RESUMO
Adipose tissues serve as an energy reservoir and endocrine organ, yet the mechanisms that coordinate these functions remain elusive. Here, we show that the transcriptional coregulators, YAP and TAZ, uncouple fat mass from leptin levels and regulate adipocyte plasticity to maintain metabolic homeostasis. Activating YAP/TAZ signalling in adipocytes by deletion of the upstream regulators Lats1 and Lats2 results in a profound reduction in fat mass by converting mature adipocytes into delipidated progenitor-like cells, but does not cause lipodystrophy-related metabolic dysfunction, due to a paradoxical increase in circulating leptin levels. Mechanistically, we demonstrate that YAP/TAZ-TEAD signalling upregulates leptin expression by directly binding to an upstream enhancer site of the leptin gene. We further show that YAP/TAZ activity is associated with, and functionally required for, leptin regulation during fasting and refeeding. These results suggest that adipocyte Hippo-YAP/TAZ signalling constitutes a nexus for coordinating adipose tissue lipid storage capacity and systemic energy balance through the regulation of adipocyte plasticity and leptin gene transcription.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Adipócitos , Tecido Adiposo , Metabolismo Energético , Via de Sinalização Hippo , Leptina , Proteínas Serina-Treonina Quinases , Transdução de Sinais , Proteínas de Sinalização YAP , Animais , Leptina/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Camundongos , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas de Sinalização YAP/metabolismo , Tecido Adiposo/metabolismo , Adipócitos/metabolismo , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/genética , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética , Proteínas com Motivo de Ligação a PDZ com Coativador Transcricional/metabolismo , Fosfoproteínas/metabolismo , Fosfoproteínas/genética , Proteínas Supressoras de Tumor/metabolismo , Proteínas Supressoras de Tumor/genética , Transativadores/metabolismo , Transativadores/genéticaRESUMO
Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal types of cancer, and novel treatment regimens are direly needed. Epigenetic regulation contributes to the development of various cancer types, but its role in the development of and potential as a therapeutic target for PDAC remains underexplored. Here, we show that PRMT1 is highly expressed in murine and human pancreatic cancer and is essential for cancer cell proliferation and tumorigenesis. Deletion of PRMT1 delays pancreatic cancer development in a KRAS-dependent mouse model, and multi-omics analyses reveal that PRMT1 depletion leads to global changes in chromatin accessibility and transcription, resulting in reduced glycolysis and a decrease in tumorigenic capacity. Pharmacological inhibition of PRMT1 in combination with gemcitabine has a synergistic effect on pancreatic tumor growth in vitro and in vivo. Collectively, our findings implicate PRMT1 as a key regulator of pancreatic cancer development and a promising target for combination therapy.
Assuntos
Carcinoma Ductal Pancreático , Neoplasias Pancreáticas , Animais , Humanos , Camundongos , Carcinoma Ductal Pancreático/tratamento farmacológico , Carcinoma Ductal Pancreático/genética , Linhagem Celular Tumoral , Epigênese Genética , Gencitabina , Neoplasias Pancreáticas/tratamento farmacológico , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/patologia , Proteína-Arginina N-Metiltransferases/genética , Proteína-Arginina N-Metiltransferases/metabolismo , Proteína-Arginina N-Metiltransferases/uso terapêutico , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismoRESUMO
Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is characterized by various disabling symptoms including exercise intolerance and is diagnosed in the absence of a specific cause, making its clinical management challenging. A better understanding of the molecular mechanism underlying this apparent bioenergetic deficiency state may reveal insights for developing targeted treatment strategies. We report that overexpression of Wiskott-Aldrich Syndrome Protein Family Member 3 (WASF3), here identified in a 38-y-old woman suffering from long-standing fatigue and exercise intolerance, can disrupt mitochondrial respiratory supercomplex formation and is associated with endoplasmic reticulum (ER) stress. Increased expression of WASF3 in transgenic mice markedly decreased their treadmill running capacity with concomitantly impaired respiratory supercomplex assembly and reduced complex IV levels in skeletal muscle mitochondria. WASF3 induction by ER stress using endotoxin, well known to be associated with fatigue in humans, also decreased skeletal muscle complex IV levels in mice, while decreasing WASF3 levels by pharmacologic inhibition of ER stress improved mitochondrial function in the cells of the patient with chronic fatigue. Expanding on our findings, skeletal muscle biopsy samples obtained from a cohort of patients with ME/CFS showed increased WASF3 protein levels and aberrant ER stress activation. In addition to revealing a potential mechanism for the bioenergetic deficiency in ME/CFS, our study may also provide insights into other disorders associated with fatigue such as rheumatic diseases and long COVID.
