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[This corrects the article DOI: 10.3389/fcell.2020.615571.].
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Reelin is a protein that is best known for its role in controlling neuronal layer formation in the developing cortex. Here, we studied its role for post-natal cortical network function, which is poorly explored. To preclude early cortical migration defects caused by Reelin deficiency, we used a conditional Reelin knock-out (RelncKO ) mouse, and induced Reelin deficiency post-natally. Induced Reelin deficiency caused hyperexcitability of the neocortical network in vitro and ex vivo. Blocking Reelin binding to its receptors ApoER2 and VLDLR resulted in a similar effect. Hyperexcitability in RelncKO organotypic slice cultures could be rescued by co-culture with wild-type organotypic slice cultures. Moreover, the GABAB receptor (GABAB R) agonist baclofen failed to activate and the antagonist CGP35348 failed to block GABAB Rs in RelncKO mice. Immunolabeling of RelncKO cortical slices revealed a reduction in GABAB R1 and GABAB R2 surface expression at the plasma membrane and western blot of RelncKO cortical tissue revealed decreased phosphorylation of the GABAB R2 subunit at serine 892 and increased phosphorylation at serine 783, reflecting receptor deactivation and proteolysis. These data show a role of Reelin in controlling early network activity, by modulating GABAB R function. Cover Image for this issue: https://doi.org/10.1111/jnc.15054.
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Moléculas de Adhesión Celular Neuronal/deficiencia , Proteínas de la Matriz Extracelular/deficiencia , Neocórtex/metabolismo , Proteínas del Tejido Nervioso/deficiencia , Receptores de GABA-B/fisiología , Serina Endopeptidasas/deficiencia , Transducción de Señal/fisiología , Animales , Animales Recién Nacidos , Moléculas de Adhesión Celular Neuronal/genética , Proteínas de la Matriz Extracelular/genética , Femenino , Agonistas de Receptores GABA-B/farmacología , Masculino , Ratones , Ratones Noqueados , Proteínas del Tejido Nervioso/genética , Técnicas de Cultivo de Órganos , Proteína Reelina , Serina Endopeptidasas/genética , Transducción de Señal/efectos de los fármacosRESUMEN
The expanded HTT CAG repeat causing Huntington's disease (HD) exhibits somatic expansion proposed to drive the rate of disease onset by eliciting a pathological process that ultimately claims vulnerable cells. To gain insight into somatic expansion in humans, we performed comprehensive quantitative analyses of CAG expansion in ~50 central nervous system (CNS) and peripheral postmortem tissues from seven adult-onset and one juvenile-onset HD individual. We also assessed ATXN1 CAG repeat expansion in brain regions of an individual with a neurologically and pathologically distinct repeat expansion disorder, spinocerebellar ataxia type 1 (SCA1). Our findings reveal similar profiles of tissue instability in all HD individuals, which, notably, were also apparent in the SCA1 individual. CAG expansion was observed in all tissues, but to different degrees, with multiple cortical regions and neostriatum tending to have the greatest instability in the CNS, and liver in the periphery. These patterns indicate different propensities for CAG expansion contributed by disease locus-independent trans-factors and demonstrate that expansion per se is not sufficient to cause cell type or disease-specific pathology. Rather, pathology may reflect distinct toxic processes triggered by different repeat lengths across cell types and diseases. We also find that the HTT CAG length-dependent expansion propensity of an individual is reflected in all tissues and in cerebrospinal fluid. Our data indicate that peripheral cells may be a useful source to measure CAG expansion in biomarker assays for therapeutic efforts, prompting efforts to dissect underlying mechanisms of expansion that may differ between the brain and periphery.
