RESUMEN
OBJECTIVE: Trisomy 21 is the most frequent genetic cause of intellectual disability. Tumor Protein 53 (TP53) gene down-regulation triggers chromosomal instability. A TP53 gene polymorphism c.215G > C (rs1042522) is associated with accumulation of aneuploid cells. We analyzed the TP53 c.215G > C (rs1042522) polymorphism in Sicilian mothers of subjects with Down Syndrome (DS) within a case-control study. METHODS: Nucleotide polymorphism was detected by pyrosequencing technology. RESULTS: The distribution of TP53 c.215G > C polymorphism showed significant difference between mothers of subjects with DS and controls. CONCLUSIONS: Our data show that TP53 c.215G > C polymorphism is a risk factor for DS in Sicilian mothers.
Asunto(s)
Síndrome de Down/genética , Madres , Polimorfismo de Nucleótido Simple , Proteína p53 Supresora de Tumor/genética , Adulto , Anciano , Estudios de Casos y Controles , Síndrome de Down/epidemiología , Femenino , Frecuencia de los Genes , Predisposición Genética a la Enfermedad , Humanos , Persona de Mediana Edad , Embarazo , Factores de Riesgo , Sicilia/epidemiologíaRESUMEN
Down syndrome is characterized by dysmorphic features, mental retardation and problems of immune deficiency. Chronic infection by Epstein-Barr virus is frequently present in subjects with Down syndrome. Ksp37 gene is commonly expressed by NK, CD8(+) T, γδ T and CD4(+) T cells; these data suggest that Ksp37 have cytotoxic properties. An increase of Ksp37 protein serum levels it has been showed during the acute phase of Epstein-Barr virus. In this study, we evaluated the expression of Ksp37 mRNA, in fibroblasts and leukocytes of DS subjects and in normal subjects with realtime reverse transcription-PCR. This analysis shows that in fibroblasts and leukocytes of Down syndrome subjects the KSP37 gene expression was increased compared with control subjects. The results of this study suggest that the expression of Ksp37 gene might be associated with increased susceptibility of individuals with Down syndrome to EBV infections and autoimmune problems.
Asunto(s)
Proteínas Sanguíneas/genética , Proteínas Sanguíneas/metabolismo , Síndrome de Down/genética , Síndrome de Down/patología , Leucocitos/metabolismo , Adulto , Estudios de Casos y Controles , Femenino , Fibroblastos/metabolismo , Humanos , Masculino , Persona de Mediana Edad , ARN Mensajero/metabolismo , Adulto JovenAsunto(s)
Enfermedad de Parkinson/epidemiología , Enfermedad de Parkinson/genética , Poli(ADP-Ribosa) Polimerasa-1/genética , Polimorfismo Genético/genética , Anciano , Anciano de 80 o más Años , Femenino , Frecuencia de los Genes/genética , Humanos , Masculino , Enfermedad de Parkinson/diagnóstico , Sicilia/epidemiologíaRESUMEN
Wnt/ß-catenin signaling is required for specification and neurogenesis of midbrain dopaminergic (mDA) neurons, the pivotal neuronal population that degenerates in Parkinson's disease (PD), and in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. Wnt/ß-catenin signaling plays a vital role in adult neurogenesis but whether it might engage DA neurogenesis/neurorepair in the affected PD brain is yet unresolved. Recently, the adult midbrain aqueduct periventricular regions (Aq-PVRs) were shown to harbor multipotent clonogenic neural stem/progenitor cells (mNPCs) with DA potential in vitro, but restrictive mechanisms in vivo are believed to limit their DA regenerative capacity. Using in vitro mNPC culture systems we herein demonstrate that aging is one most critical factor restricting mNPC neurogenic potential via dysregulation of Wnt/ß-catenin signaling. Coculture paradigms between young/aged (Y/A) mNPCs and Y/A astrocytes identified glial age and a decline of glial-derived factors including Wnts as key determinants of impaired neurogenic potential, whereas Wnt activation regimens efficiently reversed the diminished proliferative, neuronal, and DA differentiation potential of A-mNPCs. Next, in vivo studies in wild (Wt) and transgenic ß-catenin reporter mice uncovered Wnt/ß-catenin signaling activation and remarkable astrocyte remodeling of Aq-PVR in response to MPTP-induced DA neuron death. Spatio-temporal analyses unveiled ß-catenin signaling in predopaminergic (Nurr1(+)/TH(-)) and imperiled or rescuing DAT(+) neurons during MPTP-induced DA neuron injury and self-repair. Aging inhibited Wnt signaling, whereas ß-catenin activation in situ with a specific GSK-3ß antagonist promoted a significant degree of DA neurorestoration associated with reversal of motor deficit, with implications for neurorestorative approaches in PD.
