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Carr HS, Zuo Y, Frost JA. The Wnt pathway protein Dvl1 targets somatostatin receptor 2 for lysosome-dependent degradation. J Biol Chem 2023; 299:104645. [PMID: 36965619 PMCID: PMC10164914 DOI: 10.1016/j.jbc.2023.104645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 03/15/2023] [Accepted: 03/16/2023] [Indexed: 03/27/2023] Open
Abstract
The Somatostatin receptor 2 (Sstr2) is a heterotrimeric G protein-coupled receptor that is highly expressed in neuroendocrine tumors and is a common pharmacological target for intervention. Unfortunately, not all neuroendocrine tumors express Sstr2, and Sstr2 expression can be downregulated with prolonged agonist use. Sstr2 is rapidly internalized following agonist stimulation and, in the short term, is quantitatively recycled back to the plasma membrane. However, mechanisms controlling steady state expression of Sstr2 in the absence of agonist are less well described. Here, we show that Sstr2 interacts with the Wnt pathway protein Dvl1 in a ligand-independent manner to target Sstr2 for lysosomal degradation. Interaction of Sstr2 with Dvl1 does not affect receptor internalization, recycling, or signaling to adenylyl cyclase but does suppress agonist-stimulated ERK1/2 activation. Importantly, Dvl1-dependent degradation of Sstr2 can be stimulated by overexpression of Wnts and treatment of cells with Wnt pathway inhibitors can boost Sstr2 expression in neuroendocrine tumor cells. Taken together, this study identifies for the first time a mechanism that targets Sstr2 for lysosomal degradation that is independent of Sstr2 agonist and can be potentiated by Wnt ligand. Intervention in this signaling mechanism has the potential to elevate Sstr2 expression in neuroendocrine tumors and enhance Sstr2-directed therapies.
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Affiliation(s)
- Heather S Carr
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas, USA
| | - Yan Zuo
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas, USA
| | - Jeffrey A Frost
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas, USA.
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Solís KH, Romero-Ávila MT, Guzmán-Silva A, García-Sáinz JA. The LPA 3 Receptor: Regulation and Activation of Signaling Pathways. Int J Mol Sci 2021; 22:ijms22136704. [PMID: 34201414 PMCID: PMC8269014 DOI: 10.3390/ijms22136704] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/08/2021] [Accepted: 06/12/2021] [Indexed: 12/17/2022] Open
Abstract
The lysophosphatidic acid 3 receptor (LPA3) participates in different physiological actions and in the pathogenesis of many diseases through the activation of different signal pathways. Knowledge of the regulation of the function of the LPA3 receptor is a crucial element for defining its roles in health and disease. This review describes what is known about the signaling pathways activated in terms of its various actions. Next, we review knowledge on the structure of the LPA3 receptor, the domains found, and the roles that the latter might play in ligand recognition, signaling, and cellular localization. Currently, there is some information on the action of LPA3 in different cells and whole organisms, but very little is known about the regulation of its function. Areas in which there is a gap in our knowledge are indicated in order to further stimulate experimental work on this receptor and on other members of the LPA receptor family. We are convinced that knowledge on how this receptor is activated, the signaling pathways employed and how the receptor internalization and desensitization are controlled will help design new therapeutic interventions for treating diseases in which the LPA3 receptor is implicated.
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Vitali E, Piccini S, Trivellin G, Smiroldo V, Lavezzi E, Zerbi A, Pepe G, Lania AG. The impact of SST2 trafficking and signaling in the treatment of pancreatic neuroendocrine tumors. Mol Cell Endocrinol 2021; 527:111226. [PMID: 33675866 DOI: 10.1016/j.mce.2021.111226] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 02/17/2021] [Accepted: 02/21/2021] [Indexed: 01/01/2023]
Abstract
Pancreatic neuroendocrine tumors (Pan-NETs), are heterogeneous neoplasms, whose incidence and prevalence are increasing worldwide. Pan-NETs are characterized by the expression of somatostatin receptors (SSTs). In particular, SST2 is the most widely distributed SST in NETs, thus representing the main molecular target for somatostatin analogs (SSAs). SSAs are currently approved for the treatment of well-differentiated NETs, and radionuclide-labeled SSAs are used for diagnostic and treatment purposes. SSAs, by binding to SSTs, have been shown to inhibit hormone secretion and thus provide control of hypersecretion symptoms, when present, and inhibit tumor proliferation. After SSA binding to SST2, the fate of the receptor is determined by trafficking mechanisms, crucial for the response to endogenous or pharmacological ligands. Although SST2 acts mostly through G protein-dependent mechanism, receptor-ligand complex endocytosis and receptor trafficking further regulate its function. SST2 mediates the decrease of hormone secretion via a G protein-dependent mechanism, culminating with the inhibition of adenylyl cyclase and calcium channels; it also inhibits cell proliferation and increases apoptosis through the modulation of protein tyrosine phosphatases. Moreover, SST2 inhibits angiogenesis and cell migration. In this respect, the cross-talk between SST2 and its interacting proteins, including Filamin A (FLNA) and aryl hydrocarbon receptor-interacting protein (AIP), plays a crucial role for SST2 signaling and responsiveness to SSAs. This review will focus on recent studies from our and other groups that have investigated the trafficking and signaling of SST2 in Pan-NETs, in order to provide insights into the mechanisms underlying tumor responsiveness to pharmacological treatments.
