RESUMO
Mitochondria are the only organelles, along with the nucleus, that have their own DNA. Mitochondrial DNA (mtDNA) is a double-stranded circular molecule of ~16.5 kbp that can exist in multiple copies within the organelle. Both strands are translated and encode for 22 tRNAs, 2 rRNAs, and 13 proteins. mtDNA molecules are anchored to the inner mitochondrial membrane and, in association with proteins, form a structure called nucleoid, which exerts a structural and protective function. Indeed, mitochondria have evolved mechanisms necessary to protect their DNA from chemical and physical lesions such as DNA repair pathways similar to those present in the nucleus. However, there are mitochondria-specific mechanisms such as rapid mtDNA turnover, fission, fusion, and mitophagy. Nevertheless, mtDNA mutations may be abundant in somatic tissue due mainly to the proximity of the mtDNA to the oxidative phosphorylation (OXPHOS) system and, consequently, to the reactive oxygen species (ROS) formed during ATP production. In this review, we summarise the most common types of mtDNA lesions and mitochondria repair mechanisms. The second part of the review focuses on the physiological role of mtDNA damage in ageing and the effect of mtDNA mutations in neurodegenerative disorders such as Alzheimer's and Parkinson's disease. Considering the central role of mitochondria in maintaining cellular homeostasis, the analysis of mitochondrial function is a central point for developing personalised medicine.
Assuntos
Doenças Mitocondriais , Doenças Neurodegenerativas , Trifosfato de Adenosina , Dano ao DNA/genética , Reparo do DNA/genética , DNA Mitocondrial/genética , DNA Mitocondrial/metabolismo , Humanos , Doenças Mitocondriais/metabolismo , Doenças Neurodegenerativas/genética , Espécies Reativas de Oxigênio/metabolismoRESUMO
PURPOSE: Oxidative stress is a hallmark of Alzheimer's Disease (AD) and promotes tau phosphorylation. Since Thioredoxin Interacting protein (TXNIP), the inhibitor of the anti-oxidant system of Thioredoxin, is up regulated in the hippocampus of AD patients, we investigated whether TXNIP plays a role in promoting tau phosphorylation and whether Verapamil, an inhibitor of TXNIP expression, prevents TXNIP downstream effects. METHODS: We analyzed TXNIP expression and tau phosphorylation in the hippocampus of the 5xFAD mice in the absence and presence of a pharmacological treatment with Verapamil. Using SH-SY5Y cells, we verified the causative role of TXNIP in promoting tau phosphorylation at Ser202/Thr205, by inducing TXNIP silencing. RESULTS: The amyloid beta peptide (Aß1-42) leads to TXNIP over-expression in SH-SY5Y cells, which in turns induces oxidative stress and the activation of p38 MAPK, promoting tau phosphorylation at Ser202/Thr205. Silencing of TXNIP abolishes Aß1-42-induced tau phosphorylation, p38 MAPK phosphorylation and subsequent tau phosphorylation. Verapamil prevents TXNIP expression as well as p38 MAPK and tau phosphorylation at Ser202/Thr205 in the hippocampus of the 5xFAD mice. CONCLUSIONS: Our study unveil a novel pathway involved in AD progression that is inhibited by Verapamil, shedding new light on the understanding of the therapeutic potential of Verapamil in AD.
