AUTACs: Cargo-Specific Degraders Using Selective Autophagy

Area of Science:

• Biochemistry
• Cell Biology
• Drug Discovery

Background:

• Protein silencing is crucial in biomedical research.
• Targeted protein degradation (TPD) using PROTACs is a growing drug discovery area.
• Current TPD methods are limited by the proteasome's substrate scope.

Purpose of the Study:

• To introduce a novel targeted-clearance strategy, autophagy-targeting chimeras (AUTACs).
• To overcome the limitations of proteasomal degradation by utilizing autophagy.
• To demonstrate AUTACs' ability to selectively degrade intracellular materials.

Main Methods:

• Design of AUTACs comprising a degradation tag (guanine derivatives) and a target-specific warhead.
• Application of mitochondria-targeted AUTACs in patient-derived fibroblast cells.
• Assessment of mitochondrial clearance, biogenesis, and cytoprotective effects.

Main Results:

• AUTACs successfully degraded fragmented mitochondria and proteins, consistent with autophagy's substrate scope.
• Mitochondria-targeted AUTACs enhanced the removal of dysfunctional mitochondria and promoted normal mitochondrial biogenesis.
• AUTAC treatment exhibited cytoprotective effects against acute mitochondrial injuries.

Conclusions:

• AUTACs represent a novel, target-specific modality for inducing selective autophagy.
• This approach expands the scope of targeted protein degradation beyond proteasomal pathways.
• AUTACs offer a new platform for developing autophagy-based therapeutics with enhanced cargo selectivity.