Molecular glue degraders (MGDs) are small molecules that
degrade
proteins of interest via the ubiquitin–proteasome system. While
MGDs were historically discovered serendipitously, approaches for
MGD discovery now include cell-viability-based drug screens or data
mining of public transcriptomics and drug response datasets. These
approaches, however, have target spaces restricted to the essential
proteins. Here we develop a high-throughput workflow for MGD discovery
that also reaches the nonessential proteome. This workflow begins
with the rapid synthesis of a compound library by sulfur(VI) fluoride
exchange chemistry coupled to a morphological profiling assay in isogenic
cell lines that vary in levels of the E3 ligase CRBN. By comparing
the morphological changes induced by compound treatment across the
isogenic cell lines, we were able to identify
FL2-14
as
a CRBN-dependent MGD targeting the nonessential protein GSPT2. We
envision that this workflow would contribute to the discovery and
characterization of MGDs that target a wider range of proteins.