Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 39
Filtrar
Más filtros

Banco de datos
Tipo del documento
Intervalo de año de publicación
1.
Brain ; 143(6): 1780-1797, 2020 06 01.
Artículo en Inglés | MEDLINE | ID: mdl-32428221

RESUMEN

Transportation of key proteins via extracellular vesicles has been recently implicated in various neurodegenerative disorders, including Parkinson's disease, as a new mechanism of disease spreading and a new source of biomarkers. Extracellular vesicles likely to be derived from the brain can be isolated from peripheral blood and have been reported to contain higher levels of α-synuclein (α-syn) in Parkinson's disease patients. However, very little is known about extracellular vesicles in multiple system atrophy, a disease that, like Parkinson's disease, involves pathological α-syn aggregation, though the process is centred around oligodendrocytes in multiple system atrophy. In this study, a novel immunocapture technology was developed to isolate blood CNPase-positive, oligodendrocyte-derived enriched microvesicles (OEMVs), followed by fluorescent nanoparticle tracking analysis and assessment of α-syn levels contained within the OEMVs. The results demonstrated that the concentrations of OEMVs were significantly lower in multiple system atrophy patients, compared to Parkinson's disease patients and healthy control subjects. It is also noted that the population of OEMVs involved was mainly in the size range closer to that of exosomes, and that the average α-syn concentrations (per vesicle) contained in these OEMVs were not significantly different among the three groups. The phenomenon of reduced OEMVs was again observed in a transgenic mouse model of multiple system atrophy and in primary oligodendrocyte cultures, and the mechanism involved was likely related, at least in part, to an α-syn-mediated interference in the interaction between syntaxin 4 and VAMP2, leading to the dysfunction of the SNARE complex. These results suggest that reduced OEMVs could be an important mechanism related to pathological α-syn aggregation in oligodendrocytes, and the OEMVs found in peripheral blood could be further explored for their potential as multiple system atrophy biomarkers.


Asunto(s)
Atrofia de Múltiples Sistemas/fisiopatología , Oligodendroglía/metabolismo , Proteínas SNARE/metabolismo , Anciano , Animales , Secreciones Corporales/metabolismo , Encéfalo/patología , Micropartículas Derivadas de Células/inmunología , Micropartículas Derivadas de Células/metabolismo , Modelos Animales de Enfermedad , Exosomas/metabolismo , Exosomas/fisiología , Femenino , Humanos , Masculino , Ratones , Ratones Transgénicos , Persona de Mediana Edad , Neuronas/metabolismo , Enfermedad de Parkinson/patología , Proteínas SNARE/fisiología , alfa-Sinucleína/metabolismo
2.
Neurobiol Dis ; 103: 101-112, 2017 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-28411117

RESUMEN

Synucleinopathies are a group of diseases characterized by the presence of intracellular protein aggregates containing α-synuclein (α-syn). While α-syn aggregates have been shown to induce multimodal cellular dysfunctions, uptake and transport mechanisms remain unclear. Using high-content imaging on cortical neurons and astrocytes, we here define the kinetics of neuronal and astrocytic abnormalities induced by human-derived α-syn aggregates grounding the use of such system to identify and test putative therapeutic compounds. We then aimed at characterizing uptake and transport mechanisms using primary cultures of cortical neurons and astrocytes either in single well or in microfluidic chambers allowing connection between cells and cell-types. We report that astrocytes take up α-syn-aggregates far more efficiently than neurons through an endocytic event. We also highlight that active α-syn transport occurs between cells and any cell-types. Of special interest regarding the disease, we also show that uptake and spreading of α-syn from astrocytes to neurons can lead to neuronal death. Altogether, we here show that patients-derived α-synuclein aggregates, which are taken up by neurons and astrocytes, induce a differential endogenous response in the two cell types including a peculiar astrocytic toxic gain-of-function that leads to neuronal death.


