Autophagy and mitophagy flux disruption in cellular models of MERRF syndrome

Programa de Doctorado en Biotecnología, Ingeniería y TecnologíaLínea de Investigación: Biología Celular, Molecular e Ingeniería GenéticaClave Programa: DBICódigo Línea: 8MERRF (del inglés, Myoclonic Epilepsy with Ragged-Red Fibers) es una de las enfermedades mitocondriales más comunes, principalmente causada por la mutación m.8344A>G en el ADN mitocondrial. Esta mutación afecta a la traducción de proteínas codificadas por el ADN mitocondrial; por lo tanto, el ensamblaje de los complejos de la cadena de transporte de electrones está alterado, provocando una disminución de la función respiratoria mitocondrial. En esta tesis se estudia cómo el flujo autofágico y la degradación selectiva de mitocondrias disfuncionales (mitofagia) son mecanismos esenciales para el balance entre supervivencia y muerte celular en esta enfermedad. Evaluamos los flujos autofágico y mitofágico en cíbridos transmitocondriales y fibroblastos dérmicos procedentes de pacientes con síndrome MERRF, observando que la mitofagia mediada por Parkina está aumentada en los cultivos celulares MERRF con la mutación m.8344A>G. Nuestros resultados sugieren que el tratamiento con coenzima Q10 (CoQ) previene la translocación de Parkina a la mitocondria. Además, la CoQ actúa como un acelerador del flujo autofágico y mitofágico, mejorando la fisiopatología celular. Nuestros hallazgos respaldan la hipótesis de que una autofagia y mitofagia mediada por Parkina reguladas actúan como un mecanismo de supervivencia celular en un contexto de disfunción mitocondrial. Sin embargo, el uso de cíbridos y fibroblastos dérmicos como modelos celulares del síndrome MERRF presenta desventajas, ya que no son las células más afectadas en los pacientes y no son demasiado vulnerables a defectos dependientes de la falta de energía provocada por la disfunción mitocondrial. Por esta razón, en esta tesis se presenta la generación de neuronas inducidas mediante reprogramación celular directa a partir de fibroblastos dérmicos de pacientes con la mutación m.8344A>G. La caracterización fisiopatológica de las neuronas inducidas MERRF indica que éstas pueden constituir un excelente modelo para dilucidar los mecanismos moleculares de la enfermedad, así como una plataforma de cribado para el estudio de moléculas que puedan corregir su fenotipo.Universidad Pablo de Olavide de Sevilla. Departamento de Fisiología, Anatomía y Biología CelularPostprin

Oxidative Stress in Drug-Induced Liver Injury (DILI): From Mechanisms to Biomarkers for Use in Clinical Practice

Idiosyncratic drug-induced liver injury (DILI) is a type of hepatic injury caused by an uncommon drug adverse reaction that can develop to conditions spanning from asymptomatic liver laboratoryabnormalitiestoacuteliverfailure(ALF)anddeath.Thecellularandmolecularmecha- nisms involved in DILI are poorly understood. Hepatocyte damage can be caused by the metabolic activation of chemically active intermediate metabolites that covalently bind to macromolecules (e.g., proteins, DNA), forming protein adducts—neoantigens—that lead to the generation of oxidative stress, mitochondrial dysfunction, and endoplasmic reticulum (ER) stress, which can eventually lead to cell death. In parallel, damage-associated molecular patterns (DAMPs) stimulate the immune response, whereby inflammasomes play a pivotal role, and neoantigen presentation on specific human leukocyte antigen (HLA) molecules trigger the adaptive immune response. A wide array of antioxidant mechanisms exists to counterbalance the effect of oxidants, including glutathione (GSH), superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPX), which are pivotal in detoxification. These get compromised during DILI, triggering an imbalance between oxidants and antioxidants defense systems, generating oxidative stress. As a result of exacerbated oxidative stress, several danger signals, including mitochondrial damage, cell death, and inflammatory markers, and microRNAs (miRNAs) related to extracellular vesicles (EVs) have already been reported as mechanis- tic biomarkers. Here, the status quo and the future directions in DILI are thoroughly discussed, with a special focus on the role of oxidative stress and the development of new biomarkers.This work was supported by the MINECO Retos SAF2016-78711, EXOHEP-CM S2017/BMD- 3727, NanoLiver-CM Y2018/NMT-4949, ERAB Ref. EA 18/14, AMMF 2018/117, FIS-FEDER PI16_01748, PI19-00883, UMA18-FEDERJA-194, PY18-3364_PY19 and UCM-25-2019. FJC is a Ramón y Cajal Researcher RYC-2014-15242 and a Gilead Liver Research 2018. The research group belongs to the validated Research Groups Ref. 970935 “Liver Pathophysiology” and 920631 “Lymphocyte immunobiology” and IBL-6 (imas12-associated). This article/publication is based upon work from COST Action “CA17112—Prospective European Drug-Induced Liver Injury Network” supported by COST (European Cooperation in Science and Technology); www.cost.eu; accessed 4 March 2021. CIBERehd is funded by ISCiii

