Redirecting E3 Ubiquitin Ligases for Targeted Protein Degradation with Heterologous Recognition Domains.

Targeted protein degradation (TPD) mediated by PROTACs (proteolysis targeting chimeras) or molecular glues is an emerging therapeutic strategy. Despite greater than 600 E3 ligases and their associated components, a limited number have been deployed in TPD. Those commonly used include cereblon (CRBN) and von Hippel-Lindau tumor suppressor (VHL), which are expressed widely and for which high affinity ligands are available. Limiting TPD to specific cells or tissues would be desirable in many settings. To this goal we have determined the potential of two erythroid cell-enriched E3 ligases, TRIM10 and TRIM58, to degrade a protein of interest, BCL11A, a validated therapeutic target for the β-hemoglobinopathies. We established a general strategy in which heterologous recognition domains replace the PRY-SPRY domain of TRIM10 and TRIM58. Recruitment of TRIM10 or TRIM58 to BCL11A by coiled-coil peptides, nanobodies, or the substrate recognition domain of CRBN led to its degradation. Our findings illustrate a strategy that may be widely useful in evaluating the TPD potential of other E3 ubiquitin ligases and provide a rationale for discovery of ligands for TRIM10 and TRIM58 for erythroid-selective depletion of proteins of interest.