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Ijomone OM, Ijomone OK, Iroegbu JD, Ifenatuoha CW, Olung NF, Aschner M. Epigenetic influence of environmentally neurotoxic metals. Neurotoxicology 2020; 81:51-65. [PMID: 32882300 PMCID: PMC7708394 DOI: 10.1016/j.neuro.2020.08.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 08/25/2020] [Accepted: 08/25/2020] [Indexed: 02/08/2023]
Abstract
Continuous globalization and industrialization have ensured metals are an increasing aspect of daily life. Their usefulness in manufacturing has made them vital to national commerce, security and global economy. However, excess exposure to metals, particularly as a result of environmental contamination or occupational exposures, has been detrimental to overall health. Excess exposure to several metals is considered environmental risk in the aetiology of several neurological and neurodegenerative diseases. Metal-induced neurotoxicity has been a major health concern globally with intensive research to unravel the mechanisms associated with it. Recently, greater focus has been directed at epigenetics to better characterize the underlying mechanisms of metal-induced neurotoxicity. Epigenetic changes are those modifications on the DNA that can turn genes on or off without altering the DNA sequence. This review discusses how epigenetic changes such as DNA methylation, post translational histone modification and noncoding RNA-mediated gene silencing mediate the neurotoxic effects of several metals, focusing on manganese, arsenic, nickel, cadmium, lead, and mercury.
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Affiliation(s)
- Omamuyovwi M Ijomone
- The Neuro- Lab, Department of Human Anatomy, School of Health and Health Technology, Federal University of Technology, Akure, Nigeria.
| | - Olayemi K Ijomone
- The Neuro- Lab, Department of Human Anatomy, School of Health and Health Technology, Federal University of Technology, Akure, Nigeria; Department of Anatomy, University of Medical Sciences, Ondo, Nigeria
| | - Joy D Iroegbu
- The Neuro- Lab, Department of Human Anatomy, School of Health and Health Technology, Federal University of Technology, Akure, Nigeria
| | - Chibuzor W Ifenatuoha
- The Neuro- Lab, Department of Human Anatomy, School of Health and Health Technology, Federal University of Technology, Akure, Nigeria
| | - Nzube F Olung
- The Neuro- Lab, Department of Human Anatomy, School of Health and Health Technology, Federal University of Technology, Akure, Nigeria
| | - Michael Aschner
- Departments of Molecular Pharmacology and Neurosciences, Albert Einstein College of Medicine, NY, USA.
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Kelly E, Sharma D, Wilkinson CJ, Williams RSB. Diacylglycerol kinase (DGKA) regulates the effect of the epilepsy and bipolar disorder treatment valproic acid in Dictyostelium discoideum. Dis Model Mech 2018; 11:11/9/dmm035600. [PMID: 30135067 PMCID: PMC6176992 DOI: 10.1242/dmm.035600] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 07/03/2018] [Indexed: 12/30/2022] Open
Abstract
Valproic acid (VPA) provides a common treatment for both epilepsy and bipolar disorder; however, common cellular mechanisms relating to both disorders have yet to be proposed. Here, we explore the possibility of a diacylglycerol kinase (DGK) playing a role in regulating the effect of VPA relating to the treatment of both disorders, using the biomedical model Dictyostelium discoideum. DGK enzymes provide the first step in the phosphoinositide recycling pathway, implicated in seizure activity. They also regulate levels of diacylglycerol (DAG), thereby regulating the protein kinase C (PKC) activity that is linked to bipolar disorder-related signalling. Here, we show that ablation of the single Dictyostelium dgkA gene results in reduced sensitivity to the acute effects of VPA on cell behaviour. Loss of dgkA also provides reduced sensitivity to VPA in extended exposure during development. To differentiate a potential role for this DGKA-dependent mechanism in epilepsy and bipolar disorder treatment, we further show that the dgkA null mutant is resistant to the developmental effects of a range of structurally distinct branched medium-chain fatty acids with seizure control activity and to the bipolar disorder treatment lithium. Finally, we show that VPA, lithium and novel epilepsy treatments function through DAG regulation, and the presence of DGKA is necessary for compound-specific increases in DAG levels following treatment. Thus, these experiments suggest that, in Dictyostelium, loss of DGKA attenuates a common cellular effect of VPA relating to both epilepsy and bipolar disorder treatments, and that a range of new compounds with this effect should be investigated as alternative therapeutic agents. This article has an associated First Person interview with the first author of the paper. Editor's choice: Here, using a tractable model system, Dictyostelium discoideum, we show that diacylglycerol kinase activity might contribute to the cellular mechanism of action of the epilepsy and bipolar disorder treatment, valproic acid.
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Affiliation(s)
- Elizabeth Kelly
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Devdutt Sharma
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Christopher J Wilkinson
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Robin S B Williams
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham TW20 0EX, UK
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Frej AD, Clark J, Le Roy CI, Lilla S, Thomason PA, Otto GP, Churchill G, Insall RH, Claus SP, Hawkins P, Stephens L, Williams RSB. The Inositol-3-Phosphate Synthase Biosynthetic Enzyme Has Distinct Catalytic and Metabolic Roles. Mol Cell Biol 2016; 36:1464-79. [PMID: 26951199 PMCID: PMC4859692 DOI: 10.1128/mcb.00039-16] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 02/19/2016] [Accepted: 03/03/2016] [Indexed: 12/24/2022] Open
Abstract
Inositol levels, maintained by the biosynthetic enzyme inositol-3-phosphate synthase (Ino1), are altered in a range of disorders, including bipolar disorder and Alzheimer's disease. To date, most inositol studies have focused on the molecular and cellular effects of inositol depletion without considering Ino1 levels. Here we employ a simple eukaryote, Dictyostelium discoideum, to demonstrate distinct effects of loss of Ino1 and inositol depletion. We show that loss of Ino1 results in an inositol auxotrophy that can be rescued only partially by exogenous inositol. Removal of inositol supplementation from the ino1(-) mutant resulted in a rapid 56% reduction in inositol levels, triggering the induction of autophagy, reduced cytokinesis, and substrate adhesion. Inositol depletion also caused a dramatic generalized decrease in phosphoinositide levels that was rescued by inositol supplementation. However, loss of Ino1 triggered broad metabolic changes consistent with the induction of a catabolic state that was not rescued by inositol supplementation. These data suggest a metabolic role for Ino1 that is independent of inositol biosynthesis. To characterize this role, an Ino1 binding partner containing SEL1L1 domains (Q54IX5) and having homology to mammalian macromolecular complex adaptor proteins was identified. Our findings therefore identify a new role for Ino1, independent of inositol biosynthesis, with broad effects on cell metabolism.
