Dynamic Control of Cell Signaling with Optogenetic Modulation of Protein Abundance in Living Mammalian Cells

Precise modulation of protein levels is essential for investigating the dynamics of signaling pathways. Degradation-based approaches allow rapid reduction of protein abundance, and their combination with optogenetic regulation enables controlled and reversible manipulation. In this chapter, we describe an optogenetic strategy that stabilizes a protein of interest by inhibiting its degradation. As a proof of concept, we demonstrate light-dependent stabilization of MKP3 and constitutively active MEK and examine the resulting changes in ERK signaling. We also provide a step-by-step protocol for measuring protein stabilization kinetics. This method integrates a potent degradation tag with optogenetic control to achieve tunable and reversible regulation of protein levels in living cells.