Asunto(s)
Astrocitos/metabolismo , Encéfalo/metabolismo , Cuerpos de Lewy/metabolismo , Neuronas/metabolismo , Enfermedad de Parkinson/metabolismo , alfa-Sinucleína/metabolismo , Animales , Astrocitos/efectos de los fármacos , Astrocitos/patología , Encéfalo/efectos de los fármacos , Encéfalo/patología , Células Cultivadas , Femenino , Humanos , Cuerpos de Lewy/patología , Neuronas/efectos de los fármacos , Neuronas/patología , Enfermedad de Parkinson/patología , Embarazo , Ratas , Ratas Sprague-Dawley , alfa-Sinucleína/toxicidad
3.
Oncologist ; 19(12): 1227-8, 2014 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-25355844

RESUMEN

BACKGROUND: Preclinical studies demonstrated that non-nucleoside reverse transcriptase inhibitors used for the treatment of HIV could antagonize tumor development. This led us to assess the efficacy of efavirenz in patients with metastatic castration-resistant prostate cancer (mCRPC) in a multicenter phase II study. METHODS: We used a Simon two-stage design and a 3-month prostate-specific antigen (PSA) nonprogression rate of 40% as a primary objective. Patients received 600 mg efavirenz daily with the possibility of a dose increase in case of PSA progression. Exploratory analyses included pharmacokinetics of efavirenz plasma concentrations and correlations with clinical outcomes. RESULTS: Among 53 assessable patients, we observed 15 instances of PSA nonprogression at 3 months, corresponding to a nonprogression rate of 28.3% (95% confidence interval: 16.8%-42.3%). The exploratory analysis revealed that for the 7 patients in whom optimal plasma concentration of efavirenz was achieved, PSA progression was observed in only 28.6% compared with 81.8% of patients with suboptimal plasma concentrations of efavirenz. CONCLUSION: Although 600 mg efavirenz did not statistically improve the PSA nonprogression rate, our exploratory analysis suggests that higher plasma concentrations of this drug (i.e., use of increased dosages) may be of potential benefit for the treatment of mCRPC.


Asunto(s)
Benzoxazinas/uso terapéutico , Neoplasias de la Próstata Resistentes a la Castración/tratamiento farmacológico , Inhibidores de la Transcriptasa Inversa/uso terapéutico , Adulto , Alquinos , Benzoxazinas/farmacocinética , Ciclopropanos , Progresión de la Enfermedad , Humanos , Masculino , Antígeno Prostático Específico/sangre , Resultado del Tratamiento
4.
Biomolecules ; 13(2)2023 02 01.
Artículo en Inglés | MEDLINE | ID: mdl-36830639

RESUMEN

α-Synucleinopathies are spreading neurodegenerative disorders characterized by the intracellular accumulation of insoluble aggregates populated by α-Synuclein (α-Syn) fibrils. In Parkinson's disease (PD) and dementia with Lewy bodies, intraneuronal α-Syn aggregates are referred to as Lewy bodies in the somata and as Lewy neurites in the neuronal processes. In multiple system atrophy (MSA) α-Syn aggregates are also found within mature oligodendrocytes (OLs) where they form Glial Cytoplasmic Inclusions (GCIs). However, the origin of GCIs remains enigmatic: (i) mature OLs do not express α-Syn, precluding the seeding and the buildup of inclusions and (ii) the artificial overexpression of α-Syn in OLs of transgenic mice results in a burden of soluble phosphorylated α-Syn but fails to form α-Syn fibrils. In contrast, mass spectrometry of α-Syn fibrillar aggregates from MSA patients points to the neuronal origin of the proteins intimately associated with the fibrils within the GCIs. This suggests that GCIs are preassembled in neurons and only secondarily incorporated into OLs. Interestingly, we recently isolated a synthetic human α-Syn fibril strain (1B fibrils) capable of seeding a type of neuronal inclusion observed early and specifically during MSA. Our goal was thus to investigate whether the neuronal α-Syn pathology seeded by 1B fibrils could eventually be transmitted to OLs to form GCIs in vivo. After confirming that mature OLs did not express α-Syn to detectable levels in the adult mouse brain, a series of mice received unilateral intra-striatal injections of 1B fibrils. The resulting α-Syn pathology was visualized using phospho-S129 α-Syn immunoreactivity (pSyn). We found that even though 1B fibrils were injected unilaterally, many pSyn-positive neuronal somas were present in layer V of the contralateral perirhinal cortex after 6 weeks. This suggested a fast retrograde spread of the pathology along the axons of crossing cortico-striatal neurons. We thus scrutinized the posterior limb of the anterior commissure, i.e., the myelinated interhemispheric tract containing the axons of these neurons: we indeed observed numerous pSyn-positive linear Lewy Neurites oriented parallel to the commissural axis, corresponding to axonal segments filled with aggregated α-Syn, with no obvious signs of OL α-Syn pathology at this stage. After 6 months however, the commissural Lewy neurites were no longer parallel but fragmented, curled up, sometimes squeezed in-between two consecutive OLs in interfascicular strands, or even engulfed inside OL perikarya, thus forming GCIs. We conclude that the 1B fibril strain can rapidly induce an α-Syn pathology typical of MSA in mice, in which the appearance of GCIs results from the pruning of diseased axonal segments containing aggregated α-Syn.


