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Circulating tumor cells (CTCs) are some of the key culprits that cause cancer metastasis and metastasis-related deaths. These cells exist in a dynamic microenvironment where they experience fluid shear stress (FSS), and the CTCs that survive FSS are considered to be highly metastatic and stem cell-like. Biophysical stresses such as FSS are also known to cause the production of extracellular vesicles (EVs) that can facilitate cell-cell communication by carrying biomolecular cargos such as microRNAs. Here, we hypothesized that physiological FSS will impact the yield of EV production, and that these EVs will have biomolecules that transform the recipient cells. The EVs were isolated using direct flow filtration with and without FSS from the MDA-MB-231 cancer cell line, and the expression of key stemness-related genes and microRNAs was characterized. There was a significantly increased yield of EVs under FSS. These EVs also contained significantly increased levels of miR-21, which was previously implicated to promote metastatic progression and chemotherapeutic resistance. When these EVs from FSS were introduced to MCF-7 cancer cells, the recipient cells had a significant increase in their stem-like gene expression and CD44+/CD24- cancer stem cell-like subpopulation. There was also a correlated increased proliferation along with an increased ATP production. Together, these findings indicate that the presence of physiological FSS can directly influence the EVs' production and their contents, and that the EV-mediated transfer of miR-21 can have an important role in FSS-existing contexts, such as in cancer metastasis.
Assuntos
Neoplasias da Mama , Vesículas Extracelulares , MicroRNAs , Células-Tronco Neoplásicas , Humanos , Vesículas Extracelulares/metabolismo , Neoplasias da Mama/patologia , Neoplasias da Mama/metabolismo , Neoplasias da Mama/genética , Células-Tronco Neoplásicas/metabolismo , Células-Tronco Neoplásicas/patologia , Feminino , MicroRNAs/genética , MicroRNAs/metabolismo , Células MCF-7 , Linhagem Celular Tumoral , Estresse Mecânico , Células Neoplásicas Circulantes/metabolismo , Células Neoplásicas Circulantes/patologia , Regulação Neoplásica da Expressão Gênica , Fenótipo , Antígeno CD24/metabolismo , Antígeno CD24/genéticaRESUMO
Cerebral ischemia, a condition with insufficient blood flow in the brain, is associated with cognitive and behavioral changes. The underlying cellular mechanisms of ischemia-induced brain damage include oxidative stress and inflammation. Cerebral ischemia is a major cause of death and long-term disability; thus, investigating novel dietary sources and their therapeutic potentials have gained interest. Seaweed contains various functional phytochemicals with antioxidant and anti-inflammatory effects. Studies have reported that consumption of seaweed is negatively associated with the risk of cardiovascular disease and stroke in humans, but the cellular mechanisms of seaweed's effects are less known. In this review, we discuss the neuroprotective roles of seaweed phytochemicals in various models of cerebral ischemia. We further describe the potential cellular mechanisms such as the effect of seaweed phytochemicals in ischemia-mediated oxidative stress and inflammation. Additional preclinical studies are needed to develop effective dietary interventions for the prevention of ischemia-associated brain damage in humans.
Assuntos
Isquemia Encefálica , Fármacos Neuroprotetores , Alga Marinha , Animais , Humanos , Roedores , Fármacos Neuroprotetores/uso terapêutico , Fármacos Neuroprotetores/farmacologia , Isquemia Encefálica/tratamento farmacológico , Estresse Oxidativo , Compostos Fitoquímicos/farmacologia , Compostos Fitoquímicos/uso terapêutico , Inflamação/tratamento farmacológico , VerdurasRESUMO
Cognitive decline occurs commonly as people age. Despite the complexity of cellular mechanisms, oxidative stress is a critical contributor to age-associated cognitive impairment. Selenium plays an important role in antioxidant defense systems. The purpose of the present study was to assess the correlation between selenium intake and cognitive function among older adults. The participants were individuals ≥65 years old (n=1681) who participated in the 2011-2014 National Health and Nutrition Examination Survey (NHANES), a country-wide cross-sectional survey. Dietary selenium intake and adequacy were evaluated with 2 d of 24-h recalls and the estimated average requirement (EAR) cut-point method, respectively. Cognitive function was assessed with the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) score, which was significantly higher when selenium intake was adequate. After adjusting for energy intake, the association was no longer significant. Inadequate intake of selenium is rare in the US and dependent on caloric intake in older adults.
