Muñoz-Gil, Gorka

Abstract Transcriptional condensates (TCs) are dynamic, membrane-less assemblies of proteins and nucleic acids that form at specific genomic loci to control gene expression. The primary drivers of TC formation and function are long stretches of polypeptide chains that lack well-defined tertiary structure, known as the intrinsically disordered regions (IDRs) of Transcription Factors (TFs). However, the role of well-structured domains such as the DNA-binding domain (DBD) in condensate formation and downstream regulation remains poorly understood. Here, we investigated whether the DBD of the Progesterone Receptor (PR), a model TF regulated by hormone binding, contributes to the formation of PR TCs. By combining Single Particle Tracking (SPT) with deep-learning-based single-trajectory analysis, we demonstrated that both the IDR and the DBD are required for the formation of PR condensates. Furthermore, transcriptomic analysis showed that mutations of either of the two domains result in the expression of a distinct set of genes, with functional assays corroborating these findings and linking domain-specific transcription to differential effects on cell proliferation and migration. Together, our results show that domains beyond IDRs also play a role in TC formation and function and uncover domain-specific regulation of transcriptional and oncogenic programs.