Assuntos
COVID-19 , Síndrome de Fadiga Crônica , Animais , Feminino , Humanos , Camundongos , COVID-19/metabolismo , Síndrome de Fadiga Crônica/diagnóstico , Mitocôndrias/metabolismo , Síndrome de COVID-19 Pós-Aguda , Respiração , Família de Proteínas da Síndrome de Wiskott-Aldrich/metabolismo , Camundongos TransgênicosRESUMO
Germline mutations of TP53, which cause the cancer predisposition disorder Li-Fraumeni syndrome (LFS), can increase mitochondrial activity as well as fatty acid ß-oxidation (FAO) in mice. Increased fatty acid metabolism can promote cancer malignancy, but its specific contribution to tumorigenesis in LFS remains unclear. To investigate this, we crossed LFS mice carrying the p53 R172H knock-in mutation (p53172H/H , homolog of the human TP53 R175H LFS mutation) with myoglobin-knockout (MB-/- ) mice known to have decreased FAO. MB-/- p53172H/H double-mutant mice also showed mildly reduced FAO in thymus, a common site of T lymphoma development in LFS mice, in association with an approximately 40% improvement in cancer-free survival time. RNA sequencing profiling revealed that the p53 R172H mutation promotes mitochondrial metabolism and ribosome biogenesis, both of which are suppressed by the disruption of MB. The activation of ribosomal protein S6, involved in protein translation and implicated in cancer promotion, was also inhibited in the absence of MB. To further confirm the role of FAO in lymphomagenesis, mitochondrial FAO enzyme, carnitine palmitoyltransferase 2 (CPT2), was specifically disrupted in T cells of p53172H/H mice using a Cre-loxP-mediated strategy. The heterozygous knockout of CPT2 resulted in thymus FAO haploinsufficiency and an approximately 30% improvement in survival time, paralleling the antiproliferative signaling observed with MB disruption. Thus, this study demonstrates that moderating FAO in LFS can suppress tumorigenesis and improve cancer-free survival with potential implications for cancer prevention. PREVENTION RELEVANCE: Mildly inhibiting the increased fatty acid oxidation observed in a mouse model of Li-Fraumeni syndrome, a cancer predisposition disorder caused by inherited mutations of TP53, dampens aberrant pro-tumorigenic cell signaling and improves the survival time of these mice, thereby revealing a potential strategy for cancer prevention in patients.
Assuntos
Carcinogênese/metabolismo , Carnitina O-Palmitoiltransferase/metabolismo , Ácidos Graxos/metabolismo , Síndrome de Li-Fraumeni/patologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Carcinogênese/genética , Carnitina O-Palmitoiltransferase/genética , Estudos de Casos e Controles , Células Cultivadas , Modelos Animais de Doenças , Intervalo Livre de Doença , Metabolismo Energético , Feminino , Técnicas de Introdução de Genes , Predisposição Genética para Doença , Mutação em Linhagem Germinativa , Heterozigoto , Humanos , Síndrome de Li-Fraumeni/complicações , Síndrome de Li-Fraumeni/genética , Síndrome de Li-Fraumeni/mortalidade , Masculino , Camundongos , Camundongos Knockout , Pessoa de Meia-Idade , Mioblastos , Mioglobina/genética , Oxirredução , Cultura Primária de Células , Estudos Prospectivos , Proteína Supressora de Tumor p53/genética , Adulto JovemRESUMO
The physiological effects of the many germline mutations of TP53, encoding the tumor suppressor protein p53, are poorly understood. Here we report generating a p53 R178C knockin mouse modeling the human TP53 R181C mutation, which is notable for its prevalence and prior molecular characterization. Consistent with its weak cancer penetrance in humans, homozygous p53178C/C mice show a modest increase in tumorigenesis but, surprisingly, are lean with decreased body fat content. They display evidence of increased lipolysis and upregulation of fatty acid metabolism in their inguinal white adipose tissue (iWAT). Gene expression and chromatin immunoprecipitation sequencing (ChIP-seq) analyses show that the mutant p53 bound and transactivated Beta-3-Adrenergic Receptor (ADRB3), a gene that is known to promote lipolysis and is associated with obesity. This study reveals that a germline mutation of p53 can affect fat metabolism, which has been implicated in cancer development.
