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Dibattista M, Pifferi S, Hernandez-Clavijo A, Menini A. The physiological roles of anoctamin2/TMEM16B and anoctamin1/TMEM16A in chemical senses. Cell Calcium 2024; 120:102889. [PMID: 38677213 DOI: 10.1016/j.ceca.2024.102889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 04/11/2024] [Accepted: 04/17/2024] [Indexed: 04/29/2024]
Abstract
Chemical senses allow animals to detect and discriminate a vast array of molecules. The olfactory system is responsible of the detection of small volatile molecules, while water dissolved molecules are detected by taste buds in the oral cavity. Moreover, many animals respond to signaling molecules such as pheromones and other semiochemicals through the vomeronasal organ. The peripheral organs dedicated to chemical detection convert chemical signals into perceivable information through the employment of diverse receptor types and the activation of multiple ion channels. Two ion channels, TMEM16B, also known as anoctamin2 (ANO2) and TMEM16A, or anoctamin1 (ANO1), encoding for Ca2+-activated Cl¯ channels, have been recently described playing critical roles in various cell types. This review aims to discuss the main properties of TMEM16A and TMEM16B-mediated currents and their physiological roles in chemical senses. In olfactory sensory neurons, TMEM16B contributes to amplify the odorant response, to modulate firing, response kinetics and adaptation. TMEM16A and TMEM16B shape the pattern of action potentials in vomeronasal sensory neurons increasing the interspike interval. In type I taste bud cells, TMEM16A is activated during paracrine signaling mediated by ATP. This review aims to shed light on the regulation of diverse signaling mechanisms and neuronal excitability mediated by Ca-activated Cl¯ channels, hinting at potential new roles for TMEM16A and TMEM16B in the chemical senses.
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Affiliation(s)
- Michele Dibattista
- Department of Translational Biomedicine and Neuroscience, University of Bari A. Moro, 70121 Bari, Italy
| | - Simone Pifferi
- Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, 60126 Ancona, Italy.
| | - Andres Hernandez-Clavijo
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, 52074 Aachen, Germany
| | - Anna Menini
- Neurobiology Group, SISSA, Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy.
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2
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Takeuchi H, Kurahashi T. Segregation of Ca2+ signaling in olfactory signal transduction. J Gen Physiol 2023; 155:213865. [PMID: 36787110 PMCID: PMC9960254 DOI: 10.1085/jgp.202213165] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 11/04/2022] [Accepted: 01/13/2023] [Indexed: 02/15/2023] Open
Abstract
Olfactory signal transduction is conducted through a cAMP-mediated second messenger cascade. The cytoplasmic Ca2+ concentration increases through the opening of CNG channels, a phenomenon that underlies two major functions, namely, signal boosting and olfactory adaptation. Signal boosting is achieved by an additional opening of the Ca2+-activated Cl- channel whereas adaptation is regulated by Ca2+ feedback to the CNG channel. Thus, the influx of Ca2+ and the resultant increase in cytoplasmic Ca2+ levels play seemingly opposing effects: increasing the current while reducing the current through adaptation. The two functions could be interpreted as compensating for each other. However, in real cells, both functions should be segregated. Ca2+ dynamics in olfactory cilia need to be directly measured, but technical difficulties accompanying the thin structure of olfactory cilia have prevented systematic analyses. In this study, using a combination of electrophysiology, local photolysis of caged cAMP, and Ca2+ imaging, we found that free Ca2+ in the local ciliary cytoplasm decreased along with a reduction in the current containing Ca2+-activated Cl- components returning to the basal level, whereas Ca2+-dependent adaptation persisted for a longer period. The activity of Cl- channels is highly likely to be regulated by the free Ca2+ that is present only immediately after the influx through the CNG channel, and an exclusive interaction between Ca2+ and Ca2+-binding proteins that mediate the adaptation may modulate the adaptation lifetime.
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Affiliation(s)
- Hiroko Takeuchi
- Department of Biophysical Dynamics, Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
- Correspondence to Hiroko Takeuchi:
| | - Takashi Kurahashi
- Department of Biophysical Dynamics, Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
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3
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Abdelazim MH, Abdelazim AH. Effect of Sodium Gluconate on Decreasing Elevated Nasal Calcium and Improving Olfactory Function Post COVID-19 Infection. Am J Rhinol Allergy 2022; 36:841-848. [PMID: 35942688 PMCID: PMC9364068 DOI: 10.1177/19458924221120116] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Background COVID-19 has been associated with temporary olfactory dysfunction in many
infected patients. Calcium plays a great role in the olfaction process with
negative feedback for the olfaction transmission. Many reports demonstrated
calcium elevation in the nasal secretions with a negative effect on
olfaction. Sodium gluconate is a water-soluble salt with a chemical
structure that lends to act as a highly efficient chelating agent. It can
bind the elevated calcium in the nasal secretions reducing the adverse
effects on olfactory function. Objective To evaluate the impact of intranasal sodium gluconate on decreasing the rise
of nasal calcium and improving the sense of smell in patients with olfactory
dysfunction post-COVID-19 infection. Methods Fifty patients with a history of confirmed COVID-19 suffering from olfactory
dysfunction persisted more than 90 days after severe acute respiratory
syndrome-coronavirus-2 negative testing were included in a prospective
randomized blinded controlled clinical trial. Patients were divided into 2
equal groups, receiving either 0.9% sodium chloride or 1% sodium gluconate.
Olfactory function was assessed before treatment and 1 month later using the
Sniffin’ Sticks test. Quantitative analysis of the nasal calcium
concentration was performed before treatment and 1 month later using a
laboratory-designed screen-printed ion-selective electrode. Results After using sodium gluconate, the measured olfactory scores indicated a
clinical improvement from anosmia to hyposmia compared to the nonimprovement
sodium chloride receiving group. Also, a remarked decrease in the calcium
nasal concentration was observed after using sodium gluconate compared to
sodium chloride. Conclusion Based on the proposed results, sodium gluconate may associate with an
improvement of the olfactory dysfunction post-COVID-19 infection.
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Affiliation(s)
- Mohamed H Abdelazim
- Department of Otolaryngology, Faculty of Medicine, 68820Al-Azhar University, Damietta, Egypt
| | - Ahmed H Abdelazim
- Pharmaceutical Analytical Chemistry Department, Faculty of Pharmacy, 68820Al-Azhar University, Cairo, Egypt
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4
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Li RC, Molday LL, Lin CC, Ren X, Fleischmann A, Molday RS, Yau KW. Low signaling efficiency from receptor to effector in olfactory transduction: A quantified ligand-triggered GPCR pathway. Proc Natl Acad Sci U S A 2022; 119:e2121225119. [PMID: 35914143 PMCID: PMC9371729 DOI: 10.1073/pnas.2121225119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 07/11/2022] [Indexed: 02/03/2023] Open
Abstract
G protein-coupled receptor (GPCR) signaling is ubiquitous. As an archetype of this signaling motif, rod phototransduction has provided many fundamental, quantitative details, including a dogma that one active GPCR molecule activates a substantial number of downstream G protein/enzyme effector complexes. However, rod phototransduction is light-activated, whereas GPCR pathways are predominantly ligand-activated. Here, we report a detailed study of the ligand-triggered GPCR pathway in mammalian olfactory transduction, finding that an odorant-receptor molecule when (one-time) complexed with its most effective odorants produces on average much less than one downstream effector. Further experiments gave a nominal success probability of tentatively ∼10-4 (more conservatively, ∼10-2 to ∼10-5). This picture is potentially more generally representative of GPCR signaling than is rod phototransduction, constituting a paradigm shift.
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Affiliation(s)
- Rong-Chang Li
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Laurie L. Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - Chih-Chun Lin
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205
- Neuroscience Graduate Program, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Xiaozhi Ren
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | | | - Robert S. Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC V6T 1Z3, Canada
| | - King-Wai Yau
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205
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5
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Hawn MB, Akin E, Hartzell H, Greenwood IA, Leblanc N. Molecular mechanisms of activation and regulation of ANO1-Encoded Ca 2+-Activated Cl - channels. Channels (Austin) 2021; 15:569-603. [PMID: 34488544 PMCID: PMC8480199 DOI: 10.1080/19336950.2021.1975411] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 08/29/2021] [Indexed: 01/13/2023] Open
Abstract
Ca2+-activated Cl- channels (CaCCs) perform a multitude of functions including the control of cell excitability, regulation of cell volume and ionic homeostasis, exocrine and endocrine secretion, fertilization, amplification of olfactory sensory function, and control of smooth muscle cell contractility. CaCCs are the translated products of two members (ANO1 and ANO2, also known as TMEM16A and TMEM16B) of the Anoctamin family of genes comprising ten paralogs. This review focuses on recent progress in understanding the molecular mechanisms involved in the regulation of ANO1 by cytoplasmic Ca2+, post-translational modifications, and how the channel protein interacts with membrane lipids and protein partners. After first reviewing the basic properties of native CaCCs, we then present a brief historical perspective highlighting controversies about their molecular identity in native cells. This is followed by a summary of the fundamental biophysical and structural properties of ANO1. We specifically address whether the channel is directly activated by internal Ca2+ or indirectly through the intervention of the Ca2+-binding protein Calmodulin (CaM), and the structural domains responsible for Ca2+- and voltage-dependent gating. We then review the regulation of ANO1 by internal ATP, Calmodulin-dependent protein kinase II-(CaMKII)-mediated phosphorylation and phosphatase activity, membrane lipids such as the phospholipid phosphatidyl-(4,5)-bisphosphate (PIP2), free fatty acids and cholesterol, and the cytoskeleton. The article ends with a survey of physical and functional interactions of ANO1 with other membrane proteins such as CLCA1/2, inositol trisphosphate and ryanodine receptors in the endoplasmic reticulum, several members of the TRP channel family, and the ancillary Κ+ channel β subunits KCNE1/5.
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Affiliation(s)
- M. B. Hawn
- Department of Pharmacology and Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, United States
| | - E. Akin
- Department of Pharmacology and Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, United States
| | - H.C. Hartzell
- Department of Cell Biology, Emory University School of Medicine, USA
| | - I. A. Greenwood
- Department of Vascular Pharmacology, St. George’s University of London, UK
| | - N. Leblanc
- Department of Pharmacology and Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, United States
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6
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Le SC, Liang P, Lowry AJ, Yang H. Gating and Regulatory Mechanisms of TMEM16 Ion Channels and Scramblases. Front Physiol 2021; 12:787773. [PMID: 34867487 PMCID: PMC8640346 DOI: 10.3389/fphys.2021.787773] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 10/29/2021] [Indexed: 12/30/2022] Open
Abstract
The transmembrane protein 16 (TMEM16) family consists of Ca2+-activated ion channels and Ca2+-activated phospholipid scramblases (CaPLSases) that passively flip-flop phospholipids between the two leaflets of the membrane bilayer. Owing to their diverse functions, TMEM16 proteins have been implicated in various human diseases, including asthma, cancer, bleeding disorders, muscular dystrophy, arthritis, epilepsy, dystonia, ataxia, and viral infection. To understand TMEM16 proteins in health and disease, it is critical to decipher their molecular mechanisms of activation gating and regulation. Structural, biophysical, and computational characterizations over the past decade have greatly advanced the molecular understanding of TMEM16 proteins. In this review, we summarize major structural features of the TMEM16 proteins with a focus on regulatory mechanisms and gating.
