1
|
Hills M, Ma L, Fang A, Chiremba T, Malloy S, Scott A, Perera A, Yu CR. Molecular, Cellular, and Developmental Organization of the Mouse Vomeronasal organ at Single Cell Resolution. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.22.581574. [PMID: 39253476 PMCID: PMC11383295 DOI: 10.1101/2024.02.22.581574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 09/11/2024]
Abstract
We have generated single cell transcriptomic atlases of vomeronasal organs (VNO) from juvenile and adult mice. Combined with spatial molecular imaging, we uncover a distinct, previously unidentified class of cells that express the vomeronasal receptors and a population of canonical olfactory sensory neurons in the VNO. High resolution trajectory and cluster analyses reveal the lineage relationship, spatial distribution of cell types, and a putative cascade of molecular events that specify the V1r, V2r, and OR lineages from a common stem cell population. The expression of vomeronasal and olfactory receptors follow power law distributions, but there is high variability in average expression levels between individual receptor and cell types. Substantial co-expression is found between receptors across clades, from different classes, and between olfactory and vomeronasal receptors, with nearly half from pairs located on the same chromosome. Interestingly, the expression of V2r, but not V1r, genes is associated with various transcription factors, suggesting distinct mechanisms of receptor choice associated with the two cell types. We identify association between transcription factors, surface axon guidance molecules, and individual VRs, thereby uncovering a molecular code that guides the specification of the vomeronasal circuitry. Our study provides a wealth of data on the development and organization of the accessory olfactory system at both cellular and molecular levels to enable a deeper understanding of vomeronasal system function.
Collapse
Affiliation(s)
- Max Hills
- Stowers Institute for Medical Research, 1000 E. 50 Street, Kansas City, MO 64110, USA
| | - Limei Ma
- Stowers Institute for Medical Research, 1000 E. 50 Street, Kansas City, MO 64110, USA
| | - Ai Fang
- Stowers Institute for Medical Research, 1000 E. 50 Street, Kansas City, MO 64110, USA
| | - Thelma Chiremba
- Stowers Institute for Medical Research, 1000 E. 50 Street, Kansas City, MO 64110, USA
| | - Seth Malloy
- Stowers Institute for Medical Research, 1000 E. 50 Street, Kansas City, MO 64110, USA
| | - Allison Scott
- Stowers Institute for Medical Research, 1000 E. 50 Street, Kansas City, MO 64110, USA
| | - Anoja Perera
- Stowers Institute for Medical Research, 1000 E. 50 Street, Kansas City, MO 64110, USA
| | - C Ron Yu
- Stowers Institute for Medical Research, 1000 E. 50 Street, Kansas City, MO 64110, USA
- Department of Cell Biology and Physiology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
| |
Collapse
|
2
|
Nagel M, Niestroj M, Bansal R, Fleck D, Lampert A, Stopkova R, Stopka P, Ben-Shaul Y, Spehr M. Deciphering the chemical language of inbred and wild mouse conspecific scents. eLife 2024; 12:RP90529. [PMID: 38747258 PMCID: PMC11095937 DOI: 10.7554/elife.90529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/18/2024] Open
Abstract
In most mammals, conspecific chemosensory communication relies on semiochemical release within complex bodily secretions and subsequent stimulus detection by the vomeronasal organ (VNO). Urine, a rich source of ethologically relevant chemosignals, conveys detailed information about sex, social hierarchy, health, and reproductive state, which becomes accessible to a conspecific via vomeronasal sampling. So far, however, numerous aspects of social chemosignaling along the vomeronasal pathway remain unclear. Moreover, since virtually all research on vomeronasal physiology is based on secretions derived from inbred laboratory mice, it remains uncertain whether such stimuli provide a true representation of potentially more relevant cues found in the wild. Here, we combine a robust low-noise VNO activity assay with comparative molecular profiling of sex- and strain-specific mouse urine samples from two inbred laboratory strains as well as from wild mice. With comprehensive molecular portraits of these secretions, VNO activity analysis now enables us to (i) assess whether and, if so, how much sex/strain-selective 'raw' chemical information in urine is accessible via vomeronasal sampling; (ii) identify which chemicals exhibit sufficient discriminatory power to signal an animal's sex, strain, or both; (iii) determine the extent to which wild mouse secretions are unique; and (iv) analyze whether vomeronasal response profiles differ between strains. We report both sex- and, in particular, strain-selective VNO representations of chemical information. Within the urinary 'secretome', both volatile compounds and proteins exhibit sufficient discriminative power to provide sex- and strain-specific molecular fingerprints. While total protein amount is substantially enriched in male urine, females secrete a larger variety at overall comparatively low concentrations. Surprisingly, the molecular spectrum of wild mouse urine does not dramatically exceed that of inbred strains. Finally, vomeronasal response profiles differ between C57BL/6 and BALB/c animals, with particularly disparate representations of female semiochemicals.
