1
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Simmons SC, Flerlage WJ, Langlois LD, Shepard RD, Bouslog C, Thomas EH, Gouty KM, Sanderson JL, Gouty S, Cox BM, Dell'Acqua ML, Nugent FS. AKAP150-anchored PKA regulates synaptic transmission and plasticity, neuronal excitability and CRF neuromodulation in the mouse lateral habenula. Commun Biol 2024; 7:345. [PMID: 38509283 PMCID: PMC10954712 DOI: 10.1038/s42003-024-06041-8] [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: 12/06/2023] [Accepted: 03/08/2024] [Indexed: 03/22/2024] Open
Abstract
The scaffolding A-kinase anchoring protein 150 (AKAP150) is critically involved in kinase and phosphatase regulation of synaptic transmission/plasticity, and neuronal excitability. Emerging evidence also suggests that AKAP150 signaling may play a key role in brain's processing of rewarding/aversive experiences, however its role in the lateral habenula (LHb, as an important brain reward circuitry) is completely unknown. Using whole cell patch clamp recordings in LHb of male wildtype and ΔPKA knockin mice (with deficiency in AKAP-anchoring of PKA), here we show that the genetic disruption of PKA anchoring to AKAP150 significantly reduces AMPA receptor-mediated glutamatergic transmission and prevents the induction of presynaptic endocannabinoid-mediated long-term depression in LHb neurons. Moreover, ΔPKA mutation potentiates GABAA receptor-mediated inhibitory transmission while increasing LHb intrinsic excitability through suppression of medium afterhyperpolarizations. ΔPKA mutation-induced suppression of medium afterhyperpolarizations also blunts the synaptic and neuroexcitatory actions of the stress neuromodulator, corticotropin releasing factor (CRF), in mouse LHb. Altogether, our data suggest that AKAP150 complex signaling plays a critical role in regulation of AMPA and GABAA receptor synaptic strength, glutamatergic plasticity and CRF neuromodulation possibly through AMPA receptor and potassium channel trafficking and endocannabinoid signaling within the LHb.
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Affiliation(s)
- Sarah C Simmons
- Uniformed Services University of the Health Sciences, Department of Pharmacology and Molecular Therapeutics, Bethesda, MD, 20814, USA
| | - William J Flerlage
- Uniformed Services University of the Health Sciences, Department of Pharmacology and Molecular Therapeutics, Bethesda, MD, 20814, USA
| | - Ludovic D Langlois
- Uniformed Services University of the Health Sciences, Department of Pharmacology and Molecular Therapeutics, Bethesda, MD, 20814, USA
| | - Ryan D Shepard
- Uniformed Services University of the Health Sciences, Department of Pharmacology and Molecular Therapeutics, Bethesda, MD, 20814, USA
| | - Christopher Bouslog
- Uniformed Services University of the Health Sciences, Department of Pharmacology and Molecular Therapeutics, Bethesda, MD, 20814, USA
| | - Emily H Thomas
- Uniformed Services University of the Health Sciences, Department of Pharmacology and Molecular Therapeutics, Bethesda, MD, 20814, USA
| | - Kaitlyn M Gouty
- Uniformed Services University of the Health Sciences, Department of Pharmacology and Molecular Therapeutics, Bethesda, MD, 20814, USA
| | - Jennifer L Sanderson
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO, 80045, USA
| | - Shawn Gouty
- Uniformed Services University of the Health Sciences, Department of Pharmacology and Molecular Therapeutics, Bethesda, MD, 20814, USA
| | - Brian M Cox
- Uniformed Services University of the Health Sciences, Department of Pharmacology and Molecular Therapeutics, Bethesda, MD, 20814, USA
| | - Mark L Dell'Acqua
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO, 80045, USA.
| | - Fereshteh S Nugent
- Uniformed Services University of the Health Sciences, Department of Pharmacology and Molecular Therapeutics, Bethesda, MD, 20814, USA.
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2
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Simmons S, Flerlage W, Langlois L, Shepard R, Bouslog C, Thomas E, Gouty K, Sanderson J, Gouty S, Cox B, Dell’Acqua M, Nugent F. AKAP150-anchored PKA regulation of synaptic transmission and plasticity, neuronal excitability and CRF neuromodulation in the lateral habenula. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.06.570160. [PMID: 38106086 PMCID: PMC10723374 DOI: 10.1101/2023.12.06.570160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Numerous studies of hippocampal synaptic function in learning and memory have established the functional significance of the scaffolding A-kinase anchoring protein 150 (AKAP150) in kinase and phosphatase regulation of synaptic receptor and ion channel trafficking/function and hence synaptic transmission/plasticity, and neuronal excitability. Emerging evidence also suggests that AKAP150 signaling may play a critical role in brain's processing of rewarding/aversive experiences. Here we focused on an unexplored role of AKAP150 in the lateral habenula (LHb), a diencephalic brain region that integrates and relays negative reward signals from forebrain striatal and limbic structures to midbrain monoaminergic centers. LHb aberrant activity (specifically hyperactivity) is also linked to depression. Using whole cell patch clamp recordings in LHb of male wildtype (WT) and ΔPKA knockin mice (with deficiency in AKAP-anchoring of PKA), we found that the genetic disruption of PKA anchoring to AKAP150 significantly reduced AMPA receptor (AMPAR)-mediated glutamatergic transmission and prevented the induction of presynaptic endocannabinoid (eCB)-mediated long-term depression (LTD) in LHb neurons. Moreover, ΔPKA mutation potentiated GABAA receptor (GABAAR)-mediated inhibitory transmission postsynaptically while increasing LHb intrinsic neuronal excitability through suppression of medium afterhyperpolarizations (mAHPs). Given that LHb is a highly stress-responsive brain region, we further tested the effects of corticotropin releasing factor (CRF) stress neuromodulator on synaptic transmission and intrinsic excitability of LHb neurons in WT and ΔPKA mice. As in our earlier study in rat LHb, CRF significantly suppressed GABAergic transmission onto LHb neurons and increased intrinsic excitability by diminishing small-conductance potassium (SK) channel-mediated mAHPs. ΔPKA mutation-induced suppression of mAHPs also blunted the synaptic and neuroexcitatory actions of CRF in mouse LHb. Altogether, our data suggest that AKAP150 complex signaling plays a critical role in regulation of AMPAR and GABAAR synaptic strength, glutamatergic plasticity and CRF neuromodulation possibly through AMPAR and potassium channel trafficking and eCB signaling within the LHb.
