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Newman-Tancredi A, Depoortère RY, Kleven MS, Kołaczkowski M, Zimmer L. Translating biased agonists from molecules to medications: Serotonin 5-HT 1A receptor functional selectivity for CNS disorders. Pharmacol Ther 2021; 229:107937. [PMID: 34174274 DOI: 10.1016/j.pharmthera.2021.107937] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 06/01/2021] [Accepted: 06/17/2021] [Indexed: 12/18/2022]
Abstract
Biased agonism (or "functional selectivity") at G-protein-coupled receptors has attracted rapidly increasing interest as a means to improve discovery of more efficacious and safer pharmacotherapeutics. However, most studies are limited to in vitro tests of cellular signaling and few biased agonists have progressed to in vivo testing. As concerns 5-HT1A receptors, which exert a major control of serotonergic signaling in diverse CNS regions, study of biased agonism has previously been limited by the poor target selectivity and/or partial agonism of classically available ligands. However, a new generation of highly selective, efficacious and druggable agonists has advanced the study of biased agonism at this receptor and created new therapeutic opportunities. These novel agonists show differential properties for G-protein signaling, cellular signaling (particularly pERK), electrophysiological effects, neurotransmitter release, neuroimaging by PET and pharmacoMRI, and behavioral tests of mood, motor activity and side effects. Overall, NLX-101 (a.k.a. F15599) exhibits preferential activation of cortical and brain stem 5-HT1A receptors, whereas NLX-112 (a.k.a. befiradol or F13640) shows prominent activation of 5-HT1A autoreceptors in Raphe nuclei and in regions associated with motor control. Accordingly, NLX-101 is potently active in rodent models of depression and respiratory control, whereas NLX-112 shows promising activity in models of Parkinson's disease across several species - rat, marmoset and macaque. Moreover, NLX-112 has also been labeled with 18F to produce the first agonist PET radiopharmaceutical (known as [18F]-F13640) for investigation of the active state of 5-HT1A receptors in rodent, primate and human. The structure-functional activity relationships of biased agonists have been investigated by receptor modeling and novel compounds have been identified which exhibit increased affinity at 5-HT1A receptors and new profiles of cellular signaling bias, notably for β-arrestin recruitment versus pERK. Taken together, the data suggest that 5-HT1A receptor biased agonists constitute potentially superior pharmacological agents for treatment of CNS disorders involving serotonergic mechanisms.
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Affiliation(s)
| | | | | | | | - Luc Zimmer
- Université Claude Bernard Lyon1, Lyon, France; Hospices Civils de Lyon, Lyon, France; Lyon Neuroscience Research Center, CNRS-INSERM, France
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Tran HQ, Shin EJ, Hoai Nguyen BC, Phan DH, Kang MJ, Jang CG, Jeong JH, Nah SY, Mouri A, Saito K, Nabeshima T, Kim HC. 5-HT 1A receptor agonist 8-OH-DPAT induces serotonergic behaviors in mice via interaction between PKCδ and p47phox. Food Chem Toxicol 2018; 123:125-141. [PMID: 30366073 DOI: 10.1016/j.fct.2018.10.049] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Revised: 10/18/2018] [Accepted: 10/22/2018] [Indexed: 12/22/2022]
Abstract
Serotonin syndrome is an adverse reaction due to increased serotonin (5-hydroxytryptophan: 5-HT) concentrations in the central nervous system (CNS). The full 5-HT1A receptor (5-HT1AR) agonist (±)-8-hydroxy-dipropylaminotetralin (8-OH-DPAT) has been recognized to elicit traditional serotonergic behaviors. Treatment with 8-OH-DPAT selectively increased PKCδ expression out of PKC isoforms and 5-HT turnover rate in the hypothalamus of wild-type mice. Treatment with 8-OH-DPAT resulted in oxidative burdens, co-immunoprecipitation of 5-HT1AR and PKCδ, and phosphorylation and membrane translocation of p47phox. Importantly, p47phox also interacted with 5-HT1AR or PKCδ in the presence of 8-OH-DPAT. Consistently, the interaction and oxidative burdens were attenuated by 5-HT1AR antagonism (i.e., WAY100635), PKCδ inhibition (i.e., rottlerin and genetic depletion of PKCδ), or NADPH oxidase/p47phox inhibition (i.e., apocynin and genetic depletion of p47phox). However, WAY100635, apocynin, or rottlerin did not exhibit any additive effects against the protective effect by inhibition of PKCδ or p47phox. Furthermore, apocynin, rottlerin, or WAY100635 also significantly protected from pro-inflammatory/pro-apoptotic changes induced by 8-OH-DPAT. Therefore, we suggest that 8-OH-DPAT-induced serotonergic behaviors requires oxidative stress, pro-inflammatory, and pro-apoptotic changes, that PKCδ or p47phox mediates the serotonergic behaviors induced by 8-OH-DPAT, and that the inhibition of PKCδ-dependent p47phox activation is critical for protecting against serotonergic behaviors.
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Affiliation(s)
- Hai-Quyen Tran
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Eun-Joo Shin
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Bao-Chau Hoai Nguyen
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Dieu-Hien Phan
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Min-Ji Kang
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Choon-Gon Jang
- Department of Pharmacology, School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Ji Hoon Jeong
- Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Seung-Yeol Nah
- Ginsentology Research Laboratory and Department of Physiology, College of Veterinary Medicine, Konkuk University, Seoul, 05029, Republic of Korea
| | - Akihiro Mouri
- Advanced Diagnostic System Research Laboratory, Fujita Health University Graduate School of Health Science, Aichi, 470-1192, Japan
| | - Kuniaki Saito
- Advanced Diagnostic System Research Laboratory, Fujita Health University Graduate School of Health Science, Aichi, 470-1192, Japan
| | - Toshitaka Nabeshima
- Advanced Diagnostic System Research Laboratory, Fujita Health University Graduate School of Health Science, Aichi, 470-1192, Japan; Aino University, Ibaraki, 576-0012, Japan; Japanese Drug Organization of Appropriate and Research, Nagoya, 468-0069, Japan
| | - Hyoung-Chun Kim
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea.
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Tran HQ, Lee Y, Shin EJ, Jang CG, Jeong JH, Mouri A, Saito K, Nabeshima T, Kim HC. PKCδ Knockout Mice Are Protected from Dextromethorphan-Induced Serotonergic Behaviors in Mice: Involvements of Downregulation of 5-HT 1A Receptor and Upregulation of Nrf2-Dependent GSH Synthesis. Mol Neurobiol 2018; 55:7802-7821. [PMID: 29468562 DOI: 10.1007/s12035-018-0938-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 01/28/2018] [Indexed: 12/12/2022]
Abstract
We investigated whether a specific serotonin (5-HT) receptor-mediated mechanism was involved in dextromethorphan (DM)-induced serotonergic behaviors. We firstly observed that the activation of 5-HT1A receptor, but not 5-HT2A receptor, contributed to DM-induced serotonergic behaviors in mice. We aimed to determine whether the upregulation of 5-HT1A receptor induced by DM facilitates the specific induction of certain PKC isoform, because previous reports suggested that 5-HT1A receptor activates protein kinase C (PKC). A high dose of DM (80 mg/kg, i.p.) induced a selective induction of PKCδ out of PKCα, PKCβI, PKCβII, PKCξ, and PKCδ in the hypothalamus of wild-type (WT) mice. More importantly, 5-HT1A receptor co-immunoprecipitated PKCδ in the presence of DM. Consistently, rottlerin, a pharmacological inhibitor of PKCδ, or PKCδ knockout significantly protected against increases in 5-HT1A receptor gene expression, 5-HT turnover rate, and serotonergic behaviors induced by DM. Treatment with DM resulted in an initial increase in nuclear factor erythroid-2-related factor 2 (Nrf2) nuclear translocation and DNA-binding activity, γ-glutamylcysteine (GCL) mRNA expression, and glutathione (GSH) level. This compensative induction was further potentiated by rottlerin or PKCδ knockout. However, GCL mRNA and GSH/GSSG levels were decreased 6 and 12 h post-DM. These decreases were attenuated by PKCδ inhibition. Our results suggest that interaction between 5-HT1A receptor and PKCδ is critical for inducing DM-induced serotonergic behaviors and that inhibition of PKCδ attenuates the serotonergic behaviors via downregulation of 5-HT1A receptor and upregulation of Nrf2-dependent GSH synthesis.
