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Jiang X, Shao Y, Liao Y, Zheng X, Peng M, Cai Y, Wang M, Liu H, Zeng C, Lin Y, Zhang W, Liu L. Mechanisms underlying the efficacy and limitation of dopa and tetrahydrobiopterin therapies for the deficiency of GTP cyclohydrolase 1 revealed in a novel mouse model. Eur J Pharmacol 2024; 967:176379. [PMID: 38342361 DOI: 10.1016/j.ejphar.2024.176379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2023] [Revised: 01/31/2024] [Accepted: 01/31/2024] [Indexed: 02/13/2024]
Abstract
Dopa and tetrahydrobiopterin (BH4) supplementation are recommended therapies for the dopa-responsive dystonia caused by GTP cyclohydrolase 1 (GCH1, also known as GTPCH) deficits. However, the efficacy and mechanisms of these therapies have not been intensively studied yet. In this study, we tested the efficacy of dopa and BH4 therapies by using a novel GTPCH deficiency mouse model, Gch1KI/KI, which manifested infancy-onset motor deficits and growth retardation similar to the patients. First, dopa supplementation supported Gch1KI/KI mouse survival to adulthood, but residual motor deficits and dwarfism remained. Interestingly, RNAseq analysis indicated that while the genes participating in BH4 biosynthesis and regeneration were significantly increased in the liver, no significant changes were observed in the brain. Second, BH4 supplementation alone restored the growth of Gch1KI/KI pups only in early postnatal developmental stage. High doses of BH4 supplementation indeed restored the total brain BH4 levels, but brain dopamine deficiency remained. While total brain TH levels were relatively increased in the BH4 treated Gch1KI/KI mice, the TH in the striatum were still almost undetectable, suggesting differential BH4 requirements among brain regions. Last, the growth of Gch1KI/KI mice under combined therapy outperformed dopa or BH4 therapy alone. Notably, dopamine was abnormally high in more than half, but not all, of the treated Gch1KI/KI mice, suggesting the existence of variable synergetic effects of dopa and BH4 supplementation. Our results provide not only experimental evidence but also novel mechanistic insights into the efficacy and limitations of dopa and BH4 therapies for GTPCH deficiency.
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Affiliation(s)
- Xiaoling Jiang
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, 510623, China
| | - Yongxian Shao
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, 510623, China
| | - Yongqiang Liao
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, 510623, China
| | - Xiaoning Zheng
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, 510623, China
| | - Minzhi Peng
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, 510623, China
| | - Yanna Cai
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, 510623, China
| | - Meiyi Wang
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, 510623, China
| | - Huazhen Liu
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, 510623, China
| | - Chunhua Zeng
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, 510623, China
| | - Yunting Lin
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, 510623, China.
| | - Wen Zhang
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, 510623, China.
| | - Li Liu
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong, 510623, China.
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Lackner K, Ebner S, Watschinger K, Maglione M. Multiple Shades of Gray-Macrophages in Acute Allograft Rejection. Int J Mol Sci 2023; 24:ijms24098257. [PMID: 37175964 PMCID: PMC10179242 DOI: 10.3390/ijms24098257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Revised: 04/27/2023] [Accepted: 05/01/2023] [Indexed: 05/15/2023] Open
Abstract
Long-term results following solid organ transplantation do not mirror the excellent short-term results achieved in recent decades. It is therefore clear that current immunosuppressive maintenance protocols primarily addressing the adaptive immune system no longer meet the required clinical need. Identification of novel targets addressing this shortcoming is urgently needed. There is a growing interest in better understanding the role of the innate immune system in this context. In this review, we focus on macrophages, which are known to prominently infiltrate allografts and, during allograft rejection, to be involved in the surge of the adaptive immune response by expression of pro-inflammatory cytokines and direct cytotoxicity. However, this active participation is janus-faced and unspecific targeting of macrophages may not consider the different subtypes involved. Under this premise, we give an overview on macrophages, including their origins, plasticity, and important markers. We then briefly describe their role in acute allograft rejection, which ranges from sustaining injury to promoting tolerance, as well as the impact of maintenance immunosuppressants on macrophages. Finally, we discuss the observed immunosuppressive role of the vitamin-like compound tetrahydrobiopterin and the recent findings that suggest the innate immune system, particularly macrophages, as its target.
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Affiliation(s)
- Katharina Lackner
- Daniel Swarovski Research Laboratory, Department of Visceral, Transplant and Thoracic Surgery, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Susanne Ebner
- Daniel Swarovski Research Laboratory, Department of Visceral, Transplant and Thoracic Surgery, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Katrin Watschinger
- Institute of Biological Chemistry, Biocenter, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Manuel Maglione
- Daniel Swarovski Research Laboratory, Department of Visceral, Transplant and Thoracic Surgery, Medical University of Innsbruck, 6020 Innsbruck, Austria
- Department of Visceral, Transplant, and Thoracic Surgery, Medical University of Innsbruck, 6020 Innsbruck, Austria
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John RV, Devasia T, N M, Lukose J, Chidangil S. Micro-Raman spectroscopy study of blood samples from myocardial infarction patients. Lasers Med Sci 2022; 37:3451-3460. [PMID: 35821543 DOI: 10.1007/s10103-022-03604-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 06/28/2022] [Indexed: 12/15/2022]
Abstract
Acute myocardial infarction (MI) is found to be a major causative factor for global mortality and morbidity. This situation demands necessity of developing efficient and rapid diagnostic tools to detect acute MI. Raman spectroscopy is a non-destructive optical diagnostic technique, which has high potential in probing biochemical changes in clinical samples during initiation and progress of diseases. In this work, blood was taken as the sample to examine inflammation in acute MI patients using Raman spectroscopy. Ratio of Raman peak intensities that corresponds to phenylalanine (1000 cm-1) and tyrosine (825 cm-1) can facilitate indirect information about tetrahydrobiopterin (BH4) availability, which can indicate inflammatory status in patients. This ratio obtained was higher for MI patients in comparison with control subjects. The decrease in phenylalanine and tyrosine ratio (Phe-Tyr ratio) is attributed to the prognosis of standard of care (medications like antiplatelets including aspirin, statin and revascularisation) leading to inflammation reduction. Phe-Tyr ratio estimated from the Raman spectra of blood can be exploited as a reliable method to probe inflammation due to MI. The method is highly objective, require only microliters of sample and minimal sample preparation, signifying its clinical utility.
