Background Mitochondrial serine catabolism to formate induces a metabolic switch to a hypermetabolic state with high rates of glycolysis, purine synthesis and pyrimidine synthesis. While formate is a purine precursor, it is not clear how formate induces pyrimidine synthesis. Methods Here we combine phospho-proteome and metabolic profiling to determine how formate induces pyrimidine synthesis. Results We discover that formate induces phosphorylation of carbamoyl phosphate synthetase (CAD), which is known to increase CAD enzymatic activity. Mechanistically, formate induces mechanistic target of rapamycin complex 1 (mTORC1) activity as quantified by phosphorylation of its targets S6, 4E-BP1, S6K1 and CAD. Treatment with the allosteric mTORC1 inhibitor rapamycin abrogates CAD phosphorylation and pyrimidine synthesis induced by formate. Furthermore, we show that the formate-dependent induction of mTOR signalling and CAD phosphorylation is dependent on an increase in purine synthesis. Conclusions We conclude that formate activates mTORC1 and induces pyrimidine synthesis via the mTORC1-dependent phosphorylation of CAD.

中文翻译：

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甲酸转化为嘌呤刺激 mTORC1 导致嘧啶合成的 CAD 依赖性激活

背景 线粒体丝氨酸分解代谢为甲酸会诱导代谢转变为高代谢状态，糖酵解、嘌呤合成和嘧啶合成的速率很高。虽然甲酸盐是一种嘌呤前体，但尚不清楚甲酸盐如何诱导嘧啶合成。方法 在这里，我们结合磷酸化蛋白质组和代谢分析来确定甲酸盐如何诱导嘧啶合成。结果 我们发现甲酸盐会诱导氨基甲酰磷酸合成酶 (CAD) 的磷酸化，已知这会增加 CAD 酶的活性。从机制上讲，甲酸盐诱导雷帕霉素复合物 1 (mTORC1) 活性的机械靶点，通过其靶点 S6、4E-BP1、S6K1 和 CAD 的磷酸化来量化。用别构 mTORC1 抑制剂雷帕霉素治疗可消除甲酸盐诱导的 CAD 磷酸化和嘧啶合成。此外，我们表明，甲酸盐依赖性 mTOR 信号传导和 CAD 磷酸化的诱导依赖于嘌呤合成的增加。结论 我们得出结论，甲酸盐通过 mTORC1 依赖性 CAD 磷酸化激活 mTORC1 并诱导嘧啶合成。