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Weak Ultrasound Contributes to Neuromodulatory Effects in the Rat Motor Cortex. Int J Mol Sci 2023; 24:ijms24032578. [PMID: 36768901 PMCID: PMC9917173 DOI: 10.3390/ijms24032578] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/23/2023] [Accepted: 01/24/2023] [Indexed: 01/31/2023] Open
Abstract
Transcranial focused ultrasound (tFUS) is a novel neuromodulating technique. It has been demonstrated that the neuromodulatory effects can be induced by weak ultrasound exposure levels (spatial-peak temporal average intensity, ISPTA < 10 mW/cm2) in vitro. However, fewer studies have examined the use of weak tFUS to potentially induce long-lasting neuromodulatory responses in vivo. The purpose of this study was to determine the lower-bound threshold of tFUS stimulation for inducing neuromodulation in the motor cortex of rats. A total of 94 Sprague-Dawley rats were used. The sonication region aimed at the motor cortex under weak tFUS exposure (ISPTA of 0.338-12.15 mW/cm2). The neuromodulatory effects of tFUS on the motor cortex were evaluated by the changes in motor-evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS). In addition to histology analysis, the in vitro cell culture was used to confirm the neuromodulatory mechanisms following tFUS stimulation. In the results, the dose-dependent inhibitory effects of tFUS were found, showing increased intensities of tFUS suppressed MEPs and lasted for 30 min. Weak tFUS significantly decreased the expression of excitatory neurons and increased the expression of inhibitory GABAergic neurons. The PIEZO-1 proteins of GABAergic neurons were found to involve in the inhibitory neuromodulation. In conclusion, we show the use of weak ultrasound to induce long-lasting neuromodulatory effects and explore the potential use of weak ultrasound for future clinical neuromodulatory applications.
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2
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Anand A, Tseng HC, Chiang HC, Hsu WH, Liao YF, Lu SHA, Tsai SY, Pan CY, Chen YT. Significant Elevation in Potassium Concentration Surrounding Stimulated Excitable Cells Revealed by an Aptamer-Modified Nanowire Transistor. ACS APPLIED BIO MATERIALS 2021; 4:6865-6873. [PMID: 35006986 DOI: 10.1021/acsabm.1c00584] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recording ion fluctuations surrounding biological cells with a nanoelectronic device offers seamless integration of nanotechnology into living organisms and is essential for understanding cellular activities. The concentration of potassium ion in the extracellular fluid (CK+ex) is a critical determinant of cell membrane potential and must be maintained within an appropriate range. Alteration in CK+ex can affect neuronal excitability, induce heart arrhythmias, and even trigger seizure-like reactions in the brain. Therefore, monitoring local fluctuations in real time provides an early diagnosis of the occurrence of the K+-induced pathophysiological responses. Here, we modified the surface of a silicon nanowire field-effect transistor (SiNW-FET) with K+-specific DNA-aptamers (AptK+) to monitor the real-time variations of CK+ex in primary cultured rat embryonic cortical neurons or human embryonic stem cell-derived cardiomyocytes. The binding affinity of AptK+ to K+, determined by measuring the dissociation constant of the AptK+-K+ complex (Kd = 10.1 ± 0.9 mM), is at least 38-fold higher than other ions (e.g., Na+, Ca2+, and Mg2+). By placing cultured cortical neurons over an AptK+/SiNW-FET device, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) stimulation raised the CK+ex dose-dependently to 16 mM when AMPA concentration was >10 μM; this elevation could be significantly suppressed by an AMPA receptor antagonist, 6,7-dinitroquinoxaline-2,3-dione. Likewise, the stimulation of isoproterenol to cardiomyocytes raised the CK+ex to 6-8 mM, with a concomitant increase in the beating rate. This study utilizing a robust nanobiosensor to detect real-time ion fluctuations surrounding excitable cells underlies the importance of ion homeostasis and offers the feasibility of developing an implant device for real-time monitoring.
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Affiliation(s)
- Ankur Anand
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan.,Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - Hui-Chiun Tseng
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan
| | - Hsu-Cheng Chiang
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Wan-Hsuan Hsu
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan
| | - Yi-Fan Liao
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan.,Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
| | - Serena Huei-An Lu
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan
| | - Su-Yi Tsai
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan
| | - Chien-Yuan Pan
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan
| | - Yit-Tsong Chen
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan.,Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
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Halty-deLeon L, Hansson BS, Wicher D. The Drosophila melanogaster Na +/Ca 2+ Exchanger CALX Controls the Ca 2+ Level in Olfactory Sensory Neurons at Rest and After Odorant Receptor Activation. Front Cell Neurosci 2018; 12:186. [PMID: 30018538 PMCID: PMC6038709 DOI: 10.3389/fncel.2018.00186] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 06/11/2018] [Indexed: 11/13/2022] Open
Abstract
CALX, the Na+/Ca2+ exchanger in Drosophila, is highly expressed in the outer dendrites of olfactory sensory neurons (OSNs) which are equipped with the odorant receptors (ORs). Insect OR/Orco dimers are nonselective cation channels that pass also calcium which leads to elevated calcium levels after OR activation. CALX exhibits an anomalous regulation in comparison to its homolog in mammals sodium/calcium exchanger, NCX: it is inhibited by increasing intracellular calcium concentration [Ca2+]i. Thus, CALX mediates only Ca2+ efflux, not influx. The main goal of this study was to elucidate a possible role of this protein in the olfactory response. We first asked whether already described NCX inhibitors were capable of blocking CALX. By means of calcium imaging techniques in ex-vivo preparations and heterologous expression systems, we determined ORM-10962 as a potent CALX inhibitor. CALX inhibition did not affect the odor response but it affected the recovery of the calcium level after this response. In addition, CALX controls the calcium level of OSNs at rest.
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Affiliation(s)
- Lorena Halty-deLeon
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Bill S Hansson
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Dieter Wicher
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Jena, Germany
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4
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Anand A, Chi CH, Banerjee S, Chou MY, Tseng FG, Pan CY, Chen YT. The Extracellular Zn 2+ Concentration Surrounding Excited Neurons Is High Enough to Bind Amyloid-β Revealed by a Nanowire Transistor. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1704439. [PMID: 29770576 DOI: 10.1002/smll.201704439] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 03/07/2018] [Indexed: 06/08/2023]
Abstract
The Zn2+ stored in the secretory vesicles of glutamatergic neurons is coreleased with glutamate upon stimulation, resulting in the elevation of extracellular Zn2+ concentration (CZn2+ex). This elevation of CZn2+ex regulates the neurotransmission and facilitates the fibrilization of amyloid-β (Aβ). However, the exact CZn2+ex surrounding neurons under (patho)physiological conditions is not clear and the connection between CZn2+ex and the Aβ fibrilization remains obscure. Here, a silicon nanowire field-effect transistor (SiNW-FET) with the Zn2+ -sensitive fluorophore, FluoZin-3 (FZ-3), to quantify the CZn2+ex in real time is modified. This FZ-3/SiNW-FET device has a dissociation constant of ≈12 × 10-9 m against Zn2+ . By placing a coverslip seeded with cultured embryonic cortical neurons atop an FZ-3/SiNW-FET, the CZn2+ex elevated to ≈110 × 10-9 m upon stimulation with α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA). Blockers against the AMPA receptor or exocytosis greatly suppress this elevation, indicating that the Zn2+ stored in the synaptic vesicles is the major source responsible for this elevation of CZn2+ex. In addition, a SiNW-FET modified with Aβ could bind Zn2+ with a dissociation constant of ≈633 × 10-9 m and respond to the Zn2+ released from AMPA-stimulated neurons. Therefore, the CZn2+ex can reach a level high enough to bind Aβ and the Zn2+ homeostasis can be a therapeutic strategy to prevent neurodegeneration.
