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1.
Brain ; 145(6): 2092-2107, 2022 06 30.
Artículo en Inglés | MEDLINE | ID: mdl-35245368

RESUMEN

Synaptic impairment might precede neuronal degeneration in Parkinson's disease. However, the intimate mechanisms altering synaptic function by the accumulation of presynaptic α-synuclein in striatal dopaminergic terminals before dopaminergic death occurs, have not been elucidated. Our aim is to unravel the sequence of synaptic functional and structural changes preceding symptomatic dopaminergic cell death. As such, we evaluated the temporal sequence of functional and structural changes at striatal synapses before parkinsonian motor features appear in a rat model of progressive dopaminergic death induced by overexpression of the human mutated A53T α-synuclein in the substantia nigra pars compacta, a protein transported to these synapses. Sequential window acquisition of all theoretical mass spectra proteomics identified deregulated proteins involved first in energy metabolism and later, in vesicle cycling and autophagy. After protein deregulation and when α-synuclein accumulated at striatal synapses, alterations to mitochondrial bioenergetics were observed using a Seahorse XF96 analyser. Sustained dysfunctional mitochondrial bioenergetics was followed by a decrease in the number of dopaminergic terminals, morphological and ultrastructural alterations, and an abnormal accumulation of autophagic/endocytic vesicles inside the remaining dopaminergic fibres was evident by electron microscopy. The total mitochondrial population remained unchanged whereas the number of ultrastructurally damaged mitochondria increases as the pathological process evolved. We also observed ultrastructural signs of plasticity within glutamatergic synapses before the expression of motor abnormalities, such as a reduction in axospinous synapses and an increase in perforated postsynaptic densities. Overall, we found that a synaptic energetic failure and accumulation of dysfunctional organelles occur sequentially at the dopaminergic terminals as the earliest events preceding structural changes and cell death. We also identify key proteins involved in these earliest functional abnormalities that may be modulated and serve as therapeutic targets to counterbalance the degeneration of dopaminergic cells to delay or prevent the development of Parkinson's disease.


Asunto(s)
Enfermedad de Parkinson , Trastornos Parkinsonianos , Animales , Autofagia , Cuerpo Estriado/metabolismo , Dopamina/metabolismo , Neuronas Dopaminérgicas/metabolismo , Metabolismo Energético , Trastornos Parkinsonianos/metabolismo , Ratas , alfa-Sinucleína/metabolismo
2.
Mol Psychiatry ; 26(2): 629-644, 2021 02.
Artículo en Inglés | MEDLINE | ID: mdl-31911635

RESUMEN

ATP signaling and surface P2X4 receptors are upregulated selectively in neurons and/or glia in various CNS disorders including anxiety, chronic pain, epilepsy, ischemia, and neurodegenerative diseases. However, the cell-specific functions of P2X4 in pathological contexts remain elusive. To elucidate P2X4 functions, we created a conditional transgenic knock-in P2X4 mouse line (Floxed P2X4mCherryIN) allowing the Cre activity-dependent genetic swapping of the internalization motif of P2X4 by the fluorescent mCherry protein to prevent constitutive endocytosis of P2X4. By combining molecular, cellular, electrophysiological, and behavioral approaches, we characterized two distinct knock-in mouse lines expressing noninternalized P2X4mCherryIN either exclusively in excitatory forebrain neurons or in all cells natively expressing P2X4. The genetic substitution of wild-type P2X4 by noninternalized P2X4mCherryIN in both knock-in mouse models did not alter the sparse distribution and subcellular localization of P2X4 but increased the number of P2X4 receptors at the surface of the targeted cells mimicking the pathological increased surface P2X4 state. Increased surface P2X4 density in the hippocampus of knock-in mice altered LTP and LTD plasticity phenomena at CA1 synapses without affecting basal excitatory transmission. Moreover, these cellular events translated into anxiolytic effects and deficits in spatial memory. Our results show that increased surface density of neuronal P2X4 contributes to synaptic deficits and alterations in anxiety and memory functions consistent with the implication of P2X4 in neuropsychiatric and neurodegenerative disorders. Furthermore, these conditional P2X4mCherryIN knock-in mice will allow exploring the cell-specific roles of P2X4 in various physiological and pathological contexts.


