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Feng W, Lopez JR, Antrobus S, Zheng J, Uryash A, Dong Y, Beqollari D, Bannister RA, Hopkins PM, Beam KG, Allen PD, Pessah IN. Putative malignant hyperthermia mutation Ca V1.1-R174W is insufficient to trigger a fulminant response to halothane or confer heat stress intolerance. J Biol Chem 2023; 299:104992. [PMID: 37392848 PMCID: PMC10413282 DOI: 10.1016/j.jbc.2023.104992] [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: 04/04/2023] [Revised: 06/16/2023] [Accepted: 06/20/2023] [Indexed: 07/03/2023] Open
Abstract
Malignant hyperthermia susceptibility (MHS) is an autosomal dominant pharmacogenetic disorder that manifests as a hypermetabolic state when carriers are exposed to halogenated volatile anesthetics or depolarizing muscle relaxants. In animals, heat stress intolerance is also observed. MHS is linked to over 40 variants in RYR1 that are classified as pathogenic for diagnostic purposes. More recently, a few rare variants linked to the MHS phenotype have been reported in CACNA1S, which encodes the voltage-activated Ca2+ channel CaV1.1 that conformationally couples to RyR1 in skeletal muscle. Here, we describe a knock-in mouse line that expresses one of these putative variants, CaV1.1-R174W. Heterozygous (HET) and homozygous (HOM) CaV1.1-R174W mice survive to adulthood without overt phenotype but fail to trigger with fulminant malignant hyperthermia when exposed to halothane or moderate heat stress. All three genotypes (WT, HET, and HOM) express similar levels of CaV1.1 by quantitative PCR, Western blot, [3H]PN200-110 receptor binding and immobilization-resistant charge movement densities in flexor digitorum brevis fibers. Although HOM fibers have negligible CaV1.1 current amplitudes, HET fibers have similar amplitudes to WT, suggesting a preferential accumulation of the CaV1.1-WT protein at triad junctions in HET animals. Never-the-less both HET and HOM have slightly elevated resting free Ca2+ and Na+ measured with double barreled microelectrode in vastus lateralis that is disproportional to upregulation of transient receptor potential canonical (TRPC) 3 and TRPC6 in skeletal muscle. CaV1.1-R174W and upregulation of TRPC3/6 alone are insufficient to trigger fulminant malignant hyperthermia response to halothane and/or heat stress in HET and HOM mice.
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Affiliation(s)
- Wei Feng
- Department of Molecular Biosciences, University of California Davis, Davis, California, USA
| | - Jose R Lopez
- Department of Molecular Biosciences, University of California Davis, Davis, California, USA; Department of Research, Mount Sinai Medical Center, Miami Beach, Florida, USA
| | - Shane Antrobus
- Department of Molecular Biosciences, University of California Davis, Davis, California, USA
| | - Jing Zheng
- Department of Molecular Biosciences, University of California Davis, Davis, California, USA
| | - Arkady Uryash
- Department of Research, Mount Sinai Medical Center, Miami Beach, Florida, USA
| | - Yao Dong
- Department of Molecular Biosciences, University of California Davis, Davis, California, USA
| | - Donald Beqollari
- Department of Medicine-Cardiology Division, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Roger A Bannister
- Department of Medicine-Cardiology Division, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Philip M Hopkins
- Institute of Medical Research at St James's, University of Leeds, Leeds, United Kingdom
| | - Kurt G Beam
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Paul D Allen
- Department of Molecular Biosciences, University of California Davis, Davis, California, USA; Institute of Medical Research at St James's, University of Leeds, Leeds, United Kingdom
| | - Isaac N Pessah
- Department of Molecular Biosciences, University of California Davis, Davis, California, USA.
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Neuromodulatory effect of interleukin 1β in the dorsal raphe nucleus on individual differences in aggression. Mol Psychiatry 2022; 27:2563-2579. [PMID: 33931727 PMCID: PMC8556414 DOI: 10.1038/s41380-021-01110-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 03/26/2021] [Accepted: 04/09/2021] [Indexed: 02/03/2023]
Abstract
Heightened aggressive behavior is considered as one of the central symptoms of many neuropsychiatric disorders including autism, schizophrenia, and dementia. The consequences of aggression pose a heavy burden on patients and their families and clinicians. Unfortunately, we have limited treatment options for aggression and lack mechanistic insight into the causes of aggression needed to inform new efforts in drug discovery and development. Levels of proinflammatory cytokines in the periphery or cerebrospinal fluid were previously reported to correlate with aggressive traits in humans. However, it is still unknown whether cytokines affect brain circuits to modulate aggression. Here, we examined the functional role of interleukin 1β (IL-1β) in mediating individual differences in aggression using a resident-intruder mouse model. We found that nonaggressive mice exhibit higher levels of IL-1β in the dorsal raphe nucleus (DRN), the major source of forebrain serotonin (5-HT), compared to aggressive mice. We then examined the effect of pharmacological antagonism and viral-mediated gene knockdown of the receptors for IL-1 within the DRN and found that both treatments consistently increased aggressive behavior of male mice. Aggressive mice also exhibited higher c-Fos expression in 5-HT neurons in the DRN compared to nonaggressive mice. In line with these findings, deletion of IL-1 receptor in the DRN enhanced c-Fos expression in 5-HT neurons during aggressive encounters, suggesting that modulation of 5-HT neuronal activity by IL-1β signaling in the DRN controls expression of aggressive behavior.
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Aleman M, Zhang R, Feng W, Qi L, Lopez JR, Crowe C, Dong Y, Cherednichenko G, Pessah IN. Dietary Caffeine Synergizes Adverse Peripheral and Central Responses to Anesthesia in Malignant Hyperthermia Susceptible Mice. Mol Pharmacol 2020; 98:351-363. [PMID: 32764093 DOI: 10.1124/mol.120.119412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 07/31/2020] [Indexed: 11/22/2022] Open
Abstract
Ryanodine receptor (RYR) mutations confer stress-triggered malignant hyperthermia (MH) susceptibility. Dietary caffeine (CAF) is the most commonly consumed psychoactive compound by humans. CAF-triggered Ca2+ release and its influences on skeletal muscle contractility are widely used as experimental tools to study RYR function/dysfunction and diagnose MH susceptibility. We hypothesize that dietary CAF achieving blood levels measured in human plasma exacerbates the penetrance of RYR1 MH susceptibility mutations triggered by gaseous anesthetic, affecting both central and peripheral adverse responses. Heterozygous R163C-RYR1 (HET) MH susceptible mice are used to investigate the influences of dietary CAF on both peripheral and central responses before and after induction of halothane (HAL) maintenance anesthesia under experimental conditions that maintain normal core body temperature. HET mice receiving CAF (plasma CAF 893 ng/ml) have significantly shorter times to respiratory arrest compared with wild type, without altering blood chemistry or displaying hyperthermia or muscle rigor. Intraperitoneal bolus dantrolene before HAL prolongs time to respiratory arrest. A pilot electrographic study using subcutaneous electrodes reveals that dietary CAF does not alter baseline electroencephalogram (EEG) total power, but significantly shortens delay to isoelectric EEG, which precedes respiratory and cardiac arrest. CAF ± HAL are studied on RYR1 single-channel currents and HET myotubes to define molecular mechanisms of gene-by-environment synergism. Strong pharmacological synergism between CAF and HAL is demonstrated in both single-channel and myotube preparations. Central and peripheral nervous systems mediate adverse responses to HAL in a HET model of MH susceptibility exposed to dietary CAF, a modifiable lifestyle factor that may mitigate risks of acute and chronic diseases associated with RYR1 mutations. SIGNIFICANCE STATEMENT: Dietary caffeine at a human-relevant dose synergizes adverse peripheral and central responses to anesthesia in malignant hyperthermia susceptible mice. Synergism of these drugs can be attributed to their actions at ryanodine receptors.
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Affiliation(s)
- Monica Aleman
- Department of Molecular Biosciences, School of Veterinary Medicine (R.Z., W.F., J.R.L., Y.D., G.C., I.N.P.), Department of Medicine and Epidemiology, The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine (M.A., C.C.), and Department of Public Health Sciences, School of Medicine, School of Medicine (L.Q.), University of California, Davis, California
| | - Rui Zhang
- Department of Molecular Biosciences, School of Veterinary Medicine (R.Z., W.F., J.R.L., Y.D., G.C., I.N.P.), Department of Medicine and Epidemiology, The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine (M.A., C.C.), and Department of Public Health Sciences, School of Medicine, School of Medicine (L.Q.), University of California, Davis, California
| | - Wei Feng
- Department of Molecular Biosciences, School of Veterinary Medicine (R.Z., W.F., J.R.L., Y.D., G.C., I.N.P.), Department of Medicine and Epidemiology, The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine (M.A., C.C.), and Department of Public Health Sciences, School of Medicine, School of Medicine (L.Q.), University of California, Davis, California
| | - Lihong Qi
- Department of Molecular Biosciences, School of Veterinary Medicine (R.Z., W.F., J.R.L., Y.D., G.C., I.N.P.), Department of Medicine and Epidemiology, The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine (M.A., C.C.), and Department of Public Health Sciences, School of Medicine, School of Medicine (L.Q.), University of California, Davis, California
| | - Jose R Lopez
- Department of Molecular Biosciences, School of Veterinary Medicine (R.Z., W.F., J.R.L., Y.D., G.C., I.N.P.), Department of Medicine and Epidemiology, The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine (M.A., C.C.), and Department of Public Health Sciences, School of Medicine, School of Medicine (L.Q.), University of California, Davis, California
| | - Chelsea Crowe
- Department of Molecular Biosciences, School of Veterinary Medicine (R.Z., W.F., J.R.L., Y.D., G.C., I.N.P.), Department of Medicine and Epidemiology, The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine (M.A., C.C.), and Department of Public Health Sciences, School of Medicine, School of Medicine (L.Q.), University of California, Davis, California
| | - Yao Dong
- Department of Molecular Biosciences, School of Veterinary Medicine (R.Z., W.F., J.R.L., Y.D., G.C., I.N.P.), Department of Medicine and Epidemiology, The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine (M.A., C.C.), and Department of Public Health Sciences, School of Medicine, School of Medicine (L.Q.), University of California, Davis, California
| | - Genady Cherednichenko
- Department of Molecular Biosciences, School of Veterinary Medicine (R.Z., W.F., J.R.L., Y.D., G.C., I.N.P.), Department of Medicine and Epidemiology, The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine (M.A., C.C.), and Department of Public Health Sciences, School of Medicine, School of Medicine (L.Q.), University of California, Davis, California
| | - Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine (R.Z., W.F., J.R.L., Y.D., G.C., I.N.P.), Department of Medicine and Epidemiology, The William R. Pritchard Veterinary Medical Teaching Hospital, School of Veterinary Medicine (M.A., C.C.), and Department of Public Health Sciences, School of Medicine, School of Medicine (L.Q.), University of California, Davis, California
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Diamandakis D, Zieminska E, Siwiec M, Tokarski K, Salinska E, Lenart J, Hess G, Lazarewicz JW. Tetrabromobisphenol A-induced depolarization of rat cerebellar granule cells: ex vivo and in vitro studies. CHEMOSPHERE 2019; 223:64-73. [PMID: 30769291 DOI: 10.1016/j.chemosphere.2019.02.032] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 02/05/2019] [Accepted: 02/07/2019] [Indexed: 06/09/2023]
Abstract
The brominated flame retardant tetrabromobisphenol A (TBBPA) is toxic to cultured brain neurons, and glutamate receptors partially mediate this effect; consequently, the depolarizing effect of TBBPA on neurons is to be expected, but it is yet to be actually demonstrated. The aim of this study was to detect TBBPA-evoked depolarization and identify the underlying mechanisms. The plasma membrane potential of rat cerebellar granule cells (CGC) in cerebellar slices or in primary cultures was measured using whole-cell current clamp recordings, or the fluorescent probe oxonol VI, respectively. The contribution of NMDA and AMPA receptors, voltage-gated sodium channels and intracellular calcium mobilization was tested using their selective antagonists or inhibitors. Direct interactions of TBBPA with NMDARs were tested by measuring the specific binding of radiolabeled NMDAR ligands to isolated rat cortical membrane fraction. TBBPA (25 μM) strongly depolarized CGC in cerebellar slices, and at ≥ 7.5 μM concentration-dependently depolarized primary CGC cultures. Depolarization of the primary CGC by 25 μM TBBPA was partly reduced when MK-801 was applied alone or in combination with either TTX or CNQX, or where bastadin 12 was applied in combination with ryanodine, whereas depolarization was completely prevented when MK-801, CNQX and TTX where combined. TBBPA had no effect on the specific binding of NMDAR radio-ligands to isolated cortical membranes. These results demonstrate the depolarizing effect of TBBPA on CGC, which is mainly mediated by ionotropic glutamate receptors, while voltage-gated sodium channels are also involved. We found no evidence for the direct activation of NMDARs by TBBPA.
