Cirera-Salinas Daniel, Yu Jian, Bodak Maxime, Ngondo Richard P, Herbert Kristina M, Ciaudo Constance
Department of Biology, Institute of Molecular Health Sciences, RNAi and Genome Integrity, Swiss Federal Institute of Technology Zurich, Zurich 8093, Switzerland.
Life Science Zurich Graduate School, University of Zurich, Zurich 8093, Switzerland.
J Cell Biol. 2017 Feb;216(2):355-366. doi: 10.1083/jcb.201606073. Epub 2017 Jan 18.
Mouse embryonic stem cells (mESCs) deficient for DGCR8, a key component of the microprocessor complex, present strong differentiation defects. However, the exact reasons impairing their commitment remain elusive. The analysis of newly generated mutant mESCs revealed that DGCR8 is essential for the exit from the pluripotency state. To dissociate canonical versus noncanonical functions of DGCR8, we complemented the mutant mESCs with a phosphomutant DGCR8, which restored microRNA levels but did not rescue the exit from pluripotency defect. Integration of omics data and RNA immunoprecipitation experiments established DGCR8 as a direct interactor of Tcf7l1 mRNA, a core component of the pluripotency network. Finally, we found that DGCR8 facilitated the splicing of Tcf7l1, an event necessary for the differentiation of mESCs. Our data reveal a new noncanonical function of DGCR8 in the modulation of the alternative splicing of Tcf7l1 mRNA in addition to its established function in microRNA biogenesis.
DGCR8是微处理器复合物的关键组成部分，缺乏DGCR8的小鼠胚胎干细胞（mESC）存在严重的分化缺陷。然而，损害它们定向分化的确切原因仍不清楚。对新产生的突变mESC的分析表明，DGCR8对于退出多能性状态至关重要。为了区分DGCR8的经典功能与非经典功能，我们用磷酸化突变体DGCR8对突变mESC进行了补充，该突变体恢复了微小RNA水平，但未能挽救多能性缺陷的退出。组学数据与RNA免疫沉淀实验相结合，确定DGCR8是多能性网络的核心组成部分Tcf7l1 mRNA的直接相互作用分子。最后，我们发现DGCR8促进了Tcf7l1的剪接，这是mESC分化所必需的事件。我们的数据揭示了DGCR8在Tcf7l1 mRNA可变剪接调控中的一种新的非经典功能，此外它在微小RNA生物合成中也具有既定功能。