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Enfermedad de Huntington/genética , Ataxias Espinocerebelosas/genética , Expansión de Repetición de Trinucleótido/genética , Repeticiones de Trinucleótidos/genética , Adulto , Anciano , Autopsia , Sistema Nervioso Central/patología , Niño , Femenino , Humanos , Proteína Huntingtina/genética , Enfermedad de Huntington/diagnóstico por imagen , Enfermedad de Huntington/patología , Masculino , Persona de Mediana Edad , Neostriado/diagnóstico por imagen , Neostriado/metabolismo , Neostriado/patología , Ataxias Espinocerebelosas/diagnóstico por imagen , Ataxias Espinocerebelosas/patologíaRESUMEN
There is increasing evidence from genetic, biochemical, pharmacological, neuroimaging and post-mortem studies that immunological dysregulation plays a crucial role in the pathogenesis of psychoses. The involvement of microglia in schizophrenia and bipolar disorder (BD) has remained controversial, however, since results from various post-mortem studies are still inconclusive. Here, we analyzed the estimated density of microglia of age-matched individuals with schizophrenia (n = 17), BD (n = 13), and non-psychiatric control subjects (n = 17) in the anterior midcingulate cortex (aMCC), a brain area putatively involved in the pathogenesis of psychoses, using ionized calcium binding adaptor molecule 1 (Iba1)-immunohistochemistry. The microglial cells displayed a homogenously distributed Iba1-staining pattern in the aMCC with slightly varying activation states in all three groups. The estimated microglial densities did not differ significantly between individuals with schizophrenia, BD and control subjects. Remarkably, when both hemispheres were investigated separately within the three groups, the density was significantly lateralized towards the right aMCC in schizophrenia (p = 0.01) and-even more evident-in BD subjects (p = 0.008). This left-right lateralization was not observed in the control group (p = 0.52). Of note, microglial density was significantly lower in BD individuals who did not commit suicide compared with BD individuals who died from suicide (p = 0.002). This difference was not observed between individuals with BD who committed suicide and controls. The results, tentatively interpreted, suggest a hitherto unknown increased lateralization of microglial density to the right hemisphere in both psychiatric groups. If confirmed in independent samples, lateralization should be considered in all post-mortem studies on microglia. Density differences between suicide and non-suicide individuals needs further elucidation.
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Trastorno Bipolar/inmunología , Proteínas de Unión al Calcio/inmunología , Giro del Cíngulo/inmunología , Proteínas de Microfilamentos/inmunología , Microglía/inmunología , Esquizofrenia/inmunología , Adulto , Diagnóstico , Femenino , Lateralidad Funcional/fisiología , Humanos , Masculino , Persona de Mediana Edad , Suicidio CompletoRESUMEN
The indusium griseum (IG) is a cortical structure overlying the corpus callosum along its anterior-posterior extent. It has been classified either as a vestige of the hippocampus or as an extension of the dentate gyrus via the fasciola cinerea, but its attribution to a specific hippocampal subregion is still under debate. To specify the identity of IG neurons more precisely, we investigated the spatiotemporal expression of calbindin, secretagogin, Necab2, PCP4, and Prox1 in the postnatal mouse IG, fasciola cinerea, and hippocampus. We identified the calcium-binding protein Necab2 as a first reliable marker for the IG and fasciola cinerea throughout postnatal development into adulthood. In contrast, calbindin, secretagogin, and PCP4 were expressed each with a different individual time course during maturation, and at no time point, IG or fasciola cinerea principal neurons expressed Prox1, a transcription factor known to define dentate granule cell fate. Concordantly, in a transgenic mouse line expressing enhanced green fluorescent protein (eGFP) in dentate granule cells, neurons of IG and fasciola cinerea were eGFP-negative. Our findings preclude that IG neurons represent dentate granule cells, as earlier hypothesized, and strongly support the view that the IG is an own hippocampal subfield composed of a distinct neuronal population.
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Neurodegenerative diseases are characterized by the accumulation of misfolded proteins in the brain. Insights into protein quality control mechanisms to prevent neuronal dysfunction and cell death are crucial in developing causal therapies. Here, we report that various disease-associated protein aggregates are modified by the linear ubiquitin chain assembly complex (LUBAC). HOIP, the catalytic component of LUBAC, is recruited to misfolded Huntingtin in a p97/VCP-dependent manner, resulting in the assembly of linear polyubiquitin. As a consequence, the interactive surface of misfolded Huntingtin species is shielded from unwanted interactions, for example with the low complexity sequence domain-containing transcription factor Sp1, and proteasomal degradation of misfolded Huntingtin is facilitated. Notably, all three core LUBAC components are transcriptionally regulated by Sp1, linking defective LUBAC expression to Huntington's disease. In support of a protective activity of linear ubiquitination, silencing of OTULIN, a deubiquitinase with unique specificity for linear polyubiquitin, decreases proteotoxicity, whereas silencing of HOIP has the opposite effect. These findings identify linear ubiquitination as a protein quality control mechanism and hence a novel target for disease-modifying strategies in proteinopathies.