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Affiliation(s)
- E Vitali
- Laboratory of Cellular and Molecular Endocrinology, Italy; Department of Biomedical Sciences, Humanitas University, Rozzano, Italy.
| | - S Piccini
- Laboratory of Cellular and Molecular Endocrinology, Italy; Department of Biomedical Sciences, Humanitas University, Rozzano, Italy
| | - G Trivellin
- Laboratory of Cellular and Molecular Endocrinology, Italy; Laboratory of Pharmacology and Brain Pathology, Humanitas Clinical and Research Center - IRCCS, Rozzano, Italy
| | - V Smiroldo
- Oncology Unit, Humanitas Clinical and Research Center - IRCCS, Rozzano, Italy
| | - E Lavezzi
- Endocrinology and Diabetology Unit Humanitas Clinical and Research Center - IRCCS, Rozzano, Italy
| | - A Zerbi
- Department of Biomedical Sciences, Humanitas University, Rozzano, Italy; Pancreas Surgery Unit, Humanitas Clinical and Research Center - IRCCS, Rozzano, Italy
| | - G Pepe
- Nuclear Medicine Humanitas Clinical and Research Center - IRCCS, Rozzano, Italy
| | - A G Lania
- Laboratory of Cellular and Molecular Endocrinology, Italy; Department of Biomedical Sciences, Humanitas University, Rozzano, Italy; Endocrinology and Diabetology Unit Humanitas Clinical and Research Center - IRCCS, Rozzano, Italy
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Octreotide and Pasireotide Combination Treatment in Somatotroph Tumor Cells: Predominant Role of SST 2 in Mediating Ligand Effects. Cancers (Basel) 2021; 13:cancers13081816. [PMID: 33920241 PMCID: PMC8069349 DOI: 10.3390/cancers13081816] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 04/08/2021] [Indexed: 12/16/2022] Open
Abstract
Simple Summary First-generation somatostatin receptor ligands, such as octreotide, are the first-line medical therapy in acromegaly. Octreotide shows preferential binding for somatostatin receptor subtype 2 (SST2), while the second-generation ligand, pasireotide, has high affinity for multiple SSTs. We aimed to elucidate whether pasireotide acts via other receptors than SST2 in somatotroph tumors, and to investigate the potential role of the combination therapy octreotide plus pasireotide. We found that octreotide and pasireotide are superimposable in reducing GH secretion in cultured somatotroph tumor cells, as well as in inhibiting cell proliferation and intracellular pathway activity in rat GH4C1 cells (a model of somatotroph tumors). We did not find any additive/synergistic effect for the combination treatment. Furthermore, we observed that co-incubation with a SST2-selective antagonist reversed the inhibitory effect of both compounds. Therefore, the two drugs act mainly via SST2 in somatotroph tumor cells, and their combination is not superior to single agent treatment. Abstract First-generation somatostatin receptor ligands (fg-SRLs), such as octreotide (OCT), represent the first-line medical therapy in acromegaly. Fg-SRLs show a preferential binding affinity for somatostatin receptor subtype-2 (SST2), while the second-generation ligand, pasireotide (PAS), has high affinity for multiple SSTs (SST5 > SST2 > SST3 > SST1). Whether PAS acts via SST2 in somatotroph tumors, or through other SSTs (e.g., SST5), is a matter of debate. In this light, the combined treatment OCT+PAS could result in additive/synergistic effects. We evaluated the efficacy of OCT and PAS (alone and in combination) on growth hormone (GH) secretion in primary cultures from human somatotroph tumors, as well as on cell proliferation, intracellular signaling and receptor trafficking in the rat GH4C1 cell line. The results confirmed the superimposable efficacy of OCT and PAS in reducing GH secretion (primary cultures), cell proliferation, cAMP accumulation and intracellular [Ca2+] increase (GH4C1 cells), without any additive effect observed for OCT+PAS. In GH4C1 cells, co-incubation with a SST2-selective antagonist reversed the inhibitory effect of OCT and PAS on cell proliferation and cAMP accumulation, while both compounds resulted in a robust internalization of SST2 (but not SST5). In conclusion, OCT and PAS seem to act mainly through SST2 in somatotroph tumor cells in vitro, without inducing any additive/synergistic effect when tested in combination.