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MESH Headings
- Acetophenones/pharmacology
- Animals
- Behavior, Animal
- Benzopyrans/pharmacology
- Cell Nucleus/drug effects
- Cell Nucleus/metabolism
- Dextromethorphan
- Down-Regulation
- Glutamate-Cysteine Ligase/genetics
- Glutamate-Cysteine Ligase/metabolism
- Glutathione/biosynthesis
- Glutathione Disulfide/metabolism
- Hypothalamus/metabolism
- Hypothermia, Induced
- Isoenzymes/metabolism
- Mice, Inbred C57BL
- Mice, Knockout
- NF-E2-Related Factor 2/metabolism
- Neuroprotective Agents/pharmacology
- Phosphorylation/drug effects
- Piperazines/pharmacology
- Protein Kinase C-delta/metabolism
- Pyridines/pharmacology
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Receptor, Serotonin, 5-HT1A/metabolism
- Receptor, Serotonin, 5-HT2A/metabolism
- Serotonin/metabolism
- Serotonin 5-HT1 Receptor Antagonists/pharmacology
- Time Factors
- Up-Regulation
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Affiliation(s)
- Hai-Quyen Tran
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Youngho Lee
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea
| | - Eun-Joo Shin
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea.
| | - Choon-Gon Jang
- Department of Pharmacology, School of Pharmacy, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Ji Hoon Jeong
- Department of Pharmacology, College of Medicine, Chung-Ang University, Seoul, 06974, Republic of Korea
| | - Akihiro Mouri
- Advanced Diagnostic System Research Laboratory, Fujita Health University Graduate School of Health Science, Toyoake, Aichi, 470-1192, Japan
| | - Kuniaki Saito
- Advanced Diagnostic System Research Laboratory, Fujita Health University Graduate School of Health Science, Toyoake, Aichi, 470-1192, Japan
| | - Toshitaka Nabeshima
- Advanced Diagnostic System Research Laboratory, Fujita Health University Graduate School of Health Science, Toyoake, Aichi, 470-1192, Japan
- Aino University, Ibaraki, 576-0012, Japan
- Japanese Drug Organization of Appropriate and Research, Nagoya, 468-0069, Japan
| | - Hyoung-Chun Kim
- Neuropsychopharmacology and Toxicology Program, College of Pharmacy, Kangwon National University, Chunchon, 24341, Republic of Korea.
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Nievergelt A, Huonker P, Schoop R, Altmann KH, Gertsch J. Identification of serotonin 5-HT1A receptor partial agonists in ginger. Bioorg Med Chem 2010; 18:3345-51. [PMID: 20363635 DOI: 10.1016/j.bmc.2010.02.062] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 02/24/2010] [Accepted: 02/28/2010] [Indexed: 01/14/2023]
Abstract
Animal studies suggest that ginger (Zingiber officinale Roscoe) reduces anxiety. In this study, bioactivity-guided fractionation of a ginger extract identified nine compounds that interact with the human serotonin 5-HT(1A) receptor with significant to moderate binding affinities (K(i)=3-20 microM). [(35)S]-GTP gamma S assays indicated that 10-shogaol, 1-dehydro-6-gingerdione, and particularly the whole lipophilic ginger extract (K(i)=11.6 microg/ml) partially activate the 5-HT(1A) receptor (20-60% of maximal activation). In addition, the intestinal absorption of gingerols and shogaols was simulated and their interactions with P-glycoprotein were measured, suggesting a favourable pharmacokinetic profile for the 5-HT(1A) active compounds.
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Affiliation(s)
- Andreas Nievergelt
- Department of Chemistry and Applied Biosciences, ETH 8093 Zurich, Switzerland
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Feng JJ, Cheng FC, Lin CH, Wei JW, Yang SD. Discovery and characterization of [3H]8-OH-DPAT binding to HeLaS3 cells. Arch Biochem Biophys 2010; 495:14-20. [PMID: 20018167 DOI: 10.1016/j.abb.2009.12.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Revised: 12/03/2009] [Accepted: 12/06/2009] [Indexed: 11/30/2022]
Abstract
Some G protein-coupled receptors (GPCRs) have functional links to cancer biology, yet the manifestation of GPCRs in tumor types is little studied to date. Using a battery of radioligand binding assays, we sought to characterize GPCR recognition binding sites on HeLaS3 tumor cells. High levels of binding of the selective serotonin 5-HT(1A) receptor agonist [3H]8-OH-DPAT were observed in these cells. Saturation and homologous competition experiments indicated that [3H]8-OH-DPAT bound different populations of high- and low-affinity sites. In competition experiments, several serotonergic compounds displaced [3H]8-OH-DPAT binding with low potency from its high-affinity binding sites, suggesting that low-affinity binding is the predominant mode of binding. A variety of drugs targeting different classes of receptors did not affect [3H]8-OH-DPAT binding. These observations may help elucidate the pathophysiological and functional relevance of 5-HT receptors in tumor cells and link GPCRs and tumorigenic mechanisms to pharmacological and chemotherapeutic paradigms.
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Affiliation(s)
- Jin-Jye Feng
- Institute of Molecular and Cellular Biology, National Tsing Hua University, 101 Section 2 Kuang-Fu Road, Hsinchu 30013, Taiwan, ROC.
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6
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Otoshi CK, Walwyn WM, Tillakaratne NJ, Zhong H, Roy RR, Edgerton VR. Distribution and localization of 5-HT(1A) receptors in the rat lumbar spinal cord after transection and deafferentation. J Neurotrauma 2009; 26:575-84. [PMID: 19260781 PMCID: PMC2828940 DOI: 10.1089/neu.2008.0640] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The serotonergic system is highly plastic, capable of adapting to changing afferent information in diverse mammalian systems. We hypothesized that removing supraspinal and/or peripheral input would play an important role in defining the distribution of one of the most prevalent serotonergic receptors, the 5-HT(1A) receptor (R), in the spinal cord. We investigated the distribution of this receptor in response to a complete thoracic (T7-T8) spinal cord transection (eliminating supraspinal input), or to spinal cord isolation (eliminating both supraspinal and peripheral input) in adult rats. Using two antibodies raised against either the second extracellular region (ECL(2)) or the third intracellular region (ICL(3)) of the 5-HT(1A)R, we compared the 5-HT(1A)R levels and distributions in specific laminae of the L3-L5 segments among the control, spinal cord-transected, and spinal cord-isolated groups. Each antibody labeled different populations of 5-HT(1A)R: ECL(2) labeled receptors in the axon hillock, whereas ICL(3) labeled receptors predominantly throughout the soma and proximal dendrites. Spinal cord transection increased the number of ECL(2)-positive cells in the medial region of laminae III-IV and lamina VII, and the mean length of the labeled axon hillocks in lamina IX. The number of ICL(3)-labeled cells was higher in lamina VII and in both the medial and lateral regions of lamina IX in the spinal cord-transected compared to the control group. In contrast, the length and number of ECL(2)-immunolabeled processes and ICL(3)-immunolabeled cells were similar in the spinal cord-isolated and control groups. Combined, these data demonstrate that the upregulation in 5-HT(1A)R that occurs with spinal cord transection alone is dependent on the presence of sensory input.
