RESUMEN
The inherent ability of melanoma cells to alter the differentiation-associated transcriptional repertoire to evade treatment and facilitate metastatic spread is well accepted and has been termed phenotypic switching. However, how these facets of cellular behavior are controlled remains largely elusive. Here, we show that cysteine availability, whether from lysosomes (CTNS-dependent) or exogenously derived (SLC7A11-dependent or as N-acetylcysteine), controls melanoma differentiation-associated pathways by acting on the melanocyte master regulator MITF. Functional data indicate that low cysteine availability reduces MITF levels and impairs lysosome functions, which affects tumor ferroptosis sensitivity but improves metastatic spread in vivo. Mechanistically, cysteine-restrictive conditions reduce acetyl-CoA levels to decrease p300-mediated H3K27 acetylation at the melanocyte-restricted MITF promoter, thus forming a cysteine feedforward regulation that controls MITF levels and downstream lysosome functions. These findings collectively suggest that cysteine homeostasis governs melanoma differentiation by maintaining MITF levels and lysosome functions, which protect against ferroptosis and limit metastatic spread.
Asunto(s)
Diferenciación Celular , Cisteína , Lisosomas , Melanoma , Factor de Transcripción Asociado a Microftalmía , Metástasis de la Neoplasia , Melanoma/patología , Melanoma/metabolismo , Melanoma/genética , Humanos , Cisteína/metabolismo , Factor de Transcripción Asociado a Microftalmía/metabolismo , Factor de Transcripción Asociado a Microftalmía/genética , Lisosomas/metabolismo , Línea Celular Tumoral , Animales , Ratones , FerroptosisRESUMEN
In response to cold, mammals activate brown fat for respiratory-dependent thermogenesis reliant on the electron transport chain (1, 2). Yet, the structural basis of respiratory complex adaptation to cold remains elusive. Herein we combined thermoregulatory physiology and cryo-EM to study endogenous respiratory supercomplexes exposed to different temperatures. A cold-induced conformation of CI:III 2 (termed type 2) was identified with a â¼25° rotation of CIII 2 around its inter-dimer axis, shortening inter-complex Q exchange space, and exhibiting different catalytic states which favor electron transfer. Large-scale supercomplex simulations in lipid membrane reveal how unique lipid-protein arrangements stabilize type 2 complexes to enhance catalytic activity. Together, our cryo-EM studies, multiscale simulations and biochemical analyses unveil the mechanisms and dynamics of respiratory adaptation at the structural and energetic level.
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Targeting of specific metabolic pathways in tumor cells has the potential to sensitize them to immune-mediated attack. Here we provide evidence for a specific means of mitochondrial respiratory Complex I (CI) inhibition that improves tumor immunogenicity and sensitivity to immune checkpoint blockade (ICB). Targeted genetic deletion of the CI subunits Ndufs4 and Ndufs6 , but not other subunits, induces an immune-dependent tumor growth attenuation in mouse melanoma models. We show that deletion of Ndufs4 induces expression of the transcription factor Nlrc5 and genes in the MHC class I antigen presentation and processing pathway. This induction of MHC-related genes is driven by an accumulation of pyruvate dehydrogenase-dependent mitochondrial acetyl-CoA downstream of CI subunit deletion. This work provides a novel functional modality by which selective CI inhibition restricts tumor growth, suggesting that specific targeting of Ndufs4 , or related CI subunits, increases T-cell mediated immunity and sensitivity to ICB.
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Mitochondrial diseases are a group of disorders defined by defects in oxidative phosphorylation caused by nuclear- or mitochondrial-encoded gene mutations. A main cellular phenotype of mitochondrial disease mutations is redox imbalances and inflammatory signaling underlying pathogenic signatures of these patients. One method to rescue this cell death vulnerability is the inhibition of mitochondrial translation using tetracyclines. However, the mechanisms whereby tetracyclines promote cell survival are unknown. Here, we show that tetracyclines inhibit the mitochondrial ribosome and promote survival through suppression of endoplasmic reticulum (ER) stress. Tetracyclines increase mitochondrial levels of the mitoribosome quality control factor MALSU1 (Mitochondrial Assembly of Ribosomal Large Subunit 1) and promote its recruitment to the mitoribosome large subunit, where MALSU1 is necessary for tetracycline-induced survival and suppression of ER stress. Glucose starvation induces ER stress to activate the unfolded protein response and IRE1α-mediated cell death that is inhibited by tetracyclines. These studies establish a new interorganelle communication whereby inhibition of the mitoribosome signals to the ER to promote survival, implicating basic mechanisms of cell survival and treatment of mitochondrial diseases.