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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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Biological and Biochemical Basis of the Differential Efficacy of First and Second Generation Somatostatin Receptor Ligands in Neuroendocrine Neoplasms. Int J Mol Sci 2019; 20:ijms20163940. [PMID: 31412614 PMCID: PMC6720449 DOI: 10.3390/ijms20163940] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/1970] [Revised: 08/05/2019] [Accepted: 08/08/2019] [Indexed: 02/07/2023] Open
Abstract
Endogenous somatostatin shows anti-secretory effects in both physiological and pathological settings, as well as inhibitory activity on cell growth. Since somatostatin is not suitable for clinical practice, researchers developed synthetic somatostatin receptor ligands (SRLs) to overcome this limitation. Currently, SRLs represent pivotal tools in the treatment algorithm of neuroendocrine tumors (NETs). Octreotide and lanreotide are the first-generation SRLs developed and show a preferential binding affinity to somatostatin receptor (SST) subtype 2, while pasireotide, which is a second-generation SRL, has high affinity for multiple SSTs (SST5 > SST2 > SST3 > SST1). A number of studies demonstrated that first-generation and second-generation SRLs show distinct functional properties, besides the mere receptor affinity. Therefore, the aim of the present review is to critically review the current evidence on the biological effects of SRLs in pituitary adenomas and neuroendocrine tumors, by mainly focusing on the differences between first-generation and second-generation ligands.
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Seyedabadi M, Ghahremani MH, Albert PR. Biased signaling of G protein coupled receptors (GPCRs): Molecular determinants of GPCR/transducer selectivity and therapeutic potential. Pharmacol Ther 2019; 200:148-178. [PMID: 31075355 DOI: 10.1016/j.pharmthera.2019.05.006] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 04/26/2019] [Indexed: 02/07/2023]
Abstract
G protein coupled receptors (GPCRs) convey signals across membranes via interaction with G proteins. Originally, an individual GPCR was thought to signal through one G protein family, comprising cognate G proteins that mediate canonical receptor signaling. However, several deviations from canonical signaling pathways for GPCRs have been described. It is now clear that GPCRs can engage with multiple G proteins and the line between cognate and non-cognate signaling is increasingly blurred. Furthermore, GPCRs couple to non-G protein transducers, including β-arrestins or other scaffold proteins, to initiate additional signaling cascades. Receptor/transducer selectivity is dictated by agonist-induced receptor conformations as well as by collateral factors. In particular, ligands stabilize distinct receptor conformations to preferentially activate certain pathways, designated 'biased signaling'. In this regard, receptor sequence alignment and mutagenesis have helped to identify key receptor domains for receptor/transducer specificity. Furthermore, molecular structures of GPCRs bound to different ligands or transducers have provided detailed insights into mechanisms of coupling selectivity. However, receptor dimerization, compartmentalization, and trafficking, receptor-transducer-effector stoichiometry, and ligand residence and exposure times can each affect GPCR coupling. Extrinsic factors including cell type or assay conditions can also influence receptor signaling. Understanding these factors may lead to the development of improved biased ligands with the potential to enhance therapeutic benefit, while minimizing adverse effects. In this review, evidence for ligand-specific GPCR signaling toward different transducers or pathways is elaborated. Furthermore, molecular determinants of biased signaling toward these pathways and relevant examples of the potential clinical benefits and pitfalls of biased ligands are discussed.
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Affiliation(s)
- Mohammad Seyedabadi
- Department of Pharmacology, School of Medicine, Bushehr University of Medical Sciences, Iran; Education Development Center, Bushehr University of Medical Sciences, Iran
| | | | - Paul R Albert
- Ottawa Hospital Research Institute, Neuroscience, University of Ottawa, Canada.
