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Orth T, Pyanova A, Lux S, Kaiser P, Reinheimer I, Nielsen DL, Khalid JA, Rognant S, Jepps TA, Matchkov VV, Schubert R. Vascular smooth muscle BK channels limit ouabain-induced vasocontraction: Dual role of the Na/K-ATPase as a hub for Src-kinase and the Na/Ca-exchanger. FASEB J 2024; 38:e70046. [PMID: 39259502 DOI: 10.1096/fj.202400628rr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 08/20/2024] [Accepted: 08/29/2024] [Indexed: 09/13/2024]
Abstract
Large-conductance, calcium-activated potassium channels (BK channels) and the Na/K-ATPase are expressed universally in vascular smooth muscle. The Na/K-ATPase may act via changes in the intracellular Ca2+ concentration mediated by the Na/Ca exchanger (NCX) and via Src kinase. Both pathways are known to regulate BK channels. Whether BK channels functionally interact in vascular smooth muscle cells with the Na/K-ATPase remains to be elucidated. Thus, this study addressed the hypothesis that BK channels limit ouabain-induced vasocontraction. Rat mesenteric arteries were studied using isometric myography, FURA-2 fluorimetry and proximity ligation assay. The BK channel blocker iberiotoxin potentiated methoxamine-induced contractions. The cardiotonic steroid, ouabain (10-5 M), induced a contractile effect of IBTX at basal tension prior to methoxamine administration and enhanced the pro-contractile effect of IBTX on methoxamine-induced contractions. These facilitating effects of ouabain were prevented by the inhibition of either NCX or Src kinase. Furthermore, inhibition of NCX or Src kinase reduced the BK channel-mediated negative feedback regulation of arterial contraction. The effects of NCX and Src kinase inhibition were independent of each other. Co-localization of the Na/K-ATPase and the BK channel was evident. Our data suggest that BK channels limit ouabain-induced vasocontraction by a dual mechanism involving the NCX and Src kinase signaling. The data propose that the NCX and the Src kinase pathways, mediating the ouabain-induced activation of the BK channel, act in an independent manner.
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Affiliation(s)
- Tobias Orth
- Research Division Cardiovascular Physiology, European Center of Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Anastasia Pyanova
- Physiology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Augsburg, Germany
| | - Simon Lux
- Research Division Cardiovascular Physiology, European Center of Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Peter Kaiser
- Research Division Cardiovascular Physiology, European Center of Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | - Isabel Reinheimer
- Research Division Cardiovascular Physiology, European Center of Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
| | | | - Josef Ali Khalid
- Department of Biomedicine, Health, Aarhus University, Aarhus, Denmark
| | - Salomé Rognant
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas A Jepps
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Rudolf Schubert
- Research Division Cardiovascular Physiology, European Center of Angioscience (ECAS), Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
- Physiology, Institute of Theoretical Medicine, Faculty of Medicine, University of Augsburg, Augsburg, Germany
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2
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Boikov SI, Karelina TV, Sibarov DA, Antonov SM. Selective inhibitor of sodium-calcium exchanger, SEA0400, affects NMDA receptor currents and abolishes their calcium-dependent block by tricyclic antidepressants. Front Pharmacol 2024; 15:1432718. [PMID: 39156114 PMCID: PMC11327140 DOI: 10.3389/fphar.2024.1432718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2024] [Accepted: 07/22/2024] [Indexed: 08/20/2024] Open
Abstract
The open-channel block of N-methyl-D-aspartate receptors (NMDARs) and their calcium-dependent desensitization (CDD) represent conventional mechanisms of glutamatergic synapse regulation. In neurotrauma, neurodegeneration, and neuropathic pain the clinical benefits of cure with memantine, ketamine, Mg2+, and some tricyclic antidepressants are often attributed to NMDAR open-channel block, while possible involvement of NMDAR CDD in the therapy is not well established. Here the effects of selective high-affinity sodium-calcium exchanger (NCX) isoform 1 inhibitor, SEA0400, on NMDA-activated whole-cell currents and their block by amitriptyline, desipramine and clomipramine recorded by patch-clamp technique in cortical neurons of primary culture were studied. We demonstrated that in the presence of extracellular Ca2+, 50 nM SEA0400 caused a reversible decrease of the steady-state amplitude of NMDAR currents, whereas loading neurons with BAPTA or the removal of extracellular Ca2+ abolished the effect. The decrease did not exceed 30% of the amplitude and did not depend on membrane voltage. The external Mg2+ block and 50 nM SEA0400 inhibition of currents were additive, suggesting their independent modes of action. In the presence of Ca2+ SEA0400 speeded up the decay of NMDAR currents to the steady state determined by CDD. The measured IC50 value of 27 nM for SEA0400-induced inhibition coincides with that for NCX1. Presumably, SEA0400 effects are induced by an enhancement of NMDAR CDD through the inhibition of Ca2+ extrusion by NCX1. SEA0400, in addition, at nanomolar concentrations could interfere with Ca2+-dependent effect of tricyclic antidepressants. In the presence of 50 nM SEA0400, the IC50s for NMDAR inhibition by amitriptyline and desipramine increased by about 20 folds, as the Ca2+-dependent NMDAR inhibition disappeared. This observation highlights NCX1 involvement in amitriptyline and desipramine effects on NMDARs and unmasks competitive relationships between SEA0400 and these antidepressants. Neither amitriptyline nor desipramine could affect NCX3. The open-channel block of NMDARs by these substances was not affected by SEA0400. In agreement, SEA0400 did not change the IC50 for clomipramine, which acts as a pure NMDAR open-channel blocker. Thus, NCX seems to represent a promising molecular target to treat neurological disorders, because of the ability to modulate NMDARs by decreasing the open probability through the enhancement of their CDD.
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Affiliation(s)
| | | | | | - Sergei M. Antonov
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, Saint-Petersburg, Russia
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3
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Davis MJ, Zawieja SD. Pacemaking in the lymphatic system. J Physiol 2024. [PMID: 38520402 DOI: 10.1113/jp284752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 02/08/2024] [Indexed: 03/25/2024] Open
Abstract
Lymphatic collecting vessels exhibit spontaneous phasic contractions that are critical for lymph propulsion and tissue fluid homeostasis. This rhythmic activity is driven by action potentials conducted across the lymphatic muscle cell (LMC) layer to produce entrained contractions. The contraction frequency of a lymphatic collecting vessel displays exquisite mechanosensitivity, with a dynamic range from <1 to >20 contractions per minute. A myogenic pacemaker mechanism intrinsic to the LMCs was initially postulated to account for pressure-dependent chronotropy. Further interrogation into the cellular constituents of the lymphatic vessel wall identified non-muscle cell populations that shared some characteristics with interstitial cells of Cajal, which have pacemaker functions in the gastrointestinal and lower urinary tracts, thus raising the possibility of a non-muscle cell pacemaker. However, recent genetic knockout studies in mice support LMCs and a myogenic origin of the pacemaker activity. LMCs exhibit stochastic, but pressure-sensitive, sarcoplasmic reticulum calcium release (puffs and waves) from IP3R1 receptors, which couple to the calcium-activated chloride channel Anoctamin 1, causing depolarisation. The resulting electrical activity integrates across the highly coupled lymphatic muscle electrical syncytia through connexin 45 to modulate diastolic depolarisation. However, multiple other cation channels may also contribute to the ionic pacemaking cycle. Upon reaching threshold, a voltage-gated calcium channel-dependent action potential fires, resulting in a nearly synchronous calcium global calcium flash within the LMC layer to drive an entrained contraction. This review summarizes the key ion channels potentially responsible for the pressure-dependent chronotropy of lymphatic collecting vessels and various mechanisms of IP3R1 regulation that could contribute to frequency tuning.
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Affiliation(s)
- Michael J Davis
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO, USA
| | - Scott D Zawieja
- Department of Medical Pharmacology and Physiology, University of Missouri School of Medicine, Columbia, MO, USA
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4
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Bouron A. Neuronal Store-Operated Calcium Channels. Mol Neurobiol 2023:10.1007/s12035-023-03352-5. [PMID: 37118324 DOI: 10.1007/s12035-023-03352-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 04/13/2023] [Indexed: 04/30/2023]
Abstract
The endoplasmic reticulum (ER) is the major intracellular calcium (Ca2+) storage compartment in eukaryotic cells. In most instances, the mobilization of Ca2+ from this store is followed by a delayed and sustained uptake of Ca2+ through Ca2+-permeable channels of the cell surface named store-operated Ca2+ channels (SOCCs). This gives rise to a store-operated Ca2+ entry (SOCE) that has been thoroughly investigated in electrically non-excitable cells where it is the principal regulated Ca2+ entry pathway. The existence of this Ca2+ route in neurons has long been a matter of debate. However, a growing body of experimental evidence indicates that the recruitment of Ca2+ from neuronal ER Ca2+ stores generates a SOCE. The present review summarizes the main studies supporting the presence of a depletion-dependent Ca2+ entry in neurons. It also addresses the question of the molecular composition of neuronal SOCCs, their expression, pharmacological properties, as well as their physiological relevance.
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Affiliation(s)
- Alexandre Bouron
- Université Grenoble Alpes, CNRS, CEA, Inserm UA13 BGE, 38000, Grenoble, France.
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Gusev K, Shalygin A, Kolesnikov D, Shuyskiy L, Makeenok S, Glushankova L, Sivak K, Yakovlev K, Orshanskaya Y, Wang G, Bakhtyukov A, Derkach K, Shpakov A, Kaznacheyeva E. Reorganization and Suppression of Store-Operated Calcium Entry in Podocytes of Type 2 Diabetic Rats. Int J Mol Sci 2023; 24:ijms24087259. [PMID: 37108424 PMCID: PMC10139047 DOI: 10.3390/ijms24087259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 04/07/2023] [Accepted: 04/12/2023] [Indexed: 04/29/2023] Open
Abstract
Type 2 diabetes mellitus (DM2) is a widespread metabolic disorder that results in podocyte damage and diabetic nephropathy. Previous studies demonstrated that TRPC6 channels play a pivotal role in podocyte function and their dysregulation is associated with development of different kidney diseases including nephropathy. Here, using single channel patch clamp technique, we demonstrated that non-selective cationic TRPC6 channels are sensitive to the Ca2+ store depletion in human podocyte cell line Ab8/13 and in freshly isolated rat glomerular podocytes. Ca2+ imaging indicated the involvement of ORAI and sodium-calcium exchanger in Ca2+ entry induced upon store depletion. In male rats fed a high-fat diet combined with a low-dose streptozotocin injection, which leads to DM2 development, we observed the reduction of a store-operated Ca2+ entry (SOCE) in rat glomerular podocytes. This was accompanied by a reorganization of store-operated Ca2+ influx such that TRPC6 channels lost their sensitivity to Ca2+ store depletion and ORAI-mediated Ca2+ entry was suppressed in TRPC6-independent manner. Altogether our data provide new insights into the mechanism of SOCE organization in podocytes in the norm and in pathology, which should be taken into account when developing pharmacological treatment of the early stages of diabetic nephropathy.
