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Case KC, Beltman RJ, Pflum MKH, Greenberg ML. Valproate regulates inositol synthesis by reducing expression of myo-inositol-3-phosphate synthase. Sci Rep 2023; 13:14844. [PMID: 37684289 PMCID: PMC10491628 DOI: 10.1038/s41598-023-41936-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Accepted: 09/04/2023] [Indexed: 09/10/2023] Open
Abstract
Inositol depletion is a hypothesized mechanism of action of mood stabilization drugs used in the treatment of bipolar disorder. It was previously reported that the mood stabilizer valproate (VPA) increased phosphorylation of myo-inositol-3-phosphate synthases (MIPS), the rate limiting enzyme of inositol synthesis. Phosphosites were identified and examination of site-directed mutants suggested that phosphorylation leads to decreased enzymatic activity. In this study, we examined the extent of MIPS phosphorylation in response to VPA and used two interaction screens to identify protein kinases that interact with MIPS. Using an epitope tagged MIPS construct, we determined the fraction of phosphorylated MIPS to be very low (less than 2% of total), and we could not detect phosphorylation of untagged MIPS in response to VPA. In vitro analyses of phosphorylation revealed that putative protein kinases, PKC and CKII, have low specificity toward MIPS. These findings suggest that VPA likely depletes inositol via a mechanism other than MIPS phosphorylation. Consistent with this, mRNA levels of the MIPS-encoding gene INO1 and MIPS protein levels were significantly reduced during the mid-log growth phase in response to VPA treatment. These findings suggest that the mechanism whereby VPA causes inositol depletion is by reducing expression of the rate-limiting enzyme MIPS.
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Affiliation(s)
- Kendall C Case
- Department of Biological Sciences, Wayne State University, Detroit, MI, 48202, USA
| | - Rachel J Beltman
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
| | - Mary Kay H Pflum
- Department of Chemistry, 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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2
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López-Gambero AJ, Sanjuan C, Serrano-Castro PJ, Suárez J, Rodríguez de Fonseca F. The Biomedical Uses of Inositols: A Nutraceutical Approach to Metabolic Dysfunction in Aging and Neurodegenerative Diseases. Biomedicines 2020; 8:biomedicines8090295. [PMID: 32825356 PMCID: PMC7554709 DOI: 10.3390/biomedicines8090295] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 08/17/2020] [Accepted: 08/18/2020] [Indexed: 02/05/2023] Open
Abstract
Inositols are sugar-like compounds that are widely distributed in nature and are a part of membrane molecules, participating as second messengers in several cell-signaling processes. Isolation and characterization of inositol phosphoglycans containing myo- or d-chiro-inositol have been milestones for understanding the physiological regulation of insulin signaling. Other functions of inositols have been derived from the existence of multiple stereoisomers, which may confer antioxidant properties. In the brain, fluctuation of inositols in extracellular and intracellular compartments regulates neuronal and glial activity. Myo-inositol imbalance is observed in psychiatric diseases and its use shows efficacy for treatment of depression, anxiety, and compulsive disorders. Epi- and scyllo-inositol isomers are capable of stabilizing non-toxic forms of β-amyloid proteins, which are characteristic of Alzheimer’s disease and cognitive dementia in Down’s syndrome, both associated with brain insulin resistance. However, uncertainties of the intrinsic mechanisms of inositols regarding their biology are still unsolved. This work presents a critical review of inositol actions on insulin signaling, oxidative stress, and endothelial dysfunction, and its potential for either preventing or delaying cognitive impairment in aging and neurodegenerative diseases. The biomedical uses of inositols may represent a paradigm in the industrial approach perspective, which has generated growing interest for two decades, accompanied by clinical trials for Alzheimer’s disease.
