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Doboszewska U, Sawicki J, Sajnóg A, Szopa A, Serefko A, Socała K, Pieróg M, Nieoczym D, Mlyniec K, Nowak G, Barałkiewicz D, Sowa I, Wlaź P. Alterations of Serum Magnesium Concentration in Animal Models of Seizures and Epilepsy—The Effects of Treatment with a GPR39 Agonist and Knockout of the Gpr39 Gene. Cells 2022; 11:cells11131987. [PMID: 35805072 PMCID: PMC9265460 DOI: 10.3390/cells11131987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 06/14/2022] [Indexed: 12/10/2022] Open
Abstract
Several ligands have been proposed for the GPR39 receptor, including the element zinc. The relationship between GPR39 and magnesium homeostasis has not yet been examined, nor has such a relationship in the context of seizures/epilepsy. We used samples from mice that were treated with an agonist of the GPR39 receptor (TC-G 1008) and underwent acute seizures (maximal electroshock (MES)- or 6-hertz-induced seizures) or a chronic, pentylenetetrazole (PTZ)-induced kindling model of epilepsy. MES seizures and PTZ kindling, unlike 6 Hz seizures, increased serum magnesium concentration. In turn, Gpr39-KO mice that underwent PTZ kindling displayed decreased concentrations of this element in serum, compared to WT mice subjected to this procedure. However, the levels of expression of TRPM7 and SlC41A1 proteins—which are responsible for magnesium transport into and out of cells, respectively—did not differ in the hippocampus between Gpr39-KO and WT mice. Furthermore, laser ablation inductively coupled plasma mass spectrometry applied to hippocampal slices did not reveal differences in magnesium levels between the groups. These data show the relationship between magnesium homeostasis and certain types of acute or chronic seizures (MES seizures or PTZ kindling, respectively), but do not explicitly support the role of GPR39 in mediating magnesium balance in the hippocampus in the latter model. However, decreased expression of TRPM7 and increased expression of SLC41A1—which were observed in the hippocampi of Gpr39-KO mice treated with TC-G 1008, in comparison to WT mice that received the same treatment—implicitly support the link between GPR39 and hippocampal magnesium homeostasis.
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Affiliation(s)
- Urszula Doboszewska
- Department of Animal Physiology and Pharmacology, Institute of Biological Sciences, Maria Curie-Skłodowska University, Akademicka 19, PL 20-033 Lublin, Poland; (K.S.); (M.P.); (D.N.); (P.W.)
- Department of Pharmacobiology, Jagiellonian University Medical College, Medyczna 9, PL 30-688 Kraków, Poland; (K.M.); (G.N.)
- Correspondence: or ; Tel.: +48-81-537-50-10; Fax: +48-81-537-59-01
| | - Jan Sawicki
- Department of Analytical Chemistry, Medical University of Lublin, Chodźki 4A, PL 20-093 Lublin, Poland; (J.S.); (I.S.)
| | - Adam Sajnóg
- Department of Trace Analysis, Adam Mickiewicz University, Uniwersytetu Poznanskiego 8, PL 61-614 Poznan, Poland; (A.S.); (D.B.)
| | - Aleksandra Szopa
- Chair and Department of Applied and Social Pharmacy, Laboratory of Preclinical Testing, Medical University of Lublin, Chodźki 1, PL 20-093 Lublin, Poland; (A.S.); (A.S.)
| | - Anna Serefko
- Chair and Department of Applied and Social Pharmacy, Laboratory of Preclinical Testing, Medical University of Lublin, Chodźki 1, PL 20-093 Lublin, Poland; (A.S.); (A.S.)
| | - Katarzyna Socała
- Department of Animal Physiology and Pharmacology, Institute of Biological Sciences, Maria Curie-Skłodowska University, Akademicka 19, PL 20-033 Lublin, Poland; (K.S.); (M.P.); (D.N.); (P.W.)
| | - Mateusz Pieróg
- Department of Animal Physiology and Pharmacology, Institute of Biological Sciences, Maria Curie-Skłodowska University, Akademicka 19, PL 20-033 Lublin, Poland; (K.S.); (M.P.); (D.N.); (P.W.)
| | - Dorota Nieoczym
- Department of Animal Physiology and Pharmacology, Institute of Biological Sciences, Maria Curie-Skłodowska University, Akademicka 19, PL 20-033 Lublin, Poland; (K.S.); (M.P.); (D.N.); (P.W.)
| | - Katarzyna Mlyniec
- Department of Pharmacobiology, Jagiellonian University Medical College, Medyczna 9, PL 30-688 Kraków, Poland; (K.M.); (G.N.)
| | - Gabriel Nowak
- Department of Pharmacobiology, Jagiellonian University Medical College, Medyczna 9, PL 30-688 Kraków, Poland; (K.M.); (G.N.)
