Characterization and functional analysis of a novel gC1qR in the swimming crab Portunus trituberculatus. Issue 84 (January 2019)

• Record Type: Journal Article
• Authors: Ning, Junhao; Liu, Yuan; Gao, Fengtao; Liu, Hourong; Cui, Zhaoxia
• Is Part Of: Fish & shellfish immunology. Issue 84(2019)
• Page Start: 970
• Page End: 978
• Publication Date: 2019-01
• Subjects: Portunus trituberculatus -- gC1qR -- Expression profiles -- Antimicrobial activity -- Microbial binding activity -- Prophenoloxidase activating system; Fishes -- Immunology -- Periodicals; Shellfish -- Immunology -- Periodicals; Poissons -- Immunologie -- Périodiques; Crustacés -- Immunologie -- Périodiques; 571.9617
• DOI: 10.1016/j.fsi.2018.11.005
• Languages: English
• ISSNs: 1050-4648

Abstract

Abstract: The receptor for the globular head of complement component C1q, gC1qR, is a multifunctional and multiligand binding protein with a crucial role in host defense. In the present study, a full-length cDNA sequence of a gC1qR homolog (PtgC1qR) in Portunus trituberculatus was identified. PtgC1qR was a 268-amino-acid polypeptide with a conserved MAM33 domain and a mitochondrial targeting sequence in the first 56 amino acids. The transcripts of PtgC1qR were detected in all examined tissues with the highest level detected in the hepatopancreas. Compared with other early embryonic stages, PtgC1qR was highly expressed in the fertilized eggs and embryos at the cleavage stage, which suggest PtgC1qR may be a maternal gene. The transcripts of PtgC1qR in hemocytes exhibited time-dependent response expression pattern after challenged with bacteria ( Vibrio alginolyticus, Micrococcus luteus ) and fungi ( Pichia pastoris ). Moreover, the recombinant PtgC1qR (rPtgC1qR) exhibited strong antibacterial activity and microbial-binding activity, suggesting its crucial role in immune defense and recognition. Further phenoloxidase (PO) assay showed that rPtgC1qR could suppress the crab PO activity in vitro in a dose-dependent manner, and it could result in nearly 100% inhibition of PO activity under the concentration of 11.65 μM. Knockdown of PtgC1qR could significantly enhance the expression of serine protease related genes ( PtSP1 - 3 and PtSPH ), proPO-associated genes ( PtproPO and PtPPAF ) and C3-like genes (Ptα2M1 and PtTEP ). However, the phagocytosis related genes ( PtMyosin, PtRab5 and PtArp ) and Ptα2M2 were significantly down-regulated in the PtgC1qR silenced crabs. These findings together demonstrate that PtgC1qR might function in crab immune response via its antibacterial activity, immune recognition or regulating the proPO system, complement pathway and phagocytosis. Highlights: A gC1qR homolog was isolated from Portunus trituberculatus. PtgC1qR expression was induced by bacteria or fungi. PtgC1qR exhibited antibacterial activity and microbial binding activity. PtgC1qR suppressed the crab PO activity in vitro. PtgC1qR regulates the expression of phagocytosis related and C3-like genes.