The presence of foreign nucleic acids in the cytosol is a marker of infection. Cells have sensors, also known as pattern recognition receptors (PRRs), in the cytosol that detect foreign nucleic acid and initiate an innate immune response. Recent studies have reported the condensation of multiple PRRs including PKR, NLRP6, and cGAS, with their nucleic acid activators into discrete nucleoprotein assemblies. Nucleic acid–protein condensates form due to multivalent interactions and can create high local concentrations of components. The formation of PRR-containing condensates may alter the magnitude or timing of PRR activation. In addition, unique condensates form following RNase L activation or during paracrine signaling from virally infected cells that may play roles in antiviral defense. These observations suggest that condensate formation may be a conserved mechanism that cells use to regulate activation of the innate immune response and open an avenue for further investigation into the composition and function of these condensates. Here we review the nucleic acid–protein granules that are implicated in the innate immune response, discuss general consequences of condensate formation and signal transduction, as well as what outstanding questions remain.

中文翻译：

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先天免疫信号中的核酸-蛋白质缩合物


细胞质中存在外来核酸是感染的标志。细胞在胞质溶胶中具有传感器，也称为模式识别受体 (PRR)，可检测外来核酸并启动先天免疫反应。最近的研究报道了多种 PRR（包括 PKR、NLRP6 和 cGAS）及其核酸激活剂浓缩成离散的核蛋白组装体。核酸-蛋白质缩合物由于多价相互作用而形成，并且可以产生高局部浓度的组分。含有 PRR 的冷凝物的形成可能会改变 PRR 激活的幅度或时间。此外，RNase L 激活后或病毒感染细胞发出旁分泌信号期间会形成独特的冷凝物，可能在抗病毒防御中发挥作用。这些观察结果表明，冷凝物的形成可能是细胞用来调节先天免疫反应激活的保守机制，并为进一步研究这些冷凝物的组成和功能开辟了途径。在这里，我们回顾了与先天免疫反应有关的核酸-蛋白质颗粒，讨论了冷凝物形成和信号转导的一般后果，以及仍然存在的悬而未决的问题。