Porcine insulin-like growth factor-I (pIGF-I): complementary deoxyribonucleic acid cloning and uterine expression of messenger ribonucleic acid encoding evolutionarily conserved IGF-I peptides.
In order to facilitate studies of insulin-like growth factor-I (IGF-I) expression during the pregnancy-associated development of uterus and mammary gland in the pig model, we have isolated several cDNA clones corresponding to porcine IGF-I (pIGF-I) mRNA. Sequence analysis of two cDNA fragments (sigf. 2 and sigf. 3) revealed an open reading frame encoding in order a putative 25 amino acid (aa) hydrophobic leader peptide, the mature (processed) 70 aa pIGF-I peptide and a 35 aa carboxy-terminal extension (E) peptide. The deduced aa sequence of the pIGF-I peptide is identical to human and bovine IGF-I but differs from that of rat and mouse at three and four residues, respectively. The sequences of the amino- and carboxy-terminal IGF extension peptides are also highly conserved among these species. Northern analysis using sigf. 3 as a probe revealed multiple IGF-I mRNAs (including species of 8000, 2300, and 1200 nucleotides in length) in uteri of pregnant pigs. Highest levels of the uterine IGF-I mRNAs were found at early pregnancy, when increased levels of immunoreactive tissue IGF-I were also observed. Mammary levels of IGF-I mRNAs and protein were considerably lower than that observed for uterus at the same time period. Thus, uterine production of IGF-I appears to be especially significant during early pregnancy in the pig when uterine growth, elevated IGF-I in uterine fluids, and rapid embryonic development are observed.
Tavakkol
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A
Department of Animal Science, Ohio State University, Wooster 44691.
Simmen
F A
FA
Simmen
R C
RC
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics*; D005260:Female; D005796:Genes; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics*; D013002:Somatomedins / Q000235:genetics*; D013552:Swine; D014158:Transcription, Genetic; D014599:Uterus / Q000378:metabolism*
D012333:RNA, Messenger; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D004247:DNA