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Serrano-Marín J, Marin S, Bernal-Casas D, Lillo A, González-Subías M, Navarro G, Cascante M, Sánchez-Navés J, Franco R. A metabolomics study in aqueous humor discloses altered arginine metabolism in Parkinson's disease. Fluids Barriers CNS 2023; 20:90. [PMID: 38049870 PMCID: PMC10696737 DOI: 10.1186/s12987-023-00494-5] [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: 07/27/2023] [Accepted: 11/23/2023] [Indexed: 12/06/2023] Open
Abstract
BACKGROUND The lack of accessible and informative biomarkers results in a delayed diagnosis of Parkinson's disease (PD), whose symptoms appear when a significant number of dopaminergic neurons have already disappeared. The retina, a historically overlooked part of the central nervous system (CNS), has gained recent attention. It has been discovered that the composition of cerebrospinal fluid influences the aqueous humor composition through microfluidic circulation. In addition, alterations found in the brain of patients with PD have a correlate in the retina. This new paradigm highlights the potential of the aqueous humor as a sample for identifying differentially concentrated metabolites that could, eventually, become biomarkers if also found altered in blood or CSF of patients. In this research we aim at analyzing the composition of the aqueous humor from healthy controls and PD patients. METHODS A targeted metabolomics approach with concentration determination by mass spectrometry was used. Statistical methods including principal component analysis and linear discriminants were used to select differentially concentrated metabolites that allow distinguishing patients from controls. RESULTS In this first metabolomics study in the aqueous humor of PD patients, elevated levels of 16 compounds were found; molecules differentially concentrated grouped into biogenic amines, amino acids, and acylcarnitines. A biogenic amine, putrescine, alone could be a metabolite capable of differentiating between PD and control samples. The altered levels of the metabolites were correlated, suggesting that the elevations stem from a common mechanism involving arginine metabolism. CONCLUSIONS A combination of three metabolites, putrescine, tyrosine, and carnitine was able to correctly classify healthy participants from PD patients. Altered metabolite levels suggest altered arginine metabolism. The pattern of metabolomic disturbances was not due to the levodopa-based dopamine replacement medication because one of the patients was not yet taking levodopa but a dopamine receptor agonist.
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Affiliation(s)
- Joan Serrano-Marín
- Department of Biochemistry and Molecular Biomedicine, Universitat de Barcelona, Barcelona, Spain
| | - Silvia Marin
- Department of Biochemistry and Molecular Biomedicine, Universitat de Barcelona, Barcelona, Spain
- Institute of Biomedicine of University of Barcelona (IBUB), University of Barcelona (UB), Barcelona, 08028, Spain
- CIBEREHD. Network Center for Hepatic and Digestive Diseases, National Spanish Health Institute Carlos III (ISCIII), Madrid, 28029, Spain
| | - David Bernal-Casas
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, Universitat de Barcelona (UB), Barcelona, 08028, Spain
| | - Alejandro Lillo
- Department of Biochemistry and Physiology, Universitat de Barcelona, Barcelona, Spain
| | - Marc González-Subías
- Department of Biochemistry and Molecular Biomedicine, Universitat de Barcelona, Barcelona, Spain
| | - Gemma Navarro
- Department of Biochemistry and Physiology, Universitat de Barcelona, Barcelona, Spain
- CiberNed. Network Center for Biomedical Research in Neurodegenerative Diseases., Spanish National Health Institute Carlos iii, Av. Monforte de Lemos, 3-5, Madrid, 28029, Spain
| | - Marta Cascante
- Department of Biochemistry and Molecular Biomedicine, Universitat de Barcelona, Barcelona, Spain
- Institute of Biomedicine of University of Barcelona (IBUB), University of Barcelona (UB), Barcelona, 08028, Spain
- CIBEREHD. Network Center for Hepatic and Digestive Diseases, National Spanish Health Institute Carlos III (ISCIII), Madrid, 28029, Spain
| | - Juan Sánchez-Navés
- Department of Ophthalmology, Ophthalmedic and I.P.O. Institute of Ophthalmology, Palma de Mallorca, Spain
| | - Rafael Franco
- Department of Biochemistry and Molecular Biomedicine, Universitat de Barcelona, Barcelona, Spain.
- CiberNed. Network Center for Biomedical Research in Neurodegenerative Diseases., Spanish National Health Institute Carlos iii, Av. Monforte de Lemos, 3-5, Madrid, 28029, Spain.
- School of Chemistry, Universitat de Barcelona, Barcelona, Spain.
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Franco R, Serrano-Marín J. The unbroken Krebs cycle. Hormonal-like regulation and mitochondrial signaling to control mitophagy and prevent cell death. Bioessays 2023; 45:e2200194. [PMID: 36549872 DOI: 10.1002/bies.202200194] [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: 10/07/2022] [Revised: 12/04/2022] [Accepted: 12/08/2022] [Indexed: 12/24/2022]
Abstract
The tricarboxylic acid (TCA) or Krebs cycle, which takes place in prokaryotic cells and in the mitochondria of eukaryotic cells, is central to life on Earth and participates in key events such as energy production and anabolic processes. Despite its relevance, it is not perceived as tightly regulated compared to other key metabolisms such as glycolysis/gluconeogenesis. A better understanding of the functioning of the TCA cycle is crucial due to mitochondrial function impairment in several diseases, especially those that occur with neurodegeneration. This article revisits what is known about the regulation of the Krebs cycle and hypothesizes the need for large-scale, rapid regulation of TCA cycle enzyme activity. Evidence of mitochondrial enzyme activity regulation by activation/deactivation of protein kinases and phosphatases exists in the literature. Apart from indirect regulation via G protein-coupled receptors (GPCRs) at the cell surface, signaling upon activation of GPCRs in mitochondrial membranes may lead to a direct regulation of the enzymes of the Krebs cycle. Hormonal-like regulation by posttranscriptional events mediated by activable kinases and phosphatases deserve proper assessment using isolated mitochondria. Also see the video abstract here: https://youtu.be/aBpDSWiMQyI.
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Affiliation(s)
- Rafael Franco
- CiberNed, Network Center for Neurodegenerative Diseases, National Spanish Health Institute Carlos III, Madrid, Spain.,Molecular Neurobiology Laboratory, Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Universitat de Barcelona, Barcelona, Spain.,School of Chemistry, Universitat de Barcelona, Barcelona, Spain
| | - Joan Serrano-Marín
- Molecular Neurobiology Laboratory, Department of Biochemistry and Molecular Biomedicine, Faculty of Biology, Universitat de Barcelona, Barcelona, Spain
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