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Inducible dimerization of RET reveals a specific AKT deregulation in oncogenic signaling

Barbara Frêche1, Patricia Guillaumot, Julie Charmetant

  • 1Laboratoire de Génétique moléculaire, Signalisation et Cancer, Unité Mixte de Recherche (UMR) 5201, Facultéde Médecine, 8 avenue Rockefeller, 69 373 LYON Cedex 08, France.

The Journal of Biological Chemistry
|August 27, 2005
PubMed

Insights

Multiple endocrine neoplasia type 2A (MEN2A) mutations in the RET proto-oncogene cause distinct AKT signaling patterns. These RET mutations bypass normal lipid raft regulation of AKT activation.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cell Signaling

Background:

  • Dominant-activating mutations in the RET proto-oncogene are linked to Multiple Endocrine Neoplasia type 2A (MEN2A).
  • The precise signaling consequences of ligand-independent RET activation in MEN2A remain unclear compared to ligand-induced activation.

Purpose of the Study:

  • To investigate whether oncogenic RET activation in MEN2A elicits identical signaling outputs as ligand-induced RET activation.
  • To elucidate the role of lipid rafts in regulating RET signaling pathways.

Main Methods:

  • Developed a cellular model to compare RET activation via natural ligand versus controlled dimerization mimicking MEN2A mutations.
  • Analyzed proximal and distal signaling events, including AKT and ERK kinase activation.
  • Investigated the influence of cholesterol-sensitive lipid environments on AKT activation dynamics.

Main Results:

  • Controlled RET dimerization (mimicking MEN2A) preserved proximal RET signaling but altered distal AKT activation, causing a delayed and sustained response.
  • Distal ERK activation remained unaffected by controlled RET dimerization.
  • Ligand-induced AKT activation timing is regulated by lipid rafts, a control mechanism bypassed by MEN2A RET mutants.

Conclusions:

  • MEN2A RET mutations induce subtle but significant differences in signaling pathways compared to ligand-induced activation.
  • Lipid rafts play a crucial role in the temporal regulation of AKT activation downstream of RET.

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