RESUMEN
In Alzheimer disease, the development of tau pathology follows neuroanatomically connected pathways, suggesting that abnormal tau species might recruit normal tau by passage from cell to cell. Herein, we analyzed the effect of stereotaxic brain injection of human Alzheimer high-molecular-weight paired helical filaments (PHFs) in the dentate gyrus of wild-type and mutant tau THY-Tau22 mice. After 3 months of incubation, wild-type and THY-Tau22 mice developed an atrophy of the dentate gyrus and a tau pathology characterized by Gallyas and tau-positive grain-like inclusions into granule cells that extended in the hippocampal hilus and eventually away into the alveus, and the fimbria. Gallyas-positive neuropil threads and oligodendroglial coiled bodies were also observed. These tau inclusions were composed only of mouse tau, and were immunoreactive with antibodies to 4R tau, phosphotau, misfolded tau, ubiquitin, and p62. Although local hyperphosphorylation of tau was increased in the dentate gyrus in THY-Tau22 mice, the development of neurofibrillary tangles made of mutant human tau was not accelerated in the hippocampus, indicating that wild-type human PHFs were inefficient in seeding tau aggregates made of G272V/P301S mutant human tau. Our results indicate thus that injection of human wild-type Alzheimer PHF seeded aggregation of wild-type murine tau into an argyrophilic 4R tau pathology, and constitutes an interesting model independent of expression of a mutant tau protein.
Asunto(s)
Enfermedad de Alzheimer/patología , Citoesqueleto/patología , Ovillos Neurofibrilares/patología , Proteínas tau/metabolismo , Anciano , Anciano de 80 o más Años , Enfermedad de Alzheimer/metabolismo , Animales , Conducta Animal , Encéfalo/metabolismo , Encéfalo/patología , Células CHO , Cricetulus , Citoesqueleto/metabolismo , Modelos Animales de Enfermedad , Femenino , Hipocampo/metabolismo , Hipocampo/patología , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Ovillos Neurofibrilares/metabolismo , Isoformas de Proteínas , Proteínas tau/genéticaRESUMEN
Single nucleotide polymorphisms in PICALM, a key component of clathrin-mediated endocytosis machinery, have been identified as genetic susceptibility loci for late onset Alzheimer's disease (LOAD). We previously reported that PICALM protein levels were decreased in AD brains and that PICALM was co-localised with neurofibrillary tangles in LOAD, familial AD with PSEN1 mutations and Down syndrome. In the present study, we analysed PICALM expression, cell localisation and association with pathological cellular inclusions in other tauopathies and in non-tau related neurodegenerative diseases. We observed that PICALM was associated with neuronal tau pathology in Pick disease and in progressive supranuclear palsy (PSP) and co-localised with both 3R and 4R tau positive inclusions unlike in corticobasal degeneration (CBD) or in frontotemporal lobar degeneration (FTLD)-MAPT P301L. PICALM immunoreactivities were not detected in tau-positive tufted astrocytes in PSP, astrocytic plaques in CBD, Lewy bodies in Lewy body disease, diffuse type (LBD) and in TDP-43-positive inclusions in FTLD. In the frontal cortex in tauopathies, the ratio of insoluble to soluble PICALM was increased while the level of soluble PICALM was decreased and was inversely correlated with the level of phosphotau. PICALM decrease was also significantly correlated with increased LC3-II and decreased Beclin-1 levels in tauopathies and in non-tau related neurodegenerative diseases. These results suggest that there is a close relationship between abnormal PICALM processing, tau pathology and impairment of autophagy in human neurodegenerative diseases.