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Affiliation(s)
- Reena V John
- Centre of Excellence for Biophotonics, Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Tom Devasia
- Department of Cardiology, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Mithun N
- Centre of Excellence for Biophotonics, Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Jijo Lukose
- Centre of Excellence for Biophotonics, Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Santhosh Chidangil
- Centre of Excellence for Biophotonics, Department of Atomic and Molecular Physics, Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India.
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Trongtrakul K, Thonusin C, Pothirat C, Chattipakorn SC, Chattipakorn N. Past Experiences for Future Applications of Metabolomics in Critically Ill Patients with Sepsis and Septic Shocks. Metabolites 2021; 12:metabo12010001. [PMID: 35050123 PMCID: PMC8779293 DOI: 10.3390/metabo12010001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 12/16/2021] [Accepted: 12/18/2021] [Indexed: 12/17/2022] Open
Abstract
A disruption of several metabolic pathways in critically ill patients with sepsis indicates that metabolomics might be used as a more precise tool for sepsis and septic shock when compared with the conventional biomarkers. This article provides information regarding metabolomics studies in sepsis and septic shock patients. It has been shown that a variety of metabolomic pathways are altered in sepsis and septic shock, including amino acid metabolism, fatty acid oxidation, phospholipid metabolism, glycolysis, and tricarboxylic acid cycle. Based upon this comprehensive review, here, we demonstrate that metabolomics is about to change the world of sepsis biomarkers, not only for its utilization in sepsis diagnosis, but also for prognosticating and monitoring the therapeutic response. Additionally, the future direction regarding the establishment of studies integrating metabolomics with other molecular modalities and studies identifying the relationships between metabolomic profiles and clinical characteristics to address clinical application are discussed in this article. All of the information from this review indicates the important impact of metabolomics as a tool for diagnosis, monitoring therapeutic response, and prognostic assessment of sepsis and septic shock. These findings also encourage further clinical investigations to warrant its use in routine clinical settings.
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Affiliation(s)
- Konlawij Trongtrakul
- Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand; (K.T.); (C.P.)
| | - Chanisa Thonusin
- Metabolomics Unit, Cardiac Electrophysiology Research and Training Center, Chiang Mai University, Chiang Mai 50200, Thailand;
- Center of Excellence in Cardiac Electrophysiology Research, Chiang Mai University, Chiang Mai 50200, Thailand
- Cardiac Electrophysiology Unit, Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
- Correspondence: (C.T.); (N.C.)
| | - Chaicharn Pothirat
- Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand; (K.T.); (C.P.)
| | - Siriporn C. Chattipakorn
- Metabolomics Unit, Cardiac Electrophysiology Research and Training Center, Chiang Mai University, Chiang Mai 50200, Thailand;
- Center of Excellence in Cardiac Electrophysiology Research, Chiang Mai University, Chiang Mai 50200, Thailand
- Department of Oral Biology and Diagnostic Sciences, Faculty of Dentistry, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Nipon Chattipakorn
- Metabolomics Unit, Cardiac Electrophysiology Research and Training Center, Chiang Mai University, Chiang Mai 50200, Thailand;
- Center of Excellence in Cardiac Electrophysiology Research, Chiang Mai University, Chiang Mai 50200, Thailand
- Cardiac Electrophysiology Unit, Department of Physiology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
- Correspondence: (C.T.); (N.C.)
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Fanet H, Capuron L, Castanon N, Calon F, Vancassel S. Tetrahydrobioterin (BH4) Pathway: From Metabolism to Neuropsychiatry. Curr Neuropharmacol 2021; 19:591-609. [PMID: 32744952 PMCID: PMC8573752 DOI: 10.2174/1570159x18666200729103529] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/03/2020] [Accepted: 07/23/2020] [Indexed: 11/22/2022] Open
Abstract
Tetrahydrobipterin (BH4) is a pivotal enzymatic cofactor required for the synthesis of serotonin, dopamine and nitric oxide. BH4 is essential for numerous physiological processes at periphery and central levels, such as vascularization, inflammation, glucose homeostasis, regulation of oxidative stress and neurotransmission. BH4 de novo synthesis involves the sequential activation of three enzymes, the major controlling point being GTP cyclohydrolase I (GCH1). Complementary salvage and recycling pathways ensure that BH4 levels are tightly kept within a physiological range in the body. Even if the way of transport of BH4 and its ability to enter the brain after peripheral administration is still controversial, data showed increased levels in the brain after BH4 treatment. Available evidence shows that GCH1 expression and BH4 synthesis are stimulated by immunological factors, notably pro-inflammatory cytokines. Once produced, BH4 can act as an anti- inflammatory molecule and scavenger of free radicals protecting against oxidative stress. At the same time, BH4 is prone to autoxidation, leading to the release of superoxide radicals contributing to inflammatory processes, and to the production of BH2, an inactive form of BH4, reducing its bioavailability. Alterations in BH4 levels have been documented in many pathological situations, including Alzheimer's disease, Parkinson's disease and depression, in which increased oxidative stress, inflammation and alterations in monoaminergic function are described. This review aims at providing an update of the knowledge about metabolism and the role of BH4 in brain function, from preclinical to clinical studies, addressing some therapeutic implications.
