RESUMEN

Abnormal tau accumulation is the hallmark of several neurodegenerative diseases, named tauopathies. Strategies aimed at reducing tau in the brain are promising therapeutic interventions, yet more precise therapies would require targeting specific nuclei and neuronal subpopulations affected by disease while avoiding global reduction of physiological tau. Here, we developed artificial microRNAs directed against the human MAPT mRNA to dwindle tau protein by engaging the endogenous RNA interference pathway. In human differentiated neurons in culture, microRNA-mediated tau reduction diminished neuronal firing without affecting neuronal morphology or impairing axonal transport. In the htau mouse model of tauopathy, we locally expressed artificial microRNAs in the prefrontal cortex (PFC), an area particularly vulnerable to initiating tau pathology in this model. Tau knockdown prevented the accumulation of insoluble and hyperphosphorylated tau, modulated firing activity of putative pyramidal neurons, and improved glucose uptake in the PFC. Moreover, such tau reduction prevented cognitive decline in aged htau mice. Our results suggest target engagement of designed tau-microRNAs to effectively reduce tau pathology, providing a proof of concept for a potential therapeutic approach based on local tau knockdown to rescue tauopathy-related phenotypes.

Asunto(s)

MicroARNs , Tauopatías , Ratones , Humanos , Animales , Anciano , Proteínas tau/genética , Proteínas tau/metabolismo , MicroARNs/genética , MicroARNs/metabolismo , Tauopatías/genética , Tauopatías/terapia , Tauopatías/metabolismo , Neuronas/metabolismo , Fenotipo , Ratones Transgénicos , Modelos Animales de Enfermedad

RESUMEN

Alzheimer's disease (AD) is the most prevalent aging-associated neurodegenerative disease, with a higher incidence in women than men. There is evidence that sex hormone replacement therapy, particularly estrogen, reduces memory loss in menopausal women. Neurofibrillary tangles are associated with tau protein aggregation, a characteristic of AD and other tauopathies. In this sense, autophagy is a promising cellular process to remove these protein aggregates. This study evaluated the autophagy mechanisms involved in neuroprotection induced by 17ß-estradiol (E2) in a Tet-On inducible expression tauopathy cell model (EGFP-tau WT or with the P301L mutation, 0N4R isoform). The results indicated that 17ß-estradiol induces autophagy by activating AMPK in a concentration-dependent manner, independent of mTOR signals. The estrogen receptor α (ERα) agonist, PPT, also induced autophagy, while the ERα antagonist, MPP, substantially attenuated the 17ß-estradiol-mediated autophagy induction. Notably, 17ß-estradiol increased LC3-II levels and phosphorylated and total tau protein clearance in the EGFP-tau WT cell line but not in EGPF-tau P301L. Similar results were observed with E2-BSA, a plasma membrane-impermeable estrogen, suggesting membrane ERα involvement in non-genomic estrogenic pathway activation. Furthermore, 17ß-estradiol-induced autophagy led to EGFP-tau protein clearance. These results demonstrate that modulating autophagy via the estrogenic pathway may represent a new therapeutic target for treating AD.

Asunto(s)

Enfermedad de Alzheimer , Enfermedades Neurodegenerativas , Tauopatías , Proteínas Quinasas Activadas por AMP , Autofagia , Estradiol/farmacología , Receptor alfa de Estrógeno/metabolismo , Estrógenos/farmacología , Femenino , Humanos , Masculino , Agregado de Proteínas , Receptores de Estrógenos , Serina-Treonina Quinasas TOR , Proteínas tau/metabolismo