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Affiliation(s)
- Anna D Frej
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, United Kingdom
| | - Jonathan Clark
- The Babraham Institute, Cambridge, Cambridgeshire, United Kingdom
| | - Caroline I Le Roy
- Department of Food and Nutritional Sciences, The University of Reading, Reading, Berkshire, United Kingdom
| | - Sergio Lilla
- Cancer Research UK Beatson Institute, Bearsden, Glasgow, United Kingdom
| | - Peter A Thomason
- Cancer Research UK Beatson Institute, Bearsden, Glasgow, United Kingdom
| | - Grant P Otto
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, United Kingdom
| | - Grant Churchill
- Department of Pharmacology, University of Oxford, Oxford, Oxfordshire, United Kingdom
| | - Robert H Insall
- Cancer Research UK Beatson Institute, Bearsden, Glasgow, United Kingdom
| | - Sandrine P Claus
- Department of Food and Nutritional Sciences, The University of Reading, Reading, Berkshire, United Kingdom
| | - Phillip Hawkins
- The Babraham Institute, Cambridge, Cambridgeshire, United Kingdom
| | - Len Stephens
- The Babraham Institute, Cambridge, Cambridgeshire, United Kingdom
| | - Robin S B Williams
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, United Kingdom
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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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Ye C, Greenberg ML. Inositol synthesis regulates the activation of GSK-3α in neuronal cells. J Neurochem 2014; 133:273-83. [PMID: 25345501 DOI: 10.1111/jnc.12978] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 10/10/2014] [Accepted: 10/13/2014] [Indexed: 12/26/2022]
Abstract
The synthesis of inositol provides precursors of inositol lipids and inositol phosphates that are pivotal for cell signaling. Mood stabilizers lithium and valproic acid, used for treating bipolar disorder, cause cellular inositol depletion, which has been proposed as a therapeutic mechanism of action of both drugs. Despite the importance of inositol, the requirement for inositol synthesis in neuronal cells is not well understood. Here, we examined inositol effects on proliferation of SK-N-SH neuroblastoma cells. The essential role of inositol synthesis in proliferation is underscored by the findings that exogenous inositol was dispensable for proliferation, and inhibition of inositol synthesis decreased proliferation. Interestingly, the inhibition of inositol synthesis by knocking down INO1, which encodes inositol-3-phosphate synthase, the rate-limiting enzyme of inositol synthesis, led to the inactivation of GSK-3α by increasing the inhibitory phosphorylation of this kinase. Similarly, the mood stabilizer valproic acid effected transient decreases in intracellular inositol, leading to inactivation of GSK-3α. As GSK-3 inhibition has been proposed as a likely therapeutic mechanism of action, the finding that inhibition of inositol synthesis results in the inactivation of GSK-3α suggests a unifying hypothesis for mechanism of mood-stabilizing drugs. Inositol is an essential metabolite that serves as a precursor for inositol lipids and inositol phosphates. We report that inhibition of the rate-limiting enzyme of inositol synthesis leads to the inactivation of glycogen synthase kinase (GSK) 3α by increasing inhibitory phosphorylation of this kinase. These findings have implications for the therapeutic mechanisms of mood stabilizers and suggest that inositol synthesis and GSK 3α activity are intrinsically related.
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Affiliation(s)
- Cunqi Ye
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
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Zhang L, Di J. The transcriptional activator Ino2p dissociates from the yeast INM1 promoter in induction. DNA Cell Biol 2014; 33:863-8. [PMID: 25211324 DOI: 10.1089/dna.2014.2397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mood stabilizers lithium and valproates are widely used in the treatment of bipolar disorder. It has been shown that these drugs can affect the inositol monophosphatase activity and thus the inositol de novo biosynthesis. However, the molecular mechanism of this action has thus far been vague. As such, characterizing the regulation of the gene encoding inositol monophosphatase at the molecular level can help to understand the bipolar disorder. As the model organism, the inositol monophosphatase is encoded by INM1 in Saccharomyces cerevisiae. In this study, we showed, using real-time reverse transcriptase polymerase chain reaction analysis, that INM1 is expressed in the presence of inositol, suggesting that the presence of inositol is required for INM1 transcriptional activation. We also demonstrated, using chromatin immunoprecipitation, that Ino2p is present at the promoter under uninduced conditions. Upon induction, Ino2p dissociates from the INM1 promoter. Furthermore, chromatin remodelers Ino80p and Snf2p are recruited to INM1 promoter upon induction as well as histone acetylases Gcn5p and Esa1p. Altogether, we have provided the evidence which describes how the transcriptional activator and coactivators participate in INM1 activation.
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Affiliation(s)
- Lingzhi Zhang
- 1 Department of Emergency, Shengjing Hospital of China Medical University , Shenyang, China
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Teng HF, Li PN, Hou DR, Liu SW, Lin CT, Loo MR, Kao CH, Lin KH, Chen SL. Valproic acid enhances Oct4 promoter activity through PI3K/Akt/mTOR pathway activated nuclear receptors. Mol Cell Endocrinol 2014; 383:147-58. [PMID: 24361750 DOI: 10.1016/j.mce.2013.12.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 11/24/2013] [Accepted: 12/13/2013] [Indexed: 12/21/2022]
Abstract
Valproic acid (VPA) has been shown to increase the reprogramming efficiency of induced pluripotent stem cells (iPSC) from somatic cells, but the mechanism by which VPA enhances iPSC induction has not been defined. Here we demonstrated that VPA directly activated Oct4 promoter activity through activation of the PI3K/Akt/mTOR signaling pathway that targeted the proximal hormone response element (HRE, -41∼-22) in this promoter. The activating effect of VPA is highly specific as similar compounds or constitutional isomers failed to instigate Oct4 promoter activity. We further demonstrated that the upstream 2 half-sites in this HRE were essential to the activating effect of VPA and they were targeted by a subset of nuclear receptors, such as COUP-TFII and TR2. These findings show the first time that NRs are implicated in the VPA stimulated expression of stem cell-specific factors and should invite more investigation on the cooperation between VPA and NRs on iPSC induction.