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Affiliation(s)
- Konstantin Gusev
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg 194064, Russia
| | - Alexey Shalygin
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg 194064, Russia
| | - Dmitrii Kolesnikov
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg 194064, Russia
| | - Leonid Shuyskiy
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg 194064, Russia
| | - Sofia Makeenok
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg 194064, Russia
| | - Lyubov Glushankova
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg 194064, Russia
| | - Konstantin Sivak
- Smorodintsev Research Institute of Influenza WHO National Influenza Centre of Russia, St. Petersburg 197376, Russia
| | - Kirill Yakovlev
- Smorodintsev Research Institute of Influenza WHO National Influenza Centre of Russia, St. Petersburg 197376, Russia
| | - Yana Orshanskaya
- Smorodintsev Research Institute of Influenza WHO National Influenza Centre of Russia, St. Petersburg 197376, Russia
| | - Guanghui Wang
- Department of Pharmacology, College of Pharmaceutic Sciences, Soochow University, Suzhou 215031, China
| | - Andrey Bakhtyukov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg 194223, Russia
| | - Kira Derkach
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg 194223, Russia
| | - Alexander Shpakov
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg 194223, Russia
| | - Elena Kaznacheyeva
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg 194064, Russia
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Wang Q, #, Zhang Y, #, Du Q, Zhao X, Wang W, Zhai Q, Xiang M. SKF96365 impedes spinal glutamatergic transmission-mediated neuropathic allodynia. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2023; 27:39-48. [PMID: 36575932 PMCID: PMC9806642 DOI: 10.4196/kjpp.2023.27.1.39] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 08/18/2022] [Accepted: 09/08/2022] [Indexed: 12/29/2022]
Abstract
Spinal nerve injury causes mechanical allodynia and structural imbalance of neurotransmission, which were typically associated with calcium overload. Store-operated calcium entry (SOCE) is considered crucial elements-mediating intracellular calcium homeostasis, ion channel activity, and synaptic plasticity. However, the underlying mechanism of SOCE in mediating neuronal transmitter release and synaptic transmission remains ambiguous in neuropathic pain. Neuropathic rats were operated by spinal nerve ligations. Neurotransmissions were assessed by whole-cell recording in substantia gelatinosa. Immunofluorescence staining of STIM1 with neuronal and glial biomarkers in the spinal dorsal horn. The endoplasmic reticulum stress level was estimated from qRT-PCR. Intrathecal injection of SOCE antagonist SKF96365 dose-dependently alleviated mechanical allodynia in ipsilateral hind paws of neuropathic rats with ED50 of 18 μg. Immunofluorescence staining demonstrated that STIM1 was specifically and significantly expressed in neurons but not astrocytes and microglia in the spinal dorsal horn. Bath application of SKF96365 inhibited enhanced miniature excitatory postsynaptic currents in a dosage-dependent manner without affecting miniature inhibitory postsynaptic currents. Mal-adaption of SOCE was commonly related to endoplasmic reticulum (ER) stress in the central nervous system. SKF96365 markedly suppressed ER stress levels by alleviating mRNA expression of C/EBP homologous protein and heat shock protein 70 in neuropathic rats. Our findings suggested that nerve injury might promote SOCE-mediated calcium levels, resulting in long-term imbalance of spinal synaptic transmission and behavioral sensitization, SKF96365 produces antinociception by alleviating glutamatergic transmission and ER stress. This work demonstrated the involvement of SOCE in neuropathic pain, implying that SOCE might be a potential target for pain management.
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Affiliation(s)
- Qiru Wang
- Department of Pharmacy, Fudan University Shanghai Cancer Center, Minhang Branch, Shanghai 200240, China
| | - #
- Department of Pharmacy, Fudan University Shanghai Cancer Center, Minhang Branch, Shanghai 200240, China
| | - Yang Zhang
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai 200240, China
| | - #
- Department of Pharmacy, Fudan University Shanghai Cancer Center, Minhang Branch, Shanghai 200240, China
| | - Qiong Du
- Department of Pharmacy, Fudan University Shanghai Cancer Center, Minhang Branch, Shanghai 200240, China
| | - Xinjie Zhao
- Department of Pharmacy, Fudan University Shanghai Cancer Center, Minhang Branch, Shanghai 200240, China
| | - Wei Wang
- Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai 200240, China,Correspondence Ming Xiang, E-mail: , Qing Zhai, E-mail: , Wei Wang, E-mail:
| | - Qing Zhai
- Department of Pharmacy, Fudan University Shanghai Cancer Center, Minhang Branch, Shanghai 200240, China,Correspondence Ming Xiang, E-mail: , Qing Zhai, E-mail: , Wei Wang, E-mail:
| | - Ming Xiang
- Department of Pharmacy, Fudan University Shanghai Cancer Center, Minhang Branch, Shanghai 200240, China,Correspondence Ming Xiang, E-mail: , Qing Zhai, E-mail: , Wei Wang, E-mail:
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7
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Bolaños P, Calderón JC. Excitation-contraction coupling in mammalian skeletal muscle: Blending old and last-decade research. Front Physiol 2022; 13:989796. [PMID: 36117698 PMCID: PMC9478590 DOI: 10.3389/fphys.2022.989796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 08/08/2022] [Indexed: 11/13/2022] Open
Abstract
The excitation–contraction coupling (ECC) in skeletal muscle refers to the Ca2+-mediated link between the membrane excitation and the mechanical contraction. The initiation and propagation of an action potential through the membranous system of the sarcolemma and the tubular network lead to the activation of the Ca2+-release units (CRU): tightly coupled dihydropyridine and ryanodine (RyR) receptors. The RyR gating allows a rapid, massive, and highly regulated release of Ca2+ from the sarcoplasmic reticulum (SR). The release from triadic places generates a sarcomeric gradient of Ca2+ concentrations ([Ca2+]) depending on the distance of a subcellular region from the CRU. Upon release, the diffusing Ca2+ has multiple fates: binds to troponin C thus activating the contractile machinery, binds to classical sarcoplasmic Ca2+ buffers such as parvalbumin, adenosine triphosphate and, experimentally, fluorescent dyes, enters the mitochondria and the SR, or is recycled through the Na+/Ca2+ exchanger and store-operated Ca2+ entry (SOCE) mechanisms. To commemorate the 7th decade after being coined, we comprehensively and critically reviewed “old”, historical landmarks and well-established concepts, and blended them with recent advances to have a complete, quantitative-focused landscape of the ECC. We discuss the: 1) elucidation of the CRU structures at near-atomic resolution and its implications for functional coupling; 2) reliable quantification of peak sarcoplasmic [Ca2+] using fast, low affinity Ca2+ dyes and the relative contributions of the Ca2+-binding mechanisms to the whole concert of Ca2+ fluxes inside the fibre; 3) articulation of this novel quantitative information with the unveiled structural details of the molecular machinery involved in mitochondrial Ca2+ handing to understand how and how much Ca2+ enters the mitochondria; 4) presence of the SOCE machinery and its different modes of activation, which awaits understanding of its magnitude and relevance in situ; 5) pharmacology of the ECC, and 6) emerging topics such as the use and potential applications of super-resolution and induced pluripotent stem cells (iPSC) in ECC. Blending the old with the new works better!
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Affiliation(s)
- Pura Bolaños
- Laboratory of Cellular Physiology, Centre of Biophysics and Biochemistry, Venezuelan Institute for Scientific Research (IVIC), Caracas, Venezuela
| | - Juan C. Calderón
- Physiology and Biochemistry Research Group-PHYSIS, Faculty of Medicine, University of Antioquia, Medellín, Colombia
- *Correspondence: Juan C. Calderón,
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8
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Ballarini E, Malacrida A, Rodriguez-Menendez V, Pozzi E, Canta A, Chiorazzi A, Monza L, Semperboni S, Meregalli C, Carozzi VA, Hashemi M, Nicolini G, Scuteri A, Housley SN, Cavaletti G, Alberti P. Sodium-Calcium Exchanger 2: A Pivotal Role in Oxaliplatin Induced Peripheral Neurotoxicity and Axonal Damage? Int J Mol Sci 2022; 23:10063. [PMID: 36077454 PMCID: PMC9456447 DOI: 10.3390/ijms231710063] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 08/26/2022] [Accepted: 08/29/2022] [Indexed: 12/14/2022] Open
Abstract
Oxaliplatin (OHP)-induced peripheral neurotoxicity (OIPN) is a frequent adverse event of colorectal cancer treatment. OIPN encompasses a chronic and an acute syndrome. The latter consists of transient axonal hyperexcitability, due to unbalance in Na+ voltage-operated channels (Na+VOC). This leads to sustained depolarisation which can activate the reverse mode of the Na+/Ca2+ exchanger 2 (NCX2), resulting in toxic Ca2+ accumulation and axonal damage (ADa). We explored the role of NCX2 in in vitro and in vivo settings. Embryonic rat Dorsal Root Ganglia (DRG) organotypic cultures treated with SEA0400 (SEA), a NCX inhibitor, were used to assess neuroprotection in a proof-of-concept and pilot study to exploit NCX modulation to prevent ADa. In vivo, OHP treated mice (7 mg/Kg, i.v., once a week for 8 weeks) were compared with a vehicle-treated group (n = 12 each). Neurophysiological and behavioural testing were performed to characterise acute and chronic OIPN, and morphological analyses were performed to detect ADa. Immunohistochemistry, immunofluorescence, and western blotting (WB) analyses were also performed to demonstrate changes in NCX2 immunoreactivity and protein expression. In vitro, NCX inhibition was matched by ADa mitigation. In the in vivo part, after verifyingboth acute and chronic OIPN had ensued, we confirmed via immunohistochemistry, immunofluorescence, and WB that a significant NCX2 alteration had ensued in the OHP group. Our data suggest NCX2 involvement in ADa development, paving the way to a new line of research to prevent OIPN.