Collapse
Affiliation(s)
- Maximilian Nagel
- Department of Chemosensation, Institute for Biology II, RWTH Aachen UniversityAachenGermany
| | - Marco Niestroj
- Department of Chemosensation, Institute for Biology II, RWTH Aachen UniversityAachenGermany
| | - Rohini Bansal
- Department of Medical Neurobiology, Institute for Medical Research Israel Canada, Faculty of Medicine, The Hebrew University of JerusalemJerusalemIsrael
| | - David Fleck
- Department of Chemosensation, Institute for Biology II, RWTH Aachen UniversityAachenGermany
| | - Angelika Lampert
- Institute of Neurophysiology, Uniklinik RWTH Aachen UniversityAachenGermany
- Research Training Group 2416 MultiSenses – MultiScales, RWTH Aachen UniversityAachenGermany
| | - Romana Stopkova
- BIOCEV group, Department of Zoology, Faculty of Science, Charles UniversityPragueCzech Republic
| | - Pavel Stopka
- BIOCEV group, Department of Zoology, Faculty of Science, Charles UniversityPragueCzech Republic
| | - Yoram Ben-Shaul
- Department of Medical Neurobiology, Institute for Medical Research Israel Canada, Faculty of Medicine, The Hebrew University of JerusalemJerusalemIsrael
| | - Marc Spehr
- Department of Chemosensation, Institute for Biology II, RWTH Aachen UniversityAachenGermany
- Research Training Group 2416 MultiSenses – MultiScales, RWTH Aachen UniversityAachenGermany
| |
Collapse
|
3
|
Villamayor PR, Gullón J, Quintela L, Sánchez-Quinteiro P, Martínez P, Robledo D. Sex separation unveils the functional plasticity of the vomeronasal organ in rabbits. Front Mol Neurosci 2022; 15:1034254. [PMID: 36340690 PMCID: PMC9634631 DOI: 10.3389/fnmol.2022.1034254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 10/03/2022] [Indexed: 02/10/2024] Open
Abstract
Chemosensory cues are vital for social and sexual behaviours and are primarily detected and processed by the vomeronasal system (VNS), whose plastic capacity has been investigated in mice. However, studying chemosensory plasticity outside of laboratory conditions may give a more realistic picture of how the VNS adapts to a changing environment. Rabbits are a well-described model of chemocommunication since the discovery of the rabbit mammary pheromone and their vomeronasal organ (VNO) transcriptome was recently characterised, a first step to further study plasticity-mediated transcriptional changes. In this study, we assessed the plastic capacity of the rabbit male and female VNO under sex-separation vs. sex-combined scenarios, including adults and juveniles, to determine whether the rabbit VNO is plastic and, if so, whether such plasticity is already established at early stages of life. First, we characterised the number of differentially expressed genes (DEGs) between the VNO of rabbit male and female under sex-separation and compared it to sex-combined individuals, both in adults and juveniles, finding that differences between male and female were larger in a sex-separated scenario. Secondly, we analysed the number of DEGs between sex-separated and sex-combined scenarios, both in males and females. In adults, both sexes showed a high number of DEGs while in juveniles only females showed differences. Additionally, the vomeronasal receptor genes were strikingly downregulated in sex-separated adult females, whereas in juveniles upregulation was shown for the same condition, suggesting a role of VRs in puberty onset. Finally, we described the environment-modulated plastic capacity of genes involved in reproduction, immunity and VNO functional activity, including G-protein coupled receptors. Our results show that sex-separation induces sex- and stage-specific gene expression differences in the VNO of male and female rabbit, both in adults and juveniles. These results bring out for the first time the plastic capacity of the rabbit VNO, supporting its functional adaptation to specifically respond to a continuous changing environment. Finally, species-specific differences and individual variability should always be considered in VNO studies and overall chemocommunication research.