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Affiliation(s)
- Han Fang Teng
- Department of Life Sciences, National Central University, Jhongli 32001, Taiwan
| | - Pei Ning Li
- Department of Life Sciences, National Central University, Jhongli 32001, Taiwan
| | - Duen Ren Hou
- Department of Chemistry, National Central University, Jhongli 32001, Taiwan
| | - Sin Wei Liu
- Department of Chemistry, National Central University, Jhongli 32001, Taiwan
| | - Cheng Tao Lin
- Department of Life Sciences, National Central University, Jhongli 32001, Taiwan
| | - Moo Rung Loo
- Department of Life Sciences, National Central University, Jhongli 32001, Taiwan
| | - Chien Han Kao
- Department of Life Sciences, National Central University, Jhongli 32001, Taiwan
| | - Kwang Huei Lin
- Department of Biochemistry, Chang Gung University, Taoyuan 333, Taiwan
| | - Shen Liang Chen
- Department of Life Sciences, National Central University, Jhongli 32001, Taiwan.
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Epigenetics and autism. AUTISM RESEARCH AND TREATMENT 2013; 2013:826156. [PMID: 24151554 PMCID: PMC3787640 DOI: 10.1155/2013/826156] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 07/17/2013] [Accepted: 08/01/2013] [Indexed: 12/19/2022]
Abstract
This review identifies mechanisms for altering DNA-histone interactions of cell chromatin to upregulate or downregulate gene expression that could serve as epigenetic targets for therapeutic interventions in autism. DNA methyltransferases (DNMTs) can phosphorylate histone H3 at T6. Aided by protein kinase C β 1, the DNMT lysine-specific demethylase-1 prevents demethylation of H3 at K4. During androgen-receptor-(AR-) dependent gene activation, this sequence may produce AR-dependent gene overactivation which may partly explain the male predominance of autism. AR-dependent gene overactivation in conjunction with a DNMT mechanism for methylating oxytocin receptors could produce high arousal inputs to the amygdala resulting in aberrant socialization, a prime characteristic of autism. Dysregulation of histone methyltransferases and histone deacetylases (HDACs) associated with low activity of methyl CpG binding protein-2 at cytosine-guanine sites in genes may reduce the capacity for condensing chromatin and silencing genes in frontal cortex, a site characterized by decreased cortical interconnectivity in autistic subjects. HDAC1 inhibition can overactivate mRNA transcription, a putative mechanism for the increased number of cerebral cortical columns and local frontal cortex hyperactivity in autistic individuals. These epigenetic mechanisms underlying male predominance, aberrant social interaction, and low functioning frontal cortex may be novel targets for autism prevention and treatment strategies.
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Modi HR, Basselin M, Taha AY, Li LO, Coleman RA, Bialer M, Rapoport SI. Propylisopropylacetic acid (PIA), a constitutional isomer of valproic acid, uncompetitively inhibits arachidonic acid acylation by rat acyl-CoA synthetase 4: a potential drug for bipolar disorder. BIOCHIMICA ET BIOPHYSICA ACTA 2013; 1831:880-6. [PMID: 23354024 PMCID: PMC3593989 DOI: 10.1016/j.bbalip.2013.01.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Revised: 12/21/2012] [Accepted: 01/13/2013] [Indexed: 12/22/2022]
Abstract
BACKGROUND Mood stabilizers used for treating bipolar disorder (BD) selectively downregulate arachidonic acid (AA) turnover (deacylation-reacylation) in brain phospholipids, when given chronically to rats. In vitro studies suggest that one of these, valproic acid (VPA), which is teratogenic, reduces AA turnover by inhibiting the brain long-chain acyl-CoA synthetase (Acsl)4 mediated acylation of AA to AA-CoA. We tested whether non-teratogenic VPA analogues might also inhibit Acsl4 catalyzed acylation, and thus have a potential anti-BD action. METHODS Rat Acsl4-flag protein was expressed in Escherichia coli, and the ability of three VPA analogues, propylisopropylacetic acid (PIA), propylisopropylacetamide (PID) and N-methyl-2,2,3,3-tetramethylcyclopropanecarboxamide (MTMCD), and of sodium butyrate, to inhibit conversion of AA to AA-CoA by Acsl4 was quantified using Michaelis-Menten kinetics. RESULTS Acsl4-mediated conversion of AA to AA-CoA in vitro was inhibited uncompetitively by PIA, with a Ki of 11.4mM compared to a published Ki of 25mM for VPA, while PID, MTMCD and sodium butyrate had no inhibitory effect. CONCLUSIONS PIA's ability to inhibit conversion of AA to AA-CoA by Acsl4 in vitro suggests that, like VPA, PIA may reduce AA turnover in brain phospholipids in unanesthetized rats, and if so, may be effective as a non-teratogenic mood stabilizer in BD patients.
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Affiliation(s)
- Hiren R Modi
- Brain Physiology and Metabolism Section, National Institute on Aging, Laboratory of Neurosciences, National Institutes of Health, Bethesda, MD, USA.
