Coordinated repression of pro-differentiation genes via P-bodies and transcription maintains Drosophila intestinal stem cell identity. Coordinated repression of pro-differentiation genes via P-bodies and transcription maintains Drosophila intestinal stem cell identity

The role of Processing bodies (P-bodies), key sites of post-transcriptional control, in adult stem cells remains poorly understood. Here, we report that adult Drosophila intestinal stem cells, but not surrounding differentiated cells such as absorptive Enterocytes (ECs), harbor P-bodies that contain Drosophila orthologs of mammalian P-body components DDX6, EDC3, EDC4 and LSM14A/B. A targeted RNAi screen in intestinal progenitor cells identified 39 previously known and 64 novel P-body regulators, including Patr-1, a gene necessary for P-body assembly. Loss of Patr-1-dependent P-bodies leads to a loss of stem cells that is associated with inappropriate translation and expression of EC-fate gene nubbin. Transcriptomic analysis of progenitor cells identifies a cadre of such weakly transcribed pro-differentiation transcripts that are elevated after P-body loss. Altogether, this study identifies a coordinated P-body dependent, translational and transcriptional repression program that maintains a defined set of in vivo stem cells in a state primed for differentiation. Overall design: Identification of RNAs regulated by P-bodies using RNA-seq.

作为转录后调控的关键位点，处理小体（Processing bodies, P-bodies）在成体干细胞中的功能仍未被充分阐明。本研究发现，成年果蝇肠道干细胞而非周围的吸收型肠上皮细胞（Enterocytes, ECs）等分化细胞，拥有携带哺乳动物P体组分DDX6、EDC3、EDC4及LSM14A/B的果蝇同源物的P体。我们针对肠道祖细胞开展靶向RNA干扰（RNAi）筛选，共鉴定出39个已知P体调控因子与64个新型P体调控因子，其中包括P体组装必需基因Patr-1。缺失Patr-1依赖的P体将导致干细胞丢失，这一现象与肠上皮细胞命运基因nubbin的异常翻译及表达密切相关。对祖细胞的转录组分析显示，P体缺失后，一批此类弱转录的促分化转录本的丰度显著升高。综上，本研究揭示了一套依赖P体的协同翻译与转录抑制程序，该程序可维持特定体内干细胞群体处于分化预激活状态。整体实验设计：通过RNA测序（RNA-seq）鉴定P体调控的RNA分子。