Assuntos
Mutação em Linhagem Germinativa/genética , Lipólise/genética , Homologia de Sequência de Aminoácidos , Proteína Supressora de Tumor p53/genética , Células 3T3-L1 , Adipócitos/metabolismo , Tecido Adiposo Branco/patologia , Animais , Sequência de Bases , Ácidos Graxos/sangue , Regulação da Expressão Gênica , Homozigoto , Humanos , Síndrome de Li-Fraumeni/genética , Metabolômica , Camundongos , Camundongos Endogâmicos C57BL , Fenótipo , Análise de Componente Principal , Receptores Adrenérgicos beta 3/genética , Transdução de SinaisRESUMO
Doxorubicin is a widely used chemotherapeutic agent that causes dose-dependent cardiotoxicity in a subset of treated patients, but the genetic determinants of this susceptibility are poorly understood. Here, we report that a noncanonical tumor suppressor activity of p53 prevents cardiac dysfunction in a mouse model induced by doxorubicin administered in divided low doses as in the clinics. While relatively preserved in wild-type (p53+/+ ) state, mice deficient in p53 (p53-/- ) developed left ventricular (LV) systolic dysfunction after doxorubicin treatment. This functional decline in p53-/- mice was associated with decreases in cardiac oxidative metabolism, mitochondrial mass, and mitochondrial genomic DNA (mtDNA) homeostasis. Notably, mice with homozygous knockin of the p53 R172H (p53172H/H ) mutation, which like p53-/- state lacks the prototypical tumor suppressor activities of p53 such as apoptosis but retains its mitochondrial biogenesis capacity, showed preservation of LV function and mitochondria after doxorubicin treatment. In contrast to p53-null state, wild-type and mutant p53 displayed distinct mechanisms of transactivating mitochondrial transcription factor A (TFAM) and p53-inducible ribonucleotide reductase 2 (p53R2), which are involved in mtDNA transcription and maintenance. Importantly, supplementing mice with a precursor of NAD+ prevented the mtDNA depletion and cardiac dysfunction. These findings suggest that loss of mtDNA contributes to cardiomyopathy pathogenesis induced by doxorubicin administered on a schedule simulating that in the clinics. Given a similar mtDNA protection role of p53 in doxorubicin-treated human induced pluripotent stem cell (iPSC)-derived cardiomyocytes, the mitochondrial markers associated with cardiomyopathy development observed in blood and skeletal muscle cells may have prognostic utility.
Assuntos
Cardiotoxicidade/metabolismo , Cardiotoxicidade/prevenção & controle , Doxorrubicina/toxicidade , Proteína Supressora de Tumor p53/metabolismo , Animais , Apoptose/fisiologia , Cardiomiopatias/metabolismo , DNA Mitocondrial/genética , Proteínas de Ligação a DNA , Cardiopatias/metabolismo , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mitocôndrias Cardíacas/metabolismo , Proteínas Mitocondriais , Mutação , Miócitos Cardíacos/metabolismo , Biogênese de Organelas , Cultura Primária de Células , Fatores de Transcrição , Proteína Supressora de Tumor p53/genéticaRESUMO
Inheritance of germline mutations in the tumor suppressor gene TP53 causes Li-Fraumeni syndrome (LFS), a cancer predisposition disorder. The arginine to histidine substitution at amino acid position 337 of p53 (R337H) is a founder mutation highly prevalent in southern and southeastern Brazil and is considered an LFS mutation. Although this mutation is of significant clinical interest, its role in tumorigenesis using animal models has not been described. Here, we generate a knockin mouse model containing the homologous R337H mutation (mouse R334H). De novo tumorigenesis was not significantly increased in either heterozygous (p53334R/H ) or homozygous (p53334H/H ) p53 R334H knockin mice compared with wild-type mice. However, susceptibility to diethylnitrosamine (DEN)-induced liver carcinogenesis was increased in a mutant allele dose-dependent manner. In parallel, p53334H/H mice exposed to DEN exhibited increased DNA damage but decreased cell-cycle regulation in the liver. Oligomerization of p53, which is required for transactivation of target genes, was reduced in R334H liver, consistent with its decreased nuclear activity compared with wild-type. By modeling a TP53 mutation in mice that has relatively weak cancer penetrance, this study provides in vivo evidence that the human R337H mutation can compromise p53 activity and promote tumorigenesis.Significance: A germline mutation in the oligomerization domain of p53 decreases its transactivation potential and renders mice susceptible to carcinogen-induced liver tumorigenesis. Cancer Res; 78(18); 5375-83. ©2018 AACR.