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Affiliation(s)
- Ankur Anand
- Department of Engineering and System Science, National Tsing Hua University, Hsinchu, 30013, Taiwan
- Nanoscience and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei, 115, Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 106, Taiwan
| | - Chih-Hung Chi
- Department of Life Science, National Taiwan University, Taipei, 106, Taiwan
| | - Subhasree Banerjee
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 106, Taiwan
- Department of Life Science, National Taiwan University, Taipei, 106, Taiwan
- Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan
| | - Ming-Yi Chou
- Department of Life Science, National Taiwan University, Taipei, 106, Taiwan
| | - Fan-Gang Tseng
- Department of Engineering and System Science, National Tsing Hua University, Hsinchu, 30013, Taiwan
- Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu, 30013, Taiwan
- Research Center for Applied Sciences, Academia Sinica, Taipei, 115, Taiwan
| | - Chien-Yuan Pan
- Department of Life Science, National Taiwan University, Taipei, 106, Taiwan
| | - Yit-Tsong Chen
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 106, Taiwan
- Department of Chemistry, National Taiwan University, Taipei, 106, Taiwan
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5
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Li Y, Jiao Q, Xu H, Du X, Shi L, Jia F, Jiang H. Biometal Dyshomeostasis and Toxic Metal Accumulations in the Development of Alzheimer's Disease. Front Mol Neurosci 2017; 10:339. [PMID: 29114205 PMCID: PMC5660707 DOI: 10.3389/fnmol.2017.00339] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 10/05/2017] [Indexed: 12/14/2022] Open
Abstract
Biometal dyshomeostasis and toxic metal accumulation are common features in many neurodegenerative disorders, including Alzheimer’s disease (AD), Parkinson’s disease, and Huntington’s disease. The neurotoxic effects of metal imbalance are generally associated with reduced enzymatic activities, elevated protein aggregation and oxidative stress in the central nervous system, in which a cascade of events lead to cell death and neurodegeneration. Although the links between biometal imbalance and neurodegenerative disorders remain elusive, a major class of endogenous proteins involved in metal transport has been receiving increasing attention over recent decades. The abnormal expression of these proteins has been linked to biometal imbalance and to the pathogenesis of AD. Here, we present a brief overview of the physiological roles of biometals including iron, zinc, copper, manganese, magnesium and calcium, and provide a detailed description of their transporters and their synergistic involvement in the development of AD. In addition, we also review the published data relating to neurotoxic metals in AD, including aluminum, lead, cadmium, and mercury.
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Affiliation(s)
- Yong Li
- Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Department of Physiology, Medical College of Qingdao University, Qingdao, China.,Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Qingdao University, Qingdao, China
| | - Qian Jiao
- Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Department of Physiology, Medical College of Qingdao University, Qingdao, China.,Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Qingdao University, Qingdao, China
| | - Huamin Xu
- Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Department of Physiology, Medical College of Qingdao University, Qingdao, China.,Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Qingdao University, Qingdao, China
| | - Xixun Du
- Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Department of Physiology, Medical College of Qingdao University, Qingdao, China.,Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Qingdao University, Qingdao, China
| | - Limin Shi
- Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Department of Physiology, Medical College of Qingdao University, Qingdao, China.,Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Qingdao University, Qingdao, China
| | - Fengju Jia
- Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Department of Physiology, Medical College of Qingdao University, Qingdao, China.,Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Qingdao University, Qingdao, China
| | - Hong Jiang
- Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Department of Physiology, Medical College of Qingdao University, Qingdao, China.,Shandong Provincial Collaborative Innovation Center for Neurodegenerative Disorders, Qingdao University, Qingdao, China
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6
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Hung HH, Kao LS, Liu PS, Huang CC, Yang DM, Pan CY. Dopamine elevates intracellular zinc concentration in cultured rat embryonic cortical neurons through the cAMP-nitric oxide signaling cascade. Mol Cell Neurosci 2017; 82:35-45. [DOI: 10.1016/j.mcn.2017.04.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 03/16/2017] [Accepted: 04/14/2017] [Indexed: 01/11/2023] Open
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Anand A, Liu CR, Chou AC, Hsu WH, Ulaganathan RK, Lin YC, Dai CA, Tseng FG, Pan CY, Chen YT. Detection of K + Efflux from Stimulated Cortical Neurons by an Aptamer-Modified Silicon Nanowire Field-Effect Transistor. ACS Sens 2017; 2:69-79. [PMID: 28722429 DOI: 10.1021/acssensors.6b00505] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The concentration gradient of K+ across the cell membrane of a neuron determines its resting potential and cell excitability. During neurotransmission, the efflux of K+ from the cell via various channels will not only decrease the intracellular K+ content but also elevate the extracellular K+ concentration. However, it is not clear to what extent this change could be. In this study, we developed a multiple-parallel-connected silicon nanowire field-effect transistor (SiNW-FET) modified with K+-specific DNA-aptamers (aptamer/SiNW-FET) for the real-time detection of the K+ efflux from cultured cortical neurons. The aptamer/SiNW-FET showed an association constant of (2.18 ± 0.44) × 106 M-1 against K+ and an either less or negligible response to other alkali metal ions. The α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) stimulation induced an outward current and hyperpolarized the membrane potential in a whole-cell patched neuron under a Na+/K+-free buffer. When neurons were placed atop the aptamer/SiNW-FET in a Na+/K+-free buffer, AMPA (13 μM) stimulation elevated the extracellular K+ concentration to ∼800 nM, which is greatly reduced by 6,7-dinitroquinoxaline-2,3-dione, an AMPA receptor antagonist. The EC50 of AMPA in elevating the extracellular K+ concentration was 10.3 μM. By stimulating the neurons with AMPA under a normal physiological buffer, the K+ concentration in the isolated cytosolic fraction was decreased by 75%. These experiments demonstrate that the aptamer/SiNW-FET is sensitive for detecting cations and the K+ concentrations inside and outside the neurons could be greatly changed to modulate the neuron excitability.
