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A role for E2F1 in Ras activation of p21(WAF1/CIP1) transcription
A L Gartel1, F Najmabadi, E Goufman
1University of Illinois College of Medicine, Department of Genetics, M/C 669, 900 South Ashland Avenue, Chicago, IL 60607, USA.
Abstract:
We recently reported that E2F1 could transactivate the p21 promoter via cis-acting elements between -119 to +16 bp of the p21 gene. Here we show that activated V12-H-Ras can induce the p21 promoter through the same region of the p21 promoter by a p53-independent mechanism in NIH3T3 cells. In contrast, activated Ras was not able to induce the p21 promoter in E2F1-/- fibroblasts, suggesting that E2F1 is required for induction of the p21 promoter by activated Ras. Cotransfection of increasing concentrations of dominant negative E2F1 alone, or with dominant negative DP1 into NIH3T3 cells suppressed induction of the p21 promoter by activated Ras. These data suggest that p53-independent induction of the p21 promoter by activated Ras is mediated at least in part by E2F1. Oncogene (2000) 19, 961 - 964.
Insights
Activated Ras induces the p21 promoter via a p53-independent pathway. This induction requires E2F1, highlighting its role in Ras-mediated gene regulation.
Area of Science:
- Molecular Biology
- Cell Biology
- Oncology
Background:
- The p21 promoter is known to be transactivated by E2F1.
- The role of Ras signaling in p21 gene regulation is not fully understood.
Purpose of the Study:
- To investigate the mechanism by which activated Ras induces the p21 promoter.
- To determine the involvement of E2F1 and p53 in Ras-mediated p21 promoter activation.
Main Methods:
- Utilized NIH3T3 cells and E2F1-/- fibroblasts.
- Employed V12-H-Ras activation.
- Performed promoter assays with the p21 gene promoter (-119 to +16 bp).
- Used dominant-negative E2F1 and DP1 constructs.
Main Results:
- Activated Ras induced the p21 promoter in NIH3T3 cells through a p53-independent mechanism.
- Ras failed to induce the p21 promoter in E2F1-/- fibroblasts.
- Dominant-negative E2F1 and DP1 suppressed Ras-induced p21 promoter activity.
Conclusions:
- Activated Ras induces the p21 promoter in a p53-independent manner.
- E2F1 is essential for Ras-mediated induction of the p21 promoter.
- Ras signaling likely converges on E2F1 for p21 gene transactivation.