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Regulation of Oxidative Phosphorylation of Liver Mitochondria in Sepsis. Cells 2022; 11:cells11101598. [PMID: 35626633 PMCID: PMC9139457 DOI: 10.3390/cells11101598] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 04/25/2022] [Accepted: 05/09/2022] [Indexed: 11/26/2022] Open
Abstract
The link between liver dysfunction and decreased mitochondrial oxidative phosphorylation in sepsis has been clearly established in experimental models. Energy transduction is plastic: the efficiency of mitochondrial coupling collapses in the early stage of sepsis but is expected to increase during the recovery phases of sepsis. Among the mechanisms regulating the coupling efficiency of hepatic mitochondria, the slipping reactions at the cytochrome oxidase and ATP synthase seem to be a determining element, whereas other regulatory mechanisms such as those involving proton leakage across the mitochondrial membrane have not yet been formally proven in the context of sepsis. If the dysfunction of hepatic mitochondria is related to impaired cytochrome c oxidase and ATP synthase functions, we need to consider therapeutic avenues to restore their activities for recovery from sepsis. In this review, we discussed previous findings regarding the regulatory mechanism involved in changes in the oxidative phosphorylation of liver mitochondria in sepsis, and propose therapeutic avenues to improve the functions of cytochrome c oxidase and ATP synthase in sepsis.
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Duroux-Richard I, Apparailly F, Khoury M. Mitochondrial MicroRNAs Contribute to Macrophage Immune Functions Including Differentiation, Polarization, and Activation. Front Physiol 2021; 12:738140. [PMID: 34803730 PMCID: PMC8595120 DOI: 10.3389/fphys.2021.738140] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 09/22/2021] [Indexed: 12/22/2022] Open
Abstract
A subset of microRNA (miRNA) has been shown to play an important role in mitochondrial (mt) functions and are named MitomiR. They are present within or associated with mitochondria. Most of the mitochondrial miRNAs originate from the nucleus, while a very limited number is encoded by mtDNA. Moreover, the miRNA machinery including the Dicer and Argonaute has also been detected within mitochondria. Recent, literature has established a close relationship between miRNAs and inflammation. Indeed, specific miRNA signatures are associated with macrophage differentiation, polarization and functions. Nevertheless, the regulation of macrophage inflammatory pathways governed specifically by MitomiR and their implication in immune-mediated inflammatory disorders remain poorly studied. Here, we propose a hypothesis in which MitomiR play a key role in triggering macrophage differentiation and modulating their downstream activation and immune functions. We sustain this proposition by bioinformatic data obtained from either the human monocytic THP1 cell line or the purified mitochondrial fraction of PMA-induced human macrophages. Interestingly, 22% of the 754 assayed miRNAs were detected in the mitochondrial fraction and are either exclusively or highly enriched cellular miRNA. Furthermore, the in silico analysis performed in this study, identified a specific MitomiR signature associated with macrophage differentiation that was correlated with gene targets within the mitochondria genome or with mitochondrial pathways. Overall, our hypothesis and data suggest a previously unrecognized link between MitomiR and macrophage function and fate. We also suggest that the MitomiR-dependent control could be further enhanced through the transfer of mitochondria from donor to target cells, as a new strategy for MitomiR delivery.
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Affiliation(s)
| | - Florence Apparailly
- IRMB, INSERM, Université de Montpellier, CHU Montpellier, Montpellier, France.,Clinical Department for Osteoarticular Diseases, University Hospital of Montpellier, Montpellier, France
| | - Maroun Khoury
- Laboratory of Nano-Regenerative Medicine, Faculty of Medicine, Universidad de Los Andes, Santiago, Chile.,Cells for Cells and REGENERO, The Chilean Consortium for Regenerative Medicine, Santiago, Chile.,IMPACT, Center of Interventional Medicine for Precision and Advanced Cellular Therapy, Santiago, Chile
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Duncan GJ, Simkins TJ, Emery B. Neuron-Oligodendrocyte Interactions in the Structure and Integrity of Axons. Front Cell Dev Biol 2021; 9:653101. [PMID: 33763430 PMCID: PMC7982542 DOI: 10.3389/fcell.2021.653101] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 02/15/2021] [Indexed: 12/12/2022] Open
Abstract
The myelination of axons by oligodendrocytes is a highly complex cell-to-cell interaction. Oligodendrocytes and axons have a reciprocal signaling relationship in which oligodendrocytes receive cues from axons that direct their myelination, and oligodendrocytes subsequently shape axonal structure and conduction. Oligodendrocytes are necessary for the maturation of excitatory domains on the axon including nodes of Ranvier, help buffer potassium, and support neuronal energy metabolism. Disruption of the oligodendrocyte-axon unit in traumatic injuries, Alzheimer's disease and demyelinating diseases such as multiple sclerosis results in axonal dysfunction and can culminate in neurodegeneration. In this review, we discuss the mechanisms by which demyelination and loss of oligodendrocytes compromise axons. We highlight the intra-axonal cascades initiated by demyelination that can result in irreversible axonal damage. Both the restoration of oligodendrocyte myelination or neuroprotective therapies targeting these intra-axonal cascades are likely to have therapeutic potential in disorders in which oligodendrocyte support of axons is disrupted.