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Proteína Huntingtina/metabolismo , Enfermedad de Huntington/metabolismo , Poliubiquitina/metabolismo , Procesamiento Proteico-Postraduccional , Factor de Transcripción Sp1/metabolismo , Proteína que Contiene Valosina/metabolismo , Adulto , Anciano , Animales , Encéfalo/metabolismo , Encéfalo/patología , Estudios de Casos y Controles , Células Cultivadas , Embrión de Mamíferos/citología , Embrión de Mamíferos/metabolismo , Femenino , Fibroblastos/citología , Fibroblastos/metabolismo , Humanos , Proteína Huntingtina/genética , Enfermedad de Huntington/genética , Enfermedad de Huntington/patología , Masculino , Ratones , Ratones Noqueados , Persona de Mediana Edad , FN-kappa B/genética , FN-kappa B/metabolismo , Neuronas/metabolismo , Neuronas/patología , Unión Proteica , Dominios y Motivos de Interacción de Proteínas , Transducción de Señal , Factor de Transcripción Sp1/genética , Ubiquitinación , Proteína que Contiene Valosina/genéticaRESUMEN
The Ccdc66-deficient (Ccdc66 -/-) mouse model exhibits slow progressive retinal degeneration. It is unclear whether CCDC66 protein also plays a role in the wildtype (WT; Ccdc66 +/+) mouse brain and whether the lack of Ccdc66 gene expression in the Ccdc66 -/- mouse brain may result in morphological and behavioral alterations. CCDC66 protein expression in different brain regions of the adult WT mouse and in whole brain during postnatal development was quantified by SDS-PAGE and Western blot. Ccdc66 reporter gene expression was visualized by X-gal staining. Selected brain regions were further analyzed by light and electron microscopy. In order to correlate anatomical with behavioral data, an olfactory habituation/dishabituation test was performed. CCDC66 protein was expressed throughout the early postnatal development in the WT mouse brain. In adult mice, the main olfactory bulb exhibited high CCDC66 protein levels comparable to the expression in the retina. Additionally, the Ccdc66 -/- mouse brain showed robust Ccdc66 reporter gene expression especially in adult olfactory bulb glomeruli, the olfactory nerve layer and the olfactory epithelium. Degeneration was detected in the Ccdc66 -/- olfactory bulb glomeruli at advanced age. This degeneration was also reflected in behavioral alterations; compared to the WT, Ccdc66 -/- mice spent significantly less time sniffing at the initial presentation of unknown, neutral odors and barely responded to social odors. Ccdc66 -/- mice develop substantial olfactory nerve fiber degeneration and alteration of olfaction-related behavior at advanced age. Thus, the Ccdc66 -/- mouse model for retinal degeneration adds the possibility to study mechanisms of central nervous system degeneration.
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PURPOSE: Retinitis pigmentosa (RP) is the most common inherited retinal disease with high genetic heterogeneity and variable phenotypes. Characteristic symptoms include night blindness and progressive loss of visual field, leading to blindness. Mutations in >60 genes have been identified to date as causative for RP, and additional candidate genes are assumed. METHODS: To find the disease-causing mutations in the affected members of five Turkish families, we sequenced whole exomes using an Illumina platform. RESULTS: Among all candidate genes for retinal degeneration we found two previously known sequence variations: a 4 bp deletion in the RPGR gene (c.1662_1665delAGAA; p.Glu555Glyfs*14) and a recently described USH1-causing missense mutation in MYO7A (c.472G>A, p.Gly158Arg). Furthermore, a novel 1 bp deletion in the VCAN gene (c.5118delA; p.Ser1707Valfs*44) was detected as well as a large deletion in EYS, spanning â¼ 400kb and comprising exons 16-26 (p.fs*). In one family, exome analyses of two affected individuals revealed a homozygous missense mutation (c.883G>A; p.Asp295Asn) in the AGBL5 (Agbl5; CCP5) gene, previously not reported to be associated with RP. RNA and protein analyses showed expression in human retina, as well as in mouse retina, brain and testis. Furthermore, cDNA analyses indicate the existence of tissue-specific AGBL5 splice variations in humans. AGBL5/CCP5 immunoreactivity was also visualized in human and mouse retinae. CONCLUSION: Due to the characteristic RP phenotype in patients carrying the AGBL5 missense mutation we suggest this gene as a candidate for a new form of autosomal recessively inherited RP and recommend further investigation to confirm this hypothesis.
