Department of Biochemistry and Molecular Biology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
the Key Laboratory of Xinjiang Endemic & Ethnic Diseases and Department of Biochemistry, Shihezi University School of Medicine, Shihezi 832002, China.
Acta Biochim Biophys Sin (Shanghai). 2023 Oct 25;55(10):1650-1658. doi: 10.3724/abbs.2023098.
Neuritin plays a key role in neural development and regeneration by promoting neurite outgrowth and synapse maturation. Our previous research revealed the mechanism by which neuritin inhibits Notch signaling through interaction with neuralized-like 1 (Neurl1) to promote neurite growth. However, how neuritin regulates Notch signaling through Neurl1 has not been elucidated. Here, we first confirm that neuritin is an upstream regulator of Neurl1 and inhibits Notch signaling through Neurl1. Neurl1 is an E3 ubiquitin ligase that can promote ubiquitination and endocytosis of the Notch1 ligand Jagged1. Therefore, we observe the effect of neuritin on the ligase activity of Neurl1. The results indicate that neuritin inhibits Neurl1 activity by reducing the ubiquitination level and endocytosis of the target protein Jagged1. Moreover, we find that decreased activity of Neurl1 results in reduced expression of Notch receptor Notch intracellular domain (NICD) and downstream target gene hairy and enhancer of split-1 ( ). Furthermore, we investigate how neuritin affects Neurl1 enzyme activity. The results show that neuritin not only weakens the affinity between Neurl1 and Jagged1 but also promotes the degradation of Neurl1 by the 26S proteasome pathway. Taken together, our results suggest that neuritin negatively regulates Notch signaling by inhibiting the activity of Neurl1, promoting the degradation of Neurl1 and weakening the affinity of Neurl1 for Jagged1. Our study clarifies the molecular mechanisms of neuritin in regulating the Notch signaling pathway and provides new clues about how neuritin mediates neural regeneration and plasticity.
神经调节蛋白通过促进神经突生长和突触成熟，在神经发育和再生中发挥关键作用。我们之前的研究揭示了神经调节蛋白通过与神经调节蛋白样 1（Neurl1）相互作用抑制 Notch 信号通路从而促进神经突生长的机制。然而，神经调节蛋白如何通过 Neurl1 调节 Notch 信号通路尚未阐明。在这里，我们首先证实神经调节蛋白是 Neurl1 的上游调节剂，并通过 Neurl1 抑制 Notch 信号通路。Neurl1 是一种 E3 泛素连接酶，可促进 Notch1 配体 Jagged1 的泛素化和内吞作用。因此，我们观察了神经调节蛋白对 Neurl1 酶活性的影响。结果表明，神经调节蛋白通过降低靶蛋白 Jagged1 的泛素化水平和内吞作用来抑制 Neurl1 活性。此外，我们发现 Neurl1 活性的降低导致 Notch 受体 Notch 细胞内结构域（NICD）和下游靶基因 hairy 和 splice-1（ ）的表达减少。此外，我们研究了神经调节蛋白如何影响 Neurl1 酶活性。结果表明，神经调节蛋白不仅削弱了 Neurl1 和 Jagged1 之间的亲和力，还通过 26S 蛋白酶体途径促进 Neurl1 的降解。总之，我们的结果表明，神经调节蛋白通过抑制 Neurl1 的活性负调控 Notch 信号通路，促进 Neurl1 的降解并削弱 Neurl1 与 Jagged1 的亲和力。我们的研究阐明了神经调节蛋白在调节 Notch 信号通路中的分子机制，并为神经调节蛋白介导神经再生和可塑性的机制提供了新的线索。
