Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 80
Filtrar
Mais filtros

Base de dados
Tipo de documento
Intervalo de ano de publicação
1.
Cell ; 2024 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-39303716

RESUMO

Eukaryotic cell function and survival rely on the use of a mitochondrial H+ electrochemical gradient (Δp), which is composed of an inner mitochondrial membrane (IMM) potential (ΔΨmt) and a pH gradient (ΔpH). So far, ΔΨmt has been assumed to be composed exclusively of H+. Here, using a rainbow of mitochondrial and nuclear genetic models, we have discovered that a Na+ gradient equates with the H+ gradient and controls half of ΔΨmt in coupled-respiring mammalian mitochondria. This parallelism is controlled by the activity of the long-sought Na+-specific Na+/H+ exchanger (mNHE), which we have identified as the P-module of complex I (CI). Deregulation of this mNHE function, without affecting the canonical enzymatic activity or the assembly of CI, occurs in Leber's hereditary optic neuropathy (LHON), which has profound consequences in ΔΨmt and mitochondrial Ca2+ homeostasis and explains the previously unknown molecular pathogenesis of this neurodegenerative disease.

2.
Nat Immunol ; 17(9): 1037-1045, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27348412

RESUMO

Macrophages tightly scale their core metabolism after being activated, but the precise regulation of the mitochondrial electron-transport chain (ETC) and its functional implications are currently unknown. Here we found that recognition of live bacteria by macrophages transiently decreased assembly of the ETC complex I (CI) and CI-containing super-complexes and switched the relative contributions of CI and CII to mitochondrial respiration. This was mediated by phagosomal NADPH oxidase and the reactive oxygen species (ROS)-dependent tyrosine kinase Fgr. It required Toll-like receptor signaling and the NLRP3 inflammasome, which were both connected to bacterial viability-specific immune responses. Inhibition of CII during infection with Escherichia coli normalized serum concentrations of interleukin 1ß (IL-1ß) and IL-10 to those in mice treated with dead bacteria and impaired control of bacteria. We have thus identified ETC adaptations as an early immunological-metabolic checkpoint that adjusts innate immune responses to bacterial infection.


Assuntos
Complexo de Proteínas da Cadeia de Transporte de Elétrons/metabolismo , Infecções por Escherichia coli/imunologia , Escherichia coli K12/imunologia , Macrófagos/imunologia , Mitocôndrias/metabolismo , Animais , Células Cultivadas , Metabolismo Energético/genética , Interações Hospedeiro-Parasita , Imunidade Inata/genética , Interleucina-10/metabolismo , Interleucina-1beta/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Fagocitose , Espécies Reativas de Oxigênio/metabolismo
3.
EMBO J ; 42(10): e111699, 2023 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-36912136

RESUMO

The maintenance of cellular function relies on the close regulation of adenosine triphosphate (ATP) synthesis and hydrolysis. ATP hydrolysis by mitochondrial ATP Synthase (CV) is induced by loss of proton motive force and inhibited by the mitochondrial protein ATPase inhibitor (ATPIF1). The extent of CV hydrolytic activity and its impact on cellular energetics remains unknown due to the lack of selective hydrolysis inhibitors of CV. We find that CV hydrolytic activity takes place in coupled intact mitochondria and is increased by respiratory chain defects. We identified (+)-Epicatechin as a selective inhibitor of ATP hydrolysis that binds CV while preventing the binding of ATPIF1. In cells with Complex-III deficiency, we show that inhibition of CV hydrolytic activity by (+)-Epichatechin is sufficient to restore ATP content without restoring respiratory function. Inhibition of CV-ATP hydrolysis in a mouse model of Duchenne Muscular Dystrophy is sufficient to improve muscle force without any increase in mitochondrial content. We conclude that the impact of compromised mitochondrial respiration can be lessened using hydrolysis-selective inhibitors of CV.