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Affiliation(s)
- H. Fanet
- INRAe, Nutrition and Integrated Neurobiology, UMR 1286, Bordeaux, France
- Université de Bordeaux, Nutrition and Integrated Neurobiology, UMR 1286, Bordeaux, France
- Faculty of Pharmacy, Université Laval, Quebec City, QC, Canada
- Neurosciences Axis, Centre de Recherche du CHU de Québec-Université Laval, Quebec City, QC, Canada
- OptiNutriBrain International Associated Laboratory (NurtriNeuro France-INAF Canada), Quebec City, Canada
| | - L. Capuron
- INRAe, Nutrition and Integrated Neurobiology, UMR 1286, Bordeaux, France
- Université de Bordeaux, Nutrition and Integrated Neurobiology, UMR 1286, Bordeaux, France
- OptiNutriBrain International Associated Laboratory (NurtriNeuro France-INAF Canada), Quebec City, Canada
| | - N. Castanon
- INRAe, Nutrition and Integrated Neurobiology, UMR 1286, Bordeaux, France
- Université de Bordeaux, Nutrition and Integrated Neurobiology, UMR 1286, Bordeaux, France
- OptiNutriBrain International Associated Laboratory (NurtriNeuro France-INAF Canada), Quebec City, Canada
| | - F. Calon
- Faculty of Pharmacy, Université Laval, Quebec City, QC, Canada
- Neurosciences Axis, Centre de Recherche du CHU de Québec-Université Laval, Quebec City, QC, Canada
- OptiNutriBrain International Associated Laboratory (NurtriNeuro France-INAF Canada), Quebec City, Canada
| | - S. Vancassel
- INRAe, Nutrition and Integrated Neurobiology, UMR 1286, Bordeaux, France
- Université de Bordeaux, Nutrition and Integrated Neurobiology, UMR 1286, Bordeaux, France
- OptiNutriBrain International Associated Laboratory (NurtriNeuro France-INAF Canada), Quebec City, Canada
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Vardy ERLC, MacDonald A, Ford S, Hofman DL. Phenylketonuria, co-morbidity, and ageing: A review. J Inherit Metab Dis 2020; 43:167-178. [PMID: 31675115 DOI: 10.1002/jimd.12186] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 10/27/2019] [Accepted: 10/28/2019] [Indexed: 12/17/2022]
Abstract
Phenylketonuria (PKU) is a metabolic condition which, left untreated, results in severe and irreversible brain damage. Newborn screening and the development of the low phenylalanine (Phe) diet have transformed the outcomes for people with PKU. Those who have benefited from early treatment are now approaching their fifth and sixth decade. It is therefore timely to consider multi-morbidity in PKU and the effects of ageing, in parallel with the wider benefits of emerging treatment options in addition to dietary relaxation. We have conducted the first literature review of co-morbidity and ageing in the context of PKU. Avenues explored have emerged from limited study of multi-morbidity to date and the knowledge and critical enquiry of the authors. Findings suggest PKU to have a wider impact than brain development, and result in several intriguing questions that require investigation to attain the best outcomes for people with PKU in adulthood moving through to older age. We recognise the difficulty in studying longitudinal outcomes in rare diseases and emphasise the necessity to develop PKU registries and cohorts that facilitate well-designed studies to answer some of the questions raised in this review. Whilst awaiting new information in these areas we propose that clinicians engage with patients to make personalised and well-informed decisions around Phe control and assessment for co-morbidity.
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Affiliation(s)
- Emma R L C Vardy
- Department of Ageing and Complex Medicine, Salford Royal NHS Foundation Trust, Salford Care Organisation, Part of Northern Care Alliance NHS Group, Salford, UK
| | - Anita MacDonald
- Department of dietetics, Birmingham Women's and Children's NHS Trust, Birmingham, UK
| | - Suzanne Ford
- National Society for Phenylketonuria, Preston, UK
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Jiang X, Liu H, Shao Y, Peng M, Zhang W, Li D, Li X, Cai Y, Tan T, Lu X, Xu J, Su X, Lin Y, Liu Z, Huang Y, Zeng C, Tang YP, Liu L. A novel GTPCH deficiency mouse model exhibiting tetrahydrobiopterin-related metabolic disturbance and infancy-onset motor impairments. Metabolism 2019; 94:96-104. [PMID: 30742839 DOI: 10.1016/j.metabol.2019.02.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 01/22/2019] [Accepted: 02/05/2019] [Indexed: 11/17/2022]
Abstract
BACKGROUND GTP cyclohydrolase I (GTPCH) deficiency could impair the synthesis of tetrahydrobiopterin and causes metabolic diseases involving phenylalanine catabolism, neurotransmitter synthesis, nitric oxide production and so on. Though improvements could be achieved by tetrahydrobiopterin and neurotransmitter precursor levodopa supplementation, residual motor and mental deficits remain in some patients. An appropriate GTPCH deficiency animal model with clinical symptoms, especially the motor impairments, is still not available for mechanism and therapy studies yet. OBJECTIVES AND METHODS To investigate whether the heterozygous GTPCH missense mutation p.Leu117Arg identified from a patient with severe infancy-onset dopa-responsive motor impairments is causative and establish a clinical relevant GTPCH deficiency mouse model, we generated a mouse mutant mimicking this missense mutation using the CRISPR/Cas9 technology. Series of characterization experiments on the heterozygous and homozygous mutants were conducted. RESULTS The expressions of GTPCH were not significantly changed in the mutants, but the enzyme activities were impaired in the homozygous mutants. BH4 reduction and phenylalanine accumulation were observed both in the liver and brain of the homozygous mutants. Severer metabolic disturbance occurred in the brain than in the liver. Significant reduction of neurotransmitter dopamine, norepinephrine and serotonin was observed in the brains of homozygous mutants. Live-born homozygous mutants exhibited infancy-onset motor and vocalization deficits similar to the disease symptoms observed in the patient, while no obvious symptoms were observed in the young heterozygous mutant mice. With benserazide-levodopa treatment, survival of the homozygous mutants was improved but not completely rescued. CONCLUSIONS The GTPCH p.Leu117Arg missense mutation is deleterious and could cause tetrahydrobiopterin, phenylalanine and neurotransmitter metabolic disturbances and infancy-onset motor dysfunctions recessively. This is the first GTPCH deficiency mouse model which could be live-born and exhibits significant motor impairments. The different extents of BH4 reduction and phenylalanine accumulation observed between liver and brain in response to GTPCH deficiency gives potential new insights into the vulnerability of brain to GTPCH deficiency.
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Affiliation(s)
- Xiaoling Jiang
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510623, China
| | - Huazhen Liu
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510623, China
| | - Yongxian Shao
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510623, China
| | - Mingzhi Peng
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510623, China
| | - Wen Zhang
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510623, China
| | - Duan Li
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510623, China
| | - Xiuzhen Li
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510623, China
| | - Yanna Cai
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510623, China
| | - Ting Tan
- Lab of Neural Development and Behavior Genetics, Institute of Pediatrics, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510623, China
| | - Xinshuo Lu
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510623, China
| | - Jianan Xu
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510623, China
| | - Xueying Su
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510623, China
| | - Yunting Lin
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510623, China
| | - Zongcai Liu
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510623, China
| | - Yonglan Huang
- Department of Neonatal Screening, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510623, China
| | - Chunhua Zeng
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510623, China
| | - Ya-Ping Tang
- Lab of Neural Development and Behavior Genetics, Institute of Pediatrics, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510623, China.
| | - Li Liu
- Department of Genetics and Endocrine, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, Guangdong 510623, China.
