| Summary: | 碩士 === 國立陽明大學 === 生物藥學研究所 === 96 === Most of normal human somatic cells undergo limited cell divisions and then enter a non-dividing state termed cellular senescence. Although it was shown that telomere shortening plays a role in cellular senescence, the mechanism underlying this cellular process at the molecular level is less clear. Only a limited number of genes were shown to participate in senescence. In order to identify genes that participate in this process, cDNA microarray analysis was performed to compare the expression of genes in young and aged normal fibroblasts. Among a total of over one hundred genes that their expression levels were altered during senescence, we have selected genes that are involved in cell cycle regulation and proliferation for further analysis. The role of these genes in senescence is addressed using RNA interference to decrease their expression in cancer cells or transforming plasmids to increase their expressions in normal cells. The senescence phenotypes were then analyzed upon these treatments. Among these genes, we found that decreased expression of survivin showed senescence characteristics in HeLa cells. In addition, overexpressing SERPINB2 in BJ-HTERT cells also showed senescence characteristics. The results suggest that those two genes are involved in senescence. To further identify the function of survivin in cellular senescence, we introduced shRNA against survivin to human skin fibroblasts IMR90 using lentivirus-mediated gene delivery system. Decrease the level of survivin in IMR90 cells caused senescence-associated changes both morphologically and biochemically. We have also knockdown survivin in three cell line (wt, p53-/-, and p21-/- HCT116) to elucidate the possible mechanism involved in survivin-induced senescence. Our result indicated that survivin might play a role in senescence that mediates through both p53 and p16 pathway.
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