Assuntos
Trifosfato de Adenosina , Mitocôndrias , Camundongos , Animais , Trifosfato de Adenosina/metabolismo , Mitocôndrias/metabolismo , ATPases Translocadoras de Prótons/metabolismo , Proteínas/metabolismo , Homeostase , Hidrólise
4.
Nature ; 586(7828): 287-291, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32728214

RESUMO

All metazoans depend on the consumption of O2 by the mitochondrial oxidative phosphorylation system (OXPHOS) to produce energy. In addition, the OXPHOS uses O2 to produce reactive oxygen species that can drive cell adaptations1-4, a phenomenon that occurs in hypoxia4-8 and whose precise mechanism remains unknown. Ca2+ is the best known ion that acts as a second messenger9, yet the role ascribed to Na+ is to serve as a mere mediator of membrane potential10. Here we show that Na+ acts as a second messenger that regulates OXPHOS function and the production of reactive oxygen species by modulating the fluidity of the inner mitochondrial membrane. A conformational shift in mitochondrial complex I during acute hypoxia11 drives acidification of the matrix and the release of free Ca2+ from calcium phosphate (CaP) precipitates. The concomitant activation of the mitochondrial Na+/Ca2+ exchanger promotes the import of Na+ into the matrix. Na+ interacts with phospholipids, reducing inner mitochondrial membrane fluidity and the mobility of free ubiquinone between complex II and complex III, but not inside supercomplexes. As a consequence, superoxide is produced at complex III. The inhibition of Na+ import through the Na+/Ca2+ exchanger is sufficient to block this pathway, preventing adaptation to hypoxia. These results reveal that Na+ controls OXPHOS function and redox signalling through an unexpected interaction with phospholipids, with profound consequences for cellular metabolism.


Assuntos
Transporte de Elétrons , Hipóxia/metabolismo , Mitocôndrias/metabolismo , Sistemas do Segundo Mensageiro , Sódio/metabolismo , Animais , Neoplasias da Mama/metabolismo , Neoplasias da Mama/patologia , Fosfatos de Cálcio/metabolismo , Linhagem Celular Tumoral , Precipitação Química , Humanos , Masculino , Fluidez de Membrana , Camundongos Endogâmicos C57BL , Membranas Mitocondriais/química , Membranas Mitocondriais/metabolismo , Proteínas Mitocondriais/metabolismo , Fosforilação Oxidativa , Ratos , Ratos Wistar , Espécies Reativas de Oxigênio/metabolismo , Trocador de Sódio e Cálcio/metabolismo
5.
EMBO J ; 39(13): e104073, 2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32432379

RESUMO

Respirometry is the gold standard measurement of mitochondrial oxidative function, as it reflects the activity of the electron transport chain complexes working together. However, the requirement for freshly isolated mitochondria hinders the feasibility of respirometry in multi-site clinical studies and retrospective studies. Here, we describe a novel respirometry approach suited for frozen samples by restoring electron transfer components lost during freeze/thaw and correcting for variable permeabilization of mitochondrial membranes. This approach preserves 90-95% of the maximal respiratory capacity in frozen samples and can be applied to isolated mitochondria, permeabilized cells, and tissue homogenates with high sensitivity. We find that primary changes in mitochondrial function, detected in fresh tissue, are preserved in frozen samples years after collection. This approach will enable analysis of the integrated function of mitochondrial Complexes I to IV in one measurement, collected at remote sites or retrospectively in samples residing in tissue biobanks.


Assuntos
Criopreservação , Complexo de Proteínas da Cadeia de Transporte de Elétrons/metabolismo , Mitocôndrias/metabolismo , Consumo de Oxigênio , Proteínas de Peixe-Zebra/metabolismo , Peixe-Zebra/metabolismo , Animais , Masculino , Camundongos
6.
PLoS Biol ; 19(11): e3001447, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34758018

