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Shim SS, Berglund K, Yu SP. Lithium: An Old Drug for New Therapeutic Strategy for Alzheimer's Disease and Related Dementia. NEURODEGENER DIS 2023; 23:1-12. [PMID: 37666228 DOI: 10.1159/000533797] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 08/23/2023] [Indexed: 09/06/2023] Open
Abstract
BACKGROUND Although Alzheimer's disease (AD) is the most common form of dementia, the effective treatment of AD is not available currently. Multiple trials of drugs, which were developed based on the amyloid hypothesis of AD, have not been highly successful to improve cognitive and other symptoms in AD patients, suggesting that it is necessary to explore additional and alternative approaches for the disease-modifying treatment of AD. The diverse lines of evidence have revealed that lithium reduces amyloid and tau pathology, attenuates neuronal loss, enhances synaptic plasticity, and improves cognitive function. Clinical studies have shown that lithium reduces the risk of AD and deters the progress of mild cognitive impairment and early AD. SUMMARY Our recent study has revealed that lithium stabilizes disruptive calcium homeostasis, and subsequently, attenuates the downstream neuropathogenic processes of AD. Through these therapeutic actions, lithium produces therapeutic effects on AD with potential to modify the disease process. This review critically analyzed the preclinical and clinical studies for the therapeutic effects of lithium on AD. We suggest that disruptive calcium homeostasis is likely to be the early neuropathological mechanism of AD, and the stabilization of disruptive calcium homeostasis by lithium would be associated with its therapeutic effects on neuropathology and cognitive deficits in AD. KEY MESSAGES Lithium is likely to be efficacious for AD as a disease-modifying drug by acting on multiple neuropathological targets including disruptive calcium homeostasis.
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Affiliation(s)
- Seong Sool Shim
- Department of Psychiatry and Behavioral Sciences, Emory University School of Medicine, Atlanta, Georgia, USA
- Mental Health Service Line, Department of Veteran's Affair, Atlanta VA Medical Center, Decatur, Georgia, USA
- Department of Veteran's Affair, Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center, Decatur, Georgia, USA
| | - Ken Berglund
- Department of Veteran's Affair, Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center, Decatur, Georgia, USA
- Department of Neurosurgery, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Shan Ping Yu
- Department of Veteran's Affair, Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Medical Center, Decatur, Georgia, USA
- Department of Anesthesiology, Emory University School of Medicine, Atlanta, Georgia, USA
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2
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Hoare SRJ, Tewson PH, Quinn AM, Hughes TE, Bridge LJ. Analyzing kinetic signaling data for G-protein-coupled receptors. Sci Rep 2020; 10:12263. [PMID: 32704081 PMCID: PMC7378232 DOI: 10.1038/s41598-020-67844-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 06/15/2020] [Indexed: 02/07/2023] Open
Abstract
In classical pharmacology, bioassay data are fit to general equations (e.g. the dose response equation) to determine empirical drug parameters (e.g. EC50 and Emax), which are then used to calculate chemical parameters such as affinity and efficacy. Here we used a similar approach for kinetic, time course signaling data, to allow empirical and chemical definition of signaling by G-protein-coupled receptors in kinetic terms. Experimental data are analyzed using general time course equations (model-free approach) and mechanistic model equations (mechanistic approach) in the commonly-used curve-fitting program, GraphPad Prism. A literature survey indicated signaling time course data usually conform to one of four curve shapes: the straight line, association exponential curve, rise-and-fall to zero curve, and rise-and-fall to steady-state curve. In the model-free approach, the initial rate of signaling is quantified and this is done by curve-fitting to the whole time course, avoiding the need to select the linear part of the curve. It is shown that the four shapes are consistent with a mechanistic model of signaling, based on enzyme kinetics, with the shape defined by the regulation of signaling mechanisms (e.g. receptor desensitization, signal degradation). Signaling efficacy is the initial rate of signaling by agonist-occupied receptor (kτ), simply the rate of signal generation before it becomes affected by regulation mechanisms, measurable using the model-free analysis. Regulation of signaling parameters such as the receptor desensitization rate constant can be estimated if the mechanism is known. This study extends the empirical and mechanistic approach used in classical pharmacology to kinetic signaling data, facilitating optimization of new therapeutics in kinetic terms.
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Affiliation(s)
- Sam R J Hoare
- Pharmechanics, LLC, 14 Sunnyside Drive South, Owego, NY, 13827, USA.
| | - Paul H Tewson
- Montana Molecular, 366 Gallatin Park Dr. Suite A, Bozeman, MT, 59715, USA
| | - Anne Marie Quinn
- Montana Molecular, 366 Gallatin Park Dr. Suite A, Bozeman, MT, 59715, USA
| | - Thomas E Hughes
- Montana Molecular, 366 Gallatin Park Dr. Suite A, Bozeman, MT, 59715, USA
| | - Lloyd J Bridge
- Department of Engineering Design and Mathematics, University of the West of England, Frenchay Campus, Bristol, BS16 1QY, UK
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3
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Abstract
The multitudinous inositol phosphate family elicits a wide range of molecular effects that regulate countless biological responses. In this review, I provide a methodological viewpoint of the manner in which key advances in the field of inositol phosphate research were made. I also note some of the considerable challenges that still lie ahead.
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Affiliation(s)
- Stephen B Shears
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA.
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4
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A metabolic investigation of anticancer effect of G. glabra root extract on nasopharyngeal carcinoma cell line, C666-1. Mol Biol Rep 2019; 46:3857-3864. [DOI: 10.1007/s11033-019-04828-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 04/16/2019] [Indexed: 12/24/2022]
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5
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Lu Y, Wang L, Teng F, Zhang J, Hu M, Tao Y. Production of myo-inositol from glucose by a novel trienzymatic cascade of polyphosphate glucokinase, inositol 1-phosphate synthase and inositol monophosphatase. Enzyme Microb Technol 2018; 112:1-5. [DOI: 10.1016/j.enzmictec.2018.01.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 12/20/2017] [Accepted: 01/15/2018] [Indexed: 02/06/2023]
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6
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Dai M, Wang F, Zou Z, Xiao G, Chen H, Yang H. Metabolic regulations of a decoction of Hedyotis diffusa in acute liver injury of mouse models. Chin Med 2017; 12:35. [PMID: 29296119 PMCID: PMC5738817 DOI: 10.1186/s13020-017-0159-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 12/14/2017] [Indexed: 01/22/2023] Open
Abstract
Background Dysfunctional metabolisms are contributed to LPS/GALN-induced hepatitis. However, whether Hedyotis diffusa (HD) employs metabolic strategies against hepatitis is unknown. Methods We use the cytokines expression, levels of serum alanine transaminase and aspartate transaminase, survival and histological analysis to measure the effect of decoction of HD on acute severe hepatitis of mouse induced by LPS/GALN. Meanwhile, we utilize GC/MS-based metabolomics to characterize the variation of metabolomes. Results The present study shows the relieving liver damage in HD decoction-treated mice. Metabolic category using differential metabolites indicates the lower percentage of carbohydrates in LPS/GALN + HD group than LPS/GALN group, revealing the value of carbohydrate metabolism in HD decoction-administrated mouse liver. Further pathway enrichment analysis proposes that citrate cycle, galactose metabolism, and starch and sucrose metabolism are three important carbohydrate metabolisms that involve in the protective effect of decoction of HD during acute hepatitis. Furthermore, other important enrichment pathways are biosynthesis of unsaturated fatty acids, alanine, aspartate and glutamate metabolism, and arginine and proline metabolism. Fatty acids or amino acids involved in above-mentioned pathways are also detected in high loading distribution on IC01 and IC02, thereby manifesting the significance of these metabolites. Other key metabolites detect in ICA analysis were cholesterol, lactic acid and tryptophan. Conclusions The variation tendency of above-mentioned metabolites is totally consistent with the protective nature of decoction of HD. These findings give a viewpoint that HD decoction-effected metabolic strategies are linked to underlying mechanisms of decoction of HD and highlight the importance of metabolic mechanisms against hepatitis. Electronic supplementary material The online version of this article (10.1186/s13020-017-0159-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Min Dai
- Traditional Chinese Medicine Department, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510630 China
| | - Fenglin Wang
- Traditional Chinese Medicine Department, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510630 China
| | - Zengcheng Zou
- Traditional Chinese Medicine Department, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510630 China
| | - Gemin Xiao
- Traditional Chinese Medicine Department, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510630 China
| | - Hongjie Chen
- Traditional Chinese Medicine Department, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510630 China
| | - Hongzhi Yang
- Traditional Chinese Medicine Department, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510630 China
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7
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Yu W, Greenberg ML. Inositol depletion, GSK3 inhibition and bipolar disorder. FUTURE NEUROLOGY 2016; 11:135-148. [PMID: 29339929 DOI: 10.2217/fnl-2016-0003] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 03/04/2016] [Indexed: 12/31/2022]
Abstract
Valproic acid and lithium are widely used to treat bipolar disorder, a severe illness characterized by cycles of mania and depression. However, their efficacy is limited, and treatment is often accompanied by serious side effects. The therapeutic mechanisms of these drugs are not understood, hampering the development of more effective treatments. Among the plethora of biochemical effects of the drugs, those that are common to both may be more related to therapeutic efficacy. Two common outcomes include inositol depletion and GSK3 inhibition, which have been proposed to explain the efficacy of both valproic acid and lithium. Here, we discuss the inositol depletion and GSK3 inhibition hypotheses, and introduce a unified model suggesting that inositol depletion and GSK3 inhibition are inter-related.