Asunto(s)
Enfermedad de Alzheimer/metabolismo , Proteínas Relacionadas con la Autofagia/metabolismo , Clatrina/metabolismo , Endocitosis/fisiología , Proteínas de Ensamble de Clatrina Monoméricas/metabolismo , Enfermedad de Pick/metabolismo , Neumotórax/metabolismo , Proteínas tau/metabolismo , Encéfalo/metabolismo , Degeneración Lobar Frontotemporal/metabolismo , Humanos , Ovillos Neurofibrilares/metabolismo , Neuronas/metabolismo , Fosforilación , Parálisis Supranuclear Progresiva/metabolismo , Tauopatías/patologíaRESUMEN
Neurofibrillary degeneration in transgenic models of tauopathies has been observed to be enhanced when these models are crossed with transgenic models developing an Aß pathology. The mechanisms leading to this enhanced tau pathology are not well understood. We have performed a detailed analysis of tau misprocessing in a new transgenic mouse model combining APP, PS1 and tau mutations (5xFAD×Tg30 mice) by comparison with littermates expressing only a FTD mutant tau (Tg30 mice). These 5xFAD×Tg30 mice showed a more severe deficient motor phenotype than Tg30 mice and developed with age a dramatically accelerated NFT load in the brain compared to Tg30 mice. Insoluble tau in 5xFAD×Tg30 mice compared to insoluble tau in Tg30 mice showed increased phosphorylation, enhanced misfolding and truncation changes mimicking more closely the post-translational changes characteristic of PHF-tau in Alzheimer's disease. Endogenous wild-type mouse tau was recruited at much higher levels in insoluble tau in 5xFAD×Tg30 than in Tg30 mice. Extracellular amyloid load, Aß40 and Aß42, ß-CTFs and ß-CTF phosphorylation levels were lower in 5xFAD×Tg30 mice than in 5xFAD mice. Despite this reduction of Aß, a significant hippocampal neuronal loss was observed in 5xFAD×Tg30 but not in 5xFAD mice indicating its closer association with increased tau pathology. This 5xFAD×Tg30 model thus mimics more faithfully tau pathology and neuronal loss observed in AD and suggests that additional post-translational changes in tau and self-recruitment of endogenous tau drive the enhanced tau pathology developing in the presence of Aß pathology.
Asunto(s)
Precursor de Proteína beta-Amiloide/genética , Corteza Cerebral/ultraestructura , Placa Amiloide/ultraestructura , Presenilina-1/genética , Proteínas tau/genética , Proteínas tau/metabolismo , Factores de Edad , Precursor de Proteína beta-Amiloide/metabolismo , Animales , Hipocampo/ultraestructura , Ratones , Ratones Endogámicos C57BL , Ratones Mutantes , Ratones Transgénicos , Fosforilación , Presenilina-1/metabolismo , Pliegue de Proteína , Células Piramidales/patología , Médula Espinal/metabolismo , Médula Espinal/patología , Tasa de Supervivencia , Proteínas tau/químicaRESUMEN
Lack of tau expression has been reported to protect against excitotoxicity and to prevent memory deficits in mice expressing mutant amyloid precursor protein (APP) identified in familial Alzheimer disease. In APP mice, mutant presenilin 1 (PS1) enhances generation of Aß42 and inhibits cell survival pathways. It is unknown whether the deficient phenotype induced by concomitant expression of mutant PS1 is rescued by absence of tau. In this study, we have analyzed the effect of tau deletion in mice expressing mutant APP and PS1. Although APP/PS1/tau(+/+) mice had a reduced survival, developed spatial memory deficits at 6 months and motor impairments at 12 months, these deficits were rescued in APP/PS1/tau(-/-) mice. Neuronal loss and synaptic loss in APP/PS1/tau(+/+) mice were rescued in the APP/PS1/tau(-/-) mice. The amyloid plaque burden was decreased by roughly 50% in the cortex and the spinal cord of the APP/PS1/tau(-/-) mice. The levels of soluble and insoluble Aß40 and Aß42, and the Aß42/Aß40 ratio were reduced in APP/PS1/tau(-/-) mice. Levels of phosphorylated APP, of ß-C-terminal fragments (CTFs), and of ß-secretase 1 (BACE1) were also reduced, suggesting that ß-secretase cleavage of APP was reduced in APP/PS1/tau(-/-) mice. Our results indicate that tau deletion had a protective effect against amyloid induced toxicity even in the presence of mutant PS1 and reduced the production of Aß.
Asunto(s)
Precursor de Proteína beta-Amiloide/metabolismo , Neuronas/metabolismo , Neuronas/patología , Presenilina-1/metabolismo , Procesamiento Proteico-Postraduccional , Proteínas tau/deficiencia , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Precursor de Proteína beta-Amiloide/química , Animales , Ácido Aspártico Endopeptidasas/metabolismo , Muerte Celular , Espinas Dendríticas/patología , Espinas Dendríticas/ultraestructura , Humanos , Memoria a Corto Plazo , Ratones , Ratones Transgénicos , Actividad Motora , Neuroglía/metabolismo , Neuroglía/patología , Neuronas/ultraestructura , Fosforilación , Fosfotreonina/metabolismo , Placa Amiloide/metabolismo , Placa Amiloide/patología , Placa Amiloide/fisiopatología , Solubilidad , Análisis de Supervivencia , Sinapsis/patología , Sinapsis/ultraestructura , Proteínas tau/metabolismoRESUMEN
PICALM, a clathrin adaptor protein, plays important roles in clathrin-mediated endocytosis in all cell types. Recently, genome-wide association studies identified single nucleotide polymorphisms in PICALM gene as genetic risk factors for late-onset Alzheimer disease (LOAD). We analysed by western blotting with several anti-PICALM antibodies the pattern of expression of PICALM in human brain extracts. We found that PICALM was abnormally cleaved in AD samples and that the level of the uncleaved 65-75 kDa full-length PICALM species was significantly decreased in AD brains. Cleavage of human PICALM after activation of endogenous calpain or caspase was demonstrated in vitro. Immunohistochemistry revealed that PICALM was associated in situ with neurofibrillary tangles, co-localising with conformationally abnormal and hyperphosphorylated tau in LOAD, familial AD and Down syndrome cases. PHF-tau proteins co-immunoprecipitated with PICALM. PICALM was highly expressed in microglia in LOAD. These observations suggest that PICALM is associated with the development of AD tau pathology. PICALM cleavage could contribute to endocytic dysfunction in AD.
