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Agarwal P, Meena S, Meena LS. Comprehensive analysis of GTP cyclohydrolase I activity in Mycobacterium tuberculosis H 37 Rv via in silico studies. Biotechnol Appl Biochem 2020; 68:756-768. [PMID: 32691412 DOI: 10.1002/bab.1988] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 07/14/2020] [Indexed: 11/06/2022]
Abstract
GTP cyclohydrolase I enzyme (GTPCH-I) is a rate limiting enzyme in the biosynthesis pathway of tetrahydrobiopterin (BH4) and tetrahydrofolate (THF) compounds; latter being are an essential compounds involved in many biological functions. This enzyme has been evaluated structurally and functionally in many organisms to understand its putative role in cell processes, kinetics, regulations, drug targeting in infectious diseases, pain sensitivity in humans, and so on. In Mycobacterium tuberculosis (a human pathogen causing tuberculosis), this GTPCH-I activity has been predicted to be present in Rv3609c gene (folE) of H37 Rv strain, which till date has not been studied in detail. In order to understand in depth, the structure and function of folE protein in M. tuberculosis H37 Rv, in silico study was designed by using many different bioinformatics tools. Comparative and structural analysis predicts that Rv3609c gene is similar to folE protein ortholog of Listeria monocytogenes (cause food born disease), and uses zinc ion as a cofactor for its catalysis. Result shows that mutation of folE protein at 52th residue from tyrosine to glycine or variation in pH and temperature can lead to high destability in protein structure. Studies here have also predicted about the functional regions and interacting partners involved with folE protein. This study has provided clues to carry out experimentally the analysis of folE protein in mycobacteria and if found suitable will be used for drug targeting.
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Affiliation(s)
- Preeti Agarwal
- CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi, India
| | - Swati Meena
- CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi, India
| | - Laxman S Meena
- CSIR-Institute of Genomics and Integrative Biology, Mall Road, Delhi, India
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Differential Expression of Neuroinflammatory mRNAs in the Rat Sciatic Nerve Following Chronic Constriction Injury and Pain-Relieving Nanoemulsion NSAID Delivery to Infiltrating Macrophages. Int J Mol Sci 2019; 20:ijms20215269. [PMID: 31652890 PMCID: PMC6862677 DOI: 10.3390/ijms20215269] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 10/17/2019] [Accepted: 10/21/2019] [Indexed: 12/13/2022] Open
Abstract
The neuroinflammatory response to peripheral nerve injury is associated with chronic pain and significant changes in the molecular expression profiles of mRNAs in neurons, glia and infiltrating immune cells. Chronic constriction injury (CCI) of the rat sciatic nerve provides an opportunity to mimic neuropathic injury and quantitatively assess behavior and differential gene expression in individual animals. Previously, we have shown that a single intravenous injection of nanoemulsion containing celecoxib (0.24 mg/kg) reduces inflammation of the sciatic nerve and relieves pain-like behavior for up to 6 days. Here, we use this targeted therapy to explore the impact on mRNA expression changes in both pain and pain-relieved states. Sciatic nerve tissue recovered from CCI animals is used to evaluate the mRNA expression profiles utilizing quantitative PCR. We observe mRNA changes consistent with the reduced recruitment of macrophages evident by a reduction in chemokine and cytokine expression. Furthermore, genes associated with adhesion of macrophages, as well as changes in the neuronal and glial mRNAs are observed. Moreover, genes associated with neuropathic pain including Maob, Grin2b/NMDAR2b, TrpV3, IL-6, Cacna1b/Cav2.2, Itgam/Cd11b, Scn9a/Nav1.7, and Tac1 were all found to respond to the celecoxib loaded nanoemulsion during pain relief as compared to those animals that received drug-free vehicle. These results demonstrate that by targeting macrophage production of PGE2 at the site of injury, pain relief includes partial reversal of the gene expression profiles associated with chronic pain.
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Zschiebsch K, Fischer C, Wilken‐Schmitz A, Geisslinger G, Channon K, Watschinger K, Tegeder I. Mast cell tetrahydrobiopterin contributes to itch in mice. J Cell Mol Med 2019; 23:985-1000. [PMID: 30450838 PMCID: PMC6349351 DOI: 10.1111/jcmm.13999] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 09/25/2018] [Accepted: 10/13/2018] [Indexed: 12/28/2022] Open
Abstract
GTP cyclohydrolase (GCH1) governs de novo synthesis of the enzyme cofactor, tetrahydrobiopterin (BH4), which is essential for biogenic amine production, bioactive lipid metabolism and redox coupling of nitric oxide synthases. Overproduction of BH4 via upregulation of GCH1 in sensory neurons is associated with nociceptive hypersensitivity in rodents, and neuron-specific GCH1 deletion normalizes nociception. The translational relevance is revealed by protective polymorphisms of GCH1 in humans, which are associated with a reduced chronic pain. Because myeloid cells constitute a major non-neuronal source of BH4 that may contribute to BH4-dependent phenotypes, we studied here the contribution of myeloid-derived BH4 to pain and itch in lysozyme M Cre-mediated GCH1 knockout (LysM-GCH1-/- ) and overexpressing mice (LysM-GCH1-HA). Unexpectedly, knockout or overexpression in myeloid cells had no effect on nociceptive behaviour, but LysM-driven GCH1 knockout reduced, and its overexpression increased the scratching response in Compound 48/80 and hydroxychloroquine-evoked itch models, which involve histamine and non-histamine dependent signalling pathways. Mechanistically, GCH1 overexpression increased BH4, nitric oxide and hydrogen peroxide, and these changes were associated with increased release of histamine and serotonin and degranulation of mast cells. LysM-driven GCH1 knockout had opposite effects, and pharmacologic inhibition of GCH1 provided even stronger itch suppression. Inversely, intradermal BH4 provoked scratching behaviour in vivo and BH4 evoked an influx of calcium in sensory neurons. Together, these loss- and gain-of-function experiments suggest that itch in mice is contributed by BH4 release plus BH4-driven mediator release from myeloid immune cells, which leads to activation of itch-responsive sensory neurons.
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Affiliation(s)
- Katja Zschiebsch
- Institute of Clinical PharmacologyGoethe‐University HospitalFrankfurtGermany
| | - Caroline Fischer
- Institute of Clinical PharmacologyGoethe‐University HospitalFrankfurtGermany
| | | | - Gerd Geisslinger
- Institute of Clinical PharmacologyGoethe‐University HospitalFrankfurtGermany
| | - Keith Channon
- Division of Cardiovascular MedicineUniversity of OxfordOxfordUK
| | - Katrin Watschinger
- Division of Biological ChemistryBiocenterMedical University of InnsbruckInnsbruckAustria
| | - Irmgard Tegeder
- Institute of Clinical PharmacologyGoethe‐University HospitalFrankfurtGermany
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Douglas G, Hale AB, Patel J, Chuaiphichai S, Al Haj Zen A, Rashbrook VS, Trelfa L, Crabtree MJ, McNeill E, Channon KM. Roles for endothelial cell and macrophage Gch1 and tetrahydrobiopterin in atherosclerosis progression. Cardiovasc Res 2018; 114:1385-1399. [PMID: 29596571 PMCID: PMC6054219 DOI: 10.1093/cvr/cvy078] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 02/22/2018] [Accepted: 03/26/2018] [Indexed: 12/17/2022] Open
Abstract
Aims GTP cyclohydrolase I catalyses the first and rate-limiting reaction in the synthesis of tetrahydrobiopterin (BH4), an essential cofactor for nitric oxide synthases (NOS). Both eNOS and iNOS have been implicated in the progression of atherosclerosis, with opposing effects in eNOS and iNOS knockout mice. However, the pathophysiologic requirement for BH4 in regulating both eNOS and iNOS function, and the effects of loss of BH4 on the progression of atherosclerosis remains unknown. Methods and results Hyperlipidemic mice deficient in Gch1 in endothelial cells and leucocytes were generated by crossing Gch1fl/flTie2cre mice with ApoE-/- mice. Deficiency of Gch1 and BH4 in endothelial cells and myeloid cells was associated with mildly increased blood pressure. High fat feeding for 6 weeks in Gch1fl/flTie2CreApoE-/- mice resulted in significantly decreased circulating BH4 levels, increased atherosclerosis burden and increased plaque macrophage content. Gch1fl/flTie2CreApoE-/- mice showed hallmarks of endothelial cell dysfunction, with increased aortic VCAM-1 expression and decreased endothelial cell dependent vasodilation. Furthermore, loss of BH4 from pro-inflammatory macrophages resulted in increased foam cell formation and altered cellular redox signalling, with decreased expression of antioxidant genes and increased reactive oxygen species. Bone marrow chimeras revealed that loss of Gch1 in both endothelial cells and leucocytes is required to accelerate atherosclerosis. Conclusion Both endothelial cell and macrophage BH4 play important roles in the regulation of NOS function and cellular redox signalling in atherosclerosis.