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Affiliation(s)
- Wenxi Yu
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Miriam L Greenberg
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
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8
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Wenner MI, Maker GL, Dawson LF, Drummond PD, Mullaney I. The potential of metabolomic analysis techniques for the characterisation of α1-adrenergic receptors in cultured N1E-115 mouse neuroblastoma cells. Cytotechnology 2015; 68:1561-75. [PMID: 26408527 DOI: 10.1007/s10616-015-9915-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 09/03/2015] [Indexed: 10/23/2022] Open
Abstract
Several studies of neuropathic pain have linked abnormal adrenergic signalling to the development and maintenance of pain, although the mechanisms underlying this are not yet fully understood. Metabolomic analysis is a technique that can be used to give a snapshot of biochemical status, and can aid in the identification of the mechanisms behind pathological changes identified in cells, tissues and biological fluids. This study aimed to use gas chromatography-mass spectrometry-based metabolomic profiling in combination with reverse transcriptase-polymerase chain reaction and immunocytochemistry to identify functional α1-adrenergic receptors on cultured N1E-115 mouse neuroblastoma cells. The study was able to confirm the presence of mRNA for the α1D subtype, as well as protein expression of the α1-adrenergic receptor. Furthermore, metabolomic data revealed changes to the metabolite profile of cells when exposed to adrenergic pharmacological intervention. Agonist treatment with phenylephrine hydrochloride (10 µM) resulted in altered levels of several metabolites including myo-inositol, glucose, fructose, alanine, leucine, phenylalanine, valine, and n-acetylglutamic acid. Many of the changes observed in N1E-115 cells by agonist treatment were modulated by additional antagonist treatment (prazosin hydrochloride, 100 µM). A number of these changes reflected what is known about the biochemistry of α1-adrenergic receptor activation. This preliminary study therefore demonstrates the potential of metabolomic profiling to confirm the presence of functional receptors on cultured cells.
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Affiliation(s)
- Maria I Wenner
- School of Veterinary and Life Sciences, Murdoch University, Perth, WA, Australia
| | - Garth L Maker
- School of Veterinary and Life Sciences, Murdoch University, Perth, WA, Australia. .,Metabolomics Australia, Murdoch University, Perth, WA, Australia. .,Separation Science and Metabolomics Laboratory, Murdoch University, Perth, WA, Australia.
| | - Linda F Dawson
- School of Veterinary and Life Sciences, Murdoch University, Perth, WA, Australia.,School of Psychology and Exercise Science, Murdoch University, Perth, WA, Australia
| | - Peter D Drummond
- School of Psychology and Exercise Science, Murdoch University, Perth, WA, Australia
| | - Ian Mullaney
- School of Veterinary and Life Sciences, Murdoch University, Perth, WA, Australia
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9
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Chen XH, Zhang BW, Li H, Peng XX. Myo-inositol improves the host's ability to eliminate balofloxacin-resistant Escherichia coli. Sci Rep 2015; 5:10720. [PMID: 26030712 PMCID: PMC5377236 DOI: 10.1038/srep10720] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 04/29/2015] [Indexed: 12/11/2022] Open
Abstract
Antibiotic-resistant mechanisms are associated with fitness costs. However, why antibiotic-resistant bacteria usually show increasing adaptation to hosts is largely unknown, especially from the host's perspective. The present study reveals the host's varied response to balofloxacin-resistant Escherichia coli (BLFX-R) using an integrated proteome and metabolome approach and identifies myo-inositol and phagocytosis-related proteins as crucial biomarkers. Originally, macrophages have an optimal attractive preference to BLFX-S due to more polarization of BLFX-S than BLFX-R, which renders faster elimination to BLFX-S than BLFX-R. The slower elimination to BLFX-R may be reversed by exogenous myo-inositol. Primarily, myo-inositol depolarizes macrophages, elevating adherence to both BLFX-S and BLFX-R. Since the altered adherence is equal to both strains, the myo-inositol-treated macrophages are free of the barrier to BLFX-R and thereby promote phagocytosis of BLFX-R. This work provides a novel strategy based on metabolic modulation for eliminating antibiotic-resistant bacteria with a high degree of host adaptation.
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Affiliation(s)
- Xin-Hai Chen
- Center for Proteomics and Metabolomics, State Key Laboratory of Bio-Control, MOE Key Lab Aquat Food Safety, School of Life Sciences, Sun Yat-sen University, University City, Guangzhou 510006, People's Republic of China
| | - Bing-Wen Zhang
- 1] Center for Proteomics and Metabolomics, State Key Laboratory of Bio-Control, MOE Key Lab Aquat Food Safety, School of Life Sciences, Sun Yat-sen University, University City, Guangzhou 510006, People's Republic of China [2] Drug Discovery Pipeline, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, Guangdong, People's Republic of China
| | - Hui Li
- Center for Proteomics and Metabolomics, State Key Laboratory of Bio-Control, MOE Key Lab Aquat Food Safety, School of Life Sciences, Sun Yat-sen University, University City, Guangzhou 510006, People's Republic of China
| | - Xuan-Xian Peng
- Center for Proteomics and Metabolomics, State Key Laboratory of Bio-Control, MOE Key Lab Aquat Food Safety, School of Life Sciences, Sun Yat-sen University, University City, Guangzhou 510006, People's Republic of China
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10
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Wallace J. Calcium dysregulation, and lithium treatment to forestall Alzheimer's disease – a merging of hypotheses. Cell Calcium 2014; 55:175-81. [DOI: 10.1016/j.ceca.2014.02.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 01/20/2014] [Accepted: 02/05/2014] [Indexed: 12/20/2022]
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11
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Snyder RA, Bell CB, Diao Y, Krebs C, Bollinger JM, Solomon EI. Circular dichroism, magnetic circular dichroism, and variable temperature variable field magnetic circular dichroism studies of biferrous and mixed-valent myo-inositol oxygenase: insights into substrate activation of O2 reactivity. J Am Chem Soc 2013; 135:15851-63. [PMID: 24066857 DOI: 10.1021/ja406635k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
myo-Inositol oxygenase (MIOX) catalyzes the 4e(-) oxidation of myo-inositol (MI) to D-glucuronate using a substrate activated Fe(II)Fe(III) site. The biferrous and Fe(II)Fe(III) forms of MIOX were studied with circular dichroism (CD), magnetic circular dichroism (MCD), and variable temperature variable field (VTVH) MCD spectroscopies. The MCD spectrum of biferrous MIOX shows two ligand field (LF) transitions near 10000 cm(-1), split by ~2000 cm(-1), characteristic of six coordinate (6C) Fe(II) sites, indicating that the modest reactivity of the biferrous form toward O2 can be attributed to the saturated coordination of both irons. Upon oxidation to the Fe(II)Fe(III) state, MIOX shows two LF transitions in the ~10000 cm(-1) region, again implying a coordinatively saturated Fe(II) site. Upon MI binding, these split in energy to 5200 and 11200 cm(-1), showing that MI binding causes the Fe(II) to become coordinatively unsaturated. VTVH MCD magnetization curves of unbound and MI-bound Fe(II)Fe(III) forms show that upon substrate binding, the isotherms become more nested, requiring that the exchange coupling and ferrous zero-field splitting (ZFS) both decrease in magnitude. These results imply that MI binds to the ferric site, weakening the Fe(III)-μ-OH bond and strengthening the Fe(II)-μ-OH bond. This perturbation results in the release of a coordinated water from the Fe(II) that enables its O2 activation.