- Department of Neurobiology, Maj Institute of Pharmacology, Polish Academy of Sciences, Smetna 12, PL 31-343 Kraków, Poland
| | - Danuta Barałkiewicz
- Department of Trace Analysis, Adam Mickiewicz University, Uniwersytetu Poznanskiego 8, PL 61-614 Poznan, Poland; (A.S.); (D.B.)
| | - Ireneusz Sowa
- Department of Analytical Chemistry, Medical University of Lublin, Chodźki 4A, PL 20-093 Lublin, Poland; (J.S.); (I.S.)
| | - Piotr Wlaź
- Department of Animal Physiology and Pharmacology, Institute of Biological Sciences, Maria Curie-Skłodowska University, Akademicka 19, PL 20-033 Lublin, Poland; (K.S.); (M.P.); (D.N.); (P.W.)
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El-Khodor BF, James K, Chang Q, Zhang W, Loiselle YR, Panda C, Hanania T. Elevation of brain magnesium with Swiss chard and buckwheat extracts in an animal model of reduced magnesium dietary intake. Nutr Neurosci 2021; 25:2638-2649. [PMID: 34730480 DOI: 10.1080/1028415x.2021.1995119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
OBJECTIVES Inadequate dietary magnesium (Mg) intake is a growing public health concern. Mg is critical for diverse metabolic processes including energy production, macromolecule biosynthesis, and electrolyte homeostasis. Inadequate free Mg2+ ion concentration ([Mg2+]) in the brain is associated with several neurological and behavioral disorders. Elevating [Mg2+]in the brain using oral Mg supplementation has proven to be challenging due to the tight regulation of Mg2+ transport to the brain. This study explored the effect of short-term moderate reduction in dietary Mg intake (87% of normal Mg diet for 30 days) on [Mg2+] in the cerebrospinal fluid (CSF) ([Mg2+]CSF) and red blood cells (RBCs) ([Mg2+]RBC) in adult male rats. In addition, we investigated the effectiveness of magnesium-rich blend of Swiss chard and buckwheat extracts (SC/BW extract) in increasing brain [Mg2+] compared to various Mg salts commonly used as dietary supplements. METHODS Animals were assigned to either normal or low Mg diet for 30 - 45 days. Following this, animals maintained on low Mg diet were supplemented with various Mg compounds. [Mg2+]CSF and [Mg2+]RBC were measured at baseline and following Mg administration. Anxiety-like behavior and cognitive function were also evaluated. RESULTS The present study showed that a short-term and moderate reduction in Mg dietary intake results in a significant decline in [Mg2+]CSF and [Mg2+]RBC and the emergence of anxiety-like behavior in comparison to animals maintained on normal Mg diet. Supplementation with SC/BW extract significantly elevated [Mg2+]CSF and improved animal performance in the novel object recognition test in comparison with animals maintained on reduced Mg intake and supplemented with various Mg compounds. DISCUSSION These observations indicate that brain [Mg2+] is more sensitive to a short-term and moderate reduction in Mg dietary intake than previously thought and emphasizes the importance of dietary Mg in replenishing brain Mg2+ reserves.
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Affiliation(s)
| | - Karma James
- Nutrition Innovation Center, Standard Process Inc., Kannapolis, NC, USA
| | | | - Wei Zhang
- Nutrition Innovation Center, Standard Process Inc., Kannapolis, NC, USA
| | - Yvette R Loiselle
- Nutrition Innovation Center, Standard Process Inc., Kannapolis, NC, USA
| | - Chinmayee Panda
- Nutrition Innovation Center, Standard Process Inc., Kannapolis, NC, USA
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Liu S, Abboud MI, John T, Mikhailov V, Hvinden I, Walsby-Tickle J, Liu X, Pettinati I, Cadoux-Hudson T, McCullagh JSO, Schofield CJ. Roles of metal ions in the selective inhibition of oncogenic variants of isocitrate dehydrogenase 1. Commun Biol 2021; 4:1243. [PMID: 34725432 PMCID: PMC8560763 DOI: 10.1038/s42003-021-02743-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Accepted: 10/04/2021] [Indexed: 12/29/2022] Open
Abstract
Cancer linked isocitrate dehydrogenase (IDH) 1 variants, notably R132H IDH1, manifest a 'gain-of-function' to reduce 2-oxoglutarate to 2-hydroxyglutarate. High-throughput screens have enabled clinically useful R132H IDH1 inhibitors, mostly allosteric binders at the dimer interface. We report investigations on roles of divalent metal ions in IDH substrate and inhibitor binding that rationalise this observation. Mg2+/Mn2+ ions enhance substrate binding to wt IDH1 and R132H IDH1, but with the former manifesting lower Mg2+/Mn2+ KMs. The isocitrate-Mg2+ complex is the preferred wt IDH1 substrate; with R132H IDH1, separate and weaker binding of 2-oxoglutarate and Mg2+ is preferred. Binding of R132H IDH1 inhibitors at the dimer interface weakens binding of active site Mg2+ complexes; their potency is affected by the Mg2+ concentration. Inhibitor selectivity for R132H IDH1 over wt IDH1 substantially arises from different stabilities of wt and R132H IDH1 substrate-Mg2+ complexes. The results reveal the importance of substrate-metal ion complexes in wt and R132H IDH1 catalysis and the basis for selective R132H IDH1 inhibition. Further studies on roles of metal ion complexes in TCA cycle and related metabolism, including from an evolutionary perspective, are of interest.
