TAR DNA-binding protein 43 (TDP-43) is a DNA/RNA binding protein predominantly localized in the nucleus under physiological conditions. TDP-43 proteinopathy, characterized by cytoplasmic aggregation and nuclear loss, is associated with many neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Thus it is crucial to understand the molecular mechanism regulating TDP-43 homeostasis. Here, we show that the uptake of oligodeoxynucleotides (ODNs) induces reversible TDP-43 cytoplasmic puncta formation in both neurons and glia and ODNs facilitate the liquid-liquid phase separation of TDP-43 in vitro. Importantly, persistent accumulation of DNA in the cytoplasm leads to nuclear depletion of TDP-43 and enhanced production of a short isoform of TDP-43 (sTDP-43). In addition, in response to ODN uptake, the nuclear import receptor karyopherin subunit β1 (KPNB1) is sequestered in the cytosolic TDP-43 puncta. ALS-linked Q331K mutation decreases the dynamics of cytoplasmic TDP-43 puncta and increases the levels of sTDP-43. Moreover, the TDP-43 cytoplasmic puncta are induced by DNA damage and by impaired nuclear envelope integrity due to Lamin A/C deficiency. In summary, our data support that abnormal DNA accumulation in the cytoplasm may be one of the key mechanisms leading to TDP-43 proteinopathy and provides novel insights into molecular mechanisms of ALS caused by TDP-43 mutations.

中文翻译：

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胞质 DNA 积累对 TAR DNA 结合蛋白 43 （TDP-43） 稳态的调节。


TAR DNA 结合蛋白 43 （TDP-43） 是一种 DNA/RNA 结合蛋白，在生理条件下主要位于细胞核中。TDP-43 蛋白病以细胞质聚集和核丢失为特征，与许多神经退行性疾病有关，包括肌萎缩侧索硬化症 （ALS） 和额颞叶变性 （FTLD）。因此，了解调节 TDP-43 稳态的分子机制至关重要。在这里，我们表明寡脱氧核苷酸 （ODN） 的摄取诱导神经元和神经胶质细胞中可逆的 TDP-43 细胞质点形成，ODN 促进了 TDP-43 在体外的液 - 液相分离。重要的是，DNA 在细胞质中的持续积累导致 TDP-43 的核耗竭并增强 TDP-43 短亚型 （sTDP-43） 的产生。此外，为了响应 ODN 摄取，核输入受体 karyopherin 亚基 β1 （KPNB1） 被隔离在胞质 TDP-43 点中。ALS 相关的 Q331K 突变降低了细胞质 TDP-43 点的动力学并增加了 sTDP-43 的水平。此外，TDP-43 细胞质点是由 DNA 损伤和核纤层蛋白 A/C 缺陷引起的核膜完整性受损诱导的。总之，我们的数据支持细胞质中异常 DNA 积累可能是导致 TDP-43 蛋白病的关键机制之一，并为 TDP-43 突变引起的 ALS 的分子机制提供了新的见解。