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Affiliation(s)
- Elisa Ballarini
- School of Medicine and Surgery, University of Milano-Bicocca, 20126 Milan, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Alessio Malacrida
- School of Medicine and Surgery, University of Milano-Bicocca, 20126 Milan, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Virginia Rodriguez-Menendez
- School of Medicine and Surgery, University of Milano-Bicocca, 20126 Milan, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Eleonora Pozzi
- School of Medicine and Surgery, University of Milano-Bicocca, 20126 Milan, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Annalisa Canta
- School of Medicine and Surgery, University of Milano-Bicocca, 20126 Milan, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Alessia Chiorazzi
- School of Medicine and Surgery, University of Milano-Bicocca, 20126 Milan, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Laura Monza
- School of Medicine and Surgery, University of Milano-Bicocca, 20126 Milan, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Sara Semperboni
- School of Medicine and Surgery, University of Milano-Bicocca, 20126 Milan, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Cristina Meregalli
- School of Medicine and Surgery, University of Milano-Bicocca, 20126 Milan, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Valentina Alda Carozzi
- School of Medicine and Surgery, University of Milano-Bicocca, 20126 Milan, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Maryamsadat Hashemi
- School of Medicine and Surgery, University of Milano-Bicocca, 20126 Milan, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Gabriella Nicolini
- School of Medicine and Surgery, University of Milano-Bicocca, 20126 Milan, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Arianna Scuteri
- School of Medicine and Surgery, University of Milano-Bicocca, 20126 Milan, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Stephen N. Housley
- Integrated Cancer Research Center, School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Guido Cavaletti
- School of Medicine and Surgery, University of Milano-Bicocca, 20126 Milan, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
| | - Paola Alberti
- School of Medicine and Surgery, University of Milano-Bicocca, 20126 Milan, Italy
- NeuroMI (Milan Center for Neuroscience), 20126 Milan, Italy
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Voltage-gated sodium channel Na v1.5 promotes tumor progression and enhances chemosensitivity to 5-fluorouracil in colorectal cancer. Cancer Lett 2020; 500:119-131. [PMID: 33338532 DOI: 10.1016/j.canlet.2020.12.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 11/30/2020] [Accepted: 12/09/2020] [Indexed: 12/24/2022]
Abstract
Nav1.5, encoded by SCN5A, has been associated with metastasis in colorectal cancer (CRC). Here, we investigated the mechanism by which Nav1.5 regulates tumor progression and whether Nav1.5 influences chemosensitivity to 5-fluorouracil (5-FU) in CRCs. CRC cases were evaluated for Nav1.5 expression. Elevated Nav1.5 expression was associated with poor prognosis in CRCs, whereas stage II/III patients with upregulated SCN5A expression could have better survival after receiving 5-FU-based adjuvant chemotherapy. In CRC cells, SCN5A knockdown reduced the proliferation, migration and invasion. According to RNA sequencing, SCN5A knockdown inhibited both the cell cycle and epithelial-mesenchymal transition. In addition, Nav1.5 stabilized the KRas-calmodulin complex to modulate Ras signaling, promoting Ca2+ influx through the Na+-Ca2+ exchanger and Ca2+ release-activated calcium channel. Meanwhile, SCN5A knockdown increased the 50% inhibitory concentration to 5-FU by upregulating 5-FU-stimulated apoptosis in CRCs. In conclusion, Nav1.5 could progress to proliferation and metastasis through Ca2+/calmodulin-dependent Ras signaling in CRC, and it could also enhance 5-FU-stimulated apoptosis. Clinically, patients with stage II/III CRCs with elevated SCN5A expression demonstrated poor prognosis, yet those patients could benefit more from 5-FU-based chemotherapy than patients with lower SCN5A expression.
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10
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Drug development in targeting ion channels for brain edema. Acta Pharmacol Sin 2020; 41:1272-1288. [PMID: 32855530 PMCID: PMC7609292 DOI: 10.1038/s41401-020-00503-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 08/02/2020] [Indexed: 12/18/2022] Open
Abstract
Cerebral edema is a pathological hallmark of various central nervous system (CNS) insults, including traumatic brain injury (TBI) and excitotoxic injury such as stroke. Due to the rigidity of the skull, edema-induced increase of intracranial fluid significantly complicates severe CNS injuries by raising intracranial pressure and compromising perfusion. Mortality due to cerebral edema is high. With mortality rates up to 80% in severe cases of stroke, it is the leading cause of death within the first week. Similarly, cerebral edema is devastating for patients of TBI, accounting for up to 50% mortality. Currently, the available treatments for cerebral edema include hypothermia, osmotherapy, and surgery. However, these treatments only address the symptoms and often elicit adverse side effects, potentially in part due to non-specificity. There is an urgent need to identify effective pharmacological treatments for cerebral edema. Currently, ion channels represent the third-largest target class for drug development, but their roles in cerebral edema remain ill-defined. The present review aims to provide an overview of the proposed roles of ion channels and transporters (including aquaporins, SUR1-TRPM4, chloride channels, glucose transporters, and proton-sensitive channels) in mediating cerebral edema in acute ischemic stroke and TBI. We also focus on the pharmacological inhibitors for each target and potential therapeutic strategies that may be further pursued for the treatment of cerebral edema.
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Najder K, Rugi M, Lebel M, Schröder J, Oster L, Schimmelpfennig S, Sargin S, Pethő Z, Bulk E, Schwab A. Role of the Intracellular Sodium Homeostasis in Chemotaxis of Activated Murine Neutrophils. Front Immunol 2020; 11:2124. [PMID: 33013896 PMCID: PMC7506047 DOI: 10.3389/fimmu.2020.02124] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 08/05/2020] [Indexed: 12/17/2022] Open
Abstract
The importance of the intracellular Ca2+ concentration ([Ca2+]i) in neutrophil function has been intensely studied. However, the role of the intracellular Na+ concentration ([Na+]i) which is closely linked to the intracellular Ca2+ regulation has been largely overlooked. The [Na+]i is regulated by Na+ transport proteins such as the Na+/Ca2+-exchanger (NCX1), Na+/K+-ATPase, and Na+-permeable, transient receptor potential melastatin 2 (TRPM2) channel. Stimulating with either N-formylmethionine-leucyl-phenylalanine (fMLF) or complement protein C5a causes distinct changes of the [Na+]i. fMLF induces a sustained increase of [Na+]i, surprisingly, reaching higher values in TRPM2-/- neutrophils. This outcome is unexpected and remains unexplained. In both genotypes, C5a elicits only a transient rise of the [Na+]i. The difference in [Na+]i measured at t = 10 min after stimulation is inversely related to neutrophil chemotaxis. Neutrophil chemotaxis is more efficient in C5a than in an fMLF gradient. Moreover, lowering the extracellular Na+ concentration from 140 to 72 mM improves chemotaxis of WT but not of TRPM2-/- neutrophils. Increasing the [Na+]i by inhibiting the Na+/K+-ATPase results in disrupted chemotaxis. This is most likely due to the impact of the altered Na+ homeostasis and presumably NCX1 function whose expression was shown by means of qPCR and which critically relies on proper extra- to intracellular Na+ concentration gradients. Increasing the [Na+]i by a few mmol/l may suffice to switch its transport mode from forward (Ca2+-efflux) to reverse (Ca2+-influx) mode. The role of NCX1 in neutrophil chemotaxis is corroborated by its blocker, which also causes a complete inhibition of chemotaxis.
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Affiliation(s)
- Karolina Najder
- Institute of Physiology II, University Hospital Münster, Münster, Germany
| | - Micol Rugi
- Institute of Physiology II, University Hospital Münster, Münster, Germany
- University of Florence, Florence, Italy
| | - Mégane Lebel
- University of Sherbrooke, Sherbrooke, QC, Canada
| | - Julia Schröder
- Institute of Physiology II, University Hospital Münster, Münster, Germany
| | - Leonie Oster
- Institute of Physiology II, University Hospital Münster, Münster, Germany
| | | | - Sarah Sargin
- Institute of Physiology II, University Hospital Münster, Münster, Germany
| | - Zoltán Pethő
- Institute of Physiology II, University Hospital Münster, Münster, Germany
| | - Etmar Bulk
- Institute of Physiology II, University Hospital Münster, Münster, Germany
| | - Albrecht Schwab
- Institute of Physiology II, University Hospital Münster, Münster, Germany
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Gerkau NJ, Rakers C, Durry S, Petzold GC, Rose CR. Reverse NCX Attenuates Cellular Sodium Loading in Metabolically Compromised Cortex. Cereb Cortex 2019; 28:4264-4280. [PMID: 29136153 DOI: 10.1093/cercor/bhx280] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 10/04/2017] [Indexed: 01/05/2023] Open
Abstract
In core regions of ischemic stroke, disruption of blood flow causes breakdown of ionic gradients and, ultimately, calcium overload and cell death. In the surrounding penumbra, cells may recover upon reperfusion, but recovery is hampered by additional metabolic demands imposed by peri-infarct depolarizations (PIDs). There is evidence that sodium influx drives PIDs, but no data exist on PID-related sodium accumulations in vivo. Here, we found that PIDs in mouse neocortex are associated with propagating sodium elevations in neurons and astrocytes. Similar transient sodium elevations were induced in acute tissue slices by brief chemical ischemia. Blocking NMDA-receptors dampened sodium and accompanying calcium loads of neurons in tissue slices, while inhibiting glutamate transport diminished sodium influx into astrocytes, but amplified neuronal sodium loads. In both cell types, inhibition of sodium/calcium exchange (NCX) increased sodium transients. Blocking NCX also significantly reduced calcium transients, a result confirmed in vivo. Our study provides the first quantitative data on sodium elevations in peri-infarct regions in vivo. They suggest that sodium influx drives reversal of NCX, triggering a massive secondary calcium elevation while promoting export of sodium. Reported neuroprotective effects of NCX activity in stroke models might thus be related to its dampening of ischemia-induced sodium loading.
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Affiliation(s)
- Niklas J Gerkau
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Duesseldorf, Universitaetsstrasse 1, Duesseldorf, Germany
| | - Cordula Rakers
- German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, Bonn, Germany
| | - Simone Durry
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Duesseldorf, Universitaetsstrasse 1, Duesseldorf, Germany
| | - Gabor C Petzold
- German Center for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Str. 27, Bonn, Germany.,Department of Neurology, University Hospital Bonn, Sigmund-Freud-Str. 25, Bonn, Germany
| | - Christine R Rose
- Institute of Neurobiology, Faculty of Mathematics and Natural Sciences, Heinrich Heine University Duesseldorf, Universitaetsstrasse 1, Duesseldorf, Germany
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13
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Cantero-Recasens G, Butnaru CM, Brouwers N, Mitrovic S, Valverde MA, Malhotra V. Sodium channel TRPM4 and sodium/calcium exchangers (NCX) cooperate in the control of Ca 2+-induced mucin secretion from goblet cells. J Biol Chem 2018; 294:816-826. [PMID: 30482841 DOI: 10.1074/jbc.ra117.000848] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 11/21/2018] [Indexed: 01/08/2023] Open
Abstract
Regulated mucin secretion is essential for the formation of the mucus layer that protects the underlying epithelial cells from foreign particles. Alterations in the quantity or quality of secreted mucins are therefore detrimental to airway and colon physiology. Based on various biochemical assays in several human cell lines, we report here that Na+/Ca2+ exchanger 2 (NCX2) works in conjunction with transient receptor potential cation channel subfamily M member 4 (TRPM4), and perhaps TRPM5, Na+ channels to control Ca2+-mediated secretion of both mucin 2 (MUC2) and MUC5AC from HT29-18N2 colonic cancer cells. Differentiated normal bronchial epithelial (NHBE) cells and tracheal cells from patients with cystic fibrosis (CFT1-LC3) expressed only TRPM4 and all three isoforms of NCXs. Blocking the activity of TRPM4 or NCX proteins abrogated MUC5AC secretion from NHBE and CFT1-LC3 cells. Altogether, our findings reveal that NCX and TRPM4/TRPM5 are both required for mucin secretion. We therefore propose that these two proteins could be potential pharmacological targets to control mucus-related pathologies such as cystic fibrosis.
