The Research Of Neuroprotective And It’s Mechanism By Upregulating The Expression Of Parkin In SCA3/MJD Transgenic Drosophila Model

Objective:Spinocerebellar ataxia(SCA) is a common inheritedneurodegenerative disorder, the subtype SCA3is the most common one in China.It has been found that the abnormal expansion of the coding region of virulencegene CAG is the main pathogenesis,and it results in the intracellularaccumulation of the misfolded protein ataxin-3leads to the neurotoxicity;impaired mitochondria also plays an important role in the pathogenesis. Parkinis an ubiquitin protein ligase catalyzing the covalent attachment of ubiquitinmoieties onto substrate proteins,and it leads to the toxic protein degradationthrough the ubiquitin-proteasome pathway; furthermore Parkin mediatesmitochondrial fission, it contributes to the clearance of impaired mitochondriaby mitochondrial autophagy pathway to improve mitochondrial function. In thisexperiment,we use a SCA3/MJD transgenic Drosophila model to investigatewhether upregulated expression of Parkin plays a neuroprotective role and howit works.Methods:We use the Nrv2-GAL4driver of the classical GAL4-UAS system toselectively express ataxin-3protein fragment which contains78repeats of CAG(MJDtr-Q78) in the drosophila motoneuron to construct SCA3/MJD transgenicdrosophila model of the Nrv2-GAL4/UAS system,followed by the hybridizationwith Parkin to interfer SCA3/MJD transgenic drosophila model ofNrv2-GAL4/UAS system. We respectively performed the experments to detectthe flight ability,rate of the morphological abnormalities of wings,lifespananalysis,ATP content of the brain,pathogenic protein content of the brain and the mitochondrial morphology of the flight muscle by electron microscope.Results:Successfully constructed SCA3/MJD transgenic drosophila model ofthe Nrv2-GAL4/UAS system and expressed upregulation of Parkin in thismodel.We found that the flight ability decreased significantly, rate of themorphological abnormalities of wings increased obviously, the mean and themaximun lifespan significantly decreased, ATP content in brain decreased in theSCA3/MJD transgenic drosophila model of the Nrv2-GAL4/UASsystem,however after using upregulated expression of Parkin to interfere thismodel,it reveals that the flight ability,mean and the maximun lifespan, ATPcontent of the brain and the integrity of the flight muscle mitochondria improvedas well as the reduction of the pathogenic protein content of the brain and therate of the morphological abnormalities of wings.Conclusion:(1) Upregulated expression of Parkin plays a neuroprotective role inSCA3/MJD transgenic drosophila model.(2) Upregulated expression of Parkinmay protect the nervous system in SCA3/MJD transgenic Drosophila modelthrough enhancing the degradation of the ataxin-3toxic protein and theprotection of mitochondrial morphology.