Asunto(s)
Envejecimiento/metabolismo , Células-Madre Neurales/metabolismo , Neurogénesis/fisiología , Enfermedad de Parkinson/metabolismo , Vía de Señalización Wnt/fisiología , Animales , Western Blotting , Técnicas de Cocultivo , Modelos Animales de Enfermedad , Neuronas Dopaminérgicas/metabolismo , Inmunohistoquímica , Masculino , Mesencéfalo/metabolismo , Mesencéfalo/patología , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Neuroglía/metabolismo , Enfermedad de Parkinson/fisiopatología , Reacción en Cadena en Tiempo Real de la Polimerasa , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
During the past three decades, the Wingless-type MMTV integration site (Wnt) signaling cascade has emerged as an essential system regulating multiple processes in developing and adult brain. Accumulating evidence points to a dysregulation of Wnt signaling in major neurodegenerative pathologies including Parkinson's disease (PD), a common neurodegenerative disorder characterized by the progressive loss of midbrain dopaminergic (mDA) neurons and deregulated activation of astrocytes and microglia. This review highlights the emerging link between Wnt signaling and key inflammatory pathways during mDA neuron damage/repair in PD progression. In particular, we summarize recent evidence documenting that aging and neurotoxicant exposure strongly antagonize Wnt/ß-catenin signaling in mDA neurons and subventricular zone (SVZ) neuroprogenitors via astrocyte-microglial interactions. Dysregulation of the crosstalk between Wnt/ß-catenin signaling and anti-oxidant/anti-inflammatory pathways delineate novel mechanisms driving the decline of SVZ plasticity with age and the limited nigrostriatal dopaminergic self-repair in PD. These findings hold a promise in developing therapies that target Wnt/ß-catenin signaling to enhance endogenous restoration and neuronal outcome in age-dependent diseases, such as PD.
Asunto(s)
Neuronas Dopaminérgicas/fisiología , Regeneración Nerviosa/genética , Neuroinmunomodulación/genética , Enfermedad de Parkinson/metabolismo , Encéfalo/metabolismo , Encéfalo/patología , Supervivencia Celular , Microambiente Celular , Modelos Biológicos , Degeneración Nerviosa/genética , Degeneración Nerviosa/metabolismo , Degeneración Nerviosa/patología , Enfermedad de Parkinson/genéticaRESUMEN
Parkinsons'disease (PD), a common neurodegenerative disorder, is characterized by progressive loss of dopaminergic (DAergic) neurons in the subtantia nigra pars compacta (SNpc) and gliosis. The cause and mechanisms underlying the demise of nigrostriatal DAergic neurons are not completely clarified, but interactions between genes and environmental factors are recognized to play a critical role in modulating the vulnerability to PD. Current evidence points to reactive glia as a pivotal factor in PD, but whether astroglia activation may protect or exacerbate DAergic neuron loss is presently the subject of much debate. Astrocytes and microglia are the key players in neuroinflammatory responses, by secreting an array of pro- and anti-inflammatory cytokines, anti-oxidant and neurotrophic factors. Here, the contribution of astrocytes and their ability to influence DAergic neurodegeneration, neuroprotection and neurorepair will be discussed. In particular, the dynamic interplay between astrocyte-derived factors and neurogenic signals in MPTP-induced plasticity of nigrostriatal DAergic neurons will be summarized together with recent findings showing that reactive astrocytes may contribute to promote DAergic neurogenesis from midbrain adult neural stem/precursor cells (NPCs). Within a host of astrocyte- derived factors, we unveiled Wingless-type MMTV integration site (Wnt)/ß-catenin signalling was unveiled, as a strong candidate in MPTP-induced DAergic neuroplasticty/neurorepair. Understanding the intrinsic plasticity of nigrostriatal DAergic neurons and decifering the signals facilitating the crosstalk between astrocytes and midbrain neuroprogenitors may have implications for the role of stem cells technology in PD and for identifying potential therapeutic targets to promote endogenous neurorepair.
