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）是由炭疽杆菌感染引起的大多数疾病症状和死亡的原因。然而，致命毒素致病的确切分子机制仍然是个谜。致死因子（Lethal factor， L.F）是LeTx的催化成分，是一种锌依赖性蛋白酶，已被证明可以切割MAPKKs，从而破坏ERK、p38和JNK途径的信号传导。LF能够在各种被试细胞类型中进入和切割MAPKK，然而，只有小鼠巨噬细胞在体外被证明对毒素诱导的裂解敏感。此外，来自某些近交系小鼠的巨噬细胞对毒素具有抗性，但如果被细菌成分激活，可能会通过toll样受体（TLR）致敏。我们对揭示导致毒素敏感性的细胞机制很感兴趣。在这里，我们提出了旨在阐明TLR信号参与耐药巨噬细胞致敏的实验，因为我们预测这涉及到毒素活性上游的事件。此外，我们将使用毒素敏感的巨噬细胞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素或过程。

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.