RESUMO

During the first weeks of postnatal heart development, cardiomyocytes undergo a major adaptive metabolic shift from glycolytic energy production to fatty acid oxidation. This metabolic change is contemporaneous to the up-regulation and activation of the p38γ and p38δ stress-activated protein kinases in the heart. We demonstrate that p38γ/δ contribute to the early postnatal cardiac metabolic switch through inhibitory phosphorylation of glycogen synthase 1 (GYS1) and glycogen metabolism inactivation. Premature induction of p38γ/δ activation in cardiomyocytes of newborn mice results in an early GYS1 phosphorylation and inhibition of cardiac glycogen production, triggering an early metabolic shift that induces a deficit in cardiomyocyte fuel supply, leading to whole-body metabolic deregulation and maladaptive cardiac pathogenesis. Notably, the adverse effects of forced premature cardiac p38γ/δ activation in neonate mice are prevented by maternal diet supplementation of fatty acids during pregnancy and lactation. These results suggest that diet interventions have a potential for treating human cardiac genetic diseases that affect heart metabolism.


Assuntos
Glicogênio Sintase/metabolismo , Proteína Quinase 12 Ativada por Mitógeno/metabolismo , Proteína Quinase 13 Ativada por Mitógeno/metabolismo , Miocárdio/enzimologia , Animais , Animais Recém-Nascidos , Cardiomegalia/enzimologia , Cardiomegalia/patologia , Cardiomegalia/fisiopatologia , Dieta Hiperlipídica , Ativação Enzimática , Comportamento Alimentar , Feminino , Deleção de Genes , Intolerância à Glucose/enzimologia , Glicogênio/metabolismo , Quinase 3 da Glicogênio Sintase/metabolismo , Resistência à Insulina , Metabolismo dos Lipídeos , Sistema de Sinalização das MAP Quinases , Camundongos Endogâmicos C57BL , Miócitos Cardíacos/enzimologia , Especificidade de Órgãos , Fosforilação
7.
Circulation ; 145(14): 1084-1101, 2022 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-35236094

RESUMO

BACKGROUND: In most eukaryotic cells, the mitochondrial DNA (mtDNA) is transmitted uniparentally and present in multiple copies derived from the clonal expansion of maternally inherited mtDNA. All copies are therefore near-identical, or homoplasmic. The presence of >1 mtDNA variant in the same cytoplasm can arise naturally or result from new medical technologies aimed at preventing mitochondrial genetic diseases and improving fertility. The latter is called divergent nonpathologic mtDNA heteroplasmy (DNPH). We hypothesized that DNPH is maladaptive and usually prevented by the cell. METHODS: We engineered and characterized DNPH mice throughout their lifespan using transcriptomic, metabolomic, biochemical, physiologic, and phenotyping techniques. We focused on in vivo imaging techniques for noninvasive assessment of cardiac and pulmonary energy metabolism. RESULTS: We show that DNPH impairs mitochondrial function, with profound consequences in critical tissues that cannot resolve heteroplasmy, particularly cardiac and skeletal muscle. Progressive metabolic stress in these tissues leads to severe pathology in adulthood, including pulmonary hypertension and heart failure, skeletal muscle wasting, frailty, and premature death. Symptom severity is strongly modulated by the nuclear context. CONCLUSIONS: Medical interventions that may generate DNPH should address potential incompatibilities between donor and recipient mtDNA.


Assuntos
Fragilidade , Cardiopatias , Hipertensão Pulmonar , Adulto , Animais , DNA Mitocondrial/genética , Fragilidade/patologia , Cardiopatias/patologia , Heteroplasmia , Humanos , Hipertensão Pulmonar/genética , Hipertensão Pulmonar/patologia , Camundongos , Mitocôndrias/genética
8.
Rev Endocr Metab Disord ; 23(1): 121-131, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34741717