Asunto(s)
Astrocitos/fisiología , Neuronas Dopaminérgicas/fisiología , Trastornos Parkinsonianos/etiología , Animales , Astrocitos/patología , Neuronas Dopaminérgicas/patología , Humanos , Inflamación/patología , Inflamación/fisiopatología , Intoxicación por MPTP/etiología , Intoxicación por MPTP/patología , Intoxicación por MPTP/fisiopatología , Ratones , Modelos Neurológicos , Degeneración Nerviosa/patología , Degeneración Nerviosa/fisiopatología , Regeneración Nerviosa/fisiología , Neurogénesis/fisiología , Estrés Oxidativo , Trastornos Parkinsonianos/patología , Trastornos Parkinsonianos/fisiopatología , Sustancia Negra/patología , Sustancia Negra/fisiopatología , Corteza Visual/patología , Corteza Visual/fisiopatología , Vía de Señalización WntRESUMEN
Parkinson's disease (PD) is a common neurodegenerative disorder characterized by progressive loss of dopaminergic (DAergic) neuronal cell bodies in the substantia nigra pars compacta and gliosis. The cause and mechanisms underlying the demise of nigrostriatal DAergic neurons are ill-defined, but interactions between genes and environmental factors are recognized to play a critical role in modulating the vulnerability to PD. Current evidence points to reactive glia as a pivotal factor in PD pathophysiology, playing both protective and destructive roles. Here, the contribution of reactive astrocytes and their ability to modulate DAergic neurodegeneration, neuroprotection and neurorepair in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) rodent model of PD will be discussed in the light of novel emerging evidence implicating wingless-type mouse mammary tumor virus integration site (Wnt)/ß-catenin signaling as a strong candidate in MPTP-induced nigrostriatal DAergic plasticity. In this work, we highlight an intrinsic Wnt1/frizzled-1/ß-catenin tone that critically contributes to the survival and protection of adult midbrain DAergic neurons, with potential implications for drug design or drug action in PD. The dynamic interplay between astrocyte-derived factors and neurogenic signals in MPTP-induced nigrostriatal DAergic neurotoxicity and repair will be summarized, together with recent findings showing a critical role of glia-neural stem/progenitor cell (NPC) interactions aimed at overcoming neurodegeneration and inducing neurorestoration. Understanding the intrinsic plasticity of nigrostriatal DAergic neurons and deciphering the signals facilitating the crosstalk between astrocytes, microglia, DAergic neurons and NPCs may have major implications for the role of stem cell technology in PD, and for identifying potential therapeutic targets to induce endogenous neurorepair.