Assuntos
Carcinogênese/genética , Neoplasias Hepáticas/patologia , Proteína Supressora de Tumor p53/genética , Alelos , Animais , Brasil , Transformação Celular Neoplásica/genética , Dano ao DNA , Fibroblastos/metabolismo , Técnicas de Introdução de Genes , Predisposição Genética para Doença , Mutação em Linhagem Germinativa , Homozigoto , Humanos , Fígado/metabolismo , Neoplasias Hepáticas/induzido quimicamente , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Mutação , Ativação TranscricionalRESUMO
Li-Fraumeni syndrome (LFS) is a cancer predisposition disorder caused by germline mutations in TP53 that can lead to increased mitochondrial metabolism in patients. However, the implications of altered mitochondrial function for tumorigenesis in LFS are unclear. Here, we have reported that genetic or pharmacologic disruption of mitochondrial respiration improves cancer-free survival in a mouse model of LFS that expresses mutant p53. Mechanistically, inhibition of mitochondrial function increased autophagy and decreased the aberrant proliferation signaling caused by mutant p53. In a pilot study, LFS patients treated with metformin exhibited decreases in mitochondrial activity concomitant with activation of antiproliferation signaling, thus reproducing the effects of disrupting mitochondrial function observed in LFS mice. These observations indicate that a commonly prescribed diabetic medicine can restrain mitochondrial metabolism and tumorigenesis in an LFS model, supporting its further consideration for cancer prevention in LFS patients.
Assuntos
Síndrome de Li-Fraumeni/prevenção & controle , Metformina/farmacologia , Mitocôndrias/metabolismo , Neoplasias Experimentais/prevenção & controle , Consumo de Oxigênio/efeitos dos fármacos , Adulto , Animais , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/genética , Feminino , Humanos , Células Jurkat , Síndrome de Li-Fraumeni/genética , Síndrome de Li-Fraumeni/metabolismo , Masculino , Camundongos , Camundongos Mutantes , Pessoa de Meia-Idade , Mitocôndrias/genética , Mitocôndrias/patologia , Neoplasias Experimentais/genética , Neoplasias Experimentais/metabolismo , Consumo de Oxigênio/genética , Projetos Piloto , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/metabolismoRESUMO
Although exercise is linked with improved health, the specific molecular mechanisms underlying its various benefits require further clarification. Here we report that exercise increases the nuclear localization and activity of p53 by acutely down-regulating coiled-coil-helix-coiled-coil-helix domain 4 (CHCHD4), a carrier protein that mediates p53 import into the mitochondria. This response to exercise is lost in transgenic mice with constitutive expression of CHCHD4. Mechanistically, exercise-induced nuclear transcription factor FOXO3 binds to the CHCHD4 promoter and represses its expression, preventing the translocation of p53 to the mitochondria and thereby increasing p53 nuclear localization. The synergistic increase in nuclear p53 and FOXO3 by exercise can facilitate their known interaction in transactivating Sirtuin 1 (SIRT1), a NAD+-dependent histone deacetylase that mediates adaptation to various stresses. Thus, our results reveal one mechanism by which exercise could be involved in preventing cancer and potentially other diseases associated with aging.