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Affiliation(s)
- Dominik Diamandakis
- Department of Neurochemistry, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawinskiego 5, 02-106, Warsaw, Poland.
| | - Elzbieta Zieminska
- Department of Neurochemistry, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawinskiego 5, 02-106, Warsaw, Poland.
| | - Marcin Siwiec
- Department of Physiology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12, 31-343, Krakow, Poland.
| | - Krzysztof Tokarski
- Department of Physiology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12, 31-343, Krakow, Poland.
| | - Elzbieta Salinska
- Department of Neurochemistry, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawinskiego 5, 02-106, Warsaw, Poland.
| | - Jacek Lenart
- Department of Neurochemistry, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawinskiego 5, 02-106, Warsaw, Poland.
| | - Grzegorz Hess
- Department of Physiology, Institute of Pharmacology, Polish Academy of Sciences, Smetna 12, 31-343, Krakow, Poland.
| | - Jerzy W Lazarewicz
- Department of Neurochemistry, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawinskiego 5, 02-106, Warsaw, Poland.
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Masuno M, Molinski TF. Resolution of Atropisomeric Cyclic Catechol Monoether O-Sulfate Esters by a Molluscan Sulfatase. ACS OMEGA 2018; 3:7771-7775. [PMID: 30087921 PMCID: PMC6072249 DOI: 10.1021/acsomega.7b01899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Accepted: 01/22/2018] [Indexed: 06/08/2023]
Abstract
Atropisomeric cyclic catechol ethers are notoriously difficult to resolve by classical chiral phase high-performance liquid chromatography. Here, we show the first application of sulfatase enzymes for the kinetic resolution of O-sulfato-catechol ethers with enantioselectivities ranging from 30 to 65% ee, as determined by preparation of their Marfey's ether derivatives. Substrate-structure dependence was briefly explored.
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Affiliation(s)
- Makoto
N. Masuno
- Department
of Chemistry, University of California, 1 Shields Avenue, Davis, California 95616, United States
| | - Tadeusz F. Molinski
- Department of Chemistry and Biochemistry and Skaggs School of Pharmacy and Pharmaceutical
Sciences, University of California, 9500 Gilman Drive 0358, La Jolla, San Diego, California 92093, United States
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6
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Zheng J, McKinnie SMK, El Gamal A, Feng W, Dong Y, Agarwal V, Fenical W, Kumar A, Cao Z, Moore BS, Pessah IN. Organohalogens Naturally Biosynthesized in Marine Environments and Produced as Disinfection Byproducts Alter Sarco/Endoplasmic Reticulum Ca 2+ Dynamics. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2018; 52:5469-5478. [PMID: 29617551 PMCID: PMC6195434 DOI: 10.1021/acs.est.8b00512] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Contemporary sources of organohalogens produced as disinfection byproducts (DBPs) are receiving considerable attention as emerging pollutants because of their abundance, persistence, and potential to structurally mimic natural organohalogens produced by bacteria that serve signaling or toxicological functions in marine environments. Here, we tested 34 organohalogens from anthropogenic and marine sources to identify compounds active toward ryanodine receptor (RyR1), known toxicological targets of non-dioxin-like polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). [3H]Ryanodine ([3H]Ry) binding screening (≤2 μM) identified 10 highly active organohalogens. Further analysis indicated that 2,3-dibromoindole (14), tetrabromopyrrole (31), and 2,3,5-tribromopyrrole (34) at 10 μM were the most efficacious at enhancing [3H]Ry binding. Interestingly, these congeners also inhibited microsomal sarcoplasmic/endoplasmic reticulum (SR/ER) Ca2+ ATPase (SERCA1a). Dual SERCA1a inhibition and RyR1 activation triggered Ca2+ efflux from microsomal vesicles with initial rates rank ordered 31 > 34 > 14. Hexabromobipyrroles (25) enhanced [3H]Ry binding moderately with strong SERCA1a inhibition, whereas pyrrole (24), 2,3,4-tribromopyrrole (26), and ethyl-4-bromopyrrole-2-carboxylate (27) were inactive. Of three PBDE derivatives of marine origin active in the [3H]Ry assay, 4'-hydroxy-2,3',4,5',6-pentabromodiphenyl ether (18) was also a highly potent SERCA1a inhibitor. Molecular targets of marine organohalogens that are also DBPs of emerging environmental concern are likely to contribute to their toxicity.
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Affiliation(s)
- Jing Zheng
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California 95616, United States
- Department of TCM Pharmacology, School of Traditional Chinese Medicines, China Pharmaceutical University, Nanjing 210009, China
| | - Shaun M. K. McKinnie
- Center for Oceans and Human Health, Scripps Institution of Oceanography & Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093-0021, United States
| | - Abrahim El Gamal
- Center for Oceans and Human Health, Scripps Institution of Oceanography & Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093-0021, United States
| | - Wei Feng
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California 95616, United States
| | - Yao Dong
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California 95616, United States
| | | | | | - Abdhesh Kumar
- Center for Oceans and Human Health, Scripps Institution of Oceanography & Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093-0021, United States
| | - Zhengyu Cao
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California 95616, United States
- Department of TCM Pharmacology, School of Traditional Chinese Medicines, China Pharmaceutical University, Nanjing 210009, China
| | - Bradley S. Moore
- Center for Oceans and Human Health, Scripps Institution of Oceanography & Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, California 92093-0021, United States
| | - Isaac N. Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California 95616, United States
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Irwin MR, Opp MR. Sleep Health: Reciprocal Regulation of Sleep and Innate Immunity. Neuropsychopharmacology 2017; 42:129-155. [PMID: 27510422 PMCID: PMC5143488 DOI: 10.1038/npp.2016.148] [Citation(s) in RCA: 270] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 07/29/2016] [Accepted: 08/02/2016] [Indexed: 12/11/2022]
Abstract
Sleep disturbances including insomnia independently contribute to risk of inflammatory disorders and major depressive disorder. This review and overview provides an integrated understanding of the reciprocal relationships between sleep and the innate immune system and considers the role of sleep in the nocturnal regulation of the inflammatory biology dynamics; the impact of insomnia complaints, extremes of sleep duration, and experimental sleep deprivation on genomic, cellular, and systemic markers of inflammation; and the influence of sleep complaints and insomnia on inflammaging and molecular processes of cellular aging. Clinical implications of this research include discussion of the contribution of sleep disturbance to depression and especially inflammation-related depressive symptoms. Reciprocal action of inflammatory mediators on the homeostatic regulation of sleep continuity and sleep macrostructure, and the potential of interventions that target insomnia to reverse inflammation, are also reviewed. Together, interactions between sleep and inflammatory biology mechanisms underscore the implications of sleep disturbance for inflammatory disease risk, and provide a map to guide the development of treatments that modulate inflammation, improve sleep, and promote sleep health.
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Affiliation(s)
- Michael R Irwin
- Department of Psychiatry and Biobehavioral Sciences, Cousins Center for Psychoneuroimmunology, UCLA Semel Institute for Neuroscience Director and Mindful Awareness Research Center, University of California, Los Angeles, CA, USA
| | - Mark R Opp
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA, USA
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Zieminska E, Stafiej A, Toczylowska B, Albrecht J, Lazarewicz JW. Role of Ryanodine and NMDA Receptors in Tetrabromobisphenol A-Induced Calcium Imbalance and Cytotoxicity in Primary Cultures of Rat Cerebellar Granule Cells. Neurotox Res 2015. [PMID: 26215658 PMCID: PMC4556744 DOI: 10.1007/s12640-015-9546-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The study assessed the role of ryanodine receptors (RyRs) and NMDA receptors (NMDARs) in the Ca2+ transients and cytotoxicity induced in neurons by the brominated flame retardant tetrabromobisphenol A (TBBPA). Primary cultures of rat cerebellar granule cells (CGC) were exposed to 7.5, 10, or 25 µM TBBPA for 30 min, and cell viability was assessed after 24 h. Moreover, 45Ca uptake was measured, and changes in the intracellular Ca2+ concentration ([Ca2+]i) were studied using the fluo-3 probe. The involvement of NMDARs and RyRs was verified using the pertinent receptor antagonists, 0.5 µM MK-801 and 2.5 µM bastadin 12, which was co-applied with 200 µM ryanodine, respectively. The results show that TBBPA concentration-dependently induces an increase in [Ca2+]i. This effect was partly suppressed by the inhibitors of RyRs and NMDARs when administered separately, and completely abrogated by their combined application. A concentration-dependent activation of 45Ca uptake by TBBPA was prevented by MK-801 but not by RyR inhibitors. Application of ≥10 µM TBBPA concentration-dependently reduced neuronal viability, and this effect was only partially and to an equal degree reduced by NMDAR and RyR antagonists given either separately or in combination. Our results directly demonstrate that both the RyR-mediated release of intracellular Ca2+ and the NMDAR-mediated influx of Ca2+ into neurons participate in the mechanism of TBBPA-induced Ca2+ imbalance in CGC and play a significant, albeit not exclusive, role in the mechanisms of TBBPA cytotoxicity.
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Affiliation(s)
- Elzbieta Zieminska
- Department of Neurochemistry, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawinskiego 5, 02-106, Warsaw, Poland,
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9
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Is lymphocyte adenosine a diagnostic marker of clinical malignant hyperthermia? A pilot study. Crit Care Med 2015; 43:584-93. [PMID: 25479114 DOI: 10.1097/ccm.0000000000000744] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Malignant hyperthermia is a pharmacogenetic disorder typically triggered by potent inhalation anesthetics and/or the depolarizing muscle relaxant succinylcholine in malignant hyperthermia-susceptible individuals. Since lymphocytes express the same Ca channel mutation found in malignant hyperthermia-susceptible muscle, we investigated agonist-induced adenosine formation in lymphocytes as an index of sarcoplasmic reticulum Ca-release-induced adenosine 5'-triphosphate turnover as a potential minimally invasive functional malignant hyperthermia assay. DESIGN Application of lymphocytes for malignant hyperthermia diagnosis. SETTING Hospitals and university laboratory. SUBJECTS Malignant hyperthermia-susceptible patients (n = 13) and normal subjects (n = 11). INTERVENTIONS Adenosine formation due to malignant hyperthermia-triggering agent halothane or the ryanodine receptor Ca channels agonist 4-chloro-m-cresol was compared in blood lymphocytes from malignant hyperthermia-susceptible patients and normal subjects. MEASUREMENTS AND MAIN RESULTS Cai and adenosine were measured in fresh or immortalized blood lymphocytes incubated with 0-10 mM 4-chloro-m-cresol or 0-10.7 mM halothane. Cai levels were significantly higher in immortalized malignant hyperthermia-susceptible B cells treated with 0.75 mM 4-chloro-m-cresol relative to controls. Similarly, at 1 mM 4-chloro-m-cresol or 0.96 mM halothane, adenosine levels were significantly higher in malignant hyperthermia-susceptible lymphocytes or immortalized B cells relative to controls. Receiver-operating characteristic analyses showed areas under the 4-chloro-m-cresol receiver-operating characteristic curves near more than or equal to 0.96 (p ≈ 0.0001), suggesting that 4-chloro-m-cresol-induced adenosine could readily distinguish between malignant hyperthermia-susceptible and normal controls cells. CONCLUSIONS Both 4-chloro-m-cresol and halothane caused adenosine accumulation in blood lymphocytes. Adenosine accumulation was markedly increased in malignant hyperthermia-susceptible lymphocytes compared with controls reflecting higher than normal adenosine 5'-triphosphate degradation in the malignant hyperthermia-susceptible cells. Although 4-chloro-m-cresol receiver-operating characteristic curves revealed that adenosine accumulation could readily distinguish between normal and malignant hyperthermia-susceptible lymphocytes, independent confirmation is required with a substantially larger number of enrolled subjects to correctly appreciate the clinical utility of the novel lymphocyte-adenosine protocol for malignant hyperthermia testing.