Asunto(s)
Ansiedad , Memoria , Receptores Purinérgicos P2X4 , Sinapsis , Animales , Ansiedad/genética , Técnicas de Sustitución del Gen , Hipocampo , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Plasticidad Neuronal , Neuronas , Receptores Purinérgicos P2X4/genética
3.
J Cell Biochem ; 117(12): 2737-2747, 2016 12.
Artículo en Inglés | MEDLINE | ID: mdl-27070919

RESUMEN

Matrix remodeling is a key feature of glomerulosclerosis secondary to diabetes or hypertension. Podocytes contribute to glomerular basement membrane (GBM) turnover by producing matrix components and matrix remodelling enzymes, including matrix metalloproteinases (MMPs). The CD40/CD154 signaling pathway modulates matrix remodeling through the synthesis of MMPs and tissue inhibitors of MMPs. Platelets are a primary blood reservoir of CD154. Here we studied, the impact of the CD154/CD40 pathway on MMP-9 expression by cultured human podocytes. The role of CD40/CD154 was evaluated upon exposure of podocytes to recombinant human CD154 (rhCD154) or activated platelet supernatants from healthy human subjects. We first showed by protein and mRNA expression that CD40 was synthesized by podocytes and detectable on kidney tissue sections. CD40 expression was acquired during podocyte differentiation and enhanced upon exposure to rhCD154. In podocytes, rhCD154 induced an increase of MMP-9 production as shown by RT-PCR, Western blot and and gelatin zymography. Activated platelet supernatants induced MMP-9 mRNA synthesis in podocytes, an effect reduced by anti-CD40 antibody. Our results underscore a potential role for platelets through the CD40/CD154 signaling pathway in the control of GBM synthesis and degradation, via its regulatory role on MMP-9 production. CD154 secretion by activated platelets may contribute to GBM alterations in proteinuric nephropathies. J. Cell. Biochem. 117: 2737-2747, 2016. © 2016 Wiley Periodicals, Inc.


Asunto(s)
Plaquetas/metabolismo , Antígenos CD40/metabolismo , Ligando de CD40/farmacología , Metaloproteinasa 9 de la Matriz/metabolismo , Podocitos/metabolismo , Plaquetas/efectos de los fármacos , Plaquetas/patología , Western Blotting , Antígenos CD40/genética , Diferenciación Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Humanos , Metaloproteinasa 9 de la Matriz/genética , Podocitos/efectos de los fármacos , Podocitos/patología , ARN Mensajero/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa
4.
Proc Natl Acad Sci U S A ; 110(44): 18005-10, 2013 Oct 29.
Artículo en Inglés | MEDLINE | ID: mdl-24127604

RESUMEN

Dopamine is a powerful modulator of glutamatergic neurotransmission and NMDA receptor-dependent synaptic plasticity. Although several intracellular cascades participating in this functional dialogue have been identified over the last few decades, the molecular crosstalk between surface dopamine and glutamate NMDA receptor (NMDAR) signaling still remains poorly understood. Using a combination of single-molecule detection imaging and electrophysiology in live hippocampal neurons, we demonstrate here that dopamine D1 receptors (D1Rs) and NMDARs form dynamic surface clusters in the vicinity of glutamate synapses. Strikingly, D1R activation or D1R/NMDAR direct interaction disruption decreases the size of these clusters, increases NMDAR synaptic content through a fast lateral redistribution of the receptors, and favors long-term synaptic potentiation. Together, these data demonstrate the presence of dynamic D1R/NMDAR perisynaptic reservoirs favoring a rapid and bidirectional surface crosstalk between receptors and set the plasma membrane as the primary stage of the dopamine-glutamate interplay.


Asunto(s)
Hipocampo/citología , Receptor Cross-Talk/fisiología , Receptores de Dopamina D1/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Transducción de Señal/fisiología , Sinapsis/metabolismo , Animales , Hipocampo/metabolismo , Procesamiento de Imagen Asistido por Computador , Inmunohistoquímica , Microscopía Electrónica , Modelos Neurológicos , Nanopartículas , Técnicas de Placa-Clamp , Ratas , Ratas Sprague-Dawley , Ratas Wistar , Receptores de Glutamato/metabolismo
5.
Neurobiol Dis ; 78: 77-87, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-25766677

RESUMEN

Among the mechanisms underlying the development of L-dopa-induced dyskinesia (LID) in Parkinson's disease, complex alterations in dopamine signaling in D1 receptor (D1R)-expressing medium spiny striatal neurons have been unraveled such as, but not limited to, dysregulation of D1R expression, lateral diffusion, intraneuronal trafficking, subcellular localization and desensitization, leading to a pathological anchorage of D1R at the plasma membrane. Such anchorage is partly due to a decreased proteasomal activity that is specific of the L-dopa-exposed dopamine-depleted striatum, results from D1R activation and feeds-back the D1R exaggerated cell surface abundance. The precise mechanisms by which L-dopa affects striatal proteasome activity remained however unknown. We here show, in a series of in vitro ex vivo and in vivo models, that such rapid modulation of striatal proteasome activity intervenes through D1R-mediated disassembly of the 26S proteasome rather than change in transcription or translation of proteasome or proteasome subunits intraneuronal relocalization.


