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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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Kim H, Kim H, Nguyen LT, Ha T, Lim S, Kim K, Kim SH, Han K, Hyeon SJ, Ryu H, Park YS, Kim SH, Kim IB, Hong GS, Lee SE, Choi Y, Cohen LB, Oh U. Amplification of olfactory signals by Anoctamin 9 is important for mammalian olfaction. Prog Neurobiol 2022; 219:102369. [PMID: 36330924 DOI: 10.1016/j.pneurobio.2022.102369] [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: 05/21/2022] [Revised: 10/21/2022] [Accepted: 10/24/2022] [Indexed: 11/06/2022]
Abstract
Sensing smells of foods, prey, or predators determines animal survival. Olfactory sensory neurons in the olfactory epithelium (OE) detect odorants, where cAMP and Ca2+ play a significant role in transducing odorant inputs to electrical activity. Here we show Anoctamin 9, a cation channel activated by cAMP/PKA pathway, is expressed in the OE and amplifies olfactory signals. Ano9-deficient mice had reduced olfactory behavioral sensitivity, electro-olfactogram signals, and neural activity in the olfactory bulb. In line with the difference in olfaction between birds and other vertebrates, chick ANO9 failed to respond to odorants, whereas chick CNGA2, a major transduction channel, showed greater responses to cAMP. Thus, we concluded that the signal amplification by ANO9 is important for mammalian olfactory transduction.
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Affiliation(s)
- Hyungsup Kim
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
| | - Hyesu Kim
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea; Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 08826, Republic of Korea
| | - Luan Thien Nguyen
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea; College of Pharmacy, Seoul National University, Seoul 08826, Republic of Korea
| | - Taewoong Ha
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
| | - Sujin Lim
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea; College of Pharmacy, Seoul National University, Seoul 08826, Republic of Korea
| | - Kyungmin Kim
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
| | - Soon Ho Kim
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
| | - Kyungreem Han
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
| | - Seung Jae Hyeon
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
| | - Hoon Ryu
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
| | - Yong Soo Park
- Department of Anatomy, Catholic Institute for Applied Anatomy, College of Medicine, Catholic University of Korea, Seoul 06591, Republic of Korea
| | - Sang Hyun Kim
- Department of Anatomy, Catholic Institute for Applied Anatomy, College of Medicine, Catholic University of Korea, Seoul 06591, Republic of Korea
| | - In-Beom Kim
- Department of Anatomy, Catholic Institute for Applied Anatomy, College of Medicine, Catholic University of Korea, Seoul 06591, Republic of Korea
| | - Gyu-Sang Hong
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
| | - Seung Eun Lee
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea
| | - Yunsook Choi
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea; Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Lawrence B Cohen
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea; Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Uhtaek Oh
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul 02792, Republic of Korea; Department of Molecular Medicine and Biopharmaceutical Sciences, Graduate School of Convergence Science and Technology, Seoul National University, Seoul 08826, Republic of Korea.
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De Jesús-Pérez JJ, López-Romero AE, Posadas O, Segura-Covarrubias G, Aréchiga-Figueroa I, Gutiérrez-Medina B, Pérez-Cornejo P, Arreola J. Gating and anion selectivity are reciprocally regulated in TMEM16A (ANO1). J Gen Physiol 2022; 154:213275. [PMID: 35687042 PMCID: PMC9194859 DOI: 10.1085/jgp.202113027] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 05/23/2022] [Indexed: 02/03/2023] Open
Abstract
Numerous essential physiological processes depend on the TMEM16A-mediated Ca2+-activated chloride fluxes. Extensive structure-function studies have helped to elucidate the Ca2+ gating mechanism of TMEM16A, revealing a Ca2+-sensing element close to the anion pore that alters conduction. However, substrate selection and the substrate-gating relationship in TMEM16A remain less explored. Here, we study the gating-permeant anion relationship on mouse TMEM16A expressed in HEK 293 cells using electrophysiological recordings coupled with site-directed mutagenesis. We show that the apparent Ca2+ sensitivity of TMEM16A increased with highly permeant anions and SCN- mole fractions, likely by stabilizing bound Ca2+. Conversely, mutations at crucial gating elements, including the Ca2+-binding site 1, the transmembrane helix 6 (TM6), and the hydrophobic gate, impaired the anion permeability and selectivity of TMEM16A. Finally, we found that, unlike anion-selective wild-type channels, the voltage dependence of unselective TMEM16A mutant channels was less sensitive to SCN-. Therefore, our work identifies structural determinants of selectivity at the Ca2+ site, TM6, and hydrophobic gate and reveals a reciprocal regulation of gating and selectivity. We suggest that this regulation is essential to set ionic selectivity and the Ca2+ and voltage sensitivities in TMEM16A.
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Affiliation(s)
| | - Ana E. López-Romero
- Physics Institute, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - Odalys Posadas
- Physics Institute, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | | | - Iván Aréchiga-Figueroa
- Consejo Nacional de Ciencia y Tecnología, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - Braulio Gutiérrez-Medina
- Advanced Materials Division, Instituto Potosino de Investigación Científica y Tecnológica, San Luis Potosí, México
| | - Patricia Pérez-Cornejo
- Department of Physiology and Biophysics, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México
| | - Jorge Arreola
- Physics Institute, Universidad Autónoma de San Luis Potosí, San Luis Potosí, México,Correspondence to Jorge Arreola:
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TMEM16A and TMEM16B Modulate Pheromone-Evoked Action Potential Firing in Mouse Vomeronasal Sensory Neurons. eNeuro 2021; 8:ENEURO.0179-21.2021. [PMID: 34433575 PMCID: PMC8445037 DOI: 10.1523/eneuro.0179-21.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 06/21/2021] [Accepted: 07/06/2021] [Indexed: 12/02/2022] Open
Abstract
The mouse vomeronasal system controls several social behaviors. Pheromones and other social cues are detected by sensory neurons in the vomeronasal organ (VNO). Stimuli activate a transduction cascade that leads to membrane potential depolarization, increase in cytosolic Ca2+ level, and increased firing. The Ca2+-activated chloride channels TMEM16A and TMEM16B are co-expressed within microvilli of vomeronasal neurons, but their physiological role remains elusive. Here, we investigate the contribution of each of these channels to vomeronasal neuron firing activity by comparing wild-type (WT) and knock-out (KO) mice. Performing loose-patch recordings from neurons in acute VNO slices, we show that spontaneous activity is modified by Tmem16a KO, indicating that TMEM16A, but not TMEM16B, is active under basal conditions. Upon exposure to diluted urine, a rich source of mouse pheromones, we observe significant changes in activity. Vomeronasal sensory neurons (VSNs) from Tmem16a cKO and Tmem16b KO mice show shorter interspike intervals (ISIs) compared with WT mice, indicating that both TMEM16A and TMEM16B modulate the firing pattern of pheromone-evoked activity in VSNs.
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Guarascio DM, Gonzalez-Velandia KY, Hernandez-Clavijo A, Menini A, Pifferi S. Functional expression of TMEM16A in taste bud cells. J Physiol 2021; 599:3697-3714. [PMID: 34089532 PMCID: PMC8361675 DOI: 10.1113/jp281645] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Accepted: 06/04/2021] [Indexed: 12/14/2022] Open
Abstract
Key points Taste transduction occurs in taste buds in the tongue epithelium. The Ca2+‐activated Cl– channels TMEM16A and TMEM16B play relevant physiological roles in several sensory systems. Here, we report that TMEM16A, but not TMEM16B, is expressed in the apical part of taste buds. Large Ca2+‐activated Cl− currents blocked by Ani‐9, a selective inhibitor of TMEM16A, are measured in type I taste cells but not in type II or III taste cells. ATP indirectly activates Ca2+‐activated Cl– currents in type I cells through TMEM16A channels. These results indicate that TMEM16A is functional in type I taste cells and contribute to understanding the largely unknown physiological roles of these cells.
