Activation and in vivo Functions of Initiator Caspases

描述（由申请人提供）：半胱天冬酶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。在凋亡信号级联的顶部的半胱天冬酶被称为起始半胱天冬酶。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解决。此外，由于它们在小鼠中的敲除导致胚胎致死，因此难以评估这些起始半胱天冬酶的体内功能。本研究拟通过以下实验来研究caspase启动子的激活机制和体内功能：1）检测caspase二聚体依赖性激活机制。晶体结构研究表明，半胱天冬酶形成同源二聚体之前，他们的自动激活。我们将使用一个可诱导的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以引起半胱天冬酶激活。2)检测半胱天冬酶的激活级联反应。半胱天冬酶可形成信号级联以传递凋亡信号。细胞凋亡过程中信号级联中不同半胱天冬酶之间的相互作用还不清楚。我们将研究两种不同的半胱天冬酶是否在半胱天冬酶原水平和凋亡信号级联中相互作用。3)探讨caspase-8和caspase-9在条件性基因敲除模型中的功能。Caspase-8和caspase-9分别是死亡受体依赖性凋亡和凋亡相关蛋白依赖性凋亡的启动子。然而，常规的半胱天冬酶-8和半胱天冬酶-9的敲除导致胚胎或围产期死亡，使得难以评估这些半胱天冬酶的体内功能。我们将在小鼠中产生caspase-8和caspase-9的条件性敲除，以研究它们在体内的功能：这些研究将有助于阐明caspase激活的机制和促凋亡caspase在体内调节T细胞功能的功能，从而促进治疗方法的设计，以靶向这些caspase在自身免疫性疾病和癌症。

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.