Regulating genes with electromagnetic response elements

A 900 base pair segment of the c-myc promoter, containing eight nCTCTn sequ ences, is required for the induction of c-myc expression by electromagnetic (EM) fields. Similarly, a 70 bp region of the HSP70 promoter, containing t hree nCTCTn sequences, is required for the induction of HSP70 expression by EM fields. Removal of the 900 base pair segment of the c-myc promoter elim inates the ability of EM fields to induce c-myc expression. Similarly, remo val of the 70 bp region of the HSP70 promoter, with its three nCTCTn sequen ces, eliminates the response to EM fields. The nCTCTn sequences apparently act as electromagnetic field response elements (EMRE). To test if introduci ng EMREs imparts the ability to respond to applied EM fields, the 900 bp se gment of the c-myc promoter (containing eight EMREs) was placed upstream of CAT or luciferase reporter constructs that were otherwise unresponsive to EM fields. EMREs-reporter constructs were transfected into HeLa cells and e xposed to 8 muT 60 Hz fields. Protein extracts from EM field-exposed transf ectants had significant increases in activity of both CAT and luciferase, c ompared with identical transfectants that were sham-exposed. Transfectants with CAT or luciferase constructs lacking EMREs remained unresponsive to EM fields, i.e., there was no increase in either CAT or luciferase activity. These data support the idea that EMREs can be used as switches to regulate exogenously introduced genes in gene therapy. (C) 2001 Wiley-Liss, Inc.