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Affiliation(s)
- Antonio J. López-Gambero
- Departamento de Biología Celular, Genética y Fisiología, Campus de Teatinos s/n, Universidad de Málaga, Andalucia Tech, 29071 Málaga, Spain;
- UGC Salud Mental, Instituto de Investigación Biomédica de Málaga (IBIMA), Hospital Universitario Regional de Málaga, 29010 Málaga, Spain
| | | | - Pedro Jesús Serrano-Castro
- UGC Neurología, Instituto de Investigación Biomédica de Málaga (IBIMA), Hospital Universitario Regional de Málaga, 29010 Málaga, Spain;
| | - Juan Suárez
- UGC Salud Mental, Instituto de Investigación Biomédica de Málaga (IBIMA), Hospital Universitario Regional de Málaga, 29010 Málaga, Spain
- Correspondence: (J.S.); (F.R.d.F.); Tel.: +34-952614012 (J.S.)
| | - Fernando Rodríguez de Fonseca
- UGC Salud Mental, Instituto de Investigación Biomédica de Málaga (IBIMA), Hospital Universitario Regional de Málaga, 29010 Málaga, Spain
- Correspondence: (J.S.); (F.R.d.F.); Tel.: +34-952614012 (J.S.)
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Case KC, Salsaa M, Yu W, Greenberg ML. Regulation of Inositol Biosynthesis: Balancing Health and Pathophysiology. Handb Exp Pharmacol 2020; 259:221-260. [PMID: 30591968 DOI: 10.1007/164_2018_181] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Inositol is the precursor for all inositol compounds and is essential for viability of eukaryotic cells. Numerous cellular processes and signaling functions are dependent on inositol compounds, and perturbation of their synthesis leads to a wide range of human diseases. Although considerable research has been directed at understanding the function of inositol compounds, especially phosphoinositides and inositol phosphates, a focus on regulatory and homeostatic mechanisms controlling inositol biosynthesis has been largely neglected. Consequently, little is known about how synthesis of inositol is regulated in human cells. Identifying physiological regulators of inositol synthesis and elucidating the molecular mechanisms that regulate inositol synthesis will contribute fundamental insight into cellular processes that are mediated by inositol compounds and will provide a foundation to understand numerous disease processes that result from perturbation of inositol homeostasis. In addition, elucidating the mechanisms of action of inositol-depleting drugs may suggest new strategies for the design of second-generation pharmaceuticals to treat psychiatric disorders and other illnesses.
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Affiliation(s)
- Kendall C Case
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
| | - Michael Salsaa
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
| | - Wenxi Yu
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Miriam L Greenberg
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA.
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Ni Y, Li G, Ji X, Yang Y, Guo X, Sun Q. Identification of an inositol-3-phosphate synthase 1-B gene (AccIPS1-B) from Apis cerana cerana and its role in abiotic stress. Cell Stress Chaperones 2019; 24:1101-1113. [PMID: 31512154 PMCID: PMC6882988 DOI: 10.1007/s12192-019-01032-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 08/07/2019] [Accepted: 08/26/2019] [Indexed: 02/03/2023] Open
Abstract
Inositol phosphate synthase (IPS) is a rate-limiting enzyme in myo-inositol biosynthesis, which can regulate stress responses in plants and animals. However, there are few studies on the function of IPS in insects, especially in Apis cerana cerana. In this study, the inositol-3-phosphate synthase 1-B gene (AccIPS1-B) was isolated from Apis cerana cerana, and its connection to antioxidant defence was investigated. The open reading frame of AccIPS1-B was 1542 bp, encoding a 513 amino acid polypeptide. Quantitative real-time PCR analysis revealed that the expression level of AccIPS1-B was highest in pupae of Apis cerana cerana, and it was expressed at higher levels in the thorax than in other tissues tested. Moreover, the expression of AccIPS1-B was significantly upregulated by abiotic stresses. The recombinant AccIPS1-B also displayed significant tolerance to cumene hydroperoxide and HgCl2. In addition, knockdown of AccIPS1-B significantly suppressed the expression of most of the antioxidant genes and decreased the antioxidant enzymatic activities of SOD, POD, and GST. Taken together, these findings indicate that AccIPS1-B may be involved in the response to antioxidant defence and development in Apis cerana cerana.
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Affiliation(s)
- Yong Ni
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, Shandong, People's Republic of China
| | - Guilin Li
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, Shandong, People's Republic of China
| | - Xiaomin Ji
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, Shandong, People's Republic of China
| | - Yaqian Yang
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, Shandong, People's Republic of China
| | - Xingqi Guo
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, Shandong, People's Republic of China.
| | - Qinghua Sun
- State Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Taian, 271018, Shandong, People's Republic of China.
