| Summary: | 碩士 === 國立陽明大學 === 生化暨分子生物研究所 === 100 === The regulation of gene transcription is one of the most important steps for the control of cell survival, growth, differentiation, and apoptosis. In mammals, hemoglobin type exists in different forms at different development stage. In adults, HBA2 gene encodes the protein which is indispensable to compose hemoglobin. One of the aims of this thesis is to gather convincing evidence supporting the hypothesis that HBA2 gene is transcribed not by RNA polymerase II as but by a novel nuclear isoform of mitochondrial RNA polymerase (spRNAP-IV). The K562 cell line has erythroid origin and is used for the study of hemoglobin differentiation. K562 cell can be induced to differentiate into erythrocyte by Ara-C (l-ß-D-arabinofuranosylcytosine), and I found that a variety of hemoglobin transcripts were up-regulated. Interestingly, I found that the induction of transcription of HBA2 gene by Ara-C was resistant to Pol II inhibitors triptolide, suggesting that this gene is not transcribed by PolII and the transcription starts from novel promoters. The second aim of my thesis is to study the role of epigenetic regulation, namely, DNA methylation and histone modifications during the activation of HBA2 gene. In my results show that chromatin structure became more condense, DNA became hypermethylation and not regulated by histone modification(H3K9Ac、H3K27Me3、H3K4Ac and H3K4Me3). In summary, that epigenetic regulation of HBA2 gene is different with general Pol II transcribed gene.
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