Asunto(s)
Cuerpo Estriado/enzimología , Trastornos Parkinsonianos/metabolismo , Complejo de la Endopetidasa Proteasomal/metabolismo , Receptores de Dopamina D1/metabolismo , Animales , Benzazepinas/farmacología , Células Cultivadas , Cuerpo Estriado/efectos de los fármacos , Cuerpo Estriado/metabolismo , Agonistas de Dopamina/farmacología , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Neuronas/efectos de los fármacos , Neuronas/metabolismo , Trastornos Parkinsonianos/enzimología , Complejo de la Endopetidasa Proteasomal/efectos de los fármacos , Ratas Sprague-Dawley
6.
Proc Natl Acad Sci U S A ; 109(24): 9611-6, 2012 Jun 12.
Artículo en Inglés | MEDLINE | ID: mdl-22647602

RESUMEN

Parkinson disease (PD) is a progressive neurodegenerative disorder pathologically characterized by the loss of dopaminergic neurons from the substantia nigra pars compacta and the presence, in affected brain regions, of protein inclusions named Lewy bodies (LBs). The ATP13A2 gene (locus PARK9) encodes the protein ATP13A2, a lysosomal type 5 P-type ATPase that is linked to autosomal recessive familial parkinsonism. The physiological function of ATP13A2, and hence its role in PD, remains to be elucidated. Here, we show that PD-linked mutations in ATP13A2 lead to several lysosomal alterations in ATP13A2 PD patient-derived fibroblasts, including impaired lysosomal acidification, decreased proteolytic processing of lysosomal enzymes, reduced degradation of lysosomal substrates, and diminished lysosomal-mediated clearance of autophagosomes. Similar alterations are observed in stable ATP13A2-knockdown dopaminergic cell lines, which are associated with cell death. Restoration of ATP13A2 levels in ATP13A2-mutant/depleted cells restores lysosomal function and attenuates cell death. Relevant to PD, ATP13A2 levels are decreased in dopaminergic nigral neurons from patients with PD, in which ATP13A2 mostly accumulates within Lewy bodies. Our results unravel an instrumental role of ATP13A2 deficiency on lysosomal function and cell viability and demonstrate the feasibility and therapeutic potential of modulating ATP13A2 levels in the context of PD.


Asunto(s)
Adenosina Trifosfatasas/metabolismo , Lisosomas/metabolismo , Enfermedad de Parkinson/patología , Línea Celular , Técnicas de Silenciamiento del Gen , Humanos , Enfermedad de Parkinson/enzimología , Enfermedad de Parkinson/metabolismo
7.
J Neurosci ; 33(29): 11960-71, 2013 Jul 17.
Artículo en Inglés | MEDLINE | ID: mdl-23864683

RESUMEN

Enhanced motivation to take drugs is a central characteristic of addiction, yet the neural underpinning of this maladaptive behavior is still largely unknown. Here, we report a D1-like dopamine receptor (DRD1)-mediated long-term potentiation of GABAA-IPSCs (D1-LTPGABA) in the oval bed nucleus of the stria terminalis that was positively correlated with motivation to self-administer cocaine in rats. Likewise, in vivo intra-oval bed nucleus of the stria terminalis DRD1 pharmacological blockade reduced lever pressing for cocaine more effectively in rats showing enhanced motivation toward cocaine. D1-LTPGABA resulted from enhanced function and expression of G-protein-independent DRD1 coupled to c-Src tyrosine kinases and required local release of neurotensin. There was no D1-LTPGABA in rats that self-administered sucrose, in those with limited cocaine self-administration experience, or in those that received cocaine passively (yoked). Therefore, our study reveals a novel neurophysiological mechanism contributing to individual motivation to self-administer cocaine, a critical psychobiological element of compulsive drug use and addiction.


Asunto(s)
Cocaína/administración & dosificación , Inhibidores de Captación de Dopamina/administración & dosificación , Potenciación a Largo Plazo/fisiología , Motivación/fisiología , Receptores de Dopamina D1/metabolismo , Sinapsis/fisiología , Ácido gamma-Aminobutírico/metabolismo , Animales , Dopamina/metabolismo , Potenciales Postsinápticos Inhibidores/efectos de los fármacos , Potenciales Postsinápticos Inhibidores/fisiología , Potenciación a Largo Plazo/efectos de los fármacos , Masculino , Motivación/efectos de los fármacos , Neurotensina/metabolismo , Ratas , Ratas Long-Evans , Refuerzo en Psicología , Autoadministración , Núcleos Septales/efectos de los fármacos , Núcleos Septales/fisiología , Sinapsis/efectos de los fármacos
8.
Sci Rep ; 14(1): 9710, 2024 04 27.
Artículo en Inglés | MEDLINE | ID: mdl-38678103

