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標題: | 分析線蟲的TLK-1蛋白在細胞分裂中對DNA濃縮與分離和在細胞質分裂中的功能 TLK-1 functions in DNA condensation, segregation and cytokinesis in Caenorhaditis elegans |
作者: | Chan-Hsien Yeh 葉蟬嫻 |
指導教授: | 吳益群(Yi-Chun Wu) |
關鍵字: | 有絲分裂,細胞質分裂,染色體濃縮,染色體分離,線蟲, tlk-1,cytokinesis,condensation,AIR-2,Aurora B,Caenorhabditis elegans, |
出版年 : | 2010 |
學位: | 博士 |
摘要: | 在細胞進行有絲分裂過程中,染色體的濃縮與分離和細胞質分裂若是發生異常,就會破壞基因體的完整性並造成生物體的死亡或是癌化。線蟲裡的condensin和AIR-2蛋白,對於細胞分裂能夠正常執行是必需的;TLK-1已被證實是AIR-2的受質及活化物,在AIR-2與另一個活化物ICP-1結合的情況下,能參與它們的作用共同確保染色質分裂能正常進行。然而TLK-1是否有參與染色質濃縮或是細胞質分裂仍是未知問題。在論文裡,我們使用顯微鏡追蹤分析tlk-1突變株發現,TLK-1不只作用在染色體分離過程,也作用在染色體濃縮和細胞質分裂。從結果顯示,TLK-1以不同於ICP-1的作用方式參與染色體濃縮和細胞質分裂,既不影響AIR-2和condensin與染色體結合的能力,整個kinetochore的結構和功能也是正常的,只有染色體的排列有問題。更甚者,TLK-1在細胞分裂過程中的位置分佈也與AIR-2和ICP-1不同,在核膜破裂後TLK-1散布到整個細胞中,而不是結合到染色體上,這也與之前TLK-1的研究結果不一樣;由此可知,TLK-1雖是AIR-2的活化蛋白,但它是以不同於ICP-1的方式和AIR-2共同作用。而TLK-1影響細胞質分裂的分式,則是透過調控AIR-2在細胞分裂末期的分佈,使之能坐落到midzone microtubule以促進細胞質分裂完成。除此之外,TLK-1還可能透過磷酸化HCP-3的模式,使染色體在進行濃縮時能形成正確的結構。最後透過yeast two-hybrid screen,我們發現了一個新的可與TLK-1共同作用的蛋白,DLC-1。TLK-1可能與DLC-1共同影響microtubule和kinetochore的交互作用。 Defects in chromosome condensation, segregation or cytokinesis during mitosis disrupt genome integrity and cause organismal death or tumorigenesis. The conserved kinase protein AIR-2/Aurora B is required for normal execution of all these important mitotic events in C. elegans. TLK-1 has been recently shown to be a substrate and activator of AIR-2 in the presence of another AIR-2 activator ICP-1/INCENP, and to cooperate with AIR-2 to ensure proper mitotic chromosome segregation. However, whether TLK-1 may contribute to chromosome condensation or cytokinesis is unclear. A time-lapse microscopy analysis showed that tlk-1 mutants are defective in chromosome condensation and cytokinesis, in addition to chromosome segregation, during mitosis. Our data indicate that TLK-1 contributes to chromosome condensation and segregation, at least in part, in a manner that is distinct from the ICP-1-mediated mechanism and does not involve loading AIR-2 and condensin complexes to mitotic chromosomes. The overall structure of kinetochore is also normal accompanies with the chromosome alignment defect during metaphase in tlk-1 mutant. Moreover, the localization pattern of TLK-1 is different from the previous data and AIR-2/ICP-1 complex, which TLK-1 diffused to cytoplasm after nuclear envelope broken down. This reveals the differences in dynamic regulation and association of TLK-1 and ICP-1 towards AIR-2 in vivo. Finally, TLK-1 functions in cytokinesis by localizing AIR-2 to the midzone microtubules. Otherwise, TLK-1 may have function in chromosome architecture during chromosome condensation via phosphorylating HCP-3. And via yeast two-hybrid screen, we found a new TLK-1 interacting protein, DLC-1, which may cooperate to regulate the microtubule and kinetochore interaction during mitosis. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/45755 |
全文授權: | 有償授權 |
顯示於系所單位: | 分子與細胞生物學研究所 |
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