1
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Bhat S, Dietz A, Senf K, Nietzsche S, Hirabayashi Y, Westermann M, Neuhaus EM. GPRC5C regulates the composition of cilia in the olfactory system. BMC Biol 2023; 21:292. [PMID: 38110903 PMCID: PMC10729543 DOI: 10.1186/s12915-023-01790-0] [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: 07/07/2023] [Accepted: 11/30/2023] [Indexed: 12/20/2023] Open
Abstract
BACKGROUND Olfactory sensory neurons detect odourants via multiple long cilia that protrude from their dendritic endings. The G protein-coupled receptor GPRC5C was identified as part of the olfactory ciliary membrane proteome, but its function and localization is unknown. RESULTS High-resolution confocal and electron microscopy revealed that GPRC5C is located at the base of sensory cilia in olfactory neurons, but not in primary cilia of immature neurons or stem cells. Additionally, GPRC5C localization in sensory cilia parallels cilia formation and follows the formation of the basal body. In closer examination, GPRC5C was found in the ciliary transition zone. GPRC5C deficiency altered the structure of sensory cilia and increased ciliary layer thickness. However, primary cilia were unaffected. Olfactory sensory neurons from Gprc5c-deficient mice exhibited altered localization of olfactory signalling cascade proteins, and of ciliary phosphatidylinositol-4,5-bisphosphat. Sensory neurons also exhibited increased neuronal activity as well as altered mitochondrial morphology, and knockout mice had an improved ability to detect food pellets based on smell. CONCLUSIONS Our study shows that GPRC5C regulates olfactory cilia composition and length, thereby controlling odour perception.
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Affiliation(s)
- Sneha Bhat
- Pharmacology and Toxicology, Jena University Hospital, Friedrich Schiller University Jena, Drackendorfer Str. 1, 07747, Jena, Germany
| | - André Dietz
- Pharmacology and Toxicology, Jena University Hospital, Friedrich Schiller University Jena, Drackendorfer Str. 1, 07747, Jena, Germany
| | - Katja Senf
- Pharmacology and Toxicology, Jena University Hospital, Friedrich Schiller University Jena, Drackendorfer Str. 1, 07747, Jena, Germany
| | - Sandor Nietzsche
- Centre for Electron Microscopy, Jena University Hospital, Friedrich Schiller University Jena, Ziegelmühlenweg 1, 07743, Jena, Germany
| | - Yoshio Hirabayashi
- Institute for Environmental and Gender-Specific Medicine, Juntendo University Graduate School of Medicine, Chiba, 279-0021, Japan
- RIKEN Cluster for Pioneering Research, RIKEN, Wako, Saitama, 351-0198, Japan
| | - Martin Westermann
- Centre for Electron Microscopy, Jena University Hospital, Friedrich Schiller University Jena, Ziegelmühlenweg 1, 07743, Jena, Germany
| | - Eva Maria Neuhaus
- Pharmacology and Toxicology, Jena University Hospital, Friedrich Schiller University Jena, Drackendorfer Str. 1, 07747, Jena, Germany.
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2
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Hu Z, Yang J. Structural basis of properties, mechanisms, and channelopathy of cyclic nucleotide-gated channels. Channels (Austin) 2023; 17:2273165. [PMID: 37905307 PMCID: PMC10761061 DOI: 10.1080/19336950.2023.2273165] [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: 09/07/2023] [Accepted: 10/07/2023] [Indexed: 11/02/2023] Open
Abstract
Recent years have seen an outpouring of atomic or near atomic resolution structures of cyclic nucleotide-gated (CNG) channels, captured in closed, transition, pre-open, partially open, and fully open states. These structures provide unprecedented molecular insights into the activation, assembly, architecture, regulation, and channelopathy of CNG channels, as well as mechanistic explanations for CNG channel biophysical and pharmacological properties. This article summarizes recent advances in CNG channel structural biology, describes key structural features and elements, and illuminates a detailed conformational landscape of activation by cyclic nucleotides. The review also correlates structures with findings and properties delineated in functional studies, including nonselective monovalent cation selectivity, Ca2+ permeation and block, block by L-cis-diltiazem, location of the activation gate, lack of voltage-dependent gating, and modulation by lipids and calmodulin. A perspective on future research is also offered.
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Affiliation(s)
- Zhengshan Hu
- Department of Biological Sciences, Columbia University, New York, NY, USA
| | - Jian Yang
- Department of Biological Sciences, Columbia University, New York, NY, USA
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3
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Hu Z, Zheng X, Yang J. Conformational trajectory of allosteric gating of the human cone photoreceptor cyclic nucleotide-gated channel. Nat Commun 2023; 14:4284. [PMID: 37463923 DOI: 10.1038/s41467-023-39971-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 07/05/2023] [Indexed: 07/20/2023] Open
Abstract
Cyclic nucleotide-gated (CNG) channels transduce chemical signals into electrical signals in sensory receptors and neurons. They are activated by cGMP or cAMP, which bind to the cyclic nucleotide-binding domain (CNBD) to open a gate located 50-60 Å away in the central cavity. Structures of closed and open vertebrate CNG channels have been solved, but the conformational landscape of this allosteric gating remains to be elucidated and enriched. Here, we report structures of the cGMP-activated human cone photoreceptor CNGA3/CNGB3 channel in closed, intermediate, pre-open and open states in detergent or lipid nanodisc, all with fully bound cGMP. The pre-open and open states are obtained only in the lipid nanodisc, suggesting a critical role of lipids in tuning the energetic landscape of CNGA3/CNGB3 activation. The different states exhibit subunit-unique, incremental and distinct conformational rearrangements that originate in the CNBD, propagate through the gating ring to the transmembrane domain, and gradually open the S6 cavity gate. Our work illustrates a spatial conformational-change wave of allosteric gating of a vertebrate CNG channel by its natural ligand and provides an expanded framework for studying CNG properties and channelopathy.
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Affiliation(s)
- Zhengshan Hu
- Department of Biological Sciences, Columbia University, New York, NY, 10027, USA
| | - Xiangdong Zheng
- Department of Biological Sciences, Columbia University, New York, NY, 10027, USA
| | - Jian Yang
- Department of Biological Sciences, Columbia University, New York, NY, 10027, USA.
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4
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Abstract
There is increasing appreciation that G-protein-coupled receptors (GPCRs) can initiate diverse cellular responses by activating multiple G proteins, arrestins, and other biochemical effectors. Structurally different ligands targeting the same receptor are thought to stabilize the receptor in multiple distinct active conformations such that specific subsets of signaling effectors are engaged at the exclusion of others, creating a bias toward a particular outcome, which has been referred to as ligand-induced selective signaling, biased agonism, ligand-directed signaling, and functional selectivity, among others. The potential involvement of functional selectivity in mammalian olfactory signal transduction has received little attention, notwithstanding the fact that mammalian olfactory receptors comprise the largest family of mammalian GPCRs. This position review considers the possibility that, although such complexity in G-protein function may have been lost in the specialization of olfactory receptors to serve as sensory receptors, the ability of olfactory receptor neurons (ORNs) to function as signal integrators and growing appreciation that this functionality is widespread in the receptor population suggest otherwise. We pose that functional selectivity driving 2 opponent inputs have the potential to generate an output that reflects the balance of ligand-dependent signaling, the direction of which could be either suppressive or synergistic and, as such, needs to be considered as a mechanistic basis for signal integration in mammalian ORNs.
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Affiliation(s)
- Barry W Ache
- Whitney Laboratory, Departments of Biology and Neuroscience, and Center for Smell and Taste, University of Florida, Gainesville, FL, USA
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5
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Ukhanov K, Uytingco C, Green W, Zhang L, Schurmans S, Martens JR. INPP5E controls ciliary localization of phospholipids and the odor response in olfactory sensory neurons. J Cell Sci 2021; 135:jcs.258364. [PMID: 33771931 PMCID: PMC8126451 DOI: 10.1242/jcs.258364] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 03/15/2021] [Indexed: 12/12/2022] Open
Abstract
The lipid composition of the primary cilia membrane is emerging as a critical regulator of cilia formation, maintenance and function. Here, we show that conditional deletion of the phosphoinositide 5′-phosphatase gene Inpp5e, mutation of which is causative of Joubert syndrome, in terminally developed mouse olfactory sensory neurons (OSNs), leads to a dramatic remodeling of ciliary phospholipids that is accompanied by marked elongation of cilia. Phosphatidylinositol (4,5)-bisphosphate [PI(4,5)P2], which is normally restricted to the proximal segment redistributed to the entire length of cilia in Inpp5e knockout mice with a reduction in phosphatidylinositol (3,4)-bisphosphate [PI(3,4)P2] and elevation of phosphatidylinositol (3,4,5)-trisphosphate [PI(3,4,5)P3] in the dendritic knob. The redistribution of phosphoinositides impaired odor adaptation, resulting in less efficient recovery and altered inactivation kinetics of the odor-evoked electrical response and the odor-induced elevation of cytoplasmic Ca2+. Gene replacement of Inpp5e through adenoviral expression restored the ciliary localization of PI(4,5)P2 and odor response kinetics in OSNs. Our findings support the role of phosphoinositides as a modulator of the odor response and in ciliary biology of native multi-ciliated OSNs. Summary: Cilia of olfactory sensory neurons have a unique lipid composition. Localization of phospholipids is controlled by the INPP5E phosphatase and is involved in modulation of the odor response.
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Affiliation(s)
- Kirill Ukhanov
- University of Florida, Department of Pharmacology and Therapeutics, Gainesville, FL 32603, USA.,University of Florida, Center for Smell and Taste, FL 32610-0267, USA
| | - Cedric Uytingco
- University of Florida, Department of Pharmacology and Therapeutics, Gainesville, FL 32603, USA
| | - Warren Green
- University of Florida, Department of Pharmacology and Therapeutics, Gainesville, FL 32603, USA
| | - Lian Zhang
- University of Florida, Department of Pharmacology and Therapeutics, Gainesville, FL 32603, USA.,University of Florida, Center for Smell and Taste, FL 32610-0267, USA
| | - Stephane Schurmans
- Laboratory of Functional Genetics, GIGA-Molecular Biology of Disease, University of Liège, Liège, Belgium
| | - Jeffrey R Martens
- University of Florida, Department of Pharmacology and Therapeutics, Gainesville, FL 32603, USA.,University of Florida, Center for Smell and Taste, FL 32610-0267, USA
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6
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Ali MA, Wang Y, Qin Z, Yuan X, Zhang Y, Zeng C. Odorant and Taste Receptors in Sperm Chemotaxis and Cryopreservation: Roles and Implications in Sperm Capacitation, Motility and Fertility. Genes (Basel) 2021; 12:genes12040488. [PMID: 33801624 PMCID: PMC8065900 DOI: 10.3390/genes12040488] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 03/24/2021] [Accepted: 03/24/2021] [Indexed: 11/24/2022] Open
Abstract
Sperm chemotaxis, which guide sperm toward oocyte, is tightly associated with sperm capacitation, motility, and fertility. However, the molecular mechanism of sperm chemotaxis is not known. Reproductive odorant and taste receptors, belong to G-protein-coupled receptors (GPCR) super-family, cause an increase in intracellular Ca2+ concentration which is pre-requisite for sperm capacitation and acrosomal reaction, and result in sperm hyperpolarization and increase motility through activation of Ca2+-dependent Cl¯ channels. Recently, odorant receptors (ORs) in olfactory transduction pathway were thought to be associated with post-thaw sperm motility, freeze tolerance or freezability and cryo-capacitation-like change during cryopreservation. Investigation of the roles of odorant and taste receptors (TRs) is important for our understanding of the freeze tolerance or freezability mechanism and improve the motility and fertility of post-thaw sperm. Here, we reviewed the roles, mode of action, impact of odorant and taste receptors on sperm chemotaxis and post-thaw sperm quality.