Assuntos
Doença de Alzheimer/tratamento farmacológico , Proteínas de Transporte/antagonistas & inibidores , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Verapamil/farmacologia , Proteínas tau/metabolismo , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/genética , Animais , Proteínas de Transporte/metabolismo , Linhagem Celular Tumoral , Modelos Animais de Doenças , Progressão da Doença , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Hipocampo/patologia , Humanos , Camundongos , Camundongos Transgênicos , Mutação , Estresse Oxidativo/efeitos dos fármacos , Fragmentos de Peptídeos/metabolismo , Fosforilação/efeitos dos fármacos , Presenilina-1/genética , Espécies Reativas de Oxigênio/metabolismo , Serina/metabolismo , Tiorredoxinas/metabolismo , Treonina/metabolismo , Verapamil/uso terapêuticoRESUMO
Recent advances highlight that inflammation is critical to Alzheimer Disease (AD) pathogenesis. Indeed, several diseases characterized by inflammation are considered risk factors for AD, such as type 2 diabetes, obesity, hypertension, and traumatic brain injury. Moreover, allelic variations in genes involved in the inflammatory cascade are risk factors for AD. AD is also characterized by mitochondrial dysfunction, which affects the energy homeostasis of the brain. The role of mitochondrial dysfunction has been characterized mostly in neuronal cells. However, recent data are demonstrating that mitochondrial dysfunction occurs also in inflammatory cells, promoting inflammation and the secretion of pro-inflammatory cytokines, which in turn induce neurodegeneration. In this review, we summarize the recent finding supporting the hypothesis of the inflammatory-amyloid cascade in AD. Moreover, we describe the recent data that demonstrate the link between altered mitochondrial dysfunction and the inflammatory cascade. We focus in summarizing the role of Drp1, which is involved in mitochondrial fission, showing that altered Drp1 activation affects the mitochondrial homeostasis and leads to the activation of the NLRP3 inflammasome, promoting the inflammatory cascade, which in turn aggravates Amyloid beta (Ab) deposition and tau-induced neurodegeneration, showing the relevance of this pro-inflammatory pathway as an early event in AD.
RESUMO
The mitogen-activated protein kinases (MAPKs) superfamily comprises three major signaling pathways: the extracellular signal-regulated protein kinases (ERKs), the c-Jun N-terminal kinases or stress-activated protein kinases (JNKs/SAPKs) and the p38 family of kinases. ERK 1/2 signaling has been implicated in a number of neurodegenerative disorders, including Huntington's disease (HD). Phosphorylation patterns of ERK 1/2 and JNK are altered in cell models of HD. In this study, we aimed at studying the correlations between ERK 1/2 and the neuronal vulnerability to HD degeneration in the R6/2 transgenic mouse model of HD. Single and double-label immunofluorescence for phospho-ERK (pERK, the activated form of ERK) and for each of the striatal neuronal markers were employed on perfusion-fixed brain sections from R6/2 and wild-type mice. Moreover, Phosphodiesterase 4 inhibition through rolipram was used to study the effects on pERK expression in the different types of striatal neurons. We completed our study with western blot analysis. Our study shows that pERK levels increase with age in the medium spiny striatal neurons and in the parvalbumin interneurons, and that rolipram counteracts such increase in pERK. Conversely, cholinergic and somatostatinergic interneurons of the striatum contain higher levels of pERK in the R6/2 mice compared to the controls. Rolipram induces an increase in pERK expression in these interneurons. Thus, our study confirms and extends the concept that the expression of phosphorylated ERK 1/2 is related to neuronal vulnerability and is implicated in the pathophysiology of cell death in HD.
Assuntos
Doença de Huntington/tratamento farmacológico , Doença de Huntington/enzimologia , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Inibidores da Fosfodiesterase 4/farmacologia , Rolipram/farmacologia , Animais , Modelos Animais de Doenças , Doença de Huntington/patologia , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Sistema de Sinalização das MAP Quinases/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos CBA , Camundongos TransgênicosRESUMO
During peripheral nerve injury, Schwann cells (SCs) adopt a migratory phenotype and remodel the extracellular matrix and provide a supportive activity for neuron regeneration. SCs synthesize neurotrophic factors and cytokines that are crucial for the repair of the injured nerve. The receptor for advanced glycation end products (RAGE) and its ligand S100B, which are secreted by SCs, are required for the repair of the injured peripheral nerve in vivo. However, the precise intracellular pathways involved have not been completely elucidated. Here, we show that RAGE-induced S100B secretion involves the recruitment of S100B in lipid rafts and caveolae. Moreover, we demonstrate for the first time that RAGE induces the expression of thioredoxin interacting protein (TXNIP) in SCs and the injured sciatic nerve in vivo. TXNIP is involved in the activation of p38 MAPK, CREB and NFκB in SCs. TXNIP silencing partially inhibits RAGE-induced SC migration and completely abolishes RAGE-induced fibronectin and IL-1ß expression. Our results support a model in which TXNIP mediates in part RAGE-induced SC migration and is required for the expression of provisional ECM and pro-inflammatory IL-1ß. We provide new insight on the role of the SC RAGE-TXNIP axis in the repair of injured peripheral nerves.
