Optochemogenetics (OCG) Allows More Precise Control of Genetic Engineering in Mice with CreER regulators

Abstract

New approaches that allow precise spatiotemporal control of gene expression in model organisms at the single cell level are necessary to better dissect the role of specific genes and cell populations in development, disease and therapy. Here, we describe a new optochemogenetic switch (OCG switch) to control CreER/loxP-mediated recombination via photoactivatable (“caged”) tamoxifen analogues in individual cells in cell culture, organoid culture and in vivo in adult mice. This approach opens opportunities to more fully exploit existing CreER transgenic mouse strains to achieve more precise temporal- and location-specific regulation of genetic events and gene expression.

A Thioacetal Photocage Designed for Dual Release: Application in the Quantitation of Therapeutic Release by Synchronous Reporter Decaging

“…[2] It is based on the temporary inactivation of a biologically active molecule through conjugation with a photocleavable protecting group (photocage) which can be conditionally removed by light exposure to reactivate the molecule (Figure 1). The concept of photocaging has been extensively demonstrated in the control of cellular activities in vitro such as channel gating, [1] protein activation [3] and gene regulation [2, 4] as well as in the development of optogenetic animal models in vivo . [4b, 4c] …”

“…The concept of photocaging has been extensively demonstrated in the control of cellular activities in vitro such as channel gating, [1] protein activation [3] and gene regulation [2, 4] as well as in the development of optogenetic animal models in vivo . [4b, 4c] …”

“…The spatially and temporally-controlled release of both drug and imaging molecules within target cells allows for monitoring of the extent of drug release with a reporter readout in real-time. [11a–d] Of these cages, the ONB cage, which is the most well characterized for its cleavage by one-photon [1] and two-photon [4b, 5a, 6a] absorption, has played a significant role in the advancement of controlled drug release. [2, 13] …”

“…UVA is less toxic to most mammalian cells than shorter UVB and UVC, and thus has served as a tool for active control in chemical biology such as protein activation, [3a, 5a, 15] optogenetics, [4a, 4c, 16] and photochemical internalization of biomacromolecules. [17] More recently, applications of light-controlled mechanisms for drug release [13] have been developed by numerous laboratories including ours in the design of prodrugs and drug delivery systems for various therapeutic agents including olaparib (AZD-2281), [11e] melphalan, [11f] methotrexate, [18] doxorubicin (Dox), [10b, 10c, 19] paclitaxel (taxol), [20] 5-fluorouracil, [21] tamoxifen, [4a, 8, 16] and ciprofloxacin. [22] However, efficient implementation of photocage molecules for such applications [13] is often challenging due in part to the synthetic complexity involved in drug and/or reporter conjugation which requires a multistep process.…”

Light-controlled active release of photocaged ciprofloxacin for lipopolysaccharide-targeted drug delivery using dendrimer conjugates

“…25 These mechanisms are not directly applicable to antibiotic delivery due to their irrelevance to bacterial systems and to the poor uptake of NPs in bacteria. Use of UV light has been well validated for various controlled-release applications including the spatiotemporal control of gene expression in vivo , 26 and tumor targeted drug delivery. 25, 27, 28 Further, light only-based therapies which include photodynamic therapy and UVB (280–315 nm) irradiation are already in use clinically as alternative antibacterial therapies.…”