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Mitosis-specific negative regulation of epidermal growth factor receptor, triggered by a decrease in ligand binding
N Kiyokawa1, E K Lee, D Karunagaran
1Department of Tumor Biology, Breast Cancer Basic Research Program, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
The Journal of Biological Chemistry
|July 25, 1997
Summary
Epidermal growth factor receptor (EGFR) is unresponsive to stimulation during M phase due to hyperphosphorylation. Overexpression of EGFR overrides this cell cycle-specific regulation, allowing ligand-induced signaling.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Epidermal growth factor receptor (EGFR) is a key regulator of cell growth and proliferation.
- EGFR signaling is crucial for normal cellular functions but its regulation during cell division is not fully understood.
Purpose of the Study:
- To investigate the regulation of EGFR function during the M phase of the cell cycle.
- To determine the impact of M phase-specific regulation on EGFR signaling and ligand responsiveness.
Main Methods:
- Cell cycle synchronization and analysis.
- Western blotting to assess protein phosphorylation (tyrosine, serine/threonine).
- Ligand binding assays and receptor dimerization studies.
- Analysis of EGFR signaling pathways.
Main Results:
- EGFR exhibits reduced phosphotyrosine content and kinase activity in M phase due to hyperphosphorylation.
- Ligand binding affinity and EGF-induced receptor dimerization are suppressed in M phase, inhibiting downstream signaling.
- Surface receptor levels remain unchanged across cell cycle phases.
- Overexpression of EGFR overcomes M phase-specific suppression, restoring ligand responsiveness.
Conclusions:
- EGFR function is negatively regulated during M phase through hyperphosphorylation, preventing ligand-induced signaling.
- This M phase-specific regulation of receptor tyrosine kinases is critical for normal cell cycle progression.
- Disruption of this regulation, such as through EGFR overexpression, can alter cell cycle-dependent signaling pathways.