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Hanelova K, Raudenska M, Kratochvilova M, Navratil J, Vicar T, Bugajova M, Gumulec J, Masarik M, Balvan J. Autophagy modulators influence the content of important signalling molecules in PS-positive extracellular vesicles. Cell Commun Signal 2023; 21:120. [PMID: 37226246 DOI: 10.1186/s12964-023-01126-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 04/06/2023] [Indexed: 05/26/2023] Open
Abstract
Extracellular vesicles (EVs) are important mediators of intercellular communication in the tumour microenvironment. Many studies suggest that cancer cells release higher amounts of EVs exposing phosphatidylserine (PS) at the surface. There are lots of interconnections between EVs biogenesis and autophagy machinery. Modulation of autophagy can probably affect not only the quantity of EVs but also their content, which can deeply influence the resulting pro-tumourigenic or anticancer effect of autophagy modulators. In this study, we found that autophagy modulators autophinib, CPD18, EACC, bafilomycin A1 (BAFA1), 3-hydroxychloroquine (HCQ), rapamycin, NVP-BEZ235, Torin1, and starvation significantly alter the composition of the protein content of phosphatidylserine-positive EVs (PS-EVs) produced by cancer cells. The greatest impact had HCQ, BAFA1, CPD18, and starvation. The most abundant proteins in PS-EVs were proteins typical for extracellular exosomes, cytosol, cytoplasm, and cell surface involved in cell adhesion and angiogenesis. PS-EVs protein content involved mitochondrial proteins and signalling molecules such as SQSTM1 and TGFβ1 pro-protein. Interestingly, PS-EVs contained no commonly determined cytokines, such as IL-6, IL-8, GRO-α, MCP-1, RANTES, and GM-CSF, which indicates that secretion of these cytokines is not predominantly mediated through PS-EVs. Nevertheless, the altered protein content of PS-EVs can still participate in the modulation of the fibroblast metabolism and phenotype as p21 was accumulated in fibroblasts influenced by EVs derived from CPD18-treated FaDu cells. The altered protein content of PS-EVs (data are available via ProteomeXchange with identifier PXD037164) also provides information about the cellular compartments and processes that are affected by the applied autophagy modulators. Video Abstract.
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Affiliation(s)
- Klara Hanelova
- Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Martina Raudenska
- Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
- Department of Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Monika Kratochvilova
- Department of Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Jiri Navratil
- Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Tomas Vicar
- Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
- Department of Biomedical Engineering, Faculty of Electrical Engineering and Communication, Brno University of Technology, Technicka 3058/10, Brno, Czech Republic
| | - Maria Bugajova
- Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Jaromir Gumulec
- Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Michal Masarik
- Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
- Department of Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
- First Faculty of Medicine, Charles University, Katerinska 32, 12108, Prague, Czech Republic
| | - Jan Balvan
- Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.
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Jayaram R, Jones M, Reilly S, Crabtree MJ, Pal N, Goodfellow N, Nahar K, Simon J, Carnicer R, DeSilva R, Ratnatunga C, Petrou M, Sayeed R, Roalfe A, Channon KM, Bashir Y, Betts T, Hill M, Casadei B. Atrial nitroso-redox balance and refractoriness following on-pump cardiac surgery: a randomized trial of atorvastatin. Cardiovasc Res 2022; 118:184-195. [PMID: 33098411 PMCID: PMC8752359 DOI: 10.1093/cvr/cvaa302] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 09/07/2020] [Accepted: 10/12/2020] [Indexed: 01/19/2023] Open
Abstract
AIMS Systemic inflammation and increased activity of atrial NOX2-containing NADPH oxidases have been associated with the new onset of atrial fibrillation (AF) after cardiac surgery. In addition to lowering LDL-cholesterol, statins exert rapid anti-inflammatory and antioxidant effects, the clinical significance of which remains controversial. METHODS AND RESULTS We first assessed the impact of cardiac surgery and cardiopulmonary bypass (CPB) on atrial nitroso-redox balance by measuring NO synthase (NOS) and GTP cyclohydrolase-1 (GCH-1) activity, biopterin content, and superoxide production in paired samples of the right atrial appendage obtained before (PRE) and after CPB and reperfusion (POST) in 116 patients. The effect of perioperative treatment with atorvastatin (80 mg once daily) on these parameters, blood biomarkers, and the post-operative atrial effective refractory period (AERP) was then evaluated in a randomized, double-blind, placebo-controlled study in 80 patients undergoing cardiac surgery on CPB. CPB and reperfusion led to a significant increase in atrial superoxide production (74% CI 71-76%, n = 46 paired samples, P < 0.0001) and a reduction in atrial tetrahydrobiopterin (BH4) (34% CI 33-35%, n = 36 paired samples, P < 0.01), and in GCH-1 (56% CI 55-58%, n = 26 paired samples, P < 0.001) and NOS activity (58% CI 52-67%, n = 20 paired samples, P < 0.001). Perioperative atorvastatin treatment prevented the effect of CPB and reperfusion on all parameters but had no significant effect on the postoperative right AERP, troponin release, or NT-proBNP after cardiac surgery. CONCLUSION Perioperative statin therapy prevents post-reperfusion atrial nitroso-redox imbalance in patients undergoing on-pump cardiac surgery but has no significant impact on postoperative atrial refractoriness, perioperative myocardial injury, or markers of postoperative LV function. CLINICAL TRIAL REGISTRATION https://clinicaltrials.gov/ct2/show/NCT01780740.