Asunto(s)
Astrocitos/metabolismo , Intoxicación por MPTP/metabolismo , Neuronas/metabolismo , Vía de Señalización Wnt , Animales , Intoxicación por MPTP/patología , RatonesRESUMEN
Aging represents a major risk factor for the development and progression of Parkinson disease (PD), a chronic degenerative disorder characterized by the selective loss of dopaminergic (DAergic) neurons in the subtantia nigra pars compacta (SNpc). Emerging evidence highlights the glia as a pivotal factor in PD etiology, and epidemiological studies indicate that certain nonsteroidal antiinflammatory drugs (NSAIDs) may prevent or delay the progression of PD. Given that the exaggerated inflammatory response observed in old age may play a critical role in exacerbating DAergic vulnerability, we hypothesize here that switching the harmful glial response to inflammation and oxidative stress might increase the ability of the SN to resist inflammatory attacks. To this end, we developed a treatment in which we combined the effects of nitric oxide (NO) with nonsteroidal antiinflammatory activity by using HCT1026, a NO-donating derivative of flurbiprofen that has a safe profile and additional immunomodulatory properties. Young and aged mice fed with control or HCT1026 (30 mg kg(-1) day(-1)) diet were exposed to a single systemic injection of a subtoxic dose (0.2 mg kg(-1)) of lipopolysaccharide (LPS), one of the most extensively used glial activators. HCT1026 efficiently reversed the age-dependent increase of microglial activation in response to LPS to levels measured in younger mice. In aged mice, LPS induced a progressive loss of DAergic neurons with no recovery for their entire life span, whereas younger mice or aged mice fed with HCT1026 were resistant to systemic LPS-induced DAergic neurodegeneration, underscoring glia as a key pharmacological target for DAergic neuroprotection.
Asunto(s)
Envejecimiento/patología , Neuronas Dopaminérgicas/patología , Inflamación/patología , Microglía/patología , Degeneración Nerviosa/patología , Regeneración Nerviosa , Sustancia Negra/patología , Envejecimiento/efectos de los fármacos , Animales , Neuronas Dopaminérgicas/efectos de los fármacos , Flurbiprofeno/análogos & derivados , Flurbiprofeno/farmacología , Inflamación/complicaciones , Lipopolisacáridos/farmacología , Masculino , Ratones , Ratones Endogámicos C57BL , Microglía/efectos de los fármacos , Degeneración Nerviosa/complicaciones , Regeneración Nerviosa/efectos de los fármacos , Nitrosación/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Fenotipo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Reacción en Cadena en Tiempo Real de la Polimerasa , Sustancia Negra/efectos de los fármacos , Tirosina 3-Monooxigenasa/metabolismoRESUMEN
Parkinson's disease (PD) is a common neurodegenerative disorder characterized by the presence of tremor, muscle rigidity, slowness of voluntary movements and postural instability. One of the pathological hallmarks of PD is loss of dopaminergic (DAergic) neurons in the subtantia nigra pars compacta (SNpc). The cause and mechanisms underlying the demise of nigrostriatal DAergic neurons are not fully understood, but interactions between genes and environmental factors are recognized to play a critical role in modulating the vulnerability to PD. Current evidence points to reactive glia as a pivotal factor in PD, but whether astroglia activation may protect or exacerbate DAergic neuron loss is the subject of much debate. Astrocytes and microglia are the key players in neuroinflammatory responses, secreting an array of pro- and anti-inflammatory cytokines, anti-oxidants and neurotrophic factors. These mediators act as double-edged swords, exerting both detrimental and neuroprotective effects. Here, the contribution of astrocytes and microglia in mediating the effects of both genetic and environmental factors, including hormones, endotoxins and neurotoxins, and their ability to influence DAergic neurodegeneration, neuroprotection and neurorepair will be discussed. Approaches capable to regulate glial-associated oxidative stress and mitochondrial damage, by decreasing inflammatory burden, restoring mitochondrial function and DAergic neuron metabolism, might hold great promise for therapeutic interventions. Therapies that support astrocyte function, replacing astrocytes either modified or unmodified in culture, may represent novel approaches targeting astrocytes to promote DAergic neurorescue. Dissecting the molecular determinants of glia-neuron crosstalk will give us the possibility to test novel strategies to promote restoration of injured nigrostriatal DAergic neurons.
