Institute for Molecular Bioscience (IMB) and IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, Australia.
Advanced Imaging Center, Howard Hughes Medical Institute Janelia Research Campus, Ashburn, VA.
J Cell Biol. 2018 Nov 5;217(11):3873-3885. doi: 10.1083/jcb.201804137. Epub 2018 Aug 27.
Pathogen-mediated activation of macrophages arms innate immune responses that include enhanced surface ruffling and macropinocytosis for environmental sampling and receptor internalization and signaling. Activation of macrophages with bacterial lipopolysaccharide (LPS) generates prominent dorsal ruffles, which are precursors for macropinosomes. Very rapid, high-resolution imaging of live macrophages with lattice light sheet microscopy (LLSM) reveals new features and actions of dorsal ruffles, which redefine the process of macropinosome formation and closure. We offer a new model in which ruffles are erected and supported by F-actin tent poles that cross over and twist to constrict the forming macropinosomes. This process allows for formation of large macropinosomes induced by LPS. We further describe the enrichment of active Rab13 on tent pole ruffles and show that CRISPR deletion of Rab13 results in aberrant tent pole ruffles and blocks the formation of large LPS-induced macropinosomes. Based on the exquisite temporal and spatial resolution of LLSM, we can redefine the ruffling and macropinosome processes that underpin innate immune responses.
病原体介导的巨噬细胞激活引发先天免疫反应，包括增强表面皱襞和巨胞饮作用，以进行环境采样和受体内化及信号转导。用细菌脂多糖 (LPS) 激活巨噬细胞会产生明显的背侧皱襞，这是巨胞饮体的前体。利用晶格光片显微镜 (LLSM) 对活巨噬细胞进行非常快速、高分辨率的成像，揭示了背侧皱襞的新特征和作用，重新定义了巨胞饮体形成和闭合的过程。我们提出了一个新模型，其中皱襞由跨越并扭曲以收缩形成的巨胞饮体的 F-肌动蛋白帐篷杆竖立和支撑。这个过程允许 LPS 诱导形成大的巨胞饮体。我们进一步描述了活性 Rab13 在帐篷杆皱襞上的富集，并表明 CRISPR 敲除 Rab13 会导致异常的帐篷杆皱襞，并阻止大的 LPS 诱导的巨胞饮体的形成。基于 LLSM 的精湛时间和空间分辨率，我们可以重新定义先天免疫反应所依赖的皱襞和巨胞饮体过程。