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Affiliation(s)
- S.C. Simmons
- Uniformed Services University of the Health Sciences, Department of Pharmacology, Bethesda, Maryland 20814, USA
| | - W.J. Flerlage
- Uniformed Services University of the Health Sciences, Department of Pharmacology, Bethesda, Maryland 20814, USA
| | - L.D. Langlois
- Uniformed Services University of the Health Sciences, Department of Pharmacology, Bethesda, Maryland 20814, USA
| | - R.D. Shepard
- Uniformed Services University of the Health Sciences, Department of Pharmacology, Bethesda, Maryland 20814, USA
| | - C. Bouslog
- Uniformed Services University of the Health Sciences, Department of Pharmacology, Bethesda, Maryland 20814, USA
| | - E.H. Thomas
- Uniformed Services University of the Health Sciences, Department of Pharmacology, Bethesda, Maryland 20814, USA
| | - K.M. Gouty
- Uniformed Services University of the Health Sciences, Department of Pharmacology, Bethesda, Maryland 20814, USA
| | - J.L. Sanderson
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - S. Gouty
- Uniformed Services University of the Health Sciences, Department of Pharmacology, Bethesda, Maryland 20814, USA
| | - B.M. Cox
- Uniformed Services University of the Health Sciences, Department of Pharmacology, Bethesda, Maryland 20814, USA
| | - M.L. Dell’Acqua
- Department of Pharmacology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - F.S. Nugent
- Uniformed Services University of the Health Sciences, Department of Pharmacology, Bethesda, Maryland 20814, USA
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3
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Wang H, Qian T, Zhao Y, Zhuo Y, Wu C, Osakada T, Chen P, Chen Z, Ren H, Yan Y, Geng L, Fu S, Mei L, Li G, Wu L, Jiang Y, Qian W, Zhang L, Peng W, Xu M, Hu J, Jiang M, Chen L, Tang C, Zhu Y, Lin D, Zhou JN, Li Y. A tool kit of highly selective and sensitive genetically encoded neuropeptide sensors. Science 2023; 382:eabq8173. [PMID: 37972184 PMCID: PMC11205257 DOI: 10.1126/science.abq8173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 10/02/2023] [Indexed: 11/19/2023]
Abstract
Neuropeptides are key signaling molecules in the endocrine and nervous systems that regulate many critical physiological processes. Understanding the functions of neuropeptides in vivo requires the ability to monitor their dynamics with high specificity, sensitivity, and spatiotemporal resolution. However, this has been hindered by the lack of direct, sensitive, and noninvasive tools. We developed a series of GRAB (G protein-coupled receptor activation‒based) sensors for detecting somatostatin (SST), corticotropin-releasing factor (CRF), cholecystokinin (CCK), neuropeptide Y (NPY), neurotensin (NTS), and vasoactive intestinal peptide (VIP). These fluorescent sensors, which enable detection of specific neuropeptide binding at nanomolar concentrations, establish a robust tool kit for studying the release, function, and regulation of neuropeptides under both physiological and pathophysiological conditions.
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Affiliation(s)
- Huan Wang
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Tongrui Qian
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Yulin Zhao
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Yizhou Zhuo
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Chunling Wu
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Takuya Osakada
- Department of Psychiatry and Department of Neuroscience and Physiology, New York University Langone Medical Center, New York, NY 10016, USA
| | - Peng Chen
- Institute of Brain Science, The First Affiliated Hospital of Anhui Medical University, Hefei 230022, China
- Chinese Academy of Sciences Key Laboratory of Brain Function and Diseases, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Zijun Chen
- Shenzhen Key Laboratory of Drug Addiction, Shenzhen Neher Neural Plasticity Laboratory, Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Huixia Ren
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Yuqi Yan
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Lan Geng
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Shengwei Fu
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Long Mei
- Department of Psychiatry and Department of Neuroscience and Physiology, New York University Langone Medical Center, New York, NY 10016, USA
| | - Guochuan Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Ling Wu
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Yiwen Jiang
- Department of Psychiatry and Department of Neuroscience and Physiology, New York University Langone Medical Center, New York, NY 10016, USA
| | - Weiran Qian
- Institute of Molecular Medicine, Peking University, Beijing 100871, China
| | - Li Zhang
- Department of Physiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Wanling Peng
- Chinese Academy of Sciences Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Min Xu
- Chinese Academy of Sciences Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Ji Hu
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Man Jiang
- Department of Physiology, School of Basic Medicine and Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Liangyi Chen
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Chao Tang
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Yingjie Zhu
- Shenzhen Key Laboratory of Drug Addiction, Shenzhen Neher Neural Plasticity Laboratory, Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Dayu Lin
- Department of Psychiatry and Department of Neuroscience and Physiology, New York University Langone Medical Center, New York, NY 10016, USA
| | - Jiang-Ning Zhou
- Institute of Brain Science, The First Affiliated Hospital of Anhui Medical University, Hefei 230022, China
- Chinese Academy of Sciences Key Laboratory of Brain Function and Diseases, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230026, China
| | - Yulong Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
- IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
- National Biomedical Imaging Center, Peking University, Beijing 100871, China
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4
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Amado P, Zegers J, Yarur HE, Gysling K. Transcriptional Regulation, Signaling Pathways, and Subcellular Localization of Corticotropin-Releasing Factor Receptors in the Central Nervous System. Mol Pharmacol 2022; 102:280-287. [PMID: 36167424 DOI: 10.1124/molpharm.121.000476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 09/12/2022] [Indexed: 12/24/2022] Open
Abstract
Corticotropin-releasing factor (CRF) receptors CRF-R1 and CRF-R2 are differentially distributed in body tissues, and although they respond differentially to stimuli due to their association with different signaling pathways, both receptors have a fundamental role in the response and adaptation to stressful stimuli. Here, we summarize the reported data on different forms of CRF-R1 and CRF-R2 regulation as well as on their subcellular localization. Although the presence of R1 has been described at pre- and postsynaptic sites, R2 is mainly associated with postsynaptic densities. Different studies have provided valuable information on how these receptors regulate responses at a central level, elucidating different and sometimes synergistic roles in response to stress, but despite their high sequence identity, both receptors have been described to be differentially regulated both by their ligands and by transcriptional factors. To date, and from the point of view of their promoter sequences, it has not yet been reported how the different consensus sites identified in silico could be modulating the transcriptional regulation and expression of the receptors under different conditions, which strongly limits the full understanding of their differential functions, providing a wide field to increase and expand the study of the regulation and role of CRF receptors in the CRF system. SIGNIFICANCE STATEMENT: A large number of physiological functions related to the organization of the stress response in different body tissues are associated with the corticotropin-releasing factor system. This system also plays a relevant role in depression and anxiety disorders, as well as being a direct connection between stress and addiction. A better understanding of how the receptors of this system are regulated would help to expand the understanding of how these receptors respond differently to both drugs and stressful stimuli.
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Affiliation(s)
- Paula Amado
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Juan Zegers
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Hector E Yarur
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Katia Gysling
- Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile
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5
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Tasma Z, Wills P, Hay DL, Walker CS. Agonist bias and agonist-dependent antagonism at corticotrophin releasing factor receptors. Pharmacol Res Perspect 2021; 8:e00595. [PMID: 32529807 PMCID: PMC7290078 DOI: 10.1002/prp2.595] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 03/26/2020] [Indexed: 01/14/2023] Open
Abstract
The corticotropin-releasing factor (CRF) receptors represent potential drug targets for the treatment of anxiety, stress, and other disorders. However, it is not known if endogenous CRF receptor agonists display biased signaling, how effective CRF receptor antagonists are at blocking different agonists and signaling pathways or how receptor activity-modifying proteins (RAMPs) effect these processes. This study aimed to address this by investigating agonist and antagonist action at CRF1 and CRF2 receptors. We used CRF1 and CRF2 receptor transfected Cos7 cells to assess the ability of CRF and urocortin (UCN) peptides to activate cAMP, inositol monophosphate (IP1 ), and extracellular signal-regulated kinase 1/2 signaling and determined the ability of antagonists to block agonist-stimulated cAMP and IP1 accumulation. The ability of RAMPs to interact with CRF receptors was also examined. At the CRF1 receptor, CRF and UCN1 activated signaling in the same manner. However, at the CRF2 receptor, UCN1 and UCN2 displayed similar signaling profiles, whereas CRF and UCN3 displayed bias away from IP1 accumulation over cAMP. The antagonist potency was dependent on the receptor, agonist, and signaling pathway. CRF1 and CRF2 receptors had no effect on RAMP1 or RAMP2 surface expression. The presence of biased agonism and agonist-dependent antagonism at the CRF receptors offers new avenues for developing drugs tailored to activate a specific signaling pathway or block a specific agonist. Our findings suggest that the already complex CRF receptor pharmacology may be underappreciated and requires further investigation.