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Affiliation(s)
- Son C. Le
- Department of Biochemistry, Duke University Medical Center, Durham, NC, United States
| | - Pengfei Liang
- Department of Biochemistry, Duke University Medical Center, Durham, NC, United States
| | - Augustus J. Lowry
- Department of Biochemistry, Duke University Medical Center, Durham, NC, United States
| | - Huanghe Yang
- Department of Biochemistry, Duke University Medical Center, Durham, NC, United States
- Department of Neurobiology, Duke University Medical Center, Durham, NC, United States
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7
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AlMatrouk A, Lemons K, Ogura T, Lin W. Modification of the Peripheral Olfactory System by Electronic Cigarettes. Compr Physiol 2021; 11:2621-2644. [PMID: 34661289 DOI: 10.1002/cphy.c210007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Electronic cigarettes (e-cigs) are used by millions of adolescents and adults worldwide. Commercial e-liquids typically contain flavorants, propylene glycol, and vegetable glycerin with or without nicotine. These chemical constituents are detected and evaluated by chemosensory systems to guide and modulate vaping behavior and product choices of e-cig users. The flavorants in e-liquids are marketing tools. They evoke sensory percepts of appealing flavors through activation of chemical sensory systems to promote the initiation and sustained use of e-cigs. The vast majority of flavorants in e-liquids are volatile odorants, and as such, the olfactory system plays a dominant role in perceiving these molecules that enter the nasal cavity either orthonasally or retronasally during vaping. In addition to flavorants, e-cig aerosol contains a variety of by-products generated through heating the e-liquids, including odorous irritants, toxicants, and heavy metals. These harmful substances can directly and adversely impact the main olfactory epithelium (MOE). In this article, we first discuss the olfactory contribution to e-cig flavor perception. We then provide information on MOE cell types and their major functions in olfaction and epithelial maintenance. Olfactory detection of flavorants, nicotine, and odorous irritants and toxicants are also discussed. Finally, we discuss the cumulated data on modification of the MOE by flavorant exposure and toxicological impacts of formaldehyde, acrolein, and heavy metals. Together, the information presented in this overview may provide insight into how e-cig exposure may modify the olfactory system and adversely impact human health through the alteration of the chemosensory factor driving e-cig use behavior and product selections. © 2021 American Physiological Society. Compr Physiol 11:2621-2644, 2021.
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Affiliation(s)
- Abdullah AlMatrouk
- General Department of Criminal Evidence, Forensic Laboratories, Ministry of Interior, Farwaniyah, Kuwait.,Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland, USA
| | - Kayla Lemons
- Department of Psychiatry and Behavioral Sciences, Duke University School of Medicine, Durham, North Carolina, USA.,Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland, USA
| | - Tatsuya Ogura
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland, USA
| | - Weihong Lin
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, Maryland, USA
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8
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Kolesnikov D, Perevoznikova A, Gusev K, Glushankova L, Kaznacheyeva E, Shalygin A. Electrophysiological Properties of Endogenous Single Ca 2+ Activated Cl - Channels Induced by Local Ca 2+ Entry in HEK293. Int J Mol Sci 2021; 22:4767. [PMID: 33946319 PMCID: PMC8124839 DOI: 10.3390/ijms22094767] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 04/26/2021] [Accepted: 04/28/2021] [Indexed: 12/19/2022] Open
Abstract
Microdomains formed by proteins of endoplasmic reticulum and plasma membrane play a key role in store-operated Ca2+ entry (SOCE). Ca2+ release through inositol 1,4,5-trisphosphate receptor (IP3R) and subsequent Ca2+ store depletion activate STIM (stromal interaction molecules) proteins, sensors of intraluminal Ca2+, which, in turn, open the Orai channels in plasma membrane. Downstream to this process could be activated TRPC (transient receptor potential-canonical) calcium permeable channels. Using single channel patch-clamp technique we found that a local Ca2+ entry through TRPC1 channels activated endogenous Ca2+-activated chloride channels (CaCCs) with properties similar to Anoctamin6 (TMEM16F). Our data suggest that their outward rectification is based on the dependence from membrane potential of both the channel conductance and the channel activity: (1) The conductance of active CaCCs highly depends on the transmembrane potential (from 3 pS at negative potentials till 60 pS at positive potentials); (2) their activity (NPo) is enhanced with increasing Ca2+ concentration and/or transmembrane potential, conversely lowering of intracellular Ca2+ concentration reduced the open state dwell time; (3) CaCC amplitude is only slightly increased by intracellular Ca2+ concentration. Experiments with Ca2+ buffering by EGTA or BAPTA suggest close local arrangement of functional CaCCs and TRPC1 channels. It is supposed that Ca2+-activated chloride channels are involved in Ca2+ entry microdomains.
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Affiliation(s)
| | | | | | | | - Elena Kaznacheyeva
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, 194064 St. Petersburg, Russia; (D.K.); (A.P.); (K.G.); (L.G.)
| | - Alexey Shalygin
- Institute of Cytology, Russian Academy of Sciences, 4 Tikhoretsky Avenue, 194064 St. Petersburg, Russia; (D.K.); (A.P.); (K.G.); (L.G.)
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9
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Boccaccio A, Menini A, Pifferi S. The cyclic AMP signaling pathway in the rodent main olfactory system. Cell Tissue Res 2021; 383:429-443. [PMID: 33447881 DOI: 10.1007/s00441-020-03391-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 12/10/2020] [Indexed: 01/15/2023]
Abstract
Odor perception begins with the detection of odorant molecules by the main olfactory epithelium located in the nasal cavity. Odorant molecules bind to and activate a large family of G-protein-coupled odorant receptors and trigger a cAMP-mediated transduction cascade that converts the chemical stimulus into an electrical signal transmitted to the brain. Morever, odorant receptors and cAMP signaling plays a relevant role in olfactory sensory neuron development and axonal targeting to the olfactory bulb. This review will first explore the physiological response of olfactory sensory neurons to odorants and then analyze the different components of cAMP signaling and their different roles in odorant detection and olfactory sensory neuron development.
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Affiliation(s)
- Anna Boccaccio
- Institute of Biophysics, National Research Council (CNR), Genova, Italy.
| | - Anna Menini
- Neurobiology Group, SISSA, Scuola Internazionale Superiore di Studi Avanzati, Trieste, Italy
| | - Simone Pifferi
- Neurobiology Group, SISSA, Scuola Internazionale Superiore di Studi Avanzati, Trieste, Italy.,Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, Ancona, Italy
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10
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Le SC, Yang H. Structure-Function of TMEM16 Ion Channels and Lipid Scramblases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1349:87-109. [PMID: 35138612 PMCID: PMC11020148 DOI: 10.1007/978-981-16-4254-8_6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The TMEM16 protein family comprises two novel classes of structurally conserved but functionally distinct membrane transporters that function as Ca2+-dependent Cl- channels (CaCCs) or dual functional Ca2+-dependent ion channels and phospholipid scramblases. Extensive functional and structural studies have advanced our understanding of TMEM16 molecular mechanisms and physiological functions. TMEM16A and TMEM16B CaCCs control transepithelial fluid transport, smooth muscle contraction, and neuronal excitability, whereas TMEM16 phospholipid scramblases mediate the flip-flop of phospholipids across the membrane to allow phosphatidylserine externalization, which is essential in a plethora of important processes such as blood coagulation, bone development, and viral and cell fusion. In this chapter, we summarize the major methods in studying TMEM16 ion channels and scramblases and then focus on the current mechanistic understanding of TMEM16 Ca2+- and voltage-dependent channel gating as well as their ion and phospholipid permeation.
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Affiliation(s)
- Son C Le
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA
| | - Huanghe Yang
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA.
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11
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Lemons K, Fu Z, Ogura T, Lin W. TRPM5-expressing Microvillous Cells Regulate Region-specific Cell Proliferation and Apoptosis During Chemical Exposure. Neuroscience 2020; 434:171-190. [PMID: 32224228 DOI: 10.1016/j.neuroscience.2020.03.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 03/19/2020] [Accepted: 03/20/2020] [Indexed: 12/23/2022]
Abstract
The mammalian main olfactory epithelium (MOE) is exposed to a wide spectrum of external chemicals during respiration and relies on adaptive plasticity to maintain its structural and functional integrity. We previously reported that the chemo-responsive and cholinergic transient receptor potential channel M5 (TRPM5)-expressing-microvillous cells (MCs) in the MOE are required for maintaining odor-evoked electrophysiological responses and olfactory-guided behavior during two-week exposure to an inhaled chemical mixture. Here, we investigated the underlying factors by assessing the potential modulatory effects of TRPM5-MCs on MOE morphology and cell proliferation and apoptosis, which are important for MOE maintenance. In the posterior MOE of TRPM5-GFP mice, we found that two-week chemical exposure induced a significant increase in Ki67-expressing proliferating basal stem cells without a significant reduction in the thickness of the whole epithelium or mature olfactory sensory neuron (OSN) layer. This adaptive increase in stem cell proliferation was missing in chemical-exposed transcription factor Skn-1a knockout (Skn-1a-/-) mice lacking TRPM5-MCs. In addition, a greater number of isolated OSNs from chemical-exposed Skn-1a-/- mice displayed unhealthily high levels of resting intracellular Ca2+. Intriguingly, in the anterior MOE where we found a higher density of TRPM5-MCs, chemical-exposed TRPM5-GFP mice exhibited a time-dependent increase in apoptosis and a loss of mature OSNs without a significant increase in proliferation or neurogenesis to compensate for OSN loss. Together, our data suggest that TRPM5-MC-dependent region-specific upregulation of cell proliferation in the majority of the MOE during chemical exposure contributes to the adaptive maintenance of OSNs and olfactory function.
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Affiliation(s)
- Kayla Lemons
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Ziying Fu
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Tatsuya Ogura
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA
| | - Weihong Lin
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD 21250, USA.
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12
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Ayon RJ, Hawn MB, Aoun J, Wiwchar M, Forrest AS, Cunningham F, Singer CA, Valencik ML, Greenwood IA, Leblanc N. Molecular mechanism of TMEM16A regulation: role of CaMKII and PP1/PP2A. Am J Physiol Cell Physiol 2019; 317:C1093-C1106. [PMID: 31461344 DOI: 10.1152/ajpcell.00059.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
This study explored the mechanism by which Ca2+-activated Cl- channels (CaCCs) encoded by the Tmem16a gene are regulated by calmodulin-dependent protein kinase II (CaMKII) and protein phosphatases 1 (PP1) and 2A (PP2A). Ca2+-activated Cl- currents (IClCa) were recorded from HEK-293 cells expressing mouse TMEM16A. IClCa were evoked using a pipette solution in which free Ca2+ concentration was clamped to 500 nM, in the presence (5 mM) or absence of ATP. With 5 mM ATP, IClCa decayed to <50% of the initial current magnitude within 10 min after seal rupture. IClCa rundown seen with ATP-containing pipette solution was greatly diminished by omitting ATP. IClCa recorded after 20 min of cell dialysis with 0 ATP were more than twofold larger than those recorded with 5 mM ATP. Intracellular application of autocamtide-2-related inhibitory peptide (5 µM) or KN-93 (10 µM), two specific CaMKII inhibitors, produced a similar attenuation of TMEM16A rundown. In contrast, internal application of okadaic acid (30 nM) or cantharidin (100 nM), two nonselective PP1 and PP2A blockers, promoted the rundown of TMEM16A in cells dialyzed with 0 ATP. Mutating serine 528 of TMEM16A to an alanine led to a similar inhibition of TMEM16A rundown to that exerted by either one of the two CaMKII inhibitors tested, which was not observed for three putative CaMKII consensus sites for phosphorylation (T273, T622, and S730). Our results suggest that TMEM16A-mediated CaCCs are regulated by CaMKII and PP1/PP2A. Our data also suggest that serine 528 of TMEM16A is an important contributor to the regulation of IClCa by CaMKII.