Collapse
Affiliation(s)
- Paula R. Villamayor
- Departamento de Zooloxía, Xenética e Antropoloxía Física, Facultade de Veterinaria, Universidade de Santiago de Compostela, Lugo, Spain
- Departamento de Anatomía, Producción Animal e Ciencias Clínicas Veterinarias, Facultade de Veterinaria, Universidade de Santiago de Compostela, Lugo, Spain
| | | | - Luis Quintela
- Departamento de Patoloxía Animal, Facultade de Veterinaria Universidade de Santiago de Compostela, Lugo, Spain
| | - Pablo Sánchez-Quinteiro
- Departamento de Anatomía, Producción Animal e Ciencias Clínicas Veterinarias, Facultade de Veterinaria, Universidade de Santiago de Compostela, Lugo, Spain
| | - Paulino Martínez
- Departamento de Zooloxía, Xenética e Antropoloxía Física, Facultade de Veterinaria, Universidade de Santiago de Compostela, Lugo, Spain
| | - Diego Robledo
- The Roslin Institute, The Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Edinburgh, United Kingdom
| |
Collapse
|
4
|
Wong WM, Cao J, Zhang X, Doyle WI, Mercado LL, Gautron L, Meeks JP. Physiology-forward identification of bile acid-sensitive vomeronasal receptors. SCIENCE ADVANCES 2020; 6:eaaz6868. [PMID: 32523992 PMCID: PMC7259934 DOI: 10.1126/sciadv.aaz6868] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 03/20/2020] [Indexed: 06/11/2023]
Abstract
The mouse accessory olfactory system (AOS) supports social and reproductive behavior through the sensation of environmental chemosignals. A growing number of excreted steroids have been shown to be potent AOS cues, including bile acids (BAs) found in feces. As is still the case with most AOS ligands, the specific receptors used by vomeronasal sensory neurons (VSNs) to detect BAs remain unknown. To identify VSN BA receptors, we first performed a deep analysis of VSN BA tuning using volumetric GCaMP6f/s Ca2+ imaging. These experiments revealed multiple populations of BA-receptive VSNs with submicromolar sensitivities. We then developed a new physiology-forward approach for identifying AOS ligand-receptor interactions, which we call Fluorescence Live Imaging for Cell Capture and RNA sequencing, or FLICCR-seq. FLICCR-seq analysis revealed five specific V1R family receptors enriched in BA-sensitive VSNs. These studies introduce a powerful new approach for ligand-receptor matching and reveal biological mechanisms underlying mammalian BA chemosensation.
Collapse
Affiliation(s)
- Wen Mai Wong
- Department of Neuroscience, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas, USA
| | - Jie Cao
- Department of Neuroscience, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas, USA
| | - Xingjian Zhang
- Department of Neuroscience, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas, USA
| | - Wayne I. Doyle
- Department of Neuroscience, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas, USA
| | - Luis L. Mercado
- Division of Hypothalamic Research and Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas, USA
| | - Laurent Gautron
- Division of Hypothalamic Research and Department of Internal Medicine, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas, USA
| | - Julian P. Meeks
- Department of Neuroscience, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas, USA
| |
Collapse
|
5
|
Mohrhardt J, Nagel M, Fleck D, Ben-Shaul Y, Spehr M. Signal Detection and Coding in the Accessory Olfactory System. Chem Senses 2019; 43:667-695. [PMID: 30256909 PMCID: PMC6211456 DOI: 10.1093/chemse/bjy061] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In many mammalian species, the accessory olfactory system plays a central role in guiding behavioral and physiological responses to social and reproductive interactions. Because of its relatively compact structure and its direct access to amygdalar and hypothalamic nuclei, the accessory olfactory pathway provides an ideal system to study sensory control of complex mammalian behavior. During the last several years, many studies employing molecular, behavioral, and physiological approaches have significantly expanded and enhanced our understanding of this system. The purpose of the current review is to integrate older and newer studies to present an updated and comprehensive picture of vomeronasal signaling and coding with an emphasis on early accessory olfactory system processing stages. These include vomeronasal sensory neurons in the vomeronasal organ, and the circuitry of the accessory olfactory bulb. Because the overwhelming majority of studies on accessory olfactory system function employ rodents, this review is largely focused on this phylogenetic order, and on mice in particular. Taken together, the emerging view from both older literature and more recent studies is that the molecular, cellular, and circuit properties of chemosensory signaling along the accessory olfactory pathway are in many ways unique. Yet, it has also become evident that, like the main olfactory system, the accessory olfactory system also has the capacity for adaptive learning, experience, and state-dependent plasticity. In addition to describing what is currently known about accessory olfactory system function and physiology, we highlight what we believe are important gaps in our knowledge, which thus define exciting directions for future investigation.
