Methods for Quantitative Assessment of Protein Degradation

Area of Science:

• Biochemistry
• Molecular Biology
• Pharmacology

Background:

• Accurate assessment of small molecules that induce selective protein degradation (degraders) is crucial.
• Quantifying cellular protein levels is essential for characterizing degrader activity.

Purpose of the Study:

• To develop and validate ratio-metric methods for quantifying cellular protein levels using a dual fluorescent reporter system.
• To establish a kinetic framework for analyzing protein degradation data.
• To propose a time-invariant kinetic analysis for degrader characterization.

Main Methods:

• Utilized a dual fluorescent reporter system (GFP/mCherry) to quantify protein levels.
• Developed methods for generating stable GFP-protein of interest (POI)/mCherry reporter cell lines.
• Employed Fluorescence-Activated Cell Sorting (FACS) and Laser Scanning Cytometry for data readout.
• Created computational tools for data processing and kinetic analysis.

Main Results:

• Demonstrated the utility of the ratio-metric GFP/mCherry system for accurate protein level measurement.
• Showcased two distinct methods for creating stable reporter cell lines.
• Validated FACS and Laser Scanning Cytometry as effective readout techniques.
• Identified time-dependency in traditional degrader metrics (DC50, Dmax).

Conclusions:

• The developed ratio-metric reporter system provides a robust method for quantifying protein levels.
• A novel time-invariant kinetic analysis framework (Michaelis-Menten-like) was proposed for protein degrader kinetics.
• This new framework offers more accurate and time-independent parameters (Km app, Vmax app) for degrader characterization.