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Affiliation(s)
- Rae Ana Snyder
- Department of Chemistry, Stanford University , Stanford, California 94305, United States
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Lueke K, Kaiser T, Svetlitchny A, Welzel O, Wenzel EM, Tyagarajan S, Kornhuber J, Groemer TW. Basic presynaptic functions in hippocampal neurons are not affected by acute or chronic lithium treatment. J Neural Transm (Vienna) 2013; 121:211-9. [DOI: 10.1007/s00702-013-1087-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 08/27/2013] [Indexed: 01/27/2023]
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Wallace J. Treatment of trauma with lithium to forestall the development of posttraumatic stress disorder by pharmacological induction of a mild transient amnesia. Med Hypotheses 2013; 80:711-5. [PMID: 23490200 DOI: 10.1016/j.mehy.2013.02.017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 02/04/2013] [Accepted: 02/16/2013] [Indexed: 11/15/2022]
Abstract
Posttraumatic stress disorder (PTSD) is a severe anxiety disorder that develops after exposure to trauma. Symptoms include persistent reexperiencing, persistent avoidance, persistent numbing, and persistent hyperarousal. Subsequent to trauma exposure, the onset of symptoms of an acute stress reaction can typically develop over varying amounts of time from days to months. Current pharmacotherapies for PTSD are available after symptoms manifest, and primarily consist of selective serotonin reuptake inhibitor (SSRI) antidepressants. There are currently no FDA approved pharmacological interventions available for the treatment of acutely traumatized individuals to forestall the development of PTSD after trauma and prior to the onset of symptoms. A prominent model of PTSD developed by Roger Pitman attributes the pathogenesis of PTSD to over-consolidated traumatic memories that are mediated by endogenous stress hormones released with trauma and after trauma. The molecular processes of memory consolidation in neurons are mediated by intracellular signaling pathways. One secondary messenger signaling pathway with a putative role in long-term potentiation (LTP) is the inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG) secondary messenger system. Lithium, a treatment for bipolar disorder, and a pharmacotherapy that is associated with inducing transient impairments in cognition, memory, and learning, is an inhibitor of inositol monophosphatase (IMP), an enzyme in the IP3 and DAG secondary messenger pathway. I am advancing the hypothesis that the administration of lithium for a brief interval to traumatized individuals at risk for PTSD within the time period after trauma and prior to the onset of symptoms could potentially forestall the development of PTSD by disrupting LTP. I am proposing that this treatment will reduce the incidence of PTSD and reduce the severity of symptoms in those who eventually develop PTSD.
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Affiliation(s)
- James Wallace
- The Aging and Dementia Research Center, New York University School of Medicine, 145 East 32nd Street, New York, NY 10016, USA.
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Wang X, Hirao H. ONIOM (DFT:MM) Study of the Catalytic Mechanism of myo-Inositol Monophosphatase: Essential Role of Water in Enzyme Catalysis in the Two-Metal Mechanism. J Phys Chem B 2013; 117:833-42. [DOI: 10.1021/jp312483n] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Xiaoqing Wang
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore
637371
| | - Hajime Hirao
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore
637371
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Klein MT, Vinson PN, Niswender CM. Approaches for probing allosteric interactions at 7 transmembrane spanning receptors. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 115:1-59. [PMID: 23415091 PMCID: PMC5482179 DOI: 10.1016/b978-0-12-394587-7.00001-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In recent years, allosteric modulation of 7 transmembrane spanning receptors (7TMRs) has become a highly productive and exciting field of receptor pharmacology and drug discovery efforts. Positive and negative allosteric modulators (PAMs and NAMs, respectively) present a number of pharmacological and therapeutic advantages over conventional orthosteric ligands, including improved receptor-subtype selectivity, a lower propensity to induce receptor desensitization, the preservation of endogenous temporal and spatial activation of receptors, greater chemical flexibility for optimization of drug metabolism and pharmacokinetic parameters, and saturability of effect at target receptors, thus improving safety concerns and risk of overdose. Additionally, the relatively new concept of allosteric modulator-mediated receptor signal bias opens up a number of intriguing possibilities for PAMs, NAMs, and allosteric agonists, including the potential to selectively activate therapeutically beneficial signaling cascades, which could yield a superior tissue selectivity and side effect profile of allosteric modulators. However, there are a number of considerations and caveats that must be addressed when screening for and characterizing the properties of 7TMR allosteric modulators. Mode of pharmacology, methodology used to monitor receptor activity, detection of appropriate downstream analytes, selection of orthosteric probe, and assay time-course must all be considered when implementing any high-throughput screening campaign or when characterizing the properties of active compounds. Yet compared to conventional agonist/antagonist drug discovery programs, these elements of assay design are often a great deal more complicated when working with 7TMRs allosteric modulators. Moreover, for classical pharmacological methodologies and analyses, like radioligand binding and the assessment of compound affinity, the properties of allosteric modulators yield data that are more nuanced than orthosteric ligand-receptor interactions. In this review, we discuss the current methodologies being used to identify and characterize allosteric modulators, lending insight into the approaches that have been most successful in accurately and robustly identifying hit compounds. New label-free technologies capable of detecting phenotypic cellular changes in response to receptor activation are powerful tools well suited for assessing subtle or potentially masked cellular responses to allosteric modulation of 7TMRs. Allosteric modulator-induced receptor signal bias and the assay systems available to probe the various downstream signaling outcomes of receptor activation are also discussed.
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Affiliation(s)
- Michael T Klein
- Department of Pharmacology, Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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L-myo-inositol-1-phosphate synthase expressed in developing organ: isolation and characterisation of the enzyme from human fetal liver. Appl Biochem Biotechnol 2012; 167:2269-82. [PMID: 22707096 DOI: 10.1007/s12010-012-9767-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 06/04/2012] [Indexed: 10/28/2022]
Abstract
L-myo-inositol-1-phosphate synthase (MIPS; EC: 5.5.1.4) activity has been detected and partially purified for the first time from human fetal liver. Crude homogenate from the fetal liver was subjected to streptomycin sulphate precipitation and 0-60 % ammonium sulphate fractionation followed by successive chromatography through DEAE cellulose and BioGel A 0.5-m columns. After the final chromatography, the enzyme was purified 51-fold and 3.46 % of MIPS could be recovered. The human fetal liver MIPS specifically utilised D-glucose-6-phosphte and NAD(+) as its substrate and coenzyme, respectively. It shows pH optima between 7.0 and 7.5 while the temperature maximum was at 40 °C. The enzyme activity was remarkably stimulated by NH (4) (+) , slightly stimulated by K(+) and Ca(2+) and highly inhibited by Zn(2+), Cu(2+) and Hg(2+). The K (m) values of MIPS for D-glucose-6-phosphate and NAD(+) were found to be as 1.15 and 0.12 mM respectively while the V (max) values were 280 nM and 252 nM for D-glucose-6-phosphate and NAD(+) correspondingly. The apparent molecular weight of the native enzyme was determined to be 170 kDa.
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Quiroz JA, Machado-Vieira R, Zarate CA, Manji HK. Novel insights into lithium's mechanism of action: neurotrophic and neuroprotective effects. Neuropsychobiology 2010; 62:50-60. [PMID: 20453535 PMCID: PMC2889681 DOI: 10.1159/000314310] [Citation(s) in RCA: 131] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The monovalent cation lithium partially exerts its effects by activating neurotrophic and neuroprotective cellular cascades. Here, we discuss the effects of lithium on oxidative stress, programmed cell death (apoptosis), inflammation, glial dysfunction, neurotrophic factor functioning, excitotoxicity, and mitochondrial stability. In particular, we review evidence demonstrating the action of lithium on cyclic adenosine monophosphate (cAMP)-mediated signal transduction, cAMP response element binding activation, increased expression of brain-derived neurotrophic factor, the phosphatidylinositide cascade, protein kinase C inhibition, glycogen synthase kinase 3 inhibition, and B-cell lymphoma 2 expression. Notably, we also review data from clinical studies demonstrating neurotrophic effects of lithium. We expect that a better understanding of the clinically relevant pathophysiological targets of lithium will lead to improved treatments for those who suffer from mood as well as neurodegenerative disorders.
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Affiliation(s)
- Jorge A. Quiroz
- Hoffman-La Roche Inc., Pharma Development and Exploratory Neuroscience, Nutley, N.J
| | - Rodrigo Machado-Vieira
- Experimental Therapeutics, Mood and Anxiety Disorders Research Program, NIMH-NIH, Bethesda, Md
| | - Carlos A. Zarate
- Experimental Therapeutics, Mood and Anxiety Disorders Research Program, NIMH-NIH, Bethesda, Md
| | - Husseini K. Manji
- Johnson & Johnson Pharmaceutical Research and Development, L.L.C., Titusville, N.J., USA,*Husseini K. Manji, MD, FRCPC, Johnson & Johnson Pharmaceuticals Group, 1125 Trenton-Harbourton Road, E32000, Titusville, NJ 08560 (USA), Tel. +1 609 730 2968, Fax +1 609 730 2940, E-Mail
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Abstract
High performance liquid chromatography (HPLC) is an essential analytical tool in the study of the large number of inositol phosphate isomers. This chapter focuses on the separation of inositol polyphosphates from [(3)H]myo-inositol labeled tissues and cells. We review the different HPLC columns that have been used to separate inositol phosphates and their advantages and disadvantages. We describe important elements of sample preparation for effective separations and give examples of how changing factors, such as pH, can considerably improve the resolving ability of the HPLC chromatogram.
