RESUMO
Parkinson's disease (PD) is a heterogeneous multi-systemic disorder unique to humans characterized by motor and non-motor symptoms. Preclinical experimental models of PD present limitations and inconsistent neurochemical, histological, and behavioral readouts. The 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD is the most common in vivo screening platform for novel drug therapies; nonetheless, behavioral endpoints yielded amongst laboratories are often discordant and inconclusive. In this study, we characterized neurochemically, histologically, and behaviorally three different MPTP mouse models of PD to identify translational traits reminiscent of PD symptomatology. MPTP was intraperitoneally (i.p.) administered in three different regimens: (i) acute-four injections of 20 mg/kg of MPTP every 2 h; (ii) sub-acute-one daily injection of 30 mg/kg of MPTP for 5 consecutive days; and (iii) chronic-one daily injection of 4 mg/kg of MPTP for 28 consecutive days. A series of behavioral tests were conducted to assess motor and non-motor behavioral changes including anxiety, endurance, gait, motor deficits, cognitive impairment, circadian rhythm and food consumption. Impairments in balance and gait were confirmed in the chronic and acute models, respectively, with the latter showing significant correlation with lesion size. The sub-acute model, by contrast, presented with generalized hyperactivity. Both, motor and non-motor changes were identified in the acute and sub-acute regime where habituation to a novel environment was significantly reduced. Moreover, we report increased water and food intake across all three models. Overall, the acute model displayed the most severe lesion size, while across the three models striatal dopamine content (DA) did not correlate with the behavioral performance. The present study demonstrates that detection of behavioral changes following MPTP exposure is challenging and does not correlate with the dopaminergic lesion extent.
Assuntos
Doença de Parkinson , Camundongos , Animais , Humanos , 1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina/farmacologia , Dopamina , Modelos Animais de Doenças , Hipercinese , Camundongos Endogâmicos C57BLRESUMO
Parkinson's disease (PD) is the second most common neurodegenerative disease and results from the loss of dopaminergic neurons of the nigrostriatal pathway. The pathogenesis of PD is poorly understood, but inflammatory processes have been implicated. Indeed increases in the number of major histocompatibility complex II (MHC II) reactive cells have long been recognised in the brains of PD patients at post-mortem. However whether cells expressing MHC II play an active role in PD pathogenesis has not been delineated. This was addressed utilising a transgenic mouse null for MHC II and the parkinsonian toxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). In wild-type mice MHC II levels in the ventral midbrain were upregulated 1-2 days after MPTP treatment and MHC II was localized in both astrocytes and microglia. MHC II null mice showed significant reductions in MPTP-induced dopaminergic neuron loss and a significantly reduced invasion of astrocytes and microglia in MHC II null mice receiving MPTP compared with controls. In addition, MHC II null mice failed to show increases in interferon-γ or tumour necrosis factor-α in the brain after MPTP treatment, as was found in wild-type mice. However, interleukin-1ß was significantly increased in both wild-type and MHC II null mice. These data indicate that in addition to microglial cell/myeloid cell activation MHC Class II-mediated T cell activation is required for the full expression of pathology in this model of PD.
Assuntos
1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina/farmacologia , Imunidade Adaptativa/fisiologia , Regulação da Expressão Gênica/efeitos dos fármacos , Intoxicação por MPTP/imunologia , Ácido 3,4-Di-Hidroxifenilacético/metabolismo , Imunidade Adaptativa/genética , Análise de Variância , Animais , Proteínas de Ligação ao Cálcio/metabolismo , Modelos Animais de Doenças , Regulação da Expressão Gênica/genética , Proteína Glial Fibrilar Ácida/metabolismo , Antígenos de Histocompatibilidade Classe II/genética , Antígenos de Histocompatibilidade Classe II/metabolismo , Humanos , Intoxicação por MPTP/induzido quimicamente , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas dos Microfilamentos/metabolismo , RNA Mensageiro/metabolismo , Fatores de Tempo , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
High-mobility group box 1 (HMGB1) is a nuclear and cytosolic protein that is released during tissue damage from immune and non-immune cells - including microglia and neurons. HMGB1 can contribute to progression of numerous chronic inflammatory and autoimmune diseases which is mediated in part by interaction with the receptor for advanced glycation endproducts (RAGE). There is increasing evidence from in vitro studies that HMGB1 may link the two main pathophysiological components of Parkinson's disease (PD), i.e. progressive dopaminergic degeneration and chronic neuroinflammation which underlie the mechanistic basis of PD progression. Analysis of tissue and biofluid samples from PD patients, showed increased HMGB1 levels in human postmortem substantia nigra specimens as well as in the cerebrospinal fluid and serum of PD patients. In a mouse model of PD induced by sub-acute administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), systemic administration of neutralizing antibodies to HMGB1 partly inhibited the dopaminergic cell death, and reduced the increase of RAGE and tumour necrosis factor-alpha. The small natural molecule glycyrrhizin, a component from liquorice root which can directly bind to HMGB1, both suppressed MPTP-induced HMGB1 and RAGE upregulation while reducing MPTP-induced dopaminergic cell death in a dose dependent manner. These results provide first in vivo evidence that HMGB1 serves as a powerful bridge between progressive dopaminergic neurodegeneration and chronic neuroinflammation in a model of PD, suggesting that HMGB1 is a suitable target for neuroprotective trials in PD.