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Affiliation(s)
- Shuang Liu
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
- Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, MA, 02142, USA
| | - Martine I Abboud
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
- Department of Natural Sciences, Lebanese American University, Byblos/Beirut, Lebanon
| | - Tobias John
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Victor Mikhailov
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Ingvild Hvinden
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - John Walsby-Tickle
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Xiao Liu
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Ilaria Pettinati
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Tom Cadoux-Hudson
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - James S O McCullagh
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Christopher J Schofield
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
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Shen Y, Dai L, Tian H, Xu R, Li F, Li Z, Zhou J, Wang L, Dong J, Sun L. Treatment Of Magnesium-L-Threonate Elevates The Magnesium Level In The Cerebrospinal Fluid And Attenuates Motor Deficits And Dopamine Neuron Loss In A Mouse Model Of Parkinson's disease. Neuropsychiatr Dis Treat 2019; 15:3143-3153. [PMID: 31806980 PMCID: PMC6857673 DOI: 10.2147/ndt.s230688] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 10/28/2019] [Indexed: 12/13/2022] Open
Abstract
PURPOSE Epidemiology research has demonstrated that magnesium (Mg) deficiency is associated with a high incidence of Parkinson's disease (PD). It is known that the systemic administration of MgSO4 is not able to elevate the Mg concentration in cerebrospinal fluid (CSF). This study aims to verify the protective effect of magnesium-L-threonate (MgT) in 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) mouse model. METHODS C57BL/6J mice were orally administered MgT or MgSO4 for 4 weeks, and received MPTP in the third week. After analysis of open-field and rotarod tests on the last day, tyrosine hydroxylase (TH) immunopositive cells and protein levels were quantified in the substantia nigra pars compacta (SNpc) and striatum. The expression of inducible nitric oxide synthase (iNOS) level was evaluated. Mg concentration in serum and CSF was measured after oral administration of MgSO4 or MgT in normal mice. Mg concentration in the CSF was increased in the mice treated with MgT but not MgSO4. RESULTS The total distance and mean speed in open-field tests, and the time spent on rotarod in the MgT group were increased, compared with MPTP group. The MgT treatment but not MgSO4 dose-dependently attenuated the loss of TH-positive neurons, and the reduction of the TH expression in the SNpc. The MgT treatment also inhibited the expression of iNOS as measured by immunohistochemistry and Western blots. Double-immunofluorescence staining of TH and iNOS showed iNOS-positive cells were collocalized for TH-positive cells. CONCLUSION The treatment with MgT is associated with an increase of Mg in the CSF. MgT, rather than MgSO4, can significantly attenuate MPTP-induced motor deficits and dopamine (DA) neuron loss.
