Horm Metab Res 2004; 36(10): 679-685
DOI: 10.1055/s-2004-826017
Original Basic
© Georg Thieme Verlag KG Stuttgart · New York

3,5-diiodothyronine Mimics the Effect of Triiodothyronine on Insulin-like Growth Factor Binding Protein-4 Expression in Cultured Rat Hepatocytes

I.  Demori1 , E.  Gerdoni1 , E.  Fugassa1 , A.  Voci1
  • 1Dipartimento di Biologia Sperimentale, Ambientale ed Applicata (DIBISAA), Sezione di Fisiologia Generale e Comparata, Università degli Studi di Genova
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Publikationsverlauf

Received 5 January 2004

Accepted after revision 15 April 2004

Publikationsdatum:
03. November 2004 (online)

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Abstract

We have previously demonstrated that triiodothyronine (T3) stimulates hepatic IGFBP-4 expression in rats. Since there is evidence that some of the genes whose expression is regulated by T3 are also sensitive to 3,5-diiodothyronine (T2), we used the adult rat hepatocyte model in primary cultures directly exposed to T2 to evaluate insulin-like growth factor binding protein-4 (IGFBP-4) expression by Northern and Ligand blot analyses in this study. Our results demonstrate that T2, like T3, is able to enhance IGFBP-4 mRNA and protein after 12 - 24 h of incubation. The potency of the two iodothyronines is comparable as judged by dose-dependence experiments. The T2-induced IGFBP-4 increase is independent from ongoing protein synthesis but dependent on active transcription. Since T3 and T2 do not affect IGF-I production, it appears that the iodothyronines affect the hepatic IGF system at the IGFBP level. Our data, demonstrating that T2 mimics the stimulatory effect of T3 on IGFBP-4 expression by rat hepatocytes, allow us to include IGFBP-4 gene among the genes regulated by the two iodothyronines.

References

Ilaria Demori

Dipartimento di Biologia Sperimentale · Ambientale ed Applicata (DIBISAA) · Sezione di Fisiologia Generale e Comparata · Università degli Studi di Genova

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