Research Institute, Barts and London School of Medicine, Queen Mary University of London, London, United Kingdom (M.K.); Maimonides Institute for Biomedical Research of Cordoba, Córdoba, Spain (J.P.C.); Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain (J.P.C.); Reina Sofia University Hospital, Córdoba, Spain (J.P.C.); CIBER Fisiopatología de la Obesidad y Nutrición, Córdoba, Spain (J.P.C.); Pharmaceutical Radiochemistry, Technische Universität München, Munich, Germany (H.-J.W.); Culler Consulting LLC, Hopkinton, Massachusetts (M.C.); and Pituitary Center, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California (S.M.)
| | - Justo P Castaño
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany (T.G., A.L., S.S.); Unit of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy (G.T.); PROTECT, INSERM, Université Paris Diderot, Sorbonne Paris Cité, Paris, France (P.D., Z.C.); Cancer Research Center of Toulouse, INSERM UMR 1037-University Toulouse III Paul Sabatier, Toulouse, France (C.B.); Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (H.-J.K.); Centre for Endocrinology, William Harvey Research Institute, Barts and London School of Medicine, Queen Mary University of London, London, United Kingdom (M.K.); Maimonides Institute for Biomedical Research of Cordoba, Córdoba, Spain (J.P.C.); Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain (J.P.C.); Reina Sofia University Hospital, Córdoba, Spain (J.P.C.); CIBER Fisiopatología de la Obesidad y Nutrición, Córdoba, Spain (J.P.C.); Pharmaceutical Radiochemistry, Technische Universität München, Munich, Germany (H.-J.W.); Culler Consulting LLC, Hopkinton, Massachusetts (M.C.); and Pituitary Center, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California (S.M.)
| | - Hans-Jürgen Wester
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany (T.G., A.L., S.S.); Unit of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy (G.T.); PROTECT, INSERM, Université Paris Diderot, Sorbonne Paris Cité, Paris, France (P.D., Z.C.); Cancer Research Center of Toulouse, INSERM UMR 1037-University Toulouse III Paul Sabatier, Toulouse, France (C.B.); Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (H.-J.K.); Centre for Endocrinology, William Harvey Research Institute, Barts and London School of Medicine, Queen Mary University of London, London, United Kingdom (M.K.); Maimonides Institute for Biomedical Research of Cordoba, Córdoba, Spain (J.P.C.); Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain (J.P.C.); Reina Sofia University Hospital, Córdoba, Spain (J.P.C.); CIBER Fisiopatología de la Obesidad y Nutrición, Córdoba, Spain (J.P.C.); Pharmaceutical Radiochemistry, Technische Universität München, Munich, Germany (H.-J.W.); Culler Consulting LLC, Hopkinton, Massachusetts (M.C.); and Pituitary Center, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California (S.M.)
| | - Michael Culler
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany (T.G., A.L., S.S.); Unit of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy (G.T.); PROTECT, INSERM, Université Paris Diderot, Sorbonne Paris Cité, Paris, France (P.D., Z.C.); Cancer Research Center of Toulouse, INSERM UMR 1037-University Toulouse III Paul Sabatier, Toulouse, France (C.B.); Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (H.-J.K.); Centre for Endocrinology, William Harvey Research Institute, Barts and London School of Medicine, Queen Mary University of London, London, United Kingdom (M.K.); Maimonides Institute for Biomedical Research of Cordoba, Córdoba, Spain (J.P.C.); Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain (J.P.C.); Reina Sofia University Hospital, Córdoba, Spain (J.P.C.); CIBER Fisiopatología de la Obesidad y Nutrición, Córdoba, Spain (J.P.C.); Pharmaceutical Radiochemistry, Technische Universität München, Munich, Germany (H.-J.W.); Culler Consulting LLC, Hopkinton, Massachusetts (M.C.); and Pituitary Center, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California (S.M.)
| | - Shlomo Melmed
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany (T.G., A.L., S.S.); Unit of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy (G.T.); PROTECT, INSERM, Université Paris Diderot, Sorbonne Paris Cité, Paris, France (P.D., Z.C.); Cancer Research Center of Toulouse, INSERM UMR 1037-University Toulouse III Paul Sabatier, Toulouse, France (C.B.); Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (H.-J.K.); Centre for Endocrinology, William Harvey Research Institute, Barts and London School of Medicine, Queen Mary University of London, London, United Kingdom (M.K.); Maimonides Institute for Biomedical Research of Cordoba, Córdoba, Spain (J.P.C.); Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain (J.P.C.); Reina Sofia University Hospital, Córdoba, Spain (J.P.C.); CIBER Fisiopatología de la Obesidad y Nutrición, Córdoba, Spain (J.P.C.); Pharmaceutical Radiochemistry, Technische Universität München, Munich, Germany (H.-J.W.); Culler Consulting LLC, Hopkinton, Massachusetts (M.C.); and Pituitary Center, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California (S.M.)
| | - Stefan Schulz
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany (T.G., A.L., S.S.); Unit of Pharmacology, Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy (G.T.); PROTECT, INSERM, Université Paris Diderot, Sorbonne Paris Cité, Paris, France (P.D., Z.C.); Cancer Research Center of Toulouse, INSERM UMR 1037-University Toulouse III Paul Sabatier, Toulouse, France (C.B.); Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany (H.-J.K.); Centre for Endocrinology, William Harvey Research Institute, Barts and London School of Medicine, Queen Mary University of London, London, United Kingdom (M.K.); Maimonides Institute for Biomedical Research of Cordoba, Córdoba, Spain (J.P.C.); Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain (J.P.C.); Reina Sofia University Hospital, Córdoba, Spain (J.P.C.); CIBER Fisiopatología de la Obesidad y Nutrición, Córdoba, Spain (J.P.C.); Pharmaceutical Radiochemistry, Technische Universität München, Munich, Germany (H.-J.W.); Culler Consulting LLC, Hopkinton, Massachusetts (M.C.); and Pituitary Center, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California (S.M.)
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8
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Treppiedi D, Jobin ML, Peverelli E, Giardino E, Sungkaworn T, Zabel U, Arosio M, Spada A, Mantovani G, Calebiro D. Single-Molecule Microscopy Reveals Dynamic FLNA Interactions Governing SSTR2 Clustering and Internalization. Endocrinology 2018; 159:2953-2965. [PMID: 29931263 DOI: 10.1210/en.2018-00368] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 06/14/2018] [Indexed: 11/19/2022]
Abstract
The cytoskeletal protein filamin A (FLNA) has been suggested to play an important role in the responsiveness of GH-secreting pituitary tumors to somatostatin receptor subtype 2 (SSTR2) agonists by regulating SSTR2 expression and signaling. However, the underlying mechanisms are unknown. In this study, we use fast multicolor single-molecule microscopy to image individual SSTR2 and FLNA molecules at the surface of living cells with unprecedented spatiotemporal resolution. We find that SSTR2 and FLNA undergo transient interactions, which occur preferentially along actin fibers and contribute to restraining SSTR2 diffusion. Agonist stimulation increases the localization of SSTR2 along actin fibers and, subsequently, SSTR2 clustering and recruitment to clathrin-coated pits (CCPs). Interfering with FLNA-SSTR2 binding with a dominant-negative FLNA fragment increases SSTR2 mobility, hampers the formation and alignment of SSTR2 clusters along actin fibers, and impairs both SSTR2 recruitment to CCPs and SSTR2 internalization. These findings indicate that dynamic SSTR2-FLNA interactions critically control the nanoscale localization of SSTR2 at the plasma membrane and are required for coupling SSTR2 clustering to internalization. These mechanisms explain the critical role of FLNA in the control of SSTR2 expression and signaling and suggest the possibility of targeting SSTR2-FLNA interactions for the therapy of pharmacologically resistant GH-secreting pituitary tumors.
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Affiliation(s)
- Donatella Treppiedi
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Marie-Lise Jobin
- Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
- Bio-Imaging Center/Rudolf Virchow Center, University of Würzburg, Würzburg, Germany
| | - Erika Peverelli
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Elena Giardino
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Titiwat Sungkaworn
- Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
- Bio-Imaging Center/Rudolf Virchow Center, University of Würzburg, Würzburg, Germany
| | - Ulrike Zabel
- Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
- Bio-Imaging Center/Rudolf Virchow Center, University of Würzburg, Würzburg, Germany
| | - Maura Arosio
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Anna Spada
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Giovanna Mantovani
- Endocrinology Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy
- Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - Davide Calebiro
- Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
- Bio-Imaging Center/Rudolf Virchow Center, University of Würzburg, Würzburg, Germany
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, United Kingdom
- Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, Birmingham, United Kingdom
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9
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Coelho MCA, Vasquez ML, Wildemberg LE, Vázquez‐Borrego MC, Bitana L, Camacho AHDS, Silva D, Ogino LL, Ventura N, Chimelli L, Luque RM, Kasuki L, Gadelha MR. Molecular evidence and clinical importance of β-arrestins expression in patients with acromegaly. J Cell Mol Med 2018; 22:2110-2116. [PMID: 29377493 PMCID: PMC5867117 DOI: 10.1111/jcmm.13427] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 09/14/2017] [Indexed: 01/13/2023] Open
Abstract
β-arrestins seem to have a role in endocytosis and desensitization of somatostatin receptor subtype 2 (sst2) and could be associated with the responsiveness to somatostatin receptor ligands (SRL) in patients with acromegaly. To investigate the in vivo correlation between β-arrestins 1 and 2 with sst2, sst5 and dopamine receptor subtype 2 (D2) expressions, and the association of β-arrestins with response to first-generation SRL and invasiveness in somatotropinomas. β-arrestins 1 and 2, sst2, sst5 and D2 mRNA expressions were evaluated by quantitative real-time RT-PCR on tumoral tissue of 96 patients. Moreover, sst2 and sst5 protein expressions were also evaluated in 40 somatotropinomas by immunohistochemistry. Response to SRL, defined as GH <1 μg/l and normal IGF-I levels, was assessed in 40 patients. The Knosp-Steiner criteria were used to define invasiveness. Median β-arrestin 1, β-arrestin 2, sst2, sst5 and D2 mRNA copy numbers were 478; 9375; 731; 156; and 3989, respectively. There was a positive correlation between β-arrestins 1 and 2 (R = 0.444, P < 0.001). However, no correlation between β-arrestins and sst2, sst5 (mRNA and protein levels) or D2 was found. No association was found between β-arrestins expression and SRL responsiveness or tumour invasiveness. Although previous data suggest a putative correlation between β-arrestins and sst2, our data clearly indicated that no association existed between β-arrestins and sst2, sst5 or D2 expression, nor with response to SRL or tumour invasiveness. Therefore, further studies are required to clarify whether β-arrestins have a role in the response to treatment with SRL in acromegaly.