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Lee SH, Yoon J, Shin SH, Zahoor M, Kim HJ, Park PJ, Park WS, Min DS, Kim HY, Choi KY. Valproic acid induces hair regeneration in murine model and activates alkaline phosphatase activity in human dermal papilla cells. PLoS One 2012; 7:e34152. [PMID: 22506014 PMCID: PMC3323655 DOI: 10.1371/journal.pone.0034152] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 02/23/2012] [Indexed: 11/25/2022] Open
Abstract
Background Alopecia is the common hair loss problem that can affect many people. However, current therapies for treatment of alopecia are limited by low efficacy and potentially undesirable side effects. We have identified a new function for valproic acid (VPA), a GSK3β inhibitor that activates the Wnt/β-catenin pathway, to promote hair re-growth in vitro and in vivo. Methodology/ Principal Findings Topical application of VPA to male C3H mice critically stimulated hair re-growth and induced terminally differentiated epidermal markers such as filaggrin and loricrin, and the dermal papilla marker alkaline phosphatase (ALP). VPA induced ALP in human dermal papilla cells by up-regulating the Wnt/β-catenin pathway, whereas minoxidil (MNX), a drug commonly used to treat alopecia, did not significantly affect the Wnt/β-catenin pathway. VPA analogs and other GSK3β inhibitors that activate the Wnt/β-catenin pathway such as 4-phenyl butyric acid, LiCl, and BeCl2 also exhibited hair growth-promoting activities in vivo. Importantly, VPA, but not MNX, successfully stimulate hair growth in the wounds of C3H mice. Conclusions/ Significance Our findings indicate that small molecules that activate the Wnt/β-catenin pathway, such as VPA, can potentially be developed as drugs to stimulate hair re-growth.
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Affiliation(s)
- Soung-Hoon Lee
- Translational Research Center for Protein Function Control, Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Juyong Yoon
- Translational Research Center for Protein Function Control, Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Seung Ho Shin
- Translational Research Center for Protein Function Control, Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Muhamad Zahoor
- Translational Research Center for Protein Function Control, Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Hyoung Jun Kim
- Skin Research Team, Skin Research Institute, Amore Pacific Corporation Research and Development Center, Kyounggi-do, South Korea
| | - Phil June Park
- Skin Research Team, Skin Research Institute, Amore Pacific Corporation Research and Development Center, Kyounggi-do, South Korea
| | - Won-Seok Park
- Skin Research Team, Skin Research Institute, Amore Pacific Corporation Research and Development Center, Kyounggi-do, South Korea
| | - Do Sik Min
- Translational Research Center for Protein Function Control, Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
- Department of Molecular Biology, College of Natural Science, Pusan National University, Busan, South Korea
| | - Hyun-Yi Kim
- Translational Research Center for Protein Function Control, Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
| | - Kang-Yell Choi
- Translational Research Center for Protein Function Control, Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, South Korea
- * E-mail:
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Wu M, Khan IA, Dasmahapatra AK. Valproate-induced teratogenesis in Japanese rice fish (Oryzias latipes) embryogenesis. Comp Biochem Physiol C Toxicol Pharmacol 2012; 155:528-37. [PMID: 22249148 DOI: 10.1016/j.cbpc.2012.01.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2011] [Revised: 01/04/2012] [Accepted: 01/05/2012] [Indexed: 01/18/2023]
Abstract
Fertilized eggs of Japanese rice fish (medaka) at three developmental stages (Iwamatsu stages 4-30) were exposed to waterborne valproic acid (VPA) (0-80 mM) in hatching solution for 48 h. The amount of valproate to cause 50% mortality (IC(50)) is found to be developmental stage-specific. The embryos were more sensitive to valproate at early stages of development (Iwamatsu stages 4-10) than in the embryos in late stages (Iwamatsu stages 17-30). Valproate exposed embryos have microcephaly and disrupted cardiovasculature with delayed vessel circulation, thrombus formation, and slow heart rate. The hatching efficiency is also reduced by valproate exposure due to developmental delay. The mRNA analysis of nine genes belong to oxidative stress (catalase, gsr, gst), neurogenesis (iro3, wnt1, shh, otx2, nlgn3b) and cell cycle regulation (ccna2) have been done. It was observed that the genes belong to oxidative stress remained unaltered after valproate exposure. However, some of the genes belong to neurogenesis (wnt1,shh, otx2 and nlgn3b) and cell cycle (ccna2) showed developmental stage-specific alteration after valproate exposure. This study indicates that valproate is able to induce some of the phenotypic features which are analogous to human fetal valproate syndrome (FVS). Modulation of genes expressed in neural tissues indicates that this fish can be used to analyze the mechanisms of many neurobehavioral disorders like Autism spectrum disorder (ASD) in human.
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Affiliation(s)
- Mengmeng Wu
- National Center for Natural Products Research, University of Mississippi, University, Mississippi 38677, USA
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Chang P, Orabi B, Deranieh RM, Dham M, Hoeller O, Shimshoni JA, Yagen B, Bialer M, Greenberg ML, Walker MC, Williams RSB. The antiepileptic drug valproic acid and other medium-chain fatty acids acutely reduce phosphoinositide levels independently of inositol in Dictyostelium. Dis Model Mech 2012; 5:115-24. [PMID: 21876211 PMCID: PMC3255550 DOI: 10.1242/dmm.008029] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2011] [Accepted: 07/14/2011] [Indexed: 12/11/2022] Open
Abstract
Valproic acid (VPA) is the most widely prescribed epilepsy treatment worldwide, but its mechanism of action remains unclear. Our previous work identified a previously unknown effect of VPA in reducing phosphoinositide production in the simple model Dictyostelium followed by the transfer of data to a mammalian synaptic release model. In our current study, we show that the reduction in phosphoinositide [PtdInsP (also known as PIP) and PtdInsP(2) (also known as PIP(2))] production caused by VPA is acute and dose dependent, and that this effect occurs independently of phosphatidylinositol 3-kinase (PI3K) activity, inositol recycling and inositol synthesis. In characterising the structural requirements for this effect, we also identify a family of medium-chain fatty acids that show increased efficacy compared with VPA. Within the group of active compounds is a little-studied group previously associated with seizure control, and analysis of two of these compounds (nonanoic acid and 4-methyloctanoic acid) shows around a threefold enhanced potency compared with VPA for protection in an in vitro acute rat seizure model. Together, our data show that VPA and a newly identified group of medium-chain fatty acids reduce phosphoinositide levels independently of inositol regulation, and suggest the reinvestigation of these compounds as treatments for epilepsy.