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Enfermedades Mitocondriales , Ribosomas Mitocondriales , Humanos , Ribosomas Mitocondriales/metabolismo , Ribosomas Mitocondriales/patología , Proteínas Serina-Treonina Quinasas/metabolismo , Supervivencia Celular , Tetraciclinas/farmacología , Tetraciclinas/metabolismo , Endorribonucleasas/genética , Endorribonucleasas/metabolismo , Estrés del Retículo Endoplásmico/genética , Enfermedades Mitocondriales/genéticaRESUMEN
In this issue, Xu and Pan et al1 report a glucose-sensing and activation mechanism of mTORC1 through the glycosyltransferase OGT, which activates Raptor, allowing lysosomal targeting of mTORC1 to promote cell proliferation.
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Glicosiltransferasas , Serina-Treonina Quinasas TOR , Serina-Treonina Quinasas TOR/genética , Diana Mecanicista del Complejo 1 de la Rapamicina/genética , Ciclo Celular , Proliferación CelularRESUMEN
Liver mitochondria undergo architectural remodeling that maintains energy homeostasis in response to feeding and fasting. However, the specific components and molecular mechanisms driving these changes and their impact on energy metabolism remain unclear. Through comparative mouse proteomics, we found that fasting induces strain-specific mitochondrial cristae formation in the liver by upregulating MIC19, a subunit of the MICOS complex. Enforced MIC19 expression in the liver promotes cristae formation, mitochondrial respiration, and fatty acid oxidation while suppressing gluconeogenesis. Mice overexpressing hepatic MIC19 show resistance to diet-induced obesity and improved glucose homeostasis. Interestingly, MIC19 overexpressing mice exhibit elevated energy expenditure and increased pedestrian locomotion. Metabolite profiling revealed that uracil accumulates in the livers of these mice due to increased uridine phosphorylase UPP2 activity. Furthermore, uracil-supplemented diet increases locomotion in wild-type mice. Thus, MIC19-induced mitochondrial cristae formation in the liver increases uracil as a signal to promote locomotion, with protective effects against diet-induced obesity.
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Metabolismo Energético , Hígado , Caminata , Mitocondrias Hepáticas/metabolismo , Hígado/metabolismo , Proteínas Mitocondriales/metabolismo , Proteoma/metabolismo , Animales , Ratones , Dieta Alta en Grasa , Aumento de Peso , Uracilo/metabolismoRESUMEN
While targeted treatment against BRAF(V600E) improve survival for melanoma patients, many will see their cancer recur. Here we provide data indicating that epigenetic suppression of PGC1α defines an aggressive subset of chronic BRAF-inhibitor treated melanomas. A metabolism-centered pharmacological screen further identifies statins (HMGCR inhibitors) as a collateral vulnerability within PGC1α-suppressed BRAF-inhibitor resistant melanomas. Lower PGC1α levels mechanistically causes reduced RAB6B and RAB27A expression, whereby their combined re-expression reverses statin vulnerability. BRAF-inhibitor resistant cells with reduced PGC1α have increased integrin-FAK signaling and improved extracellular matrix detached survival cues that helps explain their increased metastatic ability. Statin treatment blocks cell growth by lowering RAB6B and RAB27A prenylation that reduces their membrane association and affects integrin localization and downstream signaling required for growth. These results suggest that chronic adaptation to BRAF-targeted treatments drive novel collateral metabolic vulnerabilities, and that HMGCR inhibitors may offer a strategy to treat melanomas recurring with suppressed PGC1α expression.
