1
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Vullo S, Ambrosio N, Kucera JP, Bignucolo O, Kellenberger S. Kinetic analysis of ASIC1a delineates conformational signaling from proton-sensing domains to the channel gate. eLife 2021; 10:66488. [PMID: 33729158 PMCID: PMC8009679 DOI: 10.7554/elife.66488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 03/16/2021] [Indexed: 11/13/2022] Open
Abstract
Acid-sensing ion channels (ASICs) are neuronal Na+ channels that are activated by a drop in pH. Their established physiological and pathological roles, involving fear behaviors, learning, pain sensation, and neurodegeneration after stroke, make them promising targets for future drugs. Currently, the ASIC activation mechanism is not understood. Here, we used voltage-clamp fluorometry (VCF) combined with fluorophore-quencher pairing to determine the kinetics and direction of movements. We show that conformational changes with the speed of channel activation occur close to the gate and in more distant extracellular sites, where they may be driven by local protonation events. Further, we provide evidence for fast conformational changes in a pathway linking protonation sites to the channel pore, in which an extracellular interdomain loop interacts via aromatic residue interactions with the upper end of a transmembrane helix and would thereby open the gate.
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Affiliation(s)
- Sabrina Vullo
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Nicolas Ambrosio
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Jan P Kucera
- Department of Physiology, University of Bern, Bern, Switzerland
| | - Olivier Bignucolo
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland.,SIB, Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Stephan Kellenberger
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
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2
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Xu Y, Chen F. Factors and Molecular Mechanisms Influencing the Protein Synthesis, Degradation and Membrane Trafficking of ASIC1a. Front Cell Dev Biol 2020; 8:596304. [PMID: 33195276 PMCID: PMC7644914 DOI: 10.3389/fcell.2020.596304] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 10/05/2020] [Indexed: 12/31/2022] Open
Abstract
Acid-sensing ion channels (ASICs) are members of the degenerin/epithelial sodium channel superfamily. They are extracellular pH sensors that are activated by protons. Among all ASICs, ASIC1a is one of the most intensively studied isoforms because of its unique ability to be permeable to Ca2+. In addition, it is considered to contribute to various pathophysiological conditions. As a membrane proton receptor, the number of ASIC1a present on the cell surface determines its physiological and pathological functions, and this number partially depends on protein synthesis, degradation, and membrane trafficking processes. Recently, several studies have shown that various factors affect these processes. Therefore, this review elucidated the major factors and underlying molecular mechanisms affecting ASIC1a protein expression and membrane trafficking.
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Affiliation(s)
- Yayun Xu
- Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, Hefei, China.,The Key Laboratory of Major Autoimmune Diseases of Anhui Province, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, China.,The Key Laboratory of Anti-inflammatory and Immune Medicines, Ministry of Education, Hefei, China
| | - Feihu Chen
- Department of Epidemiology and Biostatistics, School of Public Health, Anhui Medical University, Hefei, China.,The Key Laboratory of Major Autoimmune Diseases of Anhui Province, Anhui Institute of Innovative Drugs, School of Pharmacy, Anhui Medical University, Hefei, China.,The Key Laboratory of Anti-inflammatory and Immune Medicines, Ministry of Education, Hefei, China
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3
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Xu Y, Jiang YQ, Li C, He M, Rusyniak WG, Annamdevula N, Ochoa J, Leavesley SJ, Xu J, Rich TC, Lin MT, Zha XM. Human ASIC1a mediates stronger acid-induced responses as compared with mouse ASIC1a. FASEB J 2018; 32:3832-3843. [PMID: 29447005 DOI: 10.1096/fj.201701367r] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Acid-sensing ion channels (ASICs) are the major proton receptor in the brain and a key mediator of acidosis-induced neuronal injuries in disease. Most of published data on ASIC function came from studies performed in mice, and relatively little is known about potential differences between human and mouse ASICs (hASIC and mASIC, respectively). This information is critical for us to better interpret the functional importance of ASICs in human disease. Here, we examined the expression of ASICs in acutely resected human cortical tissue. Compared with mouse cortex, human cortical tissue showed a similar ratio of ASIC1a:ASIC2a expression, had reduced ASIC2b level, and exhibited a higher membrane:total ratio of ASIC1a. We further investigated the mechanism for higher surface trafficking of hASIC1a in heterologous cells. A single amino acid at position 285 was critical for increased N-glycosylation and surface expression of hASIC1a. Consistent with the changes in trafficking and current, cells expressing hASIC1a or mASIC1a S285P mutant had a higher acid-activated calcium increase and exhibited worsened acidotoxicity. These data suggest that ASICs are likely to have a larger impact on acidosis-induced neuronal injuries in humans than mice, and this effect is, at least in part, a result of more efficient trafficking of hASIC1a.-Xu, Y., Jiang, Y.-Q., Li, C., He, M., Rusyniak, W. G., Annamdevula, N., Ochoa, J., Leavesley, S. J., Xu, J., Rich, T. C., Lin, M. T., Zha, X.-M. Human ASIC1a mediates stronger acid-induced responses as compared with mouse ASIC1a.
