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Hanaford AR, Khanna A, James K, Truong V, Liao R, Chen Y, Mulholland M, Kayser EB, Watanabe K, Hsieh ES, Sedensky M, Morgan PG, Kalia V, Sarkar S, Johnson SC. Interferon-gamma contributes to disease progression in the Ndufs4(-/-) model of Leigh syndrome. Neuropathol Appl Neurobiol 2024; 50:e12977. [PMID: 38680020 DOI: 10.1111/nan.12977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 03/19/2024] [Accepted: 03/20/2024] [Indexed: 05/01/2024]
Abstract
AIM Leigh syndrome (LS), the most common paediatric presentation of genetic mitochondrial dysfunction, is a multi-system disorder characterised by severe neurologic and metabolic abnormalities. Symmetric, bilateral, progressive necrotizing lesions in the brainstem are defining features of the disease. Patients are often symptom free in early life but typically develop symptoms by about 2 years of age. The mechanisms underlying disease onset and progression in LS remain obscure. Recent studies have shown that the immune system causally drives disease in the Ndufs4(-/-) mouse model of LS: treatment of Ndufs4(-/-) mice with the macrophage-depleting Csf1r inhibitor pexidartinib prevents disease. While the precise mechanisms leading to immune activation and immune factors involved in disease progression have not yet been determined, interferon-gamma (IFNγ) and interferon gamma-induced protein 10 (IP10) were found to be significantly elevated in Ndufs4(-/-) brainstem, implicating these factors in disease. Here, we aimed to explore the role of IFNγ and IP10 in LS. METHODS To establish the role of IFNγ and IP10 in LS, we generated IFNγ and IP10 deficient Ndufs4(-/-)/Ifng(-/-) and Ndufs4(-/-)/IP10(-/-) double knockout animals, as well as IFNγ and IP10 heterozygous, Ndufs4(-/-)/Ifng(+/-) and Ndufs4(-/-)/IP10(+/-), animals. We monitored disease onset and progression to define the impact of heterozygous or homozygous loss of IFNγ and IP10 in LS. RESULTS Loss of IP10 does not significantly impact the onset or progression of disease in the Ndufs4(-/-) model. IFNγ loss significantly extends survival and delays disease progression in a gene dosage-dependent manner, though the benefits are modest compared to Csf1r inhibition. CONCLUSIONS IFNγ contributes to disease onset and progression in LS. Our findings suggest that IFNγ targeting therapies may provide some benefits in genetic mitochondrial disease, but targeting IFNγ alone would likely yield only modest benefits in LS.
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Affiliation(s)
- Allison R Hanaford
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Asheema Khanna
- Ben Towne Center for Childhood Cancer Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Katerina James
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Vivian Truong
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Ryan Liao
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Yihan Chen
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Michael Mulholland
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Ernst-Bernhard Kayser
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Kino Watanabe
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Erin Shien Hsieh
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Margaret Sedensky
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
- Department of Anaesthesiology and Pain Medicine, University of Washington, Seattle, Washington, USA
| | - Philip G Morgan
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
- Department of Anaesthesiology and Pain Medicine, University of Washington, Seattle, Washington, USA
| | - Vandana Kalia
- Ben Towne Center for Childhood Cancer Research, Seattle Children's Research Institute, Seattle, Washington, USA
- Department of Paediatrics, University of Washington School of Medicine, Seattle, Washington, USA
| | - Surojit Sarkar
- Ben Towne Center for Childhood Cancer Research, Seattle Children's Research Institute, Seattle, Washington, USA
- Department of Paediatrics, University of Washington School of Medicine, Seattle, Washington, USA
| | - Simon C Johnson
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
- Department of Anaesthesiology and Pain Medicine, University of Washington, Seattle, Washington, USA
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, USA
- Department of Neurology, University of Washington, Seattle, Washington, USA
- Department of Applied Sciences, Translational Bioscience, Northumbria University, Newcastle upon Tyne, UK
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Spencer KA, Howe MN, Mulholland MT, Truong V, Liao RW, Chen Y, Setha M, Snell JC, Hanaford A, James K, Morgan PG, Sedensky MM, Johnson SC. Impact of dietary ketosis on volatile anesthesia toxicity in a model of Leigh syndrome. Paediatr Anaesth 2024; 34:467-476. [PMID: 38358320 DOI: 10.1111/pan.14855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 01/24/2024] [Accepted: 02/01/2024] [Indexed: 02/16/2024]
Abstract
BACKGROUND Genetic mitochondrial diseases impact over 1 in 4000 individuals, most often presenting in infancy or early childhood. Seizures are major clinical sequelae in some mitochondrial diseases including Leigh syndrome, the most common pediatric presentation of mitochondrial disease. Dietary ketosis has been used to manage seizures in mitochondrial disease patients. Mitochondrial disease patients often require surgical interventions, leading to anesthetic exposures. Anesthetics have been shown to be toxic in the setting of mitochondrial disease, but the impact of a ketogenic diet on anesthetic toxicities in this setting has not been studied. AIMS Our aim in this study was to determine whether dietary ketosis impacts volatile anesthetic toxicities in the setting of genetic mitochondrial disease. METHODS The impact of dietary ketosis on toxicities of volatile anesthetic exposure in mitochondrial disease was studied by exposing young Ndufs4(-/-) mice fed ketogenic or control diet to isoflurane anesthesia. Blood metabolites were measured before and at the end of exposures, and survival and weight were monitored. RESULTS Compared to a regular diet, the ketogenic diet exacerbated hyperlactatemia resulting from isoflurane exposure (control vs. ketogenic diet in anesthesia mean difference 1.96 mM, Tukey's multiple comparison adjusted p = .0271) and was associated with a significant increase in mortality during and immediately after exposures (27% vs. 87.5% mortality in the control and ketogenic diet groups, respectively, during the exposure period, Fisher's exact test p = .0121). Our data indicate that dietary ketosis and volatile anesthesia interact negatively in the setting of mitochondrial disease. CONCLUSIONS Our findings suggest that extra caution should be taken in the anesthetic management of mitochondrial disease patients in dietary ketosis.
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Affiliation(s)
- Kira A Spencer
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
- Center for Child Health, Behavior and Development, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Miranda N Howe
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Michael T Mulholland
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
- Department of Applied Sciences, Translational Bioscience, Northumbria University, Newcastle, UK
| | - Vivian Truong
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
- Department of Applied Sciences, Translational Bioscience, Northumbria University, Newcastle, UK
| | - Ryan W Liao
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Yihan Chen
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Monyreak Setha
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - John C Snell
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Allison Hanaford
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Katerina James
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
| | - Philip G Morgan
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, Washington, USA
| | - Margaret M Sedensky
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, Washington, USA
| | - Simon C Johnson
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA
- Department of Applied Sciences, Translational Bioscience, Northumbria University, Newcastle, UK
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, Washington, USA
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, USA
- Department of Neurology, University of Washington, Seattle, Washington, USA
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Woods CB, Predoi B, Howe M, Reczek CR, Kayser EB, Ramirez JM, Morgan PG, Sedensky MM. Potassium Leak Channels and Mitochondrial Complex I Interact in Glutamatergic Interneurons of the Mouse Spinal Cord. Anesthesiology 2024; 140:715-728. [PMID: 38147628 PMCID: PMC10939847 DOI: 10.1097/aln.0000000000004891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2023]
Abstract
BACKGROUND Volatile anesthetics induce hyperpolarizing potassium currents in spinal cord neurons that may contribute to their mechanism of action. They are induced at lower concentrations of isoflurane in noncholinergic neurons from mice carrying a loss-of-function mutation of the Ndufs4 gene, required for mitochondrial complex I function. The yeast NADH dehydrogenase enzyme, NDi1, can restore mitochondrial function in the absence of normal complex I activity, and gain-of-function Ndi1 transgenic mice are resistant to volatile anesthetics. The authors tested whether NDi1 would reduce the hyperpolarization caused by isoflurane in neurons from Ndufs4 and wild-type mice. Since volatile anesthetic behavioral hypersensitivity in Ndufs4 is transduced uniquely by glutamatergic neurons, it was also tested whether these currents were also unique to glutamatergic neurons in the Ndufs4 spinal cord. METHODS Spinal cord neurons from wild-type, NDi1, and Ndufs4 mice were patch clamped to characterize isoflurane sensitive currents. Neuron types were marked using fluorescent markers for cholinergic, glutamatergic, and γ-aminobutyric acid-mediated (GABAergic) neurons. Norfluoxetine was used to identify potassium channel type. Neuron type-specific Ndufs4 knockout animals were generated using type-specific Cre-recombinase with floxed Ndufs4. RESULTS Resting membrane potentials (RMPs) of neurons from NDi1;Ndufs4, unlike those from Ndufs4, were not hyperpolarized by 0.6% isoflurane (Ndufs4, ΔRMP -8.2 mV [-10 to -6.6]; P = 1.3e-07; Ndi1;Ndufs4, ΔRMP -2.1 mV [-7.6 to +1.4]; P = 1). Neurons from NDi1 animals in a wild-type background were not hyperpolarized by 1.8% isoflurane (wild-type, ΔRMP, -5.2 mV [-7.3 to -3.2]; P = 0.00057; Ndi1, ΔRMP, 0.6 mV [-1.7 to 3.2]; P = 0.68). In spinal cord slices from global Ndufs4 animals, holding currents (HC) were induced by 0.6% isoflurane in both GABAergic (ΔHC, 81.3 pA [61.7 to 101.4]; P = 2.6e-05) and glutamatergic (ΔHC, 101.2 pA [63.0 to 146.2]; P = 0.0076) neurons. In neuron type-specific Ndufs4 knockouts, HCs were increased in cholinergic (ΔHC, 119.5 pA [82.3 to 156.7]; P = 0.00019) and trended toward increase in glutamatergic (ΔHC, 85.5 pA [49 to 126.9]; P = 0.064) neurons but not in GABAergic neurons. CONCLUSIONS Bypassing complex I by overexpression of NDi1 eliminates increases in potassium currents induced by isoflurane in the spinal cord. The isoflurane-induced potassium currents in glutamatergic neurons represent a potential downstream mechanism of complex I inhibition in determining minimum alveolar concentration. EDITOR’S PERSPECTIVE
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Affiliation(s)
- Christian B Woods
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, 98101, USA
| | - Beatrice Predoi
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, 98101, USA
| | - Miranda Howe
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, 98101, USA
| | - Colleen R Reczek
- Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Ernst-Bernhard Kayser
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, 98101, USA
| | - Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, 98101, USA
- Department of Neurological Surgery, University of Washington, Seattle, WA, 98105, USA
| | - Philip G Morgan
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, 98101, USA
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle WA, 98105, USA
| | - Margaret M Sedensky
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, 98101, USA
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle WA, 98105, USA
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O'Reilly-Shah VN, Van Cleve W, Walters A, Hunyady AI, Morgan PG, Li L, Polaner DM. Hyperammonemia is associated with reduced objective anesthetic requirements in children: A retrospective case-control study. Paediatr Anaesth 2024; 34:374-376. [PMID: 38226795 DOI: 10.1111/pan.14839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 12/28/2023] [Accepted: 01/02/2024] [Indexed: 01/17/2024]
Affiliation(s)
- Vikas N O'Reilly-Shah
- Department of Anesthesiology & Pain Medicine, University of Washington School of Medicine, Seattle, Washington, USA
| | - Wil Van Cleve
- Department of Anesthesiology & Pain Medicine, University of Washington School of Medicine, Seattle, Washington, USA
| | - Andrew Walters
- Department of Anesthesiology & Pain Medicine, University of Washington School of Medicine, Seattle, Washington, USA
| | - Agnes I Hunyady
- Department of Anesthesiology & Pain Medicine, University of Washington School of Medicine, Seattle, Washington, USA
| | - Philip G Morgan
- Department of Anesthesiology & Pain Medicine, University of Washington School of Medicine, Seattle, Washington, USA
| | - Li Li
- Department of Anesthesiology & Pain Medicine, University of Washington School of Medicine, Seattle, Washington, USA
| | - David M Polaner
- Department of Anesthesiology & Pain Medicine, University of Washington School of Medicine, Seattle, Washington, USA
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Spencer KA, Mulholland M, Snell J, Howe M, James K, Hanaford AR, Morgan PG, Sedensky M, Johnson SC. Volatile anaesthetic toxicity in the genetic mitochondrial disease Leigh syndrome. Br J Anaesth 2023; 131:832-846. [PMID: 37770252 PMCID: PMC10636522 DOI: 10.1016/j.bja.2023.08.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 07/16/2023] [Accepted: 08/07/2023] [Indexed: 09/30/2023] Open
Abstract
BACKGROUND Volatile anaesthetics are widely used in human medicine. Although generally safe, hypersensitivity and toxicity can occur in rare cases, such as in certain genetic disorders. Anaesthesia hypersensitivity is well-documented in a subset of mitochondrial diseases, but whether volatile anaesthetics are toxic in this setting has not been explored. METHODS We exposed Ndufs4(-/-) mice, a model of Leigh syndrome, to isoflurane (0.2-0.6%), oxygen 100%, or air. Cardiorespiratory function, weight, blood metabolites, and survival were assessed. We exposed post-symptom onset and pre-symptom onset animals and animals treated with the macrophage depleting drug PLX3397/pexidartinib to define the role of overt neuroinflammation in volatile anaesthetic toxicities. RESULTS Isoflurane induced hyperlactataemia, weight loss, and mortality in a concentration- and duration-dependent manner from 0.2% to 0.6% compared with carrier gas (O2 100%) or mock (air) exposures (lifespan after 30-min exposures ∗P<0.05 for isoflurane 0.4% vs air or vs O2, ∗∗P<0.005 for isoflurane 0.6% vs air or O2; 60-min exposures ∗∗P<0.005 for isoflurane 0.2% vs air, ∗P<0.05 for isoflurane 0.2% vs O2). Isoflurane toxicity was significantly reduced in Ndufs4(-/-) exposed before CNS disease onset, and the macrophage depleting drug pexidartinib attenuated sequelae of isoflurane toxicity (survival ∗∗∗P=0.0008 isoflurane 0.4% vs pexidartinib plus isoflurane 0.4%). Finally, the laboratory animal standard of care of 100% O2 as a carrier gas contributed significantly to weight loss and reduced survival, but not to metabolic changes, and increased acute mortality. CONCLUSIONS Isoflurane is toxic in the Ndufs4(-/-) model of Leigh syndrome. Toxic effects are dependent on the status of underlying neurologic disease, largely prevented by the CSF1R inhibitor pexidartinib, and influenced by oxygen concentration in the carrier gas.