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Affiliation(s)
- Chad K. Otoshi
- Department of Physiological Science, University of California-Los Angeles, Los Angeles, California
| | - Wendy M. Walwyn
- Department of Psychiatry and Biobehavioral Science, University of California-Los Angeles, Los Angeles, California
| | - Niranjala J.K. Tillakaratne
- Department of Physiological Science, University of California-Los Angeles, Los Angeles, California
- Brain Research Institute, University of California-Los Angeles, Los Angeles, California
| | - Hui Zhong
- Department of Physiological Science, University of California-Los Angeles, Los Angeles, California
| | - Roland R. Roy
- Department of Physiological Science, University of California-Los Angeles, Los Angeles, California
- Brain Research Institute, University of California-Los Angeles, Los Angeles, California
| | - V. Reggie Edgerton
- Department of Physiological Science, University of California-Los Angeles, Los Angeles, California
- Brain Research Institute, University of California-Los Angeles, Los Angeles, California
- Department of Neurobiology, University of California-Los Angeles, Los Angeles, California
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7
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Ogren SO, Eriksson TM, Elvander-Tottie E, D'Addario C, Ekström JC, Svenningsson P, Meister B, Kehr J, Stiedl O. The role of 5-HT(1A) receptors in learning and memory. Behav Brain Res 2008; 195:54-77. [PMID: 18394726 DOI: 10.1016/j.bbr.2008.02.023] [Citation(s) in RCA: 248] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Revised: 02/13/2008] [Accepted: 02/13/2008] [Indexed: 12/12/2022]
Abstract
The ascending serotonin (5-HT) neurons innervate the cerebral cortex, hippocampus, septum and amygdala, all representing brain regions associated with various domains of cognition. The 5-HT innervation is diffuse and extensively arborized with few synaptic contacts, which indicates that 5-HT can affect a large number of neurons in a paracrine mode. Serotonin signaling is mediated by 14 receptor subtypes with different functional and transductional properties. The 5-HT(1A) subtype is of particular interest, since it is one of the main mediators of the action of 5-HT. Moreover, the 5-HT(1A) receptor regulates the activity of 5-HT neurons via autoreceptors, and it regulates the function of several neurotransmitter systems via postsynaptic receptors (heteroreceptors). This review assesses the pharmacological and genetic evidence that implicates the 5-HT(1A) receptor in learning and memory. The 5-HT(1A) receptors are in the position to influence the activity of glutamatergic, cholinergic and possibly GABAergic neurons in the cerebral cortex, hippocampus and in the septohippocampal projection, thereby affecting declarative and non-declarative memory functions. Moreover, the 5-HT(1A) receptor regulates several transduction mechanisms such as kinases and immediate early genes implicated in memory formation. Based on studies in rodents the stimulation of 5-HT(1A) receptors generally produces learning impairments by interfering with memory-encoding mechanisms. In contrast, antagonists of 5-HT(1A) receptors facilitate certain types of memory by enhancing hippocampal/cortical cholinergic and/or glutamatergic neurotransmission. Some data also support a potential role for the 5-HT(1A) receptor in memory consolidation. Available results also implicate the 5-HT(1A) receptor in the retrieval of aversive or emotional memories, supporting an involvement in reconsolidation. The contribution of 5-HT(1A) receptors in cognitive impairments in various psychiatric disorders is still unclear. However, there is evidence that 5-HT(1A) receptors may play differential roles in normal brain function and in psychopathological states. Taken together, the evidence indicates that the 5-HT(1A) receptor is a target for novel therapeutic advances in several neuropsychiatric disorders characterized by various cognitive deficits.
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Affiliation(s)
- Sven Ove Ogren
- Department of Neuroscience, Karolinska Institutet, SE-17177 Stockholm, Sweden.
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Turner JH, Garnovskaya MN, Raymond JR. Serotonin 5-HT1A receptor stimulates c-Jun N-terminal kinase and induces apoptosis in Chinese hamster ovary fibroblasts. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2007; 1773:391-9. [PMID: 17208318 DOI: 10.1016/j.bbamcr.2006.12.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2006] [Revised: 11/30/2006] [Accepted: 12/04/2006] [Indexed: 01/07/2023]
Abstract
The 5-HT1A receptor is a prototypical member of the large and diverse serotonin receptor family. One key role of this receptor is to stimulate cell proliferation and differentiation via the extracellular signal regulated protein kinase (ERK) mitogen activated protein (MAP) kinase. There are few reports on the ability of the 5-HT1A receptor to modulate other MAP kinases such as c-Jun N-terminal kinase (JNK), which is activated by various extracellular stimuli, resulting in cell growth, differentiation, and programmed cell death. We report here for the first time that the 5-HT1A receptor stimulates JNK. JNK stimulation was Pertussis toxin-sensitive and was mediated by Rho family low molecular weight GTPases. The 5-HT1A receptor also increased apoptosis, which was mimicked by the MEK inhibitor PD98059, and blocked by the JNK inhibitor SP600125. These results suggest that the 5-HT1A receptor stimulates both ERK-dependent anti-apoptotic pathways and JNK-dependent pro-apoptotic pathways in CHO cells.
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Affiliation(s)
- Justin H Turner
- The Medical and Research Services of the Ralph H. Johnson Veterans Affairs Medical Center, Department of Medicine (Nephrology Division) of the Medical University of South Carolina, Charleston, SC 29425, USA
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9
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Bøttger P, Hede SE, Grunnet M, Høyer B, Klaerke DA, Pedersen L. Characterization of transport mechanisms and determinants critical for Na+-dependent Pi symport of the PiT family paralogs human PiT1 and PiT2. Am J Physiol Cell Physiol 2006; 291:C1377-87. [PMID: 16790504 DOI: 10.1152/ajpcell.00015.2006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The general phosphate need in mammalian cells is accommodated by members of the P(i) transport (PiT) family (SLC20), which use either Na(+) or H(+) to mediate inorganic phosphate (P(i)) symport. The mammalian PiT paralogs PiT1 and PiT2 are Na(+)-dependent P(i) (NaP(i)) transporters and are exploited by a group of retroviruses for cell entry. Human PiT1 and PiT2 were characterized by expression in Xenopus laevis oocytes with (32)P(i) as a traceable P(i) source. For PiT1, the Michaelis-Menten constant for P(i) was determined as 322.5 +/- 124.5 microM. PiT2 was analyzed for the first time and showed positive cooperativity in P(i) uptake with a half-maximal activity constant for P(i) of 163.5 +/- 39.8 microM. PiT1- and PiT2-mediated Na(+)-dependent P(i) uptake functions were not significantly affected by acidic and alkaline pH and displayed similar Na(+) dependency patterns. However, only PiT2 was capable of Na(+)-independent P(i) transport at acidic pH. Study of the impact of divalent cations Ca(2+) and Mg(2+) revealed that Ca(2+) was important, but not critical, for NaP(i) transport function of PiT proteins. To gain insight into the NaP(i) cotransport function, we analyzed PiT2 and a PiT2 P(i) transport knockout mutant using (22)Na(+) as a traceable Na(+) source. Na(+) was transported by PiT2 even without P(i) in the uptake medium and also when P(i) transport function was knocked out. This is the first time decoupling of P(i) from Na(+) transport has been demonstrated for a PiT family member. Moreover, the results imply that putative transmembrane amino acids E(55) and E(575) are responsible for linking P(i) import to Na(+) transport in PiT2.
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Affiliation(s)
- Pernille Bøttger
- Department of Molecular Biology, Institute of Clinical Medicine, University of Aarhus, Aarhus, Denmark
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10
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Turner JH, Gelasco AK, Raymond JR. Calmodulin Interacts with the Third Intracellular Loop of the Serotonin 5-Hydroxytryptamine1A Receptor at Two Distinct Sites. J Biol Chem 2004; 279:17027-37. [PMID: 14752100 DOI: 10.1074/jbc.m313919200] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The serotonin 5-HT(1A) receptor couples to heterotrimeric G proteins and intracellular second messengers, yet no studies have investigated the possible role of additional receptor-interacting proteins in 5-HT(1A) receptor signaling. We have found that the ubiquitous Ca(2+)-sensor calmodulin (CaM) co-immunoprecipitates with the 5-HT(1A) receptor in Chinese hamster ovary fibroblasts. The human 5-HT(1A) receptor contains two putative CaM binding motifs, located in the N- and C-terminal juxtamembrane regions of the third intracellular loop of the receptor. Peptides encompassing both the N-terminal (i3N) and C-terminal (i3C) CaM-binding domains were tested for CaM binding. Using in vitro binding assays in combination with gel shift analysis, we demonstrated Ca(2+)-dependent formation of complexes between CaM and both peptides. We determined kinetic data using a combination of BIAcore surface plasmon resonance (SPR) and dansyl-CaM fluorescence. SPR analysis gave an apparent K(D) of approximately 110 nm for the i3N peptide and approximately 700 nm for the i3C peptide. Both peptides also caused characteristic shifts in the fluorescence emission spectrum of dansyl-CaM, with apparent affinities of 87 +/- 23 nm and 1.70 +/- 0.16 microm. We used bioluminescence resonance energy transfer to show that CaM interacts with the 5-HT(1A) receptor in living cells, representing the first in vivo evidence of a G protein-coupled receptor interacting with CaM. Finally, we showed that CaM binding and phosphorylation of the 5-HT(1A) receptor i3 loop peptides by protein kinase C are antagonistic in vitro, suggesting a possible role for CaM in the regulation of 5-HT(1A) receptor phosphorylation and desensitization. These data suggest that the 5-HT(1A) receptor contains high and moderate affinity CaM binding regions that may play important roles in receptor signaling and function.