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Affiliation(s)
- Greg J. Duncan
- Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, Portland, OR, United States
| | - Tyrell J. Simkins
- Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, Portland, OR, United States
- Vollum Institute, Oregon Health & Science University, Portland, OR, United States
- Department of Neurology, VA Portland Health Care System, Portland, OR, United States
| | - Ben Emery
- Jungers Center for Neurosciences Research, Department of Neurology, Oregon Health & Science University, Portland, OR, United States
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Caputa G, Flachsmann LJ, Cameron AM. Macrophage metabolism: a wound-healing perspective. Immunol Cell Biol 2019; 97:268-278. [PMID: 30779212 DOI: 10.1111/imcb.12237] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/16/2019] [Accepted: 01/21/2019] [Indexed: 12/11/2022]
Abstract
Macrophages are a critical component of the innate immune response, and compose the first response to perturbations in tissue homeostasis. Their unique ability to dynamically integrate diverse stimuli underlies their important role in the healing response from first insult to re-establishment of tissue homeostasis. While the roles of macrophages in tissue repair have been well-described in vitro and in vivo, the influence of cellular metabolism on macrophage function during tissue repair remains an unexplored area of immunometabolism. In this review, we will explore the unique metabolic requirements of inflammatory and anti-inflammatory macrophages and the potential contribution of macrophage metabolism to each phase of wound healing.
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Affiliation(s)
- George Caputa
- Department of Immunometabolism, Max Planck Institute for Immunobiology and Epigenetics, Freiburg im Breisgau, Germany
| | - Lea J Flachsmann
- Department of Immunometabolism, Max Planck Institute for Immunobiology and Epigenetics, Freiburg im Breisgau, Germany
| | - Alanna M Cameron
- Department of Immunometabolism, Max Planck Institute for Immunobiology and Epigenetics, Freiburg im Breisgau, Germany
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Keller CW, Lünemann JD. Autophagy and Autophagy-Related Proteins in CNS Autoimmunity. Front Immunol 2017; 8:165. [PMID: 28289410 PMCID: PMC5326760 DOI: 10.3389/fimmu.2017.00165] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 02/02/2017] [Indexed: 12/13/2022] Open
Abstract
Autophagy comprises a heterogeneous group of cellular pathways that enables eukaryotic cells to deliver cytoplasmic constituents for lysosomal degradation, to recycle nutrients, and to survive during starvation. In addition to these primordial functions, autophagy has emerged as a key mechanism in orchestrating innate and adaptive immune responses and to shape CD4+ T cell immunity through delivery of peptides to major histocompatibility complex (MHC) class II-containing compartments (MIICs). Individual autophagy proteins additionally modulate expression of MHC class I molecules for CD8+ T cell activation. The emergence and expansion of autoreactive CD4+ and CD8+ T cells are considered to play a key role in the pathogenesis of multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis. Expression of the essential autophagy-related protein 5 (Atg5), which supports T lymphocyte survival and proliferation, is increased in T cells isolated from blood or brain tissues from patients with relapsing-remitting MS. Whether Atgs contribute to the activation of autoreactive T cells through autophagy-mediated antigen presentation is incompletely understood. Here, we discuss the complex functions of autophagy proteins and pathways in regulating T cell immunity and its potential role in the development and progression of MS.