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Seelan RS, Lakshmanan J, Casanova MF, Parthasarathy RN. Identification of myo-inositol-3-phosphate synthase isoforms: characterization, expression, and putative role of a 16-kDa gamma(c) isoform. J Biol Chem 2009; 284:9443-57. [PMID: 19188364 PMCID: PMC2666597 DOI: 10.1074/jbc.m900206200] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2009] [Revised: 02/02/2009] [Indexed: 11/06/2022] Open
Abstract
Myo-inositol is an important constituent of membrane phospholipids and is a precursor for the phosphoinositide signaling pathway. It is synthesized from glucose 6-phosphate by myo-inositol-3-phosphate synthase (IP synthase), a homotrimer composed of a 68-kDa polypeptide in most mammalian tissues. It is a putative target for mood-stabilizing drugs such as lithium and valproate. Here, we show that the rat gene (Isyna1) encoding this enzyme generates a number of alternatively spliced transcripts in addition to the fully spliced form that encodes the 68-kDa subunit (the alpha isoform). Specifically, we identify a small 16-kDa subunit (the gamma(c) isoform) derived by an intron retention mechanism and provide evidence for its existence in rat tissues. The gamma(c) isoform is highly conserved in mammals, but it lacks the catalytic domain while retaining the NAD(+) binding domain. Both alpha and gamma(c) isoforms are predominantly expressed in many rat tissues and display apparent stoichiometry in purified enzyme preparations. An IP synthase polyclonal antibody not only detects the alpha and gamma(c) isoforms but also several other isoforms in pancreas, intestine, and testis suggesting that the holoenzyme is composed of unique subunits in various tissues. Interestingly, the alpha isoform is not expressed in the intestine. IP synthase activity assays using purified alpha and gamma(c) isoforms indicate that the latter negatively modulates alpha isoform activity, possibly by competing for NAD(+) molecules. Our findings have important ramifications for understanding the mood stabilization process and suggest that inositol biosynthesis is a highly regulated and dynamic process.
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Affiliation(s)
- Ratnam S Seelan
- Department of Psychiatry, University of Louisville, Louisville, Kentucky 40202, USA.
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Azab AN, Agam G, Kaplanski J, Delbar V, Greenberg ML. Inositol depletion: a good or bad outcome of valproate treatment? FUTURE NEUROLOGY 2008. [DOI: 10.2217/14796708.3.3.275] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Bipolar affective disorder is a severe and chronic disabling illness affecting 1.5% of the general population. Lithium, valproate and other mood stabilizers are used to treat bipolar disorder; however, these are ineffective for, and not tolerated by, a significant percentage of patients, underscoring the urgent need for better medications. Although not universally accepted, the inositol-depletion hypothesis is one of the main hypotheses suggested to explain the therapeutic mechanism of mood-stabilizing drugs. This paper reviews the relevance of the inositol-depletion hypothesis, paying special attention to the inhibition of inositol de novo synthesis by valproate. It also discusses inositol supplementation as a treatment strategy for multiple neurological disorders, including prophylactic use against valproate-induced neural tube defects.
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Affiliation(s)
- Abed N Azab
- Ben-Gurion University of the Negev, School for Community Health Professions, Faculty of Health Sciences, PO Box 653, Beer-Sheva 84105, Israel
| | - Galila Agam
- Ben-Gurion University of the Negev, Psychiatry Research Unit & Department of Clinical Biochemistry, Faculty of Health Sciences, PO Box 4600, Beer-Sheva 84170, Israel
| | - Jacob Kaplanski
- Ben-Gurion University of the Negev, Department of Clinical Pharmacology, Faculty of Health Sciences, PO Box 653, Beer-Sheva 84105, Israel
| | - Vered Delbar
- Ben-Gurion University of the Negev, School for Community Health Professions, Faculty of Health Sciences, PO Box 653, Beer-Sheva 84105, Israel
| | - Miriam L Greenberg
- Wayne State University, Department of Biological Sciences, Detroit, MI 48202, USA
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Gould TD, Einat H, O'Donnell KC, Picchini AM, Schloesser RJ, Manji HK. Beta-catenin overexpression in the mouse brain phenocopies lithium-sensitive behaviors. Neuropsychopharmacology 2007; 32:2173-83. [PMID: 17299510 DOI: 10.1038/sj.npp.1301338] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Lithium inhibits glycogen synthase kinase-3 (GSK-3) at therapeutic concentrations; however, it is unclear if this inhibition and its downstream effects on specific signaling pathways are relevant to the treatment of bipolar disorder and depression. One of the targets of GSK-3 is the transcription factor beta-catenin. Normally active GSK-3 phosphorylates beta-catenin, leading to its degradation. Inhibition of GSK-3 therefore increases beta-catenin. We have utilized transgenic mice to investigate the behavioral consequences of CNS beta-catenin overexpression. Transgenic mice overexpressing beta-catenin demonstrated behavioral changes similar to those observed following the administration of lithium, including decreased immobility time in the forced swim test (FST). Further, we show that although acute administration of lithium and overexpression of the beta-catenin transgene inhibits d-amphetamine-induced hyperlocomotion, neither lithium nor the beta-catenin transgene prevents d-amphetamine-induced sensitization, as measured by locomotor activity. Both lithium-treated and beta-catenin mice had an elevated response to d-amphetamine following multiple administrations of the stimulant, though the difference in absolute locomotion was maintained throughout the sensitization time-course. Neither acute lithium nor beta-catenin overexpression had an effect on d-amphetamine-induced stereotyped behavior. The results of this study, in which beta-catenin transgenic mice exhibited behaviors identical to those observed in lithium-treated mice, are consistent with the hypothesis that the behavioral effects of lithium in these models are mediated through its direct inhibition of GSK-3 and the consequent increase in beta-catenin. By associating the behavioral effects of lithium with beta-catenin levels, these data suggest that increasing beta-catenin might be a novel therapeutic strategy for mood disorders.
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Affiliation(s)
- Todd D Gould
- Laboratory of Molecular Pathophysiology, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892-3711, USA
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Bachmann RF, Schloesser RJ, Gould TD, Manji HK. Mood stabilizers target cellular plasticity and resilience cascades: implications for the development of novel therapeutics. Mol Neurobiol 2007; 32:173-202. [PMID: 16215281 DOI: 10.1385/mn:32:2:173] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Bipolar disorder is a devastating disease with a lifetime incidence of about 1% in the general population. Suicide is the cause of death in 10 to 15% of patients and in addition to suicide, mood disorders are associated with many other harmful health effects. Mood stabilizers are medications used to treat bipolar disorder. In addition to their therapeutic effects for the treatment of acute manic episodes, mood stabilizers are useful as prophylaxis against future episodes and as adjunctive antidepressant medications. The most established and investigated mood-stabilizing drugs are lithium and valproate but other anticonvulsants (such as carbamazepine and lamotrigine) and antipsychotics are also considered as mood stabilizers. Despite the efficacy of these diverse medications, their mechanisms of action remain, to a great extent, unknown. Lithium's inhibition of some enzymes, such as inositol monophosphatase and glycogen synthase kinase-3, probably results in its mood-stabilizing effects. Valproate may share its anticonvulsant target with its mood-stabilizing target or may act through other mechanisms. It has been shown that lithium, valproate, and/or carbamazepine regulate numerous factors involved in cell survival pathways, including cyclic adenine monophospate response element-binding protein, brain-derived neurotrophic factor, bcl-2, and mitogen-activated protein kinases. These drugs have been suggested to have neurotrophic and neuroprotective properties that ameliorate impairments of cellular plasticity and resilience underlying the pathophysiology of mood disorders. This article also discusses approaches to develop novel treatments specifically for bipolar disorder.
