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Transcriptional regulation of AKT activation by E2F

Marie Chaussepied1, Doron Ginsberg

  • 1Department of Molecular Cell Biology, The Weizmann Institute of Science, Rehovot 76100, Israel.

Molecular Cell
|December 3, 2004
PubMed

Insights

The E2F transcription factor upregulates AKT activity by increasing the expression of Gab2, an adaptor protein. This AKT activation inhibits E2F1-induced apoptosis, suggesting a negative feedback loop between E2F and AKT signaling.

Area of Science:

  • Molecular Biology
  • Cell Signaling
  • Cancer Research

Background:

  • The pRB-E2F pathway regulates cell proliferation by controlling gene expression for cell cycle progression.
  • E2F transcription factors, particularly E2F1, are implicated in both cell proliferation and apoptosis.
  • Mitogenic signaling pathways converge on the pRB-E2F pathway.

Purpose of the Study:

  • To investigate the interplay between the E2F pathway and major signal transduction pathways.
  • To elucidate the mechanism by which E2F influences AKT activity.
  • To identify novel E2F target genes involved in signal transduction.

Main Methods:

  • Analysis of E2F-dependent gene expression.
  • Western blotting to assess protein levels and phosphorylation.
  • Identification of direct E2F target genes using molecular biology techniques.

Main Results:

  • E2F was found to upregulate AKT activity via a transcription-dependent mechanism.
  • Grb2 associated binder 2 (Gab2) was identified as a direct E2F target gene.
  • Gab2 acts as an essential mediator of E2F-induced AKT activation, which in turn inhibits E2F1-induced apoptosis.

Conclusions:

  • E2F transcription factors directly regulate AKT signaling through the induction of Gab2.
  • A negative feedback loop exists where E2F activation leads to AKT-mediated inhibition of E2F1-induced apoptosis.
  • This crosstalk between E2F and AKT signaling pathways has implications for cell proliferation and survival.

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