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Affiliation(s)
- Pishan Chang
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, TW20 0EX, UK
| | - Benoit Orabi
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, TW20 0EX, UK
| | - Rania M. Deranieh
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Manik Dham
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, TW20 0EX, UK
| | - Oliver Hoeller
- Department of Cellular and Molecular Pharmacology and the Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA 94158, USA
| | - Jakob A. Shimshoni
- Institute for Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, 91120 Jerusalem, Israel
| | - Boris Yagen
- Institute for Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, 91120 Jerusalem, Israel
| | - Meir Bialer
- Institute for Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, 91120 Jerusalem, Israel
| | - Miriam L. Greenberg
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
| | - Matthew C. Walker
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London, London, WC1N 3BG, UK
| | - Robin S. B. Williams
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, TW20 0EX, UK
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Elphick LM, Pawolleck N, Guschina IA, Chaieb L, Eikel D, Nau H, Harwood JL, Plant NJ, Williams RSB. Conserved valproic-acid-induced lipid droplet formation in Dictyostelium and human hepatocytes identifies structurally active compounds. Dis Model Mech 2011; 5:231-40. [PMID: 22003123 PMCID: PMC3291644 DOI: 10.1242/dmm.008391] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Lipid droplet formation and subsequent steatosis (the abnormal retention of lipids within a cell) has been reported to contribute to hepatotoxicity and is an adverse effect of many pharmacological agents including the antiepileptic drug valproic acid (VPA). In this study, we have developed a simple model system (Dictyostelium discoideum) to investigate the effects of VPA and related compounds in lipid droplet formation. In mammalian hepatocytes, VPA increases lipid droplet accumulation over a 24-hour period, giving rise to liver cell damage, and we show a similar effect in Dictyostelium following 30 minutes of VPA treatment. Using 3H-labelled polyunsaturated (arachidonic) or saturated (palmitic) fatty acids, we shown that VPA treatment of Dictyostelium gives rise to an increased accumulation of both types of fatty acids in phosphatidylcholine, phosphatidylethanolamine and non-polar lipids in this time period, with a similar trend observed in human hepatocytes (Huh7 cells) labelled with [3H]arachidonic acid. In addition, pharmacological inhibition of β-oxidation in Dictyostelium phenocopies fatty acid accumulation, in agreement with data reported in mammalian systems. Using Dictyostelium, we then screened a range of VPA-related compounds to identify those with high and low lipid-accumulation potential, and validated these activities for effects on lipid droplet formation by using human hepatocytes. Structure-activity relationships for these VPA-related compounds suggest that lipid accumulation is independent of VPA-catalysed teratogenicity and inositol depletion. These results suggest that Dictyostelium could provide both a novel model system for the analysis of lipid droplet formation in human hepatocytes and a rapid method for identifying VPA-related compounds that show liver toxicology.
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Affiliation(s)
- Lucy M Elphick
- Centre for Biomedical Sciences, School of Biological Science, Royal Holloway University of London, Egham, Surrey, UK
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14
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Abstract
While a distinct minicolumnar phenotype seems to be an underlying factor in a significant portion of cases of autism, great attention is being paid not only to genetics but to epigenetic factors which may lead to development of the conditions. Here we discuss the indivisible role the molecular environment plays in cellular function, particularly the pivotal position which the transcription factor and adhesion molecule, β-catenin, occupies in cellular growth. In addition, the learning environment is not only integral to postnatal plasticity, but the prenatal environment plays a vital role during corticogenesis, neuritogenesis, and synaptogenesis as well. To illustrate these points in the case of autism, we review important findings in genetics studies (e.g., PTEN, TSC1/2, FMRP, MeCP2, Neurexin-Neuroligin) and known epigenetic factors (e.g., valproic acid, estrogen, immune system, ultrasound) which may predispose towards the minicolumnar and connectivity patterns seen in the conditions, showing how one-gene mutational syndromes and exposure to certain CNS teratogens may ultimately lead to comparable phenotypes. This in turn may shed greater light on how environment and complex genetics combinatorially give rise to a heterogenetic group of conditions such as autism.
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Affiliation(s)
- Emily L. Williams
- Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, KY 40202, USA
| | - Manuel F. Casanova
- Department of Psychiatry and Behavioral Sciences, University of Louisville, Louisville, KY 40202, USA
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15
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Hu LW, Kawamoto EM, Brietzke E, Scavone C, Lafer B. The role of Wnt signaling and its interaction with diverse mechanisms of cellular apoptosis in the pathophysiology of bipolar disorder. Prog Neuropsychopharmacol Biol Psychiatry 2011; 35:11-7. [PMID: 20828594 DOI: 10.1016/j.pnpbp.2010.08.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2010] [Revised: 08/23/2010] [Accepted: 08/29/2010] [Indexed: 12/16/2022]
Abstract
The neurobiology of Bipolar Disorder (BD) is not completely understood, although abnormalities in neuroplasticity and control of apoptosis have been considered as central events in its pathophysiology. The molecules of the Wnt family comprise a class of proteins that control essential developmental processes such as embryonic patterning, cell growth, migration, and differentiation with their actions largely exerted by modulating gene transcription. The Wnt signaling pathway has interface with some mediators with a well documented action in neuroplasticity and regulation of cell surviving. In addition, mood stabilizers such as lithium and valproate may have their neuroprotective properties in part mediated by the Wnt pathway. This article is an overview of how the Wnt signaling cascade might be involved in the pathogenesis of BD and also in details of intracellular events related to this pathway. Further studies of Wnt signaling may lead to a better comprehension of the neuroprotective actions of mood stabilizers and contribute to improving the therapeutics of BD.
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Affiliation(s)
- Li Wen Hu
- Bipolar Disorder Research Program, Department of Psychiatry, Medical School, University of São Paulo, São Paulo, Brazil.
