Caspase activation during PAH induced apoptosis

本提案的总体目标是确定PAH介导的细胞凋亡过程中前B细胞中发生的分子事件。阐明这些化合物的作用机制将增加我们对它们如何发挥免疫毒性的理解。该提议的中心假设是多环芳烃（PAH）通过以I型方式经由半胱天冬酶-8诱导淋巴细胞凋亡而导致前B细胞死亡。这一假设得到了我的初步数据的支持，这些数据表明，用DMBA处理preB细胞激活了caspase-8和caspase-3，并在较小程度上激活了caspase-9。进一步证明可溶性FasL能够诱导前B细胞中的caspase-8和凋亡。本研究将进一步扩展这些发现：1）在前B细胞/基质细胞共培养系统中，表征caspase激活和辅助蛋白诱导的特定模式; 2）通过用DMBA处理gld和lpr基因敲除小鼠，确定Fas/FasL通路是否是体内骨髓毒性所必需的; 3）在前两个目标中开发的体内和体外系统中，使用PAH家族的其他成员来确定PAH的免疫毒性与半胱天冬酶激活之间的关系。

The overall goal of this proposal is to determine the molecular events that take place in preB cells during PAH mediated apoptosis. Delineating the mechanism of action of these compounds will increase our understanding of how they exert their immunotoxicity. The central hypothesis of this proposal is that polycyclic aromatic hydrocarbons (PAHs) cause death of preB cells by inducing apoptosis in lymphocytes via caspase-8 in a Type I manner. This hypothesis is supported by my preliminary data, which show that treatment of preB cells with DMBA activates caspase-8 and caspase-3, and to a lesser extent caspase-9. Further evidence is provided that soluble FasL is able to induce caspase-8 and apoptosis in preB cells. In the proposed project I will extend these findings further by: 1) characterizing the specific pattern of caspase activation and accessory protein induction in the preB cell/stromal cell co-culture system; 2) determine if the Fas/FasL pathway is necessary for in vivo bone marrow toxicity, by treating gld and lpr knockout mice with DMBA; 3) define the relationship between immunotoxicity of the PAHs and caspase activating, using other members of the PAH family in the in vivo and in vitro systems developed in the first two aims.