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Affiliation(s)
- Ramon J Ayon
- Division of Translational and Regenerative Medicine, Department of Medicine, College of Medicine, The University of Arizona College of Medicine, Arizona Health Sciences Center, Tucson, Arizona
| | - Matthew B Hawn
- Department of Pharmacology, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada.,The Center for Cardiovascular Research, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Joydeep Aoun
- Department of Pharmacology, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada.,The Center for Cardiovascular Research, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Michael Wiwchar
- Department of Pharmacology, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Abigail S Forrest
- Department of Pharmacology, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Fiona Cunningham
- Department of Pharmacology, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Cherie A Singer
- Department of Pharmacology, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Maria L Valencik
- Department of Pharmacology, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
| | - Iain A Greenwood
- Institute of Molecular and Clinical Sciences, St. George's University of London, London, United Kingdom
| | - Normand Leblanc
- Department of Pharmacology, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada.,The Center for Cardiovascular Research, Center of Biomedical Research Excellence for Molecular and Cellular Signal Transduction in the Cardiovascular System, University of Nevada, Reno School of Medicine, Reno, Nevada
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13
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Le SC, Jia Z, Chen J, Yang H. Molecular basis of PIP 2-dependent regulation of the Ca 2+-activated chloride channel TMEM16A. Nat Commun 2019; 10:3769. [PMID: 31434906 PMCID: PMC6704070 DOI: 10.1038/s41467-019-11784-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 08/02/2019] [Indexed: 11/20/2022] Open
Abstract
The calcium-activated chloride channel (CaCC) TMEM16A plays crucial roles in regulating neuronal excitability, smooth muscle contraction, fluid secretion and gut motility. While opening of TMEM16A requires binding of intracellular Ca2+, prolonged Ca2+-dependent activation results in channel desensitization or rundown, the mechanism of which is unclear. Here we show that phosphatidylinositol (4,5)-bisphosphate (PIP2) regulates TMEM16A channel activation and desensitization via binding to a putative binding site at the cytosolic interface of transmembrane segments (TMs) 3-5. We further demonstrate that the ion-conducting pore of TMEM16A is constituted of two functionally distinct modules: a Ca2+-binding module formed by TMs 6-8 and a PIP2-binding regulatory module formed by TMs 3-5, which mediate channel activation and desensitization, respectively. PIP2 dissociation from the regulatory module results in ion-conducting pore collapse and subsequent channel desensitization. Our findings thus provide key insights into the mechanistic understanding of TMEM16 channel gating and lipid-dependent regulation.
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Affiliation(s)
- Son C Le
- Department of Biochemistry, Duke University Medical Center, Durham, NC, USA
| | - Zhiguang Jia
- Department of Chemistry, University of Massachusetts, Amherst, MA, USA
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts, Amherst, MA, USA
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA, USA
| | - Huanghe Yang
- Department of Biochemistry, Duke University Medical Center, Durham, NC, USA.
- Department of Neurobiology, Duke University Medical Center, Durham, NC, USA.
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Ca 2+-activated Cl - current ensures robust and reliable signal amplification in vertebrate olfactory receptor neurons. Proc Natl Acad Sci U S A 2018; 116:1053-1058. [PMID: 30598447 DOI: 10.1073/pnas.1816371116] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Activation of most primary sensory neurons results in transduction currents that are carried by cations. One notable exception is the vertebrate olfactory receptor neuron (ORN), where the transduction current is carried largely by the anion [Formula: see text] However, it remains unclear why ORNs use an anionic current for signal amplification. We have sought to provide clarification on this topic by studying the so far neglected dynamics of [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] in the small space of olfactory cilia during an odorant response. Using computational modeling and simulations we compared the outcomes of signal amplification based on either [Formula: see text] or [Formula: see text] currents. We found that amplification produced by [Formula: see text] influx instead of a [Formula: see text] efflux is problematic for several reasons: First, the [Formula: see text] current amplitude varies greatly, depending on mucosal ion concentration changes. Second, a [Formula: see text] current leads to a large increase in the ciliary [Formula: see text] concentration during an odorant response. This increase inhibits and even reverses [Formula: see text] clearance by [Formula: see text] exchange, which is essential for response termination. Finally, a [Formula: see text] current increases the ciliary osmotic pressure, which could cause swelling to damage the cilia. By contrast, a transduction pathway based on [Formula: see text] efflux circumvents these problems and renders the odorant response robust and reliable.
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Wang L, Feng Y, Yan D, Qin L, Grati M, Mittal R, Li T, Sundhari AK, Liu Y, Chapagain P, Blanton SH, Liao S, Liu X. A dominant variant in the PDE1C gene is associated with nonsyndromic hearing loss. Hum Genet 2018; 137:437-446. [PMID: 29860631 PMCID: PMC6560636 DOI: 10.1007/s00439-018-1895-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 05/26/2018] [Indexed: 01/02/2023]
Abstract
Identification of genes with variants causing non-syndromic hearing loss (NSHL) is challenging due to genetic heterogeneity. The difficulty is compounded by technical limitations that in the past prevented comprehensive gene identification. Recent advances in technology, using targeted capture and next-generation sequencing (NGS), is changing the face of gene identification and making it possible to rapidly and cost-effectively sequence the whole human exome. Here, we characterize a five-generation Chinese family with progressive, postlingual autosomal dominant nonsyndromic hearing loss (ADNSHL). By combining population-specific mutation arrays, targeted deafness genes panel, whole exome sequencing (WES), we identified PDE1C (Phosphodiesterase 1C) c.958G>T (p.A320S) as the disease-associated variant. Structural modeling insights into p.A320S strongly suggest that the sequence alteration will likely affect the substrate-binding pocket of PDE1C. By whole-mount immunofluorescence on postnatal day 3 mouse cochlea, we show its expression in outer (OHC) and inner (IHC) hair cells cytosol co-localizing with Lamp-1 in lysosomes. Furthermore, we provide evidence that the variant alters the PDE1C hydrolytic activity for both cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Collectively, our findings indicate that the c.958G>T variant in PDE1C may disrupt the cross talk between cGMP-signaling and cAMP pathways in Ca2+ homeostasis.
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Affiliation(s)
- Li Wang
- Institute of Medical Genetics, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
- Department of Otolaryngology (D-48), Miller School of Medicine, University of Miami, 1666 NW 12th Avenue, Miami, FL, 33136, USA
| | - Yong Feng
- Department of Otolaryngology, Xiangya Hospital, Central South University, Changsha, China
| | - Denise Yan
- Department of Otolaryngology (D-48), Miller School of Medicine, University of Miami, 1666 NW 12th Avenue, Miami, FL, 33136, USA
| | - Litao Qin
- Institute of Medical Genetics, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
| | - M'hamed Grati
- Department of Otolaryngology (D-48), Miller School of Medicine, University of Miami, 1666 NW 12th Avenue, Miami, FL, 33136, USA
- Laboratory of Cell Structure and Dynamics, NIDCD, NIH, Bethesda, MD, 20892, USA
| | - Rahul Mittal
- Department of Otolaryngology (D-48), Miller School of Medicine, University of Miami, 1666 NW 12th Avenue, Miami, FL, 33136, USA
| | - Tao Li
- Institute of Medical Genetics, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
| | - Abhiraami Kannan Sundhari
- Department of Otolaryngology (D-48), Miller School of Medicine, University of Miami, 1666 NW 12th Avenue, Miami, FL, 33136, USA
| | - Yalan Liu
- Department of Otolaryngology (D-48), Miller School of Medicine, University of Miami, 1666 NW 12th Avenue, Miami, FL, 33136, USA
| | - Prem Chapagain
- Department of Physics, Florida International University, Miami, FL, USA
- Biomolecular Sciences Institute, Florida International University, Miami, FL, USA
| | - Susan H Blanton
- Department of Otolaryngology (D-48), Miller School of Medicine, University of Miami, 1666 NW 12th Avenue, Miami, FL, 33136, USA
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, 33136, USA
| | - Shixiu Liao
- Institute of Medical Genetics, Henan Provincial People's Hospital, People's Hospital of Zhengzhou University, Zhengzhou, China
| | - Xuezhong Liu
- Department of Otolaryngology (D-48), Miller School of Medicine, University of Miami, 1666 NW 12th Avenue, Miami, FL, 33136, USA.
- Department of Otolaryngology, Xiangya Hospital, Central South University, Changsha, China.
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami Miller School of Medicine, Miami, FL, 33136, USA.
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Ca 2+-activated Cl current predominates in threshold response of mouse olfactory receptor neurons. Proc Natl Acad Sci U S A 2018; 115:5570-5575. [PMID: 29735665 DOI: 10.1073/pnas.1803443115] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
In mammalian olfactory transduction, odorants activate a cAMP-mediated signaling pathway that leads to the opening of cyclic nucleotide-gated (CNG), nonselective cation channels and depolarization. The Ca2+ influx through open CNG channels triggers an inward current through Ca2+-activated Cl channels (ANO2), which is expected to produce signal amplification. However, a study on an Ano2-/- mouse line reported no elevation in the behavioral threshold of odorant detection compared with wild type (WT). Subsequent studies by others on the same Ano2-/- line, nonetheless, found subtle defects in olfactory behavior and some abnormal axonal projections from the olfactory receptor neurons (ORNs) to the olfactory bulb. As such, the question regarding signal amplification by the Cl current in WT mouse remains unsettled. Recently, with suction-pipette recording, we have successfully separated in frog ORNs the CNG and Cl currents during olfactory transduction and found the Cl current to predominate in the response down to the threshold of action-potential signaling to the brain. For better comparison with the mouse data by others, we have now carried out similar current-separation experiments on mouse ORNs. We found that the Cl current clearly also predominated in the mouse olfactory response at signaling threshold, accounting for ∼80% of the response. In the absence of the Cl current, we expect the threshold stimulus to increase by approximately sevenfold.
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Neureither F, Stowasser N, Frings S, Möhrlen F. Tracking of unfamiliar odors is facilitated by signal amplification through anoctamin 2 chloride channels in mouse olfactory receptor neurons. Physiol Rep 2018; 5:5/15/e13373. [PMID: 28784854 PMCID: PMC5555898 DOI: 10.14814/phy2.13373] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Accepted: 07/10/2017] [Indexed: 12/22/2022] Open
Abstract
Many animals follow odor trails to find food, nesting sites, or mates, and they require only faint olfactory cues to do so. The performance of a tracking dog, for instance, poses the question on how the animal is able to distinguish a target odor from the complex chemical background around the trail. Current concepts of odor perception suggest that animals memorize each odor as an olfactory object, a percept that enables fast recognition of the odor and the interpretation of its valence. An open question still is how this learning process operates efficiently at the low odor concentrations that typically prevail when animals inspect an odor trail. To understand olfactory processing under these conditions, we studied the role of an amplification mechanism that boosts signal transduction at low stimulus intensities, a process mediated by calcium‐gated anoctamin 2 chloride channels. Genetically altered Ano2−/− mice, which lack these channels, display an impaired cue‐tracking behavior at low odor concentrations when challenged with an unfamiliar, but not with a familiar, odor. Moreover, recordings from the olfactory epithelium revealed that odor coding lacks sensitivity and temporal resolution in anoctamin 2‐deficient mice. Our results demonstrate that the detection of an unfamiliar, weak odor, as well as its memorization as an olfactory object, require signal amplification in olfactory receptor neurons. This process may contribute to the phenomenal tracking abilities of animals that follow odor trails.