Abstract The Ca2+‐activated Cl– channels TMEM16A and TMEM16B have relevant roles in many physiological processes including neuronal excitability and regulation of Cl– homeostasis. Here, we examined the presence of Ca2+‐activated Cl– channels in taste cells of mouse vallate papillae by using immunohistochemistry and electrophysiological recordings. By using immunohistochemistry we showed that only TMEM16A, and not TMEM16B, was expressed in taste bud cells where it largely co‐localized with the inwardly rectifying K+ channel KNCJ1 in the apical part of type I cells. By using whole‐cell patch‐clamp recordings in isolated cells from taste buds, we measured an average current of −1083 pA at −100 mV in 1.5 μm Ca2+ and symmetrical Cl– in type I cells. Ion substitution experiments and blockage by Ani‐9, a specific TMEM16A channel blocker, indicated that Ca2+ activated anionic currents through TMEM16A channels. We did not detect any Ca2+‐activated Cl– currents in type II or III taste cells. ATP is released by type II cells in response to various tastants and reaches type I cells where it is hydrolysed by ecto‐ATPases. Type I cells also express P2Y purinergic receptors and stimulation of type I cells with extracellular ATP produced large Ca2+‐activated Cl− currents blocked by Ani‐9, indicating a possible role of TMEM16A in ATP‐mediated signalling. These results provide a definitive demonstration that TMEM16A‐mediated currents are functional in type I taste cells and provide a foundation for future studies investigating physiological roles for these often‐neglected taste cells. Taste transduction occurs in taste buds in the tongue epithelium. The Ca2+‐activated Cl– channels TMEM16A and TMEM16B play relevant physiological roles in several sensory systems. Here, we report that TMEM16A, but not TMEM16B, is expressed in the apical part of taste buds. Large Ca2+‐activated Cl− currents blocked by Ani‐9, a selective inhibitor of TMEM16A, are measured in type I taste cells but not in type II or III taste cells. ATP indirectly activates Ca2+‐activated Cl– currents in type I cells through TMEM16A channels. These results indicate that TMEM16A is functional in type I taste cells and contribute to understanding the largely unknown physiological roles of these cells.
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Affiliation(s)
- Domenico M Guarascio
- Neurobiology Group, SISSA, Scuola Internazionale Superiore di Studi Avanzati, Trieste, 34136, Italy
| | | | - Andres Hernandez-Clavijo
- Neurobiology Group, SISSA, Scuola Internazionale Superiore di Studi Avanzati, Trieste, 34136, Italy
| | - Anna Menini
- Neurobiology Group, SISSA, Scuola Internazionale Superiore di Studi Avanzati, Trieste, 34136, Italy
| | - Simone Pifferi
- Neurobiology Group, SISSA, Scuola Internazionale Superiore di Studi Avanzati, Trieste, 34136, Italy.,Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, Ancona, 60126, Italy
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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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Shin DH, Kim M, Kim Y, Jun I, Jung J, Nam JH, Cheng MH, Lee MG. Bicarbonate permeation through anion channels: its role in health and disease. Pflugers Arch 2020; 472:1003-1018. [PMID: 32621085 DOI: 10.1007/s00424-020-02425-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 06/19/2020] [Accepted: 06/26/2020] [Indexed: 12/31/2022]
Abstract
Many anion channels, frequently referred as Cl- channels, are permeable to different anions in addition to Cl-. As the second-most abundant anion in the human body, HCO3- permeation via anion channels has many important physiological roles. In addition to its classical role as an intracellular pH regulator, HCO3- also controls the activity and stability of dissolved proteins in bodily fluids such as saliva, pancreatic juice, intestinal fluid, and airway surface liquid. Moreover, HCO3- permeation through these channels affects membrane potentials that are the driving forces for transmembrane transport of solutes and water in epithelia and affect neuronal excitability in nervous tissue. Consequently, aberrant HCO3- transport via anion channels causes a number of human diseases in respiratory, gastrointestinal, genitourinary, and neuronal systems. Notably, recent studies have shown that the HCO3- permeabilities of several anion channels are not fixed and can be altered by cellular stimuli, findings which may have both physiological and pathophysiological significance. In this review, we summarize recent progress in understanding the molecular mechanisms and the physiological roles of HCO3- permeation through anion channels. We hope that the present discussions can stimulate further research into this very important topic, which will provide the basis for human disorders associated with aberrant HCO3- transport.
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Affiliation(s)
- Dong Hoon Shin
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, 03722, South Korea
| | - Minjae Kim
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, 03722, South Korea
| | - Yonjung Kim
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, 03722, South Korea
| | - Ikhyun Jun
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, 03722, South Korea
- The Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, 03722, South Korea
| | - Jinsei Jung
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, 03722, South Korea
- Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, 03722, South Korea
| | - Joo Hyun Nam
- Department of Physiology, Dongguk University College of Medicine, 123 Dongdae-ro, Kyungju, 780-714, Republic of Korea
| | - Mary Hongying Cheng
- Department of Computational & Systems Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Min Goo Lee
- Department of Pharmacology, Brain Korea 21 PLUS Project for Medical Sciences, Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul, 03722, South Korea.
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TMEM16B Calcium-Activated Chloride Channels Regulate Action Potential Firing in Lateral Septum and Aggression in Male Mice. J Neurosci 2019; 39:7102-7117. [PMID: 31320449 DOI: 10.1523/jneurosci.3137-18.2019] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 06/11/2019] [Accepted: 07/11/2019] [Indexed: 11/21/2022] Open
Abstract
The lateral septum (LS) plays an important role in regulating aggression. It is well recognized that LS lesions lead to a dramatic increase in aggressive behaviors. A better understanding of LS neurophysiology and its functional output is therefore important to assess LS involvement in regulating aggression. The LS is a heterogeneous structure that maintains inputs and outputs with multiple brain regions, and is also divided into subregions that innervate one another. Thus, it is challenging to identify the exact cell type and projections for characterization. In this study, we determined the expression pattern of the calcium-activated chloride channel, TMEM16B, in the LS of both male and female mice. We then investigated the physiological contribution of the calcium-activated chloride channel to LS neuronal signaling. By performing whole-cell patch-clamp recording, we showed that TMEM16B alters neurotransmitter release at the hippocampal-LS synapse, and regulates spike frequency and spike frequency adaptation in subpopulations of LS neurons. We further demonstrated that loss of TMEM16B function promotes lengthened displays of aggressive behaviors by male mice during the resident intruder paradigm. In conclusion, our findings suggest that TMEM16B function contributes to neuronal excitability in subpopulations of LS neurons and the regulation of aggression in male mice.SIGNIFICANCE STATEMENT Aggression is a behavior that arose evolutionarily from the necessity to compete for limited resources and survival. One particular brain region involved in aggression is the lateral septum (LS). In this study, we characterized the expression of the TMEM16B calcium-activated chloride channel in the LS and showed that TMEM16B regulates the action potential firing frequency of LS neurons. We discovered that loss of TMEM16B function lengthens the displays of aggressive behaviors in male mice. These findings suggest that TMEM16B plays an important role in regulating LS neuronal excitability and behaviors associated with LS function, thereby contributing to our understanding of how the LS may regulate aggression.
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Mohrhardt J, Nagel M, Fleck D, Ben-Shaul Y, Spehr M. Signal Detection and Coding in the Accessory Olfactory System. Chem Senses 2019; 43:667-695. [PMID: 30256909 PMCID: PMC6211456 DOI: 10.1093/chemse/bjy061] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
In many mammalian species, the accessory olfactory system plays a central role in guiding behavioral and physiological responses to social and reproductive interactions. Because of its relatively compact structure and its direct access to amygdalar and hypothalamic nuclei, the accessory olfactory pathway provides an ideal system to study sensory control of complex mammalian behavior. During the last several years, many studies employing molecular, behavioral, and physiological approaches have significantly expanded and enhanced our understanding of this system. The purpose of the current review is to integrate older and newer studies to present an updated and comprehensive picture of vomeronasal signaling and coding with an emphasis on early accessory olfactory system processing stages. These include vomeronasal sensory neurons in the vomeronasal organ, and the circuitry of the accessory olfactory bulb. Because the overwhelming majority of studies on accessory olfactory system function employ rodents, this review is largely focused on this phylogenetic order, and on mice in particular. Taken together, the emerging view from both older literature and more recent studies is that the molecular, cellular, and circuit properties of chemosensory signaling along the accessory olfactory pathway are in many ways unique. Yet, it has also become evident that, like the main olfactory system, the accessory olfactory system also has the capacity for adaptive learning, experience, and state-dependent plasticity. In addition to describing what is currently known about accessory olfactory system function and physiology, we highlight what we believe are important gaps in our knowledge, which thus define exciting directions for future investigation.
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Affiliation(s)
- Julia Mohrhardt
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, Aachen, Germany
| | - Maximilian Nagel
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, Aachen, Germany
| | - David Fleck
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, Aachen, Germany
| | - Yoram Ben-Shaul
- Department of Medical Neurobiology, School of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Marc Spehr
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, Aachen, Germany
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Ji Q, Guo S, Wang X, Pang C, Zhan Y, Chen Y, An H. Recent advances in TMEM16A: Structure, function, and disease. J Cell Physiol 2018; 234:7856-7873. [PMID: 30515811 DOI: 10.1002/jcp.27865] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2018] [Accepted: 11/13/2018] [Indexed: 12/13/2022]
Abstract
TMEM16A (also known as anoctamin 1, ANO1) is the molecular basis of the calcium-activated chloride channels, with ten transmembrane segments. Recently, atomic structures of the transmembrane domains of mouse TMEM16A (mTMEM16A) were determined by single-particle electron cryomicroscopy. This gives us a solid ground to discuss the electrophysiological properties and functions of TMEM16A. TMEM16A is reported to be dually regulated by Ca2+ and voltage. In addition, the dysfunction of TMEM16A has been found to be involved in many diseases including cystic fibrosis, various cancers, hypertension, and gastrointestinal motility disorders. TMEM16A is overexpressed in many cancers, including gastrointestinal stromal tumors, gastric cancer, head and neck squamous cell carcinoma (HNSCC), colon cancer, pancreatic ductal adenocarcinoma, and esophageal cancer. Furthermore, overexpression of TMEM16A is related to the occurrence, proliferation, and migration of tumor cells. To date, several studies have shown that many natural compounds and synthetic compounds have regulatory effects on TMEM16A. These small molecule compounds might be novel drugs for the treatment of diseases caused by TMEM16A dysfunction in the future. In addition, recent studies have shown that TMEM16A plays different roles in different diseases through different signal transduction pathways. This review discusses the topology, electrophysiological properties, modulators and functions of TMEM16A in mediates nociception, gastrointestinal dysfunction, hypertension, and cancer and focuses on multiple regulatory mechanisms regarding TMEM16A.