RESUMO

Obesity results from an imbalance in energy homeostasis, whereby excessive energy intake exceeds caloric expenditure. Energy can be dissipated out of an organism by producing heat (thermogenesis), explaining the long-standing interest in exploiting thermogenic processes to counteract obesity. Mitochondrial uncoupling is a process that expends energy by oxidizing nutrients to produce heat, instead of ATP synthesis. Energy can also be dissipated through mechanisms that do not involve mitochondrial uncoupling. Such mechanisms include futile cycles described as metabolic reactions that consume ATP to produce a product from a substrate but then converting the product back into the original substrate, releasing the energy as heat. Energy dissipation driven by cellular ATP demand can be regulated by adjusting the speed and number of futile cycles. Energy consuming futile cycles that are reviewed here are lipolysis/fatty acid re-esterification cycle, creatine/phosphocreatine cycle, and the SERCA-mediated calcium import and export cycle. Their reliance on ATP emphasizes that mitochondrial oxidative function coupled to ATP synthesis, and not just uncoupling, can play a role in thermogenic energy dissipation. Here, we review ATP consuming futile cycles, the evidence for their function in humans, and their potential employment as a strategy to dissipate energy and counteract obesity.


Assuntos
Tecido Adiposo Marrom , Metabolismo Energético , Trifosfato de Adenosina/metabolismo , Tecido Adiposo Marrom/metabolismo , Humanos , Obesidade/metabolismo , Ciclização de Substratos , Termogênese
9.
EMBO Rep ; 21(12): e49634, 2020 12 03.
Artigo em Inglês | MEDLINE | ID: mdl-33275313

RESUMO

Combined fatty acid esterification and lipolysis, termed lipid cycling, is an ATP-consuming process that contributes to energy expenditure. Therefore, interventions that stimulate energy expenditure through lipid cycling are of great interest. Here we find that pharmacological and genetic inhibition of the mitochondrial pyruvate carrier (MPC) in brown adipocytes activates lipid cycling and energy expenditure, even in the absence of adrenergic stimulation. We show that the resulting increase in ATP demand elevates mitochondrial respiration coupled to ATP synthesis and fueled by lipid oxidation. We identify that glutamine consumption and the Malate-Aspartate Shuttle are required for the increase in Energy Expenditure induced by MPC inhibition in Brown Adipocytes (MAShEEBA). We thus demonstrate that energy expenditure through enhanced lipid cycling can be activated in brown adipocytes by decreasing mitochondrial pyruvate availability. We present a new mechanism to increase energy expenditure and fat oxidation in brown adipocytes, which does not require adrenergic stimulation of mitochondrial uncoupling.


Assuntos
Adipócitos Marrons , Ácido Pirúvico , Adipócitos Marrons/metabolismo , Tecido Adiposo Marrom/metabolismo , Metabolismo Energético , Lipídeos , Mitocôndrias/metabolismo , Ácido Pirúvico/metabolismo , Termogênese , Proteína Desacopladora 1/genética , Proteína Desacopladora 1/metabolismo
10.
Nature ; 535(7613): 561-5, 2016 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-27383793

RESUMO

Human mitochondrial DNA (mtDNA) shows extensive within population sequence variability. Many studies suggest that mtDNA variants may be associated with ageing or diseases, although mechanistic evidence at the molecular level is lacking. Mitochondrial replacement has the potential to prevent transmission of disease-causing oocyte mtDNA. However, extension of this technology requires a comprehensive understanding of the physiological relevance of mtDNA sequence variability and its match with the nuclear-encoded mitochondrial genes. Studies in conplastic animals allow comparison of individuals with the same nuclear genome but different mtDNA variants, and have provided both supporting and refuting evidence that mtDNA variation influences organismal physiology. However, most of these studies did not confirm the conplastic status, focused on younger animals, and did not investigate the full range of physiological and phenotypic variability likely to be influenced by mitochondria. Here we systematically characterized conplastic mice throughout their lifespan using transcriptomic, proteomic,metabolomic, biochemical, physiological and phenotyping studies. We show that mtDNA haplotype profoundly influences mitochondrial proteostasis and reactive oxygen species generation,insulin signalling, obesity, and ageing parameters including telomere shortening and mitochondrial dysfunction, resulting in profound differences in health longevity between conplastic strains.


