David Cotán

Coenzyme Q deficiency triggers mitochondria degradation by mitophagy

Coenzyme Q10 (CoQ) is a small lipophilic molecule critical for the transport of electrons from complexes I and II to complex III in the mitochondrial respiratory chain. CoQ deficiency is a rare human genetic condition that has been associated with a variety of clinical phenotypes. With the aim of elucidating how CoQ deficiency affects an organism, we have investigated the pathophysiologic processes present within fibroblasts derived from 4 patients with CoQ deficiency. Assays of cultured fibroblasts revealed decreased activities of complex II+III, complex III, and complex IV, reduced expression of mitochondrial proteins involved in oxidative phosphorylation, decreased mitochondrial membrane potential, increased production of reactive oxygen species (ROS), activation of mitochondrial permeability transition (MPT), and reduced growth rates. These abnormalities were partially restored by CoQ supplementation. Moreover, we demonstrate that CoQ deficient fibroblasts exhibited increased levels of lysosomal markers (β-galactosidase, cathepsin, LC3, and Lyso Tracker), and enhanced expression of autophagic genes at both transcriptional and translational levels, indicating the presence of autophagy. Electron microscopy studies confirmed a massive degradation of the altered mitochondria by mitophagy. Autophagy in CoQ deficient fibroblasts was abolished by antioxidants or cyclosporin treatments suggesting that both ROS and MPT participate in this process. Furthermore, prevention of autophagy in CoQ deficient fibroblasts by 3-methyl adenine or wortmannin, as well as the induction of CoQ deficiency in cells lacking autophagy (by means of genetic knockout of the Atg5 gene in mouse embryonic fibroblasts) resulted in apoptotic cell death, suggesting a protective role of autophagy in CoQ deficiency.

Mitochondrial dysfunction and mitophagy activation in blood mononuclear cells of fibromyalgia patients: implications in the pathogenesis of the disease

IntroductionFibromyalgia is a chronic pain syndrome with unknown etiology. Recent studies have shown some evidence demonstrating that oxidative stress may have a role in the pathophysiology of fibromyalgia. However, it is still not clear whether oxidative stress is the cause or the effect of the abnormalities documented in fibromyalgia. Furthermore, the role of mitochondria in the redox imbalance reported in fibromyalgia also is controversial. We undertook this study to investigate the role of mitochondrial dysfunction, oxidative stress, and mitophagy in fibromyalgia.MethodsWe studied 20 patients (2 male, 18 female patients) from the database of the Sevillian Fibromyalgia Association and 10 healthy controls. We evaluated mitochondrial function in blood mononuclear cells from fibromyalgia patients measuring, coenzyme Q10 levels with high-performance liquid chromatography (HPLC), and mitochondrial membrane potential with flow cytometry. Oxidative stress was determined by measuring mitochondrial superoxide production with MitoSOX™ and lipid peroxidation in blood mononuclear cells and plasma from fibromyalgia patients. Autophagy activation was evaluated by quantifying the fluorescence intensity of LysoTracker™ Red staining of blood mononuclear cells. Mitophagy was confirmed by measuring citrate synthase activity and electron microscopy examination of blood mononuclear cells.ResultsWe found reduced levels of coenzyme Q10, decreased mitochondrial membrane potential, increased levels of mitochondrial superoxide in blood mononuclear cells, and increased levels of lipid peroxidation in both blood mononuclear cells and plasma from fibromyalgia patients. Mitochondrial dysfunction was also associated with increased expression of autophagic genes and the elimination of dysfunctional mitochondria with mitophagy.ConclusionsThese findings may support the role of oxidative stress and mitophagy in the pathophysiology of fibromyalgia.

Secondary coenzyme Q10 deficiency triggers mitochondria degradation by mitophagy in MELAS fibroblasts

Mitochondrial encephalomyopathy, lactic acidosis, and stroke‐like episodes (MELAS) is a mitochondrial disease most usually caused by point mutations in tRNA genes encoded by mtDNA. Here, we report on how this mutation affects mitochondrial function in primary fibroblast cultures established from 2 patients with MELAS who harbored the A3243G mutation. Both mitochondrial respiratory chain enzyme activities and coenzyme Q10 (CoQ) levels were significantly decreased in MELAS fibroblasts. A similar decrease in mitochondrial membrane potential was found in intact MELAS fibroblasts. Mitochondrial dysfunction was associated with increased oxidative stress and the activation of mitochondrial permeability transition (MPT), which triggered the degradation of impaired mitochondria. Furthermore, we found defective autophagosome elimination in MELAS fibroblasts. Electron and fluorescence microscopy studies confirmed a massive degradation of mitochondria and accumulation of autophagosomes, suggesting mitophagy activation and deficient autophagic flux. Transmitochondrial cybrids harboring the A3243G mutation also showed CoQ deficiency and increased autophagy activity. All these abnormalities were partially restored by CoQ supplementation. Autophagy in MELAS fibroblasts was also abolished by treatment with antioxidants or cyclosporine, suggesting that both reactive oxygen species and MPT participate in this process. Furthermore, prevention of autophagy in MELAS fibroblasts resulted in apoptotic cell death, suggesting a protective role of autophagy in MELAS fibroblasts.—Cotán, D., Cordero, M. D., Garrido‐Maraver, J., Oropesa‐Ávila, M., Rodríguez‐Hernández, A., Gómez Izquierdo, L., De la Mata, M., De Miguel, M., Bautista Lorite, J., Rivas Infante, E., Jackson, S., Navas, P., Sánchez‐Alcázar, J. A. Secondary coenzyme Q10 deficiency triggers mitochondria degradation by mitophagy in MELAS fibroblasts. FASEB J. 25, 2669–2687 (2011). www.fasebj.org

