| Summary: | 碩士 === 國立陽明大學 === 生化暨分子生物研究所 === 97 === The study of gene expression based on epigenetic regulation level mainly includes DNA methylation and histone modifications. According to previous studies, the cell cycle of MCF-7 becomes arrested in G0/G1 phase and apoptosis is induced after TSA treatment for 24 hours. C-fos and c-jun are immediate early genes that form the AP-1 complex. The AP-1 complex is a very important transcription factor that regulates many downstream genes including genes that regulate cell growth and apoptosis. Based on affymetrix microarray data, c-fos and c-jun were upregulated after 24 hours treatment of TSA in MCF-7. TSA is an anti-cancer drug and also a HDACi (histone deacetylase inhibitor) drug that alters epigenetic mechanism. I used bisulfite sequencing to study the DNA methylation pattern of the whole gene and the promoter region of c-fos and c-jun after TSA treatment. I also used ChIP to study the histone modifications of c-fos and c-jun. I found that the DNA methylation pattern of c-jun showed similar patterns before and after TSA treatment. However, the upstream 2000 bps and intron 1 of c-fos becomes unmethylated after TSA treatment. According to ChIP analysis, the level of H3K9 acetylation of c-fos and c-jun increases after TSA treatment. Finally, the results revealed that TSA may affect the demethylation of first intron of c-fos DNA, decrease H3K9 dimethylation and increase H3K9 acetylation to relieve the premature termination block site in intron 1 and upregulate c-fos expression. TSA treatment resulted in the decreased H3K9 dimethylation and increased H3K9 acetylation at the CpG island shore of c-jun to upregulate c-jun expression without affecting the DNA methylation of the gene. The epigenetic regulation mechanism of this gene therefore is at histone modification level but not at DNA methylation level.
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