RESUMEN
Suspended animation states allow organisms to survive extreme environments. The African turquoise killifish has evolved diapause as a form of suspended development to survive a complete drought. However, the mechanisms underlying the evolution of extreme survival states are unknown. To understand diapause evolution, we performed integrative multi-omics (gene expression, chromatin accessibility, and lipidomics) in the embryos of multiple killifish species. We find that diapause evolved by a recent remodeling of regulatory elements at very ancient gene duplicates (paralogs) present in all vertebrates. CRISPR-Cas9-based perturbations identify the transcription factors REST/NRSF and FOXOs as critical for the diapause gene expression program, including genes involved in lipid metabolism. Indeed, diapause shows a distinct lipid profile, with an increase in triglycerides with very-long-chain fatty acids. Our work suggests a mechanism for the evolution of complex adaptations and offers strategies to promote long-term survival by activating suspended animation programs in other species.
Asunto(s)
Diapausa , Animales , Evolución Biológica , Diapausa/genética , Embrión no Mamífero/metabolismo , Fundulidae/genética , Fundulidae/metabolismo , Regulación del Desarrollo de la Expresión Génica , Peces Killi/genética , Peces Killi/metabolismo , Metabolismo de los Lípidos/genética , Proteínas de Peces/genética , Masculino , FemeninoRESUMEN
Mitochondria are essential metabolic hubs that dynamically adapt to physiological demands. More than 40 proteases residing in different compartments of mitochondria, termed mitoproteases, preserve mitochondrial proteostasis and are emerging as central regulators of mitochondrial plasticity. These multifaceted enzymes limit the accumulation of short-lived, regulatory proteins within mitochondria, modulate the activity of mitochondrial proteins by protein processing, and mediate the degradation of damaged proteins. Various signaling cascades coordinate the activity of mitoproteases to preserve mitochondrial homeostasis and ensure cell survival. Loss of mitoproteases severely impairs the functional integrity of mitochondria, is associated with aging, and causes pleiotropic diseases. Understanding the dual function of mitoproteases as regulatory and quality control enzymes will help unravel the role of mitochondrial plasticity in aging and disease.
Asunto(s)
Envejecimiento/genética , Mitocondrias/genética , Proteínas Mitocondriales/química , Neoplasias/genética , Enfermedades Neurodegenerativas/genética , Péptido Hidrolasas/química , Envejecimiento/metabolismo , Animales , Apoptosis/genética , Regulación de la Expresión Génica , Homeostasis/genética , Humanos , Metabolismo de los Lípidos/genética , Mitocondrias/enzimología , Dinámicas Mitocondriales/genética , Proteínas Mitocondriales/genética , Proteínas Mitocondriales/metabolismo , Mitofagia/genética , Neoplasias/enzimología , Neoplasias/patología , Enfermedades Neurodegenerativas/enzimología , Enfermedades Neurodegenerativas/patología , Péptido Hidrolasas/genética , Péptido Hidrolasas/metabolismo , Fosfolípidos/metabolismo , Proteolisis , Proteostasis/genéticaRESUMEN
Human cells are able to sense and adapt to variations in oxygen levels. Historically, much research in this field has focused on hypoxia-inducible factor (HIF) signaling and reactive oxygen species (ROS). Here, we perform genome-wide CRISPR growth screens at 21%, 5%, and 1% oxygen to systematically identify gene knockouts with relative fitness defects in high oxygen (213 genes) or low oxygen (109 genes), most without known connection to HIF or ROS. Knockouts of many mitochondrial pathways thought to be essential, including complex I and enzymes in Fe-S biosynthesis, grow relatively well at low oxygen and thus are buffered by hypoxia. In contrast, in certain cell types, knockout of lipid biosynthetic and peroxisomal genes causes fitness defects only in low oxygen. Our resource nominates genetic diseases whose severity may be modulated by oxygen and links hundreds of genes to oxygen homeostasis.