RESUMEN

Among the several animal models of α-synucleinopathies, the well-known viral vector-mediated delivery of wild-type or mutated (A53T) α-synuclein requires new tools to increase the lesion in mice and follow up in vivo expression. To this end, we developed a bioluminescent expression reporter of the human A53T-α-synuclein gene using the NanoLuc system into an AAV2/9, embedded or not in a fibroin solution to stabilise its expression in space and time. We first verified the expression of the fused protein in vitro on transfected cells by bioluminescence and Western blotting. Next, two groups of C57Bl6Jr mice were unilaterally injected with the AAV-NanoLuc-human-A53T-α-synuclein above the substantia nigra combined (or not) with fibroin. We first show that the in vivo cerebral bioluminescence signal was more intense in the presence of fibroin. Using immunohistochemistry, we find that the human-A53T-α-synuclein protein is more restricted to the ipsilateral side with an overall greater magnitude of the lesion when fibroin was added. However, we also detected a bioluminescence signal in peripheral organs in both conditions, confirmed by the presence of viral DNA corresponding to the injected AAV in the liver using qPCR.


Asunto(s)
Dependovirus , Fibroínas , Vectores Genéticos , Mediciones Luminiscentes , Ratones Endogámicos C57BL , alfa-Sinucleína , Animales , alfa-Sinucleína/metabolismo , alfa-Sinucleína/genética , Dependovirus/genética , Humanos , Ratones , Mediciones Luminiscentes/métodos , Vectores Genéticos/genética , Fibroínas/metabolismo , Sistema Nervioso Central/metabolismo , Masculino , Luciferasas/metabolismo , Luciferasas/genética
9.
Nat Commun ; 15(1): 7142, 2024 Aug 21.
Artículo en Inglés | MEDLINE | ID: mdl-39164260

RESUMEN

The Insula functions as a multisensory relay involved in socio-emotional processing with projections to sensory, cognitive, emotional, and motivational regions. Notably, the interhemispheric projection from the Insula to the contralateral Insula is a robust yet underexplored connection. Using viral-based tracing neuroanatomy, ex vivo and in vivo electrophysiology, in vivo fiber photometry along with targeted circuit manipulation, we elucidated the nature and role of InsulaIns communication in social and anxiety processing in mice. In this study, we 1) characterized the anatomical and molecular profile of the InsulaIns neurons, 2) demonstrated that stimulation of this neuronal subpopulation induces excitation in the Insula interhemispheric circuit, 3) revealed that InsulaIns neurons are essential for social discrimination after 24 h of isolation in male mice. In conclusion, our findings highlight InsulaIns neurons as a distinct class of neurons within the insula and offer new insights into the neuronal mechanisms underlying social behavior.


Asunto(s)
Corteza Insular , Neuronas , Conducta Social , Aislamiento Social , Animales , Masculino , Neuronas/fisiología , Aislamiento Social/psicología , Ratones , Corteza Insular/fisiología , Ratones Endogámicos C57BL , Conducta Animal/fisiología , Ansiedad
10.
Brain ; 134(Pt 8): 2321-38, 2011 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-21742735

RESUMEN

Morphine is endogenously synthesized in the central nervous system and endogenous dopamine is thought to be necessary for endogenous morphine formation. As Parkinson's disease results from the loss of dopamine and is associated with central pain, we considered how endogenous morphine is regulated in the untreated and l-DOPA-treated parkinsonian brain. However, as the cellular origin and overall distribution of endogenous morphine remains obscure in the pathological adult brain, we first characterized the distribution of endogenous morphine-like compound immunoreactive cells in the rat striatum. We then studied changes in the endogenous morphine-like compound immunoreactivity of medium spiny neurons in normal, Parkinson's disease-like and l-DOPA-treated Parkinson's disease-like conditions in experimental (rat and monkey) and human Parkinson's disease. Our results reveal an unexpected dramatic upregulation of neuronal endogenous morphine-like compound immunoreactivity and levels in experimental and human Parkinson's disease, only partially normalized by l-DOPA treatment. Our data suggest that endogenous morphine formation is more complex than originally proposed and that the parkinsonian brain experiences a dramatic upregulation of endogenous morphine immunoreactivity. The functional consequences of such endogenous morphine upregulation are as yet unknown, but based upon the current knowledge of morphine signalling, we hypothesize that it is involved in fatigue, depression and pain symptoms experienced by patients with Parkinson's disease.


