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Lombardi P, Karadayian AG, Guerra JI, Bustamante J, Rodríguez de Lores Arnaiz G, Lores-Arnaiz S. Mitochondrial bioenergetics and cytometric characterization of a synaptosomal preparation from mouse brain cortex. Mitochondrion 2023; 73:95-107. [PMID: 37944836 DOI: 10.1016/j.mito.2023.10.002] [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: 12/30/2022] [Revised: 09/06/2023] [Accepted: 10/28/2023] [Indexed: 11/12/2023]
Abstract
Mitochondrial function at synapses can be assessed in isolated nerve terminals. Synaptosomes are structures obtained in vitro by detaching the nerve endings from neuronal bodies under controlled homogenization conditions. Several protocols have been described for the preparation of intact synaptosomal fractions. Herein a fast and economical method to obtain synaptosomes with optimal intrasynaptic mitochondria functionality was described. Synaptosomal fractions were obtained from mouse brain cortex by differential centrifugation followed by centrifugation in a Ficoll gradient. The characteristics of the subcellular particles obtained were analyzed by flow cytometry employing specific tools. Integrity and specificity of the obtained organelles were evaluated by calcein and SNAP-25 probes. The proportion of positive events of the synaptosomal preparation was 75 ± 2 % and 48 ± 7% for calcein and Synaptosomal-Associated Protein of 25 kDa (SNAP-25), respectively. Mitochondrial integrity was evaluated by flow cytometric analysis of cardiolipin content, which indicated that 73 ± 1% of the total events were 10 N-nonylacridine orange (NAO)-positive. Oxygen consumption, ATP production and mitochondrial membrane potential determinations showed that mitochondria inside synaptosomes remained functional after the isolation procedure. Mitochondrial and synaptosomal enrichment were determined by measuring synaptosomes/ homogenate ratio of specific markers. Functionality of synaptosomes was verified by nitric oxide detection after glutamate addition. As compared with other methods, the present protocol can be performed briefly, does not imply high economic costs, and provides an useful tool for the isolation of a synaptosomal preparation with high mitochondrial respiratory capacity and an adequate integrity and function of intraterminal mitochondria.
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Affiliation(s)
- Paulina Lombardi
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Fisicoquímica, Buenos Aires, Argentina; CONICET- Universidad de Buenos Aires, Instituto de Bioquímica y Medicina Molecular "Profesor Alberto Boveris" (IBIMOL), Buenos Aires, Argentina
| | - Analía G Karadayian
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Fisicoquímica, Buenos Aires, Argentina; CONICET- Universidad de Buenos Aires, Instituto de Bioquímica y Medicina Molecular "Profesor Alberto Boveris" (IBIMOL), Buenos Aires, Argentina
| | - Juan I Guerra
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Fisicoquímica, Buenos Aires, Argentina; CONICET- Universidad de Buenos Aires, Instituto de Bioquímica y Medicina Molecular "Profesor Alberto Boveris" (IBIMOL), Buenos Aires, Argentina
| | | | - Georgina Rodríguez de Lores Arnaiz
- Universidad de Buenos Aires, Facultad de Medicina, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Biología Celular y Neurociencias "Profesor Eduardo De Robertis" (IBCN), Buenos Aires, Argentina
| | - Silvia Lores-Arnaiz
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Fisicoquímica, Buenos Aires, Argentina; CONICET- Universidad de Buenos Aires, Instituto de Bioquímica y Medicina Molecular "Profesor Alberto Boveris" (IBIMOL), Buenos Aires, Argentina.