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Affiliation(s)
- Qiushuang Ji
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Shuai Guo
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Xuzhao Wang
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Chunli Pang
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Yong Zhan
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Yafei Chen
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
| | - Hailong An
- Key Laboratory of Molecular Biophysics, Hebei Province, Institute of Biophysics, School of Sciences, Hebei University of Technology, Tianjin, China
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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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12
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Kamaleddin MA. Molecular, biophysical, and pharmacological properties of calcium-activated chloride channels. J Cell Physiol 2017; 233:787-798. [PMID: 28121009 DOI: 10.1002/jcp.25823] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 01/24/2017] [Indexed: 12/15/2022]
Abstract
Calcium-activated chloride channels (CaCCs) are a family of anionic transmembrane ion channels. They are mainly responsible for the movement of Cl- and other anions across the biological membranes, and they are widely expressed in different tissues. Since the Cl- flow into or out of the cell plays a crucial role in hyperpolarizing or depolarizing the cells, respectively, the impact of intracellular Ca2+ concentration on these channels is attracting a lot of attentions. After summarizing the molecular, biophysical, and pharmacological properties of CaCCs, the role of CaCCs in normal cellular functions will be discussed, and I will emphasize how dysregulation of CaCCs in pathological conditions can account for different diseases. A better understanding of CaCCs and a pivotal regulatory role of Ca2+ can shed more light on the therapeutic strategies for different neurological disorders that arise from chloride dysregulation, such as asthma, cystic fibrosis, and neuropathic pain.
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Affiliation(s)
- Mohammad Amin Kamaleddin
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada.,Neurosciences and Mental Health, The Hospital for Sick Children, Toronto, Ontario, Canada
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13
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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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14
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Keckeis S, Reichhart N, Roubeix C, Strauß O. Anoctamin2 (TMEM16B) forms the Ca2+-activated Cl− channel in the retinal pigment epithelium. Exp Eye Res 2017; 154:139-150. [DOI: 10.1016/j.exer.2016.12.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 12/05/2016] [Accepted: 12/05/2016] [Indexed: 01/12/2023]
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15
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Ma K, Wang H, Yu J, Wei M, Xiao Q. New Insights on the Regulation of Ca 2+ -Activated Chloride Channel TMEM16A. J Cell Physiol 2016; 232:707-716. [PMID: 27682822 DOI: 10.1002/jcp.25621] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 09/27/2016] [Indexed: 12/16/2022]
Abstract
TMEM16A, also known as anoctamin 1, is a recently identified Ca2+ -activated chloride channel and the first member of a 10-member TMEM16 family. TMEM16A dysfunction is implicated in many diseases such as cancer, hypertension, and cystic fibrosis. TMEM16A channels are well known to be dually regulated by voltage and Ca2+ . In addition, recent studies have revealed that TMEM16A channels are regulated by many molecules such as calmodulin, protons, cholesterol, and phosphoinositides, and a diverse range of stimuli such as thermal and mechanical stimuli. A better understanding of the regulatory mechanisms of TMEM16A is important to understand its physiological and pathological role. Recently, the crystal structure of a TMEM16 family member from the fungus Nectria haematococcaten (nhTMEM16) is discovered, and provides valuable information for studying the structure and function of TMEM16A. In this review, we discuss the structure and function of TMEM16A channels based on the crystal structure of nhTMEM16A and focus on the regulatory mechanisms of TMEM16A channels. J. Cell. Physiol. 232: 707-716, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Ke Ma
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, P. R. China
| | - Hui Wang
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, P. R. China
| | - Jiankun Yu
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, P. R. China
| | - Minjie Wei
- Department of Pharmacology, School of Pharmacy, China Medical University, Shenyang, P. R. China
| | - Qinghuan Xiao
- Department of Ion Channel Pharmacology, School of Pharmacy, China Medical University, Shenyang, P. R. China
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16
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Zhang X, Jia R, Zhou J, Wang M, Yin Z, Cheng A. Capsid-Targeted Viral Inactivation: A Novel Tactic for Inhibiting Replication in Viral Infections. Viruses 2016; 8:E258. [PMID: 27657114 PMCID: PMC5035972 DOI: 10.3390/v8090258] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 09/08/2016] [Accepted: 09/15/2016] [Indexed: 12/18/2022] Open
Abstract
Capsid-targeted viral inactivation (CTVI), a conceptually powerful new antiviral strategy, is attracting increasing attention from researchers. Specifically, this strategy is based on fusion between the capsid protein of a virus and a crucial effector molecule, such as a nuclease (e.g., staphylococcal nuclease, Barrase, RNase HI), lipase, protease, or single-chain antibody (scAb). In general, capsid proteins have a major role in viral integration and assembly, and the effector molecule used in CTVI functions to degrade viral DNA/RNA or interfere with proper folding of viral key proteins, thereby affecting the infectivity of progeny viruses. Interestingly, such a capsid-enzyme fusion protein is incorporated into virions during packaging. CTVI is more efficient compared to other antiviral methods, and this approach is promising for antiviral prophylaxis and therapy. This review summarizes the mechanism and utility of CTVI and provides some successful applications of this strategy, with the ultimate goal of widely implementing CTVI in antiviral research.
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Affiliation(s)
- Xingcui Zhang
- Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, Wenjiang District, Chengdu 611130, Sichuan Province, China.
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang District, Chengdu 611130, Sichuan Province, China.
| | - Renyong Jia
- Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, Wenjiang District, Chengdu 611130, Sichuan Province, China.
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Wenjiang District, Chengdu 611130, Sichuan Province, China.
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang District, Chengdu 611130, Sichuan Province, China.
| | - Jiakun Zhou
- Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, Wenjiang District, Chengdu 611130, Sichuan Province, China.
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang District, Chengdu 611130, Sichuan Province, China.
| | - Mingshu Wang
- Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, Wenjiang District, Chengdu 611130, Sichuan Province, China.
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Wenjiang District, Chengdu 611130, Sichuan Province, China.
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang District, Chengdu 611130, Sichuan Province, China.
| | - Zhongqiong Yin
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Wenjiang District, Chengdu 611130, Sichuan Province, China.
| | - Anchun Cheng
- Avian Disease Research Center, College of Veterinary Medicine of Sichuan Agricultural University, Wenjiang District, Chengdu 611130, Sichuan Province, China.
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, Wenjiang District, Chengdu 611130, Sichuan Province, China.
- Institute of Preventive Veterinary Medicine, Sichuan Agricultural University, Wenjiang District, Chengdu 611130, Sichuan Province, China.
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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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18
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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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19
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Song SC, Beatty JA, Wilson CJ. The ionic mechanism of membrane potential oscillations and membrane resonance in striatal LTS interneurons. J Neurophysiol 2016; 116:1752-1764. [PMID: 27440246 DOI: 10.1152/jn.00511.2016] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 07/15/2016] [Indexed: 01/22/2023] Open
Abstract
Striatal low-threshold spiking (LTS) interneurons spontaneously transition to a depolarized, oscillating state similar to that seen after sodium channels are blocked. In the depolarized state, whether spontaneous or induced by sodium channel blockade, the neurons express a 3- to 7-Hz oscillation and membrane impedance resonance in the same frequency range. The membrane potential oscillation and membrane resonance are expressed in the same voltage range (greater than -40 mV). We identified and recorded from LTS interneurons in striatal slices from a mouse that expressed green fluorescent protein under the control of the neuropeptide Y promoter. The membrane potential oscillation depended on voltage-gated calcium channels. Antagonism of L-type calcium currents (CaV1) reduced the amplitude of the oscillation, whereas blockade of N-type calcium currents (CaV2.2) reduced the frequency. Both calcium sources activate a calcium-activated chloride current (CaCC), the blockade of which abolished the oscillation. The blocking of any of these three channels abolished the membrane resonance. Immunohistochemical staining indicated anoctamin 2 (ANO2), and not ANO1, as the CaCC source. Biophysical modeling showed that CaV1, CaV2.2, and ANO2 are sufficient to generate a membrane potential oscillation and membrane resonance, similar to that in LTS interneurons. LTS interneurons exhibit a membrane potential oscillation and membrane resonance that are both generated by CaV1 and CaV2.2 activating ANO2. They can spontaneously enter a state in which the membrane potential oscillation dominates the physiological properties of the neuron.
