Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 201210, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 201210, China.
Mol Cell. 2020 Aug 6;79(3):443-458.e7. doi: 10.1016/j.molcel.2020.06.019. Epub 2020 Jul 9.
Despite the prominent role of TDP-43 in neurodegeneration, its physiological and pathological functions are not fully understood. Here, we report an unexpected role of TDP-43 in the formation of dynamic, reversible, liquid droplet-like nuclear bodies (NBs) in response to stress. Formation of NBs alleviates TDP-43-mediated cytotoxicity in mammalian cells and fly neurons. Super-resolution microscopy reveals distinct functions of the two RRMs in TDP-43 NB formation. TDP-43 NBs are partially colocalized with nuclear paraspeckles, whose scaffolding lncRNA NEAT1 is dramatically upregulated in stressed neurons. Moreover, increase of NEAT1 promotes TDP-43 liquid-liquid phase separation (LLPS) in vitro. Finally, we discover that the ALS-associated mutation D169G impairs the NEAT1-mediated TDP-43 LLPS and NB assembly, causing excessive cytoplasmic translocation of TDP-43 to form stress granules, which become phosphorylated TDP-43 cytoplasmic foci upon prolonged stress. Together, our findings suggest a stress-mitigating role and mechanism of TDP-43 NBs, whose dysfunction may be involved in ALS pathogenesis.
尽管 TDP-43 在神经退行性变中起着重要作用，但它的生理和病理功能仍未完全了解。在这里，我们报告了 TDP-43 在应激反应下形成动态、可逆、液滴样核体（NB）中的一个意外作用。NB 的形成减轻了哺乳动物细胞和果蝇神经元中 TDP-43 介导的细胞毒性。超分辨率显微镜揭示了 TDP-43 NB 形成中两个 RRMs 的不同功能。TDP-43 NB 与核斑（nuclear paraspeckles）部分共定位，其支架 lncRNA NEAT1 在应激神经元中显著上调。此外，NEAT1 的增加促进了 TDP-43 的液-液相分离（LLPS）。最后，我们发现 ALS 相关突变 D169G 损害了 NEAT1 介导的 TDP-43 LLPS 和 NB 组装，导致 TDP-43 过度细胞质易位形成应激颗粒，这些颗粒在长时间应激后会磷酸化形成 TDP-43 细胞质焦点。总之，我们的发现表明 TDP-43 NB 具有减轻压力的作用和机制，其功能障碍可能与 ALS 的发病机制有关。