Pharmacological Chaperones and Coenzyme Q10 Treatment Improves Mutant β-Glucocerebrosidase Activity and Mitochondrial Function in Neuronopathic Forms of Gaucher Disease

Gaucher disease (GD) is caused by mutations in the GBA1 gene, which encodes lysosomal β-glucocerebrosidase. Homozygosity for the L444P mutation in GBA1 is associated with high risk of neurological manifestations which are not improved by enzyme replacement therapy. Alternatively, pharmacological chaperones (PCs) capable of restoring the correct folding and trafficking of the mutant enzyme represent promising alternative therapies.Here, we report on how the L444P mutation affects mitochondrial function in primary fibroblast derived from GD patients. Mitochondrial dysfunction was associated with reduced mitochondrial membrane potential, increased reactive oxygen species (ROS), mitophagy activation and impaired autophagic flux.Both abnormalities, mitochondrial dysfunction and deficient β-glucocerebrosidase activity, were partially restored by supplementation with coenzyme Q10 (CoQ) or a L-idonojirimycin derivative, N-[N’-(4-adamantan-1-ylcarboxamidobutyl)thiocarbamoyl]-1,6-anhydro-L-idonojirimycin (NAdBT-AIJ), and more markedly by the combination of both treatments. These data suggest that targeting both mitochondria function by CoQ and protein misfolding by PCs can be promising therapies in neurological forms of GD.

Coenzyme Q10 Therapy

For a number of years, coenzyme Q10 (CoQ10) was known for its key role in mitochondrial bioenergetics; later studies demonstrated its presence in other subcellular fractions and in blood plasma, and extensively investigated its antioxidant role. These 2 functions constitute the basis for supporting the clinical use of CoQ10. Also, at the inner mitochondrial membrane level, CoQ10 is recognized as an obligatory cofactor for the function of uncoupling proteins and a modulator of the mitochondrial transition pore. Furthermore, recent data indicate that CoQ10 affects the expression of genes involved in human cell signaling, metabolism and transport, and some of the effects of CoQ10 supplementation may be due to this property. CoQ10 deficiencies are due to autosomal recessive mutations, mitochondrial diseases, aging-related oxidative stress and carcinogenesis processes, and also statin treatment. Many neurodegenerative disorders, diabetes, cancer, and muscular and cardiovascular diseases have been associated with low CoQ10 levels as well as different ataxias and encephalomyopathies. CoQ10 treatment does not cause serious adverse effects in humans and new formulations have been developed that increase CoQ10 absorption and tissue distribution. Oral administration of CoQ10 is a frequent antioxidant strategy in many diseases that may provide a significant symptomatic benefit.

Clinical applications of coenzyme Q10.

Coenzyme Q10 (CoQ10) or ubiquinone was known for its key role in mitochondrial bioenergetics as electron and proton carrier; later studies demonstrated its presence in other cellular membranes and in blood plasma, and extensively investigated its antioxidant role. These two functions constitute the basis for supporting the clinical indication of CoQ10. Furthermore, recent data indicate that CoQ10 affects expression of genes involved in human cell signalling, metabolism and transport and some of the effects of CoQ10 supplementation may be due to this property. CoQ10 deficiencies are due to autosomal recessive mutations, mitochondrial diseases, ageing-related oxidative stress and carcinogenesis processes, and also a secondary effect of statin treatment. Many neurodegenerative disorders, diabetes, cancer, fibromyalgia, muscular and cardiovascular diseases have been associated with low CoQ10 levels. CoQ10 treatment does not cause serious adverse effects in humans and new formulations have been developed that increase CoQ10 absorption and tissue distribution. Oral CoQ10 treatment is a frequent mitochondrial energizer and antioxidant strategy in many diseases that may provide a significant symptomatic benefit.

