The Study On Methylation Of PLA2G4C Promoter In Schizophrenia

Schizophrenia is a common and serious mental disorder, whose pathogenesis remains undefined. The accumulating genomic evidence indicates that schizophrenia is etiologically complex, involving multiple factors include heritable factors and environmental influences. The studies of schizophrenia on genome scanning and candidate gene have acquired many positive results, however, these results with poor repeats have caused much disputation. So far, the major and specific susceptibility genes leading to schizophrenia remains unidentified. Schizophrenia associated environmental exposures, particularly at key developmental stages, may result in long-lasting epigenetic alterations that impact on the neurobiological processes involved in pathology. Several studies conducted by our laboratory demonstrated that there was increased serum PLA2 activity but no SNP locus in the PLA2 family gene association with schizophrenia in case-control samples. Based on the work we have done before, here we investigated the status of DNA methylation in a typical CpGs island in the PLA2G4C promoter by bisulphite sequencing in schizophrenia and control group who were born in 1960-1965, aiming to determine the possible involvement of the epigenetic mechanisms in the schizophrenia associated altered pattern of the PLL2G4C gene expression.Objective:In the present study, we investigated the status of DNA methylation in a typical CpGs island in promoter of PLA2G4C by bisulphite sequencing with schizophrenia and healthy person who were born in 1960-1965, aiming to determine the possible involvement of the epigenetic mechanisms in the schizophrenia associated altered pattern of the PLA2G4C gene expression. Trying to discuss the relationship between famine and DNA methylation in promoter of PL A2G4C.Methods:Genomic DNA samples were extracted from whole solidification blood using the Column Blood Clot DNA out (Andybio). Bisulphite conversion of DNA was carried out with the CpGenome DNA Modification Kit. A CpG island which spans partial 5 '-flanking sequence, around Transcription Start Site of PLA2G4C Gene and partial intron 1 region was found using a CpG island searcher (Methyl Primer Express v1.0). Two pairs of primers were used to amplify the sequences from the -405 bp to 101 bp. The products were then sequenced using an ABI BigDye Terminator Cycle Sequencing Kit (Perkin-Elmer Applied Bio-systems, Foster City, CA) on an ABI 3730 DNA sequencer (Applied Bio-systems). DNA methylation distributions was tested using the chi-square (χ2) goodness-of-fit test performed with the SPSS 16.0 program.Result:Our results showed that①There are three cytosines Methylation modification was only found in sites -13CpT,13CpG and +13CpT.②The three cytosines sites methylation modification occurred both in patients and in the normal subjects and the analytic results showed that -13CpT methylation is higher in schizophrenia. No statistically significant difference was found in frequency of methylation modification of -13CpT and +13 CpT between patients and normal.③The also found that the Hypermethylation of cytosine-13 in schizophrenia who were born during post-famine(1963-1965) and there is statistically significant difference (P<0.05). But there was no association between methylation level of the other sites (13CpG,+13CpT) and schizophrenia who were born during post-famine④There is no statistically significant difference (P>0.05) between the level of the three cytosines (-13CpT,13CpG and +13CpT) methylation and famine.Conclusions:According to the above-mentioned analytic results,we can reach the following conclusions:①Not only cytosines of CpGs but cytosines of CpTs were methylated in promoter of PLA2G4C region (-405 bp to +101 bp).②There is association between the PLA2G4C promoter CpG sites suggested that there was no association between methylation level and either disease③there was no association between methylation level of the three sites (13CpG,13CpG and +13CpT) and genders.④there was no association between methylation level of the three sites (13CpG,13CpG and +13CpT) and famine.