Asunto(s)
Atrofia de Múltiples Sistemas , Sinucleinopatías , Humanos , Ratones , Animales , alfa-Sinucleína/metabolismo , Atrofia de Múltiples Sistemas/patología , Cuerpos de Lewy/metabolismo , Cuerpos de Inclusión/metabolismo , Sinucleinopatías/metabolismo , Oligodendroglía/metabolismo , Neuritas/metabolismo , Ratones Transgénicos , Encéfalo/metabolismo
5.
Mol Pharmacol ; 82(1): 134-41, 2012 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-22528119

RESUMEN

Polyphenolic ellagitannins are natural compounds that are often associated with the therapeutic activity of plant extracts used in traditional medicine. They display cancer-preventing activity in animal models by a mechanism that remains unclear. Potential targets have been proposed, including DNA topoisomerases II (Top2). Top2α and Top2ß, the two isoforms of the human Top2, play a crucial role in the regulation of replication, transcription, and chromosome segregation. They are the target of anticancer agents used in the clinic such as anthracyclines (e.g., doxorubicin) or the epipodophyllotoxin etoposide. It was recently shown that the antitumor activity of etoposide was due primarily to the inhibition of Top2α, whereas inhibition of Top2ß was responsible for the development of secondary malignancies, pointing to the need for more selective Top2α inhibitors. Here, we show that the polyphenolic ellagitannin vescalagin preferentially inhibits the decatenation activity of Top2α in vitro, by a redox-independent mechanism. In CEM cells, we also show that transient small interfering RNA-mediated down-regulation of Top2α but not of Top2ß conferred a resistance to vescalagin, indicating that the α isoform is a preferential target. We further confirmed that Top2α inhibition was due to a catalytic inhibition of the enzyme because it did not induce DNA double-strand breaks in CEM-treated cells but prevented the formation of Top2α- rather than Top2ß-DNA covalent complexes induced by etoposide. To our knowledge, vescalagin is the first example of a catalytic inhibitor for which cytotoxicity is due, at least in part, to the preferential inhibition of Top2α.


Asunto(s)
Antígenos de Neoplasias/metabolismo , Antineoplásicos/farmacología , ADN-Topoisomerasas de Tipo II/metabolismo , Proteínas de Unión al ADN/antagonistas & inhibidores , Proteínas de Unión al ADN/metabolismo , Taninos Hidrolizables/farmacología , Catálisis , Proliferación Celular/efectos de los fármacos , Roturas del ADN de Doble Cadena , ADN de Cinetoplasto/metabolismo , Regulación hacia Abajo/efectos de los fármacos , Etopósido/farmacología , Humanos , Oxidación-Reducción/efectos de los fármacos , Proteínas de Unión a Poli-ADP-Ribosa , Isoformas de Proteínas/metabolismo , Células Tumorales Cultivadas
6.
Am J Pathol ; 178(5): 1986-98, 2011 May.
Artículo en Inglés | MEDLINE | ID: mdl-21514416

RESUMEN

The human p53 gene is a tumor suppressor mutated in half of colon cancers. Although p53 function appears important for proliferation arrest and apoptosis induced by cancer therapeutics, the prognostic significance of p53 mutations remains elusive. This suggests that p53 function is modulated at a posttranslational level and that dysfunctions affecting its modulators can have a prognostic impact. Among p53 modulators, homeodomain interacting protein kinase (HIPK) 2 emerges as a candidate "switch" governing p53 transition from a cytostatic to a proapoptotic function. Thus, we investigated the possible prognostic role of HIPK2 on a retrospective series of 80 colon cancer cases by setting up a multiplexed cytometric approach capable of exploring correlative protein expression at the single tumor cell level on TMA. Crossing the data with quantitative PCR and p53 gene sequencing and p53 functional assays, we observed the following: despite a strong impact on p21 transcription, the presence of disabling p53 mutations has no prognostic value, and the increased expression of the HIPK2 protein in tumor cells compared with paired normal tissue cells has a strong impact on survival. Unexpectedly, HIPK2 effect does not appear to be mediated by p53 function because it is also observed in p53-disabling mutated backgrounds. Thus, our results point to a prominent and p53-independent role of HIPK2 in colon cancer survival.


