Different Epidermal Growth Factor Receptor (EGFR) Agonists Produce Unique Signatures for the Recruitment of
Tom Ronan1, Jennifer L Macdonald-Obermann2, Lorel Huelsmann2
1From the Department of Biomedical Engineering and Center for Biological Systems Engineering and.
Abstract:
The EGF receptor can bind seven different agonist ligands. Although each agonist appears to stimulate the same suite of downstream signaling proteins, different agonists are capable of inducing distinct responses in the same cell. To determine the basis for these differences, we used luciferase fragment complementation imaging to monitor the recruitment of Cbl, CrkL, Gab1, Grb2, PI3K, p52 Shc, p66 Shc, and Shp2 to the EGF receptor when stimulated by the seven EGF receptor ligands. Recruitment of all eight proteins was rapid, dose-dependent, and inhibited by erlotinib and lapatinib, although to differing extents. Comparison of the time course of recruitment of the eight proteins in response to a fixed concentration of each growth factor revealed differences among the growth factors that could contribute to their differing biological effects. Principal component analysis of the resulting data set confirmed that the recruitment of these proteins differed between agonists and also between different doses of the same agonist. Ensemble clustering of the overall response to the different growth factors suggests that these EGF receptor ligands fall into two major groups as follows: (i) EGF, amphiregulin, and EPR; and (ii) betacellulin, TGFα, and epigen. Heparin-binding EGF is distantly related to both clusters. Our data identify differences in network utilization by different EGF receptor agonists and highlight the need to characterize network interactions under conditions other than high dose EGF.
Insights
Different EGF receptor ligands recruit downstream proteins uniquely, influencing cell responses. This study reveals distinct signaling patterns for various EGF receptor agonists, impacting biological outcomes.
Area of Science:
- Cellular signaling
- Molecular biology
- Receptor tyrosine kinases
Background:
- The Epidermal Growth Factor (EGF) receptor is crucial for cell growth and differentiation.
- Different EGF receptor ligands can elicit distinct cellular responses despite activating similar downstream pathways.
Purpose of the Study:
- To investigate the molecular basis for differential cellular responses induced by various EGF receptor ligands.
- To analyze the recruitment dynamics of key downstream signaling proteins to the EGF receptor upon stimulation by different ligands.
Main Methods:
- Utilized luciferase fragment complementation imaging (LFCI) to monitor protein recruitment.
- Quantified the recruitment of eight specific proteins (Cbl, CrkL, Gab1, Grb2, PI3K, p52 Shc, p66 Shc, Shp2) to the EGF receptor.
- Employed principal component analysis (PCA) and ensemble clustering to analyze recruitment data.
Main Results:
- All eight proteins showed rapid, dose-dependent recruitment, inhibited by erlotinib and lapatinib.
- Significant differences in the kinetics and extent of protein recruitment were observed among the seven EGF receptor ligands.
- PCA and clustering revealed two major groups of ligands based on their recruitment profiles: (i) EGF, amphiregulin, and EPR; (ii) betacellulin, TGFα, and epigen. Heparin-binding EGF formed a separate cluster.
Conclusions:
- EGF receptor agonists exhibit distinct patterns of downstream signaling network utilization.
- These ligand-specific recruitment differences provide a mechanistic explanation for varied biological responses.
- Future research should explore EGF receptor network interactions beyond high-dose EGF stimulation.
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