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Affiliation(s)
- Yuanyuan Xu
- Department of Physiology and Cell Biology, College of Medicine, University of South Alabama, Mobile, Alabama, USA.,Department of Neuropharmacology and Drug Discovery, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, China
| | - Yu-Qing Jiang
- Department of Physiology and Cell Biology, College of Medicine, University of South Alabama, Mobile, Alabama, USA.,The Third Hospital of Hebei Medical University, ShiJiaZhuang, China
| | - Ce Li
- Department of Physiology and Cell Biology, College of Medicine, University of South Alabama, Mobile, Alabama, USA.,Department of Rehabilitation Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Mindi He
- Department of Physiology and Cell Biology, College of Medicine, University of South Alabama, Mobile, Alabama, USA
| | - W George Rusyniak
- Department of Neurosurgery, College of Medicine, University of South Alabama, Mobile, Alabama, USA
| | - Naga Annamdevula
- Department of Pharmacology, College of Medicine, University of South Alabama, Mobile, Alabama, USA
| | - Juan Ochoa
- Department of Neurology, College of Medicine, University of South Alabama, Mobile, Alabama, USA
| | - Silas J Leavesley
- Chemical and Biomolecular Engineering, College of Engineering, University of South Alabama, Mobile, Alabama, USA
| | - Jiangping Xu
- Department of Neuropharmacology and Drug Discovery, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, China
| | - Thomas C Rich
- Department of Pharmacology, College of Medicine, University of South Alabama, Mobile, Alabama, USA
| | - Mike T Lin
- Department of Physiology and Cell Biology, College of Medicine, University of South Alabama, Mobile, Alabama, USA
| | - Xiang-Ming Zha
- Department of Physiology and Cell Biology, College of Medicine, University of South Alabama, Mobile, Alabama, USA
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4
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Farrag M, Drobish JK, Puhl HL, Kim JS, Herold PB, Kaufman MP, Ruiz-Velasco V. Endomorphins potentiate acid-sensing ion channel currents and enhance the lactic acid-mediated increase in arterial blood pressure: effects amplified in hindlimb ischaemia. J Physiol 2017; 595:7167-7183. [PMID: 29044528 DOI: 10.1113/jp275058] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 10/13/2017] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS Chronic limb ischaemia, characterized by inflammatory mediator release and a low extracellular pH, leads to acid-sensing ion channel (ASIC) activation and reflexively increases mean arterial pressure; endomorphin release is also increased under inflammatory conditions. We examined the modulation of ASIC currents by endomorphins in sensory neurons from rats with freely perfused and ligated femoral arteries: peripheral artery disease (PAD) model. Endomorphins potentiated sustained ASIC currents in both groups of dorsal root ganglion neurons, independent of mu opioid receptor stimulation or G protein activation. Intra-arterial administration of lactic acid (to simulate exercising muscle and evoke a pressor reflex), endomorphin-2 and naloxone resulted in a significantly greater pressor response than lactic acid alone, while administration of APETx2 inhibited endomorphin's enhancing effect in both groups. These results suggest a novel role for endomorphins in modulating ASIC function to effect lactic acid-mediated reflex increase in arterial pressure in patients with PAD. ABSTRACT Chronic muscle ischaemia leads to accumulation of lactic acid and other inflammatory mediators with a subsequent drop in interstitial pH. Acid-sensing ion channels (ASICs), expressed in thin muscle afferents, sense the decrease in pH and evoke a pressor reflex known to increase mean arterial pressure. The naturally occurring endomorphins are also released by primary afferents under ischaemic conditions. We examined whether high affinity mu opioid receptor (MOR) agonists, endomorphin-1 (E-1) and -2 (E-2), modulate ASIC currents and the lactic acid-mediated pressor reflex. In rat dorsal root ganglion (DRG) neurons, exposure to E-2 in acidic solutions significantly potentiated ASIC currents when compared to acidic solutions alone. The potentiation was significantly greater in DRG neurons isolated from rats whose femoral arteries were ligated for 72 h. Sustained ASIC current potentiation was also observed in neurons pretreated with pertussis toxin, an uncoupler of G proteins and MOR. The endomorphin-mediated potentiation was a result of a leftward shift of the activation curve to higher pH values and a slight shift of the inactivation curve to lower pH values. Intra-arterial co-administration of lactic acid and E-2 led to a significantly greater pressor reflex than lactic acid alone in the presence of naloxone. Finally, E-2 effects were inhibited by pretreatment with the ASIC3 blocker APETx2 and enhanced by pretreatment with the ASIC1a blocker psalmotoxin-1. These findings have uncovered a novel role of endomorphins by which the opioids can enhance the lactic acid-mediated reflex increase in arterial pressure that is MOR stimulation-independent and APETx2-sensitive.
