1
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Messina DN, Peralta ED, Acosta CG. Complex alterations in inflammatory pain and analgesic sensitivity in young and ageing female rats: involvement of ASIC3 and Nav1.8 in primary sensory neurons. Inflamm Res 2024; 73:669-691. [PMID: 38483556 DOI: 10.1007/s00011-024-01862-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 02/05/2024] [Accepted: 02/12/2024] [Indexed: 04/10/2024] Open
Abstract
OBJECTIVE AND DESIGN Our aim was to determine an age-dependent role of Nav1.8 and ASIC3 in dorsal root ganglion (DRG) neurons in a rat pre-clinical model of long-term inflammatory pain. METHODS We compared 6 and 24 months-old female Wistar rats after cutaneous inflammation. We used behavioral pain assessments over time, qPCR, quantitative immunohistochemistry, selective pharmacological manipulation, ELISA and in vitro treatment with cytokines. RESULTS Older rats exhibited delayed recovery from mechanical allodynia and earlier onset of spontaneous pain than younger rats after inflammation. Moreover, the expression patterns of Nav1.8 and ASIC3 were time and age-dependent and ASIC3 levels remained elevated only in aged rats. In vivo, selective blockade of Nav1.8 with A803467 or of ASIC3 with APETx2 alleviated mechanical and cold allodynia and also spontaneous pain in both age groups with slightly different potency. Furthermore, in vitro IL-1β up-regulated Nav1.8 expression in DRG neurons cultured from young but not old rats. We also found that while TNF-α up-regulated ASIC3 expression in both age groups, IL-6 and IL-1β had this effect only on young and aged neurons, respectively. CONCLUSION Inflammation-associated mechanical allodynia and spontaneous pain in the elderly can be more effectively treated by inhibiting ASIC3 than Nav1.8.
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Affiliation(s)
- Diego N Messina
- Laboratory of Neurobiology of Pain, Faculty of Medical Sciences, IHEM (Instituto de Histologia y Embriologia Mendoza, Dr. Mario H Burgos), Cuyo National University, Av. Del Libertador 80, 5500, Mendoza, Argentina
| | - Emanuel D Peralta
- Laboratory of Neurobiology of Pain, Faculty of Medical Sciences, IHEM (Instituto de Histologia y Embriologia Mendoza, Dr. Mario H Burgos), Cuyo National University, Av. Del Libertador 80, 5500, Mendoza, Argentina
| | - Cristian G Acosta
- Laboratory of Neurobiology of Pain, Faculty of Medical Sciences, IHEM (Instituto de Histologia y Embriologia Mendoza, Dr. Mario H Burgos), Cuyo National University, Av. Del Libertador 80, 5500, Mendoza, Argentina.
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2
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Deleye L, Franchi F, Trevisani M, Loiacono F, Vercellino S, Debellis D, Liessi N, Armirotti A, Vázquez E, Valente P, Castagnola V, Benfenati F. Few-layered graphene increases the response of nociceptive neurons to irritant stimuli. NANOSCALE 2024; 16:2419-2431. [PMID: 38226500 DOI: 10.1039/d3nr03790h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2024]
Abstract
The unique properties of few-layered graphene (FLG) make it interesting for a variety of applications, including biomedical applications, such as tissue engineering and drug delivery. Although different studies focus on applications in the central nervous system, its interaction with the peripheral nervous system has been so far overlooked. Here, we investigated the effects of exposure to colloidal dispersions of FLG on the sensory neurons of the rat dorsal root ganglia (DRG). We found that the FLG flakes were actively internalized by sensory neurons, accumulated in large intracellular vesicles, and possibly degraded over time, without major toxicological concerns, as neuronal viability, morphology, protein content, and basic electrical properties of DRG neurons were preserved. Interestingly, in our electrophysiological investigation under noxious stimuli, we observed an increased functional response upon FLG treatment of the nociceptive subpopulation of DRG neurons in response to irritants specific for chemoreceptors TRPV1 and TRPA1. The observed effects of FLG on DRG neurons may open-up novel opportunities for applications of these materials in specific disease models.
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Affiliation(s)
- Lieselot Deleye
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia (IIT), Largo Rosanna Benzi 10, 16132 Genova, Italy.
| | - Francesca Franchi
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia (IIT), Largo Rosanna Benzi 10, 16132 Genova, Italy.
- IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genova, Italy
| | - Martina Trevisani
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia (IIT), Largo Rosanna Benzi 10, 16132 Genova, Italy.
- Department of Experimental Medicine, Section of Physiology, University of Genova, Genoa, 16132, Italy.
| | - Fabrizio Loiacono
- IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genova, Italy
| | - Silvia Vercellino
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia (IIT), Largo Rosanna Benzi 10, 16132 Genova, Italy.
- IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genova, Italy
| | - Doriana Debellis
- Electron Microscopy Facility, IIT, Via Morego 30, 16163, Genoa, Italy
| | - Nara Liessi
- Analytical Chemistry Facility, IIT, via Morego, 30, 16163, Genoa, Italy
| | - Andrea Armirotti
- Analytical Chemistry Facility, IIT, via Morego, 30, 16163, Genoa, Italy
| | - Ester Vázquez
- Facultad de Ciencias Químicas, Universidad Castilla La-Mancha, Ciudad Real, 13071 Spain
| | - Pierluigi Valente
- IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genova, Italy
- Department of Experimental Medicine, Section of Physiology, University of Genova, Genoa, 16132, Italy.
| | - Valentina Castagnola
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia (IIT), Largo Rosanna Benzi 10, 16132 Genova, Italy.
- IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genova, Italy
| | - Fabio Benfenati
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia (IIT), Largo Rosanna Benzi 10, 16132 Genova, Italy.
- IRCCS Ospedale Policlinico San Martino, Largo Rosanna Benzi 10, 16132 Genova, Italy
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3
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Flor H, Noguchi K, Treede RD, Turk DC. The role of evolving concepts and new technologies and approaches in advancing pain research, management, and education since the establishment of the International Association for the Study of Pain. Pain 2023; 164:S16-S21. [PMID: 37831955 DOI: 10.1097/j.pain.0000000000003063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Accepted: 08/09/2023] [Indexed: 10/15/2023]
Abstract
ABSTRACT The decades since the inauguration of the International Association for the Study of Pain have witnessed major advances in scientific concepts (such as the biopsychosocial model and chronic primary pain as a disease in its own right) and in new technologies and approaches (from molecular biology to brain imaging) that have inspired innovations in pain research. These have guided progress in pain management and education about pain for healthcare professionals, the general public, and administrative agencies.
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Affiliation(s)
- Herta Flor
- Institute of Cognitive and Clinical Neuroscience, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Koichi Noguchi
- Laboratory of Pain Mechanism Research, Hyogo Medical University, Hyogo, Japan
| | - Rolf-Detlef Treede
- Department of Neurophysiology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Dennis C Turk
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA, United States
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4
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Okada Y, Numata T, Sabirov RZ, Kashio M, Merzlyak PG, Sato-Numata K. Cell death induction and protection by activation of ubiquitously expressed anion/cation channels. Part 3: the roles and properties of TRPM2 and TRPM7. Front Cell Dev Biol 2023; 11:1246955. [PMID: 37842082 PMCID: PMC10576435 DOI: 10.3389/fcell.2023.1246955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Accepted: 09/15/2023] [Indexed: 10/17/2023] Open
Abstract
Cell volume regulation (CVR) is a prerequisite for animal cells to survive and fulfill their functions. CVR dysfunction is essentially involved in the induction of cell death. In fact, sustained normotonic cell swelling and shrinkage are associated with necrosis and apoptosis, and thus called the necrotic volume increase (NVI) and the apoptotic volume decrease (AVD), respectively. Since a number of ubiquitously expressed ion channels are involved in the CVR processes, these volume-regulatory ion channels are also implicated in the NVI and AVD events. In Part 1 and Part 2 of this series of review articles, we described the roles of swelling-activated anion channels called VSOR or VRAC and acid-activated anion channels called ASOR or PAC in CVR and cell death processes. Here, Part 3 focuses on therein roles of Ca2+-permeable non-selective TRPM2 and TRPM7 cation channels activated by stress. First, we summarize their phenotypic properties and molecular structure. Second, we describe their roles in CVR. Since cell death induction is tightly coupled to dysfunction of CVR, third, we focus on their participation in the induction of or protection against cell death under oxidative, acidotoxic, excitotoxic, and ischemic conditions. In this regard, we pay attention to the sensitivity of TRPM2 and TRPM7 to a variety of stress as well as to their capability to physicall and functionally interact with other volume-related channels and membrane enzymes. Also, we summarize a large number of reports hitherto published in which TRPM2 and TRPM7 channels are shown to be involved in cell death associated with a variety of diseases or disorders, in some cases as double-edged swords. Lastly, we attempt to describe how TRPM2 and TRPM7 are organized in the ionic mechanisms leading to cell death induction and protection.
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Affiliation(s)
- Yasunobu Okada
- National Institute for Physiological Sciences (NIPS), Okazaki, Japan
- Department of Integrative Physiology, Graduate School of Medicine, AkitaUniversity, Akita, Japan
- Department of Physiology, School of Medicine, Aichi Medical Uniersity, Nagakute, Japan
- Department of Physiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
- Cardiovascular Research Institute, Yokohama City University, Yokohama, Japan
| | - Tomohiro Numata
- Department of Integrative Physiology, Graduate School of Medicine, AkitaUniversity, Akita, Japan
| | - Ravshan Z. Sabirov
- Institute of Biophysics and Biochemistry, National University of Uzbekistan, Tashkent, Uzbekistan
| | - Makiko Kashio
- National Institute for Physiological Sciences (NIPS), Okazaki, Japan
- Department of Physiology, School of Medicine, Aichi Medical Uniersity, Nagakute, Japan
| | - Peter G. Merzlyak
- Institute of Biophysics and Biochemistry, National University of Uzbekistan, Tashkent, Uzbekistan
| | - Kaori Sato-Numata
- Department of Integrative Physiology, Graduate School of Medicine, AkitaUniversity, Akita, Japan
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5
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Ovsepian SV, Waxman SG. Gene therapy for chronic pain: emerging opportunities in target-rich peripheral nociceptors. Nat Rev Neurosci 2023; 24:252-265. [PMID: 36658346 DOI: 10.1038/s41583-022-00673-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/22/2022] [Indexed: 01/20/2023]
Abstract
With sweeping advances in precision delivery systems and manipulation of the genomes and transcriptomes of various cell types, medical biotechnology offers unprecedented selectivity for and control of a wide variety of biological processes, forging new opportunities for therapeutic interventions. This perspective summarizes state-of-the-art gene therapies enabled by recent innovations, with an emphasis on the expanding universe of molecular targets that govern the activity and function of primary sensory neurons and which might be exploited to effectively treat chronic pain.
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Affiliation(s)
- Saak V Ovsepian
- School of Science, Faculty of Engineering and Science, University of Greenwich London, Chatham Maritime, UK.
| | - Stephen G Waxman
- Department of Neurology, Yale University School of Medicine, New Haven, CT, USA.
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT, USA.
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT, USA.