Asunto(s)
Neuroglía/efectos de los fármacos , Neuroglía/patología , Enfermedad de Parkinson/tratamiento farmacológico , Enfermedad de Parkinson/patología , Animales , Astrocitos/efectos de los fármacos , Astrocitos/metabolismo , Astrocitos/patología , Humanos , Microglía/efectos de los fármacos , Microglía/metabolismo , Microglía/patología , Neuroglía/metabolismo , Enfermedad de Parkinson/genética , Enfermedad de Parkinson/metabolismoRESUMEN
Several epidemiological investigations conducted in Sardinia, insular Italy, indicate that the strong selective pressure of malaria along the centuries may have concurred to the elevated genetic MS-risk in this region. To test such hypothesis in an experimental setting, we have compared the immune response to P. falciparum (the causative agent of malaria) in Sardinian MS patients relative to their ethnic healthy controls and control MS patients of different ethnicity. To this purpose, the P. falciparum-driven peripheral mononuclear cell proliferation, the production of pro-inflammatory cytokines of the innate immunity such as TNF-alpha, IL-6 and IL-12 and the ability to inhibit the parasite growth have been tested in relation to HLA-DR alleles and TNF promoter polymorphisms known of being associated to MS. We found that P. falciparum-induced proliferation, cytokine production and parasite killing are significantly augmented in Sardinian MS patients as compared to controls (p<0.01). Additionally, a correlation is found with genes associated to Sardinian MS, namely the TNF(-376A) promoter polymorphism and the class II HLA-DRB1*0405 allele. In conclusion, we have found evidences that some genetic traits formerly selected to confer a protective responses to P. falciparum now partially contribute to the elevated MS susceptibility amongst Sardinians.
Asunto(s)
Inmunidad Innata , Malaria/inmunología , Esclerosis Múltiple/microbiología , Plasmodium falciparum/inmunología , Adulto , Animales , Proliferación Celular , Ensayo de Inmunoadsorción Enzimática , Femenino , Predisposición Genética a la Enfermedad , Antígenos HLA-DR , Humanos , Subunidad p40 de la Interleucina-12/biosíntesis , Interleucina-6/biosíntesis , Leucocitos Mononucleares/inmunología , Leucocitos Mononucleares/metabolismo , Masculino , Esclerosis Múltiple/inmunología , Polimorfismo Genético , Factor de Necrosis Tumoral alfa/biosíntesisRESUMEN
Reduction of core body temperature has been proposed to contribute to the increased life span and the antiaging effects conferred by calorie restriction (CR). Validation of this hypothesis has been difficult in homeotherms, primarily due to a lack of experimental models. We report that transgenic mice engineered to overexpress the uncoupling protein 2 in hypocretin neurons (Hcrt-UCP2) have elevated hypothalamic temperature. The effects of local temperature elevation on the central thermostat resulted in a 0.3 degrees to 0.5 degrees C reduction of the core body temperature. Fed ad libitum, Hcrt-UCP2 transgenic mice had the same caloric intake as their wild-type littermates but had increased energy efficiency and a greater median life span (12% increase in males; 20% increase in females). Thus, modest, sustained reduction of core body temperature prolonged life span independent of altered diet or CR.
Asunto(s)
Temperatura Corporal , Longevidad , Área Preóptica/fisiología , Envejecimiento , Animales , Regulación de la Temperatura Corporal , Peso Corporal , Ritmo Circadiano , Ingestión de Líquidos , Ingestión de Alimentos , Metabolismo Energético , Femenino , Área Hipotalámica Lateral/citología , Área Hipotalámica Lateral/metabolismo , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Canales Iónicos/genética , Canales Iónicos/fisiología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Proteínas Mitocondriales/genética , Proteínas Mitocondriales/fisiología , Neuronas/metabolismo , Neuropéptidos/metabolismo , Orexinas , Área Preóptica/citología , Termogénesis , Proteína Desacopladora 2RESUMEN
Inflammation and oxidative stress have been closely associated with the pathogenesis of neurodegenerative disorders, including Parkinson's disease (PD). The expression of inducible nitric oxide synthase (iNOS) in astrocytes and microglia and the production of large amounts of nitric oxide (NO) are thought to contribute to dopaminergic neuron demise. Increasing evidence, however, indicates that activated astroglial cells play key roles in neuroprotection and can promote recovery of CNS functions. Endogenous glucocorticoids (GCs) via glucocorticoid receptors (GRs) exert potent anti-inflammatory and immunosuppressive effects and are key players in protecting the brain against stimulation of innate immunity. Here we review our work showing that exposure to a dysfunctional GR from early embryonic life in transgenic (Tg) mice expressing GR antisense RNA represents a key vulnerability factor in the response of nigrostriatal dopaminergic neurons to the neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), and further report that exacerbation of dopaminergic neurotoxicity with no recovery is determined by failure of astroglia to exert neuroprotective effects. Aberrant iNOS gene expression and increased glia vulnerability to cell death characterized the response of GR-deficient mice to stimulation of innate immunity. More importantly, GR-deficient glial cells failed to protect fetal dopaminergic neurons against oxidative stress-induces cell death, whereas wild-type glia afforded neuroprotection. Thus, lack of iNOS/NO regulation by GCs can program an aberrant GR-NO crosstalk in turn responsible for loss of astroglia neuroprotective function in response to stimulation of innate immunity, pointing to glia and efficient GR-NO dialogue as pivotal factors orchestrating neuroprotection in experimental parkinsonism.
