PSAP诱导独特的不依赖于Bcl-2家族蛋白的线粒体凋亡途径

发布时间：2018-06-28 17:44

本文选题：阿尔茨海默症 + 细胞凋亡　；参考：《吉林大学》2012年博士论文

【摘要】：Presenilin相关蛋白PSAP （Presenilin-associated protein），是一种线粒体促凋亡蛋白。然而，PSAP诱导凋亡的机制至今仍然悬而未决。为了解决这一问题，我们在HEK293细胞中建立了一个可诱导PSAP过表达的系统，运用这一体系，我们检测了在PSAP过表达引起的凋亡中，不同因子发挥的作用。这些因子包括：半胱氨酸天冬氨酸酶（Cysteine aspartic acid specific protease，caspases，简称半胱天冬酶）， Bcl-2家族蛋白，细胞色素c， Smac蛋白（Smac/Diablo, second mitochondria-derived activator of caspases/direct IAPbinding protein with low PI）， Apaf-1蛋白（apoptotic protease-activatingfactor）。我们的结果显示，PSAP诱导的凋亡依赖于caspase的活性。抑制caspase-9基因的表达阻断PSAP引起的PARP切割和caspase的活化，但是caspase-8基因的抑制表达对PSAP引起的凋亡没有影响。这一现象说明，在PSAP过表达引起的凋亡级联反应中，caspase-9充当起始caspase的作用。除了caspase-9，， Apaf-1基因的抑制表达也能够阻断PSAP引起的caspase活化和PARP切割，说明由细胞色素c引起的凋亡复合体—apoptosome—的形成对PSAP诱导的凋亡至关重要。除此之外，Smac基因的抑制表达也能阻碍PSAP过表达引起的caspase活化和PARP切割。这一结果说明，除了Apaf-1或凋亡复合体的形成，Smac对于PSAP介导的凋亡同样不可或缺。抗凋亡蛋白Bcl-2或Bcl-xl的过表达不能抑制PSAP引起的细胞程序性死亡，而抑制促凋亡蛋白Bid，Bax和Bak的基因的表达同样不影响PSAP引起的细胞色素c和Smac从线粒体中释放到细胞质中。以上结果说明PSAP引起的凋亡不受Bcl-2家族蛋白的调控。因此，PSAP引起特殊的线粒体途径的凋亡，这一特殊的途径不受Bcl-2家族蛋白调控，但依赖于细胞色素c-Apaf-1-凋亡复合体的形成，以及Smac从线粒体中的释放。
[Abstract]:Presenilin associated protein), (PSAP) is a mitochondrial apoptotic protein. However, the mechanism of apoptosis induced by PSAP is still unknown. In order to solve this problem, we established a system to induce overexpression of PSAP in HEK293 cells. Using this system, we examined the role of different factors in apoptosis induced by overexpression of PSAP. These factors include: cysteine aspartic acid specific protease caspases, Bcl-2 family proteins, cytochrome c, Smac protein (second mitochondria-derived activator of caspases/direct IAPbinding protein with low Pi), Apaf-1 protein (apoptotic protease-activatingfactor). Our results showed that apoptosis induced by PSAP-dependent on the activity of caspase. Inhibition of the expression of caspase-9 gene blocked PARP-cleavage and caspase activation, but the inhibitory expression of caspase-8 gene had no effect on the apoptosis induced by caspase-8. This phenomenon suggests that caspase-9 acts as the initiator of caspase in the cascade of apoptosis induced by overexpression of PSAP. In addition to caspase-9, the inhibitory expression of Apaf-1 gene also blocked the activation and cleavage of caspase induced by caspase, which indicated that the formation of apoptotic complex -apoptosome- induced by cytochrome c was crucial to the apoptosis induced by caspase. In addition, the inhibitory expression of SMAC gene also blocked the activation and cleavage of caspase induced by PSAP-overexpression. These results suggest that in addition to the formation of Apaf-1 or apoptotic complex, SMAC is also essential for PSAP-mediated apoptosis. Overexpression of anti-apoptotic proteins Bcl-2 or Bcl-xl did not inhibit programmed cell death induced by PSAP, while inhibition of the expression of bid-Bax and Bak genes did not affect the release of cytochrome c and SMAC from mitochondria into cytoplasm. These results suggest that apoptosis induced by PSAP is not regulated by Bcl-2 family proteins. Therefore, PSAP induces apoptosis through a special mitochondrial pathway, which is not regulated by Bcl-2 family proteins, but is dependent on the formation of cytochrome c-Apaf-1- apoptotic complex and the release of SMAC from mitochondria.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2012
【分类号】：R749.16

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