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Affiliation(s)
- Justin H Turner
- Medical and Research Services of the Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina, USA
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Salaün C, Gyan E, Rodrigues P, Heard JM. Pit2 assemblies at the cell surface are modulated by extracellular inorganic phosphate concentration. J Virol 2002; 76:4304-11. [PMID: 11932396 PMCID: PMC155110 DOI: 10.1128/jvi.76.9.4304-4311.2002] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pit2 is a type III sodium-dependent phosphate transporter and the cell surface receptor for amphotropic murine leukemia virus. Indirect arguments have previously suggested that retrovirus receptor assembly play a role in triggering membrane fusion. Using CHO cells expressing physiological amounts of functional versions of human Pit2 fused to various tagging epitopes, we provide evidence that Pit2 forms assemblies at the cell surface. Living cells were exposed to cross-linking reagents and protein extracts were treated with trifluoroacetic acid (TFA), a chemical that destroys all protein interactions but covalent links. Assemblies were also detected in the absence of cross-linking and TFA treatment, indicating that they are partially resistant to detergent denaturation. The formation of homo-oligomers was documented by the coimmunoprecipitation of differently tagged molecules. The amounts of Pit2 assemblies detected in the presence or in the absence of cross-linking reagents varied with extracellular inorganic phosphate concentration ([P(i)]). Variation of signal intensity was in the range of twofold, occurred in the absence of de novo protein synthesis and took place at the cell surface. These results indicate that Pit2 assemblies exhibit variable conformations at the surface of living cells. Susceptibility to virus infection and phosphate uptake also vary with extracellular [P(i)]. A model is proposed in which cell surface Pit2 assemblies switch from a compacted to an expanded configuration in response to changes of extracellular [P(i)], and possible relationships with the variation of biological activities are discussed.
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Affiliation(s)
- Christine Salaün
- Unité Rétrovirus et Transfert Génétique, CNRS URA 1930, Institut Pasteur, 75724 Paris, France
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Raymond JR, Mukhin YV, Gelasco A, Turner J, Collinsworth G, Gettys TW, Grewal JS, Garnovskaya MN. Multiplicity of mechanisms of serotonin receptor signal transduction. Pharmacol Ther 2001; 92:179-212. [PMID: 11916537 DOI: 10.1016/s0163-7258(01)00169-3] [Citation(s) in RCA: 343] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The serotonin (5-hydroxytryptamine, 5-HT) receptors have been divided into 7 subfamilies by convention, 6 of which include 13 different genes for G-protein-coupled receptors. Those subfamilies have been characterized by overlapping pharmacological properties, amino acid sequences, gene organization, and second messenger coupling pathways. Post-genomic modifications, such as alternative mRNA splicing or mRNA editing, creates at least 20 more G-protein-coupled 5-HT receptors, such that there are at least 30 distinct 5-HT receptors that signal through G-proteins. This review will focus on what is known about the signaling linkages of the G-protein-linked 5-HT receptors, and will highlight some fascinating new insights into 5-HT receptor signaling.
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Affiliation(s)
- J R Raymond
- The Research Service of the Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC 29401, USA.
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Yamada K, Hasuo H, Ishimatsu M, Akasu T. Characterization of outward currents induced by 5-HT in neurons of rat dorsolateral septal nucleus. J Neurophysiol 2001; 85:1453-60. [PMID: 11287469 DOI: 10.1152/jn.2001.85.4.1453] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Properties of the 5-hydroxytryptamine (5-HT)-induced current (I(5-HT)) were examined in neurons of rat dorsolateral septal nucleus (DLSN) by using whole cell patch-clamp techniques. I(5-HT) was associated with an increase in the membrane conductance of DLSN neurons. The reversal potential of I(5-HT) was -93 +/- 6 (SE) mV (n = 7) in the artificial cerebrospinal fluid (ACSF) and was changed by 54 mV per decade change in the external K(+) concentration, indicating that I(5-HT) is carried exclusively by K(+). Voltage dependency of the K(+) conductance underlying I(5-HT) was investigated by using current-voltage relationship. I(5-HT) showed a linear I-V relation in 63%, inward rectification in 21%, and outward rectification in 16% of DLSN neurons. (+/-)-8-Hydroxy-dipropylaminotetralin hydrobromide (30 microM), a selective 5-HT(1A) receptor agonist, also produced outward currents with three types of voltage dependency. Ba(2+) (100 microM) blocked the inward rectifier I(5-HT) but not the outward rectifier I(5-HT). In I(5-HT) with linear I-V relation, blockade of the inward rectifier K(+) current by Ba(2+) (100 microM) unmasked the outward rectifier current in DLSN neurons. These results suggest that I(5-HT) with linear I-V relation is the sum of inward rectifier and outward rectifier K(+) currents in DLSN neurons. Intracellular application of guanosine-5'-O-(3-thiotriphosphate) (300 microM) and guanosine-5'-O-(2-thiodiphosphate) (5 mM), blockers of G protein, irreversibly depressed I(5-HT). Protein kinase C (PKC) 19-36 (20 microM), a specific PKC inhibitor, depressed the outward rectifier I(5-HT) but not the inward rectifier I(5-HT). I(5-HT) was depressed by N-ethylmaleimide, which uncouples the G-protein-coupled receptor from pertussis-toxin-sensitive G proteins. H-89 (10 microM) and adenosine 3',5'-cyclic monophosphothioate Rp-isomer (300 microM), protein kinase A inhibitors, did not depress I(5-HT). Phorbol 12-myristate 13-acetate (10 microM), an activator of PKC, produced an outward rectifying K(+) current. These results suggest that both 5-HT-induced inward and outward rectifying currents are mediated by a G protein and that PKC is probably involved in the transduction pathway of the outward rectifying I(5-HT) in DLSN neurons.
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Affiliation(s)
- K Yamada
- Department of Physiology, Kurume University School of Medicine, Kurume 830-0011, Japan
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Abstract
BACKGROUND Serotonin (5-HT) and dopamine (DA) are intrarenal autocrine/paracrine substances that regulate phosphate reabsorption. The present studies explored intrarenal serotonin and DA metabolism and the implications for phosphate homeostasis in rats with remnant kidneys, a model for renal failure. METHODS The intrarenal productions of serotonin and DA were determined from measurements of renal interstitial fluid (microdialysate) and urine in rats with remnant or intact kidneys. In clearance studies, the effects of infusion of methiothepin, a serotonin receptor antagonist, or gludopa, a renal selective DA precursor, on phosphate and sodium excretion were determined in rats with a remnant or intact kidneys. RESULTS Renal interstitial serotonin (5-HT, 3.4 +/- 0.9 pg/min) was fourfold higher than DA (0.6 +/- 0.1 pg/min) in remnant kidneys. Conversely, urinary excretion of serotonin was fourfold less than DA in rats with a remnant kidney (5-HT 0.4 +/- 0.02 vs. DA 1.5 +/- 0.1 ng/min). Infusion of methiothepin or gludopa significantly increased the fractional excretion of phosphate (FE(Pi)) in rats with a remnant kidney from 54 +/- 3 to 67 +/- 7% (P < 0.05) and from 36 +/- 10% to 51 +/- 13% (P < 0.05), respectively. CONCLUSION We conclude that serotonin preferentially accumulates in the renal interstitium, whereas DA exits primarily via the tubular lumen. Phosphate excretion is increased by both the acute infusion of the serotonin receptor antagonist and the infusion of gludopa, suggesting that both serotonin and DA modulate phosphate excretion in rats with remnant kidneys.
