Host Factors Influencing Anthrax Toxin Sensitivity

描述(由申请人提供)：有证据表明，炭疽致命毒素(LeTx)是导致炭疽杆菌感染的大部分疾病症状和死亡的原因。然而，致命性毒素致病的确切分子机制仍然是一个谜。作为LeTx的催化成分，致死因子(L.F)是一种锌依赖的蛋白水解酶，它能裂解MAPKK，从而破坏ERK、p38和JNK信号通路。在不同的细胞类型中，LF能进入并切割MAPKK，然而，只有小鼠巨噬细胞对毒素诱导的体外裂解敏感。此外，来自某些近交系小鼠的巨噬细胞对毒素具有抵抗力，但如果用细菌成分激活，可能是通过Toll样受体(TLR)，就可以致敏。我们感兴趣的是揭开导致毒素敏感性的细胞机制。在这里，我们提出了旨在阐明TLR信号涉及耐药巨噬细胞增敏的实验，因为我们预测这涉及到在毒素活性的上游发挥作用的事件。此外，我们将使用毒素敏感的巨噬细胞系进行体细胞和化学遗传筛选，以确定发挥LF敏感性作用的细胞因子或过程。

DESCRIPTION (provided by applicant): Evidence has shown that anthrax lethal toxin (LeTx) is responsible for most disease symptoms and death due to B. anthracis infection. However, the precise molecular mechanism by which lethal toxin causes disease remains a mystery. Lethal factor (L.F), the catalytic component of LeTx, is a zinc-dependent protease that has been shown to cleave MAPKKs, thus disrupting signaling through the ERK, p38, and JNK pathways. LF is able to enter and cleave MAPKK in the various tested cell types, however, only murine macrophages were shown to be sensitive to toxin induced lysis in vitro. Furthermore, macrophages from certain inbred strains of mice are resistant to toxin, but can be sensitized if activated with bacterial components, presumably via toll like receptors (TLR). We are interested in uncovering cellular mechanisms that contribute to toxin sensitivity. Here, we propose experiments designed to elucidate TLR signaling involved in sensitization of resistant macrophages as we predict this involves events that play a role upstream of toxin activity. Additionally, we will conduct somatic cell and chemical genetic screens using a toxin sensitive macrophage cell line to identify cellular factors or processes that play a role LF sensitivity.