Assuntos
Proteínas de Transporte/metabolismo , Movimento Celular , Fibronectinas/metabolismo , Interleucina-1beta/metabolismo , Fatores de Crescimento Neural/metabolismo , Receptores Imunológicos/metabolismo , Proteínas S100/metabolismo , Células de Schwann/citologia , Animais , Proteínas de Ciclo Celular , Ativação Enzimática , Masculino , Microdomínios da Membrana/metabolismo , Ratos , Ratos Sprague-Dawley , Receptor para Produtos Finais de Glicação Avançada , Subunidade beta da Proteína Ligante de Cálcio S100 , Células de Schwann/enzimologia , Nervo Isquiático/metabolismo , Nervo Isquiático/patologia , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
The notochord is a defining feature of the chordate body plan. Experiments in ascidian, frog and mouse embryos have shown that co-expression of Brachyury and FoxA class transcription factors is required for notochord development. However, studies on the cis-regulatory sequences mediating the synergistic effects of these transcription factors are complicated by the limited knowledge of notochord genes and cis-regulatory modules (CRMs) that are directly targeted by both. We have identified an easily testable model for such investigations in a 155-bp notochord-specific CRM from the ascidian Ciona intestinalis. This CRM contains functional binding sites for both Ciona Brachyury (Ci-Bra) and FoxA (Ci-FoxA-a). By combining point mutation analysis and misexpression experiments, we demonstrate that binding of both transcription factors to this CRM is necessary and sufficient to activate transcription. To gain insights into the cis-regulatory criteria controlling its activity, we investigated the organization of the transcription factor binding sites within the 155-bp CRM. The 155-bp sequence contains two Ci-Bra binding sites with identical core sequences but opposite orientations, only one of which is required for enhancer activity. Changes in both orientation and spacing of these sites substantially affect the activity of the CRM, as clusters of identical sites found in the Ciona genome with different arrangements are unable to activate transcription in notochord cells. This work presents the first evidence of a synergistic interaction between Brachyury and FoxA in the activation of an individual notochord CRM, and highlights the importance of transcription factor binding site arrangement for its function.
Assuntos
Ciona intestinalis/embriologia , Proteínas Fetais/metabolismo , Notocorda/metabolismo , Proteínas com Domínio T/metabolismo , Transativadores/metabolismo , Animais , Elementos Facilitadores GenéticosRESUMO
Alzheimer disease (AD) is the most frequent cause of dementia and up to now there is not an effective therapy to cure AD. In addition, AD onset occurs decades before the diagnosis, affecting the possibility to set up appropriate therapeutic strategies. For this reason, it is necessary to investigate the effects of risk factors, such as cardiovascular diseases, in promoting AD. AD shows not only brain dysfunction, but also alterations in peripheral tissues/organs. Indeed, it exists a reciprocal connection between brain and heart, where cardiovascular alterations participate to AD as well as AD seem to promote cardiovascular dysfunction. In addition, metabolic dysfunction promotes both cardiovascular diseases and AD. In this review, we summarize the pathways involved in the regulation of the brain-heart axis and the effect of metabolism on these pathways. We also present the studies showing the role of the gut microbiota on the brain-heart axis. Herein, we propose recent evidences of the function of Thioredoxin Interacting protein (TXNIP) in mediating the role of metabolism on the brain-heart axis. TXNIP is a key regulator of metabolism at both cellular and body level and it exerts also a pathological function in several cardiovascular diseases as well as in AD.
Assuntos
Doença de Alzheimer , Encéfalo , Proteínas de Transporte , TiorredoxinasRESUMO
Growth factors and other regulatory molecules are required to direct differentiation of bone marrow-derived human mesenchymal stem cells (hMSC) along specific lineages. However, the therapeutic use of growth factors is limited by their susceptibility to degradation, and the need to maintain prolonged local release of growth factor at levels sufficient to stimulate hMSC. The aim of this study was to investigate whether a device containing heparan sulfate (HS), which is a co-factor in growth factor-mediated cell proliferation and differentiation, could potentiate and prolong the delivery of fibroblast growth factor-2 (FGF-2) and thus enhance hMSC stimulation. To this aim, we synthesized cationic polyelectrolyte polymers covalently and non-covalently anchored to HS and evaluated their effect on hMSC proliferation. Polymers non-covalently bound to HS resulted in the release of an HS/FGF-2 complex rather than FGF-2 alone. The release of this complex significantly restored hMSC proliferation, which was abolished in serum-free medium and only partially restored by the release of FGF-2 alone as occurred with polymer covalently bound to HS. We also demonstrate that exposure to HS/FGF-2 during early growth but not during post-confluence is essential for hMSC differentiation down the fibroblast lineage, which suggests that both factors are required to establish the correct stem cell commitment that is necessary to support subsequent differentiation. In conclusion, the delivery platform described here is a step towards the development of a new class of biomaterial that enables the prolonged, non-covalent binding and controlled delivery of growth factors and cofactors without altering their potency.