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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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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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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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11
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Lau A, Bourkas M, Lu YQQ, Ostrowski LA, Weber-Adrian D, Figueiredo C, Arshad H, Shoaei SZS, Morrone CD, Matan-Lithwick S, Abraham KJ, Wang H, Schmitt-Ulms G. Functional Amyloids and their Possible Influence on Alzheimer Disease. Discoveries (Craiova) 2017; 5:e79. [PMID: 32309597 PMCID: PMC7159844 DOI: 10.15190/d.2017.9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 09/29/2017] [Accepted: 10/02/2017] [Indexed: 12/21/2022] Open
Abstract
Amyloids play critical roles in human diseases but have increasingly been recognized to also exist naturally. Shared physicochemical characteristics of amyloids and of their smaller oligomeric building blocks offer the prospect of molecular interactions and crosstalk amongst these assemblies, including the propensity to mutually influence aggregation. A case in point might be the recent discovery of an interaction between the amyloid β peptide (Aβ) and somatostatin (SST). Whereas Aβ is best known for its role in Alzheimer disease (AD) as the main constituent of amyloid plaques, SST is intermittently stored in amyloid-form in dense core granules before its regulated release into the synaptic cleft. This review was written to introduce to readers a large body of literature that surrounds these two peptides. After introducing general concepts and recent progress related to our understanding of amyloids and their aggregation, the review focuses separately on the biogenesis and interactions of Aβ and SST, before attempting to assess the likelihood of encounters of the two peptides in the brain, and summarizing key observations linking SST to the pathobiology of AD. While the review focuses on Aβ and SST, it is to be anticipated that crosstalk amongst functional and disease-associated amyloids will emerge as a general theme with much broader significance in the etiology of dementias and other amyloidosis.
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Affiliation(s)
- Angus Lau
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, 6th Floor, 60 Leonard Avenue, Toronto, Ontario M5T 2S8, Canada
| | - Matthew Bourkas
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, 6th Floor, 60 Leonard Avenue, Toronto, Ontario M5T 2S8, Canada
| | - Yang Qing Qin Lu
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Lauren Anne Ostrowski
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Danielle Weber-Adrian
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Carlyn Figueiredo
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Hamza Arshad
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, 6th Floor, 60 Leonard Avenue, Toronto, Ontario M5T 2S8, Canada
| | - Seyedeh Zahra Shams Shoaei
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Christopher Daniel Morrone
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Stuart Matan-Lithwick
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Karan Joshua Abraham
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
| | - Hansen Wang
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, 6th Floor, 60 Leonard Avenue, Toronto, Ontario M5T 2S8, Canada
| | - Gerold Schmitt-Ulms
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Medical Sciences Building, 6th Floor, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, 6th Floor, 60 Leonard Avenue, Toronto, Ontario M5T 2S8, Canada
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12
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Cambiaghi V, Vitali E, Morone D, Peverelli E, Spada A, Mantovani G, Lania AG. Identification of human somatostatin receptor 2 domains involved in internalization and signaling in QGP-1 pancreatic neuroendocrine tumor cell line. Endocrine 2017; 56:146-157. [PMID: 27406390 DOI: 10.1007/s12020-016-1026-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 06/16/2016] [Indexed: 01/14/2023]
Abstract
Somatostatin exerts inhibitory effects on hormone secretion and cell proliferation via five receptor subtypes (SST1-SST5), whose internalization is regulated by β-arrestins. The receptor domains involved in these effects have been only partially elucidated. The aim of the study is to characterize the molecular mechanism and determinants responsible for somatostatin receptor 2 internalization and signaling in pancreatic neuroendocrine QGP-1 cell line, focusing on the third intracellular loop and carboxyl terminal domains. We demonstrated that in cells transfected with somatostatin receptor 2 third intracellular loop mutant, no differences in β-arrestins recruitment and receptor internalization were observed after somatostatin receptor 2 activation in comparison with cells bearing wild-type somatostatin receptor 2. Conversely, the truncated somatostatin receptor 2 failed to recruit β-arrestins and to internalize after somatostatin receptor 2 agonist (BIM23120) incubation. Moreover, the inhibitory effect of BIM23120 on cell proliferation, cyclin D1 expression, P-ERK1/2 levels, apoptosis and vascular endothelial growth factor secretion was completely lost in cells transfected with either third intracellular loop or carboxyl terminal mutants. In conclusion, we demonstrated that somatostatin receptor 2 internalization requires intact carboxyl terminal while the effects of SS on cell proliferation, angiogenesis and apoptosis mediated by somatostatin receptor 2 need the integrity of both third intracellular loop and carboxyl terminal.
