Transcriptional regulation of rat insulin-like growth factor-binding protein-1 expression by growth hormone.
The low mol wt insulin-like growth factor-binding protein (IGFBP-1) originally isolated from amniotic fluid has been considered to be GH independent. In this report we have examined the effect of GH on hepatic IGFBP-1 expression in the hypophysectomized rat. Using a rat IGFBP-1 cDNA probe we now demonstrated that hepatic IGFBP-1 expression is up-regulated in the GH-deficient rat. In addition, using ligand blotting, an increase in the abundance of a 30-kDa [125I]IGF-I-BP was detected in both hepatic extracts and serum from hypophysectomized rats. After a single ip injection of GH, the IGFBP-1 transcription rate was reduced within 30 min to the levels seen in the sham-operated control rats. Similarly, hepatic IGFBP-1 mRNA abundance was reduced after both acute GH injection and chronic GH treatment for 8 days. These data demonstrate that IGFBP-1 expression is inversely regulated by GH.
Seneviratne
C
C
Department of Internal Medicine, University of Manitoba, Winnipeg, Canada.
Luo
J M
JM
Murphy
L J
LJ
D000818:Animals; D002352:Carrier Proteins / Q000096:biosynthesis / Q000097:blood / Q000235:genetics*; D015342:DNA Probes; D005786:Gene Expression Regulation / Q000187:drug effects*; D013006:Growth Hormone / Q000494:pharmacology*; D007016:Hypophysectomy; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D014158:Transcription, Genetic / Q000187:drug effects*
D002352:Carrier Proteins; D015342:DNA Probes; D018969:Insulin-Like Growth Factor Binding Proteins; D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone