Chapman G, Major J A, Iyer K, James A C, Pursglove S E, Moreau J L M, Dunwoodie S L
Developmental and Stem Cell Biology Division, Victor Chang Cardiac Research Institute, Sydney, Australia; St. Vincent's Clinical School, University of New South Wales, Sydney, Australia.
Developmental and Stem Cell Biology Division, Victor Chang Cardiac Research Institute, Sydney, Australia.
Biochim Biophys Acta. 2016 Jan;1863(1):166-77. doi: 10.1016/j.bbamcr.2015.10.021. Epub 2015 Oct 30.
The Notch signalling pathway is widely utilised during embryogenesis in situations where cell-cell interactions are important for cell fate specification and differentiation. DSL ligand endocytosis into the ligand-expressing cell is an important aspect of Notch signalling because it is thought to supply the force needed to separate the Notch heterodimer to initiate signal transduction. A functional role for receptor endocytosis during Notch signal transduction is more controversial. Here we have used live-cell imaging to examine trafficking of the Notch1 receptor in response to ligand binding. Contact with cells expressing ligands induced internalisation and intracellular trafficking of Notch1. Notch1 endocytosis was accompanied by transendocytosis of ligand into the Notch1-expressing signal-receiving cell. Ligand caused Notch1 endocytosis into SARA-positive endosomes in a manner dependent on clathrin and dynamin function. Moreover, inhibition of endocytosis in the receptor-expressing cell impaired ligand-induced Notch1 signalling. Our findings resolve conflicting observations from mammalian and Drosophila studies by demonstrating that ligand-dependent activation of Notch1 signalling requires receptor endocytosis. Endocytosis of Notch1 may provide a force on the ligand:receptor complex that is important for potent signal transduction.
Notch信号通路在胚胎发育过程中被广泛利用，此时细胞间相互作用对于细胞命运决定和分化至关重要。DSL配体内吞进入表达配体的细胞是Notch信号传导的一个重要方面，因为它被认为提供了分离Notch异二聚体以启动信号转导所需的力量。受体胞吞作用在Notch信号转导过程中的功能作用更具争议性。在这里，我们使用活细胞成像技术来研究Notch1受体在配体结合后的运输情况。与表达配体的细胞接触会诱导Notch1的内化和细胞内运输。Notch1的内吞作用伴随着配体转胞吞进入表达Notch1的信号接收细胞。配体以依赖网格蛋白和发动蛋白功能的方式导致Notch1内吞进入SARA阳性的内体。此外，抑制表达受体的细胞中的内吞作用会损害配体诱导的Notch1信号传导。我们的研究结果通过证明Notch1信号传导的配体依赖性激活需要受体内吞作用，解决了来自哺乳动物和果蝇研究的相互矛盾的观察结果。Notch1 的内吞作用可能会对配体：受体复合物施加一种力量，这对有效的信号转导很重要。