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Affiliation(s)
- Zoe Tasma
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Peter Wills
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Debbie L Hay
- School of Biological Sciences, University of Auckland, Auckland, New Zealand.,Maurice Wilkins Centre and Centre for Brain Research, University of Auckland, Auckland, New Zealand
| | - Christopher S Walker
- School of Biological Sciences, University of Auckland, Auckland, New Zealand.,Maurice Wilkins Centre and Centre for Brain Research, University of Auckland, Auckland, New Zealand
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6
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Simpson SJS, Smith LIF, Jones PM, Bowe JE. UCN2: a new candidate influencing pancreatic β-cell adaptations in pregnancy. J Endocrinol 2020; 245:247-257. [PMID: 32106091 PMCID: PMC7159164 DOI: 10.1530/joe-19-0568] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 02/27/2020] [Indexed: 12/11/2022]
Abstract
The corticotropin-releasing hormone (CRH) family of peptides, including urocortin (UCN) 1, 2 and 3, are established hypothalamic neuroendocrine peptides, regulating the physiological and behaviour responses to stress indirectly, via the hypothalamic-pituitary-adrenal (HPA) axis. More recently, these peptides have been implicated in diverse roles in peripheral organs through direct signalling, including in placental and pancreatic islet physiology. CRH has been shown to stimulate insulin release through activation of its cognate receptors, CRH receptor 1 (CRHR1) and 2. However, the physiological significance of this is unknown. We have previously reported that during mouse pregnancy, expression of CRH peptides increase in mouse placenta suggesting that these peptides may play a role in various biological functions associated with pregnancy, particularly the pancreatic islet adaptations that occur in the pregnant state to compensate for the physiological increase in maternal insulin resistance. In the current study, we show that mouse pregnancy is associated with increased circulating levels of UCN2 and that when we pharmacologically block endogenous CRHR signalling in pregnant mice, impairment of glucose tolerance is observed. This effect on glucose tolerance was comparable to that displayed with specific CRHR2 blockade and not with specific CRHR1 blockade. No effects on insulin sensitivity or the proliferative capacity of β-cells were detected. Thus, CRHR2 signalling appears to be involved in β-cell adaptive responses to pregnancy in the mouse, with endogenous placental UCN2 being the likely signal mediating this.
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Affiliation(s)
- Sian J S Simpson
- Department of Diabetes, School of Life Course Sciences, Faculty of Life Science and Medicine, King’s College London, London, UK
- Correspondence should be addressed to S J S Simpson:
| | - Lorna I F Smith
- Department of Diabetes, School of Life Course Sciences, Faculty of Life Science and Medicine, King’s College London, London, UK
| | - Peter M Jones
- Department of Diabetes, School of Life Course Sciences, Faculty of Life Science and Medicine, King’s College London, London, UK
| | - James E Bowe
- Department of Diabetes, School of Life Course Sciences, Faculty of Life Science and Medicine, King’s College London, London, UK
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7
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Parra-Mercado GK, Fuentes-Gonzalez AM, Hernandez-Aranda J, Diaz-Coranguez M, Dautzenberg FM, Catt KJ, Hauger RL, Olivares-Reyes JA. CRF 1 Receptor Signaling via the ERK1/2-MAP and Akt Kinase Cascades: Roles of Src, EGF Receptor, and PI3-Kinase Mechanisms. Front Endocrinol (Lausanne) 2019; 10:869. [PMID: 31920979 PMCID: PMC6921279 DOI: 10.3389/fendo.2019.00869] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Accepted: 11/27/2019] [Indexed: 12/28/2022] Open
Abstract
In the present study, we determined the cellular regulators of ERK1/2 and Akt signaling pathways in response to human CRF1 receptor (CRF1R) activation in transfected COS-7 cells. We found that Pertussis Toxin (PTX) treatment or sequestering Gβγ reduced CRF1R-mediated activation of ERK1/2, suggesting the involvement of a Gi-linked cascade. Neither Gs/PKA nor Gq/PKC were associated with ERK1/2 activation. Besides, CRF induced EGF receptor (EGFR) phosphorylation at Tyr1068, and selective inhibition of EGFR kinase activity by AG1478 strongly inhibited the CRF1R-mediated phosphorylation of ERK1/2, indicating the participation of EGFR transactivation. Furthermore, CRF-induced ERK1/2 phosphorylation was not altered by pretreatment with batimastat, GM6001, or an HB-EGF antibody indicating that metalloproteinase processing of HB-EGF ligands is not required for the CRF-mediated EGFR transactivation. We also observed that CRF induced Src and PYK2 phosphorylation in a Gβγ-dependent manner. Additionally, using the specific Src kinase inhibitor PP2 and the dominant-negative-SrcYF-KM, it was revealed that CRF-stimulated ERK1/2 phosphorylation depends on Src activation. PP2 also blocked the effect of CRF on Src and EGFR (Tyr845) phosphorylation, further demonstrating the centrality of Src. We identified the formation of a protein complex consisting of CRF1R, Src, and EGFR facilitates EGFR transactivation and CRF1R-mediated signaling. CRF stimulated Akt phosphorylation, which was dependent on Gi/βγ subunits, and Src activation, however, was only slightly dependent on EGFR transactivation. Moreover, PI3K inhibitors were able to inhibit not only the CRF-induced phosphorylation of Akt, as expected, but also ERK1/2 activation by CRF suggesting a PI3K dependency in the CRF1R ERK signaling. Finally, CRF-stimulated ERK1/2 activation was similar in the wild-type CRF1R and the phosphorylation-deficient CRF1R-Δ386 mutant, which has impaired agonist-dependent β-arrestin-2 recruitment; however, this situation may have resulted from the low β-arrestin expression in the COS-7 cells. When β-arrestin-2 was overexpressed in COS-7 cells, CRF-stimulated ERK1/2 phosphorylation was markedly upregulated. These findings indicate that on the base of a constitutive CRF1R/EGFR interaction, the Gi/βγ subunits upstream activation of Src, PYK2, PI3K, and transactivation of the EGFR are required for CRF1R signaling via the ERK1/2-MAP kinase pathway. In contrast, Akt activation via CRF1R is mediated by the Src/PI3K pathway with little contribution of EGFR transactivation.
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Affiliation(s)
- G. Karina Parra-Mercado
- Laboratory of Signal Transduction, Department of Biochemistry, Center for Research and Advanced Studies of the National Polytechnic Institute, CINVESTAV-IPN, Mexico City, Mexico
| | - Alma M. Fuentes-Gonzalez
- Laboratory of Signal Transduction, Department of Biochemistry, Center for Research and Advanced Studies of the National Polytechnic Institute, CINVESTAV-IPN, Mexico City, Mexico
| | - Judith Hernandez-Aranda
- Laboratory of Signal Transduction, Department of Biochemistry, Center for Research and Advanced Studies of the National Polytechnic Institute, CINVESTAV-IPN, Mexico City, Mexico
| | - Monica Diaz-Coranguez
- Laboratory of Signal Transduction, Department of Biochemistry, Center for Research and Advanced Studies of the National Polytechnic Institute, CINVESTAV-IPN, Mexico City, Mexico
| | | | - Kevin J. Catt
- Section on Hormonal Regulation, Program on Developmental Endocrinology and Genetics, National Institute of Child Health and Human Development, Bethesda, MD, United States
| | - Richard L. Hauger
- Center of Excellence for Stress and Mental Health, VA Healthcare System, San Diego, CA, United States
- Department of Psychiatry, University of California, San Diego, San Diego, CA, United States
| | - J. Alberto Olivares-Reyes
- Laboratory of Signal Transduction, Department of Biochemistry, Center for Research and Advanced Studies of the National Polytechnic Institute, CINVESTAV-IPN, Mexico City, Mexico
- *Correspondence: J. Alberto Olivares-Reyes
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8
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Deussing JM, Chen A. The Corticotropin-Releasing Factor Family: Physiology of the Stress Response. Physiol Rev 2018; 98:2225-2286. [DOI: 10.1152/physrev.00042.2017] [Citation(s) in RCA: 127] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The physiological stress response is responsible for the maintenance of homeostasis in the presence of real or perceived challenges. In this function, the brain activates adaptive responses that involve numerous neural circuits and effector molecules to adapt to the current and future demands. A maladaptive stress response has been linked to the etiology of a variety of disorders, such as anxiety and mood disorders, eating disorders, and the metabolic syndrome. The neuropeptide corticotropin-releasing factor (CRF) and its relatives, the urocortins 1–3, in concert with their receptors (CRFR1, CRFR2), have emerged as central components of the physiological stress response. This central peptidergic system impinges on a broad spectrum of physiological processes that are the basis for successful adaptation and concomitantly integrate autonomic, neuroendocrine, and behavioral stress responses. This review focuses on the physiology of CRF-related peptides and their cognate receptors with the aim of providing a comprehensive up-to-date overview of the field. We describe the major molecular features covering aspects of gene expression and regulation, structural properties, and molecular interactions, as well as mechanisms of signal transduction and their surveillance. In addition, we discuss the large body of published experimental studies focusing on state-of-the-art genetic approaches with high temporal and spatial precision, which collectively aimed to dissect the contribution of CRF-related ligands and receptors to different levels of the stress response. We discuss the controversies in the field and unravel knowledge gaps that might pave the way for future research directions and open up novel opportunities for therapeutic intervention.