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Pakula MM, Maier TJ, Vorup-Jensen T. Insight on the impacts of free amino acids and their metabolites on the immune system from a perspective of inborn errors of amino acid metabolism. Expert Opin Ther Targets 2017; 21:611-626. [PMID: 28441889 DOI: 10.1080/14728222.2017.1323879] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Amino acids (AAs) support a broad range of functions in living organisms, including several that affect the immune system. The functions of the immune system are affected when free AAs are depleted or in excess because of external factors, such as starvation, or because of genetic factors, such as inborn errors of metabolism. Areas covered: In this review, we discuss the current insights into how free AAs affect immune responses. When possible, we make comparisons to known disease states resulting from inborn errors of metabolism, in which changed levels of AAs or AA metabolites provide insight into the impact of AAs on the human immune system in vivo. We also explore the literature describing how changes in AA levels might provide pharmaceutical targets for safe immunomodulatory treatment. Expert opinion: The impact of free AAs on the immune system is a neglected topic in most immunology textbooks. That neglect is undeserved, because free AAs have both direct and indirect effects on the immune system. Consistent choices of pre-clinical models and better strategies for creating formulations are required to gain clinical impact.
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Affiliation(s)
| | - Thorsten J Maier
- a Department of Biomedicine , Aarhus University , Aarhus , Denmark
| | - Thomas Vorup-Jensen
- a Department of Biomedicine , Aarhus University , Aarhus , Denmark.,b Center for Neurodegenerative Inflammation Prevention (NEURODIN) , Aarhus University , Aarhus , Denmark.,c Interdisciplinary Nanoscience Center , Aarhus University , Aarhus , Denmark.,d The Lundbeck Foundation Nanomedicine Center for Individualized Management of Tissue Damage and Regeneration (LUNA) , Aarhus University , Aarhus , Denmark.,e MEMBRANES Research center , Aarhus University , Aarhus , Denmark
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Daali Y, Millet P, Dayer P, Pastor CM. Evidence of Drug-Drug Interactions through Uptake and Efflux Transport Systems in Rat Hepatocytes: Implications for Cellular Concentrations of Competing Drugs. Drug Metab Dispos 2013; 41:1548-56. [DOI: 10.1124/dmd.113.051870] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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10
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Millet P, Moulin M, Stieger B, Daali Y, Pastor CM. How Organic Anions Accumulate in Hepatocytes Lacking Mrp2: Evidence in Rat Liver. J Pharmacol Exp Ther 2011; 336:624-632. [DOI: 10.1124/jpet.110.175406] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023] Open
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11
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Sumi-Ichinose C, Ichinose H, Ikemoto K, Nomura T, Kondo K. Advanced Research on Dopamine Signaling to Develop Drugs for the Treatment of Mental Disorders: Regulation of Dopaminergic Neural Transmission by Tyrosine Hydroxylase Protein at Nerve Terminals. J Pharmacol Sci 2010; 114:17-24. [DOI: 10.1254/jphs.09r28fm] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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12
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Schiffer E, Frossard JL, Rubbia-Brandt L, Mentha G, Pastor CM. Hepatic regeneration is decreased in a rat model of sinusoidal obstruction syndrome. J Surg Oncol 2009; 99:439-46. [PMID: 19353590 DOI: 10.1002/jso.21276] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND AND OBJECTIVES Oxaliplatin is a chemotherapeutic drug for colorectal adenocarcinoma able to extend the indications for resection of colorectal liver metastases. However, the drug may severely injure hepatic sinusoids, inducing a sinusoidal obstruction syndrome in non-tumoral parenchyma with a risk of decreased regeneration in the remnant liver following partial hepatectomy. METHODS We then investigated the evolution of hepatic functions and liver regeneration following partial hepatectomy in rats with sinusoidal obstruction syndrome. The sinusoidal obstruction syndrome was induced with a single intragastric administration of monocrotaline (MCT). RESULTS MCT administration induced obstruction of the hepatic microcirculation and increased portal pressure, hepatic VEGF expression, and Ki67 positive hepatocytes. A mild cholestasis was present without modification of hepatic tests. Following a 70% hepatectomy, liver regeneration was significantly impaired by MCT administration and this impaired regeneration was associated with hepatocellular injury evidenced 1 week after hepatectomy. CONCLUSIONS The presence of sinusoidal obstruction syndrome impairs hepatic regeneration in this rat model of sinusoidal obstruction syndrome.
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Affiliation(s)
- Eduardo Schiffer
- Laboratoire de Physiopathologie Hépatique et Imagerie Moléculaire, Hôpitaux Universitaires de Genève, Geneva 1205, Switzerland
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Planchamp C, Hadengue A, Stieger B, Bourquin J, Vonlaufen A, Frossard JL, Quadri R, Becker CD, Pastor CM. Function of Both Sinusoidal and Canalicular Transporters Controls the Concentration of Organic Anions within Hepatocytes. Mol Pharmacol 2007; 71:1089-97. [PMID: 17234897 DOI: 10.1124/mol.106.030759] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
We hypothesized that the function of both sinusoidal and canalicular transporters importantly controls the concentrations of organic anions within normal hepatocytes. Consequently, we investigated how acute transport regulation of the sinusoidal organic anion transporting polypeptides (Oatps) and the canalicular multidrug resistance associated protein 2 (Mrp(2)) determines the hepatic concentrations of the organic anion gadolinium benzyloxypropionictetraacetate (BOPTA) in rat livers. Livers were perfused with labeled BOPTA in different experimental settings that modify the function of Oatps and Mrp(2) through the protein kinase C (PKC) pathway. Intrahepatic concentrations were continuously measured with a gamma probe placed above rat livers. Labeled BOPTA was also measured in perfusate and bile. We showed that when the function of Oatps and Mrp(2) is modified in such a way that BOPTA entry and exit are similarly decreased, concentrations of organic anions within hepatocytes remain unaltered. When exit through Mrp(2) is abolished, hepatic concentrations are high if entry through Oatps is only slightly decreased (livers without Mrp(2) expression) or low if BOPTA uptake is more importantly decreased (livers perfused with a PKC activator). These results highlight that the function of both sinusoidal and canalicular transporters is important to determine the concentration of organic anions within hepatocytes.
