Aggregate selective removal of pathological tau via clustering-activated degraders

Selective degradation of pathological protein aggregates while sparing monomeric forms is of major therapeutic interest. The E3 ligase TRIM21 degrades antibody-bound proteins in an assembly state-specific manner, owing to the requirement of TRIM21 RING domain clustering for activation, yet effective targeting of intracellular assemblies remains challenging. Here, we fused the RING domain of TRIM21 to a target-specific nanobody to create intracellularly expressed constructs capable of selectively degrading assembled proteins. We evaluated this approach against histone 2B-GFP and tau, a protein that undergoes pathological aggregation in Alzheimer’s and other neurodegenerative diseases. RING-nanobody degraders prevented or reversed tau aggregation in culture and in vivo, with minimal impact on monomeric tau. This approach may have therapeutic potential for the many disorders driven by intracellular protein aggregation.

Methods
Data presented in this publication has been collected via the following methods

High content fluorescent microscopy
Single molecule pull down (SiMPULL) super resolution microscopy
Flow Cytometry
Semi-quantitative immunoblotting
Quantitative immunofluorescence
ELISA
Western blot band densitometry