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Affiliation(s)
- Franziska Neureither
- Department of Animal Molecular Physiology, Centre of Organismal Studies, Im Neuenheimer Feld 504, Heidelberg University, Heidelberg, Germany
| | - Nadine Stowasser
- Department of Animal Molecular Physiology, Centre of Organismal Studies, Im Neuenheimer Feld 504, Heidelberg University, Heidelberg, Germany
| | - Stephan Frings
- Department of Animal Molecular Physiology, Centre of Organismal Studies, Im Neuenheimer Feld 504, Heidelberg University, Heidelberg, Germany
| | - Frank Möhrlen
- Department of Animal Molecular Physiology, Centre of Organismal Studies, Im Neuenheimer Feld 504, Heidelberg University, Heidelberg, Germany
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Ben Khemis I, Mechi N, Ben Lamine A. Stereochemical study of mouse muscone receptor MOR215-1 and vibrational theory based on statistical physics formalism. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2018; 136:54-60. [PMID: 29438653 DOI: 10.1016/j.pbiomolbio.2018.02.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 02/02/2018] [Accepted: 02/09/2018] [Indexed: 11/29/2022]
Abstract
In the biosensor system, olfactory receptor sites could be activated by odorant molecules and then the biological interactions are converted into electrical signals by a signal transduction cascade that leads the toopening of ion channels, generating a current that leads into the cilia and depolarizes the membrane. The aim of this paper is to present a new investigation that allows determining the olfactory band using a monolayer adsorption with identical sites modeling which may also describe the static and the dynamic sensitivities through the expression of the olfactory response. Moreover, knowing the size of receptor site in olfactory sensory neurons provides valuable information about the relationship between molecular structure and biological activity. The determination of microreceptors and mesoreceptors is mostly carried out via physical adsorption and the radius is calculated using the Kelvin equation. The mean values of radius obtained from the maximum of the receptor size distributions peaks are 4 nm for ℓ-muscone and 6 nm for d-muscone.
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Affiliation(s)
- Ismahene Ben Khemis
- Laboratory of Quantum Physics UR 11 ES 54, Faculty of Sciences of Monastir, Environnement Street, 5019, Monastir, Tunisia.
| | - Nesrine Mechi
- Laboratory of Quantum Physics UR 11 ES 54, Faculty of Sciences of Monastir, Environnement Street, 5019, Monastir, Tunisia
| | - Abdelmottaleb Ben Lamine
- Laboratory of Quantum Physics UR 11 ES 54, Faculty of Sciences of Monastir, Environnement Street, 5019, Monastir, Tunisia.
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Wheeler LC, Harms MJ. Human S100A5 binds Ca 2+ and Cu 2+ independently. BMC BIOPHYSICS 2017; 10:8. [PMID: 29201357 PMCID: PMC5700546 DOI: 10.1186/s13628-017-0040-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 11/08/2017] [Indexed: 12/21/2022]
Abstract
Background S100A5 is a calcium binding protein found in a small subset of amniote tissues. Little is known about the biological roles of S100A5, but it may be involved in inflammation and olfactory signaling. Previous work indicated that S100A5 displays antagonism between binding of Ca2+ and Cu2+ ions-one of the most commonly cited features of the protein. We set out to characterize the interplay between Ca2+ and Cu2+ binding by S100A5 using isothermal titration calorimetry (ITC), circular dichroism spectroscopy (CD), and analytical ultracentrifugation (AUC). Results We found that human S100A5 is capable of binding both Cu2+ and Ca2+ ions simultaneously. The wildtype protein was extremely aggregation-prone in the presence of Cu2+ and Ca2+. A Cys-free version of S100A5, however, was not prone to precipitation or oligomerization. Mutation of the cysteines does not disrupt the binding of either Ca2+ or Cu2+ to S100A5. In the Cys-free background, we measured Ca2+ and Cu2+ binding in the presence and absence of the other metal using ITC. Saturating concentrations of Ca2+ or Cu2+ do not disrupt the binding of one another. Ca2+ and Cu2+ binding induce structural changes in S100A5, which are measurable using CD spectroscopy. We show via sedimentation velocity AUC that the wildtype protein is prone to the formation of soluble oligomers, which are not present in Cys-free samples. Conclusions S100A5 can bind Ca2+ and Cu2+ ions simultaneously and independently. This observation is in direct contrast to previously-reported antagonism between binding of Cu2+ and Ca2+ ions. The previous result is likely due to metal-dependent aggregation. Little is known about the biology of S100A5, so an accurate understanding of the biochemistry is necessary to make informed biological hypotheses. Our observations suggest the possibility of independent biological functions for Cu2+ and Ca2+ binding by S100A5.
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Affiliation(s)
- Lucas C Wheeler
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, 97403 OR USA.,Insitute of Molecular Biology, University of Oregon, Eugene, 97403 OR USA
| | - Michael J Harms
- Department of Chemistry and Biochemistry, University of Oregon, Eugene, 97403 OR USA.,Insitute of Molecular Biology, University of Oregon, Eugene, 97403 OR USA
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Simultaneous Loss of NCKX4 and CNG Channel Desensitization Impairs Olfactory Sensitivity. J Neurosci 2017; 37:110-119. [PMID: 28053034 DOI: 10.1523/jneurosci.2527-16.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 10/24/2016] [Accepted: 11/04/2016] [Indexed: 11/21/2022] Open
Abstract
In vertebrate olfactory sensory neurons (OSNs), Ca2+ plays key roles in both mediating and regulating the olfactory response. Ca2+ enters OSN cilia during the response through the olfactory cyclic nucleotide-gated (CNG) channel and stimulates a depolarizing chloride current by opening the olfactory Ca2+-activated chloride channel to amplify the response. Ca2+ also exerts negative regulation on the olfactory transduction cascade, through mechanisms that include reducing the CNG current by desensitizing the CNG channel via Ca2+/calmodulin (CaM), to reduce the response. Ca2+ is removed from the cilia primarily by the K+-dependent Na+/Ca2+ exchanger 4 (NCKX4), and the removal of Ca2+ leads to closure of the chloride channel and response termination. In this study, we investigate how two mechanisms conventionally considered negative regulatory mechanisms of olfactory transduction, Ca2+ removal by NCKX4, and desensitization of the CNG channel by Ca2+/CaM, interact to regulate the olfactory response. We performed electro-olfactogram (EOG) recordings on the double-mutant mice, NCKX4-/-;CNGB1ΔCaM, which are simultaneously lacking NCKX4 (NCKX4-/-) and Ca2+/CaM-mediated CNG channel desensitization (CNGB1ΔCaM). Despite exhibiting alterations in various response attributes, including termination kinetics and adaption properties, OSNs in either NCKX4-/- mice or CNGB1ΔCaM mice show normal resting sensitivity, as determined by their unchanged EOG response amplitude. We found that OSNs in NCKX4-/-;CNGB1ΔCaM mice displayed markedly reduced EOG amplitude accompanied by alterations in other response attributes. This study suggests that what are conventionally considered negative regulatory mechanisms of olfactory transduction also play a role in setting the resting sensitivity in OSNs. SIGNIFICANCE STATEMENT Sensory receptor cells maintain high sensitivity at rest. Although the mechanisms responsible for setting the resting sensitivity of sensory receptor cells are not well understood, it has generally been assumed that the sensitivity is set primarily by how effectively the components in the activation cascade of sensory transduction can be stimulated. Our findings in mouse olfactory sensory neurons suggest that mechanisms that are primarily responsible for terminating the olfactory response are also critical for proper resting sensitivity.
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Hahn A, Faulhaber J, Srisawang L, Stortz A, Salomon JJ, Mall MA, Frings S, Möhrlen F. Cellular distribution and function of ion channels involved in transport processes in rat tracheal epithelium. Physiol Rep 2017; 5:e13290. [PMID: 28642338 PMCID: PMC5492199 DOI: 10.14814/phy2.13290] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 04/26/2017] [Accepted: 04/27/2017] [Indexed: 01/17/2023] Open
Abstract
Transport of water and electrolytes in airway epithelia involves chloride-selective ion channels, which are controlled either by cytosolic Ca2+ or by cAMP The contributions of the two pathways to chloride transport differ among vertebrate species. Because rats are becoming more important as animal model for cystic fibrosis, we have examined how Ca2+- dependent and cAMP- dependent Cl- secretion is organized in the rat tracheal epithelium. We examined the expression of the Ca2+-gated Cl- channel anoctamin 1 (ANO1), the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel, the epithelial Na+ channel ENaC, and the water channel aquaporin 5 (AQP5) in rat tracheal epithelium. The contribution of ANO1 channels to nucleotide-stimulated Cl- secretion was determined using the channel blocker Ani9 in short-circuit current recordings obtained from primary cultures of rat tracheal epithelial cells in Ussing chambers. We found that ANO1, CFTR and AQP5 proteins were expressed in nonciliated cells of the tracheal epithelium, whereas ENaC was expressed in ciliated cells. Among nonciliated cells, ANO1 occurred together with CFTR and Muc5b and, in addition, in a different cell type without CFTR and Muc5b. Bioelectrical studies with the ANO1-blocker Ani9 indicated that ANO1 mediated the secretory response to the nucleotide uridine-5'-triphosphate. Our data demonstrate that, in rat tracheal epithelium, Cl- secretion and Na+ absorption are routed through different cell types, and that ANO1 channels form the molecular basis of Ca2+-dependent Cl- secretion in this tissue. These characteristic features of Cl--dependent secretion reveal similarities and distinct differences to secretory processes in human airways.
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Affiliation(s)
- Anne Hahn
- Department of Animal Molecular Physiology, Centre of Organismal Studies University of Heidelberg, Heidelberg, Germany
| | - Johannes Faulhaber
- Department of Animal Molecular Physiology, Centre of Organismal Studies University of Heidelberg, Heidelberg, Germany
| | - Lalita Srisawang
- Department of Animal Molecular Physiology, Centre of Organismal Studies University of Heidelberg, Heidelberg, Germany
| | - Andreas Stortz
- Department of Animal Molecular Physiology, Centre of Organismal Studies University of Heidelberg, Heidelberg, Germany
| | - Johanna J Salomon
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC) German Center for Lung Research (DZL) University of Heidelberg, Heidelberg, Germany
| | - Marcus A Mall
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC) German Center for Lung Research (DZL) University of Heidelberg, Heidelberg, Germany
| | - Stephan Frings
- Department of Animal Molecular Physiology, Centre of Organismal Studies University of Heidelberg, Heidelberg, Germany
| | - Frank Möhrlen
- Department of Animal Molecular Physiology, Centre of Organismal Studies University of Heidelberg, Heidelberg, Germany
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Dibattista M, Pifferi S, Boccaccio A, Menini A, Reisert J. The long tale of the calcium activated Cl - channels in olfactory transduction. Channels (Austin) 2017; 11:399-414. [PMID: 28301269 DOI: 10.1080/19336950.2017.1307489] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Ca2+-activated Cl- currents have been implicated in many cellular processes in different cells, but for many years, their molecular identity remained unknown. Particularly intriguing are Ca2+-activated Cl- currents in olfactory transduction, first described in the early 90s. Well characterized electrophysiologically, they carry most of the odorant-induced receptor current in the cilia of olfactory sensory neurons (OSNs). After many attempts to determine their molecular identity, TMEM16B was found to be abundantly expressed in the cilia of OSNs in 2009 and having biophysical properties like those of the native olfactory channel. A TMEM16B knockout mouse confirmed that TMEM16B was indeed the olfactory Cl- channel but also suggested a limited role in olfactory physiology and behavior. The question then arises of what the precise role of TMEM16b in olfaction is. Here we review the long story of this channel and its possible roles.