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Hurtado-Alvarado G, Pavón L, Castillo-García SA, Hernández ME, Domínguez-Salazar E, Velázquez-Moctezuma J, Gómez-González B. Sleep loss as a factor to induce cellular and molecular inflammatory variations. Clin Dev Immunol 2013; 2013:801341. [PMID: 24367384 PMCID: PMC3866883 DOI: 10.1155/2013/801341] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 10/19/2013] [Accepted: 10/21/2013] [Indexed: 12/17/2022]
Abstract
A reduction in the amount of time spent sleeping occurs chronically in modern society. Clinical and experimental studies in humans and animal models have shown that immune function is impaired when sleep loss is experienced. Sleep loss exerts a strong regulatory influence on peripheral levels of inflammatory mediators of the immune response. An increasing number of research projects support the existence of reciprocal regulation between sleep and low-intensity inflammatory response. Recent studies show that sleep deficient humans and rodents exhibit a proinflammatory component; therefore, sleep loss is considered as a risk factor for developing cardiovascular, metabolic, and neurodegenerative diseases (e.g., diabetes, Alzheimer's disease, and multiple sclerosis). Circulating levels of proinflammatory mediators depend on the intensity and duration of the method employed to induce sleep loss. Recognizing the fact that the concentration of proinflammatory mediators is different between acute and chronic sleep-loss may expand the understanding of the relationship between sleep and the immune response. The aim of this review is to integrate data from recent published reports (2002-2013) on the effects of sleep loss on the immune response. This review may allow readers to have an integrated view of the mechanisms involved in central and peripheral deficits induced by sleep loss.
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Affiliation(s)
- Gabriela Hurtado-Alvarado
- Area of Neurosciences, Department of Biology of Reproduction, CBS, Universidad Autónoma Metropolitana, Unidad Iztapalapa, Avenida San Rafael Atlixco No. 186, Colonia Vicentina, Iztapalapa, 09340 Mexico City, Mexico
| | - Lenin Pavón
- Department of Psychoimmunology, National Institute of Psychiatry, “Ramón de la Fuente”, Calzada México-Xochimilco 101, Colonia San Lorenzo Huipulco, Tlalpan, 14370 Mexico City, DF, Mexico
| | - Stephanie Ariadne Castillo-García
- Area of Neurosciences, Department of Biology of Reproduction, CBS, Universidad Autónoma Metropolitana, Unidad Iztapalapa, Avenida San Rafael Atlixco No. 186, Colonia Vicentina, Iztapalapa, 09340 Mexico City, Mexico
| | - María Eugenia Hernández
- Department of Psychoimmunology, National Institute of Psychiatry, “Ramón de la Fuente”, Calzada México-Xochimilco 101, Colonia San Lorenzo Huipulco, Tlalpan, 14370 Mexico City, DF, Mexico
| | - Emilio Domínguez-Salazar
- Area of Neurosciences, Department of Biology of Reproduction, CBS, Universidad Autónoma Metropolitana, Unidad Iztapalapa, Avenida San Rafael Atlixco No. 186, Colonia Vicentina, Iztapalapa, 09340 Mexico City, Mexico
| | - Javier Velázquez-Moctezuma
- Area of Neurosciences, Department of Biology of Reproduction, CBS, Universidad Autónoma Metropolitana, Unidad Iztapalapa, Avenida San Rafael Atlixco No. 186, Colonia Vicentina, Iztapalapa, 09340 Mexico City, Mexico
| | - Beatriz Gómez-González
- Area of Neurosciences, Department of Biology of Reproduction, CBS, Universidad Autónoma Metropolitana, Unidad Iztapalapa, Avenida San Rafael Atlixco No. 186, Colonia Vicentina, Iztapalapa, 09340 Mexico City, Mexico
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11
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Bannister RA, Beam KG. Ca(V)1.1: The atypical prototypical voltage-gated Ca²⁺ channel. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:1587-97. [PMID: 22982493 DOI: 10.1016/j.bbamem.2012.09.007] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2012] [Revised: 09/04/2012] [Accepted: 09/05/2012] [Indexed: 11/28/2022]
Abstract
Ca(V)1.1 is the prototype for the other nine known Ca(V) channel isoforms, yet it has functional properties that make it truly atypical of this group. Specifically, Ca(V)1.1 is expressed solely in skeletal muscle where it serves multiple purposes; it is the voltage sensor for excitation-contraction coupling and it is an L-type Ca²⁺ channel which contributes to a form of activity-dependent Ca²⁺ entry that has been termed Excitation-coupled Ca²⁺ entry. The ability of Ca(V)1.1 to serve as voltage-sensor for excitation-contraction coupling appears to be unique among Ca(V) channels, whereas the physiological role of its more conventional function as a Ca²⁺ channel has been a matter of uncertainty for nearly 50 years. In this chapter, we discuss how Ca(V)1.1 supports excitation-contraction coupling, the possible relevance of Ca²⁺ entry through Ca(V)1.1 and how alterations of Ca(V)1.1 function can have pathophysiological consequences. This article is part of a Special Issue entitled: Calcium channels.
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Affiliation(s)
- Roger A Bannister
- Department of Medicine, Cardiology Division, University of Colorado Denver-Anschutz Medical Campus, Aurora, CO 80045, USA.
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12
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Abstract
Recent research has overcome the old paradigms of the brain as an immunologically privileged organ, and of the exclusive role of neurotransmitters and neuropeptides as signal transducers in the central nervous system. Growing evidence suggests that the signal proteins of the immune system - the cytokines - are also involved in modulation of behavior and induction of psychiatric symptoms. This article gives an overview on the nature of cytokines and the proposed mechanisms of immune-to-brain interaction. The role of cytokines in psychiatric symptoms, syndromes, and disorders like sickness behavior, major depression, and schizophrenia are discussed together with recent immunogenetic findings.
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Affiliation(s)
- Markus J Schwarz
- Psychiatric Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
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13
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Malignant hyperthermia susceptibility arising from altered resting coupling between the skeletal muscle L-type Ca2+ channel and the type 1 ryanodine receptor. Proc Natl Acad Sci U S A 2012; 109:7923-8. [PMID: 22547813 DOI: 10.1073/pnas.1119207109] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Malignant hyperthermia (MH) susceptibility is a dominantly inherited disorder in which volatile anesthetics trigger aberrant Ca(2+) release in skeletal muscle and a potentially fatal rise in perioperative body temperature. Mutations causing MH susceptibility have been identified in two proteins critical for excitation-contraction (EC) coupling, the type 1 ryanodine receptor (RyR1) and Ca(V)1.1, the principal subunit of the L-type Ca(2+) channel. All of the mutations that have been characterized previously augment EC coupling and/or increase the rate of L-type Ca(2+) entry. The Ca(V)1.1 mutation R174W associated with MH susceptibility occurs at the innermost basic residue of the IS4 voltage-sensing helix, a residue conserved among all Ca(V) channels [Carpenter D, et al. (2009) BMC Med Genet 10:104-115.]. To define the functional consequences of this mutation, we expressed it in dysgenic (Ca(V)1.1 null) myotubes. Unlike previously described MH-linked mutations in Ca(V)1.1, R174W ablated the L-type current and had no effect on EC coupling. Nonetheless, R174W increased sensitivity of Ca(2+) release to caffeine (used for MH diagnostic in vitro testing) and to volatile anesthetics. Moreover, in Ca(V)1.1 R174W-expressing myotubes, resting myoplasmic Ca(2+) levels were elevated, and sarcoplasmic reticulum (SR) stores were partially depleted, compared with myotubes expressing wild-type Ca(V)1.1. Our results indicate that Ca(V)1.1 functions not only to activate RyR1 during EC coupling, but also to suppress resting RyR1-mediated Ca(2+) leak from the SR, and that perturbation of Ca(V)1.1 negative regulation of RyR1 leak identifies a unique mechanism that can sensitize muscle cells to MH triggers.
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14
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Barrientos GC, Feng W, Truong K, Matthaei KI, Yang T, Allen PD, Lopez JR, Pessah IN. Gene dose influences cellular and calcium channel dysregulation in heterozygous and homozygous T4826I-RYR1 malignant hyperthermia-susceptible muscle. J Biol Chem 2011; 287:2863-76. [PMID: 22139840 DOI: 10.1074/jbc.m111.307926] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Malignant hyperthermia susceptibility (MHS) is primarily conferred by mutations within ryanodine receptor type 1 (RYR1). Here we address how the MHS mutation T4826I within the S4-S5 linker influences excitation-contraction coupling and resting myoplasmic Ca(2+) concentration ([Ca(2+)](rest)) in flexor digitorum brevis (FDB) and vastus lateralis prepared from heterozygous (Het) and homozygous (Hom) T4826I-RYR1 knock-in mice (Yuen, B. T., Boncompagni, S., Feng, W., Yang, T., Lopez, J. R., Matthaei, K. I., Goth, S. R., Protasi, F., Franzini-Armstrong, C., Allen, P. D., and Pessah, I. N. (2011) FASEB J. doi:22131268). FDB responses to electrical stimuli and acute halothane (0.1%, v/v) exposure showed a rank order of Hom ≫ Het ≫ WT. Release of Ca(2+) from the sarcoplasmic reticulum and Ca(2+) entry contributed to halothane-triggered increases in [Ca(2+)](rest) in Hom FDBs and elicited pronounced Ca(2+) oscillations in ∼30% of FDBs tested. Genotype contributed significantly elevated [Ca(2+)](rest) (Hom > Het > WT) measured in vivo using ion-selective microelectrodes. Het and Hom oxygen consumption rates measured in intact myotubes using the Seahorse Bioscience (Billerica, MA) flux analyzer and mitochondrial content measured with MitoTracker were lower than WT, whereas total cellular calpain activity was higher than WT. Muscle membranes did not differ in RYR1 expression nor in Ser(2844) phosphorylation among the genotypes. Single channel analysis showed highly divergent gating behavior with Hom and WT favoring open and closed states, respectively, whereas Het exhibited heterogeneous gating behaviors. [(3)H]Ryanodine binding analysis revealed a gene dose influence on binding density and regulation by Ca(2+), Mg(2+), and temperature. Pronounced abnormalities inherent in T4826I-RYR1 channels confer MHS and promote basal disturbances of excitation-contraction coupling, [Ca(2+)](rest), and oxygen consumption rates. Considering that both Het and Hom T4826I-RYR1 mice are viable, the remarkable isolated single channel dysfunction mediated through this mutation in S4-S5 cytoplasmic linker must be highly regulated in vivo.
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Affiliation(s)
- Genaro C Barrientos
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California 95616, USA
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15
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Orthograde dihydropyridine receptor signal regulates ryanodine receptor passive leak. Proc Natl Acad Sci U S A 2011; 108:7046-51. [PMID: 21482776 DOI: 10.1073/pnas.1018380108] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The skeletal muscle dihydropyridine receptor (DHPR) and ryanodine receptor (RyR1) are known to engage a form of conformation coupling essential for muscle contraction in response to depolarization, referred to as excitation-contraction coupling. Here we use WT and Ca(V)1.1 null (dysgenic) myotubes to provide evidence for an unexplored RyR1-DHPR interaction that regulates the transition of the RyR1 between gating and leak states. Using double-barreled Ca(2+)-selective microelectrodes, we demonstrate that the lack of Ca(V)1.1 expression was associated with an increased myoplasmic resting [Ca(2+)] ([Ca(2+)](rest)), increased resting sarcolemmal Ca(2+) entry, and decreased sarcoplasmic reticulum (SR) Ca(2+) loading. Pharmacological control of the RyR1 leak state, using bastadin 5, reverted the three parameters to WT levels. The fact that Ca(2+) sparks are not more frequent in dysgenic than in WT myotubes adds support to the hypothesis that the leak state is a conformation distinct from gating RyR1s. We conclude from these data that this orthograde DHPR-to-RyR1 signal inhibits the transition of gated RyR1s into the leak state. Further, it suggests that the DHPR-uncoupled RyR1 population in WT muscle has a higher propensity to be in the leak conformation. RyR1 leak functions are to keep [Ca(2+)](rest) and the SR Ca(2+) content in the physiological range and thus maintain normal intracellular Ca(2+) homeostasis.