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Carboxipeptidasas/genética , Exoma/genética , Mutación Missense , Miopía Degenerativa/genética , Retinitis Pigmentosa/genética , Animales , Western Blotting , Carboxipeptidasas/metabolismo , Análisis Mutacional de ADN , Femenino , Humanos , Inmunohistoquímica , Masculino , Ratones , Linaje , TurquíaRESUMEN
BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory skin disorder caused by complex interaction of genetic and environmental factors. Besides mutations in the filaggrin gene, leading to impaired skin barrier function, variation in genes encoding additional skin proteins has been suggested to contribute to disease risk. Laminin 5, playing an important role in skin integrity, is composed of three subunits encoded by the LAMA3, LAMB3 and LAMC2 genes in which biallelic mutations cause epidermolysis bullosa junctionalis. We aimed at evaluating the role of variation in the LAMA3, LAMB3 and LAMC2 genes for AD pathogenesis. METHODS: 29 single nucleotide polymorphisms (SNPs) were genotyped in the three genes in a German AD case-control cohort comprising 470 unrelated AD patients and 320 non-atopic controls by means of restriction enzyme digestion. Allele, genotype and haplotype frequencies were compared between cases and controls using chi-square testing and the Haploview software. RESULTS: Several SNPs in the LAMA3 gene showed significant association with AD in our cohort (p <0.01), while we did not detect association with variations in the LAMB3 and LAMC2 genes. Haplotype analysis additionally revealed several significantly associated haplotypes in the LAMA3 gene. Due to extensive linkage disequilibrium, though, we were not able to further differentiate the specific disease causing variation(s) in this region. CONCLUSIONS: We established the LAMA3 gene as novel potential susceptibility gene for AD. Additional studies in independent cohorts are needed to replicate these results.
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Moléculas de Adhesión Celular/genética , Dermatitis Atópica/genética , Predisposición Genética a la Enfermedad , Laminina/genética , Polimorfismo de Nucleótido Simple , Adolescente , Adulto , Alelos , Estudios de Casos y Controles , Niño , Preescolar , Proteínas Filagrina , Haplotipos , Humanos , Desequilibrio de Ligamiento , Adulto Joven , KalininaRESUMEN
The nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signaling cascade participates in the modulation of synaptic transmission. The effects of NO are mediated by the NO-sensitive cGMP-forming guanylyl cyclases (NO-GCs), which exist in 2 isoforms with indistinguishable regulatory properties. The lack of long-term potentiation (LTP) in knock-out (KO) mice deficient in either one of the NO-GC isoforms indicates the contribution of both NO-GCs to LTP. Recently, we showed that the NO-GC1 isoform is located presynaptically in glutamatergic neurons and increases the glutamate release via hyperpolarization-activated cyclic nucleotide (HCN)-gated channels in the hippocampus. Electrophysiological analysis of hippocampal CA1 neurons in whole-cell recordings revealed a reduction of HCN currents and a hyperpolarizing shift of the activation curve in the NO-GC2 KOs associated with reduced resting membrane potentials. These features were mimicked in wild-type (WT) neurons with an NO-GC inhibitor. Analysis of glutamate receptors revealed a cGMP-dependent reduction of NMDA receptor currents in the NO-GC2 KO mice, which was mimicked in WT by HCN channel inhibition. Lowering extracellular Mg(2+) increased NMDA receptor currents in the NO-GC2 KO and allowed the induction of LTP that was absent at physiological Mg(2+). In sum, our data indicate that postsynaptic cGMP increases the N-methyl-D-aspartate (NMDA) receptor current by gating HCN channels and thereby is required for LTP.
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Región CA1 Hipocampal/citología , GMP Cíclico/metabolismo , Potenciación a Largo Plazo/fisiología , Neuronas/fisiología , Óxido Nítrico/deficiencia , Receptores de N-Metil-D-Aspartato/metabolismo , Anestésicos Locales/farmacología , Animales , Animales Recién Nacidos , GMP Cíclico/farmacología , Estimulación Eléctrica , Antagonistas de Aminoácidos Excitadores/farmacología , Guanilato Ciclasa/genética , Guanilato Ciclasa/metabolismo , Canales Regulados por Nucleótidos Cíclicos Activados por Hiperpolarización/metabolismo , Técnicas In Vitro , Lidocaína/análogos & derivados , Lidocaína/farmacología , Potenciación a Largo Plazo/efectos de los fármacos , Ratones , Ratones Noqueados , Neuronas/efectos de los fármacos , Óxido Nítrico/genética , Técnicas de Placa-Clamp , Pirimidinas/farmacología , Tetraetilamonio/farmacologíaRESUMEN
A complex network of genes determines sex in mammals. Here, we studied a European roe deer with an intersex phenotype that was consistent with a XY genotype with incomplete male-determination. Whole genome sequencing and quantitative real-time PCR analyses revealed a triple dose of the SOX9 gene, allowing insights into a new genetic defect in a wild animal.
