Banisch Torsten U, Maimon Iris, Dadosh Tali, Gilboa Lilach
Department of Biological Regulation, Weizmann Institute of Science, Rehovot 7610001, Israel.
Electron Microscopy Unit, Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 7610001, Israel.
Development. 2017 Jun 1;144(11):1937-1947. doi: 10.1242/dev.143727.
Two different compartments support germline stem cell (GSC) self-renewal and their timely differentiation: the classical niche provides maintenance cues, while a differentiation compartment, formed by somatic escort cells (ECs), is required for proper GSC differentiation. ECs extend long protrusions that invade between tightly packed germ cells, and alternate between encapsulating and releasing them. How ECs achieve this dynamic balance has not been resolved. By combining live imaging and genetic analyses in , we have characterised EC shapes and their dynamic changes. We show that germ cell encapsulation by ECs is a communal phenomenon, whereby EC-EC contacts stabilise an extensive meshwork of protrusions. We further show that Signal Transducer and Activator of Transcription (Stat) and Epidermal Growth Factor Receptor (Egfr) signalling sustain EC protrusiveness and flexibility by combinatorially affecting the activity of different RhoGTPases. Our results reveal how a complex signalling network can determine the shape of a cell and its dynamic behaviour. It also explains how the differentiation compartment can establish extensive contacts with germ cells, while allowing a continual posterior movement of differentiating GSC daughters.
两种不同的区域支持生殖系干细胞（GSC）的自我更新及其适时分化：经典的微环境提供维持信号，而由体细胞护送细胞（EC）形成的分化区域对于GSC的正常分化是必需的。EC伸出长长的突起，侵入紧密排列的生殖细胞之间，并在包裹和释放它们之间交替。EC如何实现这种动态平衡尚未得到解决。通过在[具体实验环境]中结合实时成像和基因分析，我们对EC的形状及其动态变化进行了表征。我们表明，EC对生殖细胞的包裹是一种共同现象，即EC-EC接触稳定了广泛的突起网络。我们进一步表明，信号转导和转录激活因子（Stat）和表皮生长因子受体（Egfr）信号通过组合影响不同RhoGTPases的活性来维持EC的突出性和灵活性。我们的结果揭示了一个复杂的信号网络如何决定细胞的形状及其动态行为。它还解释了分化区域如何与生殖细胞建立广泛的接触，同时允许分化的GSC子代持续向后移动。