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Affiliation(s)
- Michele Dibattista
- a Department of Basic Medical Sciences, Neuroscience and Sensory Organs , University of Bari A. Moro , Bari , Italy
| | - Simone Pifferi
- b Neurobiology Group, SISSA, Scuola Internazionale Superiore di Studi Avanzati , Trieste , Italy
| | | | - Anna Menini
- b Neurobiology Group, SISSA, Scuola Internazionale Superiore di Studi Avanzati , Trieste , Italy
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Bigdaj EV, Fufachev DK, Petrov PR, Samojlov VO. Mechanisms of electromechanical and electrochemical coupling in olfactory cilia of the frog (Rana temporaria). Biophysics (Nagoya-shi) 2017. [DOI: 10.1134/s0006350917020051] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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25
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Cyclic-nucleotide-gated cation current and Ca2+-activated Cl current elicited by odorant in vertebrate olfactory receptor neurons. Proc Natl Acad Sci U S A 2016; 113:11078-11087. [PMID: 27647918 DOI: 10.1073/pnas.1613891113] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Olfactory transduction in vertebrate olfactory receptor neurons (ORNs) involves primarily a cAMP-signaling cascade that leads to the opening of cyclic-nucleotide-gated (CNG), nonselective cation channels. The consequent Ca2+ influx triggers adaptation but also signal amplification, the latter by opening a Ca2+-activated Cl channel (ANO2) to elicit, unusually, an inward Cl current. Hence the olfactory response has inward CNG and Cl components that are in rapid succession and not easily separable. We report here success in quantitatively separating these two currents with respect to amplitude and time course over a broad range of odorant strengths. Importantly, we found that the Cl current is the predominant component throughout the olfactory dose-response relation, down to the threshold of signaling to the brain. This observation is very surprising given a recent report by others that the olfactory-signal amplification effected by the Ca2+-activated Cl current does not influence the behavioral olfactory threshold in mice.
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26
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Pietra G, Dibattista M, Menini A, Reisert J, Boccaccio A. The Ca2+-activated Cl- channel TMEM16B regulates action potential firing and axonal targeting in olfactory sensory neurons. J Gen Physiol 2016; 148:293-311. [PMID: 27619419 PMCID: PMC5037344 DOI: 10.1085/jgp.201611622] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 08/08/2016] [Indexed: 02/05/2023] Open
Abstract
TMEM16B is expressed in olfactory sensory neurons, but previous attempts to establish a physiological role in olfaction have been unsuccessful. Pietra et al. find that genetic ablation of TMEM16B results in defects in the olfactory behavior of mice and the cellular physiology of olfactory sensory neurons. The Ca2+-activated Cl− channel TMEM16B is highly expressed in the cilia of olfactory sensory neurons (OSNs). Although a large portion of the odor-evoked transduction current is carried by Ca2+-activated Cl− channels, their role in olfaction is still controversial. A previous report (Billig et al. 2011. Nat. Neurosci.http://dx.doi.org/10.1038/nn.2821) showed that disruption of the TMEM16b/Ano2 gene in mice abolished Ca2+-activated Cl− currents in OSNs but did not produce any major change in olfactory behavior. Here we readdress the role of TMEM16B in olfaction and show that TMEM16B knockout (KO) mice have behavioral deficits in odor-guided food-finding ability. Moreover, as the role of TMEM16B in action potential (AP) firing has not yet been studied, we use electrophysiological recording methods to measure the firing activity of OSNs. Suction electrode recordings from isolated olfactory neurons and on-cell loose-patch recordings from dendritic knobs of neurons in the olfactory epithelium show that randomly selected neurons from TMEM16B KO mice respond to stimulation with increased firing activity than those from wild-type (WT) mice. Because OSNs express different odorant receptors (ORs), we restrict variability by using a mouse line that expresses a GFP-tagged I7 OR, which is known to be activated by heptanal. In response to heptanal, we measure dramatic changes in the firing pattern of I7-expressing neurons from TMEM16B KO mice compared with WT: responses are prolonged and display a higher number of APs. Moreover, lack of TMEM16B causes a markedly reduced basal spiking activity in I7-expressing neurons, together with an alteration of axonal targeting to the olfactory bulb, leading to the appearance of supernumerary I7 glomeruli. Thus, TMEM16B controls AP firing and ensures correct glomerular targeting of OSNs expressing I7. Altogether, these results show that TMEM16B does have a relevant role in normal olfaction.
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Affiliation(s)
- Gianluca Pietra
- Neurobiology Group, International School for Advanced Studies (SISSA), 34136 Trieste, Italy
| | | | - Anna Menini
- Neurobiology Group, International School for Advanced Studies (SISSA), 34136 Trieste, Italy
| | | | - Anna Boccaccio
- Institute of Biophysics, National Research Council (CNR), 16149 Genova, Italy
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Untiet V, Moeller LM, Ibarra-Soria X, Sánchez-Andrade G, Stricker M, Neuhaus EM, Logan DW, Gensch T, Spehr M. Elevated Cytosolic Cl- Concentrations in Dendritic Knobs of Mouse Vomeronasal Sensory Neurons. Chem Senses 2016; 41:669-76. [PMID: 27377750 DOI: 10.1093/chemse/bjw077] [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: 12/21/2022] Open
Abstract
In rodents, the vomeronasal system controls social and sexual behavior. However, several mechanistic aspects of sensory signaling in the vomeronasal organ remain unclear. Here, we investigate the biophysical basis of a recently proposed vomeronasal signal transduction component-a Ca(2+)-activated Cl(-) current. As the physiological role of such a current is a direct function of the Cl(-) equilibrium potential, we determined the intracellular Cl(-) concentration in dendritic knobs of vomeronasal neurons. Quantitative fluorescence lifetime imaging of a Cl(-)-sensitive dye at the apical surface of the intact vomeronasal neuroepithelium revealed increased cytosolic Cl(-) levels in dendritic knobs, a substantially lower Cl(-) concentration in vomeronasal sustentacular cells, and an apparent Cl(-) gradient in vomeronasal neurons along their dendritic apicobasal axis. Together, our data provide a biophysical basis for sensory signal amplification in vomeronasal neuron microvilli by opening Ca(2+)-activated Cl(-) channels.
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Affiliation(s)
- Verena Untiet
- Institute of Complex Systems, Cellular Biophysics (ICS-4), Forschungszentrum Jülich, Leo-Brandt-Straße, D-52428 Jülich, Germany
| | - Lisa M Moeller
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, Worringerweg 3, D-52074 Aachen, Germany
| | - Ximena Ibarra-Soria
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK
| | | | - Miriam Stricker
- Institute of Complex Systems, Cellular Biophysics (ICS-4), Forschungszentrum Jülich, Leo-Brandt-Straße, D-52428 Jülich, Germany
| | - Eva M Neuhaus
- Pharmacology and Toxicology, University Hospital Jena, Drackendorfer Straße 1, Friedrich Schiller University Jena, D-07743 Jena, Germany and
| | - Darren W Logan
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SA, UK, Monell Chemical Senses Center, 3500 Market Street, Philadelphia, PA 19104, USA
| | - Thomas Gensch
- Institute of Complex Systems, Cellular Biophysics (ICS-4), Forschungszentrum Jülich, Leo-Brandt-Straße, D-52428 Jülich, Germany
| | - Marc Spehr
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, Worringerweg 3, D-52074 Aachen, Germany,
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Meyer SA, Ozbay BN, Potcoava M, Salcedo E, Restrepo D, Gibson EA. Super-resolution imaging of ciliary microdomains in isolated olfactory sensory neurons using a custom two-color stimulated emission depletion microscope. JOURNAL OF BIOMEDICAL OPTICS 2016; 21:66017. [PMID: 27367253 PMCID: PMC4923803 DOI: 10.1117/1.jbo.21.6.066017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 06/03/2016] [Indexed: 06/06/2023]
Abstract
We performed stimulated emission depletion (STED) imaging of isolated olfactory sensory neurons (OSNs) using a custom-built microscope. The STED microscope uses a single pulsed laser to excite two separate fluorophores, Atto 590 and Atto 647N. A gated timing circuit combined with temporal interleaving of the different color excitation/STED laser pulses filters the two channel detection and greatly minimizes crosstalk. We quantified the instrument resolution to be ∼81 and ∼44 nm, for the Atto 590 and Atto 647N channels. The spatial separation between the two channels was measured to be under 10 nm, well below the resolution limit. The custom-STED microscope is incorporated onto a commercial research microscope allowing brightfield, differential interference contrast, and epifluorescence imaging on the same field of view. We performed immunolabeling of OSNs in mice to image localization of ciliary membrane proteins involved in olfactory transduction. We imaged Ca2+-permeable cyclic nucleotide gated (CNG) channel (Atto 594) and adenylyl cyclase type III (ACIII) (Atto 647N) in distinct cilia. STED imaging resolved well-separated subdiffraction limited clusters for each protein. We quantified the size of each cluster to have a mean value of 88±48 nm and 124±43 nm, for CNG and ACIII, respectively. STED imaging showed separated clusters that were not resolvable in confocal images.
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Affiliation(s)
- Stephanie A. Meyer
- University of Colorado Denver Anschutz Medical Campus, Department of Bioengineering, MS 8607, 12700 East 19th Avenue, Aurora, Colorado 80045-2560, United States
| | - Baris N. Ozbay
- University of Colorado Denver Anschutz Medical Campus, Department of Bioengineering, MS 8607, 12700 East 19th Avenue, Aurora, Colorado 80045-2560, United States
| | - Mariana Potcoava
- University of Colorado Denver Anschutz Medical Campus, Department of Bioengineering, MS 8607, 12700 East 19th Avenue, Aurora, Colorado 80045-2560, United States
| | - Ernesto Salcedo
- University of Colorado Denver Anschutz Medical Campus, Department of Cell and Developmental Biology, MS 8108, 12801 East 17th Avenue, Aurora, Colorado 80045-2560, United States
| | - Diego Restrepo
- University of Colorado Denver Anschutz Medical Campus, Department of Cell and Developmental Biology, MS 8108, 12801 East 17th Avenue, Aurora, Colorado 80045-2560, United States
| | - Emily A. Gibson
- University of Colorado Denver Anschutz Medical Campus, Department of Bioengineering, MS 8607, 12700 East 19th Avenue, Aurora, Colorado 80045-2560, United States
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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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Intracellular chloride concentration of the mouse vomeronasal neuron. BMC Neurosci 2015; 16:90. [PMID: 26667019 PMCID: PMC4678706 DOI: 10.1186/s12868-015-0230-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Accepted: 12/03/2015] [Indexed: 12/23/2022] Open
Abstract
Background The vomeronasal organ (VNO) is specialized in detecting pheromone and heterospecific cues in the environment. Recent studies demonstrate the involvement of multiple ion channels in VNO signal transduction, including the calcium-activated chloride channels (CACCs). Opening of CACCs appears to result in activation of VNO neuron through outflow of Cl− ions. However, the intracellular Cl− concentration remains undetermined. Results We used the chloride ion quenching dye, MQAE, to measure the intracellular Cl− concentration of VNO neuron in live VNO slices. The resting Cl− concentration in the VNO neurons is measured at 84.73 mM. Urine activation of the VNO neurons causes a drop in Cl− concentration, consistent with the notion of an efflux of Cl− to depolarize the cells. Similar observation is made for VNO neurons from mice with deletion of the transient receptor potential canonical channel 2 (TRPC2), which have a resting Cl− concentrations at 81 mM. Conclusions The VNO neurons rest at high intracellular Cl− concentration, which can lead to depolarization of the cell when chloride channels open. These results also provide additional support of TRPC2-independent pathway of VNO activation.