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Affiliation(s)
- Gillian Douglas
- Division of Cardiovascular Medicine, BHF Centre of Research Excellence, Radcliffe Department of Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Ashley B Hale
- Division of Cardiovascular Medicine, BHF Centre of Research Excellence, Radcliffe Department of Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Jyoti Patel
- Division of Cardiovascular Medicine, BHF Centre of Research Excellence, Radcliffe Department of Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Surawee Chuaiphichai
- Division of Cardiovascular Medicine, BHF Centre of Research Excellence, Radcliffe Department of Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Ayman Al Haj Zen
- Division of Cardiovascular Medicine, BHF Centre of Research Excellence, Radcliffe Department of Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Victoria S Rashbrook
- Division of Cardiovascular Medicine, BHF Centre of Research Excellence, Radcliffe Department of Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Lucy Trelfa
- Division of Cardiovascular Medicine, BHF Centre of Research Excellence, Radcliffe Department of Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Mark J Crabtree
- Division of Cardiovascular Medicine, BHF Centre of Research Excellence, Radcliffe Department of Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Eileen McNeill
- Division of Cardiovascular Medicine, BHF Centre of Research Excellence, Radcliffe Department of Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Keith M Channon
- Division of Cardiovascular Medicine, BHF Centre of Research Excellence, Radcliffe Department of Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
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Prebble H, Cross S, Marks E, Healy J, Searle E, Aamir R, Butler A, Roake J, Hock B, Anderson N, Gieseg SP. Induced macrophage activation in live excised atherosclerotic plaque. Immunobiology 2018; 223:526-535. [DOI: 10.1016/j.imbio.2018.03.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 01/29/2018] [Accepted: 03/22/2018] [Indexed: 10/17/2022]
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Bulmer DC, Botha CA, Wheeldon A, Grey K, Mein CA, Lee K, Knowles CH, Winchester WJ, Aziz Q. Evidence of a role for GTP cyclohydrolase-1 in visceral pain. Neurogastroenterol Motil 2015; 27:656-62. [PMID: 25783971 DOI: 10.1111/nmo.12538] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 02/09/2015] [Indexed: 02/08/2023]
Abstract
BACKGROUND The enzyme guanosine triphosphate-cyclohydrolase-1 (GCH-1) is a rate limiting step in the de novo synthesis of tetrahydrobiopterin (BH4) a co-factor in monoamine synthesis and nitric oxide production. GCH-1 is strongly implicated in chronic pain based on data generated using the selective GCH-1 inhibitor 2,4-diamino-6-hydroxypyrimidine (DAHP), and studies which have identified a pain protective GCH-1 haplotype associated with lower BH4 production and reduced pain. METHODS To investigate the role for GCH-1 in visceral pain we examined the effects of DAHP on pain behaviors elicited by colorectal injection of mustard oil in rats, and the pain protective GCH-1 haplotype in healthy volunteers characterized by esophageal pain sensitivity before and after acid injury, and assessed using depression and anxiety questionnaires. KEY RESULTS In rodents pretreatment with DAHP produced a substantial dose related inhibition of pain behaviors from 10 to 180 mg/kg i.p. (p < 0.01 to 0.001). In healthy volunteers, no association was seen between the pain protective GCH-1 haplotype and the development of hypersensitivity following injury. However, a substantial increase in baseline pain thresholds was seen between first and second visits (26.6 ± 6.2 mA) in subjects who sensitized to esophageal injury and possessed the pain protective GCH-1 haplotype compared with all other groups (p < 0.05). Furthermore the same subjects who sensitized to acid and possessed the haplotype, also had significantly lower depression scores (p < 0.05). CONCLUSIONS & INFERENCES The data generated indicate that GCH-1 plays a role in visceral pain processing that requires more detailed investigation.
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Affiliation(s)
- D C Bulmer
- Wingate Institute of Neurogastroenterology, Blizard Institute, Bart's and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK; National Centre for Bowel Research and Surgical Innovation, Blizard Institute, Bart's and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK; GlaxoSmithKline Research & Development, Medicines Research Centre, Hertfordshire, UK
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Abstract
6R l-erythro-5,6,7,8-tetrahydrobiopterin (BH4) is an essential cofactor for several enzymes including phenylalanine hydroxylase and the nitric oxide synthases (NOS). Oral supplementation of BH4 has been successfully employed to treat subsets of patients with hyperphenylalaninaemia. More recently, research efforts have focussed on understanding whether BH4 supplementation may also be efficacious in cardiovascular disorders that are underpinned by reduced nitric oxide bioavailability. Whilst numerous preclinical and clinical studies have demonstrated a positive association between enhanced BH4 and vascular function, the efficacy of orally administered BH4 in human cardiovascular disease remains unclear. Furthermore, interventions that limit BH4 bioavailability may provide benefit in diseases where nitric oxide over production contributes to pathology. This review describes the pathways involved in BH4 bio-regulation and discusses other endogenous mechanisms that could be harnessed therapeutically to manipulate vascular BH4 levels.
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Affiliation(s)
- Anna Starr
- Pharmacology and Therapeutics Group, Institute of Pharmaceutical Science, School of Biomedical Sciences, King's College London, Franklin Wilkins Building, 150 Stamford Street,London SE1 9NH, United Kingdom
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Bousette N, Gramolini AO, Kislinger T. Proteomics-based investigations of animal models of disease. Proteomics Clin Appl 2012; 2:638-53. [PMID: 21136864 DOI: 10.1002/prca.200780043] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cells contain a large yet, constant genome, which contains all the coding information necessary to sustain cellular physiology. However, proteins are the end products of genes, and hence dictate the phenotype of cells and tissues. Therefore, proteomics can provide key information for the elucidation of physiological and pathophysiological mechanisms by identifying the protein profile from cells and tissues. The relatively novel techniques used for the study of proteomics thus have the potential to improve diagnostic, prognostic, as well as therapeutic avenues. In this review, we first discuss the benefits of animal models over the use of human samples for the proteomic analysis of human disease. Next, we aim to demonstrate the potential of proteomics in the elucidation of disease mechanisms that may not be possible by other conventional technologies. Following this, we describe the use of proteomics for the analysis of PTM and protein interactions in animal models and their relevance to the study of human disease. Finally, we discuss the development of clinical biomarkers for the early diagnosis of disease via proteomic analysis of animal models. We also discuss the development of standard proteomes and relate how this data will benefit future proteomic research. A comprehensive review of all animal models used in conjunction with proteomics is beyond the scope of this manuscript. Therefore, we aimed to cover a large breadth of topics, which together, demonstrate the potential of proteomics as a powerful tool in biomedical research.
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Affiliation(s)
- Nicolas Bousette
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada; Heart and Stroke/Richard Lewar Centre of Cardiovascular Excellence, Toronto, Ontario, Canada
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Abstract
Understanding and consequently treating neuropathic pain effectively is a challenge for modern medicine, as unlike inflammation, which can be controlled relatively well, chronic pain due to nerve injury is refractory to most current therapeutics. Here we define a target pathway for a new class of analgesics, tetrahydrobiopterin (BH4) synthesis and metabolism. BH4 is an essential co-factor in the synthesis of serotonin, dopamine, epinephrine, norepinephrine and nitric oxide and as a result, its availability influences many systems, including neurons. Following peripheral nerve damage, levels of BH4 are dramatically increased in sensory neurons, consequently this has a profound effect on the physiology of these cells, causing increased activity and pain hypersensitivity. These changes are principally due to the upregulation of the rate limiting enzyme for BH4 synthesis GTP Cyclohydrolase 1 (GCH1). A GCH1 pain-protective haplotype which decreases pain levels in a variety of settings, by reducing the levels of endogenous activation of this enzyme, has been characterized in humans. Here we define the control of BH4 homeostasis and discuss the consequences of large perturbations within this system, both negatively via genetic mutations and after pathological increases in the production of this cofactor that result in chronic pain. We explain the nature of the GCH1 reduced-function haplotype and set out the potential for a ' BH4 blocking' drug as a novel analgesic.