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Yu W, Daniel J, Mehta D, Maddipati KR, Greenberg ML. MCK1 is a novel regulator of myo-inositol phosphate synthase (MIPS) that is required for inhibition of inositol synthesis by the mood stabilizer valproate. PLoS One 2017; 12:e0182534. [PMID: 28817575 PMCID: PMC5560674 DOI: 10.1371/journal.pone.0182534] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 07/19/2017] [Indexed: 12/28/2022] Open
Abstract
Myo-inositol, the precursor of all inositol compounds, is essential for the viability of eukaryotes. Identifying the factors that regulate inositol homeostasis is of obvious importance to understanding cell function and the pathologies underlying neurological and metabolic resulting from perturbation of inositol metabolism. The current study identifies Mck1, a GSK3 homolog, as a novel positive regulator of inositol de novo synthesis in yeast. Mck1 was required for normal activity of myo-inositol phosphate synthase (MIPS), which catalyzes the rate-limiting step of inositol synthesis. mck1Δ cells exhibited a 50% decrease in MIPS activity and a decreased rate of incorporation of [13C6]glucose into [13C6]-inositol-3-phosphate and [13C6]-inositol compared to WT cells. mck1Δ cells also exhibited decreased growth in the presence of the inositol depleting drug valproate (VPA), which was rescued by supplementation of inositol. However, in contrast to wild type cells, which exhibited more than a 40% decrease in MIPS activity in the presence of VPA, the drug did not significantly decrease MIPS activity in mck1Δ cells. These findings indicate that VPA-induced MIPS inhibition is Mck1-dependent, and suggest a model that unifies two current hypotheses of the mechanism of action of VPA—inositol depletion and GSK3 inhibition.
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Affiliation(s)
- Wenxi Yu
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, United States of America
| | - Joshua Daniel
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, United States of America
| | - Dhara Mehta
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, United States of America
| | - Krishna Rao Maddipati
- Department of Pathology, Wayne State University, Detroit, Michigan, United States of America
| | - Miriam L. Greenberg
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, United States of America
- * E-mail:
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Tipping the scales: Lessons from simple model systems on inositol imbalance in neurological disorders. Eur J Cell Biol 2017; 96:154-163. [PMID: 28153412 DOI: 10.1016/j.ejcb.2017.01.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 01/18/2017] [Accepted: 01/21/2017] [Indexed: 11/20/2022] Open
Abstract
Inositol and inositol-containing compounds have signalling and regulatory roles in many cellular processes, suggesting that inositol imbalance may lead to wide-ranging changes in cellular functions. Indeed, changes in inositol-dependent signalling have been implicated in various diseases and cellular functions such as autophagy, and these changes have often been proposed as therapeutic targets. However, few studies have highlighted the links between inositol depletion and the downstream effects on inositol phosphates and phosphoinositides in disease states. For this research, many advances have employed simple model systems that include the social amoeba D. discoideum and the yeast S. cerevisiae, since these models enable a range of experimental approaches that are not possible in mammalian models. In this review, we discuss recent findings initiated in simple model systems and translated to higher model organisms where the effect of altered inositol, inositol phosphate and phosphoinositide levels impact on bipolar disorder, Alzheimer disease, epilepsy and autophagy.
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Jadhav S, Russo S, Cottier S, Schneiter R, Cowart A, Greenberg ML. Valproate Induces the Unfolded Protein Response by Increasing Ceramide Levels. J Biol Chem 2016; 291:22253-22261. [PMID: 27590340 DOI: 10.1074/jbc.m116.752634] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Indexed: 11/06/2022] Open
Abstract
Bipolar disorder (BD), which is characterized by depression and mania, affects 1-2% of the world population. Current treatments are effective in only 40-60% of cases and cause severe side effects. Valproate (VPA) is one of the most widely used drugs for the treatment of BD, but the therapeutic mechanism of action of this drug is not understood. This knowledge gap has hampered the development of effective treatments. To identify candidate pathways affected by VPA, we performed a genome-wide expression analysis in yeast cells grown in the presence or absence of the drug. VPA caused up-regulation of FEN1 and SUR4, encoding fatty acid elongases that catalyze the synthesis of very long chain fatty acids (C24 to C26) required for ceramide synthesis. Interestingly, fen1Δ and sur4Δ mutants exhibited VPA sensitivity. In agreement with increased fatty acid elongase gene expression, VPA increased levels of phytoceramide, especially those containing C24-C26 fatty acids. Consistent with an increase in ceramide, VPA decreased the expression of amino acid transporters, increased the expression of ER chaperones, and activated the unfolded protein response element (UPRE), suggesting that VPA induces the UPR pathway. These effects were rescued by supplementation of inositol and similarly observed in inositol-starved ino1Δ cells. Starvation of ino1Δ cells increased expression of FEN1 and SUR4, increased ceramide levels, decreased expression of nutrient transporters, and induced the UPR. These findings suggest that VPA-mediated inositol depletion induces the UPR by increasing the de novo synthesis of ceramide.