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Inhibidores de Hidroximetilglutaril-CoA Reductasas , Melanoma , Humanos , Proteínas Proto-Oncogénicas B-raf/genética , Proteínas Proto-Oncogénicas B-raf/metabolismo , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/genética , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/metabolismo , Inhibidores de Hidroximetilglutaril-CoA Reductasas/uso terapéutico , Sensibilidad Colateral al uso de Fármacos , Recurrencia Local de Neoplasia , Melanoma/tratamiento farmacológico , Melanoma/genética , Melanoma/patología , Inhibidores de Proteínas Quinasas/farmacología , Integrinas/metabolismo , Epigénesis Genética , Línea Celular Tumoral , Mutación , Hidroximetilglutaril-CoA Reductasas/metabolismoRESUMEN
Mitochondrial diseases are a group of disorders defined by defects in oxidative phosphorylation caused by nuclear- or mitochondrial-encoded gene mutations. A main cellular phenotype of mitochondrial disease mutations are redox imbalances and inflammatory signaling underlying pathogenic signatures of these patients. Depending on the type of mitochondrial mutation, certain mechanisms can efficiently rescue cell death vulnerability. One method is the inhibition of mitochondrial translation elongation using tetracyclines, potent suppressors of cell death in mitochondrial disease mutant cells. However, the mechanisms whereby tetracyclines promote cell survival are unknown. Here, we show that in mitochondrial mutant disease cells, tetracycline-mediated inhibition of mitoribosome elongation promotes survival through suppression of the ER stress IRE1α protein. Tetracyclines increased levels of the splitting factor MALSU1 (Mitochondrial Assembly of Ribosomal Large Subunit 1) at the mitochondria with recruitment to the mitochondrial ribosome (mitoribosome) large subunit. MALSU1, but not other quality control factors, was required for tetracycline-induced cell survival in mitochondrial disease mutant cells during glucose starvation. In these cells, nutrient stress induced cell death through IRE1α activation associated with a strong protein loading in the ER lumen. Notably, tetracyclines rescued cell death through suppression of IRE1α oligomerization and activity. Consistent with MALSU1 requirement, MALSU1 deficient mitochondrial mutant cells were sensitive to glucose-deprivation and exhibited increased ER stress and activation of IRE1α that was not reversed by tetracyclines. These studies show that inhibition of mitoribosome elongation signals to the ER to promote survival, establishing a new interorganelle communication between the mitoribosome and ER with implications in basic mechanisms of cell survival and treatment of mitochondrial diseases.
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Mitochondria provide essential metabolites and adenosine triphosphate (ATP) for the regulation of energy homeostasis. For instance, liver mitochondria are a vital source of gluconeogenic precursors under a fasted state. However, the regulatory mechanisms at the level of mitochondrial membrane transport are not fully understood. Here, we report that a liver-specific mitochondrial inner-membrane carrier SLC25A47 is required for hepatic gluconeogenesis and energy homeostasis. Genome-wide association studies found significant associations between SLC25A47 and fasting glucose, HbA1c, and cholesterol levels in humans. In mice, we demonstrated that liver-specific depletion of SLC25A47 impaired hepatic gluconeogenesis selectively from lactate, while significantly enhancing whole-body energy expenditure and the hepatic expression of FGF21. These metabolic changes were not a consequence of general liver dysfunction because acute SLC25A47 depletion in adult mice was sufficient to enhance hepatic FGF21 production, pyruvate tolerance, and insulin tolerance independent of liver damage and mitochondrial dysfunction. Mechanistically, SLC25A47 depletion leads to impaired hepatic pyruvate flux and malate accumulation in the mitochondria, thereby restricting hepatic gluconeogenesis. Together, the present study identified a crucial node in the liver mitochondria that regulates fasting-induced gluconeogenesis and energy homeostasis.
