Grigorash B B, Suvorova I I, Pospelov V A
Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064 Russia.
Mol Biol (Mosk). 2018 May-Jun;52(3):489-500. doi: 10.7868/S0026898418030126.
Embryonic stem cells (ESCs) have the capacity for self-renewal and pluripotency. Due to high proliferative activity, ESCs use a specific pathway of the formation of ATP molecules, which can lead to the development of the adaptive metabolic response under the conditions of energy deficiency (which is different from the response of differentiated cells). It is known that metabolic signals are integrated with the cell cycle progression; however, the signaling pathways that connect the availability of nutrients with the regulation of cell cycle in ESCs are insufficiently studied. We have studied the effect of the AICAR agent, which imitates an increase in AMP level and induces the activation of the metabolic sensor AMPK, on proliferation, cell cycle distribution, and pluripotency of mouse ESCs (mESCs). It has been demonstrated that cells treated with AICAR do not stop at the control G1/S point of the cell cycle, since they do not accumulate P21/WAF1 (G1/S checkpoint regulator), despite P53 activation. On the contrary, AICAR increases the rate of mESC proliferation, which correlates with increased expression of pluripotency marker genes (OCT3/4, NANOG, SOX2, KLF4, ESRRB, PRDM14). In addition, an increase in the transcription of the HIFlα gene (a key regulator of the cell proliferation and viability, as well as glucose metabolism under stress) was detected. An increase in the expression of glycolytic enzyme genes (LDHA, ALDOA, PCK2, GLUT4) under the effect of AICAR indicates a change in mESC metabolism towards increased glycolysis. Thus, AICAR-dependent AMPK activation as one of possible mechanisms of the mESC adaptive response to the emergence of energetic imbalance is not accompanied by a cell cycle arrest at the G1/S checkpoint, but involves the processes of increasing glycolytic activity.
胚胎干细胞（ESCs）具有自我更新和多能性的能力。由于高增殖活性，胚胎干细胞利用一种特定的ATP分子形成途径，这可能导致在能量缺乏条件下适应性代谢反应的发展（这与分化细胞的反应不同）。已知代谢信号与细胞周期进程整合；然而，连接营养物质可用性与胚胎干细胞中细胞周期调控的信号通路尚未得到充分研究。我们研究了AICAR试剂对小鼠胚胎干细胞（mESCs）增殖、细胞周期分布和多能性的影响，该试剂模拟AMP水平的增加并诱导代谢传感器AMPK的激活。已经证明，用AICAR处理的细胞不会在细胞周期的对照G1/S点停滞，因为尽管P53被激活，但它们不会积累P21/WAF1（G1/S检查点调节因子）。相反，AICAR增加了mESCs的增殖速率，这与多能性标记基因（OCT3/4、NANOG、SOX2、KLF4、ESRRB、PRDM14）表达的增加相关。此外，检测到HIFlα基因（细胞增殖和活力以及应激下葡萄糖代谢的关键调节因子）的转录增加。在AICAR作用下糖酵解酶基因（LDHA、ALDOA、PCK2、GLUT4）表达的增加表明mESCs的代谢向增加糖酵解转变。因此，作为mESCs对能量失衡出现的适应性反应的可能机制之一，AICAR依赖的AMPK激活并不伴随着细胞周期在G1/S检查点的停滞，而是涉及增加糖酵解活性的过程。