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Affiliation(s)
- Valeria Cambiaghi
- Laboratory of Cellular and Molecular Endocrinology, Humanitas Clinical and Research Center, Rozzano, Italy
| | - Eleonora Vitali
- Laboratory of Cellular and Molecular Endocrinology, Humanitas Clinical and Research Center, Rozzano, Italy
| | - Diego Morone
- Laboratory of Cellular and Molecular Endocrinology, Humanitas Clinical and Research Center, Rozzano, Italy
| | - Erika Peverelli
- Endocrine Unit, Department of Clinical Sciences and Community Health, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Anna Spada
- Endocrine Unit, Department of Clinical Sciences and Community Health, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Giovanna Mantovani
- Endocrine Unit, Department of Clinical Sciences and Community Health, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Andrea Gerardo Lania
- Endocrine Unit, Humanitas Clinical and Research Center, Rozzano, Italy.
- Humanitas University, School of Medicine, Rozzano, Italy.
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13
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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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14
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Lucas SJ, Armstrong DL. Protein phosphatase modulation of somatostatin receptor signaling in the mouse hippocampus. Neuropharmacology 2015. [PMID: 26196943 DOI: 10.1016/j.neuropharm.2015.07.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Many inhibitory interneurones in the hippocampus release the neuropeptide somatostatin (SST) which inhibits neuronal excitability through Gi/Go-coupled receptors. To investigate the signaling pathways underlying the SST inhibition of neuronal excitability in the hippocampus, we performed perforated patch-clamp recordings from CA1 pyramidal neurones in acute brain slices from P14-P18 mice. Bath application of 1 μM SST reversibly reduces the frequency of action potential firing in response to depolarising current steps, and is associated with neuronal hyperpolarisation and a reduction in membrane resistance. This effect is mediated by potassium channels with KCNK-like pharmacology. In addition, in slices that have been cultured in vitro for seven days or more, SST also produces a hyperpolarisation independent reduction in action potential firing, which can be also observed in acute slices when the Ser/Thr protein phosphatases PP2A and PP4 are inhibited selectively with fostriecin. This hyperpolarisation independent effect of SST appears to be mediated by G-protein-activated inwardly rectifying K+ (GIRK) channels. Knockdown of protein phosphatase 5, by Cre recombinase mediated deletion of the floxed Ppp5c gene, blocks the hyperpolarisation independent effect of SST, and reduces the hyperpolarisation dependent effect in a manner consistent with increased SST receptor desensitisation. Thus, reversible protein phosphorylation provides a mechanism to enhance or diminish the inhibitory effect of SST, which could allow system level regulation of circuit excitability in the hippocampus.
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Affiliation(s)
- Sarah J Lucas
- Lab. Neurobiology, National Institute of Environmental Health Sciences, NIH, Durham, NC, 27709, USA.
| | - David L Armstrong
- Lab. Neurobiology, National Institute of Environmental Health Sciences, NIH, Durham, NC, 27709, USA
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15
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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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16
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Abstract
The somatostatin (SRIF) system, which includes the SRIF ligand and receptors, regulates anterior pituitary gland function, mainly inhibiting hormone secretion and to some extent pituitary tumor cell growth. SRIF-14 via its cognate G-protein-coupled receptors (subtypes 1-5) activates multiple cellular signaling pathways including adenylate cyclase/cAMP, MAPK, ion channel-dependent pathways, and others. In addition, recent data have suggested SRIF-independent constitutive SRIF receptor activity responsible for GH and ACTH inhibition in vitro. This review summarizes current knowledge on ligand-dependent and independent SRIF receptor molecular and functional effects on hormone-secreting cells in the anterior pituitary gland.