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Affiliation(s)
- Corinne Planchamp
- Laboratoire de Physiopathologie Hépatique et Imagerie Moléculaire, Hôpitaux Universitaires de Genève, Rue Micheli-du-Crest, 24, 1205 Geneva, Switzerland
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Planchamp C, Pastor CM, Balant L, Becker CD, Terrier F, Gex-Fabry M. Quantification of Gd-BOPTA uptake and biliary excretion from dynamic magnetic resonance imaging in rat livers: model validation with 153Gd-BOPTA. Invest Radiol 2006; 40:705-14. [PMID: 16230903 DOI: 10.1097/01.rli.0000183053.08921.2b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVES We sought to develop and validate a pharmacokinetic model allowing description of the magnetic resonance (MR) signal intensity induced by the hepatobiliary contrast agent Gd-BOPTA and to quantify the overall Gd-BOPTA transport in rat liver. MATERIALS AND METHODS MR signal intensity was recorded during the perfusion of rat livers with Gd-DTPA, an extracellular contrast agent, and Gd-BOPTA, a hepatobiliary contrast agent. Similar experiments were conducted with Gd-labeled contrast agents for quantitative measurement in liver, bile and perfusate. RESULTS A complete 6-compartment, 8 parameter open model was first developed to describe the pharmacokinetics of the compound based on the radioactivity data analysis. Because perfusate and bile data were not available in MRI experiments, a reduced model (6-compartment, 5 parameters) was considered for the MRI data. The performance of the reduced model was tested using the radioactivity data. The reduced model successfully described the contrast agent amount in the liver and correctly predicted amounts in bile and perfusate. CONCLUSIONS Pharmacokinetic modeling of MR signal intensity induced by Gd-BOPTA permits quantification of Gd-BOPTA uptake and biliary excretion in rat livers.
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Affiliation(s)
- Corinne Planchamp
- Department of Radiology, Geneva University Hospitals, Geneva, Switzerland.
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Loughran PA, Stolz DB, Vodovotz Y, Watkins SC, Simmons RL, Billiar TR. Monomeric inducible nitric oxide synthase localizes to peroxisomes in hepatocytes. Proc Natl Acad Sci U S A 2005; 102:13837-42. [PMID: 16172396 PMCID: PMC1216830 DOI: 10.1073/pnas.0503926102] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Hepatocytes are capable of repeated inducible NO synthase (iNOS) expression, which occurs under inflammatory and stress conditions. This iNOS expression regulates a number of cellular functions as well as cell viability. To better understand the posttranslational mechanisms that regulate the fate of iNOS in these cells, we characterized the iNOS distributed within peroxisomes. The selective permeabilization of membranes (plasma vs. peroxisomal) confirmed that there are cytosolic and peroxisomal pools of iNOS in cytokine-stimulated hepatocytes and that the iNOS protein associates with peroxisome. Detergent solubilization of the membrane fraction released iNOS to the soluble fraction. iNOS localized to membrane fraction is predominantly monomeric, but dimerization is partially reconstituted rapidly upon incubation with tetrahydrobiopterin. The reconstituted iNOS exhibits a lower specific activity than iNOS isolated from the soluble pool. Depletion of intracellular tetrahydrobiopterin with an inhibitor of de novo pterin synthesis resulted in a predominance of monomeric iNOS without a greater relative distribution of iNOS to the peroxisomal pool. Thus, iNOS exists in a least two pools in hepatocytes: a soluble pool composed of both active dimer and monomer and a peroxisomal pool of monomeric iNOS. iNOS might localize to peroxisomes in long-lived cells such as hepatocytes as a protective mechanism to remove incompetent enzyme.
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Affiliation(s)
- P A Loughran
- Departments of Surgery and Center for Biologic Imaging, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA.
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Planchamp C, Beyer GJ, Slosman DO, Terrier F, Pastor CM. Direct evidence of the temperature dependence of Gd-BOPTA transport in the intact rat liver. Appl Radiat Isot 2005; 62:943-9. [PMID: 15799874 DOI: 10.1016/j.apradiso.2004.11.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2004] [Revised: 11/12/2004] [Accepted: 11/18/2004] [Indexed: 11/30/2022]
Abstract
The aim was to study the influence of temperature on the transport of the hepatobiliary contrast agent Gadobenate dimeglumine (Gd-BOPTA). Rat livers were isolated and perfused with Gd-BOPTA at 12, 25, 30, 36 and 38 degrees C. After the perfusion period, biopsies were collected and the MR signal intensity was measured. Uptake and biliary excretion were quantified with radiolabeled Gd-BOPTA. MR signal intensity decreased with temperature of perfusion. This phenomenon was appropriately quantified with 153Gd and 153Sm labeling, in contrast to 67Ga.
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Affiliation(s)
- Corinne Planchamp
- Laboratoire de physiopathologie hépatique, et imagerie moléculaire, Département de Radiologie, Hôpitaux Universitaires de Genève, Rue Micheli-du-Crest 24, CH-1211 Genève 14, Switzerland.
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17
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Planchamp C, Montet X, Frossard JL, Quadri R, Stieger B, Meier PJ, Ivancevic MK, Vallée JP, Terrier F, Pastor CM. Magnetic Resonance Imaging With Hepatospecific Contrast Agents in Cirrhotic Rat Livers. Invest Radiol 2005; 40:187-94. [PMID: 15770136 DOI: 10.1097/01.rli.0000154587.00638.77] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE During biliary cirrhosis in rats, organic anion-transporting peptides (Oatps) and ATP-dependent multidrug resistance-associated protein 2 (Mrp2) that are likely to transport the contrast agent Gd-BOPTA through hepatocytes are down-regulated. However, the consequences of such down-regulation on the signal intensity (SI) enhancement are unknown. Consequently, the aim of our study was to measure the hepatic SI enhancement during Gd-BOPTA perfusion as well as the Oatp and Mrp2 expression in normal and cirrhotic livers. MATERIALS AND METHODS The hepatic SI enhancement during Gd-BOPTA perfusion was measured in livers isolated from normal rats and rats that had a bile duct ligation (BDL) 15, 30, and 60 days before the perfusion. Hepatic injury and transporter expression were measured in control and cirrhotic rats. RESULTS BDL induced a severe hepatic injury that increased over time with a down-regulation of the transporter expression. The extracellular space (assessed by Gd-DTPA perfusion) increased with the severity of the disease. Gd-BOPTA-induced SI enhancement remained similar in BDL-15 and BDL-30 rats than in control rats but significantly decreased in severe cirrhosis (BDL-60 rats). In comparison, the Mn-DPDP-induced SI enhancement decreases proportionally to the severity of the disease. CONCLUSION During biliary cirrhosis, Gd-BOPTA-induced SI enhancement could not be related to the hepatic expression of transporters.
