Department of Chemical Biology, Tokyo Medical University, Shinjuku-ku, Tokyo, 160-8402, Japan.
Division of Molecular and Developmental Biology, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka, 411-8540, Japan.
Nat Commun. 2020 Feb 21;11(1):1004. doi: 10.1038/s41467-020-14815-x.
Cytoplasmic aggregation of TDP-43 characterizes degenerating neurons in most cases of amyotrophic lateral sclerosis (ALS). Here, we develop an optogenetic TDP-43 variant (opTDP-43), whose multimerization status can be modulated in vivo through external light illumination. Using the translucent zebrafish neuromuscular system, we demonstrate that short-term light stimulation reversibly induces cytoplasmic opTDP-43 mislocalization, but not aggregation, in the spinal motor neuron, leading to an axon outgrowth defect associated with myofiber denervation. In contrast, opTDP-43 forms pathological aggregates in the cytoplasm after longer-term illumination and seeds non-optogenetic TDP-43 aggregation. Furthermore, we find that an ALS-linked mutation in the intrinsically disordered region (IDR) exacerbates the light-dependent opTDP-43 toxicity on locomotor behavior. Together, our results propose that IDR-mediated TDP-43 oligomerization triggers both acute and long-term pathologies of motor neurons, which may be relevant to the pathogenesis and progression of ALS.
TDP-43 在细胞质中的聚集是大多数肌萎缩侧索硬化症（ALS）中退化神经元的特征。在这里，我们开发了一种光遗传学 TDP-43 变体（opTDP-43），其多聚状态可以通过外部光照射在体内进行调节。使用半透明的斑马鱼神经肌肉系统，我们证明了短期光刺激可在脊髓运动神经元中可逆地诱导细胞质 opTDP-43 定位错误，但不会聚集，导致与肌纤维去神经支配相关的轴突生长缺陷。相比之下，opTDP-43 在较长时间的光照后形成病理性的细胞质聚集体，并引发非光遗传学 TDP-43 的聚集。此外，我们发现，在无规则区域（IDR）中的一个与 ALS 相关的突变会加剧光依赖性 opTDP-43 对运动神经元的毒性作用。总之，我们的结果表明，IDR 介导的 TDP-43 寡聚化引发了运动神经元的急性和长期病变，这可能与 ALS 的发病机制和进展有关。
