| Summary: | 碩士 === 國立成功大學 === 生物資訊研究所 === 97 === Hypoxia/ischemia is related to several diseases processing such as tumor and stroke. Recent studies demonstrate that ischemia-reperfusion induces a multitude of temporally regulated responses in gene expression, and some evidences suggested that Sp1 might be involved in these processes. Sp1 is one of the transcription factors which can specifically bind to GC-rich element in order to regulate the transcription activity of its target genes. In this study, we found that Sp1 was accumulated in cortical neurons of rats, but not in gilal cells under Oxygen Glucose Deprivation ( OGD ) condition and Middle Cerebral Artery Occlusion ( MCAO ) model. To more address this finding, the related experiments were carried out in vivo and in vitro. Data indicated that there is no significant difference in mRNA level of Sp1 and Sp1 stability under OGD condition. After analyzing the Sp1 DNA sequence within 5'-UTR and promoter region, we found one typical IRES-conserved sequence localizing within 5'-UTR of Sp1 genomic sequence. The reporter assay and polysome distribution assay revealed that Sp1 could be accumulated strongly and rapidly under hypoxia/ischemia neuron cells. Furthermore, H2O2 induced by OGD was the key factor to lead the Sp1 accumulation. Inhibition of Sp1 by mithramycin and knockdown of Sp1 by shRNA revealed that the Sp1 accumulation under ischemia-reperfusion leads to neuron cells survival. This is the first time to figure out that Sp1 could be induced through IRES-pathway, this finding might contribute the recovery of neurons after stroke.
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