Key Laboratory of Freshwater Biodiversity Conservation, Ministry of Agriculture of China, Yangtze River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Wuhan 430223, China.
School of Animal Science, Yangtze University, Jingzhou, 434020, China.
Fish Shellfish Immunol. 2018 Aug;79:363-369. doi: 10.1016/j.fsi.2018.05.023. Epub 2018 May 15.
Liver-expressed antimicrobial peptide 2 (leap-2) is an evolutionarily ancient molecule that acts as the key component in vertebrate innate immunity against invading pathogens. Leap-2 has been identified and characterised in several teleosts, but not yet in chondrosteans. Herein, the complete coding sequences of leap-2b and leap-2c were identified from expressed sequence tags (ESTs) isolated from Dabry's sturgeon (Acipenser dabryanus) and Chinese sturgeon (A. sinensis), designated as adleap-2b, adleap-2c, asleap-2b, and asleap-2c, respectively. Adleap-2b and adleap-2c sequences share 98% and 100% sequence identity with asleap-2b, and asleap-2c, respectively. Sequence alignment revealed that all four genes contain four cysteine residues, conserved in all fish leap-2 homologs, that form two disulfide bonds. Comparative analysis of the exon-intron structure revealed a three exon/two intron structure for that leap-2 genes in animals, but intron 1 is much longer in sturgeons than in other species. The adleap-2c gene was expressed mainly in the liver of Dabry's sturgeon, and transcription of adleap-2c was significantly up-regulated (p < 0.05) in the liver and midkidney in response to Aeromonas hydrophila challenge. These results suggest adleap-2c may contribute to the defence against pathogenic bacterial invasion. The findings further our understanding of the function of adleap-2c and the molecular mechanism of innate immunity in chondrosteans.
肝表达抗菌肽 2（leap-2）是一种进化古老的分子，作为脊椎动物先天免疫抵抗入侵病原体的关键成分。leap-2 已在几种硬骨鱼中被鉴定和描述，但在软骨鱼中尚未发现。本文从达氏鲟（Acipenser dabryanus）和中华鲟（A. sinensis）的表达序列标签（EST）中鉴定并表征了 leap-2b 和 leap-2c 的完整编码序列，分别命名为adleap-2b、adleap-2c、asleap-2b 和 asleap-2c。Adleap-2b 和 adleap-2c 序列与 asleap-2b 和 asleap-2c 分别具有 98%和 100%的序列同一性。序列比对显示，这四个基因都含有四个半胱氨酸残基，在所有鱼类 leap-2 同源物中保守，形成两个二硫键。外显子-内含子结构的比较分析显示，动物 leap-2 基因具有三外显子/两内含子结构，但在内含子 1 中，鲟鱼比其他物种长得多。Adleap-2c 基因主要在达氏鲟的肝脏中表达，并且转录水平在受到嗜水气单胞菌攻击后在肝脏和中肾中显著上调（p < 0.05）。这些结果表明 adleap-2c 可能有助于抵抗致病性细菌的入侵。这些发现进一步了解了 adleap-2c 的功能和软骨鱼先天免疫的分子机制。