Asunto(s)
Encéfalo/metabolismo , Trastornos Parkinsonianos/metabolismo , 1-Metil-4-fenil-1,2,3,6-Tetrahidropiridina/farmacología , Anciano , Análisis de Varianza , Animales , Encéfalo/efectos de los fármacos , Encéfalo/patología , Encéfalo/ultraestructura , Colina O-Acetiltransferasa/metabolismo , Cromatografía Líquida de Alta Presión/métodos , Dendritas/metabolismo , Dendritas/ultraestructura , Modelos Animales de Enfermedad , Dopamina/metabolismo , Dopaminérgicos/farmacología , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática/deficiencia , Proteínas de Transporte de Dopamina a través de la Membrana Plasmática/metabolismo , Fosfoproteína 32 Regulada por Dopamina y AMPc/metabolismo , Inhibidores Enzimáticos/farmacología , Ensayo de Inmunoadsorción Enzimática/métodos , Femenino , Lateralidad Funcional , Regulación de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica/genética , Proteína Ácida Fibrilar de la Glía/metabolismo , Glutamato Descarboxilasa/metabolismo , Humanos , Levodopa/farmacología , Macaca fascicularis , Masculino , Haz Prosencefálico Medial/efectos de los fármacos , Haz Prosencefálico Medial/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Microscopía Inmunoelectrónica/métodos , Persona de Mediana Edad , Factores de Crecimiento Nervioso/metabolismo , Compuestos Orgánicos/metabolismo , Oxidopamina/efectos adversos , Trastornos Parkinsonianos/inducido químicamente , Trastornos Parkinsonianos/tratamiento farmacológico , Trastornos Parkinsonianos/patología , Cambios Post Mortem , Ratas , Ratas Sprague-Dawley , Receptores de Dopamina D2/metabolismo , Subunidad beta de la Proteína de Unión al Calcio S100 , Proteínas S100/metabolismo , Espectrometría de Masas en Tándem , alfa-Metiltirosina/farmacología
11.
Mol Neurobiol ; 59(10): 6245-6259, 2022 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-35915387

RESUMEN

Parkinson's disease (PD) is pathologically characterized by intracellular α-synuclein-rich protein aggregates, named Lewy bodies (LB), and by the progressive loss of dopaminergic neurons in the substantia nigra. Several heavy metals, including zinc (Zn), have been suggested to play a role in PD progression, although the exact role of Zn in neurodegeneration remains to be fully elucidated. To address this gap, we investigated the effects of Zn modulation on the progression of degeneration in mice injected with PD patient-derived LB-extracts carrying toxic α-synuclein aggregates. Zn modulation was achieved using either a clioquinol-enriched diet, a Zn ionophore that redistributes cellular Zn, or a Zn-enriched diet that increases Zn levels. Clioquinol treatment significantly prevented dopaminergic neurodegeneration and reduced α-synuclein-associated pathology in LB-injected mice, while no differences were observed with Zn supplementation. Biochemical analyses further demonstrate that the expression levels of vesicle-specific Zn transporter ZnT3 in the striatum of LB-injected mice treated with clioquinol were decreased, suggesting an intracellular redistribution of Zn. Additionally, we found that clioquinol modulates the autophagy-lysosomal pathway by enhancing lysosomal redistribution within the neuronal compartments. Collectively, we found that in vivo pharmacological chelation of Zn, by dampening Zn-mediated cytotoxicity, can result in an overall attenuation of PD-linked lysosomal alterations and dopaminergic neurodegeneration. The results support zinc chelation as a disease-modifying strategy for treating PD.


Asunto(s)
Clioquinol , Enfermedad de Parkinson , Animales , Encéfalo/metabolismo , Clioquinol/farmacología , Clioquinol/uso terapéutico , Dopamina/metabolismo , Neuronas Dopaminérgicas/metabolismo , Humanos , Ionóforos/farmacología , Ionóforos/uso terapéutico , Ratones , Enfermedad de Parkinson/patología , Sustancia Negra/patología , Extractos de Tejidos , Zinc/metabolismo , alfa-Sinucleína/metabolismo
12.
Aging Cell ; 21(4): e13584, 2022 04.
Artículo en Inglés | MEDLINE | ID: mdl-35318803

RESUMEN

Parkinson's disease (PD) is an age-related neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra, associated with the accumulation of misfolded α-synuclein and lysosomal impairment, two events deemed interconnected. Protein aggregation is linked to defects in degradation systems such as the autophagy-lysosomal pathway, while lysosomal dysfunction is partly related to compromised acidification. We have recently proven that acidic nanoparticles (aNPs) can re-acidify lysosomes and ameliorate neurotoxin-mediated dopaminergic neurodegeneration in mice. However, no lysosome-targeted approach has yet been tested in synucleinopathy models in vivo. Here, we show that aNPs increase α-synuclein degradation through enhancing lysosomal activity in vitro. We further demonstrate in vivo that aNPs protect nigral dopaminergic neurons from cell death, ameliorate α-synuclein pathology, and restore lysosomal function in mice injected with PD patient-derived Lewy body extracts carrying toxic α-synuclein aggregates. Our results support lysosomal re-acidification as a disease-modifying strategy for the treatment of PD and other age-related proteinopathies.