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Ciervos/genética , Trastornos del Desarrollo Sexual/genética , Duplicación de Gen , Factor de Transcripción SOX9/genética , Animales , Variaciones en el Número de Copia de ADN , Femenino , Variación Genética , Genotipo , Masculino , Datos de Secuencia Molecular , Fenotipo , Reacción en Cadena de la Polimerasa , Análisis de Secuencia de ADN/métodosRESUMEN
The N-acyl chain length of ceramides is determined by the specificity of different ceramide synthases (CerS). The CerS family in mammals consists of six members with different substrate specificities and expression patterns. We have generated and characterized a mouse line harboring an enzymatically inactive ceramide synthase 6 (CerS6KO) gene and lacz reporter cDNA coding for ß-galactosidase directed by the CerS6 promoter. These mice display a decrease in C16:0 containing sphingolipids. Relative to wild type tissues the amount of C16:0 containing sphingomyelin in kidney is â¼35%, whereas we find a reduction of C16:0 ceramide content in the small intestine to about 25%. The CerS6KO mice show behavioral abnormalities including a clasping abnormality of their hind limbs and a habituation deficit. LacZ reporter expression in the brain reveals CerS6 expression in hippocampus, cortex, and the Purkinje cell layer of the cerebellum. Using newly developed antibodies that specifically recognize the CerS6 protein we show that the endogenous CerS6 protein is N-glycosylated and expressed in several tissues of mice, mainly kidney, small and large intestine, and brain.
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Conducta Animal , Esfingolípidos/metabolismo , Esfingosina N-Aciltransferasa/metabolismo , Animales , Ansiedad/patología , Ansiedad/fisiopatología , Encéfalo/metabolismo , Encéfalo/patología , Activación Enzimática , Pruebas de Enzimas , Conducta Exploratoria , Técnica del Anticuerpo Fluorescente , Glicosilación , Células HEK293 , Habituación Psicofisiológica , Humanos , Glomérulos Renales/metabolismo , Glomérulos Renales/patología , Glomérulos Renales/ultraestructura , Espectrometría de Masas , Aprendizaje por Laberinto , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Especificidad de Órganos , Fenotipo , Esfingolípidos/química , Esfingosina N-Aciltransferasa/deficiencia , beta-Galactosidasa/metabolismoRESUMEN
Spinocerebellar ataxia 17 (SCA17) is an autosomal-dominant, late-onset neurodegenerative disorder caused by an expanded polyglutamine (polyQ) repeat in the TATA-box-binding protein (TBP). To further investigate this devastating disease, we sought to create a first transgenic rat model for SCA17 that carries a full human cDNA fragment of the TBP gene with 64 CAA/CAG repeats (TBPQ64). In line with previous observations in mouse models for SCA17, TBPQ64 rats show a severe neurological phenotype including ataxia, impairment of postural reflexes, and hyperactivity in early stages followed by reduced activity, loss of body weight, and early death. Neuropathologically, the severe phenotype of SCA17 rats was associated with neuronal loss, particularly in the cerebellum. Degeneration of Purkinje, basket, and stellate cells, changes in the morphology of the dendrites, nuclear TBP-positive immunoreactivity, and axonal torpedos were readily found by light and electron microscopy. While some of these changes are well recapitulated in existing mouse models for SCA17, we provide evidence that some crucial characteristics of SCA17 are better mirrored in TBPQ64 rats. Thus, this SCA17 model represents a valuable tool to pursue experimentation and therapeutic approaches that may be difficult or impossible to perform with SCA17 transgenic mice. We show for the first time positron emission tomography (PET) and diffusion tensor imaging (DTI) data of a SCA animal model that replicate recent PET studies in human SCA17 patients. Our results also confirm that DTI are potentially useful correlates of neuropathological changes in TBPQ64 rats and raise hope that DTI imaging could provide a biomarker for SCA17 patients.