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Affiliation(s)
- Maria Caroline Alves Coelho
- Neuroendocrinology Research Center/Endocrinology DivisionMedical School and Hospital Universitário Clementino Fraga FilhoUniversidade Federal do Rio de JaneiroRio de JaneiroBrazil
- Endocrine DivisionHospital Universitário Pedro ErnestoUniversidade Estadual do Rio de JaneiroRio de JaneiroBrazil
- Endocrine DivisionInstituto Estadual de Diabetes e Endocrinologia Luiz CapriglioneRio de JaneiroBrazil
| | - Marina Lipkin Vasquez
- Molecular Genetics LaboratoryInstituto Estadual do Cérebro Paulo NiemeyerRio de JaneiroBrazil
| | - Luiz Eduardo Wildemberg
- Neuroendocrinology Research Center/Endocrinology DivisionMedical School and Hospital Universitário Clementino Fraga FilhoUniversidade Federal do Rio de JaneiroRio de JaneiroBrazil
- Neuroendocrinology DivisionInstituto Estadual do Cérebro Paulo NiemeyerRio de JaneiroBrazil
| | - Mari C. Vázquez‐Borrego
- Maimonides Institute for Biomedical Research of Cordoba (IMIBIC)CórdobaSpain
- Department of Cell Biology, Physiology, and ImmunologyUniversidad de CórdobaCórdobaSpain
- Reina Sofia University HospitalCórdobaSpain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn)CórdobaSpain
| | - Luciana Bitana
- Neuropathology LaboratoryInstituto Estadual do Cérebro Paulo NiemeyerRio de JaneiroBrazil
| | - Aline Helen da Silva Camacho
- Neuropathology LaboratoryInstituto Estadual do Cérebro Paulo NiemeyerRio de JaneiroBrazil
- Pathology DivisionInstituto Nacional do CâncerRio de janeiroBrazil
| | - Débora Silva
- Neuropathology LaboratoryInstituto Estadual do Cérebro Paulo NiemeyerRio de JaneiroBrazil
| | - Liana Lumi Ogino
- Molecular Genetics LaboratoryInstituto Estadual do Cérebro Paulo NiemeyerRio de JaneiroBrazil
| | - Nina Ventura
- Radiology DivisionInstituto Estadual do Cérebro Paulo NiemeyerRio de JaneiroBrazil
| | - Leila Chimelli
- Neuropathology LaboratoryInstituto Estadual do Cérebro Paulo NiemeyerRio de JaneiroBrazil
| | - Raul M. Luque
- Maimonides Institute for Biomedical Research of Cordoba (IMIBIC)CórdobaSpain
- Department of Cell Biology, Physiology, and ImmunologyUniversidad de CórdobaCórdobaSpain
- Reina Sofia University HospitalCórdobaSpain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn)CórdobaSpain
| | - Leandro Kasuki
- Neuroendocrinology Research Center/Endocrinology DivisionMedical School and Hospital Universitário Clementino Fraga FilhoUniversidade Federal do Rio de JaneiroRio de JaneiroBrazil
- Neuroendocrinology DivisionInstituto Estadual do Cérebro Paulo NiemeyerRio de JaneiroBrazil
- Endocrine DivisionHospital Federal de BonsucessoRio de JaneiroBrazil
| | - Mônica R. Gadelha
- Neuroendocrinology Research Center/Endocrinology DivisionMedical School and Hospital Universitário Clementino Fraga FilhoUniversidade Federal do Rio de JaneiroRio de JaneiroBrazil
- Molecular Genetics LaboratoryInstituto Estadual do Cérebro Paulo NiemeyerRio de JaneiroBrazil
- Neuroendocrinology DivisionInstituto Estadual do Cérebro Paulo NiemeyerRio de JaneiroBrazil
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10
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Wang C, Xu C, Liu M, Pan Y, Bai B, Chen J. C-terminus of OX2R significantly affects downstream signaling pathways. Mol Med Rep 2017; 16:159-166. [PMID: 28487995 PMCID: PMC5482145 DOI: 10.3892/mmr.2017.6557] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 03/30/2017] [Indexed: 12/11/2022] Open
Abstract
The human orexin 2 receptor (OX2R) is a G-protein‑coupled receptor (GPCR) that has been implicated in a number of diverse physiological functions. Recent studies have identified a number of functions of the C‑termini of GPCRs. However, the importance of the OX2R C‑terminus in regulating signaling and surface expression remains unclear. In the present study, the function of the OX2R C‑terminus was investigated using three C‑terminal mutants, which were truncated at residues 368, 384 and 414, respectively, and the wild‑type control, which expressed the full‑length OX2R. HEK‑293 cells were transfected with the mutated and control OX2R constructs. ELISA, western blot analysis and calcium assays were used to investigate the effects of the mutations on OX2R function. The present results demonstrated that residues 385‑414 and 415‑444 exhibited a cumulative effect on the surface expression of OX2R. Residues 369‑384 exhibited a significant influence on inositol phosphate production and extracellular signal‑regulated kinase 1/2 phosphorylation. Residues 385‑414 significantly influenced agonist‑induced internalization, whereas residues 369‑384 and 385‑414 significantly influenced Ca2+ release. The results of the present study suggest that the C‑terminus of OX2R is important for its role in various physiological and pathological processes, and may therefore be associated with such disorders as depression and anorexia.
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Affiliation(s)
- Chunmei Wang
- Neurobiology Institute, Jining Medical University, Jining, Shandong 272067, P.R. China
| | - Chao Xu
- Neurobiology Institute, Jining Medical University, Jining, Shandong 272067, P.R. China
| | - Minghui Liu
- Neurobiology Institute, Jining Medical University, Jining, Shandong 272067, P.R. China
| | - Yanyou Pan
- Neurobiology Institute, Jining Medical University, Jining, Shandong 272067, P.R. China
| | - Bo Bai
- Neurobiology Institute, Jining Medical University, Jining, Shandong 272067, P.R. China
| | - Jing Chen
- Neurobiology Institute, Jining Medical University, Jining, Shandong 272067, P.R. China
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11
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Treppiedi D, Peverelli E, Giardino E, Ferrante E, Calebiro D, Spada A, Mantovani G. Somatostatin Receptor Type 2 (SSTR2) Internalization and Intracellular Trafficking in Pituitary GH-Secreting Adenomas: Role of Scaffold Proteins and Implications for Pharmacological Resistance. Horm Metab Res 2017; 49:259-268. [PMID: 27632151 DOI: 10.1055/s-0042-116025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
AbstractSomatostatin receptor type 2 (SSTR2), together with SSTR5, represents the main
target of medical treatment for growth hormone (GH)-secreting pituitary tumors,
since it is expressed in most of these tumors and exerts both antiproliferative
and cytostatic effects, and reduces hormone secretion, as well. However,
clinical practice indicates a great variability in the frequency and entity of
favorable responses of acromegalic patients to long-acting somatostatin
analogues (SSAs), but the molecular mechanisms regulating this pharmacological
resistance are not completely understood. So far, several potentially implied
mechanisms have been suggested, including impaired expression of SSTRs, or
post-receptor signal transduction alterations. More recently, new studies
exploited the molecular factors involved in SSTRs intracellular trafficking
regulation, this being a critical point for the modulation of the available
active G-coupled receptors (GPCRs) amount at the cell surface. In this respect,
the role of the scaffold proteins such as β-arrestins, and the cytoskeleton
protein Filamin A (FLNA), have become of relevant importance for GH-secreting
pituitary tumors. In fact, β-arrestins are linked to SSTR2 desensitization and
internalization, and FLNA is able to regulate SSTR2 trafficking and stability at
the plasma membrane. Therefore, the present review will summarize emerging
evidence highlighting the role of β-arrestins and FLNA, as possible novel
players in the modulation of agonist activated-SSTR2 receptor trafficking and
response in GH-secreting pituitary tumors.