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Affiliation(s)
- T J Berndt
- Department of Medicine, Mayo Clinic and Mayo Foundation, Rochester, Minnesota 55905, USA
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15
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Gross JM, Berndt TJ, Knox FG. Effect of serotonin receptor antagonist on phosphate excretion. J Am Soc Nephrol 2000; 11:1002-1007. [PMID: 10820163 DOI: 10.1681/asn.v1161002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
To determine whether endogenous intrarenal 5-hydroxytryptamine affects phosphate excretion, the serotonin receptor antagonist methiothepin (20 microgram/kg, +6 microgram/kg per h) was infused into the renal interstitium of rats fed a normal phosphate diet (0.7% phosphate [Pi]) in the presence of endogenous parathyroid hormone (PTH). Renal interstitial infusion of methiothepin significantly increased fractional phosphate excretion (FE(Pi)) from 23 +/- 4 to 30 +/- 4% (n = 8, P < 0.05). To determine whether serotonin modulates the phosphaturic response to PTH during conditions of dietary phosphate excess or deprivation, rats were fed either a high (1.8% Pi, HPD) or low (0.07% Pi, LPD) phosphate diet, and methiothepin (100 microgram/kg, +30 microgram/kg per h) or saline vehicle was infused intravenously before and during PTH infusion (33 U/kg, +1 U/kg per min). Methiothepin infusion significantly increased FE(Pi) in thyroparathyroidectomized rats fed a HPD from 25 +/- 4 to 32 +/- 4% (n = 9, P < 0.05), and the subsequent administration of PTH further increased the FE(Pi) to 64 +/- 3% (P < 0.05). The increase in FE(Pi) during PTH infusion was similar in the absence (Delta27 +/- 5%, n = 7) and presence (Delta33 +/- 6%) of methiothepin, P > 0.05. In thyroparathyroidectomized rats fed a LPD, methiothepin infusion did not increase phosphate excretion (0.8 +/- 0.4 to 1.3 +/- 0.9%, n = 7, P > 0.05). However, the increase in FE(Pi) during PTH infusion was significantly greater in the presence of methiothepin (1.3 +/- 0.9 to 20.0 +/- 4.0%, Delta18.7 +/- 3.5%) than in the vehicle-infused rats (0.5 +/- 0.2 to 8.8 +/- 1.1%, Delta8.3 +/- 1.2%; n = 8, P < 0.05). In conclusion, these observations suggest that endogenous intrarenal serotonin enhances phosphate reabsorption in phosphate-replete rats, and attenuates the phosphaturic response to PTH in phosphate-deprived rats.
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Affiliation(s)
- Jennifer M Gross
- Departments of Medicine and Physiology and Biophysics, Mayo Clinic and Mayo Foundation, Rochester, Minnesota
| | - Theresa J Berndt
- Departments of Medicine and Physiology and Biophysics, Mayo Clinic and Mayo Foundation, Rochester, Minnesota
| | - Franklyn G Knox
- Departments of Medicine and Physiology and Biophysics, Mayo Clinic and Mayo Foundation, Rochester, Minnesota
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Raymond JR, Mukhin YV, Gettys TW, Garnovskaya MN. The recombinant 5-HT1A receptor: G protein coupling and signalling pathways. Br J Pharmacol 1999; 127:1751-64. [PMID: 10482904 PMCID: PMC1566169 DOI: 10.1038/sj.bjp.0702723] [Citation(s) in RCA: 195] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The 5-hydroxytryptamine 5-HT1A receptor was one of the first G protein coupled receptors whose cDNA and gene were isolated by molecular cloning methods. Transfection of the cDNA of this receptor into cells previously bearing no 5-HT receptors has resulted in the acquisition of large amounts of information regarding potential signal transduction pathways linked to the receptor, correlations of receptor structure to its various functions, and pharmacological properties of the receptor. Transfection studies with the 5-HT1A receptor have generated critical new information that might otherwise have been elusive. This information notably includes the discovery of unsuspected novel signalling linkages, the elucidation of the mechanisms of receptor desensitization, the refinement of models of the receptor pharmacophore, and the development of silent receptor antagonists, among others. The current review summarizes the most important studies of the recombinant 5-HT1A receptor in the decade since the identification of its cDNA.
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Affiliation(s)
- J R Raymond
- Division of Nephrology, Department of Medicine, Medical University of South Carolina and the Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29425, USA.
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17
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Onwochei MO, Ofori AO, Agodoa IL. Interaction between Na+/phosphate-cotransporter and the adrenoceptors in myocardial depression. J Cardiovasc Pharmacol 1998; 31:10-7. [PMID: 9456271 DOI: 10.1097/00005344-199801000-00002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The primary objective of this study was to test the hypothesis that an increase in the alpha1-adrenoceptor tone would potentiate the myocardial biphasic contractile response to inorganic phosphate [Pi, the substrate of Na/Pi-cotransporter (NP)]. A second aim was to determine whether activation of alpha1-adrenoceptor is necessary for the NP-mediated increase in myocardial contractility (+dP/dt). Earlier study from this laboratory showed that high concentration of Pi (10 mM) produces a biphasic contractile response: initial increase in +dP/dt was followed by decline. In another study, Pi (3.5 mM) potentiated phenylephrine (PHE)-induced increase in +dP/dt. The alpha1-adrenoceptor was not blocked in these studies, and it can still be activated by the electrical stimulation of the sympathetic nerve terminals to the heart. Additionally, alpha1-adrenoceptor-activated increases in the activity of NP have been reported in numerous studies in noncardiac tissues and cell lines; therefore it is not clear whether Pi-induced increase in +dP/dt occurs only in the presence of alpha1-adrenoceptor activation. This study was performed by using isolated perfused rat heart in the condition of controlled extracellular calcium activity (0.72 mM); fixed preload (15 mm Hg); and constant heart rate (280 beats/min) and coronary flow (8 ml/min). The electronically differentiated value of the left ventricular pressure (LVP) signal was used as an index of myocardial contractility. The data show that activation of the alpha1-adrenoceptor is not necessary for the Pi-induced increase in +dP/dt (i.e., NP-mediated increase in +dP/dt has both the alpha1-adrenoceptor-dependent and alpha1-adrenoceptor-independent components. The interaction between alpha1-adrenoceptor agonist (PHE) and Pi (10 mM) did not produce a biphasic myocardial contractile response in the presence of propranolol. Because our earlier data on myocardial biphasic contractile response to 10 mM Pi was obtained when neither the beta- nor the alpha-adrenoceptor was blocked, we carried out more studies to see whether beta-adrenoceptor plays a role in this Pi-induced biphasic response. When both the alpha- and beta-adrenoceptors were activated with norepinephrine (NE), myocardial depression by high Pi concentration was markedly potentiated. This myocardial depression did not occur in the presence of phosphonoformate, a selective inhibitor of NP. It also did not occur when alpha1-adrenoceptor was blocked. Our data suggest that alpha1- and beta-adrenoceptors do not interact with the cardiac NP to potentiate the Pi-induced biphasic contractile response, but they interact in a manner that potentiates Pi-induced myocardial depression.
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MESH Headings
- Adrenergic alpha-Antagonists/pharmacology
- Adrenergic beta-Antagonists/pharmacology
- Animals
- Cardiotonic Agents/pharmacology
- Carrier Proteins/drug effects
- Carrier Proteins/physiology
- Depression, Chemical
- Drug Interactions
- Male
- Myocardial Contraction/drug effects
- Norepinephrine/pharmacology
- Propranolol/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptors, Adrenergic, alpha/drug effects
- Receptors, Adrenergic, alpha/metabolism
- Receptors, Adrenergic, beta/drug effects
- Receptors, Adrenergic, beta/metabolism
- Sodium-Phosphate Cotransporter Proteins
- Symporters
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Affiliation(s)
- M O Onwochei
- Department of Pharmacology and Therapeutics, Medical College of Ohio, Toledo 43699-0008, USA
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18
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Gerhardt CC, van Heerikhuizen H. Functional characteristics of heterologously expressed 5-HT receptors. Eur J Pharmacol 1997; 334:1-23. [PMID: 9346322 DOI: 10.1016/s0014-2999(97)01115-1] [Citation(s) in RCA: 138] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Over the past 10 years, molecular cloning has revealed the presence of 15 serotonin (5-hydroxytryptamine; 5-HT) receptor subtypes, which can be subdivided in seven subfamilies. Except for the 5-HT3 receptors, which are ligand-gated ion channels, all 5-HT receptors belong to the superfamily of G-protein-coupled receptors. The large multiplicity of 5-HT receptor subtypes has been suggested to be a direct result of the evolutionary age of the 5-HT system. Molecular information on G-protein-coupled 5-HT receptors is currently available for several mammalian species as well as for a limited number of invertebrate species (insects, molluscs). The aim of this review is to give an overview of all cloned 5-HT receptor subtypes belonging to the superfamily of G-protein-coupled receptors with specific emphasis on the pharmacological and signaling properties of the receptors upon expression in several heterologous expression systems.
