Work

The Acute-Phase Serum Amyloid A Promotes Cytokines Production in Oyster Crassostrea gigas

Year: 2025

Type: article

Abstract: Serum amyloid A (SAA) is one of the most abundant acute phase response proteins and has been extensively studied in vertebrates for its role in modulation of the inflammatory response and marker of disease diagnosis. By comparison, SAA is rarely identified in aquatic species and its physical functions are also not well studied. The present study identified the only one gene encoding SAA protein in oyster Crassostrea gigas. The open reading frame (ORF) of CgSAA was of 417 bp, encoding a putative polypeptide of 138 amino acid residues with predicted molecular weight of 15.66 kDa. CgSAA was composed of a signal peptide (residues 1-22) and a conserved SAA domain (residues 36-138). The mRNA expression of CgSAA in normal individuals was detectable but in low level, with the lowest expression level in tissue of labial palp and slightly higher expression level in haemocytes. The mRNA expression level of CgSAA was significantly up-regulated at 6 h (2.76-fold of that in control group, p < 0.01) post V. splendidus stimulation. It was also significantly induced under environmental stress of high temperature (34 ℃) or low permeability (15‰ salinity). The recombinant protein rCgSAA was expressed in Escherichia coli and purified by affinity chromatography. After rCgSAA was injected into oysters or incubated with culture primary haemocytes, the mRNA expressions of cytokine CgIL17-1, CgIL17-5 and CgTNF were all significantly un-regulated. The results collectively suggested that CgSAA, as a conserved acute phase response protein in oyster, was quickly induced under environmental stress and promoted the expressions of cytokines, which provided fresh ideas for understanding the roles of SAA proteins in aquatic invertebrates.

Source: Fishes

DOI: 10.3390/fishes10030093