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Affiliation(s)
- Gerard Cantero-Recasens
- From the Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain
| | - Cristian M Butnaru
- From the Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain
| | - Nathalie Brouwers
- From the Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain
| | - Sandra Mitrovic
- the University Hospital of Basel, Clinical Chemistry, Petersgraben 4, 4031 Basel, Switzerland
| | - Miguel A Valverde
- the Laboratory of Molecular Physiology, Faculty of Health and Life Sciences, Universitat Pompeu Fabra, 08003 Barcelona, Catalonia, Spain, and
| | - Vivek Malhotra
- From the Centre for Genomic Regulation (CRG), The Barcelona Institute for Science and Technology, Dr. Aiguader 88, 08003 Barcelona, Spain, .,the Universitat Pompeu Fabra (UPF), Barcelona, Spain.,the Institució Catalana de Recerca i Estudis Avançats (ICREA), Pg. Lluis Companys 23, 08010 Barcelona, Spain
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14
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Major contribution of the 3/6/7 class of TRPC channels to myocardial ischemia/reperfusion and cellular hypoxia/reoxygenation injuries. Proc Natl Acad Sci U S A 2017; 114:E4582-E4591. [PMID: 28526717 DOI: 10.1073/pnas.1621384114] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The injury phase after myocardial infarcts occurs during reperfusion and is a consequence of calcium release from internal stores combined with calcium entry, leading to cell death by apoptopic and necrotic processes. The mechanism(s) by which calcium enters cells has(ve) not been identified. Here, we identify canonical transient receptor potential channels (TRPC) 3 and 6 as the cation channels through which most of the damaging calcium enters cells to trigger their death, and we describe mechanisms activated during the injury phase. Working in vitro with H9c2 cardiomyoblasts subjected to 9-h hypoxia followed by 6-h reoxygenation (H/R), and analyzing changes occurring in areas-at-risk (AARs) of murine hearts subjected to a 30-min ischemia followed by 24-h reperfusion (I/R) protocol, we found: (i) that blocking TRPC with SKF96365 significantly ameliorated damage induced by H/R, including development of the mitochondrial permeability transition and proapoptotic changes in Bcl2/BAX ratios; and (ii) that AAR tissues had increased TUNEL+ cells, augmented Bcl2/BAX ratios, and increased p(S240)NFATc3, p(S473)AKT, p(S9)GSK3β, and TRPC3 and -6 proteins, consistent with activation of a positive-feedback loop in which calcium entering through TRPCs activates calcineurin-mediated NFATc3-directed transcription of TRPC genes, leading to more Ca2+ entry. All these changes were markedly reduced in mice lacking TRPC3, -6, and -7. The changes caused by I/R in AAR tissues were matched by those seen after H/R in cardiomyoblasts in all aspects except for p-AKT and p-GSK3β, which were decreased after H/R in cardiomyoblasts instead of increased. TRPC should be promising targets for pharmacologic intervention after cardiac infarcts.
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15
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Hernandez-Ojeda M, Ureña-Guerrero ME, Gutierrez-Barajas PE, Cardenas-Castillo JA, Camins A, Beas-Zarate C. KB-R7943 reduces 4-aminopyridine-induced epileptiform activity in adult rats after neuronal damage induced by neonatal monosodium glutamate treatment. J Biomed Sci 2017; 24:27. [PMID: 28486943 PMCID: PMC5423021 DOI: 10.1186/s12929-017-0335-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 05/03/2017] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Neonatal monosodium glutamate (MSG) treatment triggers excitotoxicity and induces a degenerative process that affects several brain regions in a way that could lead to epileptogenesis. Na+/Ca2+ exchangers (NCX1-3) are implicated in Ca2+ brain homeostasis; normally, they extrude Ca2+ to control cell inflammation, but after damage and in epilepsy, they introduce Ca2+ by acting in the reverse mode, amplifying the damage. Changes in NCX3 expression in the hippocampus have been reported immediately after neonatal MSG treatment. In this study, the expression level of NCX1-3 in the entorhinal cortex (EC) and hippocampus (Hp); and the effects of blockade of NCXs on the seizures induced by 4-Aminopyridine (4-AP) were analysed in adult rats after neonatal MSG treatment. KB-R7943 was applied as NCXs blocker, but is more selective to NCX3 in reverse mode. METHODS Neonatal MSG treatment was applied to newborn male rats at postnatal days (PD) 1, 3, 5, and 7 (4 g/kg of body weight, s.c.). Western blot analysis was performed on total protein extracts from the EC and Hp to estimate the expression level of NCX1-3 proteins in relative way to the expression of β-actin, as constitutive protein. Electrographic activity of the EC and Hp were acquired before and after intracerebroventricular (i.c.v.) infusion of 4-AP (3 nmol) and KB-R7943 (62.5 pmol), alone or in combination. All experiments were performed at PD60. Behavioural alterations were also recorder. RESULTS Neonatal MSG treatment significantly increased the expression of NCX3 protein in both studied regions, and NCX1 protein only in the EC. The 4-AP-induced epileptiform activity was significantly higher in MSG-treated rats than in controls, and KB-R7943 co-administered with 4-AP reduced the epileptiform activity in more prominent way in MSG-treated rats than in controls. CONCLUSIONS The long-term effects of neonatal MSG treatment include increases on functional expression of NCXs (mainly of NCX3) in the EC and Hp, which seems to contribute to improve the control that KB-R7943 exerted on the seizures induced by 4-AP in adulthood. The results obtained here suggest that the blockade of NCXs could improve seizure control after an excitotoxic process; however, this must be better studied.
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Affiliation(s)
- Mariana Hernandez-Ojeda
- Laboratorio de Biología de la Neurotransmisión, Edificio de Posgrado, Departamento de Biología Celular y Molecular, CUCBA, Universidad de Guadalajara, Km 15.5 Carretera a Nogales, Camino Ing. Ramón Padilla Sánchez Km 2, Zapopan, Jalisco Mexico 45221
| | - Monica E. Ureña-Guerrero
- Laboratorio de Biología de la Neurotransmisión, Edificio de Posgrado, Departamento de Biología Celular y Molecular, CUCBA, Universidad de Guadalajara, Km 15.5 Carretera a Nogales, Camino Ing. Ramón Padilla Sánchez Km 2, Zapopan, Jalisco Mexico 45221
| | - Paola E. Gutierrez-Barajas
- Laboratorio de Biología de la Neurotransmisión, Edificio de Posgrado, Departamento de Biología Celular y Molecular, CUCBA, Universidad de Guadalajara, Km 15.5 Carretera a Nogales, Camino Ing. Ramón Padilla Sánchez Km 2, Zapopan, Jalisco Mexico 45221
| | - Jazmin A. Cardenas-Castillo
- Laboratorio de Biología de la Neurotransmisión, Edificio de Posgrado, Departamento de Biología Celular y Molecular, CUCBA, Universidad de Guadalajara, Km 15.5 Carretera a Nogales, Camino Ing. Ramón Padilla Sánchez Km 2, Zapopan, Jalisco Mexico 45221
| | - Antoni Camins
- Unitat de Farmacologia i Farmacognòsia, Institut de Neurociencias, Facultat de Farmàcia, Universitat de Barcelona, Barcelona, Spain
- Biomedical Research Networking Center in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Carlos Beas-Zarate
- Laboratorio de Biología de la Neurotransmisión, Edificio de Posgrado, Departamento de Biología Celular y Molecular, CUCBA, Universidad de Guadalajara, Km 15.5 Carretera a Nogales, Camino Ing. Ramón Padilla Sánchez Km 2, Zapopan, Jalisco Mexico 45221
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16
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Averin AS, Kosarsky LS, Tarlachkov SV, Vekhnik VA, Averina IV, Alekseev AE, Fesenko EE, Nakipova OV. The effects of KB-R7943, an inhibitor of reverse Na+/Ca2+ exchange, on the force of contraction of papillary muscles in the heart of the ground squirrel Spermophilus undulatus. Biophysics (Nagoya-shi) 2017. [DOI: 10.1134/s000635091701002x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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17
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Lu B, Fivaz M. Neuronal SOCE: Myth or Reality? Trends Cell Biol 2016; 26:890-893. [DOI: 10.1016/j.tcb.2016.09.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 09/09/2016] [Accepted: 09/13/2016] [Indexed: 11/15/2022]
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18
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Gruszczynska-Biegala J, Sladowska M, Kuznicki J. AMPA Receptors Are Involved in Store-Operated Calcium Entry and Interact with STIM Proteins in Rat Primary Cortical Neurons. Front Cell Neurosci 2016; 10:251. [PMID: 27826230 PMCID: PMC5078690 DOI: 10.3389/fncel.2016.00251] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 10/13/2016] [Indexed: 11/13/2022] Open
Abstract
The process of store-operated calcium entry (SOCE) leads to refilling the endoplasmic reticulum (ER) with calcium ions (Ca2+) after their release into the cytoplasm. Interactions between (ER)-located Ca2+ sensors (stromal interaction molecule 1 [STIM1] and STIM2) and plasma membrane-located Ca2+ channel-forming protein (Orai1) underlie SOCE and are well described in non-excitable cells. In neurons, however, SOCE appears to be more complex because of the importance of Ca2+ influx via voltage-gated or ionotropic receptor-operated Ca2+ channels. We found that the SOCE inhibitors ML-9 and SKF96365 reduced α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-induced [Ca2+]i amplitude by 80% and 53%, respectively. To assess the possible involvement of AMPA receptors (AMPARs) in SOCE, we used their specific inhibitors. As estimated by Fura-2 acetoxymethyl (AM) single-cell Ca2+ measurements in the presence of CNQX or NBQX, thapsigargin (TG)-induced Ca2+ influx decreased 2.2 or 3.7 times, respectively. These results suggest that under experimental conditions of SOCE when Ca2+ stores are depleted, Ca2+ can enter neurons also through AMPARs. Using specific antibodies against STIM proteins or GluA1/GluA2 AMPAR subunits, co-immunoprecipitation assays indicated that when Ca2+ levels are low in the neuronal ER, a physical association occurs between endogenous STIM proteins and endogenous AMPAR receptors. Altogether, our data suggest that STIM proteins in neurons can control AMPA-induced Ca2+ entry as a part of the mechanism of SOCE.
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Affiliation(s)
- Joanna Gruszczynska-Biegala
- Laboratory of Neurodegeneration, International Institute of Molecular and Cell Biology in Warsaw Warsaw, Poland
| | - Maria Sladowska
- Laboratory of Neurodegeneration, International Institute of Molecular and Cell Biology in Warsaw Warsaw, Poland
| | - Jacek Kuznicki
- Laboratory of Neurodegeneration, International Institute of Molecular and Cell Biology in Warsaw Warsaw, Poland
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19
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Younan S, Sakita GZ, Albuquerque TR, Keller R, Bremer-Neto H. Chromium(VI) bioremediation by probiotics. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2016; 96:3977-3982. [PMID: 26997541 DOI: 10.1002/jsfa.7725] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 02/04/2016] [Accepted: 03/13/2016] [Indexed: 06/05/2023]
Abstract
Chromium is a common mineral in the earth's crust and can be released into the environment from anthropogenic sources. Intake of hexavalent chromium (Cr(VI)) through drinking water and food causes toxic effects, leading to serious diseases, and is a commonly reported environmental problem. Microorganisms can mitigate or prevent the toxic effects caused by heavy metals in addition to having effective resistance mechanisms to prevent cell damage and bind to these metals, sequestering them from the cell surface and removing them from the body. Species of Lactobacillus, Streptococcus, Bacillus and Bifidobacterium present in the human mouth and gut and in fermented foods have the ability to bind and detoxify some of these substances. This review address the primary topics related to Cr(VI) poisoning in animals and humans and the use of probiotics as a way to mitigate or prevent the toxic effects caused by Cr(VI). Further advances in the genetic knowledge of such microorganisms may lead to discoveries which will clarify the most active microorganisms that act as bioprotectants in bodies exposed to Cr(VI) and are an affordable option for people and animals intoxicated by the oral route. © 2016 Society of Chemical Industry.