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Affiliation(s)
- Jan M. Deussing
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany; and Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Alon Chen
- Department of Stress Neurobiology and Neurogenetics, Max Planck Institute of Psychiatry, Munich, Germany; and Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
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9
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Wootten D, Miller LJ, Koole C, Christopoulos A, Sexton PM. Allostery and Biased Agonism at Class B G Protein-Coupled Receptors. Chem Rev 2016; 117:111-138. [PMID: 27040440 DOI: 10.1021/acs.chemrev.6b00049] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Class B G protein-coupled receptors (GPCRs) respond to paracrine or endocrine peptide hormones involved in control of bone homeostasis, glucose regulation, satiety, and gastro-intestinal function, as well as pain transmission. These receptors are targets for existing drugs that treat osteoporosis, hypercalcaemia, Paget's disease, type II diabetes, and obesity and are being actively pursued as targets for numerous other diseases. Exploitation of class B receptors has been limited by difficulties with small molecule drug discovery and development and an under appreciation of factors governing optimal therapeutic efficacy. Recently, there has been increasing awareness of novel attributes of GPCR function that offer new opportunity for drug development. These include the presence of allosteric binding sites on the receptor that can be exploited as drug binding pockets and the ability of individual drugs to enrich subpopulations of receptor conformations to selectively control signaling, a phenomenon termed biased agonism. In this review, current knowledge of biased signaling and small molecule allostery within class B GPCRs is discussed, highlighting areas that have progressed significantly over the past decade, in addition to those that remain largely unexplored with respect to these phenomena.
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Affiliation(s)
- Denise Wootten
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville 3052, Victoria, Australia
| | - Laurence J Miller
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic , Scottsdale, Arizona 85259, United States
| | - Cassandra Koole
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville 3052, Victoria, Australia.,Laboratory of Chemical Biology and Signal Transduction, The Rockefeller University , New York, New York 10065, United States
| | - Arthur Christopoulos
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville 3052, Victoria, Australia
| | - Patrick M Sexton
- Drug Discovery Biology and Department of Pharmacology, Monash Institute of Pharmaceutical Sciences, Monash University , Parkville 3052, Victoria, Australia
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10
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: G protein-coupled receptors. Br J Pharmacol 2013; 170:1459-581. [PMID: 24517644 PMCID: PMC3892287 DOI: 10.1111/bph.12445] [Citation(s) in RCA: 505] [Impact Index Per Article: 45.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. G protein-coupled receptors are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen PH Alexander
- School of Life Sciences, University of Nottingham Medical SchoolNottingham, NG7 2UH, UK
| | - Helen E Benson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Elena Faccenda
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Adam J Pawson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Joanna L Sharman
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | | | - John A Peters
- Neuroscience Division, Medical Education Institute, Ninewells Hospital and Medical School, University of DundeeDundee, DD1 9SY, UK
| | - Anthony J Harmar
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
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11
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M T, JE G, RL H, AL H, VB R. The role of PKC signaling in CRF-induced modulation of startle. Psychopharmacology (Berl) 2013; 229:579-89. [PMID: 23722830 PMCID: PMC3784645 DOI: 10.1007/s00213-013-3114-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2012] [Accepted: 04/11/2013] [Indexed: 02/06/2023]
Abstract
RATIONALE Hypersignaling of corticotropin releasing factor (CRF) has been implicated in stress disorders; however, many of its downstream mechanisms of action remain unclear. In vitro, CRF1 receptor activation initiates multiple cell signaling cascades, including protein kinase A (PKA), protein kinase C (PKC), and mitogen-activated protein kinase kinase MEK1/2 signaling. It is unclear, however, which of these signaling cascades mediate CRF-induced behaviors during stress. OBJECTIVES We examined the role of PKA, PKC, and MEK1/2 signaling pathways in CRF-induced anxiety as measured by startle hyperreactivity. METHODS Mice treated with intracerbroventricular (ICV) ovine CRF (oCRF) were pretreated with the PKA inhibitor Rp-cAMPS, PKC inhibitor bisindolylmaleimide (BIM), or MEK1/2 inhibitor PD98059 (ICV) and assessed for acoustic startle reactivity. RESULTS The PKC inhibitor BIM significantly attenuated CRF-induced increases in startle. BIM was also able to block startle increases induced by oCRF when both compounds were infused directly into the bed nucleus of stria terminalis (BNST). PKA and MEK1/2 inhibition had no significant effects on CRF-induced changes in startle at the dose ranges tested. CRF-induced disruption of prepulse inhibition was not significantly reversed by any of the three pretreatments at the dose ranges tested. CONCLUSIONS PKC signaling is required for CRF-induced increases in startle, and this effect is mediated at least in part at the BNST. These findings suggest that PKC signaling cascades (1) may be important for the acute effects of CRF to induce startle hyperreactivity and (2) support further research of the role of PKC signaling in startle abnormalities relevant to disorders such as posttraumatic stress disorder.