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Affiliation(s)
- Mohamed Farrag
- Department of Anesthesiology and Perioperative Medicine, Penn State College of Medicine, Hershey, PA, USA
| | - Julie K Drobish
- Department of Anesthesiology and Perioperative Medicine, Penn State College of Medicine, Hershey, PA, USA
| | - Henry L Puhl
- Department of Anesthesiology and Perioperative Medicine, Penn State College of Medicine, Hershey, PA, USA
| | - Joyce S Kim
- Department of Anesthesiology and Perioperative Medicine, Penn State College of Medicine, Hershey, PA, USA
| | - Paul B Herold
- Department of Anesthesiology and Perioperative Medicine, Penn State College of Medicine, Hershey, PA, USA
| | - Marc P Kaufman
- Department of Anesthesiology and Perioperative Medicine, Penn State College of Medicine, Hershey, PA, USA
| | - Victor Ruiz-Velasco
- Department of Anesthesiology and Perioperative Medicine, Penn State College of Medicine, Hershey, PA, USA
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5
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Jiang YQ, Zha XM. miR-149 reduces while let-7 elevates ASIC1a expression in vitro. INTERNATIONAL JOURNAL OF PHYSIOLOGY, PATHOPHYSIOLOGY AND PHARMACOLOGY 2017; 9:147-152. [PMID: 29209451 PMCID: PMC5698691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Accepted: 10/26/2017] [Indexed: 06/07/2023]
Abstract
Acid-sensing ion channel 1a (ASIC1a) is the key subunit that determines acid-activated currents in neurons. ASIC1a is important for neural plasticity, learning, and for multiple neurological diseases, including stroke, multiple sclerosis, and traumatic injuries. These findings underline the importance for better defining mechanisms that regulate ASIC1a expression. During the past decade, microRNA has emerged as one important group of regulatory molecules in controlling protein expression. However, little is known about whether microRNA regulates ASIC1a. Here, we assessed several microRNAs that have predicted targeting sequences in the 3' untranslated region (UTR) of mouse ASIC1a. Our results indicated that miR-144 and -149 reduced ASIC1a expression while Let-7 increased ASIC1a protein levels. miR-30c, -98, -125, -182* had no significant effect. Since a reduction in ASIC1a expression may have translational potentials in treating neuronal injury, we further asked whether the effect of miR-144 and miR-149, both reduced ASIC1a expression, was through specific targeting of the predicted sites on ASIC1a. We mutated the targeting sequence of miR-144 and miR-149 in ASIC1a UTR. The effect of miR-149 was abolished in the corresponding mutation. In contrast, miR-144 still reduced ASIC1a level when its predicted target sequence was mutated. This result indicates that miR-149 targets the 3'UTR of ASIC1a and reduces its expression.
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Affiliation(s)
- Yu-Qing Jiang
- Department of Physiology and Cell Biology, University of South Alabama College of MedicineMobile, AL 36688, USA
- The Third Hospital of Hebei Medical University139 Ziqiang Road, Shijiazhuang 050051, Hebei Province, China
| | - Xiang-Ming Zha
- Department of Physiology and Cell Biology, University of South Alabama College of MedicineMobile, AL 36688, USA
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6
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Jiang N, Wu J, Leng T, Yang T, Zhou Y, Jiang Q, Wang B, Hu Y, Ji YH, Simon RP, Chu XP, Xiong ZG, Zha XM. Region specific contribution of ASIC2 to acidosis-and ischemia-induced neuronal injury. J Cereb Blood Flow Metab 2017; 37:528-540. [PMID: 26861816 PMCID: PMC5381448 DOI: 10.1177/0271678x16630558] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Acidosis in the brain plays a critical role in neuronal injury in neurological diseases, including brain ischemia. One key mediator of acidosis-induced neuronal injury is the acid-sensing ion channels (ASICs). Current literature has focused on ASIC1a when studying acid signaling. The importance of ASIC2, which is also widely expressed in the brain, has not been appreciated. We found here a region-specific effect of ASIC2 on acid-mediated responses. Deleting ASIC2 reduced acid-activated current in cortical and striatal neurons, but had no significant effect in cerebellar granule neurons. In addition, we demonstrated that ASIC2 was important for ASIC1a expression, and that ASIC2a but not 2b facilitated ASIC1a surface trafficking in the brain. Further, we showed that ASIC2 deletion attenuated acidosis/ischemia-induced neuronal injury in organotypic hippocampal slices but had no effect in organotypic cerebellar slices. Consistent with an injurious role of ASIC2, we showed that ASIC2 deletion significantly protected the mouse brain from ischemic damage in vivo. These data suggest a critical region-specific contribution of ASIC2 to neuronal injury and reveal an important functional difference between ASIC2a and 2b in the brain.
