Atherosclerosis and Coenzyme Q10.

Atherosclerosis is the most common cause of cardiac deaths worldwide. Classically, atherosclerosis has been explained as a simple arterial lipid deposition with concomitant loss of vascular elasticity. Eventually, this condition can lead to consequent blood flow reduction through the affected vessel. However, numerous studies have demonstrated that more factors than lipid accumulation are involved in arterial damage at the cellular level, such as inflammation, autophagy impairment, mitochondrial dysfunction, and/or free-radical overproduction. In order to consider the correction of all of these pathological changes, new approaches in atherosclerosis treatment are necessary. Ubiquinone or coenzyme Q10 is a multifunctional molecule that could theoretically revert most of the cellular alterations found in atherosclerosis, such as cholesterol biosynthesis dysregulation, impaired autophagy flux and mitochondrial dysfunction thanks to its redox and signaling properties. In this review, we will show the latest advances in the knowledge of the relationships between coenzyme Q10 and atherosclerosis. In addition, as atherosclerosis phenotype is closely related to aging, it is reasonable to believe that coenzyme Q10 supplementation could be beneficial for both conditions.

Pantothenate Rescues Iron Accumulation in Pantothenate Kinase-Associated Neurodegeneration Depending on the Type of Mutation.

Neurodegeneration with brain iron accumulation (NBIA) is a group of inherited neurologic disorders in which iron accumulates in the basal ganglia resulting in progressive dystonia, spasticity, parkinsonism, neuropsychiatric abnormalities, and optic atrophy or retinal degeneration. The most prevalent form of NBIA is pantothenate kinase-associated neurodegeneration (PKAN) associated with mutations in the gene of pantothenate kinase 2 (PANK2), which is essential for coenzyme A (CoA) synthesis. There is no cure for NBIA nor is there a standard course of treatment. In the current work, we describe that fibroblasts derived from patients harbouring PANK2 mutations can reproduce many of the cellular pathological alterations found in the disease, such as intracellular iron and lipofuscin accumulation, increased oxidative stress, and mitochondrial dysfunction. Furthermore, mutant fibroblasts showed a characteristic senescent morphology. Treatment with pantothenate, the PANK2 enzyme substrate, was able to correct all pathological alterations in responder mutant fibroblasts with residual PANK2 enzyme expression. However, pantothenate had no effect on mutant fibroblasts with truncated/incomplete protein expression. The positive effect of pantothenate in particular mutations was also confirmed in induced neurons obtained by direct reprograming of mutant fibroblasts. Our results suggest that pantothenate treatment can stabilize the expression levels of PANK2 in selected mutations. These results encourage us to propose our screening model as a quick and easy way to detect pantothenate-responder patients with PANK2 mutations. The existence of residual enzyme expression in some affected individuals raises the possibility of treatment using high dose of pantothenate.

Intracellular cholesterol accumulation and coenzyme Q10 deficiency in Familial Hypercholesterolemia.

Familial Hypercholesterolemia (FH) is an autosomal co-dominant genetic disorder characterized by elevated low-density lipoprotein (LDL) cholesterol levels and increased risk for premature cardiovascular disease. Here, we examined FH pathophysiology in skin fibroblasts derived from FH patients harboring heterozygous mutations in the LDL-receptor. Fibroblasts from FH patients showed a reduced LDL-uptake associated with increased intracellular cholesterol levels and coenzyme Q10 (CoQ10) deficiency, suggesting dysregulation of the mevalonate pathway. Secondary CoQ10 deficiency was associated with mitochondrial depolarization and mitophagy activation in FH fibroblasts. Persistent mitophagy altered autophagy flux and induced inflammasome activation accompanied by increased production of cytokines by mutant cells. All the pathological alterations in FH fibroblasts were also reproduced in a human endothelial cell line by LDL-receptor gene silencing. Both increased intracellular cholesterol and mitochondrial dysfunction in FH fibroblasts were partially restored by CoQ10 supplementation. Dysregulated mevalonate pathway in FH, including increased expression of cholesterogenic enzymes and decreased expression of CoQ10 biosynthetic enzymes, was also corrected by CoQ10 treatment. Reduced CoQ10 content and mitochondrial dysfunction may play an important role in the pathophysiology of early atherosclerosis in FH. The diagnosis of CoQ10 deficiency and mitochondrial impairment in FH patients may also be important to establish early treatment with CoQ10.