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Affiliation(s)
- Malik Ahsan Ali
- College of Animal Science and Technology and Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, Sichuan, China; (Y.W.); (Z.Q.); (X.Y.); (Y.Z.)
- Department of Theriogenology, Riphah College of Veterinary Sciences, Lahore 54000, Punjab, Pakistan;
- Department of Theriogenology, Faculty of Veterinary Science, University of Agriculture, Faisalabad 38000, Punjab, Pakistan
| | - Yihan Wang
- College of Animal Science and Technology and Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, Sichuan, China; (Y.W.); (Z.Q.); (X.Y.); (Y.Z.)
| | - Ziyue Qin
- College of Animal Science and Technology and Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, Sichuan, China; (Y.W.); (Z.Q.); (X.Y.); (Y.Z.)
| | - Xiang Yuan
- College of Animal Science and Technology and Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, Sichuan, China; (Y.W.); (Z.Q.); (X.Y.); (Y.Z.)
| | - Yan Zhang
- College of Animal Science and Technology and Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, Sichuan, China; (Y.W.); (Z.Q.); (X.Y.); (Y.Z.)
| | - Changjun Zeng
- College of Animal Science and Technology and Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, Sichuan, China; (Y.W.); (Z.Q.); (X.Y.); (Y.Z.)
- Correspondence: ; Tel./Fax: +86-28-86291010
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7
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Corey EA, Ukhanov K, Bobkov YV, McIntyre JC, Martens JR, Ache BW. Inhibitory signaling in mammalian olfactory transduction potentially mediated by Gα o. Mol Cell Neurosci 2020; 110:103585. [PMID: 33358996 DOI: 10.1016/j.mcn.2020.103585] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 11/27/2020] [Accepted: 12/09/2020] [Indexed: 01/12/2023] Open
Abstract
Olfactory GPCRs (ORs) in mammalian olfactory receptor neurons (ORNs) mediate excitation through the Gαs family member Gαolf. Here we tentatively associate a second G protein, Gαo, with inhibitory signaling in mammalian olfactory transduction by first showing that odor evoked phosphoinositide 3-kinase (PI3K)-dependent inhibition of signal transduction is absent in the native ORNs of mice carrying a conditional OMP-Cre based knockout of Gαo. We then identify an OR from native rat ORNs that are activated by octanol through cyclic nucleotide signaling and inhibited by citral in a PI3K-dependent manner. We show that the OR activates cyclic nucleotide signaling and PI3K signaling in a manner that reflects its functionality in native ORNs. Our findings lay the groundwork to explore the interesting possibility that ORs can interact with two different G proteins in a functionally identified, ligand-dependent manner to mediate opponent signaling in mature mammalian ORNs.
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Affiliation(s)
- Elizabeth A Corey
- Whitney Laboratory, Center for Smell and Taste, University of Florida, Gainesville, FL 32610, United States of America
| | - Kirill Ukhanov
- Dept. of Pharmacology and Therapeutics, Center for Smell and Taste, University of Florida, Gainesville, FL 32610, United States of America
| | - Yuriy V Bobkov
- Whitney Laboratory, Center for Smell and Taste, University of Florida, Gainesville, FL 32610, United States of America
| | - Jeremy C McIntyre
- Dept. of Neuroscience, Center for Smell and Taste, University of Florida, Gainesville, FL 32610, United States of America
| | - Jeffrey R Martens
- Dept. of Pharmacology and Therapeutics, Center for Smell and Taste, University of Florida, Gainesville, FL 32610, United States of America
| | - Barry W Ache
- Whitney Laboratory, Dept. of Biology, Center for Smell and Taste, University of Florida, Gainesville, FL 32610, United States of America; Whitney Laboratory, Dept. of Neuroscience, Center for Smell and Taste, University of Florida, Gainesville, FL 32610, United States of America.
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8
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Zheng X, Fu Z, Su D, Zhang Y, Li M, Pan Y, Li H, Li S, Grassucci RA, Ren Z, Hu Z, Li X, Zhou M, Li G, Frank J, Yang J. Mechanism of ligand activation of a eukaryotic cyclic nucleotide-gated channel. Nat Struct Mol Biol 2020; 27:625-634. [PMID: 32483338 PMCID: PMC7354226 DOI: 10.1038/s41594-020-0433-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 04/10/2020] [Indexed: 01/21/2023]
Abstract
Cyclic nucleotide-gated (CNG) channels convert cyclic nucleotide (CN) binding and unbinding into electrical signals in sensory receptors and neurons. The molecular conformational changes underpinning ligand activation are largely undefined. We report both closed- and open-state atomic cryo-EM structures of a full-length Caenorhabditis elegans cyclic GMP-activated channel TAX-4, reconstituted in lipid nanodiscs. These structures, together with computational and functional analyses and a mutant channel structure, reveal a double-barrier hydrophobic gate formed by two S6 amino acids in the central cavity. cGMP binding produces global conformational changes that open the cavity gate located ~52 Å away but do not alter the structure of the selectivity filter-the commonly presumed activation gate. Our work provides mechanistic insights into the allosteric gating and regulation of CN-gated and nucleotide-modulated channels and CNG channel-related channelopathies.
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Affiliation(s)
- Xiangdong Zheng
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA,These authors contributed equally to this work
| | - Ziao Fu
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA,These authors contributed equally to this work
| | - Deyuan Su
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Chinese Academy of Sciences, Kunming 650223, China,These authors contributed equally to this work
| | - Yuebin Zhang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Minghui Li
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA,Current address: HIT Center for Life Sciences, School of Life Science and Technology, Harbin Institute of Technology, Harbin 150001, China
| | - Yaping Pan
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Huan Li
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Shufang Li
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA,Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Robert A. Grassucci
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Zhenning Ren
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Zhengshan Hu
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Xueming Li
- Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Ming Zhou
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Guohui Li
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Joachim Frank
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA,Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Jian Yang
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA,Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences/Key Laboratory of Bioactive Peptides of Yunnan Province, Chinese Academy of Sciences, Kunming 650223, China
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9
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Le Bon AM, Deprêtre N, Sibille E, Cabaret S, Grégoire S, Soubeyre V, Masson E, Acar N, Bretillon L, Grosmaitre X, Berdeaux O. Comprehensive study of rodent olfactory tissue lipid composition. Prostaglandins Leukot Essent Fatty Acids 2018; 131:32-43. [PMID: 29628048 DOI: 10.1016/j.plefa.2018.03.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 02/20/2018] [Accepted: 03/21/2018] [Indexed: 11/20/2022]
Abstract
The peripheral olfactory tissue (OT) plays a primordial role in the detection and transduction of olfactory information. Recent proteomic and transcriptomic studies have provided valuable insight into proteins and RNAs expressed in this tissue. Paradoxically, there is little information regarding the lipid composition of mammalian OT. To delve further into this issue, using a set of complementary state-of-the-art techniques, we carried out a comprehensive analysis of OT lipid composition in rats and mice fed with standard diets. The results showed that phospholipids are largely predominant, the major classes being phosphatidylcholine and phosphatidylethanolamine. Two types of plasmalogens, plasmenyl-choline and plasmenyl-ethanolamine, as well as gangliosides were also detected. With the exception of sphingomyelin, substantial levels of n-3 polyunsaturated fatty acids, mainly docosahexaenoic acid (22:6n-3; DHA), were found in the different phospholipid classes. These findings demonstrate that the rodent OT shares several features in common with other neural tissues, such as the brain and retina.
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Affiliation(s)
- Anne Marie Le Bon
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, 9E Boulevard Jeanne d'Arc, F-21000 Dijon, France.
| | - Nicolas Deprêtre
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, 9E Boulevard Jeanne d'Arc, F-21000 Dijon, France
| | - Estelle Sibille
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, 9E Boulevard Jeanne d'Arc, F-21000 Dijon, France
| | - Stéphanie Cabaret
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, 9E Boulevard Jeanne d'Arc, F-21000 Dijon, France
| | - Stéphane Grégoire
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, 9E Boulevard Jeanne d'Arc, F-21000 Dijon, France
| | - Vanessa Soubeyre
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, 9E Boulevard Jeanne d'Arc, F-21000 Dijon, France
| | - Elodie Masson
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, 9E Boulevard Jeanne d'Arc, F-21000 Dijon, France
| | - Niyazi Acar
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, 9E Boulevard Jeanne d'Arc, F-21000 Dijon, France
| | - Lionel Bretillon
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, 9E Boulevard Jeanne d'Arc, F-21000 Dijon, France
| | - Xavier Grosmaitre
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, 9E Boulevard Jeanne d'Arc, F-21000 Dijon, France
| | - Olivier Berdeaux
- Centre des Sciences du Goût et de l'Alimentation, AgroSup Dijon, CNRS, INRA, Université Bourgogne Franche-Comté, 9E Boulevard Jeanne d'Arc, F-21000 Dijon, France
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10
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Kalbe B, Schlimm M, Mohrhardt J, Scholz P, Jansen F, Hatt H, Osterloh S. Helional induces Ca2+ decrease and serotonin secretion of QGP-1 cells via a PKG-mediated pathway. J Mol Endocrinol 2016; 57:201-10. [PMID: 27553203 DOI: 10.1530/jme-16-0063] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 08/22/2016] [Indexed: 12/30/2022]
Abstract
The secretion, motility and transport by intestinal tissues are regulated among others by specialized neuroendocrine cells, the so-called enterochromaffin (EC) cells. These cells detect different luminal stimuli, such as mechanical stimuli, fatty acids, glucose and distinct chemosensory substances. The EC cells react to the changes in their environment through the release of transmitter molecules, most importantly serotonin, to mediate the corresponding physiological response. However, little is known about the molecular targets of the chemical stimuli delivered from consumed food, spices and cosmetics within EC cells. In this study, we evaluated the expression of the olfactory receptor (OR) 2J3 in the human pancreatic EC cell line QGP-1 at the mRNA and protein levels. Using ratiofluorometric Ca(2+) imaging experiments, we demonstrated that the OR2J3-specific agonist helional induces a transient dose-dependent decrease in the intracellular Ca(2+) levels. This Ca(2+) decrease is mediated by protein kinase G (PKG) on the basis that the specific pharmacological inhibition of PKG with Rp-8-pCPT-cGMPS abolished the helional-induced Ca(2+) response. Furthermore, stimulation of QGP-1 cells with helional caused a dose-dependent release of serotonin that was comparable with the release induced by the application of a direct PKG activator (8-bromo-cGMP). Taken together, our results demonstrate that luminal odorants can be detected by specific ORs in QGP-1 cells and thus cause the directed release of serotonin and a PKG-dependent decrease in intracellular Ca(2.)
