The Key Laboratory of Zoological Systematics and Application, College of Life Sciences, Hebei University, Baoding, Hebei, 071002, China.
The Key Laboratory of Zoological Systematics and Application, College of Life Sciences, Hebei University, Baoding, Hebei, 071002, China.
Fish Shellfish Immunol. 2020 May;100:272-282. doi: 10.1016/j.fsi.2020.02.066. Epub 2020 Mar 3.
Fibrinogen-related proteins (FREPs) are widely found in both vertebrates as well as invertebrates, and they play a crucial role in host immunity. In this study, we isolated a novel ficolin gene (Mnfico3) from the oriental river prawn Macrobrachium nipponense. The complete cDNA sequence of Mnfico3 was 1133 bp long, containing an open reading frame of 765 bp coding for Mnfico3, a protein consisting of 254 amino acids. The Mnfico3 protein contained a putative N-terminal signal peptide and a fibrinogen-related protein domain present at the C-terminal. Phylogenetic analysis indicated that Mnfico3 had a closer evolutionary relationship with vertebrate ficolins than with its invertebrate homologues. Tissue distribution analysis indicated that Mnfico3 was predominantly expressed in muscle, in which its transcription was increased following bacterial challenge by Aeromonas veronii. Function analysis using recombinant protein revealed that rMnFico3 had broad-spectrum binding capacity to a variety of microorganisms and pathogen-associated molecular pattern (PAMP) ligands. Furthermore, rMnFico3 exhibited Ca-dependent agglutinating activity against microbes in vitro, and ability to attach to the hemocyte surface which promoted phagocytosis and subsequent clearance of invasive bacteria in vivo. Silencing rMnFico3 in prawn through RNAi did not alter the expression of antimicrobial peptide genes (ALF and Crustin). These results manifested that MnFico3 functioned as a potential pattern recognition receptor (PPR) to mediate cellular immune response by recognizing PAMPs, agglutinating invasive microbes, and promoting phagocytosis of hemocytes.
纤维蛋白原相关蛋白（FREPs）广泛存在于脊椎动物和无脊椎动物中，它们在宿主免疫中起着至关重要的作用。在这项研究中，我们从日本沼虾 Macrobrachium nipponense 中分离出一种新型的 ficolin 基因（Mnfico3）。Mnfico3 的完整 cDNA 序列长 1133bp，包含一个 765bp 的开放阅读框，编码 Mnfico3 蛋白，由 254 个氨基酸组成。Mnfico3 蛋白含有一个假定的 N 端信号肽和一个位于 C 端的纤维蛋白原相关蛋白结构域。系统进化分析表明，Mnfico3 与脊椎动物 ficolin 的进化关系比与无脊椎动物同源物更密切。组织分布分析表明，Mnfico3 在肌肉中表达丰度最高，在受到气单胞菌 Aeromonas veronii 细菌挑战后，其转录水平增加。使用重组蛋白进行的功能分析表明，rMnFico3 具有广谱结合多种微生物和病原体相关分子模式（PAMP）配体的能力。此外，rMnFico3 在体外对微生物具有 Ca 依赖性的凝集活性，并能附着在血细胞表面，促进体内入侵细菌的吞噬和清除。通过 RNAi 沉默对虾中的 rMnFico3 不会改变抗菌肽基因（ALF 和 Crustin）的表达。这些结果表明，MnFico3 作为一种潜在的模式识别受体（PPR），通过识别 PAMPs、凝集入侵微生物和促进血细胞的吞噬作用，介导细胞免疫反应。
