Li Yongnan, Tocher Douglas R, Pang Yuning, Du Jianlong, Xiang Xiaojun, Mai Kangsen, Ai Qinghui
Key Laboratory of Aquaculture Nutrition and Feed (Ministry of Agriculture) & Key Laboratory of Mariculture (Ministry of Education), Ocean University of China, 5 Yushan Road, Qingdao, Shandong 266003, China.
Guangdong Provincial Key Laboratory of Marine Biotechnology, Institute of Marine Sciences, Shantou University, Shantou, China.
Int J Biol Macromol. 2022 Apr 15;204:144-153. doi: 10.1016/j.ijbiomac.2022.01.184. Epub 2022 Feb 1.
Fish are the main source of long-chain polyunsaturated fatty acids (LC-PUFA) for human consumption. In the process of evolution via natural selection, adaptation to distinct environments has likely driven changes in the endogenous capacity for LC-PUFA biosynthesis between marine and freshwater fishes. However, the molecular mechanisms underlying adaptive changes in this metabolic pathway are poorly understood. Here, we compared the transcriptional regulation of elongation of very long chain fatty acids protein 5 (Elovl5), which is one of the critical enzymes in LC-PUFA biosynthesis pathway, in marine large yellow croaker (Larimichthys crocea) and freshwater rainbow trout (Oncorhynchus mykiss). Comparative transcriptomic and absolute mRNA quantification analyses revealed that the expression of elovl5 in rainbow trout was markedly higher than that in large yellow croaker. Correspondingly, the number of chromatin accessible areas in the regulatory region of elovl5 in rainbow trout was higher than in large yellow croaker, which revealed that chromatin accessibility in the regulatory region of elovl5 in rainbow trout was higher. Furthermore, the differences in sequence and activity of the elovl5 promoter were observed between rainbow trout and large yellow croaker, and transcription factors including CCAAT/enhancer-binding protein β (CEBPβ), GATA binding protein 3 (GATA3) and upstream stimulatory factor 2 (USF2) displayed different regulatory roles on elovl5 expression between the two species. We propose that changes in the gene regulatory region driven by natural selection likely play a key role in differences in elovl5 expression and the activity of Elovl5, which may influence the LC-PUFA biosynthesis capacities of rainbow trout and large yellow croaker. These findings may also provide opportunities to improve the quality of aquatic products and, consequently, human health.
鱼类是人类食用长链多不饱和脂肪酸（LC-PUFA）的主要来源。在自然选择的进化过程中，对不同环境的适应可能推动了海洋鱼类和淡水鱼类之间LC-PUFA生物合成内源性能力的变化。然而，这种代谢途径适应性变化的分子机制仍知之甚少。在此，我们比较了海洋大黄鱼（Larimichthys crocea）和淡水虹鳟（Oncorhynchus mykiss）中长链多不饱和脂肪酸生物合成途径关键酶之一的超长链脂肪酸延伸蛋白5（Elovl5）的转录调控。比较转录组学和绝对mRNA定量分析表明，虹鳟中elovl5的表达明显高于大黄鱼。相应地，虹鳟中elovl5调控区域的染色质可及区域数量高于大黄鱼，这表明虹鳟中elovl5调控区域的染色质可及性更高。此外，观察到虹鳟和大黄鱼之间elovl5启动子的序列和活性存在差异，包括CCAAT/增强子结合蛋白β（CEBPβ）、GATA结合蛋白3（GATA3）和上游刺激因子2（USF2）在内的转录因子在这两个物种中对elovl5表达发挥不同的调控作用。我们认为，自然选择驱动的基因调控区域变化可能在elovl5表达和Elovl5活性差异中起关键作用，这可能影响虹鳟和大黄鱼的LC-PUFA生物合成能力。这些发现也可能为提高水产品质量从而改善人类健康提供机会。
