Regulation of the insulin-like growth factor system during normal rat lung development.
Insulin-like growth factor (IGF)-I and IGF-II are small peptide growth factors that interact with a specific membrane receptor, the type 1 IGF receptor, to stimulate cellular proliferation and/or differentiation. The actions of these growth factors and their availability to their receptors are modulated by specific binding proteins, IGF binding protein (IGFBP)-1 through -6, which together with the IGFs and IGF receptors form the IGF system. We have analyzed RNA extracted from fetal (gestation day 16 [E16] through 22 [E22]) and adult (60-day-old) rat lung for expression of each component of the IGF system. IGF-I and -II RNAs are expressed throughout fetal development. IGF-I mRNA remained relatively constant in fetal and adult lung, whereas IGF-II RNA decreased in later gestation to levels below detection by Northern analyses in adult lung. Type 1 IGF receptor expression varied little through all ages studied, whereas the type 2 IGF receptor RNA displayed developmental regulation with a decline in expression with advancing age. IGFBP-1 transcripts were not detected in fetal or adult lung. IGFBP-2 RNA was expressed from E16 to E22, although its abundance decreased in late gestation and in adult lung, with the lowest levels of expression on day E22. IGFBP-3, -4, and -5 had similar profiles of RNA abundance, with fetuses at ages E21 and E22 displaying higher levels of transcript abundance as compared with those aged E17 to E20; the lowest RNA abundance was seen at E20.(ABSTRACT TRUNCATED AT 250 WORDS)
Moats-Staats
B M
BM
Department of Pediatrics, University of North Carolina at Chapel Hill.
Price
W A
WA
Xu
L
L
Jarvis
H W
HW
Stiles
A D
AD
D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000096:biosynthesis*; D005314:Embryonic and Fetal Development; D005260:Female; D018507:Gene Expression Regulation, Developmental; D005865:Gestational Age; D018970:Insulin-Like Growth Factor Binding Protein 1; D018971:Insulin-Like Growth Factor Binding Protein 2; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis; D007335:Insulin-Like Growth Factor II / Q000096:biosynthesis; D008168:Lung / Q000196:embryology / Q000254:growth & development* / Q000378:metabolism; D008969:Molecular Sequence Data; D011247:Pregnancy; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017526:Receptor, IGF Type 1 / Q000096:biosynthesis; D017527:Receptor, IGF Type 2 / Q000096:biosynthesis; D017451:Receptors, Somatomedin / Q000096:biosynthesis*; D013002:Somatomedins / Q000096:biosynthesis*
D002352:Carrier Proteins; D018970:Insulin-Like Growth Factor Binding Protein 1; D018971:Insulin-Like Growth Factor Binding Protein 2; D012333:RNA, Messenger; D017527:Receptor, IGF Type 2; D017451:Receptors, Somatomedin; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D017526:Receptor, IGF Type 1