Carnitine palmitoyl transferase 2 (CPT2) and very-long-chain Acyl-CoA dehydrogenase (VLCAD) deficiencies are among the most common inborn mitochondrial fatty acid β-oxidation (FAO) disorders. Despite ...advances in their clinical and molecular characterizations, few therapeutic approaches exist for these diseases. Resveratrol (RSV) is a natural polyphenol extensively studied for its potential health benefits. Indeed, it is presently thought that RSV could delay the onset of some cancers, and have protective effects against common aging disorders such as type II diabetes, cardiovascular or neurodegenerative diseases. Here, we show that exposure to RSV induces a dose- and time-dependant increase in FAO flux in human fibroblasts, and can restore normal FAO capacities in a panel of patients' fibroblasts with the mild forms (harboring various genotypes) of CPT2 or VLCAD deficiency. The correction of FAO flux correlated with a marked increase in mutant CPT2 or VLCAD protein level, in cells treated by RSV. Inhibition of sirtuin 1 (SIRT1) by Sirtinol and the use of peroxisome proliferator-activated receptor gamma co-activator-1-alpha (PGC-1α) small interfering RNAs demonstrate that the RSV-induced stimulation of FAO requires the presence of PGC-1α and SIRT1. These results show, for the first time, that RSV markedly induces mitochondrial FAO capacities in human fibroblasts, and provides the initial proof-of-concept that RSV might be efficient for correction of inherited FAO disorders.
Mitochondrial respiratory chain (RC) disorders are the most prevalent inborn metabolic diseases and remain without effective treatment to date. Up-regulation of residual enzyme activity has been ...proposed as a possible therapeutic approach in this group of disorders. As resveratrol (RSV), a natural compound, was proposed to stimulate mitochondrial metabolism in rodents, we tested the effect of this compound on mitochondrial functions in control or in Complex I (CI)- or Complex IV (CIV)-deficient patients' fibroblasts. We show that RSV stimulates the expression of a panel of proteins representing structural subunits or assembly factors of the five RC complexes, in control fibroblasts. In moderate RC-deficient patients' cells, RSV treatment increases the amount of mutated proteins and stimulates residual enzyme activities. In these patients' cells, we establish that up-regulation of RC enzyme activities induced by RSV translates into increased cellular O2 consumption rates and results in the correction of RC deficiencies. Importantly, RSV also prevents the accumulation of lactate that occurred in RC-deficient fibroblasts. Different complementary approaches demonstrate that RSV induces a mitochondrial biogenesis that might underlie the increase in mitochondrial capacities. Finally, we showed that, in human fibroblasts, RSV stimulated mitochondrial functions mainly in a SIRT1- and AMPK-independent manner and that its effects rather involved the estrogen receptor (ER) and estrogen-related receptor alpha (ERRα) signaling pathways. These results represent the first demonstration that RSV could have a beneficial effect on inborn CI and CIV deficiencies from nuclear origin, in human fibroblasts and might be clinically relevant for the treatment of some RC deficiencies.
Carnitine palmitoyltransferase 2 (CPT2) deficiency is a rare mitochondrial fatty acid oxidation (FAO) disorder characterized by myalgia, exercise intolerance, and rhabdomyolysis. We evaluate the ...efficacy of bezafibrate (BZ), a hypolipidemic drug, as a treatment for this form of CPT2 deficiency. A pilot trial was conducted with BZ in six patients for 6 months. There was a follow‐up period of 3 years. The oxidation rates of the long‐chain fatty acid derivative palmitoyl‐CoA, measured in the mitochondria of the patients' muscles, were markedly lower than normal before treatment and increased significantly (+39 to +206% P = 0.028) in all patients after BZ treatment. The evaluation of the therapeutic effects by the patients themselves (using the Short Form Health Survey (SF‐36)), as well as by the physicians, indicated an improvement in the condition of the patients; there was an increase in physical activity and a decline in muscular pain. The results suggest that BZ has a therapeutic effect in the muscular form of CPT2 deficiency.