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Affiliation(s)
- Raja Jayaram
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, L6, West Wing, Oxford OX3 9DU, UK
| | - Michael Jones
- Cardiology, Oxford Heart Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Svetlana Reilly
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, L6, West Wing, Oxford OX3 9DU, UK
| | - Mark J Crabtree
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, L6, West Wing, Oxford OX3 9DU, UK
| | - Nikhil Pal
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, L6, West Wing, Oxford OX3 9DU, UK
| | - Nicola Goodfellow
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, L6, West Wing, Oxford OX3 9DU, UK
| | - Keshav Nahar
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, L6, West Wing, Oxford OX3 9DU, UK
| | - Jillian Simon
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, L6, West Wing, Oxford OX3 9DU, UK
| | - Ricardo Carnicer
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, L6, West Wing, Oxford OX3 9DU, UK
| | - Ravi DeSilva
- Cardiothoracic Surgery, Oxford Heart Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Chandana Ratnatunga
- Cardiothoracic Surgery, Oxford Heart Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Mario Petrou
- Cardiothoracic Surgery, Oxford Heart Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Rana Sayeed
- Cardiothoracic Surgery, Oxford Heart Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Andrea Roalfe
- Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK
| | - Keith M Channon
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, L6, West Wing, Oxford OX3 9DU, UK
| | - Yaver Bashir
- Cardiology, Oxford Heart Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Timothy Betts
- Cardiology, Oxford Heart Centre, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Michael Hill
- Clinical Trial Service Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK
| | - Barbara Casadei
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, L6, West Wing, Oxford OX3 9DU, UK
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Heikal L, Starr A, Hussein D, Prieto-Lloret J, Aaronson P, Dailey LA, Nandi M. l-Phenylalanine Restores Vascular Function in Spontaneously Hypertensive Rats Through Activation of the GCH1-GFRP Complex. JACC Basic Transl Sci 2018; 3:366-377. [PMID: 29963647 PMCID: PMC6018612 DOI: 10.1016/j.jacbts.2018.01.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 10/27/2017] [Accepted: 01/24/2018] [Indexed: 12/11/2022]
Abstract
Tetrahydrobiopterin is an essential cofactor for NO production. Limitation of endogenous tetrahydrobiopterin reduces NO bioavailability, enhances oxidative stress, and impairs vascular function. Orally supplemented tetrahydrobiopterin has therapeutic challenges because it is rapidly oxidized in vivo. Here, the authors demonstrate that l-phenylalanine, when administered orally, raises vascular tetrahydrobiopterin, restores NO, reduces superoxide, and enhances vascular function in spontaneously hypertensive rats. This effect is achieved by activation of a protein complex (GCH1-GFRP) involved in the biosynthesis of tetrahydrobiopterin. Activation of this protein complex by l-phenylalanine or its analogues represents a novel therapeutic target for vascular disorders underpinned by reduced NO bioavailability.