Asunto(s)
Metabolismo de los Lípidos/genética , Mitocondrias/genética , Oxígeno/metabolismo , Transcriptoma/genética , Hipoxia de la Célula , Pruebas Genéticas/métodos , Estudio de Asociación del Genoma Completo/métodos , Células HEK293 , Humanos , Hipoxia/metabolismo , Células K562 , Metabolismo de los Lípidos/fisiología , Lípidos/genética , Lípidos/fisiología , Mitocondrias/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Transducción de Señal/fisiologíaRESUMEN
Immune cells residing in white adipose tissue have been highlighted as important factors contributing to the pathogenesis of metabolic diseases, but the molecular regulators that drive adipose tissue immune cell remodeling during obesity remain largely unknown. Using index and transcriptional single-cell sorting, we comprehensively map all adipose tissue immune populations in both mice and humans during obesity. We describe a novel and conserved Trem2+ lipid-associated macrophage (LAM) subset and identify markers, spatial localization, origin, and functional pathways associated with these cells. Genetic ablation of Trem2 in mice globally inhibits the downstream molecular LAM program, leading to adipocyte hypertrophy as well as systemic hypercholesterolemia, body fat accumulation, and glucose intolerance. These findings identify Trem2 signaling as a major pathway by which macrophages respond to loss of tissue-level lipid homeostasis, highlighting Trem2 as a key sensor of metabolic pathologies across multiple tissues and a potential therapeutic target in metabolic diseases.
Asunto(s)
Macrófagos/metabolismo , Glicoproteínas de Membrana/metabolismo , Receptores Inmunológicos/metabolismo , Tejido Adiposo Blanco/metabolismo , Tejido Adiposo Blanco/patología , Animales , Dieta Alta en Grasa , Intolerancia a la Glucosa , Humanos , Grasa Intraabdominal/metabolismo , Grasa Intraabdominal/patología , Metabolismo de los Lípidos/genética , Lípidos/análisis , Macrófagos/citología , Glicoproteínas de Membrana/deficiencia , Glicoproteínas de Membrana/genética , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Monocitos/citología , Monocitos/metabolismo , Obesidad/metabolismo , Obesidad/patología , Receptores Inmunológicos/deficiencia , Receptores Inmunológicos/genética , Transducción de Señal , Análisis de la Célula IndividualRESUMEN
In animals, systemic control of metabolism is conducted by metabolic tissues and relies on the regulated circulation of a plethora of molecules, such as hormones and lipoprotein complexes. MicroRNAs (miRNAs) are a family of post-transcriptional gene repressors that are present throughout the animal kingdom and have been widely associated with the regulation of gene expression in various contexts, including virtually all aspects of systemic control of metabolism. Here we focus on glucose and lipid metabolism and review current knowledge of the role of miRNAs in their systemic regulation. We survey miRNA-mediated regulation of healthy metabolism as well as the contribution of miRNAs to metabolic dysfunction in disease, particularly diabetes, obesity and liver disease. Although most miRNAs act on the tissue they are produced in, it is now well established that miRNAs can also circulate in bodily fluids, including their intercellular transport by extracellular vesicles, and we discuss the role of such extracellular miRNAs in systemic metabolic control and as potential biomarkers of metabolic status and metabolic disease.
Asunto(s)
Glucosa/metabolismo , MicroARNs/metabolismo , Animales , Humanos , Metabolismo de los Lípidos/genética , Metabolismo de los Lípidos/fisiología , Enfermedades Metabólicas/metabolismoRESUMEN
Depleting regulatory T cells (Treg cells) to counteract immunosuppressive features of the tumor microenvironment (TME) is an attractive strategy for cancer treatment; however, autoimmunity due to systemic impairment of their suppressive function limits its therapeutic potential. Elucidating approaches that specifically disrupt intratumoral Treg cells is direly needed for cancer immunotherapy. We found that CD36 was selectively upregulated in intrautumoral Treg cells as a central metabolic modulator. CD36 fine-tuned mitochondrial fitness via peroxisome proliferator-activated receptor-ß signaling, programming Treg cells to adapt to a lactic acid-enriched TME. Genetic ablation of Cd36 in Treg cells suppressed tumor growth accompanied by a decrease in intratumoral Treg cells and enhancement of antitumor activity in tumor-infiltrating lymphocytes without disrupting immune homeostasis. Furthermore, CD36 targeting elicited additive antitumor responses with anti-programmed cell death protein 1 therapy. Our findings uncover the unexplored metabolic adaptation that orchestrates the survival and functions of intratumoral Treg cells, and the therapeutic potential of targeting this pathway for reprogramming the TME.