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Affiliation(s)
- Kira A Spencer
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Anesthesiology and Pain Medicine, Seattle, WA, USA
| | - Michael Mulholland
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Applied Sciences, Translational Bioscience, Northumbria University, Newcastle, UK
| | - John Snell
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Miranda Howe
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Katerina James
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Applied Sciences, Translational Bioscience, Northumbria University, Newcastle, UK
| | - Allison R Hanaford
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Philip G Morgan
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Anesthesiology and Pain Medicine, Seattle, WA, USA
| | - Margaret Sedensky
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Anesthesiology and Pain Medicine, Seattle, WA, USA
| | - Simon C Johnson
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Anesthesiology and Pain Medicine, Seattle, WA, USA; Department of Applied Sciences, Translational Bioscience, Northumbria University, Newcastle, UK; Department of Laboratory Medicine and Pathology, Seattle, WA, USA; Department of Neurology, University of Washington, Seattle, WA, USA.
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Spencer KA, Woods CB, Worstman HM, Johnson SC, Ramirez JM, Morgan PG, Sedensky MM. TREK-1 and TREK-2 knockout mice are not resistant to halothane or isoflurane. Anesthesiology 2023:138071. [PMID: 37027798 DOI: 10.1097/aln.0000000000004577] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2023]
Abstract
BACKGROUND. A variety of molecular targets for volatile anesthetics have been suggested including the anesthetic-sensitive K+ leak channel, TREK-1. Knockout of TREK-1 is reported to render mice resistant to volatile anesthetics, making TREK-1 channels compelling targets for anesthetic action. Spinal cord slices from mice, either wildtype or an anesthetic-hypersensitive mutant, Ndufs4, display an isoflurane-induced outward K+ leak that correlates with their minimum alveolar concentrations (MAC) and is blocked by norfluoxetine. We hypothesized that TREK-1 channels conveyed this current and contribute to the anesthetic hypersensitivity of Ndufs4. Our results led to evaluation of a second TREK channel, TREK-2, in control of anesthetic sensitivity. METHODS. We measured anesthetic sensitivities of mice carrying knockout alleles of Trek-1 and Trek-2, the double knockout Trek-1;Trek-2, and Ndufs4;Trek-1. Neurons from spinal cord slices from each mutant were patch clamped to characterize isoflurane-sensitive currents. Norfluoxetine was used to identify TREK-dependent currents. RESULTS. We compared mean values for MAC (+/- SD) between wildtype and two Trek-1 knockout alleles in mice (p-values, Trek-1 compared to wildtype). Wildtype: (MAC(Hal), 1.30%(0.10); MAC(Iso), 1.40%(0.11): Trek-1tm1Lex (MAC(Hal), 1.27%(0.11); p=0.387; MAC(Iso), 1.38%(0.09); p=0.268): Trek-1tm1Lzd (MAC(Hal); 1.27%(0.11); p=0.482: MAC(Iso); 1.41%(0.12); p=0.188). Neither allele was resistant for loss of righting reflex. The EC50s of Ndufs4;Trek-1tm1Lex did not differ from Ndufs4. Ndufs4: (EC50(Hal), 0.65%(0.05); EC50 (Iso), 0.63%(0.05): Ndufs4;Trek-1tm1Lex (EC50(Hal), 0.58%(0.07); p=0.004; EC50(Iso); 0.61%(.06); p=0.442). Loss of TREK-2 did not alter anesthetic sensitivity in a wildtype or Trek-1 genetic background. Loss of TREK-1 or TREK-2, or both, did not alter the isoflurane-induced currents in wildtype cells but did cause them to be norfluoxetine-insensitive. CONCLUSIONS. Loss of TREK channels did not alter anesthetic sensitivity in mice, nor did it eliminate isoflurane-induced transmembrane currents. However, the isoflurane-induced currents are norfluoxetine-resistant in Trek mutants indicating that other channels may function in this role when TREK channels are deleted.
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Affiliation(s)
- Kira A Spencer
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, 98101, USA
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle WA, 98105, USA
| | - Christian B Woods
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, 98101, USA
| | - Hailey M Worstman
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, 98101, USA
| | - Simon C Johnson
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, 98101, USA
- Applied Sciences, Translational Biosciences, Northumbria University, Ellison A521A, UK (current)
| | - Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, 98101, USA
- Department of Neurological Surgery, University of Washington, Seattle, WA, 98105, USA
| | - Philip G Morgan
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, 98101, USA
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle WA, 98105, USA
| | - Margaret M Sedensky
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, 98101, USA
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle WA, 98105, USA
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Perouansky M, Johnson-Schlitz D, Sedensky MM, Morgan PG. A primordial target: Mitochondria mediate both primary and collateral anesthetic effects of volatile anesthetics. Exp Biol Med (Maywood) 2023; 248:545-552. [PMID: 37208922 PMCID: PMC10350799 DOI: 10.1177/15353702231165025] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/21/2023] Open
Abstract
One of the unsolved mysteries of medicine is how do volatile anesthetics (VAs) cause a patient to reversibly lose consciousness. In addition, identifying mechanisms for the collateral effects of VAs, including anesthetic-induced neurotoxicity (AiN) and anesthetic preconditioning (AP), has proven challenging. Multiple classes of molecules (lipids, proteins, and water) have been considered as potential VA targets, but recently proteins have received the most attention. Studies targeting neuronal receptors or ion channels had limited success in identifying the critical targets of VAs mediating either the phenotype of "anesthesia" or their collateral effects. Recent studies in both nematodes and fruit flies may provide a paradigm shift by suggesting that mitochondria may harbor the upstream molecular switch activating both primary and collateral effects. The disruption of a specific step of electron transfer within the mitochondrion causes hypersensitivity to VAs, from nematodes to Drosophila and to humans, while also modulating the sensitivity to collateral effects. The downstream effects from mitochondrial inhibition are potentially legion, but inhibition of presynaptic neurotransmitter cycling appears to be specifically sensitive to the mitochondrial effects. These findings are perhaps of even broader interest since two recent reports indicate that mitochondrial damage may well underlie neurotoxic and neuroprotective effects of VAs in the central nervous system (CNS). It is, therefore, important to understand how anesthetics interact with mitochondria to affect CNS function, not just for the desired facets of general anesthesia but also for significant collateral effects, both harmful and beneficial. A tantalizing possibility exists that both the primary (anesthesia) and secondary (AiN, AP) mechanisms may at least partially overlap in the mitochondrial electron transport chain (ETC).
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Affiliation(s)
- Misha Perouansky
- Department of Anesthesiology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53792, USA
- Laboratory of Genetics, School of Medicine and Public Health and College of Agricultural and Life Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Dena Johnson-Schlitz
- Department of Anesthesiology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53792, USA
| | - Margaret M Sedensky
- Department of Anesthesiology and Pain Medicine, University of Washington School of Medicine, Seattle, WA 98101, USA
| | - Philip G Morgan
- Department of Anesthesiology and Pain Medicine, University of Washington School of Medicine, Seattle, WA 98101, USA
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Jung S, Zimin PI, Woods CB, Kayser EB, Haddad D, Reczek CR, Nakamura K, Ramirez JM, Sedensky MM, Morgan PG. Isoflurane inhibition of endocytosis is an anesthetic mechanism of action. Curr Biol 2022; 32:3016-3032.e3. [PMID: 35688155 PMCID: PMC9329204 DOI: 10.1016/j.cub.2022.05.037] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 03/30/2022] [Accepted: 05/13/2022] [Indexed: 10/18/2022]
Abstract
The mechanisms of volatile anesthetic action remain among the most perplexing mysteries of medicine. Across phylogeny, volatile anesthetics selectively inhibit mitochondrial complex I, and they also depress presynaptic excitatory signaling. To explore how these effects are linked, we studied isoflurane effects on presynaptic vesicle cycling and ATP levels in hippocampal cultured neurons from wild-type and complex I mutant (Ndufs4(KO)) mice. To bypass complex I, we measured isoflurane effects on anesthetic sensitivity in mice expressing NADH dehydrogenase (NDi1). Endocytosis in physiologic concentrations of glucose was delayed by effective behavioral concentrations of isoflurane in both wild-type (τ [unexposed] 44.8 ± 24.2 s; τ [exposed] 116.1 ± 28.1 s; p < 0.01) and Ndufs4(KO) cultures (τ [unexposed] 67.6 ± 16.0 s; τ [exposed] 128.4 ± 42.9 s; p = 0.028). Increasing glucose, to enhance glycolysis and increase ATP production, led to maintenance of both ATP levels and endocytosis (τ [unexposed] 28.0 ± 14.4; τ [exposed] 38.2 ± 5.7; reducing glucose worsened ATP levels and depressed endocytosis (τ [unexposed] 85.4 ± 69.3; τ [exposed] > 1,000; p < 0.001). The block in recycling occurred at the level of reuptake of synaptic vesicles into the presynaptic cell. Expression of NDi1 in wild-type mice caused behavioral resistance to isoflurane for tail clamp response (EC50 Ndi1(-) 1.27% ± 0.14%; Ndi1(+) 1.55% ± 0.13%) and halothane (EC50 Ndi1(-) 1.20% ± 0.11%; Ndi1(+) 1.46% ± 0.10%); expression of NDi1 in neurons improved hippocampal function, alleviated inhibition of presynaptic recycling, and increased ATP levels during isoflurane exposure. The clear alignment of cell culture data to in vivo phenotypes of both isoflurane-sensitive and -resistant mice indicates that inhibition of mitochondrial complex I is a primary mechanism of action of volatile anesthetics.
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Affiliation(s)
- Sangwook Jung
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Pavel I Zimin
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA; Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA 98195, USA
| | - Christian B Woods
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Ernst-Bernhard Kayser
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Dominik Haddad
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA
| | - Colleen R Reczek
- Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Ken Nakamura
- Gladstone Institute of Neurological Disease, San Francisco, CA 94158, USA; Department of Neurology, University of California, San Francisco, CA 94158, USA
| | - Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA; Department of Neurological Surgery, University of Washington, Seattle, WA 98105, USA
| | - Margaret M Sedensky
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA; Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA 98195, USA
| | - Philip G Morgan
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA; Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA 98195, USA.