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Affiliation(s)
- D Treppiedi
- Endocrine Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico; Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - E Peverelli
- Endocrine Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico; Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - E Giardino
- Endocrine Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico; Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - E Ferrante
- Endocrine Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico; Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - D Calebiro
- Institute of Pharmacology and Toxicology, University of Würzburg, and Rudolf Virchow Center, Bio-Imaging Center, Würzburg, Germany
| | - A Spada
- Endocrine Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico; Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
| | - G Mantovani
- Endocrine Unit, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico; Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy
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12
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Fukutani Y, Ishii J, Kondo A, Ozawa T, Matsunami H, Yohda M. Split luciferase complementation assay for the analysis of G protein-coupled receptor ligand response in Saccharomyces cerevisiae. Biotechnol Bioeng 2017; 114:1354-1361. [DOI: 10.1002/bit.26255] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 01/17/2017] [Accepted: 01/19/2017] [Indexed: 11/11/2022]
Affiliation(s)
- Yosuke Fukutani
- Department of Biotechnology and Life Science; Tokyo University of Agriculture and Technology; Koganei Tokyo 184-8588 Japan
| | - Jun Ishii
- Graduate School of Science; Technology and Innovation; Kobe university; Kobe Japan
| | - Akihiko Kondo
- Graduate School of Science; Technology and Innovation; Kobe university; Kobe Japan
| | - Takeaki Ozawa
- Department of Chemistry; School of Science; The University of Tokyo; Hongo Tokyo Japan
| | - Hiroaki Matsunami
- Department of Molecular Genetics and Microbiology; Duke University Medical Center; Durham North Carolina
- Institute of Global Innovation Research; Tokyo University of Agriculture and Technology; Koganei Tokyo Japan
| | - Masafumi Yohda
- Department of Biotechnology and Life Science; Tokyo University of Agriculture and Technology; Koganei Tokyo 184-8588 Japan
- Institute of Global Innovation Research; Tokyo University of Agriculture and Technology; Koganei Tokyo Japan
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13
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Bronstein MD, Jallad RS. Pasireotide for treating acromegaly. Expert Opin Orphan Drugs 2016. [DOI: 10.1517/21678707.2016.1167593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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14
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Gatto F, Biermasz NR, Feelders RA, Kros JM, Dogan F, van der Lely AJ, Neggers SJCMM, Lamberts SWJ, Pereira AM, Ferone D, Hofland LJ. Low beta-arrestin expression correlates with the responsiveness to long-term somatostatin analog treatment in acromegaly. Eur J Endocrinol 2016; 174:651-62. [PMID: 26888629 DOI: 10.1530/eje-15-0391] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Accepted: 02/17/2016] [Indexed: 12/18/2022]
Abstract
OBJECTIVE The high expression of somatostatin receptor subtype 2 (SSTR2 also known as sst2) usually present in growth hormone (GH)-secreting adenomas is the rationale for therapy with somatostatin analogs (SSAs) in acromegaly. Although SSTR2 expression is a good predictor for biochemical response to SSA treatment, we still face tumors resistant to SSAs despite high SSTR2 expression. Recently, beta-arrestins (β-arrestins) have been highlighted as key players in the regulation of SSTR2 function. DESIGN To investigate whether β-arrestins might be useful predictors of responsiveness to long-term SSA treatment in acromegaly, we retrospectively evaluated 35 patients with acromegaly who underwent adenomectomy in two referral centers in The Netherlands. METHODS β-arrestin mRNA levels were evaluated in adenoma samples, together with SSTR2 (and SSTR5) mRNA and protein expression. Biochemical response to long-term SSA treatment (median 12 months) was assessed in 32 patients. RESULTS β-arrestin 1 and 2 mRNA was significantly lower in adenoma tissues from patients who achieved insulin-like growth factor 1 normalization (P = 0.024 and P = 0.047) and complete biochemical control (P = 0.047 and P = 0.039). The SSTR2 mRNA was higher in SSA responder patients compared with the resistant ones (P = 0.026). This difference was more evident when analyzing the SSTR2/β-arrestin 1 and SSTR2/β-arrestin 2 ratio (P = 0.011 and P = 0.010). β-arrestin 1 and 2 expression showed a significant trend of higher median values from full responders, partial responders to resistant patients (P = 0.045 and P = 0.021, respectively). Interestingly, SSTR2 protein expression showed a strong inverse correlation with both β-arrestin 1 and 2 mRNA (ρ = -0.69, P = 0.0011 and ρ = -0.67, P = 0.0016). CONCLUSIONS Low β-arrestin expression and high SSTR2/β-arrestin ratio correlate with the responsiveness to long-term treatment with SSAs in patients with acromegaly.
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Affiliation(s)
- Federico Gatto
- Department of Internal MedicineDivision Endocrinology, Erasmus MC, Rotterdam, The Netherlands
| | - Nienke R Biermasz
- Department of MedicineDivision of Endocrinology and Center for Endocrine Tumors, Leiden University Medical Center, Leiden, The Netherlands
| | - Richard A Feelders
- Department of Internal MedicineDivision Endocrinology, Erasmus MC, Rotterdam, The Netherlands Pituitary Center RotterdamErasmus MC, Rotterdam, The Netherlands
| | - Johan M Kros
- PathologyErasmus MC, Rotterdam, The Netherlands Pituitary Center RotterdamErasmus MC, Rotterdam, The Netherlands
| | - Fadime Dogan
- Department of Internal MedicineDivision Endocrinology, Erasmus MC, Rotterdam, The Netherlands
| | - Aart-Jan van der Lely
- Department of Internal MedicineDivision Endocrinology, Erasmus MC, Rotterdam, The Netherlands Pituitary Center RotterdamErasmus MC, Rotterdam, The Netherlands
| | - Sebastian J C M M Neggers
- Department of Internal MedicineDivision Endocrinology, Erasmus MC, Rotterdam, The Netherlands Pituitary Center RotterdamErasmus MC, Rotterdam, The Netherlands
| | - Steven W J Lamberts
- Department of Internal MedicineDivision Endocrinology, Erasmus MC, Rotterdam, The Netherlands
| | - Alberto M Pereira
- Department of MedicineDivision of Endocrinology and Center for Endocrine Tumors, Leiden University Medical Center, Leiden, The Netherlands
| | - Diego Ferone
- EndocrinologyDepartment of Internal Medicine and Medical Specialties (DIMI) and Center of Excellence for Biomedical Research (CEBR), IRCCS AOU San Martino-IST, University of Genoa, Genoa, Italy
| | - Leo J Hofland
- Department of Internal MedicineDivision Endocrinology, Erasmus MC, Rotterdam, The Netherlands Pituitary Center RotterdamErasmus MC, Rotterdam, The Netherlands
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15
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“Barcode” and Differential Effects of GPCR Phosphorylation by Different GRKs. METHODS IN PHARMACOLOGY AND TOXICOLOGY 2016. [DOI: 10.1007/978-1-4939-3798-1_5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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16
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Bou Farah L, Bowman BR, Bokiniec P, Karim S, Le S, Goodchild AK, McMullan S. Somatostatin in the rat rostral ventrolateral medulla: Origins and mechanism of action. J Comp Neurol 2015; 524:323-42. [PMID: 26131686 DOI: 10.1002/cne.23846] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Revised: 06/22/2015] [Accepted: 06/23/2015] [Indexed: 01/24/2023]
Abstract
Somatostatin (SST) or agonists of the SST-2 receptor (sst2 ) in the rostral ventrolateral medulla (RVLM) lower sympathetic nerve activity, arterial pressure, and heart rate, or when administered within the Bötzinger region, evoke apneusis. Our aims were to describe the mechanisms responsible for the sympathoinhibitory effects of SST on bulbospinal neurons and to identify likely sources of RVLM SST release. Patch clamp recordings were made from bulbospinal RVLM neurons (n = 31) in brainstem slices prepared from juvenile rat pups. Overall, 58% of neurons responded to SST, displaying an increase in conductance that reversed at -93 mV, indicative of an inwardly rectifying potassium channel (GIRK) mechanism. Blockade of sst2 abolished this effect, but application of tetrodotoxin did not, indicating that the SST effect is independent of presynaptic activity. Fourteen bulbospinal RVLM neurons were recovered for immunohistochemistry; nine were SST-insensitive and did not express sst2a . Three out of five responsive neurons were sst2a -immunoreactive. Neurons that contained preprosomatostatin mRNA and cholera-toxin-B retrogradely transported from the RVLM were detected in: paratrigeminal nucleus, lateral parabrachial nucleus, Kölliker-Fuse nucleus, ventrolateral periaqueductal gray area, central nucleus of the amygdala, sublenticular extended amygdala, interstitial nucleus of the posterior limb of the anterior commissure nucleus, and bed nucleus of the stria terminalis. Thus, those brain regions are putative sources of endogenous SST release that, when activated, may evoke sympathoinhibitory effects via interactions with subsets of sympathetic premotor neurons that express sst2 .