Assuntos
Selênio , Humanos , Idoso , Inquéritos Nutricionais , Estudos Transversais , Cognição , Estado NutricionalRESUMO
Whole-exome sequencing of Parkinson's disease (PD) patient DNA identified single-nucleotide polymorphisms (SNPs) in the tyrosine nonreceptor kinase-2 (TNK2) gene. Although this kinase had a previously demonstrated activity in preventing the endocytosis of the dopamine reuptake transporter (DAT), a causal role for TNK2-associated dysfunction in PD remains unresolved. We postulated the dopaminergic neurodegeneration resulting from patient-associated variants in TNK2 were a consequence of aberrant or prolonged TNK2 overactivity, the latter being a failure in TNK2 degradation by an E3 ubiquitin ligase, neuronal precursor cell-expressed developmentally down-regulated-4 (NEDD4). Interestingly, systemic RNA interference protein-3 (SID-3) is the sole TNK2 ortholog in the nematode Caenorhabditis elegans, where it is an established effector of epigenetic gene silencing mediated through the dsRNA-transporter, SID-1. We hypothesized that TNK2/SID-3 represents a node of integrated dopaminergic and epigenetic signaling essential to neuronal homeostasis. Use of a TNK2 inhibitor (AIM-100) or a NEDD4 activator [N-aryl benzimidazole 2 (NAB2)] in bioassays for either dopamine- or dsRNA-uptake into worm dopaminergic neurons revealed that sid-3 mutants displayed robust neuroprotection from 6-hydroxydopamine (6-OHDA) exposures, as did AIM-100 or NAB2-treated wild-type animals. Furthermore, NEDD4 activation by NAB2 in rat primary neurons correlated to a reduction in TNK2 levels and the attenuation of 6-OHDA neurotoxicity. CRISPR-edited nematodes engineered to endogenously express SID-3 variants analogous to TNK2 PD-associated SNPs exhibited enhanced susceptibility to dopaminergic neurodegeneration and circumvented the RNAi resistance characteristic of SID-3 dysfunction. This research exemplifies a molecular etiology for PD whereby dopaminergic and epigenetic signaling are coordinately regulated to confer susceptibility or resilience to neurodegeneration.
Assuntos
Doença de Parkinson , Animais , Ratos , Doença de Parkinson/genética , Doença de Parkinson/metabolismo , Dopamina/metabolismo , Oxidopamina , Neuroproteção/genética , Caenorhabditis elegans/genética , Caenorhabditis elegans/metabolismo , Neurônios Dopaminérgicos/metabolismo , Epigênese Genética , Modelos Animais de DoençasRESUMO
During the initial wave of the COVID-19 pandemic, symptoms of infection varied widely among adults younger than 60 years. This cross-sectional investigation of adults ages 18-59 years explored associations between SARS-CoV-2 symptomatology and supplementation of micronutrients involved in immune function, such as multivitamins, vitamin D, vitamin C, vitamin E and zinc. Between August and December 2020, an online survey was completed by 287 respondents, averaging 33â 3 ± 10â 5 years, who recovered from SARS-CoV-2 infection within the previous 4 months. In regression models, intake of supplements over the previous year was not protective against number of symptoms or symptom severity. Despite higher rates of supplementation over the previous year, smokers experienced more symptoms and greater symptom severity than non-smokers. Micronutrient supplementation did not protect young adults from experiencing symptoms of SARS-CoV-2, but our results suggest that smoking cessation may be a more effective modifiable lifestyle factor.