Assuntos
Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Eletrólitos/química , Fator 2 de Crescimento de Fibroblastos/administração & dosagem , Heparitina Sulfato/administração & dosagem , Sequência de Bases , Cátions , Linhagem da Célula , Células Cultivadas , Primers do DNA , Fator 2 de Crescimento de Fibroblastos/farmacocinética , Fator 2 de Crescimento de Fibroblastos/farmacologia , Heparitina Sulfato/farmacocinética , Heparitina Sulfato/farmacologia , Humanos , Células-Tronco Mesenquimais , Polímeros , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Amyloid-beta peptides (Abeta) and the protein human serum albumin (HSA) interact in vivo. They are both localised in the blood plasma and in the cerebrospinal fluid. Among other functions, HSA is involved in the transport of the essential metal copper. Complexes between Abeta and copper ions have been proposed to be an aberrant interaction implicated in the development of Alzheimer's disease, where Cu is involved in Abeta aggregation and production of reactive oxygen species (ROS). In the present work, we studied copper-exchange reaction between Abeta and HSA or the tetrapeptide DAHK (N-terminal Cu-binding domain of HSA) and the consequence of this exchange on Abeta-induced ROS production and cell toxicity. The following results were obtained: 1) HSA and DAHK removed Cu(II) from Abeta rapidly and stoichiometrically, 2) HSA and DAHK were able to decrease Cu-induced aggregation of Abeta, 3) HSA and DAHK suppressed the catalytic HO(.) production in vitro and ROS production in neuroblastoma cells generated by Cu-Abeta and ascorbate, 4) HSA and DAHK were able to rescue these cells from the toxicity of Cu-Abeta with ascorbate, 5) DAHK was more potent in ROS suppression and restoration of neuroblastoma cell viability than HSA, in correlation with an easier reduction of Cu(II)-HSA than Cu-DAHK by ascorbate, in vitro. Our data suggest that HSA is able to decrease aberrant Cu(II)-Abeta interaction. The repercussion of the competition between HSA and Abeta to bind Cu in the blood and brain and its relation to Alzheimer's disease are discussed.
Assuntos
Peptídeos beta-Amiloides/metabolismo , Cobre/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Albumina Sérica/metabolismo , Sequência de Aminoácidos , Peptídeos beta-Amiloides/toxicidade , Apoptose , Ácido Ascórbico/metabolismo , Linhagem Celular Tumoral , Espectroscopia de Ressonância de Spin Eletrônica , Humanos , Microscopia Eletrônica de Transmissão , Nefelometria e Turbidimetria , Peptídeos/metabolismoRESUMO
Efficacious therapies are not available for the cure of both gliomas and glioneuronal tumors, which represent the most numerous and heterogeneous primary cancers of the central nervous system (CNS), and for neoplasms of the peripheral nervous system (PNS), which can be divided into benign tumors, mainly represented by schwannomas and neurofibromas, and malignant tumors of the peripheral nerve sheath (MPNST). Increased cellular oxidative stress and other metabolic aspects have been reported as potential etiologies in the nervous system tumors. Thus polyphenols have been tested as effective natural compounds likely useful for the prevention and therapy of this group of neoplasms, because of their antioxidant and anti-inflammatory activity. However, polyphenols show poor intestinal absorption due to individual intestinal microbiota content, poor bioavailability, and difficulty in passing the blood-brain barrier (BBB). Recently, polymeric nanoparticle-based polyphenol delivery improved their gastrointestinal absorption, their bioavailability, and entry into defined target organs. Herein, we summarize recent findings about the primary polyphenols employed for nervous system tumor prevention and treatment. We describe the limitations of their application in clinical practice and the new strategies aimed at enhancing their bioavailability and targeted delivery.
