Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629 HZ, Delft, The Netherlands.
Biochemical Engineering, Saarland University, Campus A 1.5, 66123, Saarbrücken, Germany.
Metabolomics. 2019 Aug 29;15(9):121. doi: 10.1007/s11306-019-1584-4.
The switch from quiescence (G0) into G1 and cell cycle progression critically depends on specific nutrients and metabolic capabilities. Conversely, metabolic networks are regulated by enzyme-metabolite interaction and transcriptional regulation that lead to flux modifications to support cell growth. How cells process and integrate environmental information into coordinated responses is challenging to analyse and not yet described quantitatively.
To quantitatively monitor the central carbon metabolism during G0 exit and the first 2 h after reentering the cell cycle from synchronized Saccharomyces cerevisiae.
Dynamic tailored C metabolic flux analysis was used to observe the intracellular metabolite flux changes, and the metabolome and proteome were observed to identify regulatory mechanisms.
G0 cells responded immediately to an extracellular increase of glucose. The intracellular metabolic flux changed in time and specific events were observed. High fluxes into trehalose and glycogen synthesis were observed during the G0 exit. Both fluxes then decreased, reaching a minimum at t = 65 min. Here, storage degradation contributed significantly (i.e. 21%) to the glycolytic flux. In contrast to these changes, the glucose uptake rate remained constant after the G0 exit. The flux into the oxidative pentose phosphate pathway was highest (29-fold increase, 36.4% of the glucose uptake) at t = 65 min, while it was very low at other time points. The maximum flux seems to correlate with a late G1 state preparing for the S phase transition. In the G1/S phase (t = 87 min), anaplerotic reactions such as glyoxylate shunt increased. Protein results show that during this transition, proteins belonging to clusters related with ribosome biogenesis and assembly, and initiation transcription factors clusters were continuously synthetised.
The intracellular flux distribution changes dynamically and these major rearrangements highlight the coordinate reorganization of metabolic flux to meet requirements for growth during different cell state.
从静止期（G0）进入 G1 期和细胞周期进展，关键取决于特定的营养物质和代谢能力。相反，代谢网络受到酶-代谢物相互作用和转录调控的调节，导致通量的改变，以支持细胞生长。细胞如何处理和整合环境信息，以协调响应，是具有挑战性的分析，目前尚未进行定量描述。
定量监测同步化的酿酒酵母从静止期退出到重新进入细胞周期后的头 2 小时内的中央碳代谢。
使用动态定制的 C 代谢通量分析来观察细胞内代谢物通量的变化，并观察代谢组和蛋白质组以识别调控机制。
G0 细胞对外界葡萄糖的增加立即做出反应。细胞内代谢通量随时间变化，观察到特定事件。在 G0 退出期间，观察到进入海藻糖和糖原合成的高通量。这两种通量随后降低，在 t=65 分钟时达到最小值。此时，储存降解对糖酵解通量有显著贡献（即 21%）。与这些变化相反，G0 退出后葡萄糖摄取率保持不变。在 t=65 分钟时，氧化戊糖磷酸途径的通量最高（增加 29 倍，占葡萄糖摄取量的 36.4%），而在其他时间点则非常低。最大通量似乎与准备 S 期过渡的晚期 G1 状态相关。在 G1/S 期（t=87 分钟），乙醛酸支路等回补反应增加。蛋白质结果表明，在这一转变过程中，与核糖体生物发生和组装相关的簇以及起始转录因子簇的蛋白质持续合成。
细胞内通量分布动态变化，这些主要的重排突出了代谢通量的协调重组，以满足不同细胞状态下生长的要求。