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Affiliation(s)
- Soraia Younan
- Department of Functional Sciences, Laboratory of Biophysics, University of Western São Paulo - UNOESTE, CEP 19050-920, Presidente Prudente, São Paulo, Brazil
| | - Gabriel Z Sakita
- Department of Functional Sciences, Laboratory of Biophysics, University of Western São Paulo - UNOESTE, CEP 19050-920, Presidente Prudente, São Paulo, Brazil
| | - Talita R Albuquerque
- Department of Functional Sciences, Laboratory of Biophysics, University of Western São Paulo - UNOESTE, CEP 19050-920, Presidente Prudente, São Paulo, Brazil
| | - Rogéria Keller
- Department of Functional Sciences, Laboratory of Biophysics, University of Western São Paulo - UNOESTE, CEP 19050-920, Presidente Prudente, São Paulo, Brazil
| | - Hermann Bremer-Neto
- Department of Functional Sciences, Laboratory of Biophysics, University of Western São Paulo - UNOESTE, CEP 19050-920, Presidente Prudente, São Paulo, Brazil
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20
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Yap KAF, Shetty MS, Garcia-Alvarez G, Lu B, Alagappan D, Oh-Hora M, Sajikumar S, Fivaz M. STIM2 regulates AMPA receptor trafficking and plasticity at hippocampal synapses. Neurobiol Learn Mem 2016; 138:54-61. [PMID: 27544849 DOI: 10.1016/j.nlm.2016.08.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 08/14/2016] [Accepted: 08/16/2016] [Indexed: 10/21/2022]
Abstract
STIM2 is an integral membrane protein of the endoplasmic reticulum (ER) that regulates the activity of plasma membrane (PM) channels at ER-PM contact sites. Recent studies show that STIM2 promotes spine maturation and surface expression of the AMPA receptor (AMPAR) subunit GluA1, hinting at a probable role in synaptic plasticity. Here, we used a Stim2 cKO mouse to explore the function of STIM2 in Long-Term Potentiation (LTP) and Depression (LTD), two widely-studied models of synaptic plasticity implicated in information storage. We found that STIM2 is required for the stable expression of both LTP and LTD at CA3-CA1 hippocampal synapses. Altered plasticity in Stim2 cKO mice is associated with subtle alterations in the shape and density of dendritic spines in CA1 neurons. Further, surface delivery of GluA1 in response to LTP-inducing chemical manipulations was markedly reduced in excitatory neurons derived from Stim2 cKO mice. GluA1 endocytosis following chemically-induced LTD was also impaired in Stim2 cKO neurons. We conclude that STIM2 facilitates synaptic delivery and removal of AMPARs and regulates activity-dependent changes in synaptic strength through a unique mode of communication between the ER and the synapse.
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Affiliation(s)
- Kenrick An Fu Yap
- Duke-NUS Medical School, programme in Neuroscience and Behavioral Disorders, Singapore 169857, Singapore
| | - Mahesh Shivarama Shetty
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Gisela Garcia-Alvarez
- Duke-NUS Medical School, programme in Neuroscience and Behavioral Disorders, Singapore 169857, Singapore
| | - Bo Lu
- Duke-NUS Medical School, programme in Neuroscience and Behavioral Disorders, Singapore 169857, Singapore
| | - Durgadevi Alagappan
- Duke-NUS Medical School, programme in Neuroscience and Behavioral Disorders, Singapore 169857, Singapore
| | - Masatsugu Oh-Hora
- Division of Molecular Immunology, Medical Institute of Bioregulation, Kyushu University, Japan
| | - Sreedharan Sajikumar
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
| | - Marc Fivaz
- Duke-NUS Medical School, programme in Neuroscience and Behavioral Disorders, Singapore 169857, Singapore; Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
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21
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Sibarov DA, Abushik PA, Poguzhelskaya EE, Bolshakov KV, Antonov SM. Inhibition of Plasma Membrane Na/Ca-Exchanger by KB-R7943 or Lithium Reveals Its Role in Ca-Dependent N-methyl-d-aspartate Receptor Inactivation. J Pharmacol Exp Ther 2015; 355:484-95. [PMID: 26391160 DOI: 10.1124/jpet.115.227173] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 09/18/2015] [Indexed: 01/09/2023] Open
Abstract
To evaluate the possible role of the plasma membrane Na(+)/Ca(2+)-exchanger (NCX) in regulation of N-methyl-d-aspartate (NMDA) receptors (NMDARs), we studied effects of 2-[2-[4-(4-nitrobenzyloxy) phenyl]ethyl]isothiourea methanesulfonate (KB-R7943; KBR) and lithium (inhibitors of NCX) on NMDA-elicited whole-cell currents using the patch-clamp technique on rat cortical neurons and human embryonic kidney 293T cells expressing recombinant NMDARs. KBR inhibited NMDAR currents in a voltage-independent manner with similar potency for receptors of GluN1/2A and GluN1/2B subunit compositions that excludes open-channel block and GluN2B-selective inhibition. The inhibition by KBR depended on glycine (Gly) concentration. At 30 μM NMDA, the KBR IC50 values were 5.3 ± 0.1 and 41.2 ± 8.8 μM for 1 and 300 μM Gly, respectively. Simultaneous application of NMDA + KBR in the absence of Gly induced robust inward NMDAR currents that peaked and then rapidly decreased. KBR, therefore, is an agonist (EC50 is 1.18 ± 0.16 µM) of the GluN1 subunit coagonist binding sites. The decrease of NMDA-elicited currents in the presence of KBR was abolished in Ca(2+)-free solution and was not observed in the presence of extracellular Ca(2+) on 1,2-Bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-loaded neurons, suggesting that Ca(2+) affects NMDARs from the cytosol. In agreement, the substitution of Li(+) for extracellular Na(+) caused a considerable decrease of NMDAR currents, which was not observed in the absence of extracellular Ca(2+). Most likely, the accumulation of intracellular Ca(2+) is caused by the inhibition of Ca(2+) extrusion via NCX. Thus, KBR and Li(+) provoke Ca(2+)-dependent receptor inactivation due to the disruption of Ca(2+) extrusion by the NCX. The data reveal the role of NCX in regulation of Ca(2+)-dependent inactivation of NMDARs.
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Affiliation(s)
- Dmitry A Sibarov
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, St. Petersburg, Russia
| | - Polina A Abushik
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, St. Petersburg, Russia
| | - Ekaterina E Poguzhelskaya
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, St. Petersburg, Russia
| | - Konstantin V Bolshakov
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, St. Petersburg, Russia
| | - Sergei M Antonov
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, St. Petersburg, Russia
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Raiteri L, Raiteri M. Multiple functions of neuronal plasma membrane neurotransmitter transporters. Prog Neurobiol 2015; 134:1-16. [PMID: 26300320 DOI: 10.1016/j.pneurobio.2015.08.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 07/09/2015] [Accepted: 08/18/2015] [Indexed: 12/11/2022]
Abstract
Removal from receptors of neurotransmitters just released into synapses is one of the major steps in neurotransmission. Transporters situated on the plasma membrane of nerve endings and glial cells perform the process of neurotransmitter (re)uptake. Because the density of transporters in the membranes can fluctuate, transporters can determine the transmitter concentrations at receptors, thus modulating indirectly the excitability of neighboring neurons. Evidence is accumulating that neurotransmitter transporters can exhibit multiple functions. Being bidirectional, neurotransmitter transporters can mediate transmitter release by working in reverse, most often under pathological conditions that cause ionic gradient dysregulations. Some transporters reverse to release transmitters, like dopamine or serotonin, when activated by 'indirectly acting' substrates, like the amphetamines. Some transporters exhibit as one major function the ability to capture transmitters into nerve terminals that perform insufficient synthesis. Transporter activation can generate conductances that regulate directly neuronal excitability. Synaptic and non-synaptic transporters play different roles. Cytosolic Na(+) elevations accompanying transport can interact with plasmalemmal or/and mitochondrial Na(+)/Ca(2+) exchangers thus generating calcium signals. Finally, neurotransmitter transporters can behave as receptors mediating releasing stimuli able to cause transmitter efflux through multiple mechanisms. Neurotransmitter transporters are therefore likely to play hitherto unknown roles in multiple therapeutic treatments.
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Affiliation(s)
- Luca Raiteri
- Department of Pharmacy, Pharmacology and Toxicology Section, University of Genoa, Genoa, Italy; Center of Excellence for Biomedical Research, University of Genoa, Genoa, Italy; National Institute of Neuroscience, Genoa, Italy
| | - Maurizio Raiteri
- Department of Pharmacy, Pharmacology and Toxicology Section, University of Genoa, Genoa, Italy; Center of Excellence for Biomedical Research, University of Genoa, Genoa, Italy; National Institute of Neuroscience, Genoa, Italy.
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Effects of renal Na+/Ca2+ exchanger 1 inhibitor (SEA0400) treatment on electrolytes, renal function and hemodynamics in rats. Clin Exp Nephrol 2014; 19:585-90. [PMID: 25410661 DOI: 10.1007/s10157-014-1053-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 11/01/2014] [Indexed: 01/30/2023]
Abstract
BACKGROUND Na(+)/Ca(2+) exchanger 1 (NCX1) controls intracellular Ca(2+) concentration in various cell types. In the kidney, NCX1 is expressed mainly in the distal tubular basolateral membrane as well as in vascular smooth muscle. Tubular NCX1 is involved in Ca(2+) reabsorption, and NCX1 in renal arterioles may control intraglomerular pressure. However, the functions of renal NCX1 have not been studied in vivo. Therefore, this study examined the effects of renal NCX1 blockade on water and solute metabolism, renal function and blood pressure in rats. METHODS Wistar-Kyoto rats were uninephrectomized, and an osmotic mini pump was implanted to infuse the remnant kidney cortex with a specific NCX1 inhibitor, SEA0400 (SEA), or vehicle for 7 days. RESULTS Serum Ca(2+) concentration and urinary Ca(2+) excretion were similar between the vehicle- and SEA-treated groups. However, serum phosphate was significantly decreased by 8 % in the SEA group, with similar urinary phosphate excretion between the two groups. Systolic blood pressure was higher in the SEA group (117 ± 3 vs. 126 ± 1 mmHg, n = 9-11), with a 1.6-fold increase in plasma aldosterone concentration. However, SEA significantly reduced urinary protein excretion and the glomerular sectional area by 16 and 8 %, respectively. Similar experiment in spontaneously hypertensive rats produced different results. CONCLUSION Renal SEA treatment reduced serum phosphate concentration, urinary protein and glomerular size with higher systemic blood pressure compared to control Wistar-Kyoto rats. Further study on renal NCX1 may be beneficial in delineating the pathophysiology of glomerular pressure control and calcium/phosphate regulations.