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Affiliation(s)
- Toth M
- Center of Excellence for Stress and Mental Health, Veterans Affairs Hospital, La Jolla CA USA,Dept. of Psychiatry, University of California San Diego, La Jolla CA USA
| | - Gresack JE
- Center of Excellence for Stress and Mental Health, Veterans Affairs Hospital, La Jolla CA USA,Dept. of Psychiatry, University of California San Diego, La Jolla CA USA,Laboratory of Molecular and Cellular Neuroscience, The Rockefeller University, New York NY USA
| | - Hauger RL
- Center of Excellence for Stress and Mental Health, Veterans Affairs Hospital, La Jolla CA USA,Dept. of Psychiatry, University of California San Diego, La Jolla CA USA
| | - Halberstadt AL
- Dept. of Psychiatry, University of California San Diego, La Jolla CA USA
| | - Risbrough VB
- Center of Excellence for Stress and Mental Health, Veterans Affairs Hospital, La Jolla CA USA,Dept. of Psychiatry, University of California San Diego, La Jolla CA USA,Corresponding author: Victoria Risbrough, Ph.D., University of California San Diego, 9500 Gilman Dr. MC0804, La Jolla CA 92093-0804, Tel: 16195433582; Fax: 16195432475:
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12
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Hauger RL, Olivares-Reyes JA, Braun S, Hernandez-Aranda J, Hudson CC, Gutknecht E, Dautzenberg FM, Oakley RH. Desensitization of human CRF2(a) receptor signaling governed by agonist potency and βarrestin2 recruitment. ACTA ACUST UNITED AC 2013; 186:62-76. [PMID: 23820308 DOI: 10.1016/j.regpep.2013.06.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 04/18/2013] [Accepted: 06/20/2013] [Indexed: 01/04/2023]
Abstract
The primary goal was to determine agonist-specific regulation of CRF2(a) receptor function. Exposure of human retinoblastoma Y79 cells to selective (UCN2, UCN3 or stresscopins) and non-selective (UCN1 or sauvagine) agonists prominently desensitized CRF2(a) receptors in a rapid, concentration-dependent manner. A considerably slower rate and smaller magnitude of desensitization developed in response to the weak agonist CRF. CRF1 receptor desensitization stimulated by CRF, cortagine or stressin1-A had no effect on CRF2(a) receptor cyclic AMP signaling. Conversely, desensitization of CRF2(a) receptors by UCN2 or UCN3 did not cross-desensitize Gs-coupled CRF1 receptor signaling. In transfected HEK293 cells, activation of CRF2(a) receptors by UCN2, UCN3 or CRF resulted in receptor phosphorylation and internalization proportional to agonist potency. Neither protein kinase A nor casein kinases mediated CRF2(a) receptor phosphorylation or desensitization. Exposure of HEK293 or U2OS cells to UCN2 or UCN3 (100nM) produced strong βarrestin2 translocation and colocalization with membrane CRF2(a) receptors while CRF (1μM) generated only weak βarrestin2 recruitment. βarrestin2 did not internalize with the receptor, however, indicating that transient CRF2(a) receptor-arrestin complexes dissociate at or near the cell membrane. Since deletion of the βarrestin2 gene upregulated Gs-coupled CRF2(a) receptor signaling in MEF cells, a βarrestin2 mechanism restrains Gs-coupled CRF2(a) receptor signaling activated by urocortins. We further conclude that the rate and extent of homologous CRF2(a) receptor desensitization are governed by agonist-specific mechanisms affecting GRK phosphorylation, βarrestin2 recruitment, and internalization thereby producing unique signal transduction profiles that differentially affect the stress response.
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Affiliation(s)
- Richard L Hauger
- Center of Excellence for Stress and Mental Health, San Diego VA Healthcare System, 3350 La Jolla Village Drive, San Diego, CA 92161, USA; Department of Psychiatry, School of Medicine, University of California, 9500 Gilman Drive, La Jolla, San Diego, CA 92093, USA.
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13
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Maejima T, Masseck OA, Mark MD, Herlitze S. Modulation of firing and synaptic transmission of serotonergic neurons by intrinsic G protein-coupled receptors and ion channels. Front Integr Neurosci 2013; 7:40. [PMID: 23734105 PMCID: PMC3661940 DOI: 10.3389/fnint.2013.00040] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Accepted: 05/03/2013] [Indexed: 11/13/2022] Open
Abstract
Serotonergic neurons project to virtually all regions of the central nervous system and are consequently involved in many critical physiological functions such as mood, sexual behavior, feeding, sleep/wake cycle, memory, cognition, blood pressure regulation, breathing, and reproductive success. Therefore, serotonin release and serotonergic neuronal activity have to be precisely controlled and modulated by interacting brain circuits to adapt to specific emotional and environmental states. We will review the current knowledge about G protein-coupled receptors and ion channels involved in the regulation of serotonergic system, how their regulation is modulating the intrinsic activity of serotonergic neurons and its transmitter release and will discuss the latest methods for controlling the modulation of serotonin release and intracellular signaling in serotonergic neurons in vitro and in vivo.
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Affiliation(s)
- Takashi Maejima
- Department of Zoology and Neurobiology, Ruhr-University Bochum Bochum, Germany
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14
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Bonfiglio JJ, Inda C, Senin S, Maccarrone G, Refojo D, Giacomini D, Turck CW, Holsboer F, Arzt E, Silberstein S. B-Raf and CRHR1 internalization mediate biphasic ERK1/2 activation by CRH in hippocampal HT22 Cells. Mol Endocrinol 2013; 27:491-510. [PMID: 23371389 DOI: 10.1210/me.2012-1359] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
CRH is a key regulator of neuroendocrine, autonomic, and behavioral response to stress. CRH-stimulated CRH receptor 1 (CRHR1) activates ERK1/2 depending on intracellular context. In a previous work, we demonstrated that CRH activates ERK1/2 in limbic areas of the mouse brain (hippocampus and basolateral amygdala). ERK1/2 is an essential mediator of hippocampal physiological processes including emotional behavior, synaptic plasticity, learning, and memory. To elucidate the molecular mechanisms by which CRH activates ERK1/2 in hippocampal neurons, we used the mouse hippocampal cell line HT22. We document for the first time that ERK1/2 activation in response to CRH is biphasic, involving a first cAMP- and B-Raf-dependent early phase and a second phase that critically depends on CRHR1 internalization and β-arrestin2. By means of mass-spectrometry-based screening, we identified B-Raf-associated proteins that coimmunoprecipitate with endogenous B-Raf after CRHR1 activation. Using molecular and pharmacological tools, the functional impact of selected B-Raf partners in CRH-dependent ERK1/2 activation was dissected. These results indicate that 14-3-3 proteins, protein kinase A, and Rap1, are essential for early CRH-induced ERK1/2 activation, whereas dynamin and vimentin are required for the CRHR1 internalization-dependent phase. Both phases of ERK1/2 activation depend on calcium influx and are affected by calcium/calmodulin-dependent protein kinase II inactivation. Thus, this report describes the dynamics and biphasic nature of ERK1/2 activation downstream neuronal CRHR1 and identifies several new critical components of the CRHR1 signaling machinery that selectively controls the early and late phases of ERK1/2 activation, thus providing new potential therapeutic targets for stress-related disorders.
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Affiliation(s)
- Juan J Bonfiglio
- Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA), CONICET, Partner Institute of the Max Planck Society, Godoy Cruz 2390, C1425FQA Buenos Aires, Argentina
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15
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Brailoiu GC, Deliu E, Tica AA, Chitravanshi VC, Brailoiu E. Urocortin 3 elevates cytosolic calcium in nucleus ambiguus neurons. J Neurochem 2012; 122:1129-36. [PMID: 22774996 PMCID: PMC3433571 DOI: 10.1111/j.1471-4159.2012.07869.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Urocortin 3 (also known as stresscopin) is an endogenous ligand for the corticotropin-releasing factor receptor 2 (CRF(2)). Despite predominant G(s) coupling of CRF(2), promiscuous coupling with other G proteins has been also associated with the activation of this receptor. As urocortin 3 has been involved in central cardiovascular regulation at hypothalamic and medullary sites, we examined its cellular effects on cardiac vagal neurons of nucleus ambiguus, a key area for the autonomic control of heart rate. Urocortin 3 (1 nM-1000 nM) induced a concentration-dependent increase in cytosolic Ca(2+) concentration that was blocked by the CRF(2) antagonist K41498. In the case of two consecutive treatments with urocortin 3, the second urocortin 3-induced Ca(2+) response was reduced, indicating receptor desensitization. The effect of urocortin 3 was abolished by pre-treatment with pertussis toxin and by inhibition of phospolipase C with U-73122. Urocortin 3 activated Ca(2+) influx via voltage-gated P/Q-type channels as well as Ca(2+) release from endoplasmic reticulum. Urocortin 3 promoted Ca(2+) release via inositol 1,4,5 trisphosphate receptors, but not ryanodine receptors. Our results indicate a novel Ca(2+) -mobilizing effect of urocortin 3 in vagal pre-ganglionic neurons of nucleus ambiguus, providing a cellular mechanism for a previously reported role for this peptide in parasympathetic cardiac regulation.