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Affiliation(s)
- Benjamin Kalbe
- Department of Cell PhysiologyRuhr-University Bochum, Bochum, Germany
| | - Marian Schlimm
- Department of Cell PhysiologyRuhr-University Bochum, Bochum, Germany
| | - Julia Mohrhardt
- Department of ChemosensationInstitute for Biology II, RWTH Aachen University, Aachen, Germany
| | - Paul Scholz
- Department of Cell PhysiologyRuhr-University Bochum, Bochum, Germany
| | - Fabian Jansen
- Department of Cell PhysiologyRuhr-University Bochum, Bochum, Germany
| | - Hanns Hatt
- Department of Cell PhysiologyRuhr-University Bochum, Bochum, Germany
| | - Sabrina Osterloh
- Department of Cell PhysiologyRuhr-University Bochum, Bochum, Germany
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11
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Ukhanov K, Corey E, Ache BW. Phosphoinositide-3-Kinase Is the Primary Mediator of Phosphoinositide-Dependent Inhibition in Mammalian Olfactory Receptor Neurons. Front Cell Neurosci 2016; 10:97. [PMID: 27147969 PMCID: PMC4826873 DOI: 10.3389/fncel.2016.00097] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 03/29/2016] [Indexed: 11/24/2022] Open
Abstract
Odorants inhibit as well as excite primary olfactory receptor neurons (ORNs) in many animal species. Growing evidence suggests that inhibition of mammalian ORNs is mediated by phosphoinositide (PI) signaling through activation of phosphoinositide 3-kinase (PI3K), and that canonical adenylyl cyclase III signaling and PI3K signaling interact to provide the basis for ligand-induced selective signaling. As PI3K is known to act in concert with phospholipase C (PLC) in some cellular systems, the question arises as to whether they work together to mediate inhibitory transduction in mammalian ORNs. The present study is designed to test this hypothesis. While we establish that multiple PLC isoforms are expressed in the transduction zone of rat ORNs, that odorants can activate PLC in ORNs in situ, and that pharmacological blockade of PLC enhances the excitatory response to an odorant mixture in some ORNs in conjunction with PI3K blockade, we find that by itself PLC does not account for an inhibitory response. We conclude that PLC does not make a measurable independent contribution to odor-evoked inhibition, and that PI3K is the primary mediator of PI-dependent inhibition in mammalian ORNs.
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Affiliation(s)
- Kirill Ukhanov
- Department of Pharmacology and Therapeutics, University of Florida Gainesville, FL, USA
| | - Elizabeth Corey
- Whitney Laboratory, Center for Smell and Taste, McKnight Brain Institute Gainesville, FL, USA
| | - Barry W Ache
- Whitney Laboratory, Center for Smell and Taste, McKnight Brain InstituteGainesville, FL, USA; Department of Biology and Neuroscience, University of FloridaGainesville, FL, USA
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12
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Scholz P, Mohrhardt J, Jansen F, Kalbe B, Haering C, Klasen K, Hatt H, Osterloh S. Identification of a Novel Gnao-Mediated Alternate Olfactory Signaling Pathway in Murine OSNs. Front Cell Neurosci 2016; 10:63. [PMID: 27065801 PMCID: PMC4809895 DOI: 10.3389/fncel.2016.00063] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 02/29/2016] [Indexed: 12/23/2022] Open
Abstract
It is generally agreed that in olfactory sensory neurons (OSNs), the binding of odorant molecules to their specific olfactory receptor (OR) triggers a cAMP-dependent signaling cascade, activating cyclic-nucleotide gated (CNG) channels. However, considerable controversy dating back more than 20 years has surrounded the question of whether alternate signaling plays a role in mammalian olfactory transduction. In this study, we demonstrate a specific alternate signaling pathway in Olfr73-expressing OSNs. Methylisoeugenol (MIEG) and at least one other known weak Olfr73 agonist (Raspberry Ketone) trigger a signaling cascade independent from the canonical pathway, leading to the depolarization of the cell. Interestingly, this pathway is mediated by Gnao activation, leading to Cl(-) efflux; however, the activation of adenylyl cyclase III (ACIII), the recruitment of Ca(2+) from extra-or intracellular stores, and phosphatidylinositol 3-kinase-dependent signaling (PI signaling) are not involved. Furthermore, we demonstrated that our newly identified pathway coexists with the canonical olfactory cAMP pathway in the same OSN and can be triggered by the same OR in a ligand-selective manner. We suggest that this pathway might reflect a mechanism for odor recognition predominantly used in early developmental stages before olfactory cAMP signaling is fully developed. Taken together, our findings support the existence of at least one odor-induced alternate signal transduction pathway in native OSNs mediated by Olfr73 in a ligand-selective manner.
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Affiliation(s)
- Paul Scholz
- Department of Cell Physiology, Ruhr-University Bochum Bochum, Germany
| | - Julia Mohrhardt
- Department of Cell Physiology, Ruhr-University Bochum Bochum, Germany
| | - Fabian Jansen
- Department of Cell Physiology, Ruhr-University Bochum Bochum, Germany
| | - Benjamin Kalbe
- Department of Cell Physiology, Ruhr-University Bochum Bochum, Germany
| | - Claudia Haering
- Department of Cell Physiology, Ruhr-University Bochum Bochum, Germany
| | - Katharina Klasen
- Department of Cell Physiology, Ruhr-University Bochum Bochum, Germany
| | - Hanns Hatt
- Department of Cell Physiology, Ruhr-University Bochum Bochum, Germany
| | - Sabrina Osterloh
- Department of Cell Physiology, Ruhr-University Bochum Bochum, Germany
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13
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The Stimulus-Dependent Gradient of Cyp26B1+ Olfactory Sensory Neurons Is Necessary for the Functional Integrity of the Olfactory Sensory Map. J Neurosci 2016; 35:13807-18. [PMID: 26446231 DOI: 10.1523/jneurosci.2247-15.2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED Stimulus-dependent expression of the retinoic acid-inactivating enzyme Cyp26B1 in olfactory sensory neurons (OSNs) forms a dorsomedial (DM)-ventrolateral (VL) gradient in the mouse olfactory epithelium. The gradient correlates spatially with different rates of OSN turnover, as well as the functional organization of the olfactory sensory map, into overlapping zones of OSNs that express different odorant receptors (ORs). Here, we analyze transgenic mice that, instead of a stimulus-dependent Cyp26B1 gradient, have constitutive Cyp26B1 levels in all OSNs. Starting postnatally, OSN differentiation is decreased and progenitor proliferation is increased. Initially, these effects are selective to the VL-most zone and correlate with reduced ATF5 expression and accumulation of OSNs that do not express ORs. Transcription factor ATF5 is known to stabilize OR gene choice via onset of the stimulus-transducing enzyme adenylyl cyclase type 3. During further postnatal development of Cyp26B1 mice, an anomalous DM(high)-VL(low) expression gradient of adenylyl cyclase type 3 appears, which coincides with altered OR frequencies and OR zones. All OR zones expand ventrolaterally except for the VL-most zone, which contracts. The expansion results in an increased zonal overlap that is also evident in the innervation pattern of OSN axon terminals in olfactory bulbs. These findings together identify a mechanism by which postnatal sensory-stimulated vitamin A metabolism modifies the generation of spatially specified neurons and their precise topographic connectivity. The distributed patterns of vitamin A-metabolizing enzymes in the nervous system suggest the possibility that the mechanism may also regulate neuroplasticity in circuits other than the olfactory sensory map. SIGNIFICANCE STATEMENT The mouse olfactory sensory map is functionally wired according to precise axonal projections of spatially organized classes of olfactory sensory neurons in the nose. The genetically controlled mechanisms that regulate the development of the olfactory sensory map are beginning to be elucidated. Little is known about mechanisms by which sensory stimuli shape the organization of the map after birth. We show that a stimulus-dependent gradient of a retinoic acid-inactivating enzyme Cyp26B1 modifies the composition, localization, and axonal projections of olfactory sensory neuron classes. The mechanism is novel and suggests the interesting possibility that local vitamin A metabolism could also be a mediator of stimulus-dependent modifications of precise spatial connectivity in other parts of the nervous system.
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14
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Jarriault D, Grosmaitre X. Perforated Patch-clamp Recording of Mouse Olfactory Sensory Neurons in Intact Neuroepithelium: Functional Analysis of Neurons Expressing an Identified Odorant Receptor. J Vis Exp 2015:e52652. [PMID: 26275097 DOI: 10.3791/52652] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Analyzing the physiological responses of olfactory sensory neurons (OSN) when stimulated with specific ligands is critical to understand the basis of olfactory-driven behaviors and their modulation. These coding properties depend heavily on the initial interaction between odor molecules and the olfactory receptor (OR) expressed in the OSNs. The identity, specificity and ligand spectrum of the expressed OR are critical. The probability to find the ligand of the OR expressed in an OSN chosen randomly within the epithelium is very low. To address this challenge, this protocol uses genetically tagged mice expressing the fluorescent protein GFP under the control of the promoter of defined ORs. OSNs are located in a tight and organized epithelium lining the nasal cavity, with neighboring cells influencing their maturation and function. Here we describe a method to isolate an intact olfactory epithelium and record through patch-clamp recordings the properties of OSNs expressing defined odorant receptors. The protocol allows one to characterize OSN membrane properties while keeping the influence of the neighboring tissue. Analysis of patch-clamp results yields a precise quantification of ligand/OR interactions, transduction pathways and pharmacology, OSNs' coding properties and their modulation at the membrane level.
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Affiliation(s)
- David Jarriault
- UMR Centre des Sciences du Goŭt et de l'Alimentation, CNRS, INRA, Université de Bourgogne
| | - Xavier Grosmaitre
- UMR Centre des Sciences du Goŭt et de l'Alimentation, CNRS, INRA, Université de Bourgogne;
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15
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Kim SY, Yoo SJ, Ronnett GV, Kim EK, Moon C. Odorant Stimulation Promotes Survival of Rodent Olfactory Receptor Neurons via PI3K/Akt Activation and Bcl-2 Expression. Mol Cells 2015; 38:535-9. [PMID: 25997735 PMCID: PMC4469911 DOI: 10.14348/molcells.2015.0038] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2015] [Accepted: 03/12/2015] [Indexed: 11/27/2022] Open
Abstract
Olfactory stimulation activates multiple signaling cascades in order to mediate activity-driven changes in gene expression that promote neuronal survival. To date, the mechanisms involved in activity-dependent olfactory neuronal survival have yet to be fully elucidated. In the current study, we observed that olfactory sensory stimulation, which caused neuronal activation, promoted activation of the phosphatidylinositol 3'-kinase (PI3K)/Akt pathway and the expression of Bcl-2, which were responsible for olfactory receptor neuron (ORN) survival. We demonstrated that Bcl-2 expression increased after odorant stimulation both in vivo and in vitro. We also showed that odorant stimulation activated Akt, and that Akt activation was completely blocked by incubation with both a PI3K inhibitor (LY294002) and Akt1 small interfering RNA. Moreover, blocking the PI3K/Akt pathway diminished the odorant-induced Bcl-2 expression, as well as the effects on odorant-induced ORN survival. A temporal difference was noted between the activation of Akt1 and the expression of Bcl-2 following odorant stimulation. Blocking the PI3K/Akt pathway did not affect ORN survival in the time range prior to the increase in Bcl-2 expression, implying that these two events, activation of the PI3K pathway and Bcl-2 induction, were tightly connected to promote post-translational ORN survival. Collectively, our results indicated that olfactory activity activated PI3K/Akt, induced Bcl-2, and promoted long term ORN survival as a result.