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Calderón JC, Bolaños P, Caputo C. Tetanic Ca2+ transient differences between slow- and fast-twitch mouse skeletal muscle fibres: a comprehensive experimental approach. J Muscle Res Cell Motil 2014; 35:279-93. [DOI: 10.1007/s10974-014-9388-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 09/03/2014] [Indexed: 12/17/2022]
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25
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GABA release provoked by disturbed Na+, K+ and Ca2+ homeostasis in cerebellar nerve endings: Roles of Ca2+ channels, Na+/Ca2+ exchangers and GAT1 transporter reversal. Neurochem Int 2014; 72:1-9. [DOI: 10.1016/j.neuint.2014.04.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 03/25/2014] [Accepted: 04/03/2014] [Indexed: 11/15/2022]
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Wiczer BM, Marcu R, Hawkins BJ. KB-R7943, a plasma membrane Na(+)/Ca(2+) exchanger inhibitor, blocks opening of the mitochondrial permeability transition pore. Biochem Biophys Res Commun 2014; 444:44-9. [PMID: 24434143 DOI: 10.1016/j.bbrc.2014.01.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 01/07/2014] [Indexed: 01/13/2023]
Abstract
The isothiourea derivative, KB-R7943, inhibits the reverse-mode of the plasma membrane sodium/calcium exchanger and protects against ischemia/reperfusion injury. The mechanism through which KB-R7943 confers protection, however, remains controversial. Recently, KB-R7943 has been shown to inhibit mitochondrial calcium uptake and matrix overload, which may contribute to its protective effects. While using KB-R7943 for this purpose, we find here no evidence that KB-R7943 directly blocks mitochondrial calcium uptake. Rather, we find that KB-R7943 inhibits opening of the mitochondrial permeability transition pore in permeabilized cells and isolated liver mitochondria. Furthermore, we find that this observation correlates with protection against calcium ionophore-induced mitochondrial membrane potential depolarization and cell death, without detrimental effects to basal mitochondrial membrane potential or complex I-dependent mitochondrial respiration. Our data reveal another mechanism through which KB-R7943 may protect against calcium-induced injury, as well as a novel means to inhibit the mitochondrial permeability transition pore.
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Affiliation(s)
- Brian M Wiczer
- Department of Anesthesiology and Pain Medicine, Mitochondria and Metabolism Center, University of Washington, Seattle, WA, United States
| | - Raluca Marcu
- Department of Anesthesiology and Pain Medicine, Mitochondria and Metabolism Center, University of Washington, Seattle, WA, United States
| | - Brian J Hawkins
- Department of Anesthesiology and Pain Medicine, Mitochondria and Metabolism Center, University of Washington, Seattle, WA, United States.
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Milanese M, Romei C, Usai C, Oliveri M, Raiteri L. A new function for glycine GlyT2 transporters: Stimulation of γ-aminobutyric acid release from cerebellar nerve terminals through GAT1 transporter reversal and Ca2+-dependent anion channels. J Neurosci Res 2013; 92:398-408. [DOI: 10.1002/jnr.23321] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2013] [Accepted: 10/08/2013] [Indexed: 11/06/2022]
Affiliation(s)
- Marco Milanese
- Department of Pharmacy; Pharmacology and Toxicology Section, University of Genoa; Genoa Italy
- Center of Excellence for Biomedical Research; University of Genoa; Genoa Italy
| | - Cristina Romei
- Department of Pharmacy; Pharmacology and Toxicology Section, University of Genoa; Genoa Italy
| | - Cesare Usai
- Institute of Biophysics; National Research Council; Genoa Italy
| | - Martina Oliveri
- Department of Pharmacy; Pharmacology and Toxicology Section, University of Genoa; Genoa Italy
| | - Luca Raiteri
- Department of Pharmacy; Pharmacology and Toxicology Section, University of Genoa; Genoa Italy
- Center of Excellence for Biomedical Research; University of Genoa; Genoa Italy
- National Institute of Neuroscience; Genoa Italy
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Bolaños P, Guillen A, Gámez A, Caputo C. Quantifying SOCE fluorescence measurements in mammalian muscle fibres. The effects of ryanodine and osmotic shocks. J Muscle Res Cell Motil 2013; 34:379-93. [PMID: 24129906 DOI: 10.1007/s10974-013-9360-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Accepted: 09/18/2013] [Indexed: 11/28/2022]
Abstract
We have quantified Ca(2+) entry through store operated calcium channels in mice muscle fibres, measuring the rates of change of myoplasmic [Ca(2+)], d[Ca(2+)](myo)/dt, and of Ca(2+) removal, d[Ca(2+)](Removal)/dt, turning store operated calcium entry (SOCE) ON, and OFF, by switching on or off external Ca(2+). In depleted fibres, poisoned with 10 μM cyclopiazonic acid SOCE influx was about 3 μM/s. Ryanodine (50 μM) caused a robust, nifedipine (50 μM) independent, increase in SOCE activation to 8.6 μM/s. Decreasing medium osmolarity from 300 to 220 mOsm/L, decreased SOCE to 0.9 μM/s, while increasing osmolarity from 220 to 400 mOsm/L potentiated SOCE to 43.6 μM/s. Ryanodine inhibited the effects of hypotonicity. Experiments using 2-aminoethoxydiphenyl borate, nifedipine, or Mn(2+) quenching, strongly suggest that the increased [Ca(2+)](myo) by ryanodine or hypertonic shock is mediated by potentiated SOCE activation. The Ca(2+) response decay, quantified by d[Ca(2+)](Removal)/dt, indicates a robust residual Ca(2+) removal mechanism in sarco-endoplasmic reticulum calcium ATPase poisoned fibres. SOCE high sensitivity to osmotic shocks, or to ryanodine receptor (RyR) binding, suggests its high dependency on the structural relationship between its molecular constituents, Orai1 and stromal interaction molecule and the sarcoplasmic reticulum and plasma membranes, in the triadic junctional region, where RyRs, are conspicuously present. This study demonstrates that SOCE machinery is highly sensitive to structural changes caused by binding of an agonist to its receptor or by imposed osmotical volume changes.
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Affiliation(s)
- Pura Bolaños
- Laboratorio de Fisiología Celular, Centro de Biofísica y Bioquímica, Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Venezuela,
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Collins HE, Zhu-Mauldin X, Marchase RB, Chatham JC. STIM1/Orai1-mediated SOCE: current perspectives and potential roles in cardiac function and pathology. Am J Physiol Heart Circ Physiol 2013; 305:H446-58. [PMID: 23792674 PMCID: PMC3891250 DOI: 10.1152/ajpheart.00104.2013] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Store-operated Ca²⁺ entry (SOCE) is critical for Ca²⁺ signaling in nonexcitable cells; however, its role in the regulation of cardiomyocyte Ca²⁺ homeostasis has only recently been investigated. The increased understanding of the role of stromal interaction molecule 1 (STIM1) in regulating SOCE combined with recent studies demonstrating the presence of STIM1 in cardiomyocytes provides support that this pathway co-exists in the heart with the more widely recognized Ca²⁺ handling pathways associated with excitation-contraction coupling. There is now substantial evidence that STIM1-mediated SOCE plays a key role in mediating cardiomyocyte hypertrophy, both in vitro and in vivo, and there is growing support for the contribution of SOCE to Ca²⁺ overload associated with ischemia/reperfusion injury. Here, we provide an overview of our current understanding of the molecular regulation of SOCE and discuss the evidence supporting the role of STIM1/Orai1-mediated SOCE in regulating cardiomyocyte function.
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Affiliation(s)
- Helen E Collins
- Division of Molecular and Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama
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Abstract
The Na+/Ca2+ exchanger (NCX) is an important electrogenic transporter in maintaining Na+ and Ca2+ homeostasis in a variety of mammalian organs, and is involved in the physiological and pathophysiological regulation of Ca2+ concentration in the myocardium. It can affect cardial structure, electrophysiology and contractile properties. The role of the NCX in heart cells following ischemia/reperfusion (IR) has been investigated using a number of in vitro and in vivo models. During ischemia, ionic disturbances favor Ca2+-influx mode activity as excess Na+ is extruded in exchange for Ca2+, giving rise to increased intracellular Ca2+ levels (Cai). This rise in Cai contributes to reversible cellular dysfunction upon reperfusion, such as myocardial necrosis, arrhythmia, systolic dysfunction and heart failure. We have reviewed the major in vivo and in vitro cardiac IR-related NCX studies in an attempt to clarify the functions of NCX in IR and conclude that recent studies suggest blockage of NCX has potential therapeutic applications. Although the use of different IR models, application of NCX stimulators and inhibitors, and development of NCX transgenic animals do help elucidate the role of this ion exchanger in heart cells, related mechanisms are not completely understood and clinically effective specific NCX inhibitors need further research.
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Affiliation(s)
- Sai Chen
- Department of Physiology, Dalian Medical University, Dalian, Liaoning, China
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Cheng H, Zhang Y, Du C, Dempsey CE, Hancox JC. High potency inhibition of hERG potassium channels by the sodium-calcium exchange inhibitor KB-R7943. Br J Pharmacol 2012; 165:2260-73. [PMID: 21950687 DOI: 10.1111/j.1476-5381.2011.01688.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE KB-R7943 is an isothiourea derivative that is used widely as a pharmacological inhibitor of sodium-calcium exchange (NCX) in experiments on cardiac and other tissue types. This study investigated KB-R7943 inhibition of hERG (human ether-à-go-go-related gene) K(+) channels that underpin the cardiac rapid delayed rectifier potassium current, I(Kr) . EXPERIMENTAL APPROACH Whole-cell patch-clamp measurements were made of hERG current (I(hERG) ) carried by wild-type or mutant hERG channels and of native rabbit ventricular I(Kr) . Docking simulations utilized a hERG homology model built on a MthK-based template. KEY RESULTS KB-R7943 inhibited both I(hERG) and native I(Kr) rapidly on membrane depolarization with IC(50) values of ∼89 and ∼120 nM, respectively, for current tails at -40 mV following depolarizing voltage commands to +20 mV. Marked I(hERG) inhibition also occurred under ventricular action potential voltage clamp. I(hERG) inhibition by KB-R7943 exhibited both time- and voltage-dependence but showed no preference for inactivated over activated channels. Results of alanine mutagenesis and docking simulations indicate that KB-R7943 can bind to a pocket formed of the side chains of aromatic residues Y652 and F656, with the compound's nitrobenzyl group orientated towards the cytoplasmic side of the channel pore. The structurally related NCX inhibitor SN-6 also inhibited I(hERG) , but with a markedly reduced potency. CONCLUSIONS AND IMPLICATIONS KB-R7943 inhibits I(hERG) /I(Kr) with a potency that exceeds that reported previously for acute cardiac NCX inhibition. Our results also support the feasibility of benzyloxyphenyl-containing NCX inhibitors with reduced potential, in comparison with KB-R7943, to inhibit hERG.