Critical Review of Gaps in the Diagnosis and Management of Drug-Induced Liver Injury Associated with Severe Cutaneous Adverse Reactions

Drug-induced liver injury (DILI) encompasses the unexpected damage that drugs can cause to the liver. DILI may develop in the context of an immunoallergic syndrome with cutaneous manifes- tations, which are sometimes severe (SCARs). Nevirapine, allopurinol, anti-epileptics, sulfonamides, and antibiotics are the most frequent culprit drugs for DILI associated with SCARs. Interestingly, alleles HLA-B*58:01 and HLA-A*31:01 are associated with both adverse reactions. However, there is no consensus about the criteria used for the characterization of liver injury in this context, and the different thresholds for DILI definition make it difficult to gain insight into this complex disorder. Moreover, current limitations when evaluating causality in patients with DILI associated with SCARs are related to the plethora of causality assessment methods and the lack of consensual complementary tools. Finally, the management of this condition encompasses the treatment of liver and skin injury. Although the use of immunomodulant agents is accepted for SCARs, their role in treating liver injury remains controversial. Further randomized clinical trials are needed to test their efficacy and safety to address this complex entity. Therefore, this review aims to identify the current gaps in the definition, diagnosis, prognosis, and management of DILI associated with SCARs, proposing different strategies to fill in these gaps.Instituto de Salud Carlos III: PI18/01804 Instituto de Salud Carlos III: PI19-00883; Instituto de Salud Carlos III: PT 20/00127; Instituto de Salud Carlos III: UMA18-FEDERJA-194; Instituto de Salud Carlos III: PY18-3364; Consejería de Salud de Andalucía: PI-0310-2018, PEMP-0127-2020; Instituto de Salud Carlos III: Rio Hortega CM17/00243; Instituto de Salud Carlos III: Sara Borrell CD20/00083; Instituto de Salud Carlos III: Sara Borrell CD21/00198

Preclinical models of idiosyncratic drug-induced liver injury (iDILI): Moving towards prediction