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Affiliation(s)
- Rosilla F Bachmann
- Laboratory of Molecular Pathophysiology, National Institute of Mental Health, Bethesda, MD, USA
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23
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Azab AN, Greenberg ML. Anticonvulsant efficacy of valproate-like carboxylic acids: a potential target for anti-bipolar therapy. Bipolar Disord 2007; 9:197-205. [PMID: 17430293 DOI: 10.1111/j.1399-5618.2007.00351.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Bipolar disorder (BPD) is a severe and chronic illness, with a lifetime prevalence of approximately 1.5%. Despite the availability of some mood stabilizing drugs including lithium, valproate (valproic acid), lamotrigine and carbamazepine, BPD is characterized by high rates of recurrence, as treatment with these and other drugs is ineffective for and not well-tolerated by a significant percentage of patients. Most drugs currently used for the maintenance treatment of BPD are anticonvulsants (e.g., valproate, carbamazepine and lamotrigine). OBJECTIVES The aim of this paper is to review the studies characterizing the anticonvulsant efficacy of valproate-like carboxylic acids and related compounds, some of which may have potential for the treatment of manic-depressive illness. RESULTS The data reviewed herein demonstrate clearly that some dietary fatty acids and other valproate-like carboxylic acids exhibit potent anticonvulsant activity, and may thus be candidates for mood stabilizing treatment options for BPD.
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Affiliation(s)
- Abed N Azab
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
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24
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O'Donnell KC, Gould TD. The behavioral actions of lithium in rodent models: leads to develop novel therapeutics. Neurosci Biobehav Rev 2007; 31:932-62. [PMID: 17532044 PMCID: PMC2150568 DOI: 10.1016/j.neubiorev.2007.04.002] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2006] [Revised: 03/27/2007] [Indexed: 12/13/2022]
Abstract
For nearly as long as lithium has been in clinical use for the treatment of bipolar disorder, depression, and other conditions, investigators have attempted to characterize its effects on behaviors in rodents. Lithium consistently decreases exploratory activity, rearing, aggression, and amphetamine-induced hyperlocomotion; and it increases the sensitivity to pilocarpine-induced seizures, decreases immobility time in the forced swim test, and attenuates reserpine-induced hypolocomotion. Lithium also predictably induces conditioned taste aversion and alterations in circadian rhythms. The modulation of stereotypy, sensitization, and reward behavior are less consistent actions of the drug. These behavioral models may be relevant to human symptoms and to clinical endophenotypes. It is likely that the actions of lithium in a subset of these animal models are related to the therapeutic efficacy, as well the side effects, of the drug. We conclude with a brief discussion of various molecular mechanisms by which these lithium-sensitive behaviors may be mediated, and comment on the ways in which rat and mouse models can be used more effectively in the future to address persistent questions about the therapeutically relevant molecular actions of lithium.
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Affiliation(s)
- Kelley C O'Donnell
- The Laboratory of Molecular Pathophysiology, Mood and Anxiety Disorders Program, National Institute of Mental Health, NIH, HHS, Bldg 35, Rm 1C-912, 35 Convent Drive, Bethesda, MD 20892 3711, USA
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25
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Parthasarathy LK, Seelan RS, Tobias C, Casanova MF, Parthasarathy RN. Mammalian inositol 3-phosphate synthase: its role in the biosynthesis of brain inositol and its clinical use as a psychoactive agent. Subcell Biochem 2006; 39:293-314. [PMID: 17121280 DOI: 10.1007/0-387-27600-9_12] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Affiliation(s)
- Latha K Parthasarathy
- Molecular Neuroscience Laboratory, Autism Research Unit, Mental Health, Behavioral Science and Research Services, VA Medical Center (151), Louisville, Kentucky 40206, USA
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26
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Azab AN, Greenberg ML. Lipid connection to bipolar disorder. FUTURE NEUROLOGY 2006. [DOI: 10.2217/14796708.1.4.505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Bipolar disorder is a severe and chronic illness affecting approximately 1.5% of the American population. Despite the availability of mood bipolarstabilizers such as lithium, valproate, carbamazepine and lamotrigine, bipolar disorder is characterized by high rates of recurrence, as treatment with these and other drugs is ineffective for and not tolerated by a significant percentage of patients. Several hypotheses have been postulated to explain the mechanism(s) of action of mood stabilizers. However, the biological and molecular bases of the disease are not fully understood, hampering the development of more effective and safer drugs. A large body of evidence associates lipids (cholesterol, phospholipids and fatty acids) with the mechanism and pathology of bipolar disorder. The purpose of this paper is to review the lipid connection to bipolar disorder.
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Affiliation(s)
- Abed N Azab
- Wayne State University, Department of Biological Sciences, Detroit, MI 48202, USA
| | - Miriam L Greenberg
- Wayne State University, Department of Biological Sciences, Detroit, MI 48202, USA
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27
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Shi Y, Azab AN, Thompson MN, Greenberg ML. Inositol phosphates and phosphoinositides in health and disease. Subcell Biochem 2006; 39:265-92. [PMID: 17121279 DOI: 10.1007/0-387-27600-9_11] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
In the past two decades, considerable progress has been made toward understanding inositol phosphates and PI metabolism. However, there is still much to learn. The present challenge is to understand how inositol phosphates and PIs are compartmentalized, identify new targets of inositol phosphates and PIs, and elucidate the mechanisms underlying spatial and temporal regulation of the enzymes that metabolize inositol phosphates and PIs. Answers to these questions will help clarify the mechanisms of the diseases associated with these molecules and identify new possibilities for drug design.
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Affiliation(s)
- Yihui Shi
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
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28
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Abstract
Inositol, a simple six-carbon sugar, forms the basis of a number of important intracellular signaling molecules. Over the last 35 years, a series of biochemical and cell biological experiments have shown that lithium (Li(+)) reduces the cellular concentration of myo-inositol and as a consequence attenuates signaling within the cell. Based on these observations, inositol-depletion was proposed as a therapeutic mechanism in the treatment of bipolar mood disorder. Recent results have added significant new dimensions to the original hypothesis. However, despite a number of clinical studies, this hypothesis still remains to be either proven or refuted. In this review of our current knowledge, I will consider where the inositol-depletion hypothesis stands today and how it may be further investigated in the future.
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Affiliation(s)
- A J Harwood
- MRC Laboratory for Molecular Biology, Department of Biology, University College London, London, UK.
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29
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Gould TD, Quiroz JA, Singh J, Zarate CA, Manji HK. Emerging experimental therapeutics for bipolar disorder: insights from the molecular and cellular actions of current mood stabilizers. Mol Psychiatry 2004; 9:734-55. [PMID: 15136794 DOI: 10.1038/sj.mp.4001518] [Citation(s) in RCA: 165] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Bipolar disorder afflicts approximately 1-3% of both men and women, and is coincident with major economic, societal, medical, and interpersonal consequences. Current mediations used for its treatment are associated with variable rates of efficacy and often intolerable side effects. While preclinical and clinical knowledge in the neurosciences has expanded at a tremendous rate, recent years have seen no major breakthroughs in the development of novel types of treatment for bipolar disorder. We review here approaches to develop novel treatments specifically for bipolar disorder. Deliberate (ie not by serendipity) treatments may come from one of two general mechanisms: (1) Understanding the mechanism of action of current medications and thereafter designing novel drugs that mimics these mechanism(s); (2) Basing medication development upon the hypothetical or proven underlying pathophysiology of bipolar disorder. In this review, we focus upon the first approach. Molecular and cellular targets of current mood stabilizers include lithium inhibitable enzymes where lithium competes for a magnesium binding site (inositol monophosphatase, inositol polyphosphate 1-phosphatase, glycogen synthase kinase-3 (GSK-3), fructose 1,6-bisphosphatase, bisphosphate nucleotidase, phosphoglucomutase), valproate inhibitable enzymes (succinate semialdehyde dehydrogenase, succinate semialdehyde reductase, histone deacetylase), targets of carbamazepine (sodium channels, adenosine receptors, adenylate cyclase), and signaling pathways regulated by multiple drugs of different classes (phosphoinositol/protein kinase C, cyclic AMP, arachidonic acid, neurotrophic pathways). While the task of developing novel medications for bipolar disorder is truly daunting, we are hopeful that understanding the mechanism of action of current mood stabilizers will ultimately lead clinical trials with more specific medications and thus better treatments those who suffer from this devastating illness.
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Affiliation(s)
- T D Gould
- Laboratory of Molecular Pathophysiology, National Institute of Mental Health, Bethesda, MD 20892, USA
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30
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Saul D, Fabian L, Forer A, Brill JA. Continuous phosphatidylinositol metabolism is required for cleavage of crane fly spermatocytes. J Cell Sci 2004; 117:3887-96. [PMID: 15265984 DOI: 10.1242/jcs.01236] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Successful cleavage of animal cells requires co-ordinated regulation of the actomyosin contractile ring and cleavage furrow ingression. Data from a variety of systems implicate phosphoinositol lipids and calcium release as potential regulators of this fundamental process. Here we examine the requirement for various steps of the phosphatidylinositol (PtdIns) cycle in dividing crane fly (Nephrotoma suturalis) spermatocytes. PtdIns cycle inhibitors were added to living cells after cleavage furrows formed and began to ingress. Inhibitors known to block PtdIns recycling (lithium), PtdIns phosphorylation (wortmannin, LY294002) or phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] hydrolysis [U73122 (U7)] all stopped or slowed furrowing. The effect of these drugs on cytokinesis was quite rapid (within 0-4 minutes), so continuous metabolism of PtdIns appears to be required for continued cleavage furrow ingression. U7 caused cleavage furrow regression concomitant with depletion of F-actin from the contractile ring, whereas the other inhibitors caused neither regression nor depletion of F-actin. That U7 depletes furrow-associated actin seems counterintuitive, as inhibition of phospholipase C would be expected to increase cellular levels of PtdIns(4,5)P2 and hence increase actin polymerization. Our confocal images suggest, however, that F-actin might accumulate at the poles of U7-treated cells, consistent with the idea that PtdIns(4,5)P2 hydrolysis may be required for actin filaments formed at the poles to participate in contractile ring assembly at the furrow.
