Stem cell-specific depletion of NF-kB transcription factor Relish alters intestinal response to DSS induced injury

Immune pathways are important regulators of intestinal stem cell function, yet how these pathways act within stem cells in not well known. To determine the function of immunity in stem cells of the intestine we used Drosophila as a model. We knocked down the NF-kB family transcription factor Relish in intestinal stem cells and upon exposure to the colitis inducing chemical DSS, these intestines become hyperplastic and the flies die faster. We then performed single cell RNA sequencing to determine the role of Relish in stem cells upon damage. With the sequencing data we found profound effects of Relish depletion on the ability of the intestine to produce premature enterocytes upon damage. Within stem cells, Relish altered the expression of EGF/Ras regulators. Further experiments showed that Relish acts through Ras in stem cells to control intestinal cell death and proliferation to modulate repair upon injury. Given the important role immunity and Ras signaling plays in intestinal homeostasis and disease our findings uncover important insight into the mechanisms in which immune pathways control stem cell function and intestinal health.

免疫通路是肠道干细胞功能的重要调控因子，然而此类通路在干细胞内的具体作用机制尚未完全阐明。为探究免疫通路在肠道干细胞中的功能，本研究以果蝇（Drosophila）作为模式生物。我们在肠道干细胞中敲低了核因子κB（NF-kB）家族转录因子Relish，当受试对象暴露于诱发结肠炎的化学物质葡聚糖硫酸钠（DSS）后，肠道组织出现异常增生，果蝇的存活时间显著缩短。随后，我们通过单细胞RNA测序（single cell RNA sequencing）分析了损伤状态下Relish在干细胞中的作用。基于测序数据，我们发现Relish缺失可显著影响肠道在损伤状态下生成未成熟肠上皮细胞的能力。在干细胞内，Relish可调控表皮生长因子（EGF）/Ras信号通路调控因子的表达。进一步实验表明，Relish可通过干细胞内的Ras通路调控肠道细胞的死亡与增殖，从而调节损伤后的肠道修复过程。鉴于免疫通路与Ras信号通路在肠道稳态及疾病中发挥的重要作用，本研究的发现为阐明免疫通路调控干细胞功能与肠道健康的具体机制提供了关键科学见解。