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16
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Feng W, Barrientos GC, Cherednichenko G, Yang T, Padilla IT, Truong K, Allen PD, Lopez JR, Pessah IN. Functional and biochemical properties of ryanodine receptor type 1 channels from heterozygous R163C malignant hyperthermia-susceptible mice. Mol Pharmacol 2010; 79:420-31. [PMID: 21156754 DOI: 10.1124/mol.110.067959] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mutations in ryanodine receptor type 1 (RyR1) confer malignant hyperthermia susceptibility. How inherent impairments in Ca(2+) channel regulation affect skeletal muscle function in myotubes and adult fibers under basal (nontriggering) conditions are not understood. Myotubes, adult flexor digitorum brevis (FDB) fibers, and sarcoplasmic reticulum skeletal membranes were isolated from heterozygous knockin R163C and wild-type (WT) mice. Compared with WT myotubules, R163C myotubes have reduced Ca(2+) transient amplitudes in response to electrical field pulses; however, R163C FDB fibers do not differ in their responses to electrical stimuli, despite heightened cellular cytoplasmic resting Ca(2+) ([Ca(2+)](rest)) and sensitivity to halothane. Immunoblotting of membranes from each genotype shows similar expression of RyR1, FK506 binding protein 12 kDa, and Ca(2+)-ATPase, but RyR1 (2844)Ser phosphorylation in R163C muscle is 31% higher than that of WT muscle (p < 0.001). RyR1 channels reconstituted in planar lipid bilayers reveal ∼65% of R163C channels exhibit ≥2-fold greater open probability (P(o)) than WT, with prolonged mean open dwell times and shortened closed dwell times. [(3)H]Ryanodine (Ry) binding and single-channel analyses show that R163C-RyR1 has altered regulation compared with WT: 1) 3-fold higher sensitivity to Ca(2+) activation; 2) 2-fold greater [(3)H]Ry receptor occupancy; 3) comparatively higher channel activity, even in reducing glutathione buffer; 4) enhanced RyR1 activity both at 25 and 37°C; and 5) elevated cytoplasmic [Ca(2+)](rest). R163C channels are inherently more active than WT channels, a functional impairment that cannot be reversed by dephosphorylation with protein phosphatase. Dysregulated R163C channels produce a more overt phenotype in myotubes than in adult fibers in the absence of triggering agents, suggesting tighter negative regulation of R163C-RyR1 within the Ca(2+) release unit of adult fibers.
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Affiliation(s)
- Wei Feng
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
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17
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Eltit JM, Feng W, Lopez JR, Padilla IT, Pessah IN, Molinski TF, Fruen BR, Allen PD, Perez CF. Ablation of skeletal muscle triadin impairs FKBP12/RyR1 channel interactions essential for maintaining resting cytoplasmic Ca2+. J Biol Chem 2010; 285:38453-62. [PMID: 20926377 DOI: 10.1074/jbc.m110.164525] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previously, we have shown that lack of expression of triadins in skeletal muscle cells results in significant increase of myoplasmic resting free Ca(2+) ([Ca(2+)](rest)), suggesting a role for triadins in modulating global intracellular Ca(2+) homeostasis. To understand this mechanism, we study here how triadin alters [Ca(2+)](rest), Ca(2+) release, and Ca(2+) entry pathways using a combination of Ca(2+) microelectrodes, channels reconstituted in bilayer lipid membranes (BLM), Ca(2+), and Mn(2+) imaging analyses of myotubes and RyR1 channels obtained from triadin-null mice. Unlike WT cells, triadin-null myotubes had chronically elevated [Ca(2+)](rest) that was sensitive to inhibition with ryanodine, suggesting that triadin-null cells have increased basal RyR1 activity. Consistently, BLM studies indicate that, unlike WT-RyR1, triadin-null channels more frequently display atypical gating behavior with multiple and stable subconductance states. Accordingly, pulldown analysis and fluorescent FKBP12 binding studies in triadin-null muscles revealed a significant impairment of the FKBP12/RyR1 interaction. Mn(2+) quench rates under resting conditions indicate that triadin-null cells also have higher Ca(2+) entry rates and lower sarcoplasmic reticulum Ca(2+) load than WT cells. Overexpression of FKBP12.6 reverted the null phenotype, reducing resting Ca(2+) entry, recovering sarcoplasmic reticulum Ca(2+) content levels, and restoring near normal [Ca(2+)](rest). Exogenous FKBP12.6 also reduced the RyR1 channel P(o) but did not rescue subconductance behavior. In contrast, FKBP12 neither reduced P(o) nor recovered multiple subconductance gating. These data suggest that elevated [Ca(2+)](rest) in triadin-null myotubes is primarily driven by dysregulated RyR1 channel activity that results in part from impaired FKBP12/RyR1 functional interactions and a secondary increased Ca(2+) entry at rest.
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Affiliation(s)
- Jose M Eltit
- Department of Anesthesiology, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA
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18
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Eltit JM, Yang T, Li H, Molinski TF, Pessah IN, Allen PD, Lopez JR. RyR1-mediated Ca2+ leak and Ca2+ entry determine resting intracellular Ca2+ in skeletal myotubes. J Biol Chem 2010; 285:13781-7. [PMID: 20207743 DOI: 10.1074/jbc.m110.107300] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The control of resting free Ca(2+) in skeletal muscle is thought to be a balance of channels, pumps, and exchangers in both the sarcolemma and sarcoplasmic reticulum. We explored these mechanisms using pharmacologic and molecular perturbations of genetically engineered (dyspedic) muscle cells that constitutively lack expression of the skeletal muscle sarcoplasmic reticulum Ca(2+) release channels, RyR1 and RyR3. We demonstrate here that expression of RyR1 is responsible for more than half of total resting Ca(2+) concentration ([Ca(2+)](rest)) measured in wild type cells. The elevated [Ca(2+)](rest) in RyR1-expressing cells is not a result of active gating of the RyR1 channel but instead is accounted for by the RyR1 ryanodine-insensitive Ca(2+) leak conformation. In addition, we demonstrate that basal sarcolemmal Ca(2+) influx is also governed by RyR1 expression and contributes in the regulation of [Ca(2+)](rest) in skeletal myotubes.
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Affiliation(s)
- José M Eltit
- Department of Anesthesiology Perioperative and Pain Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA
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19
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Pessah IN, Cherednichenko G, Lein PJ. Minding the calcium store: Ryanodine receptor activation as a convergent mechanism of PCB toxicity. Pharmacol Ther 2010; 125:260-85. [PMID: 19931307 PMCID: PMC2823855 DOI: 10.1016/j.pharmthera.2009.10.009] [Citation(s) in RCA: 172] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Accepted: 10/30/2009] [Indexed: 11/24/2022]
Abstract
Chronic low-level polychlorinated biphenyl (PCB) exposures remain a significant public health concern since results from epidemiological studies indicate that PCB burden is associated with immune system dysfunction, cardiovascular disease, and impairment of the developing nervous system. Of these various adverse health effects, developmental neurotoxicity has emerged as a particularly vulnerable endpoint in PCB toxicity. Arguably the most pervasive biological effects of PCBs could be mediated by their ability to alter the spatial and temporal fidelity of Ca2+ signals through one or more receptor-mediated processes. This review will focus on our current knowledge of the structure and function of ryanodine receptors (RyRs) in muscle and nerve cells and how PCBs and related non-coplanar structures alter these functions. The molecular and cellular mechanisms by which non-coplanar PCBs and related structures alter local and global Ca2+ signaling properties and the possible short and long-term consequences of these perturbations on neurodevelopment and neurodegeneration are reviewed.
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Affiliation(s)
- Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
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20
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Lizák B, Csala M, Benedetti A, Bánhegyi G. The translocon and the non-specific transport of small molecules in the endoplasmic reticulum (Review). Mol Membr Biol 2009; 25:95-101. [DOI: 10.1080/09687680701670481] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Beáta Lizák
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
- the Pathobiochemistry Research Group of the Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary
| | - Miklós Csala
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
- the Pathobiochemistry Research Group of the Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary
| | - Angelo Benedetti
- Department of Pathophysiology, Experimental Medicine and Public Health, University of Siena, Siena, Italy
| | - Gábor Bánhegyi
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
- the Pathobiochemistry Research Group of the Hungarian Academy of Sciences, Semmelweis University, Budapest, Hungary
- Department of Pathophysiology, Experimental Medicine and Public Health, University of Siena, Siena, Italy
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21
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Murphy RM, Larkins NT, Mollica JP, Beard NA, Lamb GD. Calsequestrin content and SERCA determine normal and maximal Ca2+ storage levels in sarcoplasmic reticulum of fast- and slow-twitch fibres of rat. J Physiol 2008; 587:443-60. [PMID: 19029185 DOI: 10.1113/jphysiol.2008.163162] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Whilst calsequestrin (CSQ) is widely recognized as the primary Ca2+ buffer in the sarcoplasmic reticulum (SR) in skeletal muscle fibres, its total buffering capacity and importance have come into question. This study quantified the absolute amount of CSQ isoform 1 (CSQ1, the primary isoform) present in rat extensor digitorum longus (EDL) and soleus fibres, and related this to their endogenous and maximal SR Ca2+ content. Using Western blotting, the entire constituents of minute samples of muscle homogenates or segments of individual muscle fibres were compared with known amounts of purified CSQ1. The fidelity of the analysis was proven by examining the relative signal intensity when mixing muscle samples and purified CSQ1. The CSQ1 contents of EDL fibres, almost exclusively type II fibres, and soleus type I fibres [SOL (I)] were, respectively, 36 +/- 2 and 10 +/- 1 micromol (l fibre volume)(-1), quantitatively accounting for the maximal SR Ca2+ content of each. Soleus type II [SOL (II)] fibres (approximately 20% of soleus fibres) had an intermediate amount of CSQ1. Every SOL (I) fibre examined also contained some CSQ isoform 2 (CSQ2), which was absent in every EDL and other type II fibre except for trace amounts in one case. Every EDL and other type II fibre had a high density of SERCA1, the fast-twitch muscle sarco(endo)plasmic reticulum Ca2+-ATPase isoform, whereas there was virtually no SERCA1 in any SOL (I) fibre. Maximal SR Ca2+ content measured in skinned fibres increased with CSQ1 content, and the ratio of endogenous to maximal Ca2+ content was inversely correlated with CSQ1 content. The relative SR Ca2+ content that could be maintained in resting cytoplasmic conditions was found to be much lower in EDL fibres than in SOL (I) fibres (approximately 20 versus >60%). Leakage of Ca2+ from the SR in EDL fibres could be substantially reduced with a SR Ca2+ pump blocker and increased by adding creatine to buffer cytoplasmic [ADP] at a higher level, both results indicating that at least part of the Ca2+ leakage occurred through SERCA. It is concluded that CSQ1 plays an important role in EDL muscle fibres by providing a large total pool of releasable Ca2+ in the SR whilst maintaining free [Ca2+] in the SR at sufficiently low levels that Ca2+ leakage through the high density of SERCA1 pumps does not metabolically compromise muscle function.
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Affiliation(s)
- Robyn M Murphy
- Department of Zoology, La Trobe University, Melbourne, Victoria, Australia
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22
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Zieminska E, Lazarewicz JW, Couladouros EA, Moutsos VI, Pitsinos EN. Open-chain half-bastadins mimic the effects of cyclic bastadins on calcium homeostasis in cultured neurons. Bioorg Med Chem Lett 2008; 18:5734-7. [PMID: 18851910 DOI: 10.1016/j.bmcl.2008.09.080] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Revised: 09/22/2008] [Accepted: 09/23/2008] [Indexed: 12/24/2022]
Abstract
Constraining the catechol aryl ether moiety of bastadins by incorporation into a macrocyle is not necessary in order to mimic the effects of these marine natural products on neuronal calcium homeostasis. Simple, acyclic analogs that embody the 'western' or 'eastern' parts of bastadins were found to evoke comparable responses with bastadin 5.
