Two types of TNF-α exist in teleost fish: phylogeny, expression, and bioactivity analysis of type-II TNF-α3 in rainbow trout Oncorhynchus mykiss.
TNF-α is a cytokine involved in systemic inflammation and regulation of immune cells. It is produced chiefly by activated macrophages as a membrane or secreted form. In rainbow trout, two TNF-α molecules were described previously. In this article, we report a third TNF-α (TNF-α3) that has only low identities to known trout molecules. Phylogenetic tree and synteny analyses of trout and other fish species suggest that two types (named I and II) of TNF-α exist in teleost fish. The fish type-II TNF-α has a short stalk that may impact on its enzymatic release or restrict it to a membrane-bound form. The constitutive expression of trout TNF-α3 was generally lower than the other two genes in tissues and cell lines, with the exception of the macrophage RTS-11 cell line, in which expression was higher. Expression of all three TNF-α isoforms could be modulated by crude LPS, peptidoglycan, polyinosinic:polycytidylic acid, and rIFN-γ in cell lines and primary macrophages, as well as by bacterial and viral infections. TNF-α3 is the most responsive gene at early time points post-LPS stimulation and can be highly induced by the T cell-stimulant PHA, suggesting it is a particularly important TNF-α isoform. rTNF-α3 produced in CHO cells was bioactive in different cell lines and primary macrophages. In the latter, it induced the expression of proinflammatory cytokines (IL-1β, IL-6, IL-8, IL-17C, and TNF-αs), negative regulators (SOCS1-3, TGF-β1b), antimicrobial peptides (cathelicidin-1 and hepcidin), and the macrophage growth factor IL-34, verifying its key role in the inflammatory cytokine network and macrophage biology of fish.
Scottish Fish Immunology Research Centre, School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, United Kingdom;
Suhee
S
Hong
Ronggai
R
Li
Qiaoqing
Q
Xu
Chris J
CJ
Secombes
Tiehui
T
Wang
D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000096:biosynthesis / Q000235:genetics; D001483:Base Sequence; D002460:Cell Line; D016207:Cytokines / Q000096:biosynthesis / Q000235:genetics; D005393:Fish Diseases / Q000276:immunology / Q000378:metabolism; D005399:Fishes / Q000235:genetics / Q000276:immunology; D005786:Gene Expression Regulation / Q000187:drug effects; D007371:Interferon-gamma / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000378:metabolism*; D008969:Molecular Sequence Data; D029141:Novirhabdovirus; D017686:Oncorhynchus mykiss / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D009928:Organ Specificity; D010457:Peptidoglycan / Q000494:pharmacology; D010802:Phylogeny; D010835:Phytohemagglutinins / Q000494:pharmacology; D011070:Poly I-C / Q000494:pharmacology; D020033:Protein Isoforms / Q000737:chemistry / Q000302:isolation & purification / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000378:metabolism / Q000494:pharmacology; D018353:Rhabdoviridae Infections / Q000276:immunology / Q000378:metabolism / Q000662:veterinary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014409:Tumor Necrosis Factor-alpha / Q000737:chemistry / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D015009:Yersinia Infections / Q000276:immunology / Q000378:metabolism / Q000662:veterinary; D044124:Yersinia ruckeri
D023181:Antimicrobial Cationic Peptides; D016207:Cytokines; D008070:Lipopolysaccharides; D010457:Peptidoglycan; D010835:Phytohemagglutinins; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D011070:Poly I-C