Reduced nitric oxide (NO) bioavailability correlates with impaired cardiovascular function. NO is extremely labile and has been challenging to develop as a therapeutic agent. However, NO bioavailability could be enhanced by pharmacologically targeting endogenous NO regulatory pathways. Tetrahydrobiopterin, an essential cofactor for NO production, is synthesized by GTP cyclohydrolase-1 (GCH1), which complexes with GCH1 feedback regulatory protein (GFRP). The dietary amino acid l-phenylalanine activates this complex, elevating vascular BH4. Here, the authors demonstrate that l-phenylalanine administration restores vascular function in a rodent model of hypertension, suggesting the GCH1-GFRP complex represents a rational therapeutic target for diseases underpinned by endothelial dysfunction.
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Key Words
- ACh, acetylcholine
- ANOVA, analysis of variance
- BH2, dihydrobiopterin
- BH4, tetrahydrobiopterin
- EC50, effective concentration for 50% maximal response
- EDHF, endothelium derived hyperpolarizing factor
- GCH1, GTP cyclohydrolase-1
- GFRP, GCH1 feedback regulatory protein
- L-phe, l-phenylalanine
- L-tyr, l-tyrosine
- NO, nitric oxide
- ROS, reactive oxygen species
- SHR, spontaneously hypertensive rat(s)
- WKY, Wistar Kyoto rat(s)
- cardiovascular disease
- eNOS, endothelial nitric oxide synthase
- endothelium
- l-phenylalanine
- nitric oxide
- tetrahydrobiopterin
- vascular activity
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Affiliation(s)
- Lamia Heikal
- Institute of Pharmaceutical Sciences, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Anna Starr
- Institute of Pharmaceutical Sciences, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Dania Hussein
- Institute of Pharmaceutical Sciences, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Jesus Prieto-Lloret
- Division of Asthma, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Phil Aaronson
- Division of Asthma, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Lea Ann Dailey
- Institute of Pharmaceutical Sciences, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
| | - Manasi Nandi
- Institute of Pharmaceutical Sciences, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom.,Cardiovascular Division, Faculty of Life Sciences and Medicine, King's College London, London, United Kingdom
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Strasser B, Sperner-Unterweger B, Fuchs D, Gostner JM. Mechanisms of Inflammation-Associated Depression: Immune Influences on Tryptophan and Phenylalanine Metabolisms. Curr Top Behav Neurosci 2016; 31:95-115. [PMID: 27278641 DOI: 10.1007/7854_2016_23] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Metabolic parameters have a direct role in the regulation of immune cell function. Thereby the inflammation-induced metabolism of aromatic amino acids, most importantly of tryptophan and phenylalanine, plays a central role. In addition, neuropsychiatric conditions that go along with disorders that are characterized by acute or chronic inflammation, such as the development of depression, decreased quality of life or cognitive impairments, are connected to disturbed amino acid and subsequent neurotransmitter metabolism.The bioanalytical procedures for the determination of concentrations of tryptophan and phenylalanine and their respective first stable intermediates kynurenine and tyrosine as well as some analytical finesses and potential sources of errors are discussed in this chapter. Monitoring of these immunometabolic parameters throughout therapies in addition to biomarkers of immune response and inflammation such as neopterin can be useful to determine disease progression but also to plan psychiatric interventions timely, thus to establish personalized treatments.
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Affiliation(s)
- Barbara Strasser
- Division of Medical Biochemistry, Biocenter, Innsbruck Medical University, Innsbruck, Austria
| | | | - Dietmar Fuchs
- Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Innrain 80, Innsbruck, Austria.
