Molecular characterization and gene expression analysis of insulin-like growth factors I and II in the redbanded seabream, Pagrus auriga: transcriptional regulation by growth hormone.
Insulin-like growth factors (IGFs) I and II (IGF-I and IGF-II) play important roles in fish growth and development. The present study was aimed at isolating cDNAs encoding both IGF-I and IGF-II in the redbanded seabream (Pagrus auriga), and at measuring relative gene expression levels in different organs and during larval development. A fragment of 1321 nucleotides coding for IGF-I was cloned from liver using 3' and 5' RACE techniques. It included an open reading frame of 558 nucleotides, encoding a 185-amino acid preproIGF-I. With respect to IGF-II, a fragment of 1544 nucleotides was cloned as well. The open reading frame spanned 648 nucleotides, rendering a 215-amino acid preproIGF-II. The deduced mature 67-amino acid IGF-I and 70-amino acid IGF-II exhibited high sequence identities with their corresponding fish counterparts, ranging between 88.6-100% and 79.1-98.5%, respectively. Real-time PCR showed the highest IGF-I transcripts in liver ( approximately 200-fold higher than head-kidney). In contrast, the highest IGF-II mRNAs were detected in gills and heart ( approximately 16-fold higher than head-kidney). In addition, both IGFs exhibited different gene expression patterns during larval development suggesting that their expression is developmentally regulated. IGF-I reached the highest expression levels at 18 days after hatching (11.6-fold higher than 1 day after hatching), whereas IGF-II expression did not change significantly. Both hepatic IGF-I and IGF-II mRNA levels increased sharply (3.1- and 19-fold higher than control, respectively) 3 h after injection of porcine growth hormone, but remained unchanged from 6 to 24 h after treatment. Our results are discussed in relation to those previously reported for other bony fish.
Ponce
Marian
M
IFAPA Centro El Toruño, Camino Tiro de Pichón s/n, 11500 El Puerto de Santa María (Cádiz), Spain.
Infante
Carlos
C
Funes
Victoria
V
Manchado
Manuel
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D029941:Fish Proteins / Q000235:genetics*; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D013006:Growth Hormone / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D007335:Insulin-Like Growth Factor II / Q000235:genetics*; D008969:Molecular Sequence Data; D010473:Perciformes / Q000235:genetics* / Q000254:growth & development; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013552:Swine; D014158:Transcription, Genetic / Q000187:drug effects
D018076:DNA, Complementary; D029941:Fish Proteins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D013006:Growth Hormone