Brain-derived neurotrophic factor, via activation of tropomyosin receptor kinase B (TrkB), plays a critical role in neuronal proliferation, differentiation, survival, and death. Dysregulation of TrkB signaling is implicated in neurodegenerative disorders and cancers. Precise activation of TrkB signaling with spatial and temporal resolution is greatly desired to study the dynamic nature of TrkB signaling and its role in related diseases. Here we develop different optogenetic approaches that use light to activate TrkB signaling. Utilizing the photosensitive protein Arabidopsis thaliana cryptochrome 2, the light-inducible homo-interaction of the intracellular domain of TrkB in the cytosol or on the plasma membrane is able to induce the activation of downstream MAPK/ERK and PI3K/Akt signaling as well as the neurite outgrowth of PC12 cells. Moreover, we prove that such strategies are generalizable to other optical homo-dimerizers by demonstrating the optical TrkB activation based on the light-oxygen-voltage domain of aureochrome 1 from Vaucheria frigida. The results open up new possibilities of many other optical platforms to activate TrkB signaling to fulfill customized needs. By comparing all the different strategies, we find that the cryptochrome 2-integrated approach to achieve light-induced cell membrane recruitment and homo-interaction of intracellular domain of TrkB is most efficient in activating TrkB signaling. The optogenetic strategies presented are promising tools to investigate brain-derived neurotrophic factor/TrkB signaling with tight spatial and temporal control.

脑源性神经营养因子，通过激活原肌球蛋白受体激酶B（TrkB），在神经元增殖，分化，存活和死亡中起关键作用。TrkB信号传导异常涉及神经退行性疾病和癌症。为了研究TrkB信号的动态性质及其在相关疾病中的作用，非常需要具有时空分辨率的TrkB信号精确激活。在这里，我们开发了使用光激活TrkB信号传导的不同光遗传学方法。利用光敏蛋白拟南芥隐色染料2，在细胞质或质膜上的TrkB胞内结构域的光诱导均质相互作用，能够诱导下游MAPK / ERK和PI3K / Akt信号传导以及PC12细胞的神经突生长。此外，我们证明了这种策略可以通过证明基于来自Vaucheria frigida的aureochrome 1的光-氧-电压域的光学TrkB活化而推广到其他光学均二聚体。。结果为激活其他TrkB信号传输以满足定制需求打开了许多其他光学平台的新可能性。通过比较所有不同的策略，我们发现，实现光诱导的细胞膜募集和TrkB胞内域的均质相互作用的隐色2整合方法在激活TrkB信号传导方面最有效。提出的光遗传学策略是研究脑源性神经营养因子/ TrkB信号，具有严格的时空控制的有前途的工具。