| | - Johanna M Gostner
- Division of Medical Biochemistry, Biocenter, Innsbruck Medical University, Innsbruck, Austria
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5
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Hussein D, Starr A, Heikal L, McNeill E, Channon KM, Brown PR, Sutton BJ, McDonnell JM, Nandi M. Validating the GTP-cyclohydrolase 1-feedback regulatory complex as a therapeutic target using biophysical and in vivo approaches. Br J Pharmacol 2015; 172:4146-57. [PMID: 26014146 PMCID: PMC4543619 DOI: 10.1111/bph.13202] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 05/12/2015] [Accepted: 05/13/2015] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND AND PURPOSE 6R-L-erythro-5,6,7,8-tetrahydrobiopterin (BH4 ) is an essential cofactor for nitric oxide biosynthesis. Substantial clinical evidence indicates that intravenous BH4 restores vascular function in patients. Unfortunately, oral BH4 has limited efficacy. Therefore, orally bioavailable pharmacological activators of endogenous BH4 biosynthesis hold significant therapeutic potential. GTP-cyclohydrolase 1 (GCH1), the rate limiting enzyme in BH4 synthesis, forms a protein complex with GCH1 feedback regulatory protein (GFRP). This complex is subject to allosteric feed-forward activation by L-phenylalanine (L-phe). We investigated the effects of L-phe on the biophysical interactions of GCH1 and GFRP and its potential to alter BH4 levels in vivo. EXPERIMENTAL APPROACH Detailed characterization of GCH1-GFRP protein-protein interactions were performed using surface plasmon resonance (SPR) with or without L-phe. Effects on systemic and vascular BH4 biosynthesis in vivo were investigated following L-phe treatment (100 mg·kg(-1) , p.o.). KEY RESULTS GCH1 and GFRP proteins interacted in the absence of known ligands or substrate but the presence of L-phe doubled maximal binding and enhanced binding affinity eightfold. Furthermore, the complex displayed very slow association and dissociation rates. In vivo, L-phe challenge induced a sustained elevation of aortic BH4 , an effect absent in GCH1(fl/fl)-Tie2Cre mice. CONCLUSIONS AND IMPLICATIONS Biophysical data indicate that GCH1 and GFRP are constitutively bound. In vivo, data demonstrated that L-phe elevated vascular BH4 in an endothelial GCH1 dependent manner. Pharmacological agents which mimic the allosteric effects of L-phe on the GCH1-GFRP complex have the potential to elevate endothelial BH4 biosynthesis for numerous cardiovascular disorders.
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Affiliation(s)
- D Hussein
- Institute of Pharmaceutical Science, Faculty of Life Sciences & Medicine, King's College LondonLondon, UK
| | - A Starr
- Institute of Pharmaceutical Science, Faculty of Life Sciences & Medicine, King's College LondonLondon, UK
| | - L Heikal
- Institute of Pharmaceutical Science, Faculty of Life Sciences & Medicine, King's College LondonLondon, UK
| | - E McNeill
- British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, John Radcliffe HospitalOxford, UK
| | - K M Channon
- British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, John Radcliffe HospitalOxford, UK
| | - P R Brown
- The Randall Division of Cell and Molecular Biophysics, Faculty of Life Sciences & Medicine, King's College LondonLondon, UK
| | - B J Sutton
- The Randall Division of Cell and Molecular Biophysics, Faculty of Life Sciences & Medicine, King's College LondonLondon, UK
| | - J M McDonnell
- The Randall Division of Cell and Molecular Biophysics, Faculty of Life Sciences & Medicine, King's College LondonLondon, UK
| | - M Nandi
- Institute of Pharmaceutical Science, Faculty of Life Sciences & Medicine, King's College LondonLondon, UK
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Modulation of Radiation Response by the Tetrahydrobiopterin Pathway. Antioxidants (Basel) 2015; 4:68-81. [PMID: 26785338 PMCID: PMC4665563 DOI: 10.3390/antiox4010068] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 01/07/2015] [Accepted: 01/13/2015] [Indexed: 02/07/2023] Open
Abstract
Ionizing radiation (IR) is an integral component of our lives due to highly prevalent sources such as medical, environmental, and/or accidental. Thus, understanding of the mechanisms by which radiation toxicity develops is crucial to address acute and chronic health problems that occur following IR exposure. Immediate formation of IR-induced free radicals as well as their persistent effects on metabolism through subsequent alterations in redox mediated inter- and intracellular processes are globally accepted as significant contributors to early and late effects of IR exposure. This includes but is not limited to cytotoxicity, genomic instability, fibrosis and inflammation. Damage to the critical biomolecules leading to detrimental long-term alterations in metabolic redox homeostasis following IR exposure has been the focus of various independent investigations over last several decades. The growth of the "omics" technologies during the past decade has enabled integration of "data from traditional radiobiology research", with data from metabolomics studies. This review will focus on the role of tetrahydrobiopterin (BH4), an understudied redox-sensitive metabolite, plays in the pathogenesis of post-irradiation normal tissue injury as well as how the metabolomic readout of BH4 metabolism fits in the overall picture of disrupted oxidative metabolism following IR exposure.
