Curated Optogenetic Publication Database

Abstract: Exogenous insulin therapy is the mainstay treatment for Type-1 diabetes (T1D) caused by insulin deficiency. A fine-tuned insulin supply system is important to maintain the glucose homeostasis. In this study, we present a designed cell system that produces insulin under an AND gate control, which is triggered only in the presence of both high glucose and blue light illumination. The glucose-sensitive GIP promoter induces the expression of GI-Gal4 protein, which forms a complex with LOV-VP16 in the presence of blue light. The GI-Gal4:LOV-VP16 complex then promotes the expression of UAS-promoter-driven insulin. We transfected these components into HEK293T cells, and demonstrated the insulin was secreted under the AND gate control. Furthermore, we showed the capacity of the engineered cells to improve the blood glucose homeostasis through implantation subcutaneously into Type-1 diabetes mice.

Abstract: Programmable transcription factors can enable precise control of gene expression triggered by a chemical inducer or light. To obtain versatile transgene system with combined benefits of a chemical inducer and light inducer, we created various chimeric promoters through the assembly of different copies of the tet operator and Gal4 operator module, which simultaneously responded to a tetracycline-responsive transcription factor and a light-switchable transactivator. The activities of these chimeric promoters can be regulated by tetracycline and blue light synergistically or antagonistically. Further studies of the antagonistic genetic circuit exhibited high spatiotemporal resolution and extremely low leaky expression, which therefore could be used to spatially and stringently control the expression of highly toxic protein Diphtheria toxin A for light regulated gene therapy. When transferring plasmids engineered for the gene switch-driven expression of a firefly luciferase (Fluc) into mice, the Fluc expression levels of the treated animals directly correlated with the tetracycline and light input program. We suggest that dual-input genetic circuits using TET and light that serve as triggers to achieve expression profiles may enable the design of robust therapeutic gene circuits for gene- and cell-based therapies.

Abstract: Several light-regulated genetic circuits have been applied to spatiotemporally control transgene expression in mammalian cells. However, simultaneous regulation of multiple genes using one genetic device by light has not yet been reported. In this study, we engineered a bidirectional expression module based on LightOn system. Our data showed that both reporter genes could be regulated at defined and quantitative levels. Simultaneous regulation of four genes was further achieved in cultured cells and mice. Additionally, we successfully utilized the bidirectional expression module to monitor the expression of a suicide gene, showing potential for photodynamic gene therapy. Collectively, we provide a robust and useful tool to simultaneously control multiple genes expression by light, which will be widely used in biomedical research and biotechnology.

Abstract: Spatiotemporal control of transgene expression in living cells provides new opportunities for the characterization of gene function in complex biological processes. We previously reported a synthetic, light-switchable transgene expression system called LightOn that can be used to control gene expression using blue light. In the present study, we modified the different promoter segments of the light switchable transcription factor GAVPO and the target gene, and assayed their effects on protein expression under dark or light conditions. The results showed that the LightOn system maintained its high on/off ratio under most modifications, but its induction efficiency and background gene expression level can be fine-tuned by modifying the core promoter, the UASG sequence number, the length of the spacer between UASG and the core promoter of the target protein, and the expression level of the GAVPO transcription factor. Thus, the LightOn gene expression system can be adapted to a large range of applications according to the requirements of the background and the induced gene expression.

Abstract: We developed a light-switchable transgene system based on a synthetic, genetically encoded light-switchable transactivator. The transactivator binds promoters upon blue-light exposure and rapidly initiates transcription of target transgenes in mammalian cells and in mice. This transgene system provides a robust and convenient way to spatiotemporally control gene expression and can be used to manipulate many biological processes in living systems with minimal perturbation.