RESUMO
Vitamin D is a fat-soluble steroid hormone playing a pivotal role in calcium and phosphate homeostasis as well as in bone health. Vitamin D levels are not exclusively dependent on food intake. Indeed, the endogenous production-occurring in the skin and dependent on sun exposure-contributes to the majority amount of vitamin D present in the body. Since vitamin D receptors (VDRs) are ubiquitous and drive the expression of hundreds of genes, the interest in vitamin D has tremendously grown and its role in different diseases has been extensively studied. Several investigations indicated that vitamin D action extends far beyond bone health and calcium metabolism, showing broad effects on a variety of critical illnesses, including cancer, infections, cardiovascular and autoimmune diseases. Epidemiological studies indicated that low circulating vitamin D levels inversely correlate with cutaneous manifestations and bone abnormalities, clinical hallmarks of neurofibromatosis type 1 (NF1). NF1 is an autosomal dominant tumour predisposition syndrome causing significant pain and morbidity, for which limited treatment options are available. In this context, vitamin D or its analogues have been used to treat both skin and bone lesions in NF1 patients, alone or combined with other therapeutic agents. Here we provide an overview of vitamin D, its characteristic nutritional properties relevant for health benefits and its role in NF1 disorder. We focus on preclinical and clinical studies that demonstrated the clinical correlation between vitamin D status and NF1 disease, thus providing important insights into disease pathogenesis and new opportunities for targeted therapy.
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Chronic hyperglycemia and activation of receptor for advanced glycation end products (RAGE) are known risk factors for microvascular disease development in diabetic retinopathy. Thioredoxin-interacting protein (TXNIP), an endogenous inhibitor of antioxidant thioredoxin (TRX), plays a causative role in diabetes and its vascular complications. Herein we investigate whether HG and RAGE induce inflammation in rat retinal endothelial cells (EC) under diabetic conditions in culture through TXNIP activation and whether epigenetic mechanisms play a role in inflammatory gene expression. We show that RAGE activation by its ligand S100B or HG treatment of retinal EC induces the expression of TXNIP and inflammatory genes such as Cox2, VEGF-A, and ICAM1. TXNIP silencing by siRNA impedes RAGE and HG effects while stable over-expression of a cDNA for human TXNIP in EC elevates inflammation. p38 MAPK-NF-kappaB signaling pathway and histone H3 lysine (K) nine modifications are involved in TXNIP-induced inflammation. Chromatin immunoprecipitation (ChIP) assays reveal that TXNIP over-expression in EC abolishes H3K9 tri-methylation, a marker for gene inactivation, and increases H3K9 acetylation, an indicator of gene induction, at proximal Cox2 promoter bearing the NF-kappaB-binding site. These findings have important implications toward understanding the molecular mechanisms of ocular inflammation and endothelial dysfunction in diabetic retinopathy.
Assuntos
Proteínas de Transporte/metabolismo , Cromatina/metabolismo , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/patologia , Células Endoteliais/metabolismo , Inflamação/metabolismo , Retina/citologia , Animais , Bovinos , Proteínas de Ciclo Celular , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Ciclo-Oxigenase 2/genética , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/enzimologia , Células Endoteliais/patologia , Ativação Enzimática/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Glucose/farmacologia , Histonas/metabolismo , Inflamação/enzimologia , Inflamação/patologia , Mediadores da Inflamação/metabolismo , Molécula 1 de Adesão Intercelular/metabolismo , NF-kappa B/metabolismo , Regiões Promotoras Genéticas/genética , Ligação Proteica/efeitos dos fármacos , Processamento de Proteína Pós-Traducional/efeitos dos fármacos , Transporte Proteico/efeitos dos fármacos , Ratos , Receptor para Produtos Finais de Glicação Avançada , Receptores Imunológicos/metabolismo , Fator A de Crescimento do Endotélio Vascular/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
Autophagy is the major intracellular machinery for degrading proteins, lipids, polysaccharides, and organelles. This cellular process is essential for the maintenance of the correct cellular balance in both physiological and stress conditions. Because of its role in maintaining cellular homeostasis, dysregulation of autophagy leads to various disease manifestations, such as inflammation, metabolic alterations, aging, and neurodegeneration. A common feature of many neurologic and neuromuscular diseases is the alteration of the autophagy-lysosomal pathways. For this reason, autophagy is considered a target for the prevention and/or cure of these diseases. Dietary intake of polyphenols has been demonstrated to prevent/ameliorate several of these diseases. Thus, natural products that can modulate the autophagy machinery are considered a promising therapeutic strategy. In particular, curcumin, a phenolic compound widely used as a dietary supplement, exerts an important effect in modulating autophagy. Herein, we report on the current knowledge concerning the role of curcumin in modulating the autophagy machinery in various neurological and neuromuscular diseases as well as its role in restoring the autophagy molecular mechanism in several cell types that have different effects on the progression of neurological and neuromuscular disorders.