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Affiliation(s)
- Tamar Eigler
- Division of EndocrinologyDiabetes and Metabolism, Department of Medicine, Pituitary Center, Cedars Sinai Medical Center, Davis Building, Room 3066, 8700 Beverly Boulevard, Los Angeles, California 90048, USA
| | - Anat Ben-Shlomo
- Division of EndocrinologyDiabetes and Metabolism, Department of Medicine, Pituitary Center, Cedars Sinai Medical Center, Davis Building, Room 3066, 8700 Beverly Boulevard, Los Angeles, California 90048, USA
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17
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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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18
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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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19
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Peng Y, Deng L, Ding Y, Chen Q, Wu Y, Yang M, Wang Y, Fu Q. Comparative study of somatostatin-human serum albumin fusion proteins and natural somatostatin on receptor binding, internalization and activation. PLoS One 2014; 9:e89932. [PMID: 24587133 PMCID: PMC3937410 DOI: 10.1371/journal.pone.0089932] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Accepted: 01/25/2014] [Indexed: 01/08/2023] Open
Abstract
Albumin fusion technology, the combination of small molecular proteins or peptides with human serum albumin (HSA), is an effective method for improving the medicinal values of natural small molecular proteins or peptides. However, comparative studies between HSA-fusion proteins or peptides and the parent small molecules in biological and molecular mechanisms are less reported. In this study, we examined the binding property of two novel somatostatin-HSA fusion proteins, (SST14)2-HSA and (SST28)2-HSA, to human SSTRs in stably expressing SSTR1-5 HEK 293 cells; observed the regulation of receptor internalization and internalized receptor recycling; and detected the receptors activation of HSA fusion proteins in stably expressing SSTR2- and SSTR3-EGFP cells. We showed that both somatostatin-HSA fusion proteins had high affinity to all five SSTRs, stimulated the ERK1/2 phosphorylation and persistently inhibited the accumulation of forskolin-stimulated cAMP in SSTR2- and SSTR3-expressing cells; but were less potent than the synthetic somatostatin-14 (SST-14). Our experiments also showed that somatostatin-HSA fusion proteins did not induce the receptors internalization; rather, they accelerated the recycling of the internalized receptors induced by SST-14 to the plasma membrane. Our results indicated that somatostatin-HSA fusion proteins, different from SST-14, exhibit some particular properties in binding, regulating, and activating somatostatin receptors.
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Affiliation(s)
- Ying Peng
- Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, China
| | - Lili Deng
- Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, China
| | - Yuedi Ding
- Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, China
| | - Quancheng Chen
- Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, China
| | - Yu Wu
- Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, China
| | - Meilin Yang
- Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, China
- The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China
| | - Yaping Wang
- Wuxi Second People’s Hospital of Nanjing Medical University, Wuxi, Jiangsu, China
- * E-mail: (YW); (QF)
| | - Qiang Fu
- Key Laboratory of Nuclear Medicine, Ministry of Health, Jiangsu Key Laboratory of Molecular Nuclear Medicine, Jiangsu Institute of Nuclear Medicine, Wuxi, Jiangsu, China
- * E-mail: (YW); (QF)
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20
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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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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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22
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Waser B, Cescato R, Liu Q, Kao YJ, Körner M, Christ E, Schonbrunn A, Reubi JC. Phosphorylation of sst2 receptors in neuroendocrine tumors after octreotide treatment of patients. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 180:1942-9. [PMID: 22538189 DOI: 10.1016/j.ajpath.2012.01.041] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Revised: 01/13/2012] [Accepted: 01/26/2012] [Indexed: 12/18/2022]
Abstract
Somatostatin analogues, which are used to treat neuroendocrine tumors, target the high levels of somatostatin receptor subtype 2 (SSTR1; alias sst2) expressed in these cancers. However, some tumors are resistant to somatostatin analogues, and it is unknown whether the defect lies in sst2 activation or downstream signaling events. Because sst2 phosphorylation occurs rapidly after receptor activation, we examined whether sst2 is phosphorylated in neuroendocrine tumors. The sst2 receptor phosphorylation was evaluated by IHC and Western blot analysis with the new Ra-1124 antibody specific for the sst2 receptor phosphorylated at Ser341/343 in receptor-positive neuroendocrine tumors obtained from 10 octreotide-treated and 7 octreotide-naïve patients. The specificity, time course, and subcellular localization of sst2 receptor phosphorylation were examined in human embryo kinase-sst2 cell cultures by immunofluorescence and confocal microscopy. All seven octreotide-naïve tumors displayed exclusively nonphosphorylated cell surface sst2 expression. In contrast, 9 of the 10 octreotide-treated tumors contained phosphorylated sst2 that was predominantly internalized. Western blot analysis confirmed the IHC data. Octreotide treatment of human embryo kinase-sst2 cells in culture demonstrated that phosphorylated sst2 was localized at the plasma membrane after 10 seconds of stimulation and was subsequently internalized into endocytic vesicles. These data show, for the first time to our knowledge, that phosphorylated sst2 is present in most gastrointestinal neuroendocrine tumors from patients treated with octreotide but that a striking variability exists in the subcellular distribution of phosphorylated receptors among such tumors.
