title: A genetic time-delay circuitry in mammalian cells.
abstract: Gene expression circuitries with time-delayed expression profiles regulate key events, such as oscillating systems, noise elimination, and coordinated multi-step processes, in all organisms from bacteria to mammalian cells. We present the rational synthesis of a genetic circuit displaying time-delayed expression in silico and in mammalian cells. The network is based on a time-delay circuit, where the tetracycline-responsive transactivator (tTA) induces expression of the pristinamycin-responsive repressor PIP-KRAB, which silences expression of the terminal human placental secreted alkaline phosphatase (SEAP). While the addition of pristinamycin I inactivates PIP-KRAB and results in the immediate resumption of SEAP expression, addition of tetracycline abolishes PIP-KRAB synthesis. Consequently, SEAP production remains repressed until the PIP-KRAB buffer in the cell is eliminated. We characterized in silico and in vivo the time-delayed expression properties and analyzed the impact of the size and stability of the PIP-KRAB buffer on fine-tuning of the response kinetics. This tunable time-delay circuitry represents a biologic building block for emulating a fundamental circuit topology in integrated artificial synthetic gene networks for the design of tailor-made cell types and organisms.
authors.affiliation: Institute for Chemical and Bio-Engineering, ETH Zurich, HCI F115, Wolfgang-Pauli-Strasse 10, CH-8093 Zurich, Switzerland.
authors.forename: Wilfried
authors.initials: W
authors.lastname: Weber
authors.forename: Beat P
authors.initials: BP
authors.lastname: Kramer
authors.forename: Martin
authors.initials: M
authors.lastname: Fussenegger
mesh_terms: D000818:Animals; D016466:CHO Cells; D003198:Computer Simulation; D006224:Cricetinae; D003412:Cricetulus; D005786:Gene Expression Regulation / Q000235:genetics*; D008957:Models, Genetic; D015398:Signal Transduction / Q000235:genetics*; D013997:Time Factors