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Affiliation(s)
- G Cristina Brailoiu
- Department of Pharmacology, Temple University School of Medicine, Philadelphia, PA 19140, USA.
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16
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Buckinx R, Adriaensen D, Nassauw LV, Timmermans JP. Corticotrophin-releasing factor, related peptides, and receptors in the normal and inflamed gastrointestinal tract. Front Neurosci 2011; 5:54. [PMID: 21541251 PMCID: PMC3082851 DOI: 10.3389/fnins.2011.00054] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Accepted: 04/01/2011] [Indexed: 12/13/2022] Open
Abstract
Corticotrophin-releasing factor (CRF) is mainly known for its role in the stress response in the hypothalamic–pituitary–adrenal axis. However, increasing evidence has revealed that CRF receptor signaling has additional peripheral effects. For instance, activation of CRF receptors in the gastrointestinal tract influences intestinal permeability and motility. These receptors, CRF1 and CRF2, do not only bind CRF, but are also activated by urocortins. Most interestingly, CRF-related signaling also assumes an important role in inflammatory bowel diseases in that it influences inflammatory processes, such as cytokine secretion and immune cell activation. These effects are characterized by an often contrasting function of CRF1 and CRF2. We will review the current data on the expression of CRF and related peptides in the different regions of the gastrointestinal tract, both in normal and inflamed conditions. We next discuss the possible functional roles of CRF signaling in inflammation. The available data clearly indicate that CRF signaling significantly influences inflammatory processes although there are important species and inflammation model differences. Although further research is necessary to elucidate this apparently delicately balanced system, it can be concluded that CRF-related peptides and receptors are (certainly) important candidates in the modulation of gastrointestinal inflammation.
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Affiliation(s)
- Roeland Buckinx
- Laboratory of Cell Biology and Histology, University of Antwerp Antwerp, Belgium
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17
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Dioxin exposure of human CD34+ hemopoietic cells induces gene expression modulation that recapitulates its in vivo clinical and biological effects. Toxicology 2011; 283:18-23. [DOI: 10.1016/j.tox.2011.01.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 01/25/2011] [Accepted: 01/28/2011] [Indexed: 11/22/2022]
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18
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Singh R, Rai U. Immunomodulatory role of urotensins in teleost Channa punctatus. Gen Comp Endocrinol 2011; 170:613-21. [PMID: 21130092 DOI: 10.1016/j.ygcen.2010.11.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2010] [Revised: 11/07/2010] [Accepted: 11/25/2010] [Indexed: 12/14/2022]
Abstract
The present study, for the first time in ectothermic vertebrates, reports the immunoregulatory role of urotensins I and II (UI and UII). Urotensins decreased the phagocytosis and nitrite production by splenic phagocytes. On superoxide production, UI had stimulatory while UII showed inhibitory effect. UI exerted its effect on phagocytes through corticotrophin-releasing factor (CRF) receptor as its non-specific antagonist astressin completely blocked the effect of UI on phagocytosis, nitrite release and superoxide production. Among the antagonists for specific CRF receptor 1 and 2, only CRF receptor 1 antagonist NBI 27914 abolished the effect of urotensin I. On the other hand, UII mediated its effect through urotensin receptor (UT receptor) since its antagonist urantide antagonized the effect of UII on phagocytosis, superoxide and nitrite release. These findings provide the direct evidence on physiological role of UI and UII through CRF receptor 1 and UT receptor, respectively in control of fish immune responses.
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Affiliation(s)
- Rajeev Singh
- Department of Zoology, University of Delhi, Delhi 110 007, India
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19
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Gutknecht E, Vauquelin G, Dautzenberg FM. Corticotropin-releasing factor receptors induce calcium mobilization through cross-talk with Gq-coupled receptors. Eur J Pharmacol 2010; 642:1-9. [PMID: 20594969 DOI: 10.1016/j.ejphar.2010.05.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Revised: 04/28/2010] [Accepted: 05/25/2010] [Indexed: 11/20/2022]
Abstract
The cross-talk between corticotropin-releasing factor (CRF) and muscarinic receptors was investigated by measuring evoked transient increases in cytosolic calcium concentration. HEK293 cells stably expressing human CRF type 1 (hCRF(1)) and type 2(a) (hCRF(2(a))) receptors were stimulated with the muscarinic receptor agonist carbachol and shortly after by a CRF agonist. Unexpectedly, this second response was enhanced when compared to stimulating naive cells either with carbachol or CRF agonist only. Priming with 100 microM carbachol increased the maximal CRF agonist response and shifted its concentration-response curve to the left to attain almost the same potency as for stimulating the production of the natural second messenger cyclic AMP. Yet, priming did not affect CRF agonist-stimulated cyclic AMP production itself. Carbachol priming was not restricted to recombinant CRF receptors only since endogenously expressed beta(2)-adrenoceptors also started to produce a robust calcium signal. Without priming no such signal was observed. Similar findings were made in the human retinoblastoma cell line Y79 for endogenously expressed CRF(1) receptors and the type 1 pituitary adenylate cyclase-activating polypeptide receptors but not for the CRF(2(a)) receptors. This differentiation between CRF(1) and CRF(2) receptors was further supported by use of selective agonists and antagonists. The results suggest that stimulating a Gq-coupled receptor shortly before stimulating a Gs-coupled receptor may result in a parallel signaling event on top of the classical cyclic AMP pathway.
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Affiliation(s)
- Eric Gutknecht
- Johnson & Johnson Research & Development, CNS Research, Turnhoutseweg 30, B-2340 Beerse, Belgium.
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20
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Van Kolen K, Dautzenberg FM, Verstraeten K, Royaux I, De Hoogt R, Gutknecht E, Peeters PJ. Corticotropin releasing factor-induced ERK phosphorylation in AtT20 cells occurs via a cAMP-dependent mechanism requiring EPAC2. Neuropharmacology 2009; 58:135-44. [PMID: 19573542 DOI: 10.1016/j.neuropharm.2009.06.022] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2009] [Revised: 06/15/2009] [Accepted: 06/22/2009] [Indexed: 11/24/2022]
Abstract
CRF-induced ERK phosphorylation has been shown to be an important mechanism underlying expression of pro-opiomelanocortin, a key precursor molecule in the hypothalamic pituitary adrenal axis. In AtT20 cells, CRF signalling has been investigated but the mechanism behind CRF-induced ERK activity is not fully understood. This paper elucidates the signalling cascade involved in this phenomenon. Involvement of CRF(1) receptor on ERK phosphorylation was shown by using CRF and urocortin 1. The lack of inhibitory effect of pertussis toxin and BAPTA-AM excluded involvement of G(i)-coupling and calcium mobilization respectively. In contrast, the process is suggested to be driven by cAMP since treatment of AtT20 cells with forskolin triggered strong ERK phosphorylation. Treatment with PKA inhibitors had a minor effect on CRF-induced ERK signalling while phosphorylation of CREB was completely abolished. This ruled out involvement of PKA and suggested a role for exchange protein directly activated by cAMP (EPAC). Moreover, an activator of EPACs 8-(4-methoxyphenylthio)-2'-O-methyladenosine-3',5'-cyclic monophosphate mimicked CRF-induced ERK phosphorylation. Gene expression analysis showed high levels of EPAC2 mRNA and protein but low levels of EPAC1. Knockdown of EPAC2 expression by the use of specific siRNAs abolished CRF- and forskolin-induced ERK phosphorylation. The current study demonstrates a clear cAMP-dependent but PKA-independent mechanism underlying CRF-induced ERK activity that proceeds via EPAC2 signalling. Further research will provide more insight in the role of EPAC2 in CRF signalling.