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Starr A, Sand CA, Heikal L, Kelly PD, Spina D, Crabtree M, Channon KM, Leiper JM, Nandi M. Overexpression of GTP cyclohydrolase 1 feedback regulatory protein is protective in a murine model of septic shock. Shock 2014; 42:432-9. [PMID: 25046538 PMCID: PMC4851220 DOI: 10.1097/shk.0000000000000235] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 07/10/2014] [Indexed: 11/26/2022]
Abstract
Overproduction of nitric oxide (NO) by inducible NO synthase contributes toward refractory hypotension, impaired microvascular perfusion, and end-organ damage in septic shock patients. Tetrahydrobiopterin (BH4) is an essential NOS cofactor. GTP cyclohydrolase 1 (GCH1) is the rate-limiting enzyme for BH4 biosynthesis. Under inflammatory conditions, GCH1 activity and hence BH4 levels are increased, supporting pathological NOS activity. GCH1 activity can be controlled through allosteric interactions with GCH1 feedback regulatory protein (GFRP). We investigated whether overexpression of GFRP can regulate BH4 and NO production and attenuate cardiovascular dysfunction in sepsis. Sepsis was induced in mice conditionally overexpressing GFRP and wild-type littermates by cecal ligation and puncture. Blood pressure was monitored by radiotelemetry, and mesenteric blood flow was quantified by laser speckle contrast imaging. Blood biochemistry data were obtained using an iSTAT analyzer, and BH4 levels were measured in plasma and tissues by high-performance liquid chromatography. Increased BH4 and NO production and hypotension were observed in all mice, but the extents of these pathophysiological changes were attenuated in GFRP OE mice. Perturbations in blood biochemistry were similarly attenuated in GFRP OE compared with wild-type controls. These results suggest that GFRP overexpression regulates GCH1 activity during septic shock, which in turn limits BH4 bioavailability for iNOS. We conclude that the GCH1-GFRP axis is a critical regulator of BH4 and NO production and the cardiovascular derangements that occur in septic shock.
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Affiliation(s)
- Anna Starr
- *Pharmacology and Therapeutics Group, Institute of Pharmaceutical Science, School of Biomedical Sciences, King’s College London; and MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College London, London; and British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Claire A. Sand
- *Pharmacology and Therapeutics Group, Institute of Pharmaceutical Science, School of Biomedical Sciences, King’s College London; and MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College London, London; and British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Lamia Heikal
- *Pharmacology and Therapeutics Group, Institute of Pharmaceutical Science, School of Biomedical Sciences, King’s College London; and MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College London, London; and British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Peter D. Kelly
- *Pharmacology and Therapeutics Group, Institute of Pharmaceutical Science, School of Biomedical Sciences, King’s College London; and MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College London, London; and British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Domenico Spina
- *Pharmacology and Therapeutics Group, Institute of Pharmaceutical Science, School of Biomedical Sciences, King’s College London; and MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College London, London; and British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Mark Crabtree
- *Pharmacology and Therapeutics Group, Institute of Pharmaceutical Science, School of Biomedical Sciences, King’s College London; and MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College London, London; and British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Keith M. Channon
- *Pharmacology and Therapeutics Group, Institute of Pharmaceutical Science, School of Biomedical Sciences, King’s College London; and MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College London, London; and British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - James M. Leiper
- *Pharmacology and Therapeutics Group, Institute of Pharmaceutical Science, School of Biomedical Sciences, King’s College London; and MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College London, London; and British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Manasi Nandi
- *Pharmacology and Therapeutics Group, Institute of Pharmaceutical Science, School of Biomedical Sciences, King’s College London; and MRC Clinical Sciences Centre, Faculty of Medicine, Imperial College London, London; and British Heart Foundation Centre of Research Excellence, Division of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
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Pathak R, Pawar SA, Fu Q, Gupta PK, Berbée M, Garg S, Sridharan V, Wang W, Biju PG, Krager KJ, Boerma M, Ghosh SP, Cheema AK, Hendrickson HP, Aykin-Burns N, Hauer-Jensen M. Characterization of transgenic Gfrp knock-in mice: implications for tetrahydrobiopterin in modulation of normal tissue radiation responses. Antioxid Redox Signal 2014; 20:1436-46. [PMID: 23521531 PMCID: PMC3936502 DOI: 10.1089/ars.2012.5025] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2012] [Revised: 02/22/2013] [Accepted: 03/22/2013] [Indexed: 01/17/2023]
