Direct GPCR-EGFR interaction enables synergistic membrane-to-nucleus information transfer

Area of Science:

• Cellular Biology
• Molecular Pharmacology
• Signal Transduction

Background:

• Epidermal Growth Factor Receptor (EGFR) and G-Protein Coupled Receptors (GPCRs) are key cell surface receptors.
• Heteromerization between EGFR and GPCRs influences cellular signaling pathways.
• The interaction between Angiotensin II Receptor Type 1 (AT1R) and EGFR is investigated as a model system.

Purpose of the Study:

• To investigate the heteromerization of AT1R and EGFR.
• To determine the functional relevance of AT1R-EGFR heteromerization in synergistic nuclear information transfer.
• To elucidate the role of this interaction in downstream gene expression regulation.

Main Methods:

• In silico modeling to design AT1R mutants deficient in EGFR interaction.
• Co-immunoprecipitation (CoIP), Förster Resonance Energy Transfer (FRET), and Fluorescence-Lifetime Imaging Microscopy (FLIM) to assess receptor interaction.
• Digital high-content microscopy to quantify changes in cell morphology, ERK1/2 phosphorylation (ppERK1/2), Serum Response Factor (SRF)-activation, and cFOS protein expression.

Main Results:

• CoIP, FRET, and FLIM confirmed physical interaction between wild-type AT1R and EGFR, which was significantly reduced in AT1R mutants.
• Cells expressing wild-type AT1R and EGFR showed synergistic responses to stimuli regarding cell morphology, ppERK1/2, cFOS, and SRF activity.
• This EGFR-AT1R synergism was completely absent in cells expressing interaction-deficient AT1R mutants.

Conclusions:

• AT1R-EGFR heteromerization is essential for mediating synergistic downstream gene expression regulation.
• This heteromerization modulates the intensity and temporal dynamics of nuclear information transfer.
• Ligand-dependent EGFR transactivation alone is insufficient for complete synergistic control of gene expression.