Anti-oxidants in Parkinson's disease therapy: a critical point of view

Parkinson's disease (PD) is a degenerative neurological syndrome, which is characterized by the preferential death of dopaminergic (DAergic) neurons in the SubstantiaNigra. The pathogenesis of this disorder remains poorly understood and PD is still incurable. Currentdrug treatmentsare aimedprimarily for the treatmentof symptoms to improve the quality of life. Therefore, there is a need to find out new therapeutic strategies that not only provide symptomatic relief but also halt or reverse the neuronal damage hampering PD progression. Oxidative stress has been identified as one of the major contributors for the nigral loss in both sporadic and genetic forms of PD. In this review we first evaluate the current literature that link oxidative stress and mitochondrial dysfunction to PD. We then consider the results obtained through the treatmentof animal modelsor PD patients withmolecules that prevent oxidative stress or reduce mitochondrial dysfunction

Analysis of the Catecholaminergic Phenotype in Human SH-SY5Y and BE(2)-M17 Neuroblastoma Cell Lines upon Differentiation

Human cell lines are often used to investigate cellular pathways relevant for physiological or pathological processes or to evaluate cell toxicity or protection induced by different compounds, including potential drugs. In this study, we analyzed and compared the differentiating activities of three agents (retinoic acid, staurosporine and 12-O-tetradecanoylphorbol-13-acetate) on the human neuroblastoma SH-SY5Y and BE(2)-M17 cell lines; the first cell line is largely used in the field of neuroscience, while the second is still poorly characterized. After evaluating their effects in terms of cell proliferation and morphology, we investigated their catecholaminergic properties by assessing the expression profiles of the major genes involved in catecholamine synthesis and storage and the cellular concentrations of the neurotransmitters dopamine and noradrenaline. Our results demonstrate that the two cell lines possess similar abilities to differentiate and acquire a neuron-like morphology. The most evident effects in SH-SY5Y cells were observed in the presence of staurosporine, while in BE(2)-M17 cells, retinoic acid induced the strongest effects. Undifferentiated SH-SY5Y and BE(2)-M17 cells are characterized by the production of both NA and DA, but their levels are considerably higher in BE(2)-M17 cells. Moreover, the NAergic phenotype appears to be more pronounced in SH-SY5Y cells, while BE(2)-M17 cells have a more prominent DAergic phenotype. Finally, the catecholamine concentration strongly increases upon differentiation induced by staurosporine in both cell lines. In conclusion, in this work the catecholaminergic phenotype of the human BE(2)-M17 cell line upon differentiation was characterized for the first time. Our data suggest that SH-SY5Y and BE(2)-M17 represent two alternative cell models for the neuroscience field

Superoxide Dismutase (SOD)-mimetic M40403 is protective in cell and fly models of paraquat toxicity: Implications for Parkinson disease

Parkinson disease is a debilitating and incurable neurodegenerative disorder affecting 3c1-2% of people over 65 years of age. Oxidative damage is considered to play a central role in the progression of Parkinson disease and strong evidence links chronic exposure to the pesticide paraquat with the incidence of the disease, most probably through the generation of oxidative damage. In this work, we demonstrated in human SH-SY5Y neuroblastoma cells the beneficial role of superoxide dismutase (SOD) enzymes against paraquat-induced toxicity, as well as the therapeutic potential of the SOD-mimetic compound M40403. Having verified the beneficial effects of superoxide dismutation in cells, we then evaluated the effects using Drosophila melanogaster as an in vivo model. Besides protecting against the oxidative damage induced by paraquat treatment, our data demonstrated that in Drosophila M40403 was able to compensate for the loss of endogenous SOD enzymes, acting both at a cytosolic and mitochondrial level. Because previous clinical trials have indicated that the M40403 molecule is well tolerated in humans, this study may have important implication for the treatment of Parkinson disease

Fluorescence Spectroscopy of the Tryptophan Microenvironment in Carcinus aestuarii Hemocyanin

The steady-state and time-resolved fluorescence properties of the multitryptophan minimal subunit CaeSS2 from Carcinus aestuarii hemocyanin have been studied with the aim of probing the environment of the fluorophores within the protein matrix. Subunit a of Panulirus interruptus hemocyanin, whose X-ray structure is known, has been also studied. The results are compared with those collected with other two monomeric fractions (CaeSS1, CaeSS3) produced by dissociation of the native, oligomeric protein as well as with those of the hexameric aggregate. Three classes of tryptophan residues can be singled out by a combination of fluorescence quenching and lifetime measurements on the holo-Hc (the copper containing, oxygen binding form) and the apo-Hc (the copper-free derivative). One class of tryptophans is exposed to the protein surface. Some of these residues are proposed to be involved in the intersubunit interactions in CaeSS1 and CaeSS3 fractions whereas in CaeSS2 the protein matrix masks them. This suggests the occurrence of conformational rearrangements after detachment of the subunit from the native aggregate, which could explain the inability of CaeSS2 to reassociate. A second class of tryptophan has been correlatively assigned, by comparison with the results obtained with Panulirus interruptus hemocyanin, to residues in close proximity to the active site. The third class includes buried, active site-distant, residues