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Affiliation(s)
- Nan Jiang
- 1 Department of Physiology and Cell Biology, University of South Alabama, Mobile, USA.,2 School of Life Sciences, Shanghai University, Shanghai, China
| | - Junjun Wu
- 1 Department of Physiology and Cell Biology, University of South Alabama, Mobile, USA.,3 China State Institute of Pharmaceutical Industry, Shanghai, China
| | - Tiandong Leng
- 4 Department of Neurobiology, Morehouse School of Medicine, Atlanta, USA
| | - Tao Yang
- 4 Department of Neurobiology, Morehouse School of Medicine, Atlanta, USA
| | - Yufan Zhou
- 1 Department of Physiology and Cell Biology, University of South Alabama, Mobile, USA
| | - Qian Jiang
- 5 Department of Basic Medical Science, University of Missouri-Kansas City, Kansas City, USA
| | - Bin Wang
- 6 Department of Mathematics and Statistics, University of South Alabama, Mobile, USA
| | - Youjia Hu
- 3 China State Institute of Pharmaceutical Industry, Shanghai, China
| | - Yong-Hua Ji
- 2 School of Life Sciences, Shanghai University, Shanghai, China
| | - Roger P Simon
- 4 Department of Neurobiology, Morehouse School of Medicine, Atlanta, USA
| | - Xiang-Ping Chu
- 5 Department of Basic Medical Science, University of Missouri-Kansas City, Kansas City, USA
| | - Zhi-Gang Xiong
- 4 Department of Neurobiology, Morehouse School of Medicine, Atlanta, USA
| | - Xiang-Ming Zha
- 1 Department of Physiology and Cell Biology, University of South Alabama, Mobile, USA
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7
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Wu J, Leng T, Jing L, Jiang N, Chen D, Hu Y, Xiong ZG, Zha XM. Two di-leucine motifs regulate trafficking and function of mouse ASIC2a. Mol Brain 2016; 9:9. [PMID: 26819004 PMCID: PMC4729175 DOI: 10.1186/s13041-016-0190-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 01/21/2016] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Acid-sensing ion channels (ASICs) are proton-gated cation channels that mediate acid-induced responses in neurons. ASICs are important for mechanosensation, learning and memory, fear, pain, and neuronal injury. ASIC2a is widely expressed in the nervous system and modulates ASIC channel trafficking and activity in both central and peripheral systems. Here, to better understand mechanisms regulating ASIC2a, we searched for potential protein motifs that regulate ASIC2a trafficking. RESULTS AND CONCLUSIONS We identified a LLDLL sequence in the C-terminal juxtamembrane region of ASIC2a. Deleting or mutating the LLDLL sequence increased total expression and surface levels of ASIC2a in CHO cells. Mutating either of the two LL motifs had a similar effect. We further assessed ASIC2a localization in organotypic hippocampal slice neurons. The LL motif mutants exhibited increased dendritic trafficking and elevated targeting to dendritic spines. Consistent with an efficient trafficking, the LL motif mutants increased acid-activated current density. In addition, mutating the second LL motif increased pH sensitivity of the channel. These data identify the LL motifs as a negative regulator of ASIC2a trafficking and function, and suggest novel regulatory mechanisms in acid signaling.
