Growth hormone (GH) and prolactin (PRL) regulate IGFBP-3 gene expression in rat beta-cells.
We examined the effects of growth hormone (GH), prolactin (PRL) and insulin-like growth factor-I (IGF-I) on DNA synthesis, and insulin-like growth factor binding protein 3 (IGFBP-3) gene expression, in a rat beta-cell line INS-1. GH and PRL were equally effective in increasing DNA synthesis and IGFBP-3 gene expression. IGF-I also stimulated DNA synthesis, but its effect on IGFBP-3 mRNA accumulation was moderate. The GH activities in this cell line were not mediated by IGF-I production: (1) no IGF-I mRNA could be detected in poly-A RNA preparation, and IGF-I level was very low; (2) neither IGF-I mRNA nor the protein, were increased upon GH treatment; (3) DNA synthesis stimulatory activities of GH and IGF-I were additive; (4) the GH-induced IGFBP-3 mRNA increase was not inhibited by cycloheximide treatment. Thus, the activities of GH in this cell line are not mediated by a protein synthesis.
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INSERM CJF-9313 Hôpital Robert Debré, Paris, France.
Bréant
B
B
Czernichow
P
P
Asfari
M
M
D000818:Animals; D002417:Cattle; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D004247:DNA / Q000096:biosynthesis; D005786:Gene Expression Regulation / Q000187:drug effects; D013006:Growth Hormone / Q000494:pharmacology*; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000096:biosynthesis / Q000235:genetics*; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism*; D011388:Prolactin / Q000494:pharmacology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000494:pharmacology
D018972:Insulin-Like Growth Factor Binding Protein 3; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D011388:Prolactin; D013006:Growth Hormone; D004247:DNA; D003513:Cycloheximide