Coenzyme Q10 partially restores pathological alterations in a macrophage model of Gaucher disease.

BACKGROUND: Gaucher disease (GD) is caused by mutations in the GBA1 gene which encodes lysosomal ß-glucocerebrosidase (GCase). In GD, partial or complete loss of GCase activity causes the accumulation of the glycolipids glucosylceramide (GlcCer) and glucosylsphingosine in the lysosomes of macrophages. In this manuscript, we investigated the effects of glycolipids accumulation on lysosomal and mitochondrial function, inflammasome activation and efferocytosis capacity in a THP-1 macrophage model of Gaucher disease. In addition, the beneficial effects of coenzyme Q10 (CoQ) supplementation on cellular alterations were evaluated. Chemically-induced Gaucher macrophages were developed by differentiateing THP-1 monocytes to macrophages by treatment with phorbol 12-myristate 13-acetate (PMA) and then inhibiting intracellular GCase with conduritol B-epoxide (CBE), a specific irreversible inhibitor of GCase activity, and supplementing the medium with exogenous GlcCer. This cell model accumulated up to 16-fold more GlcCer compared with control THP-1 cells. RESULTS: Chemically-induced Gaucher macrophages showed impaired autophagy flux associated with mitochondrial dysfunction and increased oxidative stress, inflammasome activation and impaired efferocytosis. All abnormalities were partially restored by supplementation with CoQ. CONCLUSION: These data suggest that targeting mitochondria function and oxidative stress by CoQ can ameliorate the pathological phenotype of Gaucher cells. Chemically-induced Gaucher macrophages provide cellular models that can be used to investigate disease pathogenesis and explore new therapeutics for GD.

AMPK Regulation of Cell Growth, Apoptosis, Autophagy, and Bioenergetics.

In eukaryotic cells, AMP-activated protein kinase (AMPK) generally promotes catabolic pathways that produce ATP and at the same time inhibits anabolic pathways involved in different processes that consume ATP. As an energy sensor, AMPK is involved in the main cellular functions implicated in cell fate, such as cell growth and autophagy.Recently, AMPK has been connected with apoptosis regulation, although the molecular mechanism by which AMPK induces and/or inhibits cell death is not clear.This chapter reviews the essential role of AMPK in signaling pathways that respond to cellular stress and damage, highlighting the complex and reciprocal regulation between AMPK and their targets and effectors. The therapeutic implications of the role of AMPK in different pathologies such as diabetes, cancer, or mitochondrial dysfunctions are still controversial, and it is necessary to further investigate the molecular mechanisms underlying AMPK activation.

Pharmacological Chaperones and Coenzyme Q10 Treatment Improves Mutant ß-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 ß-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 ß-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.

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.

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. EXPERIMENTAL APPROACH: We evaluated the effectiveness of some common pharmacological agents that have been utilized in the treatment of MELAS, in yeast, fibroblast and cybrid models of the disease. The yeast model harbouring the A14G mutation in the mitochondrial tRNALeu(UUR) gene, which is equivalent to the A3243G mutation in humans, was used in the initial screening. Next, the most effective drugs that were able to rescue the respiratory deficiency in MELAS yeast mutants were tested in fibroblasts and cybrid models of MELAS disease. KEY RESULTS: According to our results, supplementation with riboflavin or coenzyme Q(10) effectively reversed the respiratory defect in MELAS yeast and improved the pathologic alterations in MELAS fibroblast and cybrid cell models. CONCLUSIONS AND IMPLICATIONS: Our results indicate that cell models have great potential for screening and validating the effects of novel drug candidates for MELAS treatment and presumably also for other diseases with mitochondrial impairment.

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 RNA(Lysine), 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 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 CoQ10 deficiency, mitochondrial dysfunction, and increased mitophagy activity. All these abnormalities in patient-derived fibroblasts and cybrids were partially restored by CoQ10 supplementation, indicating that these cell culture models may be suitable for screening and validation of novel drug candidates for MERRF disease.

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 Q(10) (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.