Department of Chemistry and Molecular Biology, University of Gothenburg, SE-412 96 Gothenburg, Sweden.
Human Genetics, McGill University, Montreal, QC H4H1R3, Canada.
Int J Mol Sci. 2023 Jan 29;24(3):2546. doi: 10.3390/ijms24032546.
Stress granules (SGs) are stress-induced biomolecular condensates which originate primarily from inactivated RNA translation machinery and translation initiation factors. SG formation is an important defensive mechanism for cell survival, while its dysfunction has been linked to neurodegenerative diseases. However, the molecular mechanisms of SG assembly and disassembly, as well as their impacts on cellular recovery, are not fully understood. More thorough investigations into the molecular dynamics of SG pathways are required to understand the pathophysiological roles of SGs in cellular systems. Here, we characterize the SG and cytoplasmic protein turnover in neuronal progenitor cells (NPCs) under stressed and non-stressed conditions using correlative STED and NanoSIMS imaging. We incubate NPCs with isotopically labelled (N) leucine and stress them with the ER stressor thapsigargin (TG). A correlation of STED and NanoSIMS allows the localization of individual SGs (using STED), and their protein turnover can then be extracted based on the N/N ratio (using NanoSIMS). We found that TG-induced SGs, which are highly dynamic domains, recruit their constituents predominantly from the cytoplasm. Moreover, ER stress impairs the total cellular protein turnover regimen, and this impairment is not restored after the commonly proceeded stress recovery period.
应激颗粒（SGs）是应激诱导的生物分子凝聚物，主要源自失活的 RNA 翻译机制和翻译起始因子。SG 的形成是细胞存活的重要防御机制，而其功能障碍与神经退行性疾病有关。然而，SG 组装和拆卸的分子机制，以及它们对细胞恢复的影响，尚未完全了解。更深入地研究 SG 途径的分子动力学，有助于了解 SG 在细胞系统中的病理生理作用。在这里，我们使用共定位 STED 和 NanoSIMS 成像，在应激和非应激条件下，对神经元祖细胞（NPC）中的 SG 和细胞质蛋白周转进行了表征。我们用同位素标记的（N）亮氨酸孵育 NPC，并用内质网应激剂他普西龙（TG）对其进行应激。STED 和 NanoSIMS 的相关性允许对单个 SG 进行定位（使用 STED），然后可以根据 N/N 比（使用 NanoSIMS）提取它们的蛋白周转。我们发现，TG 诱导的 SG 是高度动态的结构域，其组成部分主要从细胞质中募集而来。此外，内质网应激会损害细胞内总蛋白周转方案，而这种损害在通常进行的应激恢复后无法恢复。