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Affiliation(s)
- Junjun Wu
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, 5851 USA Dr N, MSB3074, Mobile, AL, 36688, USA. .,China State Institute of Pharmaceutical Industry, 285 Gebaini Road, Shanghai, 201203, China.
| | - Tiandong Leng
- Department of Neurobiology, Morehouse School of Medicine, 720 Westview Drive SW, Atlanta, 30310, GA, USA.
| | - Lan Jing
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, 5851 USA Dr N, MSB3074, Mobile, AL, 36688, USA. .,State Key Lab of New Drug & Pharmaceutical Process, Shanghai Institute of Pharmaceutical Industry, 1320 West Beijing Rd, Shanghai, 200040, China.
| | - Nan Jiang
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, 5851 USA Dr N, MSB3074, Mobile, AL, 36688, USA. .,Shanghai University School of Life Sciences, Shanghai, China.
| | - Daijie Chen
- China State Institute of Pharmaceutical Industry, 285 Gebaini Road, Shanghai, 201203, China.
| | - Youjia Hu
- China State Institute of Pharmaceutical Industry, 285 Gebaini Road, Shanghai, 201203, China.
| | - Zhi-Gang Xiong
- Department of Neurobiology, Morehouse School of Medicine, 720 Westview Drive SW, Atlanta, 30310, GA, USA.
| | - Xiang-ming Zha
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, 5851 USA Dr N, MSB3074, Mobile, AL, 36688, USA.
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8
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Wu J, Xu Y, Jiang YQ, Xu J, Hu Y, Zha XM. ASIC subunit ratio and differential surface trafficking in the brain. Mol Brain 2016; 9:4. [PMID: 26746198 PMCID: PMC4706662 DOI: 10.1186/s13041-016-0185-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 01/04/2016] [Indexed: 12/31/2022] Open
Abstract
Background Acid-sensing ion channels (ASICs) are key mediators of acidosis-induced responses in neurons. However, little is known about the relative abundance of different ASIC subunits in the brain. Such data are fundamental for interpreting the relative contribution of ASIC1a homomers and 1a/2 heteromers to acid signaling, and essential for designing therapeutic interventions to target these channels. We used a simple biochemical approach and semi-quantitatively determined the molar ratio of ASIC1a and 2 subunits in mouse brain. Further, we investigated differential surface trafficking of ASIC1a, ASIC2a, and ASIC2b. Results and conclusions ASIC1a subunits outnumber the sum of ASIC2a and ASIC2b. There is a region-specific variation in ASIC2a and 2b expression, with cerebellum and striatum expressing predominantly 2b and 2a, respectively. Further, we performed surface biotinylation and found that surface ASIC1a and ASIC2a ratio correlates with their total expression. In contrast, ASIC2b exhibits little surface presence in the brain. This result is consistent with increased co-localization of ASIC2b with an ER marker in 3T3 cells. Our data are the first semi-quantitative determination of relative subunit ratio of various ASICs in the brain. The differential surface trafficking of ASICs suggests that the main functional ASICs in the brain are ASIC1a homomers and 1a/2a heteromers. This finding provides important insights into the relative contribution of various ASIC complexes to acid signaling in neurons.
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Affiliation(s)
- Junjun Wu
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, 5851 USA Dr N, MSB3074, Mobile, AL, 36688, USA. .,China State Institute of Pharmaceutical Industry, 285 Gebaini Road, Shanghai, 201203, China.
| | - Yuanyuan Xu
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, 5851 USA Dr N, MSB3074, Mobile, AL, 36688, USA. .,School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, China.
| | - Yu-Qing Jiang
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, 5851 USA Dr N, MSB3074, Mobile, AL, 36688, USA. .,Department of Urology, The Third Hospital of Hebei Medical University, Shijiazhuang, HeBei, China.
| | - Jiangping Xu
- School of Pharmaceutical Sciences, Southern Medical University, Guangzhou, China.
| | - Youjia Hu
- China State Institute of Pharmaceutical Industry, 285 Gebaini Road, Shanghai, 201203, China.
| | - Xiang-ming Zha
- Department of Physiology and Cell Biology, University of South Alabama College of Medicine, 5851 USA Dr N, MSB3074, Mobile, AL, 36688, USA.
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9
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Abstract
Acid-sensing ion channels (ASICs) are proton-gated cation channels that are widely expressed in both the peripheral and central nervous systems. ASICs contribute to a variety of pathophysiological conditions that involve tissue acidosis, such as ischemic stroke, epileptic seizures and multiple sclerosis. Although much progress has been made in researching the structure-function relationship and pharmacology of ASICs, little is known about the trafficking of ASICs and its contribution to ASIC function. The recent identification of the mechanism of membrane insertion and endocytosis of ASIC1a highlights the emerging role of ASIC trafficking in regulating its pathophysiological functions. In this review, we summarize the recent advances and discuss future directions on this topic.
