| Summary: | 碩士 === 國立成功大學 === 醫學工程研究所 === 90 === DNA microarray technology allows scientists to detect global gene expressions of cells. The goal of this research project is to understand the functions of nucleotide excision repair (NER) factors and the genes that they regulate. The HeLa cells (NER proficient) and XPC mutant cells (NER deficient) were subjected to studies of the responses to post-UVC irradiation by cDNA microarray. The cellular mRNAs from both cell lines were isolated and hybridized to the genes on the cDNA chip. The signals were quantitated by the software ScanAlyze 2 (developed by Brown, C. A.). For statistical analysis microarray data, each experimental condition was performed in triplicates. Principal component analysis (PCA) was then applied to identify genes whose expressional changes were associated. The gene expression changes were also confirmed by the t-test analysis as well as RT-PCR on each individual gene.
By PCA, four major expression patterns were identified, depending on the directionality of expression changes in each gene from the control to various lengths of post-UVC incubation. We found that the expressions of growth arrest and DNA-damage-inducible 153 (GADD153) and growth arrest and DNA-damage-inducible 45, alpha (GADD45A) different in the HeLa cells and XP4PA-SV cells. The GADD153 and GADD45A expressions in other NER proficient and deficient cells were also examined. We found that expression levels of the GADD153 gene did not show a strong correlation with in vivo NER activity. In the case of the GADD45A gene, it was up-regulated in the XPC cells 30 minutes after the UVC irradiation; however, it was induced much later in the NER proficient cells. Besides XPC cells, the NER deficient XPA cells also demonstrated the early induction of the GADD45A gene. It is concluded that the expression of GADD45A gene is immediately activated in these XP cells.
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