Structure and mechanism of activity-based inhibition of the EGF receptor by Mig6

Area of Science:

• Molecular Biology
• Cell Signaling
• Cancer Research

Background:

• Mig6 (negative regulator of ErbB signaling) acts as a feedback inhibitor, targeting activated ErbB-family receptors for internalization.
• Epidermal growth factor receptor (EGFR) is a key mediator of cell growth and proliferation, often dysregulated in cancer.

Purpose of the Study:

• To elucidate the structural and functional mechanisms by which Mig6 inhibits EGFR.
• To investigate the role of dual phosphorylation in modulating Mig6-EGFR interaction and inhibition.
• To explore the significance of Mig6 loss in human gliomas with EGFR amplification.

Main Methods:

• X-ray crystallography to determine the structures of human EGFR-Mig6 complexes.
• Biochemical assays to analyze phosphorylation events and receptor inhibition.
• Bioinformatic analysis of glioma patient data (1,057 samples) for ERRFI1 gene deletions.

Main Results:

• EGFR phosphorylates Mig6 at Y394, a site primed by Src-mediated phosphorylation at Y395.
• Crystal structures reveal how Mig6 rearrangement upon EGFR phosphorylation leads to irreversible EGFR inhibition.
• Loss of Mig6 (via focal deletions of its gene, ERRFI1) is frequent in EGFR-amplified gliomas, indicating its tumor-suppressive role.

Conclusions:

• Dual phosphorylation of Mig6 by EGFR and Src provides a mechanism for tightly regulated, receptor-activated inhibition.
• Mig6 acts as a critical negative feedback regulator of EGFR signaling, with its inactivation contributing to gliomagenesis.
• Targeting Mig6 or its regulatory pathways may offer therapeutic strategies for EGFR-driven cancers.