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Estudio de Asociación del Genoma Completo , Gluconeogénesis , Humanos , Ratones , Animales , Gluconeogénesis/fisiología , Glucosa/metabolismo , Hígado/metabolismo , Metabolismo Energético/fisiología , Piruvatos/metabolismoRESUMEN
Chromophobe (Ch) renal cell carcinoma (RCC) arises from the intercalated cell in the distal nephron. There are no proven treatments for metastatic ChRCC. A distinguishing characteristic of ChRCC is strikingly high levels of reduced (GSH) and oxidized (GSSG) glutathione. Here, we demonstrate that ChRCC-derived cells exhibit higher sensitivity to ferroptotic inducers compared with clear-cell RCC. ChRCC-derived cells are critically dependent on cystine via the cystine/glutamate antiporter xCT to maintain high levels of glutathione, making them sensitive to inhibitors of cystine uptake and cyst(e)inase. Gamma-glutamyl transferase 1 (GGT1), a key enzyme in glutathione homeostasis, is markedly suppressed in ChRCC relative to normal kidney. Importantly, GGT1 overexpression inhibits the proliferation of ChRCC cells in vitro and in vivo, suppresses cystine uptake, and decreases levels of GSH and GSSG. Collectively, these data identify ferroptosis as a metabolic vulnerability in ChRCC, providing a potential avenue for targeted therapy for these distinctive tumors.
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Sistema de Transporte de Aminoácidos y+ , Carcinoma de Células Renales , Cistina , Ferroptosis , Glutatión , Neoplasias Renales , Sistema de Transporte de Aminoácidos y+/metabolismo , Transporte Biológico , Carcinoma de Células Renales/tratamiento farmacológico , Carcinoma de Células Renales/metabolismo , Carcinoma de Células Renales/patología , Cistina/metabolismo , Glutatión/metabolismo , Disulfuro de Glutatión/deficiencia , Humanos , Neoplasias Renales/tratamiento farmacológico , Neoplasias Renales/metabolismo , Neoplasias Renales/patología , Terapia Molecular Dirigida , gamma-Glutamiltransferasa/metabolismoRESUMEN
Mitochondrial energetic adaptations encompass a plethora of conserved processes that maintain cell and organismal fitness and survival in the changing environment by adjusting the respiratory capacity of mitochondria. These mitochondrial responses are governed by general principles of regulatory biology exemplified by changes in gene expression, protein translation, protein complex formation, transmembrane transport, enzymatic activities and metabolite levels. These changes can promote mitochondrial biogenesis and membrane dynamics that in turn support mitochondrial respiration. The main regulatory components of mitochondrial energetic adaptation include: the transcription coactivator peroxisome proliferator-activated receptor-γ (PPARγ) coactivator 1α (PGC1α) and associated transcription factors; mTOR and endoplasmic reticulum stress signalling; TOM70-dependent mitochondrial protein import; the cristae remodelling factors, including mitochondrial contact site and cristae organizing system (MICOS) and OPA1; lipid remodelling; and the assembly and metabolite-dependent regulation of respiratory complexes. These adaptive molecular and structural mechanisms increase respiration to maintain basic processes specific to cell types and tissues. Failure to execute these regulatory responses causes cell damage and inflammation or senescence, compromising cell survival and the ability to adapt to energetically demanding conditions. Thus, mitochondrial adaptive cellular processes are important for physiological responses, including to nutrient availability, temperature and physical activity, and their failure leads to diseases associated with mitochondrial dysfunction such as metabolic and age-associated diseases and cancer.
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Adaptación Fisiológica , Mitocondrias , Mitocondrias/metabolismo , Adaptación Fisiológica/fisiología , Membranas Mitocondriales/metabolismo , Factores de Transcripción/metabolismo , Transducción de Señal , Proteínas Mitocondriales/genéticaRESUMEN
The ability of immune cells to penetrate affected tissues is highly dependent on energy provided by mitochondria, yet their involvement in promoting migration remains unclear. Recent work by Emtenani et al (2022) describes a nuclear Atossa-Porthos axis that adjusts transcription and translation of a small subset of OXPHOS genes to increase mitochondrial bioenergetics and allow macrophage tissue invasion in flies.