Asunto(s)
Antígenos CD36/inmunología , Neoplasias/inmunología , Linfocitos T Reguladores/inmunología , Animales , Apoptosis/inmunología , Antígenos CD36/deficiencia , Antígenos CD36/genética , Línea Celular Tumoral , Femenino , Homeostasis/inmunología , Humanos , Inmunoterapia , Metabolismo de los Lípidos/genética , Linfocitos Infiltrantes de Tumor/inmunología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Neoplasias/metabolismo , Neoplasias/patología , PPAR-beta/inmunología , Transducción de Señal/inmunología , Linfocitos T Reguladores/metabolismo , Linfocitos T Reguladores/patología , Microambiente Tumoral/inmunologíaRESUMEN
The ability to sense and respond to proteotoxic insults declines with age, leaving cells vulnerable to chronic and acute stressors. Reproductive cues modulate this decline in cellular proteostasis to influence organismal stress resilience in Caenorhabditis elegans We previously uncovered a pathway that links the integrity of developing embryos to somatic health in reproductive adults. Here, we show that the nuclear receptor NHR-49, an ortholog of mammalian peroxisome proliferator-activated receptor α (PPARα), regulates stress resilience and proteostasis downstream from embryo integrity and other pathways that influence lipid homeostasis and upstream of HSF-1. Disruption of the vitelline layer of the embryo envelope, which activates a proteostasis-enhancing intertissue pathway in somatic cells, triggers changes in lipid catabolism gene expression that are accompanied by an increase in fat stores. NHR-49, together with its coactivator, MDT-15, contributes to this remodeling of lipid metabolism and is also important for the elevated stress resilience mediated by inhibition of the embryonic vitelline layer. Our findings indicate that NHR-49 also contributes to stress resilience in other pathways known to change lipid homeostasis, including reduced insulin-like signaling and fasting, and that increased NHR-49 activity is sufficient to improve proteostasis and stress resilience in an HSF-1-dependent manner. Together, our results establish NHR-49 as a key regulator that links lipid homeostasis and cellular resilience to proteotoxic stress.
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Proteínas de Caenorhabditis elegans , Caenorhabditis elegans , Metabolismo de los Lípidos , Proteostasis , Receptores Citoplasmáticos y Nucleares , Reproducción , Transducción de Señal , Estrés Fisiológico , Animales , Caenorhabditis elegans/genética , Caenorhabditis elegans/fisiología , Proteínas de Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Metabolismo de los Lípidos/genética , Receptores Citoplasmáticos y Nucleares/metabolismo , Receptores Citoplasmáticos y Nucleares/genética , Reproducción/genética , Reproducción/fisiología , Complejo Mediador/genética , Complejo Mediador/metabolismoRESUMEN
Defects in mitochondrial metabolism have been increasingly linked with age-onset protein-misfolding diseases such as Alzheimer's, Parkinson's, and Huntington's. In response to protein-folding stress, compartment-specific unfolded protein responses (UPRs) within the ER, mitochondria, and cytosol work in parallel to ensure cellular protein homeostasis. While perturbation of individual compartments can make other compartments more susceptible to protein stress, the cellular conditions that trigger cross-communication between the individual UPRs remain poorly understood. We have uncovered a conserved, robust mechanism linking mitochondrial protein homeostasis and the cytosolic folding environment through changes in lipid homeostasis. Metabolic restructuring caused by mitochondrial stress or small-molecule activators trigger changes in gene expression coordinated uniquely by both the mitochondrial and cytosolic UPRs, protecting the cell from disease-associated proteins. Our data suggest an intricate and unique system of communication between UPRs in response to metabolic changes that could unveil new targets for diseases of protein misfolding.