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Jang S, Javadov S. Unraveling the mechanisms of cardiolipin function: The role of oxidative polymerization of unsaturated acyl chains. Redox Biol 2023; 64:102774. [PMID: 37300954 PMCID: PMC10363451 DOI: 10.1016/j.redox.2023.102774] [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: 04/20/2023] [Revised: 05/26/2023] [Accepted: 06/03/2023] [Indexed: 06/12/2023] Open
Abstract
Cardiolipin is a unique phospholipid of the inner mitochondrial membrane (IMM) as well as in bacteria. It performs several vital functions such as resisting osmotic rupture and stabilizing the supramolecular structure of large membrane proteins, like ATP synthases and respirasomes. The process of cardiolipin biosynthesis results in the production of immature cardiolipin. A subsequent step is required for its maturation when its acyl groups are replaced with unsaturated acyl chains, primarily linoleic acid. Linoleic acid is the major fatty acid of cardiolipin across all organs and tissues, except for the brain. Linoleic acid is not synthesized by mammalian cells. It has the unique ability to undergo oxidative polymerization at a moderately accelerated rate compared to other unsaturated fatty acids. This property can enable cardiolipin to form covalently bonded net-like structures essential for maintaining the complex geometry of the IMM and gluing the quaternary structure of large IMM protein complexes. Unlike triglycerides, phospholipids possess only two covalently linked acyl chains, which constrain their capacity to develop robust and complicated structures through oxidative polymerization of unsaturated acyl chains. Cardiolipin, on the other hand, has four fatty acids at its disposal to form covalently bonded polymer structures. Despite its significance, the oxidative polymerization of cardiolipin has been overlooked due to the negative perception surrounding biological oxidation and methodological difficulties. Here, we discuss an intriguing hypothesis that oxidative polymerization of cardiolipin is essential for the structure and function of cardiolipin in the IMM in physiological conditions. In addition, we highlight current challenges associated with the identification and characterization of oxidative polymerization of cardiolipin in vivo. Altogether, the study provides a better understanding of the structural and functional role of cardiolipin in mitochondria.
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Affiliation(s)
- Sehwan Jang
- Department of Physiology, University of Puerto Rico School of Medicine, San Juan, PR 00936-5067, USA
| | - Sabzali Javadov
- Department of Physiology, University of Puerto Rico School of Medicine, San Juan, PR 00936-5067, USA.
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Homeostasis of carbohydrates and reactive oxygen species is critically changed in the brain of middle-aged mice: molecular mechanisms and functional reasons. BBA ADVANCES 2023; 3:100077. [PMID: 37082254 PMCID: PMC10074963 DOI: 10.1016/j.bbadva.2023.100077] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 01/19/2023] [Accepted: 01/19/2023] [Indexed: 01/23/2023] Open
Abstract
The brain is an organ that consumes a lot of energy. In the brain, energy is required for synaptic transmission, numerous biosynthetic processes and axonal transport in neurons, and for many supportive functions of glial cells. The main source of energy in the brain is glucose and to a lesser extent lactate and ketone bodies. ATP is formed at glucose catabolism via glycolysis and oxidative phosphorylation in mitochondrial electron transport chain (ETC) within mitochondria being the main source of ATP. With age, brain's energy metabolism is disturbed, involving a decrease in glycolysis and mitochondrial dysfunction. The latter is accompanied by intensified generation of reactive oxygen species (ROS) in ETC leading to oxidative stress. Recently, we have found that crucial changes in energy metabolism and intensity of oxidative stress in the mouse brain occur in middle age with minor progression in old age. In this review, we analyze the metabolic changes and functional causes that lead to these changes in the aging brain.
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Jiang Z, Shen T, Huynh H, Fang X, Han Z, Ouyang K. Cardiolipin Regulates Mitochondrial Ultrastructure and Function in Mammalian Cells. Genes (Basel) 2022; 13:genes13101889. [PMID: 36292774 PMCID: PMC9601307 DOI: 10.3390/genes13101889] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Revised: 10/13/2022] [Accepted: 10/14/2022] [Indexed: 12/01/2022] Open
Abstract
Cardiolipin (CL) is a unique, tetra-acylated diphosphatidylglycerol lipid that mainly localizes in the inner mitochondria membrane (IMM) in mammalian cells and plays a central role in regulating mitochondrial architecture and functioning. A deficiency of CL biosynthesis and remodeling perturbs mitochondrial functioning and ultrastructure. Clinical and experimental studies on human patients and animal models have also provided compelling evidence that an abnormal CL content, acyl chain composition, localization, and level of oxidation may be directly linked to multiple diseases, including cardiomyopathy, neuronal dysfunction, immune cell defects, and metabolic disorders. The central role of CL in regulating the pathogenesis and progression of these diseases has attracted increasing attention in recent years. In this review, we focus on the advances in our understanding of the physiological roles of CL biosynthesis and remodeling from human patients and mouse models, and we provide an overview of the potential mechanism by which CL regulates the mitochondrial architecture and functioning.
