Molecular editing, a concept rooted in synthetic chemistry, was applied to targeted protein degradation to achieve precision control over target selectivity. The authors started from an existing dual degrader, LLC0424, which engaged both NSD2 and GSPT1. By modifying the parent scaffold they aimed to generate structurally related molecules that adopt distinct modes of action—one acting as a PROTAC and the other as a molecular glue—to bias degradation toward either NSD2 or GSPT1.
The rationale rests on the premise that small changes in molecular structure can alter ternary complex formation, cooperativity, and the conformational ensemble sampled by a bifunctional or glue-like degrader, thereby tuning selectivity in targeted protein degradation.
Using LLC0424 as the starting point, the research team generated two analogs denoted 424-ND and 424-GD. These analogs are structurally analogous to each other and to the parent compound but were repurposed through targeted chemical edits to favor divergent mechanisms of target engagement and degradation. Specific synthetic routes and stepwise chemical modifications were reported in the full manuscript; details beyond the abstract were not provided in the source text.
The naming reflects the functional outcome observed: 424-ND functions as a degrader with NSD2 bias (ND), while 424-GD behaves as a glue that preferentially degrades GSPT1 (GD).
424-ND selectively induced degradation of NSD2. The degradation activity required the E3 ligase adaptor CRBN and an intact ubiquitin-proteasome system, indicating a classic PROTAC-like, CRBN- and proteasome-dependent mechanism. Functionally, 424-ND suppressed androgen receptor (AR) signaling in prostate cancer cells, demonstrating a downstream phenotypic consequence of selective NSD2 loss in the cellular models used.
The authors position 424-ND as a selective chemical probe for interrogating NSD2 biology and its role in AR-driven cancer signaling pathways. The abstract does not provide quantitative degradation metrics, concentration–response data, or in vivo characterization; those details are in the main paper.
In contrast to 424-ND, 424-GD selectively induced degradation of GSPT1. GSPT1 degradation by 424-GD was accompanied by robust upregulation of integrated stress response markers ATF4 and ATF3, consistent with activation of a stress-responsive transcriptional program following GSPT1 loss.
The observed molecular glue activity indicates that subtle molecular edits converted the parent dual degrader into a compound that promotes neosubstrate recruitment and degradation of GSPT1 without the same NSD2-targeting profile as 424-ND.
Biolayer interferometry experiments were performed to measure ternary complex interactions. These assays revealed distinct cooperativity profiles when either NSD2 or GSPT1 was present. The cooperativity differences correlated with the biased degradation observed: the compound favoring NSD2 displayed a ternary complex signature consistent with selective CRBN-mediated recruitment of NSD2, while the GSPT1-selective compound showed a cooperativity profile aligned with neosubstrate engagement of GSPT1.
Thus, the biophysical data connect molecular-level interaction differences to cellular degradation outcomes and selectivity.
Molecular dynamics and metadynamics simulations were used to probe the conformational behavior of the compounds. The simulations indicated that 424-ND and 424-GD occupy distinct low-energy conformational ensembles and adopt different spatial orientations. These conformational preferences likely underlie the divergent ternary complex cooperativity and target selectivity observed experimentally.
The computational results support a model in which small structural edits shift the accessible conformational landscape, thereby altering how a degrader engages E3 ligases and neosubstrates.
This work provides two selective chemical probes: a PROTAC selective for NSD2 (424-ND) and a molecular glue selective for GSPT1 (424-GD). Beyond the probes themselves, the study demonstrates that molecular editing is an effective strategy to tune selectivity in targeted protein degradation. By linking chemical edits to changes in ternary cooperativity and conformational ensembles, the approach offers a potentially generalizable route to convert dual or promiscuous degraders into selective agents with distinct mechanisms of action.
The abstract highlights the potential utility of molecular editing for structure optimization in medicinal chemistry, applied specifically to the targeted protein degradation field.
Competing interests disclosed include advisory roles for K.D. and company affiliations for A.M.C. Funding sources declared include the National Natural Science Foundation of China, the National Key R&D Program of China, and the Strategic Priority Research Program of the Chinese Academy of Sciences.
The source is a bioRxiv preprint; the abstract does not include detailed experimental protocols, full datasets, or clinical recommendations. For experimental details, degradation kinetics, potency, and broader applicability, readers should consult the full preprint and supplementary materials.