Engineered transcription factor-binding arrays for DNA-based gene expression control in mammalian cells

Tools that manipulate gene expression in mammalian cells without any additional expression are critical for cell engineering applications. Here, we demonstrate the use of arrays of transcription factor (TF) recognition elements (REs) as DNA tools for controlling gene expression. We first demonstrate that TetR-based RE arrays can alter synthetic gene circuit performance. We then open the approach to any TF with a known binding site by developing a new technique called Cloning Troublesome Repeats in Loops (CTRL), which can assemble plasmids with up to 256 RE repeats. Transfection of custom RE array plasmids assembled by CTRL into mammalian cells modifies host cell gene regulation by sequestration of TFs of interest and can sequester both synthetic and native TFs, offering applications in the control of gene circuits and for directing cell fate. This work advances our ability to assemble repetitive DNA arrays and shows how TF-binding RE arrays expand possibilities in mammalian cell engineering.