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Affiliation(s)
- Lama Bou Farah
- Australian School of Advanced Medicine, Macquarie University, 2109, NSW, Australia
| | - Belinda R Bowman
- Australian School of Advanced Medicine, Macquarie University, 2109, NSW, Australia
| | - Phil Bokiniec
- Australian School of Advanced Medicine, Macquarie University, 2109, NSW, Australia
| | - Shafinaz Karim
- Australian School of Advanced Medicine, Macquarie University, 2109, NSW, Australia
| | - Sheng Le
- Australian School of Advanced Medicine, Macquarie University, 2109, NSW, Australia
| | - Ann K Goodchild
- Australian School of Advanced Medicine, Macquarie University, 2109, NSW, Australia
| | - Simon McMullan
- Australian School of Advanced Medicine, Macquarie University, 2109, NSW, Australia
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17
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Azevedo AW, Doan T, Moaven H, Sokal I, Baameur F, Vishnivetskiy SA, Homan KT, Tesmer JJG, Gurevich VV, Chen J, Rieke F. C-terminal threonines and serines play distinct roles in the desensitization of rhodopsin, a G protein-coupled receptor. eLife 2015; 4. [PMID: 25910054 PMCID: PMC4438306 DOI: 10.7554/elife.05981] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 04/23/2015] [Indexed: 12/31/2022] Open
Abstract
Rod photoreceptors generate measurable responses to single-photon activation of individual molecules of the G protein-coupled receptor (GPCR), rhodopsin. Timely rhodopsin desensitization depends on phosphorylation and arrestin binding, which quenches G protein activation. Rhodopsin phosphorylation has been measured biochemically at C-terminal serine residues, suggesting that these residues are critical for producing fast, low-noise responses. The role of native threonine residues is unclear. We compared single-photon responses from rhodopsin lacking native serine or threonine phosphorylation sites. Contrary to expectation, serine-only rhodopsin generated prolonged step-like single-photon responses that terminated abruptly and randomly, whereas threonine-only rhodopsin generated responses that were only modestly slower than normal. We show that the step-like responses of serine-only rhodopsin reflect slow and stochastic arrestin binding. Thus, threonine sites play a privileged role in promoting timely arrestin binding and rhodopsin desensitization. Similar coordination of phosphorylation and arrestin binding may more generally permit tight control of the duration of GPCR activity. DOI:http://dx.doi.org/10.7554/eLife.05981.001 ‘Rod’ cells in the eye enable us to see in starlight. Inside these cells, a protein called rhodopsin is activated by light, which leads to an electrical signal being produced that travels to the brain. The duration of the electrical signal depends on the time it takes for the rhodopsin to be deactivated. Rhodopsin is a member of a large class of receptor proteins known as G protein-coupled receptors that regulate many processes throughout the body. Previous studies have shown that rhodopsin is deactivated by the attachment of phosphate groups to the protein. This allows another protein called arrestin to bind to rhodopsin. The phosphates can be attached to particular amino acids—the building blocks of proteins—at one end of rhodopsin. Three of these are a type of amino acid called serine. Previous work has shown that light increases the speed at which phosphate groups are added to these serines, suggesting that they are important for producing rapid electrical signals. The other three amino acids are of a different type—called threonine—but it is less clear what role they play in deactivating rhodopsin. Here, Azevedo et al. studied mutant forms of rhodopsin that were missing the serines or threonines in mice. The experiments show that loss of the serines only slightly slowed the electrical signals. However, loss of the threonines resulted in much slower electrical signals that ended at random times. This was due to rhodopsin being less able to bind to arrestin. Azevedo et al. propose a new model for how rhodopsin is deactivated. Once light activates the protein, phosphate groups are rapidly added to the serines, which begins to lower the activity of rhodopsin. However, it is the slower addition of phosphates to the threonines that is essential to promote arrestin binding and fully deactivate the protein. Other proteins belonging to the G protein-coupled receptor family also have these serines and threonines, and thus, may be regulated in a similar way. DOI:http://dx.doi.org/10.7554/eLife.05981.002
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Affiliation(s)
- Anthony W Azevedo
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
| | - Thuy Doan
- Department of Ophthalmology, University of Washington, Seattle, United States
| | - Hormoz Moaven
- Departments of Cell & Neurobiology and Ophthalmology, Zilkha Neurogenetic Institute, Keck School of Medicine of University of Southern California, Los Angeles, United States
| | - Iza Sokal
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
| | - Faiza Baameur
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, United States
| | - Sergey A Vishnivetskiy
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, United States
| | - Kristoff T Homan
- Life Sciences Institute, Departments of Pharmacology and Biological Chemistry, University of Michigan, Ann Arbor, United States
| | - John J G Tesmer
- Life Sciences Institute, Departments of Pharmacology and Biological Chemistry, University of Michigan, Ann Arbor, United States
| | - Vsevolod V Gurevich
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, United States
| | - Jeannie Chen
- Departments of Cell & Neurobiology and Ophthalmology, Zilkha Neurogenetic Institute, Keck School of Medicine of University of Southern California, Los Angeles, United States
| | - Fred Rieke
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
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18
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Thompson GL, Canals M, Poole DP. Biological redundancy of endogenous GPCR ligands in the gut and the potential for endogenous functional selectivity. Front Pharmacol 2014; 5:262. [PMID: 25506328 PMCID: PMC4246669 DOI: 10.3389/fphar.2014.00262] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 11/12/2014] [Indexed: 01/27/2023] Open
Abstract
This review focuses on the existence and function of multiple endogenous agonists of the somatostatin and opioid receptors with an emphasis on their expression in the gastrointestinal tract. These agonists generally arise from the proteolytic cleavage of prepropeptides during peptide maturation or from degradation of peptides by extracellular or intracellular endopeptidases. In other examples, endogenous peptide agonists for the same G protein-coupled receptors can be products of distinct genes but contain high sequence homology. This apparent biological redundancy has recently been challenged by the realization that different ligands may engender distinct receptor conformations linked to different intracellular signaling profiles and, as such the existence of distinct ligands may underlie mechanisms to finely tune physiological responses. We propose that further characterization of signaling pathways activated by these endogenous ligands will provide invaluable insight into the mechanisms governing biased agonism. Moreover, these ligands may prove useful in the design of novel therapeutic tools to target distinct signaling pathways, thereby favoring desirable effects and limiting detrimental on-target effects. Finally we will discuss the limitations of this area of research and we will highlight the difficulties that need to be addressed when examining endogenous bias in tissues and in animals.
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Affiliation(s)
- Georgina L Thompson
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences Parkville, VIC, Australia
| | - Meritxell Canals
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences Parkville, VIC, Australia
| | - Daniel P Poole
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences Parkville, VIC, Australia ; Department of Anatomy and Neuroscience, The University of Melbourne Parkville, VIC, Australia
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19
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Mohamed A, Blanchard MP, Albertelli M, Barbieri F, Brue T, Niccoli P, Delpero JR, Monges G, Garcia S, Ferone D, Florio T, Enjalbert A, Moutardier V, Schonbrunn A, Gerard C, Barlier A, Saveanu A. Pasireotide and octreotide antiproliferative effects and sst2 trafficking in human pancreatic neuroendocrine tumor cultures. Endocr Relat Cancer 2014; 21:691-704. [PMID: 25012983 DOI: 10.1530/erc-14-0086] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) raise difficult therapeutic problems despite the emergence of targeted therapies. Somatostatin analogs (SSA) remain pivotal therapeutic drugs. However, the tachyphylaxis and the limited antitumoral effects observed with the classical somatostatin 2 (sst2) agonists (octreotide and lanreotide) led to the development of new SSA, such as the pan sst receptor agonist pasireotide. Our aim was to compare the effects of pasireotide and octreotide on cell survival, chromogranin A (CgA) secretion, and sst2 phosphorylation/trafficking in pancreatic NET (pNET) primary cells from 15 tumors. We established and characterized the primary cultures of human pancreatic tumors (pNETs) as powerful preclinical models for understanding the biological effects of SSA. At clinically relevant concentrations (1-10 nM), pasireotide was at least as efficient as octreotide in inhibiting CgA secretion and cell viability through caspase-dependent apoptosis during short treatments, irrespective of the expression levels of the different sst receptors or the WHO grade of the parental tumor. Interestingly, unlike octreotide, which induces a rapid and persistent partial internalization of sst2 associated with its phosphorylation on Ser341/343, pasireotide did not phosphorylate sst2 and induced a rapid and transient internalization of the receptor followed by a persistent recycling at the cell surface. These results provide the first evidence, to our knowledge, of striking differences in the dynamics of sst2 trafficking in pNET cells treated with the two SSAs, but with similar efficiency in the control of CgA secretion and cell viability.
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Affiliation(s)
- Amira Mohamed
- Aix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USAAix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USA
| | - Marie-Pierre Blanchard
- Aix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USA
| | - Manuela Albertelli
- Aix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USA
| | - Federica Barbieri
- Aix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USA
| | - Thierry Brue
- Aix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USAAix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USA
| | - Patricia Niccoli
- Aix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USA
| | - Jean-Robert Delpero
- Aix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USA
| | - Genevieve Monges
- Aix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USA
| | - Stephane Garcia
- Aix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USA
| | - Diego Ferone
- Aix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USA
| | - Tullio Florio
- Aix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USA
| | - Alain Enjalbert
- Aix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USAAix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USA
| | - Vincent Moutardier
- Aix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USA
| | - Agnes Schonbrunn
- Aix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USA
| | - Corinne Gerard
- Aix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USA
| | - Anne Barlier
- Aix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USAAix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USA
| | - Alexandru Saveanu
- Aix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USAAix-Marseille UniversitéCNRS, CRN2M-UMR 7286, Faculté de Médecine, Secteur Nord - CS80011, 51, Bd Pierre Dramard, 13344 Marseille Cedex 15, FranceMolecular Biology LaboratoryAP-HM, Conception Hospital, 13385 Marseille, FranceAix-Marseille UniversitéCNRS, Plate-Forme de Recherche en Neurosciences PFRN, 13344 Marseille Cedex 15, FranceDepartment of Internal Medicine and Center of Excellence for Biomedical ResearchUniversity of Genova, Genova, ItalyEndocrinology DepartmentAP-HM, Timone Hospital, 13385 Marseille, FranceOncology DepartmentSurgery DepartmentBiopathology DepartmentPaoli Calmettes Cancer Institute, 13009 Marseille, FrancePathology LaboratorySurgery DepartmentAP-HM, Nord Hospital, 13015 Marseille, FranceDepartment of Integrative Biology and PharmacologyUniversity of Texas, Texas 77225, Houston, USA
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Lehmann A, Kliewer A, Schütz D, Nagel F, Stumm R, Schulz S. Carboxyl-terminal multi-site phosphorylation regulates internalization and desensitization of the human sst2 somatostatin receptor. Mol Cell Endocrinol 2014; 387:44-51. [PMID: 24565897 DOI: 10.1016/j.mce.2014.02.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 02/16/2014] [Accepted: 02/16/2014] [Indexed: 01/25/2023]
Abstract
The somatostatin receptor 2 (sst2) is the pharmacological target of somatostatin analogs that are widely used in the diagnosis and treatment of human neuroendocrine tumors. We have recently shown that the stable somatostatin analogs octreotide and pasireotide (SOM230) stimulate distinct patterns of sst2 receptor phosphorylation and internalization. Like somatostatin, octreotide promotes the phosphorylation of at least six carboxyl-terminal serine and threonine residues namely S341, S343, T353, T354, T356 and T359, which in turn leads to a robust receptor endocytosis. Unlike somatostatin, pasireotide stimulates a selective phosphorylation of S341 and S343 of the human sst2 receptor followed by a partial receptor internalization. Here, we show that exchange of S341 and S343 by alanine is sufficient to block pasireotide-driven internalization, whereas mutation of T353, T354, T356 and T359 to alanine is required to strongly inhibited both octreotide- and somatostatin-induced internalization. Yet, combined mutation of T353, T354, T356 and T359 is not sufficient to prevent somatostatin-driven β-arrestin mobilization and receptor desensitization. Replacement of all fourteen carboxyl-terminal serine and threonine residues by alanine completely abrogates sst2 receptor internalization and β-arrestin mobilization in HEK293 cells. Together, our findings demonstrate for the first time that agonist-selective sst2 receptor internalization is regulated by multi-site phosphorylation of its carboxyl-terminal tail.