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Jansen F, Kalbe B, Scholz P, Mikosz M, Wunderlich KA, Kurtenbach S, Nagel-Wolfrum K, Wolfrum U, Hatt H, Osterloh S. Impact of the Usher syndrome on olfaction. Hum Mol Genet 2015; 25:524-33. [PMID: 26620972 DOI: 10.1093/hmg/ddv490] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 11/24/2015] [Indexed: 12/21/2022] Open
Abstract
Usher syndrome is a genetically and clinically heterogeneous disease in humans, characterized by sensorineural hearing loss, retinitis pigmentosa and vestibular dysfunction. This disease is caused by mutations in genes encoding proteins that form complex networks in different cellular compartments. Currently, it remains unclear whether the Usher proteins also form networks within the olfactory epithelium (OE). Here, we describe Usher gene expression at the mRNA and protein level in the OE of mice and showed interactions between these proteins and olfactory signaling proteins. Additionally, we analyzed the odor sensitivity of different Usher syndrome mouse models using electro-olfactogram recordings and monitored significant changes in the odor detection capabilities in mice expressing mutant Usher proteins. Furthermore, we observed changes in the expression of signaling proteins that might compensate for the Usher protein deficiency. In summary, this study provides novel insights into the presence and purpose of the Usher proteins in olfactory signal transduction.
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Affiliation(s)
- Fabian Jansen
- Cell Physiology, Faculty for Biology and Biotechnology, Ruhr-University Bochum, 44801 Bochum, Germany and
| | - Benjamin Kalbe
- Cell Physiology, Faculty for Biology and Biotechnology, Ruhr-University Bochum, 44801 Bochum, Germany and
| | - Paul Scholz
- Cell Physiology, Faculty for Biology and Biotechnology, Ruhr-University Bochum, 44801 Bochum, Germany and
| | - Marta Mikosz
- Cell and Matrix Biology, Institute of Zoology, Johannes Gutenberg-University, 55099 Mainz, Germany
| | - Kirsten A Wunderlich
- Cell and Matrix Biology, Institute of Zoology, Johannes Gutenberg-University, 55099 Mainz, Germany
| | - Stefan Kurtenbach
- Cell Physiology, Faculty for Biology and Biotechnology, Ruhr-University Bochum, 44801 Bochum, Germany and
| | - Kerstin Nagel-Wolfrum
- Cell and Matrix Biology, Institute of Zoology, Johannes Gutenberg-University, 55099 Mainz, Germany
| | - Uwe Wolfrum
- Cell and Matrix Biology, Institute of Zoology, Johannes Gutenberg-University, 55099 Mainz, Germany
| | - Hanns Hatt
- Cell Physiology, Faculty for Biology and Biotechnology, Ruhr-University Bochum, 44801 Bochum, Germany and
| | - Sabrina Osterloh
- Cell Physiology, Faculty for Biology and Biotechnology, Ruhr-University Bochum, 44801 Bochum, Germany and
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Affiliation(s)
- Anne Tromelin
- CNRS; UMR6265 Centre des Sciences du Goût et de l'Alimentation; F-21000 Dijon France
- INRA; UMR1324 Centre des Sciences du Goût et de l'Alimentation; F-21000 Dijon France
- Université de Bourgogne; UMR Centre des Sciences du Goût et de l'Alimentation; F-21000 Dijon France
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Zhang W, Schmelzeisen S, Parthier D, Frings S, Möhrlen F. Anoctamin Calcium-Activated Chloride Channels May Modulate Inhibitory Transmission in the Cerebellar Cortex. PLoS One 2015; 10:e0142160. [PMID: 26558388 PMCID: PMC4641602 DOI: 10.1371/journal.pone.0142160] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 10/19/2015] [Indexed: 01/18/2023] Open
Abstract
Calcium-activated chloride channels of the anoctamin (alias TMEM16) protein family fulfill critical functions in epithelial fluid transport, smooth muscle contraction and sensory signal processing. Little is known, however, about their contribution to information processing in the central nervous system. Here we examined the recent finding that a calcium-dependent chloride conductance impacts on GABAergic synaptic inhibition in Purkinje cells of the cerebellum. We asked whether anoctamin channels may underlie this chloride conductance. We identified two anoctamin channel proteins, ANO1 and ANO2, in the cerebellar cortex. ANO1 was expressed in inhibitory interneurons of the molecular layer and the granule cell layer. Both channels were expressed in Purkinje cells but, while ANO1 appeared to be retained in the cell body, ANO2 was targeted to the dendritic tree. Functional studies confirmed that ANO2 was involved in a calcium-dependent mode of ionic plasticity that reduces the efficacy of GABAergic synapses. ANO2 channels attenuated GABAergic transmission by increasing the postsynaptic chloride concentration, hence reducing the driving force for chloride influx. Our data suggest that ANO2 channels are involved in a Ca2+-dependent regulation of synaptic weight in GABAergic inhibition. Thus, in balance with the chloride extrusion mechanism via the co-transporter KCC2, ANO2 appears to regulate ionic plasticity in the cerebellum.
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Affiliation(s)
- Weiping Zhang
- Department of Animal Molecular Physiology, Centre of Organismal Studies, Im Neuenheimer Feld 504, Heidelberg University, Heidelberg, Germany
| | - Steffen Schmelzeisen
- Department of Animal Molecular Physiology, Centre of Organismal Studies, Im Neuenheimer Feld 504, Heidelberg University, Heidelberg, Germany
| | - Daniel Parthier
- Department of Animal Molecular Physiology, Centre of Organismal Studies, Im Neuenheimer Feld 504, Heidelberg University, Heidelberg, Germany
| | - Stephan Frings
- Department of Animal Molecular Physiology, Centre of Organismal Studies, Im Neuenheimer Feld 504, Heidelberg University, Heidelberg, Germany
| | - Frank Möhrlen
- Department of Animal Molecular Physiology, Centre of Organismal Studies, Im Neuenheimer Feld 504, Heidelberg University, Heidelberg, Germany
- * E-mail:
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Ullah G, Demuro A, Parker I, Pearson JE. Analyzing and Modeling the Kinetics of Amyloid Beta Pores Associated with Alzheimer's Disease Pathology. PLoS One 2015; 10:e0137357. [PMID: 26348728 PMCID: PMC4562663 DOI: 10.1371/journal.pone.0137357] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Accepted: 08/14/2015] [Indexed: 11/24/2022] Open
Abstract
Amyloid beta (Aβ) oligomers associated with Alzheimer’s disease (AD) form Ca2+-permeable plasma membrane pores, leading to a disruption of the otherwise well-controlled intracellular calcium (Ca2+) homeostasis. The resultant up-regulation of intracellular Ca2+ concentration has detrimental implications for memory formation and cell survival. The gating kinetics and Ca2+ permeability of Aβ pores are not well understood. We have used computational modeling in conjunction with the ability of optical patch-clamping for massively parallel imaging of Ca2+ flux through thousands of pores in the cell membrane of Xenopus oocytes to elucidate the kinetic properties of Aβ pores. The fluorescence time-series data from individual pores were idealized and used to develop data-driven Markov chain models for the kinetics of the Aβ pore at different stages of its evolution. Our study provides the first demonstration of developing Markov chain models for ion channel gating that are driven by optical-patch clamp data with the advantage of experiments being performed under close to physiological conditions. Towards the end, we demonstrate the up-regulation of gating of various Ca2+ release channels due to Aβ pores and show that the extent and spatial range of such up-regulation increases as Aβ pores with low open probability and Ca2+ permeability transition into those with high open probability and Ca2+ permeability.
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Affiliation(s)
- Ghanim Ullah
- Department of Physics, University of South Florida, Tampa, FL 33620, United States of America
- * E-mail:
| | - Angelo Demuro
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, CA 92697, United States of America
| | - Ian Parker
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, CA 92697, United States of America
| | - John E. Pearson
- Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos, NM 87545, United States of America
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Matchkov VV, Boedtkjer DM, Aalkjaer C. The role of Ca2+ activated Cl− channels in blood pressure control. Curr Opin Pharmacol 2015; 21:127-37. [DOI: 10.1016/j.coph.2015.02.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 02/02/2015] [Accepted: 02/04/2015] [Indexed: 12/17/2022]
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Amjad A, Hernandez-Clavijo A, Pifferi S, Maurya DK, Boccaccio A, Franzot J, Rock J, Menini A. Conditional knockout of TMEM16A/anoctamin1 abolishes the calcium-activated chloride current in mouse vomeronasal sensory neurons. ACTA ACUST UNITED AC 2015; 145:285-301. [PMID: 25779870 PMCID: PMC4380210 DOI: 10.1085/jgp.201411348] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
TMEM16A is an essential component of Ca2+-activated Cl− currents in mouse vomeronasal sensory neurons. Pheromones are substances released from animals that, when detected by the vomeronasal organ of other individuals of the same species, affect their physiology and behavior. Pheromone binding to receptors on microvilli on the dendritic knobs of vomeronasal sensory neurons activates a second messenger cascade to produce an increase in intracellular Ca2+ concentration. Here, we used whole-cell and inside-out patch-clamp analysis to provide a functional characterization of currents activated by Ca2+ in isolated mouse vomeronasal sensory neurons in the absence of intracellular K+. In whole-cell recordings, the average current in 1.5 µM Ca2+ and symmetrical Cl− was −382 pA at −100 mV. Ion substitution experiments and partial blockade by commonly used Cl− channel blockers indicated that Ca2+ activates mainly anionic currents in these neurons. Recordings from inside-out patches from dendritic knobs of mouse vomeronasal sensory neurons confirmed the presence of Ca2+-activated Cl− channels in the knobs and/or microvilli. We compared the electrophysiological properties of the native currents with those mediated by heterologously expressed TMEM16A/anoctamin1 or TMEM16B/anoctamin2 Ca2+-activated Cl− channels, which are coexpressed in microvilli of mouse vomeronasal sensory neurons, and found a closer resemblance to those of TMEM16A. We used the Cre–loxP system to selectively knock out TMEM16A in cells expressing the olfactory marker protein, which is found in mature vomeronasal sensory neurons. Immunohistochemistry confirmed the specific ablation of TMEM16A in vomeronasal neurons. Ca2+-activated currents were abolished in vomeronasal sensory neurons of TMEM16A conditional knockout mice, demonstrating that TMEM16A is an essential component of Ca2+-activated Cl− currents in mouse vomeronasal sensory neurons.