Asunto(s)
Citosol/fisiología , Respuesta al Choque Térmico/fisiología , Lípidos/biosíntesis , Mitocondrias/fisiología , Respuesta de Proteína Desplegada/fisiología , Animales , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Línea Celular , Regulación de la Expresión Génica , Técnicas de Silenciamiento del Gen , Proteínas de Choque Térmico/genética , Homeostasis , Humanos , Metabolismo de los Lípidos/genética , Proteínas Mitocondriales/metabolismo , Chaperonas Moleculares/genética , Pliegue de ProteínaRESUMEN
Fasting is associated with a range of health benefits1-6. How fasting signals elicit changes in the proteome to establish metabolic programmes remains poorly understood. Here we show that hepatocytes selectively remodel the translatome while global translation is paradoxically downregulated during fasting7,8. We discover that phosphorylation of eukaryotic translation initiation factor 4E (P-eIF4E) is induced during fasting. We show that P-eIF4E is responsible for controlling the translation of genes involved in lipid catabolism and the production of ketone bodies. Inhibiting P-eIF4E impairs ketogenesis in response to fasting and a ketogenic diet. P-eIF4E regulates those messenger RNAs through a specific translation regulatory element within their 5' untranslated regions (5' UTRs). Our findings reveal a new signalling property of fatty acids, which are elevated during fasting. We found that fatty acids bind and induce AMP-activated protein kinase (AMPK) kinase activity that in turn enhances the phosphorylation of MAP kinase-interacting protein kinase (MNK), the kinase that phosphorylates eIF4E. The AMPK-MNK-eIF4E axis controls ketogenesis, revealing a new lipid-mediated kinase signalling pathway that links ketogenesis to translation control. Certain types of cancer use ketone bodies as an energy source9,10 that may rely on P-eIF4E. Our findings reveal that on a ketogenic diet, treatment with eFT508 (also known as tomivosertib; a P-eIF4E inhibitor) restrains pancreatic tumour growth. Thus, our findings unveil a new fatty acid-induced signalling pathway that activates selective translation, which underlies ketogenesis and provides a tailored diet intervention therapy for cancer.
Asunto(s)
Carcinogénesis , Ácidos Grasos , Cuerpos Cetónicos , Biosíntesis de Proteínas , Transducción de Señal , Animales , Femenino , Humanos , Ratones , Regiones no Traducidas 5'/genética , Proteínas Quinasas Activadas por AMP/metabolismo , Carcinogénesis/genética , Carcinogénesis/metabolismo , Dieta Cetogénica , Factor 4E Eucariótico de Iniciación/química , Factor 4E Eucariótico de Iniciación/metabolismo , Ayuno/fisiología , Ácidos Grasos/metabolismo , Hepatocitos/metabolismo , Cuerpos Cetónicos/biosíntesis , Cuerpos Cetónicos/metabolismo , Metabolismo de los Lípidos/genética , Neoplasias Pancreáticas/dietoterapia , Neoplasias Pancreáticas/tratamiento farmacológico , Neoplasias Pancreáticas/patología , Fosforilación/efectos de los fármacos , Proteínas Serina-Treonina Quinasas/química , Proteínas Serina-Treonina Quinasas/metabolismoRESUMEN
Acetyl-CoA is a key intermediate situated at the intersection of many metabolic pathways. The reliance of histone acetylation on acetyl-CoA enables the coordination of gene expression with metabolic state. Abundant acetyl-CoA has been linked to the activation of genes involved in cell growth or tumorigenesis through histone acetylation. However, the role of histone acetylation in transcription under low levels of acetyl-CoA remains poorly understood. Here, we use a yeast starvation model to observe the dramatic alteration in the global occupancy of histone acetylation following carbon starvation; the location of histone acetylation marks shifts from growth-promoting genes to gluconeogenic and fat metabolism genes. This reallocation is mediated by both the histone deacetylase Rpd3p and the acetyltransferase Gcn5p, a component of the SAGA transcriptional coactivator. Our findings reveal an unexpected switch in the specificity of histone acetylation to promote pathways that generate acetyl-CoA for oxidation when acetyl-CoA is limiting.
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Gluconeogénesis , Glucosa/deficiencia , Histonas/metabolismo , Metabolismo de los Lípidos , Procesamiento Proteico-Postraduccional , Saccharomyces cerevisiae/metabolismo , Acetilcoenzima A/metabolismo , Acetilación , Regulación Fúngica de la Expresión Génica , Histona Acetiltransferasas/genética , Histona Acetiltransferasas/metabolismo , Histona Desacetilasas/genética , Histona Desacetilasas/metabolismo , Metabolismo de los Lípidos/genética , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Transactivadores/genética , Transactivadores/metabolismoRESUMEN
Mycobacterium tuberculosis (Mtb) survives in macrophages by evading delivery to the lysosome and promoting the accumulation of lipid bodies, which serve as a bacterial source of nutrients. We found that by inducing the microRNA (miRNA) miR-33 and its passenger strand miR-33*, Mtb inhibited integrated pathways involved in autophagy, lysosomal function and fatty acid oxidation to support bacterial replication. Silencing of miR-33 and miR-33* by genetic or pharmacological means promoted autophagy flux through derepression of key autophagy effectors (such as ATG5, ATG12, LC3B and LAMP1) and AMPK-dependent activation of the transcription factors FOXO3 and TFEB, which enhanced lipid catabolism and Mtb xenophagy. These data define a mammalian miRNA circuit used by Mtb to coordinately inhibit autophagy and reprogram host lipid metabolism to enable intracellular survival and persistence in the host.