Recovery of MERRF Fibroblasts and Cybrids Pathophysiology by Coenzyme Q10

Mitochondrial DNA mutations are an important cause of human disease for which there is no effective treatment. Myoclonic epilepsy with ragged-red fibers (MERRF) is a mitochondrial disease usually caused by point mutations in transfer RNA genes encoded by mitochondrial DNA. The most common mutation associated with MERRF syndrome, m.8344A > G in the gene MT-TK, which encodes transfer RNALysine, affects the translation of all mitochondrial DNA encoded proteins. This impairs the assembly of the electron transport chain complexes leading to decreased mitochondrial respiratory function. Here we report on how this mutation affects mitochondrial function in primary fibroblast cultures established from patients harboring the A8344G mutation. Coenzyme Q10 (CoQ) levels, as well as mitochondrial respiratory chain activity, and mitochondrial protein expression levels were significantly decreased in MERRF fibroblasts. Mitotracker staining and imaging analysis of individual mitochondria indicated the presence of small, rounded, depolarized mitochondria in MERRF fibroblasts. Mitochondrial dysfunction was associated with increased oxidative stress and increased degradation of impaired mitochondria by mitophagy. Transmitochondrial cybrids harboring the A8344G mutation also showed CoQ deficiency, mitochondrial dysfunction, and increased mitophagy activity. All these abnormalities in patient-derived fibroblasts and cybrids were partially restored by CoQ supplementation, indicating that these cell culture models may be suitable for screening and validation of novel drug candidates for MERRF disease.

Screening of effective pharmacological treatments for MELAS syndrome using yeasts, fibroblasts and cybrid models of the disease.

BACKGROUND AND PURPOSE MELAS (mitochondrial encephalomyopathy, lactic acidosis and stroke‐like episodes) is a mitochondrial disease most usually caused by point mutations in tRNA genes encoded by mitochondrial DNA (mtDNA). Approximately 80% of cases of MELAS syndrome are associated with a m.3243A > G mutation in the MT‐TL1 gene, which encodes the mitochondrial tRNALeu (UUR). Currently, no effective treatments are available for this chronic progressive disorder. Treatment strategies in MELAS and other mitochondrial diseases consist of several drugs that diminish the deleterious effects of the abnormal respiratory chain function, reduce the presence of toxic agents or correct deficiencies in essential cofactors.

Apoptotic microtubule network organization and maintenance depend on high cellular ATP levels and energized mitochondria

Microtubule cytoskeleton is reformed during apoptosis, forming a cortical structure beneath plasma membrane, which plays an important role in preserving cell morphology and plasma membrane integrity. However, the maintenance of the apoptotic microtubule network (AMN) during apoptosis is not understood. In the present study, we examined apoptosis induced by camptothecin (CPT), a topoisomerase I inhibitor, in human H460 and porcine LLCPK-1α cells. We demonstrate that AMN was organized in apoptotic cells with high ATP levels and hyperpolarized mitochondria and, on the contrary, was dismantled in apoptotic cells with low ATP levels and mitochondrial depolarization. AMN disorganization after mitochondrial depolarization was associated with increased plasma membrane permeability assessed by enhancing LDH release and increased intracellular calcium levels. Living cell imaging monitoring of both, microtubule dynamics and mitochondrial membrane potential, showed that AMN persists during apoptosis coinciding with cycles of mitochondrial hyperpolarization. Eventually, AMN was disorganized when mitochondria suffered a large depolarization and cell underwent secondary necrosis. AMN stabilization by taxol prevented LDH release and calcium influx even though mitochondria were depolarized, suggesting that AMN is essential for plasma membrane integrity. Furthermore, high ATP levels and mitochondria polarization collapse after oligomycin treatment in apoptotic cells suggest that ATP synthase works in “reverse” mode during apoptosis. These data provide new explanations for the role of AMN and mitochondria during apoptosis.

Oral coenzyme Q10 supplementation improves clinical symptoms and recovers pathologic alterations in blood mononuclear cells in a fibromyalgia patient

Fibromyalgia (FM) is a chronic pain syndrome with unknown etiology. Recent studies have shown evidence demonstrating that mitochondrial dysfunction and oxidative stress may have a role in the pathophysiology of FM. Coenzyme Q10 (CoQ10) is an essential electron carrier in the mitochondrial respiratory chain and a strong antioxidant. Low CoQ10 levels have been detected in patients with FM, and a significant decrease of clinical symptoms has been reported after oral CoQ10 supplementation. In this report, we show the effect of CoQ10 treatment on clinical symptoms, blood mononuclear cells, and mitochondrial and oxidative stress markers from a woman with FM. After CoQ10 treatment, the patient reported a significant improvement of clinical symptoms. At the cellular level, CoQ10 treatment restored mitochondrial dysfunction and the mtDNA copy number, decreased oxidative stress, and increased mitochondrial biogenesis. Our results suggest that CoQ10 could be an alternative therapeutic approach for FM.