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MESH Headings
- Antineoplastic Agents, Hormonal/pharmacology
- Antineoplastic Agents, Hormonal/therapeutic use
- Carcinoma, Neuroendocrine/drug therapy
- Carcinoma, Neuroendocrine/metabolism
- Carcinoma, Neuroendocrine/surgery
- Chemotherapy, Adjuvant
- Humans
- Microscopy, Confocal
- Microscopy, Fluorescence
- Neoplasm Proteins/drug effects
- Neoplasm Proteins/metabolism
- Octreotide/pharmacology
- Octreotide/therapeutic use
- Phosphorylation/drug effects
- Receptors, Somatostatin/drug effects
- Receptors, Somatostatin/metabolism
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Affiliation(s)
- Beatrice Waser
- Division of Cell Biology and Experimental Cancer Research, Institute of Pathology, University of Berne, Berne, Switzerland
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23
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Kliewer A, Mann A, Petrich A, Pöll F, Schulz S. A transplantable phosphorylation probe for direct assessment of G protein-coupled receptor activation. PLoS One 2012; 7:e39458. [PMID: 22745760 PMCID: PMC3383726 DOI: 10.1371/journal.pone.0039458] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Accepted: 05/21/2012] [Indexed: 12/12/2022] Open
Abstract
The newly developed multireceptor somatostatin analogs pasireotide (SOM230), octreotide and somatoprim (DG3173) have primarily been characterized according to their binding profiles. However, their ability to activate individual somatostatin receptor subtypes (sst) has not been directly assessed so far. Here, we transplanted the carboxyl-terminal phosphorylation motif of the sst(2) receptor to other somatostatin receptors and assessed receptor activation using a set of three phosphosite-specific antibodies. Our comparative analysis revealed unexpected efficacy profiles for pasireotide, octreotide and somatoprim. Pasireotide was able to activate sst(3) and sst(5) receptors but was only a partial agonist at the sst(2) receptor. Octreotide exhibited potent agonistic properties at the sst(2) receptor but produced very little sst(5) receptor activation. Like octreotide, somatoprim was a full agonist at the sst(2) receptor. Unlike octreotide, somatoprim was also a potent agonist at the sst(5) receptor. Together, we propose the application of a phosphorylation probe for direct assessment of G protein-coupled receptor activation and demonstrate its utility in the pharmacological characterization of novel somatostatin analogs.
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Affiliation(s)
- Andrea Kliewer
- Department of Pharmacology and Toxicology, Jena University Hospital - Friedrich Schiller University Jena, Jena, Germany
| | - Anika Mann
- Department of Pharmacology and Toxicology, Jena University Hospital - Friedrich Schiller University Jena, Jena, Germany
| | - Aline Petrich
- Department of Pharmacology and Toxicology, Jena University Hospital - Friedrich Schiller University Jena, Jena, Germany
| | - Florian Pöll
- Department of Pharmacology and Toxicology, Jena University Hospital - Friedrich Schiller University Jena, Jena, Germany
| | - Stefan Schulz
- Department of Pharmacology and Toxicology, Jena University Hospital - Friedrich Schiller University Jena, Jena, Germany
- * E-mail: .
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24
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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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25
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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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26
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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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27
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Nagel F, Doll C, Pöll F, Kliewer A, Schröder H, Schulz S. Structural determinants of agonist-selective signaling at the sst(2A) somatostatin receptor. Mol Endocrinol 2011; 25:859-66. [PMID: 21330405 DOI: 10.1210/me.2010-0407] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The clinically used somatostatin (SS-14) analogs octreotide and pasireotide (SOM230) stimulate distinct species-specific patterns of sst(2A) somatostatin receptor phosphorylation and internalization. Like SS-14, 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 endocytosis of both rat and human sst(2A) receptors. Unlike SS-14, pasireotide fails to induce any substantial phosphorylation or internalization of the rat sst(2A) receptor. Nevertheless, pasireotide is able to stimulate a selective phosphorylation of S341 and S343 of the human sst(2A) receptor followed by a clearly detectable receptor sequestration. Here, we show that transplantation of amino acids 1-180 of the human sst(2A) receptor to the rat sst(2A) receptor facilitates pasireotide-induced internalization. Conversely, construction of a rat-human sst(2A) chimera conferred resistance to pasireotide-induced internalization. We then created a series of site-directed mutants leading to the identification of amino acids 27, 30, 163, and 164 that when exchanged to their human counterparts facilitated pasireotide-driven S341/S343 phosphorylation and internalization of the rat sst(2A) receptor. Exchange of these amino acids to their rat counterparts completely blocked the pasireotide-mediated internalization of the human sst(2A) receptor. Notably, octreotide and SS-14 stimulated a full phosphorylation and internalization of all mutant sst(2A) receptors tested. Together, these findings suggest that pasireotide activates the sst(2A) receptor via a molecular switch that is structurally and functionally distinct from that turned on during octreotide-driven sst(2A) activation.
