Metabolism of propionic acid to a novel acyl-coenzyme A thioester by mammalian cell lines and platelets
Metabolism of propionic acid to a novel acyl-coenzyme A thioester by mammalian cell lines and platelets
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DOI：
10.1194/jlr.m055384
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发表时间：
2015-01-01
影响因子：
6.5
通讯作者：
Blair, Ian A.
中科院分区：
文献类型：
--
作者：
Snyder, Nathaniel W.;Basu, Sankha S.;Blair, Ian A.
丙酸盐的代谢涉及活化的酰基硫酯丙酰辅酶A中间体。我们采用LC-MS/MS、LC-选择反应监测/MS和LC-高分辨率MS研究丙酸盐代谢为酰基辅酶A中间体。我们发现丙酰辅酶A可以作为直接形成新的六碳单不饱和酰基辅酶A的前体。在人肝细胞癌HepG2细胞中的时间过程和剂量反应研究表明，六碳单不饱和酰基辅酶A是丙酸依赖性的，并随着时间的推移进行进一步的代谢。利用[C-13（1）]丙酸酯和[C-13（3）]丙酸酯的研究表明了脂肪酸合成的机制，该机制保持了来自两个丙酸酯分子的所有六个碳原子。2，2-[H-2（2）]丙酸酯代谢为新的六碳单不饱和酰基-CoA导致两个氘原子完全丢失，表明丙酰基部分的C2处发生修饰。共洗脱实验和同位素示踪研究证实新的酰基辅酶A是反式-2-甲基-2-戊烯酰辅酶A。用单不饱和六碳脂肪酸处理HepG2细胞后的酰基辅酶A谱也支持这一结论。用人血小板、小鼠肝细胞癌Hepa1c1c7细胞、人支气管肺泡癌H358细胞和人结肠腺癌LoVo细胞获得了类似的结果。有趣的是，反式-2-甲基-2-戊烯酰辅酶A对应于先前描述的酰基肉毒碱，在丙酸和甲基丙二酸血症患者中暂时描述。我们提出了一个机制，这种代谢途径与所有上述发现一致。
Metabolism of propionate involves the activated acyl-thioester propionyl-CoA intermediate. We employed LC-MS/MS, LC-selected reaction monitoring/MS, and LC-high-resolution MS to investigate metabolism of propionate to acyl-CoA intermediates. We discovered that propionyl-CoA can serve as a precursor to the direct formation of a new six-carbon mono-unsaturated acyl-CoA. Time course and dose-response studies in human hepatocellular carcinoma HepG2 cells demonstrated that the six-carbon mono-unsaturated acyl-CoA was propionate-dependent and underwent further metabolism over time. Studies utilizing [C-13(1)] propionate and [C-13(3)] propionate suggested a mechanism of fatty acid synthesis, which maintained all six-carbon atoms from two propionate molecules. Metabolism of 2,2-[H-2(2)] propionate to the new six-carbon mono-unsaturated acyl-CoA resulted in the complete loss of two deuterium atoms, indicating modification at C2 of the propionyl moiety. Coelution experiments and isotopic tracer studies confirmed that the new acyl-CoA was trans-2-methyl-2-pentenoyl-CoA. Acyl-CoA profiles following treatment of HepG2 cells with mono-unsaturated six-carbon fatty acids also supported this conclusion. Similar results were obtained with human platelets, mouse hepatocellular carcinoma Hepa1c1c7 cells, human bronchoalveolar carcinoma H358 cells, and human colon adenocarcinoma LoVo cells. Interestingly, trans-2-methyl-2-pentenoyl-CoA corresponds to a previously described acylcarnitine tentatively described in patients with propionic and methylmalonic acidemia. We have proposed a mechanism for this metabolic route consistent with all of the above findings.