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Affiliation(s)
- Ankur Anand
- Nanoscience
and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei 115, Taiwan
- Department
of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan
- Institute
of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
| | - Chia-Rung Liu
- Institute
of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
| | | | | | - Rajesh Kumar Ulaganathan
- Nanoscience
and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei 115, Taiwan
- Institute
of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
| | | | | | - Fan-Gang Tseng
- Department
of Engineering and System Science, National Tsing Hua University, Hsinchu 30013, Taiwan
| | | | - Yit-Tsong Chen
- Institute
of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
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8
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Roles of Na+/Ca2+ exchanger isoforms NCX1 and NCX2 in motility in mouse ileum. Naunyn Schmiedebergs Arch Pharmacol 2016; 389:1081-90. [DOI: 10.1007/s00210-016-1271-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 07/03/2016] [Indexed: 12/13/2022]
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9
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Azuma YT, Hayashi S, Nishiyama K, Kita S, Mukai K, Nakajima H, Iwamoto T, Takeuchi T. Na(+) /Ca(2+) exchanger-heterozygote knockout mice display increased relaxation in gastric fundus and accelerated gastric transit in vivo. Neurogastroenterol Motil 2016; 28:827-36. [PMID: 26787195 DOI: 10.1111/nmo.12779] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 12/25/2015] [Indexed: 01/31/2023]
Abstract
BACKGROUND For the contraction and relaxation of gastric smooth muscles to occur, the intracellular Ca(2+) concentration must be increased and decreased, respectively. The Na(+) /Ca(2+) exchanger (NCX) is a plasma membrane transporter that is involved in regulating intracellular Ca(2+) concentrations. METHODS To determine the role of NCX in gastrointestinal tissues, we examined electric field stimulation (EFS)-induced relaxations in the circular muscles of the gastric fundus in NCX1 and NCX2 heterozygote knockout mice (HET). KEY RESULTS The myenteric plexus layers and the longitudinal and circular muscle layers in the gastric fundus of wild-type mice (WT) were strongly immunoreactive to NCX1 and NCX2. EFS induced a transient relaxation that was apparent during the stimulus and a sustained relaxation that persisted after the end of the stimulus. The amplitudes of EFS-induced transient relaxation and sustained relaxation were greater in NCX1 HET and NCX2 HET than in WT. When an inhibitor of nitric oxide synthase was added following the EFS, neither NCX1 HET nor NCX2 HET exhibited transient relaxation, similar to WT. Furthermore, when a PACAP antagonist was added following the EFS, sustained relaxation in NCX1 HET and NCX2 HET was not observed, similar to WT. Next, we examined the effect of NCX heterozygous deficiency on relaxation in response to NO and PACAP in smooth muscles. The magnitude of NOR-1- and PACAP-induced relaxations in NCX1 HET and NCX2 HET was similar to that of WT. CONCLUSIONS & INFERENCES In this study, we demonstrate that NCX1 and NCX2 expressed in neurons regulate the motility in the gastric fundus.
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Affiliation(s)
- Y T Azuma
- Laboratory of Veterinary Pharmacology, Division of Veterinary Science, Osaka Prefecture University Graduate School of Life and Environmental Science, Osaka, Japan
| | - S Hayashi
- Laboratory of Veterinary Pharmacology, Division of Veterinary Science, Osaka Prefecture University Graduate School of Life and Environmental Science, Osaka, Japan
| | - K Nishiyama
- Laboratory of Veterinary Pharmacology, Division of Veterinary Science, Osaka Prefecture University Graduate School of Life and Environmental Science, Osaka, Japan
| | - S Kita
- Department of Pharmacology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - K Mukai
- Laboratory of Veterinary Pharmacology, Division of Veterinary Science, Osaka Prefecture University Graduate School of Life and Environmental Science, Osaka, Japan
| | - H Nakajima
- Laboratory of Veterinary Pharmacology, Division of Veterinary Science, Osaka Prefecture University Graduate School of Life and Environmental Science, Osaka, Japan
| | - T Iwamoto
- Department of Pharmacology, Faculty of Medicine, Fukuoka University, Fukuoka, Japan
| | - T Takeuchi
- Laboratory of Veterinary Pharmacology, Division of Veterinary Science, Osaka Prefecture University Graduate School of Life and Environmental Science, Osaka, Japan
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10
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Wu PC, Kao LS. Calcium regulation in mouse mesencephalic neurons-Differential roles of Na(+)/Ca(2+) exchanger, mitochondria and endoplasmic reticulum. Cell Calcium 2016; 59:299-311. [PMID: 27020658 DOI: 10.1016/j.ceca.2016.03.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Revised: 03/14/2016] [Accepted: 03/19/2016] [Indexed: 12/13/2022]
Abstract
Midbrain dopaminergic (DA) neurons are the key to finely tune the voluntary movement, habit and motivation. The progressive and selective degeneration of these neurons is a pathological hallmark of Parkinson's disease (PD). The susceptibility of DA neurons in the SNpc may result from differences in how Ca(2+) is handled. However, very little information is available about the mechanisms involved in the regulation of intracellular Ca(2+) concentration ([Ca(2+)]i) in DA neurons. In this study, the relative contributions of various Na(+)/Ca(2+) exchangers and their interplay with internal Ca(2+) stores, endoplasmic reticulum (ER) and the mitochondria, in the regulation of the [Ca(2+)]i of mouse mesencephalic neurons were characterized. Both the K(+)-dependent Na(+)/Ca(2+) exchanger (NCKX) and the K(+)-independent Na(+)/Ca(2+) exchanger (NCX) can be detected and are functional in DA and non-DA neurons. NCX accounts for the larger component of Na(+)/Ca(2+) exchange activity. Single-cell RT-PCR analysis showed each individual neuron expressed a distinct set of the Na(+)/Ca(2+) exchangers. Furthermore, the Na(+)/Ca(2+) exchangers play prominent roles in removing [Ca(2+)]i induced by glutamate but not [Ca(2+)]i induced by depolarization. The mitochondria serve as a major Ca(2+) sink and are functionally located close to NCX. In contrast, the ER is functionally located close to NCKX and acts primarily as a Ca(2+) source with marginal effects. This study reveals that the Na(+)/Ca(2+) exchangers, the ER and the mitochondria, which cooperate interactively, act similarly when regulating [Ca(2+)]i in mesencephalic DA and non-DA neurons. The heterogeneous expression of multiple types of Na(+)/Ca(2+) exchangers and the quantitative differences found in [Ca(2+)]i regulation, together with other risk factors specific to DA neurons such as dopamine oxidation resulting in oxidative stress, may drive these cells to undergo selective degeneration.
