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A gradient of epidermal growth factor receptor signaling determines the sensitivity of rbf1 mutant cells to

Nam-Sung Moon1, Luisa Di Stefano, Nicholas Dyson

  • 1Massachusetts General Hospital Cancer Research Center, Harvard Medical School, Building 149, Charlestown, MA 02129, USA.

Molecular and Cellular Biology
|September 7, 2006
PubMed

Insights

Loss of retinoblastoma (Rb) protein RBF1 causes apoptosis in Drosophila. This cell death is regulated by the Argos/Epidermal Growth Factor Receptor (EGFR) pathway, not cell cycle progression.

Area of Science:

  • Developmental Biology
  • Cell Biology
  • Genetics

Background:

  • Inactivation of retinoblastoma (Rb) family proteins induces apoptosis, impacting development and tumor suppression.
  • The cell type and tissue specificity of Rb-induced apoptosis is not well understood.
  • Rb inactivation's apoptotic outcome is context-dependent, suggesting regulatory mechanisms are involved.

Purpose of the Study:

  • To investigate the specific conditions causing apoptosis in retinoblastoma protein 1 (rbf1) mutant cells during Drosophila development.
  • To elucidate the molecular mechanisms underlying the cell-type-specific apoptosis observed upon Rb family member inactivation.
  • To identify signaling pathways that cooperate with RBF1 to regulate apoptosis.

Main Methods:

  • Utilized Drosophila melanogaster as a model organism.
  • Generated and analyzed rbf1 mutant flies.
  • Investigated gene expression and protein interactions related to cell cycle, apoptosis, and signaling pathways.
  • Manipulated signaling pathways including EGFR, ras, and raf.

Main Results:

  • rbf1 mutant cells undergo apoptosis in the morphogenetic furrow during the third larval instar.
  • This apoptosis is E2F-dependent but not due to aberrant cell cycle progression.
  • The Argos/Epidermal Growth Factor Receptor (EGFR) pathway, specifically DER signaling, regulates this apoptosis.
  • RBF1 and DER/ras/raf signaling cooperate to suppress E2F-dependent apoptosis.
  • Loss of RBF1 alters a developmental cell death program controlled by Argos and DER.

Conclusions:

  • The context-dependent apoptosis resulting from rbf1 inactivation is controlled by the Argos/DER pathway.
  • A developmental gradient of DER/ras/raf signaling dictates the timing and location of rbf1 loss-induced apoptosis.
  • This study reveals a novel interaction between Rb proteins and receptor tyrosine kinase signaling in regulating apoptosis.

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