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Gnaiger E. Complex II ambiguities-FADH 2 in the electron transfer system. J Biol Chem 2024; 300:105470. [PMID: 38118236 PMCID: PMC10772739 DOI: 10.1016/j.jbc.2023.105470] [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: 07/03/2023] [Revised: 11/01/2023] [Accepted: 11/06/2023] [Indexed: 12/22/2023] Open
Abstract
The prevailing notion that reduced cofactors NADH and FADH2 transfer electrons from the tricarboxylic acid cycle to the mitochondrial electron transfer system creates ambiguities regarding respiratory Complex II (CII). CII is the only membrane-bound enzyme in the tricarboxylic acid cycle and is part of the electron transfer system of the mitochondrial inner membrane feeding electrons into the coenzyme Q-junction. The succinate dehydrogenase subunit SDHA of CII oxidizes succinate and reduces the covalently bound prosthetic group FAD to FADH2 in the canonical forward tricarboxylic acid cycle. However, several graphical representations of the electron transfer system depict FADH2 in the mitochondrial matrix as a substrate to be oxidized by CII. This leads to the false conclusion that FADH2 from the β-oxidation cycle in fatty acid oxidation feeds electrons into CII. In reality, dehydrogenases of fatty acid oxidation channel electrons to the Q-junction but not through CII. The ambiguities surrounding Complex II in the literature and educational resources call for quality control, to secure scientific standards in current communications of bioenergetics, and ultimately support adequate clinical applications. This review aims to raise awareness of the inherent ambiguity crisis, complementing efforts to address the well-acknowledged issues of credibility and reproducibility.
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Monzel AS, Enríquez JA, Picard M. Multifaceted mitochondria: moving mitochondrial science beyond function and dysfunction. Nat Metab 2023; 5:546-562. [PMID: 37100996 PMCID: PMC10427836 DOI: 10.1038/s42255-023-00783-1] [Citation(s) in RCA: 105] [Impact Index Per Article: 105.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 03/10/2023] [Indexed: 04/28/2023]
Abstract
Mitochondria have cell-type specific phenotypes, perform dozens of interconnected functions and undergo dynamic and often reversible physiological recalibrations. Given their multifunctional and malleable nature, the frequently used terms 'mitochondrial function' and 'mitochondrial dysfunction' are misleading misnomers that fail to capture the complexity of mitochondrial biology. To increase the conceptual and experimental specificity in mitochondrial science, we propose a terminology system that distinguishes between (1) cell-dependent properties, (2) molecular features, (3) activities, (4) functions and (5) behaviours. A hierarchical terminology system that accurately captures the multifaceted nature of mitochondria will achieve three important outcomes. It will convey a more holistic picture of mitochondria as we teach the next generations of mitochondrial biologists, maximize progress in the rapidly expanding field of mitochondrial science, and also facilitate synergy with other disciplines. Improving specificity in the language around mitochondrial science is a step towards refining our understanding of the mechanisms by which this unique family of organelles contributes to cellular and organismal health.
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Affiliation(s)
- Anna S Monzel
- Department of Psychiatry, Division of Behavioral Medicine, Columbia University Irving Medical Center, New York, NY, USA
| | - José Antonio Enríquez
- Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain
- CIBER de Fragilidad y Envejecimiento Saludable (CIBERFES), Madrid, Spain
| | - Martin Picard
- Department of Psychiatry, Division of Behavioral Medicine, Columbia University Irving Medical Center, New York, NY, USA.
- Department of Neurology, H. Houston Merritt Center, Columbia Translational Neuroscience Initiative, Columbia University Irving Medical Center, New York, NY, USA.
- New York State Psychiatric Institute, New York, NY, USA.
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Turton N, Millichap L, Hargreaves IP. Potential Biomarkers of Mitochondrial Dysfunction Associated with COVID-19 Infection. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1412:211-224. [PMID: 37378769 DOI: 10.1007/978-3-031-28012-2_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/29/2023]
Abstract
Mitochondria play crucial roles in modulating immune responses, and viruses can in turn moderate mitochondrial functioning. Therefore, it is not judicious to assume that clinical outcome experienced in patients with COVID-19 or long COVID may be influenced by mitochondrial dysfunction in this infection. Also, patients who are predisposed to mitochondrial respiratory chain (MRC) disorders may be more susceptible to worsened clinical outcome associated with COVID-19 infection and long COVID. MRC disorders and dysfunction require a multidisciplinary approach for their diagnosis of which blood and urinary metabolite analysis may be utilized, including the measurement of lactate, organic acid and amino acid levels. More recently, hormone-like cytokines including fibroblast growth factor-21 (FGF-21) have also been used to assess possible evidence of MRC dysfunction. In view of their association with MRC dysfunction, assessing evidence of oxidative stress parameters including GSH and coenzyme Q10 (CoQ10) status may also provide useful biomarkers for diagnosis of MRC dysfunction. To date, the most reliable biomarker available for assessing MRC dysfunction is the spectrophotometric determination of MRC enzyme activities in skeletal muscle or tissue from the disease-presenting organ. Moreover, the combined use of these biomarkers in a multiplexed targeted metabolic profiling strategy may further improve the diagnostic yield of the individual tests for assessing evidence of mitochondrial dysfunction in patients pre- and post-COVID-19 infection.
