RESUMO
Exercise is a nonpharmacological intervention that improves health during aging and a valuable tool in the diagnostics of aging-related diseases. In muscle, exercise transiently alters mitochondrial functionality and metabolism. Mitochondrial fission and fusion are critical effectors of mitochondrial plasticity, which allows a fine-tuned regulation of organelle connectiveness, size, and function. Here we have investigated the role of mitochondrial dynamics during exercise in the model organism Caenorhabditis elegans. We show that in body-wall muscle, a single exercise session induces a cycle of mitochondrial fragmentation followed by fusion after a recovery period, and that daily exercise sessions delay the mitochondrial fragmentation and physical fitness decline that occur with aging. Maintenance of proper mitochondrial dynamics is essential for physical fitness, its enhancement by exercise training, and exercise-induced remodeling of the proteome. Surprisingly, among the long-lived genotypes we analyzed (isp-1,nuo-6, daf-2, eat-2, and CA-AAK-2), constitutive activation of AMP-activated protein kinase (AMPK) uniquely preserves physical fitness during aging, a benefit that is abolished by impairment of mitochondrial fission or fusion. AMPK is also required for physical fitness to be enhanced by exercise, with our findings together suggesting that exercise may enhance muscle function through AMPK regulation of mitochondrial dynamics. Our results indicate that mitochondrial connectivity and the mitochondrial dynamics cycle are essential for maintaining physical fitness and exercise responsiveness during aging and suggest that AMPK activation may recapitulate some exercise benefits. Targeting mechanisms to optimize mitochondrial fission and fusion, as well as AMPK activation, may represent promising strategies for promoting muscle function during aging.
Assuntos
Proteínas Quinases Ativadas por AMP , Dinâmica Mitocondrial , Animais , Dinâmica Mitocondrial/fisiologia , Proteínas Quinases Ativadas por AMP/genética , Proteínas Quinases Ativadas por AMP/metabolismo , Envelhecimento/fisiologia , Caenorhabditis elegans/metabolismo , Exercício Físico , Aptidão Física , Músculo Esquelético/metabolismoRESUMO
Accumulating evidences suggest that inflammation-mediated neurons dysfunction participates in the initial and development of Parkinson's disease (PD), whereas mitochondria have been recently recognized as crucial regulators in NLRP3 inflammasome activation. Cordycepin, a major component of cordyceps militaris, has been shown to possess neuroprotective and anti-inflammatory activity. However, the effects of cordycepin in rotenone-induced PD models and the possible mechanisms are still not fully understood. Here, we observed that motor dysfunction and dopaminergic neurons loss induced by rotenone exposure were ameliorated by cordycepin. Cordycepin also reversed Drp1-mediated aberrant mitochondrial fragmentation through increasing AMPK phosphorylation and maintained normal mitochondrial morphology. Additionally, cordycepin effectively increased adenosine 5'-triphosphate (ATP) content, mitochondrial membrane potential (MMP), and reduced mitochondrial ROS levels, as well as inhibited complex 1 activity. More importantly, cordycepin administration inhibited the expression of NLRP3 inflammasome components and the release of pro-inflammatory cytokine in rotenone-induced rats and cultured neuronal PC12 cells. Moreover, we demonstrated that the activation of NLRP3 inflammasome within neurons could be suppressed by the mitochondrial division inhibitor (Mdivi-1). Collectively, the present study provides evidence that cordycepin exerts neuroprotective effects partially through preventing neural NLRP3 inflammasome activation induced by Drp1-dependent mitochondrial fragmentation in rotenone-injected PD models.