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Affiliation(s)
- So Yeun Kim
- Department of Brain & Cognitive Sciences, Graduate School Daegu Gyeungbuk Institute of Science and Technology (DGIST), Daegu 711-873,
Korea
| | - Seung-Jun Yoo
- Department of Brain & Cognitive Sciences, Graduate School Daegu Gyeungbuk Institute of Science and Technology (DGIST), Daegu 711-873,
Korea
| | - Gabriele V Ronnett
- Department of Brain & Cognitive Sciences, Graduate School Daegu Gyeungbuk Institute of Science and Technology (DGIST), Daegu 711-873,
Korea
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205,
USA
- Department of Biological Chemistry, The Johns Hopkins University School of Medicine, Baltimore, MD 21205,
USA
| | - Eun-Kyoung Kim
- Department of Brain & Cognitive Sciences, Graduate School Daegu Gyeungbuk Institute of Science and Technology (DGIST), Daegu 711-873,
Korea
| | - Cheil Moon
- Department of Brain & Cognitive Sciences, Graduate School Daegu Gyeungbuk Institute of Science and Technology (DGIST), Daegu 711-873,
Korea
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16
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Haering C, Kanageswaran N, Bouvain P, Scholz P, Altmüller J, Becker C, Gisselmann G, Wäring-Bischof J, Hatt H. Ion transporter NKCC1, modulator of neurogenesis in murine olfactory neurons. J Biol Chem 2015; 290:9767-79. [PMID: 25713142 DOI: 10.1074/jbc.m115.640656] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Indexed: 12/28/2022] Open
Abstract
Olfaction is one of the most crucial senses for vertebrates regarding foraging and social behavior. Therefore, it is of particular interest to investigate the sense of smell, its function on a molecular level, the signaling proteins involved in the process and the mechanism of required ion transport. In recent years, the precise role of the ion transporter NKCC1 in olfactory sensory neuron (OSN) chloride accumulation has been a controversial subject. NKCC1 is expressed in OSNs and is involved in chloride accumulation of dissociated neurons, but it had not been shown to play a role in mouse odorant sensation. Here, we present electro-olfactogram recordings (EOG) demonstrating that NKCC1-deficient mice exhibit significant defects in perception of a complex odorant mixture (Henkel100) in both air-phase and submerged approaches. Using next generation sequencing (NGS) and RT-PCR experiments of NKCC1-deficient and wild type mouse transcriptomes, we confirmed the absence of a highly expressed ion transporter that could compensate for NKCC1. Additional histological investigations demonstrated a reduced number of cells in the olfactory epithelium (OE), resulting in a thinner neuronal layer. Therefore, we conclude that NKCC1 is an important transporter involved in chloride ion accumulation in the olfactory epithelium, but it is also involved in OSN neurogenesis.
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Affiliation(s)
- Claudia Haering
- From Cell Physiology, Ruhr-University Bochum, Universitaetsstr.150, 44780 Bochum, Germany and
| | - Ninthujah Kanageswaran
- From Cell Physiology, Ruhr-University Bochum, Universitaetsstr.150, 44780 Bochum, Germany and
| | - Pascal Bouvain
- From Cell Physiology, Ruhr-University Bochum, Universitaetsstr.150, 44780 Bochum, Germany and
| | - Paul Scholz
- From Cell Physiology, Ruhr-University Bochum, Universitaetsstr.150, 44780 Bochum, Germany and
| | - Janine Altmüller
- the University of Köln, Cologne Center for Genomics, Köln, Germany
| | - Christian Becker
- the University of Köln, Cologne Center for Genomics, Köln, Germany
| | - Günter Gisselmann
- From Cell Physiology, Ruhr-University Bochum, Universitaetsstr.150, 44780 Bochum, Germany and
| | - Janine Wäring-Bischof
- From Cell Physiology, Ruhr-University Bochum, Universitaetsstr.150, 44780 Bochum, Germany and
| | - Hanns Hatt
- From Cell Physiology, Ruhr-University Bochum, Universitaetsstr.150, 44780 Bochum, Germany and
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17
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Kanageswaran N, Demond M, Nagel M, Schreiner BSP, Baumgart S, Scholz P, Altmüller J, Becker C, Doerner JF, Conrad H, Oberland S, Wetzel CH, Neuhaus EM, Hatt H, Gisselmann G. Deep sequencing of the murine olfactory receptor neuron transcriptome. PLoS One 2015; 10:e0113170. [PMID: 25590618 PMCID: PMC4295871 DOI: 10.1371/journal.pone.0113170] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 10/25/2014] [Indexed: 11/18/2022] Open
Abstract
The ability of animals to sense and differentiate among thousands of odorants relies on a large set of olfactory receptors (OR) and a multitude of accessory proteins within the olfactory epithelium (OE). ORs and related signaling mechanisms have been the subject of intensive studies over the past years, but our knowledge regarding olfactory processing remains limited. The recent development of next generation sequencing (NGS) techniques encouraged us to assess the transcriptome of the murine OE. We analyzed RNA from OEs of female and male adult mice and from fluorescence-activated cell sorting (FACS)-sorted olfactory receptor neurons (ORNs) obtained from transgenic OMP-GFP mice. The Illumina RNA-Seq protocol was utilized to generate up to 86 million reads per transcriptome. In OE samples, nearly all OR and trace amine-associated receptor (TAAR) genes involved in the perception of volatile amines were detectably expressed. Other genes known to participate in olfactory signaling pathways were among the 200 genes with the highest expression levels in the OE. To identify OE-specific genes, we compared olfactory neuron expression profiles with RNA-Seq transcriptome data from different murine tissues. By analyzing different transcript classes, we detected the expression of non-olfactory GPCRs in ORNs and established an expression ranking for GPCRs detected in the OE. We also identified other previously undescribed membrane proteins as potential new players in olfaction. The quantitative and comprehensive transcriptome data provide a virtually complete catalogue of genes expressed in the OE and present a useful tool to uncover candidate genes involved in, for example, olfactory signaling, OR trafficking and recycling, and proliferation.
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Affiliation(s)
| | - Marilen Demond
- Ruhr-University Bochum, Department of Cell Physiology, Bochum, Germany
- University Duisburg-Essen, Institute of Medical Radiation Biology, Essen, Germany
| | - Maximilian Nagel
- Ruhr-University Bochum, Department of Cell Physiology, Bochum, Germany
| | | | - Sabrina Baumgart
- Ruhr-University Bochum, Department of Cell Physiology, Bochum, Germany
| | - Paul Scholz
- Ruhr-University Bochum, Department of Cell Physiology, Bochum, Germany
| | | | | | - Julia F. Doerner
- Ruhr-University Bochum, Department of Cell Physiology, Bochum, Germany
| | - Heike Conrad
- Ruhr-University Bochum, Department of Cell Physiology, Bochum, Germany
- Cluster of Excellence and DFG Research Center Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Sonja Oberland
- Pharmacology and Toxicology, University Hospital Jena, Drackendorfer Str. 1, 07747 Jena, Germany
- Cluster of Excellence NeuroCure, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Christian H. Wetzel
- University of Regensburg, Department of Psychiatry and Psychotherapy, Molecular Neurosciences, Regensburg, Germany
| | - Eva M. Neuhaus
- Pharmacology and Toxicology, University Hospital Jena, Drackendorfer Str. 1, 07747 Jena, Germany
- Cluster of Excellence NeuroCure, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany
| | - Hanns Hatt
- Ruhr-University Bochum, Department of Cell Physiology, Bochum, Germany
| | - Günter Gisselmann
- Ruhr-University Bochum, Department of Cell Physiology, Bochum, Germany
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18
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Ligand-selective activation of heterologously-expressed mammalian olfactory receptor. Cell Calcium 2014; 56:245-56. [PMID: 25149566 DOI: 10.1016/j.ceca.2014.07.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 07/24/2014] [Accepted: 07/27/2014] [Indexed: 11/23/2022]
Abstract
Mammalian olfactory receptors (ORs) appear to have the capacity to couple to multiple G protein-coupled signaling pathways in a ligand-dependent selective manner. To better understand the mechanisms and molecular range of such ligand selectivity, we expressed the mouse eugenol OR (mOR-EG) in HEK293T cells together with Gα15 to monitor activation of the phospholipase-C (PLC) signaling pathway and/or Gαolf to monitor activation of the adenylate cyclase (AC) signaling pathway, resulting in intracellular Ca(2+) release and/or Ca(2+) influx through a cyclic nucleotide-gated channel, respectively. PLC-dependent responses differed dynamically from AC-dependent responses, allowing them to be distinguished when Gα15 and Gαolf were co-expressed. The dynamic difference in readout was independent of the receptor, the heterologous expression system, and the ligand concentration. Of 17 reported mOR-EG ligands tested, including eugenol, its analogs, and structurally dissimilar compounds (mousse cristal, nootkatone, orivone), some equally activated both signaling pathways, some differentially activated both signaling pathways, and some had no noticeable effect even at 1-5mM. Our findings argue that mOR-EG, when heterologously expressed, can couple to two different signaling pathways in a ligand selective manner. The challenge now is to determine the potential of mOR-EG, and perhaps other ORs, to activate multiple signaling pathways in a ligand selective manner in native ORNs.
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19
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Jin P, Ren Z, Ye F, Ying W. A novel label-free live-cell biosensor for G-protein-coupled receptor functional assay with enhanced sensitivity. Anal Biochem 2014; 450:27-9. [DOI: 10.1016/j.ab.2013.12.036] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Revised: 12/29/2013] [Accepted: 12/30/2013] [Indexed: 12/12/2022]
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20
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Dai G, Peng C, Liu C, Varnum MD. Two structural components in CNGA3 support regulation of cone CNG channels by phosphoinositides. ACTA ACUST UNITED AC 2013; 141:413-30. [PMID: 23530136 PMCID: PMC3607822 DOI: 10.1085/jgp.201210944] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cyclic nucleotide-gated (CNG) channels in retinal photoreceptors play a crucial role in vertebrate phototransduction. The ligand sensitivity of photoreceptor CNG channels is adjusted during adaptation and in response to paracrine signals, but the mechanisms involved in channel regulation are only partly understood. Heteromeric cone CNGA3 (A3) + CNGB3 (B3) channels are inhibited by membrane phosphoinositides (PIP(n)), including phosphatidylinositol 3,4,5-triphosphate (PIP(3)) and phosphatidylinositol 4,5-bisphosphate (PIP(2)), demonstrating a decrease in apparent affinity for cyclic guanosine monophosphate (cGMP). Unlike homomeric A1 or A2 channels, A3-only channels paradoxically did not show a decrease in apparent affinity for cGMP after PIP(n) application. However, PIP(n) induced an ∼2.5-fold increase in cAMP efficacy for A3 channels. The PIP(n)-dependent change in cAMP efficacy was abolished by mutations in the C-terminal region (R643Q/R646Q) or by truncation distal to the cyclic nucleotide-binding domain (613X). In addition, A3-613X unmasked a threefold decrease in apparent cGMP affinity with PIP(n) application to homomeric channels, and this effect was dependent on conserved arginines within the N-terminal region of A3. Together, these results indicate that regulation of A3 subunits by phosphoinositides exhibits two separable components, which depend on structural elements within the N- and C-terminal regions, respectively. Furthermore, both N and C regulatory modules in A3 supported PIP(n) regulation of heteromeric A3+B3 channels. B3 subunits were not sufficient to confer PIP(n) sensitivity to heteromeric channels formed with PIP(n)-insensitive A subunits. Finally, channels formed by mixtures of PIP(n)-insensitive A3 subunits, having complementary mutations in N- and/or C-terminal regions, restored PIP(n) regulation, implying that intersubunit N-C interactions help control the phosphoinositide sensitivity of cone CNG channels.
