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Wang Z, Zhang N, Zhang M, Jiang Y, Ng AS, Bridges E, Zhang W, Zeng X, Luo Q, Liang J, Győrffy B, Hublitz P, Liang Z, Fischer R, Kerr D, Harris AL, Cai S. GTP Cyclohydrolase Drives Breast Cancer Development and Promotes EMT in an Enzyme-Independent Manner. Cancer Res 2023; 83:3400-3413. [PMID: 37463466 DOI: 10.1158/0008-5472.can-22-3471] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 04/27/2023] [Accepted: 07/14/2023] [Indexed: 07/20/2023]
Abstract
GTP cyclohydrolase (GCH1) is the rate-limiting enzyme for tetrahydrobiopterin (BH4) biosynthesis. The catalysis of BH4 biosynthesis is tightly regulated for physiological neurotransmission, inflammation, and vascular tone. Paradoxically, BH4 has emerged as an oncometabolite regulating tumor growth, but the effects on tumor development remain controversial. Here, we found that GCH1 potentiated the growth of triple-negative breast cancer (TNBC) and HER2+ breast cancer and transformed nontumor breast epithelial cells. Independent of BH4 production, GCH1 protein induced epithelial-to-mesenchymal transition by binding to vimentin (Vim), which was mediated by HSP90. Conversely, GCH1 ablation impaired tumor growth, suppressed Vim in TNBC, and inhibited EGFR/ERK signaling while activating the p53 pathway in estrogen receptor-positive tumor cells. GCH1 deficiency increases tumor cell sensitivity to HSP90 inhibition and endocrine treatments. In addition, high GCH1 correlated with poor breast cancer survival. Together, this study reveals an enzyme-independent oncogenic role of GCH1, presenting it as a potential target for therapeutic development. SIGNIFICANCE GTP cyclohydrolase functions as an oncogene in breast cancer and binds vimentin to induce epithelial-to-mesenchymal transition independently of its enzyme activity, which confers targetable vulnerabilities for developing breast cancer treatment strategies.
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Affiliation(s)
- Zijing Wang
- Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
- Sichuan University-Oxford University Huaxi Joint Centre for Gastrointestinal Cancer, West China Hospital, Sichuan University, Chengdu, China
| | - Nan Zhang
- Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
- Sichuan University-Oxford University Huaxi Joint Centre for Gastrointestinal Cancer, West China Hospital, Sichuan University, Chengdu, China
| | - Miao Zhang
- Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
- School of Acupuncture and Moxibustion, Fujian University of Traditional Chinese Medicine, China
| | - Yao Jiang
- Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Aik Seng Ng
- Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Esther Bridges
- Molecular Oncology Laboratories, University Department of Oncology, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Wei Zhang
- Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Xin Zeng
- Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Qi Luo
- Xiamen Cancer Hospital, Xiamen First Hospital, Xiamen University, Fujian, China
| | - Jiabien Liang
- Xiamen Cancer Hospital, Xiamen First Hospital, Xiamen University, Fujian, China
| | - Balázs Győrffy
- TTK Cancer Biomarker Research Group, Institute of Enzymology, and Semmelweis University Department Bioinformatics and Department of Paediatrics, Budapest, Hungary
| | - Philip Hublitz
- Genome Engineering Facility, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Zhu Liang
- Nuffield Department of Medicine, Target Discovery Institute, University of Oxford, Roosevelt Drive, Oxford, United Kingdom
| | - Roman Fischer
- Nuffield Department of Medicine, Target Discovery Institute, University of Oxford, Roosevelt Drive, Oxford, United Kingdom
| | - David Kerr
- Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Adrian L Harris
- Molecular Oncology Laboratories, University Department of Oncology, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Shijie Cai
- Nuffield Division of Clinical Laboratory Sciences, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
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2
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Atanasoska M, Vazharova R, Stevanović G, Bradinova I, Staykova SY, Balabanski L, Mircheva D, Avdjieva-Tzavella D, Toncheva D. Dopa-responsive dystonia in Bulgarian patients: report of three cases. Eur J Hum Genet 2023:10.1038/s41431-023-01370-4. [PMID: 37165102 DOI: 10.1038/s41431-023-01370-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 04/20/2023] [Indexed: 05/12/2023] Open
Affiliation(s)
- Maya Atanasoska
- GMDL "CellGenetics", Sofia, Bulgaria.
- Department of Genetics, Faculty of Biology, Sofia University St Kliment Ohridski, Sofia, Bulgaria.
| | - Radoslava Vazharova
- GMDL "CellGenetics", Sofia, Bulgaria.
- Department of Biology, Medical genetics and Microbiology, Faculty of Medicine, Sofia University St Kliment Ohridski, Sofia, Bulgaria.
| | - Galina Stevanović
- Clinic of Neurology and Psychiatry for Children and Youth, School of Medicine, University of Belgrade, Belgrade, Serbia
| | - Irena Bradinova
- GMDL "CellGenetics", Sofia, Bulgaria
- National Genetic Laboratory, UHOG "Maichin dom" Sofia, Sofia, Bulgaria
| | | | | | | | | | - Draga Toncheva
- GMDL "CellGenetics", Sofia, Bulgaria
- Bulgarian Academy of Science, Sofia, Bulgaria
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3
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Clelland JD, Read LL, Smeed J, Clelland CL. Regulation of cortical and peripheral GCH1 expression and biopterin levels in schizophrenia-spectrum disorders. Psychiatry Res 2018; 262:229-236. [PMID: 29471261 PMCID: PMC5866784 DOI: 10.1016/j.psychres.2018.02.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 01/19/2018] [Accepted: 02/02/2018] [Indexed: 12/17/2022]
Abstract
Tetrahydrobiopterin (BH4) is an essential cofactor for dopamine, serotonin and nitric oxide synthesis. Deficits of plasma total biopterin (a measure of BH4) have been described in schizophrenia and schizoaffective disorder. GCH1 encodes the first and rate-limiting enzyme in BH4 synthesis. Peripheral GCH1 expression is lower in first episode psychosis patients versus controls, and we hypothesized that a GCH1 promoter polymorphism associated with psychiatric illness, contributes to regulation of both GCH1 expression and BH4 levels. We tested this hypothesis in 120 subjects (85 patients with schizophrenia or schizoaffective disorder and 35 controls): Patients with the rs10137071 A allele had significantly lower plasma biopterin than GG patients and controls. In additional samples we assessed the relationship between genotype and diagnosis (schizophrenia or control) on GCH1 expression in the prefrontal cortex (n = 67) and peripheral leukocytes (n = 53). We found a significant linear relationship between GCH1 and study group in the CNS and periphery, with A allele patients having lower expression. Finally, in antipsychotic naïve patients (n = 13) we tested for an effect of medication on GCH1: Expression rose significantly after the onset of medication, primarily in A allele patients. These data suggest the potential for personalized genetic approaches to ameliorating BH4 deficits in schizophrenia-spectrum disorders.
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Affiliation(s)
- James D Clelland
- Movement Disorders and Molecular Psychiatry, The Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Road, Orangeburg, NY, USA; Department of Psychiatry, New York University Langone Medical Center (NYU), 550 First Avenue, New York, NY, USA
| | - Laura L Read
- Movement Disorders and Molecular Psychiatry, The Nathan S. Kline Institute for Psychiatric Research, 140 Old Orangeburg Road, Orangeburg, NY, USA; Department of Psychiatry, New York University Langone Medical Center (NYU), 550 First Avenue, New York, NY, USA
| | - Jennifer Smeed
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, USA
| | - Catherine L Clelland
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, USA; Department of Pathology and Cell Biology, Columbia University Medical Center, 630 West 168th Street, New York, NY, USA.