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Affiliation(s)
- Alban Latremoliere
- F.M. Kirby Neurobiology Center, Children’s Hospital Boston, Harvard Medical School, 3 Blackfan Circle, CLS 12260, Boston, MA 02115, USA
| | - Michael Costigan
- F.M. Kirby Neurobiology Center, Children’s Hospital Boston, Harvard Medical School, 3 Blackfan Circle, CLS 12260, Boston, MA 02115, USA
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Abstract
Tetrahydrobiopterin (BH4) is a multifunctional cofactor of aromatic amino acid hydroxylases and nitric oxide synthase (NOS) as well as an intracellular antioxidant in animals. Through regulation of NOS activity BH4 plays a pivotal role not only in a variety of normal cellular functions but also in the pathogenesis of cardiovascular and neurodegenerative diseases, which develop under oxidative stress conditions. It appears that a balanced interplay between BH4 and NOS is crucial for cellular fate. If cellular BH4 homeostasis maintained by BH4 synthesis and regeneration fails to cope with increased oxidative stress, NOS is uncoupled to generate superoxide rather than NO and, in turn, exacerbates impaired BH4 homeostasis, thereby leading to cell death. The fundamental biochemical events involved in the BH4-NOS interplay are essentially the same, as revealed in mammalian endothelial, cardiac, and neuronal cells. This review summarizes information on the cellular BH4 homeostasis in mammals, focusing on its regulation under normal and oxidative stress conditions.
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Du J, Wei N, Xu H, Ge Y, Vásquez-Vivar J, Guan T, Oldham KT, Pritchard KA, Shi Y. Identification and functional characterization of phosphorylation sites on GTP cyclohydrolase I. Arterioscler Thromb Vasc Biol 2009; 29:2161-8. [PMID: 19762783 PMCID: PMC2798731 DOI: 10.1161/atvbaha.109.194464] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE The posttranslational regulation of GTP cyclohydrolase I (GCH-1), the rate-limiting enzyme for tetrahydrobiopterin (BH4) synthesis, remains elusive. Here, we identified specific phosphorylation sites on GCH-1 and characterized the function of these sites. METHODS AND RESULTS Mass spectrometry studies showed overexpressed rat GCH-1 was phosphorylated at serine (S) 51, S167, and threonine (T) 231 in HEK293 cells, whereas a computational analysis of GCH-1 revealed 8 potential phosphorylation sites (S51, S72, T85, T91, T103, S130, S167 and T231). GCH-1 activity and BH4 were significantly decreased in cells transfected with the phospho-defective mutants (S72A, T85A, T91A, T103A, or S130A) and increased in cells transfected with the T231A mutant. BH4 and BH2 were increased in cells transfected with S51E, S72E, T85E, T91E, T103D, or T130D mutants, but decreased in cells transfected with the T231D mutant, whereas cells transfected with the S167A or the S167E mutant had increased BH2. Additionally, cells transfected with the T231A mutant had reduced GCH-1 nuclear localization and nuclear GCH-1 activity. CONCLUSIONS Our data suggest GCH-1 activity is regulated either positively by phosphorylation S51, S72, T85, T91, T103, and S130, or negatively at T231. Such information might be useful in designing new therapies aiming at improving BH4 bioavailability.
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Affiliation(s)
- Jianhai Du
- Division of Pediatric Surgery, Medical College of Wisconsin, Milwaukee, WI 53226
- Children’s Research Institution, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Na Wei
- Division of Pediatric Surgery, Medical College of Wisconsin, Milwaukee, WI 53226
- Children’s Research Institution, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Hao Xu
- Division of Pediatric Surgery, Medical College of Wisconsin, Milwaukee, WI 53226
- Children’s Research Institution, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Ying Ge
- Human Proteomics Program, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, 53706
| | | | - Tongju Guan
- Division of Pediatric Surgery, Medical College of Wisconsin, Milwaukee, WI 53226
- Children’s Research Institution, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Keith T. Oldham
- Division of Pediatric Surgery, Medical College of Wisconsin, Milwaukee, WI 53226
- Children’s Research Institution, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Kirkwood A. Pritchard
- Division of Pediatric Surgery, Medical College of Wisconsin, Milwaukee, WI 53226
- Children’s Research Institution, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Yang Shi
- Division of Pediatric Surgery, Medical College of Wisconsin, Milwaukee, WI 53226
- Children’s Research Institution, Medical College of Wisconsin, Milwaukee, WI 53226
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Vásquez-Vivar J. Tetrahydrobiopterin, superoxide, and vascular dysfunction. Free Radic Biol Med 2009; 47:1108-19. [PMID: 19628033 PMCID: PMC2852262 DOI: 10.1016/j.freeradbiomed.2009.07.024] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2008] [Revised: 06/20/2009] [Accepted: 07/15/2009] [Indexed: 01/06/2023]
Abstract
(6R)-5,6,7,8-Tetrahydrobiopterin (BH(4)) is an endogenously produced pterin that is found widely distributed in mammalian tissues. BH(4) works as a cofactor of aromatic amino acid hydroxylases and nitric oxide synthases. In the vasculature a deficit of BH(4) is implicated in the mechanisms of several diseases including atherosclerosis, hypertension, diabetic vascular disease, and vascular complications from cigarette smoking and environmental pollution. These ill-effects are connected to the ability of BH(4) to regulate reactive oxygen species levels in the endothelium. The possibility of using BH(4) as a therapeutical agent in cardiovascular medicine is becoming more compelling and many biochemical and physiological aspects involved in this application are currently under investigation. This review summarizes our current understanding of BH(4) reactivity and some aspects of cellular production and regulation.
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Affiliation(s)
- Jeannette Vásquez-Vivar
- Department of Biophysics, Free Radical Research Center, Redox Biology Program, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
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Nunes ACS, Kalkmann DC, Aragão FJL. Folate biofortification of lettuce by expression of a codon optimized chicken GTP cyclohydrolase I gene. Transgenic Res 2009; 18:661-7. [PMID: 19322672 DOI: 10.1007/s11248-009-9256-1] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2009] [Accepted: 03/12/2009] [Indexed: 10/21/2022]
Abstract
Folates are essential coenzymes involved in one-carbon metabolism. Folate deficiency is associated with a higher risk of newborns with neural tube defects, spina bifida, and anencephaly, and an increased risk of cardiovascular diseases, cancer, and impaired cognitive function in adults. In plants folates are synthesized in mitochondria from pterin precursors, which are synthesized from guanosine-5'-triphosphate (GTP) in the cytosol (pterin branch), and p-aminobenzoate (PABA), derived from chorismate in plastids (PABA branch). We generated transgenic lettuce lines expressing a synthetic codon-optimized GTP-cyclohydrolase I gene (gchI) based on native Gallus gallus gene. Immunoblotting analyses confirmed the presence of the gchI in transgenic lines. Twenty-nine transgenic lines were generated and 19 exhibited significant increase in the folate content, ranging from 2.1 to 8.5-fold higher when compared to non-transgenic lines. The folate content in enriched lettuce would provide 26% of the Dietary Reference Intakes for an adult, in a regular serving. Although the lettuce lines generated here exhibited high folate enhancement over the control, better folate enrichment could be further achieved by engineering simultaneously both PABA and pterin pathways.
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Affiliation(s)
- Aline C S Nunes
- Embrapa Recursos Genéticos e Biotecnologia, PqEB W5 Norte, Brasília, DF 70770-900, Brazil
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Byun J, Yoon J, Baek K. Analysis of two promoters that control the expression of the GTP cyclohydrolase I gene in Drosophila melanogaster. Mol Cells 2009; 27:583-9. [PMID: 19387565 DOI: 10.1007/s10059-009-0072-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2009] [Revised: 03/03/2009] [Accepted: 03/05/2009] [Indexed: 10/20/2022] Open
Abstract
GTP cyclohydrolase I (GTPCH) is a key enzyme in the de novo synthesis of tetrahydrobiopterin. Previously, the Drosophila melanogaster GTPCH gene has been shown to be expressed from two different promoters (P1 and P2). In our study, the 5'-flanking DNA regions required for P1 and P2 promoter activities were characterized using transient expression assay. The DNA regions between -98 and +31, and between -73 and +35 are required for efficient P1 and P2 promoter activities, respectively. The regions between -98 and -56 and between -73 and -41 may contain critical elements required for the expression of GTPCH in Drosophila. By aligning the nucleotide sequences in the P1 and P2 promoter regions of the Drosophila melanogaster and Drosophila virilis GTPCH genes, several conserved elements including palindromic sequences in the regions critical for P1 and P2 promoter activities were identified. Western blot analysis of transgenic flies transformed using P1 or P2 promoter-lacZ fusion plasmids further revealed that P1 promoter expression is restricted to the late pupae and adult developmental stages but that the P2 promoter driven expression of GTPCH is constitutive throughout fly development. In addition, X-gal staining of the embryos and imaginal discs of transgenic flies suggests that the P2 promoter is active from stage 13 of embryo and is generally active in most regions of the imaginal discs at the larval stages.