Asunto(s)
Nanopartículas , Enfermedad de Parkinson , Animales , Humanos , Lisosomas/metabolismo , Ratones , Enfermedad de Parkinson/metabolismo , Sustancia Negra/metabolismo , alfa-Sinucleína/metabolismo
13.
J Neurosci ; 29(15): 4829-35, 2009 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-19369551

RESUMEN

We have associated behavioral, pharmacological, and quantitative immunohistochemical study in a rat analog of l-DOPA-induced dyskinesia to understand whether alterations in dopamine receptor fate in striatal neurons may be involved in mechanisms leading to movement abnormalities. Detailed analysis at the ultrastructural level demonstrates specific alterations of dopamine D(1) receptor (D(1)R) subcellular localization in striatal medium spiny neurons in l-DOPA-treated 6-hydroxydopamine-lesioned rats with abnormal involuntary movements (AIMs). This includes exaggerated D(1)R expression at the plasma membrane. However, D(1)R retains ability of internalization, as a challenge with the potent D(1)R agonist SKF-82958 induces a strong decrease of labeling at membrane in animals with AIMs. Since a functional cross talk between D(1)R and D(3)R has been suggested, we hypothesized that their coactivation by dopamine derived from l-DOPA might anchor D(1)R at the membrane. Accordingly, cotreatment with l-DOPA and the D(3)R antagonist ST 198 restores normal level of membrane-bound D(1)R. Together, these results demonstrate that AIMs are related to abnormal D(1)R localization at the membrane and intraneuronal trafficking dysregulation, and suggest that strategies aiming at disrupting the D(1)R-D(3)R cross talk might reduce l-DOPA-induced dyskinesia by reducing D(1)R availability at the membrane.


Asunto(s)
Discinesia Inducida por Medicamentos/metabolismo , Levodopa/análogos & derivados , Levodopa/toxicidad , Neuronas/metabolismo , Receptores de Dopamina D1/metabolismo , Animales , Discinesia Inducida por Medicamentos/patología , Masculino , Neuronas/efectos de los fármacos , Neuronas/ultraestructura , Trastornos Parkinsonianos/metabolismo , Trastornos Parkinsonianos/patología , Ratas , Ratas Sprague-Dawley , Receptor Cross-Talk/efectos de los fármacos , Receptores de Dopamina D1/ultraestructura , Receptores de Dopamina D3/agonistas , Receptores de Dopamina D3/antagonistas & inhibidores , Receptores de Dopamina D3/metabolismo
14.
Cells ; 9(11)2020 10 29.
Artículo en Inglés | MEDLINE | ID: mdl-33138150

RESUMEN

The synucleinopathy underlying multiple system atrophy (MSA) is characterized by the presence of abundant amyloid inclusions containing fibrillar α-synuclein (α-syn) aggregates in the brains of the patients and is associated with an extensive neurodegeneration. In contrast to Parkinson's disease (PD) where the pathological α-syn aggregates are almost exclusively neuronal, the α-syn inclusions in MSA are principally observed in oligodendrocytes (OLs) where they form glial cytoplasmic inclusions (GCIs). This is intriguing because differentiated OLs express low levels of α-syn, yet pathogenic amyloid α-syn seeds require significant amounts of α-syn monomers to feed their fibrillar growth and to eventually cause the buildup of cytopathological inclusions. One of the transgenic mouse models of this disease is based on the targeted overexpression of human α-syn in OLs using the PLP promoter. In these mice, the histopathological images showing a rapid emergence of S129-phosphorylated α-syn inside OLs are considered as equivalent to GCIs. Instead, we report here that they correspond to the accumulation of phosphorylated α-syn monomers/oligomers and not to the appearance of the distinctive fibrillar α-syn aggregates that are present in the brains of MSA or PD patients. In spite of a propensity to co-sediment with myelin sheath contaminants, the phosphorylated forms found in the brains of the transgenic animals are soluble (>80%). In clear contrast, the phosphorylated species present in the brains of MSA and PD patients are insoluble fibrils (>95%). Using primary cultures of OLs from PLP-αSyn mice we observed a variable association of S129-phosphorylated α-syn with the cytoplasmic compartment, the nucleus and with membrane domains suggesting that OLs functionally accommodate the phospho-α-syn deriving from experimental overexpression. Yet and while not taking place spontaneously, fibrillization can be seeded in these primary cultures by challenging the OLs with α-syn preformed fibrils (PFFs). This indicates that a targeted overexpression of α-syn does not model GCIs in mice but that it can provide a basis for seeding aggregation using PFFs. This approach could help establishing a link between α-syn aggregation and the development of a clinical phenotype in these transgenic animals.