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MESH Headings
- Animals
- Aplysia/chemistry
- Drosophila/chemistry
- Gene Expression Regulation
- Humans
- Lymnaea/chemistry
- Receptor, Serotonin, 5-HT1B
- Receptor, Serotonin, 5-HT1D
- Receptor, Serotonin, 5-HT2A
- Receptor, Serotonin, 5-HT2C
- Receptors, Serotonin/classification
- Receptors, Serotonin/genetics
- Receptors, Serotonin/physiology
- Receptors, Serotonin, 5-HT1
- Receptors, Serotonin, 5-HT4
- Signal Transduction/physiology
- Terminology as Topic
- Receptor, Serotonin, 5-HT1F
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Affiliation(s)
- C C Gerhardt
- Department of Biochemistry and Molecular Biology, Research Institute Neurosciences, Vrije Universteit, Amsterdam, The Netherlands
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19
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Wright DE, Seroogy KB, Lundgren KH, Davis BM, Jennes L. Comparative localization of serotonin1A, 1C, and 2 receptor subtype mRNAs in rat brain. J Comp Neurol 1995; 351:357-73. [PMID: 7706547 DOI: 10.1002/cne.903510304] [Citation(s) in RCA: 424] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Serotonin (5-HT) mediates its effects on neurons in the central nervous system through a number of different receptor types. To gain better insight as to the localization of 5-HT responsive cells, the distribution of cells expressing mRNAs encoding the three 5-HT receptor subtypes 1A, 1C, and 2 was examined in rat brain with in situ hybridization using cRNA probes. 5-HT1A receptor mRNA labeling was most pronounced in the olfactory bulb, anterior hippocampal rudiment, septum, hippocampus (dentate gyrus and layers CA1-3), entorhinal cortex, interpeduncular nucleus, and medullary raphe nuclei. 5-HT1C receptor mRNA labeling was the most abundant and widespread of the three 5-HT receptor subtypes examined. Hybridization signal was densest in the choroid plexus, anterior olfactory nucleus, olfactory tubercle, piriform cortex, septum, subiculum, entorhinal cortex, claustrum, accumbens nucleus, striatum, lateral amygdala, paratenial and paracentral thalamic nuclei, subthalamic nucleus, substantia nigra, and reticular cell groups. 5-HT2 receptor mRNA was localized to the olfactory bulb, anterior hippocampal rudiment, frontal cortex, piriform cortex, entorhinal cortex, claustrum, pontine nuclei, and cranial nerve motor nuclei including the oculomotor, trigeminal motor, facial, dorsal motor nucleus of the vagus, and hypoglossal nuclei. The distributions of mRNAs for the three different 5-HT receptor subtypes overlap with regions that bind various 5-HT receptor-selective ligands and are present in nearly all areas known to receive serotonergic innervation. The results of this study demonstrate that neurons which express these 5-HT receptor subtypes are very widespread in the central nervous system, yet possess unique distributions within the rat brain. Moreover, previously unreported regions of 5-HT receptor subtype expression were observed, particularly with the 5-HT2 receptor riboprobe in the brainstem. Finally, several brain areas contain multiple 5-HT receptor subtype mRNAs, which leads to the possibility that individual cells may express more than one 5-HT receptor subtype.
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Affiliation(s)
- D E Wright
- Department of Anatomy and Neurobiology, University of Kentucky, Lexington 40536-0084
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20
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Abstract
In the last few years, molecular biology has led to the cloning and characterization of several 5-HT receptors (serotonin receptors) in vertebrates and in invertebrates. These studies have allowed identification not only of 5-HT receptors already described but also of novel subtypes. The molecular cloning of 13 different mammalian receptor subtypes revealed an unexpected heterogeneity among 5-HT receptors. Except for the 5-HT3 receptors which are ligand-gated ion channel receptors, all the other 5-HT receptors belong to the large family of receptors interacting with G proteins. Based on their amino acid sequence homology and coupling to second messengers these receptors can be divided into distinct families: the 5-HT1 family contains receptors that are negatively coupled to adenylate cyclase: the 5-HT2 family includes receptors that stimulate phospholipase C; the adenylyl cyclase stimulatory receptors are a heterogeneous group including the 5-HT4 receptor which has not yet been cloned, the Drosophila 5-HTdro1 receptor and two mammalian receptors tentatively named 5-HT6 and 5-HT7 receptors. The 5-HT5A and 5-HT5B receptors might constitute a new family of 5-HT receptors whose effectors are unknown. This review focusses on the molecular characteristics of the cloned 5-HT receptors such as their structure, their effector systems and their distribution within the central nervous system. The existence of a large number of receptors with distinct signalling properties and expression patterns might enable a single substance like 5-HT to generate simultaneously a large panel of effects in many brain structures. The availability of the genes encoding these receptors has already allowed a partial characterization of their structure-function relationship and will probably allow in the future a dissection of the contribution of each of these receptor subtypes to physiology and behaviour.
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Affiliation(s)
- F Saudou
- Laboratoire de Génétique Moléculaire des Eucaryotes du CNRS, Unité 184 de l'INSERM, Faculté de Médecine, Strasbourg, France
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21
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Gettys TW, Fields TA, Raymond JR. Selective activation of inhibitory G-protein alpha-subunits by partial agonists of the human 5-HT1A receptor. Biochemistry 1994; 33:4283-90. [PMID: 8155646 DOI: 10.1021/bi00180a024] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Plasma membranes from Chinese hamster ovary (CHO) cells transfected with the serotonin 5-HT1A receptor have been incubated with full or partial receptor agonists and the photoreactive GTP analog, 4-azidoanilido-[alpha-32P]-GTP ([32P]-AA-GTP), to characterize the resulting receptor-G-protein interactions. Subsequent solubilization and immunoprecipitation of the membranes with anti-G(i)alpha-2 or anti-G(i)alpha-3 immunoglobulins revealed that full and partial agonists produce concentration-dependent labeling of the respective G-proteins with [32P]-AA-GTP. Full agonists of the 5-HT1A receptor [serotonin 5-hydroxytryptamine (5-HT) and 8-hydroxy-2-(di-n-propylamino)tetraline (8-OH-DPAT)] produced a 7-12-fold increase in the labeling of G(i)alpha-2 and G(i)alpha-3, whereas partial agonists (rauwolscine and ipsapirone) produced a smaller incorporation (2-5-fold) of [32P]-AA-GTP by the same G-proteins. The concentration of agonist producing half-maximal binding of [32P]-AA-GTP by G(i)alpha-3 [5-HT, 48 +/- 1 nM; 8-OH-DPAT, 28 +/- 1 nM; ipsapirone, 22 +/- 6 nM] compared to G(i)alpha-2 [5-HT, 124 +/- 38 nM; 8-OH-DPAT, 40 +/- 1 nM, ipsapirone, 82 +/- 7 nM] was lower with all agonists except rauwolscine, where the EC50's were similar (G(i)alpha-2, 604 +/- 145 nM; Gi alpha-3, 708 +/- 130 nM).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- T W Gettys
- Department of Medicine, Medical University of South Carolina, Charleston 29425
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22
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Affiliation(s)
- F G Boess
- Department of Pharmacology, Faculty of Medicine, University of Alberta, Edmonton, Canada
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23
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Adham N, Vaysse PJ, Weinshank RL, Branchek TA. The cloned human 5-HT1E receptor couples to inhibition and activation of adenylyl cyclase via two distinct pathways in transfected BS-C-1 cells. Neuropharmacology 1994; 33:403-10. [PMID: 7984278 DOI: 10.1016/0028-3908(94)90070-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The pharmacological profile of coupling of the cloned human serotonin [5-hydroxytryptamine] (5-HT)1E receptors to second messengers was studied in African green monkey kidney cells (BS-C-1). At low concentrations (0.1-100 nM), 5-HT inhibited forskolin-stimulated cAMP accumulation (FSCA) by up to 90% whereas at higher concentrations it potentiated FSCA; potentiation was dependent on receptor density. Pretreatment of cells with pertussis toxin (PTx) or cholera toxin (CTx) eliminated agonist-induced inhibition and potentiation of FSCA, respectively. The potentiation of FSCA was not due to activation of phospholipase C and/or phospholipase A2 since 5-HT had no effect on inositol phosphate release, intracellular Ca2+ mobilization or arachidonic acid mobilization; neither was it affected by pretreatment with the nonselective phospholipase A2 inhibitor, quinacrine, or by the removal of extracellular Ca2+. The pharmacological profiles of the 5-HT1E receptor-mediated inhibition and potentiation of FSCA were very similar, although agonists displayed higher affinity for the former. These results indicate that the human 5-HT1E receptors can potentially couple, with similar pharmacological profiles, to multiple effector pathways. However, the potency and intrinsic activity of the compounds eliciting these responses can differ significantly, depending on the receptor density and the effector pathway studied.