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6
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Animal toxins: As an alternative therapeutic target following ischemic stroke condition. Life Sci 2023; 317:121365. [PMID: 36640901 DOI: 10.1016/j.lfs.2022.121365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 11/29/2022] [Accepted: 12/31/2022] [Indexed: 01/13/2023]
Abstract
Globally, Ischemic stroke (IS) has become the second leading cause of mortality and chronic disability. The process of IS has triggered by the blockages of blood vessels to form clots in the brain which initiates multiple interactions with the key signaling pathways, counting excitotoxicity, acidosis, ionic imbalance, inflammation, oxidative stress, and neuronal dysfunction of cells, and ultimately cells going under apoptosis. Currently, FDA has approved only tissue plasminogen activator therapy, which is effective against IS with few limitations. However, the mechanism of excitotoxicity and acidosis has spurred the investigation of a potential candidate for IS therapy. Acid-sensing ion channels (ASICs) and Voltage-gated Ca2+ channels (VDCCs) get activated and disturb the brain's normal physiology. Animal toxins are novel inhibitors of ASICs and VDCCs channels and have provided neuroprotective insights into the pathophysiology of IS. This review will discuss the potential directions of translational ASICs and VDCCs inhibitors research for clinical therapies.
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7
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Sun HW, Chu XP, Simon RP, Xiong ZG, Leng TD. Inhibition of Acid-Sensing Ion Channels by KB-R7943, a Reverse Na+/Ca2+ Exchanger Inhibitor. Biomolecules 2023; 13:biom13030507. [PMID: 36979442 PMCID: PMC10046550 DOI: 10.3390/biom13030507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 02/27/2023] [Accepted: 03/07/2023] [Indexed: 03/12/2023] Open
Abstract
KB-R7943, an isothiourea derivative, is widely used as a pharmacological inhibitor of reverse sodium–calcium exchanger (NCX). It has been shown to have neuroprotective and analgesic effects in animal models; however, the detailed molecular mechanisms remain elusive. In the current study, we investigated whether KB-R7943 modulates acid-sensing ion channels (ASICs), a group of proton-gated cation channels implicated in the pathophysiology of various neurological disorders, using the whole-cell patch clamp techniques. Our data show that KB-R7943 irreversibly inhibits homomeric ASIC1a channels heterologously expressed in Chinese Hamster Ovary (CHO) cells in a use- and concentration-dependent manner. It also reversibly inhibits homomeric ASIC2a and ASIC3 channels in CHO cells. Both the transient and sustained current components of ASIC3 are inhibited. Furthermore, KB-R7943 inhibits ASICs in primary cultured peripheral and central neurons. It inhibits the ASIC-like currents in mouse dorsal root ganglion (DRG) neurons and the ASIC1a-like currents in mouse cortical neurons. The inhibition of the ASIC1a-like current is use-dependent and unrelated to its effect on NCX since neither of the other two well-characterized NCX inhibitors, including SEA0400 and SN-6, shows an effect on ASIC. Our data also suggest that the isothiourea group, which is lacking in other structurally related analogs that do not affect ASIC1a-like current, may serve as a critical functional group. In summary, we characterize KB-R7943 as a new ASIC inhibitor. It provides a novel pharmacological tool for the investigation of the functions of ASICs and could serve as a lead compound for developing small-molecule drugs for treating ASIC-related disorders.
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Affiliation(s)
- Hua-Wei Sun
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA
| | - Xiang-Ping Chu
- Department of Biomedical Sciences, University of Missouri-Kansas City School of Medicine, Kansas City, MO 64108, USA
| | - Roger P. Simon
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA
| | - Zhi-Gang Xiong
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA
| | - Tian-Dong Leng
- Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310, USA
- Correspondence:
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8
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Qin L, Cui J, Li J. Sympathetic Nerve Activity and Blood Pressure Response to Exercise in Peripheral Artery Disease: From Molecular Mechanisms, Human Studies, to Intervention Strategy Development. Int J Mol Sci 2022; 23:ijms231810622. [PMID: 36142521 PMCID: PMC9505475 DOI: 10.3390/ijms231810622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 09/08/2022] [Accepted: 09/09/2022] [Indexed: 11/16/2022] Open
Abstract
Sympathetic nerve activity (SNA) regulates the contraction of vascular smooth muscle and leads to a change in arterial blood pressure (BP). It was observed that SNA, vascular contractility, and BP are heightened in patients with peripheral artery disease (PAD) during exercise. The exercise pressor reflex (EPR), a neural mechanism responsible for BP response to activation of muscle afferent nerve, is a determinant of the exaggerated exercise-induced BP rise in PAD. Based on recent results obtained from a series of studies in PAD patients and a rat model of PAD, this review will shed light on SNA-driven BP response and the underlying mechanisms by which receptors and molecular mediators in muscle afferent nerves mediate the abnormalities in autonomic activities of PAD. Intervention strategies, particularly non-pharmacological strategies, improving the deleterious exercise-induced SNA and BP in PAD, and enhancing tolerance and performance during exercise will also be discussed.
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9
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Foster VS, Rash LD, King GF, Rank MM. Acid-Sensing Ion Channels: Expression and Function in Resident and Infiltrating Immune Cells in the Central Nervous System. Front Cell Neurosci 2021; 15:738043. [PMID: 34602982 PMCID: PMC8484650 DOI: 10.3389/fncel.2021.738043] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 08/30/2021] [Indexed: 11/15/2022] Open
Abstract
Peripheral and central immune cells are critical for fighting disease, but they can also play a pivotal role in the onset and/or progression of a variety of neurological conditions that affect the central nervous system (CNS). Tissue acidosis is often present in CNS pathologies such as multiple sclerosis, epileptic seizures, and depression, and local pH is also reduced during periods of ischemia following stroke, traumatic brain injury, and spinal cord injury. These pathological increases in extracellular acidity can activate a class of proton-gated channels known as acid-sensing ion channels (ASICs). ASICs have been primarily studied due to their ubiquitous expression throughout the nervous system, but it is less well recognized that they are also found in various types of immune cells. In this review, we explore what is currently known about the expression of ASICs in both peripheral and CNS-resident immune cells, and how channel activation during pathological tissue acidosis may lead to altered immune cell function that in turn modulates inflammatory pathology in the CNS. We identify gaps in the literature where ASICs and immune cell function has not been characterized, such as neurotrauma. Knowledge of the contribution of ASICs to immune cell function in neuropathology will be critical for determining whether the therapeutic benefits of ASIC inhibition might be due in part to an effect on immune cells.
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Affiliation(s)
- Victoria S. Foster
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
| | - Lachlan D. Rash
- School of Biomedical Sciences, The University of Queensland, St Lucia, QLD, Australia
| | - Glenn F. King
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, St Lucia, QLD, Australia
| | - Michelle M. Rank
- Anatomy and Physiology, Medicine, Dentistry and Health Sciences, The University of Melbourne, Melbourne, VIC, Australia
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10
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Okada Y, Sato-Numata K, Sabirov RZ, Numata T. Cell Death Induction and Protection by Activation of Ubiquitously Expressed Anion/Cation Channels. Part 2: Functional and Molecular Properties of ASOR/PAC Channels and Their Roles in Cell Volume Dysregulation and Acidotoxic Cell Death. Front Cell Dev Biol 2021; 9:702317. [PMID: 34307382 PMCID: PMC8299559 DOI: 10.3389/fcell.2021.702317] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 06/18/2021] [Indexed: 12/18/2022] Open
Abstract
For survival and functions of animal cells, cell volume regulation (CVR) is essential. Major hallmarks of necrotic and apoptotic cell death are persistent cell swelling and shrinkage, and thus they are termed the necrotic volume increase (NVI) and the apoptotic volume decrease (AVD), respectively. A number of ubiquitously expressed anion and cation channels play essential roles not only in CVR but also in cell death induction. This series of review articles address the question how cell death is induced or protected with using ubiquitously expressed ion channels such as swelling-activated anion channels, acid-activated anion channels, and several types of TRP cation channels including TRPM2 and TRPM7. In the Part 1, we described the roles of swelling-activated VSOR/VRAC anion channels. Here, the Part 2 focuses on the roles of the acid-sensitive outwardly rectifying (ASOR) anion channel, also called the proton-activated chloride (PAC) anion channel, which is activated by extracellular protons in a manner sharply dependent on ambient temperature. First, we summarize phenotypical properties, the molecular identity, and the three-dimensional structure of ASOR/PAC. Second, we highlight the unique roles of ASOR/PAC in CVR dysfunction and in the induction of or protection from acidotoxic cell death under acidosis and ischemic conditions.
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Affiliation(s)
- Yasunobu Okada
- National Institute for Physiological Sciences (NIPS), Okazaki, Japan.,Department of Physiology, School of Medicine, Aichi Medical University, Nagakute, Japan.,Department of Physiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Kaori Sato-Numata
- Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan.,Japan Society for the Promotion of Science, Tokyo, Japan
| | - Ravshan Z Sabirov
- Laboratory of Molecular Physiology, Institute of Biophysics and Biochemistry, National University of Uzbekistan, Tashkent, Uzbekistan
| | - Tomohiro Numata
- Department of Physiology, School of Medicine, Fukuoka University, Fukuoka, Japan
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11
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Dale N. CO 2 sensing by connexin26 and its role in the control of breathing. Interface Focus 2021; 11:20200029. [PMID: 33633831 PMCID: PMC7898151 DOI: 10.1098/rsfs.2020.0029] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2020] [Indexed: 12/14/2022] Open
Abstract
Breathing is essential to provide the O2 required for metabolism and to remove its inevitable CO2 by-product. The rate and depth of breathing is controlled to regulate the excretion of CO2 to maintain the pH of arterial blood at physiological values. A widespread consensus is that chemosensory cells in the carotid body and brainstem measure blood and tissue pH and adjust the rate of breathing to ensure its homeostatic regulation. In this review, I shall consider the evidence that underlies this consensus and highlight historical data indicating that direct sensing of CO2 also plays a significant role in the regulation of breathing. I shall then review work from my laboratory that provides a molecular mechanism for the direct detection of CO2 via the gap junction protein connexin26 (Cx26) and demonstrates the contribution of this mechanism to the chemosensory regulation of breathing. As there are many pathological mutations of Cx26 in humans, I shall discuss which of these alter the CO2 sensitivity of Cx26 and the extent to which these mutations could affect human breathing. I finish by discussing the evolution of the CO2 sensitivity of Cx26 and its link to the evolution of amniotes.
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Affiliation(s)
- Nicholas Dale
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
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12
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Numata T, Sato-Numata K, Okada Y. TRPM7 is involved in acid-induced necrotic cell death in a manner sensitive to progesterone in human cervical cancer cells. Physiol Rep 2020; 7:e14157. [PMID: 31293101 PMCID: PMC6640595 DOI: 10.14814/phy2.14157] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 06/10/2019] [Accepted: 06/10/2019] [Indexed: 12/31/2022] Open
Abstract
Because intravaginal pH is strongly acidic, it is important to investigate the effects of acidosis on cervical cancer cells. Recently, in response to strong acidosis, human cervical cancer HeLa cells were shown to exhibit necrosis after showing persistent cell swelling induced by Cl− influx. Since cation influx should be accompanied with Cl− influx to drive water inflow causing cell swelling, we here studied on the nature of acidotoxic cation conductance. The mRNA/protein expression was assessed by RT‐PCR and Western blotting. Ionic currents were measured by patch‐clamping techniques. Cell counting/viability and colorimetric assays were applied to assess proliferation rate and caspase 3/7 activity, respectively. Cell volume and size were measured by electronic sizing and video‐microscopic measurements, respectively. Acid exposure enhanced TRPM7 activity endogenously expressed in HeLa cells and exogenously overexpressed in HEK293T cells. Gene silencing of TRPM7 abolished acid‐induced cell swelling and necrosis but rather induced activation of apoptotic caspase 3/7 in HeLa cells. Overexpression with the pore charge‐neutralizing D1054A mutant suppressed acid‐enhanced cation currents, acid‐induced cell swelling, and acidotoxic necrosis in HEK293T cells. Progesterone treatment was surprisingly found to suppress molecular and functional expression of TRPM7 and cell proliferation in HeLa cells. Furthermore, in the progesterone‐treated cells, acid exposure did not induce persistent cell swelling followed by necrosis but induced persistent cell shrinkage and apoptotic cell death. These results indicate that in the human cervical cancer cells, TRPM7 is essentially involved in acidotoxic necrotic cell death, and progesterone inhibits TRPM7 expression thereby inhibiting acidotoxic necrosis by switching to apoptosis.
