Fang Zongxi Center, MoE Key Laboratory of Marine Genetics and Breeding, College of Marine Life Sciences, Ocean University of China, Qingdao, 266003, China.
Laoshan Laboratory, Qingdao, 266237, China.
Biol Res. 2023 Mar 11;56(1):10. doi: 10.1186/s40659-023-00422-9.
The biological tube is a basal biology structure distributed in all multicellular animals, from worms to humans, and has diverse biological functions. Formation of tubular system is crucial for embryogenesis and adult metabolism. Ascidian Ciona notochord lumen is an excellent in vivo model for tubulogenesis. Exocytosis has been known to be essential for tubular lumen formation and expansion. The roles of endocytosis in tubular lumen expansion remain largely unclear.
In this study, we first identified a dual specificity tyrosine-phosphorylation-regulated kinase 1 (DYRK1), the protein kinase, which was upregulated and required for ascidian notochord extracellular lumen expansion. We demonstrated that DYRK1 interacted with and phosphorylated one of the endocytic components endophilin at Ser263 that was essential for notochord lumen expansion. Moreover, through phosphoproteomic sequencing, we revealed that in addition to endophilin, the phosphorylation of other endocytic components was also regulated by DYRK1. The loss of function of DYRK1 disturbed endocytosis. Then, we demonstrated that clathrin-mediated endocytosis existed and was required for notochord lumen expansion. In the meantime, the results showed that the secretion of notochord cells is vigorous in the apical membrane.
We found the co-existence of endocytosis and exocytosis activities in apical membrane during lumen formation and expansion in Ciona notochord. A novel signaling pathway is revealed that DYRK1 regulates the endocytosis by phosphorylation that is required for lumen expansion. Our finding thus indicates a dynamic balance between endocytosis and exocytosis is crucial to maintain apical membrane homeostasis that is essential for lumen growth and expansion in tubular organogenesis.
生物管是一种分布在所有多细胞动物中的基础生物学结构，从蠕虫到人都有，具有多种生物学功能。管状系统的形成对于胚胎发生和成年代谢至关重要。海鞘脊索的管腔是管状发生的极好的体内模型。胞吐作用对于管状腔的形成和扩张是必不可少的。胞吞作用在管状腔扩张中的作用在很大程度上仍不清楚。
在这项研究中，我们首先鉴定了一种双特异性酪氨酸磷酸化调节激酶 1（DYRK1），它是一种蛋白激酶，在海鞘脊索细胞外腔的扩张中被上调并需要其发挥作用。我们证明 DYRK1 与内吞作用的一个组成部分之一内吞蛋白相互作用，并在 Ser263 处磷酸化它，这对于脊索管腔的扩张是必不可少的。此外，通过磷酸蛋白质组学测序，我们揭示了除了内吞蛋白外，其他内吞作用成分的磷酸化也受到 DYRK1 的调节。DYRK1 的功能丧失扰乱了内吞作用。然后，我们证明了网格蛋白介导的内吞作用的存在，并证明了它对于脊索管腔的扩张是必需的。与此同时，结果表明脊索细胞的分泌在顶膜上是活跃的。
我们发现，在海鞘脊索管腔形成和扩张过程中，顶膜中同时存在胞吞作用和胞吐作用。揭示了一种新的信号通路，即 DYRK1 通过磷酸化调节内吞作用，这对于管腔扩张是必需的。我们的发现表明，内吞作用和胞吐作用之间的动态平衡对于维持顶膜的动态平衡是至关重要的，这对于管状器官发生中的管腔生长和扩张是必不可少的。
