Exploiting the Cullin E3 Ligase Adaptor Protein SKP1 for Targeted Protein Degradation

Area of Science:

• Biochemistry
• Molecular Biology
• Drug Discovery

Background:

• Proteolysis targeting chimeras (PROTACs) leverage targeted ubiquitination and proteasome degradation to eliminate disease proteins.
• Current PROTACs primarily utilize substrate receptors like cereblon and VHL from Cullin-RING E3 ubiquitin ligases.
• Exploiting core components of the Cullin-RING E3 ubiquitin ligase complex for PROTACs remains underexplored.

Purpose of the Study:

• To investigate the potential of using core components of the Cullin-RING E3 ubiquitin ligase complex for PROTAC applications.
• To discover and validate a novel covalent recruiter targeting the SKP1 adapter protein.
• To demonstrate the efficacy of SKP1-recruiter PROTACs in degrading neo-substrate proteins.

Main Methods:

• Discovery of a cysteine-reactive covalent recruiter (EN884) targeting SKP1.
• Utilized EN884 in PROTAC design to target neo-substrate proteins.
• Assessed protein degradation in a SKP1- and proteasome-dependent manner.

Main Results:

• Identified EN884, a covalent recruiter for the SKP1 adapter protein.
• Demonstrated successful degradation of neo-substrate proteins, including BRD4 and androgen receptor, using SKP1-recruiter PROTACs.
• Confirmed the degradation is dependent on SKP1 and the proteasome.

Conclusions:

• Core and essential adapter proteins within the Cullin-RING E3 ubiquitin ligase complex can be effectively utilized for targeted protein degradation.
• Covalent chemoproteomic strategies are viable for discovering recruiters against these essential targets.
• This work expands the scope of PROTAC technology by targeting novel components of the E3 ligase machinery.