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Affiliation(s)
- Daniel Saul
- Department of Biology, York University, 4700 Keele Street, Toronto, Ontario, M3J 1P3, Canada
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31
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Ju S, Shaltiel G, Shamir A, Agam G, Greenberg ML. Human 1-D-myo-Inositol-3-phosphate Synthase Is Functional in Yeast. J Biol Chem 2004; 279:21759-65. [PMID: 15024000 DOI: 10.1074/jbc.m312078200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have cloned, sequenced, and expressed a human cDNA encoding 1-d-myo-inositol-3-phosphate (MIP) synthase (hINO1). The encoded 62-kDa human enzyme converted d-glucose 6-phosphate to 1-d-myo-inositol 3-phosphate, the rate-limiting step for de novo inositol biosynthesis. Activity of the recombinant human MIP synthase purified from Escherichia coli was optimal at pH 8.0 at 37 degrees C and exhibited K(m) values of 0.57 mm and 8 microm for glucose 6-phosphate and NAD(+), respectively. NH(4)(+) and K(+) were better activators than other cations tested (Na(+), Li(+), Mg(2+), Mn(2+)), and Zn(2+) strongly inhibited activity. Expression of the protein in the yeast ino1Delta mutant lacking MIP synthase (ino1Delta/hINO1) complemented the inositol auxotrophy of the mutant and led to inositol excretion. MIP synthase activity and intracellular inositol were decreased about 35 and 25%, respectively, when ino1Delta/hINO1 was grown in the presence of a therapeutically relevant concentration of the anti-bipolar drug valproate (0.6 mm). However, in vitro activity of purified MIP synthase was not inhibited by valproate at this concentration, suggesting that inhibition by the drug is indirect. Because inositol metabolism may play a key role in the etiology and treatment of bipolar illness, functional conservation of the key enzyme in inositol biosynthesis underscores the power of the yeast model in studies of this disorder.
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Affiliation(s)
- Shulin Ju
- Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202, USA
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32
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Guan G, Dai P, Shechter I. cDNA cloning and gene expression analysis of human myo-inositol 1-phosphate synthase. Arch Biochem Biophys 2003; 417:251-9. [PMID: 12941308 DOI: 10.1016/s0003-9861(03)00388-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
myo-Inositol 1-phosphate synthase (EC 5.5.1.4) (IPS) is a key enzyme in myo-inositol biosynthesis pathway. This study describes the molecular cloning of the full length human myo-inositol 1-phosphate synthase (hIPS) cDNA, tissue distribution of its mRNA and characterizes its gene expression in cultured HepG2 cells. Human testis, ovary, heart, placenta, and pancreas express relatively high level of hIPS mRNA, while blood leukocyte, thymus, skeletal muscle, and colon express low or marginal amount of the mRNA. In the presence of glucose, hIPS mRNA level increases 2- to 4-fold in HepG2 cells. hIPS mRNA is also up-regulated 2- to 3-fold by 2.5 microM lovastain. This up-regulation is prevented by mevalonic acid, farnesol, and geranylgeraniol, suggesting a G-protein mediated signal transduction mechanism in the regulation of hIPS gene expression. hIPS mRNA expression is 50% suppressed by 10mM lithium ion in these cells. Neither 5mM myo-inositol nor the three hormones: estrogen, thyroid hormone, and insulin altered hIPS mRNA expression in these cells.
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Affiliation(s)
- Guimin Guan
- Department of Surgery, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, USA
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Abstract
Mood stabilizers represent a class of drugs that are efficacious in the treatment of bipolar disorder. The most established medications in this class are lithium, valproic acid, and carbamazepine. In addition to their therapeutic effects for treatment of acute manic episodes, these medications often are useful as prophylaxis against future episodes and as adjunctive antidepressant medications. While important extracellular effects have not been excluded, most available evidence suggests that the therapeutically relevant targets of this class of medications are in the interior of cells. Herein we give a prospective of a rapidly evolving field, discussing common effects of mood stabilizers as well as effects that are unique to individual medications. Mood stabilizers have been shown to modulate the activity of enzymes, ion channels, arachidonic acid turnover, G protein coupled receptors and intracellular pathways involved in synaptic plasticity and neuroprotection. Understanding the therapeutic targets of mood stabilizers will undoubtedly lead to a better understanding of the pathophysiology of bipolar disorder and to the development of improved therapeutics for the treatment of this disease. Furthermore, the involvement of mood stabilizers in pathways operative in neuroprotection suggests that they may have utility in the treatment of classical neurodegenerative disorders.
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Affiliation(s)
- Todd D. Gould
- Laboratory of Molecular Pathophysiology, Building 49, Room B1EE16, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Guang Chen
- Laboratory of Molecular Pathophysiology, Building 49, Room B1EE16, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
| | - Husseini K. Manji
- Laboratory of Molecular Pathophysiology, Building 49, Room B1EE16, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
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34
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Mehta DV, Kabir A, Bhat PJ. Expression of human inositol monophosphatase suppresses galactose toxicity in Saccharomyces cerevisiae: possible implications in galactosemia. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1454:217-26. [PMID: 10452956 DOI: 10.1016/s0925-4439(99)00037-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A suppressor of galactose toxicity in a gal7 yeast strain (lacking galactose 1-phosphate uridyl transferase) has been isolated from a HeLa cell cDNA library. Analysis of the plasmid clone indicated that the insert has an ORF identical to that of hIMPase (human myo-inositol monophosphatase). The ability of hIMPase to suppress galactose toxicity is sensitive to the presence of Li(+) in the medium. A gal7 yeast strain harboring a plasmid containing cloned hIMPase grows on galactose as a sole carbon source. hIMPase mediated galactose metabolism is dependent on the functionality of GAL1 as well as GAL10 encoded galactokinase and epimerase respectively. These results predicted that the UDP-glucose/galactose pyrophosphorylase mediated pathway may be responsible for the relief of galactose toxicity. Experiments conducted to test this prediction revealed that expression of UGP1 encoded UDP-glucose pyrophosphorylase can indeed overcome the relief of galactose toxicity. Moreover, expression of UGP1 allows a gal7 strain to grow on galactose as a sole carbon source. Unlike the hIMPase mediated relief of galactose toxicity, UGP1 mediated relief of galactose toxicity is lithium insensitive. Based on our results and on the basis of available information on galactose toxicity, we suggest an alternative explanation for the molecular mechanism of galactose toxicity.
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Affiliation(s)
- D V Mehta
- Laboratory of Molecular Genetics, Biotechnology Centre, Indian Institute of Technology, Powai, Mumbai 400 076, India
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35
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Sharifzadeh M, Abdollahi M, Behrooz H, Minaii B, Kebriaeezadeh A, Kashani MR, Dehpour AR, Aghaebrahimi N. Effects of chronic lithium on ototoxicity induced by gentamicin and amikacin in guinea-pigs. PHARMACOLOGY & TOXICOLOGY 1998; 83:220-4. [PMID: 9834971 DOI: 10.1111/j.1600-0773.1998.tb01472.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The effects of chronic lithium co-therapy on the expression of gentamicin and amikacin ototoxicity were tested in guinea-pigs. Intramuscular injection of different doses of gentamicin (5, 10 mg/kg/day) and amikacin (150, 300 mg/kg/day) for three weeks, induced hearing loss consistent with the established pattern of aminoglycoside ototoxicity. Lithium salts remains one of the most widely used treatment for depressive illness. Administration of lithium chloride (600 mg/l, 35 days) in drinking water changed auditory brainstem response in a time-dependent manner. Pretreatment of animals with lithium chloride after seven days induced significant alterations in wave latency and interval. The present study assesses the protective effects of chronic lithium on gentamicin-induced ototoxicity in guinea pig. The results suggest that duration of lithium administration may be involved in auditory brainstem response changes and the observations could be accounted for, at least partially, by lithium- and aminoglycosides-induced perturbations of the phosphoinositide cascade within the inner ear.