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Affiliation(s)
- Corinne Planchamp
- Département de Radiologie and Division de Gastroentérologie, Höpitaux Universitaires de Genève, Geneva, Switzerland
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18
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Pastor CM, Planchamp C, Pochon S, Lorusso V, Montet X, Mayer J, Terrier F, Vallee JP. Kinetics of gadobenate dimeglumine in isolated perfused rat liver: MR imaging evaluation. Radiology 2003; 229:119-25. [PMID: 12944603 DOI: 10.1148/radiol.2291020726] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
PURPOSE To compare in the entire liver, the hepatic kinetics of gadobenate dimeglumine (Gd-BOPTA) and gadopentetate dimeglumine (Gd-DTPA) and to evaluate the hepatic transport of Gd-BOPTA. MATERIALS AND METHODS The authors studied both contrast agents in isolated perfused rat livers by measuring the magnetic resonance (MR) signal intensity (SI) in 12 rats, as well as the gadolinium concentrations in hepatic tissues in 42 rats. The intrahepatic transport of Gd-BOPTA was investigated with pharmacologic antagonism by using bromosulfophthalein. MR imaging was performed at 1.5 T with a fast gradient-echo T1-weighted MR sequence. RESULTS The hepatic kinetics based on the MR SI measured over time showed a rapid steady state during Gd-DTPA perfusion, while the SI continuously increased during the 30-minute Gd-BOPTA perfusion period. The pharmacokinetic modeling indicated that the half-lives of Gd-DTPA entry and exit were identical (mean, 1.3 minutes +/- 0.9 [standard error of mean]) and shorter than those observed with Gd-BOPTA (P <.001). The uptake of Gd-BOPTA was faster (mean half-life, 4.8 minutes +/- 0.3) than the washout (mean half-life, 17.5 minutes +/- 2.8) (P =.001). The combined perfusion of bromosulfophthalein and Gd-BOPTA decreased the SI enhancement in comparison with the perfusion of Gd-BOPTA alone (mean, 0.56 +/- 0.03 vs 2.54 +/- 0.39, P <.001). The entry and exit kinetic parameters obtained during the perfusion of Gd-BOPTA plus bromosulfophthalein were identical and comparable to those obtained during Gd-DTPA perfusion (P =.95). Acute bile duct ligation did not interfere with the uptake of Gd-BOPTA in hepatocytes, but it slowed down the excretion by approximately 50%. Measurements of gadolinium concentrations in hepatic tissues confirmed these findings. CONCLUSION In the liver, the hepatospecific contrast agent Gd-BOPTA enters into hepatocytes likely through the organic anion transporting peptide 1.
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Affiliation(s)
- Catherine M Pastor
- Department of Radiology, Hôpital Universitaire de Genève, Rue Micheli-du-Crest 24, Bâtiment C, Room 6-795, 1211 Geneva 14, Switzerland.
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19
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Abstract
The precursor for nitric oxide (NO) synthesis is the amino acid arginine. Reduced arginine availability may limit NO production. Arginine availability for NO synthesis may be regulated by de novo arginine production from citrulline, arginine transport across the cell membrane, and arginine breakdown by arginase.
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Affiliation(s)
- M M Hallemeesch
- Department of Clinical Chemistry, Vrije Universiteit Medical Center, Amsterdam, The Netherlands
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20
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Soeters PB, Hallemeesch MM, Bruins MJ, van Eijk HMH, Deutz NEP. Quantitative in vivo assessment of arginine utilization and nitric oxide production in endotoxemia. Am J Surg 2002; 183:480-8. [PMID: 11975939 DOI: 10.1016/s0002-9610(02)00847-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Until recently no methods were available to quantitate nitric oxide (NO) production in vivo. The advent of stable isotope techniques has allowed quantitation of NO production in different animal models and human disease states. METHODS In vivo NO production was assessed with the use of stable isotope labeled arginine. Enrichments of metabolites were measured by liquid chromatography-mass spectrometry (LC-MS). Knock-out mice were used to assess the influence of knocking out inducible NOS (iNOS) or constitutively expressed NOS (cNOS) on arginine-NO metabolism. Pig models were used to assess the role of individual organs on arginine-NO fluxes. RESULTS In mice under basal conditions cNOS mediates half of the NO production. After endotoxin challenge NO production doubles as a result of iNOS induction and cNOS-mediated NO production is downregulated. In larger animal models (pig) whole body NO production is augmented after endotoxin challenge, largely resulting from NO production in liver, intestine and kidney. Arginine supplementation increases NO production in pigs in liver, intestine and kidney both in the basal state and after endotoxin challenge. CONCLUSIONS Stable isotope techniques employing LC-MS allow in vivo assessment of NO production in small and large animal models and in patients. This allows definition of the role that iNOS and cNOS-mediated NO production play in several disease states.
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Affiliation(s)
- Peter B Soeters
- Department of Surgery, Maastricht University, P.O. Box 616, 6200 MD, Maastricht, The Netherlands.