Assuntos
1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina/farmacologia , Neurônios Dopaminérgicos/efeitos dos fármacos , Ácido Glicirrízico/farmacologia , Proteína HMGB1/metabolismo , Doença de Parkinson/tratamento farmacológico , Idoso , Idoso de 80 Anos ou mais , Animais , Morte Celular/efeitos dos fármacos , Modelos Animais de Doenças , Neurônios Dopaminérgicos/metabolismo , Feminino , Humanos , Masculino , Camundongos Endogâmicos C57BL , Microglia/efeitos dos fármacos , Microglia/metabolismo , Pessoa de Meia-Idade , Fármacos Neuroprotetores/farmacologia , Doença de Parkinson/metabolismo , Fator de Necrose Tumoral alfa/metabolismoRESUMO
The putative protein tyrosine kinase (PTK) inhibitor tyrphostin AG126 has proven beneficial in various models of inflammatory disease. Yet molecular targets and cellular mechanisms remained enigmatic. We demonstrate here that AG126 treatment has beneficial effects in experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis. AG126 alleviates the clinical symptoms, diminishes encephalitogenic Th17 differentiation, reduces inflammatory CNS infiltration as well as microglia activation and attenuates myelin damage. We show that AG126 directly inhibits Bruton's tyrosine kinase (BTK), a PTK associated with B cell receptor and Toll-like receptor (TLR) signaling. However, BTK inhibition cannot account for the entire activity spectrum. Effects on TLR-induced proinflammatory cytokine expression in microglia involve AG126 hydrolysis and conversion of its dinitrile side chain to malononitrile (MN). Notably, while liberated MN can subsequently mediate critical AG126 features, full protection in EAE still requires delivery of intact AG126. Its anti-inflammatory potential and especially interference with TLR signaling thus rely on a dual mechanism encompassing BTK and a novel MN-sensitive target. Both principles bear great potential for the therapeutic management of disturbed innate and adaptive immune functions.
Assuntos
Encefalomielite Autoimune Experimental/tratamento farmacológico , Fármacos Neuroprotetores/farmacologia , Tirfostinas/farmacologia , Tirosina Quinase da Agamaglobulinemia , Animais , Células Cultivadas , Citocinas/metabolismo , Encefalomielite Autoimune Experimental/patologia , Encefalomielite Autoimune Experimental/fisiopatologia , Feminino , Hidrólise , Fatores Imunológicos/química , Fatores Imunológicos/farmacologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microglia/efeitos dos fármacos , Microglia/fisiologia , Fator 88 de Diferenciação Mieloide/metabolismo , Fármacos Neuroprotetores/química , Nitrilas/química , Nitrilas/metabolismo , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Proteínas Tirosina Quinases/antagonistas & inibidores , Proteínas Tirosina Quinases/metabolismo , Transdução de Sinais/efeitos dos fármacos , Baço/citologia , Baço/efeitos dos fármacos , Baço/fisiopatologia , Células Th17/efeitos dos fármacos , Células Th17/patologia , Células Th17/fisiologia , Tirfostinas/químicaRESUMO
Acquired alterations in mitochondrial DNA are believed to play a pathogenic role in Parkinson's disease. In particular, accumulation of mitochondrial DNA deletions has been observed in substantia nigra pars compacta dopaminergic neurons from patients with Parkinson's disease and aged individuals. Also, mutations in mitochondrial DNA polymerase gamma result in multiple mitochondrial DNA deletions that can be associated with levodopa-responsive parkinsonism and severe substantia nigra pars compacta dopaminergic neurodegeneration. However, whether mitochondrial DNA deletions play a causative role in the demise of dopaminergic neurons remains unknown. Here we assessed the potential pathogenic effects of mitochondrial DNA deletions on the dopaminergic nigrostriatal system by using mutant mice possessing a proofreading-deficient form of mitochondrial DNA polymerase gamma (POLGD257A), which results in a time-dependent accumulation of mitochondrial DNA deletions in several tissues, including the brain. In these animals, we assessed the occurrence of mitochondrial DNA deletions within individual substantia nigra pars compacta dopaminergic neurons, by laser capture microdissection and quantitative real-time polymerase chain reaction, and determined the potential deleterious effects of such mitochondrial DNA alterations on mitochondrial function and dopaminergic neuronal integrity, by cytochrome c oxidase histochemistry and quantitative morphology. Nigral dopaminergic neurons from POLGD257A mice accumulate mitochondrial DNA deletions to a similar extent (â¼40-60%) as patients with Parkinson's disease and aged individuals. Despite such high levels of mitochondrial DNA deletions, the majority of substantia nigra pars compacta