10 research outputs found
The smoothened agonist SAG reduces mitochondrial dysfunction and neurotoxicity of frataxin-deficient astrocytes
Background: Friedreichâs ataxia is a rare hereditary neurodegenerative disease caused by decreased levels of the mitochondrial protein frataxin. Similar to other neurodegenerative pathologies, previous studies suggested that astrocytes might contribute to the progression of the disease. To fully understand the mechanisms underlying neurodegeneration in Friedreichâs ataxia, we investigated the reactivity status and functioning of cultured human astrocytes after frataxin depletion using an RNA interference-based approach and tested the effect of pharmacologically modulating the SHH pathway as a novel neuroprotective strategy. Results: We observed loss of cell viability, mitochondrial alterations, increased autophagy and lipid accumulation in cultured astrocytes upon frataxin depletion. Besides, frataxin-deficient cells show higher expression of several A1-reactivity markers and release of pro-inflammatory cytokines. Interestingly, most of these defects were prevented by chronically treating the cells with the smoothened agonist SAG. Furthermore, in vitro culture of neurons with conditioned medium from frataxin-deficient astrocytes results in a reduction of neuronal survival, neurite length and synapse formation. However, when frataxin-deficient astrocytes were chronically treated with SAG, we did not observe these alterations in neurons. Conclusions: Our results demonstrate that the pharmacological activation of the SHH pathway could be used as a target to modulate astrocyte reactivity and neuronâglia interactions to prevent neurodegeneration in Friedreichâs ataxiaThis study was supported by research grants from Comunidad AutĂłnoma de Madrid (NEUROMETAB-CM, B2017/BMD-3700) to J.D-N., Spanish Ministerio de Ciencia e InnovaciĂłn (MICINN, grant PID2019-111338RB-I00) to J.D-N. and A.G-C., Instituto de Salud Carlos III (PI20/00934, co-funded by Fondo Europeo de Desarrollo Regional, FEDER) and Association Française de lâAtaxie de Friedreich (AFAF) to F.L. A.V-A. is supported by a contract from Comunidad AutĂłnoma de Madrid (NEUROMETAB-CM, B2017/BMD-3700
α-Synuclein transfer between neurons and astrocytes indicates that astrocytes play a role in degradation rather than in spreading.
International audienceRecent evidence suggests that disease progression in Parkinson's disease (PD) could occur by the spreading of α-synuclein (α-syn) aggregates between neurons. Here we studied the role of astrocytes in the intercellular transfer and fate of α-syn fibrils, using in vitro and ex vivo models. α-Syn fibrils can be transferred to neighboring cells; however, the transfer efficiency changes depending on the cell types. We found that α-syn is efficiently transferred from astrocytes to astrocytes and from neurons to astrocytes, but less efficiently from astrocytes to neurons. Interestingly, α-syn puncta are mainly found inside the lysosomal compartments of the recipient cells. However, differently from neurons, astrocytes are able to efficiently degrade fibrillar α-syn, suggesting an active role for these cells in clearing α-syn deposits. Astrocytes co-cultured with organotypic brain slices are able to take up α-syn fibrils from the slices. Altogether our data support a role for astrocytes in trapping and clearing α-syn pathological deposits in PD
Fate and propagation of endogenously formed Tau aggregates in neuronal cells
International audienceTau accumulation in the form of neurofibrillary tangles in the brain is a hallmark of tauopathies such as Alzheimer's disease (AD). Tau aggregates accumulate in brain regions in a defined spatiotemporal pattern and may induce the aggregation of native Tau in a prion-like manner. However, the underlying mechanisms of cell-to-cell spreading of Tau pathology are unknown and could involve encapsulation within exosomes, trans-synaptic passage, and tunneling nanotubes (TNTs). We have established a neuronal cell model to monitor both internalization of externally added fibrils, synthetic (K18) or Tau from AD brain extracts, and real-time conversion of microtubule-binding domain of Tau fused to a fluorescent marker into aggregates. We found that these endogenously formed deposits colabel with ubiquitin and p62 but are not recruited to macroautophagosomes, eventually escaping clearance. Furthermore, endogenous K18-seeded Tau aggregates spread to neighboring cells where they seed new deposits. Transfer of Tau aggregates depends on direct cell contact, and they are found inside TNTs connecting neuronal cells. We further demonstrate that contact-dependent transfer occurs in primary neurons and between neurons and astrocytes in organotypic cultures
Altered Secretome and ROS Production in Olfactory Mucosa Stem Cells Derived from Friedreich's Ataxia Patients