Assuntos
Núcleo Celular/metabolismo , Proteína Forkhead Box O3/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Condicionamento Físico Animal , Proteína Supressora de Tumor p53/metabolismo , Transporte Ativo do Núcleo Celular , Animais , Núcleo Celular/genética , Proteína Forkhead Box O3/genética , Humanos , Camundongos , Camundongos Knockout , Proteínas de Transporte da Membrana Mitocondrial/genética , Elementos de Resposta , Sirtuína 1/genética , Sirtuína 1/metabolismo , Proteína Supressora de Tumor p53/genéticaRESUMO
Molecular oxygen sustains aerobic life, but it also serves as the substrate for oxidative stress, which has been associated with the pathogenesis of disease and with aging. Compared with mice housed in normoxia (21% O2), reducing ambient oxygen to 10% O2 (hypoxia) resulted in increased hematopoietic stem cell (HSC) function as measured by bone marrow (BM) cell engraftment onto lethally irradiated recipients. The number of BM c-Kit(+)Sca-1(+)Lin(-) (KSL) cells as well as the number of cells with other hematopoietic stem and progenitor cell markers were increased in hypoxia mice, whereas the BM cells' colony-forming capacity remained unchanged. KSL cells from hypoxia mice showed a decreased level of oxidative stress and increased expression of transcription factor Gata1 and cytokine receptor c-Mpl, consistent with the observations of increased erythropoiesis and enhanced HSC engraftment. These observations demonstrate the benefit of a hypoxic HSC niche and suggest that hypoxic conditions can be further optimized to preserve stem cell integrity in vivo.
Assuntos
Adaptação Biológica , Hematopoese , Células-Tronco Hematopoéticas/citologia , Células-Tronco Hematopoéticas/metabolismo , Hipóxia/metabolismo , Adaptação Biológica/genética , Animais , Ensaio de Unidades Formadoras de Colônias , Perfilação da Expressão Gênica , Sobrevivência de Enxerto , Transplante de Células-Tronco Hematopoéticas , Hipóxia/genética , Camundongos , Camundongos Knockout , Modelos Animais , Estresse Oxidativo , Fatores de TempoRESUMO
There is growing evidence in the basic science field that aberrant metabolism plays an important role in tumorigenesis. Therefore, it is imperative to perform investigations in human subjects to determine (1) whether the metabolic observations made in model systems are applicable to humans; and (2) if indeed applicable, whether the metabolic alterations are clinically significant for cancer development. As an initial step, here we describe methods for measuring the mitochondrial metabolism of blood lymphocytes and skeletal muscle myoblasts that can be obtained from human subjects.
Assuntos
Bioquímica/métodos , Linfócitos/metabolismo , Mitocôndrias/metabolismo , Mioblastos Esqueléticos/metabolismo , Células Cultivadas , Humanos , Mitocôndrias Musculares/metabolismo , Músculo Esquelético/metabolismoRESUMO
p53, a critical tumor suppressor, regulates mitochondrial respiration, but how a nuclear protein can orchestrate the function of an organelle encoded by two separate genomes, both of which require p53 for their integrity, remains unclear. Here we report that the mammalian homolog of the yeast mitochondrial disulfide relay protein Mia40 (CHCHD4) is necessary for the respiratory-dependent translocation of p53 into the mitochondria. In the setting of oxidative stress, increased CHCHD4 expression partitions p53 into the mitochondria and protects its genomic integrity while decreasing p53 nuclear localization and transcriptional activity. Conversely, decreased CHCHD4 expression prevents the mitochondrial translocation of p53 while augmenting its nuclear localization and activity. Thus, the mitochondrial disulfide relay system allows p53 to regulate two spatially segregated genomes depending on oxidative metabolic activity.