dopaminergic neurons from these animals did not exhibit mitochondrial dysfunction or degeneration. Only a few individual substantia nigra pars compacta neurons appeared as cytochrome c oxidase-negative, which exhibited higher levels of mitochondrial DNA deletions than cytochrome c oxidase-positive cells (60.38±3.92% versus 45.18±2.83%). Survival of dopaminergic neurons in POLGD257A mice was associated with increased mitochondrial DNA copy number, enhanced mitochondrial cristae network, improved mitochondrial respiration, decreased exacerbation of mitochondria-derived reactive oxygen species, greater striatal dopamine levels and resistance to parkinsonian mitochondrial neurotoxins. These results indicate that primary accumulation of mitochondrial DNA deletions within substantia nigra pars compacta dopaminergic neurons, at an extent similar to that observed in patients with Parkinson's disease, do not kill dopaminergic neurons but trigger neuroprotective compensatory mechanisms at a mitochondrial level that may account for the high pathogenic threshold of mitochondrial DNA deletions in these cells.
Assuntos
Corpo Estriado/metabolismo , DNA Mitocondrial/genética , Neurônios Dopaminérgicos/metabolismo , Doença de Parkinson/genética , Substância Negra/metabolismo , Animais , Morte Celular/genética , Corpo Estriado/patologia , DNA Polimerase gama , DNA Mitocondrial/metabolismo , DNA Polimerase Dirigida por DNA/genética , DNA Polimerase Dirigida por DNA/metabolismo , Neurônios Dopaminérgicos/patologia , Camundongos , Camundongos Transgênicos , Mitocôndrias/genética , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Doença de Parkinson/metabolismo , Doença de Parkinson/patologia , Substância Negra/patologiaRESUMO
Conversion of soluble α-synuclein into insoluble and fibrillar inclusions is a hallmark of Parkinson's disease and other synucleinopathies. Accumulating evidence points towards a relationship between its generation at nerve terminals and structural synaptic pathology. Little is known about the pathogenic impact of α-synuclein conversion and deposition at nigrostriatal dopaminergic synapses in transgenic mice, mainly owing to expression limitations of the α-synuclein construct. Here, we explore whether both the rat as a model and expression of the bacterial artificial chromosome construct consisting of human full-length wild-type α-synuclein could exert dopaminergic neuropathological effects. We found that the human promoter induced a pan-neuronal expression, matching the rodent α-synuclein expression pattern, however, with prominent C-terminally truncated fragments. Ageing promoted conversion of both full-length and C-terminally truncated α-synuclein species into insolube and proteinase K-resistant fibres, with strongest accumulation in the striatum, resembling biochemical changes seen in human Parkinson's disease. Transgenic rats develop early changes in novelty-seeking, avoidance and smell before the progressive motor deficit. Importantly, the observed pathological changes were associated with severe loss of the dopaminergic integrity, thus resembling more closely the human pathology.
Assuntos
Cromossomos Artificiais Bacterianos/genética , Neurônios Dopaminérgicos/patologia , Doença de Parkinson/genética , Doença de Parkinson/patologia , Fenótipo , alfa-Sinucleína/genética , Animais , Modelos Animais de Doenças , Progressão da Doença , Neurônios Dopaminérgicos/metabolismo , Humanos , Doença de Parkinson/metabolismo , Ratos , Ratos Sprague-Dawley , Ratos Transgênicos , alfa-Sinucleína/biossíntese , alfa-Sinucleína/toxicidadeRESUMO
Parkinson's disease is a neurodegenerative disorder that can, at least partly, be mimicked by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. S100B is a calcium-binding protein expressed in, and secreted by, astrocytes. There is increasing evidence that S100B acts as a cytokine or damage-associated molecular pattern protein not only in inflammatory but also in neurodegenerative diseases. In this study, we show that S100B protein levels were higher in post-mortem substantia nigra of patients with Parkinson's disease compared with control tissue, and cerebrospinal fluid S100B levels were higher in a large cohort of patients with Parkinson's disease compared with controls. Correspondingly, mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine showed upregulated S100B messenger RNA and protein levels. In turn, ablation of S100B resulted in neuroprotection, reduced microgliosis and reduced expression of both the receptor for advanced glycation endproducts and tumour necrosis factor-α. Our results demonstrate a role of S100B in the pathophysiology of Parkinson's disease. Targeting S100B may emerge as a potential treatment strategy in this disorder.