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Affiliation(s)
- Tomohiro Numata
- Department of Physiology, Graduate School of Medical Sciences, Fukuoka University, Fukuoka, Japan
| | | | - Yasunobu Okada
- Department of Molecular Cell Physiology, Kyoto Prefectural University of Medicine, Kyoto, Japan.,Department of Cell Physiology, National Institute for Physiological Sciences, Okazaki, Japan
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13
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Ji MJ, Hong JH. An overview of carbonic anhydrases and membrane channels of synoviocytes in inflamed joints. J Enzyme Inhib Med Chem 2020; 34:1615-1622. [PMID: 31480869 PMCID: PMC6735303 DOI: 10.1080/14756366.2019.1659791] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The highly aggressive fibroblast-like synoviocytes (FLSs) are inflammatory mediators involved in synovial joint destruction. Membrane channels and transporters are essential components of the cell migration apparatus and are involved in various cellular functions. Although evidence is emerging that cell migration is a physiological/pathological process, the mechanism of highly dynamic synoviocytes linked to the membrane channels and carbonic anhydrases (CAs) in inflamed joints is only partially understood. In this review, topics covered will give a brief overview of CAs and the membrane channels of synoviocytes. We have also systematically focused on the role of FLS channels and transporters under various conditions, including rheumatoid arthritis (RA), to understand the pathophysiology of the migration of synoviocytes as inflammatory mediators in joints.
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Affiliation(s)
- Min Jeong Ji
- Department of Physiology, College of Medicine, Gachon University, Lee Gil Ya Cancer and Diabetes Institute , Incheon , South Korea
| | - Jeong Hee Hong
- Department of Physiology, College of Medicine, Gachon University, Lee Gil Ya Cancer and Diabetes Institute , Incheon , South Korea
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14
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Sørensen LB, Gazerani P, Graven-Nielsen T. Nerve growth factor-induced muscle hyperalgesia facilitates ischaemic contraction-evoked pain. Eur J Pain 2019; 23:1814-1825. [PMID: 31314952 DOI: 10.1002/ejp.1455] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 07/01/2019] [Accepted: 07/10/2019] [Indexed: 02/03/2023]
Abstract
BACKGROUND Intramuscular injection of Nerve Growth Factor (NGF) may influence the responsiveness of active chemo-sensitive channels affecting muscle pain sensitivity. This double-blinded crossover study in healthy humans assessed contraction-evoked pain responses and pain sensitivity during acute ischaemia in the tibialis anterior (TA) muscle before and 24 hr after five distributed NGF injections (1 µg, 4 cm interval) compared with control injections (isotonic-saline). METHODS Twenty-one subjects participated in two experimental phases, each including five sessions over 7 days, with a gap of 4 weeks in-between. Muscle pain intensity evoked with daily functional tasks (Likert scale score) was collected using a paper diary. Pain intensity evoked by ischaemic and non-ischaemic contractions numerical rating scale (NRS) was collected at Day0 and Day1. Pressure pain thresholds (PPTs) on the TA were recorded before (Day0), 3 hr, 1, 3, and 7 days post-injection, and after the ischaemic-contractions and post-cuff deflation at Day0 and Day1. RESULTS Increased Likert scores of pain were present for 7 days after NGF compared to control injections (p < .05). Higher NRS pain scores of ischaemic-contractions were seen when contracting the muscle injected with NGF compared to baseline (p = .003) and control (p = .012). Pain during non-ischaemic contractions was not significantly affected by NGF injections. Decreased PPTs were found at 3 hr, Day1 and Day3 post-injection (p < .05) in both conditions. Compared with pre-contractions, PPTs were increased following ischaemic contractions at Day0 (p < .05) and Day1 (p < .05) in both conditions. CONCLUSION This study showed that ischaemic contraction-evoked pain was facilitated in an NGF-sensitized muscle. SIGNIFICANCE Acidification of the muscle environment may affect muscle nociceptors and pain by different mechanisms, including activation of ASIC3 and TRPV1. In this study, pain evoked following ischaemic contractions was increased in the Nerve Growth Factor (NGF)-sensitized muscle compared with non-ischaemic contractions and in the non-sensitized muscle. These findings illustrate that responses of peripheral afferents under ischaemic conditions are altered by a pre-sensitized muscle. This highlights the role of growth factors, including NGF, in peripheral muscle sensitization with clinical implications for ischaemic myalgia.
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Affiliation(s)
- Line Bay Sørensen
- Center for Neuroplasticity and Pain (CNAP), SMI, Faculty of Medicine, Aalborg University, Aalborg, Denmark
| | - Parisa Gazerani
- Biomedicine, Department of Health Science and Technology, Faculty of Medicine, Aalborg University, Aalborg, Denmark
| | - Thomas Graven-Nielsen
- Center for Neuroplasticity and Pain (CNAP), SMI, Faculty of Medicine, Aalborg University, Aalborg, Denmark
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15
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Glitsch M. Mechano- and pH-sensing convergence on Ca 2+-mobilising proteins - A recipe for cancer? Cell Calcium 2019; 80:38-45. [PMID: 30952068 DOI: 10.1016/j.ceca.2019.03.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Revised: 03/27/2019] [Accepted: 03/27/2019] [Indexed: 02/06/2023]
Abstract
Alterations in the (bio)chemical and physical microenvironment of cells accompany and often promote disease formation and progression. This is particularly well established for solid cancers, which are typically stiffer than the healthy tissue in which they arise, and often display profound acidification of their interstitial fluid. Cell surface receptors can sense changes in the mechanical and (bio)chemical properties of the surrounding extracellular matrix and fluid, and signalling through these receptors is thought to play a key role in disease development and advancement. This review will look at ion channels and G protein coupled receptors that are activated by mechanical cues and extracellular acidosis, and stimulation of which results in increases in intracellular Ca2+ concentrations. Cellular Ca2+ levels are dysregulated in cancer as well as cancer-associated cells, and mechano- and proton-sensing proteins likely contribute to these aberrant intracellular Ca2+ signals, making them attractive targets for therapeutic intervention.
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Affiliation(s)
- Maike Glitsch
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
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16
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Abstract
A large series of different ion channels have been identified and investigated as potential targets for new medicines for the treatment of a variety of human diseases, including pain. Among these channels, the voltage gated calcium channels (VGCC) are inhibited by drugs for the treatment of migraine, neuropathic pain or intractable pain. Transient receptor potential (TRP) channels are emerging as important pain transducers as they sense low pH media or oxidative stress and other mediators and are abundantly found at sites of inflammation or tissue injury. Low pH may also activate acid sensing ion channels (ASIC) and mechanical forces stimulate the PIEZO channels. While potent agonists of TRP channels due to their desensitizing action on pain transmission are used as topical applications, the potential of TRP antagonists as pain therapeutics remains an exciting field of investigation. The study of ASIC or PIEZO channels in pain signaling is in an early stage, whereas antagonism of the purinergic P2X3 channels has been reported to provide beneficial effects in chronic intractable cough. The present chapter covers these intriguing channels in great detail, highlighting their diverse mechanisms and broad potential for therapeutic utility.
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Affiliation(s)
- Francesco De Logu
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy
| | - Pierangelo Geppetti
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, Florence, Italy.
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17
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Castillo K, Diaz-Franulic I, Canan J, Gonzalez-Nilo F, Latorre R. Thermally activated TRP channels: molecular sensors for temperature detection. Phys Biol 2018; 15:021001. [PMID: 29135465 DOI: 10.1088/1478-3975/aa9a6f] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Temperature sensing is one of the oldest capabilities of living organisms, and is essential for sustaining life, because failure to avoid extreme noxious temperatures can result in tissue damage or death. A subset of members of the transient receptor potential (TRP) ion channel family is finely tuned to detect temperatures ranging from extreme cold to noxious heat, giving rise to thermoTRP channels. Structural and functional experiments have shown that thermoTRP channels are allosteric proteins, containing different domains that sense changes in temperature, among other stimuli, triggering pore opening. Although temperature-dependence is well characterized in thermoTRP channels, the molecular nature of temperature-sensing elements remains unknown. Importantly, thermoTRP channels are involved in pain sensation, related to pathological conditions. Here, we provide an overview of thermoTRP channel activation. We also discuss the structural and functional evidence supporting the existence of an intrinsic temperature sensor in this class of channels, and we explore the basic thermodynamic principles for channel activation. Finally, we give a view of their role in painful pathophysiological conditions.
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Affiliation(s)
- Karen Castillo
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso 2366103, Chile. www.cinv.cl
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18
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Stankowska DL, Mueller BH, Oku H, Ikeda T, Dibas A. Neuroprotective effects of inhibitors of Acid-Sensing ion channels (ASICs) in optic nerve crush model in rodents. Curr Eye Res 2017; 43:84-95. [PMID: 29111855 DOI: 10.1080/02713683.2017.1383442] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
PURPOSE The purpose of the current study was to assess the potential involvement of acid-sensing ion channel 1 (ASIC1) in retinal ganglion cell (RGC) death and investigate the neuroprotective effects of inhibitors of ASICs in promoting RGC survival following optic nerve crush (ONC). RESULTS ASIC1 protein was significantly increased in optic nerve extracts at day 7 following ONC in rats. Activated calpain-1 increased at 2 and 7 days following ONC as evidenced by increased degradation of α-fodrin, known substrate of calpain. Glial fibrillary acidic protein levels increased significantly at 2 and 7 days post-injury. By contrast, glutamine synthetase increased at 2 days while decreased at 7 days. The inhibition of ASICs with amiloride and psalmotoxin-1 significantly increased RGC survival in rats following ONC (p < 0.05, one-way ANOVA). The mean number of surviving RGCs in rats (n = 6) treated with amiloride (100 µM) following ONC was 1477 ± 98 cells/mm2 compared with ONC (1126 ± 101 cells/mm2), where psalmotoxin-1 (1 μM) treated rats (n = 6) and subjected to ONC had 1441 ± 63 RGCs/mm2 compared with ONC (1065 ± 76 RGCs/mm2). Average number of RGCs in control rats (n = 12) was 2092 ± 46 cells/mm2. Blocking of ASICs also significantly increased RGC survival from ischemic-like insult from 473 ± 80 to 842 ± 49 RGCs/mm2 (for psalmotoxin-1) and from 628 ± 53 RGCs/mm2 to 890 ± 55 RGCs/mm2 (for amiloride) with p ≤ 0.05, using one-way ANOVA. Acidification (a known activator of ASIC1) increased intracellular Ca2+ ([Ca2+]i) in rat primary RGCs, which was statistically blocked by pretreatment with 100 nM psalmotoxin-1. CONCLUSIONS ASIC1 up-regulation-induced influx of extracellular calcium may be responsible for activation of calcium-sensitive calpain-1 in the retina. Calpain-1 induced degradation of α-fodrin and leads to morphological changes and eventually neuronal death. Therefore, blockers of ASIC1 can be used as potential therapeutics in the treatment of optic nerve degeneration. ABBREVIATIONS 4-(2-Aminoethyl) benzenesulfonyl fluoride hydrochloride (AEBSF); acid-sensing ion channels (ASICs); analysis of variance (ANOVA); bicinchoninic acid (BCA); brain-derived neurotrophic factor (BDNF); central nervous system (CNS); ciliary neurotrophic factor (CNTF); dimethyl sulfoxide (DMSO); endoplasmic reticulum (ER); ethylene glycol-bis(β-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA); ethylenediaminetetraacetic acid (EDTA); Food and Drug Administration (FDA); glial fibrillary acidic protein (GFAP); glutamine synthetase (GS); intraocular pressure (IOP); kilodalton (kDa); Krebs-Ringer Buffer (KRB); optic nerve crush (ONC); phosphate-buffered saline (PBS); plasma membrane (PM); polymerase chain reaction (PCR); retinal ganglion cell (RGC); RNA Binding Protein With Multiple Splicing (RBPMS); room temperature (RT); standard error of the mean (SEM).
