Regulation of IGFBP-1 and -4 expression by triiodothyronine (T3) in cultured hepatocytes is cell- and gene-specific.
Evidence suggests that thyroid hormone plays a role in the regulation of hepatic IGF/IGFBP expression both in human and rats. In this study we compared the effect of T3 on IGFBP-1 and -4 expression in rat hepatocyte primary cultures and in the human hepatoma cell line HepG2. Northern blot analysis revealed that IGFBP-1 mRNA levels were not affected by T3 in cultured rat hepatocytes, whereas a net increase of IGFBP-1 transcript abundance was induced by the hormone in HepG2 cells. On the contrary, IGFBP-4 mRNA levels were increased in rat hepatocytes cultured in the presence of T3, but unaffected in T3-treated HepG2 cells. Therefore, thyroid hormone seems to regulate hepatic IGFBP expression in a direct and gene-specific way. Moreover, the effects of thyroid hormone depend strictly on the source of target hepatocyte.
Demori
I
I
Istituto di Fisiologia Generale, Università degli Studi di Genova.
Bottazzi
C
C
Arzani
D
D
Voci
A
A
Fugassa
E
E
D000818:Animals; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000235:genetics*; D018974:Insulin-Like Growth Factor Binding Protein 4 / Q000235:genetics*; D008099:Liver / Q000187:drug effects* / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D014284:Triiodothyronine / Q000494:pharmacology*
D018970:Insulin-Like Growth Factor Binding Protein 1; D018974:Insulin-Like Growth Factor Binding Protein 4; D012333:RNA, Messenger; D014284:Triiodothyronine