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4
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Pandya M, Golderer G, Werner E, Werner-Felmayer G. Interaction of human GTP cyclohydrolase I with its splice variants. Biochem J 2006; 400:75-80. [PMID: 16848765 PMCID: PMC1635435 DOI: 10.1042/bj20060765] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Tetrahydrobiopterin is an essential cofactor for aromatic amino acid hydroxylases, ether lipid oxidase and nitric oxide synthases. Its biosynthesis in mammals is regulated by the activity of the homodecameric enzyme GCH (GTP cyclohydrolase I; EC 3.5.4.16). In previous work, catalytically inactive human GCH splice variants differing from the wild-type enzyme within the last 20 C-terminal amino acids were identified. In the present study, we searched for a possible role of these splice variants. Gel filtration profiles of purified recombinant proteins showed that variant GCHs form high-molecular-mass oligomers similar to the wild-type enzyme. Co-expression of splice variants together with wild-type GCH in mammalian cells revealed that GCH levels were reduced in the presence of splice variants. Commensurate with these findings, the GCH activity obtained for wild-type enzyme was reduced 2.5-fold through co-expression with GCH splice variants. Western blots of native gels suggest that splice variants form decamers despite C-terminal truncation. Therefore one possible explanation for the effect of GCH splice variants could be that inactive variants are incorporated into GCH heterodecamers, decreasing the enzyme stability and activity.
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Affiliation(s)
- Maya J. Pandya
- Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Fritz-Pregl-Strasse 3, A-6020 Innsbruck, Austria
| | - Georg Golderer
- Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Fritz-Pregl-Strasse 3, A-6020 Innsbruck, Austria
| | - Ernst R. Werner
- Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Fritz-Pregl-Strasse 3, A-6020 Innsbruck, Austria
| | - Gabriele Werner-Felmayer
- Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Fritz-Pregl-Strasse 3, A-6020 Innsbruck, Austria
- To whom correspondence should be addressed (email )
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5
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Chavan B, Gillbro JM, Rokos H, Schallreuter KU. GTP cyclohydrolase feedback regulatory protein controls cofactor 6-tetrahydrobiopterin synthesis in the cytosol and in the nucleus of epidermal keratinocytes and melanocytes. J Invest Dermatol 2006; 126:2481-9. [PMID: 16778797 DOI: 10.1038/sj.jid.5700425] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
(6R)-L-erythro 5,6,7,8 tetrahydrobiopterin (6BH4) is crucial in the hydroxylation of L-phenylalanine-, L-tyrosine-, and L-tryptophan-regulating catecholamine and serotonin synthesis as well as tyrosinase in melanogenesis. The rate-limiting step of 6BH4 de novo synthesis is controlled by guanosine triphosphate (GTP) cyclohydrolase I (GTPCHI) and its feedback regulatory protein (GFRP), where binding of L-phenylalanine to GFRP increases enzyme activities, while 6BH4 exerts the opposite effect. Earlier it was demonstrated that the human epidermis holds the full capacity for autocrine 6BH4 de novo synthesis and recycling. However, besides the expression of epidermal mRNA for GFRP, the presence of a functioning GFRP feedback has never been shown. Therefore, it was tempting to investigate whether this important mechanism is present in epidermal cells. Our results identified indeed a functioning GFRP/GTPCHI axis in epidermal keratinocytes and melanocytes in the cytosol, adding the missing link for 6BH4 de novo synthesis which in turn controls cofactor supply for catecholamine and serotonin biosynthesis as well as melanogenesis in the human epidermis. Moreover, GFRP expression and GTPCHI activities have been found in the nucleus of both cell types. The significance of this result warrants further investigation.
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Affiliation(s)
- Bhaven Chavan
- Clinical and Experimental Dermatology/Department of Biomedical Sciences University of Bradford, Bradford, UK
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6
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Funderburk CD, Bowling KM, Xu D, Huang Z, O'Donnell JM. A typical N-terminal extensions confer novel regulatory properties on GTP cyclohydrolase isoforms in Drosophila melanogaster. J Biol Chem 2006; 281:33302-12. [PMID: 16966327 DOI: 10.1074/jbc.m602196200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cofactor tetrahydrobiopterin plays critical roles in the modulation of the signaling molecules dopamine, serotonin, and nitric oxide. Deficits in cofactor synthesis have been associated with several human hereditary diseases. Responsibility for the regulation of cofactor pools resides with the first enzyme in its biosynthetic pathway, GTP cyclohydrolase I. Because organisms must be able to rapidly respond to environmental and developmental cues to adjust output of these signaling molecules, complex regulatory mechanisms are vital for signal modulation. Mammalian GTP cyclohydrolase is subject to end-product inhibition via an associated regulatory protein and to positive regulation via phosphorylation, although target residues are unknown. GTP cyclohydrolase is composed of a highly conserved homodecameric catalytic core and non-conserved N-terminal domains proposed to be regulatory sites. We demonstrate for the first time in any organism that the N-terminal arms of the protein serve regulatory functions. We identify two different modes of regulation of the enzyme mediated through the N-terminal domains. The first is end-product feedback inhibition, catalytically similar to that of the mammalian enzyme, except that feedback inhibition by the cofactor requires sequences in the N-terminal arms rather than a separate regulatory protein. The second is a novel inhibitory interaction between the N-terminal arms and the active sites, which can be alleviated through the phosphorylation of serine residues within the N termini. Both mechanisms allow for acute and highly responsive regulation of cofactor production as required by downstream signaling pathways.
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7
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Matei V, Rodríguez-Vilarrupla A, Deulofeu R, Colomer D, Fernández M, Bosch J, Garcia-Pagán JC. The eNOS cofactor tetrahydrobiopterin improves endothelial dysfunction in livers of rats with CCl4 cirrhosis. Hepatology 2006; 44:44-52. [PMID: 16799985 DOI: 10.1002/hep.21228] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In cirrhosis, intrahepatic endothelial dysfunction is one of the mechanisms involved in the increased resistance to portal blood flow and therefore in the development of portal hypertension. Endothelial nitric oxide synthase (eNOS) uncoupling due to deficiency of tetrahydrobiopterin (BH4) results in decreased production of NO and plays a major role in endothelial dysfunction in other conditions. We examined whether eNOS uncoupling is involved in the pathogenesis of endothelial dysfunction of livers with cirrhosis. Basal levels of tetrahydrobiopterin and guanosine triphosphate (GTP)-cyclohydrolase (BH4 rate-limiting enzyme) expression and activity were determined in liver homogenates of control and rats with CCl4 cirrhosis. Thereafter, rats were treated with tetrahydrobiopterin, and eNOS activity, NO bioavailability, assessed with a functional assay, and the vasodilator response to acetylcholine (endothelial function) were evaluated. Livers with cirrhosis showed reduced BH4 levels and decreased GTP-cyclohydrolase activity and expression, which were associated with impaired vasorelaxation to acetylcholine. Tetrahydrobiopterin supplementation increased BH4 hepatic levels and eNOS activity and significantly improved the vasodilator response to acetylcholine in rats with cirrhosis. In conclusion, the impaired response to acetylcholine of livers with cirrhosis is modulated by a reduced availability of the eNOS cofactor, tetrahydrobiopterin. Tetrahydrobiopterin supplementation improved the endothelial dysfunction of cirrhotic livers.