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Affiliation(s)
- Kristof Van Kolen
- CNS Discovery Research, Johnson & Johnson Pharmaceutical Research and Development, Division of Janssen Pharmaceutica N.V., Turnhoutseweg 30, B-2340 Beerse, Belgium.
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21
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Gutknecht E, Van der Linden I, Van Kolen K, Verhoeven KFC, Vauquelin G, Dautzenberg FM. Molecular mechanisms of corticotropin-releasing factor receptor-induced calcium signaling. Mol Pharmacol 2008; 75:648-57. [PMID: 19098121 DOI: 10.1124/mol.108.050427] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The molecular mechanisms governing calcium signal transduction of corticotropin-releasing factor (CRF) receptors CRF(1) and CRF(2(a)) stably expressed in human embryonic kidney (HEK) 293 cells were investigated. Calcium signaling strictly depended on intracellular calcium sources, and this is the first study to establish a prominent contribution of the three major G-protein families to CRF receptor-mediated calcium signaling. Overexpression of Galpha(q/11) and Galpha(16) led to leftward shifts of the agonist concentration-response curves. Blockade of Galpha(q/11) proteins by the small interfering RNA (siRNA) technology partially reduced agonist-mediated calcium responses in CRF(1)- and CRF(2(a))-expressing HEK293 cells, thereby proving a contribution of the G(q) protein family. A small but significant inhibition of calcium signaling was recorded by pharmacological inhibition of G(i/o) proteins with pertussis toxin treatment. This effect was mediated by direct binding of Gbetagamma subunits to phospholipase C. G(i/o) inhibition also elevated cAMP responses in CRF receptor-overexpressing HEK293 cells and in Y79 retinoblastoma cells endogenously expressing human CRF(1) and CRF(2(a)) receptors, thereby demonstrating natural coupling of G(i) proteins to both CRF receptors. The strongest reduction of CRF receptor-mediated calcium mobilization was noted when blocking the G(s) signaling protein either by cholera toxin or by siRNA. It is noteworthy that simultaneous inhibition of two G-proteins shed light on the additive effects of G(s) and G(q) on the calcium signaling and, hence, that they act in parallel. On the other hand, G(i) coupling required prior G(s) activation.
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Affiliation(s)
- Eric Gutknecht
- Johnson and Johnson Research and Development, CNS Research, Beerse, Belgium.
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22
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Gutknecht E, Hauger RL, Van der Linden I, Vauquelin G, Dautzenberg FM. Expression, binding, and signaling properties of CRF2(a) receptors endogenously expressed in human retinoblastoma Y79 cells: passage-dependent regulation of functional receptors. J Neurochem 2007; 104:926-36. [PMID: 17976162 DOI: 10.1111/j.1471-4159.2007.05052.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Endogenous expression of the corticotropin-releasing factor type 2a receptor [CRF2(a)] but not CRF2(b) and CRF2(c) was observed in higher passage cultures of human Y79 retinoblastoma cells. Functional studies further demonstrated an increase in CRF2(a) mRNA and protein levels with higher passage numbers (> 20 passages). Although the CRF1 receptor was expressed at higher levels than the CRF2(a) receptor, both receptors were easily distinguishable from one another by selective receptor ligands. CRF(1)-preferring or non-selective agonists such as CRF, urocortin 1 (UCN1), and sauvagine stimulated cAMP production in Y79 to maximal responses of approximately 100 pmoles/10(5) cells, whereas the exclusive CRF2 receptor-selective agonists UCN2 and 3 stimulated cAMP production to maximal responses of approximately 25-30 pmoles/10(5) cells. UCN2 and 3-mediated cAMP stimulation was potently blocked by the approximately 300-fold selective CRF2 antagonist antisauvagine (IC50 = 6.5 +/- 1.6 nmol/L), whereas the CRF(1)-selective antagonist NBI27914 only blocked cAMP responses at concentrations > 10 microL. When the CRF(1)-preferring agonist ovine CRF was used to activate cAMP signaling, NBI27914 (IC50 = 38.4 +/- 3.6 nmol/L) was a more potent inhibitor than antisauvagine (IC50 = 2.04 +/- 0.2 microL). Finally, UCN2 and 3 treatment potently and rapidly desensitized the CRF2 receptor responses in Y79 cells. These data demonstrate that Y79 cells express functional CRF1 and CRF2a receptors and that the CRF2(a) receptor protein is up-regulated during prolonged culture.
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Affiliation(s)
- Eric Gutknecht
- CNS Research, Johnson & Johnson Research & Development, Beerse, Belgium
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Xiao J, Gong S, LeDoux MS. Caytaxin deficiency disrupts signaling pathways in cerebellar cortex. Neuroscience 2006; 144:439-61. [PMID: 17092653 PMCID: PMC1868412 DOI: 10.1016/j.neuroscience.2006.09.042] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2006] [Revised: 09/15/2006] [Accepted: 09/20/2006] [Indexed: 11/28/2022]
Abstract
The genetically dystonic (dt) rat, an autosomal recessive model of generalized dystonia, harbors an insertional mutation in Atcay. As a result, dt rats are deficient in Atcay transcript and the neuronally-restricted protein caytaxin. Previous electrophysiological and biochemical studies have defined olivocerebellar pathways, particularly the climbing fiber projection to Purkinje cells, as sites of significant functional abnormality in dt rats. In normal rats, Atcay transcript is abundantly expressed in the granular and Purkinje cell layers of cerebellar cortex. To better understand the consequences of caytaxin deficiency in cerebellar cortex, differential gene expression was examined in dt rats and their normal littermates. Data from oligonucleotide microarrays and quantitative real-time reverse transcriptase-PCR (QRT-PCR) identified phosphatidylinositol signaling pathways, calcium homeostasis, and extracellular matrix interactions as domains of cellular dysfunction in dt rats. In dt rats, genes encoding the corticotropin-releasing hormone receptor 1 (CRH-R1, Crhr1) and plasma membrane calcium-dependent ATPase 4 (PMCA4, Atp2b4) showed the greatest up-regulation with QRT-PCR. Immunocytochemical experiments demonstrated that CRH-R1, CRH, and PMCA4 were up-regulated in cerebellar cortex of mutant rats. Along with previous electrophysiological and pharmacological studies, our data indicate that caytaxin plays a critical role in the molecular response of Purkinje cells to climbing fiber input. Caytaxin may also contribute to maturational events in cerebellar cortex.
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Affiliation(s)
| | | | - Mark S. LeDoux
- Address correspondence to: Mark S. LeDoux, M.D., Ph.D., University of Tennessee Health Science Center, Department of Neurology, 855 Monroe Avenue, Link Building-Suite 415, Memphis, Tennessee 38163, Phone: 901-448-1662, FAX: 901-448-7440,
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Hauger RL, Risbrough V, Brauns O, Dautzenberg FM. Corticotropin releasing factor (CRF) receptor signaling in the central nervous system: new molecular targets. CNS & NEUROLOGICAL DISORDERS DRUG TARGETS 2006; 5:453-79. [PMID: 16918397 PMCID: PMC1925123 DOI: 10.2174/187152706777950684] [Citation(s) in RCA: 246] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Corticotropin-releasing factor (CRF) and the related urocortin peptides mediate behavioral, cognitive, autonomic, neuroendocrine and immunologic responses to aversive stimuli by activating CRF(1) or CRF(2) receptors in the central nervous system and anterior pituitary. Markers of hyperactive central CRF systems, including CRF hypersecretion and abnormal hypothalamic-pituitary-adrenal axis functioning, have been identified in subpopulations of patients with anxiety, stress and depressive disorders. Because CRF receptors are rapidly desensitized in the presence of high agonist concentrations, CRF hypersecretion alone may be insufficient to account for the enhanced CRF neurotransmission observed in these patients. Concomitant dysregulation of mechanisms stringently controlling magnitude and duration of CRF receptor signaling also may contribute to this phenomenon. While it is well established that the CRF(1) receptor mediates many anxiety- and depression-like behaviors as well as HPA axis stress responses, CRF(2) receptor functions are not well understood at present. One hypothesis holds that CRF(1) receptor activation initiates fear and anxiety-like responses, while CRF(2) receptor activation re-establishes homeostasis by counteracting the aversive effects of CRF(1) receptor signaling. An alternative hypothesis posits that CRF(1) and CRF(2) receptors contribute to opposite defensive modes, with CRF(1) receptors mediating active defensive responses triggered by escapable stressors, and CRF(2) receptors mediating anxiety- and depression-like responses induced by inescapable, uncontrollable stressors. CRF(1) receptor antagonists are being developed as novel treatments for affective and stress disorders. If it is confirmed that the CRF(2) receptor contributes importantly to anxiety and depression, the development of small molecule CRF(2) receptor antagonists would be therapeutically useful.
