CEI - Doctorado Internacional en Biociencias Moleculares y Biomedicina
URI permanente para esta comunidad
El Doctorado Binacional en Biociencias Moleculares y Biomedicina es un posgrado dedicado al entrenamiento de estudiantes con un intenso enfoque teórico-práctico. El objetivo principal es profundizar nuestra comprensión de los procesos fisiológicos y moleculares de una amplia variedad de organismos. Nuestro plan se basa en un concepto interdisciplinario que incluye a la Física, la Química, la Biología y la Medicina, los cuales son los pilares fundamentales sobre los que se asienta nuestro programa.
Carrera de Posgrado con reconocimiento oficial de CONEAU Carrera nueva Nº 1198/12
Carrera de Posgrado aprobada por Consejo Superior de UNR Res. Nº 624/14
Dirección académica en Rosario: Dr. Claudio Fernández (Argentina). Director Laboratorio Max Planck de Biología Estructural, Química y Biofísica Molecular de Rosario, Universidad Nacional de Rosario. Rosario, Argentina
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Examinando CEI - Doctorado Internacional en Biociencias Moleculares y Biomedicina por Autor "Zweckstetter, Markus"
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Ítem Acceso Abierto Alpha-synuclein amyloid aggregation: From basic to translational research(2024-05-06) Buratti, Fiamma Ayelén; Fernández, Claudio; Zweckstetter, MarkusNeurodegenerative diseases are a heterogeneous group of disorders affecting the lives of millions of people worldwide. A shared pathologic hallmark is the appearance of insoluble aggregates in the brain. The components of these are different, given a wide spectrum of neurodegenerative diseases. The presence of amyloid fibrils of specific proteins in the deposits allowed the identification of proteins involved in the development of the disease, and their study in vitro. Parkinson’s disease is considered a neurological disorder where spherical intraneuronal inclusions known as Lewy bodies are found in brain regions. The determination of inherited mutations has aided the research of alpha-synuclein, as one protein involved in the misfolding and deposition into Lewy bodies. Alpha-synuclein is an intrinsically disordered protein, found free or bound to membranes under physiological conditions. However, in pathological conditions adopt b-sheet conformations, resulting in amyloid fibrils. Many factors are modulating the pathways mentioned before, such as some regions of the protein, point mutations, and post-translational modifications. The physiological conditions could be addressed following the interaction of monomers with membranes, as one model for gaining knowledge in parameters such as membrane affinity, membrane-bound conformations, and even residues involved in the binding. Amyloid fibrils of alpha-synuclein can be generated in vitro, and be able to uncover fibril core, specific residues implicated in the aggregation process, stability and structure of fibrils. These tools permit the study of how different factors affect the physiological and pathological condition. Our study aimed to unravel the aggregation properties of alpha-synuclein through the characterization of conformational assemblies, as well as in terms of binding properties. Key factors in this process have been studied. A combination of kinetics assays, nuclear magnetic resonance, circular dichroism, dynamic light scattering, cell culture, fluorescent probes, electron and atomic force microscopy, was chosen to gain insight into all the features investigated. Structural changes induced for point mutations or post-translational modifications gave relevance to the implication of residue-specific in the pathological and functional state of the protein. We observed how particular amino acids can impair the in vitro amyloid assembly and even impact the binding to membranes. These factors are likely modulating structural conformations, that may be attributed then to the variety of alpha-synucleinopathies. The work presented here is a step forward towards understanding the role of alpha-synuclein in the pathology of Parkinson’s disease.Ítem Acceso Abierto Structural characterization of a-synuclein aggregates seeded by patient material(2018-12-14) Strohäker, Timo; Zweckstetter, Markus; Fernandez, ClaudioNeurodegenerative diseases share a common underlying pathologic hallmark, the appearance of insoluble protein aggregates in diverse tissues of the nervous system. For many neurodegenerative diseases a common temporal and spatial spreading of the pathology is proposed in analogy to prion disease and discussed under the term “prion-like”. For many diseases the major component of the insoluble protein aggregates is known and aggregation into higher molecular weight amyloid fibrils with intermolecular b-sheet rich cores can be studied in vitro. The aggregation process involves the templated misfolding and aggregation of native monomeric proteins, involving severe conformational changes. An important family of neurodegenerative diseases is caused by the misfolding and aggregation of the protein a-synuclein, the so-called synucleinopathies. asynuclein, which in vivo forms disease-specifically the main component of intracellular inclusions such as Lewy bodies in neurons and cytoplasmatic inclusions in glial cells, undergoes in vitro dramatic conformational changes from a monomeric intrinsically disordered state over transient oligomeric b-sheet rich species into highly ordered asynuclein fibrils. a-synuclein pathology in patients is diverse and there are clinically distinct disease entities with defined pathologic phenotypes among those Parkinson’s disease (PD), dementia with Lewy bodies (DLB) and multiple system atrophy (MSA) are the best characterized. Similar to prion diseases, key differences within the broad clinical representation of synucleinopathies are thought to be structurally encoded by distinct protein aggregate conformations, referred to as a-synuclein polymorphs. The aim of the study was to amplify a-synuclein aggregates from brain extracts of patients thoroughly diagnosed on the basis of the molecular pathology as well as the clinical symptoms as PD, DLB and MSA, using the established protocol of protein misfolding cyclic amplification (PMCA). A combination of hydrogen-deuterium (HD) exchange coupled to nuclear magnetic resonance (NMR) spectroscopy, electron paramagnetic resonance (EPR) and the specific binding of fluorescent probes to amyloid fibrils was chosen to obtain single-residue resolution of the conformational properties of brain-extract seeded a-synuclein fibrils. The same approach was also applied to two well-characterized in vitro a-synuclein polymorphs, their aggregation was performed in the absence of brain extract seeds following published aggregation procedures and they acted as internal references for benchmarking the methodological approach. On the other hand, the availability of a high-resolution cryo-electron VII microscopy model of the fibrillar core for one of the in vitro a-synuclein polymorphs obtained under high salt conditions, allowed direct correlation of the residue-specific conformational restraints to a structural model, both for in vitro polymorphs of asynuclein as well as brain-extract amplified a-synuclein fibrils of PD, MSA and DLB. Distinct highly ordered conformational features of in vitro a-synuclein fibrils were successfully reproduced, detecting solvent-protected residues with high precision and in agreement with published data. In contrast, a-synuclein fibrils amplified from brain extracts were more flexible and differed structurally from in vitro fibrils. Hydrogendeuterium exchange coupled to NMR spectroscopy identified a common solventprotected core shared among all patient brain derived a-synuclein fibrils for the synucleinopathies PD, MSA and DLB. The solvent-protected fibrillar core was formed by the most hydrophobic residues of a-synuclein. Outside the common core structure, a-synuclein fibrils derived from brain extracts differed disease-specifically in the conformation. Residue-specific conformational differences in core-flanking residues of a-synuclein as well as in defined N-terminal regions were observed. This study establishes a strong correlation between a-synuclein aggregate structure and the disease phenotype for the synucleinopathies Parkinson’s disease, Dementia with Lewy bodies and multiple system atrophy and the data provide further insight in “prion-like” features of neurodegenerative diseases in general and synucleinopathies in particular. The work presented here is a step forward towards the understanding of a-synuclein pathology and hopefully contributes to improved disease diagnosis and treatment of synucleinopathies.