LRRK2 phosphorylates pre-synaptic N-ethylmaleimide sensitive fusion (NSF) protein enhancing its ATPase activity and SNARE complex disassembling rate

Background Lrrk2, a gene linked to Parkinson\u2019s disease, encodes a large scaffolding protein with kinase and GTPase activities implicated in vesicle and cytoskeletal-related processes. At the presynaptic site, LRRK2 associates with synaptic vesicles through interaction with a panel of presynaptic proteins. Results Here, we show that LRRK2 kinase activity influences the dynamics of synaptic vesicle fusion. We therefore investigated whether LRRK2 phosphorylates component(s) of the exo/endocytosis machinery. We have previously observed that LRRK2 interacts with NSF, a hexameric AAA+ ATPase that couples ATP hydrolysis to the disassembling of SNARE proteins allowing them to enter another fusion cycle during synaptic exocytosis. Here, we demonstrate that NSF is a substrate of LRRK2 kinase activity. LRRK2 phosphorylates full-length NSF at threonine 645 in the ATP binding pocket of D2 domain. Functionally, NSF phosphorylated by LRRK2 displays enhanced ATPase activity and increased rate of SNARE complex disassembling. Substitution of threonine 645 with alanine abrogates LRRK2-mediated increased ATPase activity. Conclusions Given that the most common Parkinson\u2019s disease LRRK2 G2019S mutation displays increased kinase activity, our results suggest that mutant LRRK2 may impair synaptic vesicle dynamics via aberrant phosphorylation of NSF

Superoxide dismutating molecules rescue the toxic effects of PINK1 and parkin loss.

Reactive oxygen species exert important functions in regulating several cellular signalling pathways. However, an excessive accumulation of reactive oxygen species can perturb the redox homeostasis leading to oxidative stress, a condition which has been associated to many neurodegenerative disorders. Accordingly, alterations in the redox state of cells and mitochondrial homeostasis are established hallmarks in both familial and sporadic Parkinson's disease cases. PINK1 and Parkin are two genes which account for a large fraction of autosomal recessive early-onset forms of Parkinson's disease and are now firmly associated to both mitochondria and redox homeostasis. In this study we explored the hypothesis that superoxide anions participate in the generation of the Parkin and PINK1 associated phenotypic effect by testing the capacity of endogenous and exogenous superoxide dismutating molecules to rescue the toxic effects induced by loss of PINK1 or Parkin, in both cellular and fly models. Our results demonstrate the positive effect of an increased level of superoxide dismutase proteins on the pathological phenotypes, both in vitro and in vivo. A more pronounced effectiveness for mitochondrial SOD2 activity points to the superoxide radicals generated in the mitochondrial matrix as the prime suspect in the definition of the observed phenotypes. Moreover, we also demonstrate the efficacy of a SOD-mimetic compound, M40403, to partially ameliorate PINK1/Parkin phenotypes in vitro and in vivo. These results support the further exploration of SOD-mimetic compounds as a therapeutic strategy against Parkinson's disease

Human SOD2 Modification by Dopamine Quinones Affects Enzymatic Activity by Promoting Its Aggregation: Possible Implications for Parkinson’s Disease

Mitochondrial dysfunction and oxidative stress are considered central in dopaminergic neurodegeneration in Parkinson’s disease (PD). Oxidative stress occurs when the endogenous antioxidant systems are overcome by the generation of reactive oxygen species (ROS). A plausible source of oxidative stress, which could account for the selective degeneration of dopaminergic neurons, is the redox chemistry of dopamine (DA) and leads to the formation of ROS and reactive dopamine-quinones (DAQs). Superoxide dismutase 2 (SOD2) is a mitochondrial enzyme that converts superoxide radicals to molecular oxygen and hydrogen peroxide, providing a first line of defense against ROS. We investigated the possible interplay between DA and SOD2 in the pathogenesis of PD using enzymatic essays, site-specific mutagenesis, and optical and high-field-cw-EPR spectroscopies. Using radioactive DA, we demonstrated that SOD2 is a target of DAQs. Exposure to micromolar DAQ concentrations induces a loss of up to 50% of SOD2 enzymatic activity in a dose-dependent manner, which is correlated to the concomitant formation of protein aggregates, while the coordination geometry of the active site appears unaffected by DAQ modifications. Our findings support a model in which DAQ-mediated SOD2 inactivation increases mitochondrial ROS production, suggesting a link between oxidative stress and mitochondrial dysfunction