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Affiliation(s)
- Falko Nagel
- Department of Pharmacology and Toxicology, University Hospital Jena, Friedrich Schiller University, Drackendorfer Strasse 1, D-07747 Jena, Germany
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28
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Arnaldi G, Boscaro M. Pasireotide for the treatment of Cushing's disease. Expert Opin Investig Drugs 2010; 19:889-98. [DOI: 10.1517/13543784.2010.495943] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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29
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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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30
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Ben-Shlomo A, Melmed S. Pituitary somatostatin receptor signaling. Trends Endocrinol Metab 2010; 21:123-33. [PMID: 20149677 PMCID: PMC2834886 DOI: 10.1016/j.tem.2009.12.003] [Citation(s) in RCA: 134] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Revised: 12/09/2009] [Accepted: 12/10/2009] [Indexed: 12/27/2022]
Abstract
Somatotropin-release inhibitory factor (SRIF) is a major regulator of pituitary function, mostly inhibiting hormone secretion and to a lesser extent pituitary cell growth. Five SRIF receptor subtypes (SSTR1-5) are ubiquitously expressed G-protein coupled receptors. In the pituitary, SSTR1, 2, 3 and 5 are expressed, with SSTR2 and SSTR5 predominating. As new SRIF analogs have recently been introduced for treatment of pituitary disease, we evaluate the current knowledge of cell-specific pituitary SRIF receptor signaling and highlight areas of future research for comprehensive understanding of these mechanisms. Elucidating pituitary SRIF receptor signaling enables understanding of pituitary hormone secretion and cell growth, and also encourages future therapeutic development for pituitary disorders.
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Affiliation(s)
- Anat Ben-Shlomo
- Pituitary Center, Department of Medicine, Cedars Sinai Medical Center, Los Angeles, California 90048, USA
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31
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Pöll F, Lehmann D, Illing S, Ginj M, Jacobs S, Lupp A, Stumm R, Schulz S. Pasireotide and octreotide stimulate distinct patterns of sst2A somatostatin receptor phosphorylation. Mol Endocrinol 2010; 24:436-46. [PMID: 20051480 DOI: 10.1210/me.2009-0315] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Pasireotide (SOM230) is currently under clinical evaluation as a successor compound to octreotide for the treatment of acromegaly, Cushing's disease, and carcinoid tumors. Whereas octreotide acts primarily via the sst(2A) somatostatin receptor, pasireotide was designed to exhibit octreotide-like sst(2A) activity combined with enhanced binding to other somatostatin receptor subtypes. In the present study, we used phophosite-specific antibodies to examine agonist-induced phosphorylation of the rat sst(2A) receptor. We show that somatostatin and octreotide stimulate the complete phosphorylation of a cluster of four threonine residues within the cytoplasmic (353)TTETQRT(359) motif in a variety of cultured cell lines in vitro as well as in intact animals in vivo. This phosphorylation was mediated by G protein-coupled receptor kinases (GRK) 2 and 3 and followed by rapid cointernalization of the receptor and ss-arrestin into the same endocytic vesicles. In contrast, pasireotide failed to promote substantial phosphorylation and internalization of the rat sst(2A) receptor. In the presence of octreotide or SS-14, SOM230 showed partial agonist behavior, inhibiting phosphorylation, and internalization of sst(2A). Upon overexpression of GRK2 or GRK3, pasireotide stimulated selective phosphorylation of Thr356 and Thr359 but not of Thr353 or Thr354 within the (353)TTETQRT(359) motif. Pasireotide-mediated phosphorylation led to the formation of relatively unstable beta-arrestin-sst(2A) complexes that dissociated at or near the plasma membrane. Thus, octreotide and pasireotide are equally active in inducing classical G protein-dependent signaling via the sst(2A) somatostatin receptor. Yet, we find that they promote strikingly different patterns of sst(2A) receptor phosphorylation and, hence, stimulate functionally distinct pools of beta-arrestin.
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Affiliation(s)
- Florian Pöll
- Department of Pharmacology and Toxicology, Friedrich-Schiller-University, Drackendorfer Strasse 1, D-07747 Jena, Germany
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