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Affiliation(s)
- Pei-Chun Wu
- Brain Research Center, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Lung-Sen Kao
- Brain Research Center, National Yang-Ming University, Taipei, Taiwan, ROC; Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan, ROC.
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11
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Chou AC, Ju YT, Pan CY. Calmodulin Interacts with the Sodium/Calcium Exchanger NCX1 to Regulate Activity. PLoS One 2015; 10:e0138856. [PMID: 26421717 PMCID: PMC4589332 DOI: 10.1371/journal.pone.0138856] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 09/04/2015] [Indexed: 11/22/2022] Open
Abstract
Changes in intracellular Ca2+ concentrations ([Ca2+]i) are an important signal for various physiological activities. The Na+/Ca2+ exchangers (NCX) at the plasma membrane transport Ca2+ into or out of the cell according to the electrochemical gradients of Na+ and Ca2+ to modulate [Ca2+]i homeostasis. Calmodulin (CaM) senses [Ca2+]i changes and relays Ca2+ signals by binding to target proteins such as channels and transporters. However, it is not clear how calmodulin modulates NCX activity. Using CaM as a bait, we pulled down the intracellular loops subcloned from the NCX1 splice variants NCX1.1 and NCX1.3. This interaction requires both Ca2+ and a putative CaM-binding segment (CaMS). To determine whether CaM modulates NCX activity, we co-expressed NCX1 splice variants with CaM or CaM1234 (a Ca2+-binding deficient mutant) in HEK293T cells and measured the increase in [Ca2+]i contributed by the influx of Ca2+ through NCX. Deleting the CaMS from NCX1.1 and NCX1.3 attenuated exchange activity and decreased membrane localization. Without the mutually exclusive exon, the exchange activity was decreased and could be partially rescued by CaM1234. Point-mutations at any of the 4 conserved a.a. residues in the CaMS had differential effects in NCX1.1 and NCX1.3. Mutating the first two conserved a.a. in NCX1.1 decreased exchange activity; mutating the 3rd or 4th conserved a.a. residues did not alter exchange activity, but CaM co-expression suppressed activity. Mutating the 2nd and 3rd conserved a.a. residues in NCX1.3 decreased exchange activity. Taken together, our results demonstrate that CaM senses changes in [Ca2+]i and binds to the cytoplasmic loop of NCX1 to regulate exchange activity.
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Affiliation(s)
- Ai-Chuan Chou
- Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - Yu-Ten Ju
- Department of Animal Science and Technology, National Taiwan University, Taipei, Taiwan
| | - Chien-Yuan Pan
- Department of Life Science, National Taiwan University, Taipei, Taiwan
- Graduate Institute of Brain and Mind Sciences, National Taiwan University, Taipei, Taiwan
- * E-mail:
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12
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Hung HH, Huang WP, Pan CY. Dopamine- and zinc-induced autophagosome formation facilitates PC12 cell survival. Cell Biol Toxicol 2014; 29:415-29. [PMID: 24077806 DOI: 10.1007/s10565-013-9261-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 09/11/2013] [Indexed: 12/29/2022]
Abstract
Dopamine oxidation and divalent cations have been reported to induce neuronal cell death. Although autophagy is involved in neuronal cell death, it has also been suggested to facilitate cell survival. We sought to investigate the role of autophagy in PC12 cells and cultured neurons treated with dopamine and Zn2+. Cells expressing EGFP-LC3 were treated with high concentrations of dopamine and Zn2+, and the formation of EGFP-LC3 fluorescence aggregates was monitored. Our results showed a significant increase in the number of fluorescent puncta in the cytosol of PC12 cells treated with these chemicals. These treatments enhanced LC3 lipidation levels in PC12 cells. Decreasing the ATG7 protein level using specific small interference RNA (siRNA) and pretreating with phosphatidylinositol 3-phosphate kinase blockers, wortmannin and LY294002, inhibited puncta formation. Dopamine or Zn2+ treatment significantly elevated the intracellular Zn2+ concentration ([Zn2+] i ); however, inhibiting the [Zn2+] i elevation in dopamine-treated cells suppressed the puncta formation. LY294002 or siRNA-directed members of the autophagy pathway increased the fraction of phosphatidylserine present on the outer membrane leaflet in PC12 cells treated with dopamine or Zn2+, suggesting an increase in apoptosis. Primary embryonic midbrain neurons expressing EGFP-LC3 also displayed a significant increase in the number of fluorescent aggregates in cells upon treatment with dopamine or Zn2+. Dopamine or Zn2+ treatment significantly elevated the [Zn2+] i in neurons and caused neuronal death. Our results indicate that treating cells with dopamine and Zn2+ results in the activation of the autophagy pathway in an effort to enhance cell survival.
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13
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Wang CH, Chen YF, Wu CY, Wu PC, Huang YL, Kao CH, Lin CH, Kao LS, Tsai TF, Wei YH. Cisd2 modulates the differentiation and functioning of adipocytes by regulating intracellular Ca2+ homeostasis. Hum Mol Genet 2014; 23:4770-85. [PMID: 24833725 DOI: 10.1093/hmg/ddu193] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
CISD2 is a causative gene associated with Wolfram syndrome (WFS). However, it remains a mystery as to how the loss of CISD2 causes metabolic defects in patients with WFS. Investigation on the role played by Cisd2 in specific cell types may help us to resolve these underlying mechanisms. White adipose tissue (WAT) is central to the maintenance of energy metabolism and glucose homeostasis in humans. In this study, adipocyte-specific Cisd2 knockout (KO) mice showed impairment in the development of epididymal WAT (eWAT) in the cell autonomous manner. A lack of Cisd2 caused defects in the biogenesis and function of mitochondria during differentiation of adipocytes in vitro. Insulin-stimulated glucose uptake and secretion of adiponectin by the Cisd2 KO adipocytes were decreased. Moreover, Cisd2 deficiency increased the cytosolic level of Ca(2+) and induced Ca(2+)-calcineurin-dependent signaling that inhibited adipogenesis. Importantly, Cisd2 was found to interact with Gimap5 on the mitochondrial and ER membranes and thereby modulate mitochondrial Ca(2+) uptake associated with the maintenance of intracellular Ca(2+) homeostasis in adipocytes. Thus, it would seem that Cisd2 plays an important role in intracellular Ca(2+) homeostasis, which is required for the differentiation and functioning of adipocytes as well as the regulation of glucose homeostasis in mice.