Asunto(s)
Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/patología , Proteínas de Ensamble de Clatrina Monoméricas/metabolismo , Ovillos Neurofibrilares/metabolismo , Ovillos Neurofibrilares/patología , Adulto , Anciano , Anciano de 80 o más Años , Enfermedad de Alzheimer/etiología , Estudios de Casos y Controles , Síndrome de Down/etiología , Síndrome de Down/metabolismo , Síndrome de Down/patología , Femenino , Humanos , Masculino , Microglía/fisiología , Persona de Mediana Edad , Proteínas tau/metabolismoRESUMEN
Many models of human tauopathies have been generated in mice by expression of a human mutant tau with maintained expression of mouse endogenous tau. Because murine tau might interfere with the toxic effects of human mutant tau, we generated a model in which a pathogenic human tau protein is expressed in the absence of wild-type tau protein, with the aim of facilitating the study of the pathogenic role of the mutant tau and to reproduce more faithfully a human tauopathy. The Tg30 line is a tau transgenic mouse model overexpressing human 1N4R double-mutant tau (P301S and G272V) that develops Alzheimer's disease-like neurofibrillary tangles in an age-dependent manner. By crossing Tg30 mice with mice invalidated for their endogenous tau gene, we obtained Tg30xtau(-/-) mice that express only exogenous human double-mutant 1N4R tau. Although Tg30xtau(-/-) mice express less tau protein compared with Tg30, they exhibit signs of decreased survival, increased proportion of sarkosyl-insoluble tau in the brain and in the spinal cord, increased number of Gallyas-positive neurofibrillary tangles in the hippocampus, increased number of inclusions in the spinal cord, and a more severe motor phenotype. Deletion of murine tau accelerated tau aggregation during aging of this mutant tau transgenic model, suggesting that murine tau could interfere with the development of tau pathology in transgenic models of human tauopathies.
Asunto(s)
Técnicas de Inactivación de Genes , Proteínas Asociadas a Microtúbulos/metabolismo , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Proteínas tau/metabolismo , Animales , Recuento de Células , Glucógeno Sintasa Quinasa 3/metabolismo , Glucógeno Sintasa Quinasa 3 beta , Hipocampo/efectos de los fármacos , Hipocampo/metabolismo , Hipocampo/patología , Humanos , Cuerpos de Inclusión Intranucleares/efectos de los fármacos , Cuerpos de Inclusión Intranucleares/patología , Cuerpos de Inclusión Intranucleares/ultraestructura , Memoria a Corto Plazo/efectos de los fármacos , Ratones , Ratones Transgénicos , Modelos Animales , Actividad Motora/efectos de los fármacos , Ovillos Neurofibrilares/efectos de los fármacos , Ovillos Neurofibrilares/metabolismo , Ovillos Neurofibrilares/patología , Ovillos Neurofibrilares/ultraestructura , Fosforilación/efectos de los fármacos , Procesamiento Proteico-Postraduccional/efectos de los fármacos , Estructura Cuaternaria de Proteína , Sarcosina/análogos & derivados , Sarcosina/farmacología , Nervio Ciático/efectos de los fármacos , Nervio Ciático/patología , Solubilidad/efectos de los fármacos , Médula Espinal/efectos de los fármacos , Médula Espinal/metabolismo , Médula Espinal/patología , Análisis de Supervivencia , Proteínas tau/químicaRESUMEN
Abnormal homeostasis of heavy metals is a well-documented physiopathological mechanism in Alzheimer's disease. An exacerbation of these abnormalities is best illustrated in the amyloid plaques in Alzheimer's disease brain tissue, in which zinc reaches the enormous concentration of 1000 microM. Zinc in the plaques is thought to originate from impaired glutamatergic neurons distributed in the associative cortex and limbic structures of normal brain. Although the characteristics of zinc binding to Abeta and its role in promotion of Abeta aggregation have been intensively studied, the contribution of zinc to the development of tau pathology remains elusive. To further document the effect of zinc we have investigated the modifications of tau phosphorylation, conformation and association to microtubules induced by zinc in clonal cell lines expressing a human tau isoform. A bimodal dose dependent effect of zinc was observed. At 100 microM zinc induced a tau dephosphorylation on the PHF-1 epitope, and at higher zinc concentrations induced the appearance of the abnormal tau conformational epitope MC1 and reduced the electrophoretic mobility of tau, known to be associated to increased tau phosphorylation. High zinc concentrations also increased glycogen synthase kinase-3beta (GSK-3beta) phosphorylation on tyrosine 216, a phosphorylation associated with increased activity of this tau kinase. Live imaging of tau-EGFP expressing cells demonstrated that high zinc concentrations induced a release of tau from microtubules. These results suggest that zinc plays a significant role in the development of tau pathology associated to Alzheimer's disease.