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Affiliation(s)
- Jaegoo Byun
- Graduate School of Biotechnology, Kyung Hee University, 446-701 Yongin, Korea
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Tatham AL, Crabtree MJ, Warrick N, Cai S, Alp NJ, Channon KM. GTP cyclohydrolase I expression, protein, and activity determine intracellular tetrahydrobiopterin levels, independent of GTP cyclohydrolase feedback regulatory protein expression. J Biol Chem 2009; 284:13660-13668. [PMID: 19286659 PMCID: PMC2679467 DOI: 10.1074/jbc.m807959200] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Revised: 03/10/2009] [Indexed: 11/06/2022] Open
Abstract
GTP cyclohydrolase I (GTPCH) is a key enzyme in the synthesis of tetrahydrobiopterin (BH4), a required cofactor for nitricoxide synthases and aromatic amino acid hydroxylases. Alterations of GTPCH activity and BH4 availability play an important role in human disease. GTPCH expression is regulated by inflammatory stimuli, in association with reduced expression of GTP cyclohydrolase feedback regulatory protein (GFRP). However, the relative importance of GTPCH expression versus GTPCH activity and the role of GFRP in relation to BH4 bioavailability remain uncertain. We investigated these relationships in a cell line with tet-regulated GTPCH expression and in the hph-1 mouse model of GTPCH deficiency. Doxycycline exposure resulted in a dose-dependent decrease in GTPCH protein and activity, with a strong correlation between GTPCH expression and BH4 levels (r(2) = 0.85, p < 0.0001). These changes in GTPCH and BH4 had no effect on GFRP expression or protein levels. GFRP overexpression and knockdown in tet-GCH cells did not alter GTPCH activity or BH4 levels, and GTPCH-specific knockdown in sEnd.1 endothelial cells had no effect on GFRP protein. In mouse liver we observed a graded reduction of GTPCH expression, protein, and activity, from wild type, heterozygote, to homozygote littermates, with a striking linear correlation between GTPCH expression and BH4 levels (r(2) = 0.82, p < 0.0001). Neither GFRP expression nor protein differed between wild type, heterozygote, nor homozygote mice, despite the substantial differences in BH4. We suggest that GTPCH expression is the primary regulator of BH4 levels, and changes in GTPCH or BH4 are not necessarily accompanied by changes in GFRP expression.
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Affiliation(s)
- Amy L Tatham
- Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
| | - Mark J Crabtree
- Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
| | - Nicholas Warrick
- Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
| | - Shijie Cai
- Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
| | - Nicholas J Alp
- Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom
| | - Keith M Channon
- Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom.
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Chiarini A, Armato U, Pacchiana R, Dal Pra I. Proteomic analysis of GTP cyclohydrolase 1 multiprotein complexes in cultured normal adult human astrocytes under both basal and cytokine-activated conditions. Proteomics 2009; 9:1850-60. [PMID: 19294699 DOI: 10.1002/pmic.200800561] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Indexed: 12/28/2022]
Abstract
GTP cyclohydrolase 1 (GCH1) is the rate-limiting enzyme of a metabolic pathway synthesizing tetrahydrobiopterin (BH(4)), the cofactor dimerizing and activating inducible nitric oxide synthase (NOS-2). GCH1 protein expression and enzyme activity are minimal in cultured, phenotypically stable, untreated normal adult human astrocytes (NAHA), but are strongly induced, together with NOS-2, by a mixture of three proinflammatory cytokines (IL-1beta, TNF-alpha, and IFN-gamma--the CM-trio) released by microglia under brain-damaging conditions. The resulting hyper-production of NO severely harms neurons. In this study, using MALDI-TOF/MS, PMF, Western immunoblotting (WB), and antibody microarrays we identified several proteins coimmunoprecipitating with GCH1. Under basal conditions, GCH1 was associated with various adaptor/regulator molecules involved in G-protein-coupled receptors signalling, protein serine/threonine phosphatase 2Cbeta (PP2Cbeta), and serine-threonine kinases like Ca(2+) calmodulin kinases (CaMKs), casein kinases (CKs), cAMP-dependent kinases (PKAs), and mitogen-activated protein kinases (MAPKs). Exposure to the three cytokines' mixture (CM-trio) significantly changed, within the 48-72 h required for the induction and activation of GCH1, the levels and identities of some of the 0 h-associated proteins: after 72 h CK-IIalpha tended to dissociate from, whereas MAPK12 and JNK3 were strongly associated with fully active GCH1. These findings provide a first enticing glimpse into the intricate mechanisms regulating GCH1 activation by proinflammatory cytokines in NAHA, and may have therapeutic implications.
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Affiliation(s)
- Anna Chiarini
- Department of Biomedical and Surgical Sciences, Histology and Embryology Unit, University of Verona Medical School, Verona, Italy.
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17
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Bowling KM, Huang Z, Xu D, Ferdousy F, Funderburk CD, Karnik N, Neckameyer W, O'Donnell JM. Direct binding of GTP cyclohydrolase and tyrosine hydroxylase: regulatory interactions between key enzymes in dopamine biosynthesis. J Biol Chem 2008; 283:31449-59. [PMID: 18801743 PMCID: PMC2581565 DOI: 10.1074/jbc.m802552200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2008] [Revised: 07/24/2008] [Indexed: 11/06/2022] Open
Abstract
The signaling functions of dopamine require a finely tuned regulatory network for rapid induction and suppression of output. A key target of regulation is the enzyme tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis, which is activated by phosphorylation and modulated by the availability of its cofactor, tetrahydrobiopterin. The first enzyme in the cofactor synthesis pathway, GTP cyclohydrolase I, is activated by phosphorylation and inhibited by tetrahydrobiopterin. We previously reported that deficits in GTP cyclohydrolase activity in Drosophila heterozygous for mutant alleles of the gene encoding this enzyme led to tightly corresponding diminution of in vivo tyrosine hydroxylase activity that could not be rescued by exogenous cofactor. We also found that the two enzymes could be coimmunoprecipitated from tissue extracts and proposed functional interactions between the enzymes that extended beyond provision of cofactor by one pathway for another. Here, we confirm the physical association of these enzymes, identifying interacting regions in both, and we demonstrate that their association can be regulated by phosphorylation. The functional consequences of the interaction include an increase in GTP cyclohydrolase activity, with concomitant protection from end-product feedback inhibition. In vivo, this effect would in turn provide sufficient cofactor when demand for catecholamine synthesis is greatest. The activity of tyrosine hydroxylase is also increased by this interaction, in excess of the stimulation resulting from phosphorylation alone. Vmax is elevated, with no change in Km. These results demonstrate that these enzymes engage in mutual positive regulation.
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Affiliation(s)
- Kevin M Bowling
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama 35487, USA
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Widder JD, Chen W, Li L, Dikalov S, Thöny B, Hatakeyama K, Harrison DG. Regulation of tetrahydrobiopterin biosynthesis by shear stress. Circ Res 2007; 101:830-8. [PMID: 17704208 DOI: 10.1161/circresaha.107.153809] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
An essential cofactor for the endothelial NO synthase is tetrahydrobiopterin (H4B). In the present study, we show that in human endothelial cells, laminar shear stress dramatically increases H4B levels and enzymatic activity of GTP cyclohydrolase (GTPCH)-1, the first step of H4B biosynthesis. In contrast, protein levels of GTPCH-1 were not affected by shear. Shear did not change protein expression or activity of the downstream enzymes 6-pyruvoyl-tetrahydropterin synthase and sepiapterin reductase and decreased protein levels of the salvage enzyme dihydrofolate reductase. Oscillatory shear only modestly affected H4B levels and GPTCH-1 activity. We also demonstrate that laminar, but not oscillatory shear stress, stimulates phosphorylation of GTPCH-1 on serine 81 and that this is mediated by the alpha prime (alpha') subunit of casein kinase 2. The increase in H4B caused by shear is essential in allowing proper function of endothelial NO synthase because GPTCH-1 blockade with 2,4-diamino-6-hydroxypyrimidine during shear inhibited dimer formation of endothelial NO synthase, increased endothelial cell superoxide production, and prevented the increase in NO production caused by shear. Thus, shear stress not only increases endothelial NO synthase levels but also stimulates production of H4B by markedly enhancing GTPCH-1 activity via casein kinase 2-dependent phosphorylation on serine 81. These findings illustrate a new function of casein kinase 2 in the endothelium and provide insight into regulation of GTPCH-1 activity.
