RESUMEN
Targeted protein degradation is a new therapeutic modality based on drugs that destabilize proteins by inducing their proximity to E3 ubiquitin ligases. Of particular interest are molecular glues that can degrade otherwise unligandable proteins by orchestrating direct interactions between target and ligase. However, their discovery has so far been serendipitous, thus hampering broad translational efforts. Here, we describe a scalable strategy toward glue degrader discovery that is based on chemical screening in hyponeddylated cells coupled to a multi-omics target deconvolution campaign. This approach led us to identify compounds that induce ubiquitination and degradation of cyclin K by prompting an interaction of CDK12-cyclin K with a CRL4B ligase complex. Notably, this interaction is independent of a dedicated substrate receptor, thus functionally segregating this mechanism from all described degraders. Collectively, our data outline a versatile and broadly applicable strategy to identify degraders with nonobvious mechanisms and thus empower future drug discovery efforts.
Asunto(s)
Acetamidas/química , Antibacterianos/farmacología , Quinasas Ciclina-Dependientes/metabolismo , Ciclinas/metabolismo , Doxiciclina/farmacología , Hidrazinas/química , Indoles/química , Proteolisis/efectos de los fármacos , Proteína 7 de Unión a Retinoblastoma/metabolismo , Línea Celular Tumoral , Relación Dosis-Respuesta a Droga , Evaluación Preclínica de Medicamentos , Regulación de la Expresión Génica , Humanos , Estructura Molecular , Unión Proteica , Conformación Proteica , Procesamiento Proteico-Postraduccional/efectos de los fármacos , Bibliotecas de Moléculas Pequeñas/química , Relación Estructura-Actividad , Ubiquitina-Proteína Ligasas/metabolismo , Ubiquitinación/efectos de los fármacosRESUMEN
The histone acetyl reader bromodomain-containing protein 4 (BRD4) is an important regulator of chromatin structure and transcription, yet factors modulating its activity have remained elusive. Here we describe two complementary screens for genetic and physical interactors of BRD4, which converge on the folate pathway enzyme MTHFD1 (methylenetetrahydrofolate dehydrogenase, cyclohydrolase and formyltetrahydrofolate synthetase 1). We show that a fraction of MTHFD1 resides in the nucleus, where it is recruited to distinct genomic loci by direct interaction with BRD4. Inhibition of either BRD4 or MTHFD1 results in similar changes in nuclear metabolite composition and gene expression; pharmacological inhibitors of the two pathways synergize to impair cancer cell viability in vitro and in vivo. Our finding that MTHFD1 and other metabolic enzymes are chromatin associated suggests a direct role for nuclear metabolism in the control of gene expression.