Different EGF-induced receptor dimer conformations for signaling and internalization.
Jordi Haubrich1, Jurriaan M Zwier2, Fabienne Charrier-Savournin2
1Institut de Génomique Fonctionnelle, University of Montpellier, CNRS, INSERM, Montpellier Cedex 5, France.
Summary
Epidermal Growth Factor Receptor (EGFR) dimerization is induced by both EGF and tyrosine kinase inhibitors. Intracellular dimer conformation, not signaling, dictates EGFR internalization, offering new cancer treatment strategies.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Epidermal Growth Factor Receptor (EGFR) activation and internalization mechanisms are crucial for cancer therapy but remain debated.
- Understanding whether agonists form EGFR dimers or act on pre-existing dimers is key.
Purpose of the Study:
- To provide direct evidence for EGF-induced EGFR dimer formation.
- To investigate the effect of tyrosine kinase (TK) inhibitors on EGFR dimerization and internalization.
- To determine the role of intracellular TK dimer conformation in EGFR internalization.
Main Methods:
- Utilized Förster Resonance Energy Transfer (FRET) between snap-tagged EGFR subunits to quantify dimer formation.
- Assessed the impact of EGF and various TK inhibitors (Erlotinib, Lapatinib) on EGFR dimerization.
- Monitored EGF-induced EGFR internalization in the presence of TK inhibitors.
Main Results:
- EGF agonists significantly increase EGFR dimer formation, confirmed by FRET.
- Erlotinib-class TK inhibitors induce EGFR dimer formation even when the binding domain is inactive.
- TK inhibitors block EGFR signaling but do not inhibit EGF-induced internalization; only Erlotinib promoting asymmetric dimers slowed internalization.
Conclusions:
- EGFR internalization is primarily regulated by the conformation of the intracellular TK dimer, not EGFR signaling.
- Distinct modes of action exist for TK inhibitors targeting EGFR.
- These findings open new avenues for controlling EGFR signaling in cancer treatment.
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