Assuntos
Anti-Inflamatórios/uso terapêutico , Desoxiadenosinas/uso terapêutico , Dinaminas/antagonistas & inibidores , Dinâmica Mitocondrial/efeitos dos fármacos , Fármacos Neuroprotetores/uso terapêutico , Transtornos Parkinsonianos/tratamento farmacológico , Rotenona/toxicidade , Animais , Anti-Inflamatórios/farmacologia , Desoxiadenosinas/farmacologia , Relação Dose-Resposta a Droga , Dinaminas/metabolismo , Inseticidas/toxicidade , Masculino , Dinâmica Mitocondrial/fisiologia , Proteína 3 que Contém Domínio de Pirina da Família NLR/antagonistas & inibidores , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Fármacos Neuroprotetores/farmacologia , Células PC12 , Transtornos Parkinsonianos/induzido quimicamente , Transtornos Parkinsonianos/metabolismo , Ratos , Ratos Sprague-DawleyRESUMO
BACKGROUND: The lack of effective treatments for Alzheimer's disease (AD) reflects an incomplete understanding of disease mechanisms. Alterations in proteins involved in mitochondrial dynamics, an essential process for mitochondrial integrity and function, have been reported in AD brains. Impaired mitochondrial dynamics causes mitochondrial dysfunction and has been associated with cognitive impairment in AD. Here, we investigated a possible link between pro-inflammatory interleukin-1 (IL-1), mitochondrial dysfunction, and cognitive impairment in AD models. METHODS: We exposed primary hippocampal cell cultures to amyloid-ß oligomers (AßOs) and carried out AßO infusions into the lateral cerebral ventricle of cynomolgus macaques to assess the impact of AßOs on proteins that regulate mitochondrial dynamics. Where indicated, primary cultures were pre-treated with mitochondrial division inhibitor 1 (mdivi-1), or with anakinra, a recombinant interleukin-1 receptor (IL-1R) antagonist used in the treatment of rheumatoid arthritis. Cognitive impairment was investigated in C57BL/6 mice that received an intracerebroventricular (i.c.v.) infusion of AßOs in the presence or absence of mdivi-1. To assess the role of interleukin-1 beta (IL-1ß) in AßO-induced alterations in mitochondrial proteins and memory impairment, interleukin receptor-1 knockout (Il1r1-/-) mice received an i.c.v. infusion of AßOs. RESULTS: We report that anakinra prevented AßO-induced alteration in mitochondrial dynamics proteins in primary hippocampal cultures. Altered levels of proteins involved in mitochondrial fusion and fission were observed in the brains of cynomolgus macaques that received i.c.v. infusions of AßOs. The mitochondrial fission inhibitor, mdivi-1, alleviated synapse loss and cognitive impairment induced by AßOs in mice. In addition, AßOs failed to cause alterations in expression of mitochondrial dynamics proteins or memory impairment in Il1r1-/- mice. CONCLUSION: These findings indicate that IL-1ß mediates the impact of AßOs on proteins involved in mitochondrial dynamics and that strategies aimed to prevent pathological alterations in those proteins may counteract synapse loss and cognitive impairment in AD.
Assuntos
Peptídeos beta-Amiloides/toxicidade , Interleucina-1beta/biossíntese , Transtornos da Memória/induzido quimicamente , Transtornos da Memória/metabolismo , Dinâmica Mitocondrial/fisiologia , Fragmentos de Peptídeos/toxicidade , Animais , Feminino , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Macaca fascicularis , Masculino , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Potencial da Membrana Mitocondrial/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Dinâmica Mitocondrial/efeitos dos fármacos , RatosRESUMO
Several studies suggest that the assembly of mitochondrial respiratory complexes into structures known as supercomplexes (SCs) may increase the efficiency of the electron transport chain, reducing the rate of production of reactive oxygen species. Therefore, the study of the (dis)assembly of SCs may be relevant for the understanding of mitochondrial dysfunction reported in brain aging and major neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD). Here we briefly reviewed the biogenesis and structural properties of SCs, the impact of mtDNA mutations and mitochondrial dynamics on SCs assembly, the role of lipids on stabilization of SCs and the methodological limitations for the study of SCs. More specifically, we summarized what is known about mitochondrial dysfunction and SCs organization and activity in aging, AD and PD. We focused on the critical variables to take into account when postmortem tissues are used to study the (dis)assembly of SCs. Since few works have been performed to study SCs in AD and PD, the impact of SCs dysfunction on the alteration of brain energetics in these diseases remains poorly understood. The convergence of future progress in the study of SCs structure at high resolution and the refinement of animal models of AD and PD, as well as the use of iPSC-based and somatic cell-derived neurons, will be critical in understanding the biological relevance of the structural remodeling of SCs.
Assuntos
Encéfalo/metabolismo , Metabolismo Energético/fisiologia , Mitocôndrias/metabolismo , Dinâmica Mitocondrial/fisiologia , Doenças Neurodegenerativas/metabolismo , Neurônios/metabolismo , Envelhecimento/metabolismo , Envelhecimento/patologia , Animais , Encéfalo/patologia , Complexo I de Transporte de Elétrons/genética , Complexo I de Transporte de Elétrons/metabolismo , Complexo IV da Cadeia de Transporte de Elétrons/genética , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Humanos , Mitocôndrias/patologia , Doenças Neurodegenerativas/patologia , Neurônios/patologia , Espécies Reativas de Oxigênio/metabolismoRESUMO
Offspring born to obese and diabetic mothers are prone to metabolic diseases, a phenotype that has been linked to mitochondrial dysfunction and endoplasmic reticulum (ER) stress in oocytes. In addition, metabolic diseases impact the architecture and function of mitochondria-ER contact sites (MERCs), changes which associate with mitofusin 2 (MFN2) repression in muscle, liver and hypothalamic neurons. MFN2 is a potent modulator of mitochondrial metabolism and insulin signaling, with a key role in mitochondrial dynamics and tethering with the ER. Here, we investigated whether offspring born to mice with MFN2-deficient oocytes are prone to obesity and diabetes. Deletion of Mfn2 in oocytes resulted in a profound transcriptomic change, with evidence of impaired mitochondrial and ER function. Moreover, offspring born to females with oocyte-specific deletion of Mfn2 presented increased weight gain and glucose intolerance. This abnormal phenotype was linked to decreased insulinemia and defective insulin signaling, but not mitochondrial and ER defects in offspring liver and skeletal muscle. In conclusion, this study suggests a link between disrupted mitochondrial/ER function in oocytes and increased risk of metabolic diseases in the progeny. Future studies should determine whether MERC architecture and function are altered in oocytes from obese females, which might contribute toward transgenerational transmission of metabolic diseases.