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Affiliation(s)
- Andreas Lehmann
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, 07747 Jena, Germany
| | - Andrea Kliewer
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, 07747 Jena, Germany
| | - Dagmar Schütz
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, 07747 Jena, Germany
| | - Falko Nagel
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, 07747 Jena, Germany
| | - Ralf Stumm
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, 07747 Jena, Germany
| | - Stefan Schulz
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, 07747 Jena, Germany.
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21
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Schulz S, Lehmann A, Kliewer A, Nagel F. Fine-tuning somatostatin receptor signalling by agonist-selective phosphorylation and dephosphorylation: IUPHAR Review 5. Br J Pharmacol 2014; 171:1591-9. [PMID: 24328848 PMCID: PMC3966740 DOI: 10.1111/bph.12551] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 10/08/2013] [Accepted: 10/31/2013] [Indexed: 12/28/2022] Open
Abstract
The biological actions of somatostatin are mediated by a family of five GPCRs, named sst1 to sst5 . Somatostatin receptors exhibit equally high-binding affinities to their natural ligand somatostatin-14 and largely overlapping distributions. The overexpression of somatostatin receptors in human tumours is the molecular basis for diagnostic and therapeutic application of the stable somatostatin analogues octreotide, lanreotide and pasireotide. The efficiency of somatostatin receptor signalling is tightly regulated and ultimately limited by the coordinated phosphorylation and dephosphorylation of intracellular carboxyl-terminal serine and threonine residues. Here, we review and discuss recent progress in the generation and application of phosphosite-specific antibodies for human sst2 and sst5 receptors. These phosphosite-specific antibodies are unique tools to monitor the spatial and temporal dynamics of receptors phosphorylation and dephosphorylation. Using a combined approach of phosphosite-specific antibodies and siRNA knock-down screening, relevant kinases and phosphatases were identified. Emerging evidence suggests distinct mechanisms of agonist-selective fine-tuning for individual somatostatin receptors. The recently uncovered differences in phosphorylation and dephosphorylation of these receptors may hence be of physiological significance in mediating responses to acute, persistent or repeated stimuli in a variety of target tissues.
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Affiliation(s)
- Stefan Schulz
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-UniversityJena, Germany
| | - Andreas Lehmann
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-UniversityJena, Germany
| | - Andrea Kliewer
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-UniversityJena, Germany
| | - Falko Nagel
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-UniversityJena, Germany
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22
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Meng F, Huang G, Gao S, Li J, Yan Z, Wang Y. Identification of the receptors for somatostatin (SST) and cortistatin (CST) in chickens and investigation of the roles of cSST28, cSST14, and cCST14 in inhibiting cGHRH1-27NH2-induced growth hormone secretion in cultured chicken pituitary cells. Mol Cell Endocrinol 2014; 384:83-95. [PMID: 24418361 DOI: 10.1016/j.mce.2014.01.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Revised: 12/15/2013] [Accepted: 01/06/2014] [Indexed: 01/13/2023]
Abstract
Somatostatin receptors (SSTRs) are proposed to mediate the actions of somatostatin (SST) and its related peptide, cortistatin (CST), in vertebrates. However, the identity, functionality, and tissue expression of these receptors remain largely unknown in most non-mammalian vertebrates including birds. In this study, five SSTRs (named cSSTR1, cSSTR2, cSSTR3, cSSTR4, cSSTR5) were cloned from chicken brain by RT-PCR. Using a pGL3-CRE-luciferase reporter system, we demonstrated that activation of each cSSTR expressed in CHO cells by cSST28, cSST14 and cCST14 treatment could inhibit forskolin-induced luciferase activity of CHO cells, indicating the functional coupling of all cSSTRs to Gi protein(s). Interestingly, cSSTR1-4 expressed in CHO cells could be activated by cSST28, cSST14 and cCST14 with high potencies, suggesting that they may function as the receptors common for these peptides. In contrast, cSSTR5 could be potently activated by cSST28 only, indicating that it is a cSST28-specific receptor. Using RT-PCR, wide expression of cSSTRs was detected in chicken tissues including pituitary. In accordance with their expression in pituitary, cSST28, cSST14, and cCST14 were demonstrated to inhibit basal and novel cGHRH1-27NH2-induced GH secretion in cultured chicken pituitary cells dose-dependently (0-10nM) by Western blot analysis, suggesting the involvement of cSSTR(s) common for these peptides in mediating their inhibitory actions. Collectively, our study establishes a molecular basis to elucidate the roles of SST/CST in birds and provide insights into the roles of SST/CST in vertebrates, such as their conserved actions on pituitary.
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Affiliation(s)
- Fengyan Meng
- Key Laboratory of Bio-Resources and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, PR China
| | - Guian Huang
- Key Laboratory of Bio-Resources and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, PR China
| | - Shunyu Gao
- Key Laboratory of Bio-Resources and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, PR China
| | - Juan Li
- Key Laboratory of Bio-Resources and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, PR China
| | - Zhenxin Yan
- Key Laboratory of Bio-Resources and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, PR China
| | - Yajun Wang
- Key Laboratory of Bio-Resources and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610065, PR China.
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23
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Lehmann A, Kliewer A, Märtens JC, Nagel F, Schulz S. Carboxyl-terminal receptor domains control the differential dephosphorylation of somatostatin receptors by protein phosphatase 1 isoforms. PLoS One 2014; 9:e91526. [PMID: 24637622 PMCID: PMC3956607 DOI: 10.1371/journal.pone.0091526] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2013] [Accepted: 02/12/2014] [Indexed: 02/01/2023] Open
Abstract
We have recently identified protein phosphatase 1β (PP1β) as G protein-coupled receptor (GPCR) phosphatase for the sst2 somatostatin receptor using siRNA knockdown screening. By contrast, for the sst5 somatostatin receptor we identified protein phosphatase 1γ (PP1γ) as GPCR phosphatase using the same approach. We have also shown that sst2 and sst5 receptors differ substantially in the temporal dynamics of their dephosphorylation and trafficking patterns. Whereas dephosphorylation and recycling of the sst2 receptor requires extended time periods of ∼30 min, dephosphorylation and recycling of the sst5 receptor is completed in less than 10 min. Here, we examined which receptor domains determine the selection of phosphatases for receptor dephosphorylation. We found that generation of tail-swap mutants between sst2 and sst5 was required and sufficient to reverse the patterns of dephosphorylation and trafficking of these two receptors. In fact, siRNA knockdown confirmed that the sst5 receptor carrying the sst2 tail is predominantly dephosphorylated by PP1β, whereas the sst2 receptor carrying the sst5 tail is predominantly dephosphorylated by PP1γ. Thus, the GPCR phosphatase responsible for dephosphorylation of individual somatostatin receptor subtypes is primarily determined by their different carboxyl-terminal receptor domains. This phosphatase specificity has in turn profound consequences for the dephosphorylation dynamics and trafficking patterns of GPCRs.
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Affiliation(s)
- Andreas Lehmann
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany
| | - Andrea Kliewer
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany
| | - Jan Carlo Märtens
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany
| | - Falko Nagel
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany
| | - Stefan Schulz
- Institute of Pharmacology and Toxicology, Jena University Hospital, Friedrich-Schiller-University, Jena, Germany
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24
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Reubi JC, Schonbrunn A. Illuminating somatostatin analog action at neuroendocrine tumor receptors. Trends Pharmacol Sci 2013; 34:676-88. [PMID: 24183675 DOI: 10.1016/j.tips.2013.10.001] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 09/26/2013] [Accepted: 10/03/2013] [Indexed: 02/08/2023]
Abstract
Somatostatin analogs for the diagnosis and therapy of neuroendocrine tumors (NETs) have been used in clinical applications for more than two decades. Five somatostatin receptor subtypes have been identified and molecular mechanisms of somatostatin receptor signaling and regulation have been elucidated. These advances increased understanding of the biological role of each somatostatin receptor subtype, their distribution in NETs, as well as agonist-specific regulation of receptor signaling, internalization, and phosphorylation, particularly for the sst2 receptor subtype, which is the primary target of current somatostatin analog therapy for NETs. Various hypotheses exist to explain differences in patient responsiveness to somatostatin analog inhibition of tumor secretion and growth as well as differences in the development of tumor resistance to therapy. In addition, we now have a better understanding of the action of both first generation (octreotide, lanreotide, Octreoscan) and second generation (pasireotide) FDA-approved somatostatin analogs, including the biased agonistic character of some agonists. The increased understanding of somatostatin receptor pharmacology provides new opportunities to design more sophisticated assays to aid the future development of somatostatin analogs with increased efficacy.
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Affiliation(s)
- Jean Claude Reubi
- Cell Biology and Experimental Cancer Research, Institute of Pathology, University of Berne, Berne, Switzerland.