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9
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Stokes JC, Bornstein RL, James K, Park KY, Spencer KA, Vo K, Snell JC, Johnson BM, Morgan PG, Sedensky MM, Baertsch NA, Johnson SC. Leukocytes mediate disease pathogenesis in the Ndufs4(KO) mouse model of Leigh syndrome. JCI Insight 2022; 7:156522. [PMID: 35050903 PMCID: PMC8983133 DOI: 10.1172/jci.insight.156522] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 01/19/2022] [Indexed: 11/23/2022] Open
Abstract
Symmetric, progressive, necrotizing lesions in the brainstem are a defining feature of Leigh syndrome (LS). A mechanistic understanding of the pathogenesis of these lesions has been elusive. Here, we report that leukocyte proliferation is causally involved in the pathogenesis of LS. Depleting leukocytes with a colony-stimulating factor 1 receptor inhibitor disrupted disease progression, including suppression of CNS lesion formation and a substantial extension of survival. Leukocyte depletion rescued diverse symptoms, including seizures, respiratory center function, hyperlactemia, and neurologic sequelae. These data reveal a mechanistic explanation for the beneficial effects of mTOR inhibition. More importantly, these findings dramatically alter our understanding of the pathogenesis of LS, demonstrating that immune involvement is causal in disease. This work has important implications for the mechanisms of mitochondrial disease and may lead to novel therapeutic strategies.
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Affiliation(s)
- Julia C Stokes
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States of America
| | - Rebecca L Bornstein
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, United States of America
| | - Katerina James
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States of America
| | - Kyung Yeon Park
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States of America
| | - Kira A Spencer
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States of America
| | - Katie Vo
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States of America
| | - John C Snell
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States of America
| | - Brittany M Johnson
- Department of Neurology, University of Washington, Seattle, United States of America
| | - Philip G Morgan
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States of America
| | - Margaret M Sedensky
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States of America
| | - Nathan A Baertsch
- Department of Pediatrics, University of Washington, Seattle, United States of America
| | - Simon C Johnson
- Department of Neurology, University of Washington, Seattle, United States of America
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10
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Jung S, Kayser EB, Johnson SC, Li L, Worstman HM, Sun GX, Sedensky MM, Morgan PG. Tetraethylammonium chloride reduces anaesthetic-induced neurotoxicity in Caenorhabditis elegans and mice. Br J Anaesth 2022; 128:77-88. [PMID: 34857359 PMCID: PMC8787783 DOI: 10.1016/j.bja.2021.09.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/30/2021] [Accepted: 09/15/2021] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND If anaesthetics cause permanent cognitive deficits in some children, the implications are enormous, but the molecular causes of anaesthetic-induced neurotoxicity, and consequently possible therapies, are still debated. Anaesthetic exposure early in development can be neurotoxic in the invertebrate Caenorhabditis elegans causing endoplasmic reticulum (ER) stress and defects in chemotaxis during adulthood. We screened this model organism for compounds that alleviated neurotoxicity, and then tested these candidates for efficacy in mice. METHODS We screened compounds for alleviation of ER stress induction by isoflurane in C. elegans assayed by induction of a green fluorescent protein (GFP) reporter. Drugs that inhibited ER stress were screened for reduction of the anaesthetic-induced chemotaxis defect. Compounds that alleviated both aspects of neurotoxicity were then blindly tested for the ability to inhibit induction of caspase-3 by isoflurane in P7 mice. RESULTS Isoflurane increased ER stress indicated by increased GFP reporter fluorescence (240% increase, P<0.001). Nine compounds reduced induction of ER stress by isoflurane by 90-95% (P<0.001 in all cases). Of these compounds, tetraethylammonium chloride and trehalose also alleviated the isoflurane-induced defect in chemotaxis (trehalose by 44%, P=0.001; tetraethylammonium chloride by 23%, P<0.001). In mouse brain, tetraethylammonium chloride reduced isoflurane-induced caspase staining in the anterior cortical (-54%, P=0.007) and hippocampal regions (-46%, P=0.002). DISCUSSION Tetraethylammonium chloride alleviated isoflurane-induced neurotoxicity in two widely divergent species, raising the likelihood that it may have therapeutic value. In C. elegans, ER stress predicts isoflurane-induced neurotoxicity, but is not its cause.
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Affiliation(s)
- Sangwook Jung
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Ernst-Bernhard Kayser
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Simon C Johnson
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Anesthesiology and Pain Medicine, Seattle, WA, USA; Department of Neurology, University of Washington, Seattle, WA, USA
| | - Li Li
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Anesthesiology and Pain Medicine, Seattle, WA, USA
| | - Hailey M Worstman
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Grace X Sun
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - Margaret M Sedensky
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Anesthesiology and Pain Medicine, Seattle, WA, USA
| | - Philip G Morgan
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Anesthesiology and Pain Medicine, Seattle, WA, USA.
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11
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Yaster M, Flack SH, Martin LD, Morgan PG. An interview with Dr. Anne Marie Lynn, a pioneering woman in medicine. Paediatr Anaesth 2021; 31:1040-1045. [PMID: 34293231 DOI: 10.1111/pan.14258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 07/17/2021] [Indexed: 11/26/2022]
Abstract
Dr. Anne Marie Lynn (1949-present), Professor Emeritus of Anesthesiology, Pain Medicine, and Pediatrics at the University of Washington, Seattle, was one of the most influential women in pediatric anesthesiology of her generation. Dr. Lynn embodies the spirit of discovery and advancement that have created the practice of pediatric anesthesiology as we know it today. A pioneer in pain medicine pharmacology, particularly morphine and ketorolac, her research transformed pediatric anesthesia, pediatric pain medicine, and pediatric intensive care medicine. Through her journal articles, book chapters, national and international lectures, mentoring of residents, fellows, and faculty, and leadership in the Society for Pediatric Anesthesia, she inspired a generation of women and men physicians by demonstrating that gender should not be a barrier to undertaking roles once only held only by men. In 2017, for her many contributions, she was awarded the Society for Pediatric Anesthesia's Myron Yaster lifetime achievement award.
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Affiliation(s)
- Myron Yaster
- Departments of Anesthesiology, Critical Care Medicine and Pediatrics, The Johns Hopkins University, Baltimore, Maryland, USA
| | - Sean H Flack
- Department of Anesthesiology and Pain Medicine, Seattle Children's, University of Washington, Seattle, Washington, USA
| | - Lynn D Martin
- Department of Anesthesiology and Pain Medicine, Seattle Children's, University of Washington, Seattle, Washington, USA
| | - Philip G Morgan
- Department of Anesthesiology and Pain Medicine, Seattle Children's, University of Washington, Seattle, Washington, USA
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12
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Stokes J, Freed A, Bornstein R, Su KN, Snell J, Pan A, Sun GX, Park KY, Jung S, Worstman H, Johnson BM, Morgan PG, Sedensky MM, Johnson SC. Mechanisms underlying neonate-specific metabolic effects of volatile anesthetics. eLife 2021; 10:65400. [PMID: 34254587 PMCID: PMC8291971 DOI: 10.7554/elife.65400] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 07/12/2021] [Indexed: 12/15/2022] Open
Abstract
Volatile anesthetics (VAs) are widely used in medicine, but the mechanisms underlying their effects remain ill-defined. Though routine anesthesia is safe in healthy individuals, instances of sensitivity are well documented, and there has been significant concern regarding the impact of VAs on neonatal brain development. Evidence indicates that VAs have multiple targets, with anesthetic and non-anesthetic effects mediated by neuroreceptors, ion channels, and the mitochondrial electron transport chain. Here, we characterize an unexpected metabolic effect of VAs in neonatal mice. Neonatal blood β-hydroxybutarate (β-HB) is rapidly depleted by VAs at concentrations well below those necessary for anesthesia. β-HB in adults, including animals in dietary ketosis, is unaffected. Depletion of β-HB is mediated by citrate accumulation, malonyl-CoA production by acetyl-CoA carboxylase, and inhibition of fatty acid oxidation. Adults show similar significant changes to citrate and malonyl-CoA, but are insensitive to malonyl-CoA, displaying reduced metabolic flexibility compared to younger animals.
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Affiliation(s)
- Julia Stokes
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States
| | - Arielle Freed
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States.,University of Washington School of Dentistry, Seattle, United States
| | - Rebecca Bornstein
- Department of Pathology, University of Washington, Seattle, United States
| | - Kevin N Su
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, United States
| | - John Snell
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States
| | - Amanda Pan
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States
| | - Grace X Sun
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States
| | - Kyung Yeon Park
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States
| | - Sangwook Jung
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States
| | - Hailey Worstman
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States
| | - Brittany M Johnson
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States
| | - Philip G Morgan
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States.,Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, United States
| | - Margaret M Sedensky
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States.,Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, United States
| | - Simon C Johnson
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, United States.,Department of Pathology, University of Washington, Seattle, United States.,Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, United States.,Department of Neurology, University of Washington, Seattle, United States
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13
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Hsieh VC, Niezgoda J, Sedensky MM, Hoppel CL, Morgan PG. Anesthetic Hypersensitivity in a Case-Controlled Series of Patients With Mitochondrial Disease. Anesth Analg 2021; 133:924-932. [PMID: 33591116 DOI: 10.1213/ane.0000000000005430] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
BACKGROUND Children with mitochondrial disease undergo anesthesia for a wide array of surgical procedures. However, multiple medications used for their perioperative care can affect mitochondrial function. Defects in function of the mitochondrial electron transport chain (ETC) can lead to a profound hypersensitivity to sevoflurane in children. We studied the sensitivities to sevoflurane, during mask induction and maintenance of general anesthesia, in children presenting for muscle biopsies for diagnosis of mitochondrial disease. METHODS In this multicenter study, 91 children, aged 6 months to 16 years, presented to the operating room for diagnostic muscle biopsy for presumptive mitochondrial disease. General anesthesia was induced by a slow increase of inhaled sevoflurane concentration. The primary end point, end-tidal (ET) sevoflurane necessary to achieve a bispectral index (BIS) of 60, was recorded. Secondary end points were maximal sevoflurane used to maintain a BIS between 40 and 60 during the case, and maximum and minimum heart rate and blood pressures. After induction, general anesthesia was maintained according to the preferences of the providers directing the cases. Primary data were analyzed comparing data from patients with complex I deficiencies to other groups using nonparametric statistics in SPSS v.27. RESULTS The median sevoflurane concentration to reach BIS of 60 during inductions (ET sevoflurane % [BIS = 60]) was significantly lower for patients with complex I defects (0.98%; 95% confidence interval [CI], 0.5-1.4) compared to complex II (1.95%; 95% CI, 1.2-2.7; P < .001), complex III (2.0%; 95% CI, 0.7-3.5; P < .001), complex IV (2.0%; 95% CI, 1.7-3.2; P < .001), and normal groups (2.2%; 95% CI, 1.8-3.0; P < .001). The sevoflurane sensitivities of complex I patients did not reach significance when compared to patients diagnosed with mitochondrial disease but without an identifiable ETC abnormality (P = .172). Correlation of complex I activity with ET sevoflurane % (BIS = 60) gave a Spearman's coefficient of 0.505 (P < .001). The differences in sensitivities between groups were less during the maintenance of the anesthetic than during induction. CONCLUSIONS The data indicate that patients with complex I dysfunction are hypersensitive to sevoflurane compared to normal patients. Hypersensitivity was less common in patients presenting with other mitochondrial defects or without a mitochondrial diagnosis.