Assuntos
Envelhecimento/genética , Núcleo Celular/genética , DNA Mitocondrial/genética , Variação Genética/genética , Metabolismo/genética , Mitocôndrias/genética , Mitocôndrias/metabolismo , Envelhecimento/fisiologia , Animais , Feminino , Genoma Mitocondrial/genética , Haplótipos , Insulina/metabolismo , Longevidade/genética , Masculino , Metabolismo/fisiologia , Metabolômica , Camundongos , Camundongos Congênicos , Mitocôndrias/patologia , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Obesidade/genética , Obesidade/metabolismo , Fenótipo , Proteômica , Espécies Reativas de Oxigênio/metabolismo , Encurtamento do Telômero , Transcriptoma , Resposta a Proteínas não Dobradas
11.
EMBO J ; 36(22): 3356-3371, 2017 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-29018038

RESUMO

In the amyloidogenic pathway associated with Alzheimer disease (AD), the amyloid precursor protein (APP) is cleaved by ß-secretase to generate a 99-aa C-terminal fragment (C99) that is then cleaved by γ-secretase to generate the ß-amyloid (Aß) found in senile plaques. In previous reports, we and others have shown that γ-secretase activity is enriched in mitochondria-associated endoplasmic reticulum (ER) membranes (MAM) and that ER-mitochondrial connectivity and MAM function are upregulated in AD We now show that C99, in addition to its localization in endosomes, can also be found in MAM, where it is normally processed rapidly by γ-secretase. In cell models of AD, however, the concentration of unprocessed C99 increases in MAM regions, resulting in elevated sphingolipid turnover and an altered lipid composition of both MAM and mitochondrial membranes. In turn, this change in mitochondrial membrane composition interferes with the proper assembly and activity of mitochondrial respiratory supercomplexes, thereby likely contributing to the bioenergetic defects characteristic of AD.


Assuntos
Doença de Alzheimer/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Retículo Endoplasmático/metabolismo , Membranas Intracelulares/metabolismo , Mitocôndrias/metabolismo , Doença de Alzheimer/patologia , Secretases da Proteína Precursora do Amiloide/metabolismo , Animais , Linhagem Celular , Respiração Celular , Retículo Endoplasmático/ultraestrutura , Humanos , Membranas Intracelulares/ultraestrutura , Camundongos , Mitocôndrias/ultraestrutura , Mutação/genética , Consumo de Oxigênio , Presenilinas/genética , Transporte Proteico , Esfingolipídeos/metabolismo , Regulação para Cima
12.
PLoS Biol ; 16(7): e2004455, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29979672

RESUMO

Adipose tissue has emerged as an important regulator of whole-body metabolism, and its capacity to dissipate energy in the form of heat has acquired a special relevance in recent years as potential treatment for obesity. In this context, the p38MAPK pathway has arisen as a key player in the thermogenic program because it is required for the activation of brown adipose tissue (BAT) thermogenesis and participates also in the transformation of white adipose tissue (WAT) into BAT-like depot called beige/brite tissue. Here, using mice that are deficient in p38α specifically in adipose tissue (p38αFab-KO), we unexpectedly found that lack of p38α protected against high-fat diet (HFD)-induced obesity. We also showed that p38αFab-KO mice presented higher energy expenditure due to increased BAT thermogenesis. Mechanistically, we found that lack of p38α resulted in the activation of the related protein kinase family member p38δ. Our results showed that p38δ is activated in BAT by cold exposure, and lack of this kinase specifically in adipose tissue (p38δ Fab-KO) resulted in overweight together with reduced energy expenditure and lower body and skin surface temperature in the BAT region. These observations indicate that p38α probably blocks BAT thermogenesis through p38δ inhibition. Consistent with the results obtained in animals, p38α was reduced in visceral and subcutaneous adipose tissue of subjects with obesity and was inversely correlated with body mass index (BMI). Altogether, we have elucidated a mechanism implicated in physiological BAT activation that has potential clinical implications for the treatment of obesity and related diseases such as diabetes.