Asunto(s)
Atrofia de Múltiples Sistemas/metabolismo , Atrofia de Múltiples Sistemas/patología , Oligodendroglía/metabolismo , Agregado de Proteínas , alfa-Sinucleína/metabolismo , Amiloide/metabolismo , Animales , Encéfalo/metabolismo , Células Cultivadas , Humanos , Ratones Endogámicos C57BL , Ratones Transgénicos , Modelos Animales , Proteína Básica de Mielina/metabolismo , Proteína Proteolipídica de la Mielina/genética , Neuronas/metabolismo , Enfermedad de Parkinson/patología , Fosforilación , Fosfoserina/metabolismo , Regiones Promotoras Genéticas/genética , Multimerización de Proteína
15.
Nat Commun ; 11(1): 3440, 2020 07 10.
Artículo en Inglés | MEDLINE | ID: mdl-32651387

RESUMEN

In recent years, exploration of the brain extracellular space (ECS) has made remarkable progress, including nanoscopic characterizations. However, whether ECS precise conformation is altered during brain pathology remains unknown. Here we study the nanoscale organization of pathological ECS in adult mice under degenerative conditions. Using electron microscopy in cryofixed tissue and single nanotube tracking in live brain slices combined with super-resolution imaging analysis, we find enlarged ECS dimensions and increased nanoscale diffusion after α-synuclein-induced neurodegeneration. These animals display a degraded hyaluronan matrix in areas close to reactive microglia. Furthermore, experimental hyaluronan depletion in vivo reduces dopaminergic cell loss and α-synuclein load, induces microgliosis and increases ECS diffusivity, highlighting hyaluronan as diffusional barrier and local tissue organizer. These findings demonstrate the interplay of ECS, extracellular matrix and glia in pathology, unraveling ECS features relevant for the α-synuclein propagation hypothesis and suggesting matrix manipulation as a disease-modifying strategy.


Asunto(s)
Encéfalo/metabolismo , Espacio Extracelular/metabolismo , Ácido Hialurónico/metabolismo , Sinucleinopatías/metabolismo , Animales , Masculino , Ratones , Ratones Endogámicos C57BL , Microglía/metabolismo , Microglía/ultraestructura , Microscopía Electrónica , Enfermedad de Parkinson/metabolismo , Espectroscopía Infrarroja Corta
16.
Sci Adv ; 6(40)2020 10.
Artículo en Inglés | MEDLINE | ID: mdl-33008896

RESUMEN

The conformational strain diversity characterizing α-synuclein (α-syn) amyloid fibrils is thought to determine the different clinical presentations of neurodegenerative diseases underpinned by a synucleinopathy. Experimentally, various α-syn fibril polymorphs have been obtained from distinct fibrillization conditions by altering the medium constituents and were selected by amyloid monitoring using the probe thioflavin T (ThT). We report that, concurrent with classical ThT-positive products, fibrillization in saline also gives rise to polymorphs invisible to ThT (τ-). The generation of τ- fibril polymorphs is stochastic and can skew the apparent fibrillization kinetics revealed by ThT. Their emergence has thus been ignored so far or mistaken for fibrillization inhibitions/failures. They present a yet undescribed atomic organization and show an exacerbated propensity toward self-replication in cortical neurons, and in living mice, their injection into the substantia nigra pars compacta triggers a synucleinopathy that spreads toward the dorsal striatum, the nucleus accumbens, and the insular cortex.


Asunto(s)
Sinucleinopatías , alfa-Sinucleína , Amiloide , Animales , Benzotiazoles , Ratones , Neuronas
17.
JCI Insight ; 4(16)2019 08 22.
Artículo en Inglés | MEDLINE | ID: mdl-31434803

RESUMEN

The synucleinopathies Parkinson's disease (PD) and Multiple system atrophy (MSA) - characterized by α-synuclein intracytoplasmic inclusions into, respectively, neurons and oligodendrocytes - are associated with impairment of the autophagy-lysosomal pathways (ALP). Increased expression of the master regulator of ALP, transcription factor EB (TFEB), is hypothesized to promote the clearance of WT α-synuclein and survival of dopaminergic neurons. Here, we explore the efficacy of targeted TFEB overexpression either in neurons or oligodendrocytes to reduce the pathological burden of α-synuclein in a PD rat model and a MSA mouse model. While TFEB neuronal expression was sufficient to prevent neurodegeneration in the PD model, we show that only TFEB oligodendroglial overexpression leads to neuroprotective effects in the MSA model. These beneficial effects were associated with a decreased accumulation of α-synuclein into oligodendrocytes through recovery of the ALP machinery. Our study demonstrates that the cell type where α-synuclein aggregates dictates the target of TFEB overexpression in order to be protective, paving the way for adapted therapies.


