The food additive vanillic acid controls transgene expression in mammalian cells and mice

Abstract

Trigger-inducible transcription-control devices that reversibly fine-tune transgene expression in response to molecular cues have significantly advanced the rational reprogramming of mammalian cells. When designed for use in future gene- and cell-based therapies the trigger molecules have to be carefully chosen in order to provide maximum specificity, minimal side-effects and optimal pharmacokinetics in a mammalian organism. Capitalizing on control components that enable Caulobacter crescentus to metabolize vanillic acid originating from lignin degradation that occurs in its oligotrophic freshwater habitat, we have designed synthetic devices that specifically adjust transgene expression in mammalian cells when exposed to vanillic acid. Even in mice transgene expression was robust, precise and tunable in response to vanillic acid. As a licensed food additive that is regularly consumed by humans via flavoured convenience food and specific fresh vegetable and fruits, vanillic acid can be considered as a safe trigger molecule that could be used for diet-controlled transgene expression in future gene- and cell-based therapies.

Two Systems for Conditional Gene Expression in Myxococcus xanthus Inducible by Isopropyl-β- d -Thiogalactopyranoside or Vanillate

“…Vanillate, a natural aromatic plant compound produced from the lignin cleavage, has no apparent deleterious effects on cell physiology in C. crescentus (18-20, 40, 42), and this also appears to be the case in M. xanthus. As a licensed food additive regularly consumed by humans via flavored convenience food, fresh vegetables, and fruits, vanillate is expected to be a safe trigger molecule for transgene expression, and indeed the vanillate-based system was successfully adapted for controlling transgene expression in mammalian cells and mice, as reported recently (11). Thus, both IPTG and vanillate are convenient as innocuous inducers for conditional gene expression in M. xanthus.…”

“…We explored in parallel the applicability in M. xanthus of a vanillate-inducible system that was developed for the bacterium C. crescentus (40) and, very recently, was employed (with suitable modifications) in studies of mammalian cells and mice (11). The system was developed based on the ability of C. crescentus to use vanillate, an intermediate from lignin cleavage, as a carbon source.…”

“…In this report, the design of a new IPTG-based inducible system for conditional expression in M. xanthus is described and its applicability demonstrated. In parallel, we also report the design and use of an alternative inducible system in M. xanthus based on the vanillate-inducible system, first developed for Caulobacter crescentus (40) and, very recently, employed in mammalian cells and mice (11). We show that the IPTG-and vanillate-inducible systems can both generate M. xanthus strains that conditionally express several essential genes, including ftsZ, which is required, as mentioned earlier, at high levels in vivo, and can also be used to study genes involved in M. xanthus development.…”

Engineering Gene Circuits for Mammalian Cell–Based Applications

“…Because the ligandbinding domain is part of the protein, the binding of the ligand to the regulator dimer leads to the dissociation of the operator-dimer complex, thus influencing gene-expression rates. Based on this design strategy, mammalian cells have been engineered with various synthetic systems to sense different ligand inputs (e.g., antibiotics, Gossen and Bujard 1992;Fussenegger et al 2000;Urlinger et al 2000;Weber et al 2002Weber et al , 2003and Weber et al 2006Weber et al , 2009Hartenbach et al 2007;Gitzinger et al 2009Gitzinger et al , 2012Kemmer et al 2010;Bacchus et al 2013) and proven to be useful tools for diverse biological applications. Moreover, a synthetic system that enables dual-input gene-expression control was developed using a single engineered prokaryotic regulator protein fused to the transrepressor domain KRAB, termed KRAB-CbaR (Xie et al 2014).…”

“…Encapsulated cells that contain ligand-responsive gene switches have shown the ability to regulate the production of therapeutic proteins in a ligand-dependent manner in mice. Although small molecules that are not found in an organism (e.g., antibiotics, Weber et al 2002;and drugs, Ye et al 2013) they must be invasively administered, gene-control systems based on radio waves (Stanley et al 2012), light (Ye et al 2011;Folcher et al 2014;Kim et al 2015), food additives (Gitzinger et al 2012;Rössger et al 2013b), and skin cream (Gitzinger et al 2009), providing more convenient, noninvasive options to manipulate gene expression. Accordingly, recent work has shown the use of a brain -computer interface to control the illumination of red-light-emitting diodes (LEDs) to control gene expression in living cells (Folcher et al 2014).…”