Assuntos
GTP Fosfo-Hidrolases/metabolismo , Oócitos/metabolismo , Animais , Retículo Endoplasmático/metabolismo , Estresse do Retículo Endoplasmático/fisiologia , Feminino , GTP Fosfo-Hidrolases/genética , Homeostase/fisiologia , Camundongos , Mitocôndrias/metabolismo , Dinâmica Mitocondrial/fisiologia , Músculo Esquelético/metabolismo , Transdução de SinaisRESUMO
Binge drinking is the consumption of large volumes of alcohol in short periods and exerts its effects on the central nervous system, including the hippocampus. We have previously shown that binge drinking alters mitochondrial dynamics and induces neuroinflammation in the hippocampus of adolescent rats. Mild traumatic brain injury (mTBI), is regularly linked to alcohol consumption and share mechanisms of brain damage. In this context, we hypothesized that adolescent binge drinking could prime the development of brain damage generated by mTBI. We found that alcohol binge drinking induced by the "drinking in the dark" (DID) paradigm increases oxidative damage and astrocyte activation in the hippocampus of adolescent mice. Interestingly, adolescent animals submitted to DID showed decreased levels of mitofusin 2 that controls mitochondrial dynamics. When mTBI was evaluated as a second challenge, hippocampi from animals previously submitted to DID showed a reduction in dendritic spine number and a different spine profile. Mitochondrial performance could be compromised by alterations in mitochondrial fission in DID-mTBI animals. These data suggest that adolescent alcohol consumption can modify the progression of mTBI pathophysiology. We propose that mitochondrial impairment and oxidative damage could act as priming factors, modifying predisposition against mTBI effects.
Assuntos
Consumo de Bebidas Alcoólicas/efeitos adversos , Consumo de Bebidas Alcoólicas/fisiopatologia , Lesões Encefálicas Traumáticas/fisiopatologia , Hipocampo/fisiopatologia , Maturidade Sexual/fisiologia , Consumo de Bebidas Alcoólicas/patologia , Animais , Consumo Excessivo de Bebidas Alcoólicas/complicações , Consumo Excessivo de Bebidas Alcoólicas/patologia , Consumo Excessivo de Bebidas Alcoólicas/fisiopatologia , Lesões Encefálicas Traumáticas/complicações , Lesões Encefálicas Traumáticas/patologia , Espinhas Dendríticas/patologia , Modelos Animais de Doenças , Hipocampo/patologia , Inflamação/etiologia , Inflamação/patologia , Inflamação/fisiopatologia , Peroxidação de Lipídeos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Dinâmica Mitocondrial/fisiologia , Estresse OxidativoRESUMO
Membrane tension pores determine organelle dynamics and functions, giving rise to physical observables during the cell death process. While fluorescent organelle-targeted probes for specific chemical analytes are increasingly available, subcellular dynamic processes involving not only chemical parameters but also physicochemical and physical parameters are uncommon. Here, we report a mitochondrial chemical probe, named RCN, rationally designed to monitor osmotic effects during transmembrane tension pore formation by using local mitochondrial polarity and a subcellular localization redistribution property of the probe. Utilizing fluorescence spectroscopy, high-resolution confocal imaging, and spectrally resolved confocal microscopy, we provide a new correlation between mitochondrial dynamics and bleb vesicle formation using osmotic pressure stimuli in the cell, where the mitochondrial local polarity was found to drastically increase. The RCN provides a reliable protocol to assess transmembrane pore formation driven by osmotic pressure increments through local polarity variations and is a more robust physicochemical parameter allowing the health and decease status of the cell to be measured.
