Encoding Growth Factor Identity in the Temporal Dynamics of FOXO3 under the Combinatorial Control of ERK and AKT...

Area of Science:

• Cellular signaling pathways
• Molecular biology
• Systems biology

Background:

• Extracellular growth factors transmit signals to transcription factors through cytoplasmic kinase cascades.
• The mechanisms by which these cascades encode specific ligand identities and concentrations remain incompletely understood.
• FOXO3 is a crucial transcription factor involved in various cellular processes, subject to complex regulatory control.

Purpose of the Study:

• To investigate the dynamic behavior of the transcription factor FOXO3 in response to extracellular signals.
• To elucidate how different growth factor signals are encoded by FOXO3 translocation dynamics.
• To explore the differential regulation of FOXO3 dynamics by key kinases Akt and ERK.

Main Methods:

• Live-cell imaging techniques to visualize FOXO3 localization in real-time.
• Statistical modeling to analyze the temporal dynamics of FOXO3 nuclear-to-cytosolic translocation.
• Perturbation experiments to assess the roles of Akt and ERK in regulating FOXO3 dynamics.

Main Results:

• FOXO3 translocation occurs in two distinct temporal phases: an initial synchronous translocation and a subsequent extended shuttling.
• The magnitude and dynamics of these phases vary with growth factor identity and cell type.
• Akt and ERK differentially regulate the early and late phases of FOXO3 translocation, exhibiting low mutual information between phases.
• Cancer cells with dysregulated Akt and ERK show reduced diversity in FOXO3 dynamic states.

Conclusions:

• FOXO3 translocation dynamics provide a mechanism for encoding distinct information about extracellular signals.
• The differential regulation of translocation phases by Akt and ERK allows for complex signal processing.
• Aberrant kinase signaling in cancer cells impairs the ability of FOXO3 to generate diverse dynamic responses.