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Imagen de Difusión Tensora , Modelos Animales de Enfermedad , Ataxias Espinocerebelosas , Proteína de Unión a TATA-Box/genética , Expansión de Repetición de Trinucleótido/genética , Animales , Ansiedad/etiología , Ansiedad/genética , Peso Corporal/genética , Encéfalo/metabolismo , Encéfalo/patología , Encéfalo/ultraestructura , Procesamiento Automatizado de Datos , Femenino , Genotipo , Humanos , Masculino , Aprendizaje por Laberinto , Actividad Motora , Examen Neurológico , Tomografía de Emisión de Positrones , Desempeño Psicomotor/fisiología , Racloprida/farmacocinética , Ratas , Ratas Transgénicas , Prueba de Desempeño de Rotación con Aceleración Constante , Índice de Severidad de la Enfermedad , Ataxias Espinocerebelosas/diagnóstico , Ataxias Espinocerebelosas/genética , Ataxias Espinocerebelosas/fisiopatología , Tubulina (Proteína)/metabolismoRESUMEN
Huntington disease (HD) is an inherited progressive neurodegenerative disorder, characterized by motor, cognitive, and psychiatric deficits as well as neurodegeneration and brain atrophy beginning in the striatum and the cortex and extending to other subcortical brain regions. The genetic cause is an expansion of the CAG repeat stretch in the HTT gene encoding huntingtin protein (htt). Here, we generated an HD transgenic rat model using a human bacterial artificial chromosome (BAC), which contains the full-length HTT genomic sequence with 97 CAG/CAA repeats and all regulatory elements. BACHD transgenic rats display a robust, early onset and progressive HD-like phenotype including motor deficits and anxiety-related symptoms. In contrast to BAC and yeast artificial chromosome HD mouse models that express full-length mutant huntingtin, BACHD rats do not exhibit an increased body weight. Neuropathologically, the distribution of neuropil aggregates and nuclear accumulation of N-terminal mutant huntingtin in BACHD rats is similar to the observations in human HD brains. Aggregates occur more frequently in the cortex than in the striatum and neuropil aggregates appear earlier than mutant htt accumulation in the nucleus. Furthermore, we found an imbalance in the striatal striosome and matrix compartments in early stages of the disease. In addition, reduced dopamine receptor binding was detectable by in vivo imaging. Our data demonstrate that this transgenic BACHD rat line may be a valuable model for further understanding the disease mechanisms and for preclinical pharmacological studies.
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Cromosomas Artificiales Bacterianos/genética , Enfermedad de Huntington/genética , Enfermedad de Huntington/patología , Proteínas del Tejido Nervioso/genética , Empalme Alternativo , Animales , Ansiedad/genética , Ansiedad/psicología , Conducta Animal/fisiología , Western Blotting , Peso Corporal/fisiología , Ingestión de Alimentos/fisiología , Trastornos Neurológicos de la Marcha/psicología , Dosificación de Gen , Humanos , Proteína Huntingtina , Enfermedad de Huntington/psicología , Inmunohistoquímica , Actividad Motora/fisiología , Tomografía de Emisión de Positrones , Equilibrio Postural/fisiología , Regiones Promotoras Genéticas , ARN Mensajero/biosíntesis , ARN Mensajero/genética , Ratas , Ratas Sprague-Dawley , Ratas Transgénicas , Reacción en Cadena en Tiempo Real de la PolimerasaRESUMEN
Pannexin 1 (Panx1) represents a class of vertebrate membrane channels, bearing significant sequence homology with the invertebrate gap junction proteins, the innexins and more distant similarities in the membrane topologies and pharmacological sensitivities with gap junction proteins of the connexin family. In the nervous system, cooperation among pannexin channels, adenosine receptors, and K(ATP) channels modulating neuronal excitability via ATP and adenosine has been recognized, but little is known about the significance in vivo. However, the localization of Panx1 at postsynaptic sites in hippocampal neurons and astrocytes in close proximity together with the fundamental role of ATP and adenosine for CNS metabolism and cell signaling underscore the potential relevance of this channel to synaptic plasticity and higher brain functions. Here, we report increased excitability and potently enhanced early and persistent LTP responses in the CA1 region of acute slice preparations from adult Panx1(-/-) mice. Adenosine application and N-methyl-D-aspartate receptor (NMDAR)-blocking normalized this phenotype, suggesting that absence of Panx1 causes chronic extracellular ATP/adenosine depletion, thus facilitating postsynaptic NMDAR activation. Compensatory transcriptional up-regulation of metabotropic glutamate receptor 4 (grm4) accompanies these adaptive changes. The physiological modification, promoted by loss of Panx1, led to distinct behavioral alterations, enhancing anxiety and impairing object recognition and spatial learning in Panx1(-/-) mice. We conclude that ATP release through Panx1 channels plays a critical role in maintaining synaptic strength and plasticity in CA1 neurons of the adult hippocampus. This result provides the rationale for in-depth analysis of Panx1 function and adenosine based therapies in CNS disorders.
