Programmable solid-state condensates for spatiotemporal control of mammalian gene expression.

Engineering of nuclear condensates with chemically inducible gene switches is highly desired but challenging for precise and on-demand regulation of mammalian gene expression. Here, we harness the phase-separation capability of biomolecular condensates and describe a versatile strategy to chemically program ligand-dependent gene expression at various stages of interest. By engineering synthetic anchor proteins capable of tethering various genetically encoded condensate structures toward different cellular compartments or gene products of interest, inducible regulation of transcriptional and translational activities was achieved at different endogenous and episomal loci using the same sets of anchor proteins and synthetic solid-state condensates. Using such a holistic condensate-based strategy, we not only achieved regulation performances comparing favorably to state-of-the-art strategies described for CRISPR-Cas9 activity and transcriptional silencing but further showed that chemically inducible retention of mRNA molecules into engineered condensate structures within the nucleus can become a remarkably efficient alternative for translational regulation.