RESUMO
Parkinson's disease (PD) is a common neurodegenerative disorder that displays both sporadic and inherited forms. Exposure to several common environmental toxins acting through oxidative stress has been shown to be associated with PD. One recently identified inherited PD gene, DJ-1, may have a role in protection from oxidative stress, thus potentially linking a genetic cause with critical environmental risk factors. To develop an animal model that would allow integrative study of genetic and environmental influences, we have generated Drosophila lacking DJ-1 function. Fly DJ-1 homologs exhibit differential expression: DJ-1beta is ubiquitous, while DJ-1alpha is predominantly expressed in the male germline. DJ-1alpha and DJ-1beta double knockout flies are viable, fertile, and have a normal lifespan; however, they display a striking selective sensitivity to those environmental agents, including paraquat and rotenone, linked to PD in humans. This sensitivity results primarily from loss of DJ-1beta protein, which also becomes modified upon oxidative stress. These studies demonstrate that fly DJ-1 activity is selectively involved in protection from environmental oxidative insult in vivo and that the DJ-1beta protein is biochemically responsive to oxidative stress. Study of these flies will provide insight into the critical interplay of genetics and environment in PD.
Assuntos
Proteínas de Drosophila/genética , Proteínas do Tecido Nervoso/genética , Estresse Oxidativo/efeitos dos fármacos , Paraquat/toxicidade , Doença de Parkinson/genética , Doença de Parkinson/metabolismo , Rotenona/toxicidade , Sequência de Aminoácidos , Animais , Animais Geneticamente Modificados , Western Blotting , Análise por Conglomerados , Biologia Computacional , Cruzamentos Genéticos , Drosophila , Dados de Sequência Molecular , Mutação/genética , Neurônios/efeitos dos fármacos , Filogenia , Proteína Desglicase DJ-1 , Alinhamento de Sequência , Análise de SobrevidaRESUMO
DJ-1 is a ubiquitously expressed protein involved in various cellular processes including cell proliferation, RNA-binding, and oxidative stress. Mutations that result in loss of DJ-1 function lead to early onset parkinsonism in humans, and DJ-1 protein is present in pathological lesions of several tauopathies and synucleinopathies. In order to further investigate the role of DJ-1 in human neurodegenerative disease, we have generated novel polyclonal and monoclonal antibodies to human DJ-1 protein. We have characterized these antibodies and confirmed the pathological co-localization of DJ-1 with other neurodegenerative disease-associated proteins, as well as the decrease in DJ-1 solubility in disease tissue. In addition, we report the presence of DJ-1 in a large molecular complex (> 2000 kDa), and provide evidence for an interaction between endogenous DJ-1 and alpha-synuclein in normal and diseased tissue. These findings provide new avenues towards the study of DJ-1 function and how loss of its activity may lead to parkinsonism. Furthermore, our results provide further evidence for the interplay between neurodegenerative disease-associated proteins.
Assuntos
Encéfalo/metabolismo , Corpos de Inclusão/metabolismo , Substâncias Macromoleculares/metabolismo , Degeneração Neural/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Proteínas Oncogênicas/metabolismo , Animais , Anticorpos/imunologia , Especificidade de Anticorpos , Encéfalo/fisiopatologia , Drosophila , Humanos , Corpos de Inclusão/imunologia , Peptídeos e Proteínas de Sinalização Intracelular , Camundongos , Dados de Sequência Molecular , Peso Molecular , Degeneração Neural/fisiopatologia , Proteínas Oncogênicas/imunologia , Doença de Parkinson/metabolismo , Doença de Parkinson/fisiopatologia , Proteína Desglicase DJ-1 , Homologia de Sequência de Aminoácidos , Solubilidade , Sinucleínas , alfa-Sinucleína , Proteínas tau/metabolismoRESUMO
The ability to see at night relies on the transduction of single photons by the rod photoreceptors and transmission of the resulting signals through the retina. Using paired patch-clamp recordings, we investigated the properties of the first stage of neural processing of the rod light responses: signal transfer from rods to bipolar and horizontal cells. Bypassing the relatively slow phototransduction process and directly modulating the rod voltage or current allowed us to characterize signal transfer over a wide range of temporal frequencies. We found that the rod to second-order cell synapse acts as a bandpass filter, preferentially transmitting signals with frequencies between 1.5 and 4 Hz while attenuating higher and lower frequency inputs. The similarity of the responses in different types of postsynaptic cell and the properties of miniature EPSCs (mEPSCs) recorded in OFF bipolar cells suggest that most of the bandpass filtering is mediated presynaptically. Modeling of the network of electrically coupled rod photoreceptors suggests that spread of the signal through the network contributed to the observed high-pass filtering but not to the low-pass filtering. Attenuation of low temporal frequencies at the first retinal synapse sharpens the temporal resolution of the light response; attenuation of high temporal frequencies removes voltage noise in the rod that threatens to swamp the light response.