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Affiliation(s)
- S C Song
- Department of Biology, The University of Texas at San Antonio, San Antonio, Texas; and
| | - J A Beatty
- Department of Biology, The University of Texas at San Antonio, San Antonio, Texas; and Department of Physiology, Michigan State University, East Lansing, Michigan
| | - C J Wilson
- Department of Biology, The University of Texas at San Antonio, San Antonio, Texas; and
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20
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Tian J, Pinto JM, Cui X, Zhang H, Li L, Liu Y, Wu C, Wei Y. Sendai Virus Induces Persistent Olfactory Dysfunction in a Murine Model of PVOD via Effects on Apoptosis, Cell Proliferation, and Response to Odorants. PLoS One 2016; 11:e0159033. [PMID: 27428110 PMCID: PMC4948916 DOI: 10.1371/journal.pone.0159033] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 06/27/2016] [Indexed: 11/24/2022] Open
Abstract
Background Viral infection is a common cause of olfactory dysfunction. The complexities of studying post-viral olfactory loss in humans have impaired further progress in understanding the underlying mechanism. Recently, evidence from clinical studies has implicated Parainfluenza virus 3 as a causal agent. An animal model of post viral olfactory disorders (PVOD) would allow better understanding of disease pathogenesis and represent a major advance in the field. Objective To develop a mouse model of PVOD by evaluating the effects of Sendai virus (SeV), the murine counterpart of Parainfluenza virus, on olfactory function and regenerative ability of the olfactory epithelium. Methods C57BL/6 mice (6–8 months old) were inoculated intranasally with SeV or ultraviolet (UV)-inactivated virus (UV-SeV). On days 3, 10, 15, 30 and 60 post-infection, olfactory epithelium was harvested and analyzed by histopathology and immunohistochemical detection of S-phase nuclei. We also measured apoptosis by TUNEL assay and viral load by real-time PCR. The buried food test (BFT) was used to measure olfactory function of mice at day 60. In parallel, cultured murine olfactory sensory neurons (OSNs) infected with SeV or UV-SeV were tested for odorant-mixture response by measuring changes in intracellular calcium concentrations indicated by fura-4 AM assay. Results Mice infected with SeV suffered from olfactory dysfunction, peaking on day 15, with no loss observed with UV-SeV. At 60 days, four out of 12 mice infected with SeV still had not recovered, with continued normal function in controls. Viral copies of SeV persisted in both the olfactory epithelium (OE) and the olfactory bulb (OB) for at least 60 days. At day 10 and after, both unit length labeling index (ULLI) of apoptosis and ULLI of proliferation in the SeV group was markedly less than the UV-SeV group. In primary cultured OSNs infected by SeV, the percentage of cells responding to mixed odors was markedly lower in the SeV group compared to UV-SeV (P = 0.007). Conclusion We demonstrate that SeV impairs olfaction, persists in OE and OB tissue, reduces their regenerative ability, and impairs the normal physiological function of OSNs without gross cytopathology. This mouse model shares key features of human post-viral olfactory loss, supporting its future use in studies of PVOD. Further testing and development of this model should allow us to clarify the pathophysiology of PVOD.
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Affiliation(s)
- Jun Tian
- Department of Otolaryngology Head & Neck Surgery, The First Hospital of Shanxi Medical University, Shanxi Medical University, Taiyuan, Shanxi Province, China
| | - Jayant M. Pinto
- Section of Otolaryngology-Head and Neck Surgery, Department of Surgery, The University of Chicago, Chicago, Illinois, United States of America
| | - Xiaolan Cui
- Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Chaoyang District, Beijing, China
| | - Henghui Zhang
- Peking University People’s Hospital, Peking University Hepatology Institute, Beijing, China
| | - Li Li
- Department of Otolaryngology Head & Neck Surgery, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China
| | - Yulong Liu
- Department of Otolaryngology Head & Neck Surgery, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Chan Wu
- Department of Otolaryngology Head & Neck Surgery, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Yongxiang Wei
- Department of Otolaryngology Head & Neck Surgery, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
- * E-mail:
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21
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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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22
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Dibattista M, Reisert J. The Odorant Receptor-Dependent Role of Olfactory Marker Protein in Olfactory Receptor Neurons. J Neurosci 2016; 36:2995-3006. [PMID: 26961953 PMCID: PMC4783500 DOI: 10.1523/jneurosci.4209-15.2016] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 01/25/2016] [Accepted: 02/04/2016] [Indexed: 11/21/2022] Open
Abstract
Olfactory receptor neurons (ORNs) in the nasal cavity detect and transduce odorants into action potentials to be conveyed to the olfactory bulb. Odorants are delivered to ORNs via the inhaled air at breathing frequencies that can vary from 2 to 10 Hz in the mouse. Thus olfactory transduction should occur at sufficient speed such that it can accommodate repetitive and frequent stimulation. Activation of odorant receptors (ORs) leads to adenylyl cyclase III activation, cAMP increase, and opening of cyclic nucleotide-gated channels. This makes the kinetic regulation of cAMP one of the important determinants for the response time course. We addressed the dynamic regulation of cAMP during the odorant response and examined how basal levels of cAMP are controlled. The latter is particularly relevant as basal cAMP depends on the basal activity of the expressed OR and thus varies across ORNs. We found that olfactory marker protein (OMP), a protein expressed in mature ORNs, controls both basal and odorant-induced cAMP levels in an OR-dependent manner. Lack of OMP increases basal cAMP, thus abolishing differences in basal cAMP levels between ORNs expressing different ORs. Moreover, OMP speeds up signal transduction for ORNs to better synchronize their output with high-frequency stimulation and to perceive brief stimuli. Last, OMP also steepens the dose-response relation to improve concentration coding although at the cost of losing responses to weak stimuli. We conclude that OMP plays a key regulatory role in ORN physiology by controlling multiple facets of the odorant response.
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Affiliation(s)
| | - Johannes Reisert
- Monell Chemical Senses Center, Philadelphia, Pennsylvania 19104-3308
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23
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Whitlock JM, Hartzell HC. A Pore Idea: the ion conduction pathway of TMEM16/ANO proteins is composed partly of lipid. Pflugers Arch 2016; 468:455-73. [PMID: 26739711 PMCID: PMC4751199 DOI: 10.1007/s00424-015-1777-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Revised: 12/14/2015] [Accepted: 12/16/2015] [Indexed: 01/04/2023]
Abstract
Since their first descriptions, ion channels have been conceived as proteinaceous conduits that facilitate the passage of ionic cargo between segregated environments. This concept is reinforced by crystallographic structures of cation channels depicting ion conductance pathways completely lined by protein. Although lipids are sometimes present in fenestrations near the pore or may be involved in channel gating, there is little or no evidence that lipids inhabit the ion conduction pathway. Indeed, the presence of lipid acyl chains in the conductance pathway would curse the design of the channel's aqueous pore. Here, we make a speculative proposal that anion channels in the TMEM16/ANO superfamily have ion conductance pathways composed partly of lipids. Our reasoning is based on the idea that TMEM16 ion channels evolved from a kind of lipid transporter that scrambles lipids between leaflets of the membrane bilayer and the modeled structural similarity between TMEM16 lipid scramblases and TMEM16 anion channels. This novel view of the TMEM16 pore offers explanation for the biophysical and pharmacological oddness of TMEM16A. We build upon the recent X-ray structure of nhTMEM16 and develop models of both TMEM16 ion channels and lipid scramblases to bolster our proposal. It is our hope that this model of the TMEM16 pore will foster innovative investigation into TMEM16 function.
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Affiliation(s)
- Jarred M Whitlock
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - H Criss Hartzell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, 30322, USA.