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Affiliation(s)
- Yanling Shen
- Department of Guangxi Key Laboratory of Brain and Cognitive Neuroscience, Guilin Medical University, Guilin541004, Guangxi, People’s Republic of China
- Department of Pathology, Affiliated Chenggong Hospital, Xiamen University, Xiamen, Fujian361000, People’s Republic of China
| | - Ling Dai
- Department of Guangxi Key Laboratory of Brain and Cognitive Neuroscience, Guilin Medical University, Guilin541004, Guangxi, People’s Republic of China
| | - Haibo Tian
- Department of Guangxi Key Laboratory of Brain and Cognitive Neuroscience, Guilin Medical University, Guilin541004, Guangxi, People’s Republic of China
- Department of Pathology, Fuling Central Hospital of Chongqing City, Chongqing408099, People’s Republic of China
| | - Runnan Xu
- Department of Guangxi Key Laboratory of Brain and Cognitive Neuroscience, Guilin Medical University, Guilin541004, Guangxi, People’s Republic of China
| | - Fuying Li
- Department of Neurology and Neurological Science, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Zhuohang Li
- Department of Guangxi Key Laboratory of Brain and Cognitive Neuroscience, Guilin Medical University, Guilin541004, Guangxi, People’s Republic of China
| | - Jeremy Zhou
- School of Pharmacy and Medical Sciences, and UniSA Cancer Research Institute, University of South Australia, Adelaide, SA5001, Australia
| | - Liping Wang
- School of Pharmacy and Medical Sciences, and UniSA Cancer Research Institute, University of South Australia, Adelaide, SA5001, Australia
| | - Jianghui Dong
- Department of Guangxi Key Laboratory of Brain and Cognitive Neuroscience, Guilin Medical University, Guilin541004, Guangxi, People’s Republic of China
- School of Pharmacy and Medical Sciences, and UniSA Cancer Research Institute, University of South Australia, Adelaide, SA5001, Australia
| | - Liyuan Sun
- Department of Guangxi Key Laboratory of Brain and Cognitive Neuroscience, Guilin Medical University, Guilin541004, Guangxi, People’s Republic of China
- Department of Neurology and Neurological Science, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
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Guilliam TA, Doherty AJ. PrimPol-Prime Time to Reprime. Genes (Basel) 2017; 8:genes8010020. [PMID: 28067825 PMCID: PMC5295015 DOI: 10.3390/genes8010020] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 12/09/2016] [Accepted: 12/16/2016] [Indexed: 01/16/2023] Open
Abstract
The complex molecular machines responsible for genome replication encounter many obstacles during their progression along DNA. Tolerance of these obstructions is critical for efficient and timely genome duplication. In recent years, primase-polymerase (PrimPol) has emerged as a new player involved in maintaining eukaryotic replication fork progression. This versatile replicative enzyme, a member of the archaeo-eukaryotic primase (AEP) superfamily, has the capacity to perform a range of template-dependent and independent synthesis activities. Here, we discuss the emerging roles of PrimPol as a leading strand repriming enzyme and describe the mechanisms responsible for recruiting and regulating the enzyme during this process. This review provides an overview and update of the current PrimPol literature, as well as highlighting unanswered questions and potential future avenues of investigation.
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Affiliation(s)
- Thomas A Guilliam
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK.
| | - Aidan J Doherty
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK.
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Gening LV, Lakhin AV, Makarova IV, Nenasheva VV, Andreeva LE, Tarantul VZ. Alterations in Synthesis and Repair of DNA during the Development of Loach Misgurnus fossilis. J Dev Biol 2016; 4:jdb4010006. [PMID: 29615575 PMCID: PMC5831811 DOI: 10.3390/jdb4010006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 01/18/2016] [Accepted: 01/20/2016] [Indexed: 01/01/2023] Open
Abstract
Using a modified radiolabeled primer extension method (we named this modification misGvA—“misincorporation of G versus A”) we have investigated the DNA synthesis and repair at early and late stages of development of loach Misgurnus fossilis. The misincorporation activity of DNA polymerase iota (Pol ι) in wild-type loach could not be detected by this method at any stage of loach development. In transgenic loach overexpressing human Pol ι we have shown that the bypassing of DNA synthesis arrest after incorporation of mismatched nucleotide by Pol ι (the T-stop) was not associated with this enzyme. Non-transgenic loach larvae are virtually lacking the capacity for error correction of DNA duplex containing a mismatched nucleotide. Such repair activity develops only in the adult fish. It appears that the initial stages of development are characterized by more intensive DNA synthesis, while in terminal stages the repair activities become more prominent. The misGvA approach clearly indicates substantial changes in the DNA synthesis intensity, although the role of particular replicative and repair DNA polymerases in this process requires further study.
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Affiliation(s)
- Leonid V Gening
- Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Square, 123182 Moscow, Russia.
| | - Andrei V Lakhin
- Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Square, 123182 Moscow, Russia.
| | - Irina V Makarova
- Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Square, 123182 Moscow, Russia.
| | - Valentina V Nenasheva
- Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Square, 123182 Moscow, Russia.
| | - Ludmila E Andreeva
- Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Square, 123182 Moscow, Russia.
| | - Vyacheslav Z Tarantul
- Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Square, 123182 Moscow, Russia.