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Affiliation(s)
- Gucan Dai
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA 99164, USA
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21
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Daiber P, Genovese F, Schriever VA, Hummel T, Möhrlen F, Frings S. Neuropeptide receptors provide a signalling pathway for trigeminal modulation of olfactory transduction. Eur J Neurosci 2012. [PMID: 23205840 DOI: 10.1111/ejn.12066] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The mammalian olfactory epithelium contains olfactory receptor neurons and trigeminal sensory endings. The former mediate odor detection, the latter the detection of irritants. The two apparently parallel chemosensory systems are in reality interdependent in various well-documented ways. Psychophysical studies have shown that virtually all odorants can act as irritants, and that most irritants have an odor. Thus, the sensory perception of odorants and irritants is based on simultaneous input from the two systems. Moreover, functional interactions between the olfactory system and the trigeminal system exist on both peripheral and central levels. Here we examine the impact of trigeminal stimulation on the odor response of olfactory receptor neurons. Using an odorant with low trigeminal potency (phenylethyl alcohol) and a non-odorous irritant (CO(2) ), we have explored this interaction in psychophysical experiments with human subjects and in electroolfactogram (EOG) recordings from rats. We have demonstrated that simultaneous activation of the trigeminal system attenuates the perception of odor intensity and distorts the EOG response. On the molecular level, we have identified a route for this cross-modal interaction. The neuropeptide calcitonin-gene related peptide (CGRP), which is released from trigeminal sensory fibres upon irritant stimulation, inhibits the odor response of olfactory receptor neurons. CGRP receptors expressed by these neurons mediate this neuromodulatory effect. This study demonstrates a site of trigeminal-olfactory interaction in the periphery. It reveals a pathway for trigeminal impact on olfactory signal processing that influences odor perception.
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Affiliation(s)
- Philipp Daiber
- Department of Molecular Physiology, Centre for Organismal Studies, Heidelberg University, Heidelberg, Germany
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22
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Lucero MT. Peripheral modulation of smell: fact or fiction? Semin Cell Dev Biol 2012; 24:58-70. [PMID: 22986099 DOI: 10.1016/j.semcdb.2012.09.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Accepted: 09/06/2012] [Indexed: 01/01/2023]
Abstract
Despite studies dating back 30 or more years showing modulation of odorant responses at the level of the olfactory epithelium, most descriptions of the olfactory system infer that odorant signals make their way from detection by cilia on olfactory sensory neurons to the olfactory bulb unaltered. Recent identification of multiple subtypes of microvillar cells and identification of neuropeptide and neurotransmitter expression in the olfactory mucosa add to the growing body of literature for peripheral modulation in the sense of smell. Complex mechanisms including perireceptor events, modulation of sniff rates, and changes in the properties of sensory neurons match the sensitivity of olfactory sensory neurons to the external odorant environment, internal nutritional status, reproductive status, and levels of arousal or stress. By furthering our understanding of the players mediating peripheral olfaction, we may open the door to novel approaches for modulating the sense of smell in both health and disease.
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Affiliation(s)
- Mary T Lucero
- Department of Physiology, School of Medicine, University of Utah, 420 Chipeta Way Ste, 1700 Salt Lake City, UT 84108, USA.
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23
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Klasen K, Hollatz D, Zielke S, Gisselmann G, Hatt H, Wetzel CH. The TRPM8 ion channel comprises direct Gq protein-activating capacity. Pflugers Arch 2012; 463:779-97. [PMID: 22460725 DOI: 10.1007/s00424-012-1098-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Revised: 03/12/2012] [Accepted: 03/14/2012] [Indexed: 11/29/2022]
Abstract
The transient receptor potential (TRP) family of ion channels comprises receptors that are activated by a vast variety of physical as well as chemical stimuli. TRP channels interact in a complex manner with several intracellular signaling cascades, both up- and downstream of receptor activation. Investigating cascades stimulated downstream of the cold and menthol receptor TRPM8, we found evidence for both, functional and structural interaction of TRPM8 with Gαq. We demonstrated menthol-evoked increase in intracellular Ca(2+) under extracellular Ca(2+)-free conditions, which was blocked by the PLC inhibitors U73122 or edelfosine. This metabotropic Ca(2+) signal could be observed also in cells expressing a channel-dead (i.e. non-conducting) or a chloride-conducting TRPM8 pore mutant. However, this intracellular metabotropic Ca(2+) signal could not be detected in Gαq deficient cells or in the presence of dominant-negative GαqX. Evidence for a close spatial proximity necessary for physical interaction of TRPM8 and Gαq was provided by acceptor bleaching experiments demonstrating FRET between TRPM8-CFP and Gαq-YFP. A Gαq-YFP mobility assay (FRAP) revealed a restricted diffusion of Gαq-YFP under conditions when TRPM8 is immobilized in the plasma membrane. Moreover, a menthol-induced and TRPM8-mediated G protein activation could be demonstrated by FRET experiments monitoring the dissociation of Gαq-YFP from a Gβ/Gγ-CFP complex, and by the exchange of radioactive [(35)S]GTPγS for GDP. Our observations lead to a view that extends the operational range of the TRPM8 receptor from its function as a pure ion channel to a molecular switch with additional metabotropic capacity.
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Affiliation(s)
- Katharina Klasen
- Lehrstuhl für Zellphysiologie, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
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Mitochondrial Ca(2+) mobilization is a key element in olfactory signaling. Nat Neurosci 2012; 15:754-62. [PMID: 22446879 DOI: 10.1038/nn.3074] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2011] [Accepted: 02/21/2012] [Indexed: 12/13/2022]
Abstract
In olfactory sensory neurons (OSNs), cytosolic Ca(2+) controls the gain and sensitivity of olfactory signaling. Important components of the molecular machinery that orchestrates OSN Ca(2+) dynamics have been described, but key details are still missing. Here, we demonstrate a critical physiological role of mitochondrial Ca(2+) mobilization in mouse OSNs. Combining a new mitochondrial Ca(2+) imaging approach with patch-clamp recordings, organelle mobility assays and ultrastructural analyses, our study identifies mitochondria as key determinants of olfactory signaling. We show that mitochondrial Ca(2+) mobilization during sensory stimulation shapes the cytosolic Ca(2+) response profile in OSNs, ensures a broad dynamic response range and maintains sensitivity of the spike generation machinery. When mitochondrial function is impaired, olfactory neurons function as simple stimulus detectors rather than as intensity encoders. Moreover, we describe activity-dependent recruitment of mitochondria to olfactory knobs, a mechanism that provides a context-dependent tool for OSNs to maintain cellular homeostasis and signaling integrity.
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Chaput MA, El Mountassir F, Atanasova B, Thomas-Danguin T, Le Bon AM, Perrut A, Ferry B, Duchamp-Viret P. Interactions of odorants with olfactory receptors and receptor neurons match the perceptual dynamics observed for woody and fruity odorant mixtures. Eur J Neurosci 2012; 35:584-97. [PMID: 22304504 DOI: 10.1111/j.1460-9568.2011.07976.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The present study aimed to create a direct bridge between observations on peripheral and central responses to odorant mixtures and their components. Three experiments were performed using mixtures of fruity (isoamyl acetate; ISO) and woody (whiskey lactone; WL) odorants known to contribute to some of the major notes in Burgundy red wine. These experiments consisted of (i) calcium imaging of human embryonic kidney cells (HEK293T) transfected with olfactory receptors (ORs); (ii) single-unit electrophysiological recordings from olfactory receptor neurons (ORNs) and analyses of electro-olfactogram (EOG) responses in the rat nose in vivo; and (iii) psychophysical measurements of the perceived intensity of the mixtures as rated by human subjects. The calcium imaging and electrophysiological results revealed that ISO and WL can act simultaneously on single ORs or ORNs and confirm that receptor responses to mixtures are not the result of a simple sum of the effects of the individual mixture compounds. The addition of WL to ISO principally suppressed the ORN activation induced by ISO alone and was found to enhance this activation in a subset of cases. In the human studies, the addition of high concentrations of WL to ISO decreased the perceived intensity of the ISO. In contrast, the addition of low concentrations of WL enhanced the perceived intensity of the fruity note (ISO) in this mixture, as it enhanced EOG responses in ORNs. Thus, both OR and ORN responses to ISO + WL mixtures faithfully reflected perceptual response changes, so the odour mixture information is set up after the peripheral stage of the olfactory system.
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Affiliation(s)
- M A Chaput
- UMR 5292, Centre de recherche en neurosciences de Lyon, Université de Lyon, CNRS, INSERM, 50 avenue Tony Garnier, F-69366 Lyon, France.
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Rosenhouse‐Dantsker A, Mehta D, Levitan I. Regulation of Ion Channels by Membrane Lipids. Compr Physiol 2012; 2:31-68. [DOI: 10.1002/cphy.c110001] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Benbernou N, Robin S, Tacher S, Rimbault M, Rakotomanga M, Galibert F. cAMP and IP3 signaling pathways in HEK293 cells transfected with canine olfactory receptor genes. ACTA ACUST UNITED AC 2011; 102 Suppl 1:S47-61. [PMID: 21846747 DOI: 10.1093/jhered/esr033] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Olfactory receptors (ORs) expressed at the cell surface of olfactory sensory neurons lining the olfactory epithelium are the first actors of events leading to odor perception and recognition. As for other mammalian ORs, few dog OR have been deorphanized, mainly because of the absence of good methodology and the difficulties encountered to express ORs at the cell surface. Within this work, our aim was 1) to deorphanize a large subset of dog OR and 2) to compare the implication of the 2 main pathways, namely the cAMP and inositol 1,4,5-triphosphate (IP3) pathways, in the transduction of the olfactory message. For this, we used 2 independent tests to assess the importance of each of these 2 pathways and analyzed the responses of 47 canine family 6 ORs to a number of aliphatic compounds. We found these ORs globally capable of inducing intracellular calcium elevation through the IP3 pathway as confirmed by the use of specific inhibitors and/or a cAMP increase in response to aldehyde exposure. We showed that the implication of the cAMP or/and IP3 pathway was dependent upon the ligand-receptor combination rather than on one or the other partner. Finally, by exposing OR-expressing cells to the 21 possible pairs of C6-C12 aliphatic aldehydes, we confirmed that some odorant pairs may have an inhibitory or additive effect. Altogether, these results reinforce the notion that odorant receptor subfamilies may constitute functional units and call for a more systematic use of 2 complementary tests interrogating the cAMP and IP3 pathways when deorphanizing ORs.
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Affiliation(s)
- Naïma Benbernou
- Institute of Genetic and Development of Rennes, CNRS Unité de Recherche Mixte 6061, Faculté de Médecine, Rennes, F-35043 France
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Wasserman SM, Beverly M, Bell HW, Sengupta P. Regulation of response properties and operating range of the AFD thermosensory neurons by cGMP signaling. Curr Biol 2011; 21:353-62. [PMID: 21315599 DOI: 10.1016/j.cub.2011.01.053] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 01/20/2011] [Accepted: 01/21/2011] [Indexed: 11/26/2022]
Abstract
BACKGROUND The neuronal mechanisms that encode specific stimulus features in order to elicit defined behavioral responses are poorly understood. C. elegans forms a memory of its cultivation temperature (T(c)) and exhibits distinct behaviors in different temperature ranges relative to T(c). In particular, C. elegans tracks isotherms only in a narrow temperature band near T(c). T(c) memory is in part encoded by the threshold of responsiveness (T∗(AFD)) of the AFD thermosensory neuron pair to temperature stimuli. However, because AFD thermosensory responses appear to be similar at all examined temperatures above T∗(AFD), the mechanisms that generate specific behaviors in defined temperature ranges remain to be determined. RESULTS Here, we show that the AFD neurons respond to the sinusoidal variations in thermal stimuli followed by animals during isothermal tracking (IT) behavior only in a narrow temperature range near T(c). We find that mutations in the AFD-expressed gcy-8 receptor guanylyl cyclase (rGC) gene result in defects in the execution of IT behavior and are associated with defects in the responses of the AFD neurons to oscillating thermal stimuli. In contrast, mutations in the gcy-18 or gcy-23 rGCs alter the temperature range in which IT behavior is exhibited. Alteration of intracellular cGMP levels via rGC mutations or addition of cGMP analogs shift the lower and upper ranges of the temperature range of IT behavior in part via alteration in T∗(AFD). CONCLUSIONS Our observations provide insights into the mechanisms by which a single sensory neuron type encodes features of a given stimulus to generate different behaviors in defined zones.