Assuntos
Autofagia/efeitos dos fármacos , Curcumina/uso terapêutico , Suplementos Nutricionais , Músculo Esquelético/efeitos dos fármacos , Doenças do Sistema Nervoso/tratamento farmacológico , Sistema Nervoso/efeitos dos fármacos , Doenças Neuromusculares/tratamento farmacológico , Animais , Proteínas Relacionadas à Autofagia/metabolismo , Curcumina/efeitos adversos , Suplementos Nutricionais/efeitos adversos , Humanos , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Sistema Nervoso/metabolismo , Sistema Nervoso/patologia , Doenças do Sistema Nervoso/metabolismo , Doenças do Sistema Nervoso/patologia , Doenças Neuromusculares/metabolismo , Doenças Neuromusculares/patologia , Transdução de SinaisRESUMO
RAGE is a multiligand receptor of the immunoglobulin superfamily involved in regeneration of injured peripheral nerve and cell motility. RAGE is implicated in the development of various chronic diseases, such as neurodegenerative disorders, inflammatory responses, and diabetic complications. The correlation between RAGE endocytic trafficking and RAGE function is still uninvestigated. S100B is one of the ligands of RAGE. The molecular mechanisms responsible of S100B translocation in exocytic vesicles are still poorly investigated. In the present study we elucidate the role of RAGE endocytic trafficking in promoting S100B secretion in Schwann cells. Here we show that RAGE-induced secretion of S100B requires phosphorylated caveolin1-dependent endocytosis of RAGE. Endocytosis of RAGE in response to ligand binding promotes the fusion of endosomes with S100B-positive secretory vesicles. Src promotes the fusion of endosomes with S100B-secretory vesicles. Inhibition of src induces RAGE degradation. RAGE-mediated src activation induces cav1 phosphorylation and relocalization in the perinuclear compartment. RAGE signaling and recycling are required for S100-induced Schwann cells morphological changes and are inhibited by high-glucose, suggesting a possible link between diabetes and peripheral nerve injury. Indeed, high glucose inhibits RAGE-mediated src activation. Src inhibition blocks RAGE recycling, S100B secretion, and morphological changes. In summary, we identified a novel pathway of vesicular trafficking required for the amplification of RAGE signaling and cytoskeleton dynamics that is potentially involved in the regeneration of injured peripheral nerve.
Assuntos
Membrana Celular/metabolismo , Fatores de Crescimento Neural/metabolismo , Receptores Imunológicos/metabolismo , Proteínas S100/metabolismo , Células de Schwann/metabolismo , Vesículas Secretórias/metabolismo , Animais , Western Blotting , Caveolina 1/metabolismo , Células Cultivadas , Endocitose/fisiologia , Ativação Enzimática/efeitos dos fármacos , Imunofluorescência , Glucose/farmacologia , Imunoprecipitação , Regeneração Nervosa/fisiologia , Transporte Proteico/fisiologia , Ratos , Ratos Sprague-Dawley , Receptor para Produtos Finais de Glicação Avançada , Subunidade beta da Proteína Ligante de Cálcio S100 , Transdução de Sinais/fisiologia , Quinases da Família src/metabolismoRESUMO
The aim of the present study is to investigate changes of interferon (IFN) production occurring over the first 48 h after infection of peripheral blood mononuclear cells (PBMCs) with severe acute respiratory syndrome (SARS) coronavirus (CoV) and to compare these changes to those induced by well-established IFN-inducing viruses, such as vesicular stomatitis (VSV) and Newcastle viruses (NDV). Experiments have been carried out using PBMCs of 10 different healthy donors. The results showed that the antiviral activity of IFN contained in the supernatant of SARS-CoV-infected PBMCs was lower than those induced by VSV and NDV. Consequently, SARS-CoV induces a lower synthesis of IFN-alpha, -beta and -gamma compared to VSV and NDV. Characterization of the profile of IFN-alpha subtypes genes expression in SARS-CoV-infected PBMCs demonstrated that the level of IFN-alpha2 and -6 subtypes were higher compared to other IFN-alpha subtypes namely, IFN-alpha5, -8, -10, -13/1, -17, and -21. In conclusion, SARS-CoV induces IFNs to a less extent compared to VSV and NDV, thus suggesting that the IFN system does play a limited role in early host defense against SARS-CoV infection.