Asunto(s)
Neuroglía/fisiología , Neuronas/fisiología , Óxido Nítrico/fisiología , Trastornos Parkinsonianos/fisiopatología , Receptor Cross-Talk/fisiología , Receptores de Glucocorticoides/fisiología , 1-Metil-4-fenil-1,2,3,6-Tetrahidropiridina/farmacología , Animales , Relación Dosis-Respuesta a Droga , Regulación de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica/fisiología , Humanos , Modelos Biológicos , Neuroglía/efectos de los fármacos , Neuronas/efectos de los fármacos , Trastornos Parkinsonianos/inducido químicamenteRESUMEN
Alterations in developmental programming of neuroendocrine and immune system function may critically modulate vulnerability to various diseases. In particular, genetic factors, including gender, may interact with early life events such as exposure to hormones, endotoxins, or neurotoxins, thereby influencing disease predisposition and/or severity, but little is known about the role of the astroglial cell compartment and its mediators in this phenomenon. Indeed, in the context of innate inflammatory mechanisms, a dysfunction of the astroglial cell compartment is believed to contribute to the selective degeneration of dopaminergic (DA) neurons in the substantia nigra pars compacta in Parkinson's disease (PD) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of PD. Hence, in response to brain injury the roles of astrocytes and microglia are very dynamic and cell type-dependent, in that they may exert the known proinflammatory (harmful) effects, but in certain circumstances they can turn into highly protective cells and exert anti-inflammatory (beneficial) functions, thereby facilitating neuronal recovery and repair. Here, we summarize our work suggesting a chief role of hormonal programming of glial response to inflammation and oxidative stress in MPTP-induced loss of DA neuron functionality and demonstrate that endogenous glucocorticoids and the female hormone estrogen (E(2)) inhibit the aberrant neuroinflammatory cascade, protect astrocytes and microglia from programmed cell death, and stimulate recovery of DA neuron functionality, thereby triggering the repair process. The overall results highlight glia as a final common pathway directing neuroprotection versus neurodegeneration. Such recognition of endogenous glial protective pathways may provide a new insight and may contribute to the development of novel therapeutic treatment strategies for PD and possibly other neurodegenerative disorders.
