Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:1.9.3.1 (cytochrome oxidase)
8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The central nervous system has a particularly high energy requirement, thus making it very susceptible to defects in mitochondrial function. A number of neurodegenerative diseases, in particular Parkinson's disease (PD), Huntington's disease (HD) and Friedreich's ataxia (FRDA), are associated with mitochondrial dysfunction. The identification of a mitochondrial complex-I defect in PD provides a link between toxin models of the disease, and clues to the pathogenesis of idiopathic PD. We have undertaken genomic transplantation studies involving the transfer of mitochondrial DNA (mtDNA) from PD patients with a complex-I defect to a novel nuclear background. Histochemical, immunohistochemical and functional analysis of the resulting cybrids all showed a pattern in the PD clones indicative of a mtDNA mutation. There is good evidence for the involvement of defective energy metabolism and excitotoxicity in the aetiology of HD. We, and others, have shown a severe deficiency of complex II/III confined to the striatum that mimics the toxin-induced animal models of HD. There is also a milder defect in complex IV in the caudate. The tricarboxylic acid cycle enzyme aconitase is particularly sensitive to inhibition by peroxynitrite and superoxide radicals. We have found this enzyme to be severely decreased in HD caudate, putamen and cortex in a pattern that parallels the severity of neuronal loss seen. We propose a scheme for the role of nitric oxide, free radicals and excitotoxicity in the pathogenesis of HD. FRDA is caused by an expanded GAA repeat in intron 1 of the X25 gene encoding a protein called frataxin. Frataxin is widely expressed and is a mitochondrial protein, although its function is unknown. We have found abnormal magnetic resonance spectroscopy in the skeletal muscle of FRDA patients, which parallels our biochemical findings of reduced complexes I-III in patients' heart and skeletal muscle. There is also reduced aconitase activity in these areas. Increased iron deposition was seen in patients' tissues in a pattern consistent with a mitochondrial location. The mitochondrial iron accumulation, defective respiratory chain activity and aconitase dysfunction suggest that frataxin may be involved in mitochondrial iron regulation. There is also evidence that oxidative stress contributes to cellular toxicity.
...
PMID:Secondary abnormalities of mitochondrial DNA associated with neurodegeneration. 1098 61

Malonate is an inhibitor of cellular metabolism, which, following intrastriatal injection, induces a striatal pathology similar to that seen in Huntington's disease. In two parallel studies, we have investigated the suggested relationship between the neuronal vulnerability to metabolic toxicity and the decline in metabolic function with increasing age. The first experiment investigated malonate-induced neuronal loss in animals aged from 6 weeks up to 27 months, and the second assessed the activities of two mitochondrial enzymes, succinate dehydrogenase and cytochrome oxidase (CYTOX) in animals aged 6 weeks, 3, 8 and 18 months. In the first study, male Lister-Hooded rats received intrastriatal stereotaxic injections of malonate (0.5 or 1.0 M). Animals were killed 10 days after surgery, and the brains were stained with cresyl violet and processed for NADPH-diaphorase activity and glial fibrillary-acidic-protein (GFAP) immunohistochemistry. Animals aged 6 months and older exhibited over 60% striatal neuronal loss. However, the degree of neuronal loss did not show any age-related increase in rats between 6 and 27 months of age, indicating that the extent of malonate-induced toxicity does not increase with age in animals older than 6 months. Infusion of 0.5 M malonate produced smaller lesions, which also demonstrated a consistent extent of neuronal loss from 6 months onwards. Metabolic enzyme activities were decreased in the striatum with increasing age, although this effect was only significant for CYTOX activity. Thus, the pattern of malonate-induced neuronal loss in aged animals partially reflects the changes in metabolic activity during ageing.
...
PMID:Age-dependence of malonate-induced striatal toxicity. 1104 58

Over 100 mutations of mitochondrial DNA (mtDNA) have been associated with human disease. The phenotypic manifestation of mtDNA mutations is extremely broad, from oligosymptomatic patients with isolated deafness, diabetes, ophthalmoplegia, etc., to complex encephalomyopathic disorders that may include dementia, seizures, ataxia, stroke-like episodes, etc. The genotype variants are also wide, with rearrangements (deletions, duplications) and point mutations affecting protein coding genes, tRNAs and rRNAs. There are some broad genotype/phenotype correlations but also substantial overlap. The pathogenetic mechanisms involved in the expression of mtDNA mutations are still not yet fully understood. More recently, mutations of nuclear genes encoding subunits of the respiratory chain, particularly those of complex I, have been identified. These predominantly, but not exclusively, involve infant onset disease with early death. Recently it has become clear that the function of the respiratory chain may be impaired by mutations affecting other mitochondrial proteins or as a secondary phenomenon to other intracellular biochemical derangements. Examples include Friedreich ataxia where a mutation of a nuclear encoded protein (frataxin), probably involved in iron homeostasis in mitochondria, results in severe deficiency of the respiratory chain in a pattern indicative of free radical mediated damage. Mutations of nuclear encoded proteins involved in cytochrome oxidase assembly and maintenance have been characterised and, as predicted, are associated with severe deficiency of cytochrome oxidase and, most frequently, Leigh syndrome. Defects of intracellular metabolism, with particularly excess-free radical generation including nitric oxide or peroxynitrite, may cause secondary damage to the respiratory chain. This is probably of relevance in Huntington disease, motor neuron disease (amyotrophic lateral sclerosis) and Wilson disease. These disorders seem to have defective oxidative phosphorylation as a common pathway in their pathogenesis and it may be that treatments designed to improve respiratory chain function may ameliorate the progression of these disorders.
...
PMID:Primary and secondary defects of the mitochondrial respiratory chain. 1213 29

