Kang Soeun, Antoniewicz Maciek R, Hay Nissim
Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL, USA.
Chemical Engineering Department, University of Michigan, Ann Arbor, MI, USA.
Nat Commun. 2024 Aug 8;15(1):6777. doi: 10.1038/s41467-024-51117-y.
Metabolic rewiring during the proliferation-to-quiescence transition is poorly understood. Here, using a model of contact inhibition-induced quiescence, we conducted C-metabolic flux analysis in proliferating (P) and quiescent (Q) mouse embryonic fibroblasts (MEFs) to investigate this process. Q cells exhibit reduced glycolysis but increased TCA cycle flux and mitochondrial respiration. Reduced glycolytic flux in Q cells correlates with reduced glycolytic enzyme expression mediated by yes-associated protein (YAP) inhibition. The increased TCA cycle activity and respiration in Q cells is mediated by induced mitochondrial pyruvate carrier (MPC) expression, rendering them vulnerable to MPC inhibition. The malate-to-pyruvate flux, which generates NADPH, is markedly reduced by modulating malic enzyme 1 (ME1) dimerization in Q cells. Conversely, the malate dehydrogenase 1 (MDH1)-mediated oxaloacetate-to-malate flux is reversed and elevated in Q cells, driven by high mitochondrial-derived malate levels, reduced cytosolic oxaloacetate, elevated MDH1 levels, and a high cytoplasmic NAD/NADH ratio. Transcriptomic analysis revealed large number of genes are induced in Q cells, many of which are associated with the extracellular matrix (ECM), while YAP-dependent and cell cycle-related genes are repressed. The results suggest that high TCA cycle flux and respiration in Q cells are required to generate ATP and amino acids to maintain de-novo ECM protein synthesis and secretion.
细胞从增殖状态转变为静止状态期间的代谢重编程仍知之甚少。在此，我们利用接触抑制诱导静止的模型，对增殖期（P）和静止期（Q）的小鼠胚胎成纤维细胞（MEF）进行了碳代谢通量分析，以研究这一过程。Q细胞的糖酵解作用减弱，但三羧酸循环通量和线粒体呼吸作用增强。Q细胞中糖酵解通量的降低与Yes相关蛋白（YAP）抑制介导的糖酵解酶表达降低相关。Q细胞中三羧酸循环活性和呼吸作用的增强是由诱导的线粒体丙酮酸载体（MPC）表达介导的，这使得它们易受MPC抑制的影响。通过调节Q细胞中的苹果酸酶1（ME1）二聚化，生成NADPH的苹果酸到丙酮酸的通量显著降低。相反，在高线粒体来源的苹果酸水平、降低的胞质草酰乙酸、升高的苹果酸脱氢酶1（MDH1）水平和高细胞质NAD/NADH比值的驱动下，MDH1介导的草酰乙酸到苹果酸的通量在Q细胞中发生逆转并升高。转录组分析显示，Q细胞中有大量基因被诱导，其中许多与细胞外基质（ECM）相关，而YAP依赖和细胞周期相关基因则受到抑制。结果表明，Q细胞中高的三羧酸循环通量和呼吸作用对于生成ATP和氨基酸以维持从头合成ECM蛋白及分泌是必需的。