Assuntos
COVID-19 , SARS-CoV-2 , Adulto Jovem , Humanos , Adolescente , Adulto , Pessoa de Meia-Idade , Autorrelato , COVID-19/epidemiologia , Pandemias , Estudos Transversais , Suplementos Nutricionais , VitaminasRESUMO
The presence of circulating cancer cells in the bloodstream is positively correlated with metastasis. We hypothesize that fluid shear stress (FSS) occurring during circulation alters mitochondrial function, enhancing metastatic behaviors of cancer cells. MCF7 and MDA-MB-231 human breast cancer cells subjected to FSS exponentially increased proliferation. Notably, FSS-treated cells consumed more oxygen but were resistant to uncoupler-mediated ATP loss. We found that exposure to FSS downregulated the F1FO ATP synthase c-subunit and overexpression of the c-subunit arrested cancer cell migration. Approaches that regulate c-subunit abundance may reduce the likelihood of breast cancer metastasis.
Assuntos
Neoplasias da Mama , ATPases Mitocondriais Próton-Translocadoras , Humanos , Feminino , ATPases Mitocondriais Próton-Translocadoras/genética , ATPases Mitocondriais Próton-Translocadoras/metabolismo , Neoplasias da Mama/genética , Neoplasias da Mama/patologia , Regulação para Baixo , Trifosfato de Adenosina , Proliferação de Células , OxigênioRESUMO
Alpha-tocotrienol (α-TCT) is a member of the vitamin E family. It has been reported to protect the brain against various pathologies including cerebral ischemia and neurodegeneration. However, it is still unclear if α-TCT exhibits beneficial effects during brain development. We hypothesized that treatment with α-TCT improves intracellular redox homeostasis supporting normal development of neurons. We found that primary hippocampal neurons isolated from rat feti grown in α-TCT-containing media achieved greater levels of neurite complexity compared to ethanol-treated control neurons. Neurons were treated with 1 µM α-TCT for 3 weeks, and media were replaced with fresh α-TCT every week. Treatment with α-TCT increased α-TCT levels (26 pmol/mg protein) in the cells, whereas the control neurons did not contain α-TCT. α-TCT-treated neurons produced adenosine triphosphate (ATP) at a higher rate and increased ATP retention at neurites, supporting formation of neurite branches. Although treatment with α-TCT alone did not change neuronal viability, neurons grown in α-TCT were more resistant to death at maturity. We further found that messenger RNA and protein levels of B-cell lymphoma-extra large (Bcl-xL) are increased by α-TCT treatment without inducing posttranslational cleavage of Bcl-xL. Bcl-xL is known to enhance mitochondrial energy production, which improves neuronal function including neurite outgrowth and neurotransmission. Therefore α-TCT-mediated Bcl-xL upregulation may be the central mechanism of neuroprotection seen in the α-TCT-treated group. In summary, treatment with α-TCT upregulates Bcl-xL and increases ATP levels at neurites. This correlates with increased neurite branching during development and with protection of mature neurons against oxidative stress.
Assuntos
Linfoma de Células B , Neurônios , Trifosfato de Adenosina/metabolismo , Trifosfato de Adenosina/farmacologia , Animais , Hipocampo/metabolismo , Linfoma de Células B/metabolismo , Ratos , Tocotrienóis , Regulação para Cima , Proteína bcl-X/genética , Proteína bcl-X/metabolismoRESUMO
Mitochondrial ATP synthase is vital not only for cellular energy production but also for energy dissipation and cell death. ATP synthase c-ring was suggested to house the leak channel of mitochondrial permeability transition (mPT), which activates during excitotoxic ischemic insult. In this present study, we purified human c-ring from both eukaryotic and prokaryotic hosts to biophysically characterize its channel activity. We show that purified c-ring forms a large multi-conductance, voltage-gated ion channel that is inhibited by the addition of ATP synthase F1 subcomplex. In contrast, dissociation of F1 from FO occurs during excitotoxic neuronal death suggesting that the F1 constitutes the gate of the channel. mPT is known to dissipate the osmotic gradient across the inner membrane during cell death. We show that ATP synthase c-subunit knock down (KD) prevents the osmotic change in response to high calcium and eliminates large conductance, Ca2+ and CsA sensitive channel activity of mPT. These findings elucidate the gating mechanism of the ATP synthase c-subunit leak channel (ACLC) and suggest how ACLC opening is regulated by cell stress in a CypD-dependent manner.