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Mitocondrias , Fosforilación Oxidativa , Núcleo Celular/metabolismo , Metabolismo Energético , Macrófagos/metabolismo , Mitocondrias/metabolismoRESUMEN
Mitochondrial dysfunction is increasingly appreciated as a central contributor to human disease. Oxidative metabolism at the mitochondrial respiratory chain produces ATP and is intricately tied to redox homeostasis and biosynthetic pathways. Metabolic stress arising from genetic mutations in mitochondrial genes and environmental factors such as malnutrition or overnutrition is perceived by the cell and leads to adaptive and maladaptive responses that can underlie pathology. Here, we will outline cellular sensors that react to alterations in energy production, organellar redox, and metabolites stemming from mitochondrial disease (MD) mutations. MD is a heterogeneous group of disorders primarily defined by defects in mitochondrial oxidative phosphorylation from nuclear or mitochondrial-encoded gene mutations. Preclinical therapies that improve fitness of MD mouse models have been recently identified. Targeting metabolic/energetic deficiencies, maladaptive signaling processes, and hyper-oxygenation of tissues are all strategies aside from direct genetic approaches that hold therapeutic promise. A further mechanistic understanding of these curative processes as well as the identification of novel targets will significantly impact mitochondrial biology and disease research.
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Enfermedades Mitocondriales , Estrés Oxidativo , Humanos , Animales , Ratones , Especies Reactivas de Oxígeno/metabolismo , Mitocondrias/metabolismo , Metabolismo Energético/genética , Oxidación-Reducción , Enfermedades Mitocondriales/metabolismoRESUMEN
Cannabinoid receptor 1 (CB-1) antagonists are potential candidates for treating obesity and metabolic complications. Despite clear metabolic benefits, unwanted side effects in the brain pose issues for patients. With the hope of overcoming this obstacle, CB-1 in peripheral tissues has become a potential drug target. Previous studies had suggested that liver CB-1 would be an excellent target to prevent development of nonalcoholic steatohepatitis (NAFLD). However, in this issue of the JCI, Wang et al. showed that CB-1 was barely detectable in the liver and deletion of CB-1 in hepatocytes provided no metabolic benefits against NAFLD. These contradictory results raise substantial concerns about the potential benefits of peripheral CB-1 blockers against NAFLD.
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Hígado , Enfermedad del Hígado Graso no Alcohólico , Hepatocitos , Humanos , Enfermedad del Hígado Graso no Alcohólico/tratamiento farmacológico , Obesidad/tratamiento farmacológico , Receptores de CannabinoidesRESUMEN
The protein complexes of the mitochondrial electron transport chain exist in isolation and in higher order assemblies termed supercomplexes (SCs) or respirasomes (SC I+III2+IV). The association of complexes I, III and IV into the respirasome is regulated by unknown mechanisms. Here, we designed a nanoluciferase complementation reporter for complex III and IV proximity to determine in vivo respirasome levels. In a chemical screen, we found that inhibitors of the de novo pyrimidine synthesis enzyme dihydroorotate dehydrogenase (DHODH) potently increased respirasome assembly and activity. By-passing DHODH inhibition via uridine supplementation decreases SC assembly by altering mitochondrial phospholipid composition, specifically elevated peroxisomal-derived ether phospholipids. Cell growth rates upon DHODH inhibition depend on ether lipid synthesis and SC assembly. These data reveal that nucleotide pools signal to peroxisomes to modulate synthesis and transport of ether phospholipids to mitochondria for SC assembly, which are necessary for optimal cell growth in conditions of nucleotide limitation.
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Transporte de Electrón , Nucleótidos/química , Peroxisomas/química , Fosfolípidos/química , Dihidroorotato Deshidrogenasa , Transporte de Electrón/genética , Complejo III de Transporte de Electrones/genética , Complejo IV de Transporte de Electrones/genética , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Lípidos/biosíntesis , Metabolómica , Mitocondrias/metabolismo , Estructura Molecular , Oxidorreductasas actuantes sobre Donantes de Grupo CH-CH/química , Consumo de Oxígeno , Éteres Fosfolípidos , Uridina/metabolismoRESUMEN
The architecture of cristae provides a spatial mitochondrial organization that contains functional respiratory complexes. Several protein components including OPA1 and MICOS complex subunits organize cristae structure, but upstream regulatory mechanisms are largely unknown. Here, in vivo and in vitro reconstitution experiments show that the endoplasmic reticulum (ER) kinase PERK promotes cristae formation by increasing TOM70-assisted mitochondrial import of MIC19, a critical subunit of the MICOS complex. Cold stress or ß-adrenergic stimulation activates PERK that phosphorylates O-linked N-acetylglucosamine transferase (OGT). Phosphorylated OGT glycosylates TOM70 on Ser94, enhancing MIC19 protein import into mitochondria and promoting cristae formation and respiration. In addition, PERK-activated OGT O-GlcNAcylates and attenuates CK2α activity, which mediates TOM70 Ser94 phosphorylation and decreases MIC19 mitochondrial protein import. We have identified a cold-stress inter-organelle PERK-OGT-TOM70 axis that increases cell respiration through mitochondrial protein import and subsequent cristae formation. These studies have significant implications in cellular bioenergetics and adaptations to stress conditions.