Asunto(s)
Proteínas Portadoras/biosíntesis , Neoplasias del Colon/genética , Neoplasias del Colon/mortalidad , Proteínas Serina-Treonina Quinasas/biosíntesis , Proteína p53 Supresora de Tumor/genética , Adulto , Anciano , Anciano de 80 o más Años , Proteínas Portadoras/genética , Neoplasias del Colon/patología , Análisis Mutacional de ADN , Femenino , Técnica del Anticuerpo Fluorescente , Expresión Génica , Perfilación de la Expresión Génica , Humanos , Inmunohistoquímica , Estimación de Kaplan-Meier , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Pronóstico , Proteínas Serina-Treonina Quinasas/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Análisis de Matrices Tisulares , Proteína p53 Supresora de Tumor/metabolismo
7.
Bioorg Med Chem ; 20(22): 6724-31, 2012 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-23063521

RESUMEN

Monoclonal antibodies (MoAb) and tyrosine kinase inhibitors (TKI) targeting the EGFR (Epidermal Growth Factor Receptor) pathways are currently used in colorectal cancer treatment. Despite the improvement of median overall survival, resistance is observed notably due to KRAS and BRAF gene mutations. We synthesized four series of thienopyrimidines whose scaffold is structurally close to TKI used in clinical practice. We evaluated apoptosis induced by these compounds using flow cytometry on KRAS and BRAF mutated cell lines. Our results confirm that the mutated cell lines (HCT116 and HT29) are more resistant to apoptosis than the non-mutated cell line (Hela). Interestingly, among the 13 compounds tested, three of them (5b, 6b and 6d) and gefitinib exhibited a noteworthy pro-apoptotic effect, especially on mutated cell lines with an IC(50) value between 70 and 110µM. These three compounds seem particularly attractive for the development of novel treatments for colorectal cancer patients harboring EGFR pathway mutations.


Asunto(s)
Apoptosis/efectos de los fármacos , Proteínas Proto-Oncogénicas B-raf/genética , Pirimidinas/toxicidad , Proteínas ras/genética , Caspasas/metabolismo , Neoplasias Colorrectales/metabolismo , Neoplasias Colorrectales/patología , Células HCT116 , Células HT29 , Células HeLa , Humanos , Mutación , Proteínas Proto-Oncogénicas B-raf/metabolismo , Pirimidinas/síntesis química , Pirimidinas/química , Relación Estructura-Actividad , Proteínas ras/metabolismo
8.
Biomolecules ; 12(4)2022 03 24.
Artículo en Inglés | MEDLINE | ID: mdl-35454083

RESUMEN

In 1957, Lionel Penrose built the first man-made self-replicating mechanical device and illustrated its function in a series of machine prototypes, prefiguring our current view of the genesis and the proliferation of amyloid fibrils. He invented and demonstrated, with the help of his son Roger, the concepts that decades later, would become the fundamentals of prion and prion-like neurobiology: nucleation, seeding and conformational templating of monomers, linear polymer elongation, fragmentation, and spread. He published his premonitory discovery in a movie he publicly presented at only two conferences in 1958, a movie we thus reproduce here. By making a 30-year-jump in the early 90's, we evoke the studies performed by Peter Lansbury and his group in which α-Synuclein (α-Syn) was for the first time (i) compared to a prion; (ii) shown to contain a fibrillization-prone domain capable of seeding its own assembly into fibrils; (iii) identified as an intrinsically disordered protein (IDP), and which, in the early 2000s, (iv) was described by one of us as a protein chameleon. We use these temporally distant breakthroughs to propose that the combination of the chameleon nature of α-Syn with the rigid gear of the Penrose machine is sufficient to account for a phenomenon that is of current interest: the emergence and the spread of a variety of α-Syn fibril strains in α-Synucleinopathies.


