School of Marine Sciences, Ningbo University, Ningbo, 315211, China.
Liaoning Key Laboratory of Marine Animal Immunology, Dalian Ocean University, Dalian, 116023, China; Liaoning Key Laboratory of Marine Animal Immunology & Disease Control, Dalian Ocean University, Dalian, 116023, China; Dalian Key Laboratory of Aquatic Animal Disease Prevention and Control, Dalian Ocean University, Dalian, 116023, China.
Fish Shellfish Immunol. 2020 Apr;99:167-175. doi: 10.1016/j.fsi.2020.02.011. Epub 2020 Feb 7.
Galectins belong to the family of carbohydrate-binding proteins and play major roles in the immune and inflammatory responses of both vertebrates and invertebrates. In the present study, one novel galectin-1 protein named AjGal-1 was identified from Apostichopus japonicas with an open reading frame of 1179 bp encoding a polypeptide of 392 amino acids. The deduced amino acids sequence of AjGal-1 contained three carbohydrate recognition domains (CRDs) which shared 34-37% identity with that of other galectin proteins from echinodermata, fishes, and birds. In the phylogenetic tree, AjGal-1 was closely clustered with galectins from Mesocentrotus nudus and Paracentrotus lividus. The mRNA transcripts of AjGal-1 were ubiquitously expressed in all the detected tissues, including gut, longitudinal muscle, gonad, coelomocytes, respiratory tree, tentacle and body wall, with the highest expression level in coelomocytes. After Vibrio splendidus stimulation, the mRNA expression levels of AjGal-1 in coelomocytes were significantly increased at 6 and 12 h (P < 0.01) compared with that in control group, and went back to normal level at 72 h. The recombinant protein of AjGal-1 (rAjGal-1) could bind various PAMPs including d-galactose, lipopolysaccharide (LPS), peptidoglycan (PGN) and mannose (Man), and exhibited the highest affinity to d-galactose. Meanwhile, rAjGal-1 could also bind and agglutinate different kinds of microorganisms, including gram-negative bacteria (V. splendidus and Escherichia coli), gram-positive bacteria (Micrococus leteus), and fungi (Pichia pastoris). rAjGal-1 also exhibited anti-microbial activity against V. splendidus and E. coli. All these results suggested that AjGal-1 could function as an important PRR with broad spectrum of microbial recognition and anti-microbial activity against the invading pathogen in A. japonicas.
半乳糖凝集素属于糖结合蛋白家族，在脊椎动物和无脊椎动物的免疫和炎症反应中发挥重要作用。本研究从刺参中鉴定出一种新型半乳糖凝集素-1 蛋白，命名为 AjGal-1，其开放阅读框为 1179bp，编码 392 个氨基酸的多肽。AjGal-1 的推导氨基酸序列包含三个糖识别结构域（CRD），与棘皮动物、鱼类和鸟类的其他半乳糖蛋白具有 34-37%的同源性。在系统进化树中，AjGal-1 与Mesocentrotus nudus 和 Paracentrotus lividus 的半乳糖凝集素紧密聚类。AjGal-1 的 mRNA 转录本在所有检测组织中均广泛表达，包括肠道、纵向肌肉、性腺、体腔细胞、呼吸树、触手和体壁，在体腔细胞中的表达水平最高。在灿烂弧菌刺激后，与对照组相比，体腔细胞中 AjGal-1 的 mRNA 表达水平在 6 和 12 h 时显著增加（P < 0.01），并在 72 h 时恢复正常水平。AjGal-1 的重组蛋白（rAjGal-1）可结合各种 PAMP，包括 d-半乳糖、脂多糖（LPS）、肽聚糖（PGN）和甘露糖（Man），并与 d-半乳糖具有最高的亲和力。同时，rAjGal-1 还可以结合和凝集不同种类的微生物，包括革兰氏阴性菌（灿烂弧菌和大肠杆菌）、革兰氏阳性菌（Micrococus leteus）和真菌（毕赤酵母）。rAjGal-1 对灿烂弧菌和大肠杆菌也表现出抗菌活性。这些结果表明，AjGal-1 可以作为一种重要的 PRR，具有广泛的微生物识别谱和对刺参入侵病原体的抗菌活性。