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16
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Shimshoni JA, Basselin M, Li LO, Coleman RA, Rapoport SI, Modi HR. Valproate uncompetitively inhibits arachidonic acid acylation by rat acyl-CoA synthetase 4: relevance to valproate's efficacy against bipolar disorder. Biochim Biophys Acta Mol Cell Biol Lipids 2010; 1811:163-9. [PMID: 21184843 DOI: 10.1016/j.bbalip.2010.12.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Revised: 12/10/2010] [Accepted: 12/15/2010] [Indexed: 01/04/2023]
Abstract
BACKGROUND The ability of chronic valproate (VPA) to reduce arachidonic acid (AA) turnover in brain phospholipids of unanesthetized rats has been ascribed to its inhibition of acyl-CoA synthetase (Acsl)-mediated activation of AA to AA-CoA. Our aim was to identify a rat Acsl isoenzyme that could be inhibited by VPA in vitro. METHODS Rat Acsl3-, Acsl6v1- and Acsl6v2-, and Acsl4-flag proteins were expressed in E. coli, and the ability of VPA to inhibit their activation of long-chain fatty acids to acyl-CoA was estimated using Michaelis-Menten kinetics. RESULTS VPA uncompetitively inhibited Acsl4-mediated conversion of AA and of docosahexaenoic (DHA) but not of palmitic acid to acyl-CoA, but did not affect AA conversion by Acsl3, Acsl6v1 or Acsl6v2. Acsl4-mediated conversion of AA to AA-CoA showed substrate inhibition and had a 10-times higher catalytic efficiency than did conversion of DHA to DHA-CoA. Butyrate, octanoate, or lithium did not inhibit AA activation by Acsl4. CONCLUSIONS VPA's ability to inhibit Acsl4 activation of AA and of DHA to their respective acyl-CoAs, when related to the higher catalytic efficiency of AA than DHA conversion, may account for VPA's selective reduction of AA turnover in rat brain phospholipids, and contribute to VPA's efficacy against bipolar disorder.
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Affiliation(s)
- Jakob A Shimshoni
- National Institute on Aging, National Institutes of Health, Bethesda, MD, USA
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17
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Ludtmann MHR, Boeckeler K, Williams RSB. Molecular pharmacology in a simple model system: implicating MAP kinase and phosphoinositide signalling in bipolar disorder. Semin Cell Dev Biol 2010; 22:105-13. [PMID: 21093602 PMCID: PMC3032892 DOI: 10.1016/j.semcdb.2010.11.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 11/10/2010] [Accepted: 11/11/2010] [Indexed: 01/20/2023]
Abstract
Understanding the mechanisms of drug action has been the primary focus for pharmacological researchers, traditionally using rodent models. However, non-sentient model systems are now increasingly being used as an alternative approach to better understand drug action or targets. One of these model systems, the social amoeba Dictyostelium, enables the rapid ablation or over-expression of genes, and the subsequent use of isogenic cell culture for the analysis of cell signalling pathways in pharmacological research. The model also supports an increasingly important ethical view of research, involving the reduction, replacement and refinement of animals in biomedical research. This review outlines the use of Dictyostelium in understanding the pharmacological action of two commonly used bipolar disorder treatments (valproic acid and lithium). Both of these compounds regulate mitogen activated protein (MAP) kinase and inositol phospholipid-based signalling by unknown means. Analysis of the molecular pathways targeted by these drugs in Dictyostelium and translation of discoveries to animal systems has helped to further understand the molecular mechanisms of these bipolar disorder treatments.
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Affiliation(s)
- Marthe H R Ludtmann
- Centre for Biomedical Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, UK
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18
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Bialer M, White HS. Key factors in the discovery and development of new antiepileptic drugs. Nat Rev Drug Discov 2010; 9:68-82. [PMID: 20043029 DOI: 10.1038/nrd2997] [Citation(s) in RCA: 374] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Since the early 1990s, many new antiepileptic drugs (AEDs) that offer appreciable advantages in terms of their favourable pharmacokinetics, improved tolerability and lower potential for drug-drug interactions have entered the market. However, despite the therapeutic arsenal of old and new AEDs, approximately 30% of patients with epilepsy still suffer from seizures. Thus, there remains a substantial need for the development of more efficacious AEDs for patients with refractory seizures. Here, we briefly review the emerging knowledge on the pathological basis of epilepsy and how it might best be used in the design of new therapeutics. We also discuss the current approach to AED discovery and highlight some of the unique features of newer models of pharmacoresistance and epileptogenesis that have emerged in recent years.
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Affiliation(s)
- Meir Bialer
- Institute of Drug Research, School of Pharmacy, Faculty of Medicine, and the David R. Bloom Centre for Pharmacy, The Hebrew University of Jerusalem, Jerusalem, Israel.
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19
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Abstract
The anticonvulsant properties of VPA (valproic acid), a branched short-chain fatty acid, were serendipitously discovered in 1963. Since then, therapeutic roles of VPA have increased to include bipolar disorder and migraine prophylaxis, and have more recently been proposed in cancer, Alzheimer's disease and HIV treatment. These numerous therapeutic roles elevate VPA to near 'panacea' level. Surprisingly, the mechanisms of action of VPA in the treatment of many of these disorders remain unclear, although it has been shown to alter a wide variety of signalling pathways and a small number of direct targets. To analyse the mechanism of action of VPA, a number of studies have defined the structural characteristics of VPA-related compounds giving rise to distinct therapeutic and cellular effects, including adverse effects such as teratogenicity and hepatotoxicity. These studies raise the possibility of identifying target-specific novel compounds, providing better therapeutic action or reduced side effects. This short review will describe potential therapeutic pathways targeted by VPA, and highlight studies showing structural constraints necessary for these effects.
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20
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McVearry KM, Gaillard WD, VanMeter J, Meador KJ. A prospective study of cognitive fluency and originality in children exposed in utero to carbamazepine, lamotrigine, or valproate monotherapy. Epilepsy Behav 2009; 16:609-16. [PMID: 19892603 PMCID: PMC3692001 DOI: 10.1016/j.yebeh.2009.09.024] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Accepted: 09/30/2009] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To investigate the differential effects of fetal exposure to antiepileptic drugs (AEDs) on cognitive fluency and flexibility in a prospective sample of children. METHODS This substudy of the Neurodevelopmental Effects of Antiepileptic Drugs investigation enrolled pregnant women with epilepsy on AED monotherapy (carbamazepine, lamotrigine, and valproate). Blinded to drug exposure, 54 children were tested for ability to generate ideas in terms of quantity (fluency/flexibility) and quality (originality). Forty-two children met inclusion criteria (mean age=4.2 years, SD=0.5) for statistical analyses of drug exposure group differences. RESULTS Fluency was lower in the valproate group (mean=76.3, SD=7.53) versus the lamotrigine (mean=93.76, SD=13.5, ANOVA P<0.0015) and carbamazepine (mean=95.5, SD=18.1, ANOVA P<0.003) groups. Originality was lower in the valproate group (mean=84.2, SD=3.23) versus the lamotrigine (mean=103.1, SD=14.8, ANOVA P<0.002) and carbamazepine (mean=99.4, SD=17.1, ANOVA P<0.01) groups. These results were not explained by factors other than AED exposure. CONCLUSION Children prenatally exposed to valproate demonstrate impaired fluency and originality compared with children exposed to lamotrigine and carbamazepine.