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Affiliation(s)
- Nadia Turton
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, UK
| | | | - Iain P Hargreaves
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, UK.
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Turton N, Cufflin N, Dewsbury M, Fitzpatrick O, Islam R, Watler LL, McPartland C, Whitelaw S, Connor C, Morris C, Fang J, Gartland O, Holt L, Hargreaves IP. The Biochemical Assessment of Mitochondrial Respiratory Chain Disorders. Int J Mol Sci 2022; 23:ijms23137487. [PMID: 35806492 PMCID: PMC9267223 DOI: 10.3390/ijms23137487] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 07/03/2022] [Accepted: 07/04/2022] [Indexed: 12/10/2022] Open
Abstract
Mitochondrial respiratory chain (MRC) disorders are a complex group of diseases whose diagnosis requires a multidisciplinary approach in which the biochemical investigations play an important role. Initial investigations include metabolite analysis in both blood and urine and the measurement of lactate, pyruvate and amino acid levels, as well as urine organic acids. Recently, hormone-like cytokines, such as fibroblast growth factor-21 (FGF-21), have also been used as a means of assessing evidence of MRC dysfunction, although work is still required to confirm their diagnostic utility and reliability. The assessment of evidence of oxidative stress may also be an important parameter to consider in the diagnosis of MRC function in view of its association with mitochondrial dysfunction. At present, due to the lack of reliable biomarkers available for assessing evidence of MRC dysfunction, the spectrophotometric determination of MRC enzyme activities in skeletal muscle or tissue from the disease-presenting organ is considered the ‘Gold Standard’ biochemical method to provide evidence of MRC dysfunction. The purpose of this review is to outline a number of biochemical methods that may provide diagnostic evidence of MRC dysfunction in patients.
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Affiliation(s)
- Nadia Turton
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Neve Cufflin
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Mollie Dewsbury
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Olivia Fitzpatrick
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Rahida Islam
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Lowidka Linares Watler
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Cara McPartland
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Sophie Whitelaw
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Caitlin Connor
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Charlotte Morris
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Jason Fang
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Ollie Gartland
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Liv Holt
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
| | - Iain P Hargreaves
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
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Yao D, Su R, Zhang Y, Wang B, Hou Y, Luo Y, Sun L, Guo Y, Jin Y. Impact of dietary Lactobacillus supplementation on intramuscular fat deposition and meat quality of Sunit sheep. J Food Biochem 2022; 46:e14207. [PMID: 35502134 DOI: 10.1111/jfbc.14207] [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: 12/01/2021] [Revised: 03/29/2022] [Accepted: 04/05/2022] [Indexed: 12/01/2022]
Abstract
To investigate the impacts of dietary Lactobacillus supplementation on meat quality such as edible quality and nutritional value of Sunit sheep, a 90-day feeding experiment (Lactobacillus dietary group, R group; non-Lactobacillus dietary group, C group) using twelve 3-month-old Sunit sheep was conducted. The deposition of intramuscular fat (IMF) was increased (p < .05) while the share force and cooking loss were decreased (p < .05) in the R group compared with the C group. The proportions of seven kinds of fatty acids (FAs) have changed significantly (p < .05), especially with higher functional FAs and lower trans-FA in the R group. Metabonomics analysis showed that the metabolites and pathway-related lipid syntheses, such as carnitine cycle, tricarboxylic acid cycle, and glycerophosphocholine metabolic pathway, have significantly changed in the R group. The Lactobacillus dietary supplements impacted the variation of IMF deposition and FAs composition by altering the lipid metabolism pathways of Sunit sheep and then changed the edible quality and nutritional value. PRACTICAL APPLICATIONS: It is well known that the intramuscular fat (IMF) and fatty acids composition in livestock is positively correlated with various aspects of meat quality such as edible quality and nutritional value, which are related to consumer preference. The present study analyzed the effects of Lactobacillus supplement on the intramuscular fat deposition and meat quality of Sunit sheep, which resulted in the increase of IMF, and the differences of fatty acids composition, especially the functional fatty acids. It was explored the mechanism of Lactobacillus affect the variation of lipid metabolism pathways and key metabolites in sheep, which suggested that altering the feeding regimen could improve the meat quality of agri-animals.
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Affiliation(s)
- Duo Yao
- College of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot, China.,Inner Mongolia Institute of Quality and Standardization, Inner Mongolia Administration for Market Regulation, Hohhot, China
| | - Rina Su
- College of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot, China
| | - Yue Zhang
- College of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot, China
| | - Bohui Wang
- College of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot, China
| | - Yanru Hou
- College of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot, China
| | - Yulong Luo
- College of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot, China
| | - Lina Sun
- College of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot, China
| | - Yueying Guo
- College of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot, China
| | - Ye Jin
- College of Food Science and Engineering, Inner Mongolia Agricultural University, Hohhot, China
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