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Affiliation(s)
- N Adham
- Synaptic Pharmaceutical Corporation, Paramus, N.J. 07652
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24
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Overexpressed protein kinase C-delta and -epsilon subtypes in NIH 3T3 cells exhibit differential subcellular localization and differential regulation of sodium-dependent phosphate uptake. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)37609-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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25
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Saudou F, Hen R. 5-Hydroxytryptamine receptor subtypes: molecular and functional diversity. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 1994; 30:327-80. [PMID: 7833295 DOI: 10.1016/s1054-3589(08)60178-7] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- F Saudou
- Département de Neurobiologie, Unité 184 de l'INSERM, Strasbourg, France
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26
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Raymond JR, Olsen CL, Gettys TW. Cell-specific physical and functional coupling of human 5-HT1A receptors to inhibitory G protein alpha-subunits and lack of coupling to Gs alpha. Biochemistry 1993; 32:11064-73. [PMID: 8218170 DOI: 10.1021/bi00092a016] [Citation(s) in RCA: 122] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We have studied the physical and functional linkages of heterologously expressed human 5-HT1A receptors to G protein alpha-subunits in HeLa and CHO-K1 cells. HeLa cells expressed immunoreactivity to G(i) proteins with an apparent rank order of G(i) alpha 3 (approximately 1 pmol/mg of protein) >> G(i) alpha 1 (approximately 0.1 pmol/mg) >> G(i) alpha 2 (< 0.02 pmol/mg), whereas CHO-K1 cells expressed immunoreactivity to G(i) alpha 2 (approximately 5 pmol/mg) >> G(i) alpha 3 (approximately 0.7 pmol/mg), but not to G(i) alpha 1. Both cell lines expressed large and small forms of Gs alpha, but neither expressed detectable G(o) alpha. Agonist-promotable physical coupling of the 5-HT1A receptor to G proteins was examined with high-affinity agonist binding and with co-immunoprecipitation using rabbit anti-receptor IgG fractions. Agonist treatment induced coupling of the 5-HT1A receptors to G proteins with an apparent rank order of G(i) alpha 3 > G(i) alpha 1, G(i) alpha 2 in HeLa cells and G(i) alpha 3 > G(i) alpha 2 in CHO-K1 cells. Agonist-promotable functional coupling of the 5-HT1A receptors to inhibition of adenylylcyclase was measured in membranes derived from HeLa and CHO-K1 cells expressing approximately 2.5-3 pmol of receptors/mg of protein by preincubation with antisera raised against the carboxyl termini of the G(i) protein alpha-subunits. A noteworthy difference between the two cell types was that antisera against the predominant G protein (G(i) alpha 2) were substantially more efficacious than G(i) alpha 3 antisera at blocking functional coupling to adenylylcyclase inhibition in CHO-K1 cells, whereas in HeLa cells, antisera against nonpredominant G proteins (G(i) alpha 1/G(i) alpha 2) were equally as effective as those against the predominant G protein (G(i) alpha 3). No physical or functional coupling of the 5-HT1A receptor to Gs alpha isoforms was detected in either cell line. These findings suggest that the 5-HT1A receptor can physically couple to multiple distinct G(i) proteins in mammalian cell membranes and that functional coupling to adenylylcyclase inhibition may be mediated by G(i) alpha 1, G(i) alpha 2, and G(i) alpha 3. One factor influencing the relative importance of those G proteins for 5-HT1A receptor-inhibited adenylylcyclase activity appears to be their-relative levels of expression.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J R Raymond
- Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710
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Arthur JM, Casañas SJ, Raymond JR. Partial agonist properties of rauwolscine and yohimbine for the inhibition of adenylyl cyclase by recombinant human 5-HT1A receptors. Biochem Pharmacol 1993; 45:2337-41. [PMID: 8517875 DOI: 10.1016/0006-2952(93)90208-e] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Previous studies by another group have suggested that the alpha 2-adrenergic receptor antagonist rauwolscine may function as an agonist at the serotonin1A (5-HT1A) receptor expressed in human brain. To directly test that hypothesis, we transfected the human 5-HT1A receptor cDNA into CHO cells and examined the ability of rauwolscine and its isomer, yohimbine, to inhibit ligand binding of [3H]-(+/-)-8-hydroxy-2-(di-n-propylamino)tetralin ([3H]8-OH-DPAT) and the activity of adenylyl cyclase in membranes derived from a single transformant that stably expresses approximately 225 fmol of 5-HT1A receptor/mg of membrane protein. Both ligands competitively antagonized the binding of [3H]8-OH-DPAT (Ki = 158 +/- 69 nM for rauwolscine and 690 +/- 223 nM for yohimbine), yielding shallow displacement curves consistent with agonist activity (Hill values = 0.69 +/- 0.2 for rauwolscine and 0.63 +/- 0.06 for yohimbine). Both ligands also inhibited forskolin-stimulated adenylyl cyclase activity in membranes derived from transfected (but not nontransfected) cells. For rauwolscine, the IC50 was 1.5 +/- 0.2 microM, and for yohimbine 4.6 +/- 1.0 microM, with activity ratios of 0.70 and 0.59, respectively, when compared to the full agonist serotonin. These studies demonstrated that rauwolscine and yohimbine are partial agonists for the human 5-HT1A receptor.
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Affiliation(s)
- J M Arthur
- Department of Medicine (Nephrology and Cardiology), Duke University Medical Center, Durham, NC 27710
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Lauder JM. Neurotransmitters as growth regulatory signals: role of receptors and second messengers. Trends Neurosci 1993; 16:233-40. [PMID: 7688165 DOI: 10.1016/0166-2236(93)90162-f] [Citation(s) in RCA: 587] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In the adult nervous system, neurotransmitters act as chemical mediators of intercellular communication by the activation of specific receptors and second messengers in postsynaptic cells. This specialized role may have evolved from more primitive functions in lower organisms where these substances were used as both intra- and intercellular signalling devices. This view derives from the finding that a number of 'classical' neurotransmitters are present in primitive organisms and early embryos in the absence of a nervous system, and pharmacological evidence that these substances regulate morphogenetic activities such as proliferation, differentiation, cell motility and metamorphosis. These phylogenetically old functions may be reiterated in the developing nervous system and in the humoral functions of neurotransmitters outside the nervous system. This review will provide evidence for this hypothesis based on the commonality of signal transduction mechanisms used in primitive organisms, early embryos and non-neuronal cells, and relate these relationships to the functions of neurotransmitters in the developing nervous system. This discussion has generally been limited to neurotransmitters where non-neuronal functions have been studied and information regarding the involvement of receptors and second messenger pathways is available.