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Affiliation(s)
| | - Yi-Fan Chen
- Institute of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan, Miaoli County 350, Taiwan Ph.D. Program for Translational Medicine, College of Medical Science and Technology, Taipei Medical University, Taipei 110, Taiwan
| | - Chia-Yu Wu
- Department of Life Sciences and Institute of Genome Sciences
| | - Pei-Chun Wu
- Department of Life Sciences and Institute of Genome Sciences Brain Research Center
| | - Yi-Long Huang
- Department of Life Sciences and Institute of Genome Sciences
| | - Cheng-Heng Kao
- Center of General Education, Chang Gung University, Taoyuan 333, Taiwan
| | - Chao-Hsiung Lin
- Department of Life Sciences and Institute of Genome Sciences
| | - Lung-Sen Kao
- Department of Life Sciences and Institute of Genome Sciences Brain Research Center
| | - Ting-Fen Tsai
- Department of Life Sciences and Institute of Genome Sciences Brain Research Center Aging and Health Research Center, National Yang-Ming University, Taipei 112, Taiwan Institute of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan, Miaoli County 350, Taiwan
| | - Yau-Huei Wei
- Institute of Biochemistry and Molecular Biology Department of Medicine, Mackay Medical College, Sanzhi, New Taipei City 252, Taiwan
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Chou MY, Lee CY, Liou HH, Pan CY. Phenytoin attenuates the hyper-exciting neurotransmission in cultured embryonic cortical neurons. Neuropharmacology 2014; 83:54-61. [PMID: 24721626 DOI: 10.1016/j.neuropharm.2014.03.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 03/17/2014] [Accepted: 03/22/2014] [Indexed: 11/26/2022]
Abstract
Phenytoin is an effective anti-epileptic drug that inhibits Na(+) channel activities; however, how phenytoin modulates synaptic transmission to soothe epileptic symptoms is not clear. To characterize the effects of phenytoin regulation on neurotransmission, we studied the electrophysical properties of cultured embryonic cortical neurons. Phenytoin inhibited the inward Na(+) current in a dose-dependent manner with an IC50 of 16.8 μM, and at 100 μM, the inhibitory effect of phenytoin on the Na(+) current was proportional to the frequency applied. In cultured neurons, phenytoin significantly decreased the action potential firing rate and the peak potential. To study the effect of phenytoin in neurotransmission, we measured the Ca(2+) responses from stimulated target neurons and their neighboring neurons. Phenytoin significantly suppressed the Ca(2+) responses evoked by strong stimulations in the target and neighboring neurons, and exerted a decreased inhibitory effect under moderate stimulation. Picrotoxin, a GABAA receptor antagonist, enhanced the recorded spontaneous excitatory postsynaptic current activities. After picrotoxin-induced enhancement, phenytoin had a more pronounced effect on the suppression of the spontaneous hyper-exciting excitatory postsynaptic current (>100 pA), but it only mildly inhibited the general excitatory postsynaptic current. Our results demonstrate that phenytoin suppresses the efficacy of neurotransmission especially for the high-frequency stimulation by reducing the Na(+) channel activity and can potentially alleviate epileptiform activity.
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Affiliation(s)
- Ming-Yi Chou
- Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - Chun-Yao Lee
- Department of Pharmacology and Neurology, National Taiwan University Hospital and College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Horng-Huei Liou
- Department of Pharmacology and Neurology, National Taiwan University Hospital and College of Medicine, National Taiwan University, Taipei, Taiwan.
| | - Chien-Yuan Pan
- Department of Life Science, National Taiwan University, Taipei, Taiwan; Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, Taiwan.
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15
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Yang YC, Kao LS. Regulation of sodium-calcium exchanger activity by creatine kinase. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 961:163-73. [PMID: 23224878 DOI: 10.1007/978-1-4614-4756-6_14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
It has been shown that in rat heart NCX1 exists in a macromolecular -complex including PKA, PKA-anchoring protein, PKC, and phosphatases PP1 and PP2A. In addition, several lines of evidence suggest that the interactions of the exchanger with other molecules are closely associated with its function in regulation of [Ca(2+)](i). NCX contains a large intracellular loop (NCXIL) that is responsible for regulating NCX activity. We used the yeast two-hybrid method to screen a human heart cDNA library and found that the C-terminal region of sarcomeric mitochondrial creatine kinase (sMiCK) interacted with NCX1IL. Among the four creatine kinase (CK) isozymes, both sMiCK and the muscle-type cytosolic creatine kinase (CKM) co-immunoprecipitated with NCX1. Both sMiCK and CKM were able to produce a recovery in the decreased NCX1 activity that was lost under energy-compromised conditions. This regulation is mediated through a putative PKC phosphorylation site of sMiCK and CKM. The catalytic activity of sMiCK and CKM is not required for their regulation of NCX1 activity. Our results suggest a novel mechanism for the regulation of NCX1 activity and a novel role for CK.
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Affiliation(s)
- Ya-Chi Yang
- Institute of Biochemistry and Molecular Biology, National Yang-Ming University, Taipei, Taiwan, Republic of China
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16
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Functional and structural properties of the NCKX2 Na(+)-Ca (2+)/K (+) exchanger: a comparison with the NCX1 Na (+)/Ca (2+) exchanger. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 961:81-94. [PMID: 23224872 DOI: 10.1007/978-1-4614-4756-6_8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Na(+)/Ca(2+)-K(+) exchangers (NCKX), alongside the more widely known Na(+)/Ca(2+) exchangers (NCX), are important players in the cellular Ca(2+) toolkit. But, unlike NCX, much less is known about the physiological roles of NCKX, while emergent evidence indicates that NCKX has highly specialized functions in cells and tissues where it is expressed. As their name implies, there are functional similarities in the properties of the two Ca(2+) exchanger families, but there are specific differences as well. Here, we compare and contrast their key functional properties of ionic dependence and affinities, as well as report on the effects of KB-R7943 - a compound that is widely used to differentiate the two exchangers. We also review structural similarities and differences between the two exchangers. The aim is to draw attention to key differences that will aid in differentiating the two exchangers in physiological contexts where both exist but perhaps play distinct roles.
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17
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Azuma YT, Nishiyama K, Kita S, Komuro I, Nakajima H, Iwamoto T, Takeuchi T. Na(+) /Ca(2+) exchanger 2-heterozygote knockout mice display decreased acetylcholine release and altered colonic motility in vivo. Neurogastroenterol Motil 2012; 24:e600-10. [PMID: 23072505 DOI: 10.1111/nmo.12029] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND The Na(+) /Ca(2+) exchanger (NCX) is a plasma membrane transporter involved in regulating intracellular Ca(2+) concentrations. NCX is critical for Ca(2+) regulation in cardiac muscle, vascular smooth muscle, and nerve fibers. However, little is known about the physiological role of NCX in the myenteric neurons and smooth muscles of the gastrointestinal tract. METHODS To determine the role of NCX1 and NCX2 in gastrointestinal tissues, we examined electric field stimulation (EFS)-induced responses in the longitudinal smooth muscle of the distal colon in NCX1- and NCX2-heterozygote knockout mice. KEY RESULTS We found that the amplitudes of EFS-induced relaxation that persisted during EFS were greater in NCX2 heterozygous mice (HET) than in wild-type mice (WT). Under the nonadrenergic, noncholinergic (NANC) condition, EFS-induced relaxation in NCX2 HET was similar in amplitude to that of WT. In addition, an NCX inhibitor, YM-244769 enhanced EFS-induced relaxation but did not affect EFS-induced relaxation under the NANC condition, as in NCX2 HET. Unlike NCX2 HET, NCX1 HET displayed no marked changes in colonic motility. These results indicate that cholinergic function in the colon is altered in NCX2 HET. The magnitude of acetylcholine (ACh)-induced contraction in NCX2 HET was similar to that in WT. In contrast, EFS-induced ACh release was reduced in NCX2 HET compared with that in WT. CONCLUSIONS & INFERENCES In this study, we demonstrate that NCX2 regulates colonic motility by altering ACh release onto the myenteric neurons of the distal colon.
