College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, 430070, China.
College of Fisheries, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Huazhong Agricultural University, Wuhan, 430070, China; College of Fisheries, Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt, Ministry of Education/Hubei Provincial Engineering Laboratory for Pond Aquaculture, Huazhong Agricultural University, Wuhan, 430070, China.
Biochem Biophys Res Commun. 2020 Nov 12;532(3):414-419. doi: 10.1016/j.bbrc.2020.08.074. Epub 2020 Aug 31.
At present, fish provide an important supply of long-chain polyunsaturated fatty acids (LC-PUFAs) for human consumption. Previous studies have shown that fatty acyl elongase 2 (elovl2) and elovl5 play important roles in fish LC-PUFA synthesis. Generally, freshwater fish have a stronger ability to synthesize LC-PUFAs than marine fish. However, the roles of elovl2, elovl5 and elovl2 + elovl5 in LC-PUFA synthesis of freshwater fish in vivo are not very clear. In this study, the elovl2 knockout zebrafish (elovl2), elovl5 knockout zebrafish (elovl5) and the double gene knockout zebrafish (DKO) were generated by CRISPR/Cas9 technology for the first time. Compared with wild type zebrafish (WT), elovl5-deletion zebrafish showed a significant increase in C22 PUFA content, which might be due to the up-regulation expressions of elovl4b and elovl2. elovl5 expressed at very low levels in livers of elovl2 relative to WT, indicating that elovl5 may be an "assistant attacker" of elovl2 in LC-PUFA synthesis of zebrafish. Moreover, there were no significant differences in levels of C18-C22 PUFAs between DKO and WT, indicating that besides elovl2 + elovl5 path, LC-PUFA synthesis in zebrafish could be performed by other paths. In addition, the hepatic lipidomic analysis results revealed that the contents of C22:6n-3 in phosphatidyl ethanolamine (PE-DHA) and PE-C22 PUFAs were more easily affected by the absence of elovl2 and elovl5. Our results suggest that the elovl2+elovl5 path is not the only path for LC-PUFA synthesis in zebrafish, and provide novel insights into the roles of elovl2 and elovl5 in LC-PUFA synthesis of freshwater fish.
目前，鱼类为人类提供了重要的长链多不饱和脂肪酸（LC-PUFA）供应。先前的研究表明，脂肪酸延长酶 2（elovl2）和 elovl5 在鱼类 LC-PUFA 合成中发挥着重要作用。一般来说，淡水鱼比海水鱼具有更强的合成 LC-PUFA 的能力。然而，elovl2、elovl5 和 elovl2+elovl5 在淡水鱼体内 LC-PUFA 合成中的作用尚不清楚。本研究首次利用 CRISPR/Cas9 技术构建了 elovl2 敲除斑马鱼（elovl2）、elovl5 敲除斑马鱼（elovl5）和双基因敲除斑马鱼（DKO）。与野生型斑马鱼（WT）相比，elovl5 缺失斑马鱼的 C22PUFA 含量显著增加，这可能是由于 elovl4b 和 elovl2 的上调表达所致。elovl2 相对于 WT 肝脏中 elovl5 的表达水平极低，表明 elovl5 可能是 LC-PUFA 合成中 elovl2 的“助攻手”。此外，DKO 和 WT 之间 C18-C22PUFAs 的水平没有显著差异，表明除了 elovl2+elovl5 途径外，LC-PUFA 在斑马鱼中的合成还可以通过其他途径进行。此外，肝脂质组学分析结果表明，PE-DHA 和 PE-C22PUFAs 中 C22:6n-3 的含量更容易受到 elovl2 和 elovl5 缺失的影响。我们的结果表明，elovl2+elovl5 途径不是斑马鱼 LC-PUFA 合成的唯一途径，为 elovl2 和 elovl5 在淡水鱼 LC-PUFA 合成中的作用提供了新的见解。