Assuntos
Gliose/patologia , Fatores de Crescimento Neural/metabolismo , Fármacos Neuroprotetores/metabolismo , Doença de Parkinson/metabolismo , Receptores Imunológicos/metabolismo , Proteínas S100/metabolismo , Substância Negra/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , 1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina/antagonistas & inibidores , Idoso , Animais , Estudos de Casos e Controles , Linhagem Celular , Modelos Animais de Doenças , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Fatores de Crescimento Neural/genética , Doença de Parkinson/sangue , Doença de Parkinson/líquido cefalorraquidiano , Doença de Parkinson/genética , Doença de Parkinson/patologia , Receptor para Produtos Finais de Glicação Avançada , Subunidade beta da Proteína Ligante de Cálcio S100 , Proteínas S100/genética , Substância Negra/patologia , Regulação para CimaRESUMO
Mutations in the N-terminus of the gene encoding α-synuclein (α-syn) are linked to autosomal dominantly inherited Parkinson's disease (PD). The vast majority of PD patients develop neuropsychiatric symptoms preceding motor impairments. During this premotor stage, synucleinopathy is first detectable in the olfactory bulb (OB) and brain stem nuclei; however its impact on interconnected brain regions and related symptoms is still less far understood. Using a novel conditional transgenic mouse model, displaying region-specific expression of human mutant α-syn, we evaluated effect and reversibility of olfactory synucleinopathy. Our data showed that induction of mutant A30P α-syn expression increased transgenic deposition into somatodendritic compartment of dopaminergic neurons, without generating fibrillar inclusions. We found reversibly reduced levels of dopamine and metabolites in the OB, suggesting an impact of A30P α-syn on olfactory neurotransmitter content. We further showed that mutant A30P expression led to neurodegenerative changes on an ultrastructural level and a behaviorally hyperactive response correlated with novelty, odor processing and stress associated with an increased dopaminergic tone in midbrain regions. Our present data indicate that mutant (A30P) α-syn is directly implicated in reduction of dopamine signaling in OB interneurons, which mediates further alterations in brain regions without transgenic expression leading functionally to a hyperactive response. These modulations of neurotransmission may underlie in part some of the early neuropsychiatric symptoms in PD preceding dysfunction of the nigrostriatal dopaminergic system.
Assuntos
Dopamina/deficiência , Neurônios/metabolismo , Bulbo Olfatório/metabolismo , Transtornos Parkinsonianos/metabolismo , Transtornos Parkinsonianos/fisiopatologia , alfa-Sinucleína/genética , Substituição de Aminoácidos/genética , Animais , Cricetinae , Modelos Animais de Doenças , Dopamina/biossíntese , Feminino , Humanos , Hipercinese/genética , Hipercinese/metabolismo , Hipercinese/fisiopatologia , Masculino , Camundongos , Camundongos Transgênicos , Mutação/genética , Neurônios/patologia , Bulbo Olfatório/patologia , Bulbo Olfatório/fisiopatologia , Transtornos Parkinsonianos/genética , alfa-Sinucleína/biossíntese , alfa-Sinucleína/fisiologiaRESUMO
Synphilin-1 has been identified as an interacting protein of alpha-synuclein, Parkin, and LRRK2, proteins which are mutated in familial forms of Parkinson disease (PD). Subsequently, synphilin-1 has also been shown to be an intrinsic component of Lewy bodies in sporadic PD. In order to elucidate the role of synphilin-1 in the pathogenesis of PD, we generated transgenic mice overexpressing wild-type and mutant (R621C) synphilin-1 driven by a mouse prion protein promoter. Transgenic expression of both wild-type and the R621C variant synphilin-1 resulted in increased dopamine levels of the nigrostriatal system in 3-month-old mice. Furthermore, we found pathological ubiquitin-positive inclusions in cerebellar sections and dark-cell degeneration of Purkinje cells. Both transgenic mouse lines showed significant reduction of motor skill learning and motor performance. These findings suggest a pathological role of overexpressed synphilin-1 in vivo and will help to further elucidate the mechanisms of protein aggregation and neuronal cell death.
