biostudies-literatureCheng-Sanchez ISwiss National Science FoundationKrebsliga Schweiz355-361https://www.ebi.ac.uk/biostudies/studies/S-EPMC10945562biostudies-literatureUnknown15(3)Proteolysis Targeting Chimeras (PROTACs) are bifunctional molecules that simultaneously bind an E3 ligase and a protein of interest, inducing degradation of the latter via the ubiquitin-proteasome system. Here we present the development of degraders targeting CREB-binding protein (CBP) and E1A-associated protein (EP300)-two homologous multidomain enzymes crucial for enhancer-mediated transcription. Our PROTAC campaign focused on CPI-1612, a reported inhibitor of the histone acetyltransferase (HAT) domain of these two proteins. A novel asymmetric synthesis of this ligand was devised, while PROTAC-SAR was explored by measuring degradation, target engagement, and ternary complex formation <i>in cellulo</i>. Our study demonstrates that engagement of Cereblon (CRBN) and a sufficiently long linker between the E3 and CBP/EP300 binders (≥21 atoms) are required for PROTAC-mediated degradation using CPI-1612 resulting in a new active PROTAC <b>dCE-1</b>. Lessons learned from this campaign, particularly the importance of cell-based assays to understand the reasons underlying PROTAC performance, are likely applicable to other targets to assist the development of degraders.ACS medicinal chemistry lettersDiscovery and Characterization of Active CBP/EP300 Degraders Targeting the HAT Domain.PMC10945562180345KFS-4585-08-2018Sinergia Grant CRSII5_180345/1Kirillova MSNevado CGossele KACheng-Sanchez IPalaferri LfalseDiscovery and Characterization of Active CBP/EP300 Degraders Targeting the HAT Domain.Proteolysis Targeting Chimeras (PROTACs) are bifunctional molecules that simultaneously bind an E3 ligase and a protein of interest, inducing degradation of the latter via the ubiquitin-proteasome system. Here we present the development of degraders targeting CREB-binding protein (CBP) and E1A-associated protein (EP300)-two homologous multidomain enzymes crucial for enhancer-mediated transcription. Our PROTAC campaign focused on CPI-1612, a reported inhibitor of the histone acetyltransferase (HAT) domain of these two proteins. A novel asymmetric synthesis of this ligand was devised, while PROTAC-SAR was explored by measuring degradation, target engagement, and ternary complex formation <i>in cellulo</i>. Our study demonstrates that engagement of Cereblon (CRBN) and a sufficiently long linker between the E3 and CBP/EP300 binders (≥21 atoms) are required for PROTAC-mediated degradation using CPI-1612 resulting in a new active PROTAC <b>dCE-1</b>. Lessons learned from this campaign, particularly the importance of cell-based assays to understand the reasons underlying PROTAC performance, are likely applicable to other targets to assist the development of degraders.2024-01-01T00:00:00Z2024 Mar2026-06-02T18:07:03.567Z2025-04-04T00:26:31.722ZS-EPMC109455623850584210.1021/acsmedchemlett.3c00490