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Achuthan V, Keith BJ, Connolly BA, DeStefano JJ. Human immunodeficiency virus reverse transcriptase displays dramatically higher fidelity under physiological magnesium conditions in vitro. J Virol 2014; 88:8514-27. [PMID: 24850729 PMCID: PMC4135932 DOI: 10.1128/jvi.00752-14] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 05/15/2014] [Indexed: 12/24/2022] Open
Abstract
UNLABELLED The fidelity of human immunodeficiency virus (HIV) reverse transcriptase (RT) has been a subject of intensive investigation. The mutation frequencies for the purified enzyme in vitro vary widely but are typically in the 10(-4) range (per nucleotide addition), making the enzyme severalfold less accurate than most polymerases, including other RTs. This has often been cited as a factor in HIV's accelerated generation of genetic diversity. However, cellular experiments suggest that HIV does not have significantly lower fidelity than other retroviruses and shows a mutation frequency in the 10(-5) range. In this report, we reconcile, at least in part, these discrepancies by showing that HIV RT fidelity in vitro is in the same range as cellular results from experiments conducted with physiological (for lymphocytes) concentrations of free Mg(2+) (~0.25 mM) and is comparable to Moloney murine leukemia virus (MuLV) RT fidelity. The physiological conditions produced mutation rates that were 5 to 10 times lower than those obtained under typically employed in vitro conditions optimized for RT activity (5 to 10 mM Mg(2+)). These results were consistent in both commonly used lacZα complementation and steady-state fidelity assays. Interestingly, although HIV RT showed severalfold-lower fidelity under high-Mg(2+) (6 mM) conditions, MuLV RT fidelity was insensitive to Mg(2+). Overall, the results indicate that the fidelity of HIV replication in cells is compatible with findings of experiments carried out in vitro with purified HIV RT, providing more physiological conditions are used. IMPORTANCE Human immunodeficiency virus rapidly evolves through the generation and subsequent selection of mutants that can circumvent the immune response and escape drug therapy. This process is fueled, in part, by the presumably highly error-prone HIV polymerase reverse transcriptase (RT). Paradoxically, results of studies examining HIV replication in cells indicate an error frequency that is ~10 times lower than the rate for RT in the test tube, which invokes the possibility of factors that make RT more accurate in cells. This study brings the cellular and test tube results in closer agreement by showing that HIV RT is not more error prone than other RTs and, when assayed under physiological magnesium conditions, has a much lower error rate than in typical assays conducted using conditions optimized for enzyme activity.
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Affiliation(s)
- Vasudevan Achuthan
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA
| | - Brian J Keith
- Institute of Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Bernard A Connolly
- Institute of Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Jeffrey J DeStefano
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland, USA
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Gening LV, Lakhin AV, Stelmashook EV, Isaev NK, Tarantul VZ. Inhibition of Mn2+-induced error-prone DNA synthesis with Cd2+ and Zn2+. BIOCHEMISTRY (MOSCOW) 2013; 78:1137-45. [DOI: 10.1134/s0006297913100088] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Martin MJ, Garcia-Ortiz MV, Esteban V, Blanco L. Ribonucleotides and manganese ions improve non-homologous end joining by human Polμ. Nucleic Acids Res 2012; 41:2428-36. [PMID: 23275568 PMCID: PMC3575841 DOI: 10.1093/nar/gks1444] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Human DNA polymerase mu (Polμ), a family X member involved in DNA repair, has both template-directed and terminal transferase (template-independent) activities. In addition to their ability to incorporate untemplated nucleotides, another similarity between Polµ and terminal deoxynucleotidyl transferase (TdT) is their promiscuity in using ribonucleotides (NTPs), whose physiological significance is presently unknown. As shown here, Polµ can use NTPs instead of deoxynucleotides (dNTPs) during non-homologous end joining (NHEJ) of non-complementary ends, a Polµ-specific task. Moreover, a physiological concentration of Mn2+ ions did benefit Polµ-mediated NHEJ by improving the efficiency and accuracy of nucleotide insertion. Analysis of different mutations in the ‘steric gate’ of the active site indicated that Polµ is taking advantage of an open active site, valid for selecting alternative activating metal ions and nucleotides as substrates. This versatility would allow ad hoc selection of the most appropriate nucleotide/metal ion combination for individual NHEJ events to gain efficiency without a cost in terms of fidelity, thus widening the spectrum of available solutions to position a discontinuous template strand in proper register for connection.
