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Updated: Feb 17, 2026
An Optimized Single-Molecule Pull-Down Assay for Quantification of Protein Phosphorylation
Published on: June 6, 2022
Development of a 5-plex SILAC method tuned for the quantitation of tyrosine phosphorylation dynamics
Manuel Tzouros1, Sabrina Golling, David Avila
1Translational Technologies and Bioinformatics, Non-Clinical Safety, Pharmaceuticals Division, F. Hoffmann-La Roche Ltd., 4070 Basel, Switzerland.
Abstract:
The propagation of phosphorylation downstream of receptor tyrosine kinases is a key dynamic cellular event involved in signal transduction, which is often deregulated in disease states such as cancer. Probing phosphorylation dynamics is therefore crucial for understanding receptor tyrosine kinases' function and finding ways to inhibit their effects. MS methods combined with metabolic labeling such as stable isotope labeling with amino acids in cell culture (SILAC) have already proven successful in deciphering temporal phosphotyrosine perturbations. However, they are limited in terms of multiplexing, and they also are time consuming, because several experiments need to be performed separately. Here, we introduce an innovative approach based on 5-plex SILAC that allows monitoring of phosphotyrosine signaling perturbations induced by a drug treatment in one single experiment. Using this new labeling strategy specifically tailored for phosphotyrosines, it was possible to generate the time profiles for 318 unique phosphopeptides belonging to 215 proteins from an erlotinib-treated breast cancer cell line model. Hierarchical clustering of the time profiles followed by pathway enrichment analysis highlighted epidermal growth factor receptor (EGFR or ErbB1) and ErbB2 signaling as the major pathways affected by erlotinib, thereby validating the method. Moreover, based on the similarity of its time profile to those of other proteins in the ErbB pathways, the phosphorylation at Tyr453 of protein FAM59A, a recently described adaptor of EGFR, was confirmed as tightly involved in the signaling cascade. The present investigation also demonstrates the remote effect of EGFR inhibition on ErbB3 phosphorylation sites such as Tyr1289 and Tyr1328, as well as a potential feedback effect on Tyr877 of ErbB2. Overall, the 5-plex SILAC is a straightforward approach that extends sample multiplexing and builds up the arsenal of methods for tyrosine phosphorylation dynamics.
Insights
This study introduces a 5-plex SILAC method to track phosphotyrosine signaling dynamics in cancer cells after drug treatment. The approach efficiently identifies key signaling pathways like EGFR and ErbB2 affected by erlotinib.
Area of Science:
- Cellular signaling and signal transduction
- Cancer biology and molecular oncology
- Mass spectrometry and proteomics
Background:
- Receptor tyrosine kinase (RTK) signaling, particularly phosphorylation, is crucial for cellular communication and often dysregulated in cancer.
- Understanding RTK phosphorylation dynamics is vital for disease treatment and drug development.
- Existing methods like MS with SILAC are effective but limited in multiplexing and are time-consuming.
Purpose of the Study:
- To develop an improved method for monitoring phosphotyrosine signaling dynamics.
- To enable simultaneous analysis of multiple samples in a single experiment, reducing time and increasing efficiency.
- To investigate the effects of erlotinib on phosphotyrosine signaling in a breast cancer model.
Main Methods:
- Development and application of a novel 5-plex stable isotope labeling with amino acids in cell culture (SILAC) strategy.
- Mass spectrometry (MS) analysis of phosphopeptides from erlotinib-treated breast cancer cells.
- Time-profile generation for phosphopeptides, followed by hierarchical clustering and pathway enrichment analysis.
Main Results:
- Successfully generated time profiles for 318 unique phosphopeptides from 215 proteins in a single experiment.
- Identified epidermal growth factor receptor (EGFR) and ErbB2 signaling pathways as significantly affected by erlotinib treatment.
- Confirmed the role of FAM59A phosphorylation at Tyr453 in the EGFR signaling cascade and observed effects on ErbB3 and ErbB2 phosphorylation.
Conclusions:
- The 5-plex SILAC method offers enhanced multiplexing for efficient analysis of tyrosine phosphorylation dynamics.
- This approach provides valuable insights into complex signaling networks affected by targeted therapies like erlotinib.
- The study validates the utility of advanced proteomic techniques for understanding cancer signaling and identifying therapeutic targets.
