Egr1 regulates the coordinated expression of numerous EGF receptor target genes as identified by ChIP on chip

Background: UV irradiation activates the EGF receptor, induces Egr1 expression and promotes apoptosis in a variety of cell types. We examined the hypothesis that Egr1 regulates genes that mediate this process by use of a chip-on-chip protocol in human tumorigenic prostate M12 cells. Results: UV irradiation led to significant binding of 288 gene promoters by Egr1. A major functional subgroup consisted of apoptosis related genes. The largest subgroup of 24 genes; belong to the EGFR-signal transduction pathway. Egr1 promoter binding had a significant impact on gene expression of target genes. Conventional ChIP and qRTPCR were used to validate promoter binding and expression changes. siRNA experiments were used to demonstrate the specific role of Egr1 in gene regulation. UV-stimulation promotes growth arrest and apoptosis of M12 cells and our data clearly show that downstream target of EGFR, namely Egr1, mediates this apoptotic response. Our study also identified numerous previously unknown targets of Egr1. These include FasL, MAX and RRAS2, which may play a role in the apoptotic response/growth arrest. Conclusion: Our results indicate that M12 cells undergo Egr1-dependent apoptotic response upon UV-stimulation and led to the identification of downstream targets of Egr1, which mediate EGFR function.