Clinical Pharmacology & Therapeutics (2010) 88 1, 101–108. doi: 10.1038/clpt.2010.55
Very-long-chain acyl–coenzyme A dehydrogenase (VLCAD) deficiency is an inborn mitochondrial fatty-acid β-oxidation (FAO) defect associated with a broad mutational spectrum, with phenotypes ranging ...from fatal cardiopathy in infancy to adolescent-onset myopathy, and for which there is no established treatment. Recent data suggest that bezafibrate could improve the FAO capacities in β-oxidation–deficient cells, by enhancing the residual level of mutant enzyme activity via gene-expression stimulation. Since VLCAD-deficient patients frequently harbor missense mutations with unpredictable effects on enzyme activity, we investigated the response to bezafibrate as a function of genotype in 33 VLCAD-deficient fibroblasts representing 45 different mutations. Treatment with bezafibrate (400 βM for 48 h) resulted in a marked increase in FAO capacities, often leading to restoration of normal values, for 21 genotypes that mainly corresponded to patients with the myopathic phenotype. In contrast, bezafibrate induced no changes in FAO for 11 genotypes corresponding to severe neonatal or infantile phenotypes. This pattern of response was not due to differential inductions of VLCAD messenger RNA, as shown by quantitative real-time polymerase chain reaction, but reflected variable increases in measured VLCAD residual enzyme activity in response to bezafibrate. Genotype cross-analysis allowed the identification of alleles carrying missense mutations, which could account for these different pharmacological profiles and, on this basis, led to the characterization of 9 mild and 11 severe missense mutations. Altogether, the responses to bezafibrate reflected the severity of the metabolic blockage in various genotypes, which appeared to be correlated with the phenotype, thus providing a new approach for analysis of genetic heterogeneity. Finally, this study emphasizes the potential of bezafibrate, a widely prescribed hypolipidemic drug, for the correction of VLCAD deficiency and exemplifies the integration of molecular information in a therapeutic strategy.
Summary
Enzyme defects in the mitochondrial fatty acid oxidation (FAO) are a large family of inherited metabolic disease well characterized clinically and genetically, but for which pharmacological ...strategies remain limited. It is now well established that regulation of genes involved in mitochondrial FAO is under control of the PPAR (peroxisome proliferator activated receptor) signalling pathway, and this led us to test a possible pharmacological correction of FAO disorders by fibrates and other PPAR activators. This review presents the basic data supporting our initial hypothesis, summarizes the results obtained in cells from patients with CPT II (carnitine palmitoyltransferase II) or VLCAD (very long-chain acyl-CoA dehydrogenase) deficiency, and discusses the perspectives and limits of this approach for therapy of these disorders.
Summary Introduction Obstructive sleep apnoea syndrome (OSAS) constitutes a new major public health problem because of its several pathophysiologic consequences such as cognitive disorders, excessive ...daytime sleepiness with risks of traffic accidents, cardiovascular implications, and decrease of quality of life. The necessity of a gold-standard polysomnography to ensure an accurate diagnosis implies an expensive, technical and time-consuming examination. Thus, it seems logical to develop new systems so as to diagnose SAS and to make it possible to detect apnoeas/hypopnoeas easily during sleep even at home. Aim of the study To assess a novel type-3 portable monitoring (PM) device, the Somnolter, and dedicated automatic analysis of several signals, one of which is the mandibular movement signal. Method We studied patients suffering from OSAS. For all the patients, a nocturnal diagnosis polysomnography (PSG) was recorded in hospital settings, based on six EEG channels, two EOG channels, chin EMG channel, EKG, and respiratory parameters. At the same time, the Somnolter PM device recorded the physiological parameters from its own nasal prongs, thoracic belt, pulse oxymeter, body position, and jaw movement sensors. A visual analysis of PSG recordings was made leading to the detection of apnoea/hypopnoea index (AHI-PSG) and an automatic analysis of the Somnolter traces was performed to get automatic apnoea/hypopnoea index (AHI-A). The added value of the mandible movement signals was the particular jaw movements related to arousals, to respiratory efforts and to sleep/wake state. A comparison was made between the automatic and gold AHIs standard and the correlation was calculated between them. Results Ninety patients, aged between 47 and 70 years (mean age: 55.4 ± 8.7) took part in the study. The linear regression and the correlation coefficient between AHI-PSG and AHI-A showed the good reliability of the automatic method. The Bland Altman analysis shows a correlation of 0.95 with a sensitivity of 83.6 and specificity of 81.8. Conclusion The dedicated automatic analysis based on mandibular movements presents a good potential for the diagnosis of OSAS. The AHI computed by the automatic method is correlated with the AHI-PSG and the Somnolter could easily be used both in hospital, and in ambulatory settings.
