AIBp調控Aurora A和Plk1來控制細胞進入有絲分裂

AIBp protein regulates Aurora A and Plk1 to control mitotic entry

高琮傑(TSUNG-CHIEH KAO)

指導教授 ： 洪義人

高雄醫學大學/醫學院/生物化學研究所/碩士(2013年)

摘要

在真核生物有絲分裂的過程中，中心體在紡錘體的形成具有重要的作用，而紡錘體的兩極化是確保染色體能被準確地分離到子細胞和維持基因組穩定的關鍵，而雙極紡錘絲形成是染色體分離的首要條件。先前報導指出，中心體異常會導致染色體形成錯誤、基因組不穩定以及腫瘤的形成。最近的研究證據讓我們比較可以了解 Aurora kinase A(Aurora A)，Polo-like kinase 1 (Plk1)和其結合蛋白 (Bora和Furry)是如何交互作用。先前我們發現了一種新穎的 Aurora A和 hNinein結合蛋白，AIBp，它與中心體結構的維護以及紡錘絲形成有關。在此，我們利用酵母菌雙雜交和免疫共沉澱發現 AIBp會與 Plk1交互結合。利用 kinase assay發現AIBp不僅是 Aurora A和 Plk1的受質且可以正向調控 Aurora A及 Plk1的活性；然而 AIBp與 hNinein 結合卻會阻礙了Aurora A和 Plk1對 hNinein的磷酸化。其角色類似於 Bora或 Furry，AIBp結合 Plk1，爾後促使 Aurora A去磷酸化Plk1在 Thr210位置，且可以維持住在細胞分裂時Plk1的活性。此外，在 HeLa癌細胞株中，利用 siRNA調降AIBp表現，發現會造成細胞分裂異常形成不對稱分裂紡錘絲、類似甜甜圈形態的染色體及多紡錘絲構造並且損害了Aurora A和Plk1 kinase的活性。綜合以上，我們的研究結果顯示出AIBp可能是一種支架蛋白分別與Aurora A和 Plk1結合，進而形成了一個功能複合體來調控 hNinein磷酸化以決定細胞是否進入有絲分裂。

關鍵字

Aurora-A ； Plk1 ； Bora ； Furry ； AIBp

並列摘要

Centrosome has a crucial role in the formation of bipolar mitotic spindles, which are essential for mitotic integrity and accurate chromosomal segregation during cell cycle in eukaryotic cells. Bipolar mitotic spindle is an integral prerequisite for chromosome segregation. Previous study reports centrosome abnormalities lead to deficit of chromosome formation, genomic instability and carcinogenesis. Recent evidences have led to a better understanding for how Aurora kinase A (Aurora A), Polo-like kinase 1 (Plk1) and their binding proteins (Bora and Furry) are intertwined. We have previously reported a novel Aurora A and hNinein binding protein, AIBp, facilitates a role in maintaining centrosomal structure and contributes spindle formation. Here, we identified AIBp also binds to Plk1 by using yeast two-hybrid and co-immunoprecipitation. In kinase assay, AIBp acts as not only a substrate but also a positive regulator towards both Aurora A and Plk1; however, AIBp blocks the phosphorylation of hNinein mediated by Aurora A and Plk1. As similar role as that of Bora and/or Furry, AIBp binds to Plk1, subsequently promotes Aurora A-mediated Plk1 activation at Thr210 and maintains activity of Plk1 during mitosis. Moreover, siRNA-mediated knockdown AIBp expression in HeLa cells impaired both Aurora A and Plk1 kinase activity, which resulted in phenotypes of doughnut-like shape chromosomes, asymmetrical spindle pole, multiple spindle pole formation and chromosome misalignment. Together, our results suggest that AIBp may function as a bridge protein for Aurora A and Plk1, forms a functional complex, and may also regulate hNinein phosphorylation to control mitotic entry.

並列關鍵字

Aurora-A ； Plk1 ； Bora ； Furry ； AIBp

參考文獻

1 Bettencourt-Dias, M. & Glover, D. M. Centrosome biogenesis and function: centrosomics brings new understanding. Nature reviews. Molecular cell biology 8, 451-463 (2007).

2 Sluder, G. Two-way traffic: centrosomes and the cell cycle. Nature reviews. Molecular cell biology 6, 743-748 (2005).

3 Bornens, M. Centrosome composition and microtubule anchoring mechanisms. Current opinion in cell biology 14, 25-34 (2002).

4 Doxsey, S. Duplicating dangerously: linking centrosome duplication and aneuploidy. Molecular cell 10, 439-440 (2002).

5 Holland, A. J. & Cleveland, D. W. Boveri revisited: chromosomal instability, aneuploidy and tumorigenesis. Nature reviews. Molecular cell biology 10, 478-487 (2009).