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Affiliation(s)
- M Sharifzadeh
- Department of Toxicology and Pharmacology, Faculty of Pharmacy, Tehran University of Medical Sciences, Iran
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36
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Van Epps-Fung M, Gupta K, Hardy RW, Wells A. A role for phospholipase C activity in GLUT4-mediated glucose transport. Endocrinology 1997; 138:5170-5. [PMID: 9389497 DOI: 10.1210/endo.138.12.5596] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Overexpression of surrogate receptors [epidermal growth factor (EGF) receptor (EGFR) and platelet-derived growth factor receptor] in adipocytes has demonstrated that multiple signaling pathways may lead to GLUT4-mediated glucose uptake. These implicated pathways function independently of IRS-1 phosphorylation and PI3-kinase activation. In addition, we previously demonstrated that EGFR tyrosyl autophosphorylation is required to stimulate GLUT4-mediated glucose transport in 3T3-L1 adipocytes. This observation suggests that signaling molecules that are dependent on EGFR autophosphorylation, such as phospholipase C (PLC), may lie in the signaling pathway to glucose transport. As PLC has been implicated in glucose transport by several clinical and basic mechanistic studies, we investigated whether EGFR signaling may promote glucose transport via modulation of PLC activity. Activation of EGFR overexpressing 3T3-L1 adipocytes leads to a 3.4 +/- 1.2-fold stimulation of PLC activity over basal levels vs. only 1.06 +/- 0.01-fold stimulation by insulin. Pharmacological inhibition of PLC by 50 microM U73122 reduced phosphoinositide accumulation by 79.2 +/- 16.9% and resulted in a concomitant 56.0 +/- 12.7% decrease in EGF-induced glucose transport. This inhibition of glucose transport by U73122 was specific, because the inactive congener, U73343, failed to block EGF-induced glucose transport. Despite the low levels of insulin-induced PLC activity, insulin-stimulated glucose transport activity was similarly inhibited by U73122 (55.9 +/- 13.1% inhibition). Inhibition of PLC activation did not impair either EGF- or insulin-induced activation of glycogen synthase or incorporation of glucose into lipid, supporting the hypothesis that both EGF- and insulin-induced glucose disposal can be independent of GLUT4-mediated glucose transport. The diminution of glucose transport secondary to inhibition of PLC activity was reflected by a decrease in GLUT4 translocation to the plasma membrane upon either EGF or insulin stimulation. These results are consistent with either a permissive or an active role for PLC activity in the translocation of GLUT4 to the plasma membrane.
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Affiliation(s)
- M Van Epps-Fung
- Department of Pathology, University of Alabama at Birmingham, 35294, USA
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Majumder AL, Johnson MD, Henry SA. 1L-myo-inositol-1-phosphate synthase. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1348:245-56. [PMID: 9370339 DOI: 10.1016/s0005-2760(97)00122-7] [Citation(s) in RCA: 153] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
1L-myo-Inositol-1-phosphate synthase catalyzes the conversion of D-glucose 6-phosphate to 1L-myo-inositol-1-phosphate, the first committed step in the production of all inositol-containing compounds, including phospholipids, either directly or by salvage. The enzyme exists in a cytoplasmic form in a wide range of plants, animals, and fungi. It has also been detected in several bacteria and a chloroplast form is observed in alga and higher plants. The enzyme has been purified from a wide range of organisms and its active form is a multimer of identical subunits ranging in molecular weight from 58,000 to 67,000. The activity of the synthase is stimulated by NH4Cl and inhibited by glucitol 6-phosphate and 2-deoxyglucose 6-phosphate. Structural genes (INO1) encoding the 1L-myo-inositol-1-phosphate synthase subunit have been isolated from several eukaryotic microorganisms and higher plants. In baker's yeast, Saccharomyces cerevisiae, the transcriptional regulation of the INO1 gene has been studied in detail and its expression is sensitive to the availability of phospholipid precursors as well as growth phase. The regulation of the structural gene encoding 1L-myo-inositol-1-phosphate synthase has also been analyzed at the transcriptional level in the aquatic angiosperm, Spirodela polyrrhiza and the halophyte, Mesembryanthemum crystallinum.
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Affiliation(s)
- A L Majumder
- Department of Botany, Bose Institute, Calcutta, India
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Matsuhisa A, Suzuki N, Noda T, Shiba K. Inositol monophosphatase activity from the Escherichia coli suhB gene product. J Bacteriol 1995; 177:200-5. [PMID: 8002619 PMCID: PMC176573 DOI: 10.1128/jb.177.1.200-205.1995] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The suhB gene is located at 55 min on the Escherichia coli chromosome and encodes a protein of 268 amino acids. Mutant alleles of suhB have been isolated as extragenic suppressors for the protein secretion mutation (secY24), the heat shock response mutation (rpoH15), and the DNA synthesis mutation (dnaB121) (K. Shiba, K. Ito, and T. Yura, J. Bacteriol. 160:696-701, 1984; R. Yano, H. Nagai, K. Shiba, and T. Yura, J. Bacteriol. 172:2124-2130, 1990; S. Chang, D. Ng, L. Baird, and C. Georgopoulos, J. Biol. Chem. 266:3654-3660, 1991). These mutant alleles of suhB cause cold-sensitive cell growth, indicating that the suhB gene is essential at low temperatures. Little work has been done, however, to elucidate the role of the product of suhB in a normal cell and the suppression mechanisms of the suhB mutations in the aforementioned mutants. The sequence similarity shared between the suhB gene product and mammalian inositol monophosphatase has prompted us to test the inositol monophosphatase activity of the suhB gene product. We report here that the purified SuhB protein showed inositol monophosphatase activity. The kinetic parameters of SuhB inositol monophosphatase (Km = 0.071 mM; Vmax = 12.3 mumol/min per mg) are similar to those of mammalian inositol monophosphatase. The ssyA3 and suhB2 mutations, which were isolated as extragenic suppressors for secY24 and rpoH15, respectively, had a DNA insertion at the 5' proximal region of the suhB gene, and the amount of SuhB protein within mutant cells decreased. The possible role of suhB in E. coli is discussed.
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Affiliation(s)
- A Matsuhisa
- Research & Development Center, Fuso Pharmaceutical Industries, Osaka, Japan
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Katayama T. Effect of dietary addition of myo-inositol on lipid metabolism in rats fed sucrose or corn starch. Nutr Res 1994. [DOI: 10.1016/s0271-5317(05)80205-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Affiliation(s)
- R S Jope
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham 35294
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Parthasarathy L, Vadnal RE, Parthasarathy R, Devi CS. Biochemical and molecular properties of lithium-sensitive myo-inositol monophosphatase. Life Sci 1994; 54:1127-42. [PMID: 8152337 DOI: 10.1016/0024-3205(94)00835-3] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Myo-inositol monophosphatase is a pivotal enzyme of the inositol second messenger system which is specifically inhibited by therapeutic levels of lithium salts, implicating inhibition of this enzyme as a potential site of its action in bipolar disease. This enzyme has a native molecular weight of 59,000, and has traditionally been found in the cytosolic fraction, although a membrane-bound form has also been identified. Possessing two identical subunits, this enzyme hydrolyzes those monophosphates which are equatorially located within the inositol ring, and several nucleoside monophosphates phosphorylated at the 2-position. Each subunit of the native enzyme contains an active site with unusually large caverns as revealed by crystallographic studies, which may explain the accommodation of these structurally unrelated substrates. We have suggested that the uncompetitive inhibition of this phosphatase by lithium ions may prevent the formation of an enzyme-bound non-isomeric (meso) intermediate, Mg(2+)-inositol 1,3 or 4,6 cyclic monophosphate when this enzyme hydrolyzes its respective isomeric substrates.
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Abstract
We have previously established that 21-day-old postnatal rat oligodendrocytes, maintained in monolayer culture and subjected to 6 h of hypoxia, show reversible inhibition of synthesis of alpha-hydroxy fatty acid and myelin basic protein but a dramatic induction of a 22-kDa protein, suggesting that this is a good model to study the mechanism of CNS demyelination caused by hypoxic injury. We now report that hypoxia also dramatically inhibits the basal protein kinase C-mediated phosphorylation of myelin basic protein and myelin 2',3'-cyclic nucleotide phosphohydrolase by 80%, but that the inhibition of phosphorylation can be reversed by addition of a protein kinase C activator, phorbol 12-myristate 13-acetate. The mechanism of action appears to involve the uncoupling of signal transduction at a site before phospholipase C, because hypoxia did not affect protein kinase C activity or its translocation to the membrane fraction. The most potent activator of phospholipase C (as measured by inositol phosphate release) was carbachol (muscarinic M1 receptor agonist), followed by L-phenylephrine (alpha 1-adrenergic receptor agonist) in normal oligodendrocytes. Excitatory amino acids and histamine were ineffective. Hypoxia for 6 h completely inhibited both muscarinic and alpha 1-adrenergic receptor-mediated inositol monophosphate release but did not affect phospholipase D-coupled phosphatidylethanol production in response to carbachol. We therefore conclude from this and earlier work that early, reversible changes in oligodendrocyte metabolism result not simply from ATP depletion, but may specifically target GTP binding protein-mediated processes.
