Direct binding of MEK1 and MEK2 to AKT induces Foxo1 phosphorylation, cellular migration and metastasis

Area of Science:

• Cellular signaling pathways
• Molecular biology
• Cancer research

Background:

• Signaling pathway crosstalk is crucial for cellular specificity.
• The ERK cascade's specificity is partly achieved through interactions with other pathways.

Purpose of the Study:

• To identify direct interactions between MEK1/2 and AKT.
• To elucidate the functional consequences of this interaction.
• To explore its therapeutic potential in cancer.

Main Methods:

• Identified direct interaction between MEK1/2 and AKT using biochemical assays.
• Characterized the interaction domains and regulatory phosphorylation sites.
• Developed a blocking peptide to inhibit the MEK-AKT interaction.
• Assessed cellular effects (migration, adhesion, proliferation) and metastasis in a mouse model.

Main Results:

• MEK1 and MEK2 directly interact with AKT, mediated by the proline-rich domain.
• Phosphorylation at Ser298 (MEK1) or Ser306 (MEK2) regulates this interaction.
• A blocking peptide inhibited MEK-AKT interaction, affecting cell migration and adhesion but not proliferation.
• The MEK-AKT complex phosphorylates FoxO1, a transcription factor involved in migration.
• Inhibition of the interaction reduced metastasis in a breast cancer mouse model.

Conclusions:

• The MEK-AKT interaction is a novel mechanism regulating cell migration and adhesion.
• This interaction represents a potential therapeutic target for metastatic cancers.
• Understanding this crosstalk enhances knowledge of signaling specificity determination.