A C1qDC (CgC1qDC-6) with a collagen-like domain mediates hemocyte phagocytosis and migration in oysters. (September 2019)

• Record Type: Journal Article
• Authors: Li, Huan; Kong, Ning; Sun, Jiejie; Wang, Weilin; Li, Meijia; Gong, Changhao; Dong, Miren; Wang, Min; Wang, Lingling; Song, Linsheng
• Is Part Of: Developmental and comparative immunology. Volume 98(2019)
• Page Start: 157
• Page End: 165
• Publication Date: 2019-09
• Subjects: Crassostrea gigas -- C1qDC -- Collagen-like domain -- Pattern recognition receptor -- Opsonization -- Chemotaxis; Immunology -- Periodicals; Developmental immunology -- Periodicals; 616.079
• DOI: 10.1016/j.dci.2019.04.010
• Languages: English
• ISSNs: 0145-305X

Abstract

Abstract: Most of the bivalve C1q domain containing proteins (C1qDCs) are either only composed of the globular head domain, or contain an N-terminal coiled-coil domain, presumed to cover a role in oligomerization. On the other hand, collagen regions, widespread in vertebrate C1qDCs, are very uncommon in bivalves. In the present study, a C1qDC with a collagen-like domain (designated Cg C1qDC-6) was identified from the Pacific oyster Crassostrea gigas and its possible involvement in immune responses was also characterized. The coding sequence of Cg C1qDC-6 was of 756 bp, encoding a peptide of 251 amino acids with an N-terminal signal peptide, a central collagen-like domain, and a C-terminal ghC1q domain. Cg C1qDC-6 was clustered with the C1qDCs from several mollusks in the phylogenetic tree. Cg C1qDC-6 was detected at both mRNA and protein levels in all tested tissues including hepatopancreas, gonad, gill, mantle, adductor muscle, and hemocytes. The recombinant Cg C1qDC-6 protein (r Cg C1qDC-6) exhibited binding activity to various pathogen-associated molecular patterns (PAMPs) including LPS, PGN, mannose and Poly I:C, and microorganisms including Gram-negative bacteria ( Escherichia coli and Vibrio splendidus ), Gram-positive bacteria ( Micrococcus luteus and Staphylococcus aureus ), and fungus ( Pichia pastoris ). The phagocytic rates of oyster hemocytes towards V . splendidus pre-incubation with r Cg C1qDC-6 were significantly enhanced ( p < 0.05). In the chemotaxis assay, r Cg C1qDC-6 could mediate the migration of oyster hemocytes in a dose-dependent manner, which exhibited a positive chemotactic effect at low concentration (<10 nM). These results collectively indicated that Cg C1qDC-6 could serve as a pattern recognition receptor and mediate the hemocyte phagocytosis and migration to eliminate the invading pathogens. Highlights: Cg C1qDC-6 was the only one C1qDC with a collagen-like domain identified in Pacific oyster. Cg C1qDC-6 distributed in various oyster tissues, and can recognize and bind broadly PAMPs and microorganisms. Cg C1qDC-6 displayed chemotactic activity on oyster hemocytes. The phagocytic rate of hemocytes was enhanced after the bacteria was pre-incubated with Cg C1qDC-6.