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Cherkashin AP, Kolesnikova AS, Tarasov MV, Romanov RA, Rogachevskaja OA, Bystrova MF, Kolesnikov SS. Expression of calcium-activated chloride channels Ano1 and Ano2 in mouse taste cells. Pflugers Arch 2015; 468:305-19. [DOI: 10.1007/s00424-015-1751-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 10/20/2015] [Accepted: 10/23/2015] [Indexed: 02/03/2023]
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25
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TMEM16, LRRC8A, bestrophin: chloride channels controlled by Ca2+ and cell volume. Trends Biochem Sci 2015; 40:535-43. [DOI: 10.1016/j.tibs.2015.07.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 07/10/2015] [Accepted: 07/10/2015] [Indexed: 01/13/2023]
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Four basic residues critical for the ion selectivity and pore blocker sensitivity of TMEM16A calcium-activated chloride channels. Proc Natl Acad Sci U S A 2015; 112:3547-52. [PMID: 25733897 DOI: 10.1073/pnas.1502291112] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
TMEM16A (transmembrane protein 16) (Anoctamin-1) forms a calcium-activated chloride channel (CaCC) that regulates a broad array of physiological properties in response to changes in intracellular calcium concentration. Although known to conduct anions according to the Eisenman type I selectivity sequence, the structural determinants of TMEM16A anion selectivity are not well-understood. Reasoning that the positive charges on basic residues are likely contributors to anion selectivity, we performed whole-cell recordings of mutants with alanine substitution for basic residues within the putative pore region and identified four residues on four different putative transmembrane segments that significantly increased the permeability of the larger halides and thiocyanate relative to that of chloride. Because TMEM16A permeation properties are known to shift with changes in intracellular calcium concentration, we further examined the calcium dependence of anion selectivity. We found that WT TMEM16A but not mutants with alanine substitution at those four basic residues exhibited a clear decline in the preference for larger anions as intracellular calcium was increased. Having implicated these residues as contributing to the TMEM16A pore, we scrutinized candidate small molecules from a high-throughput CaCC inhibitor screen to identify two compounds that act as pore blockers. Mutations of those four putative pore-lining basic residues significantly altered the IC50 of these compounds at positive voltages. These findings contribute to our understanding regarding anion permeation of TMEM16A CaCC and provide valuable pharmacological tools to probe the channel pore.
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Cenedese V, Mezzavilla M, Morgan A, Marino R, Ettorre CP, Margaglione M, Gasparini P, Menini A. Assessment of the olfactory function in Italian patients with type 3 von Willebrand disease caused by a homozygous 253 Kb deletion involving VWF and TMEM16B/ANO2. PLoS One 2015; 10:e0116483. [PMID: 25635880 PMCID: PMC4312080 DOI: 10.1371/journal.pone.0116483] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 12/08/2014] [Indexed: 01/18/2023] Open
Abstract
Type 3 Von Willebrand disease is an autosomal recessive disease caused by the virtual absence of the von Willebrand factor (VWF). A rare 253 kb gene deletion on chromosome 12, identified only in Italian and German families, involves both the VWF gene and the N-terminus of the neighbouring TMEM16B/ANO2 gene, a member of the family named transmembrane 16 (TMEM16) or anoctamin (ANO). TMEM16B is a calcium-activated chloride channel expressed in the olfactory epithelium. As a patient homozygous for the 253 kb deletion has been reported to have an olfactory impairment possibly related to the partial deletion of TMEM16B, we assessed the olfactory function in other patients using the University of Pennsylvania Smell Identification Test (UPSIT). The average UPSIT score of 4 homozygous patients was significantly lower than that of 5 healthy subjects with similar sex, age and education. However, 4 other members of the same family, 3 heterozygous for the deletion and 1 wild type, had a slightly reduced olfactory function indicating that socio-cultural or other factors were likely to be responsible for the observed difference. These results show that the ability to identify odorants of the homozygous patients for the deletion was not significantly different from that of the other members of the family, showing that the 253 kb deletion does not affect the olfactory performance. As other genes may compensate for the lack of TMEM16B, we identified some predicted functional partners from in silico studies of the protein-protein network of TMEM16B. Calculation of diversity for the corresponding genes for individuals of the 1000 Genomes Project showed that TMEM16B has the highest level of diversity among all genes of the network, indicating that TMEM16B may not be under purifying selection and suggesting that other genes in the network could compensate for its function for olfactory ability.
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Affiliation(s)
- Valentina Cenedese
- Neurobiology Group, SISSA, International School for Advanced Studies, Trieste, Italy
| | - Massimo Mezzavilla
- Institute for Maternal and Child Health, Istituto Di Ricovero e Cura a Carattere Scientifico “Burlo Garofolo” and Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste, Italy
| | - Anna Morgan
- Institute for Maternal and Child Health, Istituto Di Ricovero e Cura a Carattere Scientifico “Burlo Garofolo” and Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste, Italy
| | - Renato Marino
- Centro Emofilia e Trombosi, Azienda Ospedaliero-Universitaria Ospedale Policlinico Consorziale “Giovanni XXIII”, Bari, Italy
| | - Cosimo Pietro Ettorre
- Centro Emofilia e Trombosi, Azienda Ospedaliero-Universitaria Ospedale Policlinico Consorziale “Giovanni XXIII”, Bari, Italy
| | - Maurizio Margaglione
- Genetica Medica, Dipartimento di Medicina Clinica e Sperimentale, University of Foggia, Foggia, Italy
| | - Paolo Gasparini
- Institute for Maternal and Child Health, Istituto Di Ricovero e Cura a Carattere Scientifico “Burlo Garofolo” and Department of Medical, Surgical and Health Sciences, University of Trieste, Trieste, Italy
| | - Anna Menini
- Neurobiology Group, SISSA, International School for Advanced Studies, Trieste, Italy
- * E-mail:
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Cherian OL, Menini A, Boccaccio A. Multiple effects of anthracene-9-carboxylic acid on the TMEM16B/anoctamin2 calcium-activated chloride channel. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1005-13. [PMID: 25620774 DOI: 10.1016/j.bbamem.2015.01.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 01/04/2015] [Accepted: 01/13/2015] [Indexed: 10/24/2022]
Abstract
Ca(2+)-activated Cl(-) currents (CaCCs) play important roles in many physiological processes. Recent studies have shown that TMEM16A/anoctamin1 and TMEM16B/anoctamin2 constitute CaCCs in several cell types. Here we have investigated for the first time the extracellular effects of the Cl(-) channel blocker anthracene-9-carboxylic acid (A9C) and of its non-charged analogue anthracene-9-methanol (A9M) on TMEM16B expressed in HEK 293T cells, using the whole-cell patch-clamp technique. A9C caused a voltage-dependent block of outward currents and inhibited a larger fraction of the current as depolarization increased, whereas the non-charged A9M produced a small, not voltage dependent block of outward currents. A similar voltage-dependent block by A9C was measured both when TMEM16B was activated by 1.5 and 13μM Ca(2+). However, in the presence of 1.5μM Ca(2+) (but not in 13μM Ca(2+)), A9C also induced a strong potentiation of tail currents measured at -100mV after depolarizing voltages, as well as a prolongation of the deactivation kinetics. On the contrary, A9M did not produce potentiation of tail currents, showing that the negative charge is required for potentiation. Our results provide the first evidence that A9C has multiple effects on TMEM16B and that the negative charge of A9C is necessary both for voltage-dependent block and for potentiation. Future studies are required to identify the molecular mechanisms underlying these complex effects of A9C on TMEM16B. Understanding these mechanisms will contribute to the elucidation of the structure and functional properties of TMEM16B channels.
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Affiliation(s)
- O Lijo Cherian
- Neurobiology Group, SISSA, International School for Advanced Studies, Via Bonomea 265, 34136 Trieste, Italy
| | - Anna Menini
- Neurobiology Group, SISSA, International School for Advanced Studies, Via Bonomea 265, 34136 Trieste, Italy
| | - Anna Boccaccio
- Istituto di Biofisica, CNR, Via De Marini 6, 16149 Genova, Italy.
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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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30
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Betto G, Cherian OL, Pifferi S, Cenedese V, Boccaccio A, Menini A. Interactions between permeation and gating in the TMEM16B/anoctamin2 calcium-activated chloride channel. ACTA ACUST UNITED AC 2014; 143:703-18. [PMID: 24863931 PMCID: PMC4035747 DOI: 10.1085/jgp.201411182] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Extracellular anions more permeant than Cl− modulate TMEM16B gating to promote channel opening, whereas less permeant anions favor channel closure. At least two members of the TMEM16/anoctamin family, TMEM16A (also known as anoctamin1) and TMEM16B (also known as anoctamin2), encode Ca2+-activated Cl− channels (CaCCs), which are found in various cell types and mediate numerous physiological functions. Here, we used whole-cell and excised inside-out patch-clamp to investigate the relationship between anion permeation and gating, two processes typically viewed as independent, in TMEM16B expressed in HEK 293T cells. The permeability ratio sequence determined by substituting Cl− with other anions (PX/PCl) was SCN− > I− > NO3− > Br− > Cl− > F− > gluconate. When external Cl− was substituted with other anions, TMEM16B activation and deactivation kinetics at 0.5 µM Ca2+ were modified according to the sequence of permeability ratios, with anions more permeant than Cl− slowing both activation and deactivation and anions less permeant than Cl− accelerating them. Moreover, replacement of external Cl− with gluconate, or sucrose, shifted the voltage dependence of steady-state activation (G-V relation) to more positive potentials, whereas substitution of extracellular or intracellular Cl− with SCN− shifted G-V to more negative potentials. Dose–response relationships for Ca2+ in the presence of different extracellular anions indicated that the apparent affinity for Ca2+ at +100 mV increased with increasing permeability ratio. The apparent affinity for Ca2+ in the presence of intracellular SCN− also increased compared with that in Cl−. Our results provide the first evidence that TMEM16B gating is modulated by permeant anions and provide the basis for future studies aimed at identifying the molecular determinants of TMEM16B ion selectivity and gating.