Assuntos
Proteínas de Transporte da Membrana Mitocondrial , ATPases Mitocondriais Próton-Translocadoras , Trifosfato de Adenosina/metabolismo , Morte Celular , Humanos , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Poro de Transição de Permeabilidade Mitocondrial , ATPases Mitocondriais Próton-Translocadoras/genética , ATPases Mitocondriais Próton-Translocadoras/metabolismo , ATPases Translocadoras de Prótons/metabolismoRESUMO
Mitochondrial dysfunction is a key element in the progression of Parkinson's disease (PD). The inefficient operation of the electron transport chain (ETC) impairs energy production and enhances the generation of oxidative stress contributing to the loss of dopaminergic cells in the brain. ATPase inhibitory factor 1 (IF1) is a regulator of mitochondrial energy metabolism. IF1 binds directly to the F1Fo ATP synthase and prevents ATP wasting during compromised energy metabolism. In this study, we found treatment with IF1 protects mitochondria against PD-like insult in vitro. SH-SY5Y cells treated with IF1 were resistant to loss of ATP and mitochondrial inner membrane potential during challenge with rotenone, an inhibitor of complex I in the ETC. We further demonstrated that treatment with IF1 reversed rotenone-induced superoxide production in mitochondria and peroxide accumulation in whole cells. Ultimately, IF1 decreased protein levels of pro-apoptotic Bax, cleaved caspase-3, and cleaved PARP, rescuing SH-SY5Y cells from rotenone-mediated apoptotic death. Administration of IF1 significantly improved the results of pole and hanging tests performed by PD mice expressing human α-synuclein. This indicates that IF1 mitigates PD-associated motor deficit. Together, these findings suggest that IF1 exhibits a neuroprotective effect preventing mitochondrial dysfunction in PD pathology.
Assuntos
Fármacos Neuroprotetores , Doença de Parkinson , Adenosina Trifosfatases/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Camundongos , Mitocôndrias/metabolismo , Fármacos Neuroprotetores/metabolismo , Fármacos Neuroprotetores/farmacologia , Doença de Parkinson/metabolismo , Rotenona/metabolismo , Rotenona/farmacologiaRESUMO
B-cell lymphoma-extra large (Bcl-xL) is a mitochondrial protein known to inhibit mitochondria-dependent intrinsic apoptotic pathways. An increasing number of studies have demonstrated that Bcl-xL is critical in regulating neuronal energy metabolism and has a protective role in pathologies associated with an energy deficit. However, it is less known how Bcl-xL regulates physiological processes of the brain. In this study, we hypothesize that Bcl-xL is required for neurite branching and maturation during neuronal development by improving local energy metabolism. We found that the absence of Bcl-xL in rat primary hippocampal neurons resulted in mitochondrial dysfunction. Specifically, the ATP/ADP ratio was significantly decreased in the neurites of Bcl-xL depleted neurons. We further found that neurons transduced with Bcl-xL shRNA or neurons treated with ABT-263, a pharmacological inhibitor of Bcl-xL, showed impaired mitochondrial motility. Neurons lacking Bcl-xL had significantly decreased anterograde and retrograde movement of mitochondria and an increased stationary mitochondrial population when Bcl-xL was depleted by either means. These mitochondrial defects, including loss of ATP, impaired normal neurite development. Neurons lacking Bcl-xL showed significantly decreased neurite arborization, growth and complexity. Bcl-xL depleted neurons also showed impaired synapse formation. These neurons showed increased intracellular calcium concentration and were more susceptible to excitotoxic challenge. Bcl-xL may support positioning of mitochondria at metabolically demanding regions of neurites like branching points. Our findings suggest a role for Bcl-xL in physiological regulation of neuronal growth and development.
