| Parkinson's disease (PD) is a neurodegenerative disorder that ischaracterized by muscle tremors in stationary limbs, bradykinesia anddifficulty initiating and sustaining movements, and affects 1-2% of thepopulation older than sixty years of age. As the disease progresses, boththe sense of balance and the memory of the affected individualdeteriorate. Post-mortem analysis reveals the selective loss ofdopaminergic neurons from the substantia nigra region of the brain.Filamentous protein inclusions, known as Lewy bodies, are found withinthe neuronal cell bodies of the affected area, in most but not all PDpatients. At Present there is still no effective treatment for the disease,some drugs such as L-DOBA can just lessen the clinical symptom.Although the majority of PD cases appear to be sporadic, about5-15% has been determined to have an inherited basis. Recently,mutations in at least six genes have been identified as causes of PDincluding theα-synuclein, UCHL1 and LRRK2 with autosomaldominant inheritance and Parkin, PINK1 and DJ-1 with autosomalrecessive inheritance. Many of these genes are associated with theubiquitin/proteasome protein degradation (UPS) pathway. Parkin act asan E3 ligase,α-synuclein, the main component of Lewy body and itsinteracting protein synphilin-1 are the substrates of Parkin. PINK1,located in the mitochondria, is associated with the oxidative stress. LRRK2 posses the kinase activity, increased LRRK2 kinase activityplays an essential role in pathogenic LRRK2 mutant-inducedneurodegeneration in vitro, moreover it can regulates neurite processmorphology in primary cultured rat neuronal cells. Although Lewybodies are a prominent pathologic feature of PD, the underlyingmolecular pathogenic mechanisms accounting for Lewy-body formationand the interaction between these genes are poorly understood.Drosophila has become an important tool for the research of humaninheritance disease especially neurodegenerative disorder. Among the sixhuman PD associated gene, five of them have homolog gene indrosophila, including UCHL1(Uch/CG426), LRRK2 (CG5483),Parkin(parkin/CG10523), PINK1(Pink1/CG4523), DJ-1(DJ-1a/CG6646, DJ-1b/CG1349), and their function is very similar.In this study, interaction betweenα-synuclein and PINK1 indrosophila is investigated; moreover a LRRK2 Knockout drosophilamodel is used to figure out the role of LRRK2 in pathogenesis of PD.Cross the fly line UAS-α-synuclein (WT,A30P,A53T) withUAS-hPINK1 to get the lines UAS-hPINK1; UAS-α-synuclein(WT,A30P,A53T), then cross with GAL4 line to expressα-synuclein andPINK1 separately and simultaneously, treat the flies with different drugsto detect the survival rate, after co-express these two genes, the survivalrate has improved than only expressα-synuclein. On the other hand,immunostaining the neurons to observe the variation under the fluorescent microscope, the numbers of dopaminergic neuron in thegroup expressing these two genes are more than the group justexpressingα-synuclein. These results suggested that PINK1 can resistthe oxidative stress, and protect the neuron loss.Identified the LRRK2 Knockout fly line by RT-PCR, we found thatLRRK2 is no kinase activity. Observed the character of the line, thesemutant flies are viable, fertile and developed with no obvious externalabnormality, and showed similar life span to wildtype counterparts. Afterexposure to oxidants, the mutant flies showed little difference in survivalfrom wildtype. Immunostained the small ventral lateral neurons anddopaminergic neurons, no notable change of number and distribution ofDA neurons in mutant flies at age 1 and 30 day, but there are apparentabnormity including the morphology, branch and length in the nurites.These results suggest that LRRK2 kinase activity is essential for neitherdopamiergic neuron survival nor protection from oxidative stress, but itplays an important role in sustaining the neurite growth.In summary, these results will benefit for explaining the mechanismof PD, screening for drugs in scale and finding out new drugs for PD.
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