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Affiliation(s)
- Vincent C Hsieh
- From the Department of Anesthesiology and Perioperative Medicine, University of Washington and Seattle Children's Hospital, Seattle, Washington
| | - Julie Niezgoda
- Department of Pediatric Anesthesiology, Cleveland Clinic, Cleveland, Ohio
| | - Margaret M Sedensky
- From the Department of Anesthesiology and Perioperative Medicine, University of Washington and Seattle Children's Hospital, Seattle, Washington
| | - Charles L Hoppel
- Department of Pharmacology and Medicine, Case Western Reserve University, Cleveland, Ohio
| | - Philip G Morgan
- From the Department of Anesthesiology and Perioperative Medicine, University of Washington and Seattle Children's Hospital, Seattle, Washington
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14
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Johnson SC, Kayser EB, Bornstein R, Stokes J, Bitto A, Park KY, Pan A, Sun G, Raftery D, Kaeberlein M, Sedensky MM, Morgan PG. Regional metabolic signatures in the Ndufs4(KO) mouse brain implicate defective glutamate/α-ketoglutarate metabolism in mitochondrial disease. Mol Genet Metab 2020; 130:118-132. [PMID: 32331968 PMCID: PMC7272141 DOI: 10.1016/j.ymgme.2020.03.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Accepted: 03/29/2020] [Indexed: 02/08/2023]
Abstract
Leigh Syndrome (LS) is a mitochondrial disorder defined by progressive focal neurodegenerative lesions in specific regions of the brain. Defects in NDUFS4, a subunit of complex I of the mitochondrial electron transport chain, cause LS in humans; the Ndufs4 knockout mouse (Ndufs4(KO)) closely resembles the human disease. Here, we probed brain region-specific molecular signatures in pre-symptomatic Ndufs4(KO) to identify factors which underlie focal neurodegeneration. Metabolomics revealed that free amino acid concentrations are broadly different by region, and glucose metabolites are increased in a manner dependent on both region and genotype. We then tested the impact of the mTOR inhibitor rapamycin, which dramatically attenuates LS in Ndufs4(KO), on region specific metabolism. Our data revealed that loss of Ndufs4 drives pathogenic changes to CNS glutamine/glutamate/α-ketoglutarate metabolism which are rescued by mTOR inhibition Finally, restriction of the Ndufs4 deletion to pre-synaptic glutamatergic neurons recapitulated the whole-body knockout. Together, our findings are consistent with mTOR inhibition alleviating disease by increasing availability of α-ketoglutarate, which is both an efficient mitochondrial complex I substrate in Ndufs4(KO) and an important metabolite related to neurotransmitter metabolism in glutamatergic neurons.
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Affiliation(s)
- Simon C Johnson
- Department of Neurology, University of Washington, Seattle, WA 98105, USA; Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA 98105, USA; Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Ernst-Bernhard Kayser
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Rebecca Bornstein
- Department of Pathology, University of Washington, Seattle, WA 98105, USA
| | - Julia Stokes
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA 98105, USA
| | - Alessandro Bitto
- Department of Pathology, University of Washington, Seattle, WA 98105, USA
| | - Kyung Yeon Park
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Amanda Pan
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Grace Sun
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Daniel Raftery
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA 98105, USA; Department of Chemistry, University of Washington, Seattle, WA 98109, United States
| | - Matt Kaeberlein
- Department of Pathology, University of Washington, Seattle, WA 98105, USA
| | - Margaret M Sedensky
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA 98105, USA; Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Philip G Morgan
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA 98105, USA; Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA.
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15
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Bitto A, Tung H, Ying K, Smith DL, Kayser EB, Morgan PG, Sedensky MM, Kaeberlein M. AGING AND MITOCHONDRIAL DISEASE: SHARED MECHANISMS AND THERAPIES? Innov Aging 2019. [PMCID: PMC6840059 DOI: 10.1093/geroni/igz038.1459] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Mitochondrial disease describes multiple pathologies characterized by a wide array of disease symptoms and severity, caused by mitochondrial dysfunction in one or multiple organs. Aging organisms display a similar variety of disease phenotypes, which are often characterized by mitochondrial impairment. Despite the heterogeneity of aging phenotypes, several interventions have been identified which can increase lifespan and delay the onset of age-related diseases in multiple organisms. Two age-delaying interventions, rapamycin and acarbose, dramatically suppress pathology in a mouse model of mitochondrial disease caused by depletion of the NADH-Ubiquinone Oxidoreductase Complex (Ndufs4-/-). This model recapitulates human Leigh syndrome, a childhood mitochondrial disease. Upon treatment with either drug, disease suppression is accompanied by a remodeling of nutrient metabolism and restoration of the NAD+/NADH ratio in the brain without affecting the electron transport chain. Thus, we propose that metabolic derangements induced by mitochondrial dysfunction may be a shared mechanism of aging and mitochondrial disease.
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Affiliation(s)
| | - Herman Tung
- Allen Institute for brain science, Seattle, Washington, United States
| | - Kejun Ying
- School of Life Sciences, Sun Yat-sen University, Guangzhou Shi, Guangdong, China (People’s Republic)
| | - Daniel L Smith
- Department of Nutrition Science, University of Alabama, Birmingham, Alabama, United States
| | | | - Philip G Morgan
- Seattle Children’s Research Institute, Seattle, Washington, United States
| | | | - Matt Kaeberlein
- Department of Pathology, University of Washington, Seattle, Washington, United States
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16
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Johnson SC, Pan A, Sun GX, Freed A, Stokes JC, Bornstein R, Witkowski M, Li L, Ford JM, Howard CRA, Sedensky MM, Morgan PG. Relevance of experimental paradigms of anesthesia induced neurotoxicity in the mouse. PLoS One 2019; 14:e0213543. [PMID: 30897103 PMCID: PMC6428290 DOI: 10.1371/journal.pone.0213543] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 02/24/2019] [Indexed: 11/30/2022] Open
Abstract
Routine general anesthesia is considered to be safe in healthy individuals. However, pre-clinical studies in mice, rats, and monkeys have repeatedly demonstrated that exposure to anesthetic agents during early post-natal periods can lead to acute neurotoxicity. More concerning, later-life defects in cognition, assessed by behavioral assays for learning and memory, have been reported. Although the potential for anesthetics to damage the neonatal brain is well-documented, the clinical significance of the pre-clinical models in which damage is induced remains quite unclear. Here, we systematically evaluate critical physiological parameters in post-natal day 7 neonatal mice exposed to 1.5% isoflurane for 2–4 hours, the most common anesthesia induced neurotoxicity paradigm in this animal model. We find that 2 or more hours of anesthesia exposure results in dramatic respiratory and metabolic changes that may limit interpretation of this paradigm to the clinical situation. Our data indicate that neonatal mouse models of AIN are not necessarily appropriate representations of human exposures.
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Affiliation(s)
- Simon C. Johnson
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, United States of America
- Department of Neurology, University of Washington, Seattle, WA, United States of America
- * E-mail:
| | - Amanda Pan
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, United States of America
| | - Grace X. Sun
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, United States of America
| | - Arielle Freed
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, United States of America
- University of Washington School of Dentistry, Seattle, WA, United States of America
| | - Julia C. Stokes
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, United States of America
| | - Rebecca Bornstein
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, United States of America
- Department of Pathology, University of Washington, Seattle, WA, United States of America
| | - Michael Witkowski
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, United States of America
| | - Li Li
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, United States of America
| | - Jeremy M. Ford
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, United States of America
- Seattle Children's Imagination Lab, Seattle Children’s Research Institute, Seattle, WA, United States of America
| | - Christopher R. A. Howard
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, United States of America
- Seattle Children's Imagination Lab, Seattle Children’s Research Institute, Seattle, WA, United States of America
| | - Margaret M. Sedensky
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, United States of America
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA, United States of America
| | - Philip G. Morgan
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA, United States of America
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA, United States of America
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17
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Morgan PG, Sedensky MM. Traumatic Brain Injury in Flies. Anesth Analg 2018; 127:e90. [DOI: 10.1213/ane.0000000000003753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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18
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Zimin PI, Woods CB, Kayser EB, Ramirez JM, Morgan PG, Sedensky MM. Isoflurane disrupts excitatory neurotransmitter dynamics via inhibition of mitochondrial complex I. Br J Anaesth 2018; 120:1019-1032. [PMID: 29661379 DOI: 10.1016/j.bja.2018.01.036] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 01/08/2018] [Accepted: 02/09/2018] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND The mechanisms of action of volatile anaesthetics are unclear. Volatile anaesthetics selectively inhibit complex I in the mitochondrial respiratory chain. Mice in which the mitochondrial complex I subunit NDUFS4 is knocked out [Ndufs4(KO)] either globally or in glutamatergic neurons are hypersensitive to volatile anaesthetics. The volatile anaesthetic isoflurane selectively decreases the frequency of spontaneous excitatory events in hippocampal slices from Ndufs4(KO) mice. METHODS Complex I inhibition by isoflurane was assessed with a Clark electrode. Synaptic function was measured by stimulating Schaffer collateral fibres and recording field potentials in the hippocampus CA1 region. RESULTS Isoflurane specifically inhibits complex I dependent respiration at lower concentrations in mitochondria from Ndufs4(KO) than from wild-type mice. In hippocampal slices, after high frequency stimulation to increase energetic demand, short-term synaptic potentiation is less in KO compared with wild-type mice. After high frequency stimulation, both Ndufs4(KO) and wild-type hippocampal slices exhibit striking synaptic depression in isoflurane at twice the 50% effective concentrations (EC50). The pattern of synaptic depression by isoflurane indicates a failure in synaptic vesicle recycling. Application of a selective A1 adenosine receptor antagonist partially eliminates isoflurane-induced short-term depression in both wild-type and Ndufs4(KO) slices, implicating an additional mitochondria-dependent effect on exocytosis. When mitochondria are the sole energy source, isoflurane completely eliminates synaptic output in both mutant and wild-type mice at twice the (EC50) for anaesthesia. CONCLUSIONS Volatile anaesthetics directly inhibit mitochondrial complex I as a primary target, limiting synaptic ATP production, and excitatory vesicle endocytosis and exocytosis.
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Affiliation(s)
- P I Zimin
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA, USA.
| | - C B Woods
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - E B Kayser
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA
| | - J M Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Neurological Surgery, University of Washington, Seattle, WA, USA
| | - P G Morgan
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA, USA
| | - M M Sedensky
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, USA; Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, WA, USA
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19
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Affiliation(s)
- Vincent C. Hsieh
- Department of Anesthesiology and Perioperative Medicine, University of Washington, Seattle, WA, USA
| | - Elliot J. Krane
- Department of Anesthesiology, Perioperative and Pain Medicine, Stanford University, Stanford, CA, USA
- Department of Pediatrics, Stanford University, Stanford, CA, USA
| | - Philip G. Morgan
- Department of Anesthesiology and Perioperative Medicine, University of Washington, Seattle, WA, USA
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Bennett CF, Kwon JJ, Chen C, Russell J, Acosta K, Burnaevskiy N, Crane MM, Bitto A, Vander Wende H, Simko M, Pineda V, Rossner R, Wasko BM, Choi H, Chen S, Park S, Jafari G, Sands B, Perez Olsen C, Mendenhall AR, Morgan PG, Kaeberlein M. Transaldolase inhibition impairs mitochondrial respiration and induces a starvation-like longevity response in Caenorhabditis elegans. PLoS Genet 2017; 13:e1006695. [PMID: 28355222 PMCID: PMC5389855 DOI: 10.1371/journal.pgen.1006695] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 04/12/2017] [Accepted: 03/15/2017] [Indexed: 12/31/2022] Open
Abstract
Mitochondrial dysfunction can increase oxidative stress and extend lifespan in Caenorhabditis elegans. Homeostatic mechanisms exist to cope with disruptions to mitochondrial function that promote cellular health and organismal longevity. Previously, we determined that decreased expression of the cytosolic pentose phosphate pathway (PPP) enzyme transaldolase activates the mitochondrial unfolded protein response (UPRmt) and extends lifespan. Here we report that transaldolase (tald-1) deficiency impairs mitochondrial function in vivo, as evidenced by altered mitochondrial morphology, decreased respiration, and increased cellular H2O2 levels. Lifespan extension from knockdown of tald-1 is associated with an oxidative stress response involving p38 and c-Jun N-terminal kinase (JNK) MAPKs and a starvation-like response regulated by the transcription factor EB (TFEB) homolog HLH-30. The latter response promotes autophagy and increases expression of the flavin-containing monooxygenase 2 (fmo-2). We conclude that cytosolic redox established through the PPP is a key regulator of mitochondrial function and defines a new mechanism for mitochondrial regulation of longevity. There are a growing number of studies linking mitochondrial dysfunction to enhanced longevity, especially in the nematode C. elegans. The reasons for these pro-longevity effects have been elusive, but one current model is that adaptive responses to mitochondrial inhibition promote organismal health and stress resistance. Here, we report an intriguing example of mitochondrial stress induced by inhibition of a cytosolic metabolic pathway that extends lifespan in worms. We find that inhibition of the pentose phosphate pathway, which is essential for cytosolic redox homeostasis, affects multiple parameters of mitochondrial function and activates a starvation-like response that promotes longevity through recycling of damaged cellular components and induction of the enzyme flavin-containing monooxygenase 2. These results establish novel links between the pentose phosphate pathway, mitochondrial function, redox homeostasis, and organismal aging.