Asunto(s)
Ambiente , Predisposición Genética a la Enfermedad , Hormonas/metabolismo , Enfermedad de Parkinson/genética , Enfermedad de Parkinson/metabolismo , 1-Metil-4-fenil-1,2,3,6-Tetrahidropiridina/metabolismo , Animales , Encéfalo/crecimiento & desarrollo , Encéfalo/metabolismo , Encéfalo/fisiología , Dopamina/metabolismo , Estrógenos/metabolismo , Glucocorticoides/metabolismo , Humanos , Neuroglía/fisiología , Neuronas/fisiología , Neurotoxinas/metabolismo , Óxido Nítrico Sintasa de Tipo II/metabolismo , Enfermedad de Parkinson/fisiopatologíaRESUMEN
Unconjugated bilirubin (UCB) causes encephalopathy in severely jaundiced neonates by damaging astrocytes and neurons. Astrocytes, which help defend the brain against cytotoxic insults, express the ATP-dependent transporter, multidrug resistance-associated protein 1 (Mrp1), which mediates export of organic anions, probably including UCB. We therefore studied whether exposure to UCB affects the expression and intracellular localization of Mrp1 in cultured mouse astroglial cells (>95% astrocytes). Mrp1 was localized and quantitated by confocal laser scanning microscopy and double immunofluorescence labeling by using specific antibodies against Mrp1 and the astrocyte marker glial fibrillary acidic protein, plus the Golgi marker wheat germ agglutinin (WGA). In unexposed astrocytes, Mrp1 colocalized with WGA in the Golgi apparatus. Exposure to UCB at a low unbound concentration (Bf) of 40 nM caused rapid redistribution of Mrp1 from the Golgi throughout the cytoplasm to the plasma membrane, with a peak 5-fold increase in Mrp1 immunofluorescence intensity from 30 to 120 min. Bf above aqueous saturation produced a similar but aborted response. Exposure to this higher Bf for 16 h markedly decreased Trypan blue exclusion and methylthiazoletetrazoilum activity and increased apoptosis 5-fold by terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling assay. These toxic effects were modestly increased by inhibition of Mrp1 activity with 3-([3-(2-[7-chloro-2-quinolinyl]ethenyl)phenyl-(3-dimethylamino-3-oxopropyl)-thio-methyl]thio)propanoic acid (MK571). By contrast, Bf=40 nM caused injury only if Mrp1 activity was inhibited by MK571, which also blocked translocation of Mrp1. Our conclusion is that in astrocytes, UCB up-regulates expression of Mrp1 and promotes its trafficking from the Golgi to the plasma membrane, thus moderating cytotoxicity from UCB, presumably by limiting its intracellular accumulation.
Asunto(s)
Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/genética , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/metabolismo , Astrocitos/citología , Bilirrubina/fisiología , Regulación de la Expresión Génica/fisiología , Miembro 1 de la Subfamilia B de Casetes de Unión a ATP/antagonistas & inhibidores , Animales , Animales Recién Nacidos , Astrocitos/efectos de los fármacos , Astrocitos/patología , Bilirrubina/toxicidad , Encéfalo/citología , Membrana Celular/fisiología , Membrana Celular/ultraestructura , Células Cultivadas , Regulación de la Expresión Génica/efectos de los fármacos , Aparato de Golgi/fisiología , Aparato de Golgi/ultraestructura , Antagonistas de Leucotrieno/farmacología , Ratones , Propionatos/farmacología , Transporte de Proteínas , Quinolinas/farmacologíaRESUMEN
Glucocorticoids (GCs) exert via glucocorticoid receptors (GRs) potent anti-inflammatory and immunosuppressive effects. Emerging evidence indicates that an inflammatory process is involved in dopaminergic nigro-striatal neuronal loss in Parkinson's disease. We here report that the GR deficiency of transgenic (Tg) mice expressing GR antisense RNA from early embryonic life has a dramatic impact in "programming" the vulnerability of dopaminergic neurons to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The GR deficiency of Tg mice exacerbates MPTP-induced toxicity to dopaminergic neurons, as revealed by both severe loss of tyrosine hydroxylase positive nigral neurons and sharp decreases in striatal levels of dopamine and its metabolites. In addition, the late increase in dopamine oxidative metabolism and ascorbic acid oxidative status in GR-deficient mice was far greater than in wild-type (Wt) mice. Inducible nitric oxide synthase (iNOS) was sharply increased in activated astrocytes, macrophages/microglia of GR-deficient as compared with Wt mice. Moreover, GR-deficient microglia produced three- to fourfold higher nitrite levels than Wt mice; these increases preceded the loss of dopaminergic function and were resistant to GR the inhibitory effect of GC, pointing to peroxynitrites as candidate neurotoxic effectors. The iNOS inhibitor N6-(1-iminoethyl)-L-lysine normalized vulnerability of Tg mice, thus establishing a novel link between genetic impairment of GR function and vulnerability to MPTP.