El cultivo de garbanzo (Cicer arietinum L.) en Argentina

El Programa Transferencia de Resultados de Investigación y Comunicación Pública de la Ciencia (PROTRI), de la Secretaría de Ciencia y Tecnología del Gobierno de la Provincia de Córdoba, financió la realización del libro El cultivo de garbanzo en Argentina con el objeto de promover la transferencia de resultados, experiencias o saberes entre las áreas del sector social y productivo para una mejor calidad de vida. Para la ejecución de esta obra han sido convocados técnicos e investigadores de las Ciencias Agropecuarias, Biológicas y Económicas, quienes en una forma clara y sencilla, aunque no menos consistente, ponen a disposición del lector sus experiencias adquiridas a lo largo de varios años de trabajo. El desarrollo de los diferentes temas se realiza a través de dieciséis Capítulos que abarcan desde la domesticación de Cicer y su llegada a la Argentina (Capítulo 1), pasando por el estudio morfológico de las diferentes partes de la planta en relación a los cultivares locales (Capítulo 2), además del manejo del suelo y sus nutrientes, en cuanto a requerimientos edáficos en los sistemas productivos (Capítulo 3). También se contempla el análisis de la influencia de los diversos factores ambientales para la determinación de zonas productivas (Capítulo 4). En el Capítulo 5 se hace referencia a la ecofisiología del cultivo, sus requerimientos en las diferentes etapas fenológicas, y cuándo y cómo se expresan en los cultivares. Un tema de indudable importancia para las leguminosas en general, y para el garbanzo en particular, es la simbiosis con las bacterias fijadoras de nitrógeno y su influencia en la productividad, el cual se desarrolla en el Capítulo 6. La mejora genética en el país es abordada en el Capítulo 7, donde se exponen sus inicios, desarrollo, disponibilidad de recursos, bondades y potencial del germoplasma disponible. A lo largo del ciclo biológico de la planta, el cultivo es visitado por insectos e infectado por hongos. Identificarlos y conocer sus ciclos biológicos y comportamientos es un aspecto importante para seleccionar las medidas de manejo y control más adecuadas (Capítulos 8 y 9). Quizás pocos sepan que el volumen de semilla genética de un cultivar, alcanza sólo unos pocos gramos (alrededor de 20). Para llevar este pequeño volumen a toneladas, se requiere del trabajo y tesón de investigadores, fitomejoradores y productores. Resultado de ese esfuerzo es la difusión de los seis cultivares obtenidos en el país, y se sigue trabajando para lograr nuevos materiales que se adapten a las diversas áreas y sistemas de producción (Capítulo 10). El desarrollo de los diferentes cultivares, que dan lugar a diversas arquitecturas de plantas, sumado a la adopción de diversos sistemas de producción, hace que el tema de la mecanización ocupe un lugar importante. Maquinas pequeñas y grandes intervienen en las etapas de siembra y de cosecha tratando de lograr la mayor eficiencia posible y un producto de calidad (Capítulo 11). Un cuello de botella para la expansión del cultivo es su comercialización, tanto para consumo interno como externo. En el Capítulo 12 se analizan los diferentes mercados y la necesidad de lograr un producto rentable de alta calidad, para mercados muy diversos. En el Capítulo 13 se hace un recorrido por las diferentes Provincias que actualmente producen garbanzo. Sus autores comentan como se incorporó el cultivo a los sistemas productivos de la región, sobre posibilidades y limitaciones, manejos y potencial de rendimiento, entre otros aportes. Los Capítulos 14 y 15 presentan dos temas de relevancia actual: la composición química del grano y las posibilidades de brindar valor agregado a éste, aspectos reforzados en la última década por el auge de las tendencias que promueven un nuevo estilo de vida y una alimentación sana, con alimentos naturales, bajos en grasa y con un buen balance nutricional. En el último Capítulo (16) se presentan experiencias de investigación en las que se utilizó al garbanzo como materia prima o como sustrato para diversas experimentaciones. La interacción docente-investigador-alumno permitió que vieran la luz diversos trabajos que, además de la formación de recursos humanos, brindan una información útil y novedosa al incursionar en temas tales como manejo de fechas de siembra, riego, alimento para pollos, cerdos y abejas. Estimado lector, tiene en sus manos un libro que es una invitación a un viaje con dieciséis estaciones. En cada una de ellas encontrará información sobre el cultivo del garbanzo en la Argentina. Estos datos fueron obtenidos por docentes, investigadores, productores, estudiantes que trabajaron y siguen trabajando para aportar al conocimiento del cultivo en nuestro país, bajo la realidad local y el contexto regional, ya que la mayoría de los trabajos y publicaciones son de origen extranjero y la aplicación de muchas de las tecnologías de manejo requieren una correcta adaptación y validación. Esperamos que este libro, además de serle útil, pueda ser disfrutado, sintiendo la pasión y el entusiasmo de cada uno de los autores por brindar y compartir sus conocimientos y logros