The Acute-Phase Serum Amyloid A Promotes Cytokines Production in Oyster <i>Crassostrea gigas</i>
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 as a marker of disease diagnosis. By comparison, SAA is rarely identified in aquatic species and its physical fu...
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| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-02-01
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| Series: | Fishes |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2410-3888/10/3/93 |
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| Summary: | 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 as a 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 <i>Crassostrea gigas</i>. The open reading frame (ORF) of <i>Cg</i>SAA was of 417 bp, encoding a putative polypeptide of 138 amino acid residues with a predicted molecular weight of 15.66 kDa. <i>Cg</i>SAA was composed of a signal peptide (residues 1–22) and a conserved SAA domain (residues 36–138). The mRNA expression of <i>Cg</i>SAA in normal individuals was detectable but at a low level, with the lowest expression level in the tissue of labial palp and a slightly higher expression level in hemocytes. The mRNA expression level of <i>Cg</i>SAA was significantly up-regulated at 6 h (2.76-fold of that in control group, <i>p</i> < 0.01) post <i>V. splendidus</i> stimulation. It was also significantly induced under environmental stress at high temperature (34 °C) or low salinity (15‰ salinity). The recombinant protein r<i>Cg</i>SAA was expressed in <i>Escherichia coli</i> and purified by affinity chromatography. After r<i>Cg</i>SAA was injected into oysters or incubated with culture primary hemocytes, the mRNA expressions of the cytokines <i>Cg</i>IL17-1, <i>Cg</i>IL17-5, and <i>Cg</i>TNF were all significantly up-regulated. The results collectively suggested that <i>Cg</i>SAA, as a conserved acute-phase response protein in oyster, was quickly induced under environmental stress and promoted the expressions of cytokines, which provide fresh ideas for understanding the roles of SAA proteins in aquatic invertebrates. |
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| ISSN: | 2410-3888 |