Regulation of mouse GADD34 gene transcription after DNA damaging agent methylmethane sulfonate

The GADD34 gene is transcriptionally induced by growth arrest and DNA damage. However, the mechanisms underlying the transcriptional regulation are still unclear. We analyzed the promoter of mouse GADD34 gene and the methylmethane sulfonate (MMS)-induced transcriptional regulation of this gene. By introducing genome mutants, which were linked to the luciferase reporter, into NIH3T3 cells, we defined a 100-bp fragment upstream of the transcriptional initiating site as the minimal promoter of the GADD34 gene. Subsequent study revealed that CRE-binding site located in this minimal promoter was critical for MMS-induced transcription of the GADD34 gene. In vitro binding experiments showed that phosphorylated c-Jun was contained in the CRE/DNA complex. Overexpression of the dominant negative form of c-Jun led to a decrease of MMS-responsive promoter activity. From these results, we conclude that the CRE site of the GADD34 promoter is indispensable to the MMS-responsive cis-element that c-Jun is the essential transcription factor for MMS-stimulated regulation of GADD34 gene expression and that the upstream signaling is dependent on JNK.