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25
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Gärtner F, Seidel T, Schulz U, Gummert J, Milting H. Desensitization and internalization of endothelin receptor A: impact of G protein-coupled receptor kinase 2 (GRK2)-mediated phosphorylation. J Biol Chem 2013; 288:32138-32148. [PMID: 24064210 DOI: 10.1074/jbc.m113.461566] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Endothelin receptor A (ETA), a G protein-coupled receptor, mediates endothelin signaling, which is regulated by GRK2. Three Ser and seven Thr residues recently proven to be phosphoacceptor sites are located in the C-terminal extremity (CTE) of the receptor following its palmitoylation site. We created various phosphorylation-deficient ETA mutants. The phospholipase C activity of mutant receptors in HEK-293 cells was analyzed during continuous endothelin stimulation to investigate the impact of phosphorylation sites on ETA desensitization. Total deletion of phosphoacceptor sites in the CTE affected proper receptor regulation. However, proximal and distal phosphoacceptor sites both turned out to be sufficient to induce WT-like desensitization. Overexpression of the Gαq coupling-deficient mutant GRK2-D110A suppressed ETA-WT signaling but failed to decrease phospholipase C activity mediated by the phosphorylation-deficient mutant ETA-6PD. In contrast, GRK2-WT acted on both receptors, whereas the kinase-inactive mutant GRK2-D110A/K220R failed to inhibit signaling of ETA-WT and ETA-6PD. This demonstrates that ETA desensitization involves at least two autonomous GRK2-mediated components: 1) a phosphorylation-independent signal decrease mediated by blocking of Gαq and 2) a mechanism involving phosphorylation of Ser and Thr residues in the CTE of the receptor in a redundant fashion, able to incorporate either proximal or distal phosphoacceptor sites. High level transfection of GRK2 variants influenced signaling of ETA-WT and ETA-6PD and hints at an additional phosphorylation-independent regulatory mechanism. Furthermore, internalization of mRuby-tagged receptors was observed with ETA-WT and the phosphorylation-deficient mutant ETA-14PD (lacking 14 phosphoacceptor sites) and turned out to be based on a phosphorylation-independent mechanism.
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Affiliation(s)
- Florian Gärtner
- From the E. & H. Klessmann Institute for Cardiovascular Research & Development, Clinic of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr University Bochum, D-32545 Bad Oeynhausen
| | - Thorsten Seidel
- Dynamic Cell Imaging, Faculty of Biology, Bielefeld University, D-33501 Bielefeld, Germany
| | - Uwe Schulz
- From the E. & H. Klessmann Institute for Cardiovascular Research & Development, Clinic of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr University Bochum, D-32545 Bad Oeynhausen
| | - Jan Gummert
- From the E. & H. Klessmann Institute for Cardiovascular Research & Development, Clinic of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr University Bochum, D-32545 Bad Oeynhausen
| | - Hendrik Milting
- From the E. & H. Klessmann Institute for Cardiovascular Research & Development, Clinic of Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr University Bochum, D-32545 Bad Oeynhausen.
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26
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Albertelli M, Arvigo M, Boschetti M, Ferone D, Gatto F, Minuto F. Somatostatin receptor pathophysiology in the neuroendocrine system. Expert Rev Endocrinol Metab 2013; 8:149-157. [PMID: 30736175 DOI: 10.1586/eem.13.7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The actions of somatostatin (SRIF) are mediated by specific G protein-coupled receptors, named SRIF receptor (SSTR) subtypes 1, 2, 3 and 5. SRIF binding to SSTR activates a series of second messenger systems, resulting in the inhibition of calcium channels and adenylate cyclase activity, ultimately leading to inhibition of hormone secretion, while stimulation of other second messengers, such as phosphotyrosine phosphatases play a role in the control of cell growth. The SSTR and dopamine receptor families share a 30% sequence homology and appear to be structurally related. The knowledge on the pathophysiology of these two families of G protein-coupled receptors in neuroendocrine tumors has progressively increased due to the new insights in receptor dimerization, internalization and trafficking. Depending on the expression of different SSTRs in tissues, their combinations and interactions affect the functionality of the subtypes expressed and the influence of the microenvironment, the response to ligands and, by consequence, the response to treatment can be very different.
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Affiliation(s)
| | - Marica Arvigo
- a Department of Internal Medicine, University of Genova, Genova, Italy
| | - Mara Boschetti
- a Department of Internal Medicine, University of Genova, Genova, Italy
- b IRCSS AOU San Martino - IST, Genova, Italy
| | - Diego Ferone
- a Department of Internal Medicine, University of Genova, Genova, Italy
- b IRCSS AOU San Martino - IST, Genova, Italy
| | - Federico Gatto
- a Department of Internal Medicine, University of Genova, Genova, Italy
| | - Francesco Minuto
- a Department of Internal Medicine, University of Genova, Genova, Italy
- b IRCSS AOU San Martino - IST, Genova, Italy
- c Department of Internal Medicine, University of Genova, Genova, Italy.
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27
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Abstract
The neuropeptide somatostatin (SRIF) is an important modulator of neurotransmission in the central nervous system and acts as a potent inhibitor of hormone and exocrine secretion. In addition, SRIF regulates cell proliferation in normal and tumorous tissues. The six somatostatin receptor subtypes (sst1, sst2A, sst2B, sst3, sst4, and sst5), which belong to the G protein-coupled receptor (GPCR) family, share a common molecular topology: a hydrophobic core of seven transmembrane-spanning α-helices, three intracellular loops, three extracellular loops, an amino-terminus outside the cell, and a carboxyl-terminus inside the cell. For most of the GPCRs, intracytosolic sequences, and more particularly the C-terminus, are believed to interact with proteins that are mandatory for either exporting neosynthesized receptor, anchoring receptor at the plasma membrane, internalization, recycling, or degradation after ligand binding. Accordingly, most of the SRIF receptors can traffic not only in vitro within different cell types but also in vivo. A picture of the pathways and proteins involved in these processes is beginning to emerge.
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Affiliation(s)
- Zsolt Csaba
- INSERM, Unité Mixte de Recherche U676, Paris, France
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28
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Butcher AJ, Kong KC, Prihandoko R, Tobin AB. Physiological role of G-protein coupled receptor phosphorylation. Handb Exp Pharmacol 2012:79-94. [PMID: 22222696 DOI: 10.1007/978-3-642-23274-9_5] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
It is now well established that G-protein coupled receptors (GPCRs) are hyper-phosphorylated following agonist occupation usually at serine and threonine residues contained on the third intracellular loop and C-terminal tail. After some 2 decades of intensive research, the nature of protein kinases involved in this process together with the signalling consequences of receptor phosphorylation has been firmly established. The major challenge that the field currently faces is placing all this information within a physiological context and determining to what extent does phosphoregulation of GPCRs impact on whole animal responses. In this chapter, we address this issue by describing how GPCR phosphorylation might vary depending on the cell type in which the receptor is expressed and how this might be employed to drive selective regulation of physiological responses.
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Affiliation(s)
- Adrian J Butcher
- Department of Cell Physiology and Pharmacology, University of Leicester, Hodgkin Building, Lancaster Road, Leicester, LE1 9HN, UK
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29
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Sreenivasan VKA, Stremovskiy OA, Kelf TA, Heblinski M, Goodchild AK, Connor M, Deyev SM, Zvyagin AV. Pharmacological characterization of a recombinant, fluorescent somatostatin receptor agonist. Bioconjug Chem 2011; 22:1768-75. [PMID: 21823634 DOI: 10.1021/bc200104u] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Somatostatin (SST) is a peptide neurotransmitter/hormone found in several mammalian tissue types. Apart from its natural importance, labeled SST/analogues are utilized in clinical applications such as targeting/diagnosis of neuroendocrine tumors. We report on the development and characterization of a novel, recombinant, fluorescent somatostatin analogue that has potential to elucidate somatostatin-activated cell signaling. SST was genetically fused with a monomeric-red fluorescent protein (mRFP) as the fluorescent label. The attachment of SST to mRFP had no detectable effect on its fluorescent properties. This analogue's potency to activate the endogenous and transfected somatostatin receptors was characterized using assays of membrane potential and Ca(2+) mobilization and immunocytochemistry. SST-mRFP was found to be an effective somatostatin receptor agonist, able to trigger the membrane hyperpolarization, mobilization of the intracellular Ca(2+) and receptor-ligand internalization in cells expressing somatostatin receptors. This complex represents a novel optical reporter due to its red emission spectral band suitable for in vivo imaging and tracking of the somatostatin receptor signaling pathways, affording higher resolution and sensitivity than those of the state-of-the-art radiolabeling bioassays.
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30
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Shenoy SK, Lefkowitz RJ. β-Arrestin-mediated receptor trafficking and signal transduction. Trends Pharmacol Sci 2011; 32:521-33. [PMID: 21680031 DOI: 10.1016/j.tips.2011.05.002] [Citation(s) in RCA: 549] [Impact Index Per Article: 42.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 05/05/2011] [Accepted: 05/09/2011] [Indexed: 01/14/2023]
Abstract
β-Arrestins function as endocytic adaptors and mediate trafficking of a variety of cell-surface receptors, including seven-transmembrane receptors (7TMRs). In the case of 7TMRs, β-arrestins carry out these tasks while simultaneously inhibiting upstream G-protein-dependent signaling and promoting alternate downstream signaling pathways. The mechanisms by which β-arrestins interact with a continuously expanding ensemble of protein partners and perform their multiple functions including trafficking and signaling are currently being uncovered. Molecular changes at the level of protein conformation as well as post-translational modifications of β-arrestins probably form the basis for their dynamic interactions during receptor trafficking and signaling. It is becoming increasingly evident that β-arrestins, originally discovered as 7TMR adaptor proteins, indeed have much broader and more versatile roles in maintaining cellular homeostasis. In this review paper, we assess the traditional and novel functions of β-arrestins and discuss the molecular attributes that might facilitate multiple interactions in regulating cell signaling and receptor trafficking.
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Affiliation(s)
- Sudha K Shenoy
- Department of Medicine, Duke University Medical Center, Box 3821, Durham, NC 27710, USA.