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Affiliation(s)
- Kelly M McVearry
- Department of Neurology, Georgetown University Medical Center, Washington, DC 20007, USA.
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21
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Employing multiple models, methods and mechanisms in bipolar disorder research. Biochem Soc Trans 2009; 37:1077-9. [DOI: 10.1042/bst0371077] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
BD (bipolar disorder) is a devastating condition, giving rise to debilitating mood swings and a greatly increased likelihood of suicide. Research into the origins, progression and treatment of BD has been slow, primarily due to lack of suitable model systems for BD research. However, the complexity of the neurological basis for mood, variability in patient populations and the lack of clear readouts for BD diagnosis also provide significant problems for research in this area. In this Biochemical Society Focused Meeting, held at Royal Holloway University of London, approx. 40 national and international delegates met to discuss current research into understanding BD. The talks presented at this conference covered research examining the genetic basis of the disorder, changes in patient populations, pharmacological actions of BD drugs and the development of new models systems for this research. The focus of these talks and the following papers is to help to unify and disseminate research into this important but poorly understood medical condition.
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22
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PtdIns(3,4,5)P3 and inositol depletion as a cellular target of mood stabilizers. Biochem Soc Trans 2009; 37:1110-4. [DOI: 10.1042/bst0371110] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Lithium (Li+) is the mood stabilizer most frequently used in the treatment of bipolar mood disorder; however, its therapeutic mechanism is unknown. In the 1980s, Berridge and colleagues proposed that Li+ treatment acts via inhibition of IMPase (inositol monophosphatase) to deplete the cellular concentration of myo-inositol. Inositol depletion is also seen with the alternative mood stabilizers VPA (valproic acid) and CBZ (carbamazepine), suggesting a common therapeutic action. All three drugs cause changes in neuronal cell morphology and cell chemotaxis; however, it is unclear how reduced cellular inositol modulates these changes in cell behaviour. It is often assumed that reduced inositol suppresses Ins(1,4,5)P3, a major intracellular signal molecule, but there are other important phosphoinostide-based signal molecules in the cell. In the present paper, we discuss evidence that Li+ has a substantial effect on PtdIns(3,4,5)P3, an important signal molecule within the nervous system. As seen for Ins(1,4,5)P3 signalling, suppression of PtdIns(3,4,5)P3 signalling also occurs via an inositol-depletion mechanism. This has implications for the cellular mechanisms controlling phosphoinositide signalling, and offers insight into the genetics underlying risk of bipolar mood disorder.
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Shimshoni JA, Dalton EC, Watson P, Boris Y, Bialer M, Harwood AJ. Evaluation of the effects of propylisopropylacetic acid (PIA) on neuronal growth cone morphology. Neuropharmacology 2009; 56:831-7. [PMID: 19705552 PMCID: PMC3098385 DOI: 10.1016/j.neuropharm.2009.01.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Propylisopropylacetic acid (PIA) is a constitutional isomer of valproic acid (VPA). It has previously been found to be a weak antiepileptic, but in common with mood stabilizers, causes inositol depletion and growth cone spreading, suggesting the basis of a new series of mood stabilizers. To assess this possibility, we have compared the effects of racemic (R,S)-PIA and its individual enantiomers to those of the mood stabilizers lithium (Li+), VPA and carbamazepine (CBZ). Unlike Li+ and VPA, but in common with CBZ and (R,S)-PIA, neither (R)-PIA nor (S)-PIA enantiomer induces T-cell factor (TCF)-mediated gene expression. However, as seen for other mood stabilizers, both enantiomers are potent inducers of growth cone spreading. To investigate the mechanism for these effects, we examined changes in the actin cytoskeleton following drug treatment with Li+, VPA, CBZ, (R,S)-PIA or its individual enantiomers. All exhibit a redistribution of F-actin to the growth cone periphery, a feature of spread growth cones. (R,S)-PIA has the strongest effect as it also elevates F-actin polymerization at the cell periphery. This change in the actin cytoskeleton is associated with a substantial increase in F-actin-rich protrusions on the surface of the growth cone and in its close vicinity. These results demonstrate an effect of (R,S)-PIA on the neuronal actin cytoskeleton shared in common with other mood stabilizers, and suggest a potential to induce structural changes within the CNS.
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Affiliation(s)
- Jakob A Shimshoni
- Department of Pharmaceutics, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
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24
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King JS, Teo R, Ryves J, Reddy JV, Peters O, Orabi B, Hoeller O, Williams RSB, Harwood AJ. The mood stabiliser lithium suppresses PIP3 signalling in Dictyostelium and human cells. Dis Model Mech 2009; 2:306-12. [PMID: 19383941 DOI: 10.1242/dmm.001271] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Bipolar mood disorder (manic depression) is a major psychiatric disorder whose molecular origins are unknown. Mood stabilisers offer patients both acute and prophylactic treatment, and experimentally, they provide a means to probe the underlying biology of the disorder. Lithium and other mood stabilisers deplete intracellular inositol and it has been proposed that bipolar mood disorder arises from aberrant inositol (1,4,5)-trisphosphate [IP(3), also known as Ins(1,4,5)P(3)] signalling. However, there is no definitive evidence to support this or any other proposed target; a problem exacerbated by a lack of good cellular models. Phosphatidylinositol (3,4,5)-trisphosphate [PIP(3), also known as PtdIns(3,4,5)P(3)] is a prominent intracellular signal molecule within the central nervous system (CNS) that regulates neuronal survival, connectivity and synaptic function. By using the genetically tractable organism Dictyostelium, we show that lithium suppresses PIP(3)-mediated signalling. These effects extend to the human neutrophil cell line HL60. Mechanistically, we show that lithium attenuates phosphoinositide synthesis and that its effects can be reversed by overexpression of inositol monophosphatase (IMPase), consistent with the inositol-depletion hypothesis. These results demonstrate a lithium target that is compatible with our current knowledge of the genetic predisposition for bipolar disorder. They also suggest that lithium therapy might be beneficial for other diseases caused by elevated PIP(3) signalling.
