Insulin-like growth factor I regulates type I procollagen messenger ribonucleic acid steady state levels in bone of rats.
RNA extracted from parietal bones of rats was analyzed for the abundance of type I procollagen mRNA by a dot hybridization assay using specific cDNA probes. Hypophysectomized rats, deficient in IGF I, have 4.1-fold lower steady state levels of mRNA encoding the alpha 1 chain of type I collagen when compared to normal rats of the same weight (120 g). Administration of recombinant human insulin-like growth factor I (IGF I) for 6 days restores bone collagen mRNA levels to normal, and a single sc injection of 100 micrograms IGF I results in a 1.9-fold increase of both alpha 1(I) and alpha 2 (I)chain mRNAs after 8 h. Studies with calvaria cells in primary culture and with a bone-derived cell line, PyMS, yielded similar results: IGF I treatment of these osteoblast-like cells for 24 h increased steady state levels of type I procollagen mRNAs. Thus, IGF I appears to contribute to osteoblast mRNA expression for both chains of type I collagen.
Department of Medicine (Metabolic Unit), University Hospital, Zürich, Switzerland.
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C
Schmid
H P
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Guler
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D
Rowe
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Froesch
D000818:Animals; D015152:Blotting, Northern; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism*; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D007016:Hypophysectomy; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008297:Male; D009693:Nucleic Acid Hybridization; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism*; D010957:Plasmids; D011347:Procollagen / Q000235:genetics*; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013002:Somatomedins / Q000494:pharmacology*
D011347:Procollagen; D012333:RNA, Messenger; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D004247:DNA