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Autofagia/genética , Metabolismo de los Lípidos/genética , Lisosomas/fisiología , Macrófagos/fisiología , MicroARNs/metabolismo , Mycobacterium tuberculosis/fisiología , Tuberculosis/genética , Animales , Células Cultivadas , Interacciones Huésped-Patógeno , Humanos , Evasión Inmune , Lisosomas/microbiología , Macrófagos/microbiología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , MicroARNs/genética , Transducción de Señal , Factores de Transcripción/metabolismoRESUMEN
Single-nucleotide variations in C13orf31 (LACC1) that encode p.C284R and p.I254V in a protein of unknown function (called 'FAMIN' here) are associated with increased risk for systemic juvenile idiopathic arthritis, leprosy and Crohn's disease. Here we set out to identify the biological mechanism affected by these coding variations. FAMIN formed a complex with fatty acid synthase (FASN) on peroxisomes and promoted flux through de novo lipogenesis to concomitantly drive high levels of fatty-acid oxidation (FAO) and glycolysis and, consequently, ATP regeneration. FAMIN-dependent FAO controlled inflammasome activation, mitochondrial and NADPH-oxidase-dependent production of reactive oxygen species (ROS), and the bactericidal activity of macrophages. As p.I254V and p.C284R resulted in diminished function and loss of function, respectively, FAMIN determined resilience to endotoxin shock. Thus, we have identified a central regulator of the metabolic function and bioenergetic state of macrophages that is under evolutionary selection and determines the risk of inflammatory and infectious disease.
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Artritis Juvenil/genética , Enfermedad de Crohn/genética , Infecciones/genética , Lepra/genética , Macrófagos/inmunología , Proteínas/genética , Choque Séptico/genética , Adenosina Trifosfato/metabolismo , Animales , Bacteriólisis , Células Cultivadas , Metabolismo Energético , Acido Graso Sintasa Tipo I/metabolismo , Predisposición Genética a la Enfermedad , Humanos , Inflamasomas/metabolismo , Péptidos y Proteínas de Señalización Intracelular , Metabolismo de los Lípidos/genética , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , NADPH Oxidasas/metabolismo , Oxidación-Reducción , Polimorfismo de Nucleótido Simple , RiesgoRESUMEN
Naive CD4+ T cells differentiate into functionally diverse T helper (Th) cell subsets. Th2 cells play a pathogenic role in asthma, yet a clear picture of their transcriptional profile is lacking. We performed single-cell RNA sequencing (scRNA-seq) of T helper cells from lymph node, lung, and airways in the house dust mite (HDM) model of allergic airway disease. scRNA-seq resolved transcriptional profiles of naive CD4+ T, Th1, Th2, regulatory T (Treg) cells, and a CD4+ T cell population responsive to type I interferons. Th2 cells in the airways were enriched for transcription of many genes, including Cd200r1, Il6, Plac8, and Igfbp7, and their mRNA profile was supported by analysis of chromatin accessibility and flow cytometry. Pathways associated with lipid metabolism were enriched in Th2 cells, and experiments with inhibitors of key metabolic pathways supported roles for glucose and lipid metabolism. These findings provide insight into the differentiation of pathogenic Th2 cells in the context of allergy.