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Affiliation(s)
- Y T Azuma
- Laboratory of Veterinary Pharmacology, Division of Veterinary Science, Osaka Prefecture University Graduate School of Life and Environmental Science, Osaka, Japan.
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Brittain MK, Brustovetsky T, Brittain JM, Khanna R, Cummins TR, Brustovetsky N. Ifenprodil, a NR2B-selective antagonist of NMDA receptor, inhibits reverse Na+/Ca2+ exchanger in neurons. Neuropharmacology 2012; 63:974-82. [PMID: 22820271 DOI: 10.1016/j.neuropharm.2012.07.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Revised: 07/02/2012] [Accepted: 07/05/2012] [Indexed: 11/25/2022]
Abstract
Glutamate-induced delayed calcium dysregulation (DCD) is causally linked to excitotoxic neuronal death. The mechanisms of DCD are not completely understood, but it has been proposed that the excessive influx of external Ca(2+) is essential for DCD. The NMDA-subtype of glutamate receptor (NMDAR) and the plasmalemmal Na(+)/Ca(2+) exchanger operating in the reverse mode (NCX(rev)) have been implicated in DCD. In experiments with "younger" neurons, 6-8 days in vitro (6-8 DIV), in which the NR2A-containing NMDAR expression is low, ifenprodil, an inhibitor of NR2B-containing NMDAR, completely prevented DCD whereas PEAQX, another NMDAR antagonist that preferentially interacts with NR2A-NMDAR, was without effect. With "older" neurons (13-16 DIV), in which NR2A- and NR2B-NMDARs are expressed to a greater extent, both ifenprodil and PEAQX applied separately failed to prevent DCD. However, combined application of ifenprodil and PEAQX completely averted DCD. Ifenprodil and ifenprodil-like NR2B-NMDAR antagonists Ro 25-6981 and Co 101244 but not PEAQX or AP-5 inhibited gramicidin- and Na(+)/NMDG-replacement-induced increases in cytosolic Ca(2+) mediated predominantly by NCX(rev). This suggests that ifenprodil, Ro 25-6981, and Co 101244 inhibit NCX(rev). The ability of ifenprodil to inhibit NCX(rev) correlates with its efficacy in preventing DCD and emphasizes an important role of NCX(rev) in DCD. Overall our data suggest that both NR2A- and NR2B-NMDARs are involved in DCD in "older" neurons, and it is necessary to inhibit both NMDARs and NCX(rev) to prevent glutamate-induced DCD.
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Affiliation(s)
- Matthew K Brittain
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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19
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Yi YH, Chang YS, Lin CH, Lew TS, Tang CY, Tseng WL, Tseng CP, Lo SJ. Integrin-mediated membrane blebbing is dependent on sodium-proton exchanger 1 and sodium-calcium exchanger 1 activity. J Biol Chem 2012; 287:10316-10324. [PMID: 22270364 DOI: 10.1074/jbc.m111.244962] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Integrin signaling and membrane blebbing modulate cell adhesion, spreading, and migration. However, the relationship between integrin signaling and membrane blebbing is unclear. Here, we show that an integrin-ligand interaction induces both membrane blebbing and changes in membrane permeability. Sodium-proton exchanger 1 (NHE1) and sodium-calcium exchanger 1 (NCX1) are membrane proteins located on the bleb membrane. Inhibition of NHE1 disrupts membrane blebbing and decreases changes in membrane permeability. However, inhibition of NCX1 enhances cell blebbing; cells become swollen because of NHE1 induced intracellular sodium accumulation. Our study found that NHE1 induced sodium influx is a driving force for membrane bleb growth, while sodium efflux (and calcium influx) induced by NCX1 in a reverse mode results in membrane bleb retraction. Together, these findings reveal a novel function for NHE1 and NCX1 in membrane blebbing and permeability, and establish a link between membrane blebbing and integrin signaling.
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Affiliation(s)
- Yung-Hsiang Yi
- Molecular Medicine Research Center, Chang Gung University, Kwei-Shan, Tao-Yuan 333, Taiwan, R.O.C.; Department of Biomedical Sciences, Chang Gung University, Kwei-Shan, Tao-Yuan 333, Taiwan, R.O.C
| | - Yu-Sun Chang
- Molecular Medicine Research Center, Chang Gung University, Kwei-Shan, Tao-Yuan 333, Taiwan, R.O.C
| | - Chi-Hung Lin
- Institute of Microbiology and Immunology, National Yang-Ming University, Taipei 112, Taiwan, R.O.C
| | - Tien-Shen Lew
- Department of Physiology, National Yang-Ming University, Taipei 112, Taiwan, R.O.C., and
| | - Chih-Yung Tang
- Department of Physiology, National Taiwan University, Taipei 100, Taiwan, R.O.C
| | - Wei-Lien Tseng
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Kwei-Shan, Tao-Yuan 333, Taiwan, R.O.C
| | - Ching-Ping Tseng
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Kwei-Shan, Tao-Yuan 333, Taiwan, R.O.C
| | - Szecheng J Lo
- Department of Biomedical Sciences, Chang Gung University, Kwei-Shan, Tao-Yuan 333, Taiwan, R.O.C.; Institute of Microbiology and Immunology, National Yang-Ming University, Taipei 112, Taiwan, R.O.C..