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31
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Kao YJ, Ghosh M, Schonbrunn A. Ligand-dependent mechanisms of sst2A receptor trafficking: role of site-specific phosphorylation and receptor activation in the actions of biased somatostatin agonists. Mol Endocrinol 2011; 25:1040-54. [PMID: 21493671 DOI: 10.1210/me.2010-0398] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The somatostatin receptor subtype 2A (sst2A) mediates many of somatostatin's neuroendocrine actions and is the primary therapeutic target for the stable somatostatin analogs used to inhibit hormone secretion by pituitary and gastroenteropancreatic tumors. Two new multireceptor targeting somatostatin analogs currently under clinical investigation, the multisomatostatin receptor agonist cyclo-[diaminoethylcarbamoyl-HydroxyPro-Phenylglycine-D-Trp-Lys-(4-O-benzyl)Tyr-Phe] (SOM230) (Pasireotide) and pan-somatostatin receptor agonist Tyr-cyclo-[D-diaminobutyric acid-Arg-Phe-Phe-D-Trp-Lys-Thr-Phe] (KE108), behave as functionally selective ligands at the sst2A receptor, mimicking some of somatostatin's actions but antagonizing others. Further, SOM230 and KE108 are less able to induce receptor internalization than somatostatin, indicating that they exhibit functional selectivity for receptor regulation as well as signaling. Here, we identify agonist-specific differences in the molecular events regulating sst2A receptor endocytosis. SOM230 and KE108 were less potent and less effective than somatostatin at stimulating sst2A receptor phosphorylation at two pairs of residues, Ser341/343 and Thr353/354. Only the pattern of Thr353/354 phosphorylation correlated with receptor internalization, consistent with the known importance of Thr phosphorylation for sst2A receptor endocytosis. As expected, arrestin recruitment to membrane receptors was reduced with SOM230 and KE108. In addition, both receptor dephosphorylation and receptor recycling occurred more rapidly with SOM230 and KE108 than with somatostatin. Surprisingly, however, SOM230 and KE108 also altered sst2A internalization in a phosphorylation-independent manner, because these analogs were less effective than somatostatin at stimulating the endocytosis of a phosphorylation-negative receptor mutant. These results show that the decreased receptor internalization produced by SOM230 and KE108 compared with somatostatin result from phosphorylation-independent effects as well as reduced site-specific receptor phosphorylation and receptor-arrestin association.
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Affiliation(s)
- Yachu J Kao
- Department of Integrative Biology and Pharmacology, University of Texas, Health Science Center-Houston, Houston, Texas 77030, USA
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Ghosh M, Schonbrunn A. Differential temporal and spatial regulation of somatostatin receptor phosphorylation and dephosphorylation. J Biol Chem 2011; 286:13561-73. [PMID: 21343287 DOI: 10.1074/jbc.m110.215723] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The G(i)-coupled somatostatin 2A receptor (sst2A) mediates many of the neuromodulatory and neuroendocrine actions of somatostatin (SS) and is targeted by the SS analogs used to treat neuroendocrine tumors. As for other G protein-coupled receptors, agonists stimulate sst2A receptor phosphorylation on multiple residues, and phosphorylation at different sites has distinct effects on receptor internalization and uncoupling. To elucidate the spatial and temporal regulation of sst2A receptor phosphorylation, we examined agonist-stimulated phosphorylation of multiple receptor GPCR kinase sites using phospho-site-specific antibodies. SS increased receptor phosphorylation sequentially, first on Ser-341/343 and then on Thr-353/354, followed by receptor internalization. Reversal of receptor phosphorylation was determined by the duration of prior agonist exposure. In acutely stimulated cells, in which most receptors remained on the cell surface, dephosphorylation occurred only on Thr-353/354. In contrast, both Ser-341/343 and Thr-353/354 were rapidly dephosphorylated when cells were stimulated long enough to allow receptor internalization before agonist removal. Consistent with these observations, dephosphorylation of Thr-353/354 was not affected by either hypertonic sucrose or dynasore, which prevent receptor internalization, whereas dephosphorylation of Ser-341/343 was completely blocked. An okadaic acid- and fostriecin-sensitive phosphatase catalyzed the dephosphorylation of Thr-353/354 both intracellularly and at the cell surface. In contrast, dephosphorylation of Ser-341/343 was insensitive to these inhibitors. Our results show that the phosphorylation and dephosphorylation of neighboring GPCR kinase sites in the sst2A receptor are subject to differential spatial and temporal regulation. Thus, the pattern of receptor phosphorylation is determined by the duration of agonist stimulation and compartment-specific enzymatic activity.
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Affiliation(s)
- Madhumita Ghosh
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas 77225, USA
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War SA, Somvanshi RK, Kumar U. Somatostatin receptor-3 mediated intracellular signaling and apoptosis is regulated by its cytoplasmic terminal. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:390-402. [PMID: 21194548 DOI: 10.1016/j.bbamcr.2010.12.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Revised: 11/25/2010] [Accepted: 12/13/2010] [Indexed: 12/25/2022]
Abstract
In the present study, we describe the role of cytoplasmic terminal (C-tail) domain in regulating coupling to adenylyl cyclase, signaling, and apoptosis in human embryonic kidney (HEK-293) cells transfected with wild type (wt)-hSSTR3 and C-tail deleted mutants. Cells transfected with wt-hSSTR3 and C-tail mutants show comparable membrane expression; however, display decreased expression in presence of agonist. wt-hSSTR3 exists as preformed homodimer at cell surface in basal conditions and decreases in response to agonist. Cells expressing C-tail mutants also show evidence of homodimerization with the same intensity as wt-hSSTR3. The agonist-dependent inhibition of cyclic adenosine monophosphate (cAMP) was lost in cells expressing C-tail mutants. Agonist treatment in cells expressing wt-hSSTR3 resulted in inhibition of cell proliferation, increased expression of PARP-1, and TUNEL positivity in proliferating cell nuclear antigen (PCNA)-positive cells. The agonist mediated increase in membrane expression of protein tyrosine phosphatase (PTP) seen with wt-hSSTR3 was diminished in C-tail mutants, which was accompanied with the loss of receptor's ability to induce apoptosis. Taken together, our data provide new insights into C-tail-dependent regulation of cell signaling and apoptosis by hSSTR3.
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Affiliation(s)
- Sajad A War
- Faculty of Pharmaceutical Sciences, Division of Pharmacology and Toxicology, The University of British Columbia, Vancouver, BC V6T1Z3, Canada
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Walther C, Nagel S, Gimenez LE, Mörl K, Gurevich VV, Beck-Sickinger AG. Ligand-induced internalization and recycling of the human neuropeptide Y2 receptor is regulated by its carboxyl-terminal tail. J Biol Chem 2010; 285:41578-90. [PMID: 20959467 DOI: 10.1074/jbc.m110.162156] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Agonist-induced internalization of G protein-coupled receptors plays an important role in signal regulation. The underlying mechanisms of the internalization of the human neuropeptide Y(2) receptor (hY(2)R), as well as its desensitization, endocytosis, and resensitization are mainly unknown. In the present study we have investigated the role of carboxyl-terminal (C-terminal) Ser/Thr residues and acidic amino acids in regulating receptor internalization, arrestin interaction, and recycling by fluorescence microscopy, cell surface enzyme-linked immunosorbent assay, and bioluminescence resonance energy transfer in several cell lines. Strikingly, C-terminal truncation mutants revealed two different internalization motifs. Whereas a distal motif (373)DSXTEXT(379) was found to be the primary regulatory internalization sequence acting in concert with arrestin-3, the proximal motif (347)DXXXSEXSXT(356) promoted ligand-induced internalization in an arrestin-3-independent manner. Moreover, we identified a regulatory sequence located between these internalization motifs ((357)FKAKKNLEVRKN(368)), which serves as an inhibitory element. We found that hY(2)R recycling is also governed by structural determinants within the proximal internalization motif. In conclusion, these results indicate that the hY(2)R C terminus is involved in multiple molecular events that regulate internalization, interaction with arrestin-3, and receptor resensitization. Our findings provide novel insights into complex mechanisms of controlled internalization of hY(2)R, which is likely applicable to other GPCRs.
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Affiliation(s)
- Cornelia Walther
- Faculty of Biosciences, Institute of Biochemistry, Leipzig University, Brüderstrasse 34, 04103 Leipzig, Germany
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Kenakin T, Miller LJ. Seven transmembrane receptors as shapeshifting proteins: the impact of allosteric modulation and functional selectivity on new drug discovery. Pharmacol Rev 2010; 62:265-304. [PMID: 20392808 DOI: 10.1124/pr.108.000992] [Citation(s) in RCA: 458] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
It is useful to consider seven transmembrane receptors (7TMRs) as disordered proteins able to allosterically respond to a number of binding partners. Considering 7TMRs as allosteric systems, affinity and efficacy can be thought of in terms of energy flow between a modulator, conduit (the receptor protein), and a number of guests. These guests can be other molecules, receptors, membrane-bound proteins, or signaling proteins in the cytosol. These vectorial flows of energy can yield standard canonical guest allostery (allosteric modification of drug effect), effects along the plane of the cell membrane (receptor oligomerization), or effects directed into the cytosol (differential signaling as functional selectivity). This review discusses these apparently diverse pharmacological effects in terms of molecular dynamics and protein ensemble theory, which tends to unify 7TMR behavior toward cells. Special consideration will be given to functional selectivity (biased agonism and biased antagonism) in terms of mechanism of action and potential therapeutic application. The explosion of technology that has enabled observation of diverse 7TMR behavior has also shown how drugs can have multiple (pluridimensional) efficacies and how this can cause paradoxical drug classification and nomenclatures.
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Affiliation(s)
- Terry Kenakin
- GlaxoSmithKline, 5 Moore Drive, Mailtstop V-287, Research Triangle Park, NC 27709, USA.