Asunto(s)
Factores de Transcripción Básicos con Cremalleras de Leucinas y Motivos Hélice-Asa-Hélice/metabolismo , Atrofia de Múltiples Sistemas/patología , Enfermedad de Parkinson/patología , Anciano , Animales , Autofagia , Encéfalo/metabolismo , Línea Celular Tumoral , Modelos Animales de Enfermedad , Células HEK293 , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Atrofia de Múltiples Sistemas/metabolismo , Oligodendroglía/metabolismo , Enfermedad de Parkinson/metabolismo , Ratas , Ratas Sprague-Dawley , alfa-Sinucleína/metabolismo
18.
EMBO Mol Med ; 11(1)2019 01.
Artículo en Inglés | MEDLINE | ID: mdl-30552094

RESUMEN

Dopamine D2 receptor signaling is central for striatal function and movement, while abnormal activity is associated with neurological disorders including the severe early-onset DYT1 dystonia. Nevertheless, the mechanisms that regulate D2 receptor signaling in health and disease remain poorly understood. Here, we identify a reduced D2 receptor binding, paralleled by an abrupt reduction in receptor protein level, in the striatum of juvenile Dyt1 mice. This occurs through increased lysosomal degradation, controlled by competition between ß-arrestin 2 and D2 receptor binding proteins. Accordingly, we found lower levels of striatal RGS9-2 and spinophilin. Further, we show that genetic depletion of RGS9-2 mimics the D2 receptor loss of DYT1 dystonia striatum, whereas RGS9-2 overexpression rescues both receptor levels and electrophysiological responses in Dyt1 striatal neurons. This work uncovers the molecular mechanism underlying D2 receptor downregulation in Dyt1 mice and in turn explains why dopaminergic drugs lack efficacy in DYT1 patients despite significant evidence for striatal D2 receptor dysfunction. Our data also open up novel avenues for disease-modifying therapeutics to this incurable neurological disorder.


Asunto(s)
Cuerpo Estriado/patología , Distonía Muscular Deformante/patología , Distonía Muscular Deformante/fisiopatología , Chaperonas Moleculares/genética , Proteínas RGS/análisis , Receptores de Dopamina D2/análisis , Transducción de Señal , Animales , Modelos Animales de Enfermedad , Expresión Génica , Técnicas de Silenciamiento del Gen , Ratones Endogámicos C57BL , Proteínas de Microfilamentos/análisis , Proteínas del Tejido Nervioso/análisis , Proteínas RGS/genética
19.
Ultrastruct Pathol ; 32(5): 178-83, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-18958789

RESUMEN

Human telomerase comprises a catalytic protein subunit (hTERT) and an RNA subunit (hTR). Telomerase extends chromosome ends in compensation for the attrition of the telomeres during replication. In this work, the authors explore the expression of hTERT and hTR in neutrophils, respectively by immunochemistry techniques and in situ hybridization. hTERT was strongly expressed in neutrophils cytoplasm. The ultrastructural study showed that the gold particles were not associated with specific organelles but scattered in the cytosol. hTR was not expressed. hTERT is expressed in the cytoplasm of neutrophils, but its roles-eventually extratelomeric effects-remain to be elucidated.


Asunto(s)
Citoplasma/enzimología , Microscopía Inmunoelectrónica , Neutrófilos/enzimología , Telomerasa/análisis , Citoplasma/ultraestructura , Humanos , Hibridación in Situ , Hígado/enzimología , Hígado/ultraestructura , Neutrófilos/ultraestructura , ARN , ARN Largo no Codificante , ARN no Traducido/análisis , Vejiga Urinaria/enzimología , Vejiga Urinaria/ultraestructura
20.
Neurosci Lett ; 419(3): 273-7, 2007 Jun 04.
Artículo en Inglés | MEDLINE | ID: mdl-17498877

RESUMEN

Dopaminergic receptors of the D1 type are highly expressed in the dorsal striatum and nucleus accumbens. In the dorsal striatum, they are rarely observed on presynaptic terminals. However, their subcellular localization in the nucleus accumbens core and shell had not been compared to that of dorsal striatum. Here we investigated the subcellular localization of D1 receptors in these three brain regions using immunogold labeling and electron microscopy. We showed that, among all presynaptic terminals forming asymmetric contact with dendritic processes, the percentage of D1R immunoreactive terminals was low in the dorsal striatum (8.2%), but reached in the nucleus accumbens core and shell 25.5 and 29%, respectively. These observations are consistent with electrophysiological studies, which showed that D1 stimulation inhibits the response of target neurons to glutamatergic input via presynaptic mechanisms in the nucleus accumbens but not in the dorsal striatum.


Asunto(s)
Cuerpo Estriado/ultraestructura , Núcleo Accumbens/ultraestructura , Receptores de Dopamina D1/ultraestructura , Animales , Inmunohistoquímica , Masculino , Microscopía Electrónica de Transmisión , Terminales Presinápticos/ultraestructura , Ratas , Ratas Sprague-Dawley
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