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Affiliation(s)
- J M Lauder
- Dept of Cell Biology and Anatomy, University of North Carolina School of Medicine, Chapel Hill 27599-7090
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Oláh Z, Lehel C, Anderson WB. Differential effects of activation of protein kinase C and cyclic-AMP-dependent protein kinase on sodium-dependent phosphate uptake in NIH 3T3 cells. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1176:333-8. [PMID: 8471634 DOI: 10.1016/0167-4889(93)90063-u] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Activation of protein kinase C (PKC) by phorbol ester (PMA), or by diacylglycerol analogue (OAG) treatment of NIH 3T3 cells resulted in the rapid (within 2-5 min) stimulation (approx. 2-fold) of sodium-dependent phosphate (Pi) transport. Conversely, preincubation of these cells with forskolin and cholera toxin, or incubation with 8-bromo-cAMP, to activate cAMP-dependent protein kinase (PKA), resulted in a decrease in Na+/Pi transport. Activation of either PKC or PKA did not change the Vmax of Pi uptake. However, activation of PKC did result in an increase, while activation of PKA caused a decrease, in the affinity for Pi. These results indicate that there is differential regulation of Na+/Pi uptake in NIH 3T3 cells by activators of PKC (stimulated) and PKA (inhibited) as a consequence of changes in the affinity of the transporter for Pi.
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Affiliation(s)
- Z Oláh
- Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda 20892
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Affiliation(s)
- S J Peroutka
- Department of Neurology, Stanford University, California
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Dallaire L, Giroux S, Béliveau R. Regulation of phosphate transport by second messengers in capillaries of the blood-brain barrier. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1110:59-64. [PMID: 1382598 DOI: 10.1016/0005-2736(92)90294-v] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Regulation of phosphate uptake by the blood-brain barrier was studied in isolated bovine capillaries. Dibutyryl cAMP, in the presence of 3-isobutylmethylxanthine, resulted in a dose-dependent inhibition of phosphate uptake. Phosphate influx, with or without 3-isobutylmethylxanthine, was not different. Inhibition of phosphate uptake was also observed when capillaries were preincubated with isoproterenol, parathyroid hormone, insulin and acidic or basic fibroblast growth factors. Treatment of capillaries with vasoactive intestinal peptide, prostaglandin E1, angiotensin II, epidermal growth factor and phorbol esters did not affect phosphate transport. Endothelin I increased phosphate uptake by 15%. Preincubation with cholera toxin also resulted in a dose-dependent decrease in phosphate uptake. In addition, pertussis toxin inhibited phosphate transport by 29%, but only in the presence of 3-isobutylmethylxanthine. These results demonstrate that generation of second messengers, following receptor stimulation, can induce physiological effects on capillary phosphate influx and suggest that G proteins may modulate this transport.
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Affiliation(s)
- L Dallaire
- Laboratoire de membranologie, Université du Québec à Montréal, Canada
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Raymond JR, Albers FJ, Middleton JP. Functional expression of human 5-HT1A receptors and differential coupling to second messengers in CHO cells. NAUNYN-SCHMIEDEBERG'S ARCHIVES OF PHARMACOLOGY 1992; 346:127-37. [PMID: 1448178 DOI: 10.1007/bf00165293] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The signal transduction linkages of the cloned human 5-HT1A receptor as expressed stably in CHO cells were studied. A transfected clonal cell line which expresses 900 +/- 36 fmol 5-HT1A receptor/mg protein (designated CHO-5-HT1A/WT-27) responded to 5-HT and/or 8-OH-DPAT by coupling to several second messenger pathways. The 5-HT1A receptor inhibited, but did not stimulate, membrane adenylyl cyclase activity and whole cell cAMP accumulation in a dose-dependent manner (for 5-HT, IC50 = 146 +/- 27 and 55 +/- 12 nM, respectively). Activation of the receptor was associated with other signal transduction linkages: (i) a 40-50% increase in hydrolysis of inositol phosphates (for 5-HT, EC50 = 1.33 +/- 0.15 microM for 5-HT), (ii) a transient elevation of cytosolic Ca2+ levels (apparent at 1-100 microM 5-HT) which was not affected by chelation of extracellular Ca2+ by EGTA, and (iii) an augmentation of [3H]-arachidonic acid release pharmacologically with the calcium ionophore A23187 or by activation of endogenous thrombin or P2 purinergic receptors (for 5-HT, EC50 = 1.22 +/- 0.17 microM). This pathway may be an amplification mechanism for signaling in anatomic regions with high concentrations of several neuro-transmitters, hormones or autacoids, such as at neuronal junctions or near areas of platelet aggregation. All linkages were sensitive to pertussis toxin pre-treatment (IC50 approximately 0.5-0.6 ng/ml x 4.5 h for all pathways), suggesting the involvement of Gi protein(s) in these signal transduction pathways. Coupling to varied signal transduction pathways in a single cell system may be a common feature of receptors which classically inhibit adenylyl cyclase such as the 5-HT1A receptor.
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Affiliation(s)
- J R Raymond
- Department of Medicine (Nephrology), Duke University Medical Center, Durham, NC 27710
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Ho BY, Karschin A, Raymond JR, Branchek T, Lester HA, Davidson N. Expression in animal cells of the 5-HT1A receptor by a vaccinia virus vector system. FEBS Lett 1992; 301:303-6. [PMID: 1533596 DOI: 10.1016/0014-5793(92)80262-f] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The co-infection or infection-transfection variants of the T7 RNA polymerase/vaccinia vector system were used to express 5-HT1ARs in COS-7, BSC-40 and GH3 cells, with co-infection giving ca. 3-fold higher level than infection-transfection. Binding affinities were similar to those of the endogenous 5-HT1AR, with highest affinities for 5-HT and 8-OH-DPAT. Functional properties were demonstrated by assays of agonist-stimulated GTPase activity and its inhibition by pertussin toxin. Immunoblot assays showed expression of the unglycosylated and glycosylated receptor protein in the membrane and, surprisingly, in the cytosolic fractions.
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Affiliation(s)
- B Y Ho
- Division of Biology, California Institute of Technology, Pasadena 91125
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Raymond JR, Albers FJ, Middleton JP, Lefkowitz RJ, Caron MG, Obeid LM, Dennis VW. 5-HT1A and histamine H1 receptors in HeLa cells stimulate phosphoinositide hydrolysis and phosphate uptake via distinct G protein pools. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)52444-3] [Citation(s) in RCA: 58] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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el Mestikawy S, Fargin A, Raymond JR, Gozlan H, Hnatowich M. The 5-HT1A receptor: an overview of recent advances. Neurochem Res 1991; 16:1-10. [PMID: 2052135 DOI: 10.1007/bf00965820] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Progress in the field of neuronal receptor research has accelerated during the last few years due to developments in pharmacology and molecular biology. This is particularly true in the case of the serotonin 5-HT1A receptor. In 1983 the very selective, high affinity 5-HT1A agonist 8-OH-DPAT was developed which allowed the pharmacology and distribution of the 5-HT1A receptor in the central nervous system of the rat and man to be extensively characterized. By 1987, the gene encoding this receptor protein was cloned and sequenced, allowing not only elucidation of its structure, but also better insight into the nature of its coupling to transmembrane signal transduction systems. Thus in a short period of time considerable knowledge has accumulated on how serotonin exerts its functions in the central nervous system via the 5-HT1A receptor. In the present review we will briefly discuss some of the latest developments regarding the 5-HT1A receptor.
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Affiliation(s)
- S el Mestikawy
- INSERM U288, Neurobiologie cellulaire et fonctionnelle, Faculté de Médecine Pitié-Salpêtrière, Paris, France
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Abstract
Significant advances in the molecular pharmacological analysis of 5-hydroxytryptamine (5-HT) receptor subtypes occurred in the 1980's. To a significant degree, this progress resulted from 2 independent approaches: molecular biology and molecular pharmacology. This review focuses on the pharmacological data derived from radioligand binding studies. At the present time, 5-HT receptor subtypes are often categorized into at least 3 major "families" as well as a few "orphan" receptors that cannot yet be placed into the major categories. Each "family" consists of multiple receptor subtypes which share similarities in their molecular biological, pharmacological, biochemical and physiological properties. In order to provide a comparative pharmacological analysis of the 7 most extensively characterized 5-HT receptor subtypes, potency information is presented on the 30 pharmacological agents that have been, to date, studied most extensively in the published literature.
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Affiliation(s)
- S J Peroutka
- Department of Neurology, Stanford University Medical Center, CA 94350
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