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Affiliation(s)
- Julian D Widder
- Division of Cardiology, Emory University, 101 Woodruff Circle, Atlanta, GA 30322, USA
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20
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Shinozaki K, Nishio Y, Ayajiki K, Yoshida Y, Masada M, Kashiwagi A, Okamura T. Pitavastatin Restores Vascular Dysfunction in Insulin-Resistant State by Inhibiting NAD(P)H Oxidase Activity and Uncoupled Endothelial Nitric Oxide Synthase-Dependent Superoxide Production. J Cardiovasc Pharmacol 2007; 49:122-30. [PMID: 17414223 DOI: 10.1097/fjc.0b013e31802f5895] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
3-Hydroxyl-3-methylglutaryl coenzyme A reductase inhibitors (statins) may benefit the vasculopathy of insulin resistance independent of its lipid-lowering effects. Because imbalance of nitric oxide (NO) and superoxide anion (O(2)(-)) formation may lead to vascular dysfunction, we investigated the effect of statin on vasomotion of insulin-resistant state to clarify the mechanism by which statin ameliorates the impaired function. In the isolated aorta, contraction induced by angiotensin II was more potent in Zucker fatty rats (ZF) compared with that in Zucker lean rats. Both angiotensin II type 1 receptor expression and O(2)(-) production were upregulated in ZF. In addition, deficiency of tetrahydrobiopterin (BH4) contributes to the endothelial dysfunction in ZF. Oral administration of pitavastatin for 8 weeks normalized angiotensin II-induced vasoconstriction and endothelial function in ZF. Pitavastatin treatment of ZF increased vascular BH4 content, which was associated with twofold increase in endothelial NO synthase (eNOS) activity as well as a 60% reduction in endothelial O(2)(-) production. The treatment also markedly downregulated protein expression of angiotensin II type 1 receptor and gp91phox, whereas expression of guanosine triphosphate cyclohydrolase I was upregulated. Pitavastatin restores vascular dysfunction by inhibiting NAD(P)H oxidase activity and uncoupled eNOS-dependent O(2)(-) production.
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Affiliation(s)
- Kazuya Shinozaki
- Department of Pharmacology, Shiga University of Medical Science, Otsu, Shiga, Japan
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21
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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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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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23
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Tegeder I, Costigan M, Griffin RS, Abele A, Belfer I, Schmidt H, Ehnert C, Nejim J, Marian C, Scholz J, Wu T, Allchorne A, Diatchenko L, Binshtok AM, Goldman D, Adolph J, Sama S, Atlas SJ, Carlezon WA, Parsegian A, Lötsch J, Fillingim RB, Maixner W, Geisslinger G, Max MB, Woolf CJ. GTP cyclohydrolase and tetrahydrobiopterin regulate pain sensitivity and persistence. Nat Med 2006; 12:1269-77. [PMID: 17057711 DOI: 10.1038/nm1490] [Citation(s) in RCA: 399] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2006] [Accepted: 09/15/2006] [Indexed: 02/07/2023]
Abstract
We report that GTP cyclohydrolase (GCH1), the rate-limiting enzyme for tetrahydrobiopterin (BH4) synthesis, is a key modulator of peripheral neuropathic and inflammatory pain. BH4 is an essential cofactor for catecholamine, serotonin and nitric oxide production. After axonal injury, concentrations of BH4 rose in primary sensory neurons, owing to upregulation of GCH1. After peripheral inflammation, BH4 also increased in dorsal root ganglia (DRGs), owing to enhanced GCH1 enzyme activity. Inhibiting this de novo BH4 synthesis in rats attenuated neuropathic and inflammatory pain and prevented nerve injury-evoked excess nitric oxide production in the DRG, whereas administering BH4 intrathecally exacerbated pain. In humans, a haplotype of the GCH1 gene (population frequency 15.4%) was significantly associated with less pain following diskectomy for persistent radicular low back pain. Healthy individuals homozygous for this haplotype exhibited reduced experimental pain sensitivity, and forskolin-stimulated immortalized leukocytes from haplotype carriers upregulated GCH1 less than did controls. BH4 is therefore an intrinsic regulator of pain sensitivity and chronicity, and the GTP cyclohydrolase haplotype is a marker for these traits.
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Affiliation(s)
- Irmgard Tegeder
- Neural Plasticity Research Group, Department of Anesthesia and Critical Care, Massachusetts General Hospital & Harvard Medical School, 149 13th Street, Room 4309, Charlestown, Massachusetts 02129, USA
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24
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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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25
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Ren J. Hope or hype: The obsession for tetrahydrobiopterin and GTP cyclohydrolase I (GTPCH I) in cardiovascular medicine. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.jccr.2005.11.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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26
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Shinozaki K, Nishio Y, Yoshida Y, Koya D, Ayajiki K, Masada M, Kashiwagi A, Okamura T. Supplement of tetrahydrobiopterin by a gene transfer of GTP cyclohydrolase I cDNA improves vascular dysfunction in insulin-resistant rats. J Cardiovasc Pharmacol 2005; 46:505-12. [PMID: 16160605 DOI: 10.1097/01.fjc.0000177981.91434.ba] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Deficiency of tetrahydrobiopterin (BH4) in the vascular tissue contributes to endothelial dysfunction in the insulin-resistant state. We intended to develop a new gene transfer method by overexpression of its biosynthetic enzyme, GTP cyclohydrolase I (GTP-CH1). The GTP-CH1 cDNA was inserted into a pCAGGS vector, and then plasmid DNA was mixed with atelocollagen, and the aliquot was injected into thigh muscles of insulin-resistant Zucker fatty rats. After 4 weeks, pteridine derivative levels, superoxide anion (O2-), activity of endothelial nitric oxide synthase (eNOS), and endothelium-dependent relaxation were evaluated in the aortas obtained from Zucker lean or fatty rats. The BH4 contents and GTP-CH1 activity in Zucker fatty rats were 50%-55% less than those of Zucker lean rats. However, those impairments were significantly improved by a plasmid DNA injection, and aortic BH4 content reached more than 80% of the level of Zucker lean rats. Increased A23187-stimulated O2- production as well as decreased eNOS activity and endothelial function in insulin-resistant Zucker fatty rats were improved by a plasmid DNA injection to a level similar to that in Zucker lean rats. These findings suggest that intramuscular GTP-CH1 gene transfer using atelocollagen serves as a useful method of long-term systemic delivery of BH4 and the treatment of endothelial dysfunction.
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Affiliation(s)
- Kazuya Shinozaki
- Department of Pharmacology, Shiga University of Medical Science, Otsu, Japan
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Shimizu S, Ishii M, Miyasaka Y, Wajima T, Negoro T, Hagiwara T, Kiuchi Y. Possible involvement of hydroxyl radical on the stimulation of tetrahydrobiopterin synthesis by hydrogen peroxide and peroxynitrite in vascular endothelial cells. Int J Biochem Cell Biol 2005; 37:864-75. [PMID: 15694845 DOI: 10.1016/j.biocel.2004.11.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2004] [Revised: 10/22/2004] [Accepted: 11/08/2004] [Indexed: 11/20/2022]
Abstract
We recently described that hydrogen peroxide (H2O2) stimulates the synthesis of tetrahydrobiopterin (BH4) through the induction of the rate-limiting enzyme GTP-cyclohydrolase I (GTPCH), and increases tetrahydrobiopterin content in vascular endothelial cells. Tetrahydrobiopterin is easily oxidized by peroxynitrite (ONOO-), but not by hydrogen peroxide. The aim of this study was to determine the effect of hydroxyl radical and peroxynitrite, which are both toxic biological oxidants, on tetrahydrobiopterin synthesis and the regulation of its content in vascular endothelial cells. In the cell-free assay system, tetrahydrobiopterin was rapidly oxidized by the hydroxyl radical and peroxynitrite, but not by hydrogen peroxide. However, the addition of not only hydrogen peroxide but also the hydroxyl radical and peroxynitrite to vascular endothelial cells transiently decreased tetrahydrobiopterin content, and then markedly increased its content. Interestingly, total biopterin content was also decreased by early treatment with oxidants. Moreover, oxidants induced the expression of GTP-cyclohydrolase I, and the increase of the tetrahydrobiopterin content was blocked by the treatment with GTP-cyclohydrolase I inhibitor. Both the hydrogen peroxide- and peroxynitrite-induced increases in tetrahydrobiopterin content and findings suggest that not only hydrogen peroxide but also the hydroxyl radical and peroxynitrite stimulates tetrahydrobiopterin synthesis through GTP-cyclohydrolase I expression, and that the hydroxyl radical plays a central role in the stimulation of tetrahydrobiopterin synthesis. Moreover, the transient decrease in BH4 to tetrahydrobiopterin.