Asunto(s)
Proteínas Intrínsecamente Desordenadas , Priones , Sinucleinopatías , Amiloide , Humanos , alfa-Sinucleína/metabolismo
9.
NPJ Parkinsons Dis ; 8(1): 10, 2022 Jan 13.
Artículo en Inglés | MEDLINE | ID: mdl-35027576

RESUMEN

Aggregated alpha-synuclein (α-syn) is a principal constituent of Lewy bodies (LBs) and glial cytoplasmic inclusions (GCIs) observed respectively inside neurons in Parkinson's disease (PD) and oligodendrocytes in multiple system atrophy (MSA). Yet, the cellular origin, the pathophysiological role, and the mechanism of formation of these inclusions bodies (IBs) remain to be elucidated. It has recently been proposed that α-syn IBs eventually cause the demise of the host cell by virtue of the cumulative sequestration of partner proteins and organelles. In particular, the hypothesis of a local cross-seeding of other fibrillization-prone proteins like tau or TDP-43 has also been put forward. We submitted sarkosyl-insoluble extracts of post-mortem brain tissue from PD, MSA and control subjects to a comparative proteomic analysis to address these points. Our studies indicate that: (i) α-syn is by far the most enriched protein in PD and MSA extracts compared to controls; (ii) PD and MSA extracts share a striking overlap of their sarkosyl-insoluble proteomes, consisting of a vast majority of mitochondrial and neuronal synaptic proteins, and (iii) other fibrillization-prone protein candidates possibly cross-seeded by α-syn are neither found in PD nor MSA extracts. Thus, our results (i) support the idea that pre-assembled building blocks originating in neurons serve to the formation of GCIs in MSA, (ii) show no sign of amyloid cross-seeding in either synucleinopathy, and (iii) point to the sequestration of mitochondria and of neuronal synaptic components in both LBs and GCIs.

10.
Vaccines (Basel) ; 10(9)2022 Aug 30.
Artículo en Inglés | MEDLINE | ID: mdl-36146508

RESUMEN

The progressive accumulation of misfolded α-synuclein (α-syn) in the brain is widely considered to be causal for the debilitating clinical manifestations of synucleinopathies including, most notably, Parkinson's disease (PD). Immunotherapies, both active and passive, against α-syn have been developed and are promising novel treatment strategies for such disorders. To increase the potency and specificity of PD vaccination, we created the 'Win the Skin Immune System Trick' (WISIT) vaccine platform designed to target skin-resident dendritic cells, inducing superior B and T cell responses. Of the six tested WISIT candidates, all elicited higher immune responses compared to conventional, aluminum adjuvanted peptide-carrier conjugate PD vaccines, in BALB/c mice. WISIT-induced antibodies displayed higher selectivity for α-syn aggregates than those induced by conventional vaccines. Additionally, antibodies induced by two selected candidates were shown to inhibit α-syn aggregation in a dose-dependent manner in vitro. To determine if α-syn fibril formation could also be inhibited in vivo, WISIT candidate type 1 (CW-type 1) was tested in an established synucleinopathy seeding model and demonstrated reduced propagation of synucleinopathy in vivo. Our studies provide proof-of-concept for the efficacy of the WISIT vaccine technology platform and support further preclinical and clinical development of this vaccine candidate.