Inherited defect in very-long-chain acyl-CoA dehydrogenase (VLCAD), a mitochondrial enzyme catalyzing the initial step of long-chain fatty acid β-oxidation (FAO), is one of the most frequent FAO ...enzyme defects. VLCAD deficiency is associated with clinical manifestations varying in severity, tissue involvement and age of onset. The molecular basis of VLCAD deficiency has been elucidated but therapeutic approaches are quite limited. In this study, we tested the hypothesis that fibrates, acting as agonist of peroxisome proliferator-activated receptors (PPARs), might stimulate FAO in VLCAD-deficient cells. We demonstrate that addition of bezafibrate or fenofibric acid in the culture medium induced a dose-dependent (up to 3-fold) increase in palmitate oxidation capacities in cells from patients with the myopathic form of VLCAD deficiency, but not in cells from severely affected patients. Complete normalization of cell FAO capacities could be achieved after exposure to 500 µm bezafibrate for 48 h. Cell therapy of VLCAD deficiency was related to drug-induced increases in VLCAD mRNA (+44 to +150%; P<0.001), protein (1.5–2-fold) and residual enzyme activity (up to 7.7-fold) in patient cells. Bezafibrate also diminished the production of toxic long-chain acylcarnitines by 90% in cells harboring moderate VLCAD deficiency. Finally, real-time PCR studies indicated that bezafibrate potentially stimulated gene expression of other enzymes in the β-oxidation pathway. These data highlight the potential of fibrates in the correction of inborn FAO defects, as most mutations associated with these defects are compatible with the synthesis of a mutant protein with variable levels of residual enzyme activity.
The peroxisome proliferator-activated receptor alpha (PPARalpha) is a nuclear receptor implicated in the control of cellular lipid utilization. To test the hypothesis that PPARalpha is activated as a ...component of the cellular lipid homeostatic response, the expression of PPARalpha target genes was characterized in response to a perturbation in cellular lipid oxidative flux caused by pharmacologic inhibition of mitochondrial fatty acid import. Inhibition of fatty acid oxidative flux caused a feedback induction of PPARalpha target genes encoding fatty acid oxidation enzymes in liver and heart. In mice lacking PPARalpha (PPARalpha-/-), inhibition of cellular fatty acid flux caused massive hepatic and cardiac lipid accumulation, hypoglycemia, and death in 100% of male, but only 25% of female PPARalpha-/- mice. The metabolic phenotype of male PPARalpha-/- mice was rescued by a 2-wk pretreatment with beta-estradiol. These results demonstrate a pivotal role for PPARalpha in lipid and glucose homeostasis in vivo and implicate estrogen signaling pathways in the regulation of cardiac and hepatic lipid metabolism.
Crisponi syndrome is a rare autosomal recessive disorder characterized by congenital muscular contractions of facial muscles, with trismus in response to stimuli, dysmorphic features, bilateral ...camptodactyly, major feeding and respiratory difficulties, and access of hyperthermia leading to death in the first months of life. The overlap with Stüve-Wiedemann syndrome (SWS) is striking, but the two conditions differ in that congenital lower limb bowing is absent in Crisponi syndrome, whereas it is a cardinal feature of SWS. We report here the exclusion of the leukemia inhibitory factor receptor gene in Crisponi syndrome and the identification of homozygote or compound heterozygote cytokine receptor-like factor 1 (
CRLF1) mutations in four children from three unrelated families. The four mutations were located in the immunoglobulin-like and type III fibronectin domains, and three of them predicted premature termination of translation. Using real-time quantitative polymerase chain reaction, we found a significant decrease in
CRLF1 mRNA expression in patient fibroblasts, which is suggestive of a mutation-mediated decay of the abnormal transcript. CRLF1 forms a heterodimer complex with cardiotrophin-like cytokine factor 1, and this heterodimer competes with ciliary neurotrophic factor for binding to the ciliary neurotrophic factor receptor (CNTFR) complex. The identification of
CRLF1 mutations in Crisponi syndrome supports the key role of the CNTFR pathway in the function of the autonomic nervous system.
Succinate dehydrogenase deficiency in human Brière, J-J; Favier, J; El Ghouzzi, V ...
Cellular and molecular life sciences : CMLS,
10/2005, Letnik:
62, Številka:
19-20
Journal Article
Recenzirano
Mitochondrial succinate dehydrogenase (SDH) consists merely of four nuclearly encoded subunits. It participates in the electron transfer in the respiratory chain and in succinate catabolism in the ...Krebs cycle. Mutations in the four genes, SDHA, B, C and D, have been reported, resulting in strikingly diverse clinical presentations. So far, SDHA mutations have been reported to cause an encephalomyopathy in childhood, while mutations in the genes encoding the other three subunits have been associated only with tumour formation. Following a brief description of SDH genes and subunits, we examine the properties and roles of SDH in the mitochondria. This allows further discussion of the several hypotheses proposed to account for the different clinical presentations resulting from impaired activity of the enzyme. Finally we stress the importance of SDH as a target and/or marker in a number of diseases and the need to better delineate the consequences of SDH deficiency in humans.
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