DNA Methylation Study In α-synuclein A53T Transgenic PD Mouse Model

Parkinson’s disease (PD), also know as paralysis agitans, is a common neurodegenerative disease of old people. The prevalence is more than1%of the population over65years old, and it has become the second top neurodegenerative disease after Alzheimer’s disease. With the aging of population, the incidence rate shows an increasing trend. DNA methylation is the most important and deeply understood epigenetic modification in mammal. Mounting studies have shown a pivotal role that methylation plays in PD etiology and development. However, those researches mainly focus on one or several special genes and test their methylation status at promoter regions, lacking of genomic level studies.Objective To test the methylation status alternations of a-synuclein A53T transgenic PD mouse model at genomic level and summary the involved signal pathways. Investigate methylation changes among the PD causative loci PARK1-18, and study those genes’ expression level.Methods Extract DNA and RNA from substantial nigral of24transgenic and24normal control mice. Use5-methylcytosine antibody immunoprecipitation method combines with high-density microarray hybridization (MeDIP-Chip) to depict the global changes in DNA methylation between the two groups, and analysize the pathways involved in the altered genes. Use Bisulfite Sequencing PCR (BSP) technology to test the methylation levels of interesting genes. Utilize RT-PCR method to study gene’s expression level.Results The DNA Methylation Chip scanned12535genes’promoter regions in the two groups, and found3572genes had methylation alternations. Compare to normal control, transgenic mice had2031genes with hypomethylation status, and1541genes had increased methylation level. Pathway analysis showed that the involved genes relevant to over20signal pathways, including glycine, serine and threonine metabolism, proteasome, SNARE interactions in vesicular transport, P53signaling pathway, ubiquitin mediated proteolysis, WNT signaling pathway, NOTCH signaling pathway, etc. Among them, SNARE interactions in vesicular transport, ubiquitin mediated proteolysis and WNT signaling pathway were considered as closely related to PD. BSP result showed PARK5(Uchll) and PARK15(Fbxo7) were both with significant hypomethylation status in transgenic mice, with Uchll p=0.012*; Fbxo7p=0.002*. Uchll gene expressed significantly increased in transgenic mice (p=0.017*), but Fbxo7had no different expression level between the two groups (p=0.472).Conclusions1. This is the first research that uses a-synuclein A53T transgenic PD mice model to study DNA methylation alternations wordwild. They have abnormal methylation status, and several signaling pathways are involved2. MeDIP-Chip is an effective method for genome-wide analysis of DNA methylation changes. The involved genes can be further studied in future reaearches3. PARK5(Uchll) and PARK15(Fbxo7) are both significant hypomethylation in transgenic mice. Uchll gene’s expression level is significantly increased in transgenic mice4. The transcription level of PARK5(Uchll) can be regulated by the CpG island methylation status of its promotor region...