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Affiliation(s)
- Christian W Keller
- Institute of Experimental Immunology, Laboratory of Neuroinflammation, University of Zürich , Zürich , Switzerland
| | - Jan D Lünemann
- Institute of Experimental Immunology, Laboratory of Neuroinflammation, University of Zürich, Zürich, Switzerland; Department of Neurology, University Hospital Zürich, Zürich, Switzerland
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Campbell GR, Kraytsberg Y, Krishnan KJ, Ohno N, Ziabreva I, Reeve A, Trapp BD, Newcombe J, Reynolds R, Lassmann H, Khrapko K, Turnbull DM, Mahad DJ. Clonally expanded mitochondrial DNA deletions within the choroid plexus in multiple sclerosis. Acta Neuropathol 2012; 124:209-20. [PMID: 22688405 PMCID: PMC3674417 DOI: 10.1007/s00401-012-1001-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 05/26/2012] [Accepted: 05/26/2012] [Indexed: 12/01/2022]
Abstract
Mitochondrial DNA deletions (∆-mtDNA) have been implicated in the pathogenesis of Alzheimer's disease (AD), multiple sclerosis (MS) and Parkinson's disease (PD), as well as ageing. Clonal expansion of ∆-mtDNA is the process by which a mutant mtDNA molecule increases to high levels within a single cell containing both wild-type and mutant mtDNA. Unlike in AD and PD, the diffuse inflammatory process in MS involves the choroid plexus, and mitochondria are exposed to reactive oxygen and nitrogen species over a prolonged period. We determined the extent of respiratory enzyme deficiency and ∆-mtDNA at a single cell level within choroid plexus epithelial cells in MS as well as in AD, PD and controls. The respiratory enzyme-deficient (lacking complex IV and with intact complex II activity) cells were more prevalent within the choroid plexus in AD, MS and PD compared with controls. The main catalytic subunit of complex IV (subunit-I of cytochrome c oxidase) was lacking in significantly more respiratory enzyme-deficient cells in MS compared with AD, PD and controls. The single cell analysis showed a fourfold increase in the percentage of respiratory enzyme-deficient choroid plexus epithelial cells harbouring clonally expanded ∆-mtDNA in MS. Our findings establish clonal expansion of ∆-mtDNA as a feature relatively more prominent within the choroid plexus epithelium in MS than AD, PD or controls. We propose clonal expansion of ∆-mtDNA as a molecular link between inflammation and part of a delayed cellular energy failure in MS.
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Affiliation(s)
- Graham R Campbell
- The Mitochondrial Research Group, Institute for Ageing and Health, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
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Abstract
OBJECTIVE The cytopathic hypoxia theory proposes that there is an impaired cellular oxygen utilization during sepsis. Respiratory complex IV, or cytochrome c oxidase, was only previously studied in muscle biopsies of 16 surviving and 12 nonsurviving septic patients. We hypothesized that higher activities and quantities of this enzyme complex could be associated with septic patient survival. The objective was to evaluate the relationship between cytochrome c oxidase activities and quantities and 6-month survival in a larger series of septic patients using a less invasive method (circulating platelets). DESIGN Prospective, multicenter, observational study. SETTING The study was carried out in six Spanish intensive care units. PATIENTS We included 96 septic patients. INTERVENTIONS We determined the cytochrome c oxidase activity per citrate synthase activity ratio and cytochrome c oxidase quantity per citrate synthase activity ratio in circulating platelets at the time of diagnosis and related them to 6-month survival. The written informed consent from the family members was obtained. MEASUREMENTS AND MAIN RESULTS Survivor patients (n = 54) showed higher cytochrome c oxidase activity per citrate synthase activity ratio (p = .04) and cytochrome c oxidase quantity per citrate synthase activity ratio (p = .006) than nonsurvivors (n = 42). Logistic regression analyses confirmed that the cytochrome c oxidase activity per citrate synthase activity ratio (p = .04) and cytochrome c oxidase quantity per citrate synthase activity ratio (p = .02) were independent predictors of 6-month survival. The area under the curve to predict 6-month survival was 0.62 (95% confidence interval 0.51-0.74; p = .04) for the cytochrome c oxidase activity per citrate synthase activity ratio and 0.67 (95% confidence interval 0.56-0.76; p = .003) for the cytochrome c oxidase quantity per citrate synthase activity ratio. A negative correlation was found between the cytochrome c oxidase quantity per citrate synthase activity ratio and Sepsis-Related Organ Failure Assessment score (p = .04). CONCLUSIONS Platelet cytochrome c oxidase activity and quantity were independent predictors of 6-month survival and could be used as biomarkers of sepsis mortality. This is a rapid, easy, and less invasive protocol to assess mitochondrial function. Patients with lower cytochrome c oxidase activity and quantity could benefit from drugs that improve mitochondrial function.