Assuntos
Proteínas de Transporte/genética , Proteínas do Tecido Nervoso/genética , Células de Purkinje/metabolismo , Transgenes , alfa-Sinucleína/metabolismo , Animais , Encéfalo/patologia , Feminino , Humanos , Imuno-Histoquímica/métodos , Masculino , Camundongos , Camundongos Transgênicos , Microscopia Eletrônica/métodos , Modelos Genéticos , Neurotransmissores/metabolismo , Tomografia por Emissão de Pósitrons/métodosRESUMO
Parkinson's disease (PD) is the second most common neurodegenerative disease, affecting over a million people in the United States alone, and is characterized by rigidity, bradykinesia, resting tremor, and postural instability. Its main neuropathological feature is the loss of dopaminergic neurons of the substantia nigra pars compacta. However, the pathogenesis of this loss is not understood fully. One of the earliest biochemical changes seen in PD is a reduction in the levels of total glutathione, a key cellular antioxidant. Traditionally, it has been thought that this decrease in GSH levels is the consequence of increased oxidative stress, a process heavily implicated in PD pathogenesis. However, emerging evidence suggests that GSH depletion may itself play an active role in PD pathogenesis. This review aims to explore the contribution of GSH depletion to PD pathogenesis.
Assuntos
Glutationa/metabolismo , Doença de Parkinson/metabolismo , Humanos , Doença de Parkinson/tratamento farmacológicoRESUMO
Alpha-synuclein (alpha-syn) has been implicated in the pathogenesis of many neurodegenerative disorders, including Parkinson's disease. These disorders are characterized by various neurological and psychiatric symptoms based on progressive neuropathological alterations. Whether the neurodegenerative process might be halted or even reversed is presently unknown. Therefore, conditional mouse models are powerful tools to analyze the relationship between transgene expression and progression of the disease. To explore whether alpha-syn solely originates and further incites these alterations, we generated conditional mouse models by using the tet-regulatable system. Mice expressing high levels of human wild-type alpha-syn in midbrain and forebrain regions developed nigral and hippocampal neuropathology, including reduced neurogenesis and neurodegeneration in absence of fibrillary inclusions, leading to cognitive impairment and progressive motor decline. Turning off transgene expression in symptomatic mice halted progression but did not reverse the symptoms. Thus, our data suggest that approaches targeting alpha-syn-induced pathological pathways might be of benefit rather in early disease stages. Furthermore, alpha-syn-associated cytotoxicity is independent of filamentous inclusion body formation in our conditional mouse model.
Assuntos
Transtornos das Habilidades Motoras/patologia , Degeneração Neural/patologia , Degeneração Neural/fisiopatologia , Doença de Parkinson/patologia , Doença de Parkinson/fisiopatologia , Animais , Cricetinae , Modelos Animais de Doenças , Modificador do Efeito Epidemiológico , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Transtornos das Habilidades Motoras/genética , Transtornos das Habilidades Motoras/fisiopatologia , Degeneração Neural/genética , Doença de Parkinson/genéticaRESUMO
Parkinson disease (PD) is a neurodegenerative disorder characterized by a loss of the nigrostriatal dopaminergic neurons accompanied by a deficit in mitochondrial respiration. 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is a neurotoxin that causes dopaminergic neurodegeneration and a mitochondrial deficit reminiscent of PD. Here we show that the infusion of the ketone body d-beta-hydroxybutyrate (DbetaHB) in mice confers partial protection against dopaminergic neurodegeneration and motor deficits induced by MPTP. These effects appear to be mediated by a complex II-dependent mechanism that leads to improved mitochondrial respiration and ATP production. Because of the safety record of ketone bodies in the treatment of epilepsy and their ability to penetrate the blood-brain barrier, DbetaHB may be a novel neuroprotective therapy for PD.
Assuntos
Ácido 3-Hidroxibutírico/metabolismo , Ácido 3-Hidroxibutírico/farmacologia , Respiração Celular/efeitos dos fármacos , Mitocôndrias/metabolismo , Fármacos Neuroprotetores/farmacologia , Doença de Parkinson/metabolismo , 1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Encéfalo/citologia , Encéfalo/metabolismo , Dopamina/metabolismo , Dopaminérgicos/metabolismo , Transporte de Elétrons/fisiologia , Complexo I de Transporte de Elétrons , Humanos , Peróxido de Hidrogênio/metabolismo , Hidroxibutirato Desidrogenase/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Atividade Motora/fisiologia , NAD/metabolismo , NADH NADPH Oxirredutases/metabolismo , Neurônios/citologia , Neurônios/metabolismo , Fármacos Neuroprotetores/metabolismo , Oxidantes/metabolismo , Oxigênio/metabolismo , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
The serine protease HtrA2/Omi is released from the mitochondrial intermembrane space following apoptotic stimuli. Once in the cytosol, HtrA2/Omi has been implicated in promoting cell death by binding to inhibitor of apoptosis proteins (IAPs) via its amino-terminal Reaper-related motif, thus inducing caspase activity, and also in mediating caspase-independent death through its own protease activity. We report here the phenotype of mice entirely lacking expression of HtrA2/Omi due to targeted deletion of its gene, Prss25. These animals, or cells derived from them, show no evidence of reduced rates of cell death but on the contrary suffer loss of a population of neurons in the striatum, resulting in a neurodegenerative disorder with a parkinsonian phenotype that leads to death of the mice around 30 days after birth. The phenotype of these mice suggests that it is the protease function of this protein and not its IAP binding motif that is critical. This conclusion is reinforced by the finding that simultaneous deletion of the other major IAP binding protein, Smac/DIABLO, does not obviously alter the phenotype of HtrA2/Omi knockout mice or cells derived from them. Mammalian HtrA2/Omi is therefore likely to function in vivo in a manner similar to that of its bacterial homologues DegS and DegP, which are involved in protection against cell stress, and not like the proapoptotic Reaper family proteins in Drosophila melanogaster.