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Affiliation(s)
- Sara M Wasserman
- Department of Biology, Brandeis University, Waltham, MA 02454, USA
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Abstract
Phosphoinositide signaling, in particular, phosphoinositide 3-kinase (PI3K) signaling, has been implicated in mediating inhibitory odorant input to mammalian olfactory receptor neurons (ORNs). To better understand this phenomenon we investigated PI3K-dependent inhibition between single odorant pairs. The concentration-dependent inhibition of the response of native rat ORNs to octanol by citral is PI3K dependent; blocking PI3K activity with the β and γ isoform-specific inhibitors AS252424 (5-[5-(4-fluoro-2-hydroxy-phenyl)-furan-2-ylmethylene]-thiazolidine-2,4-dione) and TGX221(7-methyl-2-(4-morpholinyl)-9-[1-(phenylamino)ethyl]-4H-pyrido [1,2-a]pyrimidin-4-one) eliminated or strongly reduced the inhibition. Interestingly, blocking PI3K also changed the apparent agonist strength of the otherwise noncompetitive antagonist citral. The excitation evoked by citral after blocking PI3K, could be suppressed by the adenylate cyclase III (ACIII) blockers MDL12330A (cis-N-(2-phenylcyclopentyl)-azacyclotridec-1-en-2-amine hydrochloride) and SQ22536 [9-(tetrahydro-2-furanyl)-9H-purin-6-amine], indicating that citral could also activate ACIII, presumably through the canonical olfactory receptor (OR). The G-protein G(β)γ subunit blockers suramin (8,8'-[carbonylbis[imino-3,1-phenylen ecarbonylimino(4-methyl-3,1-phenylene)carbonylimino]]bis-1,3,5-naphthalenetrisulfonic acid), gallein (3',4',5',6'-tetrahydroxyspiro[isobenzofuran-1(3H),9'-(9H)xanthen]-3-one), and M119 (cyclohexanecarboxylic acid [2-(4,5,6-trihydroxy-3-oxo-3H-xanthen-9-yl)-(9CI)]) suppressed citral's inhibition of the response to octanol, indicating that the activation of PI3K by citral was G-protein dependent, consistent with the idea that inhibition acts via the canonical OR. Lilial similarly antagonized the response to isoamyl acetate in other ORNs, indicating the effect generalizes to at least one other odorant pair. The ability of methyl-isoeugenol, limonene, α-pinene, isovaleric acid, and isosafrole to inhibit the response of other ORNs to IBMX (3-isobutyl-1-methylxanthine)/forskolin in a PI3K-dependent manner argues the effect generalizes to yet other structurally dissimilar odorants. Our findings collectively raise the interesting possibility that the OR serves as a molecular logic gate when mammalian ORNs are activated by natural, complex mixtures containing both excitatory and inhibitory odorants.
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Insulin signaling plays a dual role in Caenorhabditis elegans memory acquisition and memory retrieval. J Neurosci 2010; 30:8001-11. [PMID: 20534848 DOI: 10.1523/jneurosci.4636-09.2010] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Insulin signaling plays a prominent role in regulation of dauer formation and longevity in Caenorhabditis elegans. Here, we show that insulin signaling also is required in benzaldehyde-starvation associative plasticity, in which worms pre-exposed to the odor attractant benzaldehyde in the absence of food subsequently demonstrate a conditioned aversion response toward the odorant. Animals with mutations in insulin-related 1 (ins-1), abnormal dauer formation 2 (daf-2), and aging alteration 1 (age-1), which encode the homolog of human insulin, insulin/IGF-1 receptor, and PIP3 kinase, respectively, demonstrated significant deficits in benzaldehyde-starvation associative plasticity. Using a conditional allele, we show that the behavioral roles of DAF-2 signaling in associative plasticity can be dissociated, with DAF-2 signaling playing a more significant role in the memory retrieval than in memory acquisition. We propose DAF-2 signaling acts as a learning-specific starvation signal in the memory acquisition phase of benzaldehyde-starvation associative plasticity but functions to switch benzaldehyde-sensing amphid wing C neurons into an avoidance signaling mode during memory retrieval.
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Affiliation(s)
- Barry W Ache
- Center for Smell and Taste, University of Florida, Gainesville, 32610, USA.
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Brunert D, Klasen K, Corey EA, Ache BW. PI3Kgamma-dependent signaling in mouse olfactory receptor neurons. Chem Senses 2010; 35:301-8. [PMID: 20190008 DOI: 10.1093/chemse/bjq020] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Phosphatidylinositol 3-kinase (PI3K)-dependent signaling couples to receptors for many different ligands in diverse cellular systems. Recent findings suggest that PI3K-dependent signaling also mediates inhibition of odorant responses in rat olfactory receptor neurons (ORNs). Here, we present evidence that murine ORNs show PI3K-dependent calcium responses to odorant stimulation, they express 2 G protein-coupled receptor (GPCR)-activated isoforms of PI3K, PI3Kbeta and PI3Kgamma, and they exhibit odorant-induced PI3K activity. These findings support our use of a transgenic mouse model to begin to investigate the mechanisms underlying PI3K-mediated inhibition of odorant responses in mammalian ORNs. Mice deficient in PI3Kgamma, a class IB PI3K that is activated via GPCRs, lack detectable odorant-induced PI3K activity in their olfactory epithelium and their ORNs are less sensitive to PI3K inhibition. We conclude that odorant-dependent PI3K signaling generalizes to the murine olfactory system and that PI3Kgamma plays a role in mediating inhibition of odorant responses in mammalian ORNs.
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Affiliation(s)
- Daniela Brunert
- Center for Smell and Taste, University of Florida, Gainesville, FL 32610-0127 USA.
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Corey EA, Bobkov Y, Pezier A, Ache BW. Phosphoinositide 3-kinase mediated signaling in lobster olfactory receptor neurons. J Neurochem 2010; 113:341-50. [PMID: 20132480 DOI: 10.1111/j.1471-4159.2010.06597.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In vertebrates and some invertebrates, odorant molecules bind to G protein-coupled receptors on olfactory receptor neurons (ORNs) to initiate signal transduction. Phosphoinositide 3-kinase (PI3K) activity has been implicated physiologically in olfactory signal transduction, suggesting a potential role for a G protein-coupled receptor-activated class I PI3K. Using isoform-specific antibodies, we identified a protein in the olfactory signal transduction compartment of lobster ORNs that is antigenically similar to mammalian PI3Kgamma and cloned a gene for a PI3K with amino acid homology with PI3Kbeta. The lobster olfactory PI3K co-immunoprecipitates with the G protein alpha and beta subunits, and an odorant-evoked increase in phosphatidylinositol (3,4,5)-trisphosphate can be detected in the signal transduction compartment of the ORNs. PI3Kgamma and beta isoform-specific inhibitors reduce the odorant-evoked output of lobster ORNs in vivo. Collectively, these findings provide evidence that PI3K is indeed activated by odorant receptors in lobster ORNs and further support the potential involvement of G protein activated PI3K signaling in olfactory transduction.
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Affiliation(s)
- Elizabeth A Corey
- Whitney Laboratory, Center for Smell and Taste, McKnight Brain Institute, University of Florida, Gainesville, Florida 32080-8610, USA.
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Dooley R, Baumgart S, Rasche S, Hatt H, Neuhaus EM. Olfactory receptor signaling is regulated by the post-synaptic density 95, Drosophila discs large, zona-occludens 1 (PDZ) scaffold multi-PDZ domain protein 1. FEBS J 2010; 276:7279-90. [PMID: 19909339 DOI: 10.1111/j.1742-4658.2009.07435.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The unique ability of mammals to detect and discriminate between thousands of different odorant molecules is governed by the diverse array of olfactory receptors expressed by olfactory sensory neurons in the nasal epithelium. Olfactory receptors consist of seven transmembrane domain G protein-coupled receptors and comprise the largest gene superfamily in the mammalian genome. We found that approximately 30% of olfactory receptors possess a classical post-synaptic density 95, Drosophila discs large, zona-occludens 1 (PDZ) domain binding motif in their C-termini. PDZ domains have been established as sites for protein-protein interaction and play a central role in organizing diverse cell signaling assemblies. In the present study, we show that multi-PDZ domain protein 1 (MUPP1) is expressed in the apical compartment of olfactory sensory neurons. Furthermore, on heterologous co-expression with olfactory sensory neurons, MUPP1 was shown to translocate to the plasma membrane. We found direct interaction of PDZ domains 1 + 2 of MUPP1 with the C-terminus of olfactory receptors in vitro. Moreover, the odorant-elicited calcium response of OR2AG1 showed a prolonged decay in MUPP1 small interfering RNA-treated cells. We have therefore elucidated the first building blocks of the putative 'olfactosome', brought together by the scaffolding protein MUPP1, a possible central nucleator of the olfactory response.
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Affiliation(s)
- Ruth Dooley
- Molecular Medicine Lab RCSI, Beaumont Hospital, Dublin, Republic of Ireland
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35
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Ukhanov K, Corey EA, Brunert D, Klasen K, Ache BW. Inhibitory odorant signaling in Mammalian olfactory receptor neurons. J Neurophysiol 2009; 103:1114-22. [PMID: 20032232 DOI: 10.1152/jn.00980.2009] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Odorants inhibit as well as excite olfactory receptor neurons (ORNs) in many species of animals. Cyclic nucleotide-dependent activation of canonical mammalian ORNs is well established but it is still unclear how odorants inhibit these cells. Here we further implicate phosphoinositide-3-kinase (PI3K), an indispensable element of PI signaling in many cellular processes, in olfactory transduction in rodent ORNs. We show that odorants rapidly and transiently activate PI3K in the olfactory cilia and in the olfactory epithelium in vitro. We implicate known G-protein-coupled isoforms of PI3K and show that they modulate not only the magnitude but also the onset kinetics of the electrophysiological response of ORNs to complex odorants. Finally, we show that the ability of a single odorant to inhibit another can be PI3K dependent. Our collective results provide compelling support for the idea that PI3K-dependent signaling mediates inhibitory odorant input to mammalian ORNs and at least in part contributes to the mixture suppression typically seen in the response of ORNs to complex natural odorants.
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Affiliation(s)
- Kirill Ukhanov
- Whitney Laboratory, Center for Smell and Taste, University of Florida, Gainesville, FL 32610-0127, USA.