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Affiliation(s)
- Maria Jose Martin
- Centro de Biología Molecular Severo Ochoa (CSIC-UAM), 28049 Madrid, Spain
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Socała K, Nieoczym D, Poleszak E, Wlaź P. Influence of the phosphodiesterase type 5 inhibitor, sildenafil, on antidepressant-like activity of magnesium in the forced swim test in mice. Pharmacol Rep 2012; 64:205-11. [PMID: 22580537 DOI: 10.1016/s1734-1140(12)70747-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 09/01/2011] [Indexed: 11/28/2022]
Abstract
Magnesium, which acts as an antagonist of N-methyl-D-aspartate (NMDA) subtype of glutamate receptors, exerts antidepressant-like activity in animal models of depression. The present study was undertaken to elucidate the influence of sildenafil, a phosphodiesterase type 5 inhibitor, on the anti-immobility action of magnesium in the forced swim test in mice. Swim sessions were conducted by placing mice in glass cylinders filled with water for 6 min and the duration of the behavioral immobility during the last 4 min of the test was evaluated. Locomotor activity was measured with photoresistor actimeters. Serum and brain magnesium levels were assayed spectrophotometrically. Magnesium at a dose of 30 mg/kg, i.p. significantly decreased the immobility time while sildenafil (5, 10 and 20 mg/kg, i.p.) in a dose-dependent manner reduced the antidepressant-like activity of magnesium. The co-administration of magnesium with sildenafil at the highest dose entirely abolished the antidepressant-like effect of magnesium and caused a statistically significant increase in immobility duration as compared to the control group. Combination of magnesium with sildenafil resulted in a potent reduction (80%) of locomotor activity and pharmacokinetic studies showed a significant increase of magnesium concentration in serum (as compared to magnesium treatment alone) without changes within brain tissue in mice treated with magnesium and sildenafil. When given alone, sildenafil caused a significant increase in magnesium levels in both serum and brain. Our results indicate that a simultaneous treatment with magnesium and sildenafil results in hypermagnesemia in laboratory animals. However, the mechanism underlying this effect remains elusive.
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Affiliation(s)
- Katarzyna Socała
- Department of Animal Physiology, Institute of Biology and Biochemistry, Maria Curie-Skłodowska University, Akademicka 19, PL 20-033 Lublin, Poland
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Gening LV. DNA polymerase ι of mammals as a participant in translesion synthesis of DNA. BIOCHEMISTRY (MOSCOW) 2011; 76:61-8. [DOI: 10.1134/s0006297911010081] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Mebazaa MS, Ouerghi S, Frikha N, Moncer K, Mestiri T, James MF, Ben Ammar MS. Is magnesium sulfate by the intrathecal route efficient and safe? ACTA ACUST UNITED AC 2011; 30:47-50. [PMID: 21236623 DOI: 10.1016/j.annfar.2010.12.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Accepted: 12/02/2010] [Indexed: 01/27/2023]
Abstract
The polypharmacological approach to the treatment of postoperative pain has become routine in an attempt to minimize the adverse side effects of opioids. Magnesium sulphate is a noncompetitive antagonist of the N-methyl-d-aspartate (NMDA) receptor and thus can modify nociceptive modulation. Intravenous administration of magnesium sulphate can improve postoperative analgesia and decrease the requirement for postoperative opiates, but the effects are inconsistent and have not been reliably accompanied by a reduction in the incidence of morphine-related adverse events. Several studies have shown that the administration of magnesium by the intrathecal route is safe and, in combination with opiates, extends the effect of spinal anaesthesia in both animal and human studies. The analysis of these studies justifies further investigation of the use of magnesium sulphate by the intrathecal route.
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Affiliation(s)
- M S Mebazaa
- Department of Anesthesiology, Intensive Care and Emergency Medicine, University Hospital of Mongi Slim, La Marsa, Sidi Daoud 2046, Tunisia
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Angel MJ, Chen R, Bryan Young G. Metabolic encephalopathies. HANDBOOK OF CLINICAL NEUROLOGY 2010; 90:115-66. [PMID: 18631820 DOI: 10.1016/s0072-9752(07)01707-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Michael J Angel
- University of Toronto, Division of Neurology, Toronto Western Hospital, Toronto, Ontario, Canada.