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Affiliation(s)
- Christopher F. Bennett
- Department of Pathology, University of Washington, Seattle, WA, United States of America
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA, United States of America
| | - Jane J. Kwon
- Department of Pathology, University of Washington, Seattle, WA, United States of America
| | - Christine Chen
- Department of Pathology, University of Washington, Seattle, WA, United States of America
| | - Joshua Russell
- Department of Pathology, University of Washington, Seattle, WA, United States of America
| | - Kathlyn Acosta
- Department of Pathology, University of Washington, Seattle, WA, United States of America
| | - Nikolay Burnaevskiy
- Department of Pathology, University of Washington, Seattle, WA, United States of America
| | - Matthew M. Crane
- Department of Pathology, University of Washington, Seattle, WA, United States of America
| | - Alessandro Bitto
- Department of Pathology, University of Washington, Seattle, WA, United States of America
| | - Helen Vander Wende
- Department of Pathology, University of Washington, Seattle, WA, United States of America
| | - Marissa Simko
- Department of Pathology, University of Washington, Seattle, WA, United States of America
| | - Victor Pineda
- Department of Pathology, University of Washington, Seattle, WA, United States of America
| | - Ryan Rossner
- Department of Pathology, University of Washington, Seattle, WA, United States of America
- Molecular Medicine and Mechanisms of Disease Program, University of Washington, Seattle, WA, United States of America
| | - Brian M. Wasko
- Department of Pathology, University of Washington, Seattle, WA, United States of America
| | - Haeri Choi
- Department of Pathology, University of Washington, Seattle, WA, United States of America
| | - Shiwen Chen
- Department of Pathology, University of Washington, Seattle, WA, United States of America
| | - Shirley Park
- Department of Pathology, University of Washington, Seattle, WA, United States of America
| | - Gholamali Jafari
- Department of Pathology, University of Washington, Seattle, WA, United States of America
| | - Bryan Sands
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America
| | - Carissa Perez Olsen
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, United States of America
| | | | - Philip G. Morgan
- Center for Integrated Brain Research, Seattle Children’s Research Institute, Seattle, WA, United States of America
- Department of Anesthesiology, University of Washington School of Medicine, Seattle, WA, United States of America
| | - Matt Kaeberlein
- Department of Pathology, University of Washington, Seattle, WA, United States of America
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA, United States of America
- Molecular Medicine and Mechanisms of Disease Program, University of Washington, Seattle, WA, United States of America
- * E-mail:
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Zimin PI, Woods CB, Quintana A, Ramirez JM, Morgan PG, Sedensky MM. Glutamatergic Neurotransmission Links Sensitivity to Volatile Anesthetics with Mitochondrial Function. Curr Biol 2016; 26:2194-201. [PMID: 27498564 DOI: 10.1016/j.cub.2016.06.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 04/28/2016] [Accepted: 06/14/2016] [Indexed: 12/31/2022]
Abstract
An enigma of modern medicine has persisted for over 150 years. The mechanisms by which volatile anesthetics (VAs) produce their effects (loss of consciousness, analgesia, amnesia, and immobility) remain an unsolved mystery. Many attractive putative molecular targets have failed to produce a significant effect when genetically tested in whole-animal models [1-3]. However, mitochondrial defects increase VA sensitivity in diverse organisms from nematodes to humans [4-6]. Ndufs4 knockout (KO) mice lack a subunit of mitochondrial complex I and are strikingly hypersensitive to VAs yet resistant to the intravenous anesthetic ketamine [7]. The change in VA sensitivity is the largest reported for a mammal. Limiting NDUFS4 loss to a subset of glutamatergic neurons recapitulates the VA hypersensitivity of Ndufs4(KO) mice, while loss in GABAergic or cholinergic neurons does not. Baseline electrophysiologic function of CA1 pyramidal neurons does not differ between Ndufs4(KO) and control mice. Isoflurane concentrations that anesthetize only Ndufs4(KO) mice (0.6%) decreased the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) only in Ndufs4(KO) CA1 neurons, while concentrations effective in control mice (1.2%) decreased sEPSC frequencies in both control and Ndufs4(KO) CA1 pyramidal cells. Spontaneous inhibitory postsynaptic currents (sIPSCs) were not differentially affected between genotypes. The effects of isoflurane were similar on evoked field excitatory postsynaptic potentials (fEPSPs) and paired pulse facilitation (PPF) in KO and control hippocampal slices. We propose that CA1 presynaptic excitatory neurotransmission is hypersensitive to isoflurane in Ndufs4(KO) mice due to the inhibition of pre-existing reduced complex I function, reaching a critical reduction that can no longer meet metabolic demands.
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Affiliation(s)
- Pavel I Zimin
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, WA 98101, USA.
| | - Christian B Woods
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Albert Quintana
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, WA 98101, USA; Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Philip G Morgan
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Margaret M Sedensky
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, WA 98101, USA
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Affiliation(s)
- Philip G Morgan
- Department of Anesthesiology and Pain Medicine, Seattle Children's Research Institute, University of Washington, Seattle, Washington, Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, Washington
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Abstract
BACKGROUND Lack of NDUFS4, a subunit of mitochondrial complex I (NADH:ubiquinone oxidoreductase), causes Leigh syndrome (LS), a progressive encephalomyopathy. Knocking out Ndufs4, either systemically or in brain only, elicits LS in mice. In patients as well as in KO mice distinct regions of the brain degenerate while surrounding tissue survives despite systemic complex I dysfunction. For the understanding of disease etiology and ultimately for the development of rationale treatments for LS, it appears important to uncover the mechanisms that govern focal neurodegeneration. RESULTS Here we used the Ndufs4(KO) mouse to investigate whether regional and temporal differences in respiratory capacity of the brain could be correlated with neurodegeneration. In the KO the respiratory capacity of synaptosomes from the degeneration prone regions olfactory bulb, brainstem and cerebellum was significantly decreased. The difference was measurable even before the onset of neurological symptoms. Furthermore, neither compensating nor exacerbating changes in glycolytic capacity of the synaptosomes were found. By contrast, the KO retained near normal levels of synaptosomal respiration in the degeneration-resistant/resilient "rest" of the brain. We also investigated non-synaptic mitochondria. The KO expectedly had diminished capacity for oxidative phosphorylation (state 3 respiration) with complex I dependent substrate combinations pyruvate/malate and glutamate/malate but surprisingly had normal activity with α-ketoglutarate/malate. No correlation between oxidative phosphorylation (pyruvate/malate driven state 3 respiration) and neurodegeneration was found: Notably, state 3 remained constant in the KO while in controls it tended to increase with time leading to significant differences between the genotypes in older mice in both vulnerable and resilient brain regions. Neither regional ROS damage, measured as HNE-modified protein, nor regional complex I stability, assessed by blue native gels, could explain regional neurodegeneration. CONCLUSION Our data suggests that locally insufficient respiration capacity of the nerve terminals may drive focal neurodegeneration.
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Affiliation(s)
- Ernst-Bernhard Kayser
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, Washington, United States of America
- * E-mail:
| | - Margaret M. Sedensky
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, Washington, United States of America
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, Washington, United States of America
| | - Philip G. Morgan
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, Washington, United States of America
- Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, Washington, United States of America
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Dancy BM, Brockway N, Ramadasan-Nair R, Yang Y, Sedensky MM, Morgan PG. Glutathione S-transferase mediates an ageing response to mitochondrial dysfunction. Mech Ageing Dev 2015; 153:14-21. [PMID: 26704446 DOI: 10.1016/j.mad.2015.12.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 12/03/2015] [Accepted: 12/10/2015] [Indexed: 12/30/2022]
Abstract
To understand primary mitochondrial disease, we utilized a complex I-deficient Caenorhabditis elegans mutant, gas-1. These animals strongly upregulate the expression of gst-14 (encoding a glutathione S-transferase). Knockdown of gst-14 dramatically extends the lifespan of gas-1 and increases hydroxynonenal (HNE) modified mitochondrial proteins without improving complex I function. We observed no change in reactive oxygen species levels as measured by Mitosox staining, consistent with a potential role of GST-14 in HNE clearance. The upregulation of gst-14 in gas-1 animals is specific to the pharynx. These data suggest that an HNE-mediated response in the pharynx could be beneficial for lifespan extension in the context of complex I dysfunction in C. elegans. Thus, whereas HNE is typically considered damaging, our work is consistent with recent reports of its role in signaling, and that in this case, the signal is pro-longevity in a model of mitochondrial dysfunction.
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Affiliation(s)
- Beverley M Dancy
- Center for Developmental Therapeutics, Seattle Children's Research Institute, 1900 9th Avenue, Seattle, WA 98101, USA.
| | - Nicole Brockway
- Center for Developmental Therapeutics, Seattle Children's Research Institute, 1900 9th Avenue, Seattle, WA 98101, USA.
| | - Renjini Ramadasan-Nair
- Center for Developmental Therapeutics, Seattle Children's Research Institute, 1900 9th Avenue, Seattle, WA 98101, USA.
| | - Yoing Yang
- Department of Genetics, Case Western Reserve University, Cleveland, OH 44106, USA.
| | - Margaret M Sedensky
- Center for Developmental Therapeutics, Seattle Children's Research Institute, 1900 9th Avenue, Seattle, WA 98101, USA; Department of Anesthesiology and Pain Medicine, University of Washington, 1959 NE Pacific Street, BB-1469, Seattle, WA 98195, USA.
| | - Philip G Morgan
- Center for Developmental Therapeutics, Seattle Children's Research Institute, 1900 9th Avenue, Seattle, WA 98101, USA; Department of Anesthesiology and Pain Medicine, University of Washington, 1959 NE Pacific Street, BB-1469, Seattle, WA 98195, USA.
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25
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Eckenhoff RG, Morgan PG. Forward to the past. Anesth Analg 2015; 120:259-60. [PMID: 25602447 DOI: 10.1213/ane.0000000000000534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Roderic G Eckenhoff
- From the *Department of Anesthesiology & Critical Care, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania; and †Department of Anesthesia, University of Washington, Seattle, Washington
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Abstract
Simple multicellular animal model systems are central to studying the complex mechanisms underlying a bewildering array of diseases involving dysfunctional mitochondria. Mutant nuclear- and mitochondrial-encoded subunits of the Caenorhabditis elegans mitochondrial respiratory chain (MRC) have been investigated, including GAS-1, NUO-1, NUO-6, MEV-1, SDHB-1, CLK-1, ISP-1, CTB-1, and ATP-2. These, as well as proteins that modify the MRC indirectly, have been studied on the molecular, cellular, and organismal levels through the variety of experimental approaches that are readily achievable in C. elegans. In C. elegans, MRC dysfunction can mimic signs and symptoms observed in human patients with primary mitochondrial disorders, such as neuromuscular deficits, developmental delay, altered anesthetic sensitivity, and increased lactate levels. Antioxidant dietary supplements, coenzyme Q substitutes, and flavin cofactors have been explored as potential therapeutic strategies. Furthermore, mutants with altered longevity have proved useful for probing the contributions of bioenergetics, reactive oxygen species, and stress responses to the process of aging. C. elegans will undoubtedly continue to provide a useful system in which to explore unanswered questions in mitochondrial biology and disease.
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Affiliation(s)
- Beverley M Dancy
- Center for Developmental Therapeutics, Seattle Children's Research Institute, 1900 Ninth Ave, Seattle, WA, USA,2 Department of Anesthesiology and Pain Medicine, University of Washington, 1959 NE Pacific St, Seattle, WA, USA
| | - Margaret M Sedensky
- Center for Developmental Therapeutics, Seattle Children's Research Institute, 1900 Ninth Ave, Seattle, WA, USA,2 Department of Anesthesiology and Pain Medicine, University of Washington, 1959 NE Pacific St, Seattle, WA, USA
| | - Philip G Morgan
- Center for Developmental Therapeutics, Seattle Children's Research Institute, 1900 Ninth Ave, Seattle, WA, USA,2 Department of Anesthesiology and Pain Medicine, University of Washington, 1959 NE Pacific St, Seattle, WA, USA
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Morgan PG, Higdon R, Kolker N, Bauman AT, Ilkayeva O, Newgard CB, Kolker E, Steele LM, Sedensky MM. Comparison of proteomic and metabolomic profiles of mutants of the mitochondrial respiratory chain in Caenorhabditis elegans. Mitochondrion 2014; 20:95-102. [PMID: 25530493 DOI: 10.1016/j.mito.2014.12.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 09/10/2014] [Accepted: 12/10/2014] [Indexed: 01/06/2023]
Abstract
Single-gene mutations that disrupt mitochondrial respiratory chain function in Caenorhabditis elegans change patterns of protein expression and metabolites. Our goal was to develop useful molecular fingerprints employing adaptable techniques to recognize mitochondrial defects in the electron transport chain. We analyzed mutations affecting complex I, complex II, or ubiquinone synthesis and discovered overarching patterns in the response of C. elegans to mitochondrial dysfunction across all of the mutations studied. These patterns are in KEGG pathways conserved from C. elegans to mammals, verifying that the nematode can serve as a model for mammalian disease. In addition, specific differences exist between mutants that may be useful in diagnosing specific mitochondrial diseases in patients.