Abstract
AIMS The free radical scavenger and nitric oxide synthase cofactor, 5,6,7,8-tetrahydrobiopterin (BH4), plays a well-documented role in many disorders associated with oxidative stress, including normal tissue radiation responses. Radiation exposure is associated with decreased BH4 levels, while BH4 supplementation attenuates aspects of radiation toxicity. The endogenous synthesis of BH4 is catalyzed by the enzyme guanosine triphosphate cyclohydrolase I (GTPCH1), which is regulated by the inhibitory GTP cyclohydrolase I feedback regulatory protein (GFRP). We here report and characterize a novel, Cre-Lox-driven, transgenic mouse model that overexpresses Gfrp. RESULTS Compared to control littermates, transgenic mice exhibited high transgene copy numbers, increased Gfrp mRNA and GFRP expression, enhanced GFRP-GTPCH1 interaction, reduced BH4 levels, and low glutathione (GSH) levels and differential mitochondrial bioenergetic profiles. After exposure to total body irradiation, transgenic mice showed decreased BH4/7,8-dihydrobiopterin ratios, increased vascular oxidative stress, and reduced white blood cell counts compared with controls. INNOVATION AND CONCLUSION This novel Gfrp knock-in transgenic mouse model allows elucidation of the role of GFRP in the regulation of BH4 biosynthesis. This model is a valuable tool to study the involvement of BH4 in whole body and tissue-specific radiation responses and other conditions associated with oxidative stress.
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Affiliation(s)
- Rupak Pathak
- Division of Radiation Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Snehalata A. Pawar
- Division of Radiation Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Qiang Fu
- Division of Radiation Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Prem K. Gupta
- Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Maaike Berbée
- Division of Radiation Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Sarita Garg
- Division of Radiation Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Vijayalakshmi Sridharan
- Division of Radiation Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Wenze Wang
- Division of Radiation Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Prabath G. Biju
- Division of Radiation Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Kimberly J. Krager
- Division of Radiation Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Marjan Boerma
- Division of Radiation Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Sanchita P. Ghosh
- Armed Forces Radiobiology Research Institute, Uniformed Services University of the Health Sciences, Bethesda, Maryland
| | - Amrita K. Cheema
- Department of Oncology, Georgetown University Medical Center, Washington, District of Columbia
| | - Howard P. Hendrickson
- Department of Pharmaceutical Sciences, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Nukhet Aykin-Burns
- Division of Radiation Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas
| | - Martin Hauer-Jensen
- Division of Radiation Health, University of Arkansas for Medical Sciences, Little Rock, Arkansas
- Surgical Service, Central Arkansas Veterans Healthcare System, Little Rock, Arkansas
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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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Nandi M, Kelly P, Torondel B, Wang Z, Starr A, Ma Y, Cunningham P, Stidwill R, Leiper J. Genetic and pharmacological inhibition of dimethylarginine dimethylaminohydrolase 1 is protective in endotoxic shock. Arterioscler Thromb Vasc Biol 2012; 32:2589-97. [PMID: 22995517 DOI: 10.1161/atvbaha.112.300232] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
OBJECTIVE The overproduction of vascular NO contributes toward the circulatory collapse observed in patients with septic shock. Dimethylarginine dimethylaminohydrolase (DDAH), which has 2 isoforms, metabolizes asymmetrically methylated arginines (asymmetric mono- or di-methylarginine), endogenously produced NO synthase inhibitors. We wished to investigate whether reducing DDAH1 activity, using genetic and pharmacological approaches, is protective during lipopolysaccharide-induced endotoxic shock. METHODS AND RESULTS Experiments were conducted in DDAH1 heterozygous knockout mice (DDAH1(+/-)) or naive rats treated with a synthetic pharmacological DDAH inhibitor (L-257). We demonstrate for the first time that L-257 is DDAH1 selective using recombinant human DDAH proteins. DDAH1 mRNA was expressed in aortic but not macrophage cDNA, and consistent with this expression profile, L-257 selectively inhibited NO production from lipopolysaccharide-treated aorta but not macrophages, in culture. Conscious and anesthetized cardiovascular hemodynamics were monitored using implanted radiotelemetry devices or invasive catheters, respectively. Lipopolysaccharide was administered intravenously to model endotoxemia, and all animals presented with circulatory shock. DDAH1(+/-) mice or L-257-treated rats displayed attenuation in the rate of developed hypotension compared with wild-type littermates or vehicle control animals, respectively. CONCLUSIONS Pharmacological and genetic reduction of DDAH1 activity is protective against the vascular changes observed during endotoxic shock.