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20
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Brustovetsky T, Brittain MK, Sheets PL, Cummins TR, Pinelis V, Brustovetsky N. KB-R7943, an inhibitor of the reverse Na+ /Ca2+ exchanger, blocks N-methyl-D-aspartate receptor and inhibits mitochondrial complex I. Br J Pharmacol 2011; 162:255-70. [PMID: 20883473 DOI: 10.1111/j.1476-5381.2010.01054.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND AND PURPOSE An isothiourea derivative (2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiourea methane sulfonate (KB-R7943), a widely used inhibitor of the reverse Na(+) /Ca(2+) exchanger (NCX(rev)), was instrumental in establishing the role of NCX(rev) in glutamate-induced Ca(2+) deregulation in neurons. Here, the effects of KB-R7943 on N-methyl-D-aspartate (NMDA) receptors and mitochondrial complex I were tested. EXPERIMENTAL APPROACH Fluorescence microscopy, electrophysiological patch-clamp techniques and cellular respirometry with Seahorse XF24 analyzer were used with cultured hippocampal neurons; membrane potential imaging, respirometry and Ca(2+) flux measurements were made in isolated rat brain mitochondria. KEY RESULTS KB-R7943 inhibited NCX(rev) with IC(50) = 5.7 ± 2.1 µM, blocked NMDAR-mediated ion currents, and inhibited NMDA-induced increase in cytosolic Ca(2+) with IC(50) = 13.4 ± 3.6 µM but accelerated calcium deregulation and mitochondrial depolarization in glutamate-treated neurons. KB-R7943 depolarized mitochondria in a Ca(2+) -independent manner. Stimulation of NMDA receptors caused NAD(P)H oxidation that was coupled or uncoupled from ATP synthesis depending on the presence of Ca(2+) in the bath solution. KB-R7943, or rotenone, increased NAD(P)H autofluorescence under resting conditions and suppressed NAD(P)H oxidation following glutamate application. KB-R7943 inhibited 2,4-dinitrophenol-stimulated respiration of cultured neurons with IC(50) = 11.4 ± 2.4 µM. With isolated brain mitochondria, KB-R7943 inhibited respiration, depolarized organelles and suppressed Ca(2+) uptake when mitochondria oxidized complex I substrates but was ineffective when mitochondria were supplied with succinate, a complex II substrate. CONCLUSIONS AND IMPLICATIONS KB-R7943, in addition to NCX(rev) , blocked NMDA receptors in cultured hippocampal neurons and inhibited complex I in the mitochondrial respiratory chain. These findings are critical for the correct interpretation of experimental results obtained with KB-R7943 and a better understanding of its neuroprotective action.
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Affiliation(s)
- Tatiana Brustovetsky
- Department of Pharmacology and Toxicology Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA.
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Fu JD, Jiang P, Rushing S, Liu J, Chiamvimonvat N, Li RA. Na+/Ca2+ exchanger is a determinant of excitation-contraction coupling in human embryonic stem cell-derived ventricular cardiomyocytes. Stem Cells Dev 2010; 19:773-82. [PMID: 19719399 DOI: 10.1089/scd.2009.0184] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In adult cardiomyocytes (CMs), the Na(+)/Ca(2+) exchanger (NCX) is a well-defined determinant of Ca(2+) homeostasis. Developmentally, global NCX knockout in mice leads to abnormal myofibrillar organization, electrical defects, and early embryonic death. Little is known about the expression and function of NCX in human heart development. Self-renewable, pluripotent human embryonic stem cells (hESCs) can serve as an excellent experimental model. However, hESC-derived CMs are highly heterogeneous. A stably lentivirus-transduced hESC line (MLC2v-dsRed) was generated to express dsRed under the transcriptional control of the ventricular-restricted myosin light chain-2v (MLC2v) promoter. Electrophysiologically, dsRed+ cells differentiated from MLC2vdsRed hESCs displayed ventricular action potentials (AP), exclusively. Neither atrial nor pacemaker APs were observed. While I(Ca-L), I(f), and I(Kr) were robustly expressed, I(Ks) and I(K1) were absent in dsRed+ ventricular hESCCMs. Upon differentiation (7+40 to +90 days), the basal [Ca(2+)](i), Ca(2+) transient amplitude, maximum upstroke, and decay velocities significantly increased (P < 0.05). The I(Ca-L) antagonizer nifedipine (1 microM) decreased the Ca(2+) transient amplitude (to approximately 30%) and slowed the kinetics (by approximately 2-fold), but Ca(2+) transients could still be elicited even after complete ICa-L blockade, suggesting the presence of additional Ca(2+) influx(es). Indeed, Ni(2+)-sensitive INCX could be recorded in 7+40- and +90-day dsRed+ hESC-CMs, and its densities increased from -1.2 +/- 0.6 pA/pF at -120 mV and 3.6 +/- 1.0 pA/pF at 60 mV by 6- and 2-folds, respectively. With higher [Ca(2+)](i), 7+90-day ventricular hESC-CMs spontaneously but irregularly fired transients upon a single stimulus under an external Na(+)-free condition; however, without extracellular Na(+), nifedipine could completely inhibit Ca(2+) transients. We conclude that I(NCX) is functionally expressed in developing ventricular hESC-CMs and contributes to their excitation-contraction coupling.
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Affiliation(s)
- Ji-Dong Fu
- Human Embryonic Stem Cell Consortium, University of California, Davis, California, USA
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22
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Desai-Shah M, Cooper RL. Different mechanisms of Ca2+ regulation that influence synaptic transmission: comparison between crayfish and Drosophila neuromuscular junctions. Synapse 2010; 63:1100-21. [PMID: 19650116 DOI: 10.1002/syn.20695] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A brief historical background on synaptic transmission in relation to Ca(2+) dynamics and short-term facilitation is described. This study focuses on the mechanisms responsible for the regulation of intracellular calcium concentration ([Ca(2+)](i)) in high output terminals of larval Drosophila compared to a low-output terminal of the crayfish neuromuscular junction (NMJ). Three processes; plasmalemmal Na(+)/Ca(2+) exchanger [NCX], Ca(2+)-ATPase (PMCA), and sarcoplasmic/endoplasmic Ca(2+)-ATPase (SERCA) are important in regulating the [Ca(2+)](i) are examined. When the NCX is compromised by reduced [Na(+)](o), no consistent effect occurred; but a NCX blocker KB-R7943 decreased the excitatory postsynaptic potential (EPSP) amplitudes. Compromising the PMCA with pH 8.8 resulted in an increase in EPSP amplitude but treatment with a PMCA specific inhibitor carboxyeosin produced opposite results. Thapsigargin exposure to block the SERCA generally decreases EPSP amplitude. Compromising the activity of the above Ca(2+) regulating proteins had no substantial effects on short-term depression. The Kum(170TS) strain (with dysfunctional SERCA), showed a decrease in EPSP amplitudes including the first EPSP within the train. Synaptic transmission is altered by reducing the function of the above three [Ca(2+)](i) regulators; but they are not consistent among different species as expected. Results in crayfish NMJ were more consistent with expected results as compared to the Drosophila NMJ. It is predicated that different mechanisms are used for regulating the [Ca(2+)](i) in high and low output synaptic terminals.