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Proteínas del Complejo de Importación de Proteínas Precursoras Mitocondriales/metabolismo , Proteínas Mitocondriales/metabolismo , N-Acetilglucosaminiltransferasas/metabolismo , eIF-2 Quinasa/metabolismo , Adipocitos Marrones/citología , Adipocitos Marrones/efectos de los fármacos , Adipocitos Marrones/metabolismo , Animales , Quinasa de la Caseína II/metabolismo , Frío , Retículo Endoplásmico/metabolismo , Estrés del Retículo Endoplásmico , GTP Fosfohidrolasas/genética , GTP Fosfohidrolasas/metabolismo , Glicosilación , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Mitocondrias/metabolismo , Mitocondrias/patología , Proteínas del Complejo de Importación de Proteínas Precursoras Mitocondriales/genética , Proteínas Mitocondriales/genética , N-Acetilglucosaminiltransferasas/genética , Fosforilación , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Transporte de Proteínas , ARN Guía de Kinetoplastida/metabolismo , eIF-2 Quinasa/antagonistas & inhibidores , eIF-2 Quinasa/deficiencia , eIF-2 Quinasa/genéticaRESUMEN
Despite a myriad of available pharmacotherapies for the treatment of type 2 diabetes (T2D), challenges still exist in achieving glycemic control. Several novel glucose-lowering strategies are currently under clinical investigation, highlighting the need for more robust treatments. Previously, we have shown that suppressing peroxisome proliferator-activated receptor gamma coactivator 1-alpha activity with a small molecule (SR18292, 16) can reduce glucose release from hepatocytes and ameliorate hyperglycemia in diabetic mouse models. Despite structural similarities in 16 to known ß-blockers, detailed structure-activity relationship studies described herein have led to the identification of analogues lacking ß-adrenergic activity that still maintain the ability to suppress glucagon-induced glucose release from hepatocytes and ameliorate hyperglycemia in diabetic mouse models. Hence, these compounds exert their biological effects in a mechanism that does not include adrenergic signaling. These probe molecules may lead to a new therapeutic approach to treat T2D either as a single agent or in combination therapy.
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Glucagón/antagonistas & inhibidores , Gluconeogénesis/efectos de los fármacos , Hipoglucemiantes/farmacología , Indoles/farmacología , Propanoles/farmacología , Adipocitos Marrones/efectos de los fármacos , Adipocitos Marrones/metabolismo , Animales , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Hepatocitos/efectos de los fármacos , Hepatocitos/metabolismo , Hipoglucemiantes/química , Indoles/química , Lipólisis/efectos de los fármacos , Glucógeno Hepático/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , PPAR gamma/efectos de los fármacos , Propanoles/química , Receptores Adrenérgicos beta/efectos de los fármacos , Transducción de Señal/efectos de los fármacos , Relación Estructura-Actividad , Sistema Nervioso Simpático/efectos de los fármacosRESUMEN
Mitochondrial diseases (MDs) are a heterogeneous group of disorders resulting from mutations in nuclear or mitochondrial DNA genes encoding mitochondrial proteins1,2. MDs cause pathologies with severe tissue damage and ultimately death3,4. There are no cures for MDs and current treatments are only palliative5-7. Here we show that tetracyclines improve fitness of cultured MD cells and ameliorate disease in a mouse model of Leigh syndrome. To identify small molecules that prevent cellular damage and death under nutrient stress conditions, we conduct a chemical high-throughput screen with cells carrying human MD mutations and discover a series of antibiotics that maintain survival of various MD cells. We subsequently show that a sub-library of tetracycline analogues, including doxycycline, rescues cell death and inflammatory signatures in mutant cells through partial and selective inhibition of mitochondrial translation, resulting in an ATF4-independent mitohormetic response. Doxycycline treatment strongly promotes fitness and survival of Ndufs4-/- mice, a preclinical Leigh syndrome mouse model8. A proteomic analysis of brain tissue reveals that doxycycline treatment largely prevents neuronal death and the accumulation of neuroimmune and inflammatory proteins in Ndufs4-/- mice, indicating a potential causal role for these proteins in the brain pathology. Our findings suggest that tetracyclines deserve further evaluation as potential drugs for the treatment of MDs.
