Cellular and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, MI 48104, USA; Department of Neurology, University of Michigan, Ann Arbor, MI 48104, USA.
Department of Neurology, University of Michigan, Ann Arbor, MI 48104, USA.
Cell Rep. 2019 Apr 23;27(4):1133-1150.e8. doi: 10.1016/j.celrep.2019.03.093.
The majority of individuals with amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) exhibit neuronal cytoplasmic inclusions rich in the RNA binding protein TDP43. Even so, the relation between the RNA binding properties of TDP43 and neurodegeneration remains obscure. Here, we show that engineered mutations disrupting a salt bridge between the RNA recognition motifs of TDP43 interfere with RNA binding and eliminate the recognition of native TDP43 substrates. The same mutations dramatically destabilize TDP43, alter its subcellular localization, and abrogate TDP43-dependent neurodegeneration. Worms harboring homologous TDP-1 mutations phenocopy knockout strains, confirming the necessity of salt bridge residues for TDP43 function. Moreover, the accumulation of functional TDP43, but not RNA binding-deficient variants, disproportionately affects transcripts encoding ribosome and oxidative phosphorylation components. These studies demonstrate the significance of the salt bridge in sustaining TDP43 stability and RNA binding properties, factors that are crucial for neurodegeneration arising from TDP43 deposition in ALS and FTD.
大多数肌萎缩性侧索硬化症（ALS）和额颞叶痴呆（FTD）患者的神经元细胞质中富含 RNA 结合蛋白 TDP43 的包涵体。即便如此，TDP43 的 RNA 结合特性与神经退行性变之间的关系仍不清楚。在这里，我们表明，破坏 TDP43 的 RNA 识别基序之间的盐桥的工程突变会干扰 RNA 结合并消除对天然 TDP43 底物的识别。相同的突变会极大地破坏 TDP43，改变其亚细胞定位，并消除 TDP43 依赖性神经退行性变。携带同源 TDP-1 突变的蠕虫模拟敲除菌株，证实了盐桥残基对于 TDP43 功能的必要性。此外，功能正常的 TDP43 的积累，而不是 RNA 结合缺陷变体，不成比例地影响编码核糖体和氧化磷酸化成分的转录物。这些研究表明盐桥在维持 TDP43 的稳定性和 RNA 结合特性方面的重要性，这些因素对于由 ALS 和 FTD 中 TDP43 沉积引起的神经退行性变至关重要。
