Haven't got a glue: Protein surface variation for the design of molecular glue degraders

Molecular glue degraders are small, drug-like compounds that induce interactions between an E3 ubiquitin ligase and a target, which result in ubiquitination and subsequent degradation of the recruited protein. In recent years, serendipitous discoveries revealed that some preclinical and clinical compounds already work as molecular glue degraders, with many more postulated to destabilize their targets through indirect or yet unresolved mechanisms. Here we review strategies by which E3 ubiquitin ligases can be reprogrammed by monovalent degraders, with a focus on molecular glues hijacking cullin-RING ubiquitin ligases. We argue that such drugs exploit the intrinsic property of proteins to form higher-order assemblies, a phenomenon previously seen with disease-causing sequence variations. Modifications of the protein surface by a bound small molecule can change the interactome of the target protein. By inducing interactions between a ligase and a substrate, molecular glue degraders offer an exciting path for the development of novel therapeutics.

Development of an FKBP12-recruiting chemical-induced proximity DNA-encoded library and its application to discover an autophagy potentiator

Chemical inducers of proximity (CIPs) are molecules that recruit one protein to another and introduce new functionalities toward modulating protein states and activities. While CIP-mediated recruitment of E3 ligases is widely exploited for the development of degraders, other therapeutic modalities remain underexplored. We describe a non-degrader CIP-DNA-encoded library (CIP-DEL) that recruits FKBP12 to target proteins using non-traditional acyclic structures, with an emphasis on introducing stereochemically diverse and rigid connectors to attach the combinatorial library. We deployed this strategy to modulate ATG16L1 T300A, which confers genetic susceptibility to Crohn's disease (CD), and identified a compound that stabilizes the variant protein against caspase-3 (Casp3) cleavage in a FKBP12-independent manner. We demonstrate in cellular models that this compound potentiates autophagy, and reverses the xenophagy defects as well as increased cytokine secretion characteristic of ATG16L1 T300A. This study provides a platform to access unexplored chemical space for CIP design to develop therapeutic modalities guided by human genetics.