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Astrocitos/metabolismo , Conexinas/fisiología , Hipocampo/metabolismo , Aprendizaje/fisiología , Proteínas del Tejido Nervioso/fisiología , Neuronas/metabolismo , Transmisión Sináptica/fisiología , Adenosina Trifosfato/metabolismo , Animales , Ansiedad , Astrocitos/citología , Western Blotting , Electrofisiología , Femenino , Técnica del Anticuerpo Fluorescente , Hipocampo/citología , Técnicas para Inmunoenzimas , Potenciación a Largo Plazo , Masculino , Ratones , Ratones Noqueados , Neuronas/citología , ARN Mensajero/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Receptores de N-Metil-D-Aspartato/metabolismo , Reconocimiento en Psicología/fisiología , Reflejo de Sobresalto/fisiología , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Posttranslational amyloid-ß (Aß) modification is considered to play an important role in Alzheimer's disease (AD) etiology. An N-terminally modified Aß species, pyroglutamate-amyloid-ß (pE3-Aß), has been described as a major constituent of Aß deposits specific to human AD but absent in normal aging. Formed via cyclization of truncated Aß species by glutaminyl cyclase (QC; QPCT) and/or its isoenzyme (isoQC; QPCTL), pE3-Aß aggregates rapidly and is known to seed additional Aß aggregation. To directly investigate pE3-Aß toxicity in vivo, we generated and characterized transgenic TBA2.1 and TBA2.2 mice, which express truncated mutant human Aß. Along with a rapidly developing behavioral phenotype, these mice showed progressively accumulating Aß and pE3-Aß deposits in brain regions of neuronal loss, impaired long-term potentiation, microglial activation, and astrocytosis. Illustrating a threshold for pE3-Aß neurotoxicity, this phenotype was not found in heterozygous animals but in homozygous TBA2.1 or double-heterozygous TBA2.1/2.2 animals only. A significant amount of pE3-Aß formation was shown to be QC-dependent, because crossbreeding of TBA2.1 with QC knock-out, but not isoQC knock-out, mice significantly reduced pE3-Aß levels. Hence, lowering the rate of QC-dependent posttranslational pE3-Aß formation can, in turn, lower the amount of neurotoxic Aß species in AD.
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Precursor de Proteína beta-Amiloide/biosíntesis , Trastornos Heredodegenerativos del Sistema Nervioso/genética , Trastornos Heredodegenerativos del Sistema Nervioso/patología , Hipocampo/patología , Ácido Pirrolidona Carboxílico/metabolismo , Envejecimiento/patología , Envejecimiento/psicología , Enfermedad de Alzheimer/patología , Animales , Conducta Animal , Encéfalo/patología , Ensayo de Inmunoadsorción Enzimática , Gliosis/patología , Trastornos Heredodegenerativos del Sistema Nervioso/psicología , Humanos , Inmunohistoquímica , Cinética , Potenciación a Largo Plazo/fisiología , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos DBA , Ratones Transgénicos , Microscopía Electrónica , Plasticidad Neuronal/genética , Plasticidad Neuronal/fisiología , Fenotipo , Equilibrio Postural/fisiología , Procesamiento Proteico-Postraduccional , Reflejo de Sobresalto/fisiología , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
Mutations in the N-terminus of the gene encoding α-synuclein (α-syn) are linked to autosomal dominantly inherited Parkinson's disease (PD). The vast majority of PD patients develop neuropsychiatric symptoms preceding motor impairments. During this premotor stage, synucleinopathy is first detectable in the olfactory bulb (OB) and brain stem nuclei; however its impact on interconnected brain regions and related symptoms is still less far understood. Using a novel conditional transgenic mouse model, displaying region-specific expression of human mutant α-syn, we evaluated effect and reversibility of olfactory synucleinopathy. Our data showed that induction of mutant A30P α-syn expression increased transgenic deposition into somatodendritic compartment of dopaminergic neurons, without generating fibrillar inclusions. We found reversibly reduced levels of dopamine and metabolites in the OB, suggesting an impact of A30P α-syn on olfactory neurotransmitter content. We further showed that mutant A30P expression led to neurodegenerative changes on an ultrastructural level and a behaviorally hyperactive response correlated with novelty, odor processing and stress associated with an increased dopaminergic tone in midbrain regions. Our present data indicate that mutant (A30P) α-syn is directly implicated in reduction of dopamine signaling in OB interneurons, which mediates further alterations in brain regions without transgenic expression leading functionally to a hyperactive response. These modulations of neurotransmission may underlie in part some of the early neuropsychiatric symptoms in PD preceding dysfunction of the nigrostriatal dopaminergic system.