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Campbell GR, Ziabreva I, Reeve AK, Krishnan KJ, Reynolds R, Howell O, Lassmann H, Turnbull DM, Mahad DJ. Mitochondrial DNA deletions and neurodegeneration in multiple sclerosis. Ann Neurol 2010; 69:481-92. [PMID: 21446022 PMCID: PMC3580047 DOI: 10.1002/ana.22109] [Citation(s) in RCA: 257] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2010] [Revised: 05/26/2010] [Accepted: 05/28/2010] [Indexed: 01/07/2023]
Abstract
Objective Cerebral atrophy is a correlate of clinical progression in multiple sclerosis (MS). Mitochondria are now established to play a part in the pathogenesis of MS. Uniquely, mitochondria harbor their own mitochondrial DNA (mtDNA), essential for maintaining a healthy central nervous system. We explored mitochondrial respiratory chain activity and mtDNA deletions in single neurons from secondary progressive MS (SPMS) cases. Methods Ninety-eight snap-frozen brain blocks from 13 SPMS cases together with complex IV/complex II histochemistry, immunohistochemistry, laser dissection microscopy, long-range and real-time PCR and sequencing were used to identify and analyze respiratory-deficient neurons devoid of complex IV and with complex II activity. Results The density of respiratory-deficient neurons in SPMS was strikingly in excess of aged controls. The majority of respiratory-deficient neurons were located in layer VI and immediate subcortical white matter (WM) irrespective of lesions. Multiple deletions of mtDNA were apparent throughout the gray matter (GM) in MS. The respiratory-deficient neurons harbored high levels of clonally expanded mtDNA deletions at a single-cell level. Furthermore, there were neurons lacking mtDNA-encoded catalytic subunits of complex IV. mtDNA deletions sufficiently explained the biochemical defect in the majority of respiratory-deficient neurons. Interpretation These findings provide evidence that neurons in MS are respiratory-deficient due to mtDNA deletions, which are extensive in GM and may be induced by inflammation. We propose induced multiple deletions of mtDNA as an important contributor to neurodegeneration in MS.
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Affiliation(s)
- Graham R Campbell
- Institute of Ageing and Health, Mitochondrial Research Group, Newcastle University, Newcastle upon Tyne, UK
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Mahad DJ, Ziabreva I, Campbell G, Lax N, White K, Hanson PS, Lassmann H, Turnbull DM. Mitochondrial changes within axons in multiple sclerosis. Brain 2009; 132:1161-74. [PMID: 19293237 DOI: 10.1093/brain/awp046] [Citation(s) in RCA: 327] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Multiple sclerosis is the most common cause of non-traumatic neurological impairment in young adults. An energy deficient state has been implicated in the degeneration of axons, the pathological correlate of disease progression, in multiple sclerosis. Mitochondria are the most efficient producers of energy and play an important role in calcium homeostasis. We analysed the density and function of mitochondria using immunohistochemistry and histochemistry, respectively, in chronic active and inactive lesions in progressive multiple sclerosis. As shown before in acute pattern III and Balo's lesions, the mitochondrial respiratory chain complex IV activity is reduced despite the presence of mitochondria in demyelinated axons with amyloid precursor protein accumulation, which are predominantly located at the active edge of chronic active lesions. Furthermore, the strong non-phosphorylated neurofilament (SMI32) reactivity was associated with a significant reduction in complex IV activity and mitochondria within demyelinated axons. The complex IV defect associated with axonal injury may be mediated by soluble products of innate immunity, as suggested by an inverse correlation between complex IV activity and macrophage/microglial density in chronic lesions. However, in inactive areas of chronic multiple sclerosis lesions the mitochondrial respiratory chain complex IV activity and mitochondrial mass, judged by porin immunoreactivity, are increased within approximately half of large (>2.5 microm diameter) chronically demyelinated axons compared with large myelinated axons in the brain and spinal cord. The axon-specific mitochondrial docking protein (syntaphilin) and phosphorylated neurofilament-H were increased in chronic lesions. The lack of complex IV activity in a proportion of Na(+)/K(+) ATPase alpha-1 positive demyelinated axons supports axonal dysfunction as a contributor to neurological impairment and disease progression. Furthermore, in vitro studies show that inhibition of complex IV augments glutamate-mediated axonal injury (amyloid precursor protein and SMI32 reactivity). Our findings have important implications for both axonal degeneration and dysfunction during the progressive stage of multiple sclerosis.
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Affiliation(s)
- Don J Mahad
- Mitochondrial Research Group, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK.
