This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Surmacz, E Articles by Baserga, R Search for Related Content PubMed PubMed Citation Articles by Surmacz, E Articles by Baserga, R

Activation of the ribosomal DNA promoter in cells exposed to insulinlike growth factor I.

ABSTRACT

We constructed a stable cell line, 3T3A5, which carried a chimeric gene in which the simian virus 40 T-antigen-coding gene was under the control of the mouse ribosomal DNA promoter. These cells expressed T antigen when they were growing exponentially in 10% fetal calf serum, but they all became T negative when incubated for 5 days in low-concentration serum. The readdition of serum or platelet-poor plasma again induced the expression of T antigen, which was accompanied by an increase in steady-state levels of the corresponding RNA. Among the various growth factors tested for their ability to induce T-antigen expression in 3T3A5 cells, only insulinlike growth factor I (IGF-I) could induce T antigen at physiological concentrations. The effect of IGF-I or platelet-poor plasma was abolished by an antibody to IGF-I. Other growth factors, like insulin and epidermal growth factor, could induce the expression of T antigen in 3T3A5 cells, but only at concentrations far above the physiological range. Other growth factors were totally ineffective. These results indicate that exposure of cells to IGF-I can activate transcription from the ribosomal DNA promoter.

This article has been cited by other articles:

• Wu, A., Tu, X., Prisco, M., Baserga, R. (2005). Regulation of Upstream Binding Factor 1 Activity by Insulin-like Growth Factor I Receptor Signaling. J. Biol. Chem. 280: 2863-2872 [Abstract] [Full Text]  
• Valentinis, B, Baserga, R (2001). IGF-I receptor signalling in transformation and differentiation. Mol. Pathol. 54: 133-137 [Abstract] [Full Text]  
• Valentinis, B., Navarro, M., Zanocco-Marani, T., Edmonds, P., McCormick, J., Morrione, A., Sacchi, A., Romano, G., Reiss, K., Baserga, R. (2000). Insulin Receptor Substrate-1, p70S6K, and Cell Size in Transformation and Differentiation of Hemopoietic Cells. J. Biol. Chem. 275: 25451-25459 [Abstract] [Full Text]