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Affiliation(s)
- Wei-Zheng Zeng
- a Discipline of Neuroscience and Department of Anatomy; Histology and Embryology; Institute of Medical Sciences ; Shanghai Jiao Tong University School of Medicine ; Shanghai 200025 , P.R. China
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10
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Osmakov DI, Andreev YA, Kozlov SA. Acid-sensing ion channels and their modulators. BIOCHEMISTRY (MOSCOW) 2015; 79:1528-45. [PMID: 25749163 DOI: 10.1134/s0006297914130069] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
According to a modern look acid-sensing ion channels (ASICs) are one of the most important receptors that perceive pH change in the body. ASICs represent proton-gated Na+-selective channels, which are expressed in neurons of the central and peripheral nervous system. These channels are attracting attention of researchers around the world, as they are involved in various physiological processes in the body. Drop of pH may occur in tissues in norm (e.g. the accumulation of lactic acid, the release of protons upon ATP hydrolysis) and pathology (inflammation, ischemic stroke, tissue damage and seizure). These processes are accompanied by unpleasant pain sensations, which may be short-lived or can lead to chronic inflammatory diseases. Modulators of ASIC channels activity are potential candidates for new effective analgesic and neuroprotection drugs. This review summarizes available information about structure, function, and physiological role of ASIC channels. In addition a description of all known ligands of these channels and their practical relevance is provided.
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Affiliation(s)
- D I Osmakov
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
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11
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Vick JS, Askwith CC. ASICs and neuropeptides. Neuropharmacology 2015; 94:36-41. [PMID: 25592215 DOI: 10.1016/j.neuropharm.2014.12.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 12/04/2014] [Accepted: 12/08/2014] [Indexed: 11/30/2022]
Abstract
The acid sensing ion channels (ASICs) are proton-gated cation channels expressed throughout the nervous system. ASICs are activated during acidic pH fluctuations, and recent work suggests that they are involved in excitatory synaptic transmission. ASICs can also induce neuronal degeneration and death during pathological extracellular acidosis caused by ischemia, autoimmune inflammation, and traumatic injury. Many endogenous neuromodulators target ASICs to affect their biophysical characteristics and contributions to neuronal activity. One of the most unconventional types of modulation occurs with the interaction of ASICs and neuropeptides. Collectively, FMRFamide-related peptides and dynorphins potentiate ASIC activity by decreasing the proton-sensitivity of steady state desensitization independent of G protein-coupled receptor activation. By decreasing the proton-sensitivity of steady state desensitization, the FMRFamide-related peptides and dynorphins permit ASICs to remain active at more acidic basal pH. Unlike the dynorphins, some FMRFamide-related peptides also potentiate ASIC activity by slowing inactivation and increasing the sustained current. Through mechanistic studies, the modulation of ASICs by FMRFamide-related peptides and dynorphins appears to be through distinct interactions with the extracellular domain of ASICs. Dynorphins are expressed throughout the nervous system and can increase neuronal death during prolonged extracellular acidosis, suggesting that the interaction between dynorphins and ASICs may have important consequences for the prevention of neurological injury. The overlap in expression of FMRFamide-related peptides with ASICs in the dorsal horn of the spinal cord suggests that their interaction may have important consequences for the treatment of pain during injury and inflammation. This article is part of the Special Issue entitled 'Acid-Sensing Ion Channels in the Nervous System'.
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Affiliation(s)
- Jonathan S Vick
- The Department of Neuroscience, The Ohio State University Wexner Medical Center, United States
| | - Candice C Askwith
- The Department of Neuroscience, The Ohio State University Wexner Medical Center, United States.
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12
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Kellenberger S, Schild L. International Union of Basic and Clinical Pharmacology. XCI. Structure, Function, and Pharmacology of Acid-Sensing Ion Channels and the Epithelial Na+ Channel. Pharmacol Rev 2014; 67:1-35. [DOI: 10.1124/pr.114.009225] [Citation(s) in RCA: 193] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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13
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Radu BM, Dumitrescu DI, Marin A, Banciu DD, Iancu AD, Selescu T, Radu M. Advanced type 1 diabetes is associated with ASIC alterations in mouse lower thoracic dorsal root ganglia neurons. Cell Biochem Biophys 2014; 68:9-23. [PMID: 23723009 DOI: 10.1007/s12013-013-9678-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Acid-sensing ion channels (ASICs) from dorsal root ganglia (DRG) neurons are proton sensors during ischemia and inflammation. Little is known about their role in type 1 diabetes (T1D). Our study was focused on ASICs alterations determined by advanced T1D status. Primary neuronal cultures were obtained from lower (T9-T12) thoracic DRG neurons from Balb/c and TCR-HA(+/-)/Ins-HA(+/-) diabetic male mice (16 weeks of age). Patch-clamp recordings indicate a change in the number of small DRG neurons presenting different ASIC-type currents. Multiple molecular sites of ASICs are distinctly affected in T1D, probably due to particular steric constraints for glycans accessibility to the active site: (i) ASIC1 current inactivates faster, while ASIC2 is slower; (ii) PcTx1 partly reverts diabetes effects against ASIC1- and ASIC2-inactivations; (iii) APETx2 maintains unaltered potency against ASIC3 current amplitude, but slows ASIC3 inactivation. Immunofluorescence indicates opposite regulation of different ASIC transcripts while qRT-PCR shows that ASIC mRNA ranking (ASIC2 > ASIC1 > ASIC3) remains unaltered. In conclusion, our study has identified biochemical and biophysical ASIC changes in lower thoracic DRG neurons due to advanced T1D. As hypoalgesia is present in advanced T1D, ASICs alterations might be the cause or the consequence of diabetic insensate neuropathy.
