FoxO transcription factors actuate the formative pluripotency specific gene expression programme [RNA-Seq]

Naïve pluripotency is sustained by a self-reinforcing gene regulatory network (GRN) comprising core and naïve pluripotency-specific transcription factors (TFs). Upon exiting naïve pluripotency, ES cells transition through a formative post-implantation-like pluripotent state. However, the mechanisms underlying disengagement from the naïve GRN and initiation of the formative GRN remain unclear. Here, we demonstrate that phosphorylated AKT acts as a gatekeeper that prevents nuclear localization of FoxO TFs in naïve ESCs. PTEN-mediated reduction of AKT activity allows nuclear entry by FoxO TFs, enforcing a cell fate transition by binding and activating formative pluripotency-specific enhancers. Indeed, FoxO TFs are necessary and sufficient for transition from the naïve to the formative pluripotent state. Our work uncovers a pivotal role for FoxO TFs and AKT signalling in mechanisms underlying the exit from naïve pluripotency, a critical early embryonic cell fate transition. Quantseq experiments from ES cells frown in 2i and in differentiation conditions in N2B27 medium; WT, Pten KO, Tsc2 KOs treated with DMSO and with a variety of inhibitorrs are used

初始多能性（naïve pluripotency）由包含核心转录因子与初始多能性特异性转录因子（transcription factors, TFs）的自我强化基因调控网络（gene regulatory network, GRN）所维持。胚胎干细胞（embryonic stem cells, ESCs）退出初始多能性状态后，会过渡至一段成形期着床后样多能状态。然而，脱离初始GRN并启动成形期GRN的分子机制仍不明确。本研究证实，磷酸化AKT可作为调控关卡，阻止FoxO家族转录因子在初始态ESCs中的核定位。PTEN介导的AKT活性下调可使FoxO转录因子发生核转位，通过结合并激活成形期多能性特异性增强子，推动细胞命运转变。实验证明，FoxO转录因子对于从初始多能性向成形期多能性的转变既是必需的，也足以诱导该过程。本研究揭示了FoxO转录因子及AKT信号通路在初始多能性退出这一关键早期胚胎细胞命运转变过程中的核心作用。本研究针对在2i培养体系及N2B27培养基分化条件下培养的ES细胞开展了Quantseq测序实验，并使用经二甲基亚砜（dimethyl sulfoxide, DMSO）及多种抑制剂处理的野生型（wild type, WT）、Pten基因敲除（Pten knockout, Pten KO）与Tsc2基因敲除（Tsc2 knockout, Tsc2 KO）细胞进行相关分析。