Method for cloning in vivo targets of the Egr-1 transcription factor

A methodology is described that allows the in vivo trapping of transcription factors to their target regulatory elements in multiple genes simultaneously. Cross-linking using formaldehyde is the first of several steps to isolate, purify, clone and characterize multiple gene promoter DNA fragments. The example that we use indicates that the TGF beta 1 gene is a direct target induced by Egr-1 in HT1080 cells that express constitutive Egr-1, thus explaining the growth retardation that follows Egr-1 expression. The genes identified using this procedure reflect the specific activities of Egr-1 at that moment in the cell and provide a method for confirmation of genes that are the direct targets of Egr-1 action.