Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Fish Shellfish Immunol. 2014 Feb;36(2):336-43. doi: 10.1016/j.fsi.2013.11.017. Epub 2013 Dec 15.
Low-density lipoprotein receptor-related protein (LRP) is a group of important endocytic receptors contributing to binding ligands and maintaining internal environment. In the present study, an LRP-like molecule was identified from Zhikong scallop Chlamys farreri (CfLPR), and its mRNA expression profiles, tissue location, and immunology activities were analyzed to explore its possible function in the innate immune system. The ORF of CfLRP was of 1971 bp encoding a polypeptide of 656 amino acids with ten low-density lipoprotein-receptor YWTD (LY) domains and one scavenger receptor cysteine-rich (SRCR) domain. It shared similar structure with out-membrane domains of LRP family members in mammalian. The mRNA transcripts of CfLRP were dominantly expressed in hepatopancreas and mantle (P < 0.01), and its mRNA level in hemocytes was up-regulated (P < 0.01) significantly after the stimulations of lipopolysaccharides (LPS), peptidoglycan (PGN) and β-glucan. Western blotting assay using polyclonal antibody specific for CfLRP revealed that CfLRP was localized in the plasma. The recombinant protein of CfLRP (rCfLRP) could bind acetylated low density lipoprotein (Ac-LDL), metalloprotease SPF1 of Vibrio splendidus and mannan, but could not bind other typical PAMPs such as LPS, PGN, β-glucan and zymosan. Meanwhile, rCfLRP also exhibited strong bacteriostatic activity to Gram-negative bacteria Vibrio anguillarum and V. splendidus. These results indicated that CfLRP could serve as a receptor to recognize and eliminate the invading pathogens, which provided a new implication in the function of LRP-like molecules in invertebrate immunity.
低密度脂蛋白受体相关蛋白（LRP）是一组重要的内吞受体，有助于结合配体并维持内环境。本研究从栉孔扇贝（Chlamys farreri）中鉴定出一种 LRP 样分子（CfLPR），并分析其 mRNA 表达谱、组织定位和免疫学活性，以探讨其在先天免疫系统中的可能功能。CfLRP 的 ORF 为 1971bp，编码一个 656 个氨基酸的多肽，具有十个低密度脂蛋白受体 YWTD（LY）结构域和一个清道夫受体富含半胱氨酸（SRCR）结构域。它与哺乳动物 LRP 家族成员的外膜结构域具有相似的结构。CfLRP 的 mRNA 转录本主要在肝胰腺和套膜（P<0.01）中表达，其在血细胞中的 mRNA 水平在受到脂多糖（LPS）、肽聚糖（PGN）和β-葡聚糖刺激后显著上调（P<0.01）。使用针对 CfLRP 的多克隆抗体进行的 Western blot 分析表明 CfLRP 定位于血浆中。CfLRP 的重组蛋白（rCfLRP）可以结合乙酰化低密度脂蛋白（Ac-LDL）、灿烂弧菌的金属蛋白酶 SPF1 和甘露聚糖，但不能结合其他典型的 PAMP，如 LPS、PGN、β-葡聚糖和酵母聚糖。同时，rCfLRP 对革兰氏阴性菌鳗弧菌和灿烂弧菌也表现出强烈的抑菌活性。这些结果表明 CfLRP 可以作为识别和清除入侵病原体的受体，这为 LRP 样分子在无脊椎动物免疫中的功能提供了新的启示。