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Antibacterianos/uso terapéutico , Enfermedades Mitocondriales/tratamiento farmacológico , Tetraciclinas/uso terapéutico , Factor de Transcripción Activador 4/metabolismo , Animales , Encéfalo/patología , Células Cultivadas , Modelos Animales de Enfermedad , Complejo I de Transporte de Electrón/genética , Complejo I de Transporte de Electrón/metabolismo , Ensayos Analíticos de Alto Rendimiento , Humanos , Enfermedad de Leigh/tratamiento farmacológico , Enfermedad de Leigh/patología , Esperanza de Vida , Metabolómica , Ratones , Ratones Noqueados , Enfermedades Mitocondriales/mortalidad , Enfermedades Mitocondriales/patología , Aptitud Física , Análisis de SupervivenciaRESUMEN
General Control Non-repressed 5 protein (GCN5), encoded by the mammalian gene Kat2a, is the first histone acetyltransferase discovered to link histone acetylation to transcriptional activation [1]. The enzymatic activity of GCN5 is linked to cellular metabolic and energetic states regulating gene expression programs. GCN5 has a major impact on energy metabolism by i) sensing acetyl-CoA, a central metabolite and substrate of the GCN5 catalytic reaction, and ii) acetylating proteins such as PGC-1α, a transcriptional coactivator that controls genes linked to energy metabolism and mitochondrial biogenesis. PGC-1α is biochemically associated with the GCN5 protein complex during active metabolic reprogramming. In the first part of the review, we examine how metabolism can change GCN5-dependent histone acetylation to regulate gene expression to adapt cells. In the second part, we summarize the GCN5 function as a nutrient sensor, focusing on non-histone protein acetylation, mainly the metabolic role of PGC-1α acetylation across different tissues.
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Metabolismo Energético/genética , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/metabolismo , Transactivadores/metabolismo , Factores de Transcripción p300-CBP/metabolismo , Acetilcoenzima A/metabolismo , Acetilación , Tejido Adiposo/metabolismo , Animales , Glucosa/metabolismo , Histonas/metabolismo , Humanos , Hígado/metabolismo , Mitocondrias/metabolismo , Nutrientes/metabolismo , Biogénesis de Organelos , Termogénesis/genética , Activación TranscripcionalRESUMEN
The peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) is a transcriptional coactivator that controls expression of metabolic/energetic genes, programming cellular responses to nutrient and environmental adaptations such as fasting, cold, or exercise. Unlike other coactivators, PGC-1α contains protein domains involved in RNA regulation such as serine/arginine (SR) and RNA recognition motifs (RRMs). However, the RNA targets of PGC-1α and how they pertain to metabolism are unknown. To address this, we performed enhanced ultraviolet (UV) cross-linking and immunoprecipitation followed by sequencing (eCLIP-seq) in primary hepatocytes induced with glucagon. A large fraction of RNAs bound to PGC-1α were intronic sequences of genes involved in transcriptional, signaling, or metabolic function linked to glucagon and fasting responses, but were not the canonical direct transcriptional PGC-1α targets such as OXPHOS or gluconeogenic genes. Among the top-scoring RNA sequences bound to PGC-1α were Foxo1, Camk1δ, Per1, Klf15, Pln4, Cluh, Trpc5, Gfra1, and Slc25a25 PGC-1α depletion decreased a fraction of these glucagon-induced messenger RNA (mRNA) transcript levels. Importantly, knockdown of several of these genes affected glucagon-dependent glucose production, a PGC-1α-regulated metabolic pathway. These studies show that PGC-1α binds to intronic RNA sequences, some of them controlling transcript levels associated with glucagon action.