Shandong Provincial Key Laboratory of Restoration for Marine Ecology, Shandong Marine Fisheries Research Institute, Yantai 264006, China.
Fish Shellfish Immunol. 2012 Aug;33(2):204-12. doi: 10.1016/j.fsi.2012.04.012. Epub 2012 Apr 28.
C-type lectin and galectin are two types of animal carbohydrate-binding proteins which serve as pathogen recognition molecules and play crucial roles in the innate immunity of invertebrates. In the present study, a C-type lectin (designated as SgCTL-1) and galectin (designated as SgGal-1) were identified from mollusk Solen grandis, and their expression patterns, both in tissues and toward three pathogen-associated molecular patterns (PAMPs) stimulation were characterized. The full-length cDNA of SgCTL-1 and SgGal-1 was 1280 and 1466 bp, containing an open reading frame (ORF) of 519 and 1218 bp, respectively. Their deduced amino acid sequences showed high similarity to other members of C-type lectin and galectin superfamily, respectively. SgCTL-1 encoded a single carbohydrate-recognition domain (CRD), and the motif of Ca(2+)-binding site 2 was EPN (Glu(135)-Pro(136)-Asn(137)). While SgGal-1 encoded two CRDs, and the amino acid residues constituted the carbohydrate-binding motifs were well conserved in CRD1 but partially conserved in CRD2. Although SgCTL-1 and SgGal-1 exhibited different tissue expression pattern, they were both constitutively expressed in all tested tissues, including hemocytes, gonad, mantle, muscle, gill and hepatopancreas, and they were both highly expressed in hepatopancreas and gill. Furthermore, the mRNA expression of two lectins in hemocytes was significantly (P < 0.01) up-regulated with different levels after S. grandis were stimulated by lipopolysaccharide (LPS), peptidoglycan (PGN) or β-1,3-glucan. Our results suggested that SgCTL-1 and SgGal-1 from razor clam were two novel members of animal lectins, and they might function as pattern recognition receptors (PRRs) taking part in the process of pathogen recognition.
C 型凝集素和半乳糖凝集素是两种动物碳水化合物结合蛋白，作为病原体识别分子，在无脊椎动物的先天免疫中发挥着关键作用。本研究从软体动物长牡蛎中鉴定出一种 C 型凝集素（命名为 SgCTL-1）和半乳糖凝集素（命名为 SgGal-1），并对其在组织中的表达模式以及对三种病原体相关分子模式（PAMPs）刺激的反应进行了表征。SgCTL-1 和 SgGal-1 的全长 cDNA 分别为 1280 和 1466bp，包含 519 和 1218bp 的开放阅读框（ORF）。它们的推导氨基酸序列与其他 C 型凝集素和半乳糖凝集素超家族的成员具有高度相似性。SgCTL-1 编码一个单一的碳水化合物识别结构域（CRD），并且 Ca(2+)结合位点 2 的基序为 EPN（Glu(135)-Pro(136)-Asn(137)）。而 SgGal-1 编码两个 CRD，并且构成碳水化合物结合基序的氨基酸残基在 CRD1 中高度保守，但在 CRD2 中部分保守。尽管 SgCTL-1 和 SgGal-1 表现出不同的组织表达模式，但它们在所有测试的组织中均呈组成型表达，包括血细胞、性腺、套膜、肌肉、鳃和肝胰腺，并且在肝胰腺和鳃中表达水平较高。此外，当长牡蛎受到脂多糖（LPS）、肽聚糖（PGN）或β-1,3-葡聚糖刺激时，血细胞中两种凝集素的 mRNA 表达均显著（P<0.01）上调。本研究结果表明，来自长牡蛎的 SgCTL-1 和 SgGal-1 是动物凝集素的两个新成员，它们可能作为模式识别受体（PRRs）参与病原体识别过程。