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Affiliation(s)
- Giulia Betto
- Neurobiology Group, International School for Advanced Studies (SISSA), 34136 Trieste, Italy
| | - O Lijo Cherian
- Neurobiology Group, International School for Advanced Studies (SISSA), 34136 Trieste, Italy
| | - Simone Pifferi
- Neurobiology Group, International School for Advanced Studies (SISSA), 34136 Trieste, Italy
| | - Valentina Cenedese
- Neurobiology Group, International School for Advanced Studies (SISSA), 34136 Trieste, Italy
| | - Anna Boccaccio
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche, 16149 Genova, Italy
| | - Anna Menini
- Neurobiology Group, International School for Advanced Studies (SISSA), 34136 Trieste, Italy
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Ackels T, von der Weid B, Rodriguez I, Spehr M. Physiological characterization of formyl peptide receptor expressing cells in the mouse vomeronasal organ. Front Neuroanat 2014; 8:134. [PMID: 25484858 PMCID: PMC4240171 DOI: 10.3389/fnana.2014.00134] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 11/01/2014] [Indexed: 12/14/2022] Open
Abstract
The mouse vomeronasal organ (VNO) is a chemosensory structure that detects both hetero- and conspecific social cues. Based on largely monogenic expression of either type 1 or 2 vomeronasal receptors (V1Rs/V2Rs) or members of the formyl peptide receptor (FPR) family, the vomeronasal sensory epithelium harbors at least three neuronal subpopulations. While various neurophysiological properties of both V1R- and V2R-expressing neurons have been described using genetically engineered mouse models, the basic biophysical characteristics of the more recently identified FPR-expressing vomeronasal neurons have not been studied. Here, we employ a transgenic mouse strain that coexpresses an enhanced variant of yellow fluorescent protein together with FPR-rs3 allowing to identify and analyze FPR-rs3-expressing neurons in acute VNO tissue slices. Single neuron electrophysiological recordings allow comparative characterization of the biophysical properties inherent to a prototypical member of the FPR-expressing subpopulation of VNO neurons. In this study, we provide an in-depth analysis of both passive and active membrane properties, including detailed characterization of several types of voltage-activated conductances and action potential discharge patterns, in fluorescently labeled vs. unmarked vomeronasal neurons. Our results reveal striking similarities in the basic (electro) physiological architecture of both transgene-expressing and non-expressing neurons, confirming the suitability of this genetically engineered mouse model for future studies addressing more specialized issues in vomeronasal FPR neurobiology.
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Affiliation(s)
- Tobias Ackels
- Department of Chemosensation, RWTH Aachen University Aachen, Germany
| | - Benoît von der Weid
- Department of Genetics and Evolution, University of Geneva Geneva, Switzerland
| | - Ivan Rodriguez
- Department of Genetics and Evolution, University of Geneva Geneva, Switzerland
| | - Marc Spehr
- Department of Chemosensation, RWTH Aachen University Aachen, Germany
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32
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Singh RD, Gibbons SJ, Saravanaperumal SA, Du P, Hennig GW, Eisenman ST, Mazzone A, Hayashi Y, Cao C, Stoltz GJ, Ordog T, Rock JR, Harfe BD, Szurszewski JH, Farrugia G. Ano1, a Ca2+-activated Cl- channel, coordinates contractility in mouse intestine by Ca2+ transient coordination between interstitial cells of Cajal. J Physiol 2014; 592:4051-68. [PMID: 25063822 DOI: 10.1113/jphysiol.2014.277152] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Interstitial cells of Cajal (ICC) are pacemaker cells that generate electrical activity to drive contractility in the gastrointestinal tract via ion channels. Ano1 (Tmem16a), a Ca(2+)-activated Cl(-) channel, is an ion channel expressed in ICC. Genetic deletion of Ano1 in mice resulted in loss of slow waves in smooth muscle of small intestine. In this study, we show that Ano1 is required to maintain coordinated Ca(2+) transients between myenteric ICC (ICC-MY) of small intestine. First, we found spontaneous Ca(2+) transients in ICC-MY in both Ano1 WT and knockout (KO) mice. However, Ca(2+) transients within the ICC-MY network in Ano1 KO mice were uncoordinated, while ICC-MY Ca(2+) transients in Ano1 WT mice were rhythmic and coordinated. To confirm the role of Ano1 in the loss of Ca(2+) transient coordination, we used pharmacological inhibitors of Ano1 activity and shRNA-mediated knock down of Ano1 expression in organotypic cultures of Ano1 WT small intestine. Coordinated Ca(2+) transients became uncoordinated using both these approaches, supporting the conclusion that Ano1 is required to maintain coordination/rhythmicity of Ca(2+) transients. We next determined the effect on smooth muscle contractility using spatiotemporal maps of contractile activity in Ano1 KO and WT tissues. Significantly decreased contractility that appeared to be non-rhythmic and uncoordinated was observed in Ano1 KO jejunum. In conclusion, Ano1 has a previously unidentified role in the regulation of coordinated gastrointestinal smooth muscle function through coordination of Ca(2+) transients in ICC-MY.
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Affiliation(s)
- Raman Deep Singh
- Department of Physiology and Biomedical Engineering Enteric NeuroScience Program, Mayo Clinic, Rochester, MN, USA
| | - Simon J Gibbons
- Department of Physiology and Biomedical Engineering Enteric NeuroScience Program, Mayo Clinic, Rochester, MN, USA
| | | | - Peng Du
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Grant W Hennig
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, NV, USA
| | - Seth T Eisenman
- Department of Physiology and Biomedical Engineering Enteric NeuroScience Program, Mayo Clinic, Rochester, MN, USA
| | - Amelia Mazzone
- Department of Physiology and Biomedical Engineering Enteric NeuroScience Program, Mayo Clinic, Rochester, MN, USA
| | - Yujiro Hayashi
- Department of Physiology and Biomedical Engineering Enteric NeuroScience Program, Mayo Clinic, Rochester, MN, USA
| | - Chike Cao
- Department of Physiology and Biomedical Engineering Enteric NeuroScience Program, Mayo Clinic, Rochester, MN, USA
| | - Gary J Stoltz
- Department of Physiology and Biomedical Engineering Enteric NeuroScience Program, Mayo Clinic, Rochester, MN, USA
| | - Tamas Ordog
- Department of Physiology and Biomedical Engineering Enteric NeuroScience Program, Mayo Clinic, Rochester, MN, USA
| | - Jason R Rock
- Department of Anatomy, UCSF School of Medicine, San Francisco, CA, USA
| | - Brian D Harfe
- Department of Molecular Genetics and Microbiology Genetics Institute, University of Florida, College of Medicine, Gainesville, FL, USA
| | - Joseph H Szurszewski
- Department of Physiology and Biomedical Engineering Enteric NeuroScience Program, Mayo Clinic, Rochester, MN, USA
| | - Gianrico Farrugia
- Department of Physiology and Biomedical Engineering Enteric NeuroScience Program, Mayo Clinic, Rochester, MN, USA
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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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Pervez N, Ham HG, Kim S. Interplay of Signaling Molecules in Olfactory Sensory Neuron toward Signal Amplification. ACTA ACUST UNITED AC 2014. [DOI: 10.7599/hmr.2014.34.3.137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Nayab Pervez
- Department of Pharmacy, Institute of Pharmaceutical Science and Technology, Hanyang University, Ansan, Korea
| | - Hyoung-Geol Ham
- Department of Pharmacy, Institute of Pharmaceutical Science and Technology, Hanyang University, Ansan, Korea
| | - Sangseong Kim
- Department of Pharmacy, Institute of Pharmaceutical Science and Technology, Hanyang University, Ansan, Korea
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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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37
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Maurya DK, Menini A. Developmental expression of the calcium-activated chloride channels TMEM16A and TMEM16B in the mouse olfactory epithelium. Dev Neurobiol 2013; 74:657-75. [PMID: 24318978 DOI: 10.1002/dneu.22159] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Revised: 12/02/2013] [Accepted: 12/03/2013] [Indexed: 01/21/2023]
Abstract
Calcium-activated chloride channels are involved in several physiological processes including olfactory perception. TMEM16A and TMEM16B, members of the transmembrane protein 16 family (TMEM16), are responsible for calcium-activated chloride currents in several cells. Both are present in the olfactory epithelium of adult mice, but little is known about their expression during embryonic development. Using immunohistochemistry we studied their expression in the mouse olfactory epithelium at various stages of prenatal development from embryonic day (E) 12.5 to E18.5 as well as in postnatal mice. At E12.5, TMEM16A immunoreactivity was present at the apical surface of the entire olfactory epithelium, but from E16.5 became restricted to a region near the transition zone with the respiratory epithelium, where localized at the apical part of supporting cells and in their microvilli. In contrast, TMEM16B immunoreactivity was present at E14.5 at the apical surface of the entire olfactory epithelium, increased in subsequent days, and localized to the cilia of mature olfactory sensory neurons. These data suggest different functional roles for TMEM16A and TMEM16B in the developing as well as in the postnatal olfactory epithelium. The presence of TMEM16A at the apical part and in microvilli of supporting cells is consistent with a role in the regulation of the chloride ionic composition of the mucus covering the apical surface of the olfactory epithelium, whereas the localization of TMEM16B to the cilia of mature olfactory sensory neurons is consistent with a role in olfactory signal transduction.