Asunto(s)
Conformación Proteica , Sulfato de Zinc/metabolismo , Proteínas tau/química , Proteínas tau/metabolismo , Animales , Anticuerpos Monoclonales/genética , Anticuerpos Monoclonales/metabolismo , Línea Celular , Epítopos , Glucógeno Sintasa Quinasa 3/antagonistas & inhibidores , Glucógeno Sintasa Quinasa 3/metabolismo , Glucógeno Sintasa Quinasa 3 beta , Homeostasis , Humanos , Indoles/metabolismo , Maleimidas/metabolismo , Microtúbulos/metabolismo , Fosforilación , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Proteínas tau/genéticaRESUMEN
We have reported previously a tau transgenic mouse model (Tg30tau) overexpressing human 4R1N double-mutant tau (P301S and G272V) and that develops AD (Alzheimer's disease)-like NFTs (neurofibrillary tangles) in an age-dependent manner. Since murine tau might interfere with the toxic effects of human mutant tau, we set out to analyse the phenotype of our Tg30tau model in the absence of endogenous murine tau with the aim to reproduce more faithfully a model of human tauopathy. By crossing the Tg30tau line with TauKO (tau-knockout) mice, we have obtained a new mouse line called Tg30xTauKO that expresses only exogenous human double-mutant 4R1N tau. Whereas Tg30xTauKO mice express fewer tau proteins compared with Tg30tau, they exhibit augmented sarkosyl-insoluble tau in the brain and an increased number of Gallyas-positive NFTs in the hippocampus. Taken together, exclusion of murine tau causes accelerated tau aggregation during aging of this mutant tau transgenic model.
Asunto(s)
Modelos Animales de Enfermedad , Eliminación de Gen , Tauopatías/patología , Proteínas tau/genética , Proteínas tau/metabolismo , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/metabolismo , Animales , Precipitación Química , Humanos , Ratones , Ratones Transgénicos , Proteínas Mutantes/metabolismo , Proteínas Mutantes/fisiología , Multimerización de Proteína/genética , Multimerización de Proteína/fisiología , Tauopatías/genética , Tauopatías/metabolismo , Regulación hacia ArribaRESUMEN
Synaptojanin 1 (SYNJ1) is a brain-enriched lipid phosphatase critically involved in autophagosomal/endosomal trafficking, synaptic vesicle recycling and metabolism of phosphoinositides. Previous studies suggest that SYNJ1 polymorphisms have significant impact on the age of onset of Alzheimer's disease (AD) and that SYNJ1 is involved in amyloid-induced toxicity. Yet SYNJ1 protein level and cellular localization in post-mortem human AD brain tissues have remained elusive. This study aimed to examine whether SYNJ1 localization and expression are altered in post-mortem AD brains. We found that SYNJ1 is accumulated in Hirano bodies, plaque-associated dystrophic neurites and some neurofibrillary tangles (NFTs). SYNJ1 immunoreactivity was higher in neurons and in the senile plaques in AD patients carrying one or two ApolipoproteinE (APOE) ε4 allele(s). In two large cohorts of APOE-genotyped controls and AD patients, SYNJ1 transcripts were significantly increased in AD temporal isocortex compared to control. There was a significant increase in SYNJ1 transcript in APOEε4 carriers compared to non-carriers in AD cohort. SYNJ1 was systematically co-enriched with PHF-tau in the sarkosyl-insoluble fraction of AD brain. In the RIPA-insoluble fraction containing protein aggregates, SYNJ1 proteins were significantly increased and observed as a smear containing full-length and cleaved fragments in AD brains. In vitro cleavage assay showed that SYNJ1 is a substrate of calpain, which is highly activated in AD brains. Our study provides evidence of alterations in SYNJ1 mRNA level and SYNJ1 protein degradation, solubility and localization in AD brains.