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Mahad D, Ziabreva I, Lassmann H, Turnbull D. Mitochondrial defects in acute multiple sclerosis lesions. ACTA ACUST UNITED AC 2008; 131:1722-35. [PMID: 18515320 PMCID: PMC2442422 DOI: 10.1093/brain/awn105] [Citation(s) in RCA: 293] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Multiple sclerosis is a chronic inflammatory disease, which leads to focal plaques of demyelination and tissue injury in the CNS. The structural and immunopathological patterns of demyelination suggest that different immune mechanisms may be involved in tissue damage. In a subtype of lesions, which are mainly found in patients with acute fulminant multiple sclerosis with Balo's type concentric sclerosis and in a subset of early relapsing remitting multiple sclerosis, the initial myelin changes closely resemble those seen in white matter stroke (WMS), suggesting a hypoxia-like tissue injury. Since mitochondrial injury may be involved in the pathogenesis of such lesions, we analysed a number of mitochondrial respiratory chain proteins in active lesions from acute multiple sclerosis and from WMS using immunohistochemistry. Functionally important defects of mitochondrial respiratory chain complex IV [cytochrome c oxidase (COX)] including its catalytic component (COX-I) are present in Pattern III but not in Pattern II multiple sclerosis lesions. The lack of immunohistochemically detected COX-I is apparent in oligodendrocytes, hypertrophied astrocytes and axons, but not in microglia. The profile of immunohistochemically detected mitochondrial respiratory chain complex subunits differs between multiple sclerosis and WMS. The findings suggest that hypoxia-like tissue injury in Pattern III multiple sclerosis lesions may be due to mitochondrial impairment.
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Affiliation(s)
- Don Mahad
- The Mitochondrial Research Group, University of Newcastle upon Tyne, UK
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Kitamura H, Ito M, Yuasa T, Kikuguchi C, Hijikata A, Takayama M, Kimura Y, Yokoyama R, Kaji T, Ohara O. Genome-wide identification and characterization of transcripts translationally regulated by bacterial lipopolysaccharide in macrophage-like J774.1 cells. Physiol Genomics 2008; 33:121-32. [DOI: 10.1152/physiolgenomics.00095.2007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Although Escherichia coli LPS is known to elicit various proinflammatory responses in macrophages, its effect on the translational states of transcripts has not yet been explored on a genome-wide scale. To address this, we investigated the mRNA profiles in polysomal and free messenger ribonucleoprotein particle (mRNP) fractions of mouse macrophage-like J774.1 cells, using Affymetrix Mouse Genome 430 2.0 GeneChips. Comparison of the mRNA profiles in total cellular, polysomal, and free mRNP fractions enabled us to identify transcripts that were modulated at the translational level by LPS: among 19,791 transcripts, 115 and 418 were up- and downregulated at 1, 2, or 4 h after LPS stimulation (100 ng/ml) in a translation-dependent manner. Interestingly, gene ontology-based analysis suggested that translation-dependent downregulated genes frequently include those encoding proteins in the mitochondrial respiratory chain. In fact, the mRNA levels of some transcripts for complexes I, IV, and V in the mitochondrial respiratory chain were translationally downregulated, eventually contributing to the decline of their protein levels. Moreover, the amount of metabolically labeled cytochrome oxidase subunit Va in complex IV was decreased without any change of its mRNA level in total cellular fraction after LPS stimulation. Consistently, the total amounts and activities of complexes I and IV were attenuated by LPS stimulation, and the attenuation was independent of nitric oxide. These results demonstrated that translational suppression may play a critical role in the LPS-mediated attenuation of mitochondrial oxidative phosphorylation in a nitric oxide-independent manner in J774.1 cells.
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Affiliation(s)
- Hiroshi Kitamura
- Laboratories for Immunogenomics, RIKEN Research Center for Allergy and Immunology, Yokohama
| | - Masatoshi Ito
- Laboratories for Immunogenomics, RIKEN Research Center for Allergy and Immunology, Yokohama
| | - Tomoko Yuasa
- Laboratories for Immunogenomics, RIKEN Research Center for Allergy and Immunology, Yokohama
| | - Chisato Kikuguchi
- Laboratories for Immunogenomics, RIKEN Research Center for Allergy and Immunology, Yokohama
| | - Atsushi Hijikata
- Laboratories for Immunogenomics, RIKEN Research Center for Allergy and Immunology, Yokohama
| | - Michiyo Takayama
- Laboratories for Immunogenomics, RIKEN Research Center for Allergy and Immunology, Yokohama
| | - Yayoi Kimura
- Laboratories for Immunogenomics, RIKEN Research Center for Allergy and Immunology, Yokohama
| | - Ryo Yokoyama
- Laboratories for Immunogenomics, RIKEN Research Center for Allergy and Immunology, Yokohama
| | - Tomohiro Kaji
- Immunological Memory, RIKEN Research Center for Allergy and Immunology, Yokohama
| | - Osamu Ohara
- Laboratories for Immunogenomics, RIKEN Research Center for Allergy and Immunology, Yokohama
- Laboratory of Genome Technology, Department of Human Genome Research, Kazusa DNA Research Institute, Kisarazu, Japan
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Abstract
Sepsis, the principal cause of death in critically ill patients, is associated with impaired oxygen extraction by tissues. One possible explanation is the development of mitochondrial dysfunction and ineffective oxygen utilization. This abnormality has been termed cytopathic hypoxia. This may be caused by an abnormality in the transport of electrons down the cytochrome chain on the mitochondrial inner membrane. In this article we review our studies on abnormalities in the function of complex IV (cytochrome oxidase), the final electron acceptor in this chain. In addition, we provide evidence that administration of cytochrome c may overcome these abnormalities and provide a novel therapeutic alternative.