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Frank EG, Woodgate R. Increased catalytic activity and altered fidelity of human DNA polymerase iota in the presence of manganese. J Biol Chem 2007; 282:24689-96. [PMID: 17609217 DOI: 10.1074/jbc.m702159200] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
All DNA polymerases require a divalent cation for catalytic activity. It is generally assumed that Mg(2+) is the physiological cofactor for replicative DNA polymerases in vivo. However, recent studies suggest that certain repair polymerases, such as pol lambda, may preferentially utilize Mn(2+) in vitro. Here we report on the effects of Mn(2+) and Mg(2+) on the enzymatic properties of human DNA polymerase iota (pol iota). pol iota exhibited the greatest activity in the presence of low levels of Mn(2+) (0.05-0.25 mm). Peak activity in the presence of Mg(2+) was observed in the range of 0.1-0.5 mm and was significantly reduced at concentrations >2 mm. Steady-state kinetic analyses revealed that Mn(2+) increases the catalytic activity of pol iota by approximately 30-60,000-fold through a dramatic decrease in the K(m) value for nucleotide incorporation. Interestingly, whereas pol iota preferentially misinserts G opposite T by a factor of approximately 1.4-2.5-fold over the correct base A in the presence of 0.25 and 5 mm Mg(2+), respectively, the correct insertion of A is actually favored 2-fold over the misincorporation of G in the presence of 0.075 mm Mn(2+). Low levels of Mn(2+) also dramatically increased the ability of pol iota to traverse a variety of DNA lesions in vitro. Titration experiments revealed a strong preference of pol iota for Mn(2+) even when Mg(2+) is present in a >10-fold excess. Our observations therefore raise the intriguing possibility that the cation utilized by pol iota in vivo may actually be Mn(2+) rather than Mg(2+), as tacitly assumed.
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Affiliation(s)
- Ekaterina G Frank
- Laboratory of Genomic Integrity, NICHD, National Institutes of Health, Bethesda, Maryland 20892-2725, USA
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Goldschmidt V, Didierjean J, Ehresmann B, Ehresmann C, Isel C, Marquet R. Mg2+ dependency of HIV-1 reverse transcription, inhibition by nucleoside analogues and resistance. Nucleic Acids Res 2006; 34:42-52. [PMID: 16394022 PMCID: PMC1325016 DOI: 10.1093/nar/gkj411] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Metal ions are essential for DNA polymerase and RNase H activities of HIV-1 reverse transcriptase (RT). RT studies are routinely performed at 6–8 mM Mg2+, despite the fact that the in vivo concentration might be as low as 0.2 mM. We studied the influence of MgCl2 and ATP, which likely binds a significant fraction of the magnesium pool in vivo, on the DNA polymerase and RNase H activities of HIV-1 RT, its inhibition by nucleoside RT inhibitors (NRTIs) and primer unblocking by AZT-resistant RT. At low Mg2+ concentration, reverse transcription of a natural template strongly increased despite a dramatically reduced intrinsic polymerase activity under such conditions. Low Mg2+ concentrations affected the RNA stability and indirectly decreased its degradation by the RNase H activity. The reduced RNA degradation prevented premature dissociation of the template and primer strands that otherwise generated dead-end DNA products. In addition, low Mg2+ dramatically decreased the incorporation of NRTIs into DNA and increased nucleotide excision by AZT-resistant RT. The latter effect is also most likely owing to the diminished cleavage of the RNA template. Thus, differences in the free Mg2+ concentration between different cell types or during the cell cycle might strongly affect HIV-1 replication and its inhibition.
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Affiliation(s)
| | | | | | | | | | - Roland Marquet
- To whom correspondence should be addressed. Tel: +33 3 88 41 70 54; Fax: +33 3 88 60 22 18;
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Collignon FP, Friedman JA, Piepgras DG, Pichelmann MA, McIver JI, Toussaint LG, McClelland RL. Serum magnesium levels as related to symptomatic vasospasm and outcome following aneurysmal subarachnoid hemorrhage. Neurocrit Care 2005; 1:441-8. [PMID: 16174947 DOI: 10.1385/ncc:1:4:441] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
INTRODUCTION Recent evidence suggests that magnesium may be neuroprotective in the setting of cerebral ischemia, and therapeutic magnesium infusion has been proposed for prophylaxis and treatment of delayed ischemic neurological deficit (DIND) resulting from vasospasm in patients with aneurysmal subarachnoid hemorrhage (SAH). We studied the association between serum magnesium levels, the development of DIND, and the outcomes of patients with SAH. METHODS We studied 128 consecutive patients with aneurysmal SAH treated at our institution between 1990 and 1997 who had a serum magnesium level measured at least once during the acute phase of their hospitalization. Delayed ischemic neurological deficit was defined as severe (major focal deficit or coma), moderate (incomplete focal deficit or decreased sensorium without coma), or none. RESULTS There was no significant difference in mean, minimum, or maximum serum magnesium levels between patients with and without DIND (1.93, 1.83, 2.02 versus 1.91, 1.84, 1.97 mg/dL, respectively). Similarly, no difference was found in mean serum magnesium levels among patients with severe (1.94 mg/dL), moderate (1.92 mg/dL), or no DIND (1.91 mg/dL). Analyses of serum magnesium levels before (0-4 days following SAH), during (4-14 days following SAH), and after (greater than 14 days following SAH) the period of highest risk for vasospasm revealed no association with the development or severity of DIND. Permanent deficit or death resulting from vasospasm and Glasgow Outcome Scale score at longest follow-up were similarly unaffected by serum magnesium levels overall or during any time interval. Forty (31.5%) patients were hypomagnesemic (less than 1.7 mg/dL) during hospitalization, but no difference in outcome (p = 0.185) or development of DIND (p = 0.785) was found when compared to patients with normal (1.7-2.1 mg/dL) or high (greater than 2.1 mg/dL) magnesium serum levels. CONCLUSION We identified no relationship between serum magnesium levels and the development of DIND or outcome following aneurysmal SAH. Based on these data, magnesium supplementation to normal or high-normal physiological ranges seems unlikely to be beneficial for DIND resulting from vasospasm. However, no inference can be made regarding the value of therapeutic infusion of magnesium to supraphysiological levels.