Asunto(s)
Asma/inmunología , Hipersensibilidad Respiratoria/inmunología , Sistema Respiratorio/inmunología , Subgrupos de Linfocitos T/inmunología , Células Th2/inmunología , Animales , Antígenos Dermatofagoides/inmunología , Modelos Animales de Enfermedad , Humanos , Metabolismo de los Lípidos/genética , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Receptores de Orexina/genética , Pyroglyphidae/inmunología , Análisis de Secuencia de ARN , Análisis de la Célula Individual , TranscriptomaRESUMEN
In eukaryotes, gene expression is performed by three RNA polymerases that are targeted to promoters by molecular complexes. A unique common factor, the TATA-box binding protein (TBP), is thought to serve as a platform to assemble pre-initiation complexes competent for transcription. Here, we describe a novel molecular mechanism of nutrient regulation of gene transcription by dynamic O-GlcNAcylation of TBP. We show that O-GlcNAcylation at T114 of TBP blocks its interaction with BTAF1, hence the formation of the B-TFIID complex, and its dynamic cycling on and off of DNA. Transcriptomic and metabolomic analyses of TBPT114A CRISPR/Cas9-edited cells showed that loss of O-GlcNAcylation at T114 increases TBP binding to BTAF1 and directly impacts expression of 408 genes. Lack of O-GlcNAcylation at T114 is associated with a striking reprogramming of cellular metabolism induced by a profound modification of the transcriptome, leading to gross alterations in lipid storage.
Asunto(s)
Glucosa/metabolismo , Gotas Lipídicas/metabolismo , Metabolismo de los Lípidos , Factores Asociados con la Proteína de Unión a TATA/metabolismo , Proteína de Unión a TATA-Box/metabolismo , Factor de Transcripción TFIID/metabolismo , Animales , Cromatina/genética , Cromatina/metabolismo , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Experimental/metabolismo , Regulación de la Expresión Génica , Glicosilación , Células HEK293 , Células HeLa , Humanos , Metabolismo de los Lípidos/genética , Masculino , Complejos Multiproteicos , Ratas Sprague-Dawley , Transducción de Señal , Factores Asociados con la Proteína de Unión a TATA/genética , Proteína de Unión a TATA-Box/genética , Factores de Tiempo , Factor de Transcripción TFIID/genética , Transcripción Genética , TranscriptomaRESUMEN
Human cancers with activating RAS mutations are typically highly aggressive and treatment-refractory, yet RAS mutation itself is insufficient for tumorigenesis, due in part to profound metabolic stress induced by RAS activation. Here we show that loss of REDD1, a stress-induced metabolic regulator, is sufficient to reprogram lipid metabolism and drive progression of RAS mutant cancers. Redd1 deletion in genetically engineered mouse models (GEMMs) of KRAS-dependent pancreatic and lung adenocarcinomas converts preneoplastic lesions into invasive and metastatic carcinomas. Metabolic profiling reveals that REDD1-deficient/RAS mutant cells exhibit enhanced uptake of lysophospholipids and lipid storage, coupled to augmented fatty acid oxidation that sustains both ATP levels and ROS-detoxifying NADPH. Mechanistically, REDD1 loss triggers HIF-dependent activation of a lipid storage pathway involving PPARγ and the prometastatic factor CD36. Correspondingly, decreased REDD1 expression and a signature of REDD1 loss predict poor outcomes selectively in RAS mutant but not RAS wild-type human lung and pancreas carcinomas. Collectively, our findings reveal the REDD1-mediated stress response as a novel tumor suppressor whose loss defines a RAS mutant tumor subset characterized by reprogramming of lipid metabolism, invasive and metastatic progression, and poor prognosis. This work thus provides new mechanistic and clinically relevant insights into the phenotypic heterogeneity and metabolic rewiring that underlies these common cancers.
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Metabolismo de los Lípidos/genética , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Proteínas ras/genética , Animales , Línea Celular Tumoral , Progresión de la Enfermedad , Ácidos Grasos/metabolismo , Células HEK293 , Humanos , Ratones , Ratones SCID , Mutación , Oxidación-ReducciónRESUMEN
MDM2 and MDMX, negative regulators of the tumor suppressor p53, can work separately and as a heteromeric complex to restrain p53's functions. MDM2 also has pro-oncogenic roles in cells, tissues, and animals that are independent of p53. There is less information available about p53-independent roles of MDMX or the MDM2-MDMX complex. We found that MDM2 and MDMX facilitate ferroptosis in cells with or without p53. Using small molecules, RNA interference reagents, and mutant forms of MDMX, we found that MDM2 and MDMX, likely working in part as a complex, normally facilitate ferroptotic death. We observed that MDM2 and MDMX alter the lipid profile of cells to favor ferroptosis. Inhibition of MDM2 or MDMX leads to increased levels of FSP1 protein and a consequent increase in the levels of coenzyme Q10, an endogenous lipophilic antioxidant. This suggests that MDM2 and MDMX normally prevent cells from mounting an adequate defense against lipid peroxidation and thereby promote ferroptosis. Moreover, we found that PPARα activity is essential for MDM2 and MDMX to promote ferroptosis, suggesting that the MDM2-MDMX complex regulates lipids through altering PPARα activity. These findings reveal the complexity of cellular responses to MDM2 and MDMX and suggest that MDM2-MDMX inhibition might be useful for preventing degenerative diseases involving ferroptosis. Furthermore, they suggest that MDM2/MDMX amplification may predict sensitivity of some cancers to ferroptosis inducers.