Asunto(s)
Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/patología , Encéfalo/patología , Monoéster Fosfórico Hidrolasas/metabolismo , Agregación Patológica de Proteínas/patología , Anciano , Apolipoproteínas E/genética , Encéfalo/metabolismo , Calpaína/metabolismo , Células HEK293 , Humanos , Neuronas/metabolismo , Neuronas/patología , Proteínas tau/metabolismoRESUMEN
Astrocytes recruitment and activation are a hallmark of many neurodegenerative diseases including Alzheimer's disease (AD). We have previously observed an overexpression for S100A6 protein, a Ca(2+)/Zn(2+) binding protein presenting more affinity for zinc than for calcium, in amyotrophic lateral sclerosis (ALS). Here we demonstrated in AD patients but also in two different AD mouse models, that astrocytic S100A6 protein was homogeneously up-regulated within the white matter. However, within the grey matter, almost all S100A6 immunoreactivity was concentrated in astrocytes surrounding the Abeta amyloid deposits of senile plaques. These S100A6 neocortex labelled astrocytes were also positive for the glial fibrillary acidic protein (GFAP) and S100B protein. Contrasting with S100A6, the distribution for S100B and GFA astrocytic labelled cells was not restricted to the Abeta amyloid deposit in grey matter, but widely distributed throughout the neocortex. Coupling the knowledge that biometals such as zinc are highly concentrated in the amyloid deposits in AD and S100A6 having a high affinity for Zn(2+) may suggest that S100A6 plays a role in AD neuropathology.
Asunto(s)
Enfermedad de Alzheimer/metabolismo , Astrocitos/metabolismo , Proteínas de Unión al Calcio/metabolismo , Adulto , Anciano , Anciano de 80 o más Años , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/fisiología , Animales , Proteínas de Unión al Calcio/genética , Modelos Animales de Enfermedad , Femenino , Proteína Ácida Fibrilar de la Glía/metabolismo , Humanos , Masculino , Proteínas de la Membrana/genética , Proteínas de la Membrana/fisiología , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Persona de Mediana Edad , Presenilina-1RESUMEN
Active immunization using tau phospho-peptides in tauopathy mouse models has been observed to reduce tau pathology, especially when given prior to the onset of pathology. Since tau aggregates in these models and in human tauopathies are composed of full-length tau with many post-translational modifications, and are composed of several tau isoforms in many of them, pathological tau proteins bearing all these post-translational modifications might prove to be optimal tau conformers to use as immunogens, especially in models with advanced tau pathology. To this aim, we immunized aged wild-type and mutant tau mice with preparations containing human paired helical filaments (PHF) emulsified in Alum-adjuvant. This immunization protocol with fibrillar PHF-tau was well tolerated and did not induce an inflammatory reaction in the brain or adverse effect in these aged mice. Mice immunized with four repeated injections developed anti-PHF-tau antibodies with rising titers that labeled human neurofibrillary tangles in situ. Immunized mutant tau mice had a lower density of hippocampal Gallyas-positive neurons. Brain levels of Sarkosyl-insoluble tau were also reduced in immunized mice. These results indicate that an immunization protocol using fibrillar PHF-tau proteins is an efficient and tolerated approach to reduce tau pathology in an aged tauopathy animal model.
Asunto(s)
Enfermedad de Alzheimer/patología , Encéfalo/patología , Ovillos Neurofibrilares/patología , Neuronas/patología , Vacunación , Proteínas tau/metabolismo , Anciano de 80 o más Años , Enfermedad de Alzheimer/metabolismo , Animales , Encéfalo/metabolismo , Modelos Animales de Enfermedad , Femenino , Humanos , Ratones , Ratones Transgénicos , Ovillos Neurofibrilares/metabolismo , Neuronas/metabolismo , Proyectos Piloto , Sarcosina/administración & dosificación , Sarcosina/análogos & derivados , Proteínas tau/genéticaRESUMEN
Contusion-type cervical spinal cord injury (SCI) is one of the most common forms of SCI observed in patients. In particular, injuries targeting the C3-C5 region affect the pool of phrenic motor neurons (PhMNs) that innervates the diaphragm, resulting in significant and often chronic respiratory dysfunction. Using a previously described rat model of unilateral midcervical C4 contusion with the Infinite Horizon Impactor, we have characterized the early time course of PhMN degeneration and consequent respiratory deficits following injury, as this knowledge is important for designing relevant treatment strategies targeting protection and plasticity of PhMN circuitry. PhMN loss (48% of the ipsilateral pool) occurred almost entirely during the first 24 h post-injury, resulting in persistent phrenic nerve axonal degeneration and denervation at the diaphragm neuromuscular junction (NMJ). Reduced diaphragm compound muscle action potential amplitudes following phrenic nerve stimulation were observed as early as the first day post-injury (30% of pre-injury maximum amplitude), with slow functional improvement over time that was associated with partial reinnervation at the diaphragm NMJ. Consistent with ipsilateral diaphragmatic compromise, the injury resulted in rapid, yet only transient, changes in overall ventilatory parameters measured via whole-body plethysmography, including increased respiratory rate, decreased tidal volume, and decreased peak inspiratory flow. Despite significant ipsilateral PhMN loss, the respiratory system has the capacity to quickly compensate for partially impaired hemidiaphragm function, suggesting that C4 hemicontusion in rats is a model of SCI that manifests subacute respiratory abnormalities. Collectively, these findings demonstrate significant and persistent diaphragm compromise in a clinically relevant model of midcervical contusion SCI; however, the therapeutic window for PhMN protection is restricted to early time points post-injury. On the contrary, preventing loss of innervation by PhMNs and/or inducing plasticity in spared PhMN axons at the diaphragm NMJ are relevant long-term targets.