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Affiliation(s)
- Shunichi Shimizu
- Department of Pathophysiology, School of Pharmaceutical Sciences, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan.
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28
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Zhang YQ, Friedman DB, Wang Z, Woodruff E, Pan L, O'donnell J, Broadie K. Protein Expression Profiling of the Fragile X Mutant Brain Reveals Up-regulation of Monoamine Synthesis. Mol Cell Proteomics 2005; 4:278-90. [PMID: 15634690 DOI: 10.1074/mcp.m400174-mcp200] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fragile X syndrome is the most common form of inherited mental retardation, associated with both cognitive and behavioral anomalies. The disease is caused by silencing of the fragile X mental retardation 1 (fmr1) gene, which encodes the mRNA-binding, translational regulator FMRP. Previously we established a disease model through mutation of Drosophila fmr1 (dfmr1) and showed that loss of dFMRP causes defects in neuronal structure, function, and behavioral output similar to the human disease state. To uncover molecular targets of dFMRP in the brain, we use here a proteomic approach involving two-dimensional difference gel electrophoresis analyses followed by mass spectrometry identification of proteins with significantly altered expression in dfmr1 null mutants. We then focus on two misregulated enzymes, phenylalanine hydroxylase (Henna) and GTP cyclohydrolase (Punch), both of which mediate in concert the synthetic pathways of two key monoamine neuromodulators, dopamine and serotonin. Brain enzymatic assays show a nearly 2-fold elevation of Punch activity in dfmr1 null mutants. Consistently brain neurochemical assays show that both dopamine and serotonin are significantly increased in dfmr1 null mutants. At a cellular level, dfmr1 null mutant neurons display a highly significant elevation of the dense core vesicles that package these monoamine neuromodulators for secretion. Taken together, these data indicate that dFMRP normally down-regulates the monoamine pathway, which is consequently up-regulated in the mutant condition. Elevated brain levels of dopamine and serotonin provide a plausible mechanistic explanation for aspects of cognitive and behavioral deficits in human patients.
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Affiliation(s)
- Yong Q Zhang
- Department of Biological Science, Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, Tennessee 37232-1634, USA
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29
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Peterson TE, Katusic ZS. Transcribing the cross-talk of cytokine-induced tetrahydrobiopterin synthesis in endothelial cells. Circ Res 2005; 96:141-3. [PMID: 15692091 DOI: 10.1161/01.res.0000156078.12390.44] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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30
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Gilchrist M, Hesslinger C, Befus AD. Tetrahydrobiopterin, a critical factor in the production and role of nitric oxide in mast cells. J Biol Chem 2003; 278:50607-14. [PMID: 14514683 DOI: 10.1074/jbc.m307777200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Mast cells (MC) are biologically potent, ubiquitously distributed immune cells with fundamental roles in host integrity and disease. MC diversity and function is regulated by exogenous nitric oxide; however, the production and function of endogenously produced NO in MC is enigmatic. We used rat peritoneal MC (PMC) as an in vivo model to examine intracellular NO production. Live cell confocal analysis of PMC using the NO-sensitive probe diaminofluorescein showed distinct patterns of intracellular NO formation with either antigen (Ag)/IgE (short term) or interferon-gamma (IFN-gamma) (long term). Ag/IgE-induced NO production is preceded by increased intracellular Ca2+, implying constitutive nitric-oxide synthase (NOS) activity. NO formation inhibits MC degranulation. NOS has obligate requirements for tetrahydrobiopterin (BH4), a product of GTP-cyclohydrolase I (CHI), IFN-gamma-stimulated PMC increased CHI mRNA, protein, and enzymatic activity, while decreasing CHI feedback regulatory protein mRNA, causing sustained NO production. Treatment with the CHI inhibitor, 2,4-diamino-6-hydroxypyrimidine, inhibited NO in both IFN-gamma and Ag/IgE systems, increasing MC degranulation. Reconstitution with the exogenous BH4 substrate, sepiapterin, restored NO formation and inhibited exocytosis. Thus, Ag/IgE and IFN-gamma induced intracellular NO plays a key role in MC mediator release, and alterations in NOS activity via BH4 availability may be critical to the heterogeneous responsiveness of MC.
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Affiliation(s)
- Mark Gilchrist
- Glaxo-Heritage Asthma Research Laboratory, Pulmonary Research Group, Department of Medicine, University of Alberta, Edmonton, Alberta T6G 2S2, Canada.
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He A, Rosazza JPN. GTP cyclohydrolase I: purification, characterization, and effects of inhibition on nitric oxide synthase in nocardia species. Appl Environ Microbiol 2003; 69:7507-13. [PMID: 14660404 PMCID: PMC309945 DOI: 10.1128/aem.69.12.7507-7513.2003] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2003] [Accepted: 09/04/2003] [Indexed: 11/20/2022] Open
Abstract
GTP cyclohydrolase I (GTPCH) catalyzes the first step in pteridine biosynthesis in Nocardia sp. strain NRRL 5646. This enzyme is important in the biosynthesis of tetrahydrobiopterin (BH4), a reducing cofactor required for nitric oxide synthase (NOS) and other enzyme systems in this organism. GTPCH was purified more than 5,000-fold to apparent homogeneity by a combination of ammonium sulfate fractionation, GTP-agarose, DEAE Sepharose, and Ultragel AcA 34 chromatography. The purified enzyme gave a single band for a protein estimated to be 32 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The molecular mass of the native enzyme was estimated to be 253 kDa by gel filtration, indicating that the active enzyme is a homo-octamer. The enzyme follows Michaelis-Menten kinetics, with a Km for GTP of 6.5 micromoles. Nocardia GTPCH possessed a unique N-terminal amino acid sequence. The pH and temperature optima for the enzyme were 7.8 and 56 degrees C, respectively. The enzyme was heat stable and slightly activated by potassium ion but was inhibited by calcium, copper, zinc, and mercury, but not magnesium. BH4 inhibited enzyme activity by 25% at a concentration of 100 micromoles. 2,4-Diamino-6-hydroxypyrimidine (DAHP) appeared to competitively inhibit the enzyme, with a Ki of 0.23 mM. With Nocardia cultures, DAHP decreased medium levels of NO2- plus NO3-. Results suggest that in Nocardia cells, NOS synthesis of nitric oxide is indirectly decreased by reducing the biosynthesis of an essential reducing cofactor, BH4.
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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, Iowa 52242, USA
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Shiraishi H, Kato T, Atsuta K, Sumi-Ichinose C, Ohtsuki M, Itoh M, Hishida H, Tada S, Udagawa Y, Nagatsu T, Hagino Y, Ichinose H, Nomura T. cGMP inhibits GTP cyclohydrolase I activity and biosynthesis of tetrahydrobiopterin in human umbilical vein endothelial cells. J Pharmacol Sci 2003; 93:265-71. [PMID: 14646243 DOI: 10.1254/jphs.93.265] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Tetrahydrobiopterin (BH4) acts as an essential cofactor for the enzymatic activity of nitric oxide (NO) synthases. Biosynthesis of the cofactor BH4 starts from GTP and requires 3 enzymatic steps, which include GTP cyclohydrolase I (GCH I) catalysis of the first and rate-limiting step. In this study we examined the effects of cGMP on GCH I activity in human umbilical vein endothelial cells under inflammatory conditions. Exogenous application of the cGMP analogue 8-bromo-cGMP markedly inhibited GCH I activity in the short term, whereas an cAMP analogue had no effect on GCH I activity under the same condition. NO donors, NOR3 and sodium nitroprusside, elevated the intracellular cGMP level and reduced GCH I activity in the short term. This inhibition of GCH I activity was obliterated in the presence of an NO trapper carboxy-PTIO. NO donors had no effect on GCH I mRNA expression in the short term. Moreover, cycloheximide did not alter the inhibition by NO donors of GCH I activity. These findings suggest that stimulation of the cGMP signaling cascade down-regulates GCH I activity through post translational modification of the GCH I enzyme.
