TNFα介导的信号具有多样性，既可以促进细胞生存，也可以诱导细胞凋亡及坏死；但对坏死的调控机制及其相关信号转导网络尚未完全明了。新近的研究显示细胞坏死同细胞凋亡一样存在外源死亡受体及内源线粒体介导的信号通路，外源死亡受体及RIP1/RIP3介导的信号最终通过促进线粒体分裂而诱导细胞坏死；而内源线粒体介导的细胞坏死则涉及已知的Bcl-2家族促凋亡蛋白，但这些蛋白最终如何介导细胞坏死，是否也涉及对线粒体分裂的调控尚不得而知。我们前期的研究首次发现，在存在组成性Ripoptosome的L929细胞，TNFα可以通过RIP1激酶活性依赖的Bid蛋白剪切及Bax/Bak活化诱导RIP3非依赖的细胞坏死。本研究将继续探讨RIP1激酶活性涉及Bid剪切的分子机制、寻找除Casp-8之外在坏死条件下介导Bid剪切的酶以及Bid剪切促进Bax/Bak活化对线粒体分裂及细胞坏死的调节，阐明坏死调控的新机制。

TNFα can either induce apoptosis, or induce necroptosis when the activation of caspase-8 is inhibited by pan-caspases inhibitor z-VAD. Necroptosis is a specialized pathway of programmed necrosis, however the molecular mechanisms and signal transduction pathways of necroptosis are mostly less-defined. Recent studies indicated that, just like apoptosis, there are two necrosis-inducing pathways as well. The extrinsic signal is initiated by the assambly of TNFα-induced RIP1/RIP3/MLKL necrosome, leading to the activation of mitochondrial phosphatase PGAM5 and mitochondrial fission factor Drp1. Whereas, the intrinsic necrosis-inducing signals, such as ROS, can directly activate PGAM5 and Drp1 independent of RIP1/RIP3/MLKL. The activation of PGAM5 and Drp1 leads to abnormal mitochondrial fission and necrosis. In this study, we will investigate the important role of TNFα-induced and RIP1-dependnent cleavage of Bid and Bid-dependent activation of Bax/Bak on regulation of PGAM5 and Drp1, we will also investigate except Casp-8, whatelse enzyme involves Bid cleavage, and whether casapase-dependent activation of Bax/Bak or the downexpression of Bcl-xL could affect the PGAM5/Drp1 complex in a way independent of RIP1/RIP3/MLKL complex. These results will help to illucidate the pro-necrosis or anti-necrosis effects of Bcl-2 family proteins on necroptosis, and find nevol molecular targets which can regulate necroptosis.