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Abstract
It has been known for more than 60 years, and suspected for over 100, that alveolar hypoxia causes pulmonary vasoconstriction by means of mechanisms local to the lung. For the last 20 years, it has been clear that the essential sensor, transduction, and effector mechanisms responsible for hypoxic pulmonary vasoconstriction (HPV) reside in the pulmonary arterial smooth muscle cell. The main focus of this review is the cellular and molecular work performed to clarify these intrinsic mechanisms and to determine how they are facilitated and inhibited by the extrinsic influences of other cells. Because the interaction of intrinsic and extrinsic mechanisms is likely to shape expression of HPV in vivo, we relate results obtained in cells to HPV in more intact preparations, such as intact and isolated lungs and isolated pulmonary vessels. Finally, we evaluate evidence regarding the contribution of HPV to the physiological and pathophysiological processes involved in the transition from fetal to neonatal life, pulmonary gas exchange, high-altitude pulmonary edema, and pulmonary hypertension. Although understanding of HPV has advanced significantly, major areas of ignorance and uncertainty await resolution.
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Affiliation(s)
- J T Sylvester
- Division of Pulmonary & Critical Care Medicine, Department of Medicine, The Johns Hopkins University School ofMedicine, Baltimore, Maryland, USA.
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Romei C, Di Prisco S, Raiteri M, Raiteri L. Glycine release provoked by disturbed Na+, K+ and Ca2+ homeostasis in cerebellar nerve endings: roles of Ca2+ channels, Na+/Ca2+ exchangers and GlyT2 transporter reversal. J Neurochem 2011; 119:50-63. [DOI: 10.1111/j.1471-4159.2011.07401.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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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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Abstract
The Ca(2+)-dependent release of aspartate from hippocampal preparations was first reported 35 years ago, but the functional significance of this process remains uncertain. Aspartate satisfies all the criteria normally required for identification of a CNS transmitter. It is synthesized in nerve terminals, is accumulated and stored in synaptic vesicles, is released by exocytosis upon nerve terminal depolarization, and activates postsynaptic NMDA receptors. Aspartate may be employed as a neuropeptide-like co-transmitter by pathways that release either glutamate or GABA as their principal transmitter. Aspartate mechanisms include vesicular transport by sialin, vesicular content sensitive to glucose concentration, release mainly outside the presynaptic active zones, and selective activation of extrasynaptic NR1-NR2B NMDA receptors. Possible neurobiological functions of aspartate in immature neurons include activation of cAMP-dependent gene transcription and in mature neurons inhibition of CREB function, reduced BDNF expression, and induction of excitotoxic neuronal death. Recent findings suggest new experimental approaches toward resolving the functional significance of aspartate release.
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Affiliation(s)
- J Victor Nadler
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.
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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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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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Fekete A, Franklin L, Ikemoto T, Rózsa B, Lendvai B, Sylvester Vizi E, Zelles T. Mechanism of the persistent sodium current activator veratridine-evoked Ca elevation: implication for epilepsy. J Neurochem 2009; 111:745-56. [PMID: 19719824 DOI: 10.1111/j.1471-4159.2009.06368.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Although the role of Na(+) in several aspects of Ca(2+) regulation has already been shown, the exact mechanism of intracellular Ca(2+) concentration ([Ca(2+)](i)) increase resulting from an enhancement in the persistent, non-inactivating Na(+) current (I(Na,P)), a decisive factor in certain forms of epilepsy, has yet to be resolved. Persistent Na(+) current, evoked by veratridine, induced bursts of action potentials and sustained membrane depolarization with monophasic intracellular Na(+) concentration ([Na(+)](i)) and biphasic [Ca(2+)](i) increase in CA1 pyramidal cells in acute hippocampal slices. The Ca(2+) response was tetrodotoxin- and extracellular Ca(2+)-dependent and ionotropic glutamate receptor-independent. The first phase of [Ca(2+)](i) rise was the net result of Ca(2+) influx through voltage-gated Ca(2+) channels and mitochondrial Ca(2+) sequestration. The robust second phase in addition involved reverse operation of the Na(+)-Ca(2+) exchanger and mitochondrial Ca(2+) release. We excluded contribution of the endoplasmic reticulum. These results demonstrate a complex interaction between persistent, non-inactivating Na(+) current and [Ca(2+)](i) regulation in CA1 pyramidal cells. The described cellular mechanisms are most likely part of the pathomechanism of certain forms of epilepsy that are associated with I(Na,P). Describing the magnitude, temporal pattern and sources of Ca(2+) increase induced by I(Na,P) may provide novel targets for antiepileptic drug therapy.
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Affiliation(s)
- Adám Fekete
- Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Szigony, Hungary
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Postsynaptic response to stimulation of the Schaffer collaterals with properties similar to those of synaptosomal aspartate release. Brain Res 2009; 1295:13-20. [PMID: 19664606 DOI: 10.1016/j.brainres.2009.07.104] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 07/17/2009] [Accepted: 07/30/2009] [Indexed: 11/23/2022]
Abstract
Aspartate satisfies all the criteria normally required for identification of a CNS neurotransmitter. Nevertheless, little electrophysiological evidence supports the existence of aspartate transmission. In studies with rat hippocampal synaptosomes, chemically evoked aspartate release differed from glutamate release in its relative sensitivity to increased Ca(2+) concentration outside the presynaptic active zones, inefficient coupling to P/Q-type Ca(2+) channels, sensitivity to KB-R7943, and resistance to native Clostridial toxins. We took advantage of these differences to search for a potential aspartate-mediated response at Schaffer collateral synapses in organotypic hippocampal slice cultures. The slice cultures were pretreated with botulinum neurotoxin C (BoNT/C) to eliminate most of the glutamate release so that an expectedly smaller aspartate-like component of the compound EPSC could be detected by whole cell patch clamp recording. In control cultures, NMDA receptor activation accounted for only 18% of the evoked EPSC and an NR2B-selective antagonist reduced the NMDA receptor-mediated component by only 20%. Block of P/Q-type Ca(2+) channels essentially eliminated the response and 0.1 muM KB-R7943 had no significant effect. In BoNT/C-pretreated cultures, however, NMDA receptor activation accounted for 77% of the evoked EPSC and an NR2B-selective antagonist reduced the NMDA receptor-mediated component by 57%. Block of P/Q-type Ca(2+) channels reduced the response by only 28%, but 0.1 muM KB-R7943 reduced it by 45%. These results suggest that part of the Schaffer collateral synaptic response has pharmacological properties similar to those of synaptosomal aspartate release and may therefore be mediated at least partly by released aspartate.
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Secondo A, Pannaccione A, Molinaro P, Ambrosino P, Lippiello P, Esposito A, Cantile M, Khatri PR, Melisi D, Di Renzo G, Annunziato L. Molecular Pharmacology of the Amiloride Analog 3-Amino-6-chloro-5-[(4-chloro-benzyl)amino]-N-[[(2,4-dimethylbenzyl)-amino]iminomethyl]-pyrazinecarboxamide (CB-DMB) as a Pan Inhibitor of the Na+-Ca2+ Exchanger Isoforms NCX1, NCX2, and NCX3 in Stably Transfected Cells. J Pharmacol Exp Ther 2009; 331:212-21. [DOI: 10.1124/jpet.109.152132] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Russa AD, Ishikita N, Masu K, Akutsu H, Saino T, Satoh YI. Microtubule remodeling mediates the inhibition of store-operated calcium entry (SOCE) during mitosis in COS-7 cells. ACTA ACUST UNITED AC 2009; 71:249-63. [PMID: 19359807 DOI: 10.1679/aohc.71.249] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Regulation of the intracellular calcium ion concentration ([Ca(2+)](i)) is critical, because calcium signaling controls diverse and vital cellular processes such as secretion, proliferation, division, gene transcription, and apoptosis. Store-operated calcium entry (SOCE) is the main mechanism through which non-excitable cells replenish and thus maintain this delicate balance. There is limited evidence which indicates that SOCE may be inhibited during mitosis, and the mechanisms leading to the presumed inhibition has not been elucidated. In the present study, we examined and compared the [Ca(2+)](i) dynamics of COS-7 cells in mitotic and non-mitotic phases with special reference paid to SOCE. Laser scanning confocal microscopy to monitor [Ca(2+)](i) dynamics revealed that SOCE was progressively inhibited in mitosis and became virtually absent during the metaphase. We used various cytoskeletal modifying drugs and immunofluorescence to assess the contribution of microtubule and actin filaments in SOCE signaling. Nocodazole treatment caused microtubule reorganization and retraction from the cell periphery that mimicked the natural mitotic microtubule remodeling that was also accompanied by SOCE inhibition. Short exposure to paclitaxel, a microtubule-stabilizing drug, bolstered SOCE, whereas long exposure resulted in microtubule disruption and SOCE inhibition. Actin-modifying drugs did not affect SOCE. These findings indicate that mitotic microtubule remodeling plays a significant role in the inhibition of SOCE during mitosis.
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Affiliation(s)
- Afadhali Denis Russa
- Department of Anatomy (Cell Biology Group), Iwate Medical University School of Medicine, Uchimaru, Morioka, Japan
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Syyong HT, Yang HHC, Trinh G, Cheung C, Kuo KH, van Breemen C. Mechanism of asynchronous Ca(2+) waves underlying agonist-induced contraction in the rat basilar artery. Br J Pharmacol 2009; 156:587-600. [PMID: 19154440 DOI: 10.1111/j.1476-5381.2008.00063.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND AND PURPOSE Uridine 5'-triphosphate (UTP) is a potent vasoconstrictor of cerebral arteries and induces Ca(2+) waves in vascular smooth muscle cells (VSMCs). This study aimed to determine the mechanisms underlying UTP-induced Ca(2+) waves in VSMCs of the rat basilar artery. EXPERIMENTAL APPROACH Isometric force and intracellular Ca(2+) ([Ca(2+)](i)) were measured in endothelium-denuded rat basilar artery using wire myography and confocal microscopy respectively. KEY RESULTS Uridine 5'-triphosphate (0.1-1000 micromol.L(-1)) concentration-dependently induced tonic contraction (pEC(50) = 4.34 +/- 0.13), associated with sustained repetitive oscillations in [Ca(2+)](i) propagating along the length of the VSMCs as asynchronized Ca(2+) waves. Inhibition of Ca(2+) reuptake in sarcoplasmic reticulum (SR) by cyclopiazonic acid abolished the Ca(2+) waves and resulted in a dramatic drop in tonic contraction. Nifedipine reduced the frequency of Ca(2+) waves by 40% and tonic contraction by 52%, and the nifedipine-insensitive component was abolished by SKF-96365, an inhibitor of receptor- and store-operated channels, and KB-R7943, an inhibitor of reverse-mode Na(+)/Ca(2+) exchange. Ongoing Ca(2+) waves and tonic contraction were also abolished after blockade of inositol-1,4,5-triphosphate-sensitive receptors by 2-aminoethoxydiphenylborate, but not by high concentrations of ryanodine or tetracaine. However, depletion of ryanodine-sensitive SR Ca(2+) stores prior to UTP stimulation prevented Ca(2+) waves. CONCLUSIONS AND IMPLICATIONS Uridine 5'-triphosphate-induced Ca(2+) waves may underlie tonic contraction and appear to be produced by repetitive cycles of regenerative Ca(2+) release from the SR through inositol-1,4,5-triphosphate-sensitive receptors. Maintenance of Ca(2+) waves requires SR Ca(2+) reuptake from Ca(2+) entry across the plasma membrane via L-type Ca(2+) channels, receptor- and store-operated channels, and reverse-mode Na(+)/Ca(2+) exchange.