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Affiliation(s)
- Vasilica Matei
- Hepatic Hemodynamic Laboratory, Liver Unit, Institut de Malalties Digestives i Metabòliques, Hospital Clínic, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), University of Barcelona, Barcelona, Spain
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8
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He A, Simpson DR, Daniels L, Rosazza JPN. Cloning, expression, purification, and characterization of Nocardia sp. GTP cyclohydrolase I. Protein Expr Purif 2005; 35:171-80. [PMID: 15135390 DOI: 10.1016/j.pep.2004.02.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2003] [Revised: 02/05/2004] [Indexed: 11/27/2022]
Abstract
The sequence of the gene from Nocardia sp. NRRL 5646 encoding GTP cyclohydrolase I (GCH), gch, and its adjacent regions was determined. The open reading frame of Nocardia gch contains 684 nucleotides, and the deduced amino acid sequence represents a protein of 227 amino acid residues with a calculated molecular mass of 24,563Da. The uncommon start codon TTG was identified by matching the N-terminal amino acid sequence of purified Nocardia GCH with the deduced amino acid sequence. A likely ribosomal binding site was identified 9bp upstream of the translational start site. The 3' end flank region encodes a peptide that shares high homology with dihydropteroate synthases. Nocardia GCH has 73 and 60% identity to the proteins encoded by the putative gch of Mycobacterium tuberculosis and Streptomyces coelicolor, respectively. Nocardia GCH was highly expressed in Escherichia coli cells carrying a pHAT10 based expression vector, and moderately expressed in Mycobacterium smegmatis cells carrying a pSMT3 based expression vector. Enterokinase digestion of recombinant Nocardia GCH, and in-gel digestion of Nocardia GCH and recombinant GCH followed by MALDI-TOF-MS analysis, confirmed that the actual subunit size of the enzyme was 24.5kDa. Thus, we conclude that the active form of native Nocardia GCH is a decamer. Our earlier incorrect conclusion was that the native enzyme was an octamer derived from the anomalous SDS-PAGE migration of the subunit.
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Affiliation(s)
- Aimin He
- Division of Medicinal and Natural Products Chemistry and Center for Biocatalysis and Bioprocessing, College of Pharmacy, University of Iowa, Iowa City, IA 42242, USA
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9
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Hwu WL, Yeh HY, Fang SW, Chiang HS, Chiou YW, Lee YM. Regulation of GTP cyclohydrolase I by alternative splicing in mononuclear cells. Biochem Biophys Res Commun 2003; 306:937-42. [PMID: 12821132 DOI: 10.1016/s0006-291x(03)01091-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
GTP cyclohydrolase I (GCH, EC 3.5.4.16) regulates the level of tetrahydrobiopterin and in turn the activities of nitric oxide synthase and aromatic amino acid hydroxylases. Type II GCH mRNA, an alternatively spliced species abundant in blood cells, encodes a truncated and nonfunctional protein. When we stimulate peripheral blood mononuclear cells by PHA, the transcription of full-length GCH mRNA increased, but that of type II mRNA decreased transiently. We further demonstrated that the type II cDNA exerted a dominant-negative effect on the wild-type cDNA, similar to the effect of some GCH mutants. Therefore, type II mRNA may regulate GCH and then contribute to the regulation of NO production by BH4-dependent iNOS in mononuclear cells. Selection of the splicing sites may be coupled with transcriptional activation of the GCH gene.
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Affiliation(s)
- Wuh-Liang Hwu
- Department of Pediatrics and Medical Genetics, National Taiwan University Hospital and National Taiwan University, College of Medicine, Taipei, Taiwan ROC
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Ziegler I. The pteridine pathway in zebrafish: regulation and specification during the determination of neural crest cell-fate. PIGMENT CELL RESEARCH 2003; 16:172-82. [PMID: 12753383 DOI: 10.1034/j.1600-0749.2003.00044.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
This review describes pteridine biosynthesis and its relation to the differentiation of neural crest derivatives in zebrafish. During the embryonic development of these fish, neural crest precursor cells segregate into neural elements, ectomesenchymal cells and pigment cells; the latter then diversifying into melanophores, iridophores and xanthophores. The differentiation of neural cells, melanophores, and xanthophores is coupled closely with the onset of pteridine synthesis which starts from GTP and is regulated through the control of GTP cyclohydrolase I activity. De novo pteridine synthesis in embryos of this species increases during the first 72-h postfertilization, producing H4biopterin, which serves as a cofactor for neurotransmitter synthesis in neural cells and for tyrosine production in melanophores. Thereafter, sepiapterin (6-lactoyl-7,8-dihydropterin) accumulates as yellow pigment in xanthophores, together with 7-oxobiopterin, isoxanthopterin and 2,4,7-trioxopteridine. Sepiapterin is the key intermediate in the formation of 7-oxopteridines, which depends on the availability of enzymes belonging to the xanthine oxidoreductase family. Expression of the GTP cyclohydrolase I gene (gch) is found in neural cells, in melanoblasts and in early xanthophores (xanthoblasts) of early zebrafish embryos but steeply declines in xanthophores by 42-h postfertilization. The mechanism(s) whereby sepiapterin branches off from the GTP-H4biopterin pathway is currently unknown and will require further study. The surge of interest in zebrafish as a model for vertebrate development and its amenability to genetic manipulation provide powerful tools for analysing the functional commitment of neural crest-derived cells and the regulation of pteridine synthesis in mammals.
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Affiliation(s)
- Irmgard Ziegler
- GSF-Institut für Klinische Molekularbiologie und Tumorgenetik, München, Germany.
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11
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Blau N, Bonafé L, Thöny B. Tetrahydrobiopterin deficiencies without hyperphenylalaninemia: diagnosis and genetics of dopa-responsive dystonia and sepiapterin reductase deficiency. Mol Genet Metab 2001; 74:172-85. [PMID: 11592814 DOI: 10.1006/mgme.2001.3213] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
DOPA responsive dystonia (DRD) and sepiapterin reductase (SR) deficiency are inherited disorders of tetrahydrobiopterin (BH4) metabolism characterized by the signs and symptoms related to monoamine neurotransmitter deficiency. In contrast to classical forms of BH4 deficiency DRD and SR deficiency present without hyperphenylalaninemia and thus cannot be detected by the neonatal screening for phenylketonuria (PKU). While DRD is mostly caused by autosomal dominant mutations in the GTP cyclohydrolase I gene (GCH1), SR deficiency is an autosomal recessive disease. The most important biochemical investigations for the diagnosis of these neurological diseases includes CSF investigations for neurotransmitter metabolites and pterins as well as neopterin and biopterin production in cytokine-stimulated fibroblasts. Discovery of SR deficiency opened new insights into alternative pathways of the cofactor BH4 via carbonyl, aldose, and dihydrofolate reductases. As a consequence of the low dihydrofolate reductase activity in the brain, dihydrobiopterin intermediate accumulates and inhibits tyrosine and tryptophan hydroxylases and uncouples nitric oxide synthase (nNOS), leading to neurotransmitter deficiency and possibly also to neuronal cell death.
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Affiliation(s)
- N Blau
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital, Steinwiesstrasse 75, Zurich, 8032, Switzerland.
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12
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Skrygan M, Bartholomé B, Bonafé L, Blau N, Bartholomé K. A splice mutation in the GTP cyclohydrolase I gene causes dopa-responsive dystonia by exon skipping. J Inherit Metab Dis 2001; 24:345-51. [PMID: 11486899 DOI: 10.1023/a:1010544316387] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Four different mutations in the GTP cyclohydrolase I gene were found (P199L, M211V, IVS5+1G>A, G203R) in 6 out of 33 families with dopa-responsive dystonia. A splice mutation (IVS5+1G>A) located at the border of exon 5 to intron 5 was found in one of these families. Three members of the family carry the IVS5+1G>A mutation on one allele, inherited from the father to the daughter and son. Examination of the mRNA showed an exon 5 skipping that results in a reduction of enzyme activity in cultured fibroblasts to 4-17% compared to controls. The father and daughter never had clinical symptoms of dopa-responsive dystonia. The son was symptomatic at the age of 3 years and was treated successfully with L-dopa/carbidopa. After 20 years this therapy was terminated and for the next 6 years he was free of symptoms. With increased motoric activity, symptoms reappeared and the therapy was reintroduced.