Assuntos
Interferons/imunologia , Leucócitos Mononucleares/imunologia , Leucócitos Mononucleares/virologia , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/imunologia , Células Cultivadas , Perfilação da Expressão Gênica , Humanos , Interferons/biossíntese , Vírus da Doença de Newcastle/imunologia , Vesiculovirus/imunologiaRESUMO
The receptor for advanced glycation end products (RAGE) may promote diabetic vascular and renal disease through the activation of intracellular signaling pathways that promote oxidative stress. Oxidative stress is a mediator of hyperglycemia-induced cell injury and a unifying theme for all mechanisms of diabetic complications, but there are few studies on the expression and potential contribution of RAGE in diabetic neuropathy. The current study demonstrates that dorsal root ganglia neurons express functional RAGE and respond to the RAGE ligand S100 with similar downstream signaling, oxidative stress, and cellular injury as other diabetic complication-prone tissues. RAGE-induced phosphatidylinositol-3 kinase activity is associated with formation of reactive oxygen species, caspase-3 activation, and nuclear DNA degradation. These events are prevented by treatment with the antioxidant alpha-lipoic acid. Our data indicate that therapies aimed at decreasing RAGE ligands, blocking RAGE signaling, or preventing oxidative stress could significantly decrease the development of neuropathy in diabetic patients.
Assuntos
Neurônios Aferentes/metabolismo , Neurônios Aferentes/patologia , Estresse Oxidativo , Receptores Imunológicos/metabolismo , Animais , Sobrevivência Celular , Células Cultivadas , Relação Dose-Resposta a Droga , Gânglios Espinais/metabolismo , Gânglios Espinais/patologia , Glucose/administração & dosagem , Glucose/farmacologia , Produtos Finais de Glicação Avançada/metabolismo , Membranas Intracelulares/metabolismo , Ligantes , NADPH Oxidases/metabolismo , Neurônios Aferentes/efeitos dos fármacos , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos , Ratos Sprague-Dawley , Espécies Reativas de Oxigênio/metabolismo , Receptor para Produtos Finais de Glicação Avançada , Proteínas S100/farmacologia , Transdução de SinaisRESUMO
Apurinic apyrimidinic endonuclease redox effector factor-1 (APE1/Ref-1) is involved both in the base excision repair (BER) of DNA lesions and in the eukaryotic transcriptional regulation. APE1/Ref-1 is regulated at both the transcriptional and post-translational levels, through control of subcellular localization and post-translational modification. In response to stress conditions, several cell types release ATP, which exerts stimulatory effects on eukaryotic cells via the purinergic receptors (P2) family. By using western blot and immunofluorescence analysis on a human tumour thyroid cell line (ARO), we demonstrate that purinergic stimulation by extracellular ATP induces quick cytoplasm to nucleus translocation of the protein at early times and its neosynthesis at later times. Continuous purinergic triggering by extracellular ATP released by ARO cells is responsible for the control of APE1/Ref-1 intracellular level. Interference with intracellular pathways activated by P2 triggering demonstrates that Ca2+ mobilization and intracellular reactive oxygen species (ROS) production are responsible for APE1/Ref-1 translocation. The APE1/Ref-1 activities on activator protein-1 (AP-1) DNA binding and DNA repair perfectly match its nuclear enrichment upon ATP stimulation. The biological relevance of our data is reinforced by the observation that APE1/Ref-1 stimulation by ATP protects ARO cells by H2O2-induced cell death. Our data provide new insights into the complex mechanisms regulating APE1/Ref-1 functions.