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Affiliation(s)
- Dorota L Stankowska
- a North Texas Eye Research Institute , University of North Texas Health Science Center , Fort Worth
| | - Brett H Mueller
- a North Texas Eye Research Institute , University of North Texas Health Science Center , Fort Worth
| | - Hidehiro Oku
- b Department of Ophthalmology , Osaka Medical College , Takatsuki Osaka , Japan
| | - Tsunehiko Ikeda
- b Department of Ophthalmology , Osaka Medical College , Takatsuki Osaka , Japan
| | - Adnan Dibas
- a North Texas Eye Research Institute , University of North Texas Health Science Center , Fort Worth
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Czikora I, Alli AA, Sridhar S, Matthay MA, Pillich H, Hudel M, Berisha B, Gorshkov B, Romero MJ, Gonzales J, Wu G, Huo Y, Su Y, Verin AD, Fulton D, Chakraborty T, Eaton DC, Lucas R. Epithelial Sodium Channel-α Mediates the Protective Effect of the TNF-Derived TIP Peptide in Pneumolysin-Induced Endothelial Barrier Dysfunction. Front Immunol 2017; 8:842. [PMID: 28785264 PMCID: PMC5519615 DOI: 10.3389/fimmu.2017.00842] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 07/04/2017] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Streptococcus pneumoniae is a major etiologic agent of bacterial pneumonia. Autolysis and antibiotic-mediated lysis of pneumococci induce release of the pore-forming toxin, pneumolysin (PLY), their major virulence factor, which is a prominent cause of acute lung injury. PLY inhibits alveolar liquid clearance and severely compromises alveolar-capillary barrier function, leading to permeability edema associated with pneumonia. As a consequence, alveolar flooding occurs, which can precipitate lethal hypoxemia by impairing gas exchange. The α subunit of the epithelial sodium channel (ENaC) is crucial for promoting Na+ reabsorption across Na+-transporting epithelia. However, it is not known if human lung microvascular endothelial cells (HL-MVEC) also express ENaC-α and whether this subunit is involved in the regulation of their barrier function. METHODS The presence of α, β, and γ subunits of ENaC and protein phosphorylation status in HL-MVEC were assessed in western blotting. The role of ENaC-α in monolayer resistance of HL-MVEC was examined by depletion of this subunit by specific siRNA and by employing the TNF-derived TIP peptide, a specific activator that directly binds to ENaC-α. RESULTS HL-MVEC express all three subunits of ENaC, as well as acid-sensing ion channel 1a (ASIC1a), which has the capacity to form hybrid non-selective cation channels with ENaC-α. Both TIP peptide, which specifically binds to ENaC-α, and the specific ASIC1a activator MitTx significantly strengthened barrier function in PLY-treated HL-MVEC. ENaC-α depletion significantly increased sensitivity to PLY-induced hyperpermeability and in addition, blunted the protective effect of both the TIP peptide and MitTx, indicating an important role for ENaC-α and for hybrid NSC channels in barrier function of HL-MVEC. TIP peptide blunted PLY-induced phosphorylation of both calmodulin-dependent kinase II (CaMKII) and of its substrate, the actin-binding protein filamin A (FLN-A), requiring the expression of both ENaC-α and ASIC1a. Since non-phosphorylated FLN-A promotes ENaC channel open probability and blunts stress fiber formation, modulation of this activity represents an attractive target for the protective actions of ENaC-α in both barrier function and liquid clearance. CONCLUSION Our results in cultured endothelial cells demonstrate a previously unrecognized role for ENaC-α in strengthening capillary barrier function that may apply to the human lung. Strategies aiming to activate endothelial NSC channels that contain ENaC-α should be further investigated as a novel approach to improve barrier function in the capillary endothelium during pneumonia.
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Affiliation(s)
- Istvan Czikora
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Abdel A Alli
- Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, FL, United States.,Division of Nephrology, Hypertension, and Renal Transplantation, Department of Medicine, University of Florida College of Medicine, Gainesville, FL, United States
| | - Supriya Sridhar
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Michael A Matthay
- Cardiovascular Research Institute, UCSF, San Francisco, CA, United States
| | - Helena Pillich
- Institute for Medical Microbiology, Justus-Liebig University, Giessen, Germany
| | - Martina Hudel
- Institute for Medical Microbiology, Justus-Liebig University, Giessen, Germany
| | - Besim Berisha
- Institute for Medical Microbiology, Justus-Liebig University, Giessen, Germany
| | - Boris Gorshkov
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Maritza J Romero
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA, United States.,Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Joyce Gonzales
- Department of Medicine, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Guangyu Wu
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Yuqing Huo
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA, United States.,Department of Medicine, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Yunchao Su
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Alexander D Verin
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA, United States.,Department of Medicine, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - David Fulton
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA, United States.,Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Trinad Chakraborty
- Institute for Medical Microbiology, Justus-Liebig University, Giessen, Germany
| | - Douglas C Eaton
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
| | - Rudolf Lucas
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA, United States.,Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA, United States.,Department of Medicine, Medical College of Georgia, Augusta University, Augusta, GA, United States
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20
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Keating JJ, Imbrogno J, Belfort G. Polymer Brushes for Membrane Separations: A Review. ACS APPLIED MATERIALS & INTERFACES 2016; 8:28383-28399. [PMID: 27709877 DOI: 10.1021/acsami.6b09068] [Citation(s) in RCA: 102] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The fundamentals and applications of polymer brush-modified membranes are reviewed. This new class of synthetic membranes is explored with an emphasis on tuning the membrane performance through polymer brush grafting. This work highlights the intriguing performance characteristics of polymer brush-modified membranes in a variety of separations. Polymer brushes are a versatile and effective means in designing membranes for applications in protein adsorption and purification, colloid stabilization, sensors, water purification, pervaporation of organic compounds, gas separations, and as stimuli responsive materials.
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Affiliation(s)
- John J Keating
- Department of Chemical and Biological Engineering and Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Joseph Imbrogno
- Department of Chemical and Biological Engineering and Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Georges Belfort
- Department of Chemical and Biological Engineering and Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
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21
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Li MH, Leng TD, Feng XC, Yang T, Simon RP, Xiong ZG. Modulation of Acid-sensing Ion Channel 1a by Intracellular pH and Its Role in Ischemic Stroke. J Biol Chem 2016; 291:18370-83. [PMID: 27402850 DOI: 10.1074/jbc.m115.713636] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Indexed: 12/24/2022] Open
Abstract
An important contributor to brain ischemia is known to be extracellular acidosis, which activates acid-sensing ion channels (ASICs), a family of proton-gated sodium channels. Lines of evidence suggest that targeting ASICs may lead to novel therapeutic strategies for stroke. Investigations of the role of ASICs in ischemic brain injury have naturally focused on the role of extracellular pH in ASIC activation. By contrast, intracellular pH (pHi) has received little attention. This is a significant gap in our understanding because the ASIC response to extracellular pH is modulated by pHi, and activation of ASICs by extracellular protons is paradoxically enhanced by intracellular alkalosis. Our previous studies show that acidosis-induced cell injury in in vitro models is attenuated by intracellular acidification. However, whether pHi affects ischemic brain injury in vivo is completely unknown. Furthermore, whereas ASICs in native neurons are composed of different subunits characterized by distinct electrophysiological/pharmacological properties, the subunit-dependent modulation of ASIC activity by pHi has not been investigated. Using a combination of in vitro and in vivo ischemic brain injury models, electrophysiological, biochemical, and molecular biological approaches, we show that the intracellular alkalizing agent quinine potentiates, whereas the intracellular acidifying agent propionate inhibits, oxygen-glucose deprivation-induced cell injury in vitro and brain ischemia-induced infarct volume in vivo Moreover, we find that the potentiation of ASICs by quinine depends on the presence of the ASIC1a, ASIC2a subunits, but not ASIC1b, ASIC3 subunits. Furthermore, we have determined the amino acids in ASIC1a that are involved in the modulation of ASICs by pHi.
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Affiliation(s)
- Ming-Hua Li
- From the Department of Neurological Surgery, Oregon Health and Science University, Portland, Oregon 97239,
| | - Tian-Dong Leng
- the Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia 30310, and
| | - Xue-Chao Feng
- the Key Laboratory of Molecular Epigenetics of Ministry of Education, Institute of Cytology and Genetics, Northeast Normal University, 130000 Changchun, China
| | - Tao Yang
- the Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia 30310, and
| | - Roger P Simon
- the Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia 30310, and
| | - Zhi-Gang Xiong
- the Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, Georgia 30310, and
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22
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Duzhyy DE, Viatchenko-Karpinski VY, Khomula EV, Voitenko NV, Belan PV. Upregulation of T-type Ca2+ channels in long-term diabetes determines increased excitability of a specific type of capsaicin-insensitive DRG neurons. Mol Pain 2015; 11:29. [PMID: 25986602 PMCID: PMC4490764 DOI: 10.1186/s12990-015-0028-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 05/13/2015] [Indexed: 01/15/2023] Open
Abstract
Background Previous studies have shown that increased excitability of capsaicin-sensitive DRG neurons and thermal hyperalgesia in rats with short-term (2–4 weeks) streptozotocin-induced diabetes is mediated by upregulation of T-type Ca2+ current. In longer–term diabetes (after the 8th week) thermal hyperalgesia is changed to hypoalgesia that is accompanied by downregulation of T-type current in capsaicin-sensitive small-sized nociceptors. At the same time pain symptoms of diabetic neuropathy other than thermal persist in STZ-diabetic animals and patients during progression of diabetes into later stages suggesting that other types of DRG neurons may be sensitized and contribute to pain. In this study, we examined functional expression of T-type Ca2+ channels in capsaicin-insensitive DRG neurons and excitability of these neurons in longer-term diabetic rats and in thermally hypoalgesic diabetic rats. Results Here we have demonstrated that in STZ-diabetes T-type current was upregulated in capsaicin-insensitive low-pH-sensitive small-sized nociceptive DRG neurons of longer-term diabetic rats and thermally hypoalgesic diabetic rats. This upregulation was not accompanied by significant changes in biophysical properties of T-type channels suggesting that a density of functionally active channels was increased. Sensitivity of T-type current to amiloride (1 mM) and low concentration of Ni2+ (50 μM) implicates prevalence of Cav3.2 subtype of T-type channels in the capsaicin-insensitive low-pH-sensitive neurons of both naïve and diabetic rats. The upregulation of T-type channels resulted in the increased neuronal excitability of these nociceptive neurons revealed by a lower threshold for action potential initiation, prominent afterdepolarizing potentials and burst firing. Sodium current was not significantly changed in these neurons during long-term diabetes and could not contribute to the diabetes-induced increase of neuronal excitability. Conclusions Capsaicin-insensitive low-pH-sensitive type of DRG neurons shows diabetes-induced upregulation of Cav3.2 subtype of T-type channels. This upregulation results in the increased excitability of these neurons and may contribute to nonthermal nociception at a later-stage diabetes.