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Affiliation(s)
- Elzbieta Zieminska
- Medical Research Centre, Polish Academy of Sciences, Pawinskiego 5, 02-106 Warsaw, Poland
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23
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Abstract
The rates of depression, anxiety, and sleep disturbance (suicide risk factors) are greater in patients with allergic rhinitis than in the general population. The rate of allergy is also greater in patients with depression. Preliminary data suggest that patients with a history of allergy may have an increased rate of suicide. Clinicians should actively inquire to diagnose allergy in patients with depression and depression in patients with allergy. Spring peaks of suicide are highly replicated, but their origin is poorly understood. Preliminary epidemiologic data suggest that seasonal spring peaks in aeroallergens are associated with seasonal spring peaks in suicide. Our research in Brown Norway rats demonstrates that sensitization and exposure to aeroallergens induces anxiety-like and aggressive behaviors as well as allergy-related helper T-cell type 2 (Th2) cytokine gene expression in the prefrontal cortex. Thus, it is possible that sensitization and exposure to aeroallergens, which peak in spring, may be conducive to seasonal exacerbation of suicide risk factors such as anxiety, depression, hostility/aggression, and sleep disturbance. Connecting allergy with suicide and suicide risk factors adds to previous neurologic literature connecting allergy with migraines and seizure disorders. Our recent report of Th2 (allergy-mediating) cytokine expression in the orbitofrontal cortex of suicide victims should lead to future studies to test the hypothesis that mediators of allergic inflammation in the nasal cavities may result in Th2 cytokine expression in the brain, influencing affect and behavioral modulation. Certain medications used to treat allergy can exacerbate suicide risk factors, potentially worsening suicide risk and even triggering suicide. Systemic (but not topical) corticosteroids have been associated with manic and depressive episodes and mixed mood states. Recently, the US Food and Drug Administration started investigating the possibility that montelukast may trigger suicide. Although this association requires further exploration and confirmation, clinicians should err on the side of caution, inquiring about past suicide attempts; hopelessness; reasons for living; and suicidal ideation, intent, or plan; and referring the patient to a mental health professional for evaluation if appropriate.
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Affiliation(s)
- Teodor T Postolache
- Teodor T. Postolache, MD Mood and Anxiety Program (MAP), Department of Psychiatry, University of Maryland School of Medicine, 685 West Baltimore Street, MSTF Building Room 930, Baltimore, MD 21201, USA.
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24
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Zieminska E, Stafiej A, Pitsinos EN, Couladouros EA, Moutsos V, Kozlowska H, Toczylowska B, Lazarewicz JW. Synthetic bastadins modify the activity of ryanodine receptors in cultured cerebellar granule cells. Neurosignals 2007; 15:283-92. [PMID: 17726341 DOI: 10.1159/000107650] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Accepted: 06/15/2007] [Indexed: 12/18/2022] Open
Abstract
Although the interactions of several natural bastadins with the RyR1 isoform of the ryanodine receptor in sarcoplasmic reticulum has been described, their structure-dependent interference with the RyR2 isoform, mainly expressed in cardiac muscle and brain neurons, has not been studied. In this work, we examined calcium transients induced by natural bastadin 10 and several synthetic bastadins in cultured cerebellar granule cells known to contain RyR2. The fluorescent calcium indicator fluo-3 and confocal microscopy were used to evaluate changes in the intracellular Ca(2+) concentration (Ca(i)), and the involvement of ryanodine receptors was assessed using pharmacological tools. Our results demonstrate that apart from the inactive BAST218F6 (a bisdebromo analogue of bastadin 10), synthetic bastadin 5, and synthetic analogues BAST217B, BAST240 and BAST268 (at concentrations >20 microM) increased Ca(i) in a concentration-dependent, ryanodine- and FK-506-sensitive way, with a potency significantly exceeding that of 20 mM caffeine. Moreover, the same active bastadins at a concentration of 5 muM in the presence of ryanodine prevented a thapsigargin-induced increase in Ca(i). These results indicate that bastadins, acting in a structure-dependent manner, modify the activity of RyR2 in primary neuronal culture and provide new information about structure-related pharmacological properties of bastadins.
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25
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Yang T, Esteve E, Pessah IN, Molinski TF, Allen PD, López JR. Elevated resting [Ca2+]iin myotubes expressing malignant hyperthermia RyR1 cDNAs is partially restored by modulation of passive calcium leak from the SR. Am J Physiol Cell Physiol 2007; 292:C1591-8. [PMID: 17182726 DOI: 10.1152/ajpcell.00133.2006] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Malignant hyperthermia (MH) is a pharmacogenetic disorder of skeletal muscle triggered in susceptible individuals by inhalation anesthetics and depolarizing skeletal muscle relaxants. This syndrome has been linked to a missense mutation in the type 1 ryanodine receptor (RyR1) in more than 50% of cases studied to date. Using double-barreled Ca2+microelectrodes in myotubes expressing wild-type RyR1 (WTRyR1) or RyR1 with one of four common MH mutations (MHRyR1), we measured resting intracellular Ca2+concentration ([Ca2+]i). Changes in resting [Ca2+]iproduced by several drugs known to modulate the RyR1 channel complex were investigated. We found that myotubes expressing any of theMHRyR1s had a 2.0- to 3.7-fold higher resting [Ca2+]ithan those expressingWTRyR1. Exposure of myotubes expressingMHRyR1s to ryanodine (500 μM) or (2,6-dichloro-4-aminophenyl)isopropylamine (FLA 365; 20 μM) had no effects on their resting [Ca2+]i. However, when myotubes were exposed to bastadin 5 alone or to a combination of ryanodine and bastadin 5, the resting [Ca2+]iwas significantly reduced ( P < 0.01). Interestingly, the percent decrease in resting [Ca2+]iin myotubes expressingMHRyR1s was significantly greater than that forWTRyR1. From these data, we propose that the high resting myoplasmic [Ca2+]iinMHRyR1 expressing myotubes is due in part to a related structural conformation ofMHRyR1s that favors “passive” calcium leak from the sarcoplasmic reticulum.
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Affiliation(s)
- Tianzhong Yang
- Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, 75 Francis St., Boston, MA 02115, USA
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van der Poel C, Stephenson DG. Effects of elevated physiological temperatures on sarcoplasmic reticulum function in mechanically skinned muscle fibers of the rat. Am J Physiol Cell Physiol 2007; 293:C133-41. [PMID: 17344316 DOI: 10.1152/ajpcell.00052.2007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Properties of the sarcoplasmic reticulum (SR) with respect to Ca(2+) loading and release were measured in mechanically skinned fiber preparations from isolated extensor digitorum longus (EDL) muscles of the rat that were either kept at room temperature (23 degrees C) or exposed to temperatures in the upper physiological range for mammalian skeletal muscle (30 min at 40 or 43 degrees C). The ability of the SR to accumulate Ca(2+) was significantly reduced by a factor of 1.9-2.1 after the temperature treatments due to a marked increase in SR Ca(2+) leak, which persisted for at least 3 h after treatment. Results with blockers of Ca(2+) release channels (ruthenium red) and SR Ca(2+) pumps [2,5-di(tert-butyl)-1,4-hydroquinone] indicate that the increased Ca(2+) leak was not through the SR Ca(2+) release channel or the SR Ca(2+) pump, although it is possible that the leak pathway was via oligomerized Ca(2+) pump molecules. No significant change in the maximum SR Ca(2+)-ATPase activity was observed after the temperature treatment, although there was a tendency for a decrease in the SR Ca(2+)-ATPase. The observed changes in SR properties were fully prevented by the superoxide (O(2)(*-)) scavenger Tiron (20 mM), indicating that the production of O(2)(*-) at elevated temperatures is responsible for the increase in SR Ca(2+) leak. Results show that physiologically relevant elevated temperatures 1) induce lasting changes in SR properties with respect to Ca(2+) handling that contribute to a marked increase in the SR Ca(2+) leak and, consequently, to the reduction in the average coupling ratio between Ca(2+) transport and SR Ca(2+)-ATPase and muscle performance, and 2) that these changes are mediated by temperature-induced O(2)(*-) production.
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Affiliation(s)
- C van der Poel
- Dept. of Zoology, La Trobe University, Victoria 3086, Australia
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Masuno MN, Pessah IN, Olmstead MM, Molinski TF. Simplified cyclic analogues of bastadin-5. Structure-activity relationships for modulation of the RyR1/FKBP12 Ca2+ channel complex. J Med Chem 2006; 49:4497-511. [PMID: 16854055 PMCID: PMC3987770 DOI: 10.1021/jm050708u] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bastadin-5, a brominated macro-dilactam from the marine sponge Ianthella basta, enhances release of Ca2+ from stores within the sarcoplasmic reticulum (SR) of muscle and nonmuscle cells by modulating RyR1/FKBP12 complex. Analogues of bastadin-5 present desirable targets for SAR studies to shed light on the gating mechanism and locus of bastadin-5 binding on these heteromeric channels that mediate essential steps in early coupling of membrane excitation to Ca2+ signaling cascades. Simple, ring-constrained analogues of bastadin-5 were synthesized from substituted benzaldehydes in a convergent manner, featuring an efficient S(N)Ar macroetherification, and evaluated in an assay that measures [3H]-ryanodine that is known to correlate with the functional open state of the Ca2+ channel. The simplified 14-membered ring, atropisomeric analogue (+/-)-7, like bastadin-5, enhanced ryanodine binding to the RyR1/FKBP12 complex (EC50 11 microM), however, unexpectedly, the corresponding achiral 18-membered ring analogue 14 potently inhibited binding (IC50 6 microM) under the same conditions. Structure-activity relationships of both families of cyclic analogues showed activity in a ryanodine binding assay that varied with substitutions of the Br atom on the trisubstituted aryl ring by various functional groups. The most active analogues were those that conserved the dibromocatechol ether moiety that corresponds to the 'western edge' of the bastadin-5 structure. These data suggest that cyclic analogues of bastadin-5 interact with the channel complex in a complex manner that can either enhance or inhibit channel activity.
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Couladouros EA, Pitsinos EN, Moutsos VI, Sarakinos G. A general method for the synthesis of bastaranes and isobastaranes: first total synthesis of bastadins 5, 10, 12, 16, 20, and 21. Chemistry 2006; 11:406-21. [PMID: 15562403 DOI: 10.1002/chem.200400904] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A general strategy for the synthesis of twenty naturally occurring bastadins (all but bastadin 3) is presented. A key retrosynthetic disconnection of the two amide bonds, common in all target molecules, bisects the macrocyclic core into two diaryl ether fragments, an alpha,omega-diamine (western part) and an alpha,omega-dicarboxylic acid (eastern part). Efficient preparation of the synthetically challenging o-mono or dibromo-substituted diaryl ether linkages was achieved employing the diaryl iodonium salt method. Regarding the western part, variations of the aliphatic chain were more efficiently secured by the preparation of two different alpha,omega-aminonitrile moieties. Cobalt boride mediated reduction of the nitrile functionality established the required diamines and, at the same time, provided the necessary variation of the aromatic-ring bromination pattern. Regarding the eastern part, two different dicarboxyl precursors had to be prepared in order to accommodate bromination-pattern variations. Coupling and subsequent macrolactamization of different combinations of these key intermediates may lead at will to any member of this family of marine natural products. Four bastaranes (bastadins 5, 10, 12 and 16) and two isobastaranes (bastadins 20 and 21) were synthesized as a demonstration of the flexibility and efficiency of the approach presented.
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Affiliation(s)
- Elias A Couladouros
- Chemistry Laboratories, Agricultural University of Athens, Iera Odos 75, GR 118 55 Athens, Greece.