RESUMO
Bcl-xL is a pro-survival protein of the Bcl2 family found in the mitochondrial membrane. Bcl-xL supports growth, development, and maturation of neurons, and it also prevents neuronal death during neurotoxic stimulation. This article reviews the mechanisms and upstream signaling that regulate the activity and abundance of Bcl-xL. Our team and others have reported that oxidative stress is a key regulator of intracellular Bcl-xL balance in neurons. Oxidative stress regulates synthesis, degradation, and activity of Bcl-xL and therefore neuronal function. During apoptosis, pro-apoptotic Bcl2 proteins such as Bax and Bak translocate to and oligomerize in the mitochondrial membrane. Formation of oligomers causes release of cytochrome c and activation of caspases that lead to neuronal death. Bcl-xL binds directly to pro-apoptotic Bcl2 proteins to block apoptotic signaling. Although anti-apoptotic roles of Bcl-xL have been well documented, an increasing number of studies in recent decades show that protein binding partners of Bcl-xL are not limited to Bcl2 proteins. Bcl-xL forms a complex with F1Fo ATP synthase, DJ-1, DRP1, IP3R, and the ryanodine receptor. These proteins support physiological processes in neurons such as growth and development and prevent neuronal damage by regulating mitochondrial ATP production, synapse formation, synaptic vesicle recycling, neurotransmission, and calcium signaling. However, under conditions of oxidative stress, Bcl-xL undergoes proteolytic cleavage thus lowering the abundance of functional Bcl-xL in neurons. Additionally, oxidative stress alters formation of Bcl-xL-mediated multiprotein complexes by regulating post-translational phosphorylation. Finally, oxidative stress regulates transcription factors that target the Bcl-x gene and alter accessibility of microRNA to mRNA influencing mRNA levels of Bcl-xL. In this review, we discussed how Bcl-xL supports the normal physiology of neurons, and how oxidative stress contributes to pathology by manipulating the dynamics of Bcl-xL production, degradation, and activity.
RESUMO
Loss of the gene (Fmr1) encoding Fragile X mental retardation protein (FMRP) causes increased mRNA translation and aberrant synaptic development. We find neurons of the Fmr1-/y mouse have a mitochondrial inner membrane leak contributing to a "leak metabolism." In human Fragile X syndrome (FXS) fibroblasts and in Fmr1-/y mouse neurons, closure of the ATP synthase leak channel by mild depletion of its c-subunit or pharmacological inhibition normalizes stimulus-induced and constitutive mRNA translation rate, decreases lactate and key glycolytic and tricarboxylic acid (TCA) cycle enzyme levels, and triggers synapse maturation. FMRP regulates leak closure in wild-type (WT), but not FX synapses, by stimulus-dependent ATP synthase ß subunit translation; this increases the ratio of ATP synthase enzyme to its c-subunit, enhancing ATP production efficiency and synaptic growth. In contrast, in FXS, inability to close developmental c-subunit leak prevents stimulus-dependent synaptic maturation. Therefore, ATP synthase c-subunit leak closure encourages development and attenuates autistic behaviors.
Assuntos
Trifosfato de Adenosina/metabolismo , Síndrome do Cromossomo X Frágil/metabolismo , Subunidades Proteicas/metabolismo , Animais , Linhagem Celular , Ciclo do Ácido Cítrico/fisiologia , Fibroblastos/metabolismo , Proteína do X Frágil da Deficiência Intelectual/metabolismo , Células HEK293 , Humanos , Camundongos , Neurônios/metabolismo , RNA Mensageiro , Sinapses/metabolismoRESUMO
Apoptosis, programmed cell death type I, is a critical part of neurodegeneration in cerebral ischemia, Parkinson's, and Alzheimer's disease. Apoptosis begins with activation of pro-death proteins Bax and Bak, release of cytochrome c and activation of caspases, loss of membrane integrity of intracellular organelles, and ultimately cell death. Approaches that block apoptotic pathways may prevent or delay neurodegenerative processes. Carotenoids are a group of pigments found in fruits, vegetables, and seaweeds that possess antioxidant properties. Over the last several decades, an increasing number of studies have demonstrated a protective role of carotenoids in neurodegenerative disease. In this review, we describe functions of commonly consumed carotenoids including lycopene, ß-carotene, lutein, astaxanthin, and fucoxanthin and their roles in neurodegenerative disease models. We also discuss the underlying cellular mechanisms of carotenoid-mediated neuroprotection, including their antioxidant properties, role as signaling molecules, and as gene regulators that alleviate apoptosis-associated brain cell death.