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Affiliation(s)
- Dmytro E Duzhyy
- Department of General Physiology of the CNS and State Key Laboratory of Molecular and Cellular Biology, Bogomoletz Institute of Physiology of National Academy of Science of Ukraine, 4 Bogomoletz street, 01024, Kyiv, Ukraine.
| | - Viacheslav Y Viatchenko-Karpinski
- Department of General Physiology of the CNS and State Key Laboratory of Molecular and Cellular Biology, Bogomoletz Institute of Physiology of National Academy of Science of Ukraine, 4 Bogomoletz street, 01024, Kyiv, Ukraine.
| | - Eugen V Khomula
- International Center of Molecular Physiology of National Academy of Science of Ukraine, 4 Bogomoletz street, 01024, Kyiv, Ukraine.
| | - Nana V Voitenko
- Department of General Physiology of the CNS and State Key Laboratory of Molecular and Cellular Biology, Bogomoletz Institute of Physiology of National Academy of Science of Ukraine, 4 Bogomoletz street, 01024, Kyiv, Ukraine.
| | - Pavel V Belan
- Department of General Physiology of the CNS and State Key Laboratory of Molecular and Cellular Biology, Bogomoletz Institute of Physiology of National Academy of Science of Ukraine, 4 Bogomoletz street, 01024, Kyiv, Ukraine.
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Gao S, Yu Y, Ma ZY, Sun H, Zhang YL, Wang XT, Wang C, Fan WM, Zheng QY, Ma CL. NMDAR-Mediated Hippocampal Neuronal Death is Exacerbated by Activities of ASIC1a. Neurotox Res 2015; 28:122-37. [PMID: 25947342 DOI: 10.1007/s12640-015-9530-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 03/31/2015] [Accepted: 04/18/2015] [Indexed: 12/15/2022]
Abstract
NMDARs and ASIC1a both exist in central synapses and mediate important physiological and pathological conditions, but the functional relationship between them is unclear. Here we report several novel findings that may shed light on the functional relationship between these two ion channels in the excitatory postsynaptic membrane of mouse hippocampus. Firstly, NMDAR activation induced by either NMDA or OGD led to increased [Ca(2+)](i)and greater apoptotic and necrotic cell deaths in cultured hippocampal neurons; these cell deaths were prevented by application of NMDAR antagonists. Secondly, ASIC1a activation induced by pH 6.0 extracellular solution (ECS) showed similar increases in apoptotic and necrotic cell deaths; these cell deaths were prevented by ASIC1a antagonists, and also by NMDAR antagonists. Since increased [Ca(2+)](i)leads to increased cell deaths and since NMDAR exhibits much greater calcium permeability than ASIC1a, these data suggest that ASIC1a-induced neuronal death is mediated through activation of NMDARs. Thirdly, treatment of hippocampal cultures with both NMDA and acidic ECS induced greater degrees of cell deaths than either NMDA or acidic ECS treatment alone. These results suggest that ASIC1a activation up-regulates NMDAR function. Additional data supporting the functional relationship between ASIC1a and NMDAR are found in our electrophysiology experiments in hippocampal slices, where stimulation of ASIC1a induced a marked increase in NMDAR EPSC amplitude, and inhibition of ASIC1a resulted in a decrease in NMDAR EPSC amplitude. In summary, we present evidence that ASIC1a activity facilitates NMDAR function and exacerbates NMDAR-mediated neuronal death in pathological conditions. These findings are invaluable to the search for novel therapeutic targets in the treatment of brain ischemia.
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Affiliation(s)
- Su Gao
- Department of Physiology, Binzhou Medical University, Yantai Campus, 346 Guanhai Road, Laishan District, Yantai, 264003, Shandong, China
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24
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Burkhardt R, Hämmerle CH, Lang NP. Self-reported pain perception of patients after mucosal graft harvesting in the palatal area. J Clin Periodontol 2015; 42:281-7. [PMID: 25544993 DOI: 10.1111/jcpe.12357] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/11/2014] [Indexed: 10/24/2022]
Affiliation(s)
- Rino Burkhardt
- The University of Hong Kong; Prince Philip Dental Hospital; Hong Kong SAR China
- University of Zurich; Switzerland
| | | | - Niklaus P. Lang
- The University of Hong Kong; Prince Philip Dental Hospital; Hong Kong SAR China
- University of Zurich; Switzerland
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25
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Analgesic therapy for major spine surgery. Neurosurg Rev 2015; 38:407-18; discussion 419. [DOI: 10.1007/s10143-015-0605-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 07/13/2014] [Accepted: 11/16/2014] [Indexed: 12/11/2022]
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26
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Jin C, Ye QH, Yuan FL, Gu YL, Li JP, Shi YH, Shen XM, Bo-Liu, Lin ZH. Involvement of acid-sensing ion channel 1α in hepatic carcinoma cell migration and invasion. Tumour Biol 2015; 36:4309-17. [DOI: 10.1007/s13277-015-3070-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 01/08/2015] [Indexed: 01/01/2023] Open
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Holzer P. Acid-sensing ion channels in gastrointestinal function. Neuropharmacology 2015; 94:72-9. [PMID: 25582294 DOI: 10.1016/j.neuropharm.2014.12.009] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 11/21/2014] [Accepted: 12/04/2014] [Indexed: 12/15/2022]
Abstract
Gastric acid is of paramount importance for digestion and protection from pathogens but, at the same time, is a threat to the integrity of the mucosa in the upper gastrointestinal tract and may give rise to pain if inflammation or ulceration ensues. Luminal acidity in the colon is determined by lactate production and microbial transformation of carbohydrates to short chain fatty acids as well as formation of ammonia. The pH in the oesophagus, stomach and intestine is surveyed by a network of acid sensors among which acid-sensing ion channels (ASICs) and acid-sensitive members of transient receptor potential ion channels take a special place. In the gut, ASICs (ASIC1, ASIC2, ASIC3) are primarily expressed by the peripheral axons of vagal and spinal afferent neurons and are responsible for distinct proton-gated currents in these neurons. ASICs survey moderate decreases in extracellular pH and through these properties contribute to a protective blood flow increase in the face of mucosal acid challenge. Importantly, experimental studies provide increasing evidence that ASICs contribute to gastric acid hypersensitivity and pain under conditions of gastritis and peptic ulceration but also participate in colonic hypersensitivity to mechanical stimuli (distension) under conditions of irritation that are not necessarily associated with overt inflammation. These functional implications and their upregulation by inflammatory and non-inflammatory pathologies make ASICs potential targets to manage visceral hypersensitivity and pain associated with functional gastrointestinal disorders. This article is part of the Special Issue entitled 'Acid-Sensing Ion Channels in the Nervous System'.
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Affiliation(s)
- Peter Holzer
- Research Unit of Translational Neurogastroenterology, Institute of Experimental and Clinical Pharmacology, Medical University of Graz, Universitätsplatz 4, A-8010 Graz, Austria.
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Maza E, Tuninetti JS, Politakos N, Knoll W, Moya S, Azzaroni O. pH-responsive ion transport in polyelectrolyte multilayers of poly(diallyldimethylammonium chloride) (PDADMAC) and poly(4-styrenesulfonic acid-co-maleic acid) (PSS-MA) bearing strong- and weak anionic groups. Phys Chem Chem Phys 2015; 17:29935-48. [DOI: 10.1039/c5cp03965g] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We describe the creation of interfacial architectures displaying pH-dependent ionic transport properties which until now have not been observed in polyelectrolyte multilayers.
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Affiliation(s)
- Eliana Maza
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA)
- Universidad Nacional de La Plata (UNLP)
- CONICET
- (1900) La Plata
- Argentina
| | - Jimena S. Tuninetti
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA)
- Universidad Nacional de La Plata (UNLP)
- CONICET
- (1900) La Plata
- Argentina
| | | | | | - Sergio Moya
- Biosurfaces Unit
- CIC biomaGUNE
- 20009 San Sebastian
- Spain
| | - Omar Azzaroni
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA)
- Universidad Nacional de La Plata (UNLP)
- CONICET
- (1900) La Plata
- Argentina
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Gong W, Kolker SJ, Usachev Y, Walder RY, Boyle DL, Firestein GS, Sluka KA. Acid-sensing ion channel 3 decreases phosphorylation of extracellular signal-regulated kinases and induces synoviocyte cell death by increasing intracellular calcium. Arthritis Res Ther 2014; 16:R121. [PMID: 24923411 PMCID: PMC4095605 DOI: 10.1186/ar4577] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 05/20/2014] [Indexed: 12/14/2022] Open
Abstract
Introduction Acid-sensing ion channel 3 (ASIC3) is expressed in synoviocytes, activated by decreases in pH, and reduces inflammation in animal models of inflammatory arthritis. The purpose of the current study was to characterize potential mechanisms underlying the control of inflammation by ASIC3 in fibroblast-like synoviocytes (FLS). Methods Experiments were performed in cultured FLS from wild-type (WT) and ASIC3-/- mice, ASIC1-/- mice, and people with rheumatoid arthritis. We assessed the effects of acidic pH with and without interleukin-1β on FLS and the role of ASICs in modulating intracellular calcium [Ca2+]i, mitogen activated kinase (MAP kinase) expression, and cell death. [Ca2+]i was assessed by fluorescent calcium imaging, MAP kinases were measured by Western Blots; ASIC, cytokine and protease mRNA expression were measured by quantitative PCR and cell death was measured with a LIVE/DEAD assay. Results Acidic pH increased [Ca2+]i and decreased p-ERK expression in WT FLS; these effects were significantly smaller in ASIC3-/- FLS and were prevented by blockade of [Ca2+]i. Blockade of protein phosphatase 2A (PP2A) prevented the pH-induced decreases in p-ERK. In WT FLS, IL-1β increases ASIC3 mRNA, and when combined with acidic pH enhances [Ca2+]i, p-ERK, IL-6 and metalloprotienase mRNA, and cell death. Inhibitors of [Ca2+]i and ERK prevented cell death induced by pH 6.0 in combination with IL-1β in WT FLS. Conclusions Decreased pH activates ASIC3 resulting in increased [Ca2+]i, and decreased p-ERK. Under inflammatory conditions, acidic pH results in enhanced [Ca2+]i and phosphorylation of extracellular signal-regulated kinase that leads to cell death. Thus, activation of ASIC3 on FLS by acidic pH from an inflamed joint could limit synovial proliferation resulting in reduced accumulation of inflammatory mediators and subsequent joint damage.