Assuntos
Corantes Fluorescentes/química , Microscopia Confocal , Mitocôndrias/química , Dinâmica Mitocondrial/fisiologia , Linhagem Celular Tumoral , Humanos , Pressão Osmótica/fisiologiaRESUMO
3-Hydroxy-3-methylglutaryl-CoA lyase (HL) deficiency is a neurometabolic disorder characterized by predominant accumulation of 3-hydroxy-3-methylglutaric acid (HMG) in tissues and biological fluids. Patients often present in the first year of life with metabolic acidosis, non-ketotic hypoglycemia, hypotonia, lethargy, and coma. Since neurological symptoms may be triggered or worsened during episodes of metabolic decompensation, which are characterized by high urinary excretion of organic acids, this study investigated the effects of HMG intracerebroventricular administration on redox homeostasis, citric acid cycle enzyme activities, dynamics (mitochondrial fusion and fission), and endoplasmic reticulum (ER)-mitochondria crosstalk in the brain of neonatal rats euthanized 1 (short term) or 20 days (long term) after injection. HMG induced lipid peroxidation and decreased the activities of glutathione peroxidase (GPx) and citric acid cycle enzymes, suggesting bioenergetic and redox disruption, 1 day after administration. Levels of VDAC1, Grp75, and mitofusin-1, proteins involved in ER-mitochondria crosstalk and mitochondrial fusion, were increased by HMG. Furthermore, HMG diminished synaptophysin levels and tau phosphorylation, and increased active caspase-3 content, indicative of cell damage. Finally, HMG decreased GPx activity and synaptophysin levels, and changed MAPK phosphorylation 20 days after injection, suggesting that long-term toxicity is further induced by this organic acid. Taken together, these data show that HMG induces oxidative stress and disrupts bioenergetics, dynamics, ER-mitochondria communication, and signaling pathways in the brain of rats soon after birth. It may be presumed that these mechanisms underlie the onset and progression of symptoms during decompensation occurring in HL-deficient patients during the neonatal period.
Assuntos
Encéfalo/efeitos dos fármacos , Retículo Endoplasmático/efeitos dos fármacos , Metabolismo Energético/efeitos dos fármacos , Homeostase/efeitos dos fármacos , Meglutol/toxicidade , Dinâmica Mitocondrial/efeitos dos fármacos , Animais , Encéfalo/metabolismo , Retículo Endoplasmático/metabolismo , Metabolismo Energético/fisiologia , Feminino , Homeostase/fisiologia , Masculino , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Dinâmica Mitocondrial/fisiologia , Oxirredução/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/fisiologia , Ratos , Ratos WistarRESUMO
Age-related macular degeneration (AMD) is a multifactorial retinal disease characterized by a progressive loss of central vision. Retinal pigment epithelium (RPE) degeneration is a critical event in AMD. It has been associated to A2E accumulation, which sensitizes RPE to blue light photodamage. Mitochondrial quality control mechanisms have evolved to ensure mitochondrial integrity and preserve cellular homeostasis. Particularly, mitochondrial dynamics involve the regulation of mitochondrial fission and fusion to preserve a healthy mitochondrial network. The present study aims to clarify the cellular and molecular mechanisms underlying photodamage-induced RPE cell death with particular focus on the involvement of defective mitochondrial dynamics. Light-emitting diodes irradiation (445 ± 18 nm; 4.43 mW/cm2) significantly reduced the viability of both unloaded and A2E-loaded human ARPE-19 cells and increased reactive oxygen species production. A2E along with blue light, triggered apoptosis measured by MC540/PI-flow cytometry and activated caspase-3. Blue light induced mitochondrial fusion/fission imbalance towards mitochondrial fragmentation in both non-loaded and A2E-loaded cells which correlated with the deregulation of mitochondria-shaping proteins level (OPA1, DRP1 and OMA1). To our knowledge, this is the first work reporting that photodamage causes mitochondrial dynamics deregulation in RPE cells. This process could possibly contribute to AMD pathology. Our findings suggest that the regulation of mitochondrial dynamics may be a valuable strategy for treating retinal degeneration diseases, such as AMD.
Assuntos
Luz/efeitos adversos , Degeneração Macular/patologia , Epitélio Pigmentado da Retina/patologia , Retinoides/metabolismo , Apoptose/fisiologia , Linhagem Celular , Humanos , Degeneração Macular/etiologia , Dinâmica Mitocondrial/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Epitélio Pigmentado da Retina/citologiaRESUMO
HIG2A promotes cell survival under hypoxia and mediates the assembly of complex III and complex IV into respiratory chain supercomplexes. In the present study, we show that human HIGD2A and mouse Higd2a gene expressions are regulated by hypoxia, glucose, and the cell cycle-related transcription factor E2F1. The latter was found to bind the promoter region of HIGD2A. Differential expression of the HIGD2A gene was found in C57BL/6 mice in relation to tissue and age. Besides, the silencing of HIGD2A evidenced the modulation of mitochondrial dynamics proteins namely, OPA1 as a fusion protein increases, while FIS1, a fission protein, decreases. Besides, the mitochondrial membrane potential (ΔΨm) increased. The protein HIG2A is localized in the mitochondria and nucleus. Moreover, we observed that the HIG2A protein interacts with OPA1. Changes in oxygen concentration, glucose availability, and cell cycle regulate HIGD2A expression. Alterations in HIGD2A expression are associated with changes in mitochondrial physiology.