RESUMEN

Schistosomiasis, a neglected tropical disease caused by trematodes of the Schistosoma genus, affects over 250 million people around the world. This disease has been associated with learning and memory deficits in children, whereas reduced attention levels, impaired work capacity, and cognitive deficits have been observed in adults. Strongly correlated with poverty and lack of basic sanitary conditions, this chronic endemic infection is common in Africa, South America, and parts of Asia and contributes to inhibition of social development and low quality of life in affected areas. Nonetheless, studies on the mechanisms involved in the neurological impairment caused by schistosomiasis are scarce. Here, we used a murine model of infection with Schistosoma mansoni in which parasites do not invade the central nervous system to evaluate the consequences of systemic infection on neurologic function. We observed that systemic infection with S. mansoni led to astrocyte and microglia activation, expression of oxidative stress-induced transcription factor Nrf2, oxidative damage, Tau phosphorylation, and amyloid-ß peptide accumulation in the prefrontal cortex of infected animals. We also found impairment in spatial learning and memory as evaluated by the Morris water maze task. Administration of anthelmintic (praziquantel) and antioxidant (N-acetylcysteine plus deferoxamine) treatments was effective in inhibiting most of these phenotypes, and the combination of both treatments had a synergistic effect to prevent such changes. These data demonstrate new perspectives toward the understanding of the pathology and possible therapeutic approaches to counteract long-term effects of systemic schistosomiasis on brain function.

Asunto(s)

Astrocitos/patología , Microglía/patología , Enfermedades Neurodegenerativas/patología , Schistosoma mansoni/aislamiento & purificación , Esquistosomiasis mansoni/complicaciones , Acetilcisteína/farmacología , Animales , Antihelmínticos/farmacología , Astrocitos/efectos de los fármacos , Astrocitos/metabolismo , Deferoxamina/farmacología , Modelos Animales de Enfermedad , Depuradores de Radicales Libres/farmacología , Masculino , Ratones , Microglía/efectos de los fármacos , Microglía/metabolismo , Prueba del Laberinto Acuático de Morris/efectos de los fármacos , Enfermedades Neurodegenerativas/tratamiento farmacológico , Enfermedades Neurodegenerativas/etiología , Praziquantel/farmacología , Schistosoma mansoni/efectos de los fármacos , Schistosoma mansoni/metabolismo , Esquistosomiasis mansoni/parasitología , Esquistosomiasis mansoni/patología , Sideróforos/farmacología

RESUMEN

Tau is a microtubule-associated protein (MAP) responsible for controlling the stabilization of microtubules in neurons. Tau function is regulated by phosphorylation. However, in some neurological diseases Tau becomes aberrantly hyperphosphorylated, which contributes to the pathogenesis of neurological diseases, known as tauopathies. Western blotting (WB) has been widely employed to determine Tau levels in neurological disease models. However, Tau quantification by WB should be interpreted with care, as this approach has been recognized as prone to produce artifactual results if not properly performed. In the present study, our goal was to evaluate the influence of a freeze-and-thaw cycle, a common procedure preceding WB, to the integrity of Tau in brain homogenates from rats, 3xTg-AD mice and human samples. Homogenates were prepared in ice-cold RIPA buffer supplemented with protease/phosphatase inhibitors. Immediately after centrifugation, an aliquot of the extracts was analyzed via WB to quantify total and phosphorylated Tau levels. The remaining aliquots of the same extracts were stored for at least 2 weeks at either -20 or -80°C and then subjected to WB. Extracts from rodent brains submitted to freeze-and-thaw presented a ∼25 kDa fragment immunoreactive to anti-Tau antibodies. An in-gel digestion followed by mass spectrometry (MS) analysis in excised bands revealed this ∼25 kDa species corresponds to a Tau fragment. Freeze-and-thaw-induced Tau proteolysis was detected even when extracts were stored at -80°C. This phenomenon was not observed in human samples at any storage condition tested. Based on these findings, we strongly recommend the use of fresh extracts of brain samples in molecular analysis of Tau levels in rodents.

Asunto(s)

Enfermedad de Alzheimer/metabolismo , Encéfalo/metabolismo , Criopreservación/métodos , Proteínas tau/metabolismo , Enfermedad de Alzheimer/patología , Animales , Encéfalo/patología , Humanos , Inmunohistoquímica/métodos , Proteolisis , Ratas , Ratas Wistar , Proteínas tau/toxicidad

