Fig. 2.
The Egr inhibitor construct selectively blocks ERE-mediated transcription in PC12 cells. A, PC12 cells were transfected with a luciferase reporter plasmid (TG5) that is driven by a segment of the TGFβ1 promoter containing an ERE site. As found in HEK293 cells, the Egr inhibitor construct blocks the increase in luciferase activity induced by Egr3. B, The Egr inhibitor construct does not block the increase in luciferase activity displayed by cells transfected with the GAL4/Egr3(1-104) expression construct and the GAL4 reporter plasmid. C, In PC12 cells transfected with the ERE reporter, NGF induces a strong increase in luciferase activity that is suppressed by the Egr inhibitor construct. Cells were harvested 6 hr after addition of NGF.D, PC12 cells were cotransfected with a GAL4 reporter plasmid and an expression plasmid encoding a chimeric protein generated by fusing the GAL4 DNA-binding domain with the C-terminal activation domain of Elk1 (Path Detect Elk Trans-Reporting System, Stratagene). Stimulation of these cells with NGF (6 hr) triggers a robust increase in luciferase activity that is not blocked by cotransfection with a third plasmid encoding the Egr inhibitor construct.