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Affiliation(s)
- Jason S King
- Cardiff School of Biosciences, Cardiff University, Museum Avenue, Cardiff, UK
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25
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Bialer M, Johannessen SI, Levy RH, Perucca E, Tomson T, White HS. Progress report on new antiepileptic drugs: a summary of the Ninth Eilat Conference (EILAT IX). Epilepsy Res 2008; 83:1-43. [PMID: 19008076 DOI: 10.1016/j.eplepsyres.2008.09.005] [Citation(s) in RCA: 157] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Revised: 09/07/2008] [Accepted: 09/15/2008] [Indexed: 12/18/2022]
Abstract
The Ninth Eilat Conference on New Antiepileptic Drugs (AEDs)-EILAT IX, took place in Sitges, Barcelona from the 15th to 19th of June 2008. Over 300 basic scientists, clinical pharmacologists and neurologists from 25 countries attended the conference, whose main themes included old and new AEDs in generalized epilepsies, novel formulations and routes of administration of AEDs, common targets and mechanisms of action of drugs for treating epilepsy and other central nervous system (CNS) disorders, and opportunities and perspectives in new AED discovery. Consistent with previous formats of this conference, a large part of the programme was devoted to a review of AEDs in development, as well as updates on AEDs introduced since 1989. Unlike previous EILAT manuscripts, the current (EILAT IX) manuscript focuses only on the preclinical and clinical pharmacology of AEDs that are currently in development. These include brivaracetam, carisbamate (RWJ-333369), 2-deoxy-d-glucose, eslicarbazepine acetate (BIA-2-093), ganaxolone, huperzine, JZP-4, lacosamide, NAX-5055, propylisopropylacetamide (PID), retigabine, T-2000, tonabersat, valrocemide and YKP-3089. The CNS efficacy of these compounds in anticonvulsant animal models as well as other disease model systems are presented in first and second tables and their proposed mechanisms of action are summarized in the third table.
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Affiliation(s)
- Meir Bialer
- Department of Pharmaceutics, School of Pharmacy and David R. Bloom Centre for Pharmacy, Faculty of Medicine, Ein Karem, The Hebrew University of Jerusalem, 91120 Jerusalem, Israel.
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26
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Bassuk AG, Wallace RH, Buhr A, Buller AR, Afawi Z, Shimojo M, Miyata S, Chen S, Gonzalez-Alegre P, Griesbach HL, Wu S, Nashelsky M, Vladar EK, Antic D, Ferguson PJ, Cirak S, Voit T, Scott MP, Axelrod JD, Gurnett C, Daoud AS, Kivity S, Neufeld MY, Mazarib A, Straussberg R, Walid S, Korczyn AD, Slusarski DC, Berkovic SF, El-Shanti HI. A homozygous mutation in human PRICKLE1 causes an autosomal-recessive progressive myoclonus epilepsy-ataxia syndrome. Am J Hum Genet 2008; 83:572-81. [PMID: 18976727 DOI: 10.1016/j.ajhg.2008.10.003] [Citation(s) in RCA: 161] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Revised: 09/28/2008] [Accepted: 10/03/2008] [Indexed: 12/11/2022] Open
Abstract
Progressive myoclonus epilepsy (PME) is a syndrome characterized by myoclonic seizures (lightning-like jerks), generalized convulsive seizures, and varying degrees of neurological decline, especially ataxia and dementia. Previously, we characterized three pedigrees of individuals with PME and ataxia, where either clinical features or linkage mapping excluded known PME loci. This report identifies a mutation in PRICKLE1 (also known as RILP for REST/NRSF interacting LIM domain protein) in all three of these pedigrees. The identified PRICKLE1 mutation blocks the PRICKLE1 and REST interaction in vitro and disrupts the normal function of PRICKLE1 in an in vivo zebrafish overexpression system. PRICKLE1 is expressed in brain regions implicated in epilepsy and ataxia in mice and humans, and, to our knowledge, is the first molecule in the noncanonical WNT signaling pathway to be directly implicated in human epilepsy.
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27
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Xu X, Müller-Taubenberger A, Adley KE, Pawolleck N, Lee VWY, Wiedemann C, Sihra TS, Maniak M, Jin T, Williams RSB. Attenuation of phospholipid signaling provides a novel mechanism for the action of valproic acid. EUKARYOTIC CELL 2007; 6:899-906. [PMID: 17435006 PMCID: PMC1951516 DOI: 10.1128/ec.00104-06] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2006] [Accepted: 03/04/2007] [Indexed: 11/20/2022]
Abstract
Valproic acid (VPA) is used to treat epilepsy and bipolar disorder and to prevent migraine. It is also undergoing trials for cancer therapy. However, the biochemical and molecular biological actions of VPA are poorly understood. Using the social amoeba Dictyostelium discoideum, we show that an acute effect of VPA is the inhibition of chemotactic cell movement, a process partially dependent upon phospholipid signaling. Analysis of this process shows that VPA attenuates the signal-induced translocation of PH(Crac)-green fluorescent protein from cytosol to membrane, suggesting the inhibition of phosphatidylinositol-(3,4,5)-trisphosphate (PIP(3)) production. Direct labeling of lipids in vivo also shows a reduction in PIP and PIP(2) phosphorylation following VPA treatment. We further show that VPA acutely reduces endocytosis and exocytosis-processes previously shown to be dependent upon PIP(3) production. These results suggest that in Dictyostelium, VPA rapidly attenuates phospholipid signaling to reduce endocytic trafficking. To examine this effect in a mammalian model, we also tested depolarization-dependent neurotransmitter release in rat nerve terminals, and we show that this process is also suppressed upon application of VPA and an inhibitor of phosphatidylinositol 3-kinase. Although a more comprehensive analysis of the effect of VPA on lipid signaling will be necessary in mammalian systems, these results suggest that VPA may function to reduce phospholipid signaling processes and thus may provide a novel therapeutic effect for this drug.
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Affiliation(s)
- Xuehua Xu
- School of Biological Sciences, Royal Holloway University of London, Egham, United Kingdom
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