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Affiliation(s)
- Shyamalagauri Jadhav
- From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202
| | - Sarah Russo
- the Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425, the Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401, and
| | - Stéphanie Cottier
- the Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Roger Schneiter
- the Department of Biology, University of Fribourg, 1700 Fribourg, Switzerland
| | - Ashley Cowart
- the Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425, the Ralph H. Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29401, and
| | - Miriam L Greenberg
- From the Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202,
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Kalujnaia S, Hazon N, Cramb G. Myo-inositol phosphate synthase expression in the European eel (Anguilla anguilla) and Nile tilapia (Oreochromis niloticus): effect of seawater acclimation. Am J Physiol Regul Integr Comp Physiol 2016; 311:R287-98. [PMID: 27252471 PMCID: PMC5008666 DOI: 10.1152/ajpregu.00056.2016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 05/25/2016] [Indexed: 11/29/2022]
Abstract
A single MIPS gene (Isyna1/Ino1) exists in eel and tilapia genomes with a single myo-d-inositol 3-phosphate synthase (MIPS) transcript identified in all eel tissues, although two MIPS spliced variants [termed MIPS(s) and MIPS(l)] are found in all tilapia tissues. The larger tilapia transcript [MIPS(l)] results from the inclusion of the 87-nucleotide intron between exons 5 and 6 in the genomic sequence. In most tilapia tissues, the MIPS(s) transcript exhibits much higher abundance (generally >10-fold) with the exception of white skeletal muscle and oocytes, in which the MIPS(l) transcript predominates. SW acclimation resulted in large (6- to 32-fold) increases in mRNA expression for both MIPS(s) and MIPS(l) in all tilapia tissues tested, whereas in the eel, changes in expression were limited to a more modest 2.5-fold increase and only in the kidney. Western blots identified a number of species- and tissue-specific immunoreactive MIPS proteins ranging from 40 to 67 kDa molecular weight. SW acclimation failed to affect the abundance of any immunoreactive protein in any tissue tested from the eel. However, a major 67-kDa immunoreactive protein (presumed to be MIPS) found in tilapia tissues exhibited 11- and 54-fold increases in expression in gill and fin samples from SW-acclimated fish. Immunohistochemical investigations revealed specific immunoreactivity in the gill, fin, skin, and intestine taken from only SW-acclimated tilapia. Immunofluorescence indicated that MIPS was expressed within gill chondrocytes and epithelial cells of the primary filaments, basal epithelial cell layers of the skin and fin, the cytosol of columnar intestinal epithelial and mucous cells, as well as unknown entero-endocrine-like cells.
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Affiliation(s)
- Svetlana Kalujnaia
- School of Medicine, University of St. Andrews, St. Andrews, United Kingdom; and
| | - Neil Hazon
- School of Biology, University of St. Andrews, St. Andrews, United Kingdom
| | - Gordon Cramb
- School of Medicine, University of St. Andrews, St. Andrews, United Kingdom; and
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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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KOGUCHI TOMOYUKI, TANIKAWA CHIZU, MORI JINICHI, KOJIMA YOSHIYUKI, MATSUDA KOICHI. Regulation of myo-inositol biosynthesis by p53-ISYNA1 pathway. Int J Oncol 2016; 48:2415-24. [DOI: 10.3892/ijo.2016.3456] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 02/25/2016] [Indexed: 11/05/2022] Open
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