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Aoki S, Cho SH, Ono M, Kuwano T, Nakao S, Kuwano M, Nakagawa S, Gao JQ, Mayumi T, Shibuya M, Kobayashi M. Bastadin 6, a spongean brominated tyrosine derivative, inhibits tumor angiogenesis by inducing selective apoptosis to endothelial cells. Anticancer Drugs 2006; 17:269-78. [PMID: 16520655 DOI: 10.1097/00001813-200603000-00005] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Bastadin 6, a macrocyclic tetramer of a brominated tyrosine derivative, was isolated from a marine sponge and its anti-angiogenic activity was evaluated. Bastadin 6 was found to inhibit vascular endothelial growth factor (VEGF)- or basic fibroblast growth factor (bFGF)-dependent proliferation (IC50=0.052 micromol/l) of human umbilical vein endothelial cells (HUVECs) 20- to 100-fold selectively in comparison with normal fibroblast (3Y1) or several tumor cells (KB3-1, K562 and Neuro2A). Bastadin 6 also inhibited VEGF- or bFGF-induced tubular formation (0.1 micromol/l, 6 h treatment) and VEGF-induced migration (1 micromol/l, 4 h treatment) of HUVECs. Moreover, bastadin 6 almost completely blocked VEGF- or bFGF-induced in vivo neovascularization in the mice corneal assay and suppressed growth of s.c. inoculated A431 solid tumor in nude mice (100 mg/kg, i.p.). Bastadin 6 induced cell death of HUVECs with an apoptotic phenotype, whereas it showed no effect on the VEGF-induced auto-phosphorylation of VEGF receptors Flt-1 and KDR/Flk-1. These results suggest that the anti-angiogenic effect of bastadin 6 is closely related to selective induction activity of apoptosis against endothelial cells.
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Affiliation(s)
- Shunji Aoki
- Graduate School of Pharmaceutical Sciences, Osaka University, Osaka, Japan
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30
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1-O-Sulfatobastadins-1 and -2 from Ianthella basta (Pallas).Antagonists of the yR1-FKBP12 Ca2+ Channel. Mar Drugs 2004. [DOI: 10.3390/md204176] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Alam MN, McGinty D, Bashir T, Kumar S, Imeri L, Opp MR, Szymusiak R. Interleukin-1beta modulates state-dependent discharge activity of preoptic area and basal forebrain neurons: role in sleep regulation. Eur J Neurosci 2004; 20:207-16. [PMID: 15245493 DOI: 10.1111/j.1460-9568.2004.03469.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Interleukin-1beta (IL-1) is a pro-inflammatory cytokine that has been implicated in the regulation of nonrapid eye movement (nonREM) sleep. IL-1, IL-1 receptors and the IL-1 receptor antagonist (ra) are present normally in discrete brain regions, including the preoptic area (POA) of the hypothalamus and the adjoining magnocellular basal forebrain (BF). The POA/BF have been implicated in the regulation of sleep-wakefulness. We hypothesized that IL-1 promotes nonREM sleep, in part by altering the state-dependent discharge activity of POA/BF neurons. We recorded the sleep-wake discharge profiles of 83 neurons in the lateral POA/BF and assessed the effects of IL-1, IL-1ra, and IL-ra + IL-1 delivered through a microdialysis probe on state-dependent neuronal discharge activity. IL-1 decreased the discharge rate of POA/BF neurons as a group (n = 55) but wake-related and sleep-related neurons responded differently. IL-1 significantly decreased the discharge rate of wake-related neurons. Of 24 wake-related neurons studied, 19 (79%) neurons exhibited a greater than 20% change in their discharge in the presence of IL-1 during waking. IL-1 suppressed the discharge activity of 18 of 19 responsive neurons. Of 13 sleep-related neurons studied, IL-1 increased the discharge activity of five and suppressed the discharge activity of four neurons. IL-1ra increased the discharge activity of four of nine neurons and significantly attenuated IL-1-induced effects on neuronal activity of POA/BF neurons (n = 19). These results suggest that the sleep-promoting effects of IL-1 may be mediated, in part, via the suppression of wake-related neurons and the activation of a subpopulation of sleep-related neurons in the POA/BF.
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Affiliation(s)
- Md Noor Alam
- Veteran Affairs Greater Los Angeles Health Care System, 16111 Plummer Street, North Hills, CA 91343, USA
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Cherednichenko G, Zima AV, Feng W, Schaefer S, Blatter LA, Pessah IN. NADH oxidase activity of rat cardiac sarcoplasmic reticulum regulates calcium-induced calcium release. Circ Res 2003; 94:478-86. [PMID: 14699012 DOI: 10.1161/01.res.0000115554.65513.7c] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
NADH and Ca2+ have important regulatory functions in cardiomyocytes related to excitation-contraction coupling and ATP production. To elucidate elements of these functions, we examined the effect of NADH on sarcoplasmic reticulum (SR) Ca2+ release and the mechanisms of this regulation. Physiological concentrations of cytosolic NADH inhibited ryanodine receptor type 2 (RyR2)-mediated Ca2+-induced Ca2+ release (CICR) from SR membranes (IC50=120 micromol/L) and significantly lowered single channel open probability. In permeabilized single ventricular cardiomyocytes, NADH significantly inhibited the amplitude and frequency of spontaneous Ca2+ release. Blockers of electron transport prevented the inhibitory effect of NADH on CICR in isolated membranes and permeabilized cells, as well as on the activity of RyR2 channels reconstituted in lipid bilayer. An endogenous NADH oxidase activity from rat heart copurified with SR enriched with RyR2. A significant contribution by mitochondria was excluded as NADH oxidation by SR exhibited >9-fold higher catalytic activity (8.8 micromol/mg protein per minute) in the absence of exogenous mitochondrial complex I (ubiquinone) or complex III (cytochrome c) electron acceptors, but was inhibited by rotenone and pyridaben (IC50=2 to 3 nmol/L), antimycin A (IC50=13 nmol/L), and diphenyleneiodonium (IC50=28 micromol/L). Cardiac junctional SR treated with [3H](trifluoromethyl)diazirinyl-pyridaben specifically labeled a single 23-kDa PSST-like protein. These data indicate that NADH oxidation is tightly linked to, and essential for, negative regulation of the RyR2 complex and is a likely component of an important physiological negative-feedback mechanism coupling SR Ca2+ fluxes and mitochondrial energy production.
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Affiliation(s)
- Gennady Cherednichenko
- Department of Molecular Biosciences, Northern California Health Care System, University of California, Davis, Calif 95616, USA
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Manfridi A, Brambilla D, Bianchi S, Mariotti M, Opp MR, Imeri L. Interleukin-1beta enhances non-rapid eye movement sleep when microinjected into the dorsal raphe nucleus and inhibits serotonergic neurons in vitro. Eur J Neurosci 2003; 18:1041-9. [PMID: 12956704 DOI: 10.1046/j.1460-9568.2003.02836.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Interleukin-1 (IL-1) and IL-1 receptors are constitutively expressed in normal brain. IL-1 increases non-rapid eye movements (NREM) sleep in several animal species, an effect mediated in part by interactions with the serotonergic system. The site(s) in brain at which interactions between IL-1 and the serotonergic system increase NREM sleep remain to be identified. The dorsal raphe (DRN) is the origin of the major ascending serotonergic pathways to the forebrain, and it contains IL-1 receptors. This study examined the hypothesis that IL-1 increases NREM sleep by acting at the level of the DRN. IL-1beta (0.25 and 0.5 ng) was microinjected into the DRN of freely behaving rats and subsequent effects on sleep-wake activity were determined. IL-1beta 0.5 ng increased NREM sleep during the first 2 h post-injection from 33.5 +/- 3.7% after vehicle microinjection to 42.9 +/- 3.0% of recording time. To determine the effects of IL-1beta on electrophysiological properties of DRN serotonergic neurons, intracellular recordings were performed in a guinea-pig brain stem slice preparation. In 26 of 32 physiologically and pharmacologically identified serotonergic neurons, IL-1beta superfusion (25 ng/mL) decreased spontaneous firing rates by 50%, from 1.6 +/- 0.2 Hz (before IL-1beta superfusion) to 0.8 +/- 0.2 Hz. This effect was reversible upon washout. These results show that IL-1beta increases NREM sleep when administered directly into the DRN. Serotonin enhances wakefulness and these novel data also suggest that IL-1beta-induced enhancement of NREM sleep could be due in part to the inhibition of DRN serotonergic neurons.
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Affiliation(s)
- Alfredo Manfridi
- Institute of Human Physiology II, 'Giuseppe Moruzzi' Centre for Experimental Sleep Research, Milano, Italy
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Yang T, Ta TA, Pessah IN, Allen PD. Functional defects in six ryanodine receptor isoform-1 (RyR1) mutations associated with malignant hyperthermia and their impact on skeletal excitation-contraction coupling. J Biol Chem 2003; 278:25722-30. [PMID: 12732639 DOI: 10.1074/jbc.m302165200] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Malignant hyperthermia (MH) is a potentially fatal pharmacogenetic disorder of skeletal muscle that segregates with >60 mutations within the MHS-1 locus on chromosome 19 coding for ryanodine receptor type 1 (RyR1). Although some MHRyR1s have been shown to enhance sensitivity to caffeine and halothane when expressed in non-muscle cells, their influence on EC coupling can only be studied in skeletal myotubes. We therefore expressed WTRyR1, six of the most common human MHRyR1s (R163C, G341R, R614C, R2163C, V2168M, and R2458H), and a newly identified C-terminal mutation (T4826I) in dyspedic myotubes to study their functional defects and how they influence EC coupling. Myotubes expressing any MHRyR1 were significantly more sensitive to stimulation by caffeine and 4-CmC than those expressing WTRyR1. The hypersensitivity of MH myotubes extended to K+ depolarization. MH myotubes responded to direct channel activators with maximum Ca2+ amplitudes consistently smaller than WT myotubes, whereas the amplitude of their responses to depolarization were consistently larger than WT myotubes. The magnitudes of responses attainable from myotubes expressing MHRyR1s are therefore related to the nature of the stimulus rather than size of the Ca2+ store. The functional changes of MHRyR1s were directly analyzed using [3H]ryanodine binding analysis of isolated myotube membranes. Although none of the MHRyR1s examined significantly altered EC50 for Ca2+ activation, many failed to be completely inhibited by a low Ca2+ (<or=100 nm), and all were significantly more responsive to caffeine than WTRyR1 at Ca2+ concentrations that approximate those in resting myotubes. All seven mutations had diminished sensitivity to inhibition by Ca2+ and Mg2+. Using a homologous expression system, our study demonstrates for the first time that these 7 MH mutations are all both necessary and sufficient to induce MH-related phenotypes. Decreased sensitivity to Ca2+ and Mg2+ inhibition and inability of MHRyR1s to be fully inactivated at [Ca2+]i typical of normal myotubes at rest are key defects that contribute to the initiation of MH episodes.
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Affiliation(s)
- Tianzhong Yang
- Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
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Chen L, Estève E, Sabatier JM, Ronjat M, De Waard M, Allen PD, Pessah IN. Maurocalcine and peptide A stabilize distinct subconductance states of ryanodine receptor type 1, revealing a proportional gating mechanism. J Biol Chem 2003; 278:16095-106. [PMID: 12586831 DOI: 10.1074/jbc.m209501200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Maurocalcine (MCa) isolated from Scorpio maurus palmatus venom shares 82% sequence identity with imperatoxin A. Both scorpion toxins are putative mimics of the II-III loop peptide (termed peptide A (pA)) of alpha(1s)-dihydropyridine receptor and are thought to act at a common site on ryanodine receptor type 1 (RyR1) important for skeletal muscle EC coupling. The relationship between the actions of synthetic MCa (sMCa) and pA on RyR1 were examined. sMCa released Ca(2+) from SR vesicles (EC(50) = 17.5 nm) in a manner inhibited by micromolar ryanodine or ruthenium red. pA (0.5-40 microm) failed to induce SR Ca(2+) release. Rather, pA enhanced Ca(2+) loading into SR and fully inhibited Ca(2+)-, caffeine-, and sMCa-induced Ca(2+) release. The two peptides modified single channel gating behavior in distinct ways. With Cs(+)-carrying current, 10 nm to 1 microm sMCa induced long lived subconductances having 48% of the characteristic full open state and occasional transitions to 29% at either positive or negative holding potentials. In contrast, pA stabilized long lived channel closures with occasional burst transitions to 65% (s1) and 86% (s2) of the full conductance. The actions of pA and sMCa were observed in tandem. sMCa stabilized additional subconductance states proportional to pA-induced subconductances (i.e. 43% of pA-modified s1 and s2 substates), revealing a proportional gating mechanism. [(3)H]Ryanodine binding and surface plasmon resonance analyses indicated that the peptides did not interact by simple competition for a single class of mutually exclusive sites on RyR1 to produce proportional gating. The actions of sMCa were also observed with ryanodine-modified channels and channels deficient in immunophilin 12-kDa FK506-binding protein. These results provide evidence that sMCa and pA stabilize distinct RyR1 channel states through distinct mechanisms that allosterically stabilize gating states having proportional conductance.