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Affiliation(s)
- M Skrygan
- University Children's Hospital, Bochum, Germany
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13
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Golderer G, Werner ER, Heufler C, Strohmaier W, Gröbner P, Werner-Felmayer G. GTP cyclohydrolase I mRNA: novel splice variants in the slime mould Physarum polycephalum and in human monocytes (THP-1) indicate conservation of mRNA processing. Biochem J 2001; 355:499-507. [PMID: 11284739 PMCID: PMC1221763 DOI: 10.1042/0264-6021:3550499] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
GTP cyclohydrolase I (EC 3.5.4.16) is the first enzyme in the biosynthesis of tetrahydrobiopterin [(6R)-5,6,7,8-tetrahydro-L-biopterin, H(4)-biopterin] in mammals and of folic acid in bacteria. Here we have characterized the GTP cyclohydrolase I gene structure and two mRNA species from Physarum polycephalum, an acellular slime mould that synthesizes H(4)-biopterin and metabolites of the folic acid biosynthetic pathway. Its GTP cyclohydrolase I gene consists of seven exons, and the two GTP cyclohydrolase I cDNA species isolated from Physarum encode for proteins with 228 (25.7 kDa) and 195 (22.1 kDa) amino acids. Furthermore, we identified two previously undescribed mRNA species in interferon-gamma-treated human myelomonocytoma cells (THP-1) in addition to the cDNA coding for the fully functional 250-residue (27.9 kDa) protein, which is identical with that in human phaeochromocytoma cells. One of the new splice variants codes for a 233-residue (25.7 kDa) protein, whereas the other codes for the full-length protein but is alternatively spliced within the 3'-untranslated region. In heterologous expression, the shorter proteins of Physarum as well as of THP-1 cells identified here are degraded by proteolysis. Accordingly, only the 27.9 kDa protein was detectable in Western blots from THP-1 cell extracts. Quantification of GTP cyclohydrolase I mRNA species in different human cell types with and without cytokine treatment showed that in addition to the correct mRNA the two splice variants isolated here, as well as the two splice variants known from human liver, are strongly induced by cytokines in cell types with inducible GTP cyclohydrolase I (THP-1, dermal fibroblasts), but not in cell types with constitutive GTP cyclohydrolase I expression (SK-N-SH, Hep-G2). As in human liver, splicing of the new mRNA variant found in THP-1 cells occurs at the boundary of exons 5 and 6. Strikingly, the 195-residue protein from Physarum is alternatively spliced at a homologous position, i.e. at the boundary of exons 6 and 7. Thus alternative splicing of GTP cyclohydrolase I at this position occurs in two species highly distant from each other in terms of evolution. It remains to be seen whether variant proteins encoded by alternatively spliced GTP cyclohydrolase I mRNA transcripts do occur in vivo and whether they participate in regulation of enzyme activity.
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Affiliation(s)
- G Golderer
- Institute of Medical Chemistry and Biochemistry, University of Innsbruck, Fritz-Pregl-Strasse 3, A-6020 Innsbruck, Austria
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14
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Laufs S, Kim SH, Kim S, Blau N, Thöny B. Reconstitution of a metabolic pathway with triple-cistronic IRES-containing retroviral vectors for correction of tetrahydrobiopterin deficiency. J Gene Med 2000; 2:22-31. [PMID: 10765502 DOI: 10.1002/(sici)1521-2254(200001/02)2:1<22::aid-jgm86>3.0.co;2-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Tetrahydrobiopterin (BH4) is an essential cofactor for catecholamine and serotonin neurotransmitter biosynthesis. BH4 biosynthesis is carried out in a three-enzyme pathway involving GTP cyclohydrolase I (GTPCH), 6-pyruvoyl-tetrahydropterin synthase (PTPS) and sepiapterin reductase (SR). Treatment of genetic defects leading to BH4 deficiency requires neurotransmitter replacement since synthetic cofactor does not efficiently penetrate the blood-brain barrier. Autologous fibroblasts transplanted into the brain as depository cells for drug delivery might offer an alternative. However, normal fibroblasts do not express GTPCH, and fibroblasts from PTPS patients lack two biosynthetic enzymes for BH4 production. METHODS We engineered primary fibroblasts by the use of triple-cistronic, retroviral vectors for cofactor production. RESULTS Constitutive SR activity in these cells enabled BH4 biosynthesis by transducing GTPCH and PTPS cDNAs together with a selective marker coupled in a single transcript with two IRES-elements in tandem. Upon reaching a critical concentration (> 400 pmol/mg protein) of intracellular BH4, the fibroblasts efficiently released cofactor even under non-dividing conditions. CONCLUSION The use of triple-cistronic vectors for single transduction to reconstitute metabolic pathways or to treat multi-genetic diseases may be useful for engineering, for instance, depository cells for various organs, including the nervous system.
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Affiliation(s)
- S Laufs
- Department of Pediatrics, University of Zürich, Switzerland
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15
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Budworth J, Meillerais S, Charles I, Powell K. Tissue distribution of the human soluble guanylate cyclases. Biochem Biophys Res Commun 1999; 263:696-701. [PMID: 10512742 DOI: 10.1006/bbrc.1999.1444] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Soluble guanylate cyclase (sGC) is an important component of the NO signaling pathway. Human sGC isoforms alpha(1), alpha(2), and beta(1) show differential mRNA tissue distributions. alpha(1) and beta(1) are expressed in most tissues; however, the alpha(2) isoform shows a more restricted expression pattern with high levels in brain, placenta, spleen, and uterus only. Both alpha subunits exist as multiple transcripts whereas beta(1) exists as a single message. This study reports for the first time the tissue distribution of human sGC message and demonstrates that sGC isoforms are nonuniformly expressed which may be useful if the enzyme is to be exploited as a therapeutic target.
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Affiliation(s)
- J Budworth
- Wolfson Institute for Biomedical Research, University College London, 1 Wakefield Street, London, WC1N 1PJ, United Kingdom.
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16
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Furukawa Y, Nygaard TG, Gütlich M, Rajput AH, Pifl C, DiStefano L, Chang LJ, Price K, Shimadzu M, Hornykiewicz O, Haycock JW, Kish SJ. Striatal biopterin and tyrosine hydroxylase protein reduction in dopa-responsive dystonia. Neurology 1999; 53:1032-41. [PMID: 10496263 DOI: 10.1212/wnl.53.5.1032] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To determine the mechanism leading to striatal dopamine (DA) loss in dopa-responsive dystonia (DRD). BACKGROUND Although mutations in the gene GCH1, coding for the tetrahydrobiopterin (BH4) biosynthetic enzyme guanosine triphosphate-cyclohydrolase I, have been identified in some patients with DRD, the actual status of brain BH4 (the cofactor for tyrosine hydroxylase [TH]) is unknown. METHODS The authors sequenced GCH1 and measured levels of total biopterin (BP) and total neopterin (NP), TH, and dopa decarboxylase (DDC) proteins, and the DA and vesicular monoamine transporters (DAT, VMAT2) in autopsied brain of two patients with typical DRD. RESULTS Patient 1 had two GCH1 mutations but Patient 2 had no mutation in the coding region of this gene. Striatal BP levels were markedly reduced (<20% of control subjects) in both patients and were also low in two conditions characterized by degeneration of nigrostriatal DA neurons (PD and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine treated primate), whereas brain NP concentrations were selectively decreased (<45%) in the DRD patients. In the putamen, both DRD patients had severely reduced (<3%) TH protein levels but had normal concentrations of DDC protein, DAT, and VMAT2. CONCLUSIONS The data suggest that 1) brain BH4 is decreased substantially in dopa-responsive dystonia, 2) dopa-responsive dystonia can be distinguished from degenerative nigrostriatal dopamine deficiency disorders by the presence of reduced brain neopterin, and 3) the striatal dopamine reduction in dopa-responsive dystonia is caused by decreased TH activity due to low cofactor concentration and to actual loss of TH protein. This reduction of TH protein, which might be explained by reduced enzyme stability/expression consequent to congenital BH4 deficiency, can be expected to limit the efficacy of acute BH4 administration on dopamine biosynthesis in dopa-responsive dystonia.