11.
Biomolecules ; 12(3)2022 03 11.
Artículo en Inglés | MEDLINE | ID: mdl-35327628

RESUMEN

The distinct neuropathological features of the different α-Synucleinopathies, as well as the diversity of the α-Synuclein (α-Syn) intracellular inclusion bodies observed in post mortem brain sections, are thought to reflect the strain diversity characterizing invasive α-Syn amyloids. However, this "one strain, one disease" view is still hypothetical, and to date, a possible disease-specific contribution of non-amyloid factors has not been ruled out. In Multiple System Atrophy (MSA), the buildup of α-Syn inclusions in oligodendrocytes seems to result from the terminal storage of α-Syn amyloid aggregates first pre-assembled in neurons. This assembly occurs at the level of neuronal cytoplasmic inclusions, and even earlier, within neuronal intranuclear inclusions (NIIs). Intriguingly, α-Syn NIIs are never observed in α-Synucleinopathies other than MSA, suggesting that these inclusions originate (i) from the unique molecular properties of the α-Syn fibril strains encountered in this disease, or alternatively, (ii) from other factors specifically dysregulated in MSA and driving the intranuclear fibrillization of α-Syn. We report the isolation and structural characterization of a synthetic human α-Syn fibril strain uniquely capable of seeding α-Syn fibrillization inside the nuclear compartment. In primary mouse cortical neurons, this strain provokes the buildup of NIIs with a remarkable morphology reminiscent of cat's eye marbles (see video abstract). These α-Syn inclusions form giant patterns made of one, two, or three lentiform beams that span the whole intranuclear volume, pushing apart the chromatin. The input fibrils are no longer detectable inside the NIIs, where they become dominated by the aggregation of endogenous α-Syn. In addition to its phosphorylation at S129, α-Syn forming the NIIs acquires an epitope antibody reactivity profile that indicates its organization into fibrils, and is associated with the classical markers of α-Syn pathology p62 and ubiquitin. NIIs are also observed in vivo after intracerebral injection of the fibril strain in mice. Our data thus show that the ability to seed NIIs is a strain property that is integrally encoded in the fibril supramolecular architecture. Upstream alterations of cellular mechanisms are not required. In contrast to the lentiform TDP-43 NIIs, which are observed in certain frontotemporal dementias and which are conditional upon GRN or VCP mutations, our data support the hypothesis that the presence of α-Syn NIIs in MSA is instead purely amyloid-strain-dependent.


Asunto(s)
Atrofia de Múltiples Sistemas , Sinucleinopatías , Amiloide , Animales , Encéfalo/metabolismo , Cuerpos de Inclusión Intranucleares/metabolismo , Cuerpos de Inclusión Intranucleares/patología , Ratones , Atrofia de Múltiples Sistemas/genética , Atrofia de Múltiples Sistemas/patología , Neuronas/metabolismo , alfa-Sinucleína/metabolismo
12.
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
13.
Biochim Biophys Acta Bioenerg ; 1861(12): 148289, 2020 12 01.
Artículo en Inglés | MEDLINE | ID: mdl-32810507

RESUMEN

VDAC (Voltage Dependent Anion Channel) is a family of pore forming protein located in the outer mitochondrial membrane. Its channel property ensures metabolites exchange between mitochondria and the rest of the cell resulting in metabolism and bioenergetics regulation, and in cell death and life switch. VDAC1 is the best characterized and most abundant isoform, and is involved in many pathologies, as cancer or neurodegenerative diseases. However, little information is available about its gene expression regulation in normal and/or pathological conditions. In this work, we explored VDAC1 gene expression regulation in normal conditions and in the contest of some metabolic and energetic mitochondrial dysfunction and cell stress as example. The core of the putative promoter region was characterized in terms of transcription factors responsive elements both by bioinformatic studies and promoter activity experiments. In particular, we found an abundant presence of NRF-1 sites, together with other transcription factors binding sites involved in cell growth, proliferation, development, and we studied their prevalence in gene activity. Furthermore, upon depletion of nutrients or controlled hypoxia, as detected in various pathologies, we found that VDAC1 transcripts levels were significantly increased in a time related manner. VDAC1 promoter activity was also validated by gene reporter assays. According to PCR real-time experiments, it was confirmed that VDAC1 promoter activity is further stimulated when cells are exposed to stress. A bioinformatic survey suggested HIF-1α, besides NRF-1, as a most active TFBS. Their validation was obtained by TFBS mutagenesis and TF overexpression experiments. In conclusion, we experimentally demonstrated the involvement of both NRF-1 and HIF-1α in the regulation of VDAC1 promoter activation at basal level and in some peculiar cell stress conditions.


