人類類哺乳類Ste20激酵素3 (Mst3)在粒線體中之角色與作用機轉研究

Abstract

本計畫的主要目標為瞭解人類Ste20 蛋白激酵素3 (Mst3)在不同次細胞分隔區中 (尤其是在粒線體中)的生理角色。在前期的研究中，我們發現Mst3 可同時存在於細胞 質及粒線體中。然而，Mst3 在這些次細胞分隔區中的角色目前仍不清楚。許多個證據 已顯示Mst3 可能在粒線體中扮演重要的角色。例如，Mst3 不只會與凋亡促進因子 (apoptosis-inducing factor; AIF)及核酸內切酵素G (Endonuclease G; EndoG)結合成為一 促凋亡的蛋白複合體，亦參與了調控與它們有關的核酸酶活性。而以RNAi 選擇性的降 低Mst3 表現也發現會造成粒線體生物能量生合成的變異。這些結果顯示我們必須對 Mst3 在粒線體中角色與作用機轉進行更具系統性的研究。因此，在這一個三年期的計 畫中，我們希望研續先前的研究規畫，在Mst3 對粒線體的完整性、形態學變動及生物 能量生合成等議題上作進一步研究。另外，在Mst3 與AIF 及EndoG 形成蛋白複合體 及調控AIF 及EndoG 在粒線體中與在細胞凋亡過程中活性等議題，亦是本計畫的研究 重點。此外，我們提議以蛋白質體學對粒線體進行大範圍的篩選，以找出會受到Mst3 影響或是調控的粒線體蛋白。我們希望藉由這些實驗所獲得的結果，可讓我們更加瞭 解Mst3 在粒線體中的角色與分子作用機轉。

The main objective of this project is to understand the physiological role of mammalian Ste20-like protein kinases 3 (Mst3) in different subcellular compartments, especially in mitochondria. Previously, Mst3 was shown to distribute in both cytoplasm and mitochondria. However, the role of Mst3 in these compartments is still unclear. Several lines of evidence suggest that Mst3 may play important roles in mitochondria. For example, Mst3 was shown not only to form complex with AIF and EndoG, but also to regulate the nuclease activity associate with them. The bioenergetics of mitochondria was also altered by the selective knockdown of Mst3. These results suggest that a systematic study on the role and molecular mechanism of Mst3 in mitochondria is necessary. Therefore, in this three-year proposal, we want to extend our previous studies to further investigate the role of Mst3 in the mitochondrial integrity, morphology dynamics and bioenergetics. The interaction between Mst3 and AIF and/or EndoG and the role of Mst3 in regulating their activity in mitochondria as well as during apoptosis are also important issues in this proposal. Lastly, we propose to perform a wide range survey by proteomics for mitochondrial proteins that may be affected or regulated by Mst3. It is our hope that the results obtained from this project can provide a framework for understanding the role of Mst3 in the mitochondria and serving as guiding principles for the ongoing researches.