Asunto(s)
Dopamina/deficiencia , Neuronas/metabolismo , Bulbo Olfatorio/metabolismo , Trastornos Parkinsonianos/metabolismo , Trastornos Parkinsonianos/fisiopatología , alfa-Sinucleína/genética , Sustitución de Aminoácidos/genética , Animales , Cricetinae , Modelos Animales de Enfermedad , Dopamina/biosíntesis , Femenino , Humanos , Hipercinesia/genética , Hipercinesia/metabolismo , Hipercinesia/fisiopatología , Masculino , Ratones , Ratones Transgénicos , Mutación/genética , Neuronas/patología , Bulbo Olfatorio/patología , Bulbo Olfatorio/fisiopatología , Trastornos Parkinsonianos/genética , alfa-Sinucleína/biosíntesis , alfa-Sinucleína/fisiologíaRESUMEN
Suicide is the most important incident in psychiatric disorders. Psychological pain and empathy to pain involves a neural network that involves the anterior cingulate cortex (ACC) and the anterior insula (AI). At the neuronal level, little is known about how complex emotions such as shame, guilt, self-derogation and social isolation, all of which feature suicidal behavior, are represented in the brain. Based on the observation that the ACC and the AI contain a large spindle-shaped cell type, referred to as von Economo neuron (VEN), which has dramatically increased in density during human evolution, and on growing evidence that VENs play a role in the pathophysiology of various neuropsychiatric disorders, including autism, psychosis and dementia, we examined the density of VENs in the ACC of suicide victims. The density of VENs was determined using cresyl violet-stained sections of the ACC of 39 individuals with psychosis (20 cases with schizophrenia, 19 with bipolar disorder). Nine subjects had died from suicide. Twenty specimen were available from the right, 19 from the left ACC. The density of VENs was significantly greater in the ACC of suicide victims with psychotic disorders compared with psychotic individuals who died from other causes. This effect was restricted to the right ACC. VEN density in the ACC seems to be increased in suicide victims with psychosis. This finding may support the assumption that VEN have a special role in emotion processing and self-evaluation, including negative self-appraisal.
Asunto(s)
Encéfalo/patología , Neuronas/patología , Trastornos Psicóticos/patología , Suicidio , Adulto , Trastorno Bipolar/patología , Demografía , Femenino , Giro del Cíngulo/patología , Humanos , Masculino , Persona de Mediana Edad , Esquizofrenia/patologíaRESUMEN
Retinitis pigmentosa (RP) is a group of human retinal disorders, with more than 100 genes involved in retinal degeneration. Canine and murine models are useful for investigating human RP based on known, naturally occurring mutations. In Schapendoes dogs, for example, a mutation in the CCDC66 gene has been shown to cause autosomal recessively inherited, generalized progressive retinal atrophy (gPRA), the canine counterpart to RP. Here, a novel mouse model with a disrupted Ccdc66 gene was investigated to reveal the function of protein CCDC66 and the pathogenesis of this form of gPRA. Homozygous Ccdc66 mutant mice lack retinal Ccdc66 RNA and protein expression. Light and electron microscopy reveal an initial degeneration of photoreceptors already at 13 days of age, followed by a slow, progressive retinal degeneration over months. Retinal dysfunction causes reduced scotopic a-wave amplitudes, declining from 1 to 7 months of age as well as an early reduction of the photopic b-wave at 1 month, improving slightly at 7 months, as evidenced by electroretinography. In the retina of the wild-type (WT) mouse, protein CCDC66 is present at highest levels after birth, followed by a decline until adulthood, suggesting a crucial role in early development. Protein CCDC66 is expressed predominantly in the developing rod outer segments as confirmed by subcellular analyses. These findings illustrate that the lack of protein CCDC66 causes early, slow progressive rod-cone dysplasia in the novel Ccdc66 mutant mouse model, thus providing a sound foundation for the development of therapeutic strategies.