Assuntos
Trifosfato de Adenosina/farmacologia , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Receptores Purinérgicos/metabolismo , Transporte Ativo do Núcleo Celular , Animais , Cálcio/metabolismo , Morte Celular , Linhagem Celular Tumoral , Núcleo Celular/enzimologia , Humanos , Peróxido de Hidrogênio/toxicidade , NADPH Oxidases/metabolismo , Proteína Quinase C/fisiologiaRESUMO
The topology and trafficking of receptors play a key role in their signalling capability. Indeed, receptor function is related to the microenvironment inside the cell, where specific signalling molecules are compartmentalized. The response to NGF (nerve growth factor) is strongly dependent on the trafficking of its receptor, TrkA. However, information is still scarce about the role of the cellular localization of the TrkA co-receptor, p75NTR (where NTR is neurotrophin receptor), following stimulation by NGF. It has been shown that these two receptors play a key role in epithelial tissue and in epithelial-derived tumours, where the microenvironment at the plasma membrane is defined by the presence of tight junctions. Indeed, in thyroid carcinomas, rearrangements of TrkA are frequently found, which produce TrkA mutants that are localized exclusively in the cytoplasm. We used a thyroid cellular model in which it was possible to dissect the trafficking of the two NGF receptors upon neurotrophin stimulation. In FRT (Fischer rat thyroid) cells, endogenous TrkA is localized exclusively on the basolateral surface, while transfected p75NTR is selectively distributed on the apical membrane. This cellular system enabled us to selectively stimulate either p75NTR or TrkA and to analyse the role of receptor trafficking in their signalling capability. We found that, after binding to NGF, p75NTR was co-immunoprecipitated with TrkA and was transcytosed at the basolateral membrane. We showed that the TrkA-p75NTR interaction is necessary for this relocation of p75NTR to the basolateral side. Interestingly, TrkA-specific stimulation by basolateral NGF loading also induced the TrkA-p75NTR interaction and subsequent p75NTR transcytosis at the basolateral surface. Moreover, specific stimulation of p75NTR by NGF activated TrkA and the MAPK (mitogen-activated protein kinase) pathway. Our data indicate that TrkA regulates the subcellular localization of p75NTR upon stimulation with neurotrophins, thus affecting the topology of the signal transduction molecules, driving the activation of a specific signal transduction pathway.
Assuntos
Endocitose , Receptor trkA/metabolismo , Receptores de Fator de Crescimento Neural/metabolismo , Transdução de Sinais , Linhagem Celular , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Polaridade Celular , Endocitose/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Imunoprecipitação , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Fator de Crescimento Neural/farmacologia , Fosforilação/efeitos dos fármacos , Ligação Proteica/efeitos dos fármacos , Transporte Proteico/efeitos dos fármacos , Receptor de Fator de Crescimento Neural , Receptor trkA/genética , Transdução de Sinais/efeitos dos fármacosRESUMO
BACKGROUND: Considerable evidence indicates that diet is an important risk-modifying factor for Alzheimer's disease (AD). Evidence is also mounting that dietary advanced glycation end products (AGEs) are important risk factors for AD. OBJECTIVE: This study strives to determine whether estimated dietary AGEs estimated from national diets and epidemiological studies are associated with increased AD incidence. METHODS: We estimated values of dietary AGEs using values in a published paper. We estimated intake of dietary AGEs from the Washington Heights-Inwood Community Aging Project (WHICAP) 1992 and 1999 cohort studies, which investigated how the Mediterranean diet (MeDi) affected AD incidence. Further, AD prevalence data came from three ecological studies and included data from 11 countries for 1977-1993, seven developing countries for 1995-2005, and Japan for 1985-2008. The analysis used dietary AGE values from 20 years before the AD prevalence data. RESULTS: Meat was always the food with the largest amount of AGEs. Other foods with significant AGEs included fish, cheese, vegetables, and vegetable oil. High MeDi adherence results in lower meat and dairy intake, which possess high AGE content. By using two different models to extrapolate dietary AGE intake in the WHICAP 1992 and 1999 cohort studies, we showed that reduced dietary AGE significantly correlates with reduced AD incidence. For the ecological studies, estimates of dietary AGEs in the national diets corresponded well with AD prevalence data even though the cooking methods were not well known. CONCLUSION: Dietary AGEs appear to be important risk factors for AD.