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Affiliation(s)
- Lili Chen
- Department of Molecular Biosciences and Graduate Program in Neurosciences, University of California, Davis, CA 95616, USA
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Lomax RB, Camello C, Van Coppenolle F, Petersen OH, Tepikin AV. Basal and physiological Ca(2+) leak from the endoplasmic reticulum of pancreatic acinar cells. Second messenger-activated channels and translocons. J Biol Chem 2002; 277:26479-85. [PMID: 11994289 DOI: 10.1074/jbc.m201845200] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have studied the Ca(2+) leak pathways in the endoplasmic reticulum of pancreatic acinar cells by directly measuring Ca(2+) in the endoplasmic reticulum ([Ca(2+)](ER)). Cytosolic Ca(2+) ([Ca(2+)](C)) was clamped to the resting level by a BAPTA-Ca(2+) mixture. Administration of cholecystokinin within the physiological concentration range caused a graded decrease of [Ca(2+)](ER), and the rate of Ca(2+) release generated by 10 pm cholecystokinin is at least 3x as fast as the basal Ca(2+) leak revealed by inhibition of the endoplasmic reticulum Ca(2+)-ATPase. Acetylcholine also evokes a dose-dependent decrease of [Ca(2+)](ER), with an EC(50) of 0.98 +/- 0.06 microm. Inhibition of receptors for inositol 1,4,5-trisphosphate (IP(3)) by heparin or flunarizine blocks the effect of acetylcholine but only partly blocks the effect of cholecystokinin. 8-NH(2) cyclic ADP-ribose (20 microm) inhibits the action of cholecystokinin, but not of acetylcholine(.) The basal Ca(2+) leak from the endoplasmic reticulum is not blocked by antagonists of the IP(3) receptor, the ryanodine receptor, or the receptor for nicotinic acid adenine dinucleotide phosphate. However, treatment with puromycin (0.1-1 mm) to remove nascent polypeptides from ribosomes increases Ca(2+) leak from the endoplasmic reticulum by a mechanism independent of the endoplasmic reticulum Ca(2+) pumps and of the receptors for IP(3) or ryanodine.
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Affiliation(s)
- Richard B Lomax
- Medical Research Council Secretory Control Research Group, The Physiological Laboratory, University of Liverpool, Liverpool L69 3BX, United Kingdom.
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Regioselective cationic reduction of 2-aryl-1-N-(ethoxycarbonyl)enamines to 2-arylethylamine carbamates. Tetrahedron Lett 2001. [DOI: 10.1016/s0040-4039(01)01780-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Yusufi AN, Cheng J, Thompson MA, Dousa TP, Warner GM, Walker HJ, Grande JP. cADP-ribose/ryanodine channel/Ca2+-release signal transduction pathway in mesangial cells. Am J Physiol Renal Physiol 2001; 281:F91-F102. [PMID: 11399650 DOI: 10.1152/ajprenal.2001.281.1.f91] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Signaling via release of Ca2+ from intracellular stores is mediated by several systems, including the inositol 1,4,5-trisphosphate (IP3) and cADP-ribose (cADPR) pathway. We recently discovered a high capacity for cADPR synthesis in rat glomeruli and cultured mesangial cells (MC). We sought to determine whether 1) cADPR synthesis in MC is regulated by cytokines and hormones, 2) ryanodine receptors (RyRs) are expressed in MC, and 3) Ca2+ is released through RyRs in response to cADPR. We found that ADP-ribosyl cyclase, a CD38-like enzyme that catalyzes cADPR synthesis, is upregulated in MC by tumor necrosis factor-alpha, interleukin-1beta, and all-trans retinoic acid (atRA). [3H]ryanodine binds to microsomal fractions from MC with high affinity in a Ca2+-dependent manner; binding is enhanced by specific RyR agonists and blocked by ruthenium red and cADPR. Western blot analysis confirmed the presence of RyR in MC. Release of 45Ca2+ from MC microsomes was stimulated by cADPR; release was blocked by ruthenium red and 8-bromo-cADPR. ADPR (non-cyclic) was without effect. In MC, TNF-alpha and atRA amplified the increment of cytoplasmic Ca2+ elicited by vasopressin. We conclude that MC possess elements of a novel ADP-ribosyl cyclase-->cADPR-->RyR-->Ca2+-release signaling pathway subject to regulation by proinflammatory cytokines and steroid superfamily hormones.
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Affiliation(s)
- A N Yusufi
- Renal Pathophysiology Laboratory, Department of Physiology and Biophysics, Mayo Clinic, Mayo Medical School, Rochester, Minnesota 55905, USA
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Abrenica B, Gilchrist JS. Nucleoplasmic Ca(2+)loading is regulated by mobilization of perinuclear Ca(2+). Cell Calcium 2000; 28:127-36. [PMID: 10970769 DOI: 10.1054/ceca.2000.0137] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Regulation of nucleoplasmic calcium (Ca(2+)) concentration may occur by the mobilization of perinuclear luminal Ca(2+)pools involving specific Ca(2+)pumps and channels of both inner and outer perinuclear membranes. To determine the role of perinuclear luminal Ca(2+), we examined freshly cultured 10 day-old embryonic chick ventricular cardiomyocytes. We obtained evidence suggesting the existence of the molecular machinery required for the bi-directional Ca(2+)fluxes using confocal imaging techniques. Embryonic cardiomyocytes were probed with antibodies specific for ryanodine-sensitive Ca(2+)channels (RyR2), sarco/endoplasmic reticulum Ca(2+)ATPase (SERCA2)-pumps, and fluorescent BODIPY derivatives of ryanodine and thapsigargin. Using immunocytochemistry techniques, confocal imaging showed the presence of RyR2 Ca(2+)channels and SERCA2-pumps highly localized to regions surrounding the nucleus, referable to the nuclear envelope. Results obtained from Fluo-3, AM loaded ionomycin-perforated embryonic cardiomyocytes demonstrated that gradual increases of extranuclear Ca(2+)from 100 to 1600 nM Ca(2+)was localized to the nucleus. SERCA2-pump inhibitors thapsigargin and cyclopiazonic acid showed a concentration-dependent inhibition of nuclear Ca(2+)loading. Furthermore, ryanodine demonstrated a biphasic concentration-dependence upon active nuclear Ca(2+)loading. The concomitant addition of thapsigargin or cyclopiazonic acid with ryanodine at inhibitory concentrations caused an significant increase in nuclear Ca(2+)loading at low concentrations of extranuclear added Ca(2+). Our results show that the perinuclear lumen in embryonic chick ventricular cardiomyocytes is capable of autonomously regulating nucleoplasmic Ca(2+)fluxes.
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Affiliation(s)
- B Abrenica
- Department of Oral Biology and Physiology, Division of Stroke and Vascular Disease, University of Manitoba, Winnipeg, Manitoba, Canada
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Chen L, Molinski TF, Pessah IN. Bastadin 10 stabilizes the open conformation of the ryanodine-sensitive Ca(2+) channel in an FKBP12-dependent manner. J Biol Chem 1999; 274:32603-12. [PMID: 10551814 DOI: 10.1074/jbc.274.46.32603] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The marine sponge Ianthella basta synthesizes at least 25 tetrameric bromotyrosine structures that possess a stringent structural requirement for modifying the gating behavior of ryanodine-sensitive Ca(2+) channels (ryanodine receptors) (RyR)). Bastadin 5 (B5) was shown to stabilize open and closed channel states with little influence on the sensitivity of the channel to activation by Ca(2+) (Mack, M. M., Molinski, T. F., Buck, E. D., and Pessah, I. N. (1994) J. Biol. Chem. 269, 23236-23249). In the present paper, we utilize single channel analysis and measurements of Ca(2+) flux across the sarcoplasmic reticulum to identify bastadin 10 (B10) as the structural congener responsible for dramatically stabilizing the open conformation of the RyR channel, possibly by reducing the free energy associated with closed to open channel transitions (DeltaG*c --> o). The stability of the channel open state induced by B10 sensitized the channel to activation by Ca(2+) to such an extent that it essentially obviated regulation by physiological concentrations of Ca(2+) and relieved inhibition by physiological Mg(2+). These actions of B10 were produced only on the cytoplasmic face of the channel, were selectively eliminated by pretreatment of channels with FK506 or rapamycin, and were reconstituted by human recombinant FKBP12. The actions of B10 were found to be reversible. A structure-activity model is proposed by which substitutions on the Eastern and Western hemispheres of the bastarane macrocycle may confer specificity toward the RyR1-FKBP12 complex to stabilize either the closed or open channel conformation. These results indicate that RyR1-FKBP12 complexes possesses a novel binding domain for phenoxycatechols and raise the possibility of molecular recognition of an endogenous ligand.
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Affiliation(s)
- L Chen
- Department of Molecular Biosciences, School of Veterinary Medicine, Graduate Program in Neuroscience, University of California, Davis, California 95616, USA
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43
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Abstract
We investigated the role of caffeine-sensitive intracellular stores in regulating intracellular calcium ([Ca(2+)](i)) and glutamatergic synaptic transmission from rod photoreceptors. Caffeine transiently elevated and then markedly depressed [Ca(2+)](i) to below prestimulus levels in rod inner segments and synaptic terminals. Concomitant with the depression was a reduction of glutamate release and a hyperpolarization of horizontal cells, neurons postsynaptic to rods. Caffeine did not affect the rods' membrane potentials indicating that caffeine likely acted via some mechanism(s) other than a voltage-dependent deactivation of the calcium channels. Most of caffeine's depressive action on [Ca(2+)](i), on glutamate release, and on I(Ca) in rods can be attributed to calcium release from stores: (1) caffeine's actions on [Ca(2+)](i) and I(Ca) were reduced by intracellular BAPTA and barium substitution for calcium, (2) other nonxanthine store-releasing compounds, such as thymol and chlorocresol, also depressed [Ca(2+)](i), and (3) the magnitude of [Ca(2+)](i) depression depended on basal [Ca(2+)](i) before caffeine. We propose that caffeine-released calcium reduces I(Ca) in rods by an as yet unidentified intracellular signaling mechanism. To account for the depression of [Ca(2+)](i) below rest levels and the increased fall rate of [Ca(2+)](i) with higher basal calcium, we also propose that caffeine-evoked calcium release from stores activates a calcium transporter that, via sequestration into stores or extrusion, lowers [Ca(2+)](i) and suppresses glutamate release. The effects of store-released calcium reported here operate at physiological calcium concentrations, supporting a role in regulating synaptic signaling in vivo.