Assuntos
Corpo Estriado/embriologia , Corpo Estriado/enzimologia , Serina Endopeptidases/fisiologia , Animais , Apoptose/fisiologia , Proteínas Reguladoras de Apoptose , Sequência de Bases , Proteínas de Transporte/genética , Proteínas de Transporte/fisiologia , Corpo Estriado/anormalidades , DNA/genética , Feminino , Marcação de Genes , Serina Peptidase 2 de Requerimento de Alta Temperatura A , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mitocôndrias/metabolismo , Proteínas Mitocondriais/deficiência , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/fisiologia , Neurônios/patologia , Transtornos Parkinsonianos/embriologia , Transtornos Parkinsonianos/etiologia , Transtornos Parkinsonianos/genética , Fenótipo , Gravidez , Proteínas/metabolismo , Serina Endopeptidases/deficiência , Serina Endopeptidases/genética , Proteínas Inibidoras de Apoptose Ligadas ao Cromossomo XRESUMO
Parkinson's disease (PD) is characterized by a loss of ventral midbrain dopaminergic neurons, which can be modeled by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Inflammatory oxidants have emerged as key contributors to PD- and MPTP-related neurodegeneration. Here, we show that myeloperoxidase (MPO), a key oxidant-producing enzyme during inflammation, is upregulated in the ventral midbrain of human PD and MPTP mice. We also show that ventral midbrain dopaminergic neurons of mutant mice deficient in MPO are more resistant to MPTP-induced cytotoxicity than their wild-type littermates. Supporting the oxidative damaging role of MPO in this PD model are the demonstrations that MPO-specific biomarkers 3-chlorotyrosine and hypochlorous acid-modified proteins increase in the brains of MPTP-injected mice. This study demonstrates that MPO participates in the MPTP neurotoxic process and suggests that inhibitors of MPO may provide a protective benefit in PD.
Assuntos
Encéfalo/enzimologia , Transtornos Parkinsonianos/enzimologia , Peroxidase/fisiologia , 1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina/farmacocinética , Esclerose Lateral Amiotrófica/enzimologia , Animais , Corpo Estriado/enzimologia , Dopamina/análise , Avaliação Pré-Clínica de Medicamentos , Indução Enzimática , Humanos , Doença de Huntington/enzimologia , Ácido Hipocloroso/análise , Masculino , Mesencéfalo/enzimologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas do Tecido Nervoso/química , Neurônios/efeitos dos fármacos , Neurônios/enzimologia , Estresse Oxidativo , Doença de Parkinson/enzimologia , Peroxidase/biossíntese , Peroxidase/deficiência , Peroxidase/genética , RNA Mensageiro/biossíntese , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Tirosina/análogos & derivados , Tirosina/análiseRESUMO
1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) damages the nigrostriatal dopaminergic pathway as seen in Parkinson's disease (PD), a common neurodegenerative disorder with no effective protective treatment. Consistent with a role of glial cells in PD neurodegeneration, here we show that minocycline, an approved tetracycline derivative that inhibits microglial activation independently of its antimicrobial properties, mitigates both the demise of nigrostriatal dopaminergic neurons and the formation of nitrotyrosine produced by MPTP. In addition, we show that minocycline not only prevents MPTP-induced activation of microglia but also the formation of mature interleukin-1beta and the activation of NADPH-oxidase and inducible nitric oxide synthase (iNOS), three key microglial-derived cytotoxic mediators. Previously, we demonstrated that ablation of iNOS attenuates MPTP-induced neurotoxicity. Now, we demonstrate that iNOS is not the only microglial-related culprit implicated in MPTP-induced toxicity because mutant iNOS-deficient mice treated with minocycline are more resistant to this neurotoxin than iNOS-deficient mice not treated with minocycline. This study demonstrates that microglial-related inflammatory events play a significant role in the MPTP neurotoxic process and suggests that minocycline may be a valuable neuroprotective agent for the treatment of PD.