Assuntos
Tecido Adiposo Marrom/enzimologia , Tecido Adiposo Marrom/fisiologia , Proteína Quinase 13 Ativada por Mitógeno/antagonistas & inibidores , Proteína Quinase 14 Ativada por Mitógeno/metabolismo , Termogênese , Adipócitos Marrons/enzimologia , Adulto , Animais , Índice de Massa Corporal , Diabetes Mellitus Experimental/enzimologia , Diabetes Mellitus Experimental/prevenção & controle , Dieta , Metabolismo Energético , Ativação Enzimática , Humanos , Sistema de Sinalização das MAP Quinases , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteína Quinase 13 Ativada por Mitógeno/metabolismo , Modelos Biológicos , Obesidade/enzimologia , Obesidade/prevenção & controle , Proteína Desacopladora 1/metabolismo
13.
PLoS Pathog ; 13(10): e1006651, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29077752

RESUMO

The interferon (IFN)-stimulated gene 15 (ISG15) encodes one of the most abundant proteins induced by interferon, and its expression is associated with antiviral immunity. To identify protein components implicated in IFN and ISG15 signaling, we compared the proteomes of ISG15-/- and ISG15+/+ bone marrow derived macrophages (BMDM) after vaccinia virus (VACV) infection. The results of this analysis revealed that mitochondrial dysfunction and oxidative phosphorylation (OXPHOS) were pathways altered in ISG15-/- BMDM treated with IFN. Mitochondrial respiration, Adenosine triphosphate (ATP) and reactive oxygen species (ROS) production was higher in ISG15+/+ BMDM than in ISG15-/- BMDM following IFN treatment, indicating the involvement of ISG15-dependent mechanisms. An additional consequence of ISG15 depletion was a significant change in macrophage polarization. Although infected ISG15-/- macrophages showed a robust proinflammatory cytokine expression pattern typical of an M1 phenotype, a clear blockade of nitric oxide (NO) production and arginase-1 activation was detected. Accordingly, following IFN treatment, NO release was higher in ISG15+/+ macrophages than in ISG15-/- macrophages concomitant with a decrease in viral titer. Thus, ISG15-/- macrophages were permissive for VACV replication following IFN treatment. In conclusion, our results demonstrate that ISG15 governs the dynamic functionality of mitochondria, specifically, OXPHOS and mitophagy, broadening its physiological role as an antiviral agent.


Assuntos
Citocinas/metabolismo , Macrófagos/metabolismo , Mitocôndrias/metabolismo , Mitofagia , Vaccinia virus/metabolismo , Vacínia/metabolismo , Animais , Arginase/genética , Arginase/metabolismo , Citocinas/genética , Ativação Enzimática/genética , Macrófagos/patologia , Camundongos , Camundongos Knockout , Mitocôndrias/genética , Mitocôndrias/patologia , Óxido Nítrico/metabolismo , Fosforilação Oxidativa , Ubiquitinas/genética , Ubiquitinas/metabolismo , Vacínia/genética
15.
J Cell Sci ; 127(Pt 17): 3768-81, 2014 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-24994937

RESUMO

Cell-cell adhesions are important sites through which cells experience and resist forces. In endothelial cells, these forces regulate junction dynamics and determine endothelial barrier strength. We identify the Ig superfamily member EMMPRIN (also known as basigin) as a coordinator of forces at endothelial junctions. EMMPRIN localization at junctions correlates with endothelial junction strength in different mouse vascular beds. Accordingly, EMMPRIN-deficient mice show altered junctions and increased junction permeability. Lack of EMMPRIN alters the localization and function of VE-cadherin (also known as cadherin-5) by decreasing both actomyosin contractility and tugging forces at endothelial cell junctions. EMMPRIN ensures proper actomyosin-driven maturation of competent endothelial junctions by forming a molecular complex with γ-catenin (also known as junction plakoglobin) and Nm23 (also known as NME1), a nucleoside diphosphate kinase, thereby locally providing ATP to fuel the actomyosin machinery. These results provide a novel mechanism for the regulation of actomyosin contractility at endothelial junctions and might have broader implications in biological contexts such as angiogenesis, collective migration and tissue morphogenesis by coupling compartmentalized energy production to junction assembly.