Assuntos
Apoptose/efeitos dos fármacos , Carotenoides/farmacologia , Fármacos Neuroprotetores/farmacologia , Animais , Antioxidantes/química , Antioxidantes/farmacologia , Carotenoides/química , Humanos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Fármacos Neuroprotetores/química , Relação Estrutura-AtividadeRESUMO
Circulating tumor cells (CTCs) are cancer cells that detach from the primary site and travel in the blood stream. A higher number of CTCs increases the risk of breast cancer metastasis, and it is inversely associated with the survival rates of patients with breast cancer. Although the numbers of CTCs are generally low and the majority of CTCs die in circulation, the survival of a few CTCs can seed the development of a tumor at a secondary location. An increasing number of studies demonstrate that CTCs undergo modification in response to the dynamic biophysical environment in the blood due in part to fluid shear stress. Fluid shear stress generates reactive oxygen species (ROS), triggers redox-sensitive cell signaling, and alters the function of intracellular organelles. In particular, the mitochondrion is an important target organelle in determining the metastatic phenotype of CTCs. In healthy cells, mitochondria produce adenosine triphosphate (ATP) via oxidative phosphorylation in the electron transport chain, and during oxidative phosphorylation, they produce physiological levels of ROS. Mitochondria also govern death mechanisms such as apoptosis and mitochondrial permeability transition pore opening to, in order eliminate unwanted or damaged cells. However, in cancer cells, mitochondria are dysregulated, causing aberrant energy metabolism, redox homeostasis, and cell death pathways that may favor cancer invasiveness. In this review, we discuss the influence of fluid shear stress on CTCs with an emphasis on breast cancer pathology, then discuss alterations of cellular mechanisms that may increase the metastatic potentials of CTCs.
Assuntos
Neoplasias da Mama/patologia , Células Neoplásicas Circulantes/patologia , Trifosfato de Adenosina/metabolismo , Animais , Neoplasias da Mama/metabolismo , Feminino , Humanos , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Metástase Neoplásica/patologia , Células Neoplásicas Circulantes/metabolismo , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , Estresse MecânicoRESUMO
Parkinson's disease (PD) is a neurodegenerative disorder caused by the depletion of dopaminergic neurons in the basal ganglia, the movement center of the brain. Approximately 60,000 people are diagnosed with PD in the United States each year. Although the direct cause of PD can vary, accumulation of oxidative stress-induced neuronal damage due to increased production of reactive oxygen species (ROS) or impaired intracellular antioxidant defenses invariably occurs at the cellular levels. Pharmaceuticals such as dopaminergic prodrugs and agonists can alleviate some of the symptoms of PD. Currently, however, there is no treatment to halt the progression of PD pathology. Due to the nature of PD, a long and progressive neurodegenerative process, strategies to prevent or delay PD pathology may be well suited to lifestyle changes like dietary modification with antioxidant-rich foods to improve intracellular redox homeostasis. In this review, we discuss cellular and genetic factors that increase oxidative stress in PD. We also discuss neuroprotective roles of dietary antioxidants including vitamin C, vitamin E, carotenoids, selenium, and polyphenols along with their potential mechanisms to alleviate PD pathology.