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36
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Klasen K, Corey EA, Kuck F, Wetzel CH, Hatt H, Ache BW. Odorant-stimulated phosphoinositide signaling in mammalian olfactory receptor neurons. Cell Signal 2009; 22:150-7. [PMID: 19781634 DOI: 10.1016/j.cellsig.2009.09.026] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Accepted: 09/14/2009] [Indexed: 01/28/2023]
Abstract
Recent evidence has revived interest in the idea that phosphoinositides (PIs) may play a role in signal transduction in mammalian olfactory receptor neurons (ORNs). To provide direct evidence that odorants indeed activate PI signaling in ORNs, we used adenoviral vectors carrying two different fluorescently tagged probes, the pleckstrin homology (PH) domains of phospholipase C delta 1 (PLC delta 1) and the general receptor of phosphoinositides (GRP1), to monitor PI activity in the dendritic knobs of ORNs in vivo. Odorants mobilized PI(4,5)P(2)/IP(3) and PI(3,4,5)P(3), the substrates and products of PLC and PI3K. We then measured odorant activation of PLC and PI3K in olfactory ciliary-enriched membranes in vitro using a phospholipid overlay assay and ELISAs. Odorants activated both PLC and PI3K in the olfactory cilia within 2s of odorant stimulation. Odorant-dependent activation of PLC and PI3K in the olfactory epithelium could be blocked by enzyme-specific inhibitors. Odorants activated PLC and PI3K with partially overlapping specificity. These results provide direct evidence that odorants indeed activate PI signaling in mammalian ORNs in a manner that is consistent with the idea that PI signaling plays a role in olfactory transduction.
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Affiliation(s)
- K Klasen
- Whitney Laboratory, Center for Smell and Taste, and McKnight Brain Institute, University of Florida, Gainesville, FL, USA.
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37
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Wu CS, Chen PH, Yuan Q, Wang P. Response enhancement of olfactory sensory neurons-based biosensors for odorant detection. J Zhejiang Univ Sci B 2009; 10:285-90. [PMID: 19353747 DOI: 10.1631/jzus.b0820220] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This paper presents a novel strategy for the response enhancement of olfactory sensory neurons (OSNs)-based biosensors by monitoring the enhancive responses of OSNs to odorants. An OSNs-based biosensor was developed on the basis of the light addressable potentiometric sensor (LAPS), in which rat OSNs were cultured on the surface of LAPS chip and served as sensing elements. LY294002, the specific inhibitor of phosphatidylinositol 3-kinase (PI3K), was used to enhance the responses of OSNs to odorants. The responses of OSNs to odorants with and without the treatment of LY294002 were recorded by LAPS. The results show that the enhancive effect of LY294002 was recorded efficiently by LAPS and the responses of this OSNs-LAPS hybrid biosensor were enhanced by LY294002 by about 1.5-fold. We conclude that this method can enhance the responses of OSNs-LAPS hybrid biosensors, which may provide a novel strategy for the bioelectrical signal monitor of OSNs in biosensors. It is also suggested that this strategy may be applicable to other kinds of OSNs-based biosensors for cellular activity detection, such as microelectrode array (MEA) and field effect transistor (FET).
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Affiliation(s)
- Chun-sheng Wu
- Biosensor National Special Laboratory, MOE Key Laboratory of Biomedical Engineering, Department of Biomedical Engineering, Zhejiang University, Hangzhou 310027, China
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38
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Brunert D, Kurtenbach S, Isik S, Benecke H, Gisselmann G, Schuhmann W, Hatt H, Wetzel CH. Odorant-dependent generation of nitric oxide in Mammalian olfactory sensory neurons. PLoS One 2009; 4:e5499. [PMID: 19430528 PMCID: PMC2675079 DOI: 10.1371/journal.pone.0005499] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2008] [Accepted: 04/15/2009] [Indexed: 11/26/2022] Open
Abstract
The gaseous signalling molecule nitric oxide (NO) is involved in various physiological processes including regulation of blood pressure, immunocytotoxicity and neurotransmission. In the mammalian olfactory bulb (OB), NO plays a role in the formation of olfactory memory evoked by pheromones as well as conventional odorants. While NO generated by the neuronal isoform of NO synthase (nNOS) regulates neurogenesis in the olfactory epithelium, NO has not been implicated in olfactory signal transduction. We now show the expression and function of the endothelial isoform of NO synthase (eNOS) in mature olfactory sensory neurons (OSNs) of adult mice. Using NO-sensitive micro electrodes, we show that stimulation liberates NO from isolated wild-type OSNs, but not from OSNs of eNOS deficient mice. Integrated electrophysiological recordings (electro-olfactograms or EOGs) from the olfactory epithelium of these mice show that NO plays a significant role in modulating adaptation. Evidence for the presence of eNOS in mature mammalian OSNs and its involvement in odorant adaptation implicates NO as an important new element involved in olfactory signal transduction. As a diffusible messenger, NO could also have additional functions related to cross adaptation, regeneration, and maintenance of MOE homeostasis.
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Affiliation(s)
- Daniela Brunert
- Lehrstuhl für Zellphysiologie, Ruhr-Universität Bochum, Bochum, Germany
- International Graduate School of Neuroscience, Ruhr-Universität Bochum, Bochum, Germany
| | - Stefan Kurtenbach
- Lehrstuhl für Zellphysiologie, Ruhr-Universität Bochum, Bochum, Germany
| | - Sonnur Isik
- Lehrstuhl für Analytische Chemie, AG Elektroanalytik und Sensorik, Ruhr-Universität Bochum, Bochum, Germany
| | - Heike Benecke
- Lehrstuhl für Zellphysiologie, Ruhr-Universität Bochum, Bochum, Germany
| | - Günter Gisselmann
- Lehrstuhl für Zellphysiologie, Ruhr-Universität Bochum, Bochum, Germany
| | - Wolfgang Schuhmann
- Lehrstuhl für Analytische Chemie, AG Elektroanalytik und Sensorik, Ruhr-Universität Bochum, Bochum, Germany
- International Graduate School of Neuroscience, Ruhr-Universität Bochum, Bochum, Germany
| | - Hanns Hatt
- Lehrstuhl für Zellphysiologie, Ruhr-Universität Bochum, Bochum, Germany
- International Graduate School of Neuroscience, Ruhr-Universität Bochum, Bochum, Germany
| | - Christian H. Wetzel
- Lehrstuhl für Zellphysiologie, Ruhr-Universität Bochum, Bochum, Germany
- International Graduate School of Neuroscience, Ruhr-Universität Bochum, Bochum, Germany
- * E-mail:
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Abstract
Cyclic nucleotide-gated (CNG) channels are ion channels which are activated by the binding of cGMP or cAMP. The channels are important cellular switches which transduce changes in intracellular concentrations of cyclic nucleotides into changes of the membrane potential and the Ca2+ concentration. CNG channels play a central role in the signal transduction pathways of vision and olfaction. Structurally, the channels belong to the superfamily of pore-loop cation channels. They share a common domain structure with hyperpolarization-activated cyclic nucleotide-gated (HCN) channels and Eag-like K+ channels. In this chapter, we give an overview on the molecular properties of CNG channels and describe the signal transduction pathways these channels are involved in. We will also summarize recent insights into the physiological and pathophysiological role of CNG channel proteins that have emerged from the analysis of CNG channel-deficient mouse models and human channelopathies.
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Affiliation(s)
- Martin Biel
- Center for Integrated Protein Science CIPS-M and Zentrum für Pharmaforschung-Department Pharmazie, Pharmakologie für Naturwissenschaften, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, München, 81377, Germany.
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Wu C, Chen P, Yu H, Liu Q, Zong X, Cai H, Wang P. A novel biomimetic olfactory-based biosensor for single olfactory sensory neuron monitoring. Biosens Bioelectron 2008; 24:1498-502. [PMID: 18799305 DOI: 10.1016/j.bios.2008.07.065] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2008] [Revised: 07/06/2008] [Accepted: 07/28/2008] [Indexed: 11/27/2022]
Abstract
This paper presents a novel biomimetic olfactory biosensor for the study of olfactory transduction mechanisms on the basis of light addressable potentiometric sensor (LAPS), in which rat olfactory sensory neurons (OSNs) are used as sensing elements. Rat OSNs are cultured on the surface of LAPS chip. To validate the origin of the electrical signals recorded by LAPS, the inhibitory effect of MDL12330A to the olfactory signals of OSNs is tested, which is the specific inhibitor of adenylyl cyclase. The enhancive effect of LY294002 to the responses of OSNs is also investigated, which is the specific inhibitor of phosphatidylinositol 3-kinase (PI3K). The results show that this hybrid biosensor can record the responses of OSNs to odours efficiently in a non-invasive way for a long term, and the responses can be inhibited by MDL12330A and enhanced by LY294002. All these results demonstrate that this hybrid biosensor can be used to monitor electrophysiology of OSNs in a non-invasive way and suggest it could be a promising tool for the study of olfactory transduction mechanisms.
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Affiliation(s)
- Chunsheng Wu
- Biosensor National Special Laboratory, Key Laboratory of Biomedical Engineering of Education Ministry, Department of Biomedical Engineering, Zhejiang University, Zheda Road No. 38, Hangzhou 310027, PR China
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Triller A, Boulden E, Churchill A, Hatt H, Englund J, Spehr M, Sell C. Odorant–Receptor Interactions and Odor Percept: A Chemical Perspective. Chem Biodivers 2008; 5:862-86. [DOI: 10.1002/cbdv.200890101] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Kerr DS, Von Dannecker LEC, Davalos M, Michaloski JS, Malnic B. Ric-8B interacts with G alpha olf and G gamma 13 and co-localizes with G alpha olf, G beta 1 and G gamma 13 in the cilia of olfactory sensory neurons. Mol Cell Neurosci 2008; 38:341-8. [PMID: 18462949 DOI: 10.1016/j.mcn.2008.03.006] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2008] [Revised: 03/12/2008] [Accepted: 03/17/2008] [Indexed: 01/06/2023] Open
Abstract
Olfactory sensory neurons are able to detect odorants with high sensitivity and specificity. We have demonstrated that Ric-8B, a guanine nucleotide exchange factor (GEF), interacts with Galphaolf and enhances odorant receptor signaling. Here we show that Ric-8B also interacts with Ggamma13, a divergent member of the Ggamma subunit family which has been implicated in taste signal transduction, and is abundantly expressed in the cilia of olfactory sensory neurons. We show that Gbeta1 is the predominant Gbeta subunit expressed in the olfactory sensory neurons. Ric-8B and Gbeta1, like Galphaolf and Ggamma13, are enriched in the cilia of olfactory sensory neurons. We also show that Ric-8B interacts with Galphaolf in a nucleotide dependent manner, consistent with the role as a GEF. Our results constitute the first example of a GEF protein that interacts with two different olfactory G protein subunits and further implicate Ric-8B as a regulator of odorant signal transduction.
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Affiliation(s)
- Daniel S Kerr
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes, 748, CEP 05508-000, São Paulo, Brazil
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43
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Abstract
Most animals have evolved multiple olfactory systems to detect general odors as well as social cues. The sophistication and interaction of these systems permit precise detection of food, danger, and mates, all crucial elements for survival. In most mammals, the nose contains two well described chemosensory apparatuses (the main olfactory epithelium and the vomeronasal organ), each of which comprises several subtypes of sensory neurons expressing distinct receptors and signal transduction machineries. In many species (e.g., rodents), the nasal cavity also includes two spatially segregated clusters of neurons forming the septal organ of Masera and the Grueneberg ganglion. Results of recent studies suggest that these chemosensory systems perceive diverse but overlapping olfactory cues and that some neurons may even detect the pressure changes carried by the airflow. This review provides an update on how chemosensory neurons transduce chemical (and possibly mechanical) stimuli into electrical signals, and what information each system brings into the brain. Future investigation will focus on the specific ligands that each system detects with a behavioral context and the processing networks that each system involves in the brain. Such studies will lead to a better understanding of how the multiple olfactory systems, acting in concert, offer a complete representation of the chemical world.