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Affiliation(s)
- Manasi Nandi
- Pharmacology and Therapeutics Group, Institute of Pharmaceutical Science, School of Biomedical Sciences, King's College London, Franklin-Wilkins Bldg, 150 Stamford St, London SE1 9NH, UK.
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11
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Belik J, McIntyre BAS, Enomoto M, Pan J, Grasemann H, Vasquez-Vivar J. Pulmonary hypertension in the newborn GTP cyclohydrolase I-deficient mouse. Free Radic Biol Med 2011; 51:2227-33. [PMID: 21982896 PMCID: PMC5050525 DOI: 10.1016/j.freeradbiomed.2011.09.012] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 09/10/2011] [Accepted: 09/13/2011] [Indexed: 11/30/2022]
Abstract
Tetrahydrobiopterin (BH4) is a regulator of endothelial nitric oxide synthase (eNOS) activity. Deficient levels result in eNOS uncoupling, with a shift from nitric oxide to superoxide generation. The hph-1 mutant mouse has deficient GTP cyclohydrolase I (GTPCH1) activity, resulting in low BH4 tissue content. The adult hph-1 mouse has pulmonary hypertension, but whether such condition is present from birth is not known. Thus, we evaluated newborn animals' pulmonary arterial medial thickness, biopterin content (BH4+BH2), H(2)O(2) and eNOS, right ventricle-to-left ventricle+septum (RV/LV+septum) ratio, near-resistance pulmonary artery agonist-induced force, and endothelium-dependent and -independent relaxation. The lung biopterin content was inversely related to age for both types, but significantly lower in hph-1 mice, compared to wild-type animals. As judged by the RV/LV+septum ratio, newborn hph-1 mice have pulmonary hypertension and, after a 2-week 13% oxygen exposure, the ratios were similar in both types. The pulmonary arterial agonist-induced force was reduced (P<0.01) in hph-1 animals and no type-dependent difference in endothelium-dependent or -independent vasorelaxation was observed. Compared to wild-type mice, the lung H(2)O(2) content was increased, whereas the eNOS expression was decreased (P<0.01) in hph-1 animals. The pulmonary arterial medial thickness, a surrogate marker of vascular remodeling, was increased (P<0.01) in hph-1 compared to wild-type mice. In conclusion, our data suggest that pulmonary hypertension is present from birth in the GTPCH1-deficient mice, not as a result of impaired vasodilation, but secondary to vascular remodeling.
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Affiliation(s)
- Jaques Belik
- Department of Paediatrics, The Hospital for Sick Children Research Institute, University of Toronto, Toronto, ON M5G 1X8, Canada.