Asunto(s)
Proteínas de Ciclo Celular/metabolismo , Ferroptosis/genética , Metabolismo de los Lípidos/genética , PPAR alfa/metabolismo , Proteínas Proto-Oncogénicas c-mdm2/metabolismo , Proteínas Proto-Oncogénicas/metabolismo , Animales , Encéfalo/metabolismo , Encéfalo/fisiopatología , Proteínas de Ciclo Celular/genética , Glioblastoma/fisiopatología , Células HCT116 , Humanos , Mutación , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas c-mdm2/antagonistas & inhibidores , Proteínas Proto-Oncogénicas c-mdm2/genética , Interferencia de ARN , Ratas , Proteína p53 Supresora de Tumor/metabolismo , Ubiquinona/análogos & derivados , Ubiquinona/metabolismoRESUMEN
Understanding perturbations in circulating lipid levels that often occur years or decades before clinical symptoms may enhance our understanding of disease mechanisms and provide novel intervention opportunities. Here, we assessed if polygenic scores (PGSs) for complex traits could detect lipid dysfunctions related to the traits and provide new biological insights. We constructed genome-wide PGSs (approximately 1 million genetic variants) for 50 complex traits in 7,169 Finnish individuals with routine clinical lipid profiles and lipidomics measurements (179 lipid species). We identified 678 associations (P < 9.0 × 10-5) involving 26 traits and 142 lipids. Most of these associations were also validated with the actual phenotype measurements where available (89.5% of 181 associations where the trait was available), suggesting that these associations represent early signs of physiological changes of the traits. We detected many known relationships (e.g., PGS for body mass index (BMI) and lysophospholipids, PGS for type 2 diabetes and triacyglycerols) and those that suggested potential target for prevention strategies (e.g., PGS for venous thromboembolism and arachidonic acid). We also found association of PGS for favorable adiposity with increased sphingomyelins levels, suggesting a probable role of sphingomyelins in increased risk for certain disease, e.g., venous thromboembolism as reported previously, in favorable adiposity despite its favorable metabolic effect. Altogether, our study provides a comprehensive characterization of lipidomic alterations in genetic predisposition for a wide range of complex traits. The study also demonstrates potential of PGSs for complex traits to capture early, presymptomatic lipid alterations, highlighting its utility in understanding disease mechanisms and early disease detection.
Asunto(s)
Estudio de Asociación del Genoma Completo , Lípidos , Herencia Multifactorial , Humanos , Herencia Multifactorial/genética , Masculino , Femenino , Lípidos/sangre , Lípidos/genética , Persona de Mediana Edad , Finlandia , Lipidómica/métodos , Adulto , Fenotipo , Índice de Masa Corporal , Metabolismo de los Lípidos/genética , Anciano , Polimorfismo de Nucleótido Simple/genética , Predisposición Genética a la EnfermedadRESUMEN
MicroRNAs (miRNAs) have essential functions during embryonic development, and their dysregulation causes cancer1,2. Altered global miRNA abundance is found in different tissues and tumours, which implies that precise control of miRNA dosage is important1,3,4, but the underlying mechanism(s) of this control remain unknown. The protein complex Microprocessor, which comprises one DROSHA and two DGCR8 proteins, is essential for miRNA biogenesis5-7. Here we identify a developmentally regulated miRNA dosage control mechanism that involves alternative transcription initiation (ATI) of DGCR8. ATI occurs downstream of a stem-loop in DGCR8 mRNA to bypass an autoregulatory feedback loop during mouse embryonic stem (mES) cell differentiation. Deletion of the stem-loop causes imbalanced DGCR8:DROSHA protein stoichiometry that drives irreversible Microprocessor aggregation, reduced primary miRNA processing, decreased mature miRNA abundance, and widespread de-repression of lipid metabolic mRNA targets. Although global miRNA dosage control is not essential for mES cells to exit from pluripotency, its dysregulation alters lipid metabolic pathways and interferes with embryonic development by disrupting germ layer specification in vitro and in vivo. This miRNA dosage control mechanism is conserved in humans. Our results identify a promoter switch that balances Microprocessor autoregulation and aggregation to precisely control global miRNA dosage and govern stem cell fate decisions during early embryonic development.