Assuntos
Dissulfetos/metabolismo , Mitocôndrias/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Animais , Western Blotting , Núcleo Celular/metabolismo , Reparo do DNA , DNA Mitocondrial/genética , DNA Mitocondrial/metabolismo , Células HCT116 , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microscopia Confocal , Proteínas de Transporte da Membrana Mitocondrial/genética , Proteínas do Complexo de Importação de Proteína Precursora Mitocondrial , Mutação , Ligação Proteica , Transporte Proteico , Interferência de RNA , Proteína Supressora de Tumor p53/genéticaRESUMO
There is growing evidence that alterations in metabolism may contribute to tumorigenesis. Here, we report on members of families with the Li-Fraumeni syndrome who carry germline mutations in TP53, the gene encoding the tumor-suppressor protein p53. As compared with family members who are not carriers and with healthy volunteers, family members with these mutations have increased oxidative phosphorylation of skeletal muscle. Basic experimental studies of tissue samples from patients with the Li-Fraumeni syndrome and a mouse model of the syndrome support this in vivo finding of increased mitochondrial function. These results suggest that p53 regulates bioenergetic homeostasis in humans. (Funded by the National Heart, Lung, and Blood Institute and the National Institutes of Health; ClinicalTrials.gov number, NCT00406445.).
Assuntos
Metabolismo Energético/genética , Exercício Físico/fisiologia , Genes p53 , Síndrome de Li-Fraumeni/metabolismo , Mitocôndrias Musculares/metabolismo , Fosfocreatina/metabolismo , Animais , Estudos de Casos e Controles , Modelos Animais de Doenças , Feminino , Mutação em Linhagem Germinativa , Heterozigoto , Humanos , Síndrome de Li-Fraumeni/genética , Masculino , Camundongos , Músculo Esquelético/metabolismo , Consumo de Oxigênio/genética , Consumo de Oxigênio/fisiologia , Projetos Piloto , Levantamento de Peso/fisiologiaRESUMO
Zinc finger protein tristetraprolin (TTP) modulates macrophage inflammatory activity by destabilizing cytokine mRNAs. In this study, through a screen of TTP-bound mRNAs in activated human macrophages, we have identified CCL3 mRNA as the most abundantly bound TTP target mRNA and have characterized this interaction via conserved AU-rich elements. Compared to the wild-type cells, TTP(-/-) macrophages produced higher levels of LPS-induced CCL3. In addition, the plasma level of CCL3 in TTP(-/-) mice was markedly higher than that in wild-type mice. To determine the in vivo significance of TTP-regulated CCL3, we generated CCL3(-/-)TTP(-/-) double-knockout mice. Along with decreased proinflammatory cytokines in their paw joints, there were significant functional and histologic improvements in the inflammatory arthritis of TTP(-/-) mice when CCL3 was absent, although cachexia, reflecting systemic inflammation, was notably unaffected. Furthermore, the marked exacerbation of aortic plaque formation caused by TTP deficiency in the APOE(-/-) mouse model of atherosclerosis was also rescued by disrupting CCL3. Taken together, our data indicate that the interaction between TTP and CCL3 mRNA plays an important role in modulating localized inflammatory processes in tissues that are dissociated from the systemic manifestations of chronic inflammation.
Assuntos
Quimiocina CCL3/metabolismo , Inflamação/metabolismo , Macrófagos/metabolismo , Tristetraprolina/metabolismo , Animais , Artrite Experimental/imunologia , Artrite Experimental/metabolismo , Sequência de Bases , Quimiocina CCL3/genética , Quimiocina CCL3/imunologia , Feminino , Humanos , Imunoprecipitação , Inflamação/imunologia , Macrófagos/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Dados de Sequência Molecular , RNA Mensageiro/análise , RNA Interferente Pequeno , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transfecção , Tristetraprolina/imunologiaRESUMO
Oxygen serves as an essential factor for oxidative stress, and it has been shown to be a mutagen in bacteria. While it is well established that ambient oxygen can also cause genomic instability in cultured mammalian cells, its effect on de novo tumorigenesis at the organismal level is unclear. Herein, by decreasing ambient oxygen exposure, we report a â¼50% increase in the median tumor-free survival time of p53-/- mice. In the thymus, reducing oxygen exposure decreased the levels of oxidative DNA damage and RAG recombinase, both of which are known to promote lymphomagenesis in p53-/- mice. Oxygen is further shown to be associated with genomic instability in two additional cancer models involving the APC tumor suppressor gene and chemical carcinogenesis. Together, these observations represent the first report directly testing the effect of ambient oxygen on de novo tumorigenesis and provide important physiologic evidence demonstrating its critical role in increasing genomic instability in vivo.