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Affiliation(s)
- Devendra Kumar Maurya
- Laboratory of Olfactory Transduction, SISSA, International School for Advanced Studies, Via Bonomea 265, Trieste, 34136, Italy
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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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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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40
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Ponissery Saidu S, Stephan AB, Talaga AK, Zhao H, Reisert J. Channel properties of the splicing isoforms of the olfactory calcium-activated chloride channel Anoctamin 2. ACTA ACUST UNITED AC 2013; 141:691-703. [PMID: 23669718 PMCID: PMC3664704 DOI: 10.1085/jgp.201210937] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Anoctamin (ANO)2 (or TMEM16B) forms a cell membrane Ca(2+)-activated Cl(-) channel that is present in cilia of olfactory receptor neurons, vomeronasal microvilli, and photoreceptor synaptic terminals. Alternative splicing of Ano2 transcripts generates multiple variants with the olfactory variants skipping exon 14 and having alternative splicing of exon 4. In the present study, 5' rapid amplification of cDNA ends analysis was conducted to characterize the 5' end of olfactory Ano2 transcripts, which showed that the most abundant Ano2 transcripts in the olfactory epithelium contain a novel starting exon that encodes a translation initiation site, whereas transcripts of the publically available sequence variant, which has an alternative and longer 5' end, were present in lower abundance. With two alternative starting exons and alternative splicing of exon 4, four olfactory ANO2 isoforms are thus possible. Patch-clamp experiments in transfected HEK293T cells expressing these isoforms showed that N-terminal sequences affect Ca(2+) sensitivity and that the exon 4-encoded sequence is required to form functional channels. Coexpression of the two predominant isoforms, one with and one without the exon 4 sequence, as well as coexpression of the two rarer isoforms showed alterations in channel properties, indicating that different isoforms interact with each other. Furthermore, channel properties observed from the coexpression of the predominant isoforms better recapitulated the native channel properties, suggesting that the native channel may be composed of two or more splicing isoforms acting as subunits that together shape the channel properties.
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41
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Shimizu T, Iehara T, Sato K, Fujii T, Sakai H, Okada Y. TMEM16F is a component of a Ca2+-activated Cl- channel but not a volume-sensitive outwardly rectifying Cl- channel. Am J Physiol Cell Physiol 2013; 304:C748-59. [PMID: 23426967 DOI: 10.1152/ajpcell.00228.2012] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
TMEM16 (transmembrane protein 16) proteins, which possess eight putative transmembrane domains with intracellular NH2- and COOH-terminal tails, are thought to comprise a Cl(-) channel family. The function of TMEM16F, a member of the TMEM16 family, has been greatly controversial. In the present study, we performed whole cell patch-clamp recordings to investigate the function of human TMEM16F. In TMEM16F-transfected HEK293T cells but not TMEM16K- and mock-transfected cells, activation of membrane currents with strong outward rectification was found to be induced by application of a Ca(2+) ionophore, ionomycin, or by an increase in the intracellular free Ca(2+) concentration. The free Ca(2+) concentration for half-maximal activation of TMEM16F currents was 9.6 μM, which is distinctly higher than that for TMEM16A/B currents. The outwardly rectifying current-voltage relationship for TMEM16F currents was not changed by an increase in the intracellular Ca(2+) level, in contrast to TMEM16A/B currents. The Ca(2+)-activated TMEM16F currents were anion selective, because replacing Cl(-) with aspartate(-) in the bathing solution without changing cation concentrations caused a positive shift of the reversal potential. The anion selectivity sequence of the TMEM16F channel was I(-) > Br(-) > Cl(-) > F(-) > aspartate(-). Niflumic acid, a Ca(2+)-activated Cl(-) channel blocker, inhibited the TMEM16F-dependent Cl(-) currents. Neither overexpression nor knockdown of TMEM16F affected volume-sensitive outwardly rectifying Cl(-) channel (VSOR) currents activated by osmotic swelling or apoptotic stimulation. These results demonstrate that human TMEM16F is an essential component of a Ca(2+)-activated Cl(-) channel with a Ca(2+) sensitivity that is distinct from that of TMEM16A/B and that it is not related to VSOR activity.
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Affiliation(s)
- Takahiro Shimizu
- Department of Pharmaceutical Physiology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan.
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Dynamic modulation of ANO1/TMEM16A HCO3(-) permeability by Ca2+/calmodulin. Proc Natl Acad Sci U S A 2012; 110:360-5. [PMID: 23248295 DOI: 10.1073/pnas.1211594110] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Anoctamin 1 (ANO1)/transmembrane protein 16A (TMEM16A) is a calcium-activated anion channel that may play a role in HCO(3)(-) secretion in epithelial cells. Here, we report that the anion selectivity of ANO1 is dynamically regulated by the Ca(2+)/calmodulin complex. Whole-cell current measurements in HEK 293T cells indicated that ANO1 becomes highly permeable to HCO(3)(-) at high [Ca(2+)](i). Interestingly, this result was not observed in excised patches, indicating the involvement of cytosolic factors in this process. Further studies revealed that the direct association between ANO1 and calmodulin at high [Ca(2+)](i) is responsible for changes in anion permeability. Calmodulin physically interacted with ANO1 in a [Ca(2+)](i)-dependent manner, and addition of recombinant calmodulin to the cytosolic side of excised patches reversibly increased P(HCO3)/P(Cl). In addition, the high [Ca(2+)](i)-induced increase in HCO(3)(-) permeability was reproduced in mouse submandibular gland acinar cells, in which ANO1 plays a critical role in fluid secretion. These results indicate that the HCO(3)(-) permeability of ANO1 can be dynamically modulated and that ANO1 may play an important role in cellular HCO(3)(-) transport, especially in transepithelial HCO(3)(-) secretion.
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Tian Y, Schreiber R, Kunzelmann K. Anoctamins are a family of Ca2+-activated Cl- channels. J Cell Sci 2012; 125:4991-8. [PMID: 22946059 DOI: 10.1242/jcs.109553] [Citation(s) in RCA: 128] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Anoctamin 1 (Ano1; TMEM16A) and anoctamin 2 (Ano2; TMEM16B) are novel Cl(-) channels transiently activated by an increase in intracellular Ca(2+). These channels are essential for epithelial Cl(-) secretion, smooth muscle peristalsis and olfactory signal transduction. They are central to inherited diseases and cancer and can act as heat sensors. Surprisingly, another member of this protein family, Ano6, operates as a Ca(2+)-activated phospholipid scramblase, and others were reported as intracellular proteins. It is therefore unclear whether anoctamins constitute a family of Ca(2+)-activated Cl(-) channels, or are proteins with heterogeneous functions. Using whole-cell patch clamping we demonstrate that Ano4-10 are all able to produce transient Ca(2+)-activated Cl(-) currents when expressed in HEK293 cells. Although some anoctamins (Ano1, 2, 4, 6, 7) were found to be well expressed in the plasma membrane, others (Ano8, 9, 10) show rather poor membrane expression and were mostly retained in the cytosol. The transient nature of the Cl(-) currents was demonstrated to be independent of intracellular Ca(2+) levels. We show that inactivation of Ano1 currents occurs in the continuous presence of elevated Ca(2+) concentrations, possibly by calmodulin-dependent kinase. The present results demonstrate that anoctamins are a family of Ca(2+)-activated Cl(-) channels, which also induce permeability for cations. They may operate as Cl(-) channels located in the plasma membrane or in intracellular compartments. These results increase our understanding of the physiological significance of anoctamins and their role in disease.
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Affiliation(s)
- Yuemin Tian
- Institut für Physiologie, Universität Regensburg, Universitätsstraße 31, 93053 Regensburg, Germany
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Dauner K, Lissmann J, Jeridi S, Frings S, Möhrlen F. Expression patterns of anoctamin 1 and anoctamin 2 chloride channels in the mammalian nose. Cell Tissue Res 2012; 347:327-41. [PMID: 22314846 DOI: 10.1007/s00441-012-1324-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 01/09/2012] [Indexed: 02/01/2023]
Abstract
Calcium-activated chloride channels are expressed in chemosensory neurons of the nose and contribute to secretory processes and sensory signal transduction. These channels are thought to be members of the family of anoctamins (alternative name: TMEM16 proteins), which are opened by micromolar concentrations of intracellular Ca(2+). Two family members,ANO 1 (TMEM16A) and ANO 2 (TMEM16B), are expressed in the various sensory and respiratory tissues of the nose.We have examined the tissue specificity and sub-cellular localization of these channels in the nasal respiratory epithelium and in the five chemosensory organs of the nose: the main olfactory epithelium, the septal organ of Masera, the vomeronasal organ, the Grueneberg ganglion and the trigeminal system. We have found that the two channels show mutually exclusive expression patterns. ANO 1 is present in the apical membranes of various secretory epithelia in which it is co-localized with the water channel aquaporin 5. It has also been detected in acinar cells and duct cells of subepithelial glands and in the supporting cells of sensory epithelia. In contrast, ANO 2 expression is restricted to chemosensory neurons in which it has been detected in microvillar and ciliary surface structures. The different expression patterns of ANO 1 and ANO 2 have been observed in the olfactory, vomeronasal and respiratory epithelia. No expression has been detected in the Grueneberg ganglion or trigeminal sensory fibers. On the basis of this differential expression, we derive the main functional features of ANO 1 and ANO 2 chloride channels in the nose and suggest their significance for nasal physiology.