Asunto(s)
Diafragma/inervación , Neuronas Motoras/patología , Nervio Frénico/patología , Trastornos Respiratorios/etiología , Traumatismos de la Médula Espinal/complicaciones , Animales , Vértebras Cervicales , Diafragma/patología , Modelos Animales de Enfermedad , Femenino , Nervio Frénico/fisiopatología , Ratas , Ratas Sprague-Dawley , Recuperación de la Función/fisiología , Trastornos Respiratorios/patología , Traumatismos de la Médula Espinal/patología , Traumatismos de la Médula Espinal/fisiopatologíaRESUMEN
Respiratory dysfunction is the leading cause of morbidity and mortality following traumatic spinal cord injury (SCI). Injuries targeting mid-cervical spinal cord regions affect the phrenic motor neuron pool that innervates the diaphragm, the primary respiratory muscle of inspiration. Contusion-type injury in the cervical spinal cord is one of the most common forms of human SCI; however, few studies have evaluated mid-cervical contusion in animal models or characterized consequent histopathological and functional effects of degeneration of phrenic motor neuron-diaphragm circuitry. In an attempt to target the phrenic motor neuron pool, two unilateral contusion injury paradigms were tested, a single injury at level C4 and a double injury both at levels C3 and C4, and animals were followed for up to 6 weeks post-injury. Both unilateral cervical injury paradigms are reproducible with no mortality or need for breathing assistance, and are accompanied by phrenic motor neuron loss, phrenic nerve axon degeneration, diaphragm atrophy, denervation and subsequent partial reinnervation at the diaphragm neuromuscular junction, changes in spontaneous diaphragm EMG recordings, and reduction in phrenic nerve compound muscle action potential amplitude. These findings demonstrate significant and chronically persistent respiratory compromise following mid-cervical SCI due to phrenic motor neuron degeneration. These injury paradigms and accompanying analyses provide important tools both for understanding mechanisms of phrenic motor neuron and diaphragm pathology following SCI and for evaluating therapeutic strategies in clinically relevant cervical SCI models.
Asunto(s)
Axones/patología , Diafragma/patología , Modelos Animales de Enfermedad , Degeneración Nerviosa/patología , Nervio Frénico/patología , Traumatismos de la Médula Espinal/patología , Animales , Axones/fisiología , Vértebras Cervicales/patología , Diafragma/inervación , Diafragma/fisiopatología , Femenino , Neuronas Motoras/patología , Neuronas Motoras/fisiología , Degeneración Nerviosa/fisiopatología , Red Nerviosa/patología , Red Nerviosa/fisiopatología , Nervio Frénico/fisiología , Ratas , Ratas Sprague-Dawley , Parálisis Respiratoria/patología , Parálisis Respiratoria/fisiopatología , Traumatismos de la Médula Espinal/fisiopatologíaRESUMEN
Neurofibrillary tangles (NFTs) made of phosphorylated tau proteins are a key lesion of Alzheimer's disease and other neurodegenerative diseases, and previous studies have indicated that lithium can decrease tau phosphorylation in tau transgenic models. In this study, we have reassessed the effectiveness of treatment per os with lithium on the prevention, the arrest, or the reversal of NFT development in a tau transgenic line (Tg30tau) developing severe neurofibrillary pathology in the brain and the spinal cord. Wild-type and Tgtau30 mice were treated per os with lithium carbonate or with natrium carbonate by chronic chow feeding for 8 months starting at the age of 3 months (to test for a preventive effect on NFT formation) or by oral gavage for 1 month starting at the age of 9 months (after development of NFTs). In mice treated by oral gavage, a decrease of tau phosphorylation and of Sarkosyl-insoluble aggregated tau was observed in the brain and in the spinal cord. The density of NFTs identified by Gallyas staining in the hippocampus and in the spinal cord was also significantly reduced and was similar to that observed at the beginning of the lithium treatment. In these animals, the level of brain beta-catenin was increased probably as a result of its stabilization by glycogen synthase kinase-3beta inhibition. Despite this inhibitory effect of lithium on NFT development, the motor and working memory deficits were not significantly rescued in these aged animals. Chronic chow feeding with lithium did not alter the development of NFT. Nevertheless, this study indicates that even a relatively short-term per os treatment leading to high blood concentration of lithium is effective in arresting the formation of NFTs in the hippocampus and the spinal cord of a tau transgenic model.