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Affiliation(s)
- Y Furukawa
- Human Neurochemical Pathology Laboratory, Centre for Addiction and Mental Health, The Clarke Division, Toronto, Ontario, Canada
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17
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Mancini R, Saracino F, Buscemi G, Fischer M, Schramek N, Bracher A, Bacher A, Gütlich M, Carbone ML. Complementation of the fol2 deletion in Saccharomyces cerevisiae by human and Escherichia coli genes encoding GTP cyclohydrolase I. Biochem Biophys Res Commun 1999; 255:521-7. [PMID: 10049741 DOI: 10.1006/bbrc.1998.9951] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Saccharomyces cerevisiae is so far the only organism where a knock-out mutant in the gene encoding GTP cyclohydrolase I (FOL2) has been obtained. GTP cyclohydrolase I controls the de novo biosynthetic pathway of tetrahydrobiopterin and folic acid. Since deletion of yeast FOL2 leads to a recessive auxotrophy for folinic acid, we used a yeast fol2Delta mutant for an in vivo functional assay of heterologous GTP cyclohydrolases I. We show that the GTP cyclohydrolase I, encoded either by the E. coli folE gene or by the human cDNA, complements the yeast fol2Delta mutation by restoring folate prototrophy. Furthermore the folE-3x allele of the E. coli gene, carrying three base substitutions, failed to complement the yeast fol2Delta defect. This allele behaved as a negative semidominant to the wild type folE and, when overexpressed, completely abolished complementation of fol2Delta by folE. Thus, the yeast fol2 null mutant is a suitable system to characterize mutations in genes encoding GTP cyclohydrolase I.
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Affiliation(s)
- R Mancini
- Dipartimento di Genetica e di Biologia dei Microrganismi, Università di Milano, Italy
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18
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Nagatsu T, Ichinose H. Molecular biology of catecholamine-related enzymes in relation to Parkinson's disease. Cell Mol Neurobiol 1999; 19:57-66. [PMID: 10079965 DOI: 10.1023/a:1006912523846] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
1. Catecholamine (dopamine, norepinephrine, and epinephrine) biosynthesis is regulated by tyrosine hydroxylase (TH). TH activity is regulated by the concentration of the cofactor tetrahydrobiopterin (BH4), whose level is regulated by GTP cyclohydrolase I (GCH) activity. Thus, GCH activity indirectly regulates TH activity and catecholamine levels. 2. TH activity in the nigrostriatal dopaminergic neurons is most sensitive to the decrease in BH4. 3. Mutations of GCH result in reductions in GCH activity, BH4, TH activity, and dopamine, causing either recessively inherited GCH deficiency or dominantly inherited hereditary progressive dystonia [HPD; Segawa's disease; also called dopa-responsive dystonia (DRD)]. 4. In juvenile parkinsonism and Parkinson's disease, which have dopamine deficiency in the basal ganglia as HPD/DRD, the GCH gene may be normal, and the molecular mechanism of the dopamine deficiency in the basal ganglia is different from that in HPD/DRD.
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Affiliation(s)
- T Nagatsu
- Institute for Comprehensive Medical Science, Graduate School of Medicine, Fujita Health University, Aichi, Japan
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19
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Characterization of intrastriatal recombinant adeno-associated virus-mediated gene transfer of human tyrosine hydroxylase and human GTP-cyclohydrolase I in a rat model of Parkinson's disease. J Neurosci 1998. [PMID: 9592104 DOI: 10.1523/jneurosci.18-11-04271.1998] [Citation(s) in RCA: 168] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
To achieve local, continuous L-DOPA delivery in the striatum by gene replacement as a model for a gene therapy for Parkinson's disease, the present studies used high titer purified recombinant adeno-associated virus (rAAV) containing cDNAs encoding human tyrosine hydroxylase (hTH) or human GTP-cyclohydrolase I [GTPCHI, the rate-limiting enzyme for tetrahydrobiopterin (BH4) synthesis] or both to infect the 6-OHDA denervated rat striatum. Striatal TH and GTPCHI staining was observed 3 weeks after rAAV transduction, with little detectable perturbation of the tissue. Six months after intrastriatal rAAV transduction, TH staining was present but apparently reduced compared with the 3 week survival time. In a separate group of animals, striatal TH staining was demonstrated 1 year after rAAV transduction. Double staining studies using the neuronal marker NeuN indicated that >90% of rAAV-transduced cells expressing hTH were neurons. Microdialysis experiments indicated that only those lesioned animals that received the mixture of MD-TH and MD-GTPCHI vector displayed BH4 independent in vivo L-DOPA production (mean approximately 4-7 ng/ml). Rats that received the hTH rAAV vector alone produced measurable L-DOPA (mean approximately 1-4 ng/ml) only after receiving exogenous BH4. L-Aromatic amino acid decarboxylase blockade, but not 100 mM KCl-induced depolarization, enhanced L-DOPA overflow, and animals in the non-hTH groups (GTPCHI and alkaline phosphatase) yielded minimal L-DOPA. Although elevated L-DOPA was observed in animals that received mixed hTH and hGTPCHI rAAV vectors, there was no reduction of apomorphine-induced rotational behavior 3 weeks after intrastriatal vector injection. These data demonstrate that purified rAAV, a safe and nonpathogenic viral vector, mediates long-term striatal hTH transgene expression in neurons and can be used to successfully deliver L-DOPA to the striatum.
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20
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Leff SE, Rendahl KG, Spratt SK, Kang UJ, Mandel RJ. In vivo L-DOPA production by genetically modified primary rat fibroblast or 9L gliosarcoma cell grafts via coexpression of GTPcyclohydrolase I with tyrosine hydroxylase. Exp Neurol 1998; 151:249-64. [PMID: 9628761 DOI: 10.1006/exnr.1998.6803] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To investigate the biochemical requirements for in vivo L-DOPA production by cells genetically modified ex vivo in a rat model of Parkinson's disease (PD), rat syngeneic 9L gliosarcoma and primary Fischer dermal fibroblasts (FDFs) were transduced with retroviral vectors encoding the human tyrosine hydroxylase 2 (hTH2) and human GTP cyclohydrolase I (hGTPCHI) cDNAs. As GTPCHI is a rate-limiting enzyme in the pathway for synthesis of the essential TH cofactor, tetrahydrobiopterin (BH4), only hTH2 and GTPCHI cotransduced cultured cells produced L-DOPA in the absence of added BH4. As striatal BH4 levels in 6-hydroxydopamine (6-OHDA)-lesioned rats are minimal, the effects of cotransduction with hTH2 and hGTPCHI on L-DOPA synthesis by striatal grafts of either 9L cells or FDFs in unilateral 6-OHDA-lesioned rats were tested. Microdialysis experiments showed that those subjects that received cells cotransduced with hTH2 and hGTPCHI produced significantly higher levels of L-DOPA than animals that received either hTH2 or untransduced cells. However, animals that received transduced FDF grafts showed a progressive loss of transgene expression until expression was undetectable 5 weeks after engraftment. In FDF-engrafted animals, no differential effect of hTH2 vs hTH2 + hGTPCHI transgene expression on apomorphine-induced rotation was observed. The differences in L-DOPA production found with cells transduced with hTH2 alone and those cotransduced with hTH2 and hGTPCHI show that BH4 is critical to the restoration of the capacity for L-DOPA production and that GTPCHI expression is an effective means of supplying BH4 in this rat model of PD.
