Proteome half-life dynamics in living human cells

Area of Science:

• Cell biology
• Proteomics
• Biochemistry

Background:

• Cells maintain protein homeostasis through degradation and dilution via cell growth.
• The interplay between protein degradation and dilution is not fully understood.
• Accurate measurement of protein half-lives is crucial for understanding cellular dynamics.

Purpose of the Study:

• To develop a noninvasive method for measuring protein half-lives in living cells.
• To investigate the dynamics of proteome half-life under various cellular conditions.
• To explore the implications of protein half-life regulation in cancer therapy.

Main Methods:

• Development of the "bleach-chase" technique for noninvasive protein half-life measurement.
• Application of the method to fluorescently tagged proteins in living human cancer cells.
• Assay of approximately 100 different proteins to determine their half-lives.

Main Results:

• Measured protein half-lives in human cancer cells ranged from 45 minutes to 22.5 hours.
• Cellular stresses that inhibit cell division preferentially increased the half-lives of long-lived proteins.
• Short-lived proteins showed minimal changes in half-life under stress conditions.

Conclusions:

• The balance of degradation and dilution influences protein half-life dynamics.
• Differential protein stability changes under stress suggest a mechanism for targeting rapidly growing cancer cells.
• The bleach-chase method provides a novel approach to study proteome half-life dynamics in vivo.