Collapse
Affiliation(s)
- Julia Mohrhardt
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, Aachen, Germany
| | - Maximilian Nagel
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, Aachen, Germany
| | - David Fleck
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, Aachen, Germany
| | - Yoram Ben-Shaul
- Department of Medical Neurobiology, School of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Marc Spehr
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, Aachen, Germany
| |
Collapse
|
6
|
Holy TE. The Accessory Olfactory System: Innately Specialized or Microcosm of Mammalian Circuitry? Annu Rev Neurosci 2018; 41:501-525. [DOI: 10.1146/annurev-neuro-080317-061916] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In mammals, the accessory olfactory system is a distinct circuit that has received attention for its role in detecting and responding to pheromones. While the neuroscientific investigation of this system is comparatively new, recent advances and its compact size have made it an attractive model for developing an end-to-end understanding of such questions as regulation of essential behaviors, plasticity, and individual recognition. Recent discoveries have indicated a need to reevaluate our conception of this system, suggesting that ( a) physical principles—rather than biological necessity—play an underappreciated role in its raison d'être and that ( b) the anatomy of downstream projections is not dominated by unique specializations but instead consists of an abbreviated cortical/basal ganglia motif reminiscent of other sensorimotor systems. These observations suggest that the accessory olfactory system distinguishes itself primarily by the physicochemical properties of its ligands, but its architecture is otherwise a microcosm of mammalian neurocircuitry.
Collapse
Affiliation(s)
- Timothy E. Holy
- Department of Neuroscience, Washington University, St. Louis, Missouri 63132, USA
| |
Collapse
|
7
|
Silvotti L, Cavaliere RM, Belletti S, Tirindelli R. In-vivo activation of vomeronasal neurons shows adaptive responses to pheromonal stimuli. Sci Rep 2018; 8:8490. [PMID: 29855521 PMCID: PMC5981476 DOI: 10.1038/s41598-018-26831-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 05/18/2018] [Indexed: 01/29/2023] Open
Abstract
In most mammals, the vomeronasal system has a pivotal role in mediating socio-sexual behaviours. The vomeronasal organ senses pheromones through the activation of specific receptors. Pheromone binding to cognate receptors activates Ca-influx via the gating of a cation channel that generates membrane depolarisation. The ex-vivo activation of vomeronasal neurons (VSNs) by pheromonal stimuli has been largely investigated by electrophysiological and imaging techniques; however, few studies have been carried out to determine the physiological responses of VSNs, in-vivo. By tracking the phosphorylation of S6 ribosomal protein as a marker of neuronal activity, we show that S6 becomes phosphorylated (pS6) in mouse VSNs stimulated by intraspecific and heterospecific pheromonal cues. We observed that female scent induces pS6 immunoreactivity in the apical VSNs of male vomeronasal epithelium, whereas male cues stimulate S6 phosphorylation in both the basal and apical VSNs of females. We also show that this dimorphic pattern of pS6 immunoreactivity is reproduced when heterospecific stimuli are used. Moreover, we found that a consistent proportion of VSNs is activated by both heterospecific and intraspecific pheromones. Additionally, we have evidence of adaptive responses to S6 phosphorylation when stimulation with cues of the same and opposite sex and of different species is sustained.
Collapse
Affiliation(s)
- Lucia Silvotti
- Department of Medicine and Surgery, Neuroscience Unit, University of Parma, Via Volturno, 39, 43125, Parma, Italy
| | - Rosa Maria Cavaliere
- Department of Medicine and Surgery, Neuroscience Unit, University of Parma, Via Volturno, 39, 43125, Parma, Italy
| | - Silvana Belletti
- Department of Medicine and Surgery, Neuroscience Unit, University of Parma, Via Volturno, 39, 43125, Parma, Italy
| | - Roberto Tirindelli
- Department of Medicine and Surgery, Neuroscience Unit, University of Parma, Via Volturno, 39, 43125, Parma, Italy.
| |
Collapse
|
8
|
Abstract
Steroids play vital roles in animal physiology across species, and the production of specific steroids is associated with particular internal biological functions. The internal functions of steroids are, in most cases, quite clear. However, an important feature of many steroids (their chemical stability) allows these molecules to play secondary, external roles as chemical messengers after their excretion via urine, feces, or other shed substances. The presence of steroids in animal excretions has long been appreciated, but their capacity to serve as chemosignals has not received as much attention. In theory, the blend of steroids excreted by an animal contains a readout of its own biological state. Initial mechanistic evidence for external steroid chemosensation arose from studies of many species of fish. In sea lampreys and ray-finned fishes, bile salts were identified as potent olfactory cues and later found to serve as pheromones. Recently, we and others have discovered that neurons in amphibian and mammalian olfactory systems are also highly sensitive to excreted glucocorticoids, sex steroids, and bile acids, and some of these molecules have been confirmed as mammalian pheromones. Steroid chemosensation in olfactory systems, unlike steroid detection in most tissues, is performed by plasma membrane receptors, but the details remain largely unclear. In this review, we present a broad view of steroid detection by vertebrate olfactory systems, focusing on recent research in fishes, amphibians, and mammals. We review confirmed and hypothesized mechanisms of steroid chemosensation in each group and discuss potential impacts on vertebrate social communication.