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Affiliation(s)
- Beatrice Mihaela Radu
- Section of Anatomy and Histology, Department of Neurological, Neuropsychological, Morphological and Movement Sciences, University of Verona, Strada Le Grazie 8, 37134, Verona, Italy
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15
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Jing L, Chu XP, Zha XM. Three distinct motifs within the C-terminus of acid-sensing ion channel 1a regulate its surface trafficking. Neuroscience 2013; 247:321-7. [PMID: 23727453 DOI: 10.1016/j.neuroscience.2013.05.041] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Revised: 05/20/2013] [Accepted: 05/21/2013] [Indexed: 10/26/2022]
Abstract
Various protein motifs play a key role in regulating protein biogenesis and trafficking. Here, we discovered that three distinct motifs regulate the trafficking of acid-sensing ion channel 1a (ASIC1a), the primary neuronal proton receptor which plays critical roles in neurological diseases including stroke, multiple sclerosis and seizures. Mutating the PDZ binding motif of ASIC1a increased its surface expression and current density. In contrast, mutating either a RRGK motif or a KEAKR motif reduced ASIC1a surface expression and acid-activated current density. Mutating or deleting the RRGK motif also reduced pH sensitivity and the rate of desensitization of ASIC1a. These changes were likely due to a change in ASIC1a biogenesis; mutating either the RRGK or KEAKR motif reduced N-glycosylation of ASIC1a while mutating the PDZ binding motif had the opposite effect. Our results demonstrate that these C-terminal motifs are important for ASIC1a trafficking and channel function. In addition, in contrast to multiple previous studies, which all show that K/R containing motifs lead to endoplasmic reticulum (ER) retention, our findings indicate that these motifs can also be required for efficient trafficking.
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Affiliation(s)
- L Jing
- Department of Cell Biology and Neuroscience, University of South Alabama College of Medicine, 307 University Boulevard, MSB1201, Mobile, AL 36688, United States
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Zha XM. Acid-sensing ion channels: trafficking and synaptic function. Mol Brain 2013; 6:1. [PMID: 23281934 PMCID: PMC3562204 DOI: 10.1186/1756-6606-6-1] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 12/20/2012] [Indexed: 01/05/2023] Open
Abstract
Extracellular acidification occurs in the brain with elevated neural activity, increased metabolism, and neuronal injury. This reduction in pH can have profound effects on brain function because pH regulates essentially every single biochemical reaction. Therefore, it is not surprising to see that Nature evolves a family of proteins, the acid-sensing ion channels (ASICs), to sense extracellular pH reduction. ASICs are proton-gated cation channels that are mainly expressed in the nervous system. In recent years, a growing body of literature has shown that acidosis, through activating ASICs, contributes to multiple diseases, including ischemia, multiple sclerosis, and seizures. In addition, ASICs play a key role in fear and anxiety related psychiatric disorders. Several recent reviews have summarized the importance and therapeutic potential of ASICs in neurological diseases, as well as the structure-function relationship of ASICs. However, there is little focused coverage on either the basic biology of ASICs or their contribution to neural plasticity. This review will center on these topics, with an emphasis on the synaptic role of ASICs and molecular mechanisms regulating the spatial distribution and function of these ion channels.
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Affiliation(s)
- Xiang-ming Zha
- Department of Cell Biology and Neuroscience, College of Medicine, University of South Alabama, 307 University Blvd, MSB1201, Mobile, AL 36688, USA.