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Affiliation(s)
- Richard L Hauger
- San Diego VA Healthcare System, University of California San Diego, La Jolla, 929093-0603, USA.
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Stimulation of neuropeptide Y-mediated calcium responses in human SMS-KAN neuroblastoma cells endogenously expressing Y2 receptors by co-expression of chimeric G proteins. Biochem Pharmacol 2005; 69:1493-9. [PMID: 15857613 DOI: 10.1016/j.bcp.2005.02.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2005] [Revised: 02/21/2005] [Accepted: 02/22/2005] [Indexed: 11/20/2022]
Abstract
Human SMS-KAN neuroblastoma cells endogenously express the neuropeptide Y (NPY) type 2 (Y(2)) receptor. Although ligand binding and GTPgammaS binding studies supported high functional Y(2) receptor expression, only weak coupling to the natural second messenger cyclic AMP was observed. The main reason was the low responsiveness of SMS-KAN cells to forskolin, a direct activator of adenylyl cyclases. In order to obtain a cell-based functional assay for the Y(2) receptor in SMS-KAN cells, the transient calcium (Ca(2+)) mobilization assay in the fluorimetric imaging plate reader (FLIPR) format was established by stably expressing a chimeric G protein Gq(i9). This manipulation resulted in robust mobilization of Ca(2+) after challenge with various NPY-related agonists in a 384-well format. The sensitivity of the FLIPR readout was in the low nanomolar range for NPY agonists and comparable to that of the recombinant Y(2) receptor. The selective Y(2) antagonist BIIE0246 competitively inhibited NPY-mediated Ca(2+) transients in SMS-KAN/Gq(i9) cells with a pA(2) value of 7.39+/-0.1. This is the first evidence that an endogenously expressed G protein-coupled receptor couples to an overexpressed chimeric G protein, thereby functionally responding in the FLIPR readout.
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Maya-Núñez G, Castro-Fernández C, Méndez JP. CRH-stimulation of cyclic adenosine 5'-monophosphate pathway is partially inhibited by the coexpression of CRH-R1 and CRH-R2alpha. Endocrine 2005; 27:67-73. [PMID: 16077174 DOI: 10.1385/endo:27:1:067] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2005] [Revised: 05/18/2005] [Accepted: 06/02/2005] [Indexed: 01/21/2023]
Abstract
Corticotropin-releasing hormone (CRH) is one of the major proteins responsible for brain stress regulation. Two well-known receptors have been described: type 1 and type 2alpha, both members of the receptor superfamily of G protein-coupled receptors (GPCR). We investigated receptor regulation when both CRH receptor subtypes are coexpressed in the same mammalian cell line. When both types of receptors are coexpressed, cAMP second messenger production is partially inhibited compared to when receptors are expressed separately. However, neither binding kinetics nor internalization rates are modified by coexpression of these receptors. To our knowledge this is the first demonstration of receptor interaction that results in the modification of CRH-mediated signal transduction pathway. Because CRH-R1 and CRH-R2alpha have overlapping mRNA expression patterns in the brain, these receptors may be coexpressed in neurons, suggesting that receptor interaction may play an important role in the effect evoked by CRH, contributing to the complexity of differential coupling of the CRH receptors in different endocrine and stress behavior responses.
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Affiliation(s)
- G Maya-Núñez
- Research Unit in Developmental Biology, Hospital de Pediatría, Centro Médico Nacional Siglo SXXI, Instituto Mexicano del Seguro Social, Mexico
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Dautzenberg FM, Higelin J, Pflieger P, Neidhart W, Guba W. Establishment of robust functional assays for the characterization of neuropeptide Y (NPY) receptors: identification of 3-(5-benzoyl-thiazol-2-ylamino)-benzonitrile as selective NPY type 5 receptor antagonist. Neuropharmacology 2005; 48:1043-55. [PMID: 15857631 DOI: 10.1016/j.neuropharm.2005.01.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2004] [Revised: 01/24/2005] [Accepted: 01/25/2005] [Indexed: 01/26/2023]
Abstract
The human Neuropeptide Y (NPY) receptors 1 (hY1), 2 (hY2), 4 (hY4), and the mouse type 5 (mY5) receptor were expressed in human embryonic kidney 293 (HEK293) cells. The receptors bound a radioiodinated NPY ligand with high affinity and various NPY analogs competed for binding in a receptor selective-manner. Similarly, cAMP-inhibition and GTPgammaS binding assays were established. The four NPY receptors were further tested in the fluorimetric imaging plate reader (FLIPR) format, a cellular high-throughput assay, in the absence and presence of chimeric G proteins, Gqo5, Gqi5 and Gqi9. The receptors stimulated transient calcium release only in the presence of chimeric G proteins. While hY1, hY2 and hY4 receptors coupled to Gqo5, Gqi5 and Gqi9, the mY5 receptor stimulated transient calcium release only when co-expressed with Gqi9. Using an in silico screening approach we identified a small molecule 3-(5-benzoyl-thiazol-2-ylamino)-benzonitrile (compound 1), which bound to the mY5 receptor with high affinity (Ki=32.1+/-1.8 nM), competitively antagonized NPY-mediated GTPgammaS binding and calcium stimulation with high potency, and had no affinity for other NPY receptors. These data show that NPY receptors can be functionally coupled to the FLIPR readout, allowing for high throughput compound testing and identification of novel molecules.
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Dautzenberg FM, Neysari S. Irreversible binding kinetics of neuropeptide Y ligands to Y2 but not to Y1 and Y5 receptors. Pharmacology 2005; 75:21-9. [PMID: 15908753 DOI: 10.1159/000085897] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2005] [Accepted: 03/29/2005] [Indexed: 01/10/2023]
Abstract
Neuropeptide Y (NPY) receptors type 1 (Y1), type 2 Y2) and type 5 (Y5) were tested for their kinetic properties to bind radiolabeled NPY or PYY. Rapid association and dissociation was observed with recombinant (HEK293 cells) and endogenous (SK-N-MC cells) human Y1 and recombinant mouse Y5 receptors. Recombinant (HEK293) and endogenous (SMS-KAN) human Y2 receptors bound both radiolabels comparable to the Y1 receptors, but only minimal ( approximately 20%) dissociation of both radiolabels was observed after long incubation time (>8 h). Furthermore, neither peptide nor small molecule Y2 ligands efficiently competed for binding to Y2 receptors once association binding had been initiated. The Y2-selective antagonist BIIE0246 behaved as an insurmountable antagonist in functional assays when pre-incubated for 30 min before agonist addition, but was a competitive antagonist when co-applied with the agonist. These data show that Y2 receptors in contrast to Y1 and Y5 receptors bind their ligands in an irreversible manner.
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