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MESH Headings
- 3T3 Cells
- Animals
- Antioxidants/metabolism
- Antiparkinson Agents/pharmacology
- Apomorphine/pharmacology
- Behavior, Animal/drug effects
- Biopterins/analogs & derivatives
- Biopterins/metabolism
- Corpus Striatum/chemistry
- Corpus Striatum/enzymology
- Corpus Striatum/pathology
- Dihydroxyphenylalanine/metabolism
- Disease Models, Animal
- Fibroblasts/cytology
- Fibroblasts/enzymology
- Fibroblasts/transplantation
- GTP Cyclohydrolase/metabolism
- Gene Expression Regulation, Enzymologic/physiology
- Genetic Therapy
- Gliosarcoma
- Humans
- Levodopa/biosynthesis
- Male
- Mice
- Microdialysis
- Parkinson Disease, Secondary/metabolism
- Parkinson Disease, Secondary/surgery
- Parkinson Disease, Secondary/therapy
- Rats
- Rats, Inbred F344
- Recombinant Fusion Proteins/physiology
- Retroviridae/genetics
- Transformation, Genetic
- Transgenes/physiology
- Tumor Cells, Cultured/metabolism
- Tumor Cells, Cultured/transplantation
- Tyrosine 3-Monooxygenase/metabolism
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Affiliation(s)
- S E Leff
- Department of Gene Therapy Applications, Cell Genesys Inc., 342 Lakeside Drive, Foster City, California, 94404, USA.
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21
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Mandel RJ, Rendahl KG, Spratt SK, Snyder RO, Cohen LK, Leff SE. Characterization of intrastriatal recombinant adeno-associated virus-mediated gene transfer of human tyrosine hydroxylase and human GTP-cyclohydrolase I in a rat model of Parkinson's disease. J Neurosci 1998; 18:4271-84. [PMID: 9592104 PMCID: PMC6792786] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
To achieve local, continuous L-DOPA delivery in the striatum by gene replacement as a model for a gene therapy for Parkinson's disease, the present studies used high titer purified recombinant adeno-associated virus (rAAV) containing cDNAs encoding human tyrosine hydroxylase (hTH) or human GTP-cyclohydrolase I [GTPCHI, the rate-limiting enzyme for tetrahydrobiopterin (BH4) synthesis] or both to infect the 6-OHDA denervated rat striatum. Striatal TH and GTPCHI staining was observed 3 weeks after rAAV transduction, with little detectable perturbation of the tissue. Six months after intrastriatal rAAV transduction, TH staining was present but apparently reduced compared with the 3 week survival time. In a separate group of animals, striatal TH staining was demonstrated 1 year after rAAV transduction. Double staining studies using the neuronal marker NeuN indicated that >90% of rAAV-transduced cells expressing hTH were neurons. Microdialysis experiments indicated that only those lesioned animals that received the mixture of MD-TH and MD-GTPCHI vector displayed BH4 independent in vivo L-DOPA production (mean approximately 4-7 ng/ml). Rats that received the hTH rAAV vector alone produced measurable L-DOPA (mean approximately 1-4 ng/ml) only after receiving exogenous BH4. L-Aromatic amino acid decarboxylase blockade, but not 100 mM KCl-induced depolarization, enhanced L-DOPA overflow, and animals in the non-hTH groups (GTPCHI and alkaline phosphatase) yielded minimal L-DOPA. Although elevated L-DOPA was observed in animals that received mixed hTH and hGTPCHI rAAV vectors, there was no reduction of apomorphine-induced rotational behavior 3 weeks after intrastriatal vector injection. These data demonstrate that purified rAAV, a safe and nonpathogenic viral vector, mediates long-term striatal hTH transgene expression in neurons and can be used to successfully deliver L-DOPA to the striatum.
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Affiliation(s)
- R J Mandel
- Department of Gene Therapy Applications, Cell Genesys Inc., Foster City, California 94404, USA
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22
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Walter R, Linscheid P, Blau N, Kierat L, Schaffner A, Schoedon G. Induction of tetrahydrobiopterin synthesis in human umbilical vein smooth muscle cells by inflammatory stimuli. Immunol Lett 1998; 60:13-7. [PMID: 9541457 DOI: 10.1016/s0165-2478(97)00123-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Tetrahydrobiopterin (BH4) is an obligatory cofactor and regulator of nitric oxide synthases (NOS). We evaluated the biosynthesis of BH4 in human umbilical vein smooth muscle cells (HUVSMC). Trace amounts of BH4 were found intra- and extracellularly in untreated cells. When HUVSMC were activated by individual inflammatory stimuli (IL-1beta, TNFalpha, IFNgamma or LPS), both intra- and extracellular levels of BH4 increased significantly, with TNFalpha being the most potent single stimulus. Combined inflammatory cytokines synergized in the induction of an up to 600-fold increase of BH4 synthesis. Addition of LPS to the cytokine mixture led to a further increase of BH4 synthesis. Neopterin, a product of the first intermediate in BH4 biosynthesis, was also raised, but to a much lesser extent. The increase of BH4 synthesis was paralleled by an enhanced expression of isoform-1 (the only isoform coding for the active enzyme) of GTP cyclohydrolase I in cytokine treated cells. Our results show for the first time that BH4 biosynthesis is strongly induced by combinations of inflammatory stimuli in HUVSMC. The importance of BH4-dependent NO synthesis in HUVSMC needs, however, additional detailed studies.
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Affiliation(s)
- R Walter
- Department of Medicine, University Hospital, Zürich, Switzerland.
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23
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Dassesse D, Hemmens B, Cuvelier L, Résibois A. GTP-cyclohydrolase-I like immunoreactivity in rat brain. Brain Res 1997; 777:187-201. [PMID: 9449428 DOI: 10.1016/s0006-8993(97)01111-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
GTPCH-I immunoreactive structures in the rat brain were studied using a polyclonal antibody raised in the chick. General mapping was made using the avidin-biotin-peroxidase technique and compared with the distribution of tyrosine hydroxylase and serotonin immunoreactivities. Double immunofluorescence was performed in order to establish real intracellular colocalization. GTPCH-I immunoreactivity was generally found to be low. Immunostained neurons were present in all the serotonin cell groups. In catecholaminergic neurons, although tyrosine hydroxylase immunoreactivity was always very high, GTPCH-I immunoreactivity was extremely variable, from relatively strong (substantia nigra, ventral tegmental area) to low (locus coeruleus, caudal part of the hypothalamus), extremely low (rostral hypothalamus, ventral brainstem) or almost absent (dorsal brainstem, some hypothalamic nuclei). When feasible, double immunolabeling revealed that all the serotonin cells and most of the tyrosine hydroxylase cells were also expressing GTPCH-I. Our results argue in favor of a regulation of tyrosine hydroxylase activity by the intracellular synthesis of BH4.
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Affiliation(s)
- D Dassesse
- Laboratoire d'Histologie, Faculté de Médecine, Université Libre de Bruxelles, Belgium
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24
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Serova LI, Nankova B, Kvetnansky R, Sabban EL. Immobilization Stress Elevates GTP Cyclohydrolase I mRNA Levels in Rat Adrenals Predominantly by Hormonally Mediated Mechanisms. Stress 1997; 1:135-144. [PMID: 9787239 DOI: 10.3109/10253899709001103] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
GTP cyclohydrolase I (GTPCH) is the rate-limiting enzyme in the biosynthesis of tetrahydrobiopterin, the cofactor for catecholamine, indolamine and nitric oxide biosynthesis. In this study we examined the effect of immobilization stress on GTPCH mRNA levels and the mechanism(s) of stress-induced changes in adrenomedullary GTPCH mRNA levels. We used reverse-polymerase chain reaction to isolate and clone a cDNA corresponding to nucleotides 269 to 570 of rat GTPCH. Northern blot analysis with a cRNA probe revealed two species of GTPCH mRNA (about 3.6 and 1.2 kb) in rat adrenal medulla and cortex, and in PC12 cells. The levels of both forms of GTPCH mRNA were significantly increased 3-5 fold in adrenal medulla by a single 2 hour immobilization and by repeated immobilizations (2 hours a day for 2 days). Hypophysectomy had little effect on their basal levels but prevented the stress elicited rise in both GTPCH mRNAs. In contrast, unilateral transection of the splanchnic nerve did not affect induction of the 3.6 kb GTPCH mRNA by stress. Combined denervation with hypophysectomy completely blocked the induction of both GTPCH mRNA species by immobilization stress. Thus, stress elicits elevation of both forms of GTPCH mRNA by a mechanism requiring an intact pituitary-adrenocortical axis.