Asunto(s)
Dosificación de Gen , Estratos Germinativos/metabolismo , MicroARNs/genética , Proteínas de Unión al ARN/genética , Ribonucleasa III/genética , Animales , Regulación del Desarrollo de la Expresión Génica , Células Hep G2 , Humanos , Células K562 , Metabolismo de los Lípidos/genética , Ratones , Regiones Promotoras Genéticas , Iniciación de la Transcripción GenéticaRESUMEN
Excessive levels of saturated fatty acids are toxic to cells, although the basis for this lipotoxicity remains incompletely understood. Here, we analyzed the transcriptome, lipidome, and genetic interactions of human leukemia cells exposed to palmitate. Palmitate treatment increased saturated glycerolipids, accompanied by a transcriptional stress response, including upregulation of the endoplasmic reticulum (ER) stress response. A comprehensive genome-wide short hairpin RNA (shRNA) screen identified >350 genes modulating lipotoxicity. Among previously unknown genetic modifiers of lipotoxicity, depletion of RNF213, a putative ubiquitin ligase mutated in Moyamoya vascular disease, protected cells from lipotoxicity. On a broader level, integration of our comprehensive datasets revealed that changes in di-saturated glycerolipids, but not other lipid classes, are central to lipotoxicity in this model. Consistent with this, inhibition of ER-localized glycerol-3-phosphate acyltransferase activity protected from all aspects of lipotoxicity. Identification of genes modulating the response to saturated fatty acids may reveal novel therapeutic strategies for treating metabolic diseases linked to lipotoxicity.
Asunto(s)
Estrés del Retículo Endoplásmico/efectos de los fármacos , Retículo Endoplásmico/efectos de los fármacos , Glicéridos/metabolismo , Metabolismo de los Lípidos/efectos de los fármacos , Ácido Palmítico/toxicidad , Aciltransferasas/genética , Aciltransferasas/metabolismo , Adenosina Trifosfatasas/metabolismo , Retículo Endoplásmico/metabolismo , Retículo Endoplásmico/patología , Estrés del Retículo Endoplásmico/genética , Regulación Enzimológica de la Expresión Génica , Células HeLa , Células Hep G2 , Humanos , Células K562 , Metabolismo de los Lípidos/genética , Proteína 1 de Unión a los Elementos Reguladores de Esteroles/genética , Proteína 1 de Unión a los Elementos Reguladores de Esteroles/metabolismo , Transcriptoma , Ubiquitina-Proteína Ligasas/metabolismoRESUMEN
The Wnt/Wingless signaling pathway plays critical roles in metazoan development and energy metabolism, but its role in regulating lipid homeostasis remains not fully understood. Here, we report that the activation of canonical Wnt/Wg signaling promotes lipolysis while concurrently inhibiting lipogenesis and fatty acid ß-oxidation in both larval and adult adipocytes, as well as cultured S2R+ cells, in Drosophila. Using RNA-sequencing and CUT&RUN (Cleavage Under Targets & Release Using Nuclease) assays, we identified a set of Wnt target genes responsible for intracellular lipid homeostasis. Notably, active Wnt signaling directly represses the transcription of these genes, resulting in decreased de novo lipogenesis and fatty acid ß-oxidation, but increased lipolysis. These changes lead to elevated free fatty acids and reduced triglyceride (TG) accumulation in adipocytes with active Wnt signaling. Conversely, downregulation of Wnt signaling in the fat body promotes TG accumulation in both larval and adult adipocytes. The attenuation of Wnt signaling also increases the expression of specific lipid metabolism-related genes in larval adipocytes, wing discs, and adult intestines. Taken together, these findings suggest that Wnt signaling-induced transcriptional repression plays an important role in regulating lipid homeostasis by enhancing lipolysis while simultaneously suppressing lipogenesis and fatty acid ß-oxidation.