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Affiliation(s)
- Zhitong Jiang
- Department of Cardiovascular Surgery, Peking University Shenzhen Hospital, Shenzhen 518055, China
| | - Tao Shen
- Department of Cardiovascular Surgery, Peking University Shenzhen Hospital, Shenzhen 518055, China
| | - Helen Huynh
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, San Diego, CA 92093, USA
| | - Xi Fang
- Department of Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, San Diego, CA 92093, USA
| | - Zhen Han
- Department of Cardiovascular Surgery, Peking University Shenzhen Hospital, Shenzhen 518055, China
- Correspondence: (Z.H.); (K.O.)
| | - Kunfu Ouyang
- Department of Cardiovascular Surgery, Peking University Shenzhen Hospital, Shenzhen 518055, China
- Correspondence: (Z.H.); (K.O.)
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Falabella M, Vernon HJ, Hanna MG, Claypool SM, Pitceathly RDS. Cardiolipin, Mitochondria, and Neurological Disease. Trends Endocrinol Metab 2021; 32:224-237. [PMID: 33640250 PMCID: PMC8277580 DOI: 10.1016/j.tem.2021.01.006] [Citation(s) in RCA: 106] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 01/26/2021] [Accepted: 01/27/2021] [Indexed: 02/07/2023]
Abstract
Over the past decade, it has become clear that lipid homeostasis is central to cellular metabolism. Lipids are particularly abundant in the central nervous system (CNS) where they modulate membrane fluidity, electric signal transduction, and synaptic stabilization. Abnormal lipid profiles reported in Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and traumatic brain injury (TBI), are further support for the importance of lipid metablism in the nervous system. Cardiolipin (CL), a mitochondria-exclusive phospholipid, has recently emerged as a focus of neurodegenerative disease research. Aberrant CL content, structure, and localization are linked to impaired neurogenesis and neuronal dysfunction, contributing to aging and the pathogenesis of several neurodegenerative diseases, such as AD and PD. Furthermore, the highly tissue-specific acyl chain composition of CL confers it significant potential as a biomarker to diagnose and monitor the progression in several neurological diseases. CL also represents a potential target for pharmacological strategies aimed at treating neurodegeneration. Given the equipoise that currently exists between CL metabolism, mitochondrial function, and neurological disease, we review the role of CL in nervous system physiology and monogenic and neurodegenerative disease pathophysiology, in addition to its potential application as a biomarker and pharmacological target.
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Affiliation(s)
- Micol Falabella
- Department of Neuromuscular Diseases, University College London Queen Square Institute of Neurology, London, UK
| | - Hilary J Vernon
- Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Michael G Hanna
- Department of Neuromuscular Diseases, University College London Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, UK
| | - Steven M Claypool
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Robert D S Pitceathly
- Department of Neuromuscular Diseases, University College London Queen Square Institute of Neurology and The National Hospital for Neurology and Neurosurgery, London, UK.
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Olesen MA, Torres AK, Jara C, Murphy MP, Tapia-Rojas C. Premature synaptic mitochondrial dysfunction in the hippocampus during aging contributes to memory loss. Redox Biol 2020; 34:101558. [PMID: 32447261 PMCID: PMC7248293 DOI: 10.1016/j.redox.2020.101558] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 04/22/2020] [Accepted: 04/27/2020] [Indexed: 12/18/2022] Open
Abstract
Aging is a process characterized by cognitive impairment and mitochondrial dysfunction. In neurons, these organelles are classified as synaptic and non-synaptic mitochondria depending on their localization. Interestingly, synaptic mitochondria from the cerebral cortex accumulate more damage and are more sensitive to swelling than non-synaptic mitochondria. The hippocampus is fundamental for learning and memory, synaptic processes with high energy demand. However, it is unknown if functional differences are found in synaptic and non-synaptic hippocampal mitochondria; and whether this could contribute to memory loss during aging. In this study, we used 3, 6, 12 and 18 month-old (mo) mice to evaluate hippocampal memory and the function of both synaptic and non-synaptic mitochondria. Our results indicate that recognition memory is impaired from 12mo, whereas spatial memory is impaired at 18mo. This was accompanied by a differential function of synaptic and non-synaptic mitochondria. Interestingly, we observed premature dysfunction of synaptic mitochondria at 12mo, indicated by increased ROS generation, reduced ATP production and higher sensitivity to calcium overload, an effect that is not observed in non-synaptic mitochondria. In addition, at 18mo both mitochondrial populations showed bioenergetic defects, but synaptic mitochondria were prone to swelling than non-synaptic mitochondria. Finally, we treated 2, 11, and 17mo mice with MitoQ or Curcumin (Cc) for 5 weeks, to determine if the prevention of synaptic mitochondrial dysfunction could attenuate memory loss. Our results indicate that reducing synaptic mitochondrial dysfunction is sufficient to decrease age-associated cognitive impairment. In conclusion, our results indicate that age-related alterations in ATP produced by synaptic mitochondria are correlated with decreases in spatial and object recognition memory and propose that the maintenance of functional synaptic mitochondria is critical to prevent memory loss during aging. Hippocampus-dependent learning and memory are impaired with age, which correlated with synaptic mitochondrial dysfunction. Synaptic mitochondria fail before non-synaptic mitochondria, indicating premature synaptic mitochondrial damage in aging. Reducing synaptic mitochondrial dysfunction, with MitoQ or Curcumin, decrease age-associated hippocampal memory impairment. Age-related changes in ATP production of synaptic mitochondria correlated with decreased hippocampal memory. Maintenance of functional synaptic mitochondria is critical to prevent memory loss during aging.
