Molecular cloning and characterization of rainbow trout (Oncorhynchus mykiss) CCAAT/enhancer binding protein beta.
A full-length cDNA encoding CCAAT/enhancer-binding protein beta (C/EBPbeta) was cloned from rainbow trout by anchored PCR. The putative 291 amino acid protein has 53% and 32% identity to the zebrafish and Japanese flounder sequences, respectively, and 30-34% identity to tetrapod homologues. This clone contains most conserved C/EBPbeta domains except the second transactivation domain just like the zebrafish homologue. Also similar to zebrafish, rainbow trout produces only shorter C/EBPbeta isoforms (LAP and LIP) but not the longer isoform (LAP*). However, unlike the zebrafish and Japanese flounder homologues, trout C/EBPbeta has the short open reading frame (uORF) upstream of the start codon for LAP but in an alternate reading frame, a feature of tetrapod C/EBPbeta genes. In normal rainbow trout, C/EBPbeta mRNA was detected in peripheral blood leukocytes, head kidney, posterior kidney, liver, spleen, gills, intestine and muscle. RT-PCR revealed that transcript levels of trout C/EBPbeta are clearly higher in sodium alginate-induced peritoneal cells than in head kidney and peritoneal cells of saline-injected fish or head kidney cells of alginate-injected fish. Together with expression in immunologically important tissues, this indicates that C/EBPbeta is likely to be involved in the immune response just as in mammals. Southern hybridization suggested that C/EBPbeta is a single copy gene. There are no introns in this C/EBPbeta gene, just like the mammalian homologues. These data suggest that we have obtained the trout ortholog of C/EBPbeta.
Fujiki
Kazuhiro
K
Department of Biology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario, N2L 3G1, Canada.
Gerwick
Lena
L
Bayne
Christopher J
CJ
Mitchell
Leslie
L
Gauley
Julie
J
Bols
Niels
N
Dixon
Brian
B
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D019143:Evolution, Molecular; D018628:Gene Dosage; D008969:Molecular Sequence Data; D017686:Oncorhynchus mykiss / Q000235:genetics* / Q000378:metabolism; D010802:Phylogeny; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
D022782:CCAAT-Enhancer-Binding Protein-beta; D018076:DNA, Complementary; D012333:RNA, Messenger