State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, 410081, China.
State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Sciences, Hunan Normal University, Changsha, 410081, China.
Fish Shellfish Immunol. 2020 Jul;102:47-55. doi: 10.1016/j.fsi.2020.04.015. Epub 2020 Apr 10.
Lipocalin 2 (Lcn2) has been identified in mammals, however, the in vivo function of fish Lcn2 is essentially unknown. Triploid crucian carp (3n = 150) of red crucian carp (female, 2n = 100) and allotetraploid (male, 4n = 200) shows better resistance to pathogenic infections. To elucidate the antimicrobial mechanism of triploid crucian carp, we examined the function of a novel Lcn2 from triploid crucian carp (3nLcn2). 3nLcn2 is 183 residues in length and contains a conserved lipocalin domain. Quantitative real time reverse transcription PCR (qRT-PCR) analysis showed that 3nLcn2 expression occurred in multiple tissues and was upregulated by bacterial infection in a time-dependent manner. We found that purified recombinant 3nLcn2 (r3nLcn2) exerted bactericidal activity to Aeromonas hydrophila and Escherichia coli. qRT-PCR detected increased expression of pro-inflammatory cytokines and tight junctions in fish with 3nLcn2 overexpression. Fish administered with 3nLcn2 exhibited enhanced intestinal barrier and resistance against bacterial infection. These results provide the first evidence that 3nLcn2 is a functional lipocalin with antimicrobial activity and plays a positive role in the immune defense during bacterial infection.
脂联素 2（Lcn2）在哺乳动物中已被鉴定，但鱼类 Lcn2 的体内功能基本未知。三倍体鲫鱼（3n=150）由红鲫（雌性，2n=100）和异源四倍体（雄性，4n=200）组成，表现出更好的抗病原感染能力。为了阐明三倍体鲫鱼的抗菌机制，我们研究了三倍体鲫鱼（3nLcn2）的一种新型 Lcn2 的功能。3nLcn2 长 183 个残基，含有保守的脂联素结构域。实时定量 RT-PCR（qRT-PCR）分析显示，3nLcn2 在多种组织中表达，并在细菌感染时呈时间依赖性上调。我们发现纯化的重组 3nLcn2（r3nLcn2）对嗜水气单胞菌和大肠杆菌具有杀菌活性。qRT-PCR 检测到过表达 3nLcn2 的鱼类促炎细胞因子和紧密连接的表达增加。给予 3nLcn2 的鱼类表现出增强的肠道屏障和对细菌感染的抵抗力。这些结果首次证明 3nLcn2 是一种具有抗菌活性的功能性脂联素，在细菌感染期间的免疫防御中发挥积极作用。