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Affiliation(s)
- Y Qi
- Department of Pediatrics, Joseph P. Kennedy Jr. Mental Retardation Research Center, University of Chicago, Illinois 60637
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Davis BA, Hogan EM, Boron WF. Activation of Na-H exchange by intracellular lithium in barnacle muscle fibers. THE AMERICAN JOURNAL OF PHYSIOLOGY 1992; 263:C246-56. [PMID: 1322042 DOI: 10.1152/ajpcell.1992.263.1.c246] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We internally dialyzed single barnacle muscle fibers (BMF) for 90 min with a dialysis fluid (DF) containing no Na+ and either 0 or 100 mM Li+ and measured intracellular pH (pHi) with a microelectrode. During dialysis, the pH 8.0 artificial seawater (ASW) contained neither Na+ nor HCO3-. After we halted dialysis with a Li(+)-free/low-pH DF and allowed pHi to stabilize at approximately 6.8, adding 440 mM Na(+)-10 mM HCO3- to the ASW caused pHi to recover rapidly and stabilize at 7.32. In contrast, when the DF contained 100 mM Li+, pHi stabilized at 7.49. In fibers dialyzed to a pHi of approximately 7.2, Li+ stimulated a component of acid extrusion that was dependent on Na+ but not affected by SITS. Thus Li+ activates a Na(+)-dependent acid-extrusion mechanism other than the well characterized Na(+)-dependent Cl-HCO3 exchanger. To study the Li(+)-activated mechanism, we minimized Na(+)-dependent Cl-HCO3 exchange by raising pHDF to 7.35 and pretreated BMFs with SITS. We found that dialysis with Li+ elicits a Na(+)-dependent pHi increase that is largely blocked by amiloride, consistent with the hypothesis that Li+ activates a latent Na-H exchanger even at a normal pHi. In the absence of Li+, the Na-H exchanger is relatively inactive at pHi 7.35 (net acid-extrusion rate, Jnet = 9.5 microM/min) but modestly stimulated by reducing pHi to 6.8 (Jnet = 64 microM/min). In the presence of Li+, the Na-H exchanger is very active at pHi values of both 7.35 (Jnet = 141 microM/min) and 6.8 (Jnet = 168 microM/min). Thus Li+ alters the pHi sensitivity of the Na-H exchanger. Because the Na-H exchanger is only approximately 6% as active as the Na(+)-dependent Cl-HCO3 exchanger in the absence of Li+ at a pHi of approximately 6.8, we suggest that the major role of the Na-H exchanger may not be in pHi regulation but in another function such as cell-volume regulation.
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Affiliation(s)
- B A Davis
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06510
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Birch N, Phillips J. Lithium and Medicine: Inorganic Pharmacology. ADVANCES IN INORGANIC CHEMISTRY 1991. [DOI: 10.1016/s0898-8838(08)60036-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Burns G, Herz A, Nikolarakis KE. Stimulation of hypothalamic opioid peptide release by lithium is mediated by opioid autoreceptors: evidence from a combined in vitro, ex vivo study. Neuroscience 1990; 36:691-7. [PMID: 2172862 DOI: 10.1016/0306-4522(90)90012-s] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The effect of both chronic and acute lithium treatment on hypothalamic opioid peptides was investigated. Acute treatment with lithium was found to stimulate the release of beta-endorphin, dynorphin and Met-enkephalin from perfused rat hypothalamic slices. Application of tetrodotoxin was found to have no effect upon the stimulation indicating it to be mediated at the nerve terminal level. The release of hypothalamic opioid peptides is known to be under the chronic control of a system of inhibitory autoreceptors. Blockade of these autoreceptors with, for example, the opioid receptor antagonist naloxone causes a release of all three opioid peptides. Simultaneous addition of naloxone and lithium was found to have no additive effect on the release of any opioid, suggesting lithium acts via an inhibition of the inhibitory autoreceptor. Preincubation with pertussis toxin prevented the lithium stimulation of dynorphin and Met-enkephalin, but not beta-endorphin, release, indicating lithium interacts with a G-protein to affect the autoreceptor controlling the release of dynorphin and Met-enkephalin. Chronic treatment with lithium in vivo (10 days) had no effect on the basal release or hypothalamic content of any of the opioids, but prevented the naloxone-stimulated release of dynorphin and Met-enkephalin in vitro. Long-term treatment with lithium would thus appear to inactivate the autoreceptor(s) controlling their release. These data demonstrate a lithium-stimulated release of hypothalamic beta-endorphin, Met-enkephalin and dynorphin, apparently mediated via an inhibition of the autoreceptors controlling their release. Chronic treatment with lithium permanently inactivated the autoreceptor(s) controlling the release of dynorphin and Met-enkephalin but not beta-endorphin. Lithium would appear to mediate its effects upon Met-enkephalin and dynorphin release via an interaction with a pertussis toxin-sensitive G-protein. The mechanisms underlying its release of beta-endorphin are at present uncertain.
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Affiliation(s)
- G Burns
- Department of Neuropharmacology, Max-Planck-Institut für Psychiatrie, Planegg-Martinsried, F.R.G
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Beyaert R, Vanhaesebroeck B, Suffys P, Van Roy F, Fiers W. Lithium chloride potentiates tumor necrosis factor-mediated cytotoxicity in vitro and in vivo. Proc Natl Acad Sci U S A 1989; 86:9494-8. [PMID: 2556714 PMCID: PMC298523 DOI: 10.1073/pnas.86.23.9494] [Citation(s) in RCA: 64] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Tumor necrosis factor (TNF) is cytotoxic for several transformed cell lines in vitro. In the presence of LiCl, the murine fibrosarcoma cell lines L929 and WEHI 164 clone 13 became greater than 10 times more sensitive to TNF-mediated cytotoxicity. The human tumor cell lines BT20 and HeLa D98/AH2 were also responsive to the cytotoxicity-enhancing effect of LiCl. Other monovalent or divalent cations did not affect TNF-mediated cytotoxicity. The potentiating effect of LiCl on TNF cytotoxicity was largely independent of transcription, and LiCl could be added to the cells as early as 2 hr before or as late as 4 hr after TNF without loss of effectiveness. The mechanism by which LiCl increases the cytotoxic response seems to differ from the sensitizing effect of actinomycin D or interferon gamma, since the latter treatments overcame TNF resistance of several cell lines, whereas LiCl did not. Evidence is presented that LiCl acts, either directly or indirectly, via the TNF-activated phospholipase A2 pathway. In nude mice, a combination of TNF and LiCl led to hemorrhagic necrosis and growth inhibition of L929 tumors, whereas little effect was observed when TNF was administered alone. HeLa D98/AH2 tumors also were sensitive to the potentiating effect of LiCl in vivo. We conclude that LiCl enhances the effectiveness of TNF in vitro and in vivo, results that may have therapeutic implications.
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Affiliation(s)
- R Beyaert
- State University, Laboratory of Molecular Biology, Ghent, Belgium
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Affiliation(s)
- S B Shears
- Laboratory of Cellular and Molecular Pharmacology, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709
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Abstract
Lithium is widely used in psychiatric chemotherapy and is especially effective in the treatment of manic-depressive illness (MDI), but the mechanism for its therapeutic properties and side effects remains to be elucidated. One of the possibilities relates to the inhibitory effect of Li+ on inositol-1-phosphatase (I-1-P'ase) activity. Indeed, the concentration of inositol-1-phosphate (I-1-P) after treatment with Li+ was shown to be increased in various mammalian cells. Yet, no direct study of I-1-P'ase activity in human cells has been reported. Erythrocytes are readily accessible for routine studies and could facilitate the investigation of I-1-P'ase as affected by Li+ in relation to MDI. It is now shown that I-1-P'ase can be measured in lysate of human erythrocytes, using a small blood sample. The enzymatic activity is localized in the soluble fraction. The Km for I-1-P is 0.14 mM. Intriguingly, the Ki for Li+ is 0.86 mM, within the range of therapeutic concentrations in MDI patients.
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Affiliation(s)
- G Agam
- Ben Gurion University of the Negev, Beer Sheva, Israel
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Affiliation(s)
- S B Shears
- Department of Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709
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