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Affiliation(s)
- Hiroaki Shiraishi
- Department of Pharmacology, School of Medicine, Fujita Health University, Toyoake, Aichi, Japan
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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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Madsen JT, Jansen P, Hesslinger C, Meyer M, Zimmer J, Gramsbergen JB. Tetrahydrobiopterin precursor sepiapterin provides protection against neurotoxicity of 1-methyl-4-phenylpyridinium in nigral slice cultures. J Neurochem 2003; 85:214-23. [PMID: 12641743 DOI: 10.1046/j.1471-4159.2003.01666.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Complex-I inhibition and oxidative processes have been implicated in the loss of nigral dopamine neurones in Parkinson's disease and the toxicity of MPTP and its metabolite MPP+. Tetrahydrobiopterin, an essential cofactor for tyrosine hydroxylase, may act as an antioxidant in dopaminergic neurones and protects against the toxic consequences of glutathione depletion. Here we studied the effects of manipulating tetrahydrobiopterin levels on MPP+ toxicity in organotypic, rat ventral mesencephalic slice cultures. In cultures exposed to 30 micro m MPP+ for 2 days, followed by 8 days 'recovery' in control medium, we measured dopamine and its metabolites in the tissue and culture medium by HPLC, lactate dehydrogenase release to the culture medium, cellular uptake of propidium iodide and counted the tyrosine hydroxylase-immunoreactive neurones. Inhibition of tetrahydrobiopterin synthesis by 2,4-diamino-6-hydroxypyrimidine had no significant synergistic effect on MPP+ toxicity. In contrast, the tetrahydrobiopterin precursor l-sepiapterin attenuated the MPP+-induced dopamine depletion and loss of tyrosine hydroxylase-positive cells in a dose-dependent manner with 40 micro m l-sepiapterin providing maximal protection. Accordingly, increasing intracellular tetrahydrobiopterin levels may protect against oxidative stress by complex-I inhibition.
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Affiliation(s)
- Jakob Torp Madsen
- Anatomy and Neurobiology, Institute of Medical Biology, University of Southern Denmark, Odense, Denmark
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35
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Abstract
A model for the possible involvement of Protein Kinase C (PKC) in the pathogenesis of inborn errors of metabolism has been proposed. According to this model, perturbation of PKC activity by the accumulation of naturally occurring compounds serves as a unifying functional link between genotype and phenotype. Recent reports regarding an increasing number of modulating metabolites, specific PKC-subtypes activities, their effect on transcription factors and gene expression in various diseases and additional PKC-substrates expand the model. A re-examination of the proposed model in view of these reports and, vice versa, a review of these reports in the context of the proposed model reveal some common phenotypic outcomes in inborn errors of fatty acid-, cholesterol- and homocystine-metabolism as well as lysosomal and peroxisomal diseases.
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Affiliation(s)
- Avihu Boneh
- Metabolic Service, Genetic Health Services, Victoria, Australia.
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36
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Bauer M, Suppmann S, Meyer M, Hesslinger C, Gasser T, Widmer HR, Ueffing M. Glial cell line-derived neurotrophic factor up-regulates GTP-cyclohydrolase I activity and tetrahydrobiopterin levels in primary dopaminergic neurones. J Neurochem 2002; 82:1300-10. [PMID: 12358777 DOI: 10.1046/j.1471-4159.2002.01074.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Glial cell line-derived neurotrophic factor (GDNF) protects dopaminergic neurones against toxic and physical damage. In addition, GDNF promotes differentiation and structural integrity of dopaminergic neurones. Here we show that GDNF can support the function of primary dopaminergic neurones by triggering activation of GTP-cyclohydrolase I (GTPCH I), a key enzyme in catecholamine biosynthesis. GDNF stimulation of primary dopaminergic neurones expressing both tyrosine 3-monooxygenase and GTPCH I resulted in a dose-dependent doubling of GTPCH I activity, and a concomitant increase in tetrahydrobiopterin levels whereas tyrosine 3-monooxygenase activity was not altered. Actinomycin D, asan inhibitor of de novo biosynthesis, abolished any GDNF-mediated up-regulation of GTPCH I activity. However, GTPCH I mRNA levels in primary dopaminergic neurones were not altered by GDNF treatment, suggesting that the mode of action for that up-regulation is not directly connected to the regulation of GTPCH I transcription. We conclude that GDNF, in addition to its action in structural differentiation, also promotes differentiation regarding expression and enzymatic activity of a crucial component in the dopaminergic biosynthetic pathway.
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Affiliation(s)
- M Bauer
- Department of Neurology, Klinikum Grosshadern, LMU München, Germany
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37
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Ohtsuki M, Shiraishi H, Kato T, Kuroda R, Tazawa M, Sumi-Ichinose C, Tada S, Udagawa Y, Itoh M, Hishida H, Ichinose H, Nagatsu T, Hagino Y, Nomura T. cAMP inhibits cytokine-induced biosynthesis of tetrahydrobiopterin in human umbilical vein endothelial cells. Life Sci 2002; 70:2187-98. [PMID: 12002810 DOI: 10.1016/s0024-3205(02)01503-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
We studied the effects of cAMP on cytokine (interferon-gamma plus tumor necrosis factor-alpha)-induced stimulation of tetrahydrobiopterin (BH4) synthesis in human umbilical vein endothelial cells (HUVEC). The cytokine mixture caused a marked increase in the biosynthesis and release of BH4 by HUVEC. Dibutyryl-cAMP produced a dose-dependent inhibition of this cytokine-induced stimulation of synthesis and release of BH4 by these cells. 8-Bromo-cAMP also caused a significant inhibition, although the effects were less marked than those of dibutyryl-cAMP. Both forskolin and the stable analog of prostacyclin, iloprost, caused cAMP accumulation and a concomitant diminution of the cytokine-induced BH4 synthesis in HUVEC. Dibutyryl-cAMP and iloprost also significantly inhibited the cytokine-induced stimulation of GTP cyclohydrolase I (GCHI) activity and mRNA production. We concluded that the suppression by the cAMP messenger system of cytokine-induced stimulation of synthesis and release of BH4 by HUVEC can be attributed to the inhibition of the activity of GCHI, the rate-limiting enzyme in BH4 biosynthetic pathway, in HUVEC. The data also suggest that the cAMP-mediated reduction in the GCHI mRNA level may at least partially explain the decline in GCHI activity. It is reasoned that under inflammatory conditions, cAMP-elevating agents such as prostacyclin exert regulatory effects on circulation by inhibiting cytokine-induced synthesis and release of BH4 by HUVEC.
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Affiliation(s)
- Masatsugu Ohtsuki
- Department of Internal Medicine, Fujita Health University School of Medicine, Toyoake, Aichi, Japan
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38
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Fujimoto K, Takahashi SY, Katoh S. Mutational analysis of sites in sepiapterin reductase phosphorylated by Ca2+/calmodulin-dependent protein kinase II. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1594:191-8. [PMID: 11825621 DOI: 10.1016/s0167-4838(01)00300-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Sepiapterin reductase (SPR) catalyzes the last step in the pathway of tetrahydrobiopterin biosynthesis in tissues. SPR is phosphorylated by Ca2+-dependent protein kinases, which indicates that Ca2+-activated protein kinases may play a role in the regulation of SPR in vivo. Phosphorylation sites of rat sepiapterin reductase (rSPR) by Ca2+/calmodulin-dependent protein kinase II were determined in the present study. Using specific monoclonal anti-phospho-Ser and -Thr antibodies, we found that only Ser residues of rSPR were phosphorylated. We constructed several point mutants of SPR by systematically replacing the three Ser residues by Ala ones. These mutants showed that all three Ser residues, i.e. S46, S196, and S214, of rSPR were phosphorylated. We also recognized that only Ser-213 of human SPR was phosphorylated. Each of these serine residues in SPR was found in the consensus sequence (Arg-X-X-Ser/Thr) of the phosphorylation site.
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Affiliation(s)
- Kengo Fujimoto
- Department of Biochemistry, Meikai University School of Dentistry, Sakado, Saitama 350-0283, Japan.