Asunto(s)
Antimaníacos/uso terapéutico , Carbonato de Litio/uso terapéutico , Ovillos Neurofibrilares/efectos de los fármacos , Ovillos Neurofibrilares/patología , Tauopatías/tratamiento farmacológico , Tauopatías/fisiopatología , Factores de Edad , Análisis de Varianza , Animales , Anticuerpos Monoclonales/metabolismo , Antimaníacos/sangre , Encéfalo/metabolismo , Encéfalo/patología , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Conducta Exploratoria/efectos de los fármacos , Conducta Exploratoria/fisiología , Glucógeno Sintasa Quinasa 3/metabolismo , Humanos , Inmunoprecipitación/métodos , Carbonato de Litio/sangre , Ratones , Ratones Transgénicos , Proteínas Asociadas a Microtúbulos/metabolismo , Actividad Motora/efectos de los fármacos , Actividad Motora/genética , Mutación/genética , Proteínas del Tejido Nervioso/metabolismo , Fosforilación/efectos de los fármacos , Proteínas Proto-Oncogénicas c-akt/metabolismo , Nervio Ciático/patología , Médula Espinal/metabolismo , Médula Espinal/patología , Tauopatías/complicaciones , Tauopatías/genética , Proteínas tau/genética , Proteínas tau/metabolismoRESUMEN
Blood-brain barrier (BBB) and blood-spinal cord barrier (BSCB) impairment is an additional accident occurring during the amyotrophic lateral sclerosis (ALS) progression. In this work, we aimed to decipher if BBB/BSCB leakage appeared before critical detrimental events and could serve as a marker preceding clinical symptoms. Three different BBB leakage markers: Evans blue, IgG and hemosiderin, were used to look at the SOD1-linked ALS rat model at presymptomatic and symptomatic stages. Although IgG and hemosiderin could be detected at presymptomatic stage, Evans blue extravasation which fits best with BBB/BSCB impairment could only be seen at symptomatic stages. BBB/BSCB impairment was further substantiate by showing at symptomatic stages decreased mRNA expression of ZO-1 and occludin as well as agrin, a basal membrane constituent. Electron microscopic data substantiate a toxic environment around endothelial cell and peri-vascular swollen astrocyte end-feet showing oedema-linked BBB opening.
Asunto(s)
Esclerosis Amiotrófica Lateral/patología , Barrera Hematoencefálica/patología , Tronco Encefálico/patología , Médula Espinal/patología , Superóxido Dismutasa/genética , Agrina/genética , Agrina/metabolismo , Esclerosis Amiotrófica Lateral/genética , Esclerosis Amiotrófica Lateral/metabolismo , Animales , Astrocitos/metabolismo , Astrocitos/patología , Biomarcadores , Barrera Hematoencefálica/metabolismo , Tronco Encefálico/metabolismo , Forma de la Célula , Modelos Animales de Enfermedad , Células Endoteliales/citología , Ensayo de Inmunoadsorción Enzimática , Azul de Evans , Hemosiderina/metabolismo , Inmunoglobulinas/metabolismo , Inmunohistoquímica , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Microscopía Electrónica , Ocludina , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Ratas Transgénicas , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Médula Espinal/metabolismo , Coloración y Etiquetado , Proteína de la Zonula Occludens-1RESUMEN
Onset of motoneuron death characterizing amyotrophic lateral sclerosis (ALS) is closely linked to modified astrocytic and glial environments. Here, we show that in the spinal cord from transgenic rat overexpressing mutated human SOD1, aquaporin-4 mRNA and protein are specifically overexpressed in the gray matter at end stage of disease. Immunohistochemistry and double immunofluorescence allowed to detect, in the spinal cord gray matter of the ALS rat, increased aquaporin-4 surrounding both vessel and motoneuron perikarya. The use of pre-embedding immunohistochemistry at electron microscopic level confirmed such localization associated with swollen astrocytic processes surrounding the vessels. The AQP4 immunohistochemical labeling surrounding several motoneuron perikarya was only seen in ALS rats. Identification of this AQP4-positive cellular type remains unclear.