RESUMEN

Alzheimer's disease (AD) is characterized by amyloid (A)ß peptide accumulation and intracellular neurofibrillary tangles. New hypotheses have suggested that AD involves neuroinflammation and oxidative stress. Gold nanoparticles (AuNP) presents anti-inflammatory and antioxidant characteristics. The present study evaluated the AuNP treatment on an AD model (okadaic acid, OA). Male Wistar rats were injected intracerebroventricularly with OA (100 µg); 24 h later they were treated with 20-nm AuNP (at a dose 2.5 mg/kg) every 48 h for 21 days. The following groups were separated (n = 12/group): Sham, AuNP, OA, and OA + AuNP. OA increases Tau phosphorylation in the cortex and hippocampus, while AuNP treatment maintained it as normal. Spatial memory was impaired by OA, and AuNP treatment prevented this deficit. Neurotrophic factors (BDNF and NGF- ß) in the cortex and hippocampus were decreased by OA. The OA and OA + AuNP groups showed increased interleukin (IL)-1 ß in the hippocampus and cortex, and the AuNP group showed increased IL-1 ß in the hippocampus. In both groups, S100 levels in the cortex and hippocampus were increased by OA. IL-4 was increased in OA + AuNP animals. AuNPs prevented oxidative stress (sulfhydryl and nitrite levels) in brain structures induced by OA. Moreover, OA modulated ATP synthase activity, and AuNP maintained normal brain mitochondrial function. The antioxidant capacities were reduced by OA, and AuNP restored antioxidant status (SOD, catalase activities and GSH levels) on brain. OA-induced damage on brain tissues, and long-term AuNP treatment prevented the neuroinflammation, modulation of mitochondrial function, and impaired cognition induced by AD model, showing that AuNPs may be a promising treatment for neurodisease caused by these elements.

Asunto(s)

Enfermedad de Alzheimer/tratamiento farmacológico , Lesiones Encefálicas/tratamiento farmacológico , Oro/farmacología , Nanopartículas del Metal , Péptidos beta-Amiloides/farmacología , Animales , Antioxidantes/farmacología , Encéfalo/efectos de los fármacos , Disfunción Cognitiva/tratamiento farmacológico , Modelos Animales de Enfermedad , Hipocampo/efectos de los fármacos , Masculino , Fármacos Neuroprotectores/farmacología , Ratas Wistar

RESUMEN

The microtubule-associated protein tau regulates myriad neuronal functions, such as microtubule dynamics, axonal transport and neurite outgrowth. Tauopathies are neurodegenerative disorders characterized by the abnormal metabolism of tau, which accumulates as insoluble neuronal deposits. The adult human brain contains equal amounts of tau isoforms with three (3R) or four (4R) repeats of microtubule-binding domains, derived from the alternative splicing of exon 10 (E10) in the tau transcript. Several tauopathies are associated with imbalances of tau isoforms, due to splicing deficits. Here, we used a trans-splicing strategy to shift the inclusion of E10 in a mouse model of tauopathy that produces abnormal excess of 3R tau. Modulating the 3R/4R ratio in the prefrontal cortex led to a significant reduction of pathological tau accumulation concomitant with improvement of neuronal firing and reduction of cognitive impairments. Our results suggest promising potential for the use of RNA reprogramming in human neurodegenerative diseases.

Asunto(s)

Tauopatías/patología , Proteínas tau/metabolismo , Empalme Alternativo , Animales , Modelos Animales de Enfermedad , Exones , Masculino , Ratones , Corteza Prefrontal/metabolismo , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , ARN Mensajero/metabolismo , Tauopatías/metabolismo , Proteínas tau/genética

RESUMEN

Tauopathies are a major group of neurodegenerative proteinopathies characterized by the accumulation of abnormal and hyperphosphorylated tau proteins in the brain. Tau pathology is characterized as 3R (repeat) or 4R predominant or mixed 3R and 4R type. Here we report three cases lacking mutations in the microtubule associated protein tau (MAPT) gene with unusual tau pathology. The age at onset and duration of illness, respectively, were 63 and 20 years (male), 67 and 5 years (female) and 72 and 20 years (female). The clinical presentation was compatible with a diagnosis of progressive supranuclear palsy (PSP) in two subjects and with cognitive decline in all three subjects. Common neuropathological features included neuronal loss in the hippocampus and dentate gyrus associated with spherical basophilic Pick body-like inclusions showing 4R tau immunoreactivity, which was supported by the detection of predominantly 4R tau species by Western blot examination. In addition, accumulation of tau immunoreactive argyrophilic astrocytes in the hippocampus and amygdala and oligodendroglial coiled bodies in the hippocampal white matter were observed. These morphologies appeared in combination with Alzheimer disease-related pathology and subcortical tau pathology compatible with PSP. Together with a single case report in the literature, our observations on these three cases expand the spectrum of previously described tauopathies. We suggest that this tauopathy variant with hippocampal 4R tau immunoreactive spherical inclusions might contribute to the cognitive deficits in the patients reported here. The precise definition of the clinicopathological relevance of these unusual tau pathologies merits further study.

