Shandong Provincial Key Laboratory of Biochemical Engineering, College of Marine Science and Biological Engineering, Qingdao University of Science and Technology, Qingdao, 266042, China.
CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Department of Animal Sciences, Purdue University, IN, 47907, USA.
Fish Shellfish Immunol. 2019 May;88:318-327. doi: 10.1016/j.fsi.2019.03.003. Epub 2019 Mar 7.
A variety of combinations of leucine-rich repeat (LRR) and immunoglobulin-like (Ig) domains have been found and discovered in invertebrates and vertebrates, but the functions remain largely unexplored. In the present study, a novel LRR and Ig domain-containing protein (LRRIG), CgLRRIG-3, was identified and characterized from oyster Crassostrea gigas. It contained two typical LRR motifs, a LRRNT motif and an Ig domain and PSI-BALST and phylogeny analysis revealed that the sequence of CgLRRIG-3 was most related with leucine-rich repeat neuronal 1 proteins from vertebrate. Its mRNA transcripts were constitutively expressed in muscle, gill, hepatopancreas, mantle, gonad and hemocytes with the highest level in hepatopancreas. The mRNA expression level of CgLRRIG-3 in hemocytes could respond to the stimulations of variety PAMPs including lipopolysaccharide (LPS), peptidoglycan (PGN), glucan (GLU) and polyinosinic-polycytidylic acid (poly I:C). The recombinant proteins exhibited a wide PAMP binding repertoire to four typical PAMPs and could significantly induce the expression of CgTNF-1 and CgIL17-5 as well as increase phagocytosis in primary cultured oyster hemocytes. In hepatopancreas, CgLRRIG-3 was mainly distributed in the basolateral membrane of digestive tubule and the hemocoel sinusoid between the digestive tubules. And in hemocytes, the positive signal was mainly distributed in a special group of granulocytes. These results collectively indicated that CgLRRIG-3 could not only function as an immune effector.
在无脊椎动物和脊椎动物中发现并发现了各种富含亮氨酸重复（LRR）和免疫球蛋白样（Ig）结构域的组合，但功能仍在很大程度上未被探索。在本研究中，从牡蛎（Crassostrea gigas）中鉴定并表征了一种新型的富含亮氨酸重复和 Ig 结构域的蛋白（LRRIG），即 CgLRRIG-3。它包含两个典型的 LRR 基序，一个 LRRNT 基序和一个 Ig 结构域，PSI-BALST 和系统发育分析表明，CgLRRIG-3 的序列与脊椎动物的富含亮氨酸重复神经元 1 蛋白最为相关。其 mRNA 转录本在肌肉，鳃，肝胰腺，套膜，性腺和血细胞中组成型表达，在肝胰腺中表达水平最高。血细胞中 CgLRRIG-3 的 mRNA 表达水平可对各种 PAMP 的刺激做出反应，包括脂多糖（LPS），肽聚糖（PGN），葡聚糖（GLU）和聚肌苷酸-聚胞苷酸（poly I：C）。重组蛋白表现出对四种典型 PAMP 的广泛 PAMP 结合谱，可显着诱导原代培养牡蛎血细胞中 CgTNF-1 和 CgIL17-5 的表达，并增加吞噬作用。在肝胰腺中，CgLRRIG-3 主要分布在消化管的基底外侧膜和消化管之间的血腔窦。在血细胞中，阳性信号主要分布在一组特殊的粒细胞中。这些结果共同表明，CgLRRIG-3 不仅可以作为免疫效应子发挥作用。