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Affiliation(s)
- H T Syyong
- Department of Anesthesiology, Pharmacology & Therapeutics, University of British Columbia, Vancouver, British Columbia, Canada
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Sandow SL, Haddock RE, Hill CE, Chadha PS, Kerr PM, Welsh DG, Plane F. WHAT'S WHERE AND WHY AT A VASCULAR MYOENDOTHELIAL MICRODOMAIN SIGNALLING COMPLEX. Clin Exp Pharmacol Physiol 2009; 36:67-76. [DOI: 10.1111/j.1440-1681.2008.05076.x] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Serrano F, Deshazer M, Smith KDB, Ananta JS, Wilson LJ, Pautler RG. Assessing transneuronal dysfunction utilizing manganese-enhanced MRI (MEMRI). Magn Reson Med 2008; 60:169-75. [PMID: 18581360 DOI: 10.1002/mrm.21648] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In this study we utilized manganese-enhanced MRI (MEMRI) to evaluate the in vivo transneuronal efficiency of manganese ion (Mn(2+)) movement as a means to assess overall changes in neuronal function. We designated this extension the manganese transfer index (MTI) value. To evaluate the MTI value as an index of transneuronal physiology we examined both pharmacological agents and different mouse models of neuronal dysfunction. We found that treatment with isoflurane, which attenuates synaptic vesicle release, or memantine, which attenuates postsynaptic uptake of Ca(2+) as well as Mn(2+), resulted in a decrease in the MTI value. Furthermore, we evaluated if changes in the MTI value can be detected in three knockout mice with altered brain function accompanied either with or without neurodegeneration. Our data demonstrate that the MTI values either decreased or increased in response to different functional as well as anatomical changes. These results demonstrate the potential utility of the MTI value as an in vivo index for the detection of changes in neuronal function in animal models of human disease.
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Affiliation(s)
- Faridis Serrano
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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Nakagawa T, Otsubo Y, Yatani Y, Shirakawa H, Kaneko S. Mechanisms of substrate transport-induced clustering of a glial glutamate transporter GLT-1 in astroglial-neuronal cultures. Eur J Neurosci 2008; 28:1719-30. [PMID: 18973588 DOI: 10.1111/j.1460-9568.2008.06494.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Glutamate uptake by the Na(+)-dependent glutamate transporter GLT-1, which is predominantly expressed in astrocytes, is crucial for regulating glutamate concentration at the synaptic cleft and achieving proper excitatory neurotransmission. A body of evidence suggests that GLT-1 constitutively traffics between the plasma membrane and endosomes via an endocytosis/recycling pathway, and forms a cluster. Here, we report substrate transport via GLT-1-induced formation of GLT-1 cluster accompanied by intracellular trafficking in rat astroglial-neuronal cultures. We constructed a recombinant adenovirus expressing enhanced green fluorescence protein (EGFP)-tagged GLT-1. Adenoviral infection resulted in the expression of functional GLT-1-EGFP preferentially in astrocytes, partly as clusters. Treatment with glutamate, but not N-methyl-D-aspartate, dramatically increased the number of GLT-1 clusters within 1 h. The estimated EC(50) value of glutamate was 240 microm. In addition, glutamate decreased the cell surface expression and increased the intracellular expression of GLT-1. The GLT-1 clusters were found in early and recycling endosomes and partly in lysosomes, and were inhibited by blockade of endocytotic pathways. Ionotropic and metabotropic glutamate receptor antagonists had no effect on glutamate-induced GLT-1 clustering. The non-transportable glutamate uptake inhibitors (2S,3S)-3-[3-[4-(trifluoromethyl)benzoylamino]benzyloxy]aspartate and dihydrokainate, as well as Na(+)-free conditions, prevented the glutamate-induced GLT-1 clustering, whereas the competitive substrates, aspartate and L-trans-pyrrolidine-2,4-dicarboxylate, induced GLT-1 clustering. Furthermore, the Na(+)/K(+)-ATPase inhibitor, ouabain, and the Na(+) ionophores, gramicidin and monensin, produced GLT-1 clustering. Modulators of intracellular Ca(2+)signaling or membrane depolarization had no effect on GLT-1 clustering. Taken together, these results suggest that Na(+) influx associated with GLT-1 substrate transport triggers the formation of GLT-1 clusters accompanied by intracellular trafficking via endocytotic pathways in astrocytes.
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Affiliation(s)
- Takayuki Nakagawa
- Department of Molecular Pharmacology, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
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Neuron is the primary target of Ca2+ paradox-type insult-induced cell injury in neuron/astrocyte co-cultures. Neurochem Int 2008; 52:887-96. [DOI: 10.1016/j.neuint.2007.10.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2007] [Revised: 10/02/2007] [Accepted: 10/05/2007] [Indexed: 11/22/2022]
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Reverse mode Na+/Ca2+ exchangers trigger the release of Ca2+ from intracellular Ca2+ stores in cultured rat embryonic cortical neurons. Brain Res 2008; 1201:41-51. [DOI: 10.1016/j.brainres.2008.01.042] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2007] [Revised: 01/09/2008] [Accepted: 01/14/2008] [Indexed: 11/15/2022]
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Storozhevykh TP, Sorokina EG, Vabnitz AV, Senilova YE, Tukhbatova GR, Pinelis VG. Na+/Ca2+ exchange and regulation of cytoplasmic concentration of calcium in rat cerebellar neurons treated with glutamate. BIOCHEMISTRY (MOSCOW) 2007; 72:750-9. [PMID: 17680767 DOI: 10.1134/s0006297907070097] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In the present work, the forward and/or reversed Na+/Ca2+ exchange in cerebellar granular cells was suppressed by substitution of Na+o by Li+ before, during, and after exposure to glutamate for varied time and also using the inhibitor KB-R7943 of the reversed exchange. After glutamate challenge for 1 min, Na+o/Li+ substitution did not influence the recovery of low [Ca2+]i in a calcium-free medium. A 1-h incubation with 100 microM glutamate induced in the neurons a biphasic and irreversible [Ca2+]i rise (delayed calcium deregulation (DCD)), enhancement of [Na+]i, and decrease in the mitochondrial potential. If Na+o had been substituted by Li+ before the application of glutamate, i.e. the exchange reversal was suppressed during the exposure to glutamate, the number of cells with DCD was nearly fourfold lowered. However, addition of the Na+/K+-ATPase inhibitor ouabain (0.5 mM) not preventing the exchange reversal also decreased DCD in the presence of glutamate. Both exposures decreased the glutamate-caused loss of intracellular ATP. Glucose deprivation partially abolished protective effects of the Na+o/Li+ substitution and ouabain. KB-R7943 (10 microM) increased 7.4-fold the number of cells with the [Ca2+]i decreased to the basal level after the exposure to glutamate. Thus, reversal of the Na+/Ca2+ exchange reinforced the glutamate-caused perturbations of calcium homeostasis in the neurons and slowed the recovery of the decreased [Ca2+]i in the post-glutamate period. However, for development of DCD, in addition to the exchange reversal, other factors are required, in particular a decrease in the intracellular concentration of ATP.
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Affiliation(s)
- T P Storozhevykh
- Research Center for Children's Health, Russian Academy of Medical Sciences, Moscow, 119991, Russia.
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Baba A. [Molecular pharmacologic approaches to functional analysis of new biological target molecules for drug discovery]. YAKUGAKU ZASSHI 2007; 127:1643-54. [PMID: 17917422 DOI: 10.1248/yakushi.127.1643] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This review focuses on two pharmacologic approaches to the functional evaluation of new target molecules for drug discovery. One is the development of a novel specific antagonist of the Na(+)-Ca(++) exchanger (NCX) SEA0400. The other is a comprehensive analysis of the functions of pituitary adenylate cyclase-activating polypeptide (PACAP), a neuropeptide ligand for G protein-coupled receptors. NCX is the one of the last target molecules regulating the cellular Ca(++) concentration. There was no efficient way to address the pathophysiologic roles of NCX until a specific antagonist, 2-[4-[(2,5-difluorophenyl)methoxy]phenoxy]-5-ethoxyaniline (SEA0400), was developed. Our recent studies using SEA0400 clearly showed the possible roles of NCX in several pathologic states of cardiovascular and nervous tissues. In our second approach including gene-targeting methods, we found new, unexpected roles of PACAP in higher brain functions, such as psychomotor, cognition, photoentrainment, and nociception. Based on these experimental findings, a genetic association study in schizophrenia patients revealed that the single-nucleotide polymorphisms of the PACAP gene are significantly associated with the hypofunction of the hippocampus. Regarding the peripheral roles of PACAP, we found that PACAP is involved not only in the regulation of insulin secretion in pancreatic islets, but also in the regulation of islet turnover. In subsequent phenotypic analysis of PACAP transgenic mice, we identified novel candidate genes that probably have promising functional roles.
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Affiliation(s)
- Akemichi Baba
- Molecular Pharmacological Laboratory, Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita City 565-0871, Japan.
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Török TL. Electrogenic Na+/Ca2+-exchange of nerve and muscle cells. Prog Neurobiol 2007; 82:287-347. [PMID: 17673353 DOI: 10.1016/j.pneurobio.2007.06.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Revised: 04/12/2007] [Accepted: 06/12/2007] [Indexed: 12/19/2022]
Abstract
The plasma membrane Na(+)/Ca(2+)-exchanger is a bi-directional electrogenic (3Na(+):1Ca(2+)) and voltage-sensitive ion transport mechanism, which is mainly responsible for Ca(2+)-extrusion. The Na(+)-gradient, required for normal mode operation, is created by the Na(+)-pump, which is also electrogenic (3Na(+):2K(+)) and voltage-sensitive. The Na(+)/Ca(2+)-exchanger operational modes are very similar to those of the Na(+)-pump, except that the uncoupled flux (Na(+)-influx or -efflux?) is missing. The reversal potential of the exchanger is around -40 mV; therefore, during the upstroke of the AP it is probably transiently activated, leading to Ca(2+)-influx. The Na(+)/Ca(2+)-exchange is regulated by transported and non-transported external and internal cations, and shows ATP(i)-, pH- and temperature-dependence. The main problem in determining the role of Na(+)/Ca(2+)-exchange in excitation-secretion/contraction coupling is the lack of specific (mode-selective) blockers. During recent years, evidence has been accumulated for co-localisation of the Na(+)-pump, and the Na(+)/Ca(2+)-exchanger and their possible functional interaction in the "restricted" or "fuzzy space." In cardiac failure, the Na(+)-pump is down-regulated, while the exchanger is up-regulated. If the exchanger is working in normal mode (Ca(2+)-extrusion) during most of the cardiac cycle, upregulation of the exchanger may result in SR Ca(2+)-store depletion and further impairment in contractility. If so, a normal mode selective Na(+)/Ca(2+)-exchange inhibitor would be useful therapy for decompensation, and unlike CGs would not increase internal Na(+). In peripheral sympathetic nerves, pre-synaptic alpha(2)-receptors may regulate not only the VSCCs but possibly the reverse Na(+)/Ca(2+)-exchange as well.
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Affiliation(s)
- Tamás L Török
- Department of Pharmacodynamics, Semmelweis University, P.O. Box 370, VIII. Nagyvárad-tér 4, H-1445 Budapest, Hungary.
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