Asunto(s)

Hipocampo/metabolismo , Hipocampo/patología , Cuerpos de Inclusión/metabolismo , Cuerpos de Inclusión/patología , Tauopatías/metabolismo , Tauopatías/patología , Anciano , Anciano de 80 o más Años , Disfunción Cognitiva/diagnóstico , Disfunción Cognitiva/genética , Disfunción Cognitiva/metabolismo , Disfunción Cognitiva/patología , Resultado Fatal , Femenino , Humanos , Masculino , Fenotipo , Tauopatías/diagnóstico , Tauopatías/genética , Proteínas tau/metabolismo

RESUMEN

Argyrophilic grain disease (AGD) is a frequent late-onset, 4-repeat tauopathy reported in Caucasians with high educational attainment. Little is known about AGD in non-Caucasians or in those with low educational attainment. We describe AGD demographics, clinical, and neuropathological features in a multiethnic cohort of 983 subjects ≥50 years of age from São Paulo, Brazil. Clinical data were collected through semistructured interviews with an informant and included in the Informant Questionnaire on Cognitive Decline in the Elderly, the Clinical Dementia Rating, and the Neuropsychiatric Inventory. Neuropathologic assessment relied on internationally accepted criteria. AGD was frequent (15.2%) and was the only neuropathological diagnosis in 8.9% of all cases (mean, 78.9 ± 9.4 years); it rarely occurred as an isolated neuropathological finding. AGD was associated with older age, lower socioeconomic status (SES), and appetite disorders. This is the first study of demographic, clinical, and neuropathological aspects of AGD in different ethnicities and subjects from all socioeconomic strata. The results suggest that prospective studies of AGD patients include levels of hormones related to appetite control as possible antemortem markers. Moreover, understanding the mechanisms behind higher susceptibility to AGD of low SES subjects may disclose novel environmental risk factors for AGD and other neurodegenerative diseases.

Asunto(s)

Demografía , Tauopatías/epidemiología , Tauopatías/patología , Anciano , Anciano de 80 o más Años , Autopsia , Brasil/epidemiología , Demografía/métodos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Enfermedades Neurodegenerativas/epidemiología , Enfermedades Neurodegenerativas/patología , Enfermedades Neurodegenerativas/psicología , Tauopatías/psicología

RESUMEN

Inclusions of phosphorylated tau (p-tau) are a hallmark of many neurodegenerative disorders classified as "tauopathy," of which Alzheimer's disease is the most prevalent form. Dysregulation of tau phosphorylation disrupts neuron structure and function, and hyperphosphorylated tau aggregates to form neurotoxic inclusions. The abundance of ubiquitin in tau inclusions suggests a defect in ubiquitin-mediated tau protein degradation by the proteasome. Under the temperature of 37 °C, the co-chaperone BAG2 protein targets phosphorylated tau for degradation via by a more-efficient, ubiquitin-independent pathway. In both in vivo and in vitro studies, cold exposure induces the accumulation of phosphorylated tau protein. The SH-SY5Y cell line differentiates into neuron-like cells on treatment with retinoic acid and is an established model for research on the effects of cold on tau phosphorylation. The aim of the present study was to investigate whether BAG2 mediates the cold-induced accumulation of phosphorylated tau protein. Our findings show that cold exposure causes a decrease in BAG2 expression in undifferentiated cells. Conversely, BAG2 expression is increased in differentiated cells exposed to cold. Further, undifferentiated cells exposed to cold had an increased proportion of p-tau to total tau, suggesting an accumulation of p-tau that is consistent with decreased levels of BAG2. Overexpression of BAG2 in cold-exposed undifferentiated cells restored levels of p-tau to those of 37 °C undifferentiated control. Interestingly, although BAG2 expression increased in differentiated cells, this increase was not accompanied by a decrease in the proportion of p-tau to total tau. Further, overexpression of BAG2 in cold exposed differentiated cells showed no significant difference in p-tau levels compared to 37 °C controls. Taken together, these data show that expression of BAG2 is differently regulated in a differentiation-dependent context. Our results suggest that repression of BAG2 expression or BAG2 activity by cold-sensitive pathways, as modeled in undifferentiated and differentiated cells, respectively, may be a causal factor in the accumulation of cytotoxic hyperphosphorylated tau protein via restriction of BAG2-mediated clearance of cellular p-tau.

