Cloning of the Mouse Insulin Receptor Substrate-3 (mIRS-3) Promoter, and Its Regulation by p53

• Published in: Molecular endocrinology (Baltimore, Md.) Md.), 2002-07, Vol.16 (7), p.1577-1589
• Main Authors: Sciacchitano, Salvatore, Orecchio, Andrea, Lavra, Luca, Misiti, Silvia, Giacchini, Anna, Zani, Massimo, Danese, Daniele, Gurtner, Aymone, Soddu, Silvia, Di Mario, Umberto, Andreoli, Mario
• Format: Article
• Language: English
• ISSN: 0888-8809; 1944-9917
• DOI: 10.1210/mend.16.7.0881

The insulin receptor susbtrate-3 (IRS-3) is a member of a family of intermediate adapter proteins that function as major intracellular targets for phosphorylation by the activated insulin and IGF-I receptors. Among the four IRS proteins identified so far, IRS-3 exhibits a rather peculiar expression pattern during both the embryonic development and adult life, suggesting a different mechanism of regulation of its expression. In this study, we cloned the 5′ flanking region of the mIRS-3 gene and analyzed its promoter activity. The mIRS-3 promoter is inhibited by wild-type p53, and this effect is completely abolished by cotransfection of a dominant negative p53. Tumor-derived p53 mutants show variable, but lower suppressing capability than wt p53. In addition, treatment with doxorubicin inhibits endogenous expression of mIRS-3 mRNA in C2C12 and 3T3-L1 cells. The DNA region spanning from nucleotides −287 and −178 in the mIRS-3 promoter is responsible for a 32.2% reduction of the mouse double minute 2 (MDM2) promoter activity, suggesting its involvement in the p53-mediated inhibitory effect. In conclusion, our study demonstrates that the mIRS-3 promoter is regulated by p53 at the transcriptional level. The inhibition of mIRS-3 promoter by wild-type p53, and its de-repression by tumor-derived p53 mutants, appears to be similar to that previously reported for the IGF-I receptor promoter, suggesting a common role of these two genes in p53-mediated cell growth and differentiation.