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Sherwood TW, Frey EN, Askwith CC. Structure and activity of the acid-sensing ion channels. Am J Physiol Cell Physiol 2012; 303:C699-710. [PMID: 22843794 DOI: 10.1152/ajpcell.00188.2012] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The acid-sensing ion channels (ASICs) are a family of proton-sensing channels expressed throughout the nervous system. Their activity is linked to a variety of complex behaviors including fear, anxiety, pain, depression, learning, and memory. ASICs have also been implicated in neuronal degeneration accompanying ischemia and multiple sclerosis. As a whole, ASICs represent novel therapeutic targets for several clinically important disorders. An understanding of the correlation between ASIC structure and function will help to elucidate their mechanism of action and identify potential therapeutics that specifically target these ion channels. Despite the seemingly simple nature of proton binding, multiple studies have shown that proton-dependent gating of ASICs is quite complex, leading to activation and desensitization through distinct structural components. This review will focus on the structural aspects of ASIC gating in response to both protons and the newly discovered activators GMQ and MitTx. ASIC modulatory compounds and their action on proton-dependent gating will also be discussed. This review is dedicated to the memory of Dale Benos, who made a substantial contribution to our understanding of ASIC activity.
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Affiliation(s)
- Thomas W Sherwood
- Dept. of Neuroscience, The Ohio State Univ. Wexner Medical Center, Columbus, OH 43210, USA
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Jiang Q, Zha XM, Chu XP. Inhibition of human acid-sensing ion channel 1b by zinc. INTERNATIONAL JOURNAL OF PHYSIOLOGY, PATHOPHYSIOLOGY AND PHARMACOLOGY 2012; 4:84-93. [PMID: 22837807 PMCID: PMC3403561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 05/08/2012] [Indexed: 06/01/2023]
Abstract
Acid-sensing ion channel 1b (ASIC1b) is expressed in peripheral sensory neurons and has been implicated in nociception. Understanding the modulation of ASIC1b will provide important insight into how ASIC1b contributes to pain sensation. In our previous study, we showed that zinc, an important modulator of pain sensation, reduces rat ASIC1b current. However, rat ASIC1b shows several important differences from its recently identified human homolog. Most noticeably, human ASIC1b (hASIC1b) has a sustained component, which may play a role in persistent pain. Therefore, we tested here the hypothesis that zinc modulates the current properties of hASIC1b. Bath application of zinc suppressed the peak amplitude of hASIC1b currents, with a half-maximum inhibitory concentration of 37 μM. However, zinc did not affect the sustained component of hASIC1b currents. The effect of zinc was independent of pH-dependent activation, steady-state desensitization, and extracellular Ca(2+), suggesting noncompetitive mechanisms. Further, we found that extracellular site(s) of the hASIC1b subunit is important for the effect of zinc. Mutating cysteine 196, but not cysteine 309, in the extracellular domain of the hASIC1b abolished the zinc inhibition. These results suggest that, through modulating cysteine196, zinc may have a modulatory role in acute pain.
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Affiliation(s)
- Qian Jiang
- Department of Basic Medical Science, University of Missouri-Kansas City School of MedicineKansas City, MO 64108, USA
| | - Xiang-Ming Zha
- Department of Cell Biology and Neuroscience, University of South Alabama College of MedicineMobile, AL 36688, USA
| | - Xiang-Ping Chu
- Department of Basic Medical Science, University of Missouri-Kansas City School of MedicineKansas City, MO 64108, USA
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N-glycosylation of acid-sensing ion channel 1a regulates its trafficking and acidosis-induced spine remodeling. J Neurosci 2012; 32:4080-91. [PMID: 22442073 DOI: 10.1523/jneurosci.5021-11.2012] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Acid-sensing ion channel-1a (ASIC1a) is a potential therapeutic target for multiple neurological diseases. We studied here ASIC1a glycosylation and trafficking, two poorly understood processes pivotal in determining the functional outcome of an ion channel. We found that most ASIC1a in the mouse brain was fully glycosylated. Inhibiting glycosylation with tunicamycin reduced ASIC1a surface trafficking, dendritic targeting, and acid-activated current density. N-glycosylation of the two glycosylation sites, Asn393 and Asn366, has differential effects on ASIC1a biogenesis. Maturation of Asn393 increased ASIC1a surface and dendritic trafficking, pH sensitivity, and current density. In contrast, glycosylation of Asn366 was dispensable for ASIC1a function and may be a rate-limiting step in ASIC1a biogenesis. In addition, we revealed that acidosis reduced the density and length of dendritic spines in a time- and ASIC1a-dependent manner. ASIC1a N366Q, which showed increased glycosylation and dendritic targeting, potentiated acidosis-induced spine loss. Conversely, ASIC1a N393Q, which had diminished dendritic targeting and inhibited ASIC1a current dominant-negatively, had the opposite effect. These data tie N-glycosylation of ASIC1a with its trafficking. More importantly, by revealing a site-specific effect of acidosis on dendritic spines, our findings suggest that these processes have an important role in regulating synaptic plasticity and determining long-term consequences in diseases that generate acidosis.
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