Cannabinoids could provide neuroprotection in neurodegenerative disorders. In this study, we examined whether a treatment with Delta9-tetrahydrocannabinol, a non-selective cannabinoid receptor agonist, or with SR141716, a selective antagonist for the cannabinoid CB(1) receptor subtype, could affect the toxicity of the complex II reversible inhibitor malonate injected into the striatum, which replicates the mitochondrial complex II deficiency seen in Huntington's disease patients. As expected, malonate injection produced a significant reduction in cytochrome oxidase activity in the striatum consistent with the expected neurodegeneration caused by this toxin. The administration of Delta9-tetrahydrocannabinol increased malonate-induced striatal lesions compared to vehicle and, surprisingly, SR141716, far from producing effects opposite to those of Delta9-tetrahydrocannabinol, also enhanced malonate effects, and to an even greater extent. In summary, our results are compatible with the idea that manipulating the endocannabinoid system can modify neurodegeneration in Huntington's disease, and suggest that highly selective CB(1) receptor agonists might be necessary to produce neuroprotective effects against indirect excitotoxicity.
...
PMID:Effects of cannabinoids in the rat model of Huntington's disease generated by an intrastriatal injection of malonate. 1285 38

Minocycline, a semisynthetic derivative of tetracycline, displays beneficial activity in neuroprotective in models including, Parkinson disease, spinal cord injury, amyotrophic lateral sclerosis, Huntington disease and stroke. The mechanisms by which minocycline inhibits apoptosis remain poorly understood. In the present report we have investigated the effects of minocycline on mitochondria, due to their crucial role in apoptotic pathways. In mitochondria isolated suspensions, minocycline failed to block superoxide-induced swelling but was effective in blocking mitochondrial swelling induced by calcium. This latter effect might be mediated through dissipation of mitochondrial transmembrane potential and blockade of mitochondrial calcium uptake. Consistently, minocycline fails to protect SH-SY5Y cell cultures against reactive oxygen species-mediated cell death, including malonate and 6-hydroxydopamine treatments, but it is effective against staurosporine-induced cytotoxicity. The effects of this antibiotic on mitochondrial respiratory chain complex were also analyzed. Minocycline did not modify complex IV activity, and only at the higher concentration tested (100 microM) inhibited complex II/III activity. Other members of the minocycline antibiotic family like tetracycline failed to induce these mitochondrial effects.
...
PMID:Involvement of mitochondrial potential and calcium buffering capacity in minocycline cytoprotective actions. 1596 87

There is significant evidence that energy production impairment and mitochondrial dysfunction play a role in the pathogenesis of Huntington disease. Nonetheless, the specific mitochondrial defects due to the presence of mutant huntingtin have not been fully elucidated. To determine the effects of mutant huntingtin on mitochondrial energy production, a thorough analysis of respiration, ATP production, and functioning of the respiratory complexes was carried out in clonal striatal cells established from Hdh(Q7) (wild-type) and Hdh(Q111) (mutant huntingtin knock-in) mouse embryos. Mitochondrial respiration and ATP production were significantly reduced in the mutant striatal cells compared with the wild-type cells when either glutamate/malate or succinate was used as the substrate. However, mitochondrial respiration was similar in the two cell lines when the artificial electron donor TMPD/ascorbate, which feeds into complex IV, was used as the substrate. The attenuation of mitochondrial respiration and ATP production when either glutamate/malate or succinate was used as the substrate was not due to impairment of the respiratory complexes, because their activities were equivalent in both cell lines. Intriguingly, in the striatum of presymptomatic and pathological grade 1 Huntington disease cases there is also no impairment of mitochondrial complexes I-IV (Guidetti, P., Charles, V., Chen, E. Y., Reddy, P. H., Kordower, J. H., Whetsell, W. O., Jr., Schwarcz, R., and Tagle, D. A. (2001) Exp. Neurol. 169, 340-350). To our knowledge, this is the first comprehensive analysis of the effects of physiological levels of mutant huntingtin on mitochondrial respiratory function within an appropriate cellular context. These findings demonstrate that the presence of mutant huntingtin impairs mitochondrial ATP production through one or more mechanisms that do not directly affect the function of the respiration complexes.
...
PMID:Mitochondrial respiration and ATP production are significantly impaired in striatal cells expressing mutant huntingtin. 1598 33