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Affiliation(s)
- P G Morgan
- Department of Anesthesiology and Pain Medicine, University of Washington, USA; Center for Developmental Therapeutics, Seattle Children's Research Institute, USA.
| | - R Higdon
- Bioinformatics and High-throughput Analysis Laboratory, USA; High-throughput Analysis Core, Seattle Children's Research Institute, USA; Data-Enabled Life Sciences Alliance (DELSA Global), USA
| | - N Kolker
- High-throughput Analysis Core, Seattle Children's Research Institute, USA; Data-Enabled Life Sciences Alliance (DELSA Global), USA
| | - A T Bauman
- Bioinformatics and High-throughput Analysis Laboratory, USA
| | - O Ilkayeva
- Sarah W. Stedman Nutrition and Metabolism Center & Duke Molecular Physiology Institute, Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA; Sarah W. Stedman Nutrition and Metabolism Center & Duke Molecular Physiology Institute, Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | - C B Newgard
- Sarah W. Stedman Nutrition and Metabolism Center & Duke Molecular Physiology Institute, Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA; Sarah W. Stedman Nutrition and Metabolism Center & Duke Molecular Physiology Institute, Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | - E Kolker
- Bioinformatics and High-throughput Analysis Laboratory, USA; High-throughput Analysis Core, Seattle Children's Research Institute, USA; Data-Enabled Life Sciences Alliance (DELSA Global), USA; Department of Biomedical Informatics & Medical Education, University of Washington, Seattle, WA, USA; Department of Pediatrics, University of Washington, Seattle, WA, USA; Department of Chemistry and Chemical Biology, College of Science, Northeastern University, Boston, MA 02115, USA
| | - L M Steele
- Center for Developmental Therapeutics, Seattle Children's Research Institute, USA
| | - M M Sedensky
- Department of Anesthesiology and Pain Medicine, University of Washington, USA; Center for Developmental Therapeutics, Seattle Children's Research Institute, USA
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28
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Burman JL, Itsara LS, Kayser EB, Suthammarak W, Wang AM, Kaeberlein M, Sedensky MM, Morgan PG, Pallanck LJ. A Drosophila model of mitochondrial disease caused by a complex I mutation that uncouples proton pumping from electron transfer. Dis Model Mech 2014; 7:1165-74. [PMID: 25085991 PMCID: PMC4174527 DOI: 10.1242/dmm.015321] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Mutations affecting mitochondrial complex I, a multi-subunit assembly that couples electron transfer to proton pumping, are the most frequent cause of heritable mitochondrial diseases. However, the mechanisms by which complex I dysfunction results in disease remain unclear. Here, we describe a Drosophila model of complex I deficiency caused by a homoplasmic mutation in the mitochondrial-DNA-encoded NADH dehydrogenase subunit 2 (ND2) gene. We show that ND2 mutants exhibit phenotypes that resemble symptoms of mitochondrial disease, including shortened lifespan, progressive neurodegeneration, diminished neural mitochondrial membrane potential and lower levels of neural ATP. Our biochemical studies of ND2 mutants reveal that complex I is unable to efficiently couple electron transfer to proton pumping. Thus, our study provides evidence that the ND2 subunit participates directly in the proton pumping mechanism of complex I. Together, our findings support the model that diminished respiratory chain activity, and consequent energy deficiency, are responsible for the pathogenesis of complex-I-associated neurodegeneration.
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Affiliation(s)
- Jonathon L Burman
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Leslie S Itsara
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA. Molecular and Cellular Biology Program, University of Washington, Seattle, WA 98195, USA
| | - Ernst-Bernhard Kayser
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Wichit Suthammarak
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Adrienne M Wang
- Department of Pathology, University of Washington, Seattle, WA 98195, USA
| | - Matt Kaeberlein
- Department of Pathology, University of Washington, Seattle, WA 98195, USA
| | - Margaret M Sedensky
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, WA 98101, USA
| | - Philip G Morgan
- Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, WA 98101, USA.
| | - Leo J Pallanck
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA.
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Johnson SC, Yanos ME, Kayser EB, Quintana A, Sangesland M, Castanza A, Uhde L, Hui J, Wall VZ, Gagnidze A, Oh K, Wasko BM, Ramos FJ, Palmiter RD, Rabinovitch PS, Morgan PG, Sedensky MM, Kaeberlein M. mTOR inhibition alleviates mitochondrial disease in a mouse model of Leigh syndrome. Science 2013; 342:1524-8. [PMID: 24231806 PMCID: PMC4055856 DOI: 10.1126/science.1244360] [Citation(s) in RCA: 382] [Impact Index Per Article: 34.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Mitochondrial dysfunction contributes to numerous health problems, including neurological and muscular degeneration, cardiomyopathies, cancer, diabetes, and pathologies of aging. Severe mitochondrial defects can result in childhood disorders such as Leigh syndrome, for which there are no effective therapies. We found that rapamycin, a specific inhibitor of the mechanistic target of rapamycin (mTOR) signaling pathway, robustly enhances survival and attenuates disease progression in a mouse model of Leigh syndrome. Administration of rapamycin to these mice, which are deficient in the mitochondrial respiratory chain subunit Ndufs4 [NADH dehydrogenase (ubiquinone) Fe-S protein 4], delays onset of neurological symptoms, reduces neuroinflammation, and prevents brain lesions. Although the precise mechanism of rescue remains to be determined, rapamycin induces a metabolic shift toward amino acid catabolism and away from glycolysis, alleviating the buildup of glycolytic intermediates. This therapeutic strategy may prove relevant for a broad range of mitochondrial diseases.
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Affiliation(s)
- Simon C. Johnson
- Department of Pathology, University of Washington, Seattle, WA 98195, USA
| | - Melana E. Yanos
- Department of Pathology, University of Washington, Seattle, WA 98195, USA
- Department of Psychology, University of Washington, Seattle, WA 98195, USA
| | - Ernst-Bernhard Kayser
- Anesthesiology and Pain Medicine, Seattle Children’s Hospital, Seattle, WA 98105, USA
| | - Albert Quintana
- Howard Hughes Medical Institute and Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Maya Sangesland
- Department of Pathology, University of Washington, Seattle, WA 98195, USA
| | - Anthony Castanza
- Department of Pathology, University of Washington, Seattle, WA 98195, USA
| | - Lauren Uhde
- Department of Pathology, University of Washington, Seattle, WA 98195, USA
| | - Jessica Hui
- Department of Pathology, University of Washington, Seattle, WA 98195, USA
| | - Valerie Z. Wall
- Department of Pathology, University of Washington, Seattle, WA 98195, USA
| | - Arni Gagnidze
- Department of Pathology, University of Washington, Seattle, WA 98195, USA
| | - Kelly Oh
- Department of Pathology, University of Washington, Seattle, WA 98195, USA
| | - Brian M. Wasko
- Department of Pathology, University of Washington, Seattle, WA 98195, USA
| | - Fresnida J. Ramos
- Department of Pathology, University of Washington, Seattle, WA 98195, USA
| | - Richard D. Palmiter
- Howard Hughes Medical Institute and Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | | | - Philip G. Morgan
- Anesthesiology and Pain Medicine, Seattle Children’s Hospital, Seattle, WA 98105, USA
| | - Margaret M. Sedensky
- Anesthesiology and Pain Medicine, Seattle Children’s Hospital, Seattle, WA 98105, USA
| | - Matt Kaeberlein
- Department of Pathology, University of Washington, Seattle, WA 98195, USA
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Suthammarak W, Somerlot BH, Opheim E, Sedensky M, Morgan PG. Novel interactions between mitochondrial superoxide dismutases and the electron transport chain. Aging Cell 2013; 12:1132-40. [PMID: 23895727 DOI: 10.1111/acel.12144] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/20/2013] [Indexed: 12/16/2022] Open
Abstract
The processes that control aging remain poorly understood. We have exploited mutants in the nematode, Caenorhabditis elegans, that compromise mitochondrial function and scavenging of reactive oxygen species (ROS) to understand their relation to lifespan. We discovered unanticipated roles and interactions of the mitochondrial superoxide dismutases (mtSODs): SOD-2 and SOD-3. Both SODs localize to mitochondrial supercomplex I:III:IV. Loss of SOD-2 specifically (i) decreases the activities of complexes I and II, complexes III and IV remain normal; (ii) increases the lifespan of animals with a complex I defect, but not the lifespan of animals with a complex II defect, and kills an animal with a complex III defect; (iii) induces a presumed pro-inflammatory response. Knockdown of a molecule that may be a pro-inflammatory mediator very markedly extends lifespan and health of certain mitochondrial mutants. The relationship between the electron transport chain, ROS, and lifespan is complex, and defects in mitochondrial function have specific interactions with ROS scavenging mechanisms. We conclude that mtSODs are embedded within the supercomplex I:III:IV and stabilize or locally protect it from reactive oxygen species (ROS) damage. The results call for a change in the usual paradigm for the interaction of electron transport chain function, ROS release, scavenging, and compensatory responses.
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Affiliation(s)
- Wichit Suthammarak
- Department of Anesthesiology and Pain Medicine; Center for Developmental Therapeutics; University of Washington and Seattle Children's Research Institute; Seattle WA USA
| | | | - Elyce Opheim
- Department of Anesthesiology and Pain Medicine; Center for Developmental Therapeutics; University of Washington and Seattle Children's Research Institute; Seattle WA USA
| | - Margaret Sedensky
- Department of Anesthesiology and Pain Medicine; Center for Developmental Therapeutics; University of Washington and Seattle Children's Research Institute; Seattle WA USA
- Department of Genetics; Case Western Reserve University; Cleveland OH USA
| | - Philip G. Morgan
- Department of Anesthesiology and Pain Medicine; Center for Developmental Therapeutics; University of Washington and Seattle Children's Research Institute; Seattle WA USA
- Department of Genetics; Case Western Reserve University; Cleveland OH USA
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31
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Morgan PG, Kayser EB, Sedensky M. Region specific differences in oxidative phosphorylation in mitochondria from Ndufs4 knockout mice. Mitochondrion 2013. [DOI: 10.1016/j.mito.2013.07.044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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32
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Kayser EB, Johnson SC, Kaeberlein MR, Sedensky MM, Morgan PG. Capacity for oxidative phosphorylation does not decline with age in mitochondria from ndufs4 knockout mice. Mitochondrion 2013. [DOI: 10.1016/j.mito.2013.07.045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Karamanlidis G, Lee CF, Garcia-Menendez L, Kolwicz SC, Suthammarak W, Gong G, Sedensky MM, Morgan PG, Wang W, Tian R. Mitochondrial complex I deficiency increases protein acetylation and accelerates heart failure. Cell Metab 2013; 18:239-50. [PMID: 23931755 PMCID: PMC3779647 DOI: 10.1016/j.cmet.2013.07.002] [Citation(s) in RCA: 330] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 03/22/2013] [Accepted: 07/02/2013] [Indexed: 01/04/2023]
Abstract
Mitochondrial respiratory dysfunction is linked to the pathogenesis of multiple diseases, including heart failure, but the specific mechanisms for this link remain largely elusive. We modeled the impairment of mitochondrial respiration by the inactivation of the Ndufs4 gene, a protein critical for complex I assembly, in the mouse heart (cKO). Although complex I-supported respiration decreased by >40%, the cKO mice maintained normal cardiac function in vivo and high-energy phosphate content in isolated perfused hearts. However, the cKO mice developed accelerated heart failure after pressure overload or repeated pregnancy. Decreased NAD(+)/NADH ratio by complex I deficiency inhibited Sirt3 activity, leading to an increase in protein acetylation and sensitization of the permeability transition in mitochondria (mPTP). NAD(+) precursor supplementation to cKO mice partially normalized the NAD(+)/NADH ratio, protein acetylation, and mPTP sensitivity. These findings describe a mechanism connecting mitochondrial dysfunction to the susceptibility to diseases and propose a potential therapeutic target.