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Gould TD, Chen G, Manji HK. In vivo evidence in the brain for lithium inhibition of glycogen synthase kinase-3. Neuropsychopharmacology 2004; 29:32-8. [PMID: 12942141 DOI: 10.1038/sj.npp.1300283] [Citation(s) in RCA: 163] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
There is considerable interest in the possibility that small-molecule glycogen synthase kinase-3 inhibitors may have utility in the treatment of bipolar disorder, since glycogen synthase kinase-3 is a target of lithium. Although the in vitro inhibition of glycogen synthase kinase-3 by lithium occurs with a K(i) of 1-2 mM, the degree of inhibition of this enzyme in the mammalian brain at therapeutically relevant concentrations has not fully been established. The transcription factor beta-catenin is an established marker of glycogen synthase kinase-3 inactivation because cytoplasmic levels are increased by inhibition of the enzyme. In this study, we measured beta-catenin protein levels after treatment with therapeutically relevant doses of lithium, valproate, and carbamazepine. Western blot revealed that 9 days of treatment with lithium and valproate, but not carbamazepine, increased beta-catenin protein levels in soluble fractions from the frontal cortex. The level of beta-catenin in the particulate fraction, which is not directly regulated by glycogen synthase kinase-3, did not change with any of the three drugs. Furthermore, real-time PCR revealed that lithium significantly decreased beta-catenin mRNA levels, which may represent compensation for an increase in beta-catenin stability. These results strongly suggest that lithium significantly inhibits brain glycogen synthase kinase-3 in vivo at concentrations relevant for the treatment of bipolar disorder.
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Affiliation(s)
- Todd D Gould
- Laboratory of Molecular Pathophysiology, Mood and Anxiety Disorders Program, National Institute of Mental Health, Bethesda, MD 20892-4405, USA
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Pamphlett R, Todd E, Vink R, McQuilty R, Cheema SS. Magnesium supplementation does not delay disease onset or increase survival in a mouse model of familial ALS. J Neurol Sci 2003; 216:95-8. [PMID: 14607308 DOI: 10.1016/s0022-510x(03)00216-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Treatment of amyotrophic lateral sclerosis (ALS) with anti-glutamate agents has had some success, but the search continues for more effective glutamate blockers. Magnesium (Mg) ions inhibit the opening of some glutamate receptors, so we increased dietary Mg in a mouse model of ALS in an attempt to modify the course of the disease. From the age of 6 weeks, mutant superoxide dismutase 1 (SOD1) transgenic mice and wild-type controls had either 0, 21.5 or 43 g/l of Mg pidolate added to their drinking water. Disease onset was measured by tests for coordination and forelimb strength, and survival by standard endpoints. Mg levels in the brain were measured in wild-type mice using mass spectrometry. Mutant SOD1 mice on no added Mg became weak at about 105 days, and survived between 114 and 137 days. No difference in either time of onset of weakness, or survival, was seen in mutant SOD1 mice on different doses of Mg. No increase in wild-type brain Mg was found after supplemental Mg. From these results, it appears that a trial of oral Mg supplementation in human ALS is not warranted.
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Affiliation(s)
- Roger Pamphlett
- Department of Pathology D06, The University of Sydney, New South Wales 2006, Sydney, Australia.
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