Idiosyncratic drug-induced liver injury (iDILI) encompasses the unexpected harms that pre- scription and non-prescription drugs, herbal and dietary supplements can cause to the liver. iDILI remains a major public health problem and a major cause of drug attrition. Given the lack of biomarkers for iDILI prediction, diagnosis and prognosis, searching new models to predict and study mechanisms of iDILI is necessary. One of the major limitations of iDILI preclinical assessment has been the lack of correlation between the markers of hepatotoxicity in animal toxicological studies and clinically significant iDILI. Thus, major advances in the understanding of iDILI susceptibility and pathogenesis have come from the study of well-phenotyped iDILI patients. However, there are many gaps for explaining all the complexity of iDILI susceptibility and mechanisms. Therefore, there is a need to optimize preclinical hu- man in vitro models to reduce the risk of iDILI during drug development. Here, the current experimental models and the future directions in iDILI modelling are thoroughly discussed, focusing on the human cellular models available to study the pathophysiological mechanisms of the disease and the most used in vivo animal iDILI models. We also comment about in silico approaches and the increasing relevance of patient-derived cellular models.This work was supported by grants of Instituto de Salud Carlos III cofounded by Fondo Europeo de Desarrollo Regional-FEDER (contract numbers: PI18/01804, PI19-00883, PT20/00127, UMA18-FEDERJA-194, PY18-3364, Spain) and grants of Consejería de Salud de Andalucía cofounded by FEDER (contract number: PEMP-0127-2020, Spain). M.V.P. holds a Sara Borrell (CD21/00198, Spain) research contract from ISCIII and Consejería de Salud de Andalucía. C.L.G. holds a Juan de la Cierva Incorporación (IJCI-2017-31466, Spain) research contract from Ministerio de Ciencia del Gobierno de España. SCReN and CIBERehd are funded by ISCIII (Spain). This publication is based upon work from COST Action “CA17112dProspective European Drug-Induced Liver Injury Network” supported by COST (European Cooperation in Science and Technology); www.cost.eu. The figures in this review were created with Biorender.com

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 β-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.info:eu-repo/semantics/publishedVersio

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 CoQ 10 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.This work was supported by grants (FIS PI10/00543, FIS EC08/00076) from the Ministerio de Sanidad, Spain, and Fondo Europeo de Desarrollo Regional (FEDER-Unión Europea); Servicio Andaluz de Salud-Junta de Andalucía (SAS 111242); Proyecto de Investigación de Excelencia de la Junta de Andalucía (CTS-5725); and by AEPMI (Asociación de Enfermos de Patología Mitocondrial), FEEL (Fundación Española de Enfermedades Lisosomales) and ALBA Andalucía (Federación Andaluza de Fibromialgia y Fatiga Crónica).Peer Reviewe

Taxonomic singularities of the veil of Flor yeasts in Fino Wines from the D.O. Jerez-Xérèz-Sherry

The veil of “Flor yeasts” are responsible for the biological aging process of wines produced in the D.O. of Jerez and Sanlúcar de Barrameda (Finos and Manzanillas) in the province of Cádiz and Fino in the D.O. Montilla-Moriles in the province of Córdoba, as well as in other wine-growing regions of the world, such as France, South Africa, California, Sardinia or Hungary. The first attempts to classify these flor veil yeasts were based on biochemical assays of sugar assimilation and fermentation. Thus, it was concluded that the yeasts involved in biological aging belonged all to Saccharomyces cerevisiae, distinguishing four subspecies or physiological races: beticus, cheresiensis, montuliensis and rouxii. On the other hand, molecular techniques, which allow the characterization of oenological yeasts and discriminate between the different strains, are usually pulsed field electrophoresis (PFGE), the analysis of the polymorphism for the length of the restriction fragments (RFLP) of mitochondrial DNA, and multiplex PCR of microsatellites. Recent studies in our laboratory show the existence of at least 9 different genotypes of S. cerevisiae veil of flor species, based on the study of microsatellites (SSR-PCR). In addition, we have detected the presence of some species of non-Saccharomyces yeasts not described previously

Cytoskeleton Rearrangements during the Execution Phase of Apoptosis

Apoptosis is a regulated energy‐dependent process for the elimination of unnecessary or damaged cells during embryonic development, tissue homeostasis and many pathological conditions. Apoptosis is characterized by specific morphological and biochemical features in which caspase activation has a pivotal role. During apoptosis, cells undergo characteristic morphological reorganizations in which the cytoskeleton participates actively. Traditionally, this cytoskeleton rearrangement has been assigned mainly to actinomyosin ring contraction, with microtubule and intermediate filaments both reported to be depolymerized at early stages of apoptosis. However, recent results have shown that microtubules are reformed during the execution phase of apoptosis forming an apoptotic microtubule network (AMN). Current hypothesis proposes that AMN is required to maintain plasma membrane integrity and cell morphology during the execution phase of apoptosis. AMN disruption provokes apoptotic cell collapse, secondary necrosis and the subsequent release of toxic molecules which can damage surrounding cells and promote inflammation. Therefore, AMN formation in physiological or pathological apoptosis is essential for tissue homeostasis

