Isolation of an insulin-like growth factor II cDNA from guinea pig liver: expression and developmental regulation.
Insulin-like growth factor II (IGF-II) cDNA was isolated from adult guinea pig liver by polymerase chain reaction (PCR) screening. A cDNA sequence was obtained corresponding to part of the preproIGF-II, including the signal peptide, the mature IGF-II and 37 amino acids of the acid carboxy-terminal E-domain. Amino acid sequence prediction, based on the cDNA clone, showed that mature guinea pig IGF-II has a high homology with both human and rat IGF-II, 100 and 94% identity, respectively. Levels of IGF-II mRNA in guinea pigs of different ages were analyzed by solution hybridization/RNase protection assay using part of the isolated IGF-II cDNA as a probe. There is a marked developmental regulation of IGF-II after birth. IGF-II mRNA levels were high in fetal livers, and decreased 15- to 30-fold in adults. As in man, but in contrast to rats, adult guinea pigs have significant levels of IGF-II mRNA in the liver. In fetal guinea pigs, the expression of IGF-II mRNA was 5-, 2- and 70-fold lower in kidney, skeletal muscle and brain cortex, respectively, than in liver. IGF-II mRNA levels in kidney and skeletal muscle of fetal guinea pigs were 5- and 4-fold higher, respectively, compared with adults. Similar sizes of IGF-II mRNA transcripts could be observed on Northern blots in newborn rats and in fetal guinea pigs. Our conclusions are that the mature IGF-II peptide in the guinea pig is 100% identical to the mature peptide in the human.(ABSTRACT TRUNCATED AT 250 WORDS)
Levinovitz
A
A
Center for Biotechnology, Karolinska Institute, Huddinge, Sweden.
Norstedt
G
G
van den Berg
S
S
Robinson
I C
IC
Ekström
T J
TJ
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001835:Body Weight; D004247:DNA / Q000235:genetics*; D005260:Female; D005786:Gene Expression Regulation; D006168:Guinea Pigs / Q000196:embryology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000096:biosynthesis / Q000235:genetics*; D008099:Liver / Q000737:chemistry*; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011498:Protein Precursors / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
D011498:Protein Precursors; D011993:Recombinant Fusion Proteins; D007335:Insulin-Like Growth Factor II; D004247:DNA