Asunto(s)

Frío , Chaperonas Moleculares/metabolismo , Proteínas tau/metabolismo , Diferenciación Celular , Línea Celular Tumoral , Forma de la Célula , Supervivencia Celular , Regulación Neoplásica de la Expresión Génica , Humanos , Chaperonas Moleculares/genética , Fosforilación , ARN Mensajero/genética , ARN Mensajero/metabolismo

RESUMEN

Alzheimer's disease (AD) and cerebral ischemia (CI) are neuropathologies that are characterized by aggregates of tau protein, a hallmark of cognitive disorder and dementia. Protein accumulation can be induced by autophagic failure. Autophagy is a metabolic pathway involved in the homeostatic recycling of cellular components. However, the role of autophagy in those tauopathies remains unclear. In this study, we performed a comparative analysis to identify autophagy related markers in tauopathy generated by AD and CI during short-term, intermediate, and long-term progression using the 3xTg-AD mouse model (aged 6,12, and 18 months) and the global CI 2-VO (2-Vessel Occlusion) rat model (1,15, and 30 days post-ischemia). Our findings confirmed neuronal loss and hyperphosphorylated tau aggregation in the somatosensory cortex (SS-Cx) of the 3xTg-AD mice in the late stage (aged 18 months), which was supported by a failure in autophagy. These results were in contrast to those obtained in the SS-Cx of the CI rats, in which we detected neuronal loss and tauopathy at 1 and 15 days post-ischemia, and this phenomenon was reversed at 30 days. We proposed that this phenomenon was associated with autophagy induction in the late stage, since the data showed a decrease in p-mTOR activity, an association of Beclin-1 and Vps34, a progressive reduction in PHF-1, an increase in LC3B puncta and autophago-lysosomes formation were observed. Furthermore, the survival pathways remained unaffected. Together, our comparative study suggest that autophagy could ameliorates tauopathy in CI but not in AD, suggesting a differential temporal approach to the induction of neuroprotection and the prevention of neurodegeneration.

RESUMEN

Alzheimer's disease (AD) is the most common senile dementia in the world. Although important progress has been made in understanding the pathogenesis of AD, current therapeutic approaches provide only modest symptomatic relief. In this study, we evaluated the neuroprotective effect of quercetin (25 mg/kg) administration via i.p. injection every 48 h for 3 months on aged (21-24 months old) triple transgenic AD model (3xTg-AD) mice. Our data show that quercetin decreases extracellular ß-amyloidosis, tauopathy, astrogliosis and microgliosis in the hippocampus and the amygdala. These results were supported by a significant reduction in the paired helical filament (PHF), ß-amyloid (ßA) 1-40 and ßA 1-42 levels and a decrease in BACE1-mediated cleavage of APP (into CTFß). Additionally, quercetin induced improved performance on learning and spatial memory tasks and greater risk assessment behavior based on the elevated plus maze test. Together, these findings suggest that quercetin reverses histological hallmarks of AD and protects cognitive and emotional function in aged 3xTg-AD mice.

