Department of Biology, University of Nevada Reno, Reno, United States.
Elife. 2024 Oct 30;13:RP96592. doi: 10.7554/eLife.96592.
Dual leucine zipper kinase (DLK) mediates multiple neuronal stress responses, and its expression levels are constantly suppressed to prevent excessive stress signaling. We found that Wallenda (Wnd), the ortholog of DLK, is highly enriched in the axon terminals of sensory neurons in vivo and that this subcellular localization is necessary for Highwire-mediated Wnd protein turnover under normal conditions. Our structure-function analysis found that Wnd palmitoylation is essential for its axon terminal localization. Palmitoylation-defective Wnd accumulated in neuronal cell bodies, exhibited dramatically increased protein expression levels, and triggered excessive neuronal stress responses. Defective intracellular transport is implicated in neurodegenerative conditions. Comprehensive dominant-negative Rab protein screening identified Rab11 as an essential factor for Wnd localization in axon terminals. Consequently, loss-of-function increased the protein levels of Wnd and induced neuronal stress responses. Inhibiting Wnd activity significantly ameliorated neuronal loss and c-Jun N-terminal kinase signaling triggered by loss-of-function. Taken together, these suggest that DLK proteins are constantly transported to axon terminals for protein turnover and a failure of such transport can lead to neuronal loss. Our study demonstrates how subcellular protein localization is coupled to protein turnover for neuronal stress signaling.
双重亮氨酸拉链激酶（DLK）介导多种神经元应激反应，其表达水平持续受到抑制，以防止过度的应激信号。我们发现，Wnd（DLK 的直系同源物）在体内感觉神经元的轴突末梢中高度富集，这种亚细胞定位对于 Highwire 介导的 Wnd 蛋白周转是必要的。我们的结构-功能分析发现，Wnd 的棕榈酰化对于其轴突末梢定位是必不可少的。棕榈酰化缺陷的 Wnd 在神经元胞体中积累，表现出显著增加的蛋白表达水平，并引发过度的神经元应激反应。有缺陷的细胞内运输与神经退行性疾病有关。全面的显性负 Rab 蛋白筛选鉴定出 Rab11 是 Wnd 在轴突末梢定位的必需因素。因此，功能丧失增加了 Wnd 的蛋白水平，并诱导了神经元应激反应。抑制 Wnd 的活性显著改善了由功能丧失引起的神经元丢失和 c-Jun N 末端激酶信号。综上所述，这些表明 DLK 蛋白不断被转运到轴突末梢进行蛋白周转，而这种运输的失败可能导致神经元丢失。我们的研究表明，亚细胞蛋白定位如何与神经元应激信号的蛋白周转相耦合。
