DHA与EPA合成超长链多不饱和脂肪酸的效率比较

Comparison of elongation efficiency between DHA and EPA in synthesis of very long chain polyunsaturated fatty acids

目的比较在ELOVL4蛋白酶催化作用下,DHA和EPA合成超长链多不饱和脂肪酸VLC-PUFA的效率。方法构建携带ELOVL4基因和绿色荧光蛋白的重组腺病毒,转入培养的PC12细胞,通过qRT-PCR定量分析ELOVL4基因的表达量,WB检测ELOVL4蛋白的表达;1∶1加入DHA和EPA,孵育48 h之后进行脂肪酸提取,通过气相质谱GC-MS分析超长链脂肪酸的成分。结果 GC-MS检测到分别用DHA及EPA处理后的PC12+Ad-ELOVL4的细胞中有n3 VLC-PUFA的表达,34:5n3和36:5n3分别为0.85%和1.11%;34:6n3和36:6n3分别为0.16%和0.29%;EPA所产生的五烯酸总和是DHA所产生的六烯酸总和的4倍。结论 EPA合成VLC-PUFA的效率远远高于DHA,为患者提供更高比例的EPA,而非DHA,可能是治疗STGD3疾病的方式之一。

Objective To compare the elongation efficiency between DHA and EPA for synthesis of very long chain polyunsat -urated fatty acid （VLC-PUFAs） under catalytic action of ELOVL4 protease.Methods PC12 cells were transduced with recombinant adenovirus type 5 carrying mouse Elovl4 and green fluorescent protein （GFP）.GFP-expressing and non-transduced cells were used as controls.ELOVL4 gene expression was quantified by qRT-PCRs.ELOVL4 protein was analyzed by Western-Blot （WB）.The transduced cells were treated with DHA or EPA （1：1）.After 48 h of incubation,cells were collected,and fatty acid methyl esters were prepared following total lipids extraction .The fatty acid was analyzed by using a gas chromatography-mass spectrometry （ GC-MS） .Results GC-MS analysis showed that the DHA and EPA treated PC 12＋Ad-ELOVL4 had n3 VLC-PUFAs in which 34：5n3 and 36：5n3 were 0.85%and 1.11%,respectively;34：6n3 and 36：6n3 were 0.16% and 0.29%,respectively.Total amount of pentaenoics synthesized from EPA was almost four times than that of hexaenoics synthesized from DHA .Conclusion Elongation efficiency of VLC-PUFAs from EPA is much higher than that from DHA .Therefore,dietary supplementation of more EPA rather than DHA may provide some therapeutic benefits for patients with Stargardts＆#39;disease （STGD3）.