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

A methodology is described that allows the in vivo trapping of transcriptio n factors to their target regulatory elements in multiple genes simultaneou sly. Cross-linking using formaldehyde is the first of several steps to isol ate, purify, clone and characterize multiple gene promoter DNA fragments. T he example that we use indicates that the TGF beta 1 gene is a direct targe t induced by Egr-1 in HT1080 cells that express constitutive Egr-1, thus ex plaining the growth retardation that follows Egr-1 expression. The genes id entified using this procedure reflect the specific activities of Egr-1 at t hat moment in the cell and provide a method for confirmation of genes that are the direct targets of Egr-1 action.