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Familial Parkinson's disease (PD) protein DJ-1 mutations are linked to early onset PD. We have found that DJ-1 binds directly to the F1FO ATP synthase ß subunit. DJ-1's interaction with the ß subunit decreased mitochondrial uncoupling and enhanced ATP production efficiency while in contrast mutations in DJ-1 or DJ-1 knockout increased mitochondrial uncoupling, and depolarized neuronal mitochondria. In mesencephalic DJ-1 KO cultures, there was a progressive loss of neuronal process extension. This was ameliorated by a pharmacological reagent, dexpramipexole, that binds to ATP synthase, closing a mitochondrial inner membrane leak and enhancing ATP synthase efficiency. ATP synthase c-subunit can form an uncoupling channel; we measured, therefore, ATP synthase F1 (ß subunit) and c-subunit protein levels. We found that ATP synthase ß subunit protein level in the DJ-1 KO neurons was approximately half that found in their wild-type counterparts, comprising a severe defect in ATP synthase stoichiometry and unmasking c-subunit. We suggest that DJ-1 enhances dopaminergic cell metabolism and growth by its regulation of ATP synthase protein components.
Assuntos
Neurônios Dopaminérgicos/metabolismo , Mitocôndrias/metabolismo , ATPases Mitocondriais Próton-Translocadoras/metabolismo , Proteína Desglicase DJ-1/metabolismo , Animais , Expressão Gênica , Humanos , Potencial da Membrana Mitocondrial/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mitocôndrias/genética , Membranas Mitocondriais/metabolismo , ATPases Mitocondriais Próton-Translocadoras/genética , Ligação Proteica , Proteína Desglicase DJ-1/genética , Ratos Sprague-DawleyRESUMO
B-cell lymphoma-extra large (Bcl-xL) is an anti-apoptotic member of the Bcl2 family of proteins, which supports neurite outgrowth and neurotransmission by improving mitochondrial function. During excitotoxic stimulation, however, Bcl-xL undergoes post-translational cleavage to ∆N-Bcl-xL, and accumulation of ∆N-Bcl-xL causes mitochondrial dysfunction and neuronal death. In this study, we hypothesized that the generation of reactive oxygen species (ROS) during excitotoxicity leads to formation of ∆N-Bcl-xL. We further proposed that the application of an antioxidant with neuroprotective properties such as α-tocotrienol (TCT) will prevent ∆N-Bcl-xL-induced mitochondrial dysfunction via its antioxidant properties. Primary hippocampal neurons were treated with α-TCT, glutamate, or a combination of both. Glutamate challenge significantly increased cytosolic and mitochondrial ROS and ∆N-Bcl-xL levels. ∆N-Bcl-xL accumulation was accompanied by intracellular ATP depletion, loss of mitochondrial membrane potential, and cell death. α-TCT prevented loss of mitochondrial membrane potential in hippocampal neurons overexpressing ∆N-Bcl-xL, suggesting that ∆N-Bcl-xL caused the loss of mitochondrial function under excitotoxic conditions. Our data suggest that production of ROS is an important cause of ∆N-Bcl-xL formation and that preventing ROS production may be an effective strategy to prevent ∆N-Bcl-xL-mediated mitochondrial dysfunction and thus promote neuronal survival.
Assuntos
Antioxidantes/farmacologia , Neurônios/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Processamento de Proteína Pós-Traducional , Proteólise , Tocotrienóis/farmacologia , Trifosfato de Adenosina/metabolismo , Animais , Células Cultivadas , Hipocampo/citologia , Potencial da Membrana Mitocondrial , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Neurônios/metabolismo , Neurônios/fisiologia , Estresse Oxidativo , Ratos , Ratos Sprague-Dawley , Espécies Reativas de Oxigênio/metabolismo , Proteína bcl-X/metabolismoRESUMO
B-cell lymphoma-extra large (Bcl-xL) is an anti-apoptotic Bcl-2 protein found in the mitochondrial membrane. Bcl-xL is reported to support normal brain development and protects neurons against toxic stimulation during pathological process via its roles in regulation of mitochondrial functions. Despite promising evidence showing neuroprotective properties of Bcl-xL, commonly applied molecular approaches such as genetic manipulation may not be readily applicable for human subjects. Therefore, findings at the bench may be slow to be translated into treatments for disease. Currently, there is no FDA approved application that specifically targets Bcl-xL and treats brain-associated pathology in humans. In this review, we will discuss naturally occurring nutrients that may exhibit regulatory effects on Bcl-xL expression or activity, thus potentially providing affordable, readily-applicable, easy, and safe strategies to protect the brain.