Assuntos
Microglia/metabolismo , Minociclina/farmacologia , Fármacos Neuroprotetores/farmacologia , Transtornos Parkinsonianos/prevenção & controle , Tirosina/análogos & derivados , 1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina/metabolismo , Animais , Antibacterianos/farmacologia , Astrócitos/efeitos dos fármacos , Astrócitos/patologia , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/patologia , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Interleucina-1/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microglia/efeitos dos fármacos , Microglia/patologia , NADPH Oxidases/metabolismo , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Neurônios/patologia , Óxido Nítrico Sintase/deficiência , Óxido Nítrico Sintase/genética , Óxido Nítrico Sintase/metabolismo , Óxido Nítrico Sintase Tipo II , Transtornos Parkinsonianos/induzido quimicamente , Transtornos Parkinsonianos/patologia , Substância Negra/efeitos dos fármacos , Substância Negra/patologia , Tirosina/metabolismo , Tirosina 3-Mono-Oxigenase/metabolismo , Regulação para Cima/efeitos dos fármacosRESUMO
S100B is a Ca2+ binding protein and is typically associated with brain and CNS disorders. However, the role of S100B in an inflammatory situation is not clear. The aim of the study was to determine whether S100B is likely to influence inflammation through its effect on macrophages. A murine macrophage cell line (RAW 264.7) and primary bone marrow derived macrophages were used for in vitro studies and a model of retinal inflammatory disease in which pathogenesis is highly dependent on macrophage infiltration, Experimental Autoimmune Uveoretinitis, for in vitro study. Experimental Autoimmune Uveoretinitis is a model for the human disease posterior endogenous uveoretinitis, a potentially blinding condition, with an autoimmune aetiology, that mainly affects the working age group. To date the involvement of S100B in autoimmune uveoretinitis has not been investigated. Real-time PCR array analysis on RAW 246.7 cells indicated up-regulation of gene expression for various cytokines/chemokines in response to S100B, IL-1ß and CCL22 in particular and this was confirmed by real-time PCR. In addition flow cytometry and ELISA confirmed up-regulation of protein production in response to S100B for pro-IL-1ß and CCL22 respectively. This was the case for both RAW 264.7 cells and bone marrow derived macrophages. Induction of EAU with retinal antigen in mice in which S100B had been deleted resulted in a significantly reduced level of disease compared to wild-type mice, as determined by topical endoscopic fundus imaging and histology grading. Macrophage infiltration was also significantly reduced in S100B deleted mice. Real-time PCR analysis indicated that this was associated with reduction in CCL22 and IL-1ß in retinas from S100B knock-out mice. In conclusion S100B augments the inflammatory response in uveoretinitis and this is likely to be, at least in part, via a direct effect on macrophages.
Assuntos
Quimiocina CCL22/genética , Interleucina-1beta/genética , Macrófagos/imunologia , Retinite/genética , Subunidade beta da Proteína Ligante de Cálcio S100/metabolismo , Uveíte/genética , Animais , Linhagem Celular , Quimiocina CCL22/metabolismo , Modelos Animais de Doenças , Regulação da Expressão Gênica , Interleucina-1beta/metabolismo , Macrófagos/patologia , Camundongos , Camundongos Knockout , Retinite/metabolismo , Retinite/patologia , Subunidade beta da Proteína Ligante de Cálcio S100/genética , Uveíte/metabolismo , Uveíte/patologiaRESUMO
Parkinson's disease (PD) is a common chronic neurodegenerative disorder, usually of idiopathic origin. Symptoms including tremor, bradykinesia, rigidity and postural instability are caused by the progressive loss of dopaminergic neurons in the nigrostriatal region of the brain. Symptomatic therapies are available but no treatment slows or prevents the loss of neurons. Neuroinflammation has been implicated in its pathogenesis. To this end, the present study utilises the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) neurotoxin to reproduce the pattern of cell death evident in PD patients. Herein, the role of a potential regulator of an immune response, the endocannabinoid system (ECS), is investigated. The most prevalent endocannabinoid, 2-arachidonoylglycerol (2-AG) (3 and 5mg/kg), was added exogenously and its enzymatic degradation inhibited to provide protection against MPTP-induced cell death. Furthermore, the addition of DFU (25mg/kg), a selective inhibitor of inflammatory mediator cyclooxygenase-2 (COX-2), potentiated these effects. Levels of 2-AG were shown to be upregulated in a time- and region-specific manner following MPTP administration, indicating that the ECS represents a natural defence mechanism against inflammation, potentiation of which could provide therapeutic benefits. The results expand the current understanding of the role that this signalling system has and its potential influence in PD.