Collapse
|
9
|
Duyck K, DuTell V, Ma L, Paulson A, Yu CR. Pronounced strain-specific chemosensory receptor gene expression in the mouse vomeronasal organ. BMC Genomics 2017; 18:965. [PMID: 29233099 PMCID: PMC5727874 DOI: 10.1186/s12864-017-4364-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 12/01/2017] [Indexed: 01/07/2023] Open
Abstract
Background The chemosensory system plays an important role in orchestrating sexual behaviors in mammals. Pheromones trigger sexually dimorphic behaviors and different mouse strains exhibit differential responses to pheromone stimuli. It has been speculated that differential gene expression in the sensory organs that detect pheromones may underlie sexually-dimorphic and strain-specific responses to pheromone cues. Results We have performed transcriptome analyses of the mouse vomeronasal organ, a sensory organ recognizing pheromones and interspecies cues. We find little evidence of sexual dimorphism in gene expression except for Xist, an essential gene for X-linked gene inactivation. Variations in gene expression are found mainly among strains, with genes from immune response and chemosensory receptor classes dominating the list. Differentially expressed genes are concentrated in genomic hotspots enriched in these families of genes. Some chemosensory receptors show exclusive patterns of expression in different strains. We find high levels of single nucleotide polymorphism in chemosensory receptor pseudogenes, some of which lead to functionalized receptors. Moreover, we identify a number of differentially expressed long noncoding RNA species showing strong correlation or anti-correlation with chemoreceptor genes. Conclusions Our analyses provide little evidence supporting sexually dimorphic gene expression in the vomeronasal organ that may underlie dimorphic pheromone responses. In contrast, we find pronounced variations in the expression of immune response related genes, vomeronasal and G-protein coupled receptor genes among different mouse strains. These findings raised the possibility that diverse strains of mouse perceive pheromone cues differently and behavioral difference among strains in response to pheromone may first arise from differential detection of pheromones. On the other hand, sexually dimorphic responses to pheromones more likely originate from dimorphic neural circuits in the brain than from differential detection. Moreover, noncoding RNA may offer a potential regulatory mechanism controlling the differential expression patterns. Electronic supplementary material The online version of this article (10.1186/s12864-017-4364-4) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Kyle Duyck
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO, 64110, USA
| | - Vasha DuTell
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO, 64110, USA.,Redwood Center for Theoretical Neuroscience, University of California, 567 Evans Hall, Berkeley, 94720, USA
| | - Limei Ma
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO, 64110, USA
| | - Ariel Paulson
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO, 64110, USA
| | - C Ron Yu
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO, 64110, USA. .,Department of Anatomy and Cell Biology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS, 66160, USA.
| |
Collapse
|
10
|
Type 3 inositol 1,4,5-trisphosphate receptor is dispensable for sensory activation of the mammalian vomeronasal organ. Sci Rep 2017; 7:10260. [PMID: 28860523 PMCID: PMC5579292 DOI: 10.1038/s41598-017-09638-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 07/21/2017] [Indexed: 12/31/2022] Open
Abstract
Signal transduction in sensory neurons of the mammalian vomeronasal organ (VNO) involves the opening of the canonical transient receptor potential channel Trpc2, a Ca2+-permeable cation channel that is activated by diacylglycerol and inhibited by Ca2+-calmodulin. There has been a long-standing debate about the extent to which the second messenger inositol 1,4,5-trisphosphate (InsP3) and type 3 InsP3 receptor (InsP3R3) are involved in the opening of Trpc2 channels and in sensory activation of the VNO. To address this question, we investigated VNO function of mice carrying a knockout mutation in the Itpr3 locus causing a loss of InsP3R3. We established a new method to monitor Ca2+ in the endoplasmic reticulum of vomeronasal sensory neurons (VSNs) by employing the GFP-aequorin protein sensor erGAP2. We also performed simultaneous InsP3 photorelease and Ca2+ monitoring experiments, and analysed Ca2+ dynamics, sensory currents, and action potential or field potential responses in InsP3R3-deficient VSNs. Disruption of Itpr3 abolished or minimized the Ca2+ transients evoked by photoactivated InsP3, but there was virtually no effect on sensory activation of VSNs. Therefore, InsP3R3 is dispensable for primary chemoelectrical transduction in mouse VNO. We conclude that InsP3R3 is not required for gating of Trpc2 in VSNs.
Collapse
|