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Affiliation(s)
- Richard J Levy
- New York Medical College and Maria Fareri Children's Hospital at Westchester Medical Center, Valhalla, NY, USA
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Piel DA, Gruber PJ, Weinheimer CJ, Courtois MR, Robertson CM, Coopersmith CM, Deutschman CS, Levy RJ. Mitochondrial resuscitation with exogenous cytochrome c in the septic heart. Crit Care Med 2007; 35:2120-7. [PMID: 17855825 DOI: 10.1097/01.ccm.0000278914.85340.fe] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
OBJECTIVE Mitochondrial dysfunction may play a role in the pathogenesis of sepsis-induced organ dysfunction. Respiratory-chain deficiencies that occur in sepsis, however, have never been shown to cause organ failure or to be reversible. Cytochrome oxidase uses electrons donated by its substrate, cytochrome c, to reduce oxygen to H2O. In the septic heart, cytochrome oxidase is competitively inhibited. We hypothesized that cytochrome oxidase inhibition coupled with reduced substrate availability is a reversible cause of sepsis-associated myocardial depression. DESIGN Prospective observational study aimed to overcome myocardial cytochrome oxidase inhibition with excess cytochrome c and improve cardiac function. SETTING University hospital-based laboratory. SUBJECTS Seventy-five C57Bl6 male mice. INTERVENTIONS Mice underwent cecal ligation and double puncture, sham operation, or no operation. Exogenous cytochrome c or an equal volume of saline was intravenously injected at the 24-hr time point. All animals were evaluated 30 mins after injection. MEASUREMENTS AND MAIN RESULTS Exogenous cytochrome c readily repleted cardiac mitochondria with supranormal levels of substrate (>1.6 times baseline), restored heme c content, and increased cytochrome oxidase kinetic activity. This increased left ventricular pressure and increased pressure development during isovolumic contraction (dP/dtmax) and relaxation (dP/dtmin) by >45% compared with saline injection. CONCLUSION Impaired oxidative phosphorylation is a cause of sepsis-associated myocardial depression, and mitochondrial resuscitation with exogenous cytochrome c overcomes cytochrome oxidase inhibition and improves cardiac function.
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Affiliation(s)
- David A Piel
- Department of Anesthesiology and Critical Care Medicine, The Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, USA
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Abstract
Mitochondrial dysfunction is thought to play an important role in the pathogenesis of many different disease states. It has been proposed that an acquired defect in oxidative phosphorylation prevents cells from using molecular oxygen for adenosine triphosphate production and potentially causes sepsis-induced organ dysfunction. This concept, termed cytopathic hypoxia, however, has been difficult to prove because impaired oxidative phosphorylation has never been shown to cause sepsis-induced organ failure or to be a reversible phenomenon. Presented here is are view of oxidative phosphorylation, evidence of defective electron-transport-chain function in the heart and other organ systems during sepsis, and support for a link between mitochondrial dysfunction and pathologic metabolic down-regulation.
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Affiliation(s)
- Richard J Levy
- Department of Anesthesiology and Critical Care Medicine, The Children's Hospital of Philadelphia, University of Pennsylvania, Pennsylvania 19104-4283, USA.
