A novel LRR and Ig domain-containing protein could function as an immune effector in Crassostrea gigas

Xiudan Wang; Xiaoli Zhao; Chunyu Yan; Zhihao Jia; Zhao Lv; Cuiping Ma; Mengqiang Wang

doi:10.1016/j.fsi.2019.03.003

A novel LRR and Ig domain-containing protein could function as an immune effector in Crassostrea gigas

Fish Shellfish Immunol. 2019 May:88:318-327. doi: 10.1016/j.fsi.2019.03.003. Epub 2019 Mar 7.

Authors

Xiudan Wang¹, Xiaoli Zhao¹, Chunyu Yan¹, Zhihao Jia², Zhao Lv³, Cuiping Ma¹, Mengqiang Wang⁴

Affiliations

¹ Shandong Provincial Key Laboratory of Biochemical Engineering, College of Marine Science and Biological Engineering, Qingdao University of Science and Technology, Qingdao, 266042, China.
² 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.
³ CAS 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.
⁴ CAS Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, 266071, China; Research Platform for Marine Molecular Biotechnology, National Laboratory for Marine Science and Technology, Qingdao, 266237, China; Laboratory for Marine Biology and Biotechnology, National Laboratory for Marine Science and Technology, Qingdao, 266237, China; CAS Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, 266400, China. Electronic address: wangmengqiang@qdio.ac.cn.

PMID: 30853654
DOI: 10.1016/j.fsi.2019.03.003

Abstract

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.

Keywords: Crassostrea gigas; Immune effector; Immunoglobulin domain; LRRIG; Leucine-rich repeat domain; Pattern recognition receptor.

MeSH terms

Amino Acid Sequence
Animals
Cells, Cultured
Crassostrea / genetics*
Crassostrea / immunology*
Hemocytes / metabolism
Immunity, Innate*
Immunoglobulin Domains
Pathogen-Associated Molecular Pattern Molecules / pharmacology
Phylogeny
Protein Domains
Receptors, Pattern Recognition / chemistry
Receptors, Pattern Recognition / genetics*
Receptors, Pattern Recognition / immunology*
Sequence Alignment

Substances

Pathogen-Associated Molecular Pattern Molecules
Receptors, Pattern Recognition