We present evidence for a specific role of p53 in the mitochondria-associated cellular dysfunction and behavioral abnormalities of Huntington's disease (HD). Mutant huntingtin (mHtt) with expanded polyglutamine (polyQ) binds to p53 and upregulates levels of nuclear p53 as well as p53 transcriptional activity in neuronal cultures. The augmentation is specific, as it occurs with mHtt but not mutant ataxin-1 with expanded polyQ. p53 levels are also increased in the brains of mHtt transgenic (mHtt-Tg) mice and HD patients. Perturbation of p53 by pifithrin-alpha, RNA interference, or genetic deletion prevents mitochondrial membrane depolarization and cytotoxicity in HD cells, as well as the decreased respiratory complex IV activity of mHtt-Tg mice. Genetic deletion of p53 suppresses neurodegeneration in mHtt-Tg flies and neurobehavioral abnormalities of mHtt-Tg mice. Our findings suggest that p53 links nuclear and mitochondrial pathologies characteristic of HD.
...
PMID:p53 mediates cellular dysfunction and behavioral abnormalities in Huntington's disease. 1599 41

Mitochondrial abnormalities represent a major cytopathology in Huntington's disease (HD), a fatal neurodegenerative disease caused by CAG repeat expansions in the gene encoding huntingtin (Htt). In the present study, we investigated whether defects in the mitochondrial respiratory function are consequences of the expression of mutant Htt or they promote the formation of Htt aggregates. To take advantage of existing mitochondrial DNA mutants, we developed human osteosarcoma 143B cells expressing mutant Htt in an inducible manner and found that cells expressing mutant Htt but not wild-type Htt exhibited a reduced activity of complex III and an increased activity of complex IV. Conversely, pharmacological treatments that inhibited complex III activity significantly promoted the formation of Htt aggregates. This complex III-mediated modulation of Htt aggregates was also observed in a neuronal progenitor RN33B cell line transduced by lentivirus carrying mutant Htt. This effect of complex III inhibition on the Htt aggregates appeared to be mediated by the inhibition of proteasome activity, but not by ATP depletion or production of reactive oxygen species. Accordingly, complex III mutant cells also showed decreased proteasome activity. These results suggest the presence of a feedback system connecting the mitochondrial respiratory complex III and the production of Htt aggregates. Our results suggest that therapeutic interventions targeting complex III and/or proteasome could ameliorate the progress of HD.
...
PMID:Extended polyglutamine repeats trigger a feedback loop involving the mitochondrial complex III, the proteasome and huntingtin aggregates. 1735 14

A semi professional marathon runner at risk for Huntington's disease (HD) (43 CAG repeats) developed signs of a slowly progressive myopathy with exercise-induced muscle fatigue, pain, elevated creatine kinase level, and worsening of his running performance many years before first signs of chorea were detected. Muscle biopsy displayed a mild myopathy with mitochondrial pathology including a complex IV deficiency and analysis of the patient's fibroblast culture demonstrated deficits in mitochondrial function. Challenging skeletal muscle by excessive training might have disclosed myopathy in HD even years before the appearance of other neurological symptoms.
...
PMID:Myopathy as a first symptom of Huntington's disease in a Marathon runner. 1753 45

Altered mitochondrial energy metabolism contributes to the pathophysiology of acute brain injury caused by ischemia, trauma, and neurotoxins and by chronic neurodegenerative disorders such as Parkinson's and Huntington's diseases. Although much evidence supports that the electron transport chain dysfunction in these metabolic abnormalities has both genetic and intracellular environmental causes, alternative mechanisms are being explored. These include direct, reversible inhibition of cytochrome oxidase by nitric oxide, release of mitochondrial cytochrome c, oxidative inhibition of mitochondrial matrix dehydrogenases and adenine nucleotide transport, the availability of NAD for dehydrogenase reactions, respiratory uncoupling by activities such as that of the permeability transition pore, and altered mitochondrial structure and intracellular trafficking. This review focuses on the catabolism of neuronal NAD and the release of neuronal mitochondrial NAD as important contributors to metabolic dysfunction. In addition, the relationship between apoptotic signaling cascades and disruption of mitochondrial energy metabolism is considered in light of the fine balance between apoptotic and necrotic neural cell death.
...
PMID:Mechanisms of impaired mitochondrial energy metabolism in acute and chronic neurodegenerative disorders. 1784 81


<< Previous 1 2 3 4 Next >>

---