Author Contributions: D.O. performed the experiments and analyzed the data. S.P.-L. and F.L. (Frida Loria) performed experiments, analyzed the data, drafted the work and wrote the manuscript. Y.K.-J. analyzed aconitase experiments and provided scientific input. O.-L.Y. acquired and analyzed the cytokine array experiments. F.L. (Filip Lim) helped optimize OE-MSC cultures and reviewed the manuscript. J.L.M.-B. recruited patients and healthy subjects. J.D.-N. conceived and coordinated the project, discussed the experiments and results, and provided financial support. All authors have read and agreed to the published version of the manuscript.Friedreichâs ataxia is the most common hereditary ataxia for which there is no cure or approved treatment at present. However, therapeutic developments based on the understanding of pathological mechanisms underlying the disease have advanced considerably, with the implementation of cellular models that mimic the disease playing a crucial role. Human olfactory ecto-mesenchymal stem cells represent a novel model that could prove useful due to their accessibility and neurogenic capacity. Here, we isolated and cultured these stem cells from FriedreichÂŽs ataxia patients and healthy donors, characterizing their phenotype and describing disease-specific features such as reduced cell viability, impaired aconitase activity, increased ROS production and the release of cytokines involved in neuroinflammation. Importantly, we observed a positive effect on patient-derived cells, when frataxin levels were restored, confirming the utility of this in vitro model to study the disease. This model will improve our understanding of FriedreichÂŽs ataxia pathogenesis and will help in developing rationally designed therapeutic strategies.Plan Nacional de InvestigaciĂłnAssociation Française de lâAtaxie de FriedreichFundaciĂłn Ataxia en MovimientoSecciĂłn Deptal. de BioquĂmica y BiologĂa Molecular (Veterinaria)Fac. de VeterinariaTRUEpu
Altered Secretome and ROS Production in Olfactory Mucosa Stem Cells Derived from Friedreichâs Ataxia Patients
© 2020 by the authors.Friedreichâs ataxia is the most common hereditary ataxia for which there is no cure or approved treatment at present. However, therapeutic developments based on the understanding of pathological mechanisms underlying the disease have advanced considerably, with the implementation of cellular models that mimic the disease playing a crucial role. Human olfactory ecto-mesenchymal stem cells represent a novel model that could prove useful due to their accessibility and neurogenic capacity. Here, we isolated and cultured these stem cells from FriedreichÂŽs ataxia patients and healthy donors, characterizing their phenotype and describing disease-specific features such as reduced cell viability, impaired aconitase activity, increased ROS production and the release of cytokines involved in neuroinflammation. Importantly, we observed a positive effect on patient-derived cells, when frataxin levels were restored, confirming the utility of this in vitro model to study the disease. This model will improve our understanding of FriedreichÂŽs ataxia pathogenesis and will help in developing rationally designed therapeutic strategies.This work was supported by grants of the Spanish National Research Plan (SAF 2015â69361-R), Lâassociation Française de lâAtaxie de Friedreich and FundaciĂłn Ataxia en Movimiento. Frida Loria received funding from the Marie SkĆodowska-Curie Action COFUND 2015 (EU project 713366âInterTalentum).Peer reviewe
Altered secretome and ros production in olfactory mucosa stem cells derived from friedreich's ataxia patients
Friedreichâs ataxia is the most common hereditary ataxia for which there is no cure or approved treatment at present. However, therapeutic developments based on the understanding of pathological mechanisms underlying the disease have advanced considerably, with the implementation of cellular models that mimic the disease playing a crucial role. Human olfactory ecto-mesenchymal stem cells represent a novel model that could prove useful due to their accessibility and neurogenic capacity. Here, we isolated and cultured these stem cells from FriedreichÂŽs ataxia patients and healthy donors, characterizing their phenotype and describing disease-specific features such as reduced cell viability, impaired aconitase activity, increased ROS production and the release of cytokines involved in neuroinflammation. Importantly, we observed a positive e ect on patient-derived cells, when frataxin levels were restored, confirming the utility of this in vitro model to study the disease. This model will improve our understanding of FriedreichÂŽs ataxia pathogenesis and will help in developing rationally designed therapeutic strategies.Spanish National Research Plan (SAF 2015â69361-R), Lâassociation Française de lâAtaxie de Friedreich and FundaciĂłn Ataxia en Movimiento. Frida Loria received funding from the Marie SkĆodowska-Curie Action COFUND 201
The Wnt/Ca 2+ pathway is involved in interneuronal communication mediated by tunneling nanotubes
International audienceTunneling nanotubes (TNTs) are actin-based transient tubular connections that allow direct communication between distant cells. TNTs play an important role in several physiological (development, immunity, and tissue regeneration) and pathological (cancer, neurodegeneration, and pathogens transmission) processes. Here, we report that the Wnt/Ca2+ pathway, an intracellular cascade that is involved in actin cytoskeleton remodeling, has a role in TNT formation and TNT-mediated transfer of cargoes. Specifically, we found that Ca2+ /calmodulin-dependent protein kinase II (CaMKII), a transducer of the Wnt/Ca2+ pathway, regulates TNTs in a neuronal cell line and in primary neurons. We identified the ÎČ isoform of CaMKII as a key molecule in modulating TNT formation and transfer, showing that this depends on the actin-binding activity of the protein. Finally, we found that the transfer of vesicles and aggregated α-synuclein between primary neurons can be regulated by the activation of the Wnt/Ca2+ pathway. Our findings suggest that Wnt/Ca2+ pathway could be a novel promising target for therapies designed to impair TNT-mediated propagation of pathogens