Identification and bioactivities of IFN-gamma in rainbow trout Oncorhynchus mykiss: the first Th1-type cytokine characterized functionally in fish.
IFN-gamma is one of the key cytokines in defining Th1 immune responses. In this study, an IFN-gamma homologue has been identified in rainbow trout Oncorhynchus mykiss, and its biological activities have been characterized. The trout IFN-gamma cDNA is 1034 bp in length and translates into a 180-aa protein. The first intron of the trout IFN-gamma gene contains highly polymorphic GACA minisatellites and 44-bp DNA repeats, giving rise to at least six alleles. IFN-gamma is structurally conserved among vertebrates, and a signature motif has been identified. A nuclear localization sequence known to be crucial for IFN-gamma biological activities is also present in the C-terminal region of the trout IFN-gamma. The IFN-gamma expression was induced in head kidney leukocytes by stimulation with PHA or poly(I:C) and in kidney and spleen of fish injected with poly(I:C). rIFN-gamma produced in Escherichia coli significantly stimulated gene expression of IFN-gamma-inducible protein 10 (gammaIP-10), MHC class II beta-chain, and STAT1, and enhanced respiratory burst activity in macrophages. Deletion of 29-aa residues from the C terminus containing the nuclear localization sequence motif resulted in loss of activity with respect to induction of gammaIP-10 in RTS-11 cells. Moreover, IFN-gamma-induced gammaIP-10 expression was completely abolished by the protein kinase C inhibitor staurosporine, and partially reduced by U0126, a specific inhibitor for ERKs. Taken together, the present study has demonstrated for the first time a functional IFN-gamma homologue in a fish species, strongly suggesting a conserved Th1 immune response is most likely present in lower vertebrates.
Zou
Jun
J
Scottish Fish Immunology Research Centre, University of Aberdeen, Aberdeen, Scotland, United Kingdom. j.j.zou@abdn.ac.uk
Carrington
Allison
A
Collet
Bertrand
B
Dijkstra
Johannes Martinus
JM
Yoshiura
Yasutoshi
Y
Bols
Niels
N
Secombes
Chris
C
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002070:Butadienes / Q000494:pharmacology; D002460:Cell Line; D054357:Chemokine CXCL10; D019743:Chemokines, CXC / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D003001:Cloning, Molecular; D016207:Cytokines / Q000494:pharmacology; D029941:Fish Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology; D007371:Interferon-gamma / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D007438:Introns; D008264:Macrophages / Q000276:immunology / Q000378:metabolism; D018895:Microsatellite Repeats; D008969:Molecular Sequence Data; D009570:Nitriles / Q000494:pharmacology; D017686:Oncorhynchus mykiss / Q000235:genetics / Q000276:immunology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000494:pharmacology; D016897:Respiratory Burst / Q000276:immunology; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D018417:Th1 Cells / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism
D002070:Butadienes; D054357:Chemokine CXCL10; D019743:Chemokines, CXC; D016207:Cytokines; D029941:Fish Proteins; D009570:Nitriles; D047428:Protein Kinase Inhibitors; D011993:Recombinant Fusion Proteins; C113580:U 0126; D007371:Interferon-gamma