Asunto(s)

Enfermedad de Alzheimer/tratamiento farmacológico , Enfermedad de Alzheimer/patología , Antioxidantes/uso terapéutico , Encéfalo/patología , Trastornos del Conocimiento/prevención & control , Trastornos del Humor/prevención & control , Quercetina/uso terapéutico , Envejecimiento , Enfermedad de Alzheimer/complicaciones , Enfermedad de Alzheimer/genética , Péptidos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/genética , Animales , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Trastornos del Conocimiento/etiología , Modelos Animales de Enfermedad , Esquema de Medicación , Gliosis/etiología , Gliosis/prevención & control , Aprendizaje por Laberinto/efectos de los fármacos , Ratones , Ratones Transgénicos , Trastornos del Humor/etiología , Proteínas del Tejido Nervioso/metabolismo , Neuroglía/patología , Presenilina-1/genética , Tiempo de Reacción/efectos de los fármacos , Tiempo de Reacción/genética , Proteínas tau/genética

RESUMEN

Alzheimer's disease (AD), the most common dementia in the elderly, is characterized by cognitive impairment and severe autonomic symptoms such as disturbance in core body temperature (Tc), which may be predictors or early events in AD onset. Inclusions of phosphorylated Tau (p-Tau) are a hallmark of AD and other neurodegenerative disorders called "Tauopathies." Animal and human studies show that anesthesia augments p-Tau levels through reduction of Tc, with implications for AD. Additionally, hypothermia impairs memory and cognitive function. The molecular networks related to Tc that are associated with AD remain poorly characterized. Under physiological conditions, Tau binds microtubules, promoting their assembly and stability. The dynamically regulated Tau-microtubule interaction plays an important role in structural remodeling of the cytoskeleton, having important functions in neuronal plasticity and memory in the hippocampus. Hypothermia-induced increases in p-Tau levels are significant, with an 80% increase for each degree Celsius below normothermic conditions. Although the effects of temperature on Tau phosphorylation are evident, its effects on p-Tau degradation remain poorly understoodWe review information concerning the mechanisms of Tau regulation of neuron plasticity via its effects on microtubule dynamics, with focus on pathways regulating the abundance of phosphorylated Tau species.  We highlight the effects of temperature on molecular mechanisms influencing the development of Tau-related diseases. Specifically, we argue that cold might preferentially affects central nervous system structures that are highly reliant upon plasticity, such as the hippocampus, and that the effect of cold on Tau phosphorylation may constitute a pathology-initiating trigger leading to neurodegeneration.

RESUMEN

ß-site APP cleaving enzyme 1 (BACE1) initiates APP cleavage, which has been reported to be an inducer of tau pathology by altering proteasome functions in Alzheimer's disease (AD). However, the exact relationship between BACE1 and PHF (Paired Helical Filaments) formation is not clear. In this study, we confirm that BACE1 and Hsc70 are upregulated in the brains of AD patients, and we demonstrate that both proteins show enhanced expression in lipid rafts from AD-affected triple transgenic mouse brains. BACE1 targeting increased Hsc70 levels in the membrane and cytoplasm fractions and downregulated Hsp90 and CHIP in the nucleus in the hippocampi of 3xTg-AD mice. However, these observations occurred in a proteasome-independent manner in vitro. The BACE1miR-induced reduction of soluble hyperphosphorylated tau was associated with a decrease in MAPK activity. However, the BACE1 RNAi-mediated reduction of hyperphosphorylated tau was only blocked by 3-MA (3-methyladenine) in vitro, and it resulted in the increase of Hsc70 and LAMP2 in lipid rafts from hippocampi of 3xTg-AD mice, and upregulation of survival and homeostasis signaling. In summary, our findings suggest that BACE1 silencing neuroprotects reducing soluble hyperphosphorylated tau, modulating certain autophagy-related proteins in aged 3xTg-AD mice.

RESUMEN

Alzheimer's disease (AD) is the most common cause of dementia worldwide. One of the main pathological changes that occurs in AD is the intracellular accumulation of hyperphosphorylated Tau protein in neurons. Cyclin-dependent kinase 5 (CDK5) is one of the major kinases involved in Tau phosphorylation, directly phosphorylating various residues and simultaneously regulating various substrates such as kinases and phosphatases that influence Tau phosphorylation in a synergistic and antagonistic way. It remains unknown how the interaction between CDK5 and its substrates promotes Tau phosphorylation, and systemic approaches are needed that allow an analysis of all the proteins involved. In this review, the role of the CDK5 signaling pathway in Tau hyperphosphorylation is described, an in silico model of the CDK5 signaling pathway is presented. The relationship among these theoretical and computational models shows that the regulation of Tau phosphorylation by PP2A and glycogen synthase kinase 3ß (GSK3ß) is essential under basal conditions and also describes the leading role of CDK5 under excitotoxic conditions, where silencing of CDK5 can generate changes in these enzymes to reverse a pathological condition that simulates AD.