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Affiliation(s)
- Minghong Ma
- Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
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Barbour J, Neuhaus EM, Piechura H, Stoepel N, Mashukova A, Brunert D, Sitek B, Stühler K, Meyer HE, Hatt H, Warscheid B. New insight into stimulus-induced plasticity of the olfactory epithelium in Mus musculus by quantitative proteomics. J Proteome Res 2008; 7:1594-605. [PMID: 18336002 DOI: 10.1021/pr7005796] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The olfactory system is exposed to a plethora of chemical compounds throughout an organism's lifespan. Anticipation of stimuli and construction of appropriate neural filters present a significant challenge. This may be addressed via modulation of the protein composition of the sensory epithelium in response to environmental conditions. To reveal the mechanisms governing these changes, we employed a comprehensive quantitative proteomics strategy. Two groups of juvenile mice were treated with either pulsed or continuous application of octanal. After 20 days of treatment, we performed a behavioral study and conducted electrophysiological recordings from the olfactory epithelium (OE). Both treated groups demonstrated peripheral desensitization to octanal; however, only the 'continuous' group exhibited habituation. To obtain novel insight into the molecular mechanisms underpinning the peripheral desensitization to octanal, the OE proteomes of octanal-treated mice versus control were quantitatively analyzed using two-dimensional difference gel electrophoresis. We identified several significantly regulated proteins that were functionally classified as calcium-binding proteins, cytoskeletal proteins, and lipocalins. The calcium-binding proteins and cytoskeletal proteins were up-regulated in the 'pulsed' group, whereas in the 'continuous' group, four lipocalins were significantly down-regulated. Uniquely, the lipocalin odorant-binding protein Ia was drastically down-regulated in both groups. The identified proteins reflect changes throughout the entire OE, corresponding to changes in neuronal, non-neuronal, and pericellular processes. We report the regulation of several promising candidates for the investigation of odorant-induced changes of the OE. Among these proteins are different lipocalins, which seem to play a crucial role in the regulation of the sensitivity of the olfactory system.
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Affiliation(s)
- Jon Barbour
- Medizinisches Proteom-Center, Ruhr-University Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
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45
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Gomez G, Celii A. The peripheral olfactory system of the domestic chicken: physiology and development. Brain Res Bull 2008; 76:208-16. [PMID: 18498933 DOI: 10.1016/j.brainresbull.2008.02.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2007] [Revised: 12/26/2007] [Accepted: 02/13/2008] [Indexed: 10/22/2022]
Abstract
Olfaction is a ubiquitous sensory system found in all terrestrial vertebrates. Birds use olfaction for several important activities such as feeding and mating; thus, understanding bird biology would also require the systematic study olfaction. In addition, the olfactory system has several unique features that are useful for the study of nervous system function and development, including a large multigene family for olfactory receptor expression, peripheral neurons that regenerate, and a complex system for sensory innervation of the olfactory bulb. We focused on physiological, anatomical and behavioral approaches to study the chick olfactory neurons and the olfactory bulb. Chick olfactory neurons displayed some properties similar to those found in mature neurons of other vertebrate species, and other properties that were unique. Since information from these neurons is initially processed in the olfactory bulb, we also conducted preliminary studies on the developmental timeline of this structure and showed that glomerular structures are organized in ovo during a critical time period, during which embryonic chicks can form behavioral associations with odorants introduced in ovo. Lastly, we have shown that chick olfactory neurons can grow and mature in vitro, allowing their use in cell culture studies. These results collectively demonstrate some of the features of the olfactory system that are common to all vertebrates, and some that are unique to birds. These highlight the potential for the use of the physiology and development of the olfactory system as a model system for avian brain neurobiology.
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Affiliation(s)
- George Gomez
- Biology Department, University of Scranton, Scranton, PA 18510, USA.
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46
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Function and dysfunction of CNG channels: insights from channelopathies and mouse models. Mol Neurobiol 2008; 35:266-77. [PMID: 17917115 DOI: 10.1007/s12035-007-0025-y] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Revised: 11/30/1999] [Accepted: 01/05/2007] [Indexed: 10/22/2022]
Abstract
Channels directly gated by cyclic nucleotides (CNG channels) are important cellular switches that mediate influx of Na+ and Ca2+ in response to increases in the intracellular concentration of cAMP and cGMP. In photoreceptors and olfactory receptor neurons, these channels serve as final targets for cGMP and cAMP signaling pathways that are initiated by the absorption of photons and the binding of odorants, respectively. CNG channels have been also found in other types of neurons and in non-excitable cells. However, in most of these cells, the physiological role of CNG channels has yet to be determined. CNG channels have a complex heteromeric structure. The properties of individual subunits that assemble in specific stoichiometries to the native channels have been extensively investigated in heterologous expression systems. Recently, mutations in human CNG channel genes leading to inherited diseases (so-called channelopathies) have been functionally characterized. Moreover, mouse knockout models were generated to define the role of CNG channel proteins in vivo. In this review, we will summarize recent insights into the physiological and pathophysiological role of CNG channel proteins that have emerged from genetic studies in mice and humans.
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Zhang W, Delay RJ. Gonadotropin-releasing hormone modulates voltage-activated sodium current and odor responses in Necturus maculosus olfactory sensory neurons. J Neurosci Res 2007; 85:1656-67. [PMID: 17465028 DOI: 10.1002/jnr.21297] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The terminal nerve (nervus terminalis) extends from the basal forebrain to the nasal cavity and has been shown to contain gonadotropin-releasing hormone (GnRH). The specific function of the terminal nerve is unknown, but it has been hypothesized that it modulates the function of olfactory neurons. To examine the effects of GnRH on isolated Necturus maculosus olfactory sensory neurons (OSNs), we used the perforated configuration of the patch clamp technique to record current responses. GnRH had no effect on the membrane current at any holding potential but did modulate voltage-activated TTX-sensitive sodium current (INa). Within 1 min of applying GnRH, approximately 60% of the OSNs showed a decrease in the magnitude of INa. Initial responses to GnRH were inhibitory, although in one group of cells the initial inhibitory response was followed by a potentiation of INa with continual application (approximately 5 min). The time course of the GnRH response suggested that a second messenger pathway mediated the response. Inhibitors of PKC, tyrosine kinase, and PI3K were all able to inhibit the INa, but none of them could prevent the GnRH response. Application of a cAMP analog mimicked the effects of GnRH, and only inhibitors of PKA and PKG could prevent GnRH-induced inhibition of INa. This suggests that the modulation of voltage-activated sodium currents by GnRH involve a cyclic nucleotide pathway. In addition, GnRH modulated the odor responses of OSNs. Our data suggest the release of GnRH, presumably from the terminal nerve, can serve to modulate olfactory sensory neurons.
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Affiliation(s)
- Wenling Zhang
- Department of Biology, University of Vermont, Burlington, Vermont 05405, USA
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Mobley AS, Mahendra G, Lucero MT. Evidence for multiple signaling pathways in single squid olfactory receptor neurons. J Comp Neurol 2007; 501:231-42. [PMID: 17226749 DOI: 10.1002/cne.21230] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
At least two different G-protein-mediated transduction cascades, the adenylate cyclase and phospholipase C (PLC) pathway, process chemosensory stimuli for various species. In squid olfactory receptor neurons (ORNs), physiological studies indicate that both pathways may be present; however, confirmation of the transduction molecules at the protein level is absent. Here we provide evidence that the G-proteins involved in both adenylate cyclase and PLC pathways are present in squid ORNs (Lolliguncula brevis). We used immunoblotting to show that Galpha(olf), Galpha(q), and a downstream effector, enzyme PLC140, are present in the squid olfactory epithelium (OE). To localize these proteins to one or more of the five morphological cell types described for squid OE, paraformaldehyde-fixed olfactory organs were cryosectioned (10 microm), double-labeled for Galpha(olf), Galpha(q), or PLC140, and imaged. Analysis of serial sections from entire olfactory organs for epithelial area and patterns of immunofluorescence revealed a region of highest immunoreactivity at the anterior half of the organ. At the cellular level, type 1 cells could not be distinguished morphologically and were not included in the analysis. The three labeling patterns observed in type 2 cells were Galpha(q) alone, PLC140 alone, and colocalization of Galpha(q) and PLC140. Subsets of cell types 3, 4, and 5 showed colocalization of Galpha(olf) with Galpha(q) but not with PLC140. These data suggest that the PLC pathway predominates in type 2 cells; however, coexpression of Galpha(olf) with Galpha(q) in cell types 3, 4, and 5 suggests that both pathways may participate in olfactory transduction in non-type 2 squid ORNs.
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Deisig N, Giurfa M, Lachnit H, Sandoz JC. Neural representation of olfactory mixtures in the honeybee antennal lobe. Eur J Neurosci 2007; 24:1161-74. [PMID: 16930442 DOI: 10.1111/j.1460-9568.2006.04959.x] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Natural olfactory stimuli occur as mixtures of many single odors. We studied whether the representation of a mixture in the brain retains single-odor information and how much mixture-specific information it includes. To understand mixture representation in the honeybee brain, we used in vivo calcium imaging at the level of the antennal lobe, and systematically measured odor-evoked activity in 24 identified glomeruli in response to four single odorants and all their possible binary, ternary and quaternary mixtures. Qualitatively, mixture-induced activity patterns always contained glomeruli belonging to the pattern of at least one of the components, suggesting a high conservation of component information in olfactory mixtures. Quantitatively, glomerular activity saturated quickly and increasing the number of components resulted in an increase of cases in which the response of a glomerulus to the mixture was lower than that to the strongest component ('suppression'). This shows global inhibition in the antennal lobe, probably acting as overall gain control. Single components were not equally salient (in terms of number of active glomeruli) and mixture activity patterns were always more similar to the more salient components, in a way that could be predicted linearly. Thus, although a gain control system in the honeybee antennal lobe prevents saturation of the olfactory system, mixture representation follows essentially elemental rules.
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Affiliation(s)
- Nina Deisig
- Research Centre for Animal Cognition, CNRS--Université Paul Sabatier (UMR 5169), 31062 Toulouse cedex 04, France.
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50
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Grosmaitre X, Santarelli LC, Tan J, Luo M, Ma M. Dual functions of mammalian olfactory sensory neurons as odor detectors and mechanical sensors. Nat Neurosci 2007; 10:348-54. [PMID: 17310245 PMCID: PMC2227320 DOI: 10.1038/nn1856] [Citation(s) in RCA: 227] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2006] [Accepted: 01/23/2007] [Indexed: 11/09/2022]
Abstract
Most sensory systems are primarily specialized to detect one sensory modality. Here we report that olfactory sensory neurons (OSNs) in the mammalian nose can detect two distinct modalities transmitted by chemical and mechanical stimuli. As revealed by patch-clamp recordings, many OSNs respond not only to odorants, but also to mechanical stimuli delivered by pressure ejections of odor-free Ringer solution. The mechanical responses correlate directly with the pressure intensity and show several properties similar to those induced by odorants, including onset latency, reversal potential and adaptation to repeated stimulation. Blocking adenylyl cyclase or knocking out the cyclic nucleotide-gated channel CNGA2 eliminates the odorant and the mechanical responses, suggesting that both are mediated by a shared cAMP cascade. We further show that this mechanosensitivity enhances the firing frequency of individual neurons when they are weakly stimulated by odorants and most likely drives the rhythmic activity (theta oscillation) in the olfactory bulb to synchronize with respiration.
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Affiliation(s)
- Xavier Grosmaitre
- Department of Neuroscience, University of Pennsylvania School of Medicine, 215 Stemmler Hall, 3450 Hamilton Walk, Philadelphia, Pennsylvania 19104, USA
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