In the Drosophila ovary, escort cells (ECs) extrinsically control germline stem cell (GSC) maintenance and progeny differentiation. However, the underlying mechanisms remain poorly understood. In this study, we identified 173 EC genes for their roles in controlling GSC maintenance and progeny differentiation by using an in vivo systematic RNAi approach. Of the identified genes, 10 and 163 are required in ECs to promote GSC maintenance and progeny differentiation, respectively. The genes required for progeny differentiation fall into different functional categories, including transcription, mRNA splicing, protein degradation, signal transduction and cytoskeleton regulation. In addition, the GSC progeny differentiation defects caused by defective ECs are often associated with BMP signaling elevation, indicating that preventing BMP signaling is a general functional feature of the differentiation niche. Lastly, exon junction complex (EJC) components, which are essential for mRNA splicing, are required in ECs to promote GSC progeny differentiation by maintaining ECs and preventing BMP signaling. Therefore, this study has identified the major regulators of the differentiation niche, which provides important insights into how stem cell progeny differentiation is extrinsically controlled.

在果蝇卵巢中，伴游细胞（EC）外在地控制种系干细胞（GSC）的维持和子代分化。但是，基本机制仍然知之甚少。在这项研究中，我们确定了173个EC基因通过在体内使用来控制GSC维持和子代分化系统性RNAi方法。在已鉴定的基因中，EC中分别需要10和163个基因来促进GSC维持和后代分化。子代分化所需的基因分为不同的功能类别，包括转录，mRNA剪接，蛋白质降解，信号转导和细胞骨架调节。此外，由有缺陷的EC引起的GSC后代分化缺陷通常与BMP信号升高有关，这表明防止BMP信号传导是分化位的普遍功能。最后，EC中需要mRNA剪接必不可少的外显子连接复合体（EJC）成分，以通过维持EC并防止BMP信号传导来促进GSC后代分化。所以，