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Li MH, Liu SQ, Inoue K, Lan J, Simon RP, Xiong ZG. Acid-sensing ion channels in mouse olfactory bulb M/T neurons. ACTA ACUST UNITED AC 2014; 143:719-31. [PMID: 24821964 PMCID: PMC4035746 DOI: 10.1085/jgp.201310990] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Functional acid-sensing ion channels are present in olfactory bulb neurons and may contribute to normal olfaction. The olfactory bulb contains the first synaptic relay in the olfactory pathway, the sensory system in which odorants are detected enabling these chemical stimuli to be transformed into electrical signals and, ultimately, the perception of odor. Acid-sensing ion channels (ASICs), a family of proton-gated cation channels, are widely expressed in neurons of the central nervous system. However, no direct electrophysiological and pharmacological characterizations of ASICs in olfactory bulb neurons have been described. Using a combination of whole-cell patch-clamp recordings and biochemical and molecular biological analyses, we demonstrated that functional ASICs exist in mouse olfactory bulb mitral/tufted (M/T) neurons and mainly consist of homomeric ASIC1a and heteromeric ASIC1a/2a channels. ASIC activation depolarized cultured M/T neurons and increased their intracellular calcium concentration. Thus, ASIC activation may play an important role in normal olfactory function.
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Affiliation(s)
- Ming-Hua Li
- Department of Neurological Surgery, Oregon Health & Science University, Portland, OR 97239
| | | | - Koichi Inoue
- Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310
| | | | - Roger P Simon
- Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310
| | - Zhi-Gang Xiong
- Department of Neurobiology, Neuroscience Institute, Morehouse School of Medicine, Atlanta, GA 30310
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Proton-sensitive cation channels and ion exchangers in ischemic brain injury: new therapeutic targets for stroke? Prog Neurobiol 2014; 115:189-209. [PMID: 24467911 DOI: 10.1016/j.pneurobio.2013.12.008] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Revised: 11/28/2013] [Accepted: 12/24/2013] [Indexed: 12/13/2022]
Abstract
Ischemic brain injury results from complicated cellular mechanisms. The present therapy for acute ischemic stroke is limited to thrombolysis with the recombinant tissue plasminogen activator (rtPA) and mechanical recanalization. Therefore, a better understanding of ischemic brain injury is needed for the development of more effective therapies. Disruption of ionic homeostasis plays an important role in cell death following cerebral ischemia. Glutamate receptor-mediated ionic imbalance and neurotoxicity have been well established in cerebral ischemia after stroke. However, non-NMDA receptor-dependent mechanisms, involving acid-sensing ion channel 1a (ASIC1a), transient receptor potential melastatin 7 (TRPM7), and Na(+)/H(+) exchanger isoform 1 (NHE1), have recently emerged as important players in the dysregulation of ionic homeostasis in the CNS under ischemic conditions. These H(+)-sensitive channels and/or exchangers are expressed in the majority of cell types of the neurovascular unit. Sustained activation of these proteins causes excessive influx of cations, such as Ca(2+), Na(+), and Zn(2+), and leads to ischemic reperfusion brain injury. In this review, we summarize recent pre-clinical experimental research findings on how these channels/exchangers are regulated in both in vitro and in vivo models of cerebral ischemia. The blockade or transgenic knockdown of these proteins was shown to be neuroprotective in these ischemia models. Taken together, these non-NMDA receptor-dependent mechanisms may serve as novel therapeutic targets for stroke intervention.
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Li J, Xing J, Lu J. Nerve Growth Factor, Muscle Afferent Receptors and Autonomic Responsiveness with Femoral Artery Occlusion. JOURNAL OF MODERN PHYSIOLOGICAL RESEARCH 2014; 1:1-18. [PMID: 25346945 PMCID: PMC4207086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The exercise pressor reflex is a neural control mechanism responsible for the cardiovascular responses to exercise. As exercise is initiated, thin fiber muscle afferent nerves are activated by mechanical and metabolic stimuli arising in the contracting muscles. This leads to reflex increases in arterial blood pressure and heart rate primarily through activation of sympathetic nerve activity (SNA). Studies of humans and animals have indicated that the exercise pressor reflex is exaggerated in a number of cardiovascular diseases. For the last several years, a series of studies have employed a rodent model to examine the mechanisms at receptor and cellular levels by which responses of SNA and blood pressure to static exercise are heightened in peripheral artery disease (PAD), one of the most common cardiovascular disorders. Specifically, femoral artery occlusion is used to study intermittent claudication that is observed in human PAD. Our studies have demonstrated that the receptors on thin fiber muscle afferents including transient receptor potential vanilloid type 1 (TRPV1), purinergic P2X3 and acid sensing ion channel subtype 3 (ASIC3) are engaged in augmented autonomic responses this disease. This review will present some of recent results in regard with several receptors in muscle sensory neurons in contribution to augmented autonomic responses in PAD. We will emphasize the role played by nerve growth factor (NGF) in regulating those sensory receptors in the processing of amplified exercise pressor reflex. Also, we will discuss the role played by hypoxia-inducible facor-1α regarding the enhanced autonomic reflex with femoral artery occlusion. The purpose of this review is to focus on a theme namely that PAD accentuates reflexively autonomic responses to exercise and further address regulatory mechanisms leading to abnormal autonomic responsiveness.
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Affiliation(s)
- Jianhua Li
- Heart & Vascular Institute, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
| | - Jihong Xing
- Heart & Vascular Institute, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
| | - Jian Lu
- Heart & Vascular Institute, Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA
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Khanna A, Kahle KT, Walcott BP, Gerzanich V, Simard JM. Disruption of ion homeostasis in the neurogliovascular unit underlies the pathogenesis of ischemic cerebral edema. Transl Stroke Res 2013; 5:3-16. [PMID: 24323726 DOI: 10.1007/s12975-013-0307-9] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 10/22/2013] [Accepted: 11/06/2013] [Indexed: 02/06/2023]
Abstract
Cerebral edema is a major cause of morbidity and mortality following ischemic stroke, but its underlying molecular pathophysiology is incompletely understood. Recent data have revealed the importance of ion flux via channels and transporters expressed in the neurogliovascular unit in the development of ischemia-triggered cytotoxic edema, vasogenic edema, and hemorrhagic conversion. Disruption of homeostatic mechanisms governing cell volume regulation and epithelial/endothelial ion transport due to ischemia-associated energy failure results in the thermodynamically driven re-equilibration of solutes and water across the CSF-blood and blood-brain barriers that ultimately increases the brain's extravascular volume. Additionally, hypoxia, inflammation, and other stress-triggered increases in the functional expression of ion channels and transporters normally expressed at low levels in the neurogliovascular unit cause disruptions in ion homeostasis that contribute to ischemic cerebral edema. Here, we review the pathophysiological significance of several molecular mediators of ion transport expressed in the neurogliovascular unit, including targets of existing FDA-approved drugs, which might be potential nodes for therapeutic intervention.
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Leng T, Lin J, Cottrell JE, Xiong ZG. Subunit and frequency-dependent inhibition of acid sensing ion channels by local anesthetic tetracaine. Mol Pain 2013; 9:27. [PMID: 23758830 PMCID: PMC3695766 DOI: 10.1186/1744-8069-9-27] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 06/05/2013] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Extracellular acidosis is a prominent feature of multiple pathological conditions, correlating with pain sensation. Acid-sensing ion channels (ASICs), a family of proton-gated cation channels, are distributed throughout the central and peripheral nervous systems. Activation of ASICs, particularly ASIC3 and ASIC1a channels, by acidic pH and the resultant depolarization of nociceptive primary sensory neurons, participates in nociception. Agents that inhibit the activation of ASICs are thus expected to be analgesic. Here, we studied the effect of local anesthetic tetracaine on ASIC currents. RESULTS Tetracaine inhibited the peak ASIC3 current in a concentration-dependent manner with an IC50 of 9.96 ± 1.88 mM. The degree of inhibition by tetracaine was dependent on the extracellular pH but independent of the membrane potential. Furthermore, 3 mM tetracaine also inhibited 29.83% of the sustained ASIC3 current. In addition to ASIC3, tetracaine inhibited the ASIC1a and ASIC1β currents. The inhibition of the ASIC1a current was influenced by the frequency of channel activation. In contrast to ASIC3, ASIC1a, and ASIC1β currents, ASIC2a current was not inhibited by tetracaine. In cultured mouse dorsal root ganglion neurons, 1-3 mM tetracaine inhibited both the transient and sustained ASIC currents. At pH4.5, 3 mM tetracaine reduced the peak ASIC current to 60.06 ± 4.51%, and the sustained current to 48.24 ± 7.02% of the control values in dorsal root ganglion neurons. In contrast to ASICs, voltage-gated sodium channels were inhibited by acid, with 55.15% inhibition at pH6.0 and complete inhibition at pH5.0. CONCLUSIONS These findings disclose a potential new mechanism underlying the analgesic effects of local anesthetics, particularly in acidic conditions where their primary target (i.e. voltage-gated Na+ channel) has been suppressed by protons.
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Abstract
Inhalation of acid aerosol or aspiration of acid solution evokes a stimulatory effect on airway C-fiber and Aδ afferents, which in turn causes airway irritation and triggers an array of defense reflex responses (e.g., cough, reflex bronchoconstriction, etc.). Tissue acidosis can also occur locally in the respiratory tract as a result of ischemia or inflammation, such as in the airways of asthmatic patients during exacerbation. The action of proton on the airway sensory neurons is generated by activation of two different current species: a transient (rapidly activating and inactivating) current mediated through the acid-sensing ion channels, and a slowly activating and sustained current mediated through the transient receptor potential vanilloid type 1 (TRPV1) receptor. In view of the recent findings that the expression and/or sensitivity of TRPV1 are up-regulated in the airway sensory nerves during chronic inflammatory reaction, the proton-evoked irritant effects on these nerves may play an important part in the manifestation of various symptoms associated with airway inflammatory diseases.
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Abstract
Venomous animals use a highly complex cocktails of proteins, peptides and small molecules to subdue and kill their prey. As such, venoms represent highly valuable combinatorial peptide libraries, displaying an extensive range of pharmacological activities, honed by natural selection. Modern analytical technologies enable us to take full advantage of this vast pharmacological cornucopia in the hunt for novel drug leads. Spider venoms represent a resource of several million peptides, which selectively target specific subtypes of ion channels. Structure-function studies of spider toxins are leading not only to the discovery of novel molecules, but also to novel therapeutic routes for cardiovascular diseases, cancer, neuromuscular diseases, pain and to a variety of other pathological conditions. This review presents an overview of spider peptide toxins as candidates for therapeutics and focuses on their applications in the discovery of novel mechanisms of analgesia.