RESUMEN

Both genetic and environmental factors likely contribute to the neuropathology of tauopathies, but it remains unclear how specific genetic backgrounds affect the susceptibility towards environmental toxins. Mutations in the tau gene have been associated with familial tauopathies, while annonacin, a plant-derived mitochondrial inhibitor, has been implicated in an environmental form of tauopathy. We therefore determined whether there was a pathogenic synergy between annonacin exposure and the expression of the R406W-tau mutation in transgenic mice. We found that annonacin exposure caused an increase in the number of neurons with phosphorylated tau in the somatodendritic compartment in several brain areas in R406W(+/+) mice as opposed to mice that had only the endogenous mouse tau (R406W(-/-)). Western blot analysis demonstrated a concomitant increase in total tau protein without increase in tau mRNA, but reduced proteasomal proteolytic activity in R406W(+/+), but not R406W(-/-) mice, upon annonacin-treatment. Phosphorylated tau levels exceeded the increase in total tau protein, along with increased levels of different tau kinases, foremost a striking increase in the p25/p35 ratio, known to activate the tau kinase Cdk5. In summary, we observed a synergistic interaction between annonacin exposure and the presence of the R406W-tau mutation, which resulted in reduced degradation, increased phosphorylation and redistribution of neuronal tau.

Asunto(s)

Encéfalo/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Furanos/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica/genética , Lactonas/farmacología , Proteínas tau/genética , Animales , Arginina/genética , Encéfalo/metabolismo , Relación Dosis-Respuesta a Droga , Humanos , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Microglía/efectos de los fármacos , Proteínas Asociadas a Microtúbulos/metabolismo , Mitocondrias/genética , Mitocondrias/metabolismo , Mortalidad , Mutación/genética , Neuronas/efectos de los fármacos , Fosforilación/efectos de los fármacos , Fosforilación/genética , Triptófano/genética

RESUMEN

Progressive supranuclear palsy (PSP) is a distinctive form of neurodegenerative disease which affects the brainstem and basal ganglia. Patients present supranuclear ophthalmoplegia, postural instability and mild dementia. PSP is defined neuropathologically by the accumulation of neurofibrillary tangles in the subthalamic nucleus, pallidum, red nucleus, substantia nigra, striatum, pontine tegmentum, oculomotor nucleus, medulla and dentate nucleus. Over the last decade many lines of investigations have helped refine PSP in many aspects and it is the purpose of this review to help neurologists identify PSP, to better understand its pathophysiology and to provide a more focused, symptom-based treatment approach.

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A paralisia supranuclear progressiva (PSP) é uma doença neurodegenerativa, que afeta principalmente o tronco cerebral e os núcleos da base. O quadro clínico se caracteriza por oftalmoparesia supranuclear, instabilidade postural e demência . Do ponto de vista anátomo-patológico, a PSP se caracteriza por acúmulo de emaranhados neurofibrilares no núcleo subtalâmico, globo pálido, núcleo rubro, substância negra, estriado, tegumento da ponte, núcleos oculomotores, bulbo e núcleo denteado. Nas últimas décadas, muitas linhas de pesquisa têm colaborado para redefinir a PSP em muitos aspectos. Os objetivos dessa revisão são auxiliar o neurologista geral na identificação da doença, compreensão da sua fisiopatologia, além de apresentar alternativas para seu tratamento sintomático.

Asunto(s)

Humanos , Parálisis Supranuclear Progresiva , Parálisis Supranuclear Progresiva/clasificación , Parálisis Supranuclear Progresiva/diagnóstico , Parálisis Supranuclear Progresiva/fisiopatología , Parálisis Supranuclear Progresiva/terapia