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21
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Werner ER, Bahrami S, Heller R, Werner-Felmayer G. Bacterial lipopolysaccharide down-regulates expression of GTP cyclohydrolase I feedback regulatory protein. J Biol Chem 2002; 277:10129-33. [PMID: 11799107 DOI: 10.1074/jbc.m107326200] [Citation(s) in RCA: 23] [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
GTP cyclohydrolase I feedback regulatory protein (GFRP) is a 9.7-kDa protein regulating GTP cyclohydrolase I activity in dependence of tetrahydrobiopterin and phenylalanine concentrations, thus enabling stimulation of tetrahydrobiopterin biosynthesis by phenylalanine to ensure its efficient metabolism by phenylalanine hydroxylase. Here, we were interested in regulation of GFRP expression by proinflammatory cytokines and stimuli, which are known to induce GTP cyclohydrolase I expression. Recombinant human GFRP stimulated recombinant human GTP cyclohydrolase I in the presence of phenylalanine and mediated feedback inhibition by tetrahydrobiopterin. Levels of GFRP mRNA in human myelomonocytoma (THP-1) cells remained unaltered by treatment of cells with interferon-gamma or interleukin-1beta, but were significantly down-regulated by bacterial lipopolysaccharide (LPS, 1 microg/ml), without or with cotreatment by interferon-gamma, which strongly up-regulated GTP cyclohydrolase I expression and activity. GFRP expression was also suppressed in human umbilical vein endothelial cells treated with 1 microg/ml LPS, as well as in rat tissues 7 h post intraperitoneal injection of 10 mg/kg LPS. THP-1 cells stimulated with interferon-gamma alone showed increased pteridine synthesis by addition of phenylalanine to the culture medium. Cells stimulated with interferon-gamma plus LPS, in contrast, showed phenylalanine-independent pteridine synthesis. These results demonstrate that LPS down-regulates expression of GFRP, thus rendering pteridine synthesis independent of metabolic control by phenylalanine.
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Affiliation(s)
- Ernst R Werner
- Institute for Medical Chemistry and Biochemistry, University of Innsbruck, Fritz-Pregl-Strasse 3, A-6020 Innsbruck, Austria.
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22
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Sumi-Ichinose C, Urano F, Kuroda R, Ohye T, Kojima M, Tazawa M, Shiraishi H, Hagino Y, Nagatsu T, Nomura T, Ichinose H. Catecholamines and serotonin are differently regulated by tetrahydrobiopterin. A study from 6-pyruvoyltetrahydropterin synthase knockout mice. J Biol Chem 2001; 276:41150-60. [PMID: 11517215 DOI: 10.1074/jbc.m102237200] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
(6R)-L-erythro-5,6,7,8-Tetrahydrobiopterin (BH4) is an essential cofactor for tyrosine hydroxylase (TH), tryptophan hydroxylase, phenylalanine hydroxylase, and nitric-oxide synthase. These enzymes synthesize neurotransmitters, e.g. catecholamines, serotonin, and nitric oxide (NO). We established mice unable to synthesize BH4 by disruption of the 6-pyruvoyltetrahydropterin synthase gene, the encoded protein of which catalyzes the second step of BH4 biosynthesis. Homozygous mice were born at the almost expected Mendelian ratio, but died within 48 h after birth. In the brain of homozygous mutant neonates, levels of biopterin, catecholamines, and serotonin were extremely low. The number of TH molecules was highly dependent on the intracellular concentration of BH4 at nerve terminals. Alteration of the TH protein level by modulation of the BH4 content is a novel regulatory mechanism. Our data showing that catecholaminergic, serotonergic, and NO systems were differently affected by BH4 starvation suggest the possible involvement of BH4 synthesis in the etiology of monoamine-based neurological and neuropsychiatric disorders.
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Affiliation(s)
- C Sumi-Ichinose
- Department of Pharmacology, School of Medicine, Fujita Health University, Toyoake, Aichi 470-1192, Japan
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Pastor CM, Hadengue A. Acidosis modifies metabolic functions but does not affect vascular resistances in perfused rat livers. J Hepatol 2001; 34:507-13. [PMID: 11394649 DOI: 10.1016/s0168-8278(00)00052-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
BACKGROUND Few data exist concerning the consequences of acidosis on intrahepatic vascular resistances and hepatic functions. METHODS The consequences of pH and PCO2 changes on the intrahepatic vascular reactivity to norepinephrine (NE, 10(-9) to 3 x 10(-5) M) have been investigated in isolated rat livers perfused with solutions bubbled with 5, 10, or 15% CO2 and in solutions in which pH was decreased by replacing HCO3- with NaCl while maintaining a normal PCO2. Hepatic O2 consumption (VO2) and urea release were also measured during these experiments. RESULTS The NE-induced increase of portal pressure did not change during hypercarbic and normocarbic acidosis. In contrast, the NE-induced increase of urea release was higher when the solution of perfusion was bubbled with 10 and 15% CO2, while during normocarbic acidosis the NE-induced increase of urea release did not change with pH. In the absence of NE, acidosis decreased hepatic VO2 and urea release but portal pressure was not modified by changing % CO2 or pH in the Krebs-Henseleit-bicarbonate solution. CONCLUSIONS This study clearly shows that, in the liver, the consequences of acidosis are far more important on the metabolism (VO2 and urea release) than on the intrahepatic vascular resistance.
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Affiliation(s)
- C M Pastor
- Division d'Hépatologie et de Gastroentérologie, Hĵpital Cantonal Universitaire de Genève, Switzerland.
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24
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Abstract
Fluid shear stress can be increased either by increasing the flow rate or perfusing increasing doses of norepinephrine (NE) at a constant flow rate. Concomitantly, increased fluid shear stress at the surface of endothelial cells releases nitric oxide (NO). To better understand the role of NO released by shear stress in regulating intrahepatic vascular resistances, we increased fluid shear stress either by changing the flow rate or by perfusing increasing doses of NE at a constant flow rate in perfused livers isolated from normal rats. When concentration-response curves to NE were studied at low, mild, and high flow rates, portal pressure increased during NE perfusion. The higher the flow rate, the lower the response to NE. NO synthase inhibition similarly increased the response to NE at each flow rate. Thus, NO was released by NE-induced increased shear stress, but other vasodilators are likely to be responsible for the flow-induced increased shear stress. In additional experiments, when flow rate was decreased while infusing increasing doses of NE to maintain the portal pressure constant, shear stress remained steady and NO was not released. Hepatic NO production in the different conditions of shear stress could not be detected. Our data are consistent with the fact that in the liver, NO released by shear stress decreases the vasoconstriction to NE and regulates the intrahepatic vascular resistances.
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Affiliation(s)
- C M Pastor
- Division d'hépatologie et de gastro-entérologie, Hôpital Cantonal Universitaire de Genève, Switzerland.