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Affiliation(s)
- LI Serova
- Department of Biochemistry and Molecular Biology, New York Medical College, Valhalla, N.Y. 10595 USA
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25
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Abstract
Tetrahydrobiopterin deficiencies are highly heterogeneous disorders, with more than 30 molecular lesions identified in the past 2 years in the GTP cyclohydrolase I and 6-pyruvoyl-tetrahydropterin synthase genes. The spectrum of mutations causing a reduction of these two biosynthetic enzymes is reviewed. Only three mutations, two present homozygously, are reported in the GTP cyclohydrolase I gene to cause the rare autosomal recessively inherited form of hyperphenylalaninemia. Most of the other mutations, which are scattered over the entire coding region for the six exon-containing GTP cyclohydrolase I gene, are observed in a heterozygous state with the wild-type allele and are associated with the dominant DOPA-responsive dystonia. Compound heterozygous or homozygous mutations spread over all six exons encoding the 6-pyruvoyl-tetrahydropterin synthase cause an autosomal recessively inherited variant of hyperphenylalaninemia, mostly accompanied by a deficiency of dopamine and serotonin.
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Affiliation(s)
- B Thöny
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital, Zurich, Switzerland
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26
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Werner ER, Wachter H, Werner-Felmayer G. Determination of tetrahydrobiopterin biosynthetic activities by high-performance liquid chromatography with fluorescence detection. Methods Enzymol 1997; 281:53-61. [PMID: 9250966 DOI: 10.1016/s0076-6879(97)81008-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- E R Werner
- Institut für Medizinische Chemie und Biochemie, Universität Innsbruck, Austria
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27
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Witter K, Cahill DJ, Werner T, Ziegler I, Rödl W, Bacher A, Gütlich M. Molecular cloning of a cDNA coding for GTP cyclohydrolase I from Dictyostelium discoideum. Biochem J 1996; 319 ( Pt 1):27-32. [PMID: 8870645 PMCID: PMC1217731 DOI: 10.1042/bj3190027] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The GTP cyclohydrolase I (GTP-CH) gene of the cellular slime mould Dictyostelium discoideum has been cloned and sequenced. The 855 bp cDNA of this gene contains the open reading frame (ORF) encoding 232 amino acids with a predicted molecular mass of approx. 26 kDa. Southern blot analysis indicated the presence of a single gene for GTP-CH in Dictyostelium. PCR amplification of the ORF from chromosomal DNA and sequencing showed the existence of a 101 bp intron in the GTP-CH gene of Dictyostelium discoideum. The amino acid sequence has 47% and 49% positional identity to those of the human and yeast enzymes respectively. Most of the sequence variation between species is located in the N-terminal part of the protein. The overall identity with the E. coli protein is markedly lower. The enzyme was expressed in E. coli and purified as a 68 kDa fusion protein with the maltose-binding protein of E. coli. GTP-CH of Dictyostelium is heat-stable and showed maximal activity at 60 degrees C. The Km value for GTP is 50 microM.
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Affiliation(s)
- K Witter
- GSF-Institut für Klinische Molekularbiologie, München, Germany
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28
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Werner ER, Werner-Felmayer G, Wachter H. High-performance liquid chromatographic methods for the quantification of tetrahydrobiopterin biosynthetic enzymes. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL APPLICATIONS 1996; 684:51-8. [PMID: 8906465 DOI: 10.1016/0378-4347(95)00507-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Tetrahydrobiopterin is a cofactor in hydroxylation reactions, including phenylalanine 4-monooxygenase, tyrosine 3-monooxygenase, tryptophan 5-monooxygenase, alkyl glycol ether monooxygenase and nitric oxide synthase. Determination of its biosynthesis is carried out to diagnose inherited diseases leading to partial defects in tetrahydrobiopterin synthesis. In addition, tetrahydrobiopterin synthesis is induced by proinflammatory cytokines, and intracellular levels of tetrahydro-biopterin in many cases limit the activity of tetrahydrobiopterin-dependent reactions, such as nitric oxide synthase in intact cells. Biosynthesis of tetrahydrobiopterin from guanosine 5'-triphosphate (GTP) requires the action of three enzymes, GTP-cyclohydrolase I (E.C. 3.5.4.16), 6-pyruvoyl tetrahydropterin synthase (EC, 4.6.1.10) and sepiapterin reductase (E.C. 1.1.1.153). Methods for quantification of biopterin and related pteridines in biological matrices by HPLC and application of these for determining the activity of the three tetrahydrobiopterin biosynthetic enzymes are reviewed in this article.
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Affiliation(s)
- E R Werner
- Institut für Medizinische Chemie and Piechemic, Universität Innsbuck, Austria
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29
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Milstien S, Jaffe H, Kowlessur D, Bonner TI. Purification and cloning of the GTP cyclohydrolase I feedback regulatory protein, GFRP. J Biol Chem 1996; 271:19743-51. [PMID: 8702680 DOI: 10.1074/jbc.271.33.19743] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The activity of GTP cyclohydrolase I, the initial enzyme of the de novo pathway for biosynthesis of tetrahydrobiopterin, the cofactor required for aromatic amino acid hydroxylations and nitric oxide synthesis, is sensitive to end-product feedback inhibition by tetrahydrobiopterin. This inhibition by tetrahydrobiopterin is mediated by the GTP cyclohydrolase I feedback regulatory protein GFRP, previously named p35 (Harada, T., Kagamiyama, H., and Hatakeyama, K. (1993) Science 260, 1507-1510), and -phenylalanine specifically reverses the tetrahydrobiopterin-dependent inhibition. As a first step in the investigation of the physiological role of this unique mechanism of regulation, a convenient procedure has been developed to co-purify to homogeneity both GTP cyclohydrolase I and GFRP from rat liver. GTP cyclohydrolase I and GFRP exist in a complex which can be bound to a GTP-affinity column from which GTP cyclohydrolase I and GFRP are separately and selectively eluted. GFRP is dissociated from the GTP agarose-bound complex with 0.2 NaCl, a concentration of salt which also effectively blocks the tetrahydrobiopterin-dependent inhibitory activity of GFRP. GTP cyclohydrolase I is then eluted from the GTP-agarose column with GTP. Both GFRP and GTP cyclohydrolase I were then purified separately to near homogeneity by sequential high performance anion exchange and gel filtration chromatography. GFRP was found to have a native molecular mass of 20 kDa and consist of a homodimer of 9.5-kDa subunits. Based on peptide sequences obtained from purified GFRP, oligonucleotides were synthesized and used to clone a cDNA from a rat liver cDNA library by polymerase chain reaction-based methods. The cDNA contained an open reading frame that encoded a novel protein of 84 amino acids (calculated molecular mass 9665 daltons). This protein when expressed in Escherichia coli as a thioredoxin fusion protein had tetrahydrobiopterin-dependent GTP cyclohydrolase I inhibitory activity. Northern blot analysis indicated the presence of an 0.8-kilobase GFRP mRNA in most rat tissues, the amounts generally correlating with levels of GTP cyclohydrolase I and tetrahydrobiopterin. Thus, mRNA levels were relatively high in liver and kidney and somewhat lower in testis, heart, brain, and lung. These results suggest that GFRP is widely expressed and may play a role in regulating not only phenylalanine metabolism in the liver, but also the production of biogenic amine neurotransmitters as well as nitric oxide synthesis.
