Direct transcriptional induction of Gadd45I[sup3 by Ascl1 during neuronal differentiation

• Published in: Molecular and cellular neuroscience 2010-07, Vol.44 (3), p.282-296
• Main Authors: Huang, Holly S, Kubish, Ginger M, Redmond, Tanya M, Turner, David L, Thompson, Robert C, Murphy, Geoffrey G, Uhler, Michael D
• Format: Article
• Language: English
• ISSN: 1044-7431
• DOI: 10.1016/j.mcn.2010.03.014

The basic helix-loop-helix transcription factor Ascl1 plays a critical role in the intrinsic genetic program responsible for neuronal differentiation. Here, we describe a novel model system of P19 embryonic carcinoma cells with doxycycline-inducible expression of Ascl1. Microarray hybridization and real-time PCR showed that these cells demonstrated increased expression of many neuronal proteins in a time- and concentration-dependent manner. Interestingly, the gene encoding the cell cycle regulator Gadd45I[sup3 was increased earliest and to the greatest extent following Ascl1 induction. Here, we provide the first evidence identifying Gadd45I[sup3 as a direct transcriptional target of Ascl1. Transactivation and chromatin immunoprecipitation assays identified two E-box consensus sites within the Gadd45I[sup3 promoter necessary for Ascl1 regulation, and demonstrated that Ascl1 is bound to this region within the Gadd45I[sup3 promoter. Furthermore, we found that overexpression of Gadd45I[sup3 itself is sufficient to initiate some aspects of neuronal differentiation independent of Ascl1.