Study KLF4-mediated telomere activation and search inhibitors for telomere replication

• Main Authors: Meng-hsun Hsieh, 謝孟勳
• Other Authors: 鄧述諄
• Format: Others
• Language: en_US
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/88159721120193570826

碩士 === 臺灣大學 === 微生物學研究所 === 98 === Telomeres are dynamic DNA-protein complexes that protect the ends of linear chromosomes from genome instability and end fusion. Most telomeric DNA is synthesized by the enzyme telomerase. Stem cells are characterized by the ability to renew themselves through mitotic cell division and differentiating into a diverse range of specialized cell types. The KLF families are transcriptional factors that regulate a diverse array of cellular processes, including development, differentiation, proliferation and apoptosis. KLF4, a member of this family, functions as a transcriptional activator or repressor depending on the interaction partner and the context of the binding sites. We have identified a potential MAPK phosphorylation site on KLF4 by mass spectrometry. Additionally, multiple KLF4 interacting proteins were identified. All these modification and interactions may define the specificity and refine its roles in different cells. Since the major targets of KLF4 are p21 in differentiated somatic cells and telomerase in undifferentiated stem cells, our goal is to elucidate the molecular mechanism and biological contribution of KLF4-mediated p21 repression in cancer cells and telomerase activation in stem cells. Cancer cells can elongate telomere either through telomerase reactivation or through an alternative recombination pathway for telomere lengthening (ALT). In this study, we investigate telomere recombination in mammalian. We have shown that topoisomerase 2 and 3 are all required for the ALT in yeast cells. Topoisomerase 2 resolves hyperpositively supercoiled DNA before recombination forks and topoisomerase 3 resolves hypernegatively supercoiled DNA after recombination forks. Topoisomerase 2 and 3 are not required for telomere recombination when supercoiled DNA is not formed. Adding topoisomerase 2 poison, mitoxantrone, in medium could also conferred telomere shortening and alter many phenotypes in ALT cells. So far there is no drug developed to inhibit ALT, so we are looking forward to find TOP2 poisons or inhibitors can inhibit both Type II recombination and ALT pathway. In previous data showed that knockdown of TOP3 in ALT cells could reinitiate telomerase activity for cell survive, we are also wish to find a treatment combine both telomerase inhibition and ALT blockage for complete therapy in ALT cancer.