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Affiliation(s)
- Asma Amjad
- Neurobiology Group, SISSA, Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy
| | - Andres Hernandez-Clavijo
- Neurobiology Group, SISSA, Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy
| | - Simone Pifferi
- Neurobiology Group, SISSA, Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy
| | - Devendra Kumar Maurya
- Neurobiology Group, SISSA, Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy
| | - Anna Boccaccio
- Istituto di Biofisica, National Research Council, 16149 Genova, Italy
| | - Jessica Franzot
- Neurobiology Group, SISSA, Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy
| | - Jason Rock
- Department of Anatomy, University of California, San Francisco, School of Medicine, San Francisco, CA 94143
| | - Anna Menini
- Neurobiology Group, SISSA, Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy
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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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Olfactory Signaling in Insects. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 130:37-54. [DOI: 10.1016/bs.pmbts.2014.11.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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40
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Henkel B, Drose DR, Ackels T, Oberland S, Spehr M, Neuhaus EM. Co-expression of anoctamins in cilia of olfactory sensory neurons. Chem Senses 2014; 40:73-87. [PMID: 25500808 DOI: 10.1093/chemse/bju061] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Vertebrates can sense and identify a vast array of chemical cues. The molecular machinery involved in chemodetection and transduction is expressed within the cilia of olfactory sensory neurons. Currently, there is only limited information available on the distribution and density of individual signaling components within the ciliary compartment. Using super-resolution microscopy, we show here that cyclic-nucleotide-gated channels and calcium-activated chloride channels of the anoctamin family are localized to discrete microdomains in the ciliary membrane. In addition to ANO2, a second anoctamin, ANO6, also localizes to ciliary microdomains. This observation, together with the fact that ANO6 and ANO2 co-localize, indicates a role for ANO6 in olfactory signaling. We show that both ANO2 and ANO6 can form heteromultimers and that this heteromerization alters the recombinant channels' physiological properties. Thus, we provide evidence for interaction of ANO2 and ANO6 in olfactory cilia, with possible physiological relevance for olfactory signaling.
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Affiliation(s)
- Bastian Henkel
- Department of Pharmacology and Toxicology, University Hospital Jena, Drackendorfer Strasse 1, 07747 Jena, Germany, Cluster of Excellence NeuroCure, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany, FU Berlin, Fachbereich Biologie, Chemie und Pharmazie , Takustr. 3, 14195 Berlin, Germany and
| | - Daniela R Drose
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, Worringerweg 3, 52074 Aachen, Germany
| | - Tobias Ackels
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, Worringerweg 3, 52074 Aachen, Germany
| | - Sonja Oberland
- Department of Pharmacology and Toxicology, University Hospital Jena, Drackendorfer Strasse 1, 07747 Jena, Germany, Cluster of Excellence NeuroCure, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany, FU Berlin, Fachbereich Biologie, Chemie und Pharmazie , Takustr. 3, 14195 Berlin, Germany and
| | - Marc Spehr
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, Worringerweg 3, 52074 Aachen, Germany
| | - Eva M Neuhaus
- Department of Pharmacology and Toxicology, University Hospital Jena, Drackendorfer Strasse 1, 07747 Jena, Germany, Cluster of Excellence NeuroCure, Charité-Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany,
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Lam K, Conley DB, Liu K, Kern RC, Tan BK, Richter CP. Effect of ionic compositions in nasal irrigations on human olfactory thresholds. Laryngoscope 2014; 125:E50-6. [PMID: 25267347 DOI: 10.1002/lary.24941] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 08/13/2014] [Accepted: 09/02/2014] [Indexed: 11/09/2022]
Abstract
OBJECTIVES/HYPOTHESIS Nasal irrigations are commonly employed to promote nasal hygiene in the treatment of various sinonasal conditions. Few studies have evaluated how the ionic composition of irrigation solutions affects olfactory performance. The purpose of this study was to determine the dose responsiveness of human olfactory thresholds for each of the following ions: potassium, sodium, and calcium. STUDY DESIGN Prospective translational study. METHODS Irrigation solutions with variable potassium, sodium, and calcium were tested in 25 healthy human participants. Six potassium concentrations (range, 2-10 mM), six sodium concentrations (range, 73.7-113.7 mM), and three calcium concentrations (range, 0.44-0.64 mM) were used. Before and immediately following irrigations, olfactory thresholds were determined using the Sniffin' Sticks test. Differences in olfactory threshold scores before and after irrigations were compared to assess the effect of ionic composition on olfactory sensitivity. RESULTS Physiologic concentrations of potassium, sodium, and calcium at 5.7, 89.5, and 0.54 mM, respectively, did not significantly change olfactory thresholds. Variations in both potassium and sodium concentrations demonstrated statistically significant dose-dependent elevations in olfactory thresholds (P < .05). Only the calcium concentration that was lower than the physiologic level led to significant elevations in olfactory thresholds. CONCLUSIONS Different potassium and sodium concentrations in irrigation solutions provide distinctive dose-dependent shifts in olfactory thresholds. Calcium concentrations also elevate olfactory thresholds, but calcium plays a less significant role than potassium and sodium in modulating olfactory thresholds. These results highlight the importance of the intranasal ionic microenvironment in olfactory physiology and suggest that optimal ionic concentrations in irrigation solutions exist to preserve olfactory function. LEVEL OF EVIDENCE NA.
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Affiliation(s)
- Kent Lam
- Department of Otolaryngology-Head and Neck Surgery, Northwestern University Feinberg School of Medicine, Chicago
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42
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Antunes G, Sebastião AM, Simoes de Souza FM. Mechanisms of regulation of olfactory transduction and adaptation in the olfactory cilium. PLoS One 2014; 9:e105531. [PMID: 25144232 PMCID: PMC4140790 DOI: 10.1371/journal.pone.0105531] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 07/23/2014] [Indexed: 12/11/2022] Open
Abstract
Olfactory adaptation is a fundamental process for the functioning of the olfactory system, but the underlying mechanisms regulating its occurrence in intact olfactory sensory neurons (OSNs) are not fully understood. In this work, we have combined stochastic computational modeling and a systematic pharmacological study of different signaling pathways to investigate their impact during short-term adaptation (STA). We used odorant stimulation and electroolfactogram (EOG) recordings of the olfactory epithelium treated with pharmacological blockers to study the molecular mechanisms regulating the occurrence of adaptation in OSNs. EOG responses to paired-pulses of odorants showed that inhibition of phosphodiesterases (PDEs) and phosphatases enhanced the levels of STA in the olfactory epithelium, and this effect was mimicked by blocking vesicle exocytosis and reduced by blocking cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) and vesicle endocytosis. These results suggest that G-coupled receptors (GPCRs) cycling is involved with the occurrence of STA. To gain insights on the dynamical aspects of this process, we developed a stochastic computational model. The model consists of the olfactory transduction currents mediated by the cyclic nucleotide gated (CNG) channels and calcium ion (Ca2+)-activated chloride (CAC) channels, and the dynamics of their respective ligands, cAMP and Ca2+, and it simulates the EOG results obtained under different experimental conditions through changes in the amplitude and duration of cAMP and Ca2+ response, two second messengers implicated with STA occurrence. The model reproduced the experimental data for each pharmacological treatment and provided a mechanistic explanation for the action of GPCR cycling in the levels of second messengers modulating the levels of STA. All together, these experimental and theoretical results indicate the existence of a mechanism of regulation of STA by signaling pathways that control GPCR cycling and tune the levels of second messengers in OSNs, and not only by CNG channel desensitization as previously thought.
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Affiliation(s)
- Gabriela Antunes
- Neurosciences Unit, Institute of Molecular Medicine, University of Lisbon, Lisbon, Portugal; Laboratory of Neural Systems, Psychobiology Sector, Department of Psychology, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - Ana Maria Sebastião
- Institute of Pharmacology and Neurosciences, Faculty of Medicine, University of Lisbon, Lisbon, Portugal; Neurosciences Unit, Institute of Molecular Medicine, University of Lisbon, Lisbon, Portugal
| | - Fabio Marques Simoes de Souza
- Neurosciences Unit, Institute of Molecular Medicine, University of Lisbon, Lisbon, Portugal; Center for Mathematics, Computation and Cognition, Federal University of ABC, São Bernardo do Campo, Brazil
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43
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Vocke K, Dauner K, Hahn A, Ulbrich A, Broecker J, Keller S, Frings S, Möhrlen F. Calmodulin-dependent activation and inactivation of anoctamin calcium-gated chloride channels. ACTA ACUST UNITED AC 2014; 142:381-404. [PMID: 24081981 PMCID: PMC3787769 DOI: 10.1085/jgp.201311015] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Calcium-dependent chloride channels serve critical functions in diverse biological systems. Driven by cellular calcium signals, the channels codetermine excitatory processes and promote solute transport. The anoctamin (ANO) family of membrane proteins encodes three calcium-activated chloride channels, named ANO 1 (also TMEM16A), ANO 2 (also TMEM16B), and ANO 6 (also TMEM16F). Here we examined how ANO 1 and ANO 2 interact with Ca2+/calmodulin using nonstationary current analysis during channel activation. We identified a putative calmodulin-binding domain in the N-terminal region of the channel proteins that is involved in channel activation. Binding studies with peptides indicated that this domain, a regulatory calmodulin-binding motif (RCBM), provides two distinct modes of interaction with Ca2+/calmodulin, one at submicromolar Ca2+ concentrations and one in the micromolar Ca2+ range. Functional, structural, and pharmacological data support the concept that calmodulin serves as a calcium sensor that is stably associated with the RCBM domain and regulates the activation of ANO 1 and ANO 2 channels. Moreover, the predominant splice variant of ANO 2 in the brain exhibits Ca2+/calmodulin-dependent inactivation, a loss of channel activity within 30 s. This property may curtail ANO 2 activity during persistent Ca2+ signals in neurons. Mutagenesis data indicated that the RCBM domain is also involved in ANO 2 inactivation, and that inactivation is suppressed in the retinal ANO 2 splice variant. These results advance the understanding of Ca2+ regulation in anoctamin Cl− channels and its significance for the physiological function that anoctamin channels subserve in neurons and other cell types.
