Programmable promoter editing for precise control of transgene expression.

Subtle changes in gene expression direct cells to distinct cellular states. Identifying and controlling dose-dependent transgenes requires tools for precisely titrating expression. To this end, we developed a framework called DIAL for building editable promoters that allows for fine-scale, heritable changes in transgene expression. Using DIAL, we increase expression by recombinase-mediated excision of spacers between the binding sites of a synthetic zinc-finger transcription factor and the core promoter. By nesting varying numbers and lengths of spacers, DIAL generates a tunable range of unimodal setpoints from a single promoter construct. Through small-molecule control of transcription factors and recombinases, DIAL supports temporally defined, user-guided control of transgene expression. Integration of DIAL promoters into lentivirus allows for efficient delivery to primary cells. As promoter editing generates stable states, DIAL setpoints are heritable, facilitating mapping of transgene levels to phenotypes. The highly modular and extensible DIAL framework opens up new opportunities for screening and tailoring transgene expression to regulate gene and cell-based therapies.