The RNA-seq analysis suggests a potential multi-component complement system in oyster Crassostrea gigas

• Published in: Developmental & Comparative Immunology
• Main Authors: Wang, Lingling, Zhang, Huan, Wang, Leilei, Zhang, Daoxiang, Lv, Zhao, Liu, Zhaoqun, Wang, Weilin, Zhou, Zhi, Qiu, Limei, Wang, Hao, Li, Jun, Song, Linsheng
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: Crassostrea Gigas; Complement Related Prrs; Serine Protease Domain-containing Proteins; C3; C3 Receptor-like Proteins; Crassostrea gigas
• Online Access: http://ir.qdio.ac.cn/handle/337002/143083; https://doi.org/10.1016/j.dci.2017.06.009

The complement system is one of the major effector mechanisms of immune system, playing essential roles in both the innate and adaptive immune responses. In the present study, the counterparts of vertebrate complement components were identified by screening the sequenced genome of Crassostrea gigas, resulting in the identification of 792 gene models containing complement-related domains. The transcriptome of haemocytes at 6, 12 and 24 h post lipopolysaccharides (LPS) stimulation showed differential expression of 77 Clq domain containing proteins, 53 C-type lectins and 42 fibrinogen-related proteins. mRNAs encoding 18 serine protease domain-containing (SPC) proteins, 4 MACPF-domain containing proteins and 11 C3 receptor-like proteins were up-regulated upon LPS stimulation, and CgC3 mRNA was significantly increased at 12 h. The presence of CgC3 was confirmed in cell free plasma and was present in three subunit chains as expected for the processed mature protein. The complement related PRRs with coiled coil regions and SPC proteins with CUB domains may function in the activation of CgC3, whereas, the C3-like receptors with integrin-alpha/beta domain mediated the phagocytosis of C3-labled pathogens. These PRRs appear to serve as opsonins to promote phagocytosis of opsonized pathogens. The overall results suggested the existence of a potential multi-component complement system in C gigas. (C) 2017 Elsevier Ltd. All rights reserved.