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Affiliation(s)
- Kerstin Vocke
- Department of Molecular Physiology, Centre for Organismal Studies, Heidelberg University, 69120 Heidelberg, Germany
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Kuhlmann K, Tschapek A, Wiese H, Eisenacher M, Meyer HE, Hatt HH, Oeljeklaus S, Warscheid B. The membrane proteome of sensory cilia to the depth of olfactory receptors. Mol Cell Proteomics 2014; 13:1828-43. [PMID: 24748648 DOI: 10.1074/mcp.m113.035378] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the nasal cavity, the nonmotile cilium of olfactory sensory neurons (OSNs) constitutes the chemosensory interface between the ambient environment and the brain. The unique sensory organelle facilitates odor detection for which it includes all necessary components of initial and downstream olfactory signal transduction. In addition to its function in olfaction, a more universal role in modulating different signaling pathways is implicated, for example, in neurogenesis, apoptosis, and neural regeneration. To further extend our knowledge about this multifunctional signaling organelle, it is of high importance to establish a most detailed proteome map of the ciliary membrane compartment down to the level of transmembrane receptors. We detached cilia from mouse olfactory epithelia via Ca(2+)/K(+) shock followed by the enrichment of ciliary membrane proteins at alkaline pH, and we identified a total of 4,403 proteins by gel-based and gel-free methods in conjunction with high resolution LC/MS. This study is the first to report the detection of 62 native olfactory receptor proteins and to provide evidence for their heterogeneous expression at the protein level. Quantitative data evaluation revealed four ciliary membrane-associated candidate proteins (the annexins ANXA1, ANXA2, ANXA5, and S100A5) with a suggested function in the regulation of olfactory signal transduction, and their presence in ciliary structures was confirmed by immunohistochemistry. Moreover, we corroborated the ciliary localization of the potassium-dependent Na(+)/Ca(2+) exchanger (NCKX) 4 and the plasma membrane Ca(2+)-ATPase 1 (PMCA1) involved in olfactory signal termination, and we detected for the first time NCKX2 in olfactory cilia. Through comparison with transcriptome data specific for mature, ciliated OSNs, we finally delineated the membrane ciliome of OSNs. The membrane proteome of olfactory cilia established here is the most complete today, thus allowing us to pave new avenues for the study of diverse molecular functions and signaling pathways in and out of olfactory cilia and thus to advance our understanding of the biology of sensory organelles in general.
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Affiliation(s)
- Katja Kuhlmann
- From the ‡Medizinisches Proteom-Center, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum
| | - Astrid Tschapek
- From the ‡Medizinisches Proteom-Center, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum
| | - Heike Wiese
- the ¶Faculty of Biology and BIOSS Centre for Biological Signalling Studies, University of Freiburg, Schänzlestrasse 1, 79104 Freiburg
| | - Martin Eisenacher
- From the ‡Medizinisches Proteom-Center, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum
| | - Helmut E Meyer
- From the ‡Medizinisches Proteom-Center, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, the ‖Leibniz-Institut für Analytische Wissenschaften-ISAS-e.V., Otto-Hahn-Strasse 6b, 44227 Dortmund, and
| | - Hanns H Hatt
- the **Department of Cell Physiology, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | - Silke Oeljeklaus
- the ¶Faculty of Biology and BIOSS Centre for Biological Signalling Studies, University of Freiburg, Schänzlestrasse 1, 79104 Freiburg
| | - Bettina Warscheid
- the ¶Faculty of Biology and BIOSS Centre for Biological Signalling Studies, University of Freiburg, Schänzlestrasse 1, 79104 Freiburg,
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Abstract
TMEM16 proteins, also known as anoctamins, are involved in a variety of functions that include ion transport, phospholipid scrambling, and regulation of other membrane proteins. The first two members of the family, TMEM16A (anoctamin-1, ANO1) and TMEM16B (anoctamin-2, ANO2), function as Ca2+-activated Cl- channels (CaCCs), a type of ion channel that plays important functions such as transepithelial ion transport, smooth muscle contraction, olfaction, phototransduction, nociception, and control of neuronal excitability. Genetic ablation of TMEM16A in mice causes impairment of epithelial Cl- secretion, tracheal abnormalities, and block of gastrointestinal peristalsis. TMEM16A is directly regulated by cytosolic Ca2+ as well as indirectly by its interaction with calmodulin. Other members of the anoctamin family, such as TMEM16C, TMEM16D, TMEM16F, TMEM16G, and TMEM16J, may work as phospholipid scramblases and/or ion channels. In particular, TMEM16F (ANO6) is a major contributor to the process of phosphatidylserine translocation from the inner to the outer leaflet of the plasma membrane. Intriguingly, TMEM16F is also associated with the appearance of anion/cation channels activated by very high Ca2+ concentrations. Furthermore, a TMEM16 protein expressed in Aspergillus fumigatus displays both ion channel and lipid scramblase activity. This finding suggests that dual function is an ancestral characteristic of TMEM16 proteins and that some members, such as TMEM16A and TMEM16B, have evolved to a pure channel function. Mutations in anoctamin genes (ANO3, ANO5, ANO6, and ANO10) cause various genetic diseases. These diseases suggest the involvement of anoctamins in a variety of cell functions whose link with ion transport and/or lipid scrambling needs to be clarified.
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46
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Ni YL, Kuan AS, Chen TY. Activation and inhibition of TMEM16A calcium-activated chloride channels. PLoS One 2014; 9:e86734. [PMID: 24489780 PMCID: PMC3906059 DOI: 10.1371/journal.pone.0086734] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 12/16/2013] [Indexed: 11/19/2022] Open
Abstract
Calcium-activated chloride channels (CaCC) encoded by family members of transmembrane proteins of unknown function 16 (TMEM16) have recently been intensely studied for functional properties as well as their physiological roles as chloride channels in various tissues. One technical hurdle in studying these channels is the well-known channel rundown that frequently impairs the precision of electrophysiological measurements for the channels. Using experimental protocols that employ fast-solution exchange, we circumvented the problem of channel rundown by normalizing the Ca2+-induced current to the maximally-activated current obtained within a time period in which the channel rundown was negligible. We characterized the activation of the TMEM16A-encoded CaCC (also called ANO1) by Ca2+, Sr2+, and Ba2+, and discovered that Mg2+ competes with Ca2+ in binding to the divalent-cation binding site without activating the channel. We also studied the permeability of the ANO1 pore for various anions and found that the anion occupancy in the pore–as revealed by the permeability ratios of these anions–appeared to be inversely correlated with the apparent affinity of the ANO1 inhibition by niflumic acid (NFA). On the other hand, the NFA inhibition was neither affected by the degree of the channel activation nor influenced by the types of divalent cations used for the channel activation. These results suggest that the NFA inhibition of ANO1 is likely mediated by altering the pore function but not through changing the channel gating. Our study provides a precise characterization of ANO1 and documents factors that can affect divalent cation activation and NFA inhibition of ANO1.
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Affiliation(s)
- Yu-Li Ni
- Department of Neurology, Center for Neuroscience, University of California Davis, Davis, California, United States of America
| | - Ai-Seon Kuan
- Department of Neurology, Center for Neuroscience, University of California Davis, Davis, California, United States of America
| | - Tsung-Yu Chen
- Department of Neurology, Center for Neuroscience, University of California Davis, Davis, California, United States of America
- * E-mail:
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47
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Abstract
Vertebrates can sense and avoid noxious heat that evokes pain. Many thermoTRP channels are associated with temperature sensation. TRPV1 is a representative ion channel that is activated by noxious heat. Anoctamin 1 (ANO1) is a Cl- channel activated by calcium that is highly expressed in small sensory neurons, colocalized with markers for nociceptors, and most surprisingly, activated by noxious heat over 44oC. Although ANO1 is a Cl- channel, opening of this channel leads to depolarization of sensory neurons, suggesting a role in nociception. Indeed, the functional deletion of ANO1 in sensory neurons triggers the reduction in thermal pain sensation. Thus, it seems clear that ANO1 is a heat sensor in a nociceptive pathway. Since ANO1 modulators are developed for the purpose of treating chronic diseases such as cystic fibrosis, this finding is likely to predict unwanted effects and provide a guide for better developmental strategy
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Affiliation(s)
- Hawon Cho
- Sensory Research Center, CRI, College of Pharmacy, Seoul National University
| | - Uhtaek Oh
- Sensory Research Center, CRI, College of Pharmacy, Seoul National University, ; Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 151-742, Republic of Korea
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48
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Abstract
Ca(2+)-activated Cl(-) channels (CaCCs) are plasma membrane proteins involved in various important physiological processes. In epithelial cells, CaCC activity mediates the secretion of Cl(-) and of other anions, such as bicarbonate and thiocyanate. In smooth muscle and excitable cells of the nervous system, CaCCs have an excitatory role coupling intracellular Ca(2+) elevation to membrane depolarization. Recent studies indicate that TMEM16A (transmembrane protein 16 A or anoctamin 1) and TMEM16B (transmembrane protein 16 B or anoctamin 2) are CaCC-forming proteins. Induced expression of TMEM16A and B in null cells by transfection causes the appearance of Ca(2+)-activated Cl(-) currents similar to those described in native tissues. Furthermore, silencing of TMEM16A by RNAi causes disappearance of CaCC activity in cells from airway epithelium, biliary ducts, salivary glands, and blood vessel smooth muscle. Mice devoid of TMEM16A expression have impaired Ca(2+)-dependent Cl(-) secretion in the epithelial cells of the airways, intestine, and salivary glands. These animals also show a loss of gastrointestinal motility, a finding consistent with an important function of TMEM16A in the electrical activity of gut pacemaker cells, that is, the interstitial cells of Cajal. Identification of TMEM16 proteins will help to elucidate the molecular basis of Cl(-) transport.
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Affiliation(s)
- Loretta Ferrera
- Laboratory of Molecular Genetics, Istituto Giannina Gaslini, Genova, Italy
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49
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Osorio R, Schmachtenberg O. Calcium-activated chloride channels do not contribute to the odorant transduction current in the marine teleost Isacia conceptionis. JOURNAL OF FISH BIOLOGY 2013; 83:1468-1473. [PMID: 24580677 DOI: 10.1111/jfb.12253] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2013] [Accepted: 09/11/2013] [Indexed: 06/03/2023]
Abstract
This study compared the contribution of the Ca²⁺-activated Cl⁻ conductance to the electroolfactogram (EOG) evoked by different odorant classes between the marine Cabinza grunt Isacia conceptionis and rainbow trout Oncorhynchus mykiss. The Ca²⁺-activated Cl⁻ channel blocker niflumic acid significantly diminished odorant responses in O. mykiss, but had no effect on the EOG in I. conceptionis, supporting the notion that Ca²⁺-activated Cl⁻ channels may not operate as odorant transduction current amplifiers in this marine teleost.
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Affiliation(s)
- R Osorio
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Avda. Gran Bretaña 1111, 2360102, Valparaíso, Chile
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50
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2,4,6-trichloroanisole is a potent suppressor of olfactory signal transduction. Proc Natl Acad Sci U S A 2013; 110:16235-40. [PMID: 24043819 DOI: 10.1073/pnas.1300764110] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We investigated the sensitivity of single olfactory receptor cells to 2,4,6-trichloroanisole (TCA), a compound known for causing cork taint in wines. Such off-flavors have been thought to originate from unpleasant odor qualities evoked by contaminants. However, we here show that TCA attenuates olfactory transduction by suppressing cyclic nucleotide-gated channels, without evoking odorant responses. Surprisingly, suppression was observed even at extremely low (i.e., attomolar) TCA concentrations. The high sensitivity to TCA was associated with temporal integration of the suppression effect. We confirmed that potent suppression by TCA and similar compounds was correlated with their lipophilicity, as quantified by the partition coefficient at octanol/water boundary (pH 7.4), suggesting that channel suppression is mediated by a partitioning of TCA into the lipid bilayer of plasma membranes. The rank order of suppression matched human recognition of off-flavors: TCA equivalent to 2,4,6-tribromoanisole, which is much greater than 2,4,6-trichlorophenol. Furthermore, TCA was detected in a wide variety of foods and beverages surveyed for odor losses. Our findings demonstrate a potential molecular mechanism for the reduction of flavor.
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