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Affiliation(s)
- Kristin Dauner
- Department of Molecular Physiology, Centre for Organismal Studies, University of Heidelberg, Im Neuenheimer Feld 230, 69120 Heidelberg, Germany
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Dibattista M, Amjad A, Maurya DK, Sagheddu C, Montani G, Tirindelli R, Menini A. Calcium-activated chloride channels in the apical region of mouse vomeronasal sensory neurons. ACTA ACUST UNITED AC 2012; 140:3-15. [PMID: 22732308 PMCID: PMC3382724 DOI: 10.1085/jgp.201210780] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The rodent vomeronasal organ plays a crucial role in several social behaviors. Detection of pheromones or other emitted signaling molecules occurs in the dendritic microvilli of vomeronasal sensory neurons, where the binding of molecules to vomeronasal receptors leads to the influx of sodium and calcium ions mainly through the transient receptor potential canonical 2 (TRPC2) channel. To investigate the physiological role played by the increase in intracellular calcium concentration in the apical region of these neurons, we produced localized, rapid, and reproducible increases in calcium concentration with flash photolysis of caged calcium and measured calcium-activated currents with the whole cell voltage-clamp technique. On average, a large inward calcium-activated current of −261 pA was measured at −50 mV, rising with a time constant of 13 ms. Ion substitution experiments showed that this current is anion selective. Moreover, the chloride channel blockers niflumic acid and 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid partially inhibited the calcium-activated current. These results directly demonstrate that a large chloride current can be activated by calcium in the apical region of mouse vomeronasal sensory neurons. Furthermore, we showed by immunohistochemistry that the calcium-activated chloride channels TMEM16A/anoctamin1 and TMEM16B/anoctamin2 are present in the apical layer of the vomeronasal epithelium, where they largely colocalize with the TRPC2 transduction channel. Immunocytochemistry on isolated vomeronasal sensory neurons showed that TMEM16A and TMEM16B coexpress in the neuronal microvilli. Therefore, we conclude that microvilli of mouse vomeronasal sensory neurons have a high density of calcium-activated chloride channels that may play an important role in vomeronasal transduction.
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Affiliation(s)
- Michele Dibattista
- Neurobiology Sector and Italian Institute of Technology Unit, Scuola Internazionale Superiore di Studi Avanzati (SISSA), 34136 Trieste, Italy
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46
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Cenedese V, Betto G, Celsi F, Cherian OL, Pifferi S, Menini A. The voltage dependence of the TMEM16B/anoctamin2 calcium-activated chloride channel is modified by mutations in the first putative intracellular loop. ACTA ACUST UNITED AC 2012; 139:285-94. [PMID: 22412191 PMCID: PMC3315145 DOI: 10.1085/jgp.201110764] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Ca2+-activated Cl− channels (CaCCs) are involved in several physiological processes. Recently, TMEM16A/anoctamin1 and TMEM16B/anoctamin2 have been shown to function as CaCCs, but very little information is available on the structure–function relations of these channels. TMEM16B is expressed in the cilia of olfactory sensory neurons, in microvilli of vomeronasal sensory neurons, and in the synaptic terminals of retinal photoreceptors. Here, we have performed the first site-directed mutagenesis study on TMEM16B to understand the molecular mechanisms of voltage and Ca2+ dependence. We have mutated amino acids in the first putative intracellular loop and measured the properties of the wild-type and mutant TMEM16B channels expressed in HEK 293T cells using the whole cell voltage-clamp technique in the presence of various intracellular Ca2+ concentrations. We mutated E367 into glutamine or deleted the five consecutive glutamates 386EEEEE390 and 399EYE401. The EYE deletion did not significantly modify the apparent Ca2+ dependence nor the voltage dependence of channel activation. E367Q and deletion of the five glutamates did not greatly affect the apparent Ca2+ affinity but modified the voltage dependence, shifting the conductance–voltage relations toward more positive voltages. These findings indicate that glutamates E367 and 386EEEEE390 in the first intracellular putative loop play an important role in the voltage dependence of TMEM16B, thus providing an initial structure–function study for this channel.
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Affiliation(s)
- Valentina Cenedese
- Neurobiology Sector, International School for Advanced Studies, and Italian Institute of Technology, SISSA Unit, 34136 Trieste, Italy
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47
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Huang F, Wong X, Jan LY. International Union of Basic and Clinical Pharmacology. LXXXV: calcium-activated chloride channels. Pharmacol Rev 2011; 64:1-15. [PMID: 22090471 DOI: 10.1124/pr.111.005009] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Calcium-activated chloride channels (CaCCs) are widely expressed in various tissues and implicated in physiological processes such as sensory transduction, epithelial secretion, and smooth muscle contraction. Transmembrane proteins with unknown function 16 (TMEM16A) has recently been identified as a major component of CaCCs. Detailed molecular analysis of TMEM16A will be needed to understand its structure-function relationships. The role this channel plays in physiological systems remains to be established and is currently a subject of intense investigation.
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Affiliation(s)
- Fen Huang
- Department of Physiology, Howard Hughes Medical Institute, University of California, San Francisco, Mission Bay Campus, San Francisco, CA 94158-2811, USA
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48
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Duran C, Qu Z, Osunkoya AO, Cui Y, Hartzell HC. ANOs 3-7 in the anoctamin/Tmem16 Cl- channel family are intracellular proteins. Am J Physiol Cell Physiol 2011; 302:C482-93. [PMID: 22075693 DOI: 10.1152/ajpcell.00140.2011] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ca(2+)-activated Cl(-) channels (CaCCs) participate in numerous physiological functions such as neuronal excitability, sensory transduction, and transepithelial fluid transport. Recently, it was shown that heterologously expressed anoctamins ANO1 and ANO2 generate currents that resemble native CaCCs. The anoctamin family (also called Tmem16) consists of 10 members, but it is not known whether all members of the family are CaCCs. Expression of ANOs 3-7 in HEK293 cells did not generate Cl(-) currents activated by intracellular Ca(2+), as determined by whole cell patch clamp electrophysiology. With the use of confocal imaging, only ANO1 and ANO2 traffic to the plasma membrane when expressed heterologously. Furthermore, endogenously expressed ANO7 in the human prostate is predominantly intracellular. We took a chimeric approach to identify regions critical for channel trafficking and function. However, none of the chimeras of ANO1 and ANO5/7 that we made trafficked to the plasma membrane. Our results suggest that intracellular anoctamins may be endoplasmic reticulum proteins, although it remains unknown whether these family members are CaCCs. Determining the role of anoctamin family members in ion transport will be critical to understanding their functions in physiology and disease.
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Affiliation(s)
- Charity Duran
- Department of Cell Biology and Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322-3030, USA
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49
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Boccaccio A, Sagheddu C, Menini A. Flash photolysis of caged compounds in the cilia of olfactory sensory neurons. J Vis Exp 2011:e3195. [PMID: 22064384 DOI: 10.3791/3195] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Photolysis of caged compounds allows the production of rapid and localized increases in the concentration of various physiologically active compounds. Caged compounds are molecules made physiologically inactive by a chemical cage that can be broken by a flash of ultraviolet light. Here, we show how to obtain patch-clamp recordings combined with photolysis of caged compounds for the study of olfactory transduction in dissociated mouse olfactory sensory neurons. The process of olfactory transduction (Figure 1) takes place in the cilia of olfactory sensory neurons, where odorant binding to receptors leads to the increase of cAMP that opens cyclic nucleotide-gated (CNG) channels. Ca entry through CNG channels activates Ca-activated Cl channels. We show how to dissociate neurons from the mouse olfactory epithelium and how to activate CNG channels or Ca-activated Cl channels by photolysis of caged cAMP or caged Ca. We use a flash lamp to apply ultraviolet flashes to the ciliary region to uncage cAMP or Ca while patch-clamp recordings are taken to measure the current in the whole-cell voltage-clamp configuration.
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Pifferi S, Cenedese V, Menini A. Anoctamin 2/TMEM16B: a calcium-activated chloride channel in olfactory transduction. Exp Physiol 2011; 97:193-9. [DOI: 10.1113/expphysiol.2011.058230] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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