Asunto(s)
Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Factor Nuclear 1 de Respiración/metabolismo , Regiones Promotoras Genéticas , Canal Aniónico 1 Dependiente del Voltaje/genética , Sitios de Unión , Hipoxia de la Célula/genética , Supervivencia Celular , Regulación de la Expresión Génica , Células HeLa , Humanos , Potencial de la Membrana Mitocondrial , Mitocondrias/metabolismo , Biogénesis de Organelos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Estrés Fisiológico , Factores de Transcripción/metabolismo , Canal Aniónico 1 Dependiente del Voltaje/metabolismo
14.
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
15.
Biochim Biophys Acta ; 1783(8): 1551-60, 2008 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-18424271

RESUMEN

gamma-Secretase mediates the intramembranous proteolysis of amyloid precursor protein (APP), Notch and other cellular substrates and is considered a prime pharmacological target in the development of therapeutics for Alzheimer's disease (AD). We describe here an efficient, new, simple, sensitive and rapid assay to quantify gamma-secretase activity in living cells by flow cytometry using two membrane-bound fluorescent probes, APP-GFP or C99-GFP, as substrates for gamma-secretase. The principle of the assay is based on the fact that the soluble intracellular domain of GFP-tagged APP (AICD-GFP) is released from the membrane into the cytosol following gamma-secretase cleavage. Using this feature, enzymatic activity of gamma-secretase could be deduced from the extent of the membrane retention of the probe observed after plasma membrane permeabilization and washout of the cleaved fraction. By applying two well-known gamma-secretase inhibitors (DAPT and L-685,458), we validated our assay showing that the positional GFP-based probes for gamma-secretase activity behave properly when expressed in different cell lines, providing the basis for the further development of a high-throughput and high content screening for AD targeted drug discovery. Moreover, by co-expression of different familial AD-linked mutated forms of presenilin--the key component of the gamma-secretase complex--in cells devoid of any endogenous gamma-secretase, our method allowed us to evaluate in situ the contribution of different presenilin variants to the modulation of the enzyme.


Asunto(s)
Enfermedad de Alzheimer/genética , Secretasas de la Proteína Precursora del Amiloide/análisis , Citometría de Flujo , Mutación , Presenilinas/genética , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Animales , Línea Celular , Colorantes Fluorescentes/análisis , Proteínas Fluorescentes Verdes/análisis , Proteínas Fluorescentes Verdes/genética , Humanos , Ratones , Proteínas Recombinantes/análisis
16.
Mol Cancer Res ; 6(4): 604-13, 2008 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-18403639

RESUMEN

Activation of the phosphatidylinositol 3-kinase (PI3K) signaling pathway is known to protect tumor cells from apoptosis and more specifically from the Fas-mediated apoptotic signal. The antitumoral agent edelfosine sensitizes leukemic cells to death by inducing the redistribution of the apoptotic receptor Fas into plasma membrane subdomains called lipid rafts. Herein, we show that inhibition of the PI3K signal by edelfosine triggers a Fas-mediated apoptotic signal independently of the Fas/FasL interaction. Furthermore, similarly to edelfosine, blockade of the PI3K activity, using specific inhibitors LY294002 and wortmannin, leads to the clustering of Fas whose supramolecular complex is colocalized within the lipid rafts. These findings indicate that the antitumoral agent edelfosine down-modulates the PI3K signal to sensitize tumor cells to death through the redistribution of Fas into large platform of membrane rafts.


Asunto(s)
Microdominios de Membrana/enzimología , Fosfatidilinositol 3-Quinasas/metabolismo , Transducción de Señal , Receptor fas/metabolismo , Muerte Celular/efectos de los fármacos , Línea Celular Tumoral , Regulación hacia Abajo , Activación Enzimática/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Proteína Ligando Fas/metabolismo , Humanos , Microdominios de Membrana/efectos de los fármacos , Inhibidores de las Quinasa Fosfoinosítidos-3 , Éteres Fosfolípidos/farmacología , Transporte de Proteínas/efectos de los fármacos , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transducción de Señal/efectos de los fármacos
17.
Anal Chem ; 81(23): 9590-8, 2009 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-19873978

RESUMEN

Recombinant fluorescent probes allow the detection of molecular events inside living cells. Many of them exploit the intracellular space to provide positional signals and, thus, require detection by single cell imaging. We describe here a novel strategy based on probes capable of encoding the spatial dimension of intracellular signals into "all-or-none" fluorescence intensity changes (differential anchorage probes, DAPs). The resulting signals can be acquired in single cells at high throughput by automated flow cytometry, (i) bypassing image acquisition and analysis, (ii) providing a direct quantitative readout, and (iii) allowing the exploration of large experimental series. We illustrate our purpose with DAPs for Bax and the effector caspases 3 and 7, which are keys players in apoptotic cell death, and show applications in basic research, high content multiplexed library screening, compound characterization, and drug profiling.


