乙醯基化及去乙醯基化對p53蛋白的調控

The regulation of p53 by acetylation and deacetylation

陳姿均(Tze-Chun Chen)

指導教授 ： 顏伯勳

國立臺灣大學/醫學院/生物化學暨分子生物學研究所/碩士(2016年)

https://doi.org/10.6342/NTU201610268

摘要

p53是個有很多重要細胞功能的蛋白，例如扮演腫瘤抑制子。面對各種壓力刺激時，p53會誘導特定的轉錄機轉，藉此調控細胞週期、細胞凋亡、細胞老化以及基因體的穩定。在細胞中，p53的表現和活性會被許多不同的後轉譯修飾，像是泛素化 (ubiquitination)、乙醯基化 (acetylation)、磷酸化 (phosphorylation)、甲基化 (methylation) 等所調控。不同類型的後轉譯修飾會參與p53的各類調控，有些會影響p53的穩定度，有些能夠調控活化基因表現的能力，有些則可能改變p53在細胞中的分佈。人類的SP110核質體蛋白可能參與調控基因轉錄、細胞死亡以及免疫反應，但目前對於其功能不是很清楚。實驗室先前的研究發現了SP110的其中一個異構物SP110b會與p53有交互作用。而且當SP110b大量表現時，p53在細胞內的分佈也會受到影響，使p53從原本分佈於整個細胞改變至只累積在細胞核內。進一步由液相層析串聯式質譜儀分析，發現SP110b的表現會使 p53上X 位點以及Y 位點出現被乙醯基化的現象，此現象可能會影響到p53的穩定度及活性。本論文於是進一步探討這兩個位點的乙醯基化對於p53可能的影響。實驗結果發現X或是Y位點的乙醯基化會增加p53的活性且改變p53在細胞內的分佈，尤其是Y位點乙醯基化所造成的影響更為明顯。然而，X或是Y位點的乙醯基化並不會影響到p53的穩定度。此外，p53 X及Y位點的乙醯基化在SP110b表現時對p53活性之影響會更加明顯。本論文的研究結果可以提供部份新的資訊解釋SP110b如何影響p53。

關鍵字

p53 ； SP110b ； 乙醯基化 ； 後轉譯修飾 ； 蛋白穩定度

並列摘要

p53, a protein with several cellular functions such as tumor suppressor, has well-established roles in monitoring various types of stress signals by activating specific transcriptional targets that control cell cycle, apoptosis, senescence as well as genomic DNA stability. In the cells, there are a multitude of post-translational modifications (PTMs), like ubiquitination, acetylation, methylation and phosphorylation, which could alter p53 protein level and activity in response to stresses. These different types of PTMs on p53 that usually influence protein stability, transcriptional activity or protein distribution may reflect different responses of p53. In human, SP110, a nuclear body protein, may involve in the regulation of transcriptional expression, cell death and immune response. However, the distinct functions should be further elucidated. In the previous work in the lab, we found that SP110b, one of SP110 major isoforms, has directly protein-protein interaction with p53. In the presence of SP110b overexpression, the localization of p53 was changed from the whole cell to the nucleus. Moreover, through LC MS/MS analysis, we found that SP110b expression induced acetylation of X and Y sites on p53 that may influence protein stability and activity. In this thesis, the studies were designed to determine whether the acetylation on X and Y sites could affect the functions of p53. The results demonstrated that the acetylation on the two sites affects p53 activity and cellular distribution and that, especially, the acetylation of Y site has stronger effects than those of X site. However, p53 stability doesn’t be affected by acetylation of X or Y site on p53. Besides, SP110b expression increased the X or Y site acetylation-mediated effect on p53 activity. The results of these studies provided a piece of new information to explain the relationship between SP110b and p53.

並列關鍵字

p53 ； SP110b ； Acetylation ； Protein stability ； Post-translational modification

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