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Affiliation(s)
- Margrethe A Olesen
- Laboratory of Neurobiology of Aging, Centro de Biología Celular y Biomedicina (CEBICEM), Universidad San Sebastián, Chile
| | - Angie K Torres
- Laboratory of Neurobiology of Aging, Centro de Biología Celular y Biomedicina (CEBICEM), Universidad San Sebastián, Chile
| | - Claudia Jara
- Laboratory of Neurobiology of Aging, Centro de Biología Celular y Biomedicina (CEBICEM), Universidad San Sebastián, Chile
| | - Michael P Murphy
- Medical Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Cheril Tapia-Rojas
- Laboratory of Neurobiology of Aging, Centro de Biología Celular y Biomedicina (CEBICEM), Universidad San Sebastián, Chile.
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Acaz-Fonseca E, Ortiz-Rodriguez A, Garcia-Segura LM, Astiz M. Sex differences and gonadal hormone regulation of brain cardiolipin, a key mitochondrial phospholipid. J Neuroendocrinol 2020; 32:e12774. [PMID: 31323169 DOI: 10.1111/jne.12774] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Revised: 06/14/2019] [Accepted: 07/15/2019] [Indexed: 12/14/2022]
Abstract
Cardiolipin (CL) is a phospholipid that is almost exclusively located in the inner mitochondrial membrane of eukaryotic cells. As a result of its unique structure and distribution, CL establishes non-covalent bonds with a long list of proteins involved in ATP production, mitochondria biogenesis, mitophagy and apoptosis. Thus, the amount of CL, as well as its fatty acid composition and location, strongly impacts upon mitochondrial-dependent functions and therefore the metabolic homeostasis of different tissues. The brain is particularly sensitive to mitochondrial dysfunction as a result of its high metabolic demand. Several mitochondrial related-neurodegenerative disorders, as well as physiological ageing, show altered CL metabolism. Furthermore, mice lacking enzymes involved in CL synthesis show cognitive impairments. CL content and metabolism are regulated by gonadal hormones in the developing and adult brain. In neuronal cultures, oestradiol increases CL content, whereas adult ovariectomy decreases CL content and alters CL metabolism in the hippocampal mitochondria. Transient sex differences in brain CL metabolism have been detected during development. At birth, brain CL has a higher proportion of unsaturated fatty acids in the brain of male mice than in the brain of females. In addition, the expression of enzymes involved in CL de novo and recycling synthetic pathways is higher in males. Most of these sex differences are abolished by the neonatal androgenisation of females, suggesting a role for testosterone in the generation of sex differences in brain CL. The regulation of brain CL by gonadal hormones may be linked to their homeostatic and protective actions in neural cells, as well as the manifestation of sex differences in neurodegenerative disorders.
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Affiliation(s)
- Estefania Acaz-Fonseca
- Instituto Cajal-CSIC, Madrid, Spain
- Centro de Investigación Biomédica en Red Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| | | | - Luis Miguel Garcia-Segura
- Instituto Cajal-CSIC, Madrid, Spain
- Centro de Investigación Biomédica en Red Fragilidad y Envejecimiento Saludable (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| | - Mariana Astiz
- Institute of Neurobiology, Center of Brain Behavior and Metabolism (CBBM), University of Lübeck, Lübeck, Germany
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