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Affiliation(s)
- Georgios Karamanlidis
- Mitochondria and Metabolism Center, Department of Anesthesiology and Pain Medicine, University of Washington, Seattle, 98109, USA
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Abstract
BACKGROUND Mounting evidence from animal studies shows that anesthetic exposure in early life leads to apoptosis in the developing nervous system. This loss of neurons has functional consequences in adulthood. Clinical retrospective reviews have suggested that multiple anesthetic exposures in early childhood are associated with learning disabilities later in life as well. Despite much concern about this phenomenon, little is known about the mechanism by which anesthetics initiate neuronal cell death. Caenorhabditis elegans, a powerful genetic animal model, with precisely characterized neural development and cell death pathways, affords an excellent opportunity to study anesthetic-induced neurotoxicity. We hypothesized that exposing the nematode to volatile anesthetics early in life would induce neuron cell death, producing a behavioral defect that would be manifested in adulthood. METHODS After synchronization and hatching, larval worms were exposed to volatile anesthetics at their 95% effective concentration for 4 hours. On day 4 of life, exposed and control worms were tested for their ability to sense and move to an attractant (i.e., to chemotax). We determined the rate of successful chemotaxis using a standardized chemotaxis index. RESULTS Wild-type nematodes demonstrated striking deficits in chemotaxis indices after exposure to isoflurane (ISO) or sevoflurane (SEVO) in the first larval stage (chemotaxis index: untreated, 85 ± 2; ISO, 52 ± 2; SEVO, 47 ± 2; P < 0.05 for both exposures). The mitochondrial mutant gas-1 had a heightened effect from the anesthetic exposure (chemotaxis index: untreated, 71 ± 2; ISO, 29 ± 12; SEVO, 24 ± 13; P < 0.05 for both exposures). In contrast, animals unable to undergo apoptosis because of a mutation in the pathway that mediates programmed cell death (ced-3) retained their ability to sense and move toward an attractant (chemotaxis index: untreated, 76 ± 10; ISO, 73 ± 9; SEVO, 76 ± 10). Furthermore, we discovered that the window of greatest susceptibility to anesthetic neurotoxicity in nematodes occurs in the first larval stage after hatching (L1). This coincides with a period of neurogenesis in this model. All values are means ± SD. CONCLUSION These data indicate that anesthetics affect neurobehavior in nematodes, extending the range of phyla in which early exposure to volatile anesthetics has been shown to cause functional neurological deficits. This implies that anesthetic-induced neurotoxicity occurs via an ancient underlying mechanism. C elegans is a tractable model organism with which to survey an entire genome for molecules that mediate the toxic effects of volatile anesthetics on the developing nervous system.
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Affiliation(s)
- Katherine R Gentry
- Department of Anesthesiology and Pain Medicine, Seattle Children's Hospital, M/S W 9824, PO Box 5371, Seattle, WA 98105, USA.
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Quintana A, Morgan PG, Kruse SE, Palmiter RD, Sedensky MM. Altered anesthetic sensitivity of mice lacking Ndufs4, a subunit of mitochondrial complex I. PLoS One 2012; 7:e42904. [PMID: 22912761 PMCID: PMC3422219 DOI: 10.1371/journal.pone.0042904] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 07/12/2012] [Indexed: 02/07/2023] Open
Abstract
Anesthetics are in routine use, yet the mechanisms underlying their function are incompletely understood. Studies in vitro demonstrate that both GABA(A) and NMDA receptors are modulated by anesthetics, but whole animal models have not supported the role of these receptors as sole effectors of general anesthesia. Findings in C. elegans and in children reveal that defects in mitochondrial complex I can cause hypersensitivity to volatile anesthetics. Here, we tested a knockout (KO) mouse with reduced complex I function due to inactivation of the Ndufs4 gene, which encodes one of the subunits of complex I. We tested these KO mice with two volatile and two non-volatile anesthetics. KO and wild-type (WT) mice were anesthetized with isoflurane, halothane, propofol or ketamine at post-natal (PN) days 23 to 27, and tested for loss of response to tail clamp (isoflurane and halothane) or loss of righting reflex (propofol and ketamine). KO mice were 2.5 - to 3-fold more sensitive to isoflurane and halothane than WT mice. KO mice were 2-fold more sensitive to propofol but resistant to ketamine. These changes in anesthetic sensitivity are the largest recorded in a mammal.
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Affiliation(s)
- Albert Quintana
- Howard Hughes Medical Institute and Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Philip G. Morgan
- Department of Anesthesiology and Pain Medicine, University of Washington and Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, Washington, United States of America
- * E-mail:
| | - Shane E. Kruse
- Howard Hughes Medical Institute and Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Richard D. Palmiter
- Howard Hughes Medical Institute and Department of Biochemistry, University of Washington, Seattle, Washington, United States of America
| | - Margaret M. Sedensky
- Department of Anesthesiology and Pain Medicine, University of Washington and Center for Developmental Therapeutics, Seattle Children's Research Institute, Seattle, Washington, United States of America
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Singaram VK, Morgan PG, Sedensky MM. The worm sheds light on anesthetic mechanisms. Worm 2012; 1:164-169. [PMID: 23730538 PMCID: PMC3666045 DOI: 10.4161/worm.20002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
One hundred and sixty five years have passed since the first documented use of volatile anesthetics to aid in surgery, but we have yet to understand the underlying mechanism of action of these drugs. There is no question that, in vitro, volatile anesthetics can affect the function of numerous neuronal and non-neuronal proteins. In fact, volatile anesthetics are capable of binding such diverse proteins as albumin and bacterial luciferase. The promiscuity of volatile anesthetic binding makes it difficult to determine which proteins are modulated by anesthetics to cause the state of anesthesia. Consequently, despite a great deal of in vitro data, the fundamental physiological process that volatile anesthetics perturb to effect neuronal silencing is not yet identified. Recently, data has increasingly indicated that membrane leak channels may play a role in the anesthetic response. Here we comment on the use of optogenetics to further support such a model.
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Affiliation(s)
- Vinod K Singaram
- Department of Genetics; Case Western Reserve University; Cleveland, OH USA
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Singaram VK, Somerlot BH, Falk SA, Falk MJ, Sedensky MM, Morgan PG. Optical reversal of halothane-induced immobility in C. elegans. Curr Biol 2011; 21:2070-6. [PMID: 22137475 DOI: 10.1016/j.cub.2011.10.042] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 10/04/2011] [Accepted: 10/26/2011] [Indexed: 01/29/2023]
Abstract
Volatile anesthetics (VAs) cause profound neurological effects, including reversible loss of consciousness and immobility. Despite their widespread use, the mechanism of action of VAs remains one of the unsolved puzzles of neuroscience [1, 2]. Genetic studies in Caenorhabditis elegans [3, 4], Drosophila [3, 5], and mice [6-9] indicate that ion channels controlling the neuronal resting membrane potential (RMP) also control anesthetic sensitivity. Leak channels selective for K(+) [10-13] or permeable to Na(+) [14] are critical for establishing RMP. We hypothesized that halothane, a VA, caused immobility by altering the neuronal RMP. In C. elegans, halothane-induced immobility is acutely and completely reversed by channelrhodopsin-2 based depolarization of the RMP when expressed specifically in cholinergic neurons. Furthermore, hyperpolarizing cholinergic neurons via halorhodopsin activation increases sensitivity to halothane. The sensitivity of C. elegans to halothane can be altered by 25-fold by either manipulation of membrane conductance with optogenetic methods or generation of mutations in leak channels that set the RMP. Immobility induced by another VA, isoflurane, is not affected by these treatments, thereby excluding the possibility of nonspecific hyperactivity. The sum of our data indicates that leak channels and the RMP are important determinants of halothane-induced general anesthesia.
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Affiliation(s)
- Vinod K Singaram
- Department of Genetics, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
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Pfeiffer M, Kayzer EB, Yang X, Abramson E, Kenaston MA, Lago CU, Lo HH, Sedensky MM, Lunceford A, Clarke CF, Wu SJ, McLeod C, Finkel T, Morgan PG, Mills EM. Caenorhabditis elegans UCP4 protein controls complex II-mediated oxidative phosphorylation through succinate transport. J Biol Chem 2011; 286:37712-20. [PMID: 21862587 DOI: 10.1074/jbc.m111.271452] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The novel uncoupling proteins (UCP2-5) are implicated in the mitochondrial control of oxidant production, insulin signaling, and aging. Attempts to understand their functions have been complicated by overlapping expression patterns in most organisms. Caenorhabditis elegans nematodes are unique because they express only one UCP ortholog, ceUCP4 (ucp4). Here, we performed detailed metabolic analyzes in genetically modified nematodes to define the function of the ceUCP4. The knock-out mutant ucp4 (ok195) exhibited sharply decreased mitochondrial succinate-driven (complex II) respiration. However, respiratory coupling and electron transport chain function were normal in ucp4 mitochondria. Surprisingly, isolated ucp4 mitochondria showed markedly decreased succinate uptake. Similarly, ceUCP4 inhibition blocked succinate respiration and import in wild type mitochondria. Genetic and pharmacologic inhibition of complex I function was selectively lethal to ucp4 worms, arguing that ceUCP4-regulated succinate transport is required for optimal complex II function in vivo. Additionally, ceUCP4 deficiency prolonged lifespan in the short-lived mev1 mutant that exhibits complex II-generated oxidant production. These results identify a novel function for ceUCP4 in the regulation of complex II-based metabolism through an unexpected mechanism involving succinate transport.
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Affiliation(s)
- Matthew Pfeiffer
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Texas, Austin, Texas 78712, USA
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39
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Affiliation(s)
- Margaret M Sedensky
- Department of Anesthesiology, University Hospitals and Case School of Medicine, Cleveland, Ohio 44106-5007, USA
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40
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Falk MJ, Zhang Z, Rosenjack JR, Nissim I, Daikhin E, Nissim I, Sedensky MM, Yudkoff M, Morgan PG. Metabolic pathway profiling of mitochondrial respiratory chain mutants in C. elegans. Mol Genet Metab 2008; 93:388-97. [PMID: 18178500 DOI: 10.1016/j.ymgme.2007.11.007] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2007] [Accepted: 11/02/2007] [Indexed: 11/18/2022]
Abstract
Caenorhabditis elegans affords a model of primary mitochondrial dysfunction that provides insight into cellular adaptations which accompany mutations in nuclear genes that encode mitochondrial proteins. To this end, we characterized genome-wide expression profiles of C. elegans strains with mutations in nuclear-encoded subunits of respiratory chain complexes. Our goal was to detect concordant changes among clusters of genes that comprise defined metabolic pathways. Results indicate that respiratory chain mutants significantly upregulate a variety of basic cellular metabolic pathways involved in carbohydrate, amino acid, and fatty acid metabolism, as well as cellular defense pathways such as the metabolism of P450 and glutathione. To further confirm and extend expression analysis findings, quantitation of whole worm free amino acid levels was performed in C. elegans mitochondrial mutants for subunits of complexes I, II, and III. Significant differences were seen for 13 of 16 amino acid levels in complex I mutants compared with controls, as well as overarching similarities among profiles of complex I, II, and III mutants compared with controls. The specific pattern of amino acid alterations observed provides novel evidence to suggest that an increase in glutamate-linked transamination reactions caused by the failure of NAD(+)-dependent ketoacid oxidation occurs in primary mitochondrial respiratory chain mutants. Recognition of consistent alterations both among patterns of nuclear gene expression for multiple biochemical pathways and in quantitative amino acid profiles in a translational genetic model of mitochondrial dysfunction allows insight into the complex pathogenesis underlying primary mitochondrial disease. Such knowledge may enable the development of a metabolomic profiling diagnostic tool applicable to human mitochondrial disease.
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Affiliation(s)
- M J Falk
- Division of Human Genetics, Department of Pediatrics, The Children's Hospital of Philadelphia and University of Pennsylvania, Philadelphia, PA, USA.