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Affiliation(s)
- Pierre Escoubas
- University of Nice - Sophia Antipolis, Institut de Pharmacologie Moléculaire et Cellulaire (IPMC) - CNRS UMR6097, 660 Route des Lucioles, 06560 Valbonne, France +33 04 93 95 77 35 ; +33 04 93 95 77 08 ;
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Boiko N, Kucher V, Eaton BA, Stockand JD. Inhibition of neuronal degenerin/epithelial Na+ channels by the multiple sclerosis drug 4-aminopyridine. J Biol Chem 2013; 288:9418-27. [PMID: 23404498 DOI: 10.1074/jbc.m112.449413] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
The voltage-gated K(+) (Kv) channel blocker 4-aminopyridine (4-AP) is used to target symptoms of the neuroinflammatory disease multiple sclerosis (MS). By blocking Kv channels, 4-AP facilitates action potential conduction and neurotransmitter release in presynaptic neurons, lessening the effects of demyelination. Because they conduct inward Na(+) and Ca(2+) currents that contribute to axonal degeneration in response to inflammatory conditions, acid-sensing ion channels (ASICs) contribute to the pathology of MS. Consequently, ASICs are emerging as disease-modifying targets in MS. Surprisingly, as first demonstrated here, 4-AP inhibits neuronal degenerin/epithelial Na(+) (Deg/ENaC) channels, including ASIC and BLINaC. This effect is specific for 4-AP compared with its heterocyclic base, pyridine, and the related derivative, 4-methylpyridine; and akin to the actions of 4-AP on the structurally unrelated Kv channels, dose- and voltage-dependent. 4-AP has differential actions on distinct ASICs, strongly inhibiting ASIC1a channels expressed in central neurons but being without effect on ASIC3, which is enriched in peripheral sensory neurons. The voltage dependence of the 4-AP block and the single binding site for this inhibitor are consistent with 4-AP binding in the pore of Deg/ENaC channels as it does Kv channels, suggesting a similar mechanism of inhibition in these two classes of channels. These findings argue that effects on both Kv and Deg/ENaC channels should be considered when evaluating the actions of 4-AP. Importantly, the current results are consistent with 4-AP influencing the symptoms of MS as well as the course of the disease because of inhibitory actions on Kv and ASIC channels, respectively.
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Affiliation(s)
- Nina Boiko
- Department of Physiology, University of Texas Health Sciences Center, San Antonio, TX 78229, USA
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Acidotoxicity and acid-sensing ion channels contribute to motoneuron degeneration. Cell Death Differ 2013; 20:589-98. [PMID: 23306556 DOI: 10.1038/cdd.2012.158] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurological condition with no cure. Mitochondrial dysfunction, Ca(2+) overloading and local hypoxic/ischemic environments have been implicated in the pathophysiology of ALS and are conditions that may initiate metabolic acidosis in the affected tissue. We tested the hypothesis that acidotoxicity and acid-sensing ion channels (ASICs) are involved in the pathophysiology of ALS. We found that motoneurons were selectively vulnerable to acidotoxicity in vitro, and that acidotoxicity was partially reduced in asic1a-deficient motoneuron cultures. Cross-breeding of SOD1(G93A) ALS mice with asic1a-deficient mice delayed the onset and progression of motor dysfunction in SOD1 mice. Interestingly, we also noted a strong increase in ASIC2 expression in motoneurons of SOD1 mice and sporadic ALS patients during disease progression. Pharmacological pan-inhibition of ASIC channels with the lipophilic amiloride derivative, 5-(N,N-dimethyl)-amiloride hydrochloride, potently protected cultured motoneurons against acidotoxicity, and, given post-symptom onset, significantly improved lifespan, motor performance and motoneuron survival in SOD1 mice. Together, our data provide strong evidence for the involvement of acidotoxicity and ASIC channels in motoneuron degeneration, and highlight the potential of ASIC inhibitors as a new treatment approach for ALS.
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Abstract
Molecular pain research is a relatively new and rapidly expanding field that represents advancement in conventional pain research. One of the fundamentals of molecular pain involves the cloning of genes and especially the ion channels specifically involved in nociceptive processing at the periphery and centrally. A variety of approaches were used to isolate these critically important genes. Cloning of these genes involved innovative strategies based on existing molecular approaches. This review will discuss well-utilized cloning approaches and their exploitation in molecular pain research.
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Affiliation(s)
- Armen N Akopian
- Department of Endodontics, Dental School, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
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Ji HL, Zhao RZ, Chen ZX, Shetty S, Idell S, Matalon S. δ ENaC: a novel divergent amiloride-inhibitable sodium channel. Am J Physiol Lung Cell Mol Physiol 2012; 303:L1013-26. [PMID: 22983350 DOI: 10.1152/ajplung.00206.2012] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The fourth subunit of the epithelial sodium channel, termed delta subunit (δ ENaC), was cloned in human and monkey. Increasing evidence shows that this unique subunit and its splice variants exhibit biophysical and pharmacological properties that are divergent from those of α ENaC channels. The widespread distribution of epithelial sodium channels in both epithelial and nonepithelial tissues implies a range of physiological functions. The altered expression of SCNN1D is associated with numerous pathological conditions. Genetic studies link SCNN1D deficiency with rare genetic diseases with developmental and functional disorders in the brain, heart, and respiratory systems. Here, we review the progress of research on δ ENaC in genomics, biophysics, proteomics, physiology, pharmacology, and clinical medicine.
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Affiliation(s)
- Hong-Long Ji
- Department of Cellular and Molecular Biology, University of Texas Health Science Center at Tyler, Tyler, Texas, USA.
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Li J, Xing J. Muscle afferent receptors engaged in augmented sympathetic responsiveness in peripheral artery disease. Front Physiol 2012; 3:247. [PMID: 22934005 PMCID: PMC3429025 DOI: 10.3389/fphys.2012.00247] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 06/17/2012] [Indexed: 01/23/2023] Open
Abstract
The exercise pressor reflex (EPR) is a neural control mechanism responsible for the cardiovascular responses to exercise. As exercise is initiated, thin fiber muscle afferent nerves are activated by mechanical and metabolic stimuli arising in the contracting muscles. This leads to reflex increases in arterial blood pressure (BP) and heart rate primarily through activation of sympathetic nerve activity (SNA). Studies of humans and animals have indicated that the EPR is exaggerated in a number of cardiovascular diseases. For the last several years, studies have specifically employed a rodent model to examine the mechanisms at receptor and cellular levels by which responses of SNA and BP to static exercise are heightened in peripheral artery disease (PAD), one of the most common cardiovascular disorders. A rat model of this disease has well been established. Specifically, femoral artery occlusion is used to study intermittent claudication that is observed in human PAD. The receptors on thin fiber muscle afferents that are engaged in this disease include transient receptor potential vanilloid type 1 (TRPV1), purinergic P2X, and acid sensing ion channel (ASIC). The role played by nerve growth factor in regulating those sensory receptors in the processing of amplified EPR was also investigated. The purpose of this review is to focus on a theme namely that PAD accentuates autonomic reflex responses to exercise and further address regulatory mechanisms leading to abnormal sympathetic responsiveness. This review will present some of recent results in regard with several receptors in muscle sensory neurons in contribution to augmented autonomic reflex responses in PAD. Review of the findings from recent studies would lead to a better understanding in integrated processing of sympathetic nervous system in PAD.
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Affiliation(s)
- Jianhua Li
- Heart and Vascular Institute, Penn State University College of Medicine Hershey, PA, USA
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42
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Lu J, Xing J, Li J. Role for NGF in augmented sympathetic nerve response to activation of mechanically and metabolically sensitive muscle afferents in rats with femoral artery occlusion. J Appl Physiol (1985) 2012; 113:1311-22. [PMID: 22744968 DOI: 10.1152/japplphysiol.00617.2012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Arterial blood pressure and heart rate responses to static contraction of the hindlimb muscles are greater in rats whose femoral arteries were previously ligated than in control rats. Also, the prior findings demonstrate that nerve growth factor (NGF) is increased in sensory neurons-dorsal root ganglion (DRG) neurons of occluded rats. However, the role for endogenous NGF in engagement of the augmented sympathetic and pressor responses to stimulation of mechanically and/or metabolically sensitive muscle afferent nerves during static contraction after femoral artery ligation has not been specifically determined. In the present study, both afferent nerves and either of them were activated by muscle contraction, passive tendon stretch, and arterial injection of lactic acid into the hindlimb muscles. Data showed that femoral occlusion-augmented blood pressure response to contraction was significantly attenuated by a prior administration of the NGF antibody (NGF-Ab) into the hindlimb muscles. The effects of NGF neutralization were not seen when the sympathetic nerve and pressor responses were evoked by stimulation of mechanically sensitive muscle afferent nerves with tendon stretch in occluded rats. In addition, chemically sensitive muscle afferent nerves were stimulated by lactic acid injected into arterial blood supply of the hindlimb muscles after the prior NGF-Ab, demonstrating that the reflex muscle responses to lactic acid were significantly attenuated. The results of this study further showed that NGF-Ab attenuated an increase in acid-sensing ion channel subtype 3 (ASIC3) of DRG in occluded rats. Moreover, immunohistochemistry was employed to examine the number of C-fiber and A-fiber DRG neurons. The data showed that distribution of DRG neurons with different thin fiber phenotypes was not notably altered when NGF was infused into the hindlimb muscles. However, NGF increased expression of ASIC3 in DRG neurons with C-fiber but not A-fiber. Overall, these data suggest that 1) NGF is amplified in sensory nerves of occluded rats and contributes to augmented reflex sympathetic and blood pressure responses evoked by stimulation of chemically, but not mechanically, sensitive muscle afferent nerves and 2) NGF likely plays a role in modulating the muscle metaboreflex via enhancement of ASIC3 expression in C-fiber of DRG neurons.
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Affiliation(s)
- Jian Lu
- Pennsylvania State Heart and Vascular Institute, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
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Wang JQ, Chu XP, Guo ML, Jin DZ, Xue B, Berry TJ, Fibuch EE, Mao LM. Modulation of ionotropic glutamate receptors and Acid-sensing ion channels by nitric oxide. Front Physiol 2012; 3:164. [PMID: 22654773 PMCID: PMC3359525 DOI: 10.3389/fphys.2012.00164] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Accepted: 05/07/2012] [Indexed: 11/13/2022] Open
Abstract
Ionotropic glutamate receptors (iGluR) are ligand-gated ion channels and are densely expressed in broad areas of mammalian brains. Like iGluRs, acid-sensing ion channels (ASIC) are ligand (H+)-gated channels and are enriched in brain cells and peripheral sensory neurons. Both ion channels are enriched at excitatory synaptic sites, functionally coupled to each other, and subject to the modulation by a variety of signaling molecules. Central among them is a gasotransmitter, nitric oxide (NO). Available data show that NO activity-dependently modulates iGluRs and ASICs via either a direct or an indirect pathway. The former involves a NO-based and cGMP-independent post-translational modification (S-nitrosylation) of extracellular cysteine residues in channel subunits or channel-interacting proteins. The latter is achieved by NO activation of soluble guanylyl cyclase, which in turn triggers an intracellular cGMP-sensitive cascade to indirectly modulate iGluRs and ASICs. The NO modification is usually dynamic and reversible. Modified channels undergo significant, interrelated changes in biochemistry and electrophysiology. Since NO synthesis is enhanced in various neurological disorders, the NO modulation of iGluRs and ASICs is believed to be directly linked to the pathogenesis of these disorders. This review summarizes the direct and indirect modifications of iGluRs and ASICs by NO and analyzes the role of the NO-iGluR and NO-ASIC coupling in cell signaling and in the pathogenesis of certain related neurological diseases.