Assuntos
1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina , Ácidos Araquidônicos/uso terapêutico , Endocanabinoides/uso terapêutico , Glicerídeos/uso terapêutico , Fármacos Neuroprotetores/uso terapêutico , Neurotoxinas/toxicidade , Doença de Parkinson/dietoterapia , Doença de Parkinson/etiologia , 1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina/farmacologia , Animais , Benzodioxóis/uso terapêutico , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/patologia , Morte Celular/efeitos dos fármacos , Ciclo-Oxigenase 2/metabolismo , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/farmacologia , Furanos/uso terapêutico , Transtornos Neurológicos da Marcha/tratamento farmacológico , Transtornos Neurológicos da Marcha/etiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Atividade Motora/efeitos dos fármacos , Doença de Parkinson/complicações , Doença de Parkinson/patologia , Piperidinas/uso terapêutico , Fatores de Tempo , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
Dystonia is a highly frequent movement disorder, the pathogenesis of which remains unclear. The cloning of TorsinA, the gene responsible for early-onset dystonia, was a major breakthrough. However, the function of this protein remains unclear. By sequence homology, TorsinA belongs to the ATPases associated with diverse cellular activities-family, many of whose members are chaperones and/or proteases. We report here that in an in vitro model for oxidative stress, H2O2 treatment, overexpression of TorsinA was protective against cell death. COS-1 cells overexpressing TorsinA demonstrated drastically reduced terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling-staining following exposure to H2O2. Furthermore, transfection with TorsinA significantly increased survival of PC12 after H2O2 treatment. To our knowledge, this is the first demonstration that TorsinA protects against oxidative stress. We speculate that a loss of this cellular function in mutant TorsinA may be linked to the pathogenesis of early-onset dystonia.
Assuntos
Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Morte Celular/fisiologia , Distonia/genética , Chaperonas Moleculares , Estresse Oxidativo/fisiologia , Proteínas Proto-Oncogênicas c-bcl-2 , Animais , Células COS , Sobrevivência Celular , Peróxido de Hidrogênio/toxicidade , Marcação In Situ das Extremidades Cortadas , Células PC12 , Proteínas Proto-Oncogênicas/metabolismo , Ratos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transfecção , Proteína X Associada a bcl-2RESUMO
Early-onset torsion dystonias are caused by a mutation in TorsinA, a protein widely expressed in the nervous system. Here we report the cloning of the murine TorsinA cDNA and a mRNA in situ hybridization analysis of the expression patterns of TorsinA over developmental periods relevant to the etiology of early-onset dystonias. Several studies have demonstrated a functional involvement of the nigrostriatal dopaminergic system in pathological mechanisms underlying dystonia. In this study, we show that the expression of TorsinA is significantly increased in the brain within hours of treatment with the dopaminergic toxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in mice, suggesting that the TorsinA gene is regulated by cellular stress. These results provide insights into the pathophysiology of early-onset dystonia and strengthen links between the dopaminergic system and dystonia.
Assuntos
Proteínas de Transporte/genética , Dopamina/metabolismo , Distonia Muscular Deformante/genética , Chaperonas Moleculares , Neurônios/metabolismo , Substância Negra/metabolismo , 1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina/farmacologia , Idade de Início , Animais , Animais Recém-Nascidos , DNA Complementar/análise , DNA Complementar/genética , Intoxicação por MPTP/genética , Intoxicação por MPTP/metabolismo , Intoxicação por MPTP/fisiopatologia , Camundongos , Camundongos Endogâmicos C57BL , Dados de Sequência Molecular , Degeneração Neural/induzido quimicamente , Degeneração Neural/genética , Degeneração Neural/metabolismo , Neurônios/efeitos dos fármacos , Neurotoxinas/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/genética , RNA Mensageiro/efeitos dos fármacos , RNA Mensageiro/metabolismo , Homologia de Sequência de Aminoácidos , Homologia de Sequência do Ácido Nucleico , Substância Negra/efeitos dos fármacos , Substância Negra/fisiopatologia , Regulação para Cima/efeitos dos fármacos , Regulação para Cima/genéticaRESUMO
The enzyme cyclooxygenase-2 (COX-2), responsible for the first committed step in the synthesis of several important mediators which are involved in both initiation and resolution of inflammation, and the subsequent generation of prostaglandins (PGs) upon activation has been shown to participate in the neurodegenerative processes of a variety of diseases. This review looks particular at the role of COX-2 in the pathogenesis of Parkinson's disease, involving the generation of PGs and the role of the two different parts of the cyclooxygenase-cyclooxygenase and peroxidase activity.