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Wang S, Zhang J, Theel S, Barb JJ, Munson PJ, Danner RL. Nitric oxide activation of Erk1/2 regulates the stability and translation of mRNA transcripts containing CU-rich elements. Nucleic Acids Res 2006; 34:3044-56. [PMID: 16757573 PMCID: PMC1475749 DOI: 10.1093/nar/gkl386] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2006] [Accepted: 05/05/2006] [Indexed: 12/22/2022] Open
Abstract
Nitric oxide (NO*) can stabilize mRNA by activating p38 mitogen-activated protein kinase (MAPK). Here, transcript stabilization by NO* was investigated in human THP-1 cells using microarrays. After LPS pre-stimulation, cells were treated with actinomycin D and then exposed to NO* without or with the p38 MAPK inhibitor SB202190 (SB). The decay of 220 mRNAs was affected; most were stabilized by NO*. Unexpectedly, SB often enhanced rather than antagonized transcript stability. NO* activated p38 MAPK and Erk1/2; SB blocked p38 MAPK, but further activated Erk1/2. RT-PCR confirmed that NO* and SB could additively stabilize certain mRNA transcripts, an effect abolished by Erk1/2 inhibition. In affected genes, these responses were associated with CU-rich elements (CURE) in 3'-untranslated regions (3'-UTR). NO* stabilized the mRNA of a CURE-containing reporter gene, while repressing translation. Dominant-negative Mek1, an Erk1/2 inhibitor, abolished this effect. NO* similarly stabilized, but blocked translation of MAP3K7IP2, a natural CURE-containing gene. NO* increased hnRNP translocation to the cytoplasm and binding to CURE. Over-expression of hnRNP K, like NO*, repressed translation of CURE-containing mRNA. These findings define a sequence-specific mechanism of NO*-triggered gene regulation that stabilizes mRNA, but represses translation.
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Affiliation(s)
- Shuibang Wang
- Critical Care Medicine Department, Clinical Center, National Institutes of HealthBethesda, MD 20892, USA
- Mathematical and Statistical Computing Laboratory, Division of Computational Bioscience, Center for Information Technology, National Institutes of HealthBethesda, MD 20892, USA
| | - Jianhua Zhang
- Critical Care Medicine Department, Clinical Center, National Institutes of HealthBethesda, MD 20892, USA
- Mathematical and Statistical Computing Laboratory, Division of Computational Bioscience, Center for Information Technology, National Institutes of HealthBethesda, MD 20892, USA
| | - Stephanie Theel
- Critical Care Medicine Department, Clinical Center, National Institutes of HealthBethesda, MD 20892, USA
- Mathematical and Statistical Computing Laboratory, Division of Computational Bioscience, Center for Information Technology, National Institutes of HealthBethesda, MD 20892, USA
| | - Jennifer J. Barb
- Mathematical and Statistical Computing Laboratory, Division of Computational Bioscience, Center for Information Technology, National Institutes of HealthBethesda, MD 20892, USA
| | - Peter J. Munson
- Mathematical and Statistical Computing Laboratory, Division of Computational Bioscience, Center for Information Technology, National Institutes of HealthBethesda, MD 20892, USA
| | - Robert L. Danner
- To whom correspondence should be addressed. Tel: +1 301 496 9320; Fax: +1 301 402 1213;
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Ryu SD, Kang JH, Yi HG, Nahm CH, Park CS. Hepatic flavin-containing monooxygenase activity attenuated by cGMP-independent nitric oxide-mediated mRNA destabilization. Biochem Biophys Res Commun 2004; 324:409-16. [PMID: 15465034 DOI: 10.1016/j.bbrc.2004.09.065] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2004] [Indexed: 10/26/2022]
Abstract
To identify the novel mechanism by which nitric oxide (NO) suppresses flavin-containing monooxygenase (FMO) activity in endotoxemic rat livers, NO-overproducing conditions were induced in primary cultured rat hepatocytes by treatment with a mixture (LCM) of lipopolysaccharide and proinflammatory cytokines (IL-1beta, TNF-alpha, and IFN-gamma), or by the addition of a pure NO donor, spermine-NONOate. mRNA levels of the major hepatic form, FMO1, decreased via a cGMP-independent destabilizing effect of NO rather than by decreased transcription. The decrease in the mRNA levels caused by LCM-induced inducible NO synthase (iNOS) was completely blocked by co-treatment with aminoguanidine, a selective iNOS inhibitor. Furthermore, spermine-NONOate, but not the cGMP analog, 8-bromo-cGMP, dose- and time-dependently attenuated FMO1 mRNA stability in actinomycin-D-pretreated cells, resulting in decreases in protein levels and biochemical activity. These results suggest that NO acts directly in a cGMP-independent mechanism by decreasing the half-life of FMO1 mRNA, thereby inducing impairment of FMO-related functions in endotoxemia.