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Affiliation(s)
- S Milstien
- Laboratory of Cell Biology, National Institute of Mental Health
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30
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Witter K, Werner T, Blusch JH, Schneider EM, Riess O, Ziegler I, Rödl W, Bacher A, Gütlich M. Cloning, sequencing and functional studies of the gene encoding human GTP cyclohydrolase I. Gene 1996; 171:285-90. [PMID: 8666288 DOI: 10.1016/0378-1119(95)00886-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We have identified a genomic clone containing the 5' regulatory region of the gene GTP-CH encoding human GTP cyclohydrolase I. The transcription start point (tsp) was mapped by 5'-rapid amplification of cDNA ends (5'-RACE). The 2.6-kb region upstream from the tsp showed promoter activity when ligated upstream from a reporter gene. The truncation of approximately 2 kb of the promoter did not change expression activity, while a further removal of 243 bp halved the activity. The promoter contains CCAAT and TATA boxes. The GC-rich region close to the tsp, which contains several putative Sp1-responsive elements, is required for maximum promoter activity. Interferon-gamma treatment of B-cells transfected with reporter constructs had no influence on the expression activity.
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Affiliation(s)
- K Witter
- GSF-Institut für Klinische Molekularbiologie, München, Germany
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31
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Gütlich M, Witter K, Bourdais J, Veron M, Rödl W, Ziegler I. Control of 6-(D-threo-1',2'-dihydroxypropyl) pterin (dictyopterin) synthesis during aggregation of Dictyostelium discoideum. Involvement of the G-protein-linked signalling pathway in the regulation of GTP cyclohydrolase I activity. Biochem J 1996; 314 ( Pt 1):95-101. [PMID: 8660315 PMCID: PMC1217057 DOI: 10.1042/bj3140095] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
6-(D-threo-1',2'-Dihydroxypropylpterin (dictyopterin) has been identified in extracts of growing Dictyostelium dicoideum cells [Klein, Thiery and Tatischeff (1990) Eur. J. Biochem. 187, 665-669]. We demonstrate that it originates from GTP by de novo biosynthesis and that the first committed step is catalysed by GTP cyclohydrolase I, yielding dihydroneopterin triphosphate [neopterin is 6-(D-erythro-1',2',3'-trihydroxypropyl) pterin]. The GTP cyclohydrolase I activity is found in the cytosolic fraction and in a membrane-associated form. The level of a 0.9 kb mRNA coding for GTP cyclohydrolase I decreases to about 10% of its initial value within 2 h after Dictyostelium cells start development induced by starvation. In the cytosolic fraction, the specific activities of GTP cyclohydrolase I, as well as the concentrations of (6R/S)-5,6,7,8-tetrahydrodictyopterin (H4dictyopterin), follow this decline of the mRNA level. In the particulate fraction, however, the specific activities of GTP cyclohydrolase I and, in consequence, H4dictyopterin synthesis, transiently increase and reach a maximum after 4-5 h of development. The time-course of H4dictyopterin concentrations in the starvation medium closely correlates with its production in the membrane fraction. The activity of membrane-associated GTP cyclohydrolase I can be increased by pre-incubation of the cell lysate with guanosine 5'-[gamma-thio]triphosphate and Mg2+. This GTP analogue does not serve as a substrate and has no direct effect on the enzyme activity, indicating that a G-protein-linked signalling pathway is involved in the regulation of GTP cyclohydrolase I activity and thus in H4dictyopterin production during early development of D. discoideum.
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Affiliation(s)
- M Gütlich
- GSF-Institut für Klinische Molekularbiologie und Tumorgenetik, München, Germany
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32
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Werner ER, Werner-Felmayer G, Wachter H, Mayer B. Biosynthesis of nitric oxide: dependence on pteridine metabolism. Rev Physiol Biochem Pharmacol 1996; 127:97-135. [PMID: 8533013 DOI: 10.1007/bfb0048266] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- E R Werner
- Institut für Medizinische Chemie und Biochemie, Universität Innsbruck, Austria
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33
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Ichinose H, Ohye T, Matsuda Y, Hori T, Blau N, Burlina A, Rouse B, Matalon R, Fujita K, Nagatsu T. Characterization of mouse and human GTP cyclohydrolase I genes. Mutations in patients with GTP cyclohydrolase I deficiency. J Biol Chem 1995; 270:10062-71. [PMID: 7730309 DOI: 10.1074/jbc.270.17.10062] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
GTP cyclohydrolase I is the first and rate-limiting enzyme for the biosynthesis of tetrahydrobiopterin in mammals. Previously, we reported three species of human GTP cyclohydrolase I cDNA in a human liver cDNA library (Togari, A., Ichinose, H., Matsumoto, S., Fujita, K., and Nagatsu, T. (1992) Biochem. Biophys. Res. Commun. 187, 359-365). Furthermore, very recently, we found that the GTP cyclohydrolase I gene is causative for hereditary progressive dystonia with marked diurnal fluctuation, also known as DOPA-responsive dystonia (Ichinose, H., Ohye, T., Takahashi, E., Seki, N., Hori, T., Segawa, M., Nomura, Y., Endo, K., Tanaka, H., Tsuji, S., Fujita, K., and Nagatsu, T. (1994) Nature Genetics 8, 236-242). To clarify the mechanisms that regulate transcription of the GTP cyclohydrolase I gene and to generate multiple species of mRNA, we isolated genomic DNA clones for the human and mouse GTP cyclohydrolase I genes. Structural analysis of the isolated clones revealed that the GTP cyclohydrolase I gene is encoded by a single copy gene and is composed of six exons spanning approximately 30 kilobases. We sequenced all exon/intron boundaries of the human and mouse genes. Structural analysis also demonstrated that the heterogeneity of GTP cyclohydrolase I mRNA is caused by an alternative usage of the splicing acceptor site at the sixth exon. The transcription start site of the mouse GTP cyclohydrolase I gene and the 5'-flanking sequences of the mouse and human genes were determined. We performed regional mapping of the mouse gene by fluorescence in situ hybridization, and the mouse GTP cyclohydrolase I gene was assigned to region C2-3 of mouse chromosome 14. We identified missense mutations in patients with GTP cyclohydrolase I deficiency and expressed mutated enzymes in Escherichia coli to confirm alterations in the enzyme activity.
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Affiliation(s)
- H Ichinose
- Institute for Comprehensive Medical Science, Fujita Health University, Aichi, Japan
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34
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Nomura T, Ohtsuki M, Matsui S, Sumi-Ichinose C, Nomura H, Hagino Y, Iwase K, Ichinose H, Fujita K, Nagatsu T. Isolation of a full-length cDNA clone for human GTP cyclohydrolase I type 1 from pheochromocytoma. J Neural Transm (Vienna) 1995; 101:237-42. [PMID: 8695054 DOI: 10.1007/bf01271561] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Although the existence of three different cDNA forms of human GTP cyclohydrolase I (GCH I) have been reported (Togari et al., 1992), the full-length sequence of any human GCH I cDNA involving poly (A) tail has not yet been documented. In the present study, we first isolated a full-length cDNA clone encoding human GCH I type 1 from human pheochromocytoma cDNA library. The length of the cDNA insert was 2,921 base pairs including poly (A) tail. RNA blot analysis showed a single mRNA species of 4.0 kb in human pheochromocytoma tissue.
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Affiliation(s)
- T Nomura
- Department of Pharmacology, Fujita Health University School of Medicine, Aichi, Japan
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