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Affiliation(s)
- John Q Wang
- Department of Basic Medical Science, School of Medicine, University of Missouri-Kansas City Kansas City, MO, USA
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ZHU YJ, XU F, SU JH, ZHOU H, LU TJ. MATHEMATICAL MODELING FOR THE PREDICTION AND IMPROVEMENT OF TOOTH THERMAL PAIN: A REVIEW. J MECH MED BIOL 2012. [DOI: 10.1142/s0219519411004095] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Tooth pain, especially tooth thermal pain, is one of the most important symptoms and signs in dental clinic and daily life. As a special sensation, pain has been studied extensively in both clinic and experimental research aimed at reducing or eliminating the possible negative effects of pain. Unfortunately, the full underlying mechanism of pain is still unclear, because the pain could be influenced by many factors, including physiological, psychological, physical, chemical, and biological factors and so on. Besides, most studies on pain mechanisms in the literature are based on skin pain sensation and only few are based on tooth pain. In this paper, we present a comprehensive review on both neurophysiology of tooth pain mechanism, and corresponding thermal, mechanical, and thermomechanical behaviors of teeth. We also describe a multiscale modeling approach for quantifying tooth thermal pain by integrating the mathematic methods of engineering into the neuroscience. The mathematical model of tooth thermal pain will enable better understanding of thermal pain mechanism and optimization of existing diagnosis and treatment in dental clinic.
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Affiliation(s)
- Y. J. ZHU
- Stomatological Hospital, College of Medicine, Biomedical Engineering and Biomechanics Center, Xi'an Jiaotong University, Xi'an 710049, P. R. China
| | - F. XU
- Biomedical Engineering and Biomechanics Center, Xi'an Jiaotong University, Xi'an 710049, P. R. China
- School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, P. R. China
| | - J. H. SU
- Biomedical Engineering and Biomechanics Center, Xi'an Jiaotong University, Xi'an 710049, P. R. China
| | - H. ZHOU
- Stomatological Hospital, College of Medicine, Xi'an Jiaotong University, Xi'an 710004, P. R. China
| | - T. J. LU
- Biomedical Engineering and Biomechanics Center, Xi'an Jiaotong University, Xi'an 710049, P. R. China
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Xing J, Lu J, Li J. Acid-sensing ion channel subtype 3 function and immunolabelling increases in skeletal muscle sensory neurons following femoral artery occlusion. J Physiol 2011; 590:1261-72. [PMID: 22183722 DOI: 10.1113/jphysiol.2011.221788] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Sympathetic nerve activity and arterial blood pressure responses to static hindlimb muscle contractions are greater in rats with femoral arteries that were previously ligated (24-72 h earlier) than in control rats. Studies further demonstrate that acid-sensing ion channel subtype 3 (ASIC(3)) in thin-fibre muscle afferents contributes to the amplified reflex muscle responses observed in occluded rats, probably due to enhanced ASIC(3) expression in muscle sensory neurons. The purpose of this study was to characterize acid-induced current with activation of ASIC(3) in dorsal root ganglion (DRG) neurons of control rats and rats with 24 h of femoral occlusion using whole-cell patch clamp methods. Also, immunohistochemistry was employed to examine existence of ASIC(3) expression in DRG neurons of thin-fibre afferents. DRG neurons from 4- to 6-week-old rats were labelled by injecting the fluorescence tracer DiI into the hindlimb muscles 4-5 days prior to the recording experiments. The results of this study show that ∼90% of current responses evoked by pH 6.7 in DRG neurons innervating the hindlimb muscles are ASIC(3)-like. The peak current amplitude to pH 6.7 is significantly attenuated with application of rAPETx2, a specific ASIC(3) antagonist. In addition, ASIC(3)-like current responses to pH 6.7 are observed in small, medium and large DRG neurons, and size distribution of DRG neurons is similar in control and occluded animals. However, the peak current amplitude of DRG neuron response induced by ASIC(3) stimulation is larger in occluded rats than that in control rats. Moreover, the percentage of DRG neurons with ASIC(3)-like currents is greater after arterial occlusion compared with control. Furthermore, results from double immunofluorescence experiments show that femoral artery occlusion mainly augments ASIC(3) expression within DRG neurons projecting C-fibre afferents. Taken together, these data suggest that (1) the majority of current responses to pH 6.7 are ASIC(3)-like in DRG neurons with nerve endings in the hindlimb muscles, (2) a greater acid-induced current responding to pH 6.7 develops when hindlimb arterial blood supply is deficient under ischaemic conditions, and (3) increased ASIC(3) expression is largely observed in thin C-fibres of DRG neurons after hindlimb ischaemia.
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Affiliation(s)
- Jihong Xing
- Pennsylvania State Heart & Vascular Institute, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA
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Liu X, He L, Dinger B, Fidone SJ. Chronic hypoxia-induced acid-sensitive ion channel expression in chemoafferent neurons contributes to chemoreceptor hypersensitivity. Am J Physiol Lung Cell Mol Physiol 2011; 301:L985-92. [PMID: 21890510 DOI: 10.1152/ajplung.00132.2011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Previously we demonstrated that chronic hypoxia (CH) induces an inflammatory condition characterized by immune cell invasion and increased expression of inflammatory cytokines in rat carotid body. It is well established that chronic inflammatory pain induces the expression of acid-sensitive ion channels (ASIC) in primary sensory neurons, where they contribute to hyperalgesia and allodynia. The present study examines the effect of CH on ASIC expression in petrosal ganglion (PG), which contains chemoafferent neurons that innervate oxygen-sensitive type I cells in the carotid body. Five isoforms of ASIC transcript were increased ∼1.5-2.5-fold in PG following exposure of rats to 1, 3, or 7 days of hypobaric hypoxia (380 Torr). ASIC transcript was not increased in the sympathetic superior cervical ganglion (SCG). In the PG, CH also increased the expression of channel-interacting PDZ domain protein, a scaffolding protein known to enhance the surface expression and the low pH-induced current density mediated by ASIC3. Western immunoblot analysis showed that CH elevated ASIC3 protein in PG, but not in SCG or the (sensory) nodose ganglion. ASIC3 transcript was likewise elevated in PG neurons cultured in the presence of inflammatory cytokines. Increased ASIC expression was blocked in CH rats concurrently treated with the nonsteroidal anti-inflammatory drug ibuprofen (4 mg·kg(-1)·day(-1)). Electrophysiological recording of carotid sinus nerve (CSN) activity in vitro showed that the specific ASIC antagonist A-317567 (100 μM) did not significantly alter hypoxia-evoked activity in normal preparations but blocked ∼50% of the hypoxic response following CH. Likewise, a high concentration of ibuprofen, which is known to block ASIC1a, reduced hypoxia-evoked CSN activity by ∼50% in CH preparations. Our findings indicate that CH induces inflammation-dependent phenotypic adjustments in chemoafferent neurons. Following CH, ASIC are important participants in chemotransmission between type I cells and chemoafferent nerve terminals, and these proton-gated channels appear to enhance chemoreceptor sensitivity.
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Affiliation(s)
- X Liu
- Department of Physiology, University of Utah School of Medicine, Salt Lake City, USA
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Su J, Tang Y, Liu L, Zhou H, Dong Q. Regulation of acid-sensing ion channel 1a function by tissue kallikrein may be through channel cleavage. Neurosci Lett 2011; 490:46-51. [DOI: 10.1016/j.neulet.2010.12.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Revised: 11/26/2010] [Accepted: 12/09/2010] [Indexed: 11/30/2022]
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Abstract
All animals use a sophisticated array of receptor proteins to sense their external and internal environments. Major advances have been made in recent years in understanding the molecular and genetic bases for sensory transduction in diverse modalities, indicating that both metabotropic and ionotropic pathways are important in sensory functions. Here, I review the historical background and recent advances in understanding the roles of a relatively newly discovered family of receptors, the degenerin/epithelial sodium channels (DEG/ENaC). These animal-specific cation channels show a remarkable sequence and functional diversity in different species and seem to exert their functions in diverse sensory modalities. Functions for DEG/ENaC channels have been implicated in mechanosensation as well as chemosensory transduction pathways. In spite of overall sequence diversity, all family members share a unique protein topology that includes just two transmembrane domains and an unusually large and highly structured extracellular domain, that seem to be essential for both their mechanical and chemical sensory functions. This review will discuss many of the recent discoveries and controversies associated with sensory function of DEG/ENaC channels in both vertebrate and invertebrate model systems, covering the role of family members in taste, mechanosensation, and pain.
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Jin W, Shen C, Jing L, Zha XM, Xia J. PICK1 regulates the trafficking of ASIC1a and acidotoxicity in a BAR domain lipid binding-dependent manner. Mol Brain 2010; 3:39. [PMID: 21176140 PMCID: PMC3018362 DOI: 10.1186/1756-6606-3-39] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Accepted: 12/21/2010] [Indexed: 12/11/2022] Open
Abstract
Background Acid-sensing ion channel 1a (ASIC1a) is the major ASIC subunit determining acid-activated currents in brain neurons. Recent studies show that ASIC1a play critical roles in acid-induced cell toxicity. While these studies raise the importance of ASIC1a in diseases, mechanisms for ASIC1a trafficking are not well understood. Interestingly, ASIC1a interacts with PICK1 (protein interacting with C-kinase 1), an intracellular protein that regulates trafficking of several membrane proteins. However, whether PICK1 regulates ASIC1a surface expression remains unknown. Results Here, we show that PICK1 overexpression increases ASIC1a surface level. A BAR domain mutant of PICK1, which impairs its lipid binding capability, blocks this increase. Lipid binding of PICK1 is also required for PICK1-induced clustering of ASIC1a. Consistent with the effect on ASIC1a surface levels, PICK1 increases ASIC1a-mediated acidotoxicity and this effect requires both the PDZ and BAR domains of PICK1. Conclusions Taken together, our results indicate that PICK1 regulates trafficking and function of ASIC1a in a lipid binding-dependent manner.
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Affiliation(s)
- Wenying Jin
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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Majumdar D, Bevensee MO. Na-coupled bicarbonate transporters of the solute carrier 4 family in the nervous system: function, localization, and relevance to neurologic function. Neuroscience 2010; 171:951-72. [PMID: 20884330 DOI: 10.1016/j.neuroscience.2010.09.037] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Revised: 09/03/2010] [Accepted: 09/14/2010] [Indexed: 12/26/2022]
Abstract
Many cellular processes including neuronal activity are sensitive to changes in intracellular and/or extracellular pH-both of which are regulated by acid-base transporter activity. HCO(3)(-)-dependent transporters are particularly potent regulators of intracellular pH in neurons and astrocytes, and also contribute to the composition of the cerebrospinal fluid (CSF). The molecular physiology of HCO(3)(-) transporters has advanced considerably over the past ∼14 years as investigators have cloned and characterized the function and localization of many Na-Coupled Bicarbonate Transporters of the solute carrier 4 (Slc4) family (NCBTs). In this review, we provide an updated overview of the function and localization of NCBTs in the nervous system. Multiple NCBTs are expressed in neurons and astrocytes in various brain regions, as well as in epithelial cells of the choroid plexus. Characteristics of human patients with SLC4 gene mutations/deletions and results from recent studies on mice with Slc4 gene disruptions highlight the functional importance of NCBTs in neuronal activity, somatosensory function, and CSF production. Furthermore, energy-deficient states (e.g., hypoxia and ischemia) lead to altered expression and activity of NCBTs. Thus, recent studies expand our understanding of the role of NCBTs in regulating the pH and ionic composition of the nervous system that can modulate neuronal activity.
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Affiliation(s)
- D Majumdar
- Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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