Effect of the deletion of the genes involved in phospholipid synthesis pathway on gene expression (DKO)

Phospholipid and nucleotide syntheses are fundamental metabolic processes in eukaryotic organisms, with their dysregulation implicated in various disease states. However, the interplay between these pathways remains elusive. With genetic and metabolic analyses in the yeast S. cerevisiae, we elucidate how cytidine triphosphate utilization and recycling in the Kennedy pathway for phospholipid synthesis influence nucleotide metabolism and redox balance. Deficiencies in the Kennedy pathway impose constraints on nucleotide salvage, prompting compensatory co-activation of de novo nucleotide synthesis and the pentose phosphate pathway. Consequently, this metabolic shift towards alternative nucleotide and phospholipid synthesis pathways fosters the production of antioxidants such as NADPH and glutathione. Additionally, we observe that this oxidation-responsive Kennedy pathway for phospholipid synthesis is inhibited during replicative aging, highlighting its activation as an antioxidative defense mechanism in aged cells. These findings underscore the critical role of pathway choice in phospholipid synthesis in the integrative regulation of nucleotide metabolism, redox balance, and membrane biophysical properties for cellular defense.磷脂（phospholipid）与核苷酸（nucleotide）合成是真核生物的核心代谢过程，其失调与多种疾病状态密切相关。然而，这两条代谢通路间的相互作用仍尚不明确。 本研究以酿酒酵母（S. cerevisiae）为模型开展遗传与代谢分析，阐明了磷脂合成肯尼迪途径（Kennedy pathway）中胞苷三磷酸（cytidine triphosphate）的利用与循环模式，如何调控核苷酸代谢与氧化还原平衡。 肯尼迪途径缺陷会对核苷酸补救合成造成限制，进而触发从头核苷酸合成与磷酸戊糖途径的代偿性共同激活。 由此产生的朝向替代性核苷酸与磷脂合成通路的代谢重编程，可促进烟酰胺腺嘌呤二核苷酸磷酸（NADPH）、谷胱甘肽（glutathione）等抗氧化剂的生成。 此外，本研究观察到，上述响应氧化应激的磷脂合成肯尼迪途径在细胞复制性衰老过程中受到抑制，提示该通路的激活可作为衰老细胞的抗氧化防御机制。 本研究结果凸显了磷脂合成通路选择在核苷酸代谢、氧化还原平衡以及膜生物物理特性的整合调控中的关键作用，进而参与细胞防御过程。