臺灣博碩士論文加值系統

根據之前的研究發現，約10%~15%左右的癌症是利用端粒重組alternative lengthening of telomeres (ALT)的方式維持端粒(telomere)的長度。而ALT-associated promyelocytic leukemia nuclear bodies (APBs)是ALT cells中其中一個很重要的特點，但APBs形成的詳細機制和在ALT cells中的功能都還有待更進一步的瞭解。在本篇論文中發現，當細胞中表現雌激素受體(estrogen receptor) 或COUP-TF1/TF2的配體結合區(ligand binding domain)和端粒結合蛋白(telomere binding protein)的融合蛋白(fusion protein)時，可以在細胞核中觀察到APBs以及端粒集結(telomere clustering)的現象。另外從本篇論文的結果可以看出這些現象和DNA複製(DNA replication)、DNA損傷反應(DNA damage response)、SMC5/6並沒有關係。除此之外我們也發現端粒集結並不需要PML的參與。因此根據本篇論文，我們推測當核受體(nuclear receptor)的配體結合區結合到端粒上後就足以促進形成APBs和端粒集結的現象。

About 10-15% of tumor cells maintain telomeres through a recombination-based mechanism known as alternative lengthening of telomere (ALT). ALT-associated promyelocytic leukemia bodies (APBs) are one of the hallmarks of ALT cells, but detailed descriptions of the mechanisms of APB formation are still lacking. Here, we reveal APB formation and telomere clustering are triggered when ERT2, the ligand-binding domain of estrogen receptor, fuses with TRF1, TRF2 or TRF2∆B in BJ5TA and U2OS cells. We show that DNA replication, the DNA damage response (DDR) and the SMC5/6 complex are not required for APB formation. Moreover, telomere clustering and DAXX co-localized with telomeres are PML-independent. However, we also found APBs and telomere clustering when COUP-TF1/TF2 ligand-binding domain (LBD) are fused with TRF1. We propose that the LBD of nuclear receptors localized at telomeres are sufficient for APB formation and telomere clustering.

誌謝 i
Abstract ii
摘要 iii
Contents iv
Introduction 1
Results 4
Expression of ERT1-TRF2 fusion protein in BJ5TA and U2OS cells generates APBs 4
APB formation and telomere clustering are time-dependent 5
ECTRs, SMC5/6 and NBS1 are not essential for APB formation in BJ5TA-ERT2-TRF2B cells 6
A DNA damage response (DDR) is not sufficient to trigger APB formation 8
PML is not required for telomere clustering 9
ERT2 and the COUP-TF1/TF2 ligand-binding domain localize to telomeres trigger APB formation 10
siZNF827 specifically affects APBs that are generated by COUP-TF1LBD and COUP-TF2LBD 12
Discussion 14
Material and Methods 20
Reference 30
Figures 35
Fig. 1 35
Fig. 2 39
Fig. 3 41
Fig. 4 43
Fig. 5 45
Fig. 6 48
Fig. 7 52
Fig. 8 55
Table 1 58

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