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39
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Forsythe P, Gilchrist M, Kulka M, Befus AD. Mast cells and nitric oxide: control of production, mechanisms of response. Int Immunopharmacol 2001; 1:1525-41. [PMID: 11515817 DOI: 10.1016/s1567-5769(01)00096-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Mast cells are involved in numerous activities ranging from control of the vasculature, to tissue injury and repair, allergic inflammation and host defences. They synthesize and secrete a variety of mediators, activating and modulating the functions of nearby cells and initiating complex physiological changes. Interestingly, NO produced by mast cells and/or other cells in the microenvironment appears to regulate these diverse roles. This review outlines some of the pathways central to the production of NO by mast cells and identifies many of the tightly controlled regulatory mechanisms involved. Several cofactors and regulatory elements are involved in NO production, and these act at transcriptional and post-translational sites. Their involvement in NO production will be outlined and the possibility that these pathways are critically important in mast cell functions will be discussed. The effects of NO on mast cell functions such as adhesion, activation and mediator secretion will be examined with a focus on molecular mechanisms by which NO modifies intracellular signalling pathways dependent or independent of cGMP and soluble guanylate cyclase. The possibility that NO regulates mast cell function through effects on selected ion channels will be discussed. Metabolic products of NO including peroxynitrite and other reactive species may be the critical elements that affect the actions of NO on mast cell functions. Further understanding of the actions of NO on mast cell activities may uncover novel strategies to modulate inflammatory conditions.
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Affiliation(s)
- P Forsythe
- 574 Heritage Medical Research Center, University of Alberta, Edmonton, Canada
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40
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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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Ziegler I, McDonald T, Hesslinger C, Pelletier I, Boyle P, McDonaldo T. Development of the pteridine pathway in the zebrafish, Danio rerio. J Biol Chem 2000; 275:18926-32. [PMID: 10770954 DOI: 10.1074/jbc.m910307199] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the zebrafish, the peripheral neurons and the pigment cells are derived from the neural crest and share the pteridine pathway, which leads either to the cofactor tetrahydrobiopterin or to xanthophore pigments. The components of the pteridine pattern were identified as tetrahydrobiopterin, sepiapterin, 7-oxobiopterin, isoxanthopterin, and 2,4,7-trioxopteridine. The expression of GTP cyclohydrolase I activity during the first 24-h postfertilization, followed by 6-pyruvoyl-5,6,7,8-tetrahydropterin synthase and sepiapterin reductase, suggest an early supply of tetrahydrobiopterin for neurotransmitter synthesis in the neurons and for tyrosine supply in the melanophores. At 48-h postfertilization, sepiapterin formation branches off the de novo pathway of tetrahydrobiopterin synthesis. Sepiapterin, via 7,8-dihydrobiopterin and biopterin, serves as a precursor for the formation of 7-oxobiopterin, which may be further catabolized to isoxanthopterin and 2,4,7-trioxopteridine. Neither 7, 8-dihydrobiopterin nor biopterin is a substrate for xanthine oxidoreductase. In contrast, both of these compounds are oxidized at C-7 by a xanthine oxidase variant form, which is inactivated by KCN, but is insensitive to allopurinol. The oxidase and the dehydrogenase form of xanthine oxidoreductase as well as the xanthine oxidase variant have specific developmental patterns. It follows that GTP cyclohydrolase I, the formation of sepiapterin, and the xanthine oxidoreductase family control the pteridine pathway in the zebrafish.
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Affiliation(s)
- I Ziegler
- GSF Research Center, Institut für Klinische Molekularbiologie und Tumorgenetik, 81377 München, Germany.
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Suzuki T, Ohye T, Inagaki H, Nagatsu T, Ichinose H. Characterization of wild-type and mutants of recombinant human GTP cyclohydrolase I: relationship to etiology of dopa-responsive dystonia. J Neurochem 1999; 73:2510-6. [PMID: 10582612 DOI: 10.1046/j.1471-4159.1999.0732510.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
To explore the molecular etiology of two disorders caused by a defect in GTP cyclohydrolase I--hereditary progressive dystonia with marked diurnal fluctuation (HPD), also known as dopa-responsive dystonia (DRD), and autosomal recessive GTP cyclohydrolase I deficiency--we purified and analyzed recombinant human wild-type and mutant GTP cyclohydrolase I proteins expressed in Escherichia coli. Mutant proteins showed very low enzyme activities, and some mutants were eluted at a delayed volume on gel filtration compared with the recombinant wild-type. Next, we examined the GTP cyclohydrolase I protein amount by western blot analysis in phytohemagglutinin-stimulated mononuclear blood cells from HPD/DRD patients. We found a great reduction in the amount of the enzyme protein not only in one patient who had a frameshift mutation, but also in an HPD/DRD patient who had a missense mutation. These results suggest that a dominant-negative effect of chimeric protein composed of wild-type and mutant subunits is unlikely as a cause of the reduced enzyme activity in HPD/DRD patients. We suggest that reduction of the amount of the enzyme protein, which is independent of the mutation type, could be a reason for the dominant inheritance in HPD/DRD.
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Affiliation(s)
- T Suzuki
- Division of Molecular Genetics, Institute for Comprehensive Medical Science, Fujita Health University, Aichi, Japan
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43
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Scherer-Oppliger T, Leimbacher W, Blau N, Thöny B. Serine 19 of human 6-pyruvoyltetrahydropterin synthase is phosphorylated by cGMP protein kinase II. J Biol Chem 1999; 274:31341-8. [PMID: 10531334 DOI: 10.1074/jbc.274.44.31341] [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: 11/06/2022] Open
Abstract
6-Pyruvoyltetrahydropterin synthase (PTPS) participates in tetrahydrobiopterin cofactor biosynthesis. We previously identified in a PTPS-deficient patient an inactive PTPS allele with an Arg(16) to Cys codon mutation. Arg(16) is located in the protein surface exposed phosphorylation motif Arg(16)-Arg-Ile-Ser, with Ser(19) as the putative phosphorylation site for serine-threonine protein kinases. Purification of recombinant PTPS-S19A from bacterial cells resulted in an active enzyme (k(cat)/K(m) = 6.4 x 10(3) M(-1) s(-1)), which was similar to wild-type PTPS (k(cat)/K(m) = 4.1 x 10(3) M(-1) s(-1)). In assays with purified enzymes, wild-type but not PTPS-S19A was a specific substrate for the cGMP-dependent protein kinase (cGK) type I and II. Upon expression in COS-1 cells, PTPS-S19A was stable but not phosphorylated and had a reduced activity of approximately 33% in comparison to wild-type PTPS. Extracts from several human cell lines, including brain, contained a kinase that bound to and phosphorylated immobilized wild-type, but not mutant PTPS. Addition of cGMP stimulated phosphotransferase activity 2-fold. Extracts from transfected COS-1 cells overexpressing cGKII stimulated Ser(19) phosphorylation more than 100-fold, but only 4-fold from cGKI overexpressing cells. Moreover, fibroblast extracts from mice lacking cGKII exhibited significantly reduced phosphorylation of PTPS. These results suggest that Ser(19) of human PTPS may be a substrate for cGKII phosphorylation also in vivo, a modification that is essential for normal activity.
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Affiliation(s)
- T Scherer-Oppliger
- Department of Pediatrics, Division of Clinical Chemistry and Biochemistry, University of Zürich, Steinwiesstrasse 75, CH-8032 Zürich, Switzerland
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44
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Stathakis DG, Burton DY, McIvor WE, Krishnakumar S, Wright TR, O'Donnell JM. The catecholamines up (Catsup) protein of Drosophila melanogaster functions as a negative regulator of tyrosine hydroxylase activity. Genetics 1999; 153:361-82. [PMID: 10471719 PMCID: PMC1460756 DOI: 10.1093/genetics/153.1.361] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
We report the genetic, phenotypic, and biochemical analyses of Catecholamines up (Catsup), a gene that encodes a negative regulator of tyrosine hydroxylase (TH) activity. Mutations within this locus are semidominant lethals of variable penetrance that result in three broad, overlapping effective lethal phases (ELPs), indicating that the Catsup gene product is essential throughout development. Mutants from each ELP exhibit either cuticle defects or catecholamine-related abnormalities, such as melanotic salivary glands or pseudotumors. Additionally, Catsup mutants have significantly elevated TH activity that may arise from a post-translational modification of the enzyme. The hyperactivation of TH in Catsup mutants results in abnormally high levels of catecholamines, which can account for the lethality, visible phenotypes, and female sterility observed in these mutants. We propose that Catsup is a component of a novel system that downregulates TH activity, making Catsup the fourth locus found within the Dopa decarboxylase (Ddc) gene cluster that functions in catecholamine metabolism.
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Affiliation(s)
- D G Stathakis
- Department of Biology, University of Virginia, Charlottesville, Virginia 22903-2477, USA.
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