Assuntos
Actomiosina/metabolismo , Trifosfato de Adenosina/biossíntese , Basigina/metabolismo , Células Endoteliais/citologia , Nucleosídeo NM23 Difosfato Quinases/metabolismo , gama Catenina/metabolismo , Animais , Adesão Celular/fisiologia , Membrana Celular/metabolismo , Células Cultivadas , Proteínas do Citoesqueleto/biossíntese , Endotélio Vascular/metabolismo , Junções Intercelulares/metabolismo , Camundongos
16.
Mol Cell ; 32(4): 529-39, 2008 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-19026783

RESUMO

The structural organization of the mitochondrial respiratory complexes as four big independently moving entities connected by the mobile carriers CoQ and cytochrome c has been challenged recently. Blue native gel electrophoresis reveals the presence of high-molecular-weight bands containing several respiratory complexes and suggesting an in vivo assembly status of these structures (respirasomes). However, no functional evidence of the activity of supercomplexes as true respirasomes has been provided yet. We have observed that (1) supercomplexes are not formed when one of their component complexes is absent; (2) there is a temporal gap between the formation of the individual complexes and that of the supercomplexes; (3) some putative respirasomes contain CoQ and cytochrome c; (4) isolated respirasomes can transfer electrons from NADH to O(2), that is, they respire. Therefore, we have demonstrated the existence of a functional respirasome and propose a structural organization model that accommodates these findings.


Assuntos
Transporte de Elétrons , Mitocôndrias/metabolismo , Animais , Respiração Celular , Citocromos c/metabolismo , Complexo I de Transporte de Elétrons/metabolismo , Complexo III da Cadeia de Transporte de Elétrons/metabolismo , Células L , Fígado/citologia , Fígado/metabolismo , Camundongos , Membranas Mitocondriais/metabolismo , ATPases Mitocondriais Próton-Translocadoras/química , ATPases Mitocondriais Próton-Translocadoras/metabolismo , Modelos Biológicos , NAD/metabolismo , Fosforilação Oxidativa , Ubiquinona/metabolismo
17.
Biochim Biophys Acta ; 1837(4): 444-50, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24368156

RESUMO

Mitochondria are important organelles not only as efficient ATP generators but also in controlling and regulating many cellular processes. Mitochondria are dynamic compartments that rearrange under stress response and changes in food availability or oxygen concentrations. The mitochondrial electron transport chain parallels these rearrangements to achieve an optimum performance and therefore requires a plastic organization within the inner mitochondrial membrane. This consists in a balanced distribution between free respiratory complexes and supercomplexes. The mechanisms by which the distribution and organization of supercomplexes can be adjusted to the needs of the cells are still poorly understood. The aim of this review is to focus on the functional role of the respiratory supercomplexes and its relevance in physiology. This article is part of a Special Issue entitled: Dynamic and ultrastructure of bioenergetic membranes and their components.


Assuntos
Respiração Celular , Mitocôndrias/metabolismo , Complexos Multienzimáticos/metabolismo , Fosforilação Oxidativa , Citocromos c/metabolismo , Transporte de Elétrons , Membranas Mitocondriais/metabolismo , Modelos Biológicos , Espécies Reativas de Oxigênio/metabolismo , Ubiquinona/metabolismo
18.
Biochim Biophys Acta ; 1843(11): 2403-13, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25038307