Assuntos
Neoplasias Experimentais/etiologia , Oxigênio/metabolismo , Neoplasias Cutâneas/etiologia , 9,10-Dimetil-1,2-benzantraceno/toxicidade , Animais , Sequência de Bases , Western Blotting , Carcinógenos/toxicidade , Primers do DNA , Feminino , Instabilidade Genômica , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Nus , Neoplasias Experimentais/induzido quimicamente , Neoplasias Cutâneas/induzido quimicamenteRESUMO
Oxygen is not only required for oxidative phosphorylation but also serves as the essential substrate for the formation of reactive oxygen species (ROS), which is implicated in ageing and tumorigenesis. Although the mitochondrion is known for its bioenergetic function, the symbiotic theory originally proposed that it provided protection against the toxicity of increasing oxygen in the primordial atmosphere. Using human cells lacking Synthesis of Cytochrome c Oxidase 2 (SCO2-/-), we have tested the oxygen toxicity hypothesis. These cells are oxidative phosphorylation defective and glycolysis dependent; they exhibit increased viability under hypoxia and feature an inverted growth response to oxygen compared with wild-type cells. SCO2-/- cells have increased intracellular oxygen and nicotinamide adenine dinucleotide (NADH) levels, which result in increased ROS and oxidative DNA damage. Using this isogenic cell line, we have revealed the genotoxicity of ambient oxygen. Our study highlights the importance of mitochondrial respiration both for bioenergetic benefits and for maintaining genomic stability in an oxygen-rich environment.
Assuntos
Respiração Celular/fisiologia , Mitocôndrias/metabolismo , Oxigênio/metabolismo , Western Blotting , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Linhagem Celular , Respiração Celular/genética , Dano ao DNA/genética , Dano ao DNA/fisiologia , Citometria de Fluxo , Imunofluorescência , Células HCT116 , Humanos , Mitocôndrias/genética , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Chaperonas Moleculares , Fosforilação Oxidativa , Estresse Oxidativo/genética , Estresse Oxidativo/fisiologia , Interferência de RNA , Espécies Reativas de Oxigênio/metabolismoRESUMO
OBJECTIVES: The expression of FOS, a gene critical for monocyte and macrophage function, can be inhibited by statins through the disruption of a cholesterol-independent signaling pathway. In this pilot study, we hypothesized that blood FOS mRNA levels will be sensitive to statin treatment independent of LDL cholesterol levels. METHODS: Three cohorts at increased risk of or with cardiovascular disease (CVD) were studied. Blood FOS mRNA levels were measured before and after statin treatment or in patients under stable treatment. RESULTS: Statin treatment for three months significantly reduced blood FOS mRNA and LDL cholesterol levels. However, in subjects with similar LDL levels achieved by different doses of long term statin treatment, there was an inverse relationship between statin dose and FOS expression. CONCLUSIONS: FOS mRNA levels appear to be a sensitive marker of statin treatment that is dissociated from cholesterol levels.
Assuntos
LDL-Colesterol/metabolismo , Genes fos , Inibidores de Hidroximetilglutaril-CoA Redutases/farmacologia , Proteínas Proto-Oncogênicas c-fos/sangue , Idoso , Biomarcadores/metabolismo , Proteína C-Reativa/biossíntese , Colesterol/química , Feminino , Humanos , Inflamação , Leucócitos Mononucleares/citologia , Macrófagos/citologia , Masculino , Pessoa de Meia-Idade , Estudos ProspectivosRESUMO
RATIONALE: Exercise capacity is a physiological characteristic associated with protection from both cardiovascular and all-cause mortality. p53 regulates mitochondrial function and its deletion markedly diminishes exercise capacity, but the underlying genetic mechanism orchestrating this is unclear. Understanding the biology of how p53 improves exercise capacity may provide useful insights for improving both cardiovascular as well as general health. OBJECTIVE: The purpose of this study was to understand the genetic mechanism by which p53 regulates aerobic exercise capacity. METHODS AND RESULTS: Using a variety of physiological, metabolic, and molecular techniques, we further characterized maximum exercise capacity and the effects of training, measured various nonmitochondrial and mitochondrial determinants of exercise capacity, and examined putative regulators of mitochondrial biogenesis. As p53 did not affect baseline cardiac function or inotropic reserve, we focused on the involvement of skeletal muscle and now report a wider role for p53 in modulating skeletal muscle mitochondrial function. p53 interacts with Mitochondrial Transcription Factor A (TFAM), a nuclear-encoded gene important for mitochondrial DNA (mtDNA) transcription and maintenance, and regulates mtDNA content. The increased mtDNA in p53(+/+) compared to p53(-/-) mice was more marked in aerobic versus glycolytic skeletal muscle groups with no significant changes in cardiac tissue. These in vivo observations were further supported by in vitro studies showing overexpression of p53 in mouse myoblasts increases both TFAM and mtDNA levels whereas depletion of TFAM by shRNA decreases mtDNA content. CONCLUSIONS: Our current findings indicate that p53 promotes aerobic metabolism and exercise capacity by using different mitochondrial genes and mechanisms in a tissue-specific manner.
