A galectin-9 involved in the microbial recognition and haemocyte autophagy in the Pacific oyster Crassostrea gigas

Qian Yang; Jiejie Sun; Wei Wu; Zhen Xing; Xiaoxue Yan; Xiaoqian Lv; Lingling Wang; Linsheng Song

doi:10.1016/j.dci.2023.105063

A galectin-9 involved in the microbial recognition and haemocyte autophagy in the Pacific oyster Crassostrea gigas

Dev Comp Immunol. 2023 Dec:149:105063. doi: 10.1016/j.dci.2023.105063. Epub 2023 Sep 18.

Authors

Qian Yang¹, Jiejie Sun¹, Wei Wu¹, Zhen Xing¹, Xiaoxue Yan¹, Xiaoqian Lv¹, Lingling Wang², Linsheng Song³

Affiliations

¹ Liaoning Key Laboratory of Marine Animal Immunology & Disease Control, Dalian Ocean University, Dalian, 116023, China; Laboratory of Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266235, China; Liaoning Key Laboratory of Marine Animal Immunology, Dalian Ocean University, Dalian, 116023, China.
² Liaoning Key Laboratory of Marine Animal Immunology & Disease Control, Dalian Ocean University, Dalian, 116023, China; Southern Laboratory of Ocean Science and Engineering (Guangdong, Zhuhai), Zhuhai, 519000, China; Laboratory of Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266235, China; Liaoning Key Laboratory of Marine Animal Immunology, Dalian Ocean University, Dalian, 116023, China; Dalian Key Laboratory of Prevention and Control of Aquatic Animal Diseases, Dalian Ocean University, Dalian, 116023, China. Electronic address: wanglingling@dlou.edu.cn.
³ Liaoning Key Laboratory of Marine Animal Immunology & Disease Control, Dalian Ocean University, Dalian, 116023, China; Southern Laboratory of Ocean Science and Engineering (Guangdong, Zhuhai), Zhuhai, 519000, China; Laboratory of Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266235, China; Liaoning Key Laboratory of Marine Animal Immunology, Dalian Ocean University, Dalian, 116023, China; Dalian Key Laboratory of Prevention and Control of Aquatic Animal Diseases, Dalian Ocean University, Dalian, 116023, China.

PMID: 37730190
DOI: 10.1016/j.dci.2023.105063

Abstract

Galectin-9 is a tandem-repeat type member of galectin family participating in various immune responses, such as cell agglutination, phagocytosis, and autophagy. In the present study, a tandem repeat galectin-9 (defined as CgGal-9) was identified from Pacific oyster Crassostrea gigas, which consisted of two conserved carbohydrate recognition domains (CRDs) joined by a linker peptide. CgGal-9 was closely clustered with CaGal-9 from C. angulata, and they were assigned into the branch of invertebrate galectin-9s in the phylogenetic tree. The mRNA transcripts of CgGal-9 were detected in all the tested tissues, with the highest expression level in haemocytes. The mRNA expressions of CgGal-9 in haemocytes increased significantly after lipopolysaccharide (LPS) and Vibrio splendidus stimulation. The recombinant CgGal-9 was able to bind all the examined pathogen-associated molecular patterns (LPS, peptidoglycan, and mannose) and microbes (V. splendidus, Escherichia coli, Micrococcus luteus, Staphylococcus aureus, Bacillus subtilis, and Pichia pastoris), and agglutinated most of them in the presence of Ca²⁺. In CgGal-9-RNAi oysters, the mRNA expressions of autophagy related genes (CgBeclin1, CgATG5, CgP62 and CgLC3) in haemocytes decreased significantly while that of CgmTOR increased significantly at 3 h after V. splendidus stimulation. The autophagy level and mRNA expressions of autophagy related genes decreased in haemocytes after CgGal-9 was blocked by the corresponding antibody. These results revealed that CgGal-9 was able to bind different microbes and might be involved in haemocyte autophagy in the immune response of oyster.

Keywords: Agglutination; Crassostrea gigas; Galectin-9; PAMP binding.