Asunto(s)
Esclerosis Amiotrófica Lateral/genética , Esclerosis Amiotrófica Lateral/metabolismo , Acuaporina 4/genética , Acuaporina 4/metabolismo , Médula Espinal/metabolismo , Sustitución de Aminoácidos , Esclerosis Amiotrófica Lateral/patología , Animales , Animales Modificados Genéticamente , Astrocitos/metabolismo , Astrocitos/patología , Secuencia de Bases , Cartilla de ADN/genética , Modelos Animales de Enfermedad , Humanos , Inmunohistoquímica , Microscopía Fluorescente , Microscopía Inmunoelectrónica , Neuronas Motoras/metabolismo , Neuronas Motoras/patología , Mutagénesis Sitio-Dirigida , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Médula Espinal/irrigación sanguínea , Médula Espinal/patología , Superóxido Dismutasa/genética , Superóxido Dismutasa/metabolismo , Superóxido Dismutasa-1RESUMEN
Neurodegenerative diseases characterized by brain and spinal cord involvement often show widespread accumulations of tau aggregates. We have generated a transgenic mouse line (Tg30tau) expressing in the forebrain and the spinal cord a human tau protein bearing two pathogenic mutations (P301S and G272V). These mice developed age-dependent brain and hippocampal atrophy, central and peripheral axonopathy, progressive motor impairment with neurogenic muscle atrophy, and neurofibrillary tangles and had decreased survival. Axonal spheroids and axonal atrophy developed early before neurofibrillary tangles. Neurofibrillary inclusions developed in neurons at 3 months and were of two types, suggestive of a selective vulnerability of neurons to form different types of fibrillary aggregates. A first type of tau-positive neurofibrillary tangles, more abundant in the forebrain, were composed of ribbon-like 19-nm-wide filaments and twisted paired helical filaments. A second type of tau and neurofilament-positive neurofibrillary tangles, more abundant in the spinal cord and the brainstem, were composed of 10-nm-wide neurofilaments and straight 19-nm filaments. Unbiased stereological analysis indicated that total number of pyramidal neurons and density of neurons in the lumbar spinal cord were not reduced up to 12 months in Tg30tau mice. This Tg30tau model thus provides evidence that axonopathy precedes tangle formation and that both lesions can be dissociated from overt neuronal loss in selected brain areas but not from neuronal dysfunction.
Asunto(s)
Axones/patología , Ovillos Neurofibrilares/patología , Proteínas tau/metabolismo , Animales , Atrofia/patología , Axones/metabolismo , Encéfalo/patología , Modelos Animales de Enfermedad , Glucógeno Sintasa Quinasa 3/metabolismo , Glucógeno Sintasa Quinasa 3 beta , Humanos , Cuerpos de Inclusión/ultraestructura , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Ratones , Ratones Transgénicos , Actividad Motora/fisiología , Trastornos del Movimiento/patología , Trastornos del Movimiento/fisiopatología , Degeneración Nerviosa/patología , Degeneración Nerviosa/fisiopatología , Ovillos Neurofibrilares/metabolismo , Proteínas de Neurofilamentos/metabolismo , Neuronas/citología , Neuronas/metabolismo , Neuronas/patología , Nervio Ciático/metabolismo , Nervio Ciático/patología , Nervio Ciático/ultraestructura , Médula Espinal/citología , Médula Espinal/metabolismo , Médula Espinal/patología , Tauopatías/patología , Tauopatías/fisiopatología , Proteínas tau/genéticaRESUMEN
To study the role of Abeta amyloid deposits in the generation of cytoskeletal lesions, we have generated a transgenic mouse line coexpressing in the same neurons a wild-type human tau isoform (0N3R), a mutant form of APP (751SL) and a mutant form of PS1 (M146L). These mice developed early cerebral extracellular deposits of Abeta, starting at 2.5 months. A somatodendritic neuronal accumulation of transgenic tau protein was observed in tau only and in tau/PS1/APP transgenic mice, including in neurons adjacent to Abeta deposits. The phosphorylation status of this somatodendritic tau was similar in the two transgenic lines. The Abeta deposits were surrounded by a neuritic reaction composed of axonal dystrophic processes, immunoreactive for many phosphotau epitopes and for the human tau transgenic protein. Ultrastructural observation showed in these dystrophic neurites a disorganisation of the microtubule and the neurofilament network but animals that were observed up to 18 months of age did not develop neurofibrillary tangles. These results indicate that overexpression of mutant PS1, mutant APP and of wild-type human tau were not sufficient per se to drive the formation of neurofibrillary tangles in a transgenic model. The Abeta deposits, however, were associated to marked changes in cytoskeletal organisation and in tau phosphorylation in adjacent dystrophic neurites.