Phylogeny and expression analysis of C-reactive protein (CRP) and serum amyloid-P (SAP) like genes reveal two distinct groups in fish.
The acute phase response (APR) is an early innate immune function that is initiated by inflammatory signals, leading to the release of acute phase proteins to the bloodstream to re-establish homeostasis following microbial infection. In this study we analysed the Atlantic salmon (Salmo salar) whole-genome database and identified five C-reactive protein (CRP)/serum amyloid P component (SAP) like molecules namely CRP/SAP-1a, CRP/SAP-1b, CRP/SAP-1c, CRP/SAP-2 and CRP/SAP-3. These CRP/SAP genes formed two distinct sub-families, a universal group (group I) present in all vertebrates and a fish/amphibian specific group (group II). Salmon CRP/SAP-1a, CRP/SAP-1b and CRP/SAP-1c and CRP/SAP-2 belong to the group I family whilst salmon CRP/SAP-3 is a member of group II. Gene expression analysis showed that the salmon CRP/SAP-1a as well as serum amyloid A-5 (SAA-5), one of the major acute phase proteins, were significantly up-regulated by recombinant cytokines (rIL-1β and rIFNγ) in primary head kidney cells whilst the other four CRP/SAPs remained refractory. Furthermore, SAA-5 was produced as the main acute phase protein (APP) in Atlantic salmon challenged with Aeromonas salmonicida (aroA(-) strain) whilst salmon CRP/SAPs remained unaltered. Overall, these data illustrate the potential different functions of expanded salmon CRP/SAPs to their mammalian homologues.
Scottish Fish Immunology Research Centre, Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK.
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Lee
Science & Engineering, University of Waikato, Private Bag 3105, Hamilton 3240, New Zealand.
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Bird
Scottish Fish Immunology Research Centre, Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK.
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Zou
Scottish Fish Immunology Research Centre, Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK. Electronic address: sam.martin@abdn.ac.uk.
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Martin
D048409:Aeromonas salmonicida / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D002097:C-Reactive Protein / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D005260:Female; D005393:Fish Diseases / Q000235:genetics* / Q000276:immunology / Q000382:microbiology; D029941:Fish Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D016905:Gram-Negative Bacterial Infections / Q000235:genetics / Q000276:immunology / Q000382:microbiology / Q000662:veterinary*; D008297:Male; D010802:Phylogeny; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D020317:Salmo salar; D016415:Sequence Alignment / Q000662:veterinary; D000683:Serum Amyloid P-Component / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
D018076:DNA, Complementary; D029941:Fish Proteins; D000683:Serum Amyloid P-Component; D002097:C-Reactive Protein
Acute phase protein; Atlantic salmon; C-reactive protein; Gene expression; Innate immunity; Serum amyloid-P