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Affiliation(s)
- Mohati Desai-Shah
- Department of Biology, University of Kentucky, Lexington, Kentucky 40506-0225, USA
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23
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AMPA and metabotropic excitoxicity explain subplate neuron vulnerability. Neurobiol Dis 2009; 37:195-207. [PMID: 19822212 DOI: 10.1016/j.nbd.2009.10.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Revised: 09/30/2009] [Accepted: 10/02/2009] [Indexed: 01/08/2023] Open
Abstract
Cerebral hypoxia-ischemia results in unique patterns of injury during development owing to selective vulnerability of specific cell populations including subplate neurons. To evaluate the contribution of glutamate excitotoxicity, we studied enriched cultures of subplate neurons in comparison with cortical neurons, deriving expression profiles for glutamate receptor subunits by microarray and immunoblot. The excitotoxic potency of specific glutamate receptors was tested with selective agonists and antagonists. After 1 week in culture, subplate neurons are more sensitive to oxygen-glucose deprivation than cortical neurons, confirming in vivo observations. Subplate and cortical neurons are equally sensitive to glutamate and insensitive to NMDA. Subplate neurons are more sensitive than cortical neurons to AMPA and express twofold less GluR2. Subplate neurons express significantly more mGluR3, a receptor proposed to be protective. Despite this increased expression, group II mGluR agonists increase subplate neuron death and antagonists lessen glutamate excitotoxicity, suggesting a novel mechanism for subplate vulnerability.
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Storozhevykh TP, Senilova YE, Brustovetsky T, Pinelis VG, Brustovetsky N. Neuroprotective Effect of KB-R7943 Against Glutamate Excitotoxicity is Related to Mild Mitochondrial Depolarization. Neurochem Res 2009; 35:323-35. [DOI: 10.1007/s11064-009-0058-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/29/2009] [Indexed: 01/08/2023]
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Barrientos G, Bose DD, Feng W, Padilla I, Pessah IN. The Na+/Ca2+ exchange inhibitor 2-(2-(4-(4-nitrobenzyloxy)phenyl)ethyl)isothiourea methanesulfonate (KB-R7943) also blocks ryanodine receptors type 1 (RyR1) and type 2 (RyR2) channels. Mol Pharmacol 2009; 76:560-8. [PMID: 19509218 DOI: 10.1124/mol.109.057265] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Na(+)/Ca(2+) exchanger (NCX) is a plasma membrane transporter that moves Ca(2+) in or out of the cell, depending on membrane potential and transmembrane ion gradients. NCX is the main pathway for Ca(2+) extrusion from excitable cells. NCX inhibitors can ameliorate cardiac ischemia-reperfusion injury and promote high-frequency fatigue of skeletal muscle, purportedly by inhibiting the Ca(2+) inward mode of NCX. Here we tested two known NCX inhibitors, 2-(2-(4-(4-nitrobenzyloxy)phenyl)ethyl)-isothiourea methanesulfonate (KB-R7943) and the structurally related 2-[[4-[(4-Nitrophenyl)methoxy]phenyl]methyl]-4-thiazoli dinecarboxylic acid ethyl ester (SN-6), for their influence on electrically or caffeine-evoked Ca(2+) transients in adult dissociated flexor digitorum brevis (FDB) skeletal muscle fibers and human embryonic kidney (HEK) 293 cells that have stable expression of type 1 ryanodine receptor (RyR1). KB-R7943 (< or = 10 microM) reversibly attenuates electrically evoked Ca(2+) transients in FDB and caffeine-induced Ca(2+) release in HEK 293, whereas the structurally related NCX inhibitor SN-6 does not, suggesting that KB-R7943 directly inhibits RyR1. In support of this interpretation, KB-R7943 inhibits high-affinity binding of [(3)H]ryanodine to RyR1 (IC(50) = 5.1 +/- 0.9 microM) and the cardiac isoform RyR2 (IC(50) = 13.4 +/- 1.8 microM). KB-R7943 interfered with the gating of reconstituted RyR1 and RyR2 channels, reducing open probability (P(o)), shortening mean open time, and prolonging mean closed time. KB-R7943 was more effective at blocking RyR1 with cytoplasmic conditions favoring high P(o) compared with those favoring low P(o). SN-6 has negligible activity toward altering [(3)H]ryanodine binding of RyR1 and RyR2. Our results identify that KB-R7943 is a reversible, activity-dependent blocker of the two most broadly expressed RyR channel isoforms and contributes to its pharmacological and therapeutic activities.
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Affiliation(s)
- Genaro Barrientos
- Department of Molecular Biosciences, School of Veterinary Medicine, One Shields Avenue, University of California, Davis, CA 95616, USA
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Castaldo P, Cataldi M, Magi S, Lariccia V, Arcangeli S, Amoroso S. Role of the mitochondrial sodium/calcium exchanger in neuronal physiology and in the pathogenesis of neurological diseases. Prog Neurobiol 2008; 87:58-79. [PMID: 18952141 DOI: 10.1016/j.pneurobio.2008.09.017] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 09/23/2008] [Accepted: 09/29/2008] [Indexed: 11/26/2022]
Abstract
In neurons, as in other excitable cells, mitochondria extrude Ca(2+) ions from their matrix in exchange with cytosolic Na(+) ions. This exchange is mediated by a specific transporter located in the inner mitochondrial membrane, the mitochondrial Na(+)/Ca(2+) exchanger (NCX(mito)). The stoichiometry of NCX(mito)-operated Na(+)/Ca(2+) exchange has been the subject of a long controversy, but evidence of an electrogenic 3 Na(+)/1 Ca(2+) exchange is increasing. Although the molecular identity of NCX(mito) is still undetermined, data obtained in our laboratory suggest that besides the long-sought and as yet unfound mitochondrial-specific NCX, the three isoforms of plasmamembrane NCX can contribute to NCX(mito) in neurons and astrocytes. NCX(mito) has a role in controlling neuronal Ca(2+) homeostasis and neuronal bioenergetics. Indeed, by cycling the Ca(2+) ions captured by mitochondria back to the cytosol, NCX(mito) determines a shoulder in neuronal [Ca(2+)](c) responses to neurotransmitters and depolarizing stimuli which may then outlast stimulus duration. This persistent NCX(mito)-dependent Ca(2+) release has a role in post-tetanic potentiation, a form of short-term synaptic plasticity. By controlling [Ca(2+)](m) NCX(mito) regulates the activity of the Ca(2+)-sensitive enzymes pyruvate-, alpha-ketoglutarate- and isocitrate-dehydrogenases and affects the activity of the respiratory chain. Convincing experimental evidence suggests that supraphysiological activation of NCX(mito) contributes to neuronal cell death in the ischemic brain and, in epileptic neurons coping with seizure-induced ion overload, reduces the ability to reestablish normal ionic homeostasis. These data suggest that NCX(mito) could represent an important target for the development of new neurological drugs.
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Affiliation(s)
- P Castaldo
- Department of Neuroscience, Section of Pharmacology, Università Politecnica delle Marche, Via Tronto 10/A, 60020 Torrette di Ancona, Ancona, Italy
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