Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, San Diego, CA, United States.
Front Immunol. 2020 Jan 10;10:3040. doi: 10.3389/fimmu.2019.03040. eCollection 2019.
Toll mediates a robust and effective innate immune response across vertebrates and invertebrates. In , activation of Toll by systemic infection drives the accumulation of a rich repertoire of immune effectors in hemolymph, including the recently characterized Bomanins, as well as the classical antimicrobial peptides (AMPs). Here we report the functional characterization of a Toll-induced hemolymph protein encoded by the () gene. Using the CRISPR/Cas9 system to generate a precise deletion of the transcriptional unit, we found that Bombardier is required for Toll-mediated defense against fungi and Gram-positive bacteria. Assaying cell-free hemolymph, we found that the Bomanin-dependent candidacidal activity is also dependent on Bombardier, but is independent of the antifungal AMPs Drosomycin and Metchnikowin. Using mass spectrometry, we demonstrated that deletion of results in the specific absence of short-form Bomanins from hemolymph. In addition, flies lacking Bombardier exhibited a defect in pathogen tolerance that we trace to an aberrant condition triggered by Toll activation. These results lead us to a model in which the presence of Bombardier in wild-type flies enables the proper folding, secretion, or intermolecular associations of short-form Bomanins, and the absence of Bombardier disrupts one or more of these steps, resulting in defects in both immune resistance and tolerance.
Toll 介导了脊椎动物和无脊椎动物中强大而有效的先天免疫反应。在 中，系统感染激活 Toll 会驱动丰富的免疫效应物在血淋巴中积累，包括最近被描述的 Bomanins 以及经典的抗菌肽 (AMPs)。在这里，我们报告了由 () 基因编码的 Toll 诱导的血淋巴蛋白的功能特征。我们使用 CRISPR/Cas9 系统精确地删除了 的转录单元，发现 Bombardier 是 Toll 介导的抗真菌和革兰氏阳性细菌防御所必需的。在无细胞血淋巴中进行检测，我们发现 Bomanin 依赖的杀酵母活性也依赖于 Bombardier，但独立于抗真菌 AMPs Drosomycin 和 Metchnikowin。使用质谱法，我们证明了 的缺失会导致血淋巴中短型 Bomanins 的特异性缺失。此外，缺乏 Bombardier 的果蝇表现出对病原体的耐受性缺陷，我们可以追溯到 Toll 激活引发的异常情况。这些结果使我们得出一个模型，即在野生型果蝇中存在 Bombardier 可以使短型 Bomanins 正确折叠、分泌或分子间缔合，而 Bombardier 的缺失会破坏这些步骤中的一个或多个步骤，导致免疫抵抗和耐受性缺陷。
