Activation and in vivo Functions of Initiator Caspases

描述（由申请人提供）：Caspases在多种细胞过程中发挥重要作用，包括细胞凋亡、细胞生长和增殖以及细胞因子成熟。位于凋亡信号级联顶端的Caspases被称为启动Caspases。它们在诱导细胞凋亡信号传导中起关键作用。目前，引发剂半胱天冬酶激活的精确分子机制尚未得到解决。此外，很难评估这些半胱天冬酶的体内功能，因为它们在小鼠中的敲除会导致胚胎致死。本课题拟通过实验研究引发剂caspase的激活分子机制和体内功能：1)测试二聚体依赖性caspase的激活机制。晶体结构研究表明，半胱天冬酶在自身激活之前形成同型二聚体。我们将使用诱导二聚体系统来研究二聚体中的两个半胱天冬酶分子如何相互作用导致半胱天冬酶激活。2)检测caspase的激活级联。Caspases可能形成信号级联传递凋亡信号。凋亡信号级联过程中不同半胱天冬酶之间的相互作用尚不清楚。我们将研究两种不同的半胱天冬酶是否在原半胱天冬酶水平和凋亡信号级联中相互作用。3)分析caspase-8和caspase-9在条件敲除模型中的功能。Caspase-8和caspase -9分别是死亡受体依赖性和线粒体依赖性凋亡的启动剂caspase。然而，常规敲除caspase-8和caspase-9会导致胚胎或围产期死亡，因此很难评估这些caspase的体内功能。我们将在小鼠中条件敲除caspase-8和caspase-9，以研究它们在体内的功能：这些研究将有助于阐明caspase的激活机制和促凋亡caspase在体内调节T细胞功能的功能，从而促进设计针对这些caspase治疗自身免疫性疾病和癌症的治疗方法。

DESCRIPTION (provided by applicant): Caspases play important roles in multiple cellular processes, including apoptosis, cell growth and proliferation, and cytokine maturation. Caspases at the top of the apoptosis signaling cascade are called initiator caspases. They are critical in inducing the onset of apoptosis signaling. Currently, the precise molecular mechanisms for the activation of initiator caspases have not been resolved. Moreover, it has been difficult to assess the in vivo functions of these initiator caspases because their knockouts in mice cause embryonic lethality. In this proposal, experiments are proposed to study the molecular mechanisms of activation and in vivo functions of initiator caspases: 1) To test the mechanism of dimer-dependent caspase activation. Crystal structural studies suggest that caspases form homodimers prior to their autoactivation. We will use an inducible dimeric system to study how the two caspase molecules in the dimer interact to cause caspase activation. 2) To examine the caspase activation cascades. Caspases may form a signaling cascade to transmit apoptosis signals. The interactions between different caspases in the signaling cascade during apoptosis are not well understood. We will study whether two different caspases interact at the procaspase level and in apoptosis signaling cascade. 3) To dissect the functions of caspase-8 and caspase-9 in conditional knockout models. Caspase-8 and caspae-9 are the initiator caspases in death receptor- and mitochondrion-dependent apoptosis, respectively. However, conventional knockouts of caspase-8 and caspase-9 result in embryonic or perinatal lethality, making it difficult to assess the in vivo functions of these caspases. We will generate conditional knockouts of caspase-8 and caspase-9 in mice in order to study their functions in vivo: These studies will help to elucidate the mechanisms for caspase activation and the functions of pro-apoptotic caspases in regulating T cell functions in vivo, thereby facilitating the design of therapeutic approaches to target these caspases in autoimmune diseases and cancer.