Egr-1 activation of rat adrenal phenylethanolamine N-methyltransferase gene.

The immediate early gene transcription factor Egr-1 increases luciferase reporter gene activity 3-4-fold when a rat phenylethanolamine N-methyltransferase (PNMT) promoter-luciferase construct and an Egr-1 expression construct are cotransfected into transformed PC12 cells (RS1). Egr-1 also stimulates endogenous PNMT mRNA expression in the RS1 cells. Furthermore, when transfected RS1 cells are treated with dexamethasone, both luciferase and endogenous PNMT mRNA rise an additional 2-fold although dexamethasone does not independently activate transcription from the PNMT promoter.

A novel repression module, an extensive activation domain, and a bipartite nuclear localization signal defined in the immediate-early transcription factor Egr-1.

Egr-1 is an immediate-early response gene induced transiently and ubiquitously by mitogenic stimuli and also regulated in response to signals that initiate differentiation. The Egr-1 gene product, a nuclear phosphoprotein with three zinc fingers of the Cys2His2 class, binds to the sequence CGCCCCCGC and transactivates a synthetic promoter construct 10-fold in transient-transfection assays. We have analyzed the structure and function of the Egr-1 protein in detail, delineating independent and modular activation, repression, DNA-binding, and nuclear localization activities.

Human platelet-derived growth factor A chain is transcriptionally repressed by the Wilms tumor suppressor WT1.

Wilms tumor, an embryonic kidney malignancy, accounts for approximately 6% of all pediatric neoplasms. A gene implicated in the genesis of this tumor, the Wilms tumor suppressor gene (WT1), encodes a zinc-finger DNA-binding protein (WT1) that functions as a transcriptional repressor. In certain Wilms tumors, the platelet-derived growth factor A chain (PDGF-A) is overexpressed; it has therefore been suggested that it may play an autocrine role in development of these neoplasms.

Transcriptional repression mediated by the WT1 Wilms tumor gene product.

The wt1 gene, a putative tumor suppressor gene located at the Wilms tumor (WT) locus on chromosome 11p13, encodes a zinc finger-containing protein that binds to the same DNA sequence as EGR-1, a mitogen-inducible immediate-early gene product that activates transcription. The transcriptional regulatory potential of WT1 has not been demonstrated. In transient transfection assays, the WT1 protein functioned as a repressor of transcription when bound to the EGR-1 site.