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25
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Nagatsu T, Ichinose H. Regulation of pteridine-requiring enzymes by the cofactor tetrahydrobiopterin. Mol Neurobiol 1999; 19:79-96. [PMID: 10321973 DOI: 10.1007/bf02741379] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Tetrahydrobiopterin (BH4) is synthesized from guanosine triphosphate (GTP) by GTP cyclohydrolase I (GCH), 6-pyruvoyltetrahydropterin synthase (PTS), and sepiapterin reductase (SPD). GCH is the rate-limiting enzyme. BH4 is a cofactor for three pteridine-requiring monooxygenases that hydroxylate aromatic L-amino acids, i.e., tyrosine hydroxylase (TH), tryptophan hydroxylase (TPH), and phenylalanine hydroxylase (PAH), as well as for nitric oxide synthase (NOS). The intracellular concentrations of BH4, which are mainly determined by GCH activity, may regulate the activity of TH (an enzyme-synthesizing catecholamines from tyrosine), TPH (an enzyme-synthesizing serotonin and melatonin from tryptophan), PAH (an enzyme required for complete degradation of phenylalanine to tyrosine, finally to CO2 + H2O), and also the activity of NOS (an enzyme forming NO from arginine), Dominantly inherited hereditary progressive dystonia (HPD), also termed DOPA-responsive dystonia (DRD) or Segawa's disease, is a dopamine deficiency in the nigrostriatal dopamine neurons, and is caused by mutations of one allele of the GCH gene. GCH activity and BH4 concentrations in HPD/DRD are estimated to be 2-20% of the normal value. By contrast, recessively inherited GCH deficiency is caused by mutations of both alleles of the GCH gene, and the GCH activity and BH4 concentrations are undetectable. The phenotypes of recessive GCH deficiency are severe and complex, such as hyperphenylalaninemia, muscle hypotonia, epilepsy, and fever episode, and may be caused by deficiencies of various neurotransmitters, including dopamine, norepinephrine, serotonin, and NO. The biosynthesis of dopamine, norepinephrine, epinephrine, serotonin, melatonin, and probably NO by individual pteridine-requiring enzymes may be differentially regulated by the intracellular concentration of BH4, which is mainly determined by GCH activity. Dopamine biosynthesis in different groups of dopamine neurons may be differentially regulated by TH activity, depending on intracellular BH4 concentrations and GCH activity. The nigrostriatal dopamine neurons may be most susceptible to a partial decrease in BH4, causing dopamine deficiency in the striatum and the HPD/DRD phenotype.
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Affiliation(s)
- T Nagatsu
- Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi, Japan
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Takeshima H, Shimuta M, Komazaki S, Ohmi K, Nishi M, Iino M, Miyata A, Kangawa K. Mitsugumin29, a novel synaptophysin family member from the triad junction in skeletal muscle. Biochem J 1998; 331 ( Pt 1):317-22. [PMID: 9512495 PMCID: PMC1219354 DOI: 10.1042/bj3310317] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In skeletal muscle, excitation-contraction (E-C) coupling requires the conversion of the depolarization signal of the invaginated surface membrane, namely the transverse (T-) tubule, to Ca2+ release from the sarcoplasmic reticulum (SR). Signal transduction occurs at the junctional complex between the T-tubule and SR, designated as the triad junction, which contains two components essential for E-C coupling, namely the dihydropyridine receptor as the T-tubular voltage sensor and the ryanodine receptor as the SR Ca2+-release channel. However, functional expression of the two receptors seemed to constitute neither the signal-transduction system nor the junction between the surface and intracellular membranes in cultured cells, suggesting that some as-yet-unidentified molecules participate in both the machinery. In addition, the molecular basis of the formation of the triad junction is totally unknown. It is therefore important to examine the components localized to the triad junction. Here we report the identification using monoclonal antibody and primary structure by cDNA cloning of mitsugumin29, a novel transmembrane protein from the triad junction in skeletal muscle. This protein is homologous in amino acid sequence and shares characteristic structural features with the members of the synaptophysin family. The subcellular distribution and protein structure suggest that mitsugumin29 is involved in communication between the T-tubular and junctional SR membranes.
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Affiliation(s)
- H Takeshima
- Department of Pharmacology, Faculty of Medicine, University of Tokyo, and CREST, Japan Science and Technology Corporation, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113, Japan
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Haass NK, Kartenbeck MA, Leube RE. Pantophysin is a ubiquitously expressed synaptophysin homologue and defines constitutive transport vesicles. J Cell Biol 1996; 134:731-46. [PMID: 8707851 PMCID: PMC2120938 DOI: 10.1083/jcb.134.3.731] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Certain properties of the highly specialized synaptic transmitter vesicles are shared by constitutively occurring vesicles. We and others have thus identified a cDNA in various nonneuroendocrine cell types of rat and human that is related to synaptophysin, one of the major synaptic vesicle membrane proteins, which we termed pantophysin. Here we characterize the gene structure, mRNA and protein expression, and intracellular distribution of pantophysin. Its mRNA is detected in murine cell types of nonneuroendocrine as well as of neuroendocrine origin. The intron/exon structure of the murine pantophysin gene is identical to that of synaptophysin except for the last intron that is absent in pantophysin. The encoded polypeptide of calculated mol wt 28,926 shares many sequence features with synaptophysin, most notably the four hydrophobic putative transmembrane domains, although the cytoplasmic end domains are completely different. Using antibodies against the unique carboxy terminus pantophysin can be detected by immunofluorescence microscopy in both exocrine and endocrine cells of human pancreas, and in cultured cells, colocalizing with constitutive secretory and endocytotic vesicle markers in nonneuroendocrine cells and with synaptophysin in cDNA-transfected epithelial cells. By immunoelectron microscopy, the majority of pantophysin reactivity is detected at vesicles with a diameter of < 100 nm that have a smooth surface and an electron-translucent interior. Using cell fractionation in combination with immunoisolation, these vesicles are enriched in a light fraction and shown to contain the cellular vSNARE cellubrevin and the ubiquitous SCAMPs in epithelial cells and synaptophysin in neuroendocrine or cDNA-transfected nonneuroendocrine cells and neuroendocrine tissues. Pantophysin is therefore a broadly distributed marker of small cytoplasmic transport vesicles independent of their content.
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Affiliation(s)
- N K Haass
- Division of Cell Biology, German Cancer Research Center, Heidelberg, Federal Republic of Germany
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