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Yin H, Lee KE, Park SA, Bhattarai JP, Suh BJ, Jeon JG, Kim BG, Park SJ, Han SK. Inhibitory effects of somatostatin on the substantia gelatinosa neurons of trigeminal subnucleus caudalis via somatostatin type 2 receptors in juvenile mice. Brain Res 2009; 1304:49-56. [DOI: 10.1016/j.brainres.2009.09.070] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2009] [Revised: 09/09/2009] [Accepted: 09/17/2009] [Indexed: 11/16/2022]
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Reiner S, Ziegler N, Leon C, Lorenz K, von Hayn K, Gachet C, Lohse MJ, Hoffmann C. beta-Arrestin-2 interaction and internalization of the human P2Y1 receptor are dependent on C-terminal phosphorylation sites. Mol Pharmacol 2009; 76:1162-71. [PMID: 19741005 DOI: 10.1124/mol.109.060467] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The nucleotide receptor P2Y(1) regulates a variety of physiological processes and is involved in platelet aggregation. Using human P2Y(1)-receptors C-terminally fused with a fluorescent protein, we studied the role of potential receptor phosphorylation sites in receptor internalization and beta-arrestin-2 translocation by means of confocal microscopy. Three receptor constructs were generated that lacked potential phosphorylation sites in the third intracellular loop, the proximal C terminus, or the distal C terminus. The corresponding receptor constructs were expressed in human embryonic kidney (HEK)-293 cells and stimulated with 100 muM ADP. Rapid receptor internalization was observed for the wild-type receptor and from those constructs mutated in the third intracellular loop and the proximal C terminus. However, the construct lacking phosphorylation sites at the distal C terminus did not show receptor internalization upon stimulation. The microscopic data were validated by HA-tagged receptor constructs using a cell surface enzyme-linked immunosorbent assay. P2Y(1)-receptor stimulated beta-arrestin-2-yellow fluorescent protein (YFP) translocation followed the same pattern as receptor internalization. Hence, no beta-arrestin-2-YFP translocation was observed when the distal C-terminal phosphorylation sites were mutated. Individual mutations indicate that residues Ser352 and Thr358 are essential for receptor internalization and beta-arrestin-2-YFP translocation. In contrast, protein kinase C (PKC)-mediated receptor desensitization was not affected by mutation of potential phosphorylation sites in the distal C terminus but was prevented by mutation of potential phosphorylation sites in the proximal C terminus. P2Y(1)-receptor internalization in HEK-293 cells was not blocked by inhibitors of PKC and calmodulin-dependent protein kinase. Thus, we conclude that P2Y(1)-receptor desensitization and internalization are mediated by different phosphorylation sites and kinases.
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Affiliation(s)
- Susanne Reiner
- Department of Pharmacology and Toxicology, University of Wuerzburg, Versbacher Str. 9, 97078 Wuerzburg, Germany
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Böhme I, Beck-Sickinger AG. Illuminating the life of GPCRs. Cell Commun Signal 2009; 7:16. [PMID: 19602276 PMCID: PMC2726148 DOI: 10.1186/1478-811x-7-16] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Accepted: 07/14/2009] [Indexed: 01/19/2023] Open
Abstract
The investigation of biological systems highly depends on the possibilities that allow scientists to visualize and quantify biomolecules and their related activities in real-time and non-invasively. G-protein coupled receptors represent a family of very dynamic and highly regulated transmembrane proteins that are involved in various important physiological processes. Since their localization is not confined to the cell surface they have been a very attractive "moving target" and the understanding of their intracellular pathways as well as the identified protein-protein-interactions has had implications for therapeutic interventions. Recent and ongoing advances in both the establishment of a variety of labeling methods and the improvement of measuring and analyzing instrumentation, have made fluorescence techniques to an indispensable tool for GPCR imaging. The illumination of their complex life cycle, which includes receptor biosynthesis, membrane targeting, ligand binding, signaling, internalization, recycling and degradation, will provide new insights into the relationship between spatial receptor distribution and function. This review covers the existing technologies to track GPCRs in living cells. Fluorescent ligands, antibodies, auto-fluorescent proteins as well as the evolving technologies for chemical labeling with peptide- and protein-tags are described and their major applications concerning the GPCR life cycle are presented.
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Affiliation(s)
- Ilka Böhme
- Institute of Biochemistry, Faculty of Biosciences, Pharmacy and Psychology, Leipzig University, Brüderstr, 34, 04103 Leipzig, Germany.
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Liu Q, Bee MS, Schonbrunn A. Site specificity of agonist and second messenger-activated kinases for somatostatin receptor subtype 2A (Sst2A) phosphorylation. Mol Pharmacol 2009; 76:68-80. [PMID: 19389921 DOI: 10.1124/mol.108.054262] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Somatostatin receptor subtype 2A (sst2A) mediates many of the endocrine and neuronal actions of somatostatin and is the target of somatostatin analogs in cancer therapy. As with many G-protein-coupled receptors, agonist stimulation causes sst2A receptor desensitization and internalization, events that require receptor phosphorylation. Furthermore, heterologous receptor activation of protein kinase C (PKC) also increases sst2A receptor phosphorylation and internalization. Here we analyzed a series of sst2A receptor mutants biochemically to identify residues in the receptor carboxyl terminus that were phosphorylated upon agonist stimulation, and we then generated four phosphorylation-sensitive antibodies to those residues. Once the selectivity of each antibody for its phosphorylated and nonphosphorylated target sequence was determined, the phospho-site-specific antibodies were used to demonstrate that somatostatin treatment of Chinese hamster ovary (CHO) cells expressing the wild type sst2A receptor increased phosphorylation on five residues in the receptor C terminus: Ser341, Ser343, Ser348, Thr353, and Thr354. Phorbol 12-myristate 13-acetate (PMA) increased receptor phosphorylation only on Ser343. Inhibition of PKC blocked PMA but not somatostatin stimulation, showing that different kinases catalyzed Ser343 phosphorylation. In contrast, somatostatin-stimulated sst2A receptor phosphorylation was inhibited by knockdown of G-protein coupled receptor kinase-2 with siRNA. Somatostatin increased sst2A receptor phosphorylation on the same five residues in GH4C1 pituitary cells as in CHO cells. However, PMA stimulated sst2A receptor phosphorylation on both Ser343 and Ser348 in GH4C1 cells. These results characterize the complex pattern of sst2A receptor phosphorylation by agonist and second messenger-activated kinases for the first time and indicate that cell type-specific regulation of sst2A receptor phosphorylation occurs.
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Affiliation(s)
- Qisheng Liu
- Department of Integrative Biology and Pharmacology, University of Texas-Houston, School of Medicine, Houston, TX 77225, USA
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Cervia D, Martini D, Ristori C, Catalani E, Timperio AM, Bagnoli P, Casini G. Modulation of the neuronal response to ischaemia by somatostatin analogues in wild-type and knock-out mouse retinas. J Neurochem 2008; 106:2224-35. [PMID: 18624922 DOI: 10.1111/j.1471-4159.2008.05556.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Somatostatin acts at five G protein-coupled receptors, sst(1)-sst(5). In mouse ischaemic retinas, the over-expression of sst(2) (as in sst(1) knock-out mice) results in the reduction of cell death and glutamate release. In this study, we reported that, in wild-type retinas, somatostatin, the multireceptor ligand pasireotide and the sst(2) agonist octreotide decreased ischaemia-induced cell death and that octreotide also decreased glutamate release. In contrast, cell death was increased by blocking sst(2) with cyanamide. In sst(2) over-expressing ischaemic retinas, somatostatin analogues increased cell death, and octreotide also increased glutamate release. To explain this reversal of the anti-ischaemic effect of somatostatin agonists in the presence of sst(2) over-expression, we tested sst(2) desensitisation because of internalisation or altered receptor function. We observed that (i) sst(2) was not internalised, (ii) among G protein-coupled receptor kinases (GRKs) and regulators of G protein signalling (RGSs), GRK1 and RGS1 expression increased following ischaemia, (iii) both GRK1 and RGS1 were down-regulated by octreotide in wild-type ischaemic retinas, (iv) octreotide down-regulated GRK1 but not RGS1 in sst(2) over-expressing ischaemic retinas. These results demonstrate that sst(2) activation protects against retinal ischaemia. However, in the presence of sst(2) over-expression sst(2) is functionally desensitised by agonists, possibly because of sustained RGS1 levels.
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Affiliation(s)
- Davide Cervia
- Department of Environmental Sciences, University of Tuscia, Largo dell'Università snc, Viterbo.
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Tobin AB, Butcher AJ, Kong KC. Location, location, location...site-specific GPCR phosphorylation offers a mechanism for cell-type-specific signalling. Trends Pharmacol Sci 2008; 29:413-20. [PMID: 18606460 PMCID: PMC2880250 DOI: 10.1016/j.tips.2008.05.006] [Citation(s) in RCA: 236] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Revised: 05/14/2008] [Accepted: 05/14/2008] [Indexed: 12/21/2022]
Abstract
It is now established that most of the approximately 800 G-protein-coupled receptors (GPCRs) are regulated by phosphorylation in a process that results in the recruitment of arrestins, leading to receptor desensitization and the activation of arrestin-dependent processes. This generalized view of GPCR regulation, however, does not provide an adequate mechanism for the control of tissue-specific GPCR signalling. Here, we review the evidence that GPCR phosphorylation is, in fact, a flexible and dynamic regulatory process in which GPCRs are phosphorylated in a unique manner that is associated with the cell type in which the receptor is expressed. In this scenario, phosphorylation offers a mechanism of regulating the signalling outcome of GPCRs that can be tailored to meet a specific physiological role.
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Affiliation(s)
- Andrew B Tobin
- Department of Cell Physiology and Pharmacology, University of Leicester, LE1 9HN, UK.
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