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Lamb GD, Cellini MA. High intracellular [Ca2+] alters sarcoplasmic reticulum function in skinned skeletal muscle fibres of the rat. J Physiol 1999; 519 Pt 3:815-27. [PMID: 10457093 PMCID: PMC2269537 DOI: 10.1111/j.1469-7793.1999.0815n.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
1. The effect on sarcoplasmic reticulum (SR) function of exposure to high intracellular [Ca2+] was studied in mechanically skinned fibres from the extensor digitorum longus muscle of the rat, using caffeine to assay the SR Ca2+ content. 2. A 15 s exposure to 50 microM Ca2+ irreversibly reduced the ability of the SR to load/retain Ca2+ and completely abolished depolarization-induced Ca2+ release, whereas a 90 s exposure to 10 microM Ca2+ had no detectable effect on either function. The reduction in net SR Ca2+ uptake: (a) was near-maximal with treatment at 50 microM Ca2+, (b) was unrelated to voltage-sensor function, and (c) persisted unchanged for > 20 min. The reduction was primarily due to a threefold increase in leakage of Ca2+ out of the SR. This increased leakage was not substantially blocked by the presence of 10 mM Mg2+ or 2 microM Ruthenium Red. 3. The adverse effect on SR function of exposure to high [Ca2+] could also be observed by the reduction in the ability of the SR to maintain a low [Ca2+] within the skinned fibre in the face of elevated [Ca2+] in the bathing solution. When bathed in a solution with approximately 1.5 microM Ca2+ (0.75 mM CaEGTA-EGTA), skinned fibres produced only low force responses for many minutes, but after high [Ca2+] treatment (15 s exposure to 50 microM Ca2+) they showed large, steady or oscillatory force responses. 4. These findings indicate that, in addition to uncoupling the Ca2+ release channels from the voltage sensors, exposure of skinned fibres to high [Ca2+] causes a persistent increase in resting Ca2+ efflux from the SR. Such efflux in an intact fibre would alter the distribution of Ca2+ between the SR, the cytoplasm and the extracellular solution. These results may be relevant to the basis of low-frequency fatigue and possibly other conditions in muscle.
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Affiliation(s)
- G D Lamb
- Department of Zoology, La Trobe University, Bundoora, Victoria 3083, Australia.
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Couladouros EA, Moutsos VI. A general synthetic route towards bastadins. Part 1: Synthesis of the eastern part of bastadins 4–16. Tetrahedron Lett 1999. [DOI: 10.1016/s0040-4039(99)01429-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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46
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Ahern GP, Junankar PR, Pace SM, Curtis S, Mould JA, Dulhunty AF. Effects of ivermectin and midecamycin on ryanodine receptors and the Ca2+-ATPase in sarcoplasmic reticulum of rabbit and rat skeletal muscle. J Physiol 1999; 514 ( Pt 2):313-26. [PMID: 9852316 PMCID: PMC2269079 DOI: 10.1111/j.1469-7793.1999.313ae.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
1. Ryanodine receptor (RyR) Ca2+ channels in the sarcoplasmic reticulum (SR) of skeletal muscle are regulated by the 12 kDa FK506- (or rapamycin-) binding protein (FKBP12). Rapamycin can also activate RyR channels with FKBP12 removed, suggesting that compounds with macrocyclic lactone ring structures can directly activate RyRs. Here we tested this hypothesis using two other macrocyclic lactone compounds, ivermectin and midecamycin. 2. Rabbit skeletal RyRs were examined in lipid bilayers. Ivermectin (cis, 0.66-40 microM) activated six of eight native, four of four control-incubated and eleven of eleven FKBP12-'stripped' RyR channels. Midecamycin (cis, 10-30 microM) activated three of four single native channels, six of eight control-incubated channels and six of seven FKBP12-stripped channels. Activity declined when either drug was washed out. 3. Neither ivermectin nor midecamycin removed FKBP12 from RyRs. Western blots of terminal cisternae (TC), incubated for 15 min at 37 C with 40 microM ivermectin or midecamycin, showed normal amounts of FKBP12. In contrast, no FKBP12 was detected after incubation with 40 microM rapamycin. 4. Ivermectin reduced Ca2+ uptake by the SR Ca2+-Mg2+-ATPase. Ca2+ uptake by TC fell to approximately 40% in the presence of ivermectin (10 microM), both with and without 10 microM Ruthenium Red. Ca2+ uptake by longitudinal SR also fell to approximately 40% with 10 microM ivermectin. Midecamycin (10 microM) reduced Ca2+ uptake by TC vesicles to approximately 76% without Ruthenium Red and to approximately 90 % with Ruthenium Red. 5. The rate of rise of extravesicular [Ca2+] increased approximately 2-fold when 10 microM ivermectin was added to TC vesicles that had been partially loaded with Ca2+ and then Ca2+ uptake blocked by 200 nM thapsigargin. Ivermectin also potentiated caffeine-induced Ca2+ release to approximately 140% of control. These increases in Ca2+ release were not seen with midecamycin. 6. Ivermectin, but not midecamycin, reversibly reduced Ca2+ loading in four of six skinned rat extensor digitorum longus (EDL) fibres to approximately 90%, and reversibly increased submaximal caffeine-induced contraction in five of eight fibres by approximately 110% of control. Neither ivermectin nor midecamycin altered twitch or tetanic tension in intact EDL muscle fibres within 20 min of drug addition. 7. The results confirm the hypothesis that compounds with a macrocyclic lactone ring structure can directly activate RyRs. Unexpectedly, ivermectin also reduced Ca2+ uptake into the SR. These effects of ivermectin on SR Ca2+ handling may explain some effects of the macrolide drugs on mammals.
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Affiliation(s)
- G P Ahern
- Muscle Research Group, John Curtin School of Medical Research, PO Box 334, Canberra, ACT 2601, Australia
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Chen W, London R, Murphy E, Steenbergen C. Regulation of the Ca2+ gradient across the sarcoplasmic reticulum in perfused rabbit heart. A 19F nuclear magnetic resonance study. Circ Res 1998; 83:898-907. [PMID: 9797338 DOI: 10.1161/01.res.83.9.898] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Myocardial contractility depends on Ca2+ release from and uptake into the sarcoplasmic reticulum (SR). The Ca2+ gradient between the SR matrix and the cytosol (SR Ca2+ gradient) is maintained by the SR Ca2+-ATPase using the free energy available from hydrolysis of ATP. The activity of the SR Ca2+-ATPase is not only dependent on the energy state of the cell but is also kinetically regulated by SR proteins such as phospholamban. To evaluate the importance of thermodynamic and kinetic regulation of the SR Ca2+ gradient, we examined the relationship between the energy available from ATP hydrolysis (DeltaGATP) and the energy required for maintenance of the SR Ca2+ gradient (DeltaGCa2+SR) during physiological and pathological manipulations that alter DeltaGATP and the phosphorylation state of phospholamban. We used our previously developed 19F nuclear magnetic resonance method to measure the ionized [Ca2+] in the SR of Langendorff-perfused rabbit hearts. We found that addition of either pyruvate or isoproterenol resulted in an increase in left ventricular developed pressure and an increase in [Ca2+]SR. Pyruvate increased DeltaGATP, and the increase in the SR Ca2+ gradient was matched to the increase in DeltaGATP; DeltaGATP increased from 58.3+/-0.5 to 60.4+/-1.0 kJ/mol (P<0.05), and DeltaGCa2+SR increased from 47.1+/-0.3 to 48.5+/-0.1 kJ/mol (P<0.05). In contrast, the increase in the SR Ca2+ gradient in the presence of isoproterenol occurred despite a decline in DeltaGATP from 58. 3+/-0.5 to 55.8+/-0.6 kJ/mol. Thus, the data indicate that the SR Ca2+ gradient can be increased by an increase in DeltaGATP, and that the positive inotropic effect of pyruvate can be explained by improved energy-linked SR Ca2+ handling, whereas the results with isoproterenol are consistent with removal of the kinetic limitation of phospholamban on the activity of the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase, which allows the SR Ca2+ gradient to move closer to its thermodynamic limit. Ischemia decreases DeltaGATP, and this should also have an effect on SR Ca2+ handling. During 30 minutes of ischemia, DeltaGATP decreased by 12 kJ/mol, but the decrease in DeltaGCa2+SR was 16 kJ/mol, greater than would be predicted by the fall in DeltaGATP and consistent with increased SR Ca2+ release and increased SR Ca2+ cycling. Because ischemic preconditioning is reported to decrease SR Ca2+ cycling during a subsequent sustained period of ischemia, we examined whether ischemic preconditioning affects the relationship between the fall in DeltaGATP and the fall in DeltaGCa2+SR during ischemia. We found that preconditioning attenuated the fall in DeltaGCa2+SR during ischemia; the fall in DeltaGCa2+SR was of comparable magnitude to the fall in DeltaGATP, and this was associated with a significant improvement in functional recovery during reperfusion. The data suggest that there is both thermodynamic regulation of the SR Ca2+ gradient by DeltaGATP and kinetic regulation, which can alter the relationship between DeltaGATP and DeltaGCa2+SR.
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Affiliation(s)
- W Chen
- Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA
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48
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Gafni J, Munsch JA, Lam TH, Catlin MC, Costa LG, Molinski TF, Pessah IN. Xestospongins: potent membrane permeable blockers of the inositol 1,4,5-trisphosphate receptor. Neuron 1997; 19:723-33. [PMID: 9331361 DOI: 10.1016/s0896-6273(00)80384-0] [Citation(s) in RCA: 479] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Xestospongins (Xe's) A, C, D, araguspongine B, and demethylxestospongin B, a group of macrocyclic bis-1-oxaquinolizidines isolated from the Australian sponge, Xestospongia species, are shown to be potent blockers of IP3-mediated Ca2+ release from endoplasmic reticulum vesicles of rabbit cerebellum. XeC blocks IP3-induced Ca2+ release (IC50 = 358 nM) without interacting with the IP3-binding site, suggesting a mechanism that is independent of the IP3 effector site. Analysis of Pheochromocytoma cells and primary astrocytes loaded with Ca2+-sensitive dye reveals that XeC selectively blocks bradykinin- and carbamylcholine-induced Ca2+ efflux from endoplasmic reticulum stores. Xe's represent a new class of potent, membrane permeable IP3 receptor blockers exhibiting a high selectivity over ryanodine receptors. Xe's are a valuable tool for investigating the structure and function of IP3 receptors and Ca2+ signaling in neuronal and nonneuronal cells.
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Affiliation(s)
- J Gafni
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis 95616, USA
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Wong PW, Pessah IN. Noncoplanar PCB 95 alters microsomal calcium transport by an immunophilin FKBP12-dependent mechanism. Mol Pharmacol 1997; 51:693-702. [PMID: 9145907 DOI: 10.1124/mol.51.5.693] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Ortho-substituted polychlorinated biphenyls (PCBs) have been shown to alter microsomal Ca2+ transport by selective interaction with ryanodine receptors (RyRs) of muscle sarcoplasmic reticulum (SR) and brain endoplasmic reticulum. The mechanism underlying the actions of PCBs on Ca2+ transport is further elucidated with skeletal SR enriched in Ry1R. Disruption of the association between immunophilin FKBP12 and Ry1R with FK 506 or rapamycin completely eliminates PCB 95-enhanced binding of [3H]ryanodine (IC50 approximately 35 microM) to Ry1R and PCB 95-induced release of Ca2+ from actively loaded SR vesicles (IC50 approximately 11 microM), demonstrating a FKBP12-dependent mechanism. FK 506 selectively eliminates PCB 95-induced Ca2+ release from SR because Ry1R maintains responsiveness to caffeine and Ca2+. PCB 95 and FK 506 are used to examine the relationship between ryanodine-sensitive Ca2+ channels and ryanodine-insensitive Ca2+ leak pathways present in SR vesicles. Micromolar ryanodine completely blocks ryanodine-sensitive Ca2+ efflux but neither eliminates the ryanodine-insensitive Ca2+ leak unmasked by thapsigargin nor enhances the loading capacity of SR vesicles. PCB 95 alone enhances thapsigargin evoked Ca2+ release and therefore diminishes the loading capacity of SR vesicles. However, in the presence of micromolar ryanodine, PCB 95 dose-dependently eliminates the Ca2+ leak unmasked by thapsigargin and significantly enhances the loading capacity of SR vesicles. The actions of PCB 95 on SR-loading capacity are additive with those of FK 506. Structural specificity for these novel actions are further demonstrated with coplanar PCB 126, which is inactive toward Ry1R and lacks the ability to alter the Ca2+ leak pathway. The results reveal that FKBP12 relates ryanodine-insensitive Ca2+ "leak" and ryanodine-sensitive Ca2+ channel efflux pathways of SR by modulating distinct conformations Ry1R complexes. Noncoplanar PCBs, like PCB 95, alter SR Ca2+ buffering by an FKBP12-mediated mechanism. An immunophilin-based mechanism could account for the toxic actions attributed to certain noncoplanar PCB congeners.
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Affiliation(s)
- P W Wong
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis 95616, USA
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