Assuntos
DNA Mitocondrial/metabolismo , Tolerância ao Exercício , Mitocôndrias Musculares/metabolismo , Músculo Esquelético/metabolismo , Mioblastos Esqueléticos/metabolismo , Esforço Físico , Proteína Supressora de Tumor p53/metabolismo , Animais , Sítios de Ligação , Linhagem Celular , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Tolerância ao Exercício/genética , Glicólise/genética , Proteínas de Grupo de Alta Mobilidade/genética , Proteínas de Grupo de Alta Mobilidade/metabolismo , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Contração Muscular , Força Muscular , Mutação , Miocárdio/metabolismo , Consumo de Oxigênio , Interferência de RNA , Elementos de Resposta , Natação , Fatores de Tempo , Transdução Genética , Transfecção , Proteína Supressora de Tumor p53/deficiência , Proteína Supressora de Tumor p53/genética , Regulação para Cima , Função Ventricular EsquerdaRESUMO
Translational studies using genomic techniques in cardiovascular diseases are still in their infancy. Access to disease-associated cardiovascular tissues from patients has been a major impediment to progress in contrast to the diagnostic advances made by oncologists using gene expression on readily available tumor samples. Nonetheless, progress is being made for atherosclerosis by carefully designed experiments utilizing diseased tissue or surrogate specimens. This review details the rationale and findings of a study utilizing freshly isolated blood mononuclear cells from patients undergoing carotid endarterectomy due to atherosclerotic stenosis and from matched healthy subjects. By querying this cardiovascular tissue surrogate, the messenger RNA levels of the Finkel-Biskis-Jenkins osteosarcoma gene in circulating monocytes were found to correlate with atherosclerosis severity in patients and with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor (statin) therapy in healthy subjects. The major finding of this investigation is discussed in relation to observations from other human atherosclerosis gene expression studies. These distinct studies converge to demonstrate the unequivocal importance of inflammation in atherosclerosis. Although the clinical utility of the specific findings remains open, the identification of similar genes by different investigations serves to validate our report. They also provide us with insights into pathogenesis that may impact future translational applications.
Assuntos
Aterosclerose/genética , Perfilação da Expressão Gênica/métodos , Monócitos/metabolismo , Aterosclerose/sangue , Biomarcadores/sangue , Humanos , RNA Mensageiro/sangue , Proteínas Ribossômicas/genética , Vasculite/complicações , Vasculite/genéticaRESUMO
The energy that sustains cancer cells is derived preferentially from glycolysis. This metabolic change, the Warburg effect, was one of the first alterations in cancer cells recognized as conferring a survival advantage. Here, we show that p53, one of the most frequently mutated genes in cancers, modulates the balance between the utilization of respiratory and glycolytic pathways. We identify Synthesis of Cytochrome c Oxidase 2 (SCO2) as the downstream mediator of this effect in mice and human cancer cell lines. SCO2 is critical for regulating the cytochrome c oxidase (COX) complex, the major site of oxygen utilization in the eukaryotic cell. Disruption of the SCO2 gene in human cancer cells with wild-type p53 recapitulated the metabolic switch toward glycolysis that is exhibited by p53-deficient cells. That SCO2 couples p53 to mitochondrial respiration provides a possible explanation for the Warburg effect and offers new clues as to how p53 might affect aging and metabolism.