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12
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Abstract
BH4 (6R-L-erythro-5,6,7,8-tetrahydrobiopterin) is an essential cofactor of a set of enzymes that are of central metabolic importance, including four aromatic amino acid hydroxylases, alkylglycerol mono-oxygenase and three NOS (NO synthase) isoenzymes. Consequently, BH4 is present in probably every cell or tissue of higher organisms and plays a key role in a number of biological processes and pathological states associated with monoamine neurotransmitter formation, cardiovascular and endothelial dysfunction, the immune response and pain sensitivity. BH4 is formed de novo from GTP via a sequence of three enzymatic steps carried out by GTP cyclohydrolase I, 6-pyruvoyltetrahydropterin synthase and sepiapterin reductase. An alternative or salvage pathway involves dihydrofolate reductase and may play an essential role in peripheral tissues. Cofactor regeneration requires pterin-4a-carbinolamine dehydratase and dihydropteridine reductase, except for NOSs, in which the BH4 cofactor undergoes a one-electron redox cycle without the need for additional regeneration enzymes. With regard to the regulation of cofactor biosynthesis, the major controlling point is GTP cyclohydrolase I. BH4 biosynthesis is controlled in mammals by hormones and cytokines. BH4 deficiency due to autosomal recessive mutations in all enzymes, except for sepiapterin reductase, has been described as a cause of hyperphenylalaninaemia. A major contributor to vascular dysfunction associated with hypertension, ischaemic reperfusion injury, diabetes and others, appears to be an effect of oxidized BH4, which leads to an increased formation of oxygen-derived radicals instead of NO by decoupled NOS. Furthermore, several neurological diseases have been suggested to be a consequence of restricted cofactor availability, and oral cofactor replacement therapy to stabilize mutant phenylalanine hydroxylase in the BH4-responsive type of hyperphenylalaninaemia has an advantageous effect on pathological phenylalanine levels in patients.
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Affiliation(s)
- Ernst R Werner
- Division of Biological Chemistry, Biocenter, Innsbruck Medical University, Innsbruck A-6020, Austria
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13
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Li L, Rezvan A, Salerno JC, Husain A, Kwon K, Jo H, Harrison DG, Chen W. GTP cyclohydrolase I phosphorylation and interaction with GTP cyclohydrolase feedback regulatory protein provide novel regulation of endothelial tetrahydrobiopterin and nitric oxide. Circ Res 2010; 106:328-36. [PMID: 19926872 PMCID: PMC2818799 DOI: 10.1161/circresaha.109.210658] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
RATIONALE GTP cyclohydrolase I (GTPCH-1) is the rate-limiting enzyme involved in de novo biosynthesis of tetrahydrobiopterin (BH(4)), an essential cofactor for NO synthases and aromatic amino acid hydroxylases. GTPCH-1 undergoes negative feedback regulation by its end-product BH(4) via interaction with the GTP cyclohydrolase feedback regulatory protein (GFRP). Such a negative feedback mechanism should maintain cellular BH(4) levels within a very narrow range; however, we recently identified a phosphorylation site (S81) on human GTPCH-1 that markedly increases BH(4) production in response to laminar shear. OBJECTIVE We sought to define how S81 phosphorylation alters GTPCH-1 enzyme activity and how this is modulated by GFRP. METHODS AND RESULTS Using prokaryotically expressed proteins, we found that the GTPCH-1 phospho-mimetic mutant (S81D) has increased enzyme activity, reduced binding to GFRP and resistance to inhibition by GFRP compared to wild-type GTPCH-1. Using small interfering RNA or overexpressing plasmids, GFRP was shown to modulate phosphorylation of GTPCH-1, BH(4) levels, and NO production in human endothelial cells. Laminar, but not oscillatory shear stress, caused dissociation of GTPCH-1 and GFRP, promoting GTPCH-1 phosphorylation. We also found that both GTPCH-1 phosphorylation and GFRP downregulation prevents endothelial NO synthase uncoupling in response to oscillatory shear. Finally oscillatory shear was associated with impaired GTPCH-1 phosphorylation and reduced BH(4) levels in vivo. CONCLUSIONS These studies provide a new mechanism for regulation of endothelial GTPCH-1 by its phosphorylation and interplay with GFRP. This mechanism allows for escape from GFRP negative feedback and permits large amounts of BH(4) to be produced in response to laminar shear stress.
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Affiliation(s)
- Li Li
- Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322
- Graduate Program of Molecular and Systems Pharmacology, Emory University School of Medicine, Atlanta, GA 30322
| | - Amir Rezvan
- Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322
| | - John C. Salerno
- Department of Biology and Physics, Kennesaw State University, Kennesaw, GA 30144
| | - Ahsan Husain
- Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322
| | - Kihwan Kwon
- Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322
| | - Hanjoong Jo
- Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322
- Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, Decatur, GA 30033
| | - David G. Harrison
- Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322
- Graduate Program of Molecular and Systems Pharmacology, Emory University School of Medicine, Atlanta, GA 30322
- Atlanta Veterans Administration Hospital, Decatur, GA 30033
| | - Wei Chen
- Division of Cardiology, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322
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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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