Apoptotic cells subjected to cold/warming exposure disorganize apoptotic microtubule network and undergo secondary necrosis

Apoptotic microtubule network (AMN) is organized during apoptosis, forming a cortical structure beneath the plasma membrane which plays a critical role in preserving cell morphology and plasma membrane integrity. The aim of this study was to examine the effect of cold/warming exposure on apoptotic microtubules and plasma membrane integrity during the execution phase of apoptosis. We demonstrated in camptothecin-induced apoptotic H460 cells that cold/warming exposure disorganized apoptotic microtubules and allowed the access of active caspases to the cellular cortex and the cleavage of essential proteins in the preservation of plasma membrane permeability. Cleavage of cellular cortex and plasma membrane proteins, such as ¿-spectrin, paxilin, focal adhesion kinase and calcium ATPase pump (PMCA-4) involved in cell calcium extrusion resulted in increased plasma permeability and calcium overload leading apoptotic cells to secondary necrosis. The essential role of caspase-mediated cleavage in this process was demonstrated because the addition of the pan-caspase inhibitor z-VAD during cold/warming exposure that induces AMN depolymerization avoided the cleavage of cortical and plasma membrane proteins and prevented apoptotic cells to undergo secondary necrosis. Likewise, apoptotic microtubules stabilization by taxol during cold/warming exposure also prevented cellular cortex and plasma membrane protein cleavage and secondary necrosis. Furthermore, microtubules stabilization or caspase inhibition during cold/warming exposure was also critical for proper phosphatidylserine externalization and apoptotic cell clearance by macrophages. These results indicate that cold/warming exposure of apoptotic cells induces secondary necrosis which can be prevented by both, microtubule stabilization or caspase inhibition.This work was supported by FIS PI10/00543 Grant, FIS EC08/00076 Grant, Ministerio de Sanidad, Spain and Fondo Europeo de Desarrollo Regional (FEDER-Unión Europea), SAS 111242 Grant, Servicio Andaluz de Salud-Junta de Andalucía, Proyecto de Investigación de Excelencia de la Junta de Andalucía CTS-5725, and by Asociación de Enfermos de Patología Mitocondrial (AEPMI).Peer Reviewe

The Apoptotic Microtubule Network During the Execution Phase of Apoptosis

Apoptosis is a regulated energy-dependent process of cell death characterized by specific morphological and biochemical features in which caspase activation has a central role. During apoptosis, cells undergo characteristic morphological rearrangements in which the cytoskeleton participates actively. From a historical point of view, this reorganization has been assigned mainly to actinomyosin ring contraction with microtubule and intermediate filaments, both reported to be depolymerized at early stages of apoptosis. However, recent results have shown that the microtubule cytoskeleton is reformed during the execution phase of apoptosis, forming an apoptotic microtubule network (AMN). AMN is closely associated with the plasma membrane, forming a cortical ring or cellular “cocoon.” Apoptotic microtubules’ reorganization has been reported in many cell types and under many apoptotic inducers. Recently, it has been proposed that AMN is essential for preserving plasma membrane permeability and cell morphology during the execution phase of apoptosis. Apoptotic microtubules’ depolymerization leads cells to secondary necrosis and the release of toxic intracellular contents that can harm surrounding cells and initiate inflammation. Therefore, microtubules’ reorganization in physiological apoptosis during development and in the adult organism or in pathological apoptosis induced by anticancer treatments or chronic inflammation is essential for tissue homeostasis, preventing cell damage and inflammation