Asunto(s)
Colorantes Fluorescentes/metabolismo , Espacio Intracelular/metabolismo , Proteínas Recombinantes/metabolismo , Secuencia de Aminoácidos , Animales , Apoptosis , Caspasa 3/metabolismo , Caspasa 7/metabolismo , Ciclo Celular , Muerte Celular , Línea Celular Tumoral , Permeabilidad de la Membrana Celular , Proliferación Celular , Descubrimiento de Drogas , Citometría de Flujo , Ensayos Analíticos de Alto Rendimiento , Humanos , Imagen Molecular , Datos de Secuencia Molecular , Péptido Hidrolasas/metabolismo , Proteínas Recombinantes/química , Proteína X Asociada a bcl-2/metabolismo
18.
J Exp Ther Oncol ; 8(2): 105-16, 2009.
Artículo en Inglés | MEDLINE | ID: mdl-20192117

RESUMEN

The aim of this study was to determine the apoptotic and cytotoxic effects induced on glioblastoma cells by various anticancer agents that possess different mechanisms of action (alkylating drugs, anti-EGFR (Epidermal Growth Factor receptor), proteasome inhibitor). Primary cell cultures were obtained from patients who underwent surgery for their glioblastoma. The cytotoxic effects of drugs were determined by MTT (dimethylthiazolyl diphenyl tetrazolium bromide) assay and apoptosis was evaluated by measuring mitochondrial potential by flow cytometry. Biological markers (EGFR, bcl-2) were studied by a immunoblotting technique to find out predictive markers of response. We found a large interindividual sensitivity, thus confirming the interest of the primary cultures. New proteasome inhibitor bortezomib had considerable cytotoxic and apoptotic potential in glioblastoma, even at very low concentrations. Moreover, the characterization of patients' cells for EGFR and bcl-2 status could constitute an interest, with the evaluation of other markers, in the study of expected chemotherapy response.


Asunto(s)
Antineoplásicos/farmacología , Apoptosis/efectos de los fármacos , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/patología , Receptores ErbB/genética , Genes bcl-2/genética , Glioblastoma/genética , Glioblastoma/patología , Adulto , Anciano , Biomarcadores de Tumor/metabolismo , Western Blotting , Neoplasias Encefálicas/metabolismo , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Colorantes , Receptores ErbB/metabolismo , Citometría de Flujo , Proteína Ácida Fibrilar de la Glía/metabolismo , Glioblastoma/metabolismo , Humanos , Inmunohistoquímica , Persona de Mediana Edad , Sales de Tetrazolio , Tiazoles
20.
Nat Neurosci ; 22(1): 65-77, 2019 01.
Artículo en Inglés | MEDLINE | ID: mdl-30559480

RESUMEN

Accumulation of abnormally phosphorylated TDP-43 (pTDP-43) is the main pathology in affected neurons of people with amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Morphological diversity and neuroanatomical distribution of pTDP-43 accumulations allowed classification of FTLD cases into at least four subtypes, which are correlated with clinical presentations and genetic causes. To understand the molecular basis of this heterogeneity, we developed SarkoSpin, a new method for biochemical isolation of pathological TDP-43. By combining SarkoSpin with mass spectrometry, we revealed proteins beyond TDP-43 that become abnormally insoluble in a disease subtype-specific manner. We show that pTDP-43 extracted from brain forms stable assemblies of distinct densities and morphologies that are associated with disease subtypes. Importantly, biochemically extracted pTDP-43 assemblies showed differential neurotoxicity and seeding that were correlated with disease duration of FTLD subjects. Our data are consistent with the notion that disease heterogeneity could originate from alternate pathological TDP-43 conformations, which are reminiscent of prion strains.


Asunto(s)
Encéfalo/metabolismo , Proteínas de Unión al ADN/metabolismo , Degeneración Lobar Frontotemporal/metabolismo , Agregado de Proteínas/fisiología , Animales , Encéfalo/patología , Progresión de la Enfermedad , Degeneración Lobar Frontotemporal/patología , Células HEK293 , Humanos , Cuerpos de Inclusión/metabolismo , Cuerpos de Inclusión/patología , Espectrometría de Masas , Ratones , Neuronas/metabolismo , Neuronas/patología , Fosforilación
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA