Mechanism of apoptosis induction by the receptor DCC

描述（由申请人提供）：雄激素受体，RET（在移植过程中重排），DCC（在结直肠癌中删除）和UNC5H1-3 （Unc-5同源物1-3）是越来越多的依赖受体的成员。这些受体在其配体不可用的环境中表达时，通过诱导细胞凋亡，使细胞处于依赖其配体生存的状态。令人感兴趣的是，所有这些受体都与癌症进展、中枢神经系统相关疾病和/或神经系统发育有关。例如，DCC编码一种潜在的肿瘤抑制因子，但同时也是介导线索网络-1诱导的轴突引导的关键受体。通过我们对DCC的研究，我们建议定义(i)在没有配体的情况下诱导细胞凋亡的分子机制，以及在配体存在的情况下阻止细胞凋亡的机制，（ii）这些依赖受体的体内功能，特别是在DCC的情况下，DCC诱导的细胞凋亡在神经系统发育过程中轴突引导的作用。我们将定义分子机制，从我们最初的观察开始，DCC作为一个复合体的核心，允许caspase激活。实验将包括使用DCC的促凋亡区域（氨基酸1121-1290）作为诱饵的双杂交研究，纯化和表征与DCC形成的80万道尔顿络合物中包含的蛋白质，并确定DCC多聚的存在和作用。通过监测神经系统发育过程中caspasas对DCC的切割，以及创建表达无法诱导细胞凋亡的DCC突变形式的敲入小鼠，将研究DCC促凋亡作用的体内相关性。

DESCRIPTION (provided by applicant): The androgen receptor, RET (REarranged during Transfection), DCC (Deleted in Colorectal Cancer), and UNC5H1-3 (Unc-5 homologues 1-3) are members of a growing list of dependence receptors. Such receptors, by inducing apoptosis when expressed in a setting in which their ligands are unavailable, create a cellular state of dependence on their ligands for survival. Of interest is that all of these receptors are involved in cancer progression, central nervous system-associated diseases and/or development of the nervous system. As an example, DCC encodes a potential tumor suppressor but at the same time is a key receptor in mediating axon guidance induced by the cue netrin-1. By focusing our study on DCC, we propose to define (i) the molecular mechanisms allowing the induction of apoptosis in the absence of ligand, and those mechanisms that block apoptosis in the presence of ligand, (ii) the in vivo function of these dependence receptors, and specifically in the case of DCC, the role of DCC-induced apoptosis inaxon guidance during nervous system development. We will define the molecular mechanisms startingfrom our initial observation that DCC serves as the core for a complex allowing caspase activation.Experiments will include two-hybrid studies using the pro-apoptotic region of DCC (amino acids 1121-1290) as bait, purification and characterization of the proteins contained in the 800,000 Dalton complexformed with DCC, and determination of the presence and the role of DCC multimerization. The in vivo relevance of the pro-apoptotic effect of DCC will be studied by monitoring DCC cleavage by caspasesduring development of the nervous system and by creating knock-in mice expressing a mutated form ofDCC that is unable to induce apoptosis.