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Affiliation(s)
- Seung-Duk Ryu
- Department of Pharmacology and Toxicology, College of Medicine, Medicinal Toxicology Research Center, CDIR, Inha University, Incheon 400-103, Republic of Korea
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17
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Levy RJ, Vijayasarathy C, Raj NR, Avadhani NG, Deutschman CS. Competitive and Noncompetitive Inhibition of Myocardial Cytochrome C Oxidase in Sepsis. Shock 2004; 21:110-4. [PMID: 14752282 DOI: 10.1097/01.shk.0000108400.56565.ab] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Sepsis is the most common cause of death in intensive care units worldwide. The basic pathophysiologic defect in sepsis, causing functional abnormalities in many organ systems, remains elusive. One potential cause is disruption of oxidative phosphorylation in mitochondria. Here, we report that oxidation of cytochrome c by myocardial cytochrome c oxidase, the terminal oxidase in the electron transport chain, is competitively inhibited early in experimental sepsis (cecal ligation with single or double 23-gauge puncture) in mice. In severe sepsis (cecal ligation and double puncture, 75% mortality at 48 h), inhibition becomes noncompetitive by 48 h. The development of noncompetitive inhibition is associated with a decrease in heme a,a3 content, which is the key active site in the functional subunit (I) and catalyzes the reduction of molecular oxygen. In addition, there are persistently decreased steady-state levels of subunit I mRNA and protein after cecal ligation and double puncture. Both loss of heme and loss of subunit I could explain the observed irreversible inhibition of cytochrome c oxidase. Noncompetitive inhibition of cytochrome c oxidase may interrupt oxidative phosphorylation, leading to sepsis-associated cardiac depression. Importantly, this abnormality may underlie sepsis-associated dysfunction in other organ systems.
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Affiliation(s)
- Richard J Levy
- Department of Anesthesia, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-4283, USA
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18
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Ramachandran A, Ceaser E, Darley-Usmar VM. Chronic exposure to nitric oxide alters the free iron pool in endothelial cells: role of mitochondrial respiratory complexes and heat shock proteins. Proc Natl Acad Sci U S A 2003; 101:384-9. [PMID: 14691259 PMCID: PMC314194 DOI: 10.1073/pnas.0304653101] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The mechanisms of nitric oxide (NO) signaling include binding to the iron centers in soluble guanylate cyclase and cytochrome c oxidase and posttranslational modification of proteins by S-nitrosation. Low levels of NO control mitochondrial number in cells, but little is known of the impact of chronic exposure to high levels of NO on mitochondrial function in endothelial cells. The focus of this study is the interaction of NO with mitochondrial respiratory complexes in cell culture and the effect this has on iron homeostasis. We demonstrate that chronic exposure of endothelial cells to NO decreased activity and protein levels of complexes I, II, and IV, whereas citrate synthase and ATP synthase were unaffected. Inhibition of these respiratory complexes was accompanied by an increase in cellular S-nitrosothiol levels, modification of cysteines residues, and an increase in the labile iron pool. The NO-dependent increase in the free iron pool and inhibition of complex II was prevented by inhibition of mitochondrial protein synthesis, consistent with a major contribution of the organelle to iron homeostasis. In addition, inhibition of mitochondrial protein synthesis was associated with an increase in heat shock protein 60 levels, which may be an additional mechanism leading to preservation of complex II activity.
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Affiliation(s)
- Anup Ramachandran
- Department of Pathology and Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA
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Gao C, Guo H, Wei J, Kuo PC. Osteopontin inhibits expression of cytochrome c oxidase in RAW 264.7 murine macrophages. Biochem Biophys Res Commun 2003; 309:120-5. [PMID: 12943672 DOI: 10.1016/s0006-291x(03)01534-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Osteopontin (OPN) functions as both a cell attachment protein and a cytokine that signals through two CAM molecules: alpha(v)beta(3)-integrin and CD44. OPN initiates a number of signal transduction pathways that control cell survival, proliferation, and migration. In this study, utilizing RAW 264.7 murine macrophages, we demonstrate that expression of the mitochondrial protein, CCOI, is significantly decreased in the setting of OPN stimulation. This effect is blocked by the CD44 competitive ligand, hylauronate; GRGDSP, a hexapeptide that blocks OPN-integrin binding, had no effect. CCOI mRNA and transcription were significantly decreased in the presence of OPN; CCOI mRNA half-life was unaltered by OPN. Additional mitochondrial run-on studies, which included genes from L-strand and H-strand, suggest that OPN terminates transcription of the distal H-strand. CCO enzyme activity was also significantly decreased by OPN. Our results indicate that OPN inhibits CCOI expression as the result of a novel CD44-dependent transcriptional regulatory mechanism of the mitochondrial H strand.
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Affiliation(s)
- Chengjiang Gao
- Department of Surgery, Duke University Medical Center, Durham, NC 27710, USA
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