RESUMO

Endothelial cells in the vascular system are constantly subjected to the frictional force of shear stress due to the pulsatile nature of blood flow. Although several proteins form part of the shear stress mechano-sensing pathway, the identification of mechano-transducing pathways is largely unknown. Given the increasing evidence for a signaling function of mitochondria in endothelial cells, the aim of this study was to investigate their role as mechano-sensor organelles during laminar shear stress (LSS). We demonstrated that LSS activates intracellular signaling pathways that modulate not only mitochondrial dynamics but also mitochondrial function. At early time points of LSS, the fission-related protein Drp1 was recruited from the cytosol to mitochondria and activated mitochondrial fission. LSS-dependent increase in intracellular Ca(2+) concentration was indispensable for mitochondrial fission. As alterations in mitochondrial dynamics have been related to changes in bioenergetics profiles, we studied mitochondrial function after LSS. We found that LSS decreased respiration rate, increased mitochondrial membrane potential and promoted the mitochondrial generation of ROS with the subsequent oxidation and activation of the antioxidant enzyme PRX3. Our data support a novel and active role for mitochondria in endothelial cells as active players, able to transduce the mechanical force of shear stress in the vascular endothelium into a biological response.

19.
Hum Mol Genet ; 22(6): 1233-48, 2013 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-23255162

RESUMO

Coenzyme Q10 (CoQ(10)) or ubiquinone is a well-known component of the mitochondrial respiratory chain. In humans, CoQ(10) deficiency causes a mitochondrial syndrome with an unexplained variability in the clinical presentations. To try to understand this heterogeneity in the clinical phenotypes, we have generated a Coq9 Knockin (R239X) mouse model. The lack of a functional Coq9 protein in homozygous Coq9 mutant (Coq9(X/X)) mice causes a severe reduction in the Coq7 protein and, as consequence, a widespread CoQ deficiency and accumulation of demethoxyubiquinone. The deficit in CoQ induces a brain-specific impairment of mitochondrial bioenergetics performance, a reduction in respiratory control ratio, ATP levels and ATP/ADP ratio and specific loss of respiratory complex I. These effects lead to neuronal death and demyelinization with severe vacuolization and astrogliosis in the brain of Coq9(X/X) mice that consequently die between 3 and 6 months of age. These results suggest that the instability of mitochondrial complex I in the brain, as a primary event, triggers the development of mitochondrial encephalomyopathy associated with CoQ deficiency.


Assuntos
Encefalomiopatias Mitocondriais/enzimologia , Ubiquinona/deficiência , Difosfato de Adenosina/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Encéfalo/metabolismo , Complexo I de Transporte de Elétrons/genética , Complexo I de Transporte de Elétrons/metabolismo , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Encefalomiopatias Mitocondriais/genética , Ubiquinona/genética , Ubiquinona/metabolismo
20.
Nat Genet ; 38(11): 1261-8, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17013393

RESUMO

Common mitochondrial DNA (mtDNA) haplotypes in humans and mice have been associated with various phenotypes, including learning performance and disease penetrance. Notably, no influence of mtDNA haplotype in cell respiration has been demonstrated. Here, using cell lines carrying four different common mouse mtDNA haplotypes in an identical nuclear background, we show that the similar level of respiration among the cell lines is only apparent and is a consequence of compensatory mechanisms triggered by different production of reactive oxygen species. We observe that the respiration capacity per molecule of mtDNA in cells with the NIH3T3 or NZB mtDNA is lower than in those with the C57BL/6J, CBA/J or BALB/cJ mtDNA. In addition, we have determined the genetic element underlying these differences. Our data provide insight into the molecular basis of the complex phenotypes associated with common mtDNA variants and anticipate a relevant contribution of mtDNA single nucleotide polymorphisms to phenotypic variability in humans.


Assuntos
DNA Mitocondrial/análise , Variação Genética , Fenótipo , Espécies Reativas de Oxigênio/metabolismo , Adaptação Biológica , Animais , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Ciclo do Ácido Cítrico , Cruzamentos Genéticos , Embrião de Mamíferos , Galactose/farmacologia , Haplótipos , Peróxido de Hidrogênio/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C3H , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CBA , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/enzimologia , Mitocôndrias/genética , Células NIH 3T3 , Polimorfismo Genético , Espécies Reativas de Oxigênio/farmacologia , Transdução de Sinais
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA