Advancing Targeted Protein Degradation Through Immunoproteasome-Caged N-Degrons

Area of Science:

• Biochemistry
• Molecular Biology
• Drug Discovery

Background:

• Proteolysis-targeting chimeras (PROTACs) offer therapeutic potential but face challenges with metabolic instability and selectivity.
• N-degron PROTACs are susceptible to premature degradation and off-target effects due to their structure.

Purpose of the Study:

• To develop a novel PROTAC strategy that enhances functional stability and achieves context-dependent specificity.
• To engineer an N-degron PROTAC activated by a specific protease for targeted protein degradation.

Main Methods:

• Introduction of a "caged" N-degron PROTAC with a tetrapeptide-morpholine fragment shielding the arginine degron.
• Utilizing the immunoproteasome (iCP), an inducible proteasome isoform, for protease-gated activation.
• Linking the PROTAC to dasatinib to target ABL tyrosine kinase degradation.

Main Results:

• The caged N-degron PROTAC demonstrated protease-gated activation upon iCP-mediated cleavage.
• This strategy enhanced functional stability and provided context-dependent specificity for protein degradation.
• Degradation of ABL tyrosine kinase was achieved through this immunoproteasome-gated mechanism.

Conclusions:

• Immunoproteasome-gated PROTACs represent a promising framework for next-generation degraders.
• The protease-gated strategy integrates endogenous proteolytic specificity for improved degrader activation.
• Further development is needed to address cell permeability and disease-dependent iCP expression.