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41
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Morgan PG, Georghiou M, Flynn F, Jaggar S. Lack of renoprotective effect of i.v. N-acetylcysteine in patients with chronic renal failure. Br J Anaesth 2007; 99:143; author reply 143-4. [PMID: 17573400 DOI: 10.1093/bja/aem151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Abstract
The mechanism of action of volatile anesthetics remains an enigma, despite their worldwide use. The nematode C. elegans has served as an excellent model to unravel this mystery. Genes and gene sets that control the behavior of the animal in volatile anesthetics have been identified, using multiple endpoints to mimic the phenomenon of anesthesia in man. Some of these studies have clear translational implications in more complicated organisms.
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Affiliation(s)
- P G Morgan
- Department of Anesthesiology, Case School of Medicine, Cleveland, OH 44106, USA
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43
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Falk MJ, Kayser EB, Morgan PG, Sedensky MM. Mitochondrial complex I function modulates volatile anesthetic sensitivity in C. elegans. Curr Biol 2006; 16:1641-5. [PMID: 16920626 PMCID: PMC3641903 DOI: 10.1016/j.cub.2006.06.072] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2005] [Revised: 06/22/2006] [Accepted: 06/22/2006] [Indexed: 11/22/2022]
Abstract
Despite the widespread clinical use of volatile anesthetics, their mechanisms of action remain unknown [1-6]. An unbiased genetic screen in the nematode C. elegans for animals with altered volatile anesthetic sensitivity identified a mutant in a nuclear-encoded subunit of mitochondrial complex I [7,8]. This raised the question of whether mitochondrial dysfunction might be the primary mechanism by which volatile anesthetics act, rather than an untoward secondary effect [9,10]. We report here analysis of additional C. elegans mutations in orthologs of human genes that contribute to the formation of complex I, complex II, complex III, and coenzyme Q [11-14]. To further characterize the specific contribution of complex I, we generated four hypomorphic C. elegans mutants encoding different complex I subunits [15]. Our main finding is the identification of a clear correlation between complex I-dependent oxidative phosphorylation capacity and volatile anesthetic sensitivity. These extended data link a physiologic determinant of anesthetic action in a tractable animal model to similar clinical observations in children with mitochondrial myopathies [16]. This work is the first to specifically implicate complex I-dependent oxidative phosphorylation function as a primary mediator of volatile anesthetic effect.
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Affiliation(s)
- Marni J. Falk
- Department of Pediatrics, University Hospitals of Cleveland, CASE School of Medicine, Cleveland, Ohio 44106
- Department of Genetics, University Hospitals of Cleveland, CASE School of Medicine, Cleveland, Ohio 44106
| | - Ernst-Bernhard Kayser
- Department of Anesthesiology, University Hospitals of Cleveland, CASE School of Medicine, Cleveland, Ohio 44106
| | - Philip G. Morgan
- Department of Genetics, University Hospitals of Cleveland, CASE School of Medicine, Cleveland, Ohio 44106
- Department of Anesthesiology, University Hospitals of Cleveland, CASE School of Medicine, Cleveland, Ohio 44106
- Department of Pharmacology, University Hospitals of Cleveland, CASE School of Medicine, Cleveland, Ohio 44106
| | - Margaret M. Sedensky
- Department of Genetics, University Hospitals of Cleveland, CASE School of Medicine, Cleveland, Ohio 44106
- Department of Anesthesiology, University Hospitals of Cleveland, CASE School of Medicine, Cleveland, Ohio 44106
- Correspondence:
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44
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Sedensky MM, Morgan PG. Mitochondrial respiration and reactive oxygen species in C. elegans. Exp Gerontol 2006; 41:957-67. [PMID: 16919906 DOI: 10.1016/j.exger.2006.06.056] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2006] [Revised: 06/20/2006] [Accepted: 06/30/2006] [Indexed: 10/24/2022]
Abstract
A powerful approach to understanding complex processes such as aging is to study longevity in organisms that are amenable to genetic dissection. The nematode Caenorhabditis elegans represents a superb model system in which to study the effects of mitochondrial function on longevity. Several mutant strains have been identified that indicate that mitochondrial function is a major factor affecting the organism's lifespan. Taken as a group, these mutant strains indicate that metabolic rate, per se, only affects longevity indirectly. Mutations causing lowered metabolic rate potential are capable of decreasing or increasing longevity.
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Affiliation(s)
- M M Sedensky
- Department of Anesthesiology, University Hospitals and Case School of Medicine, Cleveland, OH 44106, USA
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Sedensky MM, Morgan PG. Mitochondrial respiration and reactive oxygen species in mitochondrial aging mutants. Exp Gerontol 2006; 41:237-45. [PMID: 16497463 DOI: 10.1016/j.exger.2006.01.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2005] [Revised: 12/29/2005] [Accepted: 01/04/2006] [Indexed: 11/28/2022]
Abstract
A powerful approach to understanding a complex process such as aging is to study the process in model organisms that are amenable to genetic dissection. Several mutant strains in different organisms have been identified that affect lifespan; data from these organisms indicate that mitochondrial function is a major factor affecting lifespan. Mutations which affect some aspect of mitochondrial function and affect lifespan have been isolated in yeast, nematodes, flies and mice. These results have revealed a general pattern that decreased metabolic rates are associated with increased lifespans. However, it is also clear that some strains with decreased metabolic rates have shortened lifespans. The emerging data is most consistent with the effects of reactive oxygen species also playing a major role in determining lifespan. Mitochondrial mutations are apparently capable of slowing metabolism with resulting increases or decreases in production of reactive oxygen species. In this review, we discuss the effects of mitochondrial mutations of lifespan with an emphasis on the role of reactive oxygen species.
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Affiliation(s)
- Margaret M Sedensky
- Department of Anesthesiology and Genetics, University Hospitals and Case School of Medicine, Cleveland, OH 44106, USA
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Sedensky MM, Siefker JM, Koh JY, Miller DM, Morgan PG. A stomatin and a degenerin interact in lipid rafts of the nervous system of Caenorhabditis elegans. Am J Physiol Cell Physiol 2004; 287:C468-74. [PMID: 15102610 DOI: 10.1152/ajpcell.00182.2003] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In Caenorhabditis elegans, the gene unc-1 controls anesthetic sensitivity and normal locomotion. The protein UNC-1 is a close homolog of the mammalian protein stomatin and is expressed primarily in the nervous system. Genetic studies in C. elegans have shown that the UNC-1 protein interacts with a sodium channel subunit, UNC-8. In humans, absence of stomatin is associated with abnormal sodium and potassium levels in red blood cells. Stomatin also has been postulated to participate in the formation of lipid rafts, which are membrane microdomains associated with protein complexes, cholesterol, and sphingolipids. In this study, we isolated a low-density, detergent-resistant fraction from cell membranes of C. elegans. This fraction contains cholesterol, sphingolipids, and protein consistent with their identification as lipid rafts. We then probed Western blots of protein from the rafts and found that the UNC-1 protein is almost totally restricted to this fraction. The UNC-8 protein is also found in rafts and coimmunoprecipitates UNC-1. A second stomatin-like protein, UNC-24, also affects anesthetic sensitivity, is found in lipid rafts, and regulates UNC-1 distribution. Mutations in the unc-24 gene alter the distribution of UNC-1 in lipid rafts. Each of these mutations alters anesthetic sensitivity in C. elegans. Because lipid rafts contain many of the putative targets of volatile anesthetics, they may represent a novel class of targets for volatile anesthetics.
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Affiliation(s)
- M M Sedensky
- Departments of Anesthesiology and Genetics, University Hospitals and Case Western Reserve University, 11100 Euclid Avenue, Cleveland, OH 44106, USA
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Hartman PS, Ishii N, Kayser EB, Morgan PG, Sedensky MM. Mitochondrial mutations differentially affect aging, mutability and anesthetic sensitivity in Caenorhabditis elegans. Mech Ageing Dev 2001; 122:1187-201. [PMID: 11389932 DOI: 10.1016/s0047-6374(01)00259-7] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In the nematode Caenorhabditis elegans, mutations have been previously isolated that affect the activities of Complex I (gas-1) and Complex II (mev-1), two of the five membrane-bound complexes that control electron flow in mitochondrial respiration. We compared the effects of gas-1 and mev-1 mutations on different traits influenced by mitochondrial function. Mutations in Complex I and II both increased sensitivity to free radicals as measured during development and in aging animals. However, gas-1 and mev-1 mutations differentially affected mutability and anesthetic sensitivity. Specifically, gas-1 was anesthetic hypersensitive but not hypermutable while mev-1 was hypermutable but displayed normal responses to anesthetics. These results indicate that Complexes I and II may differ in their effects on behavior and development, and are consistent with the wide variation in phenotypes that result from mitochondrial changes in other organisms.
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Affiliation(s)
- P S Hartman
- Department of Biology, Texas Christian University, Fort Worth, TX 76129, USA
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48
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Abstract
A mutation in the gene gas-1 alters sensitivity to volatile anesthetics, fecundity, and life span in the nematode Caenorhabditis elegans. gas-1 encodes a close homologue of the 49-kDa iron protein subunit of Complex I of the mitochondrial electron transport chain from bovine heart. gas-1 is widely expressed in the nematode neuromuscular system and in a subcellular pattern consistent with that of a mitochondrial protein. Pharmacological studies indicate that gas-1 functions partially via presynaptic effects. In addition, a mutation in the gas-1 gene profoundly decreases Complex I-dependent metabolism in mitochondria as measured by rates of both oxidative phosphorylation and electron transport. An increase in Complex II-dependent metabolism also is seen in mitochondria from gas-1 animals. There is no apparent alteration in physical structure in mitochondria from gas-1 nematodes compared with those from wild type. These data indicate that gas-1 is the major 49-kDa protein of complex I and that the GAS-1 protein is critical to mitochondrial function in C. elegans. They also reveal the importance of mitochondrial function in determining not only aging and life span, but also anesthetic sensitivity, in this model organism.
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Affiliation(s)
- E B Kayser
- Department of Anesthesiology, University Hospitals, Case Western Reserve University, Cleveland, Ohio 44106, USA
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49
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Sedensky MM, Siefker JM, Morgan PG. Model organisms: new insights into ion channel and transporter function. Stomatin homologues interact in Caenorhabditis elegans. Am J Physiol Cell Physiol 2001; 280:C1340-8. [PMID: 11287347 DOI: 10.1152/ajpcell.2001.280.5.c1340] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In C. elegans the protein UNC-1 is a major determinant of anesthetic sensitivity and is a close homologue of the mammalian protein stomatin. In humans stomatin is missing from erythrocyte membranes in the hemolytic disease overhydrated hereditary stomatocytosis, despite an apparently normal stomatin gene. Overhydrated hereditary stomatocytosis is characterized by alteration of the normal transmembrane gradients of sodium and potassium. Stomatin has been shown to interact genetically with sodium channels. It is also postulated that stomatin is important in the organization of lipid rafts. We demonstrate here that antibodies against UNC-1 stain the major nerve tracts of Caenorhabditis elegans, with very intense staining of the nerve ring. We also found that a gene encoding a stomatin-like protein, UNC-24, affects anesthetic sensitivity and is genetically epistatic to unc-1. In the absence of UNC-24, the staining of the nerve ring by anti-UNC-1 is abolished, despite normal transcriptional levels of the unc-1 mRNA. Western blots indicate that UNC-24 probably affects the stability of the UNC-1 protein. UNC-24 may therefore be necessary for the correct placement of UNC-1 in the cell membrane and organization of lipid rafts.
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Affiliation(s)
- M M Sedensky
- Department of Anesthesiology, University Hospitals and Case Western Reserve University, Cleveland, Ohio 44106, USA
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50
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Abstract
We studied the effects of two nonimmobilizers, a transitional compound, and halothane on the nematode, Caenorhabditis elegans, by using reversible immobility as an end point. By themselves, the nonimmobilizers did not immobilize any of the four strains of animals tested. Toluene appears to be a transitional compound for all strains tested. The additive effects of the nonimmobilizers with halothane were also studied. Similar to results seen in studies of mice, the nonimmobilizers were antagonistic to halothane in the wild type nematode. However, the nonimmobilizers did not affect the 50% effective concentrations of halothane for two other mutant strains. For halothane, the slopes of the dose response curves were smaller in more sensitive strains compared with the wild type. As in mammals, nonimmobilizers antagonize the effects of halothane on the nematode, C. elegans. The variation in slopes in the response to halothane in different strains is consistent with multiple sites of action. These results support the use of C. elegans as a model for the study of anesthetics.
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Affiliation(s)
- P G Morgan
- Departments of Anesthesiology and Genetics, University Hospitals and Case Western Reserve University, Cleveland, Ohio 44106, USA.
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