Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.
Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA.
Mol Cell. 2018 Sep 6;71(5):703-717.e9. doi: 10.1016/j.molcel.2018.07.002. Epub 2018 Aug 9.
In amyotrophic lateral sclerosis (ALS) and frontotemporal degeneration (FTD), cytoplasmic aggregates of hyperphosphorylated TDP-43 accumulate and colocalize with some stress granule components, but how pathological TDP-43 aggregation is nucleated remains unknown. In Drosophila, we establish that downregulation of tankyrase, a poly(ADP-ribose) (PAR) polymerase, reduces TDP-43 accumulation in the cytoplasm and potently mitigates neurodegeneration. We establish that TDP-43 non-covalently binds to PAR via PAR-binding motifs embedded within its nuclear localization sequence. PAR binding promotes liquid-liquid phase separation of TDP-43 in vitro and is required for TDP-43 accumulation in stress granules in mammalian cells and neurons. Stress granule localization initially protects TDP-43 from disease-associated phosphorylation, but upon long-term stress, stress granules resolve, leaving behind aggregates of phosphorylated TDP-43. Finally, small-molecule inhibition of Tankyrase-1/2 in mammalian cells inhibits formation of cytoplasmic TDP-43 foci without affecting stress granule assembly. Thus, Tankyrase inhibition antagonizes TDP-43-associated pathology and neurodegeneration and could have therapeutic utility for ALS and FTD.
在肌萎缩性侧索硬化症（ALS）和额颞叶变性（FTD）中，过度磷酸化的 TDP-43 的细胞质聚集体积累并与一些应激颗粒成分共定位，但病理 TDP-43 聚集如何被引发仍不清楚。在果蝇中，我们证实下调多聚（ADP-核糖）聚合酶 tankyrase 可减少 TDP-43 在细胞质中的积累，并强烈减轻神经退行性变。我们证实 TDP-43 通过其核定位序列内嵌入的 PAR 结合基序非共价结合 PAR。PAR 结合促进 TDP-43 在体外的液-液相分离，并且是哺乳动物细胞和神经元中应激颗粒中 TDP-43 积累所必需的。应激颗粒定位最初保护 TDP-43 免受与疾病相关的磷酸化，但长期应激后，应激颗粒会解体，留下磷酸化 TDP-43 的聚集体。最后，在哺乳动物细胞中抑制 Tankyrase-1/2 的小分子抑制细胞质 TDP-43 焦点的形成，而不影响应激颗粒的组装。因此，Tankyrase 抑制拮抗 TDP-43 相关的病理学和神经退行性变，并且可能对 ALS 和 FTD 具有治疗效用。
