Piddini Eugenia, Vincent Jean-Paul
National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK.
Curr Opin Cell Biol. 2003 Aug;15(4):474-81. doi: 10.1016/s0955-0674(03)00072-3.
Recent advances have highlighted the importance of endocytic processes in regulating the activity and distribution of developmental signals. Classically, signalling is downregulated by endocytosis and subsequent trafficking to lysosomes (e.g. Notch, Hedgehog, Roundabout). However, endocytosis can also have a positive role in signalling. For example, endocytosis of Delta, the ligand of Notch, is needed for activation of the signal. In the case of signalling by Hedgehog, endocytic trafficking segregates an inhibitory receptor (Patched) from the positive effector (Smoothened). Endosomes could also be the site where signalling is activated (e.g. transforming growth factor beta). Finally, endocytosis could power the transport of morphogens along epithelia.
最近的进展凸显了内吞作用在调节发育信号的活性和分布方面的重要性。传统上，信号通过内吞作用以及随后向溶酶体的运输而被下调（例如Notch、Hedgehog、Roundabout）。然而，内吞作用在信号传导中也可以发挥积极作用。例如，Notch的配体Delta的内吞作用是激活该信号所必需的。在Hedgehog信号